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29 February 2024, Volume 38 Issue 2 Previous Issue    Next Issue

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Deformation and Stress Response of Caisson Lifting and Sinking Lock Ring Beam WU Yizhu, SHI Wenhao, FAN Lvye, 2024, 38 (2):  163-168.  Abstract ( 138 )   Save The sinking process of the traditional open caisson construction is uncontrollable and is greatly influenced by the soil stratigraphy and the excavation method. The active control of the sinking state by the lifting and sinking of the open caisson can effectively solve a series of problems, such as, sudden sinking and over sinking in the sinking process in the traditional soft soils. However, during the lifting and lowering process, the lock ring beam outside the well needs to resist the upper lifting reaction force, and its mechanical behavior is not clear. This paper presents a case history of an underground intelligent parking garage project of Kunshan Forest Park. A mechanical model of lifting and locking forces is established according to the characteristics of the open caisson lifting and sinking construction. By using the threedimensional finite element simulation, the deformation and stress changes of the lock ring beam during the lifting and lowering of the open caisson are evaluated. The results show that there are differences in the convergence deformation of the lock structure during the lifting and sinking process. It expands upward and contracts outward along the downward direction, and transits from circular to oblong shape along the radial direction; During the sinking process, the settlement at the outer edge of the lock ring beam is the largest. With the sinking of the open caisson, the influence range of surface settlement decreases to both sides along the lifting system, and the influence range is 0.6~1.1 times of the sinking depth; Before sinking, due to the reinforcement of the local soil at the lower part of the caisson lock, the stress concentration occurs at the contact corner edge with the lock mouth beam, the structure should be strengthened at this location in the design. Related Articles | Metrics

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Application of Anchored Static Pressuring Pile Combined with Column Interception Method in Tilted Building Restoration WANG Chuanyu, ZHANG Qinyu, WANG Xiao 2024, 38 (2):  169-173.  Abstract ( 86 )   Save In the coastal areas of the Yangtze River Delta area, the soil improved composite ground is the most widely used foundation type for the multi-story residential buildings with a total height below 24 meters. Due to its special geological and geotechnical environment, there are occasional differential settlements occurred after the completion of these residential buildings.  To mitigate the differential settlements in these buildings, the conventional improvement methods usually have a long construction duration and are often costly. This paper presents a case history of a tilted existing residential building restoration in Qidong City, Jiangsu Province by using the anchored static pressuring pile combined with interception pile method. The existing building was improved by soil-cement mixing columns. Throughout the planned interception of the existing soil-cement columns, this method can restore the tilting and at the same time, significantly reduce the construction duration and the cost. From the construction monitoring data, this combined method can be applied in the buildings on the composite ground with a total height less than 24 meters. Related Articles | Metrics

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Stability of Deep Excavation of a Metro Station in Coastal Karst Terrain YANG Fugang, SHAO Pichun, XU Huaizhong, LIU Jingxu, REN Kun, BAI Haifeng 2024, 38 (2):  174-177.  Abstract ( 89 )   Save To study the influence of karst rock cavity distribution and morphology on the stability of the supporting structure for a deep excavation as well as the ground settlement, a three-dimensional finite element model for the excavation engineering is established by using the commercial software Midas GTS NX. The influence of karst rock cavity diameter, locations, and in-fill material on the stability of the supporting structure it is analyzed. The results show that, when the distance between the karst rock cavity and the edge of excavation support is fixed, the maximum lateral displacement of the soldier piles and the maximum ground settlement gradually increase with the increase of karst rock cavity diameter. With the increase of the distance between the karst rock cavity and the supporting structure, the influence of the karst rock cavity on the lateral displacement of the soldier piles gradually decreases. The surface settlement caused by the karst rock cavity increases first and then decreases. The large-diameter karst rock cavity has an obvious influence on the in-fill material state and the stability of the supporting structure which needs to be grouted in time. The importance ranking of the influence of the karst rock cavity on the stability of the supporting structure is as follow: karst rock cavity diameter > karst rock cavity location > karst in-fill materials. With the increase of the deep excavation depth, the differential settlement of buildings surrounding the excavated area gradually increases, but the increase rate of the deformation gradually slows down and tends to be stable. Related Articles | Metrics

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Improvement of Shielded Tail in Full-Section Saturated Sand Strata ZHANG Wei, XIA Xiaoqian, CHEN Shaolin, SUN Heng, HUANG Xinmiao 2024, 38 (2):  178-180.  Abstract ( 110 )   Save The unreasonable arrangement of grease holes at the shielded tail is easily to cause serious wearing of the tail brush at areas with too large spacing, resulting in fixed slurry leakage locations, which might seriously threaten the safety of shielded tunnel construction. To mitigate for this defect, a construction project case history between the Big Data Station and the Binhai-Xincheng Station in Fuzhou Metro Nearshore Express Line is presented in this paper. Firstly, reasons for the shielded tail improvement as well as the water stop grouting reinforcement before the improvement are introduced in detail. Secondly, different shielded tail on-site improvement alternates are compared from risk, construction duration and cost aspects. The result shows that the alternate of designing a special tail brush and welding with the external hot rolled steel is obviously better than other options. Through the above measures, the shielded tail on-site improvement is successfully completed in a safe and efficient manner under a no-water condition. The new grease holes can normally pump grease into the cavity, greatly improve the safety of the subsequent construction. The relevant experience learned in this project can provide a reference for the subsequent similar projects. Related Articles | Metrics

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Analysis of Seepage Stability and Dewatering Effect on the Suspended Impervious Curtain in the Deep Excavation for a Vertical Shaft in a Highly Permeable Stratum HE Wei, HAI Han, ZHAN Yuan, CHEN Xiaoxiang, GONG Jianwu, LI Yijiang 2024, 38 (2):  181-185.  Abstract ( 114 )   Save This paper presents a case history of a cut-and-cover deep excavation for a DN3500 power project in Xi’an where the pipe jacking initiation working shaft. Through theoretical analysis, the influence of the suspended impervious curtain on the seepage stability in the sandy soil and other highly permeable strata is evaluated. And then, the influence of different groundwater control options, such as, water collection and open drainage, dewatering of pipe well points in the pit and dewatering of tube wells outside, on the deformation of the soldier pile in the deep excavation and the soil outside the excavation area are studied. The lateral earth pressure of the soldier pile can improve the safety of the excavation, but compared with the dewatering inside the excavated area, the use of the dewatering outside the pit will significantly increase the settlement of the surface outside the well. Risk control measures related to “requiring dewatering” provide a basis for the pipe jacking project’s construction and a reference for the construction of related projects. Related Articles | Metrics

