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    31 August 2025, Volume 39 Issue 4 Previous Issue    Next Issue
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    Comprehensive Mitigation of Anti-Buoyancy and Raft Foundation Cracking and Water Seepage in an Underground Garage
    LIU Weichao
    2025, 39 (4):  507-512. 
    Abstract ( 1676 )   Save
    Under a “50-year return period” storm, most of the original anti-uplift ground anchors of a project in Shandong were pulled out. Resulting in a significant uplift of the underground garage structure, multiple locations found cracks at the raft foundations, and several hollow bulges were also observed at the raft foundations. There is an urgent need to repair the underground garage. In response to such hazards, the project adopts a comprehensive mitigation plan that combining “anti-buoyancy grouted ground anchor + drainage and water pressure relief system+pier cap grouting+crack repair”. Finally, the good effect of the “restoration of anti-buoyancy axial resistance+anti-buoyancy reservation for water releasing and pore pressure relief +filling of gaps under the raft foundation+ repairing cracks on the raft foundation” was achieved. Not only did it effectively solve the problems of anti-buoyancy failure of the original structure and raft foundation separation, but it also maximizes the repair of the original damage of the raft foundation. After the mitigation, no further cracking development was observed at the raft foundation, and the ground was flat without water seepage. The mitigation effect was satisfactory. This comprehensive mitigation plan complements and improves each other, and the reinforcement effect is significant. This provides a new approach for similar engineering design and has achieved significant economic and social benefits.
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    Application of High-Pressure Rotary Jet Grouting in Borehole Collapse Large Fills
    XIAN Li, YAO Bo
    2025, 39 (4):  513-516. 
    Abstract ( 500 )   Save
    With the rapid expansion of the urban boundary, the original mountainous area has become the urban construction land after the site preparation, which will form many deep fill areas. The later construction of pile foundation is prone to problems such as borehole forming difficulties. This article presents a case history of a municipal road project. The difficulty of drilling large diameter piles located in deep fill soil area is relatively high, and multiple borehole caving occur during the construction. Therefore, a relatively stable and reliable high-pressure rotary jet grouting pile foundation assisted drilling process is proposed. Relevant tests were conducted on site, and the results showed that the use of borehole forming auxiliary technology effectively solved the problem of difficulty of borehole forming for large-diameter pile foundations in deep fill soils. After the completion of pile foundation pouring, the effect was satisfactory. This article conducts experimental investigation on the structural parameters and related arrangements of auxiliary drilling technology through on-site experiments and proposes targeted relevant parameters.
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    Detailed Geotechnical Investigation of a Site with Complex Geological Conditions in Shanghai
    WANG Xue
    2025, 39 (4):  517-522. 
    Abstract ( 266 )   Save
    The scope of geotechnical investigation is to provide related accurate guidance and reference parameters for the upcoming engineering construction. For projects within complex geological subsurface conditions, the technical requirements for geotechnical investigation are more comprehensive, the types of investigation methods are more, and the key technical problems to be solved are more stringent. A project in Jiading District of Shanghai is presented in the paper.  The complex building layout and site geological subsurface conditions of the proposed project, combined with similar engineering experience in Shanghai are briefed. Based on the collection of existing geological background data and pre-analysis, the relevant geotechnical parameters are obtained by comprehensive use of drilling, sampling, laboratory, in-situ testing and other investigation methods. To find out the engineering geological characteristics and changes of foundation soil within the scope of site investigation depth, a comprehensive assessment of soil characteristics is performed. Hydrology, site stability and building suitability under complex geological subsurface conditions of the project are evaluated, and the foundation treatment and related geotechnical suggestions to provide guidance for building construction are also proposed.
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    The Design and Practice of a Green Deep Excavation Support Method in Changzhou
    SHEN Jian, JIANG Tao, WANG Huisheng,
    2025, 39 (4):  523-528. 
    Abstract ( 164 )   Save
    This article presents a deep excavation support project in Changzhou. The design and application of a series of green excavation support technologies, such as, SMW construction method, soil mixing columns with hot rolled steel inclusions and its installation are introduced. The integration consideration of engineering geological conditions, deep excavation safety, construction schedule, environmental protection, energy saving and emission reduction, economy and other requirements are also presented. The design aspects of large span and two-way steel combination support, flexible excavation support sequence, and demolishing of the supporting structure are thoroughly discussed in the paper. Combined with theoretical calculation and engineering implementation effect, the SMW construction method with large span steel combination support system can ensure the safety operation and use of the surrounding utilities, roads and buildings while ensuring the safety of the excavation itself. The relevant technical aspects and measures can play a valuable reference role for similar projects.
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    Measured Analysis and Control Measures of Columns in Cover Excavation of Adjacent Deep Excavation with a Common Wall
    TAO Lianjin, GAO Tengfei, JIAO Boyang, ZHAO Xu, GUO Fei, ZHANG Yu,
    2025, 39 (4):  529-536. 
