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30 June 2025, Volume 39 Issue 3 Previous Issue    Next Issue

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Analysis of Vacuum Preloading Combined with Water Loading in Surcharging of Soft Soils TANG Binbin, ZHU Ganwei, TANG Jiang, ZHANG Lihong, ZHANG Kaihua 2025, 39 (3):  349-352.  Abstract ( 114 )   Save With the vacuum preloading becoming an important method in soft soil treatment, improving the preloading effect within an appropriate preloading time has become particularly important. The conventional vacuum preloading methods may require a large amount of rockfill materials; Or the physical properties of the surface soil do not increase significantly, the sensitivity of the deep soil changes less, and the consolidation degree of the soil layer is average. The vacuum preloading combined with the water loading is suitable for the coastal and plain areas lacking suitable stone materials because it does not require a large amount of stacked stone materials. Throughout the application analysis of the vacuum preloading combined with the water loading in soft soil improvement, it was found that the physical properties of the shallow soil have been improved to varying degrees; The sensitivity of the deep soil layers significantly decreases, and the sensitivity of major soft soil layers is less than 2.9; The overall consolidation degree can reach over 88%. This can provide reference for the analysis of the effect of vacuum preloading combined with water-based soft foundation pretreatment under similar geological conditions in coastal areas. Related Articles | Metrics

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Application of Anti-Uplift Piles CHEN Wenshuang, WANG Yuexiang 2025, 39 (3):  353-356.  Abstract ( 158 )   Save The uplift force generated by the groundwater will often cause adverse influence or even damage to the building foundations. Therefore, the anti-buoyancy design is a crucial link in the underground structures. At present, the commonly used anti-buoyancy technology is mainly to increase the structure’s self-weight and to bury the anti-uplift pile (anti-uplift anchors). This paper focuses on the principles of the mechanism, the classification, the application areas and the axial capacity of the anti-buoyancy piles. Combined with a case history of the Suzhou Campus of Nanjing University, the application of the resistant pile is analyzed. The test method of the axial static load test is conducted on site. By presenting the load test results, the axial capacity of the pile meets the design requirements. Therefore, the reliability of the anti-buoyancy design and the safety of the structure are achieved. Related Articles | Metrics

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Analysis and Design Options of a Material Storage Yard Over Deep Soft Soils for a Nuclear Power Plant SUN Yuting, GONG Lifei, ZHANG Hao 2025, 39 (3):  357-360.  Abstract ( 93 )   Save The tidal flats in coastal areas provide large area of land for the engineering construction and socioeconomic development. But the soft soils in the tidal flats are deep and widely distributed, which is easy to cause hazards such as the excessive settlement of the storage yards, the differential settlement and global stability issues for the foundations during the construction and the operations. A nuclear power plant in the eastern coastal area is presented in this paper as an example. The subsurface conditions, such as, engineering geology, the main physical and mechanical properties of the soft soils are evaluated by means of the geological exploration results combined with the subsurface investigations in proposed temporary storage yard. It is proposed that the design concept of “multi-stage gentle slope surcharging and geosynthetic reinforcement” is adopted. Through the global stability analysis and the numerical simulations, the results indicate that the stability of the graded construction over the deep soft soils and the safety of the influence on the surrounding buildings are effectively ensured by measures such as geosynthetic reinforcement and the different zoned construction. The feasibility of the design concepts are verified. Related Articles | Metrics

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Design and Practice of Deep Excavations Adjacent to Flood Control Facilities and Historic Buildings GE Xinpeng, SHEN Jian, WANG Huisheng, 2025, 39 (3):  361-365.  Abstract ( 88 )   Save A deep excavation project in Shanghai near the Huangpu River is adjacent to a flood control wall, the Su gate pier and other important flood control facilities. This project is also close to two other well-known historical buildings. Since the surrounding environmental conditions are extremely sensitive, the deep excavation deformation control requirements are extremely high. The project site engineering geological conditions are complex, and the soil of the adjacent river stratum is poor and permeable. There are also many design and construction difficulties such as underground obstructions. To solve the above-mentioned hazards, an overall zoning and staging option with a combination of bottom-up and top-down construction method was adopted for the deep excavation, and the support structure measures were strengthened for the key sensitive object protection links, to integrate the environmental protection requirements, the construction schedule and the engineering geological conditions. The measured data demonstrate that the surrounding protection objects such as the Huangpu River flood control facilities and historical buildings adjacent to the excavations are in a safe and controllable state during the excavation construction. The series of design measures implemented ensure the safety of the surrounding environment and achieve the expected effect. Related Articles | Metrics

