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学者姓名:李鹏飞
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Abstract :
This paper investigates the load-bearing properties and failure mechanisms of shield segments with a circular mid-span opening in shield subway tunnels. Two full-scale specimens with opening diameters of 100 and 200 mm were manufactured and tested, revealing that with an increasing opening diameter, the failure mode transferred from uniform tensile fracture of inner arc concrete to the peeling and crushing of the outer arc concrete. Moreover, the loading process can be divided into four stages, i.e. elastic, plastic expansion, failure, and ultimate stages, and each stage shares a critical load. Subsequently, numerical models were established using the elastoplastic damage constitutive of concrete, and its reliability is verified by the experimental results. Afterward, parametric analysis was performed considering the plain concrete loss and reinforced concrete loss. The analysis results show that the plain concrete loss significantly weakens the cracking load of the segment, while reinforced concrete loss has the greatest impact on the failure load. Finally, a comparative analysis is conducted between the bearing characteristics of the local failure segment, standard shield segment, and the segment joint. Overall, the research results can provide a theoretical basis for the field reinforcement and the safety assessment of local failed shield tunnels.
Keyword :
local failure local failure subway tunnels subway tunnels shield segment shield segment full scale test full scale test parametric analysis parametric analysis Bearing capacity Bearing capacity failure mechanism failure mechanism
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GB/T 7714 | Gao, Xiaojing , Li, Pengfei , Zhang, Mingju et al. Bearing capacity and failure behavior of segments with a mid-span opening of a shield subway tunnel [J]. | STRUCTURE AND INFRASTRUCTURE ENGINEERING , 2024 . |
MLA | Gao, Xiaojing et al. "Bearing capacity and failure behavior of segments with a mid-span opening of a shield subway tunnel" . | STRUCTURE AND INFRASTRUCTURE ENGINEERING (2024) . |
APA | Gao, Xiaojing , Li, Pengfei , Zhang, Mingju , Wang, Haifeng , Jia, Ziqi , Feng, Wu . Bearing capacity and failure behavior of segments with a mid-span opening of a shield subway tunnel . | STRUCTURE AND INFRASTRUCTURE ENGINEERING , 2024 . |
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Abstract :
When a tunnel crosses a landslide orthogonally, this interaction can easily lead to instability in both the landslide and tunnel structures. Based on the relative positional relationship between a landslide and a tunnel, we studied the stress mode and deformation characteristics of the tunnel in three positional relationships: within the landslide mass, the sliding surface, and the sliding bed. The tunnel is a typical type located on a sliding surface at an engineering site, so we established a numerical model showing the intersection of the tunnel and the sliding surface. The plastic zone distribution, stress characteristics, and displacement distribution characteristics of the surrounding rock before and after tunnel excavation were studied. Based on the simulation results, we analyzed the control effect of anti-slide piles in controlling the tunnel's deformation in the surrounding rock from four perspectives: the arrangement of anti-slide piles, the spacing between piles and tunnels, the diameter of anti-slide piles, and the depth of piles embedded in the bedrock. By analyzing the deformation law of the landslide mass and the force characteristics of the tunnel structure under the orthogonal conditions of a tunnel landslide, we provide theoretical guidance for the adoption of anti-slide piles to control instability in tunnel structures.
Keyword :
deformation mechanism deformation mechanism control technology control technology anti-slide pile anti-slide pile tunnel-landslide interaction tunnel-landslide interaction
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GB/T 7714 | Chen, Yang , Li, Pengfei , Lu, Shuai et al. Landslide-Tunnel Interactions and Control Countermeasures under an Orthogonal System [J]. | APPLIED SCIENCES-BASEL , 2024 , 14 (13) . |
MLA | Chen, Yang et al. "Landslide-Tunnel Interactions and Control Countermeasures under an Orthogonal System" . | APPLIED SCIENCES-BASEL 14 . 13 (2024) . |
APA | Chen, Yang , Li, Pengfei , Lu, Shuai , Sun, Zhijie , Zhu, Shizhao . Landslide-Tunnel Interactions and Control Countermeasures under an Orthogonal System . | APPLIED SCIENCES-BASEL , 2024 , 14 (13) . |
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Abstract :
In natural rock mass, the existence of joints or fissures makes the strength of surrounding rock significantly reduced. In this paper, the influence of deformation and failure law of jointed rock mass on the stability of surrounding rock is studied by prefabricating five kinds of single fracture rock samples with different angles. Firstly, the failure and deformation of the unanchored and anchored specimens under different loading conditions (uniaxial compression and cyclic loading) were studied in laboratory tests, respectively. Secondly, the microscopic fracture characteristics and deformation damage modes of the specimens were simulated by using PFC numerical simulation software. The results show that the peak strength and elastic modulus of the sample increase with the increase in the inclination angle. After the sample is anchored, the peak strength of the sample is effectively improved, and the number of cracks is significantly reduced. In practical engineering applications, bolts can change the crack propagation mode and limit the initiation of cracks in the surrounding rock. By studying the crack propagation law and failure characteristics of fractured anchored rock samples, we can deepen the understanding of rock fracture behavior and better reveal the failure and deformation mechanism of surrounding rock instability in tunnel construction.