    Abstract ( 185 )   Save
    With the acceleration of urbanization, the process of large-scale underground space development is also accelerated, and there will be a larger number of adjacent deep excavations at the same time or cross-construction. The support structure of adjacent deep excavations will produce complex deformation during the construction. The deformation of bracing structures in deep excavations using the top-down construction method is not only very important to the stability and safety of deep foundation, but also to the stability of underground and above-ground structures. The Beijing City Sub-Central Station Comprehensive Transportation Hub Project is presented in this paper as the case history. The measured data of deformation of columns in covered excavation of open cut deep excavation and semi-covered excavation deep excavation with common wall of the construction is analyzed. The PLAXIS software is used to simulate the entire process of adjacent deep excavation with common walls, and the deformation control measures of columns in the excavation with cover excavation area are proposed. The results show: (1) The maximum vertical deformation of the columns is 41mm, the deformation of columns shows large sides and small in the middle in the north-south direction, and small on both sides and large in the middle in the east-west direction; (2) The excavation of the adjacent excavations with common wall to the bottom of the excavation, the maximum horizontal deformation of each column is only 1.1mm, and the deformation direction is biased to the side of the open excavation area of pit 02B; (3) Reducing the head of confined-water (iii) to 9.8m elevation and increasing the embedment ratio of bored piles to 2.0 can effectively control the vertical deformation of columns; (4) When pit 03A is excavated first, the B1 floor slab can be constructed in advance so that the horizontal deformation of columns can be effectively controlled. The research results can provide some references and lessons for similar projects.
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    Design and Practice of Precast Inclined Strut for Deep Excavations in Soft Soils
    HOU Shengnan, ZHANG Kai, YUE Jianyong,
    2025, 39 (4):  537-542. 
    Abstract ( 234 )   Save
    There are many significant drawbacks in traditional cast-in-place concrete structures for excavation engineering, such as large construction site impact, low efficiency, and high energy consumption. With the acceleration of urbanization and the demand for sustainable green development, many new prefabricated assembled support technologies have emerged for excavation support engineering. Prefabricated assembled support structures have the characteristics of low cost, short construction period, and easy quality control. The Flying Fish 0401 project located in the Lingang new area of Shanghai is introduced, which excavation area is about 80,500m2, with a depth of 6.00-6.45m and tightly surrounded by three municipal roadways and pipelines. By considering the characteristics of the excavation depth, large area, high permeability coefficient, and analyzing its stress characteristics, a prefabricated support system was successfully implemented in the large-area excavation engineering. The excavation support structure took a fully prefabricated green support scheme consisting of prefabricated steel HUW panel support and precast inclined struct (PIS construction method) to replace the traditional cast-in situ sheet pile retaining wall and horizontal internal support design. The monitoring results show that adopting those technical measures can ensure the safety of the excavation and its surrounding environment, which provides a valuable reference for related projects.
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    Safety Measures During the Rehabilitation Construction of Aged Masonry-Retaining Walls-A Retaining Wall in Foshan City
    ZENG DeXin, ZHOU Xinglong
    2025, 39 (4):  543-547. 
    Abstract ( 204 )   Save
    From the end of the last century to the beginning of this century, restricted by many factors, such as, the social and economic level, the design and construction level of excavation support, and construction conditions at that time, the stone masonry retaining walls constructed were generally mainly dry masonry with less mortar, many cavities, and poor integrity. Under the combined effect of various objective factors, unstable phenomena such as common cracking, bulging, mortar missing, and even sliding and collapse were often observed, and the wall rehabilitation is required. During the rehabilitation construction of old stone masonry retaining walls, one of the key aspects is to ensure safety during the construction. Through practice, it is introduced that in the construction process of reinforcing old stone masonry retaining walls by the anchoring method, measures such as optimizing the construction sequence, construction equipment, and construction technology were adopted to effectively control the safety during the construction process and ensure construction safety. Practice shows that the above measures are feasible.
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    Analysis of Excavation Deformation and Internal Force of Supporting Structure of a Foundation Pit
    XIE Baojin
    2025, 39 (4):  548-552. 
    Abstract ( 160 )   Save
    The deformation and the internal force distribution characteristics of the supporting structure in a deep excavation project are presented in this paper. Three-dimensional numerical simulation method was used to simulate the entire process of the excavation. Under the influence of building load and roadway vehicle load, the excavation deformation trend of the excavated area and the horizontal deformation of the supporting wall were analyzed. The variation pattern with depth, the stress characteristics of the three-layer lateral support and the underground continuous wall and the supporting effect are evaluated. The results show that the maximum deformation occurs on the loading side of the 8-story building after the excavation, and the value is about 14 cm. The depth of the building load on the deformation of excavation is about 3 times that of the loading width. The main force structure of the first layer of the transverse support is the tubular beam, the second and third layers are the main beams, and the auxiliary beams play a fixed and connecting role. The main compressive stress of the underground continuous wall is greater than that of the middle and upper parts. The maximum compressive stress is about 5MPa. The maximum bending moment of the continuous wall appears at the depth of 6m on the side of the 8-story building, and the value is about 1 600 kN·m. There are three obvious inflection points at 6m, 10m and 14m, indicating that the lateral support has a certain limiting effect on the bending of the underground continuous wall.