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Stability Analysis of a Spillway Slope of the Tankou Second Reservoir NIAN Fuxi, FENG Xixia, CHEN Lei, YAO Xiaomin 2024, 38 (2):  186-191.  Abstract ( 94 )   Save Stability analysis of the slope is important for the safety of all construction projects. The stability and the excavation deformation characteristics of a spillway slope of the Tankou Second Reservoir is evaluated by the limit equilibrium method and the FLAC3D numerical method, respectively. The factor of safety of the slope, the displacement patterns, and the stress-stain relationships are studied. The results indicate that the overall stability of the spillway slope is satisfactory, with minor local failures occurred at the upper and middle surface of the excavated area. The reinforcement measures of the ground anchors with shotcrete should be adopted, as commonly used in the area. In this paper, the results of the spillway slope numerical simulations have provided a scientific reference for the excavation design and the reinforcement measure of the slope, which has an useful theoretical and practical significance. Related Articles | Metrics

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A construction Method of New and Old Underground Pipeline Intersection Node WAN Yunhua, GUO Shengjuan, TANG Wei 2024, 38 (2):  192-194.  Abstract ( 100 )   Save In recent years, with the development of the urban renewal as well as the renovation of old residential areas and blocks, many problems that are not occurred in the conventional new constructions have also been encountered during the development. For example, during the pipe network placement in the process of the renewal and reconstruction, the cross-connection construction of the new and existing underground pipelines is often encountered. Due to the existing underground pipeline, the traditional open caisson method is not feasible. Currently, the common treatment method is to directly adopt the method of deep excavation support plus the open cut and cover at the connection position of the new and the existing pipelines. However, sometimes, due to the unclear quantity, buried depth and direction of underground pipelines, the construction of supporting structure for the deep excavation may damage the existing underground pipelines. In addition, in some old residential areas with restricted construction space, the construction equipment cannot enter the site or there is no operating space. To solve similar problems, designers must seek new methods. This paper introduces a treatment method, which is called segmented slurry wall method, in combination with engineering examples. Related Articles | Metrics

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Structural Design of Metro Stations Connecting to the Commercial Surroundings HU Zhengbo 2024, 38 (2):  195-198.  Abstract ( 101 )   Save As the construction of metro station becomes more and more intensive, more and more metro stations are connected to the surrounding commercial facilities, so the evaluation of the structure design of the metro station connected to the surrounding commercial structures becomes more and more important. This paper presents a case history of the surrounding commercial subway station in Nanchang. The PLAXIS finite element software and SAP2000 are used to perform the retaining structure and the main structure analysis under different working conditions. These analyses provide a reference for the similar subway station structure design. The results show that: 1) the horizontal constraints, such as plate support and other horizontal constraints, which connect with the surrounding businesses, can control the horizontal displacement of the internal structure of the subway station and ensure the safety of the deep excavation. 2) the main structure under the eccentric load and the load results under the non-eccentric loading conditions have a large difference. Under the eccentric load condition, the bending moments in main structure of roof and side wall are very large so that the proper reinforcement in these areas should be considered in the structure design. Related Articles | Metrics

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Disturbance Zone Control Method for a Large Diameter Bored Pile Construction Near an Operative Subway HUANG Shunpei, WANG Liangjun, ZHU Shangming, ZHAI Langbao 2024, 38 (2):  199-203.  Abstract ( 93 )   Save The installation of bridge piles near existing subway tunnels is an inevitable result in the utilizing urban underground space. Quantifying the disturbance zone of the surrounding soil layers caused by the bridge pile installation is an important measure to ensure the safety of existing subway tunnels. Providing a safer and cost-effective construction process according to the corresponding soil disturbance has also the technical significance of related research. Therefore, by using the finite element software, the construction of a large-diameter and extra-long bored bridge pile near a subway tunnel in Fuzhou was numerically studied. From the theoretical and numerical analysis results, the three-stage evolution characteristics of the soil stratum disturbance propagation with the excavation depth were investigated and an “upper part” method was proposed. The rapid construction method for this extra-long and large diameter bored piles combined with the micro-disturbance penetration of permanent steel casing and the lower slurry retaining wall. The field measurement results of a large-diameter and extra-long bored bridge pile near the subway tunnel construction in Fuzhou show that the final deformation of the tunnel disturbance guided by this method is within the allowable safe value. The method is demonstrated to be economical and safe. Related Articles | Metrics

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Optimization of Slope / Tunnel Excavation Plan Selections in Silty Clay Mixed with Granite Slope  ZHI You, YANG Xinghong, WANG Hongxing, YU Feng 2024, 38 (2):  204-208.  Abstract ( 88 )   Save In highway engineering construction, natural slopes often face different excavation options. Cutting excavation and tunnel excavation are proposed in the slope design of a project. To select a reasonable excavation option and construct the slope with more stable and safer after the excavation, the stability of the original slope and the slope under two different excavation and support plans are evaluated by using a two-dimensional numerical simulation method. Furthermore, the stress and deformation characteristics of the two excavation options are compared. The analysis and evaluation results show that: for the excavation tunnel option, the factor of safety for the tunnel without support is low and prone to failure. The factor of safety meets the code requirements after the support measures were implemented, but there is still a risk of tensile failure above the tunnel arch. For the cutting excavation option, the overall deformation of the rock mass around the highway is small and the stress and strain are all in the safe range. The factor of safety of this slope meets the code requirements. Therefore, it is more reasonable to determine the engineering slope for cutting excavation. Related Articles | Metrics

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The Down-Hole Dynamic Compaction and the Supporting and Dewatering of Deep Excavation in a Building Site with Thick and Saturated Miscellaneous Fill JIANG Wenfu, HOU Fang, FU Qing, SUN Wenlai, 2024, 38 (2):  209-214.  Abstract ( 117 )   Save This typical building site with saturated and thick miscellaneous fill is in a Yellow River alluvial plain in Jinan City. The site was a borrow pit for a brick kiln, which was abandoned many years ago. The maximum thickness of the miscellaneous fill is 13.2 m. This miscellaneous fill soil layer contains a large number of construction waste, some of which are large blocks and steel reinforced concrete blocks. The project includes five buildings varying 3-7 stories with one underground basement. The maximum depth of the foundation excavation is 6.80 m. This article shows the engineering investigation, the dynamic compaction, the down-hole dynamic compaction, the dewatering-draining methods and the design of the deep excavation supporting structure comprehensively. It is summarized that the impact method is the most feasible for the down-hole dynamic compaction. The full-length casing follow-up rotary excavation is the best construction technology for the installation of the dewatering point well, etc. The range of the dynamic compaction and foundation excavation are discussed in detail. The in-depth discussions also include of how the system of the dewatering point well coordinates with the dynamic compaction, the down-hole dynamic compaction, the dewatering-draining methods as well as the deep excavation supporting structure. All of the above might provide some reference to the constructions with the similar miscellaneous fill sites. Related Articles | Metrics