Keyword :
Disturbance load Disturbance load Anchor support Anchor support Jointed rock mass Jointed rock mass Fracture evolution law Fracture evolution law
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GB/T 7714 | Chen, Yang , Li, Pengfei , Chen, Miao et al. Failure Behaviors of Anchored Rock Mass with Various Fracture Inclinations in Tunnels [J]. | ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING , 2024 . |
MLA | Chen, Yang et al. "Failure Behaviors of Anchored Rock Mass with Various Fracture Inclinations in Tunnels" . | ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING (2024) . |
APA | Chen, Yang , Li, Pengfei , Chen, Miao , Yang, Liu , Cui, Xiaopu , Wang, Shuo . Failure Behaviors of Anchored Rock Mass with Various Fracture Inclinations in Tunnels . | ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING , 2024 . |
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To investigate the pipeline deformation pattern caused by the excavation of deep foundation pits in composite soil-rock strata, a comprehensive study integrating on-site monitoring and numerical simulation was conducted. This study centered on a deep foundation excavation project in the soft soil in Nanjing's floodplain region. The analyses of pipeline settlement and deformation were performed based on field-measured data. This study investigated the impact of excavation on the mechanical properties of the surrounding soil that resulted in the progressive deformation of adjacent pipelines. Furthermore, numerical simulations were conducted using Plaxis 3D CONNECT Edition v22 finite element analysis software. This study elucidated the influence of factors such as pipeline-pit distance and burial depth on pipeline deformation, conducting a quantitative analysis of their effects. The results indicated that deformation primarily occurs unevenly near pit corners and is less pronounced in soil-rock strata than in single-type soil layers. This study established correlations between pipeline displacements and various factors, offering valuable insights for future excavation projects conducted under similar conditions.
Keyword :
composite soil-rock strata composite soil-rock strata sensitivity analysis sensitivity analysis pipeline deformation pipeline deformation numerical simulation numerical simulation
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GB/T 7714 | Wu, Bin , Ge, Chenhe , Li, Pengfei et al. Influence of Deep Foundation Pit Excavation on Adjacent Pipelines: A Case Study in Nanjing, China [J]. | APPLIED SCIENCES-BASEL , 2024 , 14 (2) . |
MLA | Wu, Bin et al. "Influence of Deep Foundation Pit Excavation on Adjacent Pipelines: A Case Study in Nanjing, China" . | APPLIED SCIENCES-BASEL 14 . 2 (2024) . |
APA | Wu, Bin , Ge, Chenhe , Li, Pengfei , Yang, Meng , Li, Liulian . Influence of Deep Foundation Pit Excavation on Adjacent Pipelines: A Case Study in Nanjing, China . | APPLIED SCIENCES-BASEL , 2024 , 14 (2) . |
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Abstract :
The utilization of spatial curve shield tunnelling has now emerged as the prevailing approach in shield engineering, giving rise to a more intricate ground influence. This paper establishes a three-dimensional computational model based on the elastic pass solution and integrates existing research to derive a comprehensive analytical solution for the additional stresses induced in the ground during shield tunnel construction under complex spatial curve conditions formed by connecting two simple line segments. The theoretical approach proposed in this study is subsequently validated through the utilization of a sophisticated numerical model and the approximate solution derived from previous research. Based on the yaw tunneling phenomenon of a shield in spatial curves, this paper independently analyzes the additional stress field of the soil by incorporating relevant yaw parameters and ultimately derives a series of fundamental principles for shield tunneling in space curves. The findings presented in this paper have significant implications for a wide range of shield tunneling projects.