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    Stability Analysis and Mitigation Measures of Daylight Bedded Rock Slopes with Extremely Thin Weak Interlayers
    WU Zhengchao, LIAO Dewu, ZHENG Bing, DU Yansong, PAN Shijia
    2025, 39 (4):  553-557. 
    Abstract ( 129 )   Save
    Currently, there are limited research results on high slopes with very thin weak interlayers and daylighting bedded rocks. Based on a sudden landslide in Baiyi Town, Wudang District, Guiyang City, this article uses numerical simulation methods to analyze the stability and prevention measures of daylight bedded rock slopes with extremely thin weak interlayers and detailed geological survey data. Research results show that the deformation mechanism of such slopes is slip tensile failure, and the extremely thin weak interlayers are the main reason for the slope sliding. Compared with the displacement of the slope under three different working conditions, it is concluded this type of slope experiences significant deformation and failure under both natural and water saturated conditions. In addition, based on the analysis of the deformation mechanism and the stability of the slope, a protective measure mainly consisting of the concept of “clearing the slope + slope toe protection” was proposed. Throughout the modeling and simulation analysis, it was found that such protective measures have a good protective effect on this type of slope.
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    Numerical Analysis of the Impact of Super Deep Excavation Construction on Adjacent Subway Structures
    LIU Yongzhi, GONG Sheng, CHENG Xiaobo, WANG Guoquan, YAO Huayan
    2025, 39 (4):  558-564. 
    Abstract ( 147 )   Save
    The deep excavation case history of the East Square of Hefei West-Railway-Station is presented in this paper. A three-dimensional numerical model of deep excavation was established by using PLAXIS3D software to investigate the impact of deep excavation construction in a complex environment on the adjacent rail transit structure of Metro Line No. 3. The analysis shows that the deep excavation the East Square of the West-Railway-Station induced horizontal displacement and vertical settlement of 0.87mm and 0.80mm respectively. The maximum horizontal displacement and vertical settlement of the entrance and exit structure were 2.60mm and 2.11mm respectively; the horizontal displacement and vertical settlement of the section tunnel near Hefei West-Railway-Station adjacent to Metro Line No. 3 were 0.58mm and 0.54mm respectively. All deformations met the requirements. The research results provide a scientific engineering case for the design and construction of similar projects in this area.
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    Deformation and Mitigation of an Expressway Embankment Slope Adjacent to River
    GUO Huajiang, AN Bangchao
    2025, 39 (4):  565-570. 
    Abstract ( 132 )   Save
    The landslides at expressway embankment slopes that are adjacent to the river frequently occur and these hazards might seriously affect the operational safety of expressways. This paper presents a case history of a landslide deformation mechanism and mitigation of an expressway embankment slope adjacent to the river in Guizhou. The evaluation results indicate that the landslide of this embankment is a medium sized plenary slide that is adversely affected by the erosion of the river water at the embankment slope. At the toe of the embankment slope, the fluctuation of the river water level has a negative impact on the slope. The permeability of the fill embankment is high, and excessive slope deformation occurs under the heavy precipitations. The numerical analysis results indicate that large deformations are observed in both horizontal and vertical directions. These deformations are concentrated along the Chishuihe River side and close to the machinery access road. Based on the specific conditions of this embankment, a comprehensive mitigation plan was implemented: Anti slide caisson plus repairing the drainage ditch plus clearance upper instable rock plus sealing off roadway cracks plus the rehabilitation of the machinery access road. This measure is approved to have a satisfactory result.
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    Study on Interface Shear Behavior between Completely Decomposed Granite and Concrete
    WANG Xuetao, TANG Rui, SU Dong,
    2025, 39 (4):  571-575. 
    Abstract ( 188 )   Save
    The completely decomposed granite is widely distributed. In deep foundation engineering, slurry is often used to prevent bore-hole caving in soil. However, the strength of mud cake is low, which will lead to the reduction of pile axial capacity. To improve the axial resistance of the pile in the completely granite stratum, post grouting is used to reinforce the soil around the piles. The direct shear tests were used to study the influence of mud cake effect, soil around piles with different cement content and the roughness of the shaft on the shearing behavior of the pile-soil interface. The results show that the interface strength between pile and soil is greatly reduced due to the lubrication of the mud cake. Grouting reinforcement can effectively improve the shear strength of pile-soil interface, but the behavior becomes brittle. Both the internal friction angle and the cohesion of the interface increase with an increase of the roughness of shaft.
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    Evolution of Three-Dimensional Soil Arching within a Pile-Supported and Geogrid-Reinforced Embankment
    LAO Junyuan, CHI Bingshi, ZHAO Linshuang
    2025, 39 (4):  576-579. 