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Bored Pile Installation Method and Slurry Borehole Protection Mechanism in Karst Terrains GU Haoran, PANG Dongwei 2024, 38 (2):  215-219.  Abstract ( 118 )   Save To resolve the problems of the borehole caving, deflection, and lost drill bit during the drilling process of the rotary excavation of bore piles in well-developed karst terrains, this paper presents a case history of bored pile installation for a high-rise residential building. Based on the analysis of the geological characteristics of the karst terrain at the site, the common installation hazards occurred in the bored pile installation in the karst area, such as, borehole out of plumbness, drill bit jam, borehole caving at the soil-rock interface and in the filling material, could be mitigated throughout double casing method as well as slurry borehole protection. The results show that the main characteristics of the karst terrain at the project site are the presence of vertically developed fractures, irregular filling, semi filled, and fully filled karst rock cavities and pinnacles. In rock cavities in the borehole during the drilling out of plumbness and the advancement reach 50%, and the linear dissolution rate of each borehole ranges from 45% to 78%. For the problem of drilling out of plumbness and drill bit jam, three control parameters, namely, drilling downward pressure, rotational speed, and drilling rate, are proposed for different soil layers and rock formations. For the problem of borehole caving at the soil rock interface, the double steel casing method was proposed, and a large cone angle, wear resistant spiral drill bit was used for advancing near the rock surface. For the problem of caving in the filling material, measures for grouting improvement and slurry borehole protection are proposed. After adding of 0.573kg special polymer slurry into the borehole can effectively improve the borehole wall stability and reduce hazards such as slurry lost, borehole caving, drill bit lost, and borehole necking. Related Articles | Metrics

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Analysis and Mitigation of Landslide at a Factory Area in Dalongli, Zijin Mountain in Fujian MENG Xin, YAO Ke, ZHAO Yukai, CHEN Feng, LI Huan 2024, 38 (2):  220-224.  Abstract ( 130 )   Save A landslide occurred at the slope of a factory area in Dalongli, Zijin Mountain in Fujian Province after experiencing several heavy rains. The original slope stabilizing measures were ineffective, resulting in cracks at the top of the slope, and the slope was in an unstable state. To analyze the instability mechanism of this slope, on-site undisturbed soil samples were collected and the triaxial as well as the direct shear tests were conducted to analyze the impact of rainfall on the mechanical parameters of the slope soil in the factory area. Based on the damage of the landslide, a typical section is selected, and the arbitrary slice method is used to analyze the factor of safety of the sliding surface by using the Geo-slide slope stability analysis software. The comprehensive mitigation measures such as slope cutting, ground anchor, anti-slide caisson, etc. are utilized for reinforcement. The stability check of the mitigation plan is also performed. The results show that the slope stability factor of safety increases from 0.943 to 1.359, which meets the design requirements. The slope is stable, and the expected mitigation goal can be achieved. Related Articles | Metrics

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Groundwater Variation and Stability Analysis of Baibao Landslide Under Rainfall LAI Xuemei, YI Qinglin, AN Zhili, ZENG Huaien, XU Zhihua, 2024, 38 (2):  225-228.  Abstract ( 106 )   Save To reduce the serious damage caused by the landslide hazards to the loss of human life and property, it is necessary to study the landslide phenomenon and the stability analysis to improve our understanding of the potential landslide risk. The Baibao landslide in the Three Gorges Reservoir area was selected as the research object and the field observation data were analyzed. The groundwater variation and stability of four different rainfall types were simulated by using the Geo-Studio software. The results show that the material composition of the slope body is favorable to the rainfall infiltration. The continuous rainfall that occurred in early July 2020 was the direct factor leading to the sliding of the slope body. The internal friction angle and cohesion were obtained from the test results of the field soil samples.  The rainfall in 10 days is the peak rainfall type, and the fastest drop in the factor of safety. These will further increase the probability of the landslide instability. This study can provide a reference for the subsequent theoretical support and prevention of such landslides. Related Articles | Metrics

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Deformation Characteristics of the Muping Landslide and Deformation Mechanism of Rainfall Coupled with Reservoir Pool Water LEI Yu, ZHANG Jiaxu, GAO Chenxi 2024, 38 (2):  229-233.  Abstract ( 98 )   Save Many landslides have occurred in Three Gorges Reservoir area. Since the impoundment of the reservoir, the reservoir pool water level changes periodically and the rainfall is abundant, which has an impact on the stability of slopes in the reservoir area. The Muping landslide in the Three Gorges Reservoir area was presented as a case history in this paper. The deformation mechanism of the landslide under the coupled effect of the rainfall and the reservoir pool water level is analyzed by using the combination of qualitative and quantitative methods throughout the field geological survey, the displacement monitoring and other data. The results show that the “stepped” phenomenon of the Muping landslide presents a small characteristic, and the large “stepped” phenomenon is accompanied by the large fluctuation of the reservoir pool water level and the obvious rainfall; When the reservoir pool water level drops, the landslide deformation response is more sensitive, because the head difference between the groundwater and the reservoir pool water level points out of the landslide. Single day heavy rainfall and the continuous rainfall can cause the landslide deformation, and the lag time of the peak rate in high pool water level operation stage is 9 days. The research results can provide a basis for the prevention and the control of Muping the landslide hazard and the study of similar landslides. Related Articles | Metrics