Keyword :
Yaw boring Yaw boring Space line Space line Additional stress Additional stress Shield tunnel Shield tunnel Ground loss Ground loss Construction load Construction load
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GB/T 7714 | Xie, Jiannan , Li, Pengfei , Jia, Fei et al. Analytical investigation of additional stresses induced by yaw tunneling of shield in spatial curves [J]. | TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY , 2024 , 153 . |
MLA | Xie, Jiannan et al. "Analytical investigation of additional stresses induced by yaw tunneling of shield in spatial curves" . | TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY 153 (2024) . |
APA | Xie, Jiannan , Li, Pengfei , Jia, Fei , Ge, Zhaoguo , Li, Shaohua . Analytical investigation of additional stresses induced by yaw tunneling of shield in spatial curves . | TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY , 2024 , 153 . |
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Abstract :
This paper focuses on the performance of a braced deep excavation in soft soil based on field monitoring and numerical modeling. Laboratory tests were conducted to determine the soil parameters used in the modified Cam-Clay (MCC) model. Intelligent field monitoring means were adopted and a three-dimensional model was established. Spatial and temporal effects induced by the excavation are investigated for the deep -large foundation pit in soft soil. Deformation characteristics of the enclosure structure and the surrounding environment throughout the excavation process are presented. The behaviors of diaphragm walls, columns, the maximum wall deflection rate, ground surface settlement, and utility pipelines were focused on and investigated during the whole excavation process. Besides, the axial forces of the internal supports are analyzed. Based on the measured and simulated data, the following main conclusions were obtained: the numerical simulation results are in good agreement with the measured values, which proves the accuracy of the model parameters; the wall and the ground surface showed the maximum displacement increment at stage 9, which was a coupled product of the "creep effect " of the soft soil in Nanjing, China and the "depth effect " of the excavation; as the excavation progressed, the ground settlement changed from a "rising " to a "spoon -shaped " trend, 6 vm was measured between 6 vm = 0.0686% H and 6 vm = 0.1488% H ; the rebound deformation curve of the pit bottom was corrugated, and the depth of disturbance of the pit bottom after the completion of soil unloading was 2-3 times the excavation depth; the closer the pipeline is to the corner of the pit, the less the excavation process will affect the settlement of the pipeline and the less the obvious pit corner effect will occur; the support strength of the buttress and the longest corner brace should be strengthened during the actual construction process to ensure the stability of the foundation deformation.
Keyword :
Deformation characteristics Deformation characteristics Creep effect Creep effect Deep excavation Deep excavation Modified Cam-Clay Modified Cam-Clay Corner effect Corner effect
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GB/T 7714 | Ge, Chenhe , Yang, Meng , Li, Pengfei et al. Performance and environmental impacts of deep foundation excavation in soft soils: A field and modeling-based case study in Nanjing, China [J]. | UNDERGROUND SPACE , 2024 , 18 : 218-238 . |
MLA | Ge, Chenhe et al. "Performance and environmental impacts of deep foundation excavation in soft soils: A field and modeling-based case study in Nanjing, China" . | UNDERGROUND SPACE 18 (2024) : 218-238 . |
APA | Ge, Chenhe , Yang, Meng , Li, Pengfei , Zhang, Mingju , Zhang, Zhonghao . Performance and environmental impacts of deep foundation excavation in soft soils: A field and modeling-based case study in Nanjing, China . | UNDERGROUND SPACE , 2024 , 18 , 218-238 . |
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Considering the shortcomings of traditional tunnel support methods like shotcrete, including large rebound, poor water retention, and dust pollution, this paper proposes an innovative method to use mold-bag concrete (MBC) for initial tunnel support. Through macroscopic mechanical tests and microscopic structural characterization, a high-fluidity mix ratio of MBC suitable for actual construction conditions has been developed. To clarify the mechanical properties of MBC, compressive tests were conducted, leading to important conclusions: 1) Moldbags can significantly enhance the compressive strength and ductility of MBC. The specimens of mold-bag concrete of PP (MBC-PP) fail first but have good ductility, while specimens of mold-bag concrete of SNG-PET (MBC-SPET) have the best compressive performance but poor ductility; 2) Without pressurized drainage, mold-bags can increase the compressive strength of MBC due to the water permeability characteristics, with MBC-SPET having the largest increase in compressive strength, 69.1 %; 3) MBC-SPET tests show that increasing pressure has a better effect than increasing drainage time, with 90 s and 20 kg pressurized drainage being the best increase effect. These findings highlight the potential of MBC in addressing the limitations of traditional methods, providing strength enhancement, environmental benefits, and practical feasibility for tunnel support.