    Abstract ( 128 )   Save
    This study investigated the evolution of soil arching within a pile-supported and geogrid-reinforced embankment using a three-dimensional finite element model. The results were verified through a comparison with the measured data obtained from a full-scale experiment. The development of the soil arching was evaluated during the embankment construction process and the static step-loading process. The study revealed that the stress concentration ratio between the average stress on the pile-cap and that on the subsoil increases with the increasing height of the embankment fill. But this ratio increased little during the static step-loading process. In the soil arching process, the arch foot was mainly located at the edge and corner, not the center of the pile-cap. This resulted in an uneven stress distribution on the pile-cap, with stress at the edge and corner larger than that at the center. With the increase of embankment filling height and the evolution of soil arch, the arch foot moves towards the center. The critical height of the soil arching is 1.3 to 1.4 times the net spacing between pile caps. Additionally, the arching heights were assessed at different locations of the embankment, and their values were approximately equal.
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    Discrete Element Simulation of Seabed In-Situ Cone Penetration Test
    SHI Rongjun, LIU Yisheng, ZHANG Guoyin
    2025, 39 (4):  580-585. 
    Abstract ( 116 )   Save
    The submarine cone penetration test (CPT) is a widely used insitu test method on the seabed. Based on the discrete element method, a discrete element model is used to simulate and analyze the in-situ measurement process of the probe penetrating the seabed soil. The underwater saturation state of the seabed soil is simulated by adding soil particle buoyancy and one-way fluid-solid coupling respectively, as well as the surface penetration model of the dry sand and two saturated soils are established. For the deep penetration, a 200 m soil depth penetration model using one-way fluid-solid coupling method is established. The numerical simulation results show that the soil particle response of the probe penetrating the saturated soil is significantly different from that of the unsaturated soil in terms of the force-related results such as tip resistance and the particle stress. The one-way fluid-solid coupling method can better simulate the underwater saturation state of the soil than adding soil particle buoyancy. In terms of tip resistance, only considering the buoyancy of soil particles will produce a difference of 9 %. In the surface penetration and deep penetration of the probe rod, the large stress of the soil particles is concentrated at the cone tip of the probe rod, and the related soil disturbance such as the displacement and rotation of the soil particles mainly occurs within a diameter range of the probe rod from the cone shaft.
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    Discussion on the Application of an Oblong-Shaped Soldier Pile
    YANG Yanbo, DONG Pengcheng, TANG Wei
    2025, 39 (4):  586-589. 
    Abstract ( 152 )   Save
    At present, the types of supporting soldier piles in excavation support engineering mainly include square and circular soldier piles. Square soldier piles have better stress forms and are more economical, but they need to be formed manually. Circular piles have poor stress forms and are less economical, but they can be mechanically formed. The current policies and regulations have increasingly strict restrictions on manual excavation, which leads to the fact that square piles with better support effects are often unable to be adopted, and circular piles with mechanical boreholes have high support costs due to poor stress distributions, which forms a general demand in support engineering. It is hoped that there is a soldier pile type that meets the safety and convenience of mechanical borehole forming and has high efficiency and economy like square piles. This article innovatively presents a new excavation support concept and method of “mechanical borehole forming oblong-shaped soldier pile” and makes a comparative analysis and research on the section characteristics, support effect and economy of oblong-shaped, square and circular soldier piles. The advantages and disadvantages of the relevant indexes of each soldier pile type are obtained, which provides a theoretical basis for the selection of the optimal support section, saves the support cost, improves the support effect, and increases the construction safety.
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    Prediction of Shear Strength of an Unsaturated Clay by sing on a Novel Biological Algorithm
    LIANG Shichao, ZHU Naijiang, ZHAO Hongbo, LIU Zhiqiang
    2025, 39 (4):  590-595. 
    Abstract ( 146 )   Save
    In order to obtain the optimal prediction model for the shear strength of an unsaturated clay, the long and short-term memory neural network model (LSTM) is used as the basis, and four biological algorithms, namely Harris Hawk algorithm (HHO), pigeon swarm algorithm (PIO), Sparrow algorithm (SSA) and Capuchin algorithm (CAP) are also used in this paper. The clay dry density, water content, pore ratio and temperature are used as the input data. Four types of optimization models are constructed in this paper. The results show that: the HHO-LSTM model has the best fitting effect. The slope of the fitting equation of the model was 0.991, the root-mean-square error, the average absolute error, the determination coefficient and the model efficiency coefficient are 1.328 kPa, 1.125kPa, 0.991 and 0.991, respectively. The GPI is 1.875. The accuracy indexes of simulated internal friction angle are 0.693, 0.584, 0.969 and 0.954 degrees, respectively with a related GPI of 1.805. The HHO-LSTM model can be used as a recommended model to predict the shear strength of the unsaturated clay.
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    Relationship Among Area Replacement Ratio of Composite Soils and Soil Three Phase Indexes
    ZHAO Pengtao
    2025, 39 (4):  596-599. 
