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31 October 2025, Volume 39 Issue 5 Previous Issue   

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Application of PC Pile Method in a Subway Station Auxiliary Structure Construction in Soft Soils ZHU Shangming, ZHANG Wen, SONG Zhaoping 2025, 39 (5):  683-686.  Abstract ( 219 )   Save As a new green excavation supporting system, the PC (Pipe-Combination) pile method is widely used in construction in Shanghai and Zhejiang, but its application and research results in subway station construction are still rarely reported. Based on the design and construction characteristics of an auxiliary structure of Fuzhou Metro station and the construction principle of the PC pile method, this study analyzes the key and difficult aspects of the construction of PC pile method in the auxiliary structure of metro station in soft soils by means of theoretical research, field application, monitoring and measurement. The key aspects of the PC pile methods are also introduced. Practice has proved that, compared with the traditional subway supporting structure, the PC pile method improves the comprehensive benefits of the construction progress, quality, environmental protection and cost by nearly 20%. This method positively responds to the national “double carbon” strategic goal and has a wide range of application value in other excavation supporting projects. Related Articles | Metrics

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Application of Steel Perforated Pipe Grouting in Settlement Mitigation of a Steep Embankment Slope LAI Yinnan, GUO Shen 2025, 39 (5):  687-691.  Abstract ( 144 )   Save This paper presents the case history of an expressway high embankment settlement mitigation by the steel perforated pipe grouting method. The grouting results are numerically simulated by MIDAS GTS commercial software under three different conditions: namely, only considering the effect of steel pipe, only considering the effect of grouting, and considering the combinations steel pipe and grouting. The results show that: the reinforcement effect of grouting steel perforated pipe on the embankment is composed of steel pipe and grouting soil, and the effect of the two components on the controlling embankment settlement are similar. In addition, the steel perforated pipe mainly plays the role of the soil nail, and its effect decreases with the improvement of grouting effect. Related Articles | Metrics

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Analysis of Influence of Deep Excavation on Subway Tunnel Structure in Complex Environment LI Jiaping, LEI Dan, YANG Shifei, YUAN Zhao, 2025, 39 (5):  692-698.  Abstract ( 127 )   Save With the increasingly complex development environment of the urban underground space, the impact of the deep excavation project near the subway on the operation of the tunnel has also attracted much attention. Based on a deep excavation project near a subway in Shanghai, the measured data of the tunnel deformation are evaluated during the construction process. The influence of the upper building on the tunnel deformation is analyzed by the numerical simulation method, and the subsequent construction is also predicted and analyzed. The research shows that when the excavation depth of the foundation is less than the tunnel waist embedment depth, the “horizontal laid duck egg” deformation trend is inclined upward near the tunnel. Due to the thixotropy of the soft soil, the influence of the buildings above the tunnel on the tunnel deformation during the deep excavation construction cannot be ignored. During the process, the impact of followup construction is tracked and predicted, and the lateral microdisturbance grouting method is timely adopted at key nodes to effectively control the deformation of the tunnel. This study provides reference for similar engineering cases. Related Articles | Metrics

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Design and Construction of Deep Excavation Supported by Double-Row Cantilever Piles (DCP) Using Sequential Method (SM) SONG Dawei, ZHU Yifei, LAI Yunjin 2025, 39 (5):  699-704.  Abstract ( 133 )   Save The deep excavation of an underground parking lot at Wujin Station (namely Wujin Project), a comprehensive transportation hub which is an inter-city station of the south express railway alongside Yangtze River. The construction is a super-large one with footprint area of about 39,500 square meters, with an excavation depth of 11.2 meters and periphery of about 980 meters. The excavation is supported by the double-row cantilever piles (DCP) using sequential method (SM). The principle of the SM is based on the Space-time Effect theory. For a deep excavation project, it is very important to select a reasonable length of sequential block to control the displacement of the retaining wall. To minimize the displacement of the double-row-piles retaining wall, a sequential method is introduced for the excavation of Wujin Project, for which a calculation model is established to analysis cases with different length of sequential block with consideration of Wujin Project’s retaining wall and geological conditions. The result shows that there is a critical length (CL) and that when the length of sequential block is less than CL, the displacement of the retaining wall is very sensitive to the length of sequential, otherwise is irrelevant to it. Related Articles | Metrics

