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30 June 2023, Volume 37 Issue 3 Previous Issue    Next Issue

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Mechanism and Prevention Measures of Rock Fall Hazards LIU Pengfei 2023, 37 (3):  335-338.  Abstract ( 589 )   Save Rockfall is a common geological hazard in mountainous areas. With the construction of power transmission lines in mountainous areas, the rockfall on the upper part of mountain slopes are potentially more and more harmful to the transmission line towers at the middle and lower parts of the slope. In this paper, a 110kV Shuntan Line 97JHJ tower base slope rockfall hazard evaluation is presented. The evaluation applies principles of the Newtonian motion and the energy conservation, the trajectory model of rockfall is established. The Rn and Rt are used as the parameters for predicting the rebound of the rolling rocks, and the slope friction angle is used as the parameters for the evaluation of the rolling and sliding of rockfalls. The distance, speed and kinetic energy of the rockfalls are simulated by the software to analyze the mechanism of the rolling rocks. Following the principles of the prevention first, remediation as supplement, and combination of prevention and remediation, the three measures of the prevention and treatment of rockfalls are compared and analyzed. The actual sitespecific conditions are taken into the consideration and the appropriate protective measures are implemented. This evaluation process can provide reference for the design and construction of similar projects. Related Articles | Metrics

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Analysis of a Hydropower Cutting-Off Wall Grouting Borehole with Origin QIU Shunbing 2023, 37 (3):  339-342.  Abstract ( 224 )   Save The steep deep of the bedrock underneath the Dagangshen Power Station induces a significant challenge for the seepage cut-off wall grouting operation. The tilting requirement for the project has a very restrictive requirement with a maximum tilting angle of 0.5 degrees per 100 meters. This project utilized the software Origin to process the cut-off wall grouting data. The multivariate statistics, numerical analysis, regression analysis and back analysis are performed so that the grouting angle and orientations were closely monitored. The variation of borehole bending and the projected borehole tilting can be presented. The results can be satisfactorily applied in the construction monitoring of the Dagangshen cut-off wall grouting operations. Related Articles | Metrics

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Numerical Analysis of a Large-Scale Deep Excavation in Suzhou Using ABAQUS Software and Construction Monitoring CHEN Kaiyu, YUAN Jinxing, ZHANG Ye, LU Jinghui, WANG Yuexiang 2023, 37 (3):  343-348.  Abstract ( 470 )   Save Nowadays, there are more and more large-scale deep excavation projects in cities, and it is particularly important to monitor and analyze the data of the deep excavation and to study the deformation. Based on an example of a large-scale deep excavation project in Suzhou, the accumulated vertical and horizontal deflections at the pile top and the accumulated settlement of the surrounding ground surface during the excavation process were monitored. The monitored data were compared with the numerical analysis results by using software ABAQUS. The results show that the feasibility of the different excavation supporting methods, such as, three-axis mixed soil-cement column inserted by the PHC pipe piles, bored cast-in-place reinforced concrete piles, inclined jet grouted ground anchors, steel pipe rakers, reinforced concrete strut combined with soil nail wall with shotcretes. The displacement at the pile top of the supporting structure, the groundwater level variation outside the excavated area, the surrounding pipelines, and the actual measured values of the settlement of the building are all less than permitted values. The results of the ABAQUS numerical analysis show that the cumulative vertical displacement value at the pile top is consistent with the actual monitored data. Related Articles | Metrics

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Investigation on Key Construction Installation Issues of SMW in Deep Excavation Supporting in Hongdao Coastal Area CHEN Zhaoliang, ZHENG Jianyi, LI Peng, LV Dongxing, DUAN Chuanqian, LIU Qiang 2023, 37 (3):  349-353.  Abstract ( 196 )   Save The Soil Mixing Wall (SMW) method has the advantages of short construction period, good waterproof, small impact on the surrounding environment and the hot rolled steel beams can be reused. It has been widely used in the deep excavation engineering where, the soft soil is widely distributed, such as Shanghai, Tianjin, Shenzhen and so on. The typical strata at Hongdao area shows that a thick layer of marine soft soil overlies the bedrock. The SMW method has not previously applied in this area. The investigation focuses on the key installation issues of the SMW application in the soft area based on deep excavation engineering in Hongdao coastal soil and rock composite stratum. The paper proposes the corresponding countermeasures to ensure the quality of the SMW column which can provide experience to similar projects and contribute to marine-rock strata deep excavation construction and development of coastal urbans. Related Articles | Metrics

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Comparative Analysis of Sleeve Milling and I-Steel Beam Joints Methods in Diaphragm Wall Installation in Saturated Sandy Layers  HUANG Shuhang 2023, 37 (3):  354-357.  Abstract ( 318 )   Save The Nanhang Xincun Station of Guangzhou rail transit Line No. 12 is in Baiyun District, Guangzhou. The subsurface condition is mainly composed of saturated sandy layers and strongly weathered silty mudstone. There are fault zones, and the karst formations are well-developed, so there are strong requirements for the construction of the supporting structure. The support system of diaphragm wall plus internal support is adopted for the deep excavation project. By comparing the I-steel joint form of the west foundation pit diaphragm wall and the sleeve milling joint form of the east foundation pit diaphragm wall, it is found that the sleeve milling joint process is more suitable for the geology of the saturated sandy layers, and the sleeve milling joint process has the advantages of low construction difficulty, more cost effective and a good waterproof effect. Related Articles | Metrics

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Improved Uplift Resistance Ground Anchor Installation Method in Fill and Saturated Soft Soils JIANG Kai, DENG Yu, MENG Baohua 2023, 37 (3):  358-362.  Abstract ( 220 )   Save Ground anchor, as one of the most important uplift resistance method, has always been the focus of the engineering project research due to its adaptability for a wide range of soils and simple construction installations. However, when adverse geological conditions such as high fill, high water level, soft plastic clay layer etc. are encountered, it is easy to induce adverse effects in the installation of the uplift resistance anchors. Through field in-situ tests, work efficiency analysis, economic analysis and feasibility analysis, compared with the traditional cased drilling method, the high-pressure jet grout method in advance can improve the borehole quality, enhance the bonding strength between rock and soil mass and anchor mass, and enhance the properties of soil layer, which can effectively resolve the problems induced from unfavorable geological conditions to anchor installation. Under the construction of the real-time management and information method, this method can be better applied to the construction of uplift resistance ground anchor in the soft soils. Related Articles | Metrics

