Table of Content

31 December 2022, Volume 36 Issue 6 Previous Issue    Next Issue

For Selected:

Download Citations EndNote Reference Manager ProCite BibTeX RefWorks

Toggle Thumbnails

Select

Influence Analysis of Shielded Subway Tunnel Excavation Undercrossing an Existing Bridge XU Du 2022, 36 (6):  803-806.  Abstract ( 420 )   Save The Hefei Metro Line No. 4 crosses beneath the Dangtu Road bridge that carrying the new passenger high-speed railway. The passenger volume of Dangtu road rail bridge is large and the railway operation requires a strictive deformation and stress in the bridge. The influences of deformation and stress in the bridge structure are well analyzed by using the MIDAS GTS commercial finite element analysis software in this paper. The results show that the transverse and longitudinal lateral displacements at the bridge pier are less than 3 mm and the vertical settlement of the pier is less than 5 mm. The differential settlement at the pier is less than 5 mm and the change of the additional stress in the bridge structure is very small. Further, the deformation and stress in the structure meet the relevant requirements. To ensure the safety of the bridge during shielded tunnel excavation, the measures for the safe the construction undercrossing the bridge such as, strengthening the reinforcement strength of shielding segment, separating the undercrossing of left and right lines, strengthening the control of the shielded excavation, are also presented in the paper. Related Articles | Metrics

Select

Analysis of an Improved Cross Diaphragm Method in the Baishiguan Tunnel Excavation KANG Bao, BAO Hua, LI Ben 2022, 36 (6):  807-811.  Abstract ( 299 )   Save The excavation method of shallow buried tunnels in the mountain area is an important topic in the civil engineering construction. An improved tunnel excavation that reserving the core area by using Cross Diaphragm (CRD) method was applied in the Baishiguan Tunnel excavation. The main construction aspects of this new method are discussed from the construction principles and key construction steps. The key points of the site construction management are discussed from five aspects: advanced support by using the small diameter pilot pipe, excavation and support, inverted arch filling, temporary support removal, and prediction information feedback. The engineering results show that the improved CRD method has the advantages of optimizing the construction technology, information construction, saving construction schedule and investment. The relevant results can be used as reference for actual engineering project.  Related Articles | Metrics

Select

Application of Double Row Piles in a Deep Excavation Support in Red Clay and Backfills PENG Jingyu, MENG Baohua 2022, 36 (6):  812-815.  Abstract ( 298 )   Save A deep excavation project was located in Guizhou red clay area. The new backfill and red clay deposits are at the backside of supporting soldiers. The depth of deep excavation is about 11.7 m and the double row pile support method were used. The existing theoretical analyses of the deformation do not meet the requirements of the project specifications. As a results, a panel of expert discussion was conducted, the review of the existing design parameters by the structural and geotechnical firms, review of the composition of the backfill material, degree of compaction and age of the backfill material have been performed. A new observational method was used in deep excavation construction. The construction monitoring program was implemented, and the monitored data was used the future construction excavation. Further, the ground anchor to be installed in between the double row piles was used as the emergency remediation approach if the excessive deformation was observed in the supporting structures. The construction monitoring data indicated that the deformation of the deep excavation supporting structure met the design required. The reliability of the new method has been verified and the results can be applied in the excavation support in similar projects. Related Articles | Metrics

Select

Influence of the Surcharge Loads on the Stability of Deep Excavation Supporting Structure WANG Li 2022, 36 (6):  816-819.  Abstract ( 386 )   Save Numerous examples of excavation engineering show that surcharge loads around the excavated have a significant impact on the stability of the supporting structures, and the surcharge loads even become the direct cause of some excavation accidents. Overloading or undercounting near the excavation will bring hidden hazard to the safety of the deep excavation. However, if the surcharge is increased unreasonably in the design stage, it will cause a substantial increase in the construction cost of the excavation engineering, and overloading near the side of the excavation has uncertainty, which is greatly affected by construction conditions, surrounding environmental conditions and analysis methods. Therefore, the overload calculation is a more complicated and very important part in the design of excavation engineering. This article analyzes the stability of the outer protective system from four aspects: the magnitude of the surcharging load value, the width of the overload, the depth of the overload and the distance from the excavation edge, which has certain guiding significance for the design. Related Articles | Metrics

Select

Influence of Utility Culvert Excavation Construction on the Adjacent Subway Viaduct ZHANG Dakuai 2022, 36 (6):  820-824.  Abstract ( 225 )   Save A utility culvert need to be installed near a viaduct of the metro subway structure. The unloading deformation in the viaduct structure induced by the excavation of this utility culvert needs to meet the requirement of the safe operation of the subway. According to past experience, the impact of foundation excavation construction on the surrounding environment is mainly at the excavation stage. Therefore, the strong support form of soldier piles with internal support was adopted in the design of deep excavation near the subway. The three-dimensional finite element modeling method was used to simulate the displacement of the soil and subway viaduct in all directions during the excavation. The calculation and analysis results show that the deformation of the subway viaduct caused by the deep excavation conforms to the general trend. After taking the targeted measures for the deformation control, the utility culvert construction meets the requirements for the subway protection. The research results can provide a reference for the implementation of other similar projects within the influence range of subway. Related Articles | Metrics

Select

Application of Lightweight Foamed Concrete in High Fill Embankment Slope Hazard Mitigations YU Zhilong 2022, 36 (6):  825-828.  Abstract ( 290 )   Save The lightweight foamed concrete has the advantages of light in unit weight, good fluidity, good construction, and has excellent required strength and overall stability. Therefore, it is an efficient way to apply the lightweight foamed concrete to replace and reduce the surficial load in the hazard mitigation of the high fill embankments. Due to improper construction of these high-fill embankments, the potential hazards often endanger the stability of the embankment slope. By using the combination of the deep borehole displacement monitoring and geological survey results, the potential sliding surface is able to be determined and analyzed. The stability verification analysis was performed by using the GEO software. The status sliding body was able to be back analyzed. The inverse analysis based on the required factor of safety by the design code, the inverse sliding body index is used to estimate the depth of lightweight foamed concrete required, so as to ensure the safety and reliability of high-fill embankment. Related Articles | Metrics