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Analysis and Mitigation Measures for Quality Issues of a Rock Socketed Pile YANG Tao, YAN Yonghui 2025, 39 (3):  366-368.  Abstract ( 95 )   Save Rock socketed piles have the advantages of high single pile axial capacity, less settlement, and matured construction procedures, making them widely applicable to building foundations with high axial capacity requirements. A high-rise residential project adopted the rock socketed pile foundation. Due to geological conditions and the construction techniques on the site, there were multiple occurrences of slurry leakage and borehole caving during the pile installations, which seriously affected the quality of the pile foundation and led to insufficient axial capacity of some mono-pile foundations. By comparing the detailed subsurface information and pile installation data, analyzing the static load test and low strain integration test data of these piles, and verifying the concrete coring method, the article explores and analyzes the potential reasons for the quality hazards of these rock socketed piles, and provides detailed solutions. After the problematic piles are mitigated, the single pile axial capacity could meet the design requirements. It is confirmed that the mitigation plan is feasible. Related Articles | Metrics

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Evaluation of the Reinforcement Plan for a Pipe Jacking Launching Pit in the Close Distance to a River Channel LU Dexin 2025, 39 (3):  369-374.  Abstract ( 109 )   Save Based on a case study of a municipal river engineering project near pipe jacking launching well, a three-dimensional numerical model was established to study the influence of different reinforcement options at the back of the pipe jacking launching pit and the presence or absence of river conditions on the soil deformation behind the launching pit. The results show that the reinforcement concept of using single row piles and three-axis soil mixing columns for the improvement of the launching pit is feasible when there is no river channel. When there is a river channel, the lateral displacement value of the strata using this reinforcement scheme is 66.15mm, which does not meet the requirements of deformation control. When the back of the launching pit of the pipe jacking is close to the river channel, the depth range of the river channel cannot provide effective support at the back of the pipe jacking, and the passive soil pressure provided by the back of the back layer must be calculated from the bottom of the river channel; The soil improvement adopted a double row pile + three-axis soil mixing pile reinforcement concept, with a maximum deformation value of 29.22 mm in the soil, which meets the deformation requirements of the surrounding environment and is feasible; The embedded depth of the double row piles in the support should meet the requirements of the stability of the deep excavation and the ability of the passive soil pressure on the outer layer of the piles to balance the pushing force of the pipe jacking. Related Articles | Metrics

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Application of Servo Prestressed Concrete Support a Deep Excavation in Soft Soils Adjacent to a Subway SONG Qingming, YOU Bo, ZHAO Jingyan 2025, 39 (3):  375-381.  Abstract ( 118 )   Save With the development of subway, the unloading of the deep excavation will adversely affect the adjacent subway tunnel, which even may cause the local damage to the tunnel structure. Based on a project in Qingpu District of Shanghai, this paper introduces the application of servo prestressed concrete support in the deep excavation near a subway in soft soil area. The engineering practice shows that the servo prestressed concrete support has obvious control effect on the lateral displacement of the supporting structure, which can reduce the lateral displacement of the retaining structure by 30%~40%. By using the servo prestressed concrete support technology to actively apply axial force, the deformation of retaining wall can be accurately controlled, and the influence on sensitive buildings (structures) such as rail transit is reduced. In the implementation process of the servo prestressed concrete support, the key monitoring data such as retaining inclination measurement and support axial force, load them step by step, and dynamically adjust the prestressed loading value according to the monitoring results are presented. Related Articles | Metrics

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Design and Construction of Deep Excavation Support Adjacent to Buildings with Preserved and Shared Walls ZHANG Lili 2025, 39 (3):  382-386.  Abstract ( 85 )   Save With the rapid development of urban areas, the land usage in the city center is becoming increasingly demanding. How to maximize the safety and stability of adjacent buildings has become the most important issue to be solved in deep excavations. This article combines engineering practice to study the design and construction of deep excavations, which is adjacent to preserved buildings in the city center and shares basement exterior walls. The internal force and deformation of the deep excavation supporting structure near the existing building were verified using a Tongji Qimingxing software. The impact of foundation excavation on the adjacent building outside the excavation area was analyzed using a two-dimensional finite element software. At the same time, the selection of deep excavation support plans under space constraints, as well as the design and construction focus of the common wall parts with buildings under construction, were introduced. The technical difficulties in the design and construction of deep excavation support for the adjacent preserved and under construction buildings in the city center were successfully solved, which can provide reference for similar projects. Related Articles | Metrics

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Application of Reusable All Steel Support in Deep Excavation in Soft Soils WANG Jie 2025, 39 (3):  387-391.  Abstract ( 84 )   Save A green deep excavation support method based on all steel support structure is proposed to address the problems of low construction efficiency, non-recyclable materials, and adverse environmental impact of traditional support systems of deep excavation in soft soils. By establishing a finite element numerical model and a multi-dimensional plan comparison mechanism, the collaborative bearing mechanism and the ecological benefits of the steel support system in soft soils are analyzed in detail. Research has shown that the “bow shaped” displacement distribution pattern formed by the synergistic effect of steel supports and piles can effectively control the deformation of the deep excavation and reduce disturbance to the surrounding environment; Compared with the traditional concrete support technology, the new system shows breakthrough improvements in construction organization efficiency, the material recycling, and the carbon emissions. Through the modular design and the steel component recycling, this technology achieves multi-objective coordination of safety control, resource conservation, and low-carbon construction. Engineering practice has verified that this system provides an innovative solution for the deep excavation in soft soils in highly sensitive environments that combines structural safety and ecological friendliness through the effective integration of mechanical properties and sustainable attributes. Related Articles | Metrics