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Analysis of Rock Mass Strength Parameters of an Open-Pit Mine Slope XU Min, LIU Zhengming, XU Baotian, LIU Kaibin, ZHU Linghao 2024, 38 (2):  234-238.  Abstract ( 93 )   Save The rock mass strength parameters of mining slopes are key indicators for the slope stability analysis and the mining design. The commonly used methods for estimating the rock mass strength indexes include the H-B, Feynko, and Georgi methods. This paper compares and analyzes the estimation results of the rock mass strength parameters obtained by various methods. The back analysis method is used to verify the estimation results from different theories. The rock mass strength parameters for the cohesion and the friction angles, obtained from H-B method, are 460 kPa and 27 °, respectively. The cohesion obtained by the Feynko method is close to that obtained by the H-B method, while the cohesion obtained by the Geggi method is relatively low. The cohesion and friction angle, from the back analysis method, are 450kPa and 27 °, respectively. The results indicate that the H-B method is the most reliable one. The friction angle of the rock mass can be obtained by reducing the friction angle of the rock blocks, by considering the integrity and the softening of the rock mass. Based on the stability estimation results, it is suggested that the slope angle of the studied mine steps should not exceed 60 °. The research results can provide a basis for the stability analysis and the mining design of mining slopes. Related Articles | Metrics

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Analysis of Soft Soil Properties in the Coastal Area of the West Bank of the Pearl River Estuary LUO Yuechun, GAN Zhanzi, ZENG Xinxiong, WANG Ningwei 2024, 38 (2):  239-242.  Abstract ( 115 )   Save Soft soil parameters are significant different at various regions and depths. These soil parameters are the important basis for the soil improvement and the engineering design. Therefore, the statistics and analysis of the soft soil parameters have important significance for the engineering projects. A total of 302 borehole information and 2500 detailed geotechnical test data of the coastal area on the west Bank of the Pearl River were collected. Based on this data, the distributions of soft soil parameters were analyzed. The relation of each parameter with depth is discussed, and the correlation among these parameters is also investigated. The results show that, the average moisture content is 41.5%, the average void ratio is 1.15, and the average plasticity index is 15.9. The above-mentioned parameters decrease with the increase of the depth. The average cohesion is 15.2 kPa and the average internal friction angle is 12.2°. These properties increase with the increase of the depth. The correlation of soft soil properties can be divided into three levels, water content void ratio, water content-liquid index, liquid index void ratio are strongly correlated. Compression modulus-water content, cohesion plasticity index plasticity index, internal friction angle cohesion internal friction angle are weakly correlated, and others are not correlated with each other. Related Articles | Metrics

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Discussion on the Plasticity Coefficients of the Nanshui Double Yield Surface Model SUN Xiangjun 2024, 38 (2):  243-246.  Abstract ( 120 )   Save The Nanshui double yield surface model proposed by Member of Chinese Academy of Science Mr. Shen Zhujiang in the 1990s has been widely used because of its unique and innovative modeling ideas, which consider the convenience of the application and the completeness of the theory. However, in recent years, in several geotechnical academic monographs, dissertations and journal papers, there have been many very different forms of expression of the plasticity coefficient of the Nanshui double yield surface. The reasons for this analysis have found that some formulas are published incorrectly, some formulas have different assumptions, and some are slightly wrong. Copying these formulas will make it very easy for geotechnical practitioners to wrongfully use the Nanshui double yield surface model. It is recommended that when using the Nanshui double yield surface model, the assumptions must first be clarified. Related Articles | Metrics

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Cause Analysis and Suggestions on Defects of Existing Buildings & Structures in Soft Soil Area of Yangtze River Floodplain WU Guanzheng, JIN Xuelian, ZHU Qize, FU Shouyin 2024, 38 (2):  247-252.  Abstract ( 119 )   Save The Yangtze River floodplain soft soil is widely distributed, with poor engineering properties and great potential harm to the buildings and structures above it. The foundation of existing buildings and structures in this area are usually vulnerable, and often cracks or even are destroys due to the excessive total or differential settlement, which has caused certain safety hazards and economic losses to the society. To identify the causes and characteristics of the defects of existing buildings and structures in the soft floodplain area of the Yangtze River, the field investigation and data collection were performed. The results show that geological factors, building and structure factors and inducing factors of the surrounding underground engineering activities are the main influencing factors of these buildings and structures defects. Finally, according to the different types of defects, the corresponding control measures are proposed, and the risk prevention and control suggestions are recommended from the perspective of engineering planning, design, construction and operation, so as to provide reference for the treatment and prevention of building diseases in similar areas. Related Articles | Metrics

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Settlement Analysis of Ground Improved by Micro Grouted Piles LIANG Zhenning, ZHANG Jing, LIU Xueying, 2024, 38 (2):  253-256.  Abstract ( 121 )   Save As a new foundation improvement method, the micro grouted piles can achieve the consolidation, grouting and reinforcement improvement of soft soils. It has been widely applied in soft soil areas such as Shanghai and Changshu. Due to the reinforcement factors interact with each other, and the mechanism of pile-soil interaction is complex, the settlement estimation method has not been reported. Based on a trial project of the Changshu Yaopi project, the deformation estimation method of the composite ground, composite foundation with settlement reduction piles and the pile-net composite foundation are used to analyze the total settlement under the upper structure loads. The unimproved natural foundation loading spreading model is used to estimate the total settlement caused by the dewatering effect. The surcharging settlement of the dewatering is estimated based on the Terzaghi consolidation theory. Then the settlement estimation method of the micro grouted pile composite foundation is proposed. On this basis, combined with the typical soil layer conditions, the influence of factors, such as dewatering depth, duration, service load and ratio of the dewatering depth to the service load, on the settlement are analyzed. Related Articles | Metrics

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Empirical Methods for Estimating the Effective Pile Length under Complex Geological Conditions SHEN Jiepan, LIN Chen 2024, 38 (2):  257-260.  Abstract ( 119 )   Save With the development of modern society, various large-scale engineering projects are increasingly developed, and the engineering cost control has become an intimate part of the project management. In the EPC engineering, the accurate control of the engineering costs is particularly important because it not only involves the financial risks and the ultimate benefits of the project, but also relates to the safety and the sustainable development of the engineering projects. However, in the practical engineering, the complexity of geological conditions often brings challenges to the engineering cost control. Especially in engineering projects with the pile supported foundations, it is often difficult to accurately estimate the effective pile length, which leads to hazards such as exceeding the budget and delaying the project schedule. To solve this problem, this article introduces the software of parametric design, Rhino, and its plugin, Grasshopper, to explore how to use them to estimate and statistically analyze the effective pile length under complex geological conditions. Related Articles | Metrics