Select

Optimized Design and Monitoring of a Deep Excavations Support in Thick Soft Soils CHEN Zhixian, WANG Zhiren 2022, 36 (6):  829-833.  Abstract ( 358 )   Save The deep excavation of an underground pedestrian passageway in Qianhai District of Shenzhen is presented in this paper. The site subsurface soil consists of artificial rockfill and the thick soft silty mucky soil is deposited at the bottom of the proposed excavations. The secant soldier pile with two rows of jet grout as the seepage curtain at the interface of existing and the proposed excavations was used as the excavation supporting structure. Two different approaches were planned in treating the soft soils at the bottom of the proposed excavation: one is to use high pressure jet grout; the other approach is to increase the length of the soldier piles; adjusting the location of internal supports; applying the prestress in the internal strut; and pile supported underground passageway. By using the later approach, an integral system consisting of pilecap and soldier pile supporting structure can be formed. After comparison, the results indicate that later approach is better than the first one in aspects of internal force induced deformation, stability performance and project cost. And the actual monitoring results also show that the performance of secant piles combined with pile foundation in thick silty mucky soils is stable, feasible and economical. Related Articles | Metrics

Select

Impact of the Pipeline Culvert Construction on The Safe Operation of a Rail Transit Tunnel MA Zhenwang 2022, 36 (6):  834-837.  Abstract ( 239 )   Save This paper presents a case history of a new socket-type water supply pipe and sewage pipe long-distance culvert excavation project above the No.1 rail transit line of Nantong City. A three-dimensional finite element model was established based on the relative position relationship and structural characteristics between the pipeline and the tunnel. The influence of culvert excavation mode and the length of excavation culvert section on the deformation and disturbance of the rail transit tunnel was simulated and analyzed. The analytical results show that, compared with the sloped open excavation, steel sheet pile supported vertical excavation for long-distance pipeline culvert can significantly reduce the deformation and the disturbance to the lower active tunnel. The deformation of the lower tunnel increases with the length of excavation culvert section. Space-time effect must be considered in the culvert construction. Fast earthwork excavation and backfilling can shorten the exposure time of culvert. The perched water can be excavated with drainage to avoid the overlap of adverse effects of upper unloading and precipitation on the rail transit tunnel. The evaluation results provide an useful reference for construction design of municipal pipeline adjacent to rail transit. Related Articles | Metrics

Select

Mechanism and Mitigation Measures of Landslides in Northern Fujian Province ZHUANG Shuyu 2022, 36 (6):  838-842.  Abstract ( 312 )   Save Based on the investigation of the geological hazards a slope failure in the north of Fujian Province is systematically evaluated in this paper. The failure mode, formation mechanism as well as the slope stability aspect has been analyzed. Also presented in the paper are some practical and pertinent failure countermeasures. The investigation indicates that the failure of the studied slope is the result of small-scale sliding mode and shallow landslide. In addition, the rock and soil slope bodies, topography of the inter-mountain depression, rainy and stormy climate as well as the human activities (such as excavation) with no support system also play important roles. Specifically, the stability of the slope would decrease remarkably due to the rainfall. The proposed mitigation measures of supporting slope surface by the ground anchor and the frame beam, applying gravity retaining wall for the support in severe collapse area as well as providing the drainage ditch (at the top and the bottom of the slope) and the drainage weep holes (on the slope surface) for the drainage improvement could effectively minimize the landslide related hazards. This paper provides the understanding of the formation mechanism of the geo-hazard of collapse and technical guidance to prevent landslides in the northern Fujian Province.  Related Articles | Metrics

Select

Optimization Design of Pile Foundation Engineering of a Coastal Port Project XIE Liang, YANG Guangyu, LI Chunlei 2022, 36 (6):  843-846.  Abstract ( 250 )   Save The pile foundation of the buildings in the reclaimed land area should not only provide the compressive bearing capacity required by the superstructure, but also provide the uplift bearing capacity to mitigate the buoyancy induced from the seawater when the sea water level rises. Therefore, it is necessary to predict, analyze and optimize the layout of the piles in the foundation project, to coordinate the resistance of the pile foundation, the superstructure and the buoyancy from the anticipated sea level. A pile foundation project in Shenzhen Shekou cruise wharf center is presented as the case history. The pile foundation for the buildings in the reclaimed land area is optimized by adjusting the layout direction of the piles under the column, by adjusting the pile position at the edge of the foundation, also by considering the layout of the superstructure. The simulation analysis is performed by using the MIDAS/GTS finite element software to verify the rationality of the optimization design scheme of the pile foundation project. Related Articles | Metrics

Select

Numerical Study on the Deformation Characteristics of a Deep Circular Deep Excavation in Loess Soils LIU Feipeng, LI Hongxing, XI Wang, ZHANG Xiaolei, 2022, 36 (6):  847-855.  Abstract ( 228 )   Save With the fast development of economic and social progress, human beings urgently need to develop and utilize the underground space. The resulting super-size engineering projects also promote higher requirements for the design theory, construction method and construction management technology of the related underground engineering. In this case, the diaphragm wall has become the first choice for the supporting structure of many deep excavation projects, and the shape characteristics of the diaphragm wall have also developed from the traditional straight line to the form of curved, circular, and other complicated shapes. To promote the research on the deep and large foundation excavation projects, based on an actual engineering project in Xi'an, the PLAXIS 3D is used to simulate under three-dimensional, various subsurface and loading conditions. The feasibility of the three-dimensional finite element software is validated. The deformation characteristics of the deep excavation supporting structure, the change of the lateral earth pressure behind the supporting wall, the internal force in the diaphragm wall and the influence range of the surrounding environment of the deep excavation are evaluated. The deformation criteria of the circular and ultra-deep excavation are proposed. The results indicate that the lateral deformation of the supporting structure of the circular deep excavation is very small, but it demonstrates that the deformation trend of “medium bulging”. Due to the arch effect in the circular supporting structure, the bending moment in the diaphragm wall is small, and the circumferential axial stress is much greater than that of in the radial axial stress. The structure is mainly in compression, which can take the advantage of the high compressive strength of concrete materials. Under such working conditions, the influence range of the circular deep excavation on the surrounding environment is twice as the excavation depth. The deformation of the ultra-deep excavation can be estimated from the excavation depth, excavation diameter and the stiffness of the supporting structure through a fitting coefficient n. The results show that, when the excavation depth is large, the mechanical performance of the circular supporting structure is better and has little impact on the surrounding environment. Its characteristics can be reasonably used to optimize the deep excavation and to improve the monitoring of internal force, deformation and settlement during the construction. Related Articles | Metrics