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Monitoring Analysis and Model Prediction of a TRD formed Diaphragm Wall ZHU Chunlai 2025, 39 (5):  705-710.  Abstract ( 110 )   Save In the process of construction of a diaphragm wall, the disturbance of soil mass will have an influence on the wall and adjacent buildings. To explore the action mechanism of construction on the wall and adjacent soils, this paper presents the case history of a deep excavation project in Fuyang District of Hangzhou. The design of the deep excavation supporting structure is introduced. Based on the geotechnical investigation report, the horizontal displacements of soils, the lateral displacement of the underground diaphragm wall, the lateral displacement from corner to center, the relationship between the maximum deformation value of the underground diaphragm wall and the excavation depth during the deep excavation construction are systematically analyzed. The results show that the horizontal displacement of the diaphragm wall shows the characteristics of spatial effect. TRD formed cement soil mixed wall has satisfactory groundwater sealing effect and excellent impermeability. The lateral deformation expression of diaphragm wall is derived. The research results can provide a reference and guidance for the design and construction of TRD formed diaphragm wall in the future. Related Articles | Metrics

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Application of a Jacked Super-Long Reinforced Concrete Pile in Foundation Reinforcement ZHANG Ming, A Ying 2025, 39 (5):  711-714.  Abstract ( 92 )   Save Due to the quality issues of the pile foundation construction in a high-rise residential project, the axial bearing capacity of many piles are tested could not meet the design requirements, so the piled raft foundation needs to be reinforced. Considering the structural safety, the rationality of construction plan, construction feasibility, construction schedule and other aspects, this project is decided to adopt the reinforcement scheme of using Jacked Super-long Reinforced Concrete Pile. The concept innovatively adopts the mechanical connection pile joint. Throughout the low strain integrity detection and the load test verification, the results show that Jacked Super-long Reinforced Concrete Pile has a satisfactory effect of sharing the original foundation load. The axial capacity of the jacked pile and the settlement of the building tend to be stable. Further, the installation construction method is relatively simple, which can meet the needs of soft soil foundation reinforcement. The mechanical connection pile joint is safe and reliable, and the construction schedule can be greatly shortened; This conclusion can provide a reference for the design and construction of foundation reinforcement of similar projects. Related Articles | Metrics

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Application of High Efficiency Magnesium Cement Agent to Solidify Dredged Sludge ZHANG Xiaolong 2025, 39 (5):  715-719.  Abstract ( 193 )   Save The river dredging projects will produce a large amount of silty and peaty dredged sludge every year, the traditional physical dehydration and landfill cannot permanently solve the characteristics of high silty peaty clay content and high compression rate, so the silty peaty dredged soils should be solidified. The currently widely used Portland cement has the disadvantage of large amounts of hydration and high heat release. To minimize the cost of solidifying dredged sludge and to reduce carbon emission, this paper adopts magnesium oxychloride cement combined with other additives derived from the solid waste material as the curing agent of dredged silty peaty soils from river channels. Based on the physical and mechanical properties of solidified soil, the effects of different amounts of composite magnesium oxychloride cement curing agent on the Atterberg limits and unconfined compressive strength of dredged sludge samples are explored. A reference group with and without naphthalene series C superplasticizer was set up. The results show that the addition of the curing agent can significantly reduce the water content of the silty peaty soils. With the increase of the curing agent, the liquid limit of the solidified samples gradually increases, the plastic limit gradually decreases, and the plastic index decreases. Moreover, the strength of the solidified silty peaty soils reaches 266kPa when the addition of the curing agent is 10%. However, it has a decreasing effect on the strength, but overall, the waterreducing agent can effectively improve the curing effect of magnesium cement solidified soil. Related Articles | Metrics