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Characteristics of Side Resistance for a Suspended Pile GAO Peng, WANG Hengtao, LIU Zhi, WANG Zuyao, LUO Yuanzhang, LUO Han 2024, 38 (2):  261-264.  Abstract ( 93 )   Save The testing of pile side resistance is an important part of testing the load distribution along piles, but its testing accuracy is often affected by the tip resistance during the test procedure. To obtain the relative accuracy of the side resistance along piles, the tip resistance should be approached to zero. This article presents a case history of the axial load test of a cast-in-place reinforced concrete pile in the loess region of northern Shaanxi Province. A comparative study between the suspended pile and the conventional cast-in-place reinforced concrete pile are performed, and the side resistance of the suspended pile are analyzed. The results show that as a special pile type, the suspended pile can be considered as a typical friction pile, and the tip resistance could be ignored. The load applied to the pile top is completely resisted by the side resistance. The pile resistance shows a monotonic increase with the pile top load increasing. The growth rate (slope) of the pile side resistance is significantly higher than that of in the conventional piles. The testing results could provide a reference for the relevant engineering projects. Related Articles | Metrics

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Influence of Surface Water and Rainfall Infiltration on the Slope Stability of a Highway in Weishan County WU Bangfang, AO Xiaobing, DIAO Hang 2024, 38 (2):  265-270.  Abstract ( 98 )   Save The Midas-GTS/NX software is used to simulate the slope of a highway in Weishan County, Yunnan Province. Through the mirror modeling and the simulation, the stability of the slope is analyzed by strengthening the single and double rows of anti-slide pile, which indicating the failure pattern and the deformation trend of the slope. The results show that the potential sliding surface has occurred in the original working condition of the slope, and the entire slope is in an unstable state. After the rainstorm, the soil underneath the slope is in a saturated state, and the bearing capacity is further reduced, the slope is unstable because of the large displacement of the slope in both the horizontal and the vertical directions. Therefore, it is necessary to reinforce it. The factor of safety for the slope installed by the single/double-row anti-slip pile is 2.43 under the rainfall condition, which indicating that the slope is stable, and the reinforcement effect is obvious. At the same time, it is shown that the Midas-GTS/NX finite element software can fully consider the influence of complex conditions such as surface water and rainfall infiltrations on the stability of the multi-layer soil slope. The SRM analysis results are consistent with the actual engineering estimation results. Related Articles | Metrics

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Analysis of Loess Collapsibility Characteristics by Using PCA & ANN Approach LIU Qiangqiang, WANG Fang, ZHAO Haifei, YANG Jiangfeng 2024, 38 (2):  271-275.  Abstract ( 141 )   Save The collapsibility of the loess is an important engineering characteristic, and the mechanism of collapsibility is very complicated. With the increasing of engineering construction in the Western Inner Mongolia, more and more attention has been paid to the collapsible deformation characteristics of the loess. This paper presents a case history of the loess study in the Baotou area, a typical loess area in Western Mongolia. The statistical analysis on more than 200 loess samples from ten projects are performed and the influencing factors of the loess collapsibility are evaluated by using the mathematical statistics. The natural water content, dry weight, void ratio, saturation, plasticity index and compression modulus are determined as the multiple factors in the loess collapsibility prediction. On this basis, the principal component analysis (PCA) is used to eliminate the overlap among the influencing factors, so that the recombined factors are independent of each other. Then, the artificial neural network (ANN) is used to train the prediction model. Finally, the accuracy of the prediction model is verified by the actual project data. The relative errors of the measured and the predicted collapsibility are -12.5% and -10.4% respectively. The collapsibility grades are therefore consistent. The results show that the method for the loess collapsibility analysis can be used as an important reference in the engineering practice. Related Articles | Metrics

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Rainfall threshold Value Induing the Tianjiawan Landslide in Three Gorges Reservoir Area WANG Yating, HUANG Xiaohu, CHEN Jianwei, LI Bo, 2024, 38 (2):  276-280.  Abstract ( 139 )   Save The Tanjiawan landslide in Zigui County is a typical largescale landslide within colluvial in the Three Gorges Reservoir area. In recent years, it has undergone a significant deformation due to the rainfall, posing a serious threat to people’s lives and property. Based on the geological environment of the landslide area and the cumulative displacement curve, an analysis was conducted on the relationship between the landslide deformation and the rainfall. The study shows that the rainfall is the main triggering factor for the deformation of the Tanjiawan landslide. The cumulative displacement curve exhibits a “stepped” characteristic under the continuous rainfall and heavy rainfall conditions, with a noticeable lag in the occurrence of stepped deformation. The threshold displacement rate for the accelerated “stepped” movement of the Tanjiawan landslide is 17 mm/day. The threshold value for antecedent rainfall and the current rainfall in the antecedent rainfall + the current rainfall model of the Tanjiawan landslide are 10 mm and 13 mm, respectively. After the end of the continuous rainfall, it takes 5 ~ 8 days for the displacement rate of monitoring points to return to normal. The impact of a single rainfall event on the landslide deformation lasts for 8 days. Related Articles | Metrics

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Influence of Shielded Transit Construction on Adjacent Viaduct Foundations in Ningbo Soft Soils JIN Zengxuan, WANG Yehuan, CHEN Shixuan 2024, 38 (2):  281-286.  Abstract ( 110 )   Save The influence of shielded transit tunnel construction on the existing bridge foundations is a very prominent issue. This paper presents a case history of on the shielded section of Ningbo Metro Line 8 under crossing the urban viaduct. The corresponding shielded tunnel construction model is established by using the Midas GTS NX 3D finite element software to analyze the deformation at the top of a viaduct pier. The results indicate that, during the shield construction process, the horizontal displacement (transverse and longitudinal) at the top of the bridge pier first increases, then decreases, and then increases, which exhibiting a bimodal curve. The peak moment of the former is earlier than that of the latter. While the vertical displacement (upheave and settlement) continuously increases, approaching a linear curve. According to the displacement results of the pier top obtained by the numerical analysis, the corresponding displacement control indies are recommended. The feasibility and rationality of the above control indicators are verified by combining with the displacement monitoring data of the viaduct pier during shielded transit tunnel construction, which can provide a reference for the similar shielded tunnel excavation projects in Ningbo areas. Related Articles | Metrics