Select

Construction Method of Double-Arch Tunnel Excavation in Argillaceous Siltstone Strata LIN Zehui, HU Richeng, LI Jiahua 2022, 36 (6):  856-860.  Abstract ( 259 )   Save The double-arch tunnel has the advantages of reducing the spacing between two tunnels, having high space utilization rate, and effectively saving the investment cost, but there are disadvantages such as complicated construction process, potentially disturbance of the surrounding rock, difficult to construct, and long construction schedule. How to optimize the construction sequence, to control the deformation of the surrounding rock, and to ensure the construction quality are the current challenges in the design and construction of double-arch tunnels. This paper presents a case history of a double arch tunnel project of Maozhutang Station Storage Line of Changsha Rail Transit Line 5. The design utilized “five-pilot hole + stepped excavation” method, which could continuously perform the construct operations, effectively shorten the construction period, and thus reduce the construction cost. To explore the influence of the excavation on the stress and ground subsidence of the initial shielded structure, the feasibility and safety of the proposed method are validated by the numerical analysis and the on-site construction monitoring data. This information can provide a reference for the similar projects in the future. Related Articles | Metrics

Select

State of the Art Review of Static and Dynamic Properties and Stress Wave Propagation of Coral Sand CHEN Tao, WU Jianan, MA Linjian, GENG Hansheng, DONG Lu 2022, 36 (6):  861-867.  Abstract ( 299 )   Save Coral sand is a natural medium that is widely distributed in the islands and reefs in South China Sea. With the development of the island engineering in the South China Sea, research on its physical and mechanical properties has become increasingly extensive. Due to the special marine biogenesis and marine sedimentary environment, the macroscopic physical and mechanical behavior is quite different from that of terrigenous sand. Combing the basic physical mechanics and mechanical properties of the coral sand, this paper expounds the coral sand propagation of stress wave attenuation relations and affecting factors. The multi-scale dynamic mechanical behavior of the coral sand and the dynamic constitutive model in the influence of particle breakage in the coral sand are the research area to be strengthened in order to reveal blast wave propagation relations in the three-phase saturated coral sand and to provide the long term stability of the coral islands and reefs in our county. Related Articles | Metrics

Select

Prediction and Mitigation Suggestions of a Large Deformation of a Deeply Embedded Tunnel in Xianshuihe Tectonic Fault Zone WANG Zhewei, LUO Liangcheng, ZHANG Guangze 2022, 36 (6):  868-872.  Abstract ( 214 )   Save A deeply embedded tunnel in the western Sichuan crosses the worldfamous Xianshuihe tectonic fault zone, which has very complicated geological conditions, such as significant elevation differences in topography, extreme climatic conditions, strong plate movement, complicated and dense fault structure, weak and broken rock mass structure, complicated hydrogeology, extremely high ground stress and other adverse environments. Large deformation hazards induced by the soft and weak rock mass in the deeply embedded tunnel remain the most prominent geological engineering challenges faced in the railway construction. The accurate prediction of the large deformation has an important contribution to the tunnel construction. Based on the back analysis results from the 9-borehole in-situ stress tests, three methods were used to predict the large deformation, namely, compressive strength stress ratio method, geological analysis method and surrounding rock characteristic method. Several targeted measures for the treatment of a large deformation tunnel are proposed. The following conclusions can be obtained: (1) the measured maximum lateral principal stress of the tunnel is 42.74MPa at a test depth of 1036.4 meters. The back calculated in-situ stress of the tunnel is between 5 and 45.2 MPa, and the maximum in-situ stress is located at the maximum embedment depth of 1219 meters. (2) The prediction method of “calculating by multiple methods and determining the large deformation grade and section after synthetical analysis” proposed in this paper effectively ensure the objectivity of the predicted results. The grade of deformation mainly results in slight, medium and strong large deformation, the proportion of each part accounts for 21%, 6% and 7%, respectively. (3) Based on the predicted results, targeted support measures are proposed: the mitigation measures for tunnels with different deformation grade are given, as follows: Measures such as bolt support, shotcrete or shotcrete + hanging reinforcement mesh, setting steel arch frame and improving the strength of the shotcrete and so on can be adopted for the slight large deformation. Measures such as set up longitudinal joints in shotcrete layer, shotcrete + hanging reinforcement mesh or shotcrete with steel fiber, shrinkable steel frame and so on can be adopted for medium large deformation. Measures such as strengthening stratum Shotcrete + hanging reinforcement mesh or steel fiber shotcrete, grouting, longitudinal joint in shotcrete layer, shrinkable steel arch, long anchor bolt and so on can be adopted for strong large deformation. (4) The above research results can provide reference for the large deformation prediction and mitigation in complicated tectonic structural zone. Related Articles | Metrics

Select

Influence of Deep Excavation Soldier Pile Stiffness on the Stability of Slope above Pile Head  XU Shuping, HU Xiangyu, CHEN Min, HU Fuhong 2022, 36 (6):  873-876.  Abstract ( 322 )   Save In the design of the deep excavation support, the bored cast-in-place reinforced concrete piles with slope are frequently used to facilitate the construction schedule and to reduce project cost. Different from the natural soil slope, the process of the foundation excavation is the removal of the existing soil, and there is a stress release process. The stability is lower than the corresponding natural soil slope with similar slope angle. At the same time, the displacement of the pile head also has a negative impact on the stability of the slope above the pile. The finite element software ABAQUS was used to simulate the stress release process during excavation. The slope stability was investigated by adjusting the bending stiffness EI of the support pile and by using the strength reduction method. The analytical results show that the stability of the slope above the pile head is proportional to the stiffness of the supporting soldier pile and the lateral deflection of the pile head. Related Articles | Metrics

Select

Influence of an Ultra-Deep Excavation on the Adjacent Subway Tunnel RAO Yundong, ZHOU Yong, FENG Zhongwen 2022, 36 (6):  877-883.  Abstract ( 288 )   Save The super headquarters project of Shenzhen Evergrande center is located in the coastal soft soil area. It is also adjacent to a double-line shielded tunnel in the north with complicated surrounding construction conditions and therefore, the deep excavation construction has restrictive requirements for the deformation control. In order to study the impact of the ultra-deep excavation on the surrounding environment, a numerical analysis model of the adjacent subway side section is established with plaxis2D finite element software. The Hardening Soil with Small Strain (HSS) constitutive model and Mohr Coulomb (MC) elastic-plastic constitutive model are used in the analysis. The ground subsidence adjacent to the excavation, the deep horizontal displacement of the supporting structure, the soil layer deformation and the stress and deformation relations of the subway tunnel structure during the excavation of the foundation pit are evaluated. At the same time, based on the deformation control requirements, the application effect of the servo system on the deformation control of structures surrounding the deep excavation is analyzed under the three different supporting conditions; namely, conventional support, prestressed support without servo and prestressed support with servo. The analysis results indicate that the peak value of the ground subsidence adjacent to the excavation is concentrated at 0.2~0.3H (H is the excavation depth), and the peak value of the deep horizontal displacement of the supporting structure is concentrated at 0.6~0.7H after excavation, the main influence range on the subway tunnel structure is within 0.5H. Compared with the traditional supporting method, the prestressed servo support structure can effectively reduce the ground subsidence adjacent to the excavation, the displacement of the supporting structure. The new structure can also effectively control the stress and deformation of the tunnel structure, ensure the operation safety of the adjacent subway tunnel. Related Articles | Metrics

