Abstract:To ensure the stability of the construction and operation of subway lines in a soft stratum， the soil strength around the structure can be improved by grouting reinforcement. However， according to different reinforcement degrees， the discontinuity of the soil medium will be gradually changed， and the corresponding dynamic transmission characteristics will be changed， so the dynamic response distribution mode of the reinforced area and the surrounding stratum under the driving condition needs to be further explored. A dynamic coupling model of subway line-stratum with reinforcement area is established based on the analytical theory. The reinforced soil and the natural soil are considered as saturated porous media with different physical and mechanical properties， and the corresponding dynamic equations are derived respectively by Biot theory. The subway structure is regarded as an infinite cylindrical shell with uniform thickness， which is described by the theory of the thin-walled cylindrical shell under the torsion-free condition. According to the displacement and stress continuity conditions between interfaces of the dynamic system， the vibration equations of the above parts are combined into a set of coupled dynamic equations， and the vibration of the subway peripheral stratum containing the reinforced area is calculated， the effects of stiffness and viscous damping of the reinforcement area on the distribution and transmission of the stratum dynamic response are further compared. The results show that under the steady state action， the maximum tangential acceleration of the stratum around the subway shows a cicada-wing distribution at 30° on both sides of the structure diagonally downwards， and the maximum radial acceleration occurs in the soil in the direction of the load. Due to the harmonic characteristics of the input waveform， the acceleration decays fluctuating in the stratum， but an obvious amplification of tangential acceleration occurs in the reinforcement area. After the vibration enters the natural soil， the dynamic response is significantly attenuated by the effect of stratum damping. Increasing the stiffness of the reinforcement area is conducive to reducing the conduction of tangential acceleration， while the radial acceleration changes little， and the transmitted dynamic response increases when the viscous damping decreases.

Abstract:To study the seismic response characteristics of the seamless transfer subway station and improve the understanding of the seismic performances of such station structures, the shaking table test on a scale model of such station structure was carried out for the first time. The design of the shaking table test included the preparation of test models, the arrangement of measuring points, collection of testing data and the design of test working conditions. Then, the processes of the model test were simulated by three-dimensional finite element method. Through comparison between the numerical and measured results, acceleration responses of the model soil, strain and internal force responses of the structure model and soil pressure responses on the sidewall were analyzed. The results showed that the numerical results agreed well with the test data, which validated the rationality of the modeling method in this paper. For the structure model of the seamless exchange subway station, the structural exchange end had an obvious influence on the structural deformation, the structural internal force and its surrounding soils. When the distance between the station exchange ends exceeded 1.5 times station structural width, its effect basically disappeared. These conclusions can provide powerful support to the three-dimensional calculation method for the seismic analysis of complex subway stations and the anti-seismic design of such station structures.

Abstract:The main problems in the detection of shield tunnel lining defects are how to obtain high quality images of different defects and how to quickly and accurately detect the defects. A device for mobile tunnel inspection (MTI-100) was designed and manufactured based on CCD line array cameras. Using MTI-100, Shanghai Metro Lines 1, 2, 4, 7, 8, 10 and 12 were tested and a large number of lining images were obtained. These images were manually labeled to form a high quality database of lining defects samples. Based on the Faster R-CNN (Faster Region-based Convolutional Neural Network), a deep learning framework for automatic disease detection was established. Inspired by the existing model VGG16, the CNN detection model of tunnel lining defects was established. Considering the particularity of cracks and leakage defects, statistical analysis and K-means clustering algorithm were used to analyze the geometric features, so as to optimize the related parameters of anchor box in the VGG-16 network model. The results show that the accuracy of the optimizeation is greatly improved（about 7%），and the training time is reduced. It is verified that the method can also improve the accuracy of the defect detection model of crack or leakage singly.

Abstract:DamageAnalysis on Subway Tunnel Structure under Effect of Reverse Fault DislocationAN Shao1，TAO Lianjin1，BIAN Jin2，HAN Xuechuan1，WU Xiaowa1 (1. Beijing Key Laboratory of Earthquake Engineering and Structural Retrofit，Beijing University of Technology，Beijing 100124，China;2. Guang Dong Ocean University，Zhanjiang 524008，China)Abstract:Taking the subway tunnel in Urumqi crossing Xishan reverse active fault as an example，a three- dimensional elastic-plastic finite element model of soil-tunnel structure was established to simulate and analyze plastic strain development process of secondary lining，transverse and longitudinal distribution of tensile damage factor，compressive damage factor and shear strain，calculate the crack width of concrete under the action of reverse fault dislocation. Then the damage law of the tunnel structure with different dislocation displacements,different vertical distances from tunnel bottom to the interface of surrounding rocks and different widths of fault zone was studied. Finally，the disaster reduction effect of the flexible joint was studied. Results show that the damage of secondary lining first appeared in the vault，then the bottom，and finally accumulated at the waist. The shear，tensile and compressive damage all appear at the tunnel waist of the rupture surface. When the tunnel structure is away from rupture surface，the tensile damage appears at the tunnel vault of hanging wall and invert of fault zone，the compressive damage appears at the tunnel invert of hanging wall and vault of fault zone. The severe and slightly tensile-crack damaged length are 10 m and 30 m respectively based on the crack width of concrete. The larger the fault displacement is，the more serious the structural damage is. The larger the vertical distances from tunnel bottom to the interface of surrounding rocks，the thicker the soil is，resulting in that more energy is dissipated and the structural damage is lighter. The damage to tunnel increases with the increase of width of fault zone，but when the width increases to 26 m，the influence of width of fault zone on tunnel damage becomes stable. Setting flexible joints can significantly reduce structural damage and substantially meet the design requirements for fault displacement.