    Abstract ( 195 )   Save
    The area replacement ratio of the composite soil is the most critical parameter in estimating the bearing capacity of composite foundation. To solve the computational problem of area replacement ratio involved in composite soil treatment design and professional geotechnical engineer examination, especially the computational relationship among area replacement ratio and soil three-phase indexes. Based on the in-depth study of the concept and computation method of area replacement ratio, this paper presents the composite soil with reinforcement body (column) having the effect of compaction as the case history. The basic conversion relationship of soil three-phase indexes is briefly introduced. The main concept of the constant dry soil mass among columns before and after the soil treatment is presented. This paper also discusses and deduces the computational relationship among the area replacement ratio, void ratio, dry density and other three phase indexes of the soil under two working conditions. The accuracy of the derived results ate verified and the advantages in solving problems in the examination of professional geotechnical engineers. The relevant research results are helpful to the design practitioners of composite soil engineering and the examinee of the professional geotechnical engineers in calculating the area replacement ratio.
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    Analysis of the Impact of Deep Excavation on the Underlying Regional Transit Tunnel
    ZHANG Jie, SONG Lei, LI Jipei, TANG Changyue
    2025, 39 (4):  600-605. 
    Abstract ( 119 )   Save
    With the continuous improvement of the urban rail transit network, it is inevitable that there will be adjacent or intersecting projects. The subway operation is very sensitive to the structural deformation, allowing for minimal deformation. To study the impact and response measures of deep excavation on the underlying regional transit tunnel, this article presents the municipal tunnel excavation project located directly above the Nanjing operating regional transit tunnel as a case history. The MIDAS-GTS geotechnical and tunnel simulation analysis software is used for numerical analysis. Based on the influence of spatial effects, the symmetrical zoning is adopted for deep excavation, and anti-buoyancy pipe curtains are established. The evaluation results are as follows: (1) During the deep excavation process, the vertical displacement generated by the underlying regional transit tunnel is greater than the horizontal displacement, which is basically twice of that; (2) The deformation of the left line corresponding to the first excavated area C is 1.4 times greater than that of the right line corresponding to the second excavated area D; (3) The pipe curtain method can effectively reduce the uplift of the existing tunnel in the lower part caused by the excavation of the upper foundation pit, which has reference significance for similar engineering design and construction.
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    Characteristic Analysis of Wastewater in Soft Soil Improvement by Electro-Chemical Process
    TONG Jiarong, WANG Ningwei, LUO Yuechun, ZHANG Shu,
    2025, 39 (4):  606-610. 
    Abstract ( 144 )   Save
    Electrochemical improvement of soft soil is an effective method for the soft soil strengthening. This paper presents the case history of soft soil treated by electro-chemical improvement project in Jinwan District of Zhuhai City. The water quality of the wastewater was tested and analyzed during the strengthening process. Affected by the properties of the electro-chemical improvement, the grouting solution and the geographical location of the project, the wastewater of this project has relatively high content of aluminum, sodium, chloride and total dissolved solids, and is rich in organic matter. It is a strong alkali solution, after the pH treatment, it can be discharged as the urban sewage water meets the discharging standards and will not affect the ecological environment. The Ca2+, Mg2+, Fe3+ ions and other heavy metal cations in soils can produce oxide/hydroxide precipitation during the electrochemical improvement, which promotes the consolidation of the soft soil and therefore improves the soil strength. The Al3+ in the soil will gradually be replaced with hydrogen ions produced by the electrolysis and form hydroxide precipitation, but at high pH value, part of the Al3+ will gradually dissolve and discharge from the cathode with the wastewater. It is suggested that the strong alkalinity and rich organic matter of the wastewater should be used for recycling, energy saving and emission reduction, so as to achieve the sustainable development of environmental protection.
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    Macroscopic and Microscopic Analysis of Soil Squeezing Effect of Pre-drilled Pipe Piles in Thick Peaty Soil Layers
    LI Taifeng, ZHANG Ruiyuan, JI Fuquan, CHEN Peishuai, GAO Ran
    2025, 39 (4):  611-617. 
    Abstract ( 195 )   Save
    To quantitatively study the influence of pre-drilled borehole parameters on the soil squeezing effect of pipe piles in peaty soils, field tests were conducted on the driving of of pipe piles in soft soils in a trail site at the bridge abutment area of Hailing Island Bridge to investigate the effect of pre-drilled pipe piles on the soil squeezing deformation around the piles. The results showed that pre-drilling measures caused the soil to shift towards the center of the borehole, while pipe pile driving caused the soil to shift significantly in the opposite direction. The impact range of soil squeezing was greater than 3D (D is the pile diameter). After a sharp linear increase in the pressure of excess pore water pressure in peaty soils, it maintains a relatively stable value in the short term. On this basis, a discrete element model was established, and the calculated values of lateral horizontal displacement were in good agreement with the on-site monitoring results. The displacement field can be divided into three parts. The area below the pile top and 2/3 of the pile body is the uplift displacement zone, the area above the pile end and 1/3 of the pile shaft is the horizontal displacement zone, and the area below the pile end is the subsidence displacement zone. The displacement field is distributed in an inverted cone shape and has a strip-shaped characteristic in the horizontal direction. When the pre-drilling rate and pre-drilling depth are above 0.5, the reduction effect on soil squeezing is more significant. It is recommended to set the pre-drilling rate and pre-drilling depth between 0.5 and 0.8 in the project, respectively.