Select

Dewatering Design for a Subway Deep Excavation in an Ancient Riverbed beneath the First Terrace of Yangtze River in Wuhan XU Chengbin 2022, 36 (6):  884-889.  Abstract ( 417 )   Save With the rapid development of the urban subway network, the number of commercial and residential buildings around the subway increases sharply. During the excavation of foundations, it is necessary to consider the safeguard measures of the adjacent active subway. The critical aspect of the deep excavation project of the first terrace of Yangtze River in Wuhan area is to prevent the adverse impact on the project itself and the environment caused by the seepage damage of the confined aquifer of the deep sand layer with high water head and strong permeability. The selection of the groundwater control method in the deep excavation can be divided into two modes: “bottom insertion curtain” and “suspended curtain”. The project cost, construction duration, construction difficulty and environmental impact of these two seepage minimization methods are significantly different. A case history of the dewatering treatment of a deep excavation adjacent to an active subway in the ancient riverbed beneath the first terrace of Yangtze River in Wuhan area is presented in this paper. A three-dimensional numerical model with four different curtain insertion depths is established to simulate the construction effect. The optimal curtain construction method and depth of the seepage is selected by considering construction method, cost, construction difficulty as well as its disturbance impact and construction duration in order to reduce the adverse impact of the dewatering on the surrounding environment. The monitoring results show that the simulated values are generally consistent with the measured values. The impact of the excavation dewatering on the adjacent active subway tunnel can meet the safe operation requirements. Related Articles | Metrics

Select

Influence of Water Level Change on the Seepage Characteristics and Stability of an Embankment Slope Along the Lake YAN Hui, ZHANG Chenyang 2022, 36 (6):  890-893.  Abstract ( 255 )   Save With the rapid development of Highway Engineering in China, the slope instability of the embankment along the lake has become increasingly prominent. In this paper, the PLAXIS finite element analysis software is used to establish a two-dimensional plane strain analysis model, considering the influence of different water level rise and fall speed on the seepage characteristics and the stability of the embankment slope along the lake. The results show that: in the rising stage of water level, the infiltration line in the slope is concave, the seepage rate in the slope increases first and then decreases, and the slope stability coefficient decreases first and then increases; in the falling stage, the infiltration line in the slope is convex, the seepage rate in the slope increases first and then decreases, and the stability coefficient decreases first and then increases slightly. Thus, the change law of seepage characteristics and stability of Yanhu embankment slope under the condition of water level change is obtained, which can provide reference for the protection design of similar slope engineering in the future. Related Articles | Metrics

Select

Excavation Bottom Rebound Deformation Control of a Utility Culvert Excavation in Soft Soils NIU Jiawei, GUO Rui, TAN Wentao, LU Chao, CHEN Kongyang, ZHOU Zhenhai 2022, 36 (6):  894-898.  Abstract ( 332 )   Save The foundation excavation area for the cable utility culvert has the characteristics of long and narrow, which is easy to induce excessive rebound deformation at the bottom of the excavation in soft soils and further adversely affect the project construction quality. Therefore, it was necessary to improv the bottom of the excavation by using high pressure jet grout method. The commercial ABAQUS software was used to study the influence of improvement depth, replacement ratio, properties of foundation soil and embedded depth of supporting soldier pile structure on rebound deformation at the excavation bottom. The results show that increasing the depth of improvement and the replacement ratio of the improvement area are effective measures to reduce the rebound deformation at the bottom of the excavation. However, when the improvement reaches a critical depth, the rebound reduction effect becomes not obvious, even if continue to increase the improvement depth. The improvement depth is more suitable between 4m and 8m for the cable utility culvert project. The deeper the embedded depth of the supporting soldier pile structure or the higher the strength parameter of the foundation soil, the smaller the rebound deformation of the bottom of the excavation. However, with the increase of improvement depth, both factors have less influence on the bottom rebound deformation. Related Articles | Metrics

Select

Graphical Analysis of Karst Morphological Characteristics and Exploratory Drilling Interaction HE Mingzhu 2022, 36 (6):  899-902.  Abstract ( 265 )   Save Geotechnical engineering investigation adopts results obtained from the small-diameter (≤100mm) exploratory sampling and in-situ testing to guide the design and construction of the production cast-in-situ piles. In a project practice in the coastal deeply deposited karst terrain site, even the “one exploratory borehole for one pile” method was adopted, the deviation rate with the large-diameter production pile drilling (≥800mm) construction still exceeds 20%, which made the effect from the exploratory pilot borehole reduced significantly. This paper uses the analogy method to explain the drilling effect under the complicated karst characteristics. The graphical analysis is made to illustrate the interaction between the rock mass characteristics and the production drilling. Three types of trajectory models for the drilling in the rock mass are proposed; namely, no-deviation; single deviation and multiple deviations. Factors that might induce these deviations are also discussed in the paper. The objective of this paper is to explore the essential aspects of the drilling, to enrich the basic theory of geotechnical exploration, to improve the understanding of the geotechnical exploration work by all involved parties, and to make recommendations of the technical management in Karst terrain for all involved parties. Related Articles | Metrics

Select

Procedures and Application of Foreign Geotechnical Engineering Investigation Projects WANG Zhitao, ZHU Xiaodan, HU Kongfei, ZHANG Congbao 2022, 36 (6):  903-906.  Abstract ( 911 )   Save Compared with the normal geotechnical practice in China, the procedures overseas might be significantly different. As a comparative example, a case history of the geotechnical investigation of a coal burning power plant in Indonesia is presented in this paper. The full geotechnical investigation procedures from the aspects management, standards as well as specifications, equipment, in-situ test methods, data interpretation and preparation of the investigation report are analyzed and summarized. Three conceptual procedures are suggested for the overseas soil investigation projects. The conventional standard penetration test equipment and static cone penetration equipment used in domestic and abroad are especially compared. From the geotechnical report perspective, the domestic and foreign procedures are also introduced. Five suggestions of how to conduct overseas geotechnical engineering investigation project in the project management and the technical procedures are proposed in the paper. The results of this paper can provide a reference for similar foreign geotechnical engineering investigation projects in the future. Related Articles | Metrics