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Analysis of Deformation and Failure of an Anticline Cutting High Slope in a Guangxi Expressway TAI Lianhuan 2025, 39 (5):  720-724.  Abstract ( 114 )   Save The deformation and failure mode of an anticline cutting high slope in Guangxi during the construction process are presented in this paper. The main influencing factors of slope toppling deformation are evaluated through the field geological survey and deformation test data. On this basis, a Phase2 finite element analysis model is established. The deformation morphology, sliding surface evolution and deformation development during the construction process are studied, and the deformation and failure evolution process of the slope are presented. The results show that from the perspective of geological structure, the anticline rock stratum is the main influencing factor of toppling deformation and failure. The interface between the strongly weathered and the moderately weathered rock strata controls the depth of sliding surface. The safety factor of the slope after excavation is 1.09, and the sliding surface is in an unstable state with the slope toe exposed and the slope top intact. In the process of excavation, the strong and medium weathered interface occurs dislocation deformation, and the anticline layer is toppled and slipped, which leads to the stepshaped deformation morphology of the slope surface. With the excavation, it gradually develops to the toe of the slope, which eventually leads to the toppling deformation failure mode of the slope. The slope is a toppling-traction failure mode. Its development and evolution process is excavation disturbance-rock interface dislocation-anticline layer toppling-lower deformation sliding-traction cracking upper-toppling deformation failure. Related Articles | Metrics

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Analysis of the Anti-Slide Caisson Design of Slope Near Buildings ZENG Majun, 2025, 39 (5):  725-729.  Abstract ( 84 )   Save The anti-slide casino is one of the commonly used measures for slope stabilization. Owing to its advanced theory and well-developed construction plans, it is extensively applied in the mitigation of high and steep slopes and landslides across various sectors, including transportation, water conservancy, construction, railway, municipal engineering, and geological hazard mitigation in practical engineering applications. This article presents the slope stabilization project associated with the relocation of the First Middle School in Dafang County, Guizhou Province. The geological conditions and a comparative analysis of the functions of three support design options: anti-slide square caissons, prestressed anchored anti-slide square caissons, and prestressed anchored anti-slide circular caissons are introduced with focusing on the lateral capacity. The paper further discusses the economic advantages and disadvantages of these three options within the transportation industry's standards. Lastly, the article examines the differences between theoretical design and practical application, along with the potential uncertainties in the application. The comprehensive and systematic overview of the design process for anti-slide caissons offers significant reference value to related engineering projects. Related Articles | Metrics

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Analysis and Mitigation Study of a Landslide on a Highway Embankment After Rainfall WANG Chenqi, ZHOU Jin 2025, 39 (5):  730-733.  Abstract ( 133 )   Save During the operation of an expressway in East China, several sections of highway slides are observed at embankments after the typhoon induced rainfall. Through comprehensive evaluation on the engineering geological characteristics of the embankment area, the deformation characteristics of the embankment slide, and the development of cracks, the causes of the embankment sliding hazards in this section are analyzed. By using the Geo-Slope commercial software to evaluate the stability of the embankment in this section and combining with the basic data of geological exploration and design, the shear strength parameters of the bedrock and soil are obtained. Based on the emergency mitigation requirement of rescue and hazard relief, after the stability evaluation to meet the relevant code requirements, a comprehensive mitigation plan of “two-level flat platform back pressure at the foot of the slope + optimization of embankment drainage + strengthening of pavement structure” was finally adopted. After the continuous follow-up and on-site investigation, it was found that the road has been operating safely for nearly four (4) years after the hazard treatment, and the overall stability of the embankment is satisfactory. Similar engineering projects can refer to the treatment for embankment hazards. Related Articles | Metrics