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New Vacuum Combined Surcharge Preloading Technology Applied in Zhuhai West District YE Sheng, CHEN Shiwen 2025, 39 (3):  392-396.  Abstract ( 97 )   Save This paper presents an innovative vacuum combined surcharge preloading technology system for the soft soil improvement. This system seamlessly incorporates connection, water-gas separation, clogging-resistant prefabricated vertical drains, and surcharge-assisted dewatering to minimize the vacuum loss, to avoid the pipe clogging issues, and to accelerate the soil consolidation. Using a municipal road project in Zhuhai’s West District as a case history, this paper explains the technology’s principles, implementation, and outcomes. Field data shows an average soil consolidation of 94.2% after 124 days of preloading, with only 1-2 cm settlement over five years and an estimated post-construction settlement of about 13.5 cm. Physical and mechanical property tests indicate that improved soil demonstrated an 8.6% increase in the natural density, 85.7% growth in the cohesion, and 155.6% improvement in the internal friction angle. Specifically, the natural density, the cohesion, and the internal friction angle increased by 8.6%, 85.7%, and 155.6% respectively, while the natural water content, the void ratio, the plasticity index, and the liquidity index decreased by 31.3%, 30.4%, 9.7%, and 31.6% respectively. These results indicate substantial enhancements in overall performance, with treatment outcomes exceeding expectations. Related Articles | Metrics

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Estimation of Water Inflow in Deep Excavation and Effect of Ground Subsidence QUE Linying, FAN Xiufeng, LI Jiakun, ZHANG Yunzhao 2025, 39 (3):  397-401.  Abstract ( 154 )   Save Accurate estimation of the water inflow and the effective monitoring of the environmental effect of the ground subsidence in the deep excavation dewatering are the prerequisites for a successful implementation of deep excavation. A case history of a deep excavation project is presented in this paper. The large well analytical method and the finite difference numerical simulation method are used to estimate and to evaluate the water inflow in the deep excavation area. The change of water level and the ground subsidence around the excavation area caused by different insertion depth of water-stop curtain, and the characteristics of additional water level and ground subsidence caused by the leakage of water-stop curtain are also studied. The results show that: (1) the error of water inflow estimation by the large well method is larger than that of by the numerical simulation, and the values of parameters such as the permeability coefficient and the aquifer thickness have an important influence on the estimation of water inflow, the numerical simulation parameters are taken as subarea refinement. (2) when the insertion depth of the water-stop curtain exceeds 60% of the thickness of the aquifer, it begins to play its role; when the insertion depth exceeds 80% , the clogging effect is obvious; when the insertion depth is equal to the thickness of the aquifer, the change of the water level outside the excavation area and the ground subsidence can be neglected; (3) when the water-stop curtain is leaking, the additional water level drop and ground subsidence around the leakage point due to the leakage appear to be centered on the leakage point; The phenomenon that values decrease with distance from the leak point. Related Articles | Metrics

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Analytical Method for Deformation of Deep Excavation Under Non-Limit Equilibrium Earth Pressure Conditions HE Chong, TANG Jianhua, FENG Xiang, LIU Chengchi 2025, 39 (3):  402-406.  Abstract ( 67 )   Save This paper considers the influence of the retaining wall deformation and the soil arching effect on the active earth pressure and considers the non-limit equilibrium earth pressure to discuss the relationship between the earth pressure and the retaining wall deformation. Obtaining the analytical formula for the ultimate earth pressure can simulate the process of the earth pressure gradually developing from static earth pressure to active earth pressure with the deformation of the retaining wall. The non limit equilibrium soil pressure model is applied to the elastic foundation beam model, and the equilibrium differential equation of the elastic foundation beam is solved by combining the rod finite element method and the semi -numerical and the semi-analytical methods to explore the deformation characteristics of the retaining structure during the excavation. Through the specific engineering cases, a statistical analysis of measured data such as deformation of the retaining wall and the soil pressure is conducted to study the influence and the regularity of the deformation characteristics of the retaining wall, and to verify the rationality and reliability of theoretical methods. Related Articles | Metrics