Select

Prediction of Soil Compression Coefficient by Genetic Algorithm Optimized BP Neural Network OUYANG Lei, DENG Xiping, HE Lijun, LIU Jiayin, CHEN Peng 2022, 36 (6):  907-910.  Abstract ( 404 )   Save The larger the soil compression coefficient, the higher the compressibility of the soil. Excessive compressibility of the soil is likely to cause geological hazards and cause irreversible losses. Predicting the soil compression coefficient has far-reaching significance for the prevention and minimization of geological hazards. Based on the principles of the BP neural network, with conventional physical parameters as input vector and compression coefficient as output vector, the use of the BP neural network with a strong nonlinear mapping ability and genetic algorithm can solve the problem of the BP neural network easily falling into the local optimal value. Based on constructing a compression coefficient prediction model by using the BP neural network, the genetic algorithm is used to optimize the model. After the optimization, the prediction performance is greatly improved. The maximum relative error and the minimum relative error are 22.38% and 1.13%, respectively. In engineering terms, an error within 25% is an acceptable range, so the prediction model can be used as an alternative tool to predict the compression factor to a certain extent. Related Articles | Metrics

Select

Comparison and Optimization of Shallow Foundation Excavation Supports in Thick Marine Soft Soils GAO Zhanxiang, XU Yanqing, XIANG Shuai, HE Pengfei 2022, 36 (6):  911-916.  Abstract ( 333 )   Save The thick marine mucky soil in the Pearl River Delta region is an unconsolidated mucky soil with high moisture content, high compressibility, low shear strength and high organic content, so it is difficult to provide a safe support for the foundation excavations. This paper analyzes the common supporting types of the shallow foundation excavation, namely, sloped open cut, soil nailing wall, steel sheet pile, soil-mixing wall, gravity cement soil retaining wall, etc. These supports have advantages of no internal support, short construction duration, low project cost, and can maximize the self-supporting ability of soil layers. Deformation control is critical to the success of the support. Related Articles | Metrics

Select

Spatial Variation Relations of Engineering Properties of Loess ZHANG Guowei, XIE Xiao 2022, 36 (6):  917-920.  Abstract ( 339 )   Save Soil physical and mechanical parameters are the basis for the design of soil treatment, slope stability analysis and supporting structures, etc. Based on a large amount of drilling and laboratory test data in Chengcheng County of Weibei Loess Plateau, the relationships among the soil compression coefficient, collapsibility coefficient, Atterberg Limits and other physical and mechanical parameters and the depth of the loess are analyzed. Thus, the space variations of the engineering geology characteristics of the loess and correlation among some indicators in the area are studied. The main conclusions can be obtained as follow: the physical and mechanical parameters show different characteristics with the sample depth; the dry density increase significantly with the increase of the sample depth. The collapsibility and the compression coefficient show the opposite trend. The variation of the water content, Atterberg Limits, internal friction angle, and cohesion with the sample depth is not obvious; The void ratio is positively correlated with the compression and collapsibility coefficients. The correlation between the collapsibility coefficient and the void ratio is higher. The correlation between the compression and collapsibility coefficients is more obvious when the compression coefficient of the loess is small. There is no obvious correlation between the collapsibility coefficient and the compression coefficient when the compressibility is large. Related Articles | Metrics

Select

Intelligent Evaluation of Soil Cement Mixing Column Construction Quality GAO Qin 2022, 36 (6):  921-924.  Abstract ( 327 )   Save The quality assurance and control of the soil cement mixing columns are always the critical aspects in the construction management and inspection. Currently, there are two approaches for the QA-QC control: comprehensive monitoring during the installation and integrity tests after the installation. In this paper, the intelligent evaluation system of the construction quality of soil cement mixing columns is developed, and the intelligent evaluation method of soil cement mixing column installation quality is studied based on the soft soil treatment project of an expressway in southern Jiangsu. The results show that the intelligent evaluation system for the soil cement mixing column installation quality can implement the automatic collection, storage, abnormal alarm and remote real-time sharing of the installation data in the entire process of the construction. This system can also be used in remote monitoring of on-site installation and effectively ensure the column quality. The key parameters of the soil cement mixing column installation quality analysis are the column length, the cement content per linear meter and column plumbness. The real-time construction quality evaluation model of the soil cement mixing column is established to objectively and timely feedback for the installation quality of the soil cement mixing column. Related Articles | Metrics

Select

Improved Fuzzy Comprehensive Evaluation Method in Deep Excavation Stability Assessment ZHANG Kai, LIU Tiexin, ZHANG Zhenghu, LIANG Zhengzhao, HAN Ju, ZHAN Bixiong 2022, 36 (6):  925-931.  Abstract ( 420 )   Save The deep excavation monitoring data directly reflect the force and deformation of the geotechnical materials in the corresponding locations. It is of great engineering value and scientific significance to evaluate the overall stability of the deep excavation by considering the variation of the monitoring data of different types and locations. However, the current relevant research lacks systematic quantitative consideration in this regard. Based on this, an improved entropy-weightedhierarchical analysis fuzzy comprehensive evaluation model is proposed, and reference indices are established to evaluate the safety status of the deep excavation construction. The stability of deep excavation projects is studied by considering the monitoring data of different types and locations objectively and holistically from the perspective of weights. By using the difference coefficient, the weights of indicators calculated by the hierarchical analysis and the entropy weighting method are linearly weighted together to enhance the objectivity of determining the weights of indicators and obtain the comprehensive weight value. Meanwhile, the safety status evaluation table of the deep excavation is established by combining the probability of risk occurrence and the degree of accident damage loss. On this basis, the fuzzy comprehensive evaluation is completed to evaluate the stability of deep excavation. A deep excavation project in Shenzhen is presented in this paper as an example to demonstrate the practicality of the method. The study shows that the evaluation method is more objective in assigning the index weights and more detailed in dividing the safety level evaluation indexes. The method can provide quantitative reference and theoretical support for the stability evaluation of deep foundation pit projects. Related Articles | Metrics

Select

Stability Analysis of a Broken Rock Slope Considering Crack Deterioration DENG Guoqing 2022, 36 (6):  932-936.  Abstract ( 327 )   Save The failure of the broken rock slope is usually governed by joints and cracks in the rock mass. The deterioration of the joints and cracks with different degrees induced by artificial activities and rainfall infiltrations has a negative impact on the slope stability. This study is to investigate the failure and stability evolution process caused by the deterioration of joints and cracks based on a broken rock slope in Guangxi Zhuang Autonomous Region. Firstly, the finite element method considering joint and crack networks is used to accurately simulate the distribution of the joints and cracks in the slope. Secondly, the failure evolution process of the slope under the influence of joint and crack degradation is analyzed via the defined degradation coefficient parameter of the strength and stiffness of the joints and cracks. Finally, the slope stability under joint and crack deterioration with different degrees is evaluated, and evolution of the factor of safety and distribution of potential sliding surface is analyzed by combining with the strength reduction method. The research results can provide a reference for the stabilizing treatments of similar rock slopes in other regions. Related Articles | Metrics