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    Study on The Failure Mechanism and Stability of Very Large and Shallow Embedded Cavern
    LIN Yingshu, ZHENG Yun, LU Zude, ZHANG Wei
    2025, 39 (4):  618-624. 
    Abstract ( 82 )   Save
    To explore various conditions that affect the stability of shallow embedded caverns, a case history of a very large cavern in Xiamen is presented in this paper. The conditions examined are excavation, structural loads, seismic loads, and their combinations. The on-site geological surveys and data analysis provided the necessary mechanical parameters for simulations. The 3DEC simulations analyzed how the surrounding rock deforms and fails under these conditions. The results show the following: (1) The impact of stability of the embedded caverns, from strongest to weakest, is: combined structural and seismic loads, seismic action, excavation, and structural loads. (2) The cavern often experiences shear failures at the arch toe and crest of side tunnels, while tensile failures are rare and scattered. (3) Greater excavation depth reduces stability, and side tunnel excavation worsens the deformation. Structural load mainly affects the cavern’s sides. Changes in seismic force direction don’t destabilize the cavern, but seismic load in the Z-direction impacts stability the most. (4) When seismic force is in the X-direction, structural load can enhance stability. In other directions, it increases deformation.
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    Numerical Optimization of Construction Engineering of Tunnels in Soft Rock with Large Deformation
    AN Xiaotian
    2025, 39 (4):  625-630. 
    Abstract ( 240 )   Save
    Tunnels in soft rock mass with large deformation are characterized by low strength, significant deformation, and poor stability. During the construction, safety hazards such as large deformations, collapses, and sudden water or mud inflows are likely to occur. These hazards pose serious threats to both the construction safety and the engineering quality. Although researchers both domestically and internationally have conducted extensive studies on the optimization of support parameters, selection of construction methods, and deformation control, the dynamic optimization of support parameters and construction methods remains an impressive technical challenge under complex geological conditions. This study focuses on a tunnel in soft rock mass with large deformation in an expressway, utilizing on-site monitoring data and numerical simulation analysis to optimize the tunnel’s support parameters and construction methods. By analyzing the deformation characteristics of the surrounding rock and the stress behavior of the support structure, recommendations are made to optimize the support parameters for arch support, side wall support, and local weak sections. Additionally, based on the applicability analysis of various construction methods, the CRD method is recommended as the optimal construction approach under complex geological conditions. Suggestions for dynamically adjusting support parameters and construction methods are also provided. The research results demonstrate that the optimized support parameters and construction methods effectively control the deformation of surrounding rock, significantly enhancing the safety and quality of tunnel construction. These findings provide a theoretical foundation and practical guidance for optimizing support parameters and selecting construction methods in tunnel engineering under similar complex geological conditions, offering substantial significance for advancing tunnel construction technology.
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    Design Methods for Deep Excavations in Complex Surrounding Conditions
    XING Li
    2025, 39 (4):  631-637. 
    Abstract ( 124 )   Save
    This study investigates a deep excavation project adjacent to sensitive environments, particularly focusing on complex surrounding conditions and uneven excavation depths. The construction site borders critically protected structures, including an operational shielded tunnel of Metro Line No. 13, a river floodwall, and high-voltage power pipelines, necessitating stringent environmental protection measures. Furthermore, the presence of a shallow highly permeable silt layer with hydraulic connectivity to the adjacent Shahe River significantly increases engineering challenges and risks. To ensure construction safety and environmental stability, the project implemented a zoned construction strategy following the principle of “shallow excavation first and near distance first.” Priority was given to constructing the shallow excavation adjacent to the metro tunnel to establish a stiff isolation barrier, thereby mitigating disturbances induced by subsequent deep excavation activities. A high-stiffness cruciform orthogonal bracing system was adopted to effectively control wall deformation, while a secondary support technique for sunken deep pits enhances the stability of the retaining structure. Field monitoring demonstrated that the proposed design measures were scientifically validated and effectively maintained all environmental impacts within safe and controllable thresholds throughout the construction process.
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    Test on Durability of Soil Cured by Chloride-Sulfate Polymer Curing Agent
    HE Fangchan, JIN Mingyan, LI Liqing
    2025, 39 (4):  638-641. 
    Abstract ( 130 )   Save
    The base material for the channel lining should have a good durability performance, however, the mechanical properties of conventional soils cannot meet the specification requirements in the construction of channel lining and cannot be directly applied to the engineering practice. For this reason, the Jiaozuo Guangli irrigation district loam soil is used as a research object. To explore the degree of chloride-sulfate polymer curing agent on the loam soil durability, the soil samples are mixed with chloride-sulphate polymer curing agent. The mixed soil samples are tested with different agent contents and under the different seepage resistance and anti-freezing conditions. The results show that the cured soil has good durability when the water-cement ratio is 0.3 and the mixing ratio of curing agent: loam: sand is 1∶1∶1; the relative permeability coefficient of the cured soil is 1/5 of that of the cement-cured soil under the same condition, and the anti-freezing grade of the cured soil can reach F25 which is much better than that of the control group F15. In conclusion, this curing agent meets the specification requirements and has high economic benefits, and it has been applied to the actual project.