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Discussions on Construction Impact of Jacking a Large Cross Section Box Culvert Closely Cross Through an Important Water Supply Pipeline ZHOU Lihong, ZHOU Xinglong 2023, 37 (3):  363-366.  Abstract ( 178 )   Save This paper presents a box culvert jacking project at the exit of a Jinan subway station. The mechanical model of “the influence the box culvert jacking construction on the deformation and stress of the adjacent water supply pipeline” is therefore established. Combined with on-site monitoring, the analysis of the influence of large cross section pipe jacking construction closely passing through a main water supply pipeline in the urban area are also presented in the paper. The following conclusions are obtained: during the construction of the box culvert jacking, the deformation of the existing pipeline is first uplift and then settlement, the deformation in the middle of the existing pipeline is the largest, and the deformation decreases gradually along the axis to both sides. With the increase of the jacking length, the deformation of the existing pipeline is mainly divided into three stages: uplift stage, rapid settlement stage and stabilized settlement stage. The box culvert jacking length of the pipeline in the rapid settlement stage of the project is 15-35m (the pipeline is located at the jacking length of 20m). With the increase of jacking length, the axial and radial stresses of the pipeline increase. When the jacking length is between 15-35m, the pipeline stress increases sharply. Related Articles | Metrics

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Design and Analysis of the Large-Scale Deep Excavation of a Subway Structure in Densely Populated Urban Areas LIU Chen, LI Aiguo, WEN Jianpeng, CHEN Junsheng, LEI Youkun 2023, 37 (3):  367-370.  Abstract ( 206 )   Save This paper presents a case history of a large-scale deep excavation project of the replacement of Luoshengang frozen material storage facility in Luohu District, Shenzhen City, which is in the densely populated urban area. The paper presents the subsurface conditions, reliable construction measures for the supporting structures and the open cut slope for the transportation of the excavated soils. The deep excavation has minimal influence to the adjacent buildings. Related Articles | Metrics

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Evaluation of High Slope Staged Remediations for a Tower of the Power Transmission Line LIU Yong, HE Guangling, XU Xing, LI Xuan 2023, 37 (3):  371-376.  Abstract ( 154 )   Save Due to the limitation of the passage space and the topography, some towers of the power transmission line need to be installed on the slope. With the gradual loading of tower construction, the slope stability will become worse and worse if the slope is not reinforced in time, which will induce a potential safety hazard to the tower and even cause the tower collapse. In addition, the slope remediation is always time consuming. which will greatly affect the timely completion of the power transmission construction project. Based on the Lizheng geotechnical engineering evaluation and analysis software, the staged remediation of the high and steep slope of the tower of a power transmission line has been analyzed by the limit equilibrium method. The analysis results show that selecting reasonable staged remediation method can achieve these goals, such as reasonable arrangement of the power transmission engineering process, saving power transmission construction time and moving the project forward smoothly. Related Articles | Metrics

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Optimization Design of Small Shallow Basement Foundation Excavations in Thick Soft Soils CAO Qiang, MEI Qinghai, CHU Wei, PENG Peng, DAI Ye 2023, 37 (3):  377-381.  Abstract ( 160 )   Save In order to explore a green and economical solution for the small shallow basement excavations in thick soft soils, different types of deep excavation support methods are compared and analyzed in a single story basement foundation excavation project in Hanchuan. An economical and reasonable supporting system is designed by using the soil mixing wall (SMW) method as supporting structure and the soil-cement column reinforcement in the passive zone as the concealed bracing, which solves many problems in the design of the shallow foundation excavations in thick silty layers. In the process of the project implementation, the time history curves at the column top displacement and the surrounding settlement are presented through the real-time monitoring of the horizontal displacement of supporting column top and the surrounding ground settlement. The trend of deformation and settlement is consistent with the design, which proves the rationality of the design scheme. The smooth implementation of this project provides a feasible idea for the economical optimization of similar projects and solves the problem of poor economic efficiency caused by the previous excessive design of shallow small foundation excavations in the soft soil area. Related Articles | Metrics

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Existing Metro Station Settlement Control Due to the Adjacent Deep Excavations LIU Xiu, ZHAO Meng, WEI Bingchao, MENG Yiping, ZHU Jinlong, 2023, 37 (3):  382-386.  Abstract ( 166 )   Save With the urban development, the deep excavations in the densely populated urban areas are increasingly common and ensuring the safety of surrounding buildings in the deep excavation process has become an important premise of engineering projects. Because of this, the large deep excavation project needs more strictive requirements for the construction control in the complex environment. The Hefei North First-Ring Underground Station is a four-floor structure with complicated adjacent building environment, and the safety level is classified as Level I. Considering that there are many buildings around it, the corresponding construction control measures are proposed in this paper. The foundation pit was excavated by layers, in a segmental and balanced way. The excavated areas are supported by the diaphragm wall with five layers of internal struts. The entire excavation process was performed in the strict construction considerations. The monitoring results showed that the tilting rate and the settlement of the buildings which were in the safe and stable state and all of them didn’t exceed the tolerance values. The surrounding buildings were well protected by the corresponding construction measures. Related Articles | Metrics

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Example of Special Environmental Geotechnical Surveys for Contaminated Site Remediation Projects WANG Suqing 2023, 37 (3):  387-390.  Abstract ( 186 )   Save In recent years, with the increase of contaminated site restoration projects, the depth of the contaminated site remediation has also shown an increasing trend, and the deep excavations involved in remediation and treatment have become deeper and deeper. However, the content and depth of the hydrogeological survey carried out during the preliminary environmental survey often do not meet the design and construction requirements of the deep excavation engineering in the later stage of the restoration and treatment. Therefore, there are more and more demands for the special environmental geotechnical surveys for the contaminated site remediation projects. Using the relevant specifications, combined with a specific engineering example in Shanghai, the main work content of the special environmental geotechnical survey for the restoration project of the contaminated site is introduced, the precautions and some problems encountered during the survey work are discussed and analyzed, some reasonable evaluations and suggestions for the project are put forward, some special survey experience are summarized, which can be used as a reference for subsequent special environmental geotechnical surveys for similar contaminated site restoration projects. Related Articles | Metrics