Select

Finite Element Analysis of Pile Foundation Failure Modes Caused by Uplifting of Basement#br# CHEN Linping, QIU Zhihua, CHEN Xiuhui, ZHANG Xiongshui, ZENG Wen, 2022, 36 (6):  937-940.  Abstract ( 301 )   Save Insufficient weight of the overburden soil above the basement roof, continuous rainfall and the blockage of the drainage well usually lead to the uplifting movement of the basement. The field investigation indicated that the uplifting caused cracks at the sidewall, roof and other locations of the basement. By installing drainage wells and basement floor pressure release holes, the basement uplift movement was greatly alleviated. However, the damage caused is irreversible, especially the integrity of the pile foundation is unknown. To explore the basement uplift movement induced pile foundation integrity and failure modes, the commercial finite element analysis software ABUQUS is used to conduct the numerical simulation of the basement movement. The results show that, after the basement movement, the bonding between the pipe pile and the backfill core is damaged. Subsequently, the pipe pile settles slightly under the gravity, and the displacement of the core increases with the pile cap and the bottom plate under the buoyancy. Therefore, the problem of basement uplift movement should be paid attention to, and the damage caused by the basement uplift movement to underground projects should not be ignored. Related Articles | Metrics

Select

Application of Cross-hole Seismic Tomography Method in Sinkhole Hazard Investigations in Karst Terrain WANG Zhiqiang, GUO Lei 2022, 36 (6):  941-945.  Abstract ( 345 )   Save With the increasing utilization of the urban underground space, the karst sinkhole hazards caused by the human activities including engineering activities are becoming more and more frequent. Both soil and rock cavities in the karst terrain are developed underground and their evolution mechanisms are complicated, so it is difficult to detect their evolution mechanisms and degree of development by conventional methods. To reduce the threat of karstic collapse hazards to human life and property loss, a well-developed karst terrain in Shenzhen City was used as an example. A two-dimensional section of karst exploration results was obtained by the cross-hole seismic tomography method, which is visually demonstrated the spatial location and morphology of soil and rock cavities. The tomography results also improved the visualization of interpreted results. The test results identified the distribution range and development pattern of soil and rock cavities and rock pinnacles in the area, and these results were validated with the test boring drilling results. Based on the results of the field investigation combined with the regional geological data, the causes of strong karst development in the area are analyzed and emergency management measures are proposed in the paper. The results also provide background data for the minimization and control of the karst collapse in the city. Related Articles | Metrics

Select

DEM Analysis of the Deformation Characteristics of a Highway Landslide in Mountain Area Induced by Multiple Factors FANG Liuyang, LIU Tianyi, CHEN He, PAN Yuanyang, ZHAO Xin, YE Xian, WANG Hai 2022, 36 (6):  946-951.  Abstract ( 311 )   Save To investigate the deformation characteristics of a highway landslides in the mountain area induced by multiple factors, the DEM numerical method with the advantages of simulating large deformation and failure process was established. The rainfall and earthquake induced effects were characterized by the strength reduction and application of full course seismic time history. The deformation process of the Yanyang Village landslide located in the highway from Shangri-La to Lijiang was also simulated. The deformation characteristics were analyzed under the condition of rainfall and earthquake. The results demonstrate that there are no signs of large-scale deformation failure and deep-seated sliding presented at the Yanyang Village landslide, except for the local and surficial deformation, which are in good agreement with the actual deformation features observed. The deformation is more concentrated and larger under the condition of rainfall than that under the condition of earthquake. The numerical results not only can be used to provide the theoretical support for the Yanyang Village landslide, and also can be used to provide a reference for landslides with the similar geological conditions. Related Articles | Metrics

Select

Numerical Analysis of Thermal Transfer of Coal Fire Distribution in Unfilled Abandon Mine Underlying an Expressway WANG Caibo, LI Dezeng 2022, 36 (6):  952-955.  Abstract ( 241 )   Save In this study, the spontaneous combustion of a coal seam under the subgrade of the high fill highway embankment is taken as the background.  The coal seam spontaneous combustion and stratum lithology changes on both sides of the roadway embankment are investigated by the method of borehole temperature measurement. Based on borehole investigation on both sides of the roadbed, the monitoring data of formation temperature and the rock formation variations were obtained. After the statistical analysis, the burning area, the burning depth and the burning intensity of the coal seam at the lower part of the roadbed are determined. The coal seam combustion heat source in the unfilled abandoned mine gallery is located at a depth of approximately 50 meters below the ground. The temperature distribution along the vertical borehole is parabolic. The temperature can be divided into four areas from the surface downward: the normal temperature area of the surface subgrade; the abnormal temperature area of the general rock formation; the abnormal temperature area of the coal rock formation; and the deep normal temperature area. The thermal insulation and sealing performance of lime-loess mixture in the subgrade filling in the coal field fire area was verified. The detection results showed that there was no abnormally high temperature above 200 ℃ in the subgrade, which proved that the lime-loess mixture subgrade has a good sealing effect on the surface and thermal insulation. Related Articles | Metrics

Select

Comparative Strength Tests on the Transparent Synthetic Sand and the Standard Quartz Sand WANG Xing, WU Jianjia, LI Conglei, LI Bendong 2022, 36 (6):  956-962.  Abstract ( 370 )   Save This paper presents the comparative study between the synthetic transparent sand samples and the natural standard quartz sand samples throughout a series of direct shear tests. The characters mainly include the internal friction angle, the cohesion value and the stress-strain curve. Throughout the comparative study, it is concluded that there are some differences between the two sands, for instance, the internal friction angle of the synthetic transparent sand sample is larger than that of the standard quartz sand sample by 5.3°. The shear strength value is larger than the standard sand by 9.8kPa. To prepare a synthetic transparent sand sample that has similar direct shear parameters with that of natural standard quartz sand, studies on the test results from single grain size samples of both sand samples concluded that the internal friction angle increases with the increase of sample grain size; while the grain size of the sand sample is between 0.1 and 0.25 mm, the internal friction angle of the synthetic transparent sand is greater than that of standard quartz sand; However, when the sand sample has a grain size between 1.0 and 2.0 mm, the internal friction angle of synthetic transparent sand is smaller than that of the quartz sand. Based on the test results, the synthetic transparent sand with different gradation can have the same direct shear parameters with the natural standard quartz sand. Related Articles | Metrics