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Innovative Application of Multi-Layer Strut-Type Internal Support in Ultra-Deep Excavations LIU Nanchang 2025, 39 (5):  734-737.  Abstract ( 172 )   Save The surrounding environment and geological conditions at the proposed project site are complex. The project is adjacent to a subway and an existing deep excavation site. Furthermore, there are ultra-deep foundation excavations with large-span length and large slenderness ratio of the supporting structure sections between two adjacent excavations. The deformation control of the current deep excavation is restrictive, and the technical difficulty is significant. These requirements posed a severe challenge to the foundation excavation supporting designers. The selection of supporting structures is crucial for the success of deep excavation design and construction. This article takes a deep excavation support design of the China Merchants Bank Global Headquarters Building as an example to study the innovative application of the multi-layer strut-type internal support in the supporting design of the ultra-deep excavation with large-span length and large slenderness ratio of the supporting structures. The successful application of this design not only resolves the stiffness problem of the large span length and large slenderness ratio of the supporting structure as well as the transmission and balance of lateral soil pressures, but also effectively controls the deformation of the deep excavation, ensuring the safety of the excavation supporting structure and the surrounding environment. Related Articles | Metrics

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Influence of Deep Excavation on the Deformation of Underlying Metro Tunnel YANG Bo, YANG Yang 2025, 39 (5):  738-742.  Abstract ( 88 )   Save With the rapid development of urban surface roadways and underground rail transit traffic, the influence of deep excavation on the existing underlying subway tunnels is becoming increasingly prominent. A roadway deep excavation project in Chengdu area is presented in this paper. A three-dimensional numerical model is established by using software FLAC3D to predict the influence of roadway deep excavation on the underlying underground subway tunnel. The results indicate that the unloading of deep excavation results in the change of displacement and stress fields. The upheave deformation and the lateral displacement of tunnel are observed. The backfilling and compacting of the excavation also induce the settlement and deformation of the tunnel. The tunnel is deformed by the tension and the compression towards the open surface. The tunnel is deformed in the shape of ellipse with the short side in transverse direction and the long side in vertical direction. When the soil cover of the tunnel is shallow, the roadway compaction conditions has a significant effect on the tunnel deformation, and the grouting improvement can better control the tunnel deformation. Related Articles | Metrics

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Investigate on the Failure Mode of Spread Footings on High Stiffness Subgrade Using Hybrid Finite-Discrete Element Method CHENG Shufan, 2025, 39 (5):  743-749.  Abstract ( 110 )   Save The spread footing is one of the simplest foundation types, whose failure mode is related to both self-construction and the mechanical properties of the subgrade material. The failure mode of spread footings on high stiffness ground such as bedrock may be different from those on soil. The failure process of vertically loaded concrete foundations was numerically simulated by the two-dimensional hybrid finite discrete element method (2D-FDEM). The influence of the foundation thickness and subgrade stiffness on the bearing capacity and the failure mode of the spread footing has been studied in this paper. The results show that: (1) the vertically loaded concrete spread footing mainly experiences the punching shear failure. With the increase of foundation thickness, the angle between the failure surface and the vertical direction decreases slightly and tends to be constant, which means that the failure mode changes from the punching to the shear failure. (2) The base pressure of the spread footing on the high stiffness subgrade is parabolic distribution or in a inverted bell distribution. Meanwhile, as the stiffness of the foundation subgrade increases, the non-uniformity of the base reaction also increases. (3) The FDEM model can simulate the formation process of failure surfaces, which is hard to achieve by finite element method (FEM). Compared with the structured mesh, the simulated shape of the punching cone and the location of the failure surface are more accurate in the model using unstructured mesh, such as Delaunay triangle mesh. Related Articles | Metrics

