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Environmental effects induced by excavation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第1期9卷 50-57页

作者： Yu-qi LI Jian ZHOU Kang-he XIE Department of Civil Engineering Shanghai University Shanghai 200072 China Department of Geotechnical Engineering Tongji University Shanghai 200092 China Institute of Geotechnical Engineering Zhejiang University Hangzhou 310027 China

Based on 3D Biot’s consolidation theory and nonlinear Duncan-Chang’s model, a 3D FEM (finite element method) program is developed considering the coupling of groundwater seepage and soil skeleton deformation during excavation. The comparison between the analysis result considering the variation of water head difference and that without considering it shows that the porewater pressure distribution of the former is distinctly different from that of the latter and that the foundation pit de- formations of the former are larger than those of the latter, so that the result without considering the variation of water head dif- ference is unreliable. The distribution rules of soil horizontal and vertical displacements around the pit and excess porewater pressure are analyzed in detail in time and space, which is very significant for guiding underground engineering construction and ensuring environment safety around the pit.

关键词： Environmental effect excavation Deformation Excess porewater pressure

Improved prediction of pile bending moment and deflection due to adjacent braced excavation

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Frontiers of Structural and Civil Engineering 2023年第11期17卷 1739-1759页

作者： Chana PHUTTHANANON Pornkasem JONGPRADIST Duangkamol SIRIRAK Prateep LUEPRASERT Pitthaya JAMSAWANG Construction Innovations and Future Infrastructures Research Center Department of Civil EngineeringFaculty of EngineeringKing Mongkut's University of Technology ThonburiBangkok 10140Thailand Department of Civil Engineering School of EngineeringKing Mongkut's Institute of Technology LadkrabangBangkok 10520Thailand Soil Engineering Research Center Department of Civil EngineeringKing Mongkut's University of Technology North BangkokBangkok10800Thailand

Deep excavations in dense urban areas have caused damage to nearby existing structures in numerous past construction *** assessment is crucial in the initial design *** study develops equations to predict the existing pile bending moment and deflection produced by adjacent braced *** parameters(i.e.,the excavation geometry,diaphragm wall thickness,pile geometry,strength and small-strain stiffness of the soil,and soft clay thickness)were considered and employed in the developed *** is practically unfeasible to obtain measurement data;hence,artificial data for the bending moment and deflection of existing piles were produced from well-calibrated numerical analyses of hypothetical cases,using the three-dimensional finite element *** developed equations were established through a multiple linear regression analysis of the artificial data,using the transformation *** addition,the three-dimensional nature of the excavation work was characterized by considering the excavation corner effect,using the plane strain ratio *** estimation results of the developed equations can provide satisfactory pile bending moment and deflection data and are more accurate than those found in previous studies.

关键词： pile responses excavation prediction deflection bending moments

Probability-based method using RFEM for predicting wall deflection caused by excavation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第10期12卷 737-746页

作者： Yu-geng TANG Department of Architecture Hwa-Hsia Institute of Technology Taiwan 23568 Taipei

This study employs the random finite element method (RFEM) to analyze the wall deflection caused by excavation. The RFEM combined random fields of material properties with the FEM through the Monte Carlo simulation. A well-documented excavation case history is employed to evaluate the influence of uncertainty of analysis parameters. This study shows that RFEM can provide reasonable estimations of the exceedance probability of wall deflection caused by excavation, and has the potential to be a useful tool to account for the uncertainties of material and model parameters in the numerical analysis.

关键词： excavation Random finite element method (RFEM) Uncertainty Wall deflection

Evaluation of human response to blasting vibration from excavation of a large scale rock slope:A case study

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Earthquake Engineering and Engineering Vibration 2017年第2期16卷 435-446页

作者： Yan Peng Lu Wenbo Zhang Jing Zou Yujun Chen Ming State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Wuhan 430072 China Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering Ministry of Education Wuhan University Wuhan 430072 China