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    Monitoring and Deformation Analysis of the Deep Excavation of Building for Suzhou Disability Activity Center
    LI Min
    2025, 39 (4):  642-647. 
    Abstract ( 157 )   Save
    Deep excavation monitoring is an important step in the foundation construction. The realtime and continuous deformation monitoring of the deep excavation can ensure the safety of the foundation construction and the safety of the temporary construction and surrounding utilities and buildings. Therefore, monitoring and deformation analysis of deep excavation and surrounding environment are necessary. This paper presents a case history of the deep excavation monitoring program for Suzhou Disability Activity Center Building project. The horizontal and vertical displacement of excavation supporting structure, supporting axial force, underground water level, deep horizontal displacement of soil and other items were monitored. The deformation process and monitoring results were analyzed in graphical forms. It was found that the change of each monitoring point was within the normal range. The data of each monitoring point did not exceed the alarm value, the deformation of the deep excavation support was stable, safe and reliable. The effect was satisfactory, which verified the reliability of the deep excavation supporting structure and the rationality of the monitoring program. It can ensure the safety of deep excavation and surrounding environment, improve the construction quality and minimize the safety hazards, and provide a useful reference for similar projects in this area.
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    Estimation of Foundation Bearing Capacity and Compression Modulus by Cone Penetration Test
    YUAN Pengju, ZHANG Lifeng, CHEN Longyang, HAN Wenyong, LIU Peng
    2025, 39 (4):  648-652. 
    Abstract ( 300 )   Save
    A safe, reasonable and high efficiency geotechnical design in a practical engineering project is based on a comprehensive analysis of the site-specific soil and rock properties. In this paper, the soil bearing capacity and compression modulus of the central foundation of a large project in Beijing are estimated by using the in-situ testing technique of cone penetration test (CPT). The results show that the variation of the bearing capacity of the foundation estimated by the CPT and the actual laboratory test is roughly the same, and the bearing capacity of the foundation is slightly different at various depth points. The compression modulus of soil layer estimated by CPT is slightly smaller than that measured from the laboratory test. At a soil depth of 32.6m, the compression modulus determined by CPT is much larger than that determined by laboratory test results. The compression modulus estimated by the CPT and the actual compression modulus vary with the depth of the soil. The results show that the CPT can accurately reflect the actual bearing capacity and the compression modulus of soils.
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    Estimation of Compression Index of Soft Soils Using Cone Penetration Test with Piezocones
    CHEN Kai, LIN Jun, YAN Chao, WEI Mingli
    2025, 39 (4):  653-657. 
    Abstract ( 169 )   Save
    The evaluation of compression index of soil is of great significance to the settlement of foundation soils which will have an impact on the size and dimensions of foundations. This paper analyses the correlations among three physical parameters of soil, namely void ratio, moisture content, and liquid limit. An empirical formula is then developed. The results show that there is a good linear relationship among the void ratio, moisture content, liquid limit, and compression index. Coefficient of Determination (R2) values are 0.837, 0.823 3, 0.691 0, respectively. At the same time, special attention is paid to the cone penetration test with pore water measurement (piezocone) method for the soft soil in-situ testing. Based on the piezocone data obtained from an economical housing project in Nanjing city, and combined with soil laboratory test data, the compression index of soil is analyzed and the accuracy of predicting it through the piezocone testing is evaluated. The results show that the cone tip resistance is correlated with the compression index, and the correlation coefficients of different soil layers vary (clay > silty clay > sandy soil). When the correlation coefficient takes a specific value, the compression index of each soil layer could be predicted accurately by a formula and the compressibility of each soil layer can be evaluated.
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    Development and Application Testing of a System for Investigating the Mechanical Characteristics of Pile-Soil Interfaces
    MA Xiuru, FENG Jianxue, XIAO He, LUO Zhan, LIU Xiaowei,
    2025, 39 (4):  658-663. 
    Abstract ( 139 )   Save
    The mechanical properties of the pile-soil interface are a crucial issue that affects the safe construction and healthy operation of pile foundations. Analyzing these properties is an essential step to uncovering the deformation and bearing capacity mechanisms of the pile foundation. Therefore, this paper developed a pile-soil interface mechanical properties model test system, which uses PLC automation control technology to control the vertical loading rate and displacement. The system also considers different ground settlement states, moisture content, and complex loading conditions. To verify the reliability and effectiveness of the test system, the mechanical properties of the pile-soil interface during the penetration process of a red clay pile with different moisture contents were analyzed and compared with numerical simulation results. The results revealed that the unsaturation of the soil significantly increases the soil pressure and unit lateral friction of the pilesoil interface. The test results agreed well with the numerical simulation results. This model test system can provide experimental support and theoretical references for pile foundation engineering practices.
