| With the vigorous development of China’s engineering construction industry,a large number of civil engineering infrastructures are continuously extending and transferring to deep underground,deep sea,and central and western regions.Projects such as subway construction,cross-sea and bay bridges,and railway projects(such as the Sichuan-Tibet Railway)are characterized by long distances and large scales.In China’s special seismic geological structure,they will inevitably encounter the effects of surface or deep underground seismic faults.Blindly "avoiding" them is no longer possible.Therefore,research on the mechanism of seismic fault movement,the destruction mechanism of long linear engineering structures and facilities under fault action,and other key issues has become extremely urgent,both in terms of engineering needs and academic development and technical services.The surface soil layer rupture caused by seismic fault damage often causes huge damage to surface structures.In this paper,a research method combining seismic fault simulation model experiments with numerical simulation of seismic faults is used to simulate three types of fault types with less research:tensile faults,compressional faults,and strike-slip faults.Practical engineering parameters such as surface longitudinal deformation,width of surface uplift zone,height of surface uplift,surface fault slip,and width of surface deformation influence zone are extracted to analyze the surface rupture morphology of the overlying soil layer and explain the surface damage mechanism under different fault types.The main contents are:(1)Fault slip model experimental device and experimental method,and numerical simulation preprocessing.The functional components of the fault slip model simulation device are introduced,and the basic physical and mechanical parameters of the sand configuration are obtained through direct shear tests and gravity calculation methods,and the experimental conditions and measurement system are listed.The numerical simulation software and numerical modeling process are described in detail,and the scheme design of numerical simulation is finally given.(2)Comparison of experimental results and simulation results of tensile faults.The surface rupture diagram obtained from fault experiments and the contour cloud map of surface total displacement obtained from numerical simulation are analyzed to obtain the surface longitudinal deformation change diagram.It is found that the length of surface longitudinal deformation decreases with the increase of soil layer thickness.(3)Comparison of experimental results and simulation results of compressional faults.The concept of compression ratio is introduced,and the surface rupture diagram and displacement cloud map are analyzed to extract three parameters:white line length(surface longitudinal deformation),width of surface uplift zone,and height of surface uplift,which are plotted and analyzed.It is found that the length of surface longitudinal deformation decreases with the increase of soil layer thickness,the width of surface uplift zone increases with the increase of soil layer thickness and the height of surface uplift increases with the increase of soil layer thickness.(4)Comparison of experimental results and simulation results of strike-slip faults.The surface rupture diagram of the strike-slip fault experiment and the contour cloud map of the total surface displacement obtained from numerical simulation are given.The two indicators of surface fault slip and the width of surface deformation influence zone are analyzed to obtain the trend that the surface fault slip along the fault line decreases with the increase of soil layer thickness,and the surface fault slip shows a distribution of large edge and small middle.The width of the surface deformation influence zone increases first and then decreases with the increase of soil layer thickness. |