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Numerical Analysis of Deformation and Damage Process of a High Cutting Slope in a Guangxi Expressway ZHANG Hongxing, LENG Xianlun, 2025, 39 (5):  750-753.  Abstract ( 151 )   Save To study the deformation and failure process and hazard occurrence mechanism of a high cutting slope in Guangxi is presented in this paper. The rock strata, joint occurrence and deformation as well as the failure range and mode of the slope environment were determined through on-site geological survey, and then Phase2 software was used to establish a numerical analysis model that can reflect complex geological characteristics. The deformation and failure characteristics of the slope under the control of bedding and joints were evaluated. The results show that the dip joint is the main geological factor of slope deformation and instability. The tension cracks and rainfall infiltrations are the main causes of slope deformation and failure. The hazard process is excavation disturbance-joint tension-rainfall infiltration-rock mass weakening-joint tension displacement-deformation and failure. The construction disturbance caused the joint to be in a state of tension crack. Due to the rock anchor support, the deformation and failure did not occur on the slope surface. At this time, the factor of safety of the slope was 1.07; the rainfall infiltration leads to the weakening of the strength of strongly weathered siltstone, and the J1 joint further cracks and slips, and forms a shear slip zone along the interface between the layer and the joint and rock layer, and finally cuts out at the intersection of strong weathering and slope. Related Articles | Metrics

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Influence of Impact of Rockfall Collision on the Stability of Rock Mass Toppling XU Sifa, XU Hongji, SHI Kaifeng, SUN Changyi, HU Huijing, WANG Zhe 2025, 39 (5):  754-759.  Abstract ( 86 )   Save The collapse of dangerous rock mass is one of the key problems in the field of geological hazards. At present, most of them evaluate the stability of dangerous rock mass from the perspective of limit equilibrium and fracture mechanics. In this paper, considering the impact force of rockfall collision, an estimation method for the stability coefficient of dangerous rock mass under the rockfall impact is proposed, and the stability coefficient of toppling dangerous rock mass is evaluated by using the limit equilibrium method and numerical analysis. The results show that the trends obtained by theoretical estimation and numerical simulation analysis are consistent. The stability coefficients under natural, rainstorm and rockfall impact are 4.85, 1.21, 0.78 and 2.2, 1.11, 0.8 respectively; The rainstorm and rockfall impact have a great impact on the stability of dangerous rock mass. The stability coefficients obtained from theoretical analysis and numerical analysis under rainstorm conditions have decreased by 75% and 54% respectively compared with the natural conditions; The stability coefficient decreases by 84% and 65% respectively under the action of rainstorm and rockfall impact. The research results can provide reference for the stability evaluation of similar projects. Related Articles | Metrics

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Semi-Theoretical Models on the Jet Grout Column Diameter Prediction Using Bayesian Framework XIE Yidong, LI Shanqing, ZHU Yuqing, XU Chao 2025, 39 (5):  760-763.  Abstract ( 85 )   Save The jet grout method is popular in soil improvement projects, such as dams and tunnel foundations etc. due to its cost efficiency and quick construction. The estimation of the column diameter of the jet grout is much more significant at the design stage. In this study, three optimal models with explicit formulas were established to predict the diameter of jet grout columns based on a comprehensive database summarized from different case histories around the world. The Bayesian model selection was used to determine the best model related to the three popular jet grout systems (i.e., single, double, and triple), respectively. The 95% credible intervals were estimated at the same time and the estimation on the column diameter of jet grout using the proposed models agrees well with the measured ones in practical projects. It is concluded that, except for the jet grout energy, the soil type has a significant influence on the diameter prediction of jet grout columns. Related Articles | Metrics