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    An Indirect Method to Determine the Degrees of Building Foundation Damage
    XIE Lanfang
    2025, 39 (4):  664-667. 
    Abstract ( 158 )   Save
    The foundation supports the superstructure, and the stability of the foundation is closely related to the stability of the superstructure. As a hidden project, it is difficult to find out whether the foundation is damaged in its service life. Once the damage occurred, the consequences might be very serious. Currently, most appraisal agencies estimate the degree of potential hazards of the building foundations by observing the cracks, inclination or deformation of the superstructure. In special cases, the foundation might be exposed to estimate the degree of damage. However, to observe the damage of the foundation throughout the deformation of the superstructure can only be found after severe deformation has occurred. Further, the location of the problematic soil stratum and the degree of damage of the foundation cannot be directly determined. This paper presents a method of indirect identification of foundation damage-geophysical investigation method, and verifies the reliability of this method through exploration method.
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    Case Study And Physical Model Testing of a Karst Rock Cavern Collapse
    MA Xiaolan, LIU Hong
    2025, 39 (4):  668-673. 
    Abstract ( 133 )   Save
    This case study presents the collapse that occurred on April 6, 1999, at Zhonghua North Road in Guiyang. The paper systematically demonstrates the entire process of physical modeling experiments on collapse of an underlying karst rock cavern, which includes generalization of geological models, selection of experimental variables, design of similarity ratios, design of physical models, design of similar materials, and physical model testing. A total of 15 sets of physical model experiments were formulated and implemented. The core objective of these experiments was to explore whether there is a positive correlation among three influencing factors the dimensions of soil cavities, the amplitude of water level drawdown, the rate of water level drop and the susceptibility to collapse of underlying karst rock caverns. The experimental results indicate the following: 1)The collapse of underlying karst rock caverns is influenced not only by the gravity and the negative pressure but also by the effect of underground erosion. 2)Throughout the collapse process, the settlement of surface soil continues to develop. In the early stages, the subsidence of surface soil is small but steadily increases. In the later stages, the subsidence rate continues to increase, ultimately leading to “sudden”, “instantaneous” collapse. 3)There is indeed a positive correlation between the size of karst rock cavities, the amplitude of water level drawdown, the rate of water level drop, and susceptibility to collapse of underlying karst rock caverns. Specifically, the larger the radius of the soil cavities, the more likely it is to collapse; the larger the water level drawdown, the more likely it is to collapse; and the larger rate of water level drawdown, the more likely it is to collapse.
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    Experimental Study on the Expansion and Contraction Characteristics of Expansive Soils in Zhengzhou and Luoyang
    CHEN Bing, ZHOU Maomao, PANG Renhao, SUN Xueying, LIU Min, NIU Zhifeng, WANG Liuzhen
    2025, 39 (4):  674-678. 
    Abstract ( 110 )   Save
    To study the influence of water content on expansive soils in Zhengzhou and Luoyang, the expansion stress, load expansion rate and shrinkage tests were carried out on the undisturbed soil and remolded soil samples. The variation of expansion stress, load expansion rate, shrinkage coefficient and total expansion and shrinkage deformation with soil water content were analyzed. The study results indicate that: (1) the expansion stress and load expansion rate decrease with the increase of water content; and the shrinkage coefficient increases with the increase of water content. When the water content increases, these parameters gradually tend to be stable; (2) The total expansion and shrinkage deformation show a trend of first decreasing and then increasing with the increase of the initial water content of the soil; (3) Reasonable control of fill moisture content and load can effectively control the total expansion and shrinkage deformation of the soil. Through the experimental research data, the quantitative relationship curve equation among the expansion stress, load expansion rate, shrinkage coefficient and water content was established, which provides a key theoretical basis for controlling the hazards of expansive soil in practical engineering.
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    Triaxial Shear Testing of Coal Gangue Subgrade Fillers: Fractal Gradation Effects on Mechanical Performance
    HU Zengqiang, LUO Hao
    2025, 39 (4):  679-682. 
    Abstract ( 133 )   Save
    To advance the resource utilization of coal gangue as subgrade fill, this study systematically investigates the coupled effects of fractal dimension and confining pressure on the mechanical behavior of gangue through static triaxial shear tests. Using gangue from Nayong County, Guizhou, five gradations with fractal dimensions (D=2.1~2.45) and four confining pressures (50~300 kPa) were designed. Results show that the gangue is dominated by the SiO2-Al2O3-Fe2O3 system (>85%), indicating good engineering applicability. All specimens exhibited dilatant plastic failure. Strength parameters reveal that cohesion c increases from 76.87 kPa to 101.81 kPa (32.47% growth) with rising fractal dimension, whereas the internal friction angle φ varies negligibly (<12%). Embedded within the Mohr-Coulomb framework, a semi-empirical model is developed to quantitatively predict the strength of graded gangue. The model clarifies the underlying mechanism by which fractal grading governs strength through particle filling and interlocking, providing a theoretical basis for the optimal design of coal-gangue subgrade fills.
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