| With the implementation of one strategy,one belt,one road and the other,we have built a lot of linear projects in the western region of China,such as the Han and Wei River projects and the west east gas transmission project.The terrain and landform of the area are complex,geological structure is developed,and the seismic fortification intensity is high.Linear engineering is inevitable to cross the active structural zone.The cross fault zone project is not only affected by the creep and stick slip of the fault,but also because of the existence of the structural plane and weak fracture zone,the seismic response of the cross fault project is very complex,which seriously affects the seismic fortification of the project.This paper takes the loess site of the fracture zone as the research object,and uses the large shaking table test and numerical simulation method to study the dynamic response characteristics of the site and the cross fault water transmission pipeline,analyzes the pore pressure development rules of saturated loess site under the action of earthquake load,and reveals the mechanism of seismic dynamic disaster of the water transmission pipeline,It provides reference for seismic fortification of the project.The main research contents and innovative achievements are as follows:(1)Through remote sensing interpretation,field investigation and data analysis,the geological environment conditions of the project are determined.Combined with the specific structural characteristics of the