Ground vibration, as the most critical public hazard of blasting, has received much attention from the community. Many countries established national standards to suppress vibration impact on structures, but a world-accepted blasting vibration criterion on human safety is still missing. In order to evaluate human response to the vibration from blasting excavation of a large-scale rock slope in China, this study aims to suggest a revised criterion. The vibration frequency was introduced to improve the existing single-factor （peak particle velocity） standard recommended by the United States Bureau of Mines （USBM）. The feasibility of the new criterion was checked based on field vibration monitoring and investigation of human reactions. Moreover, the air overpressure or blast effects on human beings have also been discussed. The result indicates that the entire zone of influence can be divided into three subzones： severe-annoyance, light-annoyance and perception zone according to the revised safety standard. Both the construction company and local residents have provided positive comments on this influence degree assessment, which indicates that the presented criterion is suitable for evaluating human response to nearby blasts. Nevertheless, this specific criterion needs more field tests and verifications before it can be

关键词： Construction industry excavation Velocity control

Intelligent feedback analysis on a deep excavation for the gravity anchorage foundation of a super suspension bridge

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岩石力学与工程学报 2019年第A01期38卷 2898-2912页

作者： RAN Tao LIU Daan MEI Songhua WANG Weiwei TAN Lihua Institute of Geology and Geophysics Chinese Academy of Sciences University of Chinese Academy of Sciences Zhongnan Engineering Co. Ltd. CCCC First Highway Engineering Co. Ltd.

In order to ensure the construction safety of the 38.5 m deep excavation for the gravity anchorage foundation of Fuma Yangtze River Bridge, an intelligent feedback analysis was applied to this excavation project. First, a three-dimensional numerical model that simulating the construction process of the excavation was built,and the deformations of the supporting structures were calculated by the finite difference program FLAC3 D. Then,the non-linear mapping relationship between the geomechanical parameters and the excavation-induced displacements was established by the back-propagation neural network(BPNN). Last,the geomechanical parameters were optimized intelligently by the genetic algorithm(GA) based on the developed BPNN model and the measured displacements,and the deformations during the subsequent excavation stages were predicted based on the back-calculated parameters. The research results showed that:the back-calculated values of E1,μ1,c1,and φ1 of the completely weathered stratum,and E2 of the heavily weathered stratum were greater than the initial values,while the inversion value of E3 of the moderately weathered stratum was smaller than the initial value. The magnitudes and the variation tendencies of the predicted displacements were in good accordance with the measured displacements. At the end of the excavation,the retaining piles and the top beams had a maximum displacement of 15–20 mm,exhibiting a quite small magnitude as comparing with other case histories. Local concentration of shear stress mainly occurred at the soil-pile interface and at the toe of the excavation slope,and the plastic zones mainly appeared in the completely weathered stratum. After the completion of the excavation,there were no yielding elements in the model,and the convergence of the numerical computation was achieved,indicating the excavation was in a stable state. This study lays the basis for the subsequent construction and operation of the bridge,and offers a significant refe

关键词： foundations suspension bridge anchorage deep excavation parameter inversion deformation prediction intelligent feedback analysis

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Journal of Mountain Science 2018年第5期15卷 1115-1128页

作者： DONG Chun-liang ZHAO Guang-ming LU Xiao-yu MENG Xiang-rui LI Ying-ming CHENG Xiang Key Laboratory of Safety and High-efficiency Coal Mining Ministry of Education Anhui University of Science and Technology School of Mechanics and Photoelectric Physics Anhui University of science and Technology School of Mining and Safety Anhui University of Science and Technology

The unloading effect of the excavation of deep roadways has been considerably studied, but most research methods have been limited to numerical simulations and field measurements. Only a few have adopted experimental methods for similar simulations. On the basis of the theory of mechanics,the testing system is designed considering initial geostress and dynamic unloading. The system includes an impact unloading gear and in-situ stress loading equipment, and a designed three-link structure and the impact hammer can effectively realize the dynamic excavation of ***, a cyclic excavation similar simulation experiment on a deep roadway is conducted in a laboratory. The testing system and the relevant monitoring facilities are utilized, and the unloading effect inside the surrounding rock under the cyclic dynamic excavation is studied. Results show that the cyclic dynamic excavation causes significant unloading only in the nearby rock mass, and the unloading indicators show nonlinear ***, when the lateral pressure coefficient is 1.2,the damage is concentrated on both roadsides due to the excavation unloading. Meanwhile, the damage gradually decays as the span increases.