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Analysis of Supporting Structure and Surface Deformation in the Underground Integrated Utility Culvert Excavations WANG Shilu 2023, 37 (3):  391-394.  Abstract ( 312 )   Save A comprehensive underground utility culvert structure in Zhongshan is to be constructed with open-cut and cover excavation method and the soil mixing wall (SMW) constructed columns is used for the supporting structure. In this paper, the field monitoring data and numerical simulation analysis methods are used to analyze the excavation deformation caused by following four factors: column insertion ratio, column diameter, transverse spacing of internal bracing and vertical spacing of internal bracing. The conclusions can be obtained: (1) The formulas for predicting the maximum horizontal displacement and maximum surface settlement of the SMW constructed columns are derived through analysis; (2) The diameter the SWM column is the most significant factor affecting the horizontal displacement and maximum surface settlement of the supporting structure, and the other influencing factors are column insertion ratio, transverse spacing of supports and vertical spacing of supports in order. The horizontal displacement and maximum surface settlement of SMW column are inversely proportional to the insertion ratio and diameter of SMW columns, and directly proportional to the horizontal and vertical spacing of support. Related Articles | Metrics

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Deep and Large Foundation Excavation Monitoring and Numerical Analysis in Hangzhou LI Huihui, LAI Xiaoyong 2023, 37 (3):  395-401.  Abstract ( 158 )   Save With the continuous urbanization, the development of the urban underground space has gradually increased, and the deep excavation projects involved have gradually increased in a deeper and larger direction. This trend requires higher and higher requirements for the excavation supporting system design. This paper presents a deep excavation project in the north of Hangzhou. The paper introduces in detail the characteristics of the foundation excavations and the design of the supporting structures. The PLAXIS finite element numerical software is used to establish a three-dimensional model to simulate the entire process of the excavation construction. The construction monitoring data are compared with the numerical analysis to evaluate the deformation characteristics of the supporting structure. The monitoring data show that the design parameters of this project were reasonably selected and can used for the better control the deformation. By comparing the measured values with the simulated values, the effectiveness of the numerical simulation is therefore verified. Related Articles | Metrics

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Analysis of Explosive Residues in Deep Soft Clay Blasting in Tidal Zone YU Chenhao, XIAO Guangfeng, CHEN Shengkai, QIN Wei, ZHANG Jinrong, PAN Chaohao 2023, 37 (3):  402-405.  Abstract ( 229 )   Save The blasting for the silt squeezing technology uses explosives buried in the silt to explode to form a cavity area and fill the cavities with roadbed materials such as crushed stones to achieve the construction of a highway embankment over the thick soft silty soils. At present, the main explosives used in this blasting process are ammonium ladder explosives and emulsion explosives. This technology is used in areas such as tidal zones. The explosive residues after blasting with ammonium ladder explosives include carcinogens such as nitro and benzene rings, which will spread to the surrounding seawater with the rising and falling tides, which may affect the aquaculture in the surrounding seas. In order to identify the harmful components and distribution rules of the explosive residues in the seawater of the blasting and squeezing process in the tidal zone, the explosives residuals were analyzed with UV-Visible spectrophotometer and LC-MS. The diffusion of explosive residues in water and silt in related tidal zone deep silt layer blasting and silt squeezing projects were detected. After the inspection, it was observed that the toxic substances such as nitro group and benzene ring did exist in the water after the blasting. Related Articles | Metrics

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Stability Analysis of Bored Pile Stabilized Slope Using the Improved Bishop Method DONG Pingting, BU Weifei 2023, 37 (3):  406-409.  Abstract ( 218 )   Save In order to evaluate the use of bored pile for the landslide remediation, the stability of the slope is evaluated by using the Bishop method and considering all the force effects on the factor of safety. In the evaluation, it is assumed that the force among the slides, the direction and the location of the anti slide force are determined so that the analytical model of landslide with the bored piles can be established and then sliding driving force and the factor of safety can therefore be presented. The relationship of factor of safety among the location of the bored piles and magnitude of the sliding driving forces are also discussed in the paper. The numerical results show that the improved Bishop model analysis of the slope stability by the results with the rest of the algorithm is close to show that this method is feasible and applicable. The estimation of sliding driving force and the rest of the algorithm results within 3% error analysis shows that the model in this paper to establish the good accuracy and reasonable design of the bored pile in slope remediation. The central portion of the slope provides an ideal location for the bored pile the stability of the slope, and the factor of safety increases linearly with the resistance. Related Articles | Metrics

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3D Jointed Rock Mass Network Modeling Application Using Python WANG Mingfei 2023, 37 (3):  410-413.  Abstract ( 188 )   Save The joints have a relatively important impact on the physical and mechanical properties of rock mass, but it is often difficult to fully characterize their spatial distribution in the process of field surveys. Therefore, the use of computer-aided methods to simulate the three-dimensional joints network of the rock mass is an effective supplement to the survey results. Based on the research results of predecessors, this paper develops a three-dimensional joints network simulation program of rock mass using Python and generates a three-dimensional joints network model based on the characteristics of a bridge foundation slope rock mass joints, which reflects the impact of Python programming software on rock mass suitability for civil engineering applications. Related Articles | Metrics

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Deformation Characteristics of Surrounding Expansive Rock Mass in a Highway Tunnel Under Humidity Field JIANG Dahuan, WU Tao, ZHANG Wenyu, LIU Changhong 2023, 37 (3):  414-417.  Abstract ( 111 )   Save This paper presents a case history of the study the deformation and failure characteristics of the surrounding expansive rock mass of a highway tunnel under the humidity field. The evaluation combines with the existing humidity field theory, the deformation law of the surrounding expansive rock mass under different rise span ratios and the lateral rock pressure coefficient is studied by the orthogonal test method. The results show that the deformation of the left side is less affected by the rise span ratios in the expansive conditions or not, and the roof settlement is greater than the floor heave when the rise span ratio is 1:4; Under the influence of the lateral rock pressure coefficient, the deformation of two sides of the surrounding rock mass increases with the increase of the stress ratio. When the stress ratio is 1.5 and 0.5, the floor heave will be as much as 4 times higher; When the rise span ratio and stress ratio are small or large, the variation of the roof subsidence in the former can reach about 50% with or without expansive rock mass, and the floor uplift in the latter can reach about 30%. In the two factors, the lateral rock pressure coefficient has a great influence on the deformation of the two sides, and the rise span ratio has a great influence on the deformation of the top and bottom plate. Related Articles | Metrics