Select

Application of Periodical Calibrations in Geotechnical Testing Equipment WANG Zhanmei, ZENG Ping, BAI Xinchun 2022, 36 (6):  963-968.  Abstract ( 297 )   Save With the rapid development of the engineering construction technology in China, the geotechnical laboratory is required not only to provide more data, but also to have high accuracy of laboratory testing data. Therefore, it is very important to conduct periodical calibrations on the testing procedures, frequently used. easily damaged and constantly unstable equipment. The triaxial testing and the direct shear test devices in the geotechnical tests belong to this type of equipment. The method of periodical calibration of the frequently used equipment is to compare the value of another equipment or several equipment with the same accuracy level. The quality and the representativeness of the standard samples determine the objective accuracy of the geotechnical test data. Therefore, the preparation of the standard samples is an important link that cannot be ignored in the geotechnical test. This paper proposes to use the compaction method to prepare standard samples and select statistical methods to process the comparative test data, to improve the accuracy and reliability of the testing data. Related Articles | Metrics

Select

Disadvantage Aspects and Improvement of a Conventional Density Test Device During the Bedrock Grouting of a Dam Foundation LI Jingya, ZENG Lingqian 2022, 36 (6):  969-971.  Abstract ( 199 )   Save Throughout the study and analysis of the measurement principle of a differential pressure density test device and combined with the investigation and study of the working condition of this device in the bedrock grouting site, the error source of the differential pressure density test results and the structural defects of the device in the grouting process were evaluated. The following conclusions are obtained: the conventional differential pressure density test device is directly connected to the main grouting pipe in the test process, which is affected by the fluctuation of the grouting pressure as well as the flow rate of the grout in the grouting pipe, resulting in a large measurement error and the waste of the cement grout. According to the above disadvantages analysis, the density test device can be improved by removal the test device from grouting pipe through the diverter valve and then parallel connecting to the main grouting pipe. By doing this can largely avoid the unstable environment induced by the main grouting pipe and effectively reduce the grouting density testing error. Related Articles | Metrics

Select

Undrained Shear strength Parameters for Residual Granitic Soil Samples Under Different Test Conditions WU Guoying, PAN Shenggui, ZHENG Weijun 2022, 36 (6):  972-976.  Abstract ( 477 )   Save In order to compare the difference in the undrained shear strength parameters of the residual granitic soil samples obtained by different test methods, the undisturbed residual granitic soil samples from an offshore wind farm in Putian, Fujian Province were performed with the laboratory unconsolidated undrained direct shear tests, the consolidated undrained shear tests, the unconsolidated-undrained (UU) triaxial compression tests, the consolidated-undrained (CU) triaxial compression tests. The objective of these tests was to study undrained shear strength parameters obtained from different test methods. The results show that the consolidation has a significant effect on the undrained shear strength. The cohesion c and the internal friction angle φ obtained by the sample sheared after consolidation are greater than those under the unconsolidated condition; the sample depth has a great effect on the cohesion c measured by the direct shear tests and UU tests; the internal friction angle φcu and the effective internal friction angle φ'cu of the CU tests increase with the increase of the sample depth, and the effective cohesion φ'cu decreases with the increase of the sample depth; the cohesion c obtained by the direct shear tests with the same depth and consolidation conditions is smaller than the triaxial tests, and φ is much larger than the triaxial tests. Related Articles | Metrics

Select

Mechanical Properties and Microscopic Mechanism of Rice Husk Ash-Cement Improved Mucky Soft Soils YANG Xing, Fang Yanan, LIU Juqiang, ZHANG Xin, YUE Yuwei 2022, 36 (6):  977-979.  Abstract ( 446 )   Save The paper presents the use of the rice husk ash and the cement to improve the mucky soft soils. The compactive properties, the unconfined compressive strength, the consolidation properties and the micromorphology of the rice husk ash and the cement treated soft soil samples under different curing ages were systematically studied. The results show that, compared with the untreated mucky soft soil samples, the optimal moisture content of the rice husk ash and the cement treated soil samples increases and the maximum dry density decreases. The strength of the treated soil samples is much greater than that of the untreated samples and the treated soil samples have good curing effect and good compression performance. When cured for 28 days, the cementing system of the rice husk ash-cement treated soil samples is mature, and the soil sample is cemented by the hydrated calcium silicate gel. The soil compactive behavior is improved, and the strength of the rice husk ash soil-cement treated soil samples is also improved. Related Articles | Metrics

Select

Evaluation of the Uncertainty in Determining the Chloride Content in the Leached Liquid from Soil Samples YANG Yiyu, SHI Hong, DONG Jiqing, TAN Ying, LI Tao 2022, 36 (6):  980-984.  Abstract ( 234 )   Save The uncertainty in determination the chloride content in the leached liquid from clay, silty clay and silty soil samples is analyzed and quantified in this paper. The chloride content determination method in “Standard for geotechnical testing method” (GB/T 50123-2019) is used to evaluate the uncertainty. The results showed that the expanded uncertainty of the clay soil extract sample with the chloride content of 124.25 mg/kg was 0.075 mg/kg, the silty clay soil extract sample with the chloride content of 81.65 mg/kg was 0.05 mg/kg and the silt soil extract sample with chloride content of 81.65 mg/kg was 0.075 mg/kg. Meanwhile, factors that influence all uncertainty components of different soil samples are the same. The most contribution of the uncertainty was the volume of the silver nitrate in titration. Then, is the uncertainty from the induced repeatability of the measurement and is followed by the volume of the leached liquid from the soil samples. Related Articles | Metrics

Select

Analysis of Thermal Conductivity Change and Influencing Factors of Frozen Soil under Freeze-thaw Action in Changchun CHEN Lulu, PANG Bo 2022, 36 (6):  985-987.  Abstract ( 284 )   Save The thermal conductivity of the soil is an important index for developing the shallow geothermal energy, the accuracy of its numerical value has a great influence on the utilization efficiency of the ground source heat pump. The freeze-thaw action has also the influence on the thermal conductivity of frozen soil in the seasonal frozen soil region. The study on the variation of the geothermal energy has a good reference value for the utilization of the shallow geothermal energy in the seasonal frozen soil region. This paper introduces some basic characteristics of the frozen soil in Changchun area. By analyzing the mechanism of the variation of the thermal conductivity of the frozen soil and combining the relevant experimental data, the basic characteristics that the thermal conductivity of the frozen soil will gradually decrease under the freeze-thaw action are finally determined. Based on the experimental results, the main factors that affecting the thermal conductivity of the frozen soil are determined by the moisture content, plasticity index and void ratio. The main factors that affecting the thermal conductivity of the frozen soil are preliminarily determined. According to the characteristics of the seasonal frozen soil in Changchun area, some reasonable suggestions on the use of the ground-source heat pump in this area are also proposed. Related Articles | Metrics