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Stability Analysis of Fly Ash Landfill with Underlying Soft Soils MIAO Chunxia, DONG Hui, LI Jin, ZHANG Xiaolei, ZHANG Xiaowei, XU Yi 2025, 39 (3):  407-412.  Abstract ( 92 )   Save Shanghai Laogang Landfill is built over the soft soils, and the shear strength of the soft soild is a key factor in the stability of the landfill. There is a ton-bag type fly ash landfill area built on the landfill, and the characteristics of the ton-bag fly ash are different from traditional waste and paved fly ash, resulting in insufficient understanding of the stability of the soft soil underlying the landfill. Based on the preliminary geological exploration data, the design parameters of the underlying soil layer of the fly ash landfill are estimated. By using the PLAXIS software, a finite element numerical model of the landfill-foundation is established. Considering the consolidation settlement of the soft soil under layered landfill, the strength reduction method is used to estimate the safety factor of the fly ash landfill slope; The effects of the landfill height, the grade of slope, the loading rate, and the filling method on the underlying soft soil layer are evaluated. The feasibility of expanding the capacity of fly ash landfills, and propose design suggestions to ensure the safety and stability of fly ash landfill are presented. Related Articles | Metrics

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Engineering Characteristics and Deformation Analysis of Emeishan Formation Basalt in Kun-Tang Expressway DAI Wenjun, WU Guobin 2025, 39 (3):  413-416.  Abstract ( 106 )   Save The under-construction Kunming-Tangdian Expressway passes through the basalt and tuff formations of the first to third sections (P2e1-P2e3) of the Permian Emeishan Formation. The project is mainly pavement engineering. The basalt and tuff have great differences in rock mineral composition, structure and structure. Basalt has developed columnar joints and is filled with clay and chlorite. The physical and mechanical properties of the structural plane are poor. The secondary clay and zeolite, with the physical and mechanical characteristics of swelling potential and strong water sensitivity, constitute the weak interlayer in the basalt stratum. During the construction, many slope deformations occurred in the basalt section of the Emeishan Formation, which mainly occurred in the riverside area, followed by the slope area. The circular sliding mode in the shallow soil layer is the main type, followed by the wedge failure mode in the rock layer. The formation lithology mainly occurs in tuff and basalt are second, and the slope deformation is mainly affected by factors such as poor physical and mechanical properties of tuff, unfavorable structural plane, groundwater action and steep slope rate. Related Articles | Metrics

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Generation Mechanism of Softening Estimation of Cemented Soils HUANG Hui, LU Yong, DENG Yanbo, LOU Yueyue 2025, 39 (3):  417-423.  Abstract ( 84 )   Save With the continuous construction of infrastructure, more and more underground engineering and geotechnical engineering related projects, the increasing problems encountered in the construction process, the problem of large deformation and the failure of soil are commonly encountered. Only by theoretically explaining the mechanism of the strain localization of the failure process of geotechnical samples be reproduced and solved. In this paper, the finite element software by using the constitutive model of the cemented soil is used to explore the effects of dilatancy softening, the cementation damage softening and the boundary constraints on the strain localization deformation. The study indicates that: (1) The density of the soil plays a key role in the dilatancy softening characteristics of the sand. At the same time, the dilatancy softening produces strain localization, and X-shaped shear band changes in the interior of the sample. (2) The initial cementation force is added to soften the cementation structure based on the original dilatancy softening, which makes the peak strength of the soil gradually increase. The cementation damage coefficient determines the speed of cementation force loss and affects the peak value of soil, but the softening of the cementation damage does not change the volume strain trend of soil. (3) The end constraint will affect the distribution of strain localization, but it has nothing to do with the occurrence of strain localization. Related Articles | Metrics

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Discussions on Simplified Estimation Method of Basic Quality Index BQ Value of Rock Mass WANG Zhenzhong, ZHANG Li, SUN Zhen, WANG Lei, ZHAO Qingzheng, ZHU Zeqi 2025, 39 (3):  424-427.  Abstract ( 168 )   Save In the classification of rock mass quality based on BQ value, a lot of in-situ and laboratory testing work are often required. For long-distance rock tunnels, the related work is more complicated and difficult. The Taiyueshan Tunnel in Shanxi Province on the Changzhi Yan’an connecting line (G2211) of the Qinglan National Expressway is presented in this paper. Based on the existing rock mass test data of the Taiyueshan Rock Tunnel, a simplified calculation method of BQ value is proposed by studying the relationship between rock saturated uniaxial compressive strength Rc and rock integrity index Kv. Comparing this method with the original BQ value estimation method, it is found that the two methods are basically consistent. The simplified estimation method of BQ value has a good engineering applicability and can greatly reduce the in-situ test workload and the influence of subjective experience. Related Articles | Metrics