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Numerical Simulation of Deep Excavation Support Adjacent to Subway Station MENG Limin 2025, 39 (5):  764-770.  Abstract ( 90 )   Save With the continuous construction of newly planned subway lines, the deformation control requirements for adjacent subway stations in the construction of deep excavations for buildings are becoming more stringent. The design of a deep excavation adjacent to a subway station in Huangpu District, Guangzhou, is presented in this paper. A three-dimensional model is established to numerically simulate and analyze the excavation of the deep excavation site under multiple working conditions. The analysis results show that the most unfavorable working condition is when the excavation reaches the bottom (before replacing the support). The rigidity of the supporting structure in the northeast and southeast corners of the excavation is relatively weak, and the supporting system is more stable after strengthening with the addition of large triangular corner braces (beam slab combination). Except for the construction defects of the water cut-off curtain caused by the old foundation obstacles on the site, which resulted in the measured values of the WY7 and ZC6 monitoring points on the east side being greater than the calculated values, the calculated values of the horizontal displacement of the top of excavation and the internal support axial force of the other monitoring points are close to the measured values and less than the design control values. The monitoring data of the station tunnel during subway operation also indicates that the tunnel structure is in a safe state. Related Articles | Metrics

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Influence of Cut-Off Wall Parameters on the Deformation and Seepage Stability of the Deep Excavation PENG Lin 2025, 39 (5):  771-774.  Abstract ( 159 )   Save In response to the instability problem of support structures caused by seepage deformation coupling in deep excavation engineering in soft soil areas, a three-dimensional deep excavation model was established using Plaxis3D finite element software with a project in Jiangsu Province. The influence of the depth and width of the water cut-off wall on the deformation and seepage stability of the soldier pile was studied. The results show that the depth and width of the water cut-off wall exhibit a significant nonlinear threshold effect on the performance of the deep excavation supporting structures. When the depth is ≥20 m and the width is ≥0.8 m, the horizontal displacement of the soldier pile decreases by more than 30%, and the seepage velocity synchronously decreases by more than 70%. However, as the depth and width of the water cut-off wall further increase, the decrease in the horizontal displacement and seepage velocity of the soldier pile is limited; Based on the standard limits, the critical depth of the curtain is 19.0 m and the critical width is 0.68 m. The results provide theoretical basis and parameter optimization methods for seepage cut-off design of the deep excavations in soft soils. Related Articles | Metrics

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Nonlinear Contact Pressure of Crawler Beams based on Winkler Model CHEN Bin, MO Pinqiang, LIU Yao, LI Jiacheng, LI Yucheng, LIU Qingnan 2025, 39 (5):  775-762.  Abstract ( 137 )   Save Following the growing demand for foundation safety requirements of heavy-duty equipment in large-scale engineering construction, the precise prediction of the ground pressure is crucial for the foundation stability during crawler crane operations. Based on the Winkler elastic foundation theory, this study constructs an elastoplastic foundation reaction coefficient through piecewise fitting of p-y curves and establishes a nonlinear ground pressure prediction model for track beams. Predictions and engineering measurements demonstrate the following: As lifting loads of a crawler crane increase, the load eccentricity significantly elevates the ground pressure on the eccentric side, inducing the plastic deformation and the subsequent dramatic settlement, while the non-eccentric side may experience detachment due to the stiffness differences between the track beam and the soil. During the slewing angle adjustment, the settlement at the left end of the left track continuously decreases, while the right end first increases then decreases; conversely, the left end of the right track initially decreases then increases, with the right end exhibiting sustained uplift. Settlement distributions strictly follow a symmetrical pattern around the track midpoint, systematically revealing foundation displacement characteristics under the eccentric loading. This model provides a reliable theoretical basis for the crawler crane foundation design. Related Articles | Metrics