Select

Laboratory Study on the Solidifying of Wasted Soil from Deep Excavation for a Roadway Construction ZHANG Tingting, TAO Li, LI Jianhua, NI Dingyu, GAO Shihu, LI Bingyi 2022, 36 (6):  988-991.  Abstract ( 200 )   Save As a ground treatment technology, the soil solidification method has been widely used in the road and the embankment construction. In this study, the small-scale direct shear tests, the unconfined compression tests and the CBR tests were carried out on the cured waste soil mixed with different agents. The results showed that the strength of all solidified soil samples increased with the increase of age, and the soil strength strengthened with the KZJ-F type agent increased most rapidly. Field tests were also performed in this study. The KZJ-F type agent was used to treat the in-situ soil, and vane plate shear tests and plate loading tests were performed at different depths. The results show that the shear strength of the solidified soil was greater than than 150kpa at all depths, and the ultimate bearing capacity was greater than 350kpa at the age of 7d to 28d, which fully met the engineering requirements. Related Articles | Metrics

Select

Statistical and Correlation Analysis of Physical and Mechanical Indexes of Dongguan Coastal Soft Clay ZHOU Shudong, HUANG Jinsheng, ZHANG Tongwei, ZHANG Yi, ZHANG Guibao 2022, 36 (6):  992-996.  Abstract ( 243 )   Save The physical and mechanical indices of the soft clay are the basics for the ground treatment and the engineering construction. The differences in the soft clay sedimentary environment at different areas will lead to the strong regional characteristics of the physical and mechanical indices. In this study, the Dongguan coastal soft clay was taken as a study object and the test results of nearly 450 groups of soft clay samples from the municipal road investigations were collected and analyzed by the mathematical statistics method. The correlations between the water content and the other physical and mechanical indices were also studied. The results show that the Dongguan coastal soft clay samples have the characteristics of high moisture content, high void ratio, high compressibility, and low shear strength. The frequency distribution of the consolidated undrained shear strength indices are relatively uniform, but the frequency distribution of the other physical and mechanical indices are concentrated and do not conform to the normal distribution pattern. The misture content has significant influence on the physical indices such as dry density, void ratio, liquid limit, plastic limit and compression coefficient. Compared with the direct undrained shear strength indices, the consolidated undrained shear strength indices have a greater correlation with the water content. Related Articles | Metrics

Select

Construction Monitoring of Deep Excavation Response Supported by SMW Method Columns in Thick Silty Clay Soils LIU Hongwei 2022, 36 (6):  997-1001.  Abstract ( 376 )   Save The underground rail transit has become an important infrastructure project type to solve the urban congestion and to form one of the major urban contexts. The deep excavation process often induces soil stratum deformation, which in turn might adversely affect the surrounding environment. This paper presents the case history of the Baidang South Station of Suzhou Metro deep excavation response supported by Soil Mixing Wall (SMW) columns. A typical section was selected to conduct that real-time monitoring data analysis on the axial force of the inner support, the vertical/horizontal displacement of the top of the retaining wall, the horizontal displacement of the retaining wall, the groundwater level and the ground surface subsidence. The results indicate that: 1) The supporting axial force in the supporting structure showed an overall increasing trend during the excavation process, and the supporting force would gradually transfer to the lower portion of the structure; 2) The top of the retaining wall showed a trend of horizontal displacement towards to direction of excavation, and with the deep excavation was becoming more and more pronounced. With the deeper excavation, the stress state inside and outside the excavated area changes, and the soil at the bottom of the excavation heaves, causing the retaining wall to show an overall uplift trend; 3) During the deeper excavation, the retaining wall shows a swelled belly shape, and with the excavation, the position of the maximum horizontal displacement of the retaining wall gradually moved down to the vicinity of the excavated bottom; 4) The surface settlement values of the most measuring points continue to accumulate, and gradually become flat after the completion of the excavation, and the maximum surface settlement is about 0.16% of the depth of the excavation, indicating that the SMW method column has a good applicability in deep excavation supporting in the thick silty clay soils. Related Articles | Metrics

Select

Experimental Study on the Mechanical Characteristics of the Saturated Silty Fine Sand Reinforced by the GS Solidification Agent DING Yanping, ZENG Hongbo, TU Jinguang, ZHANG Yiming, LI Jiangkun 2022, 36 (6):  1002-1005.  Abstract ( 433 )   Save The saturated silty fine sand soils encountered in the engineering projects usually has low bearing capacity and poor stability, so it needs to be strengthened to increase the engineering properties. In this paper, experimental studies on the mechanical properties of the saturated silty fine sand soil reinforced by the GS solidification agent are performed. The comparative studies used the cement as the solidification agent as the reference group, the mechanical properties, such as, unconfined compressive strength tests, direct shear tests and scanning electron microscope studies, are conducted to study the mechanical properties of solidified sand with different curing ages and mixing content of the solidification agent from both macro and micro perspectives. The results show that the compressive strength and shear strength of saturated silty fine sand improved by the GS solidification agent strengthen with the increase of curing age and solidification agent content. The increase of macro mechanical strength of the solidified sand is due to the enhancement of microstructure cementation integrity. Compared with the cement solidified sand, the GS solidified sand has higher strength and longer strength growth duration. These research findings can provide the theoretical and experimental basis for the practical application of GS solidification agent. Related Articles | Metrics

Select

Stability Analysis, Cut and Construction Monitoring Design of a High Slope LI Zhaoyu 2022, 36 (6):  1006-1012.  Abstract ( 271 )   Save To ensure the safe operation of the high-speed railway, the slope stability between Station DK187+000.00 and DK187+315.00 on the right side of the Chengde South Railway Station of Beijing-Shenyang passenger special line is analyzed as a case history. The slope stability mitigation measures were compared, analyzed. The cut slope deformation during the construction was also monitored. The results show that, under natural conditions, the retaining structure for the slope produced small local slippage, which was mainly concentrated at about 10m from the top of the steep wall, with a thickness of 2 ~ 3m, and mainly accumulated in the middle of the slope body. The deformation tended to be stable when the slope angle reached 33°. Under the condition of the rainfall and the earthquake, the upper part of the slope collapses about 20m away from the top of the slope, and the thickest part reaches 3-5m. The slope deformation mainly accumulated at the foot of the slope, and they tended to be stable when the slope angle reached 28°. Throughout the comparison and selection, the loose slope deposits of the slope were removed, and all the strongly to completely weathered bedrock were removed and supported. The angle of the side slope was controlled in the range of 1V:1H to 1V:1.5H. The platform was set every 8m of the slope height, and the width of the platform was determined to be 2m. The excavation of the lower mountain has some influence on the unloading and deformation of the upper part. Related Articles | Metrics