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Slope Stability Analysis with Dynamic Double Factors Strength Reduction Method ZHANG Zhiwei, ZHU Haofeng, CHENG Xiaowei 2025, 39 (3):  428-432.  Abstract ( 96 )   Save The value of strength reduction ratio is a key issue in the slope stability analysis by using double factors strength reduction technique (DDRM). By considering the nonsynchronous shear strength deterioration of the internal friction angle φ and the cohesive strength c, the dynamic proportional relation of the strength reduction factor Fφ/Fc is proposed in this paper. Moreover, based on a comprehensive factor of safety by the shortest path method of the strength reduction technique and the minimum value principle of the slope factor of safety, this paper presents a slope stability analysis method by the DDRM. The results indicate that the slope safety curves which can be fitted well by the polymerization with above 0.99 fit degree show an obvious nonlinear characteristic. The curve of the c-Fφ/Fc indicates that the strength reduction factor ratio Fφ/Fc  is varied between 1.02 and 1.09 which verify the rationality of the DDRM. Comparing with the traditional single factor (SRM) and the double factors strength reduction technique (DRM), the value of the strength reduction factors Fφ/Fc is simpler and the dynamically changes by the DDRM proposed in this paper. So, the smaller slope factor of safety by the DDRM makes the slope safer and the factor of safety is more reasonable than by using both the SRM and the DRM. Related Articles | Metrics

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Deformation and Failure Mechanism of Landslide Containing Gravel Soil WANG Qiuyang, XU Baotian, WAN Jiajun 2025, 39 (3):  433-438.  Abstract ( 90 )   Save Throughout the sitespecific investigation, the engineering geological conditions of the Fenghuangshan landslide in gravelly soils in Zhenjiang City are evaluated. Samples were taken for laboratory tests to determine the physical and mechanical parameters of the soil. By using the finite element method, the effects of rainfall, the slope shear strength, and the stiffness on the sliding surface and the slope displacement were evaluated. The analysis results show that the main mechanism of the disintegration deformation of landslides containing crushed stones is the displacement difference between various parts of the landslide during the sliding process, which in turn leads to the formation of micro tensile cracks and ultimately the disintegration. The rainfall is the main factor leading to the disintegration and the excessive deformation of Fenghuang Mountain gravelly soil landslide. The simulation results show that the maximum horizontal displacement of the sliding surface reaches 0.577m and the maximum vertical displacement reaches 0.413m under rainstorm conditions, both of which occur near the slope toe. The maximum horizontal displacement of the slope surface reaches 0.787m and the maximum vertical displacement is 0.312m, both of which occur in the middle and lower parts of the slope. Micro tension cracks may occur at these locations, which may lead to the risk of disintegration and the deformation of the slope. Artificial slope cutting, differences in slope strength, large terrain undulation, and the deterioration of underlying bedrock mechanical properties can all increase the slope displacement and increase the risk of disintegration and deformation. The research results can provide a basis for the investigation and treatment of similar landslides in the region. \= 〖WTHZ〗Key words\ 〖WTBZ〗Landslide In Gravell Soil; Disintegration Deformation; Rainfall 〖WT〗〖ST〗〖HT〗 Related Articles | Metrics

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Study on Scale Effect of Mechanical Properties of Porous Reef Limestone GUO Yuchen, GUO Yunhua 2025, 39 (3):  439-442.  Abstract ( 79 )   Save The porous reef limestone has a unique structure with a biological growth line skeleton, but there has been no related research on its strength and size relationship. Based on the three-dimensional CT scan results of reef limestone, the pore characteristics of reef limestone were digitized, and different-sized numerical analysis models of the porous reef limestone were established to study the relationship between the uniaxial compressive strength of porous reef limestone and its size. The reconstructed reef limestone samples were cubic blocks with sizes of 4cm, 8cm, 10cm, 12cm, and 14cm, and were subjected to uniaxial compression tests that parallel and perpendicular to the reef limestone growth direction, respectively. The results show that there is no obvious scale effect on the uniaxial compressive strength in the parallel and perpendicular to the reef limestone growth line directions, and the failure characteristics are manifested as local plastic deformation of the biological skeleton, which evolves into macroscopic ductile deformation of the structure. Related Articles | Metrics

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Relationship Between Soil Parameters of Deep Soft Clay and Passive Reinforcement Zone in a Deep Excavation Project XU Shuping, WANG Zixuan, KE Qianqian, WEI Zhengping, ZHONG Ming, HU Lei 2025, 39 (3):  443-449.  Abstract ( 91 )   Save In deep excavation sites, due to the engineering characteristics of the high water content and the low strength of soft soils, the excessive deformation of the deep excavation often leads to safety hazards. Therefore, the design concept of the deep excavation strength control has been transformed into a concept of the deformation control of the excavated area. To reduce the deformation of the deep excavation in soft soils, the Hubei Provincial Technical Specifications for Foundation Excavation Engineering (DB42/T159-2012) qualitatively stipulates the use of cement-soil mixing columns to improve the passive zone in a stepped pattern, but no specific theoretical basis is provided for the width and depth of the reinforcement. Based on the strength parameters of soft soils, the width of the excavated area with the added solid is determined using the limit equilibrium method, and the numerical simulation is conducted to analyze the deformation characteristics of the reinforcement area. The relative relationship between the soil layer strength parameters and the width of added solid is obtained, and the feasibility of the adopted reinforcement method is verified by comparing the actual engineering monitoring data with numerical simulation results. Related Articles | Metrics