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Stability Evaluation of Mined Voids in the Small Coal Mines for the Proposed Engineering Construction Conditions RAN Zhangqing, WANG Liuwen, PAN Xianwei, LI Fanxi 2023, 37 (3):  418-421.  Abstract ( 176 )   Save China’s coal industry has for a long history. The power engineering, highway, railway, water conservancy projects and other structures are inevitably constructed above the coal mines with mine voids. The characteristics of mined voids in the small coal mines, such as, lack of historical mining data, small mining depth, complex distribution and high concealment, have potentially great influence on proposed engineering constructions. Since the current small coal mined void stability analysis method is not mature, the current engineering load critical influence depth method is commonly used to evaluate the stability of the small coal mine site, but the physical significance of the engineering parameters is inconsistent with the various technical specifications. In this paper, the mechanical balance analysis is adopted to derive the formula of load critical influence depth method from the mechanical principles. The physical and mechanical significance of each parameter is clarified. Related Articles | Metrics

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Considerations of Engineering Investigations of Building Sites in Mountain Areas TANG Yangui, YUE Dachang, QIN Chao 2023, 37 (3):  422-425.  Abstract ( 179 )   Save Geological conditions in mountain areas are more complex than in plain areas for the engineering constructions. The geological structure, stratum lithology and engineering slope stability will potentially affect the building foundation types and engineering cost. This paper presents a case history of a building site investigation and treatment in Emeishan City. The following aspects are evaluated: (1) Based on the plane distribution of the fill soil and fault fracture zone, the influence of stratum lithology on the foundation uniformity and foundation type selection are analyzed and evaluated. The corresponding control measures are proposed in the paper. (2) Based on the spatial distribution of the fault fracture zone, the influence on the area stability, site seismic effect, foundation uniformity and foundation type selection are analyzed and evaluated. (3) Based on the survey results, the overall planning and design, slope stability are analyzed and evaluated, and corresponding suggestions on control measures are recommended. Related Articles | Metrics

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Stability Evaluation of Small Coal Mine Goaf Site under Complex Geological Conditions#br# LIU Mingjiang, CHEN Jinhong, 2023, 37 (3):  426-430.  Abstract ( 199 )   Save To analyze the site stability of the small coal mine goaf area, this paper presents a case history evaluation of a newly constructed ash storage yard for a power plant in Guizhou. The site stability is analyzed according to the coal mining mode and final mining time, the natural balance arch height of the roadway roof and the load influence depth under the different surcharge height are estimated. The ground deformation under the surcharge is analyzed combined with the numerical analysis. The results show that the current condition of the proposed site is in a stable state, under the action of subsequent surcharge, the local collapse of the roadway distribution area is more likely. After taking corresponding deformation improvement measures according to the roadway buried depth and surcharge height, the proposed site is suitable for the construction of the ash storage yard, which can be used for a reference in the stability evaluation of similar goaf sites. Related Articles | Metrics

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Numerical Analysis of Tunnel Excavation by Using MIDAS GTS  CHEN Junjun, GAO Kefei, WANG Qingjun, CHEN Junhong 2023, 37 (3):  431-434.  Abstract ( 324 )   Save Under the actual working conditions of a tunnel project in Shulan City, Jilin Province, the construction process of the tunnel is simulated and analyzed by using Midas GTS finite element software. The results show that, with the continuous excavation of the tunnel, the tunnel vault and its overlying rock and soil mass gradually settle. The closer to the vault, the greater the settlement value is. The settlement range of the surface caused by the tunnel excavation is about 10 times of the tunnel span length. The rock and soil mass at the bottom of the tunnel chamber will produce upward uplift displacement during the tunnel excavation, and the maximum uplift position is located at the center of the chamber bottom. The maximum shear force and bending moment of tunnel lining structure in the construction process are located at the arch shoulder and arch crown of the tunnel respectively. The deformation and stress characteristics of this tunnel during construction obtained through simulation analysis can provide a certain reference for similar tunnel engineering design, construction, and preventive measures. Related Articles | Metrics

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Numerical Simulation of Ground Subsidence Induced by a Historical Tunnel YANG Peng, LI Kai 2023, 37 (3):  435-437.  Abstract ( 156 )   Save Ground subsidence hazards are widely occurred in Guanzhong area of Shaanxi province, and most of the ground subsidence events in villages and towns are caused by the residual deformation of historical tunnels left over time. This paper simulates the ground subsidence hazards caused by the excavation of an ancient tunnel in Weinan, Shaanxi Province, and analyzes the strain and displacement characteristics of the historical tunnel area based on the numerical simulation software. The results show that due to the rainwater infiltration, the strength of the soil decreases, and the deformation occurs under the overburden load. The maximum displacement of the tunnel area is 5.62 m, and the surface displacement is 5.00 cm. The vertical displacement was increased to the top, with a maximum displacement of 1.22 cm. The distribution of the plastic area and strain changes are similar, mainly concentrated in the 45 angle range on the left and right sides of the top axis of the tunnel. Related Articles | Metrics

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Change of Ice Lake and Collapse Hazards Evaluation of Chongdui Gully Basin in Nyalam County LI Guanbo, ZHANG Luming 2023, 37 (3):  438-441.  Abstract ( 450 )   Save Two large-scale debris flow hazards broke out in the Chongduipu Basin of Nyalam County in 2002, which were mainly caused by the ice lake break. Through the comparison of the remote sensing images in 2017 and 2001 and data in 1987, it is observed that the area of main ice lakes in the basin has changed greatly in the past 30 years. It is preliminarily analyzed that some ice lakes might break. The results show that the area of Galongcuo has increased by 225% and that of Jialongcuo by 101% in the past 30 years; There is one ice lake in a highest-risk state and one in a high-risk state. According to the analysis of the 1/3 and 1/2 breakout modes of Galongcuo Zhongqi Dike, the breakout discharge is 3954 m3/s and 9340 m3/s, respectively. When the Galongcuo collapses according to the 1/3 mode, after the flood peak reaches the post disaster reconstruction Puluo planned new area of Nyalam County, a 45 m wide site area will be submerged. Once a debris flow is formed, the peak flow will reach 6899 m3·s-1, the mud depth of the debris flow will reach 13 m, the depth of the submerged site will be doubled, and the submerged area will be expanded by 30%. At the same time, it will cause serious damage to the Zhongni highway bridge at the gully mouth. It is suggested that corresponding prevention and control measures should be taken in the planning area of the gully mouth to reduce the harm of ice lake break debris flow. Related Articles | Metrics