关键词： excavation unloading in deep roadways Unloading effect Damage of surrounding rock Circular excavation Unloading index

Numerical analyses of influence of overlying pit excavation on existing tunnels

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Journal of Central South University 2008年第S2期15卷 69-75页

作者：郑刚魏少伟 Department of Civil Engineering Tianjin University

The response of existing tunnel due to overlying excavation was studied using 2D FEM (Finite element method). Three typical locations of tunnel with respect to excavation, namely at the central line under the excavation bottom, directly under the base of diaphragm wall and outside of diaphragm, were considered. The variation of tunnel response with the change of location of tunnel was analyzed. The stress path of soil surrounding tunnel during the process of excavation was compared. Numerical analysis results indicate that the underlying tunnels at different locations under the excavation will experience convergence and divergence due to overlying excavation. Moreover, the tunnel located below base of diaphragm wall will experience distortion. The deformation is mainly due to the uneven changes of ground contact pressure on tunnel linings. Both the vertical and horizontal displacement of the tunnel decrease with the increase of the tunnel embedded depth beneath the formation of excavation.

关键词： pit excavation tunnel response FEM

Deformation characteristics and safety assessment of a high-speed railway induced by undercutting metro tunnel excavation

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第1期11卷 88-98页

作者： Wangping Qian Taiyue Qi Yunjian Zhao Yizhou Le Haiyang Yi Key Laboratory of Transportation Tunnel Engineering Ministry of Education Southwest Jiaotong University School of Civil Engineering Southwest Jiao tong University China Railway Design Corporation China Changjiang Construction Investment Corp.Ltd. North China Institute of Science and Technology

Stratum deformation(settlement) is a challenging issue in tunnel engineering, especially when construction of metro tunnels has to undercut high-speed railway. For this purpose, we used the FLAC30 software to analyze the stratum settlement characteristics of high-speed railway at different crossing angles intersected by metro tunnel, in terms of ground settlement trough, stratum slip line and irregularity of ballastless tracks. According to the evolution of the stratum settlement at different angle regions, an optimized angle is proposed for the actual project design. In order to reduce the influence of stratum settlement on the safety of high-speed railway, an approach of safety assessment is proposed for the shield engineering undercutting high-speed railway, as per Chinese specifications using numerical results and on-site conditions. A case study is conducted for the shield tunnel section crossing the Wuhan-Guangzhou High-speed Railway between the Guangzhou North Railway Station and the Huacheng Road Station, which represents the first metro tunnel project passing below a high-speed railway in China. A series of measures is taken to ensure the safe excavation of the shield tunnel and the operation of the high-speed railway. The results can provide a technical support for performing a safety evaluation between high-speed railways and metro tunnels.

关键词： Metro tunnel excavation High-speed railway Settlement characteristics Safety assessment Numerical simulation Case application

Observed deformation characteristics of a deep excavation for the spring area in Jinan,China

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Journal of Mountain Science 2017年第3期14卷 581-594页

作者： ZHANG Ding-wen SHU Ji-cheng SUN Jian-ping Institute of Geotechnical Engineering School of TransportutionSoutheast UniversityNanjing 210096China School ofCivilEngineering ShangdongJianzhu UniversityJinan 250014China

The observed deflections and internal forces of pile-anchor retaining excavation were studied in spring area in Jinan city of China. Based on field measured data, the ground surface settlement, deflection of retaining piles and wall, internal force analysis of concrete piles, axial anchoring forces, groundwater table, and the deformation of surround building and pipelines were investigated. The results indicates that the combining application of concrete piles, jet grouting columns and anchors support system can effectively control excavation-induced surface ground settlements. The field maximum lateral wall deflections are between 0.o2% and o.19% of the excavation depth due to the competitive site conditions. The bending moment-depth relationship curve is S-type. Groundwater leakage results in the sharp drop in groundwater level, which is part of the reasons for the adjacent building settlement. The axial anchoring forces of the upper layer of anchors increase gradually during the excavation, but those of the lower layer of anchors slightly reduced firstly and then tend to be stable during the excavation procedure. In comparison with the histories of excavation cases, the small lateral wall deflection in this study results from the favorable site condition and the relative rigidity of the retaining structure system.

关键词： Spring area excavation Pile anchor system Ground settlement Horizontal displacement