| China is a country with a wide distribution of seismic zones and active faults,so the operating structures and buildings located in the area of active fault zones are bound to be affected to some extents.At the same time,under the background of the formation of national three-dimensional traffic network pattern and the demands of national politics,economy and people’s livelihood,there is no exception for the construction of transportation infrastructure projects in the fault zone active areas.In particular,the Sichuan-Tibet Railway under construction,as the second lifeline of the railway into Tibet in China,is located in an area where active faults are widely distributed and will inevitably cross the active fault area.Among them,there are 5 active fracture roadbeds in the form of roadbed crossing or near parallel,and the near field effect is obvious.According to the seismic safety evaluation data,the peak ground motion acceleration is as high as 0.6g.At present,it is the first time to build160 km/h～200 km/h railway in such a high seismic intensity area,and there are few studies on the corresponding anti-fault measures of construction in the near fault active zone.As one of the main types of faults,dip-slip faults inevitably lead to many roadbed crossing or parallel fault areas in the design and construction.Therefore,it is necessary for engineering construction to carry out research on this aspect,which also plays an important role in safe operation of the line,quick rescue after earthquake and quick repair of the line.The purpose of this paper is to solve the problem of static field fault rupture on the failure mechanism,by using scale model tests and nonlinear finite element numerical simulation method of combining the simulated dip-slip fault activities on the roadbed failure process,numerical simulation process,fault location,fault dip Angle dislocation quantity as key parameters,key slope on the right foot right from the fault distance under 0 times,45 °,60 ° Angle thrust faulting and 0 8 times location are under 60 ° obliquity fault rupture fault-foundation-numerical simulation analysis of roadbed model.In the aspect of model test,the model test of reverse fault displacement roadbed was carried out with the right slope foot 0times the top width of the fault at a 60° inclination Angle to provide useful theoretical basis for roadbed location and collision avoidance.The main research contents and conclusions are summarized as follows:(1)Based on the discussion of fault dislocation construction and structures,the influence of fault dislocation on engineering entities is analyzed,and the types and characteristics of fault dislocation construction and structures are described in detail,which can be roughly divided into compression failure,shear failure and combined failure.(2)The finite element software ABAQUS was used to analyze the displacement,stress,plastic zone and other laws of the prototype subgrade structure under the action of fault dislocation.The results show that the increase of stress and displacement of the subgrade on the 60° reverse fault is stronger than that on the 45° reverse fault at the same position.60 °thrust faulting,embankment destruction for extrusion,and subgrade top performance for bulge on the right,the left down slightly,and in the form of asymmetric distribution by changing the fault(60 ° normal fault)rupture location is located in the bottom width 0 times,simulation found that 60 ° is fault rupture,the subgrade damage to shear failure,and subgrade top performance for the bulge on the left,the right side of the fall,and is asymmetrical distribution,fracture position compared with Angle thrust faulting and moves to the right;When the roadbed is parallel to a 60° dip-slip fault,the horizontal distance of avoidance should be kept as far as possible at one time of the roadbed roof width as the safety red line.(3)According to the similarity theory,this paper discusses the fault rupture roadbed design process model test,and ratio of material through the laboratory test to determine the corresponding model and basic physical parameters of independent research and development of a set of fault rupture roadbed need model device,design the test way of sensors and dislocation loading plan,and the rupture test successfully.The influence of dislocation on subgrade is further discussed.Combined with the results of displacement processing data and video data analysis,the subgrade damage is more serious without reinforcement measures,and the subgrade damage becomes smaller when the cushion layer and pile structure is adopted,and the reinforcement measures play a good role in strengthening the subgrade. |
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