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Influence Factors of Abandoned Small Coal Mine on Stability of Proposed Construction Project by Using Analytic Hierarchy Process HU Yingquan, WANG Tongbiao, WANG Liuwen, CHEN Jinhong, 2025, 39 (3):  450-454.  Abstract ( 89 )   Save The small coal mines have characterized by small mining depth, disorderly distribution of mined-out areas, and in hidden nature. The distribution area constitutes a complex damaged geology, which brings a great hidden hazard to engineering construction. To explore the main factors of the influence of the abandoned small coal mines on the stability of a proposed project more accurately, this paper takes an abandoned small coal mine of a power plant as the working background and adopts the analytic hierarchy process (AHP) to analyze it. The comprehensive evaluation index system of 12 indexes is constructed, and the weights of each factor are obtained and compared in order of importance. The main factors affecting the stability of the proposed project are the depth of the mine roof, the load of the building and the safety and stability of the coal pillar. The results are generally consistent with the engineering practice. This case history provides a basis for the subsequent evaluation of the stability of the abandoned site of small coal mines. Related Articles | Metrics

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Groundwater Control of Suspended Impervious Curtain in Deep Excavation YAN Shu 2025, 39 (3):  455-458.  Abstract ( 100 )   Save To study the deep excavation with suspended impervious curtain for the groundwater control, a typical Shanghai confined water hydrogeological conditions with deep excavation is presented in this paper. Through a finite element software simulation analysis of the deep excavation in the process of precipitation, the filter tube length, the winding length and the excavation depth are evaluated inside and outside the excavated water level changes. The results show that increasing the winding path within a certain range can reduce the water level outside the excavated area; the “shallow well covering” reduces the length of the curtain during the winding length from 4-13 m. This study can provide a basis for the construction of related projects. It also provides a reference for the construction of related projects. Related Articles | Metrics

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Numerical Simulation Study on the Uniaxial Compression Failure Characteristics of Pre-cracked Sandstone ZHAO Feng, LI Farun, Shang Jichen, ZHANG Xiaoshuo, CHEN Jiayu 2025, 39 (3):  459-463.  Abstract ( 90 )   Save Studying the influence of different fracture inclinations on the failure characteristics of coal-bearing sandstone helps to understand the mechanism of the roof strata caving. By using PFC2D, numerical models of prefabricated fractured sandstone samples with different inclinations were established for the uniaxial compression test numerical simulation. The microscopic parameters were calibrated with macroscopic behaviors to analyze their load damage and mechanical response characteristics. Combined with the evolution of the microcrack distribution, the failure mechanism of the sample was discussed. The results show that as the fracture inclination increases, the damage evolution process and mechanical properties of coal-bearing sandstone differ, and the distribution characteristics and mechanical responses of microcracks also change accordingly. The larger the fracture inclination, the higher the peak strength of the sample during loading failure, and the failure mode tends to be more singular. Combining the distribution characteristics of microcracks, the impact of different fracture angles on the macro and micro failure characteristics of the sample was analyzed. The research results can provide reference value for engineering practice and rock mechanic’s research. Related Articles | Metrics

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Analysis of the Influence of Prestress Loss on Slope Stability in Different Areas WU Libin, LIU Pan, WANG Qingfeng, ZHANG Junxian, SONG Haixiao, MEI Jiwei 2025, 39 (3):  464-468.  Abstract ( 82 )   Save To explore the influence of various working conditions on the stability of a siltstone slope in a project, through the geological investigation of this slope, the strength reduction method in MIDAS GTS NX software was employed to conduct stability evaluations for the two-dimensional slope under the un-reinforced condition and eleven reinforced conditions. By comparing the horizontal displacement, the plastic strain zone, and the stability coefficient under each working condition, the slope stability and reinforcement effect were analyzed. The results show that in the three regions of the slope top, middle, and toe, after applying a prestress of 1000kN to the anchor cable of the reinforced slope, the slope stability coefficient increases to 1.80, and the slope is in a stable state. The ground anchors in different regions of the slope have different impacts on the overall stability of the slope. The prestress of the ground anchor in the toe region is crucial. When the prestress loss of the ground anchor in the toe region is 60%, the maximum horizontal displacement of the slope increases by 146.7%, and the stability coefficient decreases by 27.8%. When considering the reinforcement of prestressed ground anchors during the service period, the ground anchors at the slope toe should be preferentially selected for reinforcement. Related Articles | Metrics