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Numerical Simulation Study on Combined Support Technology for Ultra-Shallow Buried Tunnels Excavation in Soft Soils HAN Longwei, ZHOU Shudong, HUANG Zehang, ZHAO Wenping, PAN Da 2025, 39 (5):  783-789.  Abstract ( 110 )   Save The underground excavation and expansion of ultra-shallow-buried tunnels pose notable risks to construction safety since the minimal soil cover readily triggers crown instability and excessive ground subsidence. This paper presents a case history of a tunnel expansion project in Nanshan District, Shenzhen. The study evaluates the effectiveness of a combined advanced supporting system that integrates a piped-roof (umbrella arch) with forepoling using pilot small-diameter grouted pipes under ultra-shallow cover conditions. A three-dimensional numerical model was developed by using MIDAS GTS NX to simulate and to compare the deformation of the surrounding rock mass as well as the evolution of the ground subsidence under three supporting conditons: (i) single pipe-roof support, (ii) single advanced forepoling support, and (iii) the combined system. The comparative results indicate that the combined technique can take the advantage of the “beam effect” of the pipe-roof while simultaneously improving the soil using grouting through the forepoling pipes, thereby improving the overall stiffness and the load-bearing capacity of the support system. Quantitatively, the maximum crown settlement achieved with the combined support is 9.44 mm, which corresponds to reductions of 55.3% and 71.7% relative to the single pipe-roof case (21.14 mm) and the single advanced forepoling case (33.34 mm), respectively. These findings, derived from a consistent three-condition comparison within the same modeling framework, substantiate the practical advantages of the combined advance support for mitigating deformation and settlement risks in ultra-shallow settings. The outcomes provide a clear theoretical basis and operable technical references for the design of advanced supporting systems in similar tunnel expansion projects conducted by underground excavation. Related Articles | Metrics

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Comparative Analysis of Machine-Learning-Based Stability Prediction for High Steep Slopes HONG Jun 2025, 39 (5):  790-794.  Abstract ( 162 )   Save To address the complexity of the stability prediction for high-steep slopes at tunnel portals, an intelligent prediction model based on multi-source information fusion is proposed in this paper. The model integrates three machine-learning algorithms, namely, support vector machine (SVM), artificial neural network (ANN) and random forest (RF). The model builds a dedicated data set of 100 tunnel-portal slopes worldwide. It covers features such as slope height, slope angle, rock-mass strength parameters and geological structures (joints, fractures, faults), enabling intelligent stability assessment. Results show that the random-forest model performs best, with a superior accuracy and recall; feature-importance analysis indicates that the slope angle, pore-water pressure and internal friction angle are the key controlling factors. The SVM model achieves 93 % accuracy but limited generalization, whereas the ANN model reaches 97 % accuracy yet suffers from over-fitting. The study provides reliable decision-support for tunnel-engineering risk prevention and control; future work can further enhance its value through data expansion, model ensemble and real-time monitoring system optimization. Related Articles | Metrics

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Pile Integrity Testing Methods Based on Wave Theory ZHANG Lifeng, YUAN Pengju, HAO Jiafu, YANG Haibin, ZHI Liyuan, QI Songsong 2025, 39 (5):  795-798.  Abstract ( 83 )   Save With the continuous development of China's construction industry, the number of pile foundations used in the construction process of infrastructure projects is very large. The construction quality of the pile foundations is also very important, which directly affects the safety and stability of the overall building structure. For building construction, once the construction is completed, the pile foundation will become a hidden underground object, which cannot be directly tested for their integrity. Therefore, the quality inspection of the pile foundation is an important index to measure the safety and stability of buildings. In this paper, the quality of pile foundation is evaluated based on the detection principle of transmission wave method of side borehole, and the factors that may affect the wave velocity in the pile are analyzed. It can be concluded that changing the radius of soil around the pile by reflection wave method has little effect on the analytical result of the wave velocity. The wave velocity distribution of the pile measuring point is evaluated as inverted V shape by Δx/Δt method. For different pile lengths, the wave velocity distribution at measuring points of the pile shaft is calculated as V-shaped by reflection wave method. The change of the pile length by reflecting wave method has little effect on the analysis result of the wave velocity, and the velocity is basically unchanged. The wave velocity distribution of the pile measuring point is evaluated as inverted V shape by Δx/Δt method. Under the condition of the weak building contact, the changing the friction coefficient of pile and soil has little effect on the wave velocity in the pile, that is, with the change of the friction coefficient between the pile and the soil, the wave velocity in the pile changes little. Related Articles | Metrics