Keyword :
Curing age Curing age Pressurised drainage Pressurised drainage Mold-bag Mold-bag Compressive strength Compressive strength Damage pattern Damage pattern Mold-bag concrete (MBC) Mold-bag concrete (MBC)
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GB/T 7714 | Huang, Zhengdong , Li, Pengfei , Zhang, Mingju et al. Experimental investigation of the mechanical properties of mold-bag concrete (MBC) for primary support in tunnels [J]. | CONSTRUCTION AND BUILDING MATERIALS , 2024 , 445 . |
MLA | Huang, Zhengdong et al. "Experimental investigation of the mechanical properties of mold-bag concrete (MBC) for primary support in tunnels" . | CONSTRUCTION AND BUILDING MATERIALS 445 (2024) . |
APA | Huang, Zhengdong , Li, Pengfei , Zhang, Mingju , Zheng, Hong , Teng, Zhuo , Wang, Shuo . Experimental investigation of the mechanical properties of mold-bag concrete (MBC) for primary support in tunnels . | CONSTRUCTION AND BUILDING MATERIALS , 2024 , 445 . |
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Abstract :
The terminal joints of the steel support system play a critical role in controlling the deformation and stability of the foundation pit. However, accidents caused by issues with these terminal joints have been frequently observed. This paper introduces the Mold-bag Concrete Clamped Joint (MCCJ) as an innovative joint for enhancing the performance of terminal joints in the steel support system of subway station foundation pit projects. Design principles of MCCJ in the steel support system of the subway station foundation pit project are presented. It provides a detailed explanation of its structural characteristics and working principle, as well as elucidates its stress situation and force transmission mechanism. Three MCCJ specimens were designed and processed for indoor compression load tests, further their load-displacement curves, load-strain curves, and failure modes were obtained and analyzed to explore the load-bearing performance and mechanical characteristics in a more professional and academic manner. The test results demonstrate a designed bearing capacity of over 4000kN, exceeding the axial design bearing capacity of Phi 609/630 steel support and meeting strong joint design requirements. Meanwhile, a refined numerical model of MCCJ was established using Abaqus, validated by comparing numerical and experimental results. Parameter analysis reveals the significant influence of steel tube wall thickness and connecting flange thickness on load-bearing performance, while the mold-bag concrete strength grade enhances MCCJ load-bearing capacity within a certain range. Furthermore, to fulfill the compatibility between MCCJ and existing steel supports, and achieve joint strength and high performance, the parameter optimization directions for MCCJ were proposed.
Keyword :
Bearing capacity Bearing capacity MCCJ for steel support MCCJ for steel support Mold -bag concrete Mold -bag concrete Pit construction Pit construction Steel support Steel support
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GB/T 7714 | Zhang, Mingju , Shan, Yuhan , Li, Pengfei et al. Experimental and numerical investigation on behaviors of Mold-bag Concrete Clamped Joints (MCCJ) [J]. | JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH , 2024 , 220 . |
MLA | Zhang, Mingju et al. "Experimental and numerical investigation on behaviors of Mold-bag Concrete Clamped Joints (MCCJ)" . | JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 220 (2024) . |
APA | Zhang, Mingju , Shan, Yuhan , Li, Pengfei , Liu, Wenjie , Huang, Zhengdong . Experimental and numerical investigation on behaviors of Mold-bag Concrete Clamped Joints (MCCJ) . | JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH , 2024 , 220 . |
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Investigating the mechanical properties of sandy cobble strata is essential for optimizing the design and construction of urban tunnels, thereby controlling ground deformation and ensuring tunnel stability. This paper aims to comprehensively investigate the mechanical properties and energy characteristics of heterogeneous sandy cobble strata. Numerical simulations are employed to examine the stress-strain behavior and energy evolution mechanism in scenarios with and without interfaces between the soil matrix and blocks. Subsequent analysis focuses on elucidating the effects of the internal stochastic structures, which characterize heterogeneity, on the overall strength and energy characteristics. The results indicate that the presence of interfaces significantly compromises the overall strength, while exacerbating the occurrence of a tortuous plastic zone around blocks. The volumetric block proportion (VBP), which represents the volumetric content of cobbles, has a significant impact on the overall mechanical behaviour. In the context of high VBP, block sizes, counts and orientations play substantial roles. Finally, the discussion reveals that when blocks are modelled using the elastic model, the overall strength is significantly overestimated compared to the strain-softening and Mohr-Counlomb models, especially in scenarios with high VBP and in-situ stress. It provides an unsafe evaluation (i.e., overestimation) of tunnel stability.