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Experimental and Numerical Simulation Study on Blasting Damage in Reef Limestone Similar Materials GENG Hansheng, MA Linjian, LI Zeng, LI Zhizhong, ZHANG Junnan, LIU Huachao 2025, 39 (3):  469-475.  Abstract ( 112 )   Save Taking the chamber blasting excavation in reef limestone strata as the research subject, this study conducted 7 groups of blasting model tests on reef limestone analog materials. By integrating Digital Image Correlation (DIC) analysis technology, the effects of different blasting methods, charge structures, and borehole layout patterns on the blasting damage characteristics of reef limestone were systematically investigated. The developmental characteristics of blast-induced cracks at various propagation stages under different influencing factors were revealed. Based on the blast contour formation control requirements and borehole spacing parameters obtained from the model tests, a full-scale geometric model was established to perform numerical simulations of chamber blasting excavation in reef limestone strata. The study analyzed the damage range induced by CD method blasting excavation in large-section tunnels and the particle vibration velocity at 30m distance. The research findings can provide technical references for the optimization of blasting methods and parameter selection in reef limestone stratum excavation engineering. Related Articles | Metrics

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Application Dilatometer Tests in Evaluating the Effect of Soft Clay Treatment WU Yuanping, CHEN Longyang, WANG Ziwu, ZHANG Zhaobin, HAO Jiafu, WANG Kun 2025, 39 (3):  476-479.  Abstract ( 71 )   Save To quickly obtain the strength and deformation parameters of the soft soils before and after the ground improvement, and to evaluate the improvement effect of the soils, a case history of soft soil treatment of a major road construction in a city of Xiamen is presented in this paper. Flat dilatometer test method was used to conduct insitu tests in various soil layers within the treatment range. The strength and deformation parameters before and after treatment were obtained, and their variation patterns were studied to evaluate the treatment effect of the soft soils. The results indicate that the material index can effectively classify the properties of each soil layer, and the strength, modulus, and other parameters obtained from the test interpretation can accurately reflect the vertical changes in the properties of the soil layer; Before and after the reinforcement, the material index of the soil layer changes slightly, with a slight increase, while the strength parameters (undrained shear strength) and deformation parameters (lateral expansion modulus, lateral limiting modulus) of the soil layer show different degrees of increase, indicating that the floating soil mixing column treatment has obvious reinforcement and improvement effects on the strength and stiffness of the soft soils. The ratio of strength and deformation parameters of silt, muddy silty clay, and muddy clay before and after reinforcement is greater than 3.0, while the ratio of strength and deformation parameters of the fine sand and the silt interlayer and the fine sand before and after reinforcement is around 2.0. The increase in strength and deformation parameters of soft soil is independent of depth. Related Articles | Metrics

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Numerical Simulation of Direct Shear Tests on Coarse-Grained Soils Using Discrete Element Method GU Yang, ZHUANG Zhikai, WEI Weiqiong, XU Yongwang, 2025, 39 (3):  480-485.  Abstract ( 66 )   Save To study the internal particle motion and the structural change of the coarse-grained soil in direct shear tests, a two-dimensional discrete element numerical simulation method was used to analyze the horizontal motion characteristics of coarse-grained soil particles in the shear process from the microscopic point of view. The influence of the tangential bond strength of the simulated occlusion between particles on the cohesion and internal friction angle of the coarse-grained soil was analyzed. The results show that in the numerical direct shear test of the coarse-grained soil, the relative horizontal displacement of particles at different positions in the shear box is not the same. The coarse-grained soil particles with large relative horizontal displacement form an arctic shear band near the contact surface of the upper and lower shear boxes, and with the increase of the normal stress, the thickness of the arctic shear band also increases gradually. The tangential bond strength of the simulated inter-particle occlusion is positively correlated with the cohesion of coarse-grained soil, and there is no significant relationship with the internal friction angle. Related Articles | Metrics

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Mechanical Characteristics of Gravely Soils Using Field Direct Shear Tests WANG Hongyun, ZHOU Peifeng, WANG Zongkui 2025, 39 (3):  486-489.  Abstract ( 100 )   Save In order to investigate the mechanical properties such as the shear strength and the residual strength of the artificially prepared gravely soils, and to provide a basis for the stability analysis of high fill slopes, the in-situ density tests and on-site direct shear tests are conducted in a large fill slope project to study the density, the shear strength, and the residual strength of the artificial prepared gravely soils with different soil-gravel ratios. The results show that the density of gravely soils is influenced by the content and the particle gradation of crushed stones, and when the content of the crushed stones is high, the density is actually lower. Appropriate control of the particle grading when manually mixing crushed stone soil is beneficial for improving the compactness of the soil mass. The shape of the direct shear stress-shear displacement presents three stages: an upward stage, a gradually decreasing stage after reaching its peak, and a stable stage; The higher the normal stress, the greater the corresponding direct shear displacement at the peak strength for different soil-gravel ratios, and vice versa. Related Articles | Metrics