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Experimental Study on the Strength Characteristics of Tianjin Binhai Shallow Soft Soil Improved by Lime GAO Zhibin, WEN Shengliang, REN Jianxing, JI Shengwei 2025, 39 (5):  799-802.  Abstract ( 91 )   Save How to deal with the waste soil is a difficult problem in the large deep excavation projects. It is particularly difficult to excavate and reuse the shallow soil in coastal areas. This paper presents a case history of an airport engineering project in Tianjin. A large number of tests were performed on the samples of Tianjin Binhai soft soil with depths less than 15m and mixed with slaked lime. Based on analyzing the basic properties of the natural soil, the compaction characteristic of soil samples containing 0%,8%,15% and20% slaked lime was discussed. Meanwhile, the consolidated quick direct shear strength and the unconfined compressive strength of soil samples with various mixing lime ratios and degrees of compaction of 0.90, 0.93 and 0.96 were studied. The strength characteristics of the Tianjin Binhai shallow soil mixed with the slaked lime are further evaluated. It provides a reliable reference for the design and construction, when the shallow soil from the deep excavation uses in the site backfill, road backfill, and utility trench backfill. Related Articles | Metrics

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Experimental Study on Axial Uplift Characteristics of Piles with Various Interface Roughness WANG Zizhao, XIAO Fengyu, WANG Zhiwen, DING Ruiheng, WANG Zhihao 2025, 39 (5):  803-806.  Abstract ( 94 )   Save As an anti-floating structure, uplift piles are widely used because of their bidirectional axial resistance characteristics. However, the influence of interface roughness on the axial performance of uplift pile remains to be further explored. Based on the in-house pull-out test platform, an aluminum model pile was used to conduct the pull-out model test under monotonous load in dense medium and coarse sand. The strain of the pile was obtained by the strain gauge attached to the shaft of the model pile. The test results show that the model pile with Horvath interface roughness factor of 0.124 is the most similar to the grouted cast-in-place bored piles. The load-displacement of the uplift pile can be divided into three stages: namely, pre-peak growth, post-peak softening and residual stage. Both interface roughness and overburden load are beneficial to increase the ultimate axial capacity of pull-out piles. Increasing interface roughness can effectively slow down the strain softening rate, and increasing overburden load can effectively increase the residual bearing capacity of pull-out piles. The peak axial force of various sections of the uplift pile is synchronized. The axial force of each section decreases with the increase of depth, and the decreasing rate tends to expand. According to the pile soil interface, the pile shaft resistance distribution can be divided into three types: gradually increasing, first increasing and then decreasing, and continuous increasing. The increase of overburden load can improve the position where the maximum shaft resistance is exerted. Related Articles | Metrics

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Optimization of Solid WasteBased Composite Stabilizer Formulations and Study on the Stabilization Mechanism of Marine Soft Clays WANG Xiaodong, ZHANG Xin 2025, 39 (5):  807-810.  Abstract ( 139 )   Save The resource utilization of marine soft clay is of great significance for enhancing the value of land resources in coastal areas, ensuring the construction projects and achieving green and low-carbon disposal of industrial solid waste. To address the challenge of the stabilizing marine soft clay and to promote the resource utilization of industrial solid wastes, this study developed a composite inorganic stabilizer using coal gangue and fly ash as base materials, and quicklime and sodium silicate as activators. A D-optimal mixture design was employed to optimize the formulation, while SEM, EDS, and PCAS analyses were conducted to investigate the microstructural stabilization mechanism. The results show that at the optimal proportion (coal gangue: fly ash: quicklime: sodium silicate = 0.05:0.30:0.25:0.40), the unconfined compressive strength (UCS) of the stabilized soil reached 692.94 kPa after 28 days. The stabilization mechanism involves the alkali-activated pozzolanic reaction generating C-S-H gels and related products, which fill and densify the soil pore structure, reducing the porosity ratio from 33.1% to 9.58%. This research provides both an effective formulation and theoretical basis for the application of solid waste-based stabilizers in soft soil improvement. Related Articles | Metrics