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Effect of the Ground Subsidence above the Abandoned Mine Gallery on an Adjacent Construction Site by Using GDEM Software WANG Jinxiang, XU Jiancheng, JIANG Wei, ZHANG Haoran, FU Zhaoyu 2024, 38 (2):  287-293.  Abstract ( 93 )   Save The safe utilizing the abandoned mine voids site is an efficient approach to expand the available development space for the city, in which an elementary work is to estimate the effect of the ground subsidence on the adjacent construction site. The classical ways are deficient in the surface movement and deformation analysis above the abandoned mine voids under the complicated geological conditions, such as inclined seams, faults and a relief surface. This paper presents a case history of the abandoned gypsum mine goaf in Jinmen, Hubei. The GDEM software which is used based on the continuum and noncontinuum numerical method is employed in the analysis of the ground subsidence. Then the effect of the goaf on the adjacent construction site is evaluated. Furthermore, numerical models with various inclined angles for seams and different faults are established. Their surface movement and deformation are acquired, and the effects on the construction site are compared. Results show that the seams dipping opposite to the site has less effect than the seams dipping towards the site. And the influence zone becomes small with the inclined angle of seam increasing. The ground subsidence where the fault dips opposite to the site has less effect than where no fault occurs. And the fault dipping towards the site has more effect. Related Articles | Metrics

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Difference Between Measured and Predicted Deformation of a Deep Excavation Supporting Structure CHEN Jianrong 2024, 38 (2):  294-298.  Abstract ( 109 )   Save Based on a case history of a deep excavation supporting structure, the measured deformation data are compared and analyzed with the predicted values. The deformation pattern of the excavation supporting structure, the surrounding soils in the excavated area are obtained and the relationships between the numerical analysis predicted results and measured results are compared. The following conclusions are obtained: (1) The excavation speed and sequence of the excavated area is an important factor affecting the stability of the deep excavation, which must be carefully considered in the design and strictly followed in the construction. (2) For the area of the first excavation, the design and estimation of the large displacement part of the girders should be considered comprehensively. The theoretical prediction of the displacement should be modified, and the force can be estimated by the modified displacement, and then the design of the envelope structure is optimized. (3) There is a large difference between the distribution of the predicted maximum displacement and the measured maximum displacement near the bottom of the exavation. Related Articles | Metrics

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Stability Evaluation and Analysis of Landslide in Long Daylighted Bedding of a Highway in Guizhou Province LEI Qing, LIU Shihong, ZHANG Ya, CHEN Ming, JIANG Bo 2024, 38 (2):  299-303.  Abstract ( 116 )   Save To evaluate the stability of the Ganlong landslide in National Route G326, the engineering geological conditions and factors that triggering the landslide are identified in detail by the comprehensive field investigation, drilling and other methods. The stability of the landslide under the consideration of the heavy rainfall infiltration is evaluated by the geostudio software. The result shows that the landslide topography is relatively steep, the underlying bedrock is tangential, the engineering properties of rock and soil mass are poor, and the long fissure cutting rock mass formed by the longterm rain erosion leads to the cavitation of the slope body, which constitutes the basic conditions for the formation of a large long daylighted bedding landslide. One week before the landslide, the rainfall intensity reached the highest in the entire year, the infiltration line at the rear edge of the slope raised, the pore water pressure of the slope increased sharply, and the infiltration pressure inside the slope, especially in the middle and front of the slope, reached a peak, and the slope stability sharply reduced. The seepage and pore water pressure induced by the heavy rainfall are the main inducing factors of landslide formation. Related Articles | Metrics

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Monitoring and Analysis of A Deep Excavation in a Reclamation Area with Internal Strut Structure GAO Fengzhao, LIU Donglin, 2024, 38 (2):  304-309.  Abstract ( 109 )   Save In the reclamation area, the stratigraphy of the deep excavation area is complicated, and the groundwater is closely connected with the seawater. The surrounding environment of the excavated area has strictive requirements. By using the monitored data in the entire excavation and internal supporting construction process in a nearshore reclaimed area, this paper analyzes the patterns of the horizontal displacement of supporting structure, axial forces in the interior supports, the ground surface subsidence, the upheaving and settlement of the soldier piles. The results show that the maximum lateral displacement of the soldier pile occurs near the bottom of excavation in the vertical direction. The maximum lateral displacement along the edge of the excavation is at the middle of the edge. Improvement in the passive zones at the bottom of excavation can effectively reduce the horizontal displacement of the soldier piles below the excavation. The largest axial force in the horizontal bracing appears in the second vertical struct. In the same plane, the axial force in the middle of the excavation is obviously greater than that of the corner bracing. The ground subsidence around the excavated area increases with the increase of the excavation depth, and the surface subsidence is closely related to the lateral deformation of the soldier piles. Related Articles | Metrics

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Comparative Study of American and Chinese Code Methods for Determining the Moisture Content of Backfill Materials GU Liqiang, MENG Qingfei, LIU Peng, LIU Qingyu, WANG Liang 2024, 38 (2):  310-312.  Abstract ( 119 )   Save The degree of compaction testing is critical for both the roadway subgrade and the factory backfills since the stability of the foundation soils has a significant impact on the superstructure. The compactness is closely related to the maximum dry density, the wet density and the moisture content of backfill materials, among which the wet density and moisture content are obtained based on the on-site sampling. For moisture content determination of backfill materials, oven dry method is commonly used in China, and the rapid moisture content determination method is usually allowed abroad. Both two methods can determine the moisture content of backfill materials, and each has its own advantages and disadvantages. This paper analyzes and compares the test results of both methods. Related Articles | Metrics

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Performance and Microscopic Analysis of the Greater Bay Area Organic Soils Treated with Different Cement Ratios CHEN Zhidong, TAN Xiaodong, WANG Fengmei, WEI Xin 2024, 38 (2):  313-317.  Abstract ( 158 )   Save To gain an in-depth understanding of the improvement effect of different amounts of cement ratios in the organic silty soils in the Guangdong Greater Bay Area, different ratios of P.O 42.5 cement were added to in the soil samples for the quantitative evaluations. The Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) analyses on samples under the standard curing ages of 1, 3, 7, 14 and 28 days were performed. The results show that, curing ages from 1 to 7 days, the content of hydration products in the improved soil samples with cement content of 8% and 10% has little difference. There are obvious needle-like Hydrate Ettringite (Aft) formation. When curing for 28 days, the hydration products calcium-silicate-hydrate (C-S-H) of the improved soil with 10% cement content increased significantly. Combined with the results of coring samples and static load testing at the construction site, the curing effect of 10% cement content after a curing age of 28 days is better. Although the cement content only increases by 2%, the strength and foundation bearing capacity are increased by 32.6% and 54.6%, respectively, which indicating that there is a low threshold for the effect of the cement improved organic soils. The results have some reference values for the practical application of cement improved organic silty soils in the Greater Bay Area. Related Articles | Metrics

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Experimental Study on the Quality of a New Three-Dimensional Cement-Soil Mixed (TCM) Column YAO Da, WENG Jiaxing, QIU Chengchun, WANG Xichen, LIU Zhenjian 2024, 38 (2):  318-321.  Abstract ( 384 )   Save To overcome disadvantages of the conventional cement-soil mixed column installations, which often led to the poor integrity and uneven strength of the cement-mixed columns, a new three-dimensional cement-soil mixed (TCM) column system was developed, and the associated installation procedures were introduced. Combined with the standard penetration test (SPT), low stress integrity testing as well as laboratory unconfined compressive strength tests, the properties of TCM column and conventional cement-soil mixed column were comprehensively and comparatively evaluated. Results indicate that the installation procedures of the TCM column can overcome the slurry overflow phenomenon, which is one of the most important disadvantages in the conventional cement-soil mixed column installation. In addition, the quality of the TCM column is much better with coring sample rates exceed 90% for all the cases studied. Thus, the integrity grade of the TCM columns can be classified as Grade I, where the integrity and strength of the TCM column are much better than that of the conventional cement-soil mixed columns. In addition, the low counts of the standard penetration test and the unconfined compressive strength are increased significantly with the increase of the cement mixing ratio, but irrelevant to the water-cement ratio. Related Articles | Metrics

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Experimental Study on the Effect of Potential Gradient on the Vacuum Preloading Combined with Anode Follow-up Electroosmosis  ZHOU Weidong, ZHANG Zhipeng, FU Hongtao 2024, 38 (2):  322-327.  Abstract ( 118 )   Save To solve the issue of the electrode corrosion and high energy consumption in the vacuum preloading combined with electroosmosis, an improved method, namely, the vacuum preloading combined with the anode follow-up electroosmosis is proposed in this paper. The soil improvement effect of the vacuum preloading combined with the anode follow-up electroosmosis under different potential gradients was evaluated by a series of laboratory model tests. The test results show that the anode follow-up electroosmosis method with the pre-inserted electrode can significantly improve the soil strengthening effect. Compared with the vacuum preloading combined with the electroosmosis, the vacuum preloading combined with the anode follow-up electroosmosis methods can increase the water discharge by 31.3%, the average soil surface settlement increase by 15.9%, the overall water content in the improved soil is also lower. The vacuum preloading with the high potential gradient combined with the anode follow-up electroosmosis method can improve the overall soil strengthening effect, while the soil homogeneity with the low potential gradient is better and the energy consumption per unit water discharge is lower.  Related Articles | Metrics

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Application of Surcharge Method Combined with Self-balanced Method in the Pile Axial Compressive Loading Testing MENG Xinqiu, ZHAO Xuepu 2024, 38 (2):  328-331.  Abstract ( 101 )   Save To meet the requirement of axial pile loading test before the foundation pit excavation, it was decided that the loading test method should be the combination of the surcharging method and the self-balanced method after an estimation of the ultimate axial pile capacity. Meanwhile, the load transducers were placed within the effective range of the pile to monitor the distribution of loads along the pile shaft during the loading process, so that side resistance along the pile can be calculated. The combination of the surcharging method and the self-balanced method can easily solve the problem of completing the pile loading test before foundation pit excavation. All three test piles have no damage under the design maximum loading, and the axial ultimate capacity of the single pile is therefore the design ultimate loading value. The results of pile load distribution test show that the soil layer has not reached the limit state under the maximum test load. The ultimate axial pile resistance is not fully mobilized. Related Articles | Metrics

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Application of Quality Control Factors for Direct Shear Test in Geotechnical Engineering LIU Zhong, ZHANG Ying 2024, 38 (2):  332-335.  Abstract ( 129 )   Save The direct shear test is the most common laboratory test method in the geotechnical engineering to estimate the soil shear strength indices. Currently, it is widely used in the engineering projects. To evaluate the control factors for the direct shear test and improve the quality of testing, this paper establishes a two-dimensional numerical model of the direct shear test by using the discrete element method. The conclusions are as follows: (1) The aspect ratio of the shear box will affect the test value of the shear effect; More accurate shear effect test values can be obtained by using a shear box with a smaller aspect ratio; (2) The vertical and horizontal normal stresses of the shear band are equal, so the direction of the principal stress and strain rate is coaxial. Therefore, the direct shear test cannot carry out non-coaxial correlation analysis. The results of this paper provide reliable data support for improving the quality of the direct shear test. Related Articles | Metrics

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In-Situ Test Study on Mechanical Parameters of Wenzhou Soft Soils HOU Feng 2024, 38 (2):  336-341.  Abstract ( 99 )   Save The soft soil has typical engineering characteristics such as, high moisture content, large void ratio, poor permeability, large compressibility, low shear strength, long consolidation time, high sensitivity, easy to thixotropy, easy to disturb, and the rheology. A better understanding of the engineering characteristics of soft soils is critical and fundamental for analyzing and mitigating the safety issues of the underground engineering construction and operation in thick and soft soils. A series of in-situ tests were carried out in the Wenzhou soft soils, and the mechanical parameters obtained by different test methods were obtained. Based on the laboratory test results, the differences of mechanical parameters obtained by different test methods are evaluated and compared, and the best test method for charactering different mechanical parameters is determined. The cone penetration test should be used for the undrained shear strength and the foundation bearing capacity. The compression modulus can be mainly estimated by the laboratory tests, companied with the cone penetration test. The at-rest lateral earth pressure coefficient should be obtained by a dilatometer. The sensitivity should be obtained by the vane shear test. The vertical permeability coefficient can be obtained by laboratory test and piezocone penetration test. This research can provide the theoretical support for the geotechnical aspects of construction engineering in Wenzhou soft soils. Related Articles | Metrics

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Experimental Study on the Shear Deformation Characteristics of Wetted Loess Samples BI Qingtao, CAO Yanhui, ZHAO Kun, FAN Xiaoxiao 2024, 38 (2):  342-345.  Abstract ( 126 )   Save The stress path and the moisture content are the important aspects that governing the deformation characteristics of the collapsibility of loess samples. A modified stress-controlled direct shear device was used to analyze the shear deformation of the loess caused by the change of moisture content under the condition of the constant stress, and the wetted shear deformation characteristics of loess were discussed. Wetted shear tests under different normal pressures, shear stresses and dry densities were carried out. The results show that the soil sample tends to fail when the combined value of the stress and the amount of water used for the moisture content reaches a certain value. Under the same normal pressure, when the shear stress value is small, the soil sample will not have a wetted shear failure mode. When the shear stress is greater than a certain value, the sample tends to fail when the moisture content inside the soil sample reaches a certain value. Under the same stress conditions, the change of the wetted shear displacement with the wetting moisture content of soil samples with a low dry density was higher than that of soil samples with a higher dry density. Related Articles | Metrics

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Testing Methods for Evaluating the Fluidity of Liquid Soils NIU Jiawei, WU Yuezhou, GU Xinguan 2024, 38 (2):  346-349.  Abstract ( 176 )   Save The fluidity is one of the important indicators of liquid soils. Currently, there is no national or industrial standards for its evaluation method. Firstly, the specifications for materials such as concrete and cement mortar were compared to clarify the similarities and differences between different testing methods. Then, the fluidity of the liquid soil was tested using truncated cone molds and cylindrical containers, and a comparative analysis was conducted. The results show that the principles of the current relevant standards for measuring the material fluidity are the same, but the difference lies in the different experimental devices. When the fluidity of the liquid soil is between 160mm-300mm, the results obtained by using truncated cone molds and cylindrical containers are basically the same, and both can be used as testing instruments for the fluidity of the liquid soil; When the flowrate exceeds 300mm, the flowrate measured using a cylindrical container is significantly higher than that measured using a truncated cone mold. Related Articles | Metrics

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Mechanical Properties and Energy Evolution of Dolomite Under Triaxial Compressions ZHU Weihao, DONG Lu, LI Hongya, MA Linjian, ZHANG Siyi 2024, 38 (2):  350-355.  Abstract ( 136 )   Save Exploring the progressive failure of rock samples and the law governing energy evolution helps clarifying the inherent mechanism of rock damage. Triaxial compression tests were conducted on dolomite rock samples to investigate the influence of various factors, such as, confining pressure characteristics, the stress and strain energy. The correlations among the total absorbed energy, the elastic strain energy and the dissipated energy at distinct stages of rupture are analyzed, and the potential mechanisms governing their variations are evaluated. The major findings are as follows: (1) With an increase in the confining pressure, all characteristic stresses exhibit a linear growth. The peak stress corresponds to the compressive strength of dolomite rock samples, which adhere to the Mohr-Coulomb criterion. (2) As the confining pressure rises, the strain energy increases linearly. The crack initiation stress illustrates the accumulation of the elastic strain energy; while the energy dissipation at the point of crack damage stress initiates accelerated growth and dominates at the peak stress, rendering it susceptible to an unstable damage. (3) rock burst potential indices increase significantly as the confining pressure decreases. Following the excavation and the unloading, it is recommended to install stress-relief holes or concrete supports for the effective control of the rock burst. Related Articles | Metrics

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Numerical Simulation on Damage and Fracture of Calcite Vein-Filled Shale Using CT Scanning LEI Wenli, YANG Yuhan 2024, 38 (2):  356-360.  Abstract ( 127 )   Save To study the rupture evolution of the calcite vein-filled shale in the Niutitang Formation in northern Guizhou, this paper obtains the image of the shale interior by the CT scanning. The shale matrix and calcite veins are identified by using the threshold segmentation technique. The three-dimensional numerical model of the shale by combining with the numerical simulation software of RFPA-3D is established. The numerical simulations of the uniaxial compression tests on the calcite vein-filled shale with four angles are conducted. The test results show that the mechanical properties of the shale show obvious anisotropy with the inclination angle of the calcite veins, in which the compressive strength reaches the maximum of 45.05MPa when the calcite veins are 0°. The tensile strength reaches the minimum of 37.02MPa when the calcite veins are 60°. The calcite-filled shale samples show two damage modes under the uniaxial compression, which are the shear-slip damage along the calcite veins, composite damage and the “composite damage” veins and “V”-shaped tensile-shear composite damage. The research results have an important reference value for the prediction of the fracture initiation and the extension in calcite vein-filled shale reservoirs. Related Articles | Metrics

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Experimental Study on Key Parameters of Standardized Construction of Inflatable Ground Anchor with Hollow Bar Grouting XIE Biting, 2024, 38 (2):  361-364.  Abstract ( 277 )   Save To meet the requirements of the standardized tunnel construction, it is necessary to control and to evaluate the technical parameters and construction quality of the main process measures during the tunnel construction process. Throughout the on-site and laboratory testing, the key parameters in the grouting of the ground anchors with hollow bars, such as, the anchoring loads, pre-stressed torque conversion relationship, and grout stopping are studied. The standardized construction technology and the key technical parameters of the low pre-stressed inflatable ground anchor with hollow bars are proposed. The results show that, there is a significant difference in the anchoring load of the inflatable head of the ground anchors in different soil and rock strata. For layers with poor geotechnical properties, such as the carbonaceous shale section, it is not recommended to use the inflatable ground anchor with hollow bars. The prestressing load applied to the anchor rod should not be less than 60kN, and it is recommended that the torque value should not be less than 600N · m. To ensure the construction quality, special tooling and equipment with good quality control measures must be installed; The ground anchor should be equipped with a grout stop plug with exhaust and pressure stabilization function to achieve the requirement of the grouting pressure not less than 0.5MPa and the pressure stabilization time not less than 30s. Related Articles | Metrics

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Application of Self-Bored Pressuremeter Test in the Geotechnical Investigation of Padma Bridge LENG Shengqiang 2024, 38 (2):  365-368.  Abstract ( 118 )   Save It is the main purpose to obtain accurate mechanical parameters and appraise the mechanical properties of the soil and to provide reliable basis in the engineering investigation planning. The in-situ testing technology can obtain various parameters of the soil without releasing the pressure in the soil and disturbance to the soil structure. It has a high efficiency and precision, so it is increasingly popular and has a wide application in the geotechnical field. The self-boring pressurementer test is one of the most widely tests. Based on the investigation project of the Padma Multipurpose Bridge in Bangladesh, the accurate and reliable soil parameters for the project by the introduction and improvements of the foreign advanced insitu testing instruments are obtained. These efforts made a positive contribution to the promotion and application of the self-boring pressuremeter test. Related Articles | Metrics