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Study on Static Characteristics of Basalt Stone Powder-Cement Modified Silty Soils LIN Kaihao, FENG Tianhong, WU Siqi, GU Miaojie, ZHAO Yinuo, LI Na 2025, 39 (3):  490-493.  Abstract ( 110 )   Save The basalt stone powder (BSP) is a waste material produced by quarries in the process of cutting basalt, and the accumulation of large amounts of stone powder not only occupies land but also pollutes the environment and wastes resources. To effectively utilize the BSP, this study used BSP as a modifier in order to prepare the basalt stone powder cement soil (BSPCS). The effect of the BSP content on the hydrostatic properties such as stressstrain, the compressive strength and the modulus of elasticity of the hydraulic soil were investigated by means of the unconfined compressive tests. The results show that the BSP as a modifier can significantly improve the mechanical properties of the hydraulic soil. With the increase of the BSP content, the stress-strain, the compressive strength and the modulus of elasticity of the BSPCS specimens showed a trend of increasing and then decreasing. The best mechanical properties of the BSPCS samples were obtained when the BSP content was 12%. Meanwhile, with the increase of the age of maintenance, the peak strain of the BSPCS specimens was obviously shifted to the left, and the brittleness of the BSPCS specimens increased. However, the mechanical properties of the BSPCS specimens under each specified amount were significantly improved, in which the unconfined compressive strength of the BSPCS-12 specimens could meet the strength requirements of secondary roads and below in the Technical Specifications for the Construction of Highway Pavement Subgrade (JTG/T F20-2015). The conclusion of the study can provide a strong theoretical support for the application of the BSP-modified hydraulic soil. Related Articles | Metrics

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Experimental Study on Mechanical Properties of Coral Sand Solidified by Aluminum Ion Flocculant in Collaboration with MICP GE Xiaohang, GONG Jianwu, 2025, 39 (3):  494-499.  Abstract ( 103 )   Save The microbial induced calcium carbonate precipitation (MICP) is one of the types of research focuses in the field of geotechnical engineering, but its cumbersome treatment steps and low curing efficiency limit its further applications in the curing coral sands. To reduce the number of processing times and to improve the efficiency of the curing coral sands, different concentrations of the aluminum ionic flocculant (AlCl3·6H2O) were added to the cementing solution, and the effects of the aluminum ionic flocculant on the curing speed and curing effect of the MICP were investigated through experiments. The experimental results showed that: after 6 cycles of the grouting treatment, the unconfined compressive strength of the sand column reached 2.8～7.2 times of that of the control group, and the unconfined compressive strength could reach up to 2123 kPa; the introduction of the aluminum ionic flocculant could effectively induce the calcium carbonate crystals generated in the coral sand column to be transformed from unstable spherical chalcocite type to stable calcite type, which significantly enhanced the curing efficiency of the MICP. The results verified the feasibility of the microbial curing technology with aluminum ionic flocculant in the calcareous sand reinforcement scheme for island reefs. Related Articles | Metrics

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Microstructural Evolution and Physicomechanical Behavior of Lateritic Residual Soils in Guizhou Red Beds: A Multiscale Investigation from the Chishui Area YANG Tao, YANG Genlan, LI Saidong 2025, 39 (3):  500-506.  Abstract ( 133 )   Save The residual soil in the red bed constitutes a fundamental material basis for the development of large-scale density-related hazards in its shallow deposits. The physical properties and pore characteristics of this soil are essential for understanding the infiltration and movement of the water within red bed soil slopes to study its physical properties and its vertical porosity characteristics. This study investigates the undisturbed residual soil samples collected at various depths. The mineral composition and microstructure of the soil are examined using the X-ray diffraction (XRD) and the scanning electron microscopy (SEM). Based on these analyses, conventional physical property tests are performed, and the pore characteristics of the soil are subsequently evaluated using the mercury intrusion porosimetry. The findings of this study demonstrate that: (1) The mineral composition of the residual soil in the Chishui Red Beds primarily consists of quartz, clay, potassium feldspar, and hematite. With the increasing of sampling depth, the clay content increases, while the quartz content decreases. (2) As the sampling depth increases, the natural moisture content of the residual soil in the red bed rises, leading to a gradual increase in density. The particle size variation is minimal, and the soil exhibits good gradation. (3) The porosity of the soil gradually decreases with increasing depth. The characteristic curves exhibit similarity, and the trend of the curves clearly shows a distinct boundary point. Based on the comprehensive fractal results and previous research, a suitable boundary pore size value for classifying the pore types of the red bed residual soil is proposed: pores smaller than 0.05 μm are classified as the intragranular pores; those between 0.05 and 0.35 μm are classified as the micropores; pores ranging from 0.35 to 3.5 μm are identified as the small pores; those from 3.5 to 25 μm are classified as the medium pores; and pores larger than 25 μm are categorized as the large pores.  Related Articles | Metrics