Keyword :
Numerical investigation Numerical investigation Mechanical property Mechanical property Energy characteristic Energy characteristic Sandy cobble strata Sandy cobble strata Volumetric block proportion Volumetric block proportion
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GB/T 7714 | Wang, Fan , Li, Pengfei , Du, Xiuli et al. Numerical investigations of the mechanical properties and energy characteristics of sandy cobble strata considering its internal stochastic structures [J]. | COMPUTERS AND GEOTECHNICS , 2024 , 177 . |
MLA | Wang, Fan et al. "Numerical investigations of the mechanical properties and energy characteristics of sandy cobble strata considering its internal stochastic structures" . | COMPUTERS AND GEOTECHNICS 177 (2024) . |
APA | Wang, Fan , Li, Pengfei , Du, Xiuli , Ma, Jianjun , Wang, Lin . Numerical investigations of the mechanical properties and energy characteristics of sandy cobble strata considering its internal stochastic structures . | COMPUTERS AND GEOTECHNICS , 2024 , 177 . |
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Abstract :
In tunnel engineering, the rock mass contains a significant number of irregularly distributed joints, and typically exhibits high energy accumulation, thereby posing a risk of rockburst occurrence. Therefore, it is of paramount importance to investigate the fracture propagation behavior in jointed rock masses and assess the impact of borehole pressure relief on mitigating rockburst occurrences for effective prevention and control measures. This paper focuses on failure characteristics and pressure relief effectiveness of non-persistent jointed rock mass with holes through laboratory testing and numerical simulation. In laboratory experiments, rock samples are prepared to include a range of crack dip angles and circular holes. Then, the crack propagation law of crack inclination and circular hole is studied by AE and DIC technology. The experimental results show that with the increase of fracture dip angle, the peak strength and energy change of the sample decrease first and then increase. Due to the existence of holes, the crack propagation direction of the original crack is changed. After drilling, the strain energy of the sample is obviously reduced, which shows that the drilling pressure relief effect is obvious, which can effectively reduce the energy accumulated inside the rock mass and reduce the risk of rockburst. Finally, the PFC numerical simulation software is used to analyze the micro-failure process and energy change law of the sample from three aspects: the relative position of cracks and holes, the diameter of boreholes and the spacing of boreholes. Further understanding of the energy dissipation law and mechanical behavior characteristics of jointed rock mass provides a reference for exploring the pressure relief effect of rock mass and preventing rockburst.
Keyword :
PFC simulation PFC simulation Energy accumulates Energy accumulates Borehole pressure relief Borehole pressure relief Crack evolution Crack evolution
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GB/T 7714 | Chen, Yang , Li, Pengfei , Xu, Chongbang et al. Failure characteristics and pressure relief effectiveness of non-persistent jointed rock mass with holes [J]. | THEORETICAL AND APPLIED FRACTURE MECHANICS , 2024 , 134 . |
MLA | Chen, Yang et al. "Failure characteristics and pressure relief effectiveness of non-persistent jointed rock mass with holes" . | THEORETICAL AND APPLIED FRACTURE MECHANICS 134 (2024) . |
APA | Chen, Yang , Li, Pengfei , Xu, Chongbang , Chen, Miao , Yang, Jiayun . Failure characteristics and pressure relief effectiveness of non-persistent jointed rock mass with holes . | THEORETICAL AND APPLIED FRACTURE MECHANICS , 2024 , 134 . |
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