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Safety Risk Assessment of Highway Slope Construction Based on Barycenter Theory of Fuzzy Set DAI Feiya 2023, 37 (3):  442-447.  Abstract ( 188 )   Save Highway slope has the characteristics of short construction period and many uncertain risk factors, so it is necessary to perform construction safety hazard assessment. By introducing the Barycenter Theory of fuzzy set into the traditional fuzzy comprehensive evaluation method, a method of slope construction safety hazard assessment based on the Barycenter Theory of fuzzy set is proposed. Firstly, the internal and external factors that affecting the slope stability are selected to construct the risk assessment index system, and the different levels of membership of each index are estimated. Then, the AHP is used to determine the weight of each index. Finally, the risk level of slope safety is determined based on the Barycenter Theory of fuzzy set. The method is applied to the safety risk assessment of a highway slope in Guangxi Province. It is in good agreement with the situation of the slope site, which verifies the applicability and reliability of the proposed method. In addition, in order to illustrate the universality of the proposed method, two other slopes in the area are selected for risk assessment, and the results obtained are also in good agreement with the actual situation of the slope site. Related Articles | Metrics

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Failure Mechanism of Sandstone Anticline Rock Slope in the Three Gorges Reservoir Area Under Slope Toe Deterioration by Using GDEM Software XU Jiancheng, JIANG Wei, QI Zhiyu, WANG Jinxiang 2023, 37 (3):  448-454.  Abstract ( 199 )   Save Under the combined action of water-rock, the physical and mechanical properties of the rock mass at the toe of a anticline rock slope in the Three Gorges Reservoir area are prone to deteriorate, which might affect the stability of the slope. It is particularly important to accurately understand the failure mechanism of the anticline rock slope under the condition of deterioration of the rock mass at the toe of slope. In this paper, the sandstone anticline rock slope in the Three Gorges Reservoir area is presented as a case history. The slope models with different slope angle, rock dip angle and layer thickness are established by using GDEM numerical analysis software. For slopes without toppling deformation before and after toe deterioration, the variation of the maximum principal stress before and after toe deterioration is analyzed. For slopes that are stable before slope deterioration and have toppling deformation after slope deterioration, the deformation evolution process of anticline slope under the condition of the slope deterioration is summarized. Its response characteristics to the slope deterioration are clarified. In addition, the influence of the slope angle, dip angle and layer thickness on the slope deformation is analyzed, and the shape and location characteristics of the fracture surface of the sandstone anticline slope are proved. The angle between the main fracture surface and the plane of the sandstone slope is 20~26, and the boundary between the deteriorated rock mass at the toe of slope and the deformed rock mass at the upper part is taken as the boundary, and the fracture surface is in a near-straight shape upward from the cut-off point. The main failure mode in the anticline slope of sandstone is spalling, toppling and fracture. Related Articles | Metrics

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Study on Safety Risk Analysis and Management of Mining Tunnels Under-Crossing High-Pressure Oil Pipelines WEI Yanchao 2023, 37 (3):  455-458.  Abstract ( 181 )   Save This paper presents a case history of the construction of a mining tunnel. After a full communication with the relevant property owners, the evaluation combined with engineering geological conditions, the existing conditions of oil pipelines, surrounding environment and other factors. This paper decomposes the potential safety risks while drilling and blasting underneath the high-pressure oil pipeline to prepare a detailed risk list and proposes various management and control measures such as status assessment of oil pipelines. The numerical simulation analyses, blasting plan adjustments, advanced geological forecast and monitoring are also performed. The monitoring data during the under-crossing process shows that the risk management and control measures for the under-crossing oil pipelines in this tunnel are practical and feasible, which provides the effective references and targeted suggestions for future similar tunnel constructions. Related Articles | Metrics

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Identification and Evaluation of Rockfall Hazards at Portal of Xingshan Tunnel in Yichang Zhengwan High-Speed Railway Connecting Line CHEN Feng 2023, 37 (3):  459-462.  Abstract ( 258 )   Save The Yichang-Zhengwan high-speed railway connecting line plays an important role to improve the passenger and freight transportation capacity in the Sichuan-Chongqing direction. The potential rockfall hazards at the slope of the Xingshan tunnel portal along the entire route are very developed, which have become a key factor affecting the safe operation of the line. In the view of the above key issues, research on the precise identification and evaluation of rockfall potentials at the portal of Xingshan Tunnel was conducted. Combined with the on-site geological mapping, unmanned aerial vehicle LiDAR topographic survey, unmanned aerial vehicle close-up high-definition photography and 3D solid modeling, the landform, stratum lithology, bedding occurrence, joint fissure development, development characteristics and distribution of potential rockfalls at the high and steep slope at the tunnel portal were identified. Furthermore, three types of typical rockfall failure modes are constructed. The stability analysis and the evaluation of three types of rockfall modes under typical and extreme conditions are performed respectively. Finally, two types of governance measures are proposed. This study provides a reference for the evaluation and treatment of the same type of geological hazards in the future. Related Articles | Metrics

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Study on Soil Improvement Effect by Dynamic Compaction WEI Yao 2023, 37 (3):  463-467.  Abstract ( 208 )   Save The dynamic compaction method is a soil improvement method that lifting a heavy rammer to a certain height, then falls freely, compacting the soil through the contact of the rammer to produce a huge impact force, to improve soils. This method has the characteristics of simple operation, short construction period, simple technology, etc., and it has been widely used domestically as well as abroad. To further study the effect of the dynamic compaction on the soil, a finite element software was used to simulate the construction process of dynamic compaction. Considering the relationship between the compaction rammer and the elastic-plastic constitutive structure of the target soil, the regional changes of vertical displacement, dynamic stress, velocity and soil plasticity were analyzed under different compaction energy. The results are as follows: (1) Under the impact load, the elastic-plastic deformation of the soil mass occurs. The plastic deformation of the soil mass is mainly diffused from the rammer downward at a certain angle, and the distribution is apple-shaped. With the increase of the ramming times, the plastic deformation area also increases gradually. (2) The vertical displacement and dynamic stress in the soil gradually decrease with depth and show an elliptic distribution in space; (3) With the increase of tamping energy, the soil reinforcement effect is better. Related Articles | Metrics

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A New Method of DPM Data Analysis Using Spatiotemporal Smoothing and Its Application to Stratigraphic Identification WANG Xiong, LIU Xiaoxiang 2023, 37 (3):  468-472.  Abstract ( 146 )   Save The accurate identification of stratum properties is very important to ensure the stability of the slope engineering projects. Under some restrictive conditions, the design of the engineered slope may not be able to obtain the soil and rock samples during the investigation, resulting in the division of actual strata varies from different staff, which lack of an objective basis. The soil and rock engineering properties cannot be accurately characterized thus it could affect the design and construction of a stable slope. The testing while drilling method can capture the soil and rock information carried by the drilling process itself, there is a lack of reliable data analysis methods. By using the Drilling Process Monitoring (DPM) method, this paper proposes a new analytical method of test data during drilling process. By smoothing the space and time scale of the drilling speed, it solves the problem of the random fluctuation of the drilling machine dynamic parameters. This paper presents a case history of a cut slope section from Xiaomangyang to Mohan section in Kunmo Expressway in Yunnan Province. The drilling process of the ground anchor is monitored throughout the entire process, and the monitored data are analyzed smoothly in time and space. The relationship between the drilling penetration rate and lithology is established and the soil/rock strata are identified, which provides a reliable basis for the engineered slope design. Related Articles | Metrics

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Influence of Narrow Width Soils Between Deep Excavations in Soft Soils WU Kezheng 2023, 37 (3):  473-476.  Abstract ( 145 )   Save With the development of underground space engineering, the phenomenon of adjacent deep foundation pits is becoming more and more common. Due to the influence of narrow width soil between adjacent deep excavations, the lateral earth pressures on both sides of foundation excavation are asymmetric and it’s difficult to analyze the internal forces and deflections of the excavation support and the effect on the environment based on the classical excavation design theories. The design and practice of an adjacent deep excavations in Shanghai are presented. The numerical analysis method is used to analyze the internal forces and deflections of the excavation support and the effect on the environment based on HS-Small Strain model. The analytical results are compared with the measured data. The results show that the deflections and internal force of supporting structure on the side away from the adjacent excavation will be underestimated and the design on the side near the adjacent excavation is conservative through the traditional symmetrical excavation design method. Besides the deflections of the adjacent excavation and the lateral earth pressure between the excavation become larger while the stiffness of the adjacent excavation becomes smaller. Related Articles | Metrics

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Mechanical Properties of Red Sandstone Before Yielding Under Complex Stress Conditions ZHAO Houfa, NING Lin, Deng Xiaojiang 2023, 37 (3):  477-483.  Abstract ( 157 )   Save To study the energy characteristics of intact rock samples under cyclic loading and unloading conditions and continuous complex stress conditions, the axial cyclic loading and unloading tests on the red sandstone with small values of constant amplitude cycle + amplitude variation (similar to sine wave) was performed to explore the energy variation rule of intact rock samples before yielding under the cyclic loading and unloading. At the same time, the strain stage of the sample was characterized by the energy of cyclic loading and unloading with small value. The test results show that: (1) During the loading and unloading tests, the external input energy is mainly converted into elastic energy storage, and some energy is consumed, that is, the dissipated energy. (2) The change of the proportion of input energy, elastic energy and loss energy is consistent with the strain stage of the sample, and the deformation characteristics and stage of the sample under sustained load can be quantitatively characterized by the change of energy. (3) The energy in the constant amplitude cyclic stage decreases gradually with the increase of stress, and the damage and deformation stage of the specimen can be indirectly assessed by the energy change under the cyclic loading and unloading with a small amplitude. (4) The change of energy consumption ratio at peak stress in each cycle stage is an inflection point at 45 MPa stage, and the change of energy also has a certain “memory”. Related Articles | Metrics

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Influence of Backfill Materials Properties on the Geocell Reinforcement Performance#br# YANG Jihong, LI Jian 2023, 37 (3):  484-487.  Abstract ( 155 )   Save The applicability of cohesive soils as the geocell fill material was investigated using laboratory load-bearing plate tests as the basis for the numerical analysis. The contribution of the geocell and the sand in the geocell-reinforced road base (where the sand is in the geocell backfill material) is also revealed by estimating the working condition of the sand replacement. The results of the evaluation show that the reinforcement effect of the geocell is weak from the point of view of the bearing capacity. The vertical deformation of the subgrade soil when a cohesive soil, which is consistent with the subgrade backfill material, is used as the geocell backfills, probably due to the poor nature of the filler itself. When sandy soils are used as geocell filling materials, the reinforcement performance is significantly improved. In addition, the reinforcement effect of the geocell on the subgrade is highly dependent on the deformation. The lateral limiting effect of geocells can only be fully mobilized if a sufficiently large lateral deformation occurs. Related Articles | Metrics

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Effects of Water Content and Compression Time on Shear Properties of Interface between Steel and Clay#br# LIU Xianliang, GUO Jukun, WANG Rui, XU Junjie, XU Youguang 2023, 37 (3):  488-491.  Abstract ( 210 )   Save It is of great engineering significance to study the shear characteristics of the interface between structure and soil for the axial capacity and stability of the piled foundation. In this paper, the interface shear tests between steel and low liquid limit clay are performed by using the improved direct shear instrument, considering the two factors of the soil water content and the compression time. The relationship between the shear stress and the shear displacement, the shear strength index is analyzed respectively. The results show that the relationship between the shear stress and the shear displacement of the interface can be expressed by a hyperbolic model. The test peak shear stress and the model peak shear stress increase with the normal stress and the compression time and increase first and then decrease with the water content. The failure ratio ranges from 0.851 to 0.960, and the initial shear stiffness range from 19.96 to 131.58. The cohesion and the friction angle of the interface increase first and then decrease with the water content and reach the maximum near the optimal water content. The cohesion and the friction angle of interface are positively proportional to the compression time. Related Articles | Metrics

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Triaxial Shear Strength Analysis of Silty Clay in Poyang Lake Area HE Zhenhua, WU Haoyu, XUE Wei, LEI Zuxiang 2023, 37 (3):  492-496.  Abstract ( 215 )   Save Consolidated and undrained triaxial shear tests of silty clay in a section of the Poyu Bridge Project were performed by using the GDS triaxial instrument. The pore water pressure change curve and the deviator stress of the sample under different confining pressures were obtained. The deviator stress-strain curve, effective stress path and the variation curve of the pore water pressure of the sample are analyzed. The Duncan-Chang hyperbolic model is used to fit the deviatoric stress-strain relationship of the sample, and the five parameters of the Duncan-Chang hyperbolic model are obtained. The effective stress path and failure behavior of the system are summarized and analyzed. The test shows that the Poyang Lake silty clay has obvious shear expansion, and the confining pressure has a significant influence on the shear expansion of the soil; the deviator stress-strain curve of the soil is strain hardening, and the parameters of the Duncan-Chang model: k=34.74, n=0.94, Rf=0.61, φ′=30.8°, c′=13.5 kPa; the limit state stress ratio of the sample is Mc=1.32, and the effective stress path is S-shaped; the failure mode is generally drum-shaped deformation at the upper or lower part. Related Articles | Metrics

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Development and Application of a New Apparatus for Expansive Property Test of Coarse-Grained Soils CAI Yaoyu 2023, 37 (3):  497-500.  Abstract ( 141 )   Save In this paper, a new apparatus for expansive property test of the coarse-grained soil is introduced. The instrument overcomes the defect that the existing instrument is not suitable for coarse granular soil. The instrument is used to test the expansive force and expansion rate of the coarse-grained soil. The following conclusions are obtained: (1) the new apparatus can be used effectively and reliably. (2) The coarse-grained soil containing expansive rock and soil has certain expansive properties; (3) The soil samples with more fine particles in the coarse-grained soil have more obvious swelling phenomenon; (4) The expansive property of the coarse-grained soil is similar to that of the fine-grained soil. The new apparatus developed in this paper is convenient in operation, stable in performance, and precise in accuracy, which provides an accurate and reliable test equipment and method for testing the expansibility of coarse-grained soil. Related Articles | Metrics

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Characteristics Between Macro-Meso Parameters and Calibration Method of Soft Soil Creep Particle Flow FU Xu, HOU Dinggui, LI Qian, WANG Lintai, LIU Xiaoli 2023, 37 (3):  501-505.  Abstract ( 259 )   Save The key to the numerical simulation of the particle flow is to reveal the relationship between macro and meso mechanical parameters correctly and determine the meso parameters reasonably. The numerical tests of soft soil triaxial compression were established by the PFC3D software. Based on the results of macro-triaxial tests, the characteristic relationship between macro-meso parameters of the Burgers contact model was studied throughout the orthogonal test design. The results show that the stiffness Ek and Em of Hooker spring are the significant factors that affecting the deformation characteristics of the soft soil that mainly control the secant deformation modulus E50; The friction factors f and Em are significant factors that affecting the strength characteristics of the soft soil, which mainly controlling the maximum shear strength qf; The E50 is negatively correlated with Ek and positively correlated with Em, qf is negatively correlated with Em and positively correlated with the friction factor f. A linear regression relationship with macroscopic parameters as dependent variables and meso parameters as independent variables was established. The results of the inversion were used to perform the triaxial compression numerical tests and obtain macroscopic mechanical parameters. The errors were less than 10% compared with laboratory test results. Related Articles | Metrics

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Experimental Study on the Effect of Crack Propagation on the Shear Strength of Expansive Soils HUANG Peng, CHENG Yonghui, XIONG Yong, FENG Dang, CAO Xianzhen 2023, 37 (3):  506-511.  Abstract ( 219 )   Save The propagation of deep cracks directly affects the long-term service performance of expansive soil channel slope with the deep excavation. To study the influence of different degree of crack expansion on the strength of expansive soil, the membrane simulation method was used to prepare the expansive soil shear samples with different proportion of crack plane, and the direct shear tests under different overlying load were carried out to test the peak shear strength of the samples with different degree of crack expansion. Analysis shows that under the test conditions, the peak shear strength exhibits a nonlinear three-stage attenuation law of rapid attenuation, slow attenuation, and rapid attenuation with the crack expansion. Through the normalized processing, the attenuation ratio curve of the peak shear strength under the two overlying loads is obtained. It is analyzed that the overlying load has little effect on the attenuation ratio of the peak strength of the expansive clod, and the variation range is within 10%. The threshold of crack area proportion in three stages of nonlinear attenuation can be determined by multi-stage fitting of attenuation curve. When the crack propagation is at the threshold between rapid attenuation (stage I) and slow attenuation (stage II), the attenuation ratio of peak strength is (42.9%~47.8%), and when the crack propagation is at the threshold between slow attenuation (stage II) and fast attenuation (stage III), the attenuation ratio of peak strength is (50.3%~55.1%).The research results provide theoretical support for the design, calculation, operation and maintenance of deep excavation channel slope in expansive soil area. Related Articles | Metrics

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Experimental Study of the Bearing Behavior of PHC Pipe Piles in Argillaceous Siltstone LIU Chuang 2023, 37 (3):  512-514.  Abstract ( 364 )   Save This paper presents the PHC pipe pile static axial load tests in the argillaceous siltstone in Changsha area. When the tip of the PHC pipe pile in the argillaceous siltstone, the Q-S curve is steep, and has obvious failure points. The axial capacity type belongs to end-bearing and friction pile. According to the destructive test results of the single pile and the regional experience, the back-calculated pile side friction and tip resistance is performed. The empirical value of the PHC pipe pile in the soft argillaceous siltstone of the pile side friction and tip resistance is recommended. It is suggested that the side friction and the tip resistance of strongly weathered argillaceous siltstone should be lower according to the recommended value in “Technical Code for Piled Building Foundations”. The lateral resistance of the moderately weathered argillaceous siltstone is recommended to be 200-260kPa, and the end resistance is recommended to be 7000-9000kPa. Related Articles | Metrics

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Building Tilting Retrofit and Reinforcement by Combination of Bagged Lime Column and Micro Piles TIAN Tian, LI Mengyun, YANG Xiaoliang 2023, 37 (3):  515-518.  Abstract ( 226 )   Save The differential foundation settlements often occur in collapsible loess area due to the fluctuations of the groundwater, which will affect the long-term use of buildings. Quick lime columns are a common method for the retrofitting and strengthening foundations in these areas. Combination of bagged quick lime column and micro-pile are proposed to solve the shortcomings of traditional quick lime piles. The concept was applied in Shanxi Province. According to the expansion tests, the volume ratio of filling material of the column was set quick lime: dry plain soil: medium-coarse sand: cement 75:15:7:3; the maximum water injection amount was set 0.834 times of the mass of filling materials. Numerical simulation and field monitoring showed that the proposed micro-pile is feasible for the retrofit and reinforcement of building foundations. The settlements of the foundation tended to stabilize in 100 days from construction of the columns, and maximum settlement of the building foundation was less than 24.0mm. Related Articles | Metrics

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State-Dependent Experiments on Mechanical Characteristics of Artificial Cemented Silty Clayey Soils ZHOU Ya 2023, 37 (3):  519-523.  Abstract ( 319 )   Save A certain amount of cementitious material is mixed into the soil to form a structural artificial cemented soil, which could be widely used in the improvement of geomaterials. However, the existence of this structure makes the cemented soil demonstrates complex mechanical behaviors, so it is of great significance to quantitatively analyze the mechanical behavior of the cemented structural soil. This paper presents a case history of evaluating the mechanical behavior of the cemented soil. The test system analyzes the state dependence of the mechanical properties. The results show that: (1) Under the same confining pressure, the cemented soil with a relatively small void ratio shows more and more strain softening phenomenon during the shear process, and with the increase of the consolidation confining pressure, it gradually transitions to the strain hardening, which implying that the cemented soil is suitable for the shallow reinforcement; (2) The isotropic consolidation curves of the cemented soil and the remolded soil within 0~1500 kPa all showed different degrees of bending, among which the remolded soil was the most significant, and the less obvious the cemented soil with relatively small void ratio, indicating that the existence or strength of the cementing force significantly affected the isotropic compression characteristics of the soil; (3) The residual strength of the cemented soil and the slope of the critical strength line are less affected by the initial state quantity (void ratio, cementation), so they are considered to be a mechanical parameter independent of the intrinsic state. Related Articles | Metrics

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Field Trial Tests of Subway Shielded Tunnel Cutting Through the Existing Piled Foundations YANG Yijun, WANG Handong, YANG Hui, XU Linhu 2023, 37 (3):  524-527.  Abstract ( 129 )   Save The subway shielded tunnel usually inevitably encounters the pile foundations in the urban environment. When the piled foundations are encountered, the conventional methods are to replace the above bridge or change the subway alignment. There is less reported on the direct cutting through the piles by the shielded tunneling. This paper presents a case history of subway project in Suzhou which the existing shielded machine functions are improved, and the simulation test of shielded pile cutting is performed. The test monitored the deflection of the affected piles, the performance of cutter head, the shield tunneling parameters and the abrasion and cutting process of piled foundation in the process of cutting piled foundation under different working conditions and pile cutting modes. The trial test proves that it is feasible for EPB shielded machine to cut large diameter concrete piles in sedimentary soils, the shielded machine can meet the requirements of pile cutting in the high-water level sedimentary soil layer after the relevant improvement according to actual requirements. The test results can provide basis for the formulation of special monitoring scheme and special emergency plan for shield pile cutting, and also provide guidance for the design and construction of similar projects. Related Articles | Metrics

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Considerations of Pressuremeter Tests in Moderately Weathered Mudstone YANG Shuangle 2023, 37 (3):  528-530.  Abstract ( 551 )   Save By collecting the data of 13 pressuremeter test points in the moderately weathered mudstones in Wuhan Chow Tai Fook Financial Center, the characteristics of the pressuremeter test curve that not approaching the limit pressure PL convergence are expounded. It is observed that P0、Pf、fa、Gm、Em and other parameters in the moderately weathered mudstone tend to increase with the increase of depth. This depth effect is also briefly analyzed in the paper. It is proposed whether the characteristic value fa of rock mass bearing capacity determined by the pressuremeter test needs depth width correction and method for the correction is also provided. At the same time, by comparing the P0 and Pf with the qsia and qpa determined by the pile load test, the approximate relationship between them is evaluated. These analyses and reflections are intended to draw the attention of Wuhan area to the pressuremeter test in the moderately weathered rock mass. Related Articles | Metrics

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Engineering Parameters Determinations for Widening Embankments over Soft Soils in Flood Storage and Detention Areas HUANG Wanjiang, HU Shenggang 2023, 37 (3):  531-534.  Abstract ( 215 )   Save The proposed widened embankment for the flood storage and detention area construction project is over the soft soils. After years of consolidation, the soft soil properties under the existing embankment are different from the soft soil parameters outside the embankment influence zone. The proposed embankment body is formed by adding fill soils to the existing embankment. Firstly, the hazard characteristics of the existing embankment for the proposed reinforcement project were analyzed. Then, based on laboratory and in-situ testing methods, a series of soft soil tests were performed to determine the soft soil parameters inside and outside the existing embankment, and the recommended values of the stability optimization design parameters for the proposed embankment were determined. Finally, a new parameter determining and estimation method of the soft soil for existing embankment in the flood storage and detention areas was proposed based on the similar engineering embankment soft soil parameters. The evaluation results can provide some guidance for obtaining the parameters of the proposed embankment soft soil formed by the addition of exisitng embankment and for the design of proposed embankment. Related Articles | Metrics

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Calibration of Earth Pressure Cell in the Calibration Chamber YIN Jie 2023, 37 (3):  535-538.  Abstract ( 234 )   Save The earth pressure cell sensitivity K in the actual working medium within reduced-scale model experiment is quite different from the sensitivity K0 obtained from the manufacturer’s oil calibration environment. To improve the measurement accuracy of the miniature earth pressure cell in model tests of underground structures, a serial of calibration tests for earth pressure cell were carried out by using the similar materials from grade V soil stratum as the working medium. The test results show that the optimal overburden thickness is 1-3cm for the similar material of grade V soil stratum. The correlation coefficients R2 for calibration test data are all greater than 0.99, and the load-strain curves of earth pressure cell with different overburden thicknesses are almost identical and linear. The unloading stress-strain curves, on the contrary, show hysteresis effect to a certain extent in the earth pressure cell calibration test. The sensitivity K obtained from the calibration test is slightly less than the K0 provided by the manufacturer, which implies that the earth pressure cell should be re-calibrated before usage corresponding to the specific working environment.  Related Articles | Metrics

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Experimental Study of Salt Spray Corrosion of Coral Sand Concrete LI Hongli, WU Wenjuan 2023, 37 (3):  539-544.  Abstract ( 246 )   Save To explore the adaptability and mechanism of the coral sand concrete under the salt spray corrosion environment, the laboratory accelerated simulation tests were conducted. The test results showed that the coral sand concrete with the high strength level had a better adaptability under the salt spray corrosion environment compared to the coral sand concrete with the low strength level. The resistance of the conventional concrete to the salt spray corrosion was higher than that of the coral sand concrete with the same strength level; The compressive strength of the coral sand concrete first increases and then decreases with the increase of the salt spray corrosion time; The reduction in the compressive strength of the conventional concrete is smaller than that of the coral sand concrete of the same strength grade; Due to the accumulation of the corrosion products, the quality of each group of coral sand concrete (excluding CA-20) increases with the increase of the salt spray corrosion time, while the quality of CA-20 decreases due to small surface peeling in the later stage of the corrosion; The surface chloride ion concentration of each group of the coral sand concrete shows a trend of first rapid increase and then slow increase with the increase of the salt spray corrosion time. The apparent chloride ion concentration of each group of the coral sand concrete shows a trend of first rapid decrease and then gradually stable with the increase of the salt spray corrosion time. Under the same erosion time, the surface chloride ion concentration and the apparent chloride ion diffusion coefficient of the conventional concrete are lower than those of the coral sand concrete of the same strength grade. Related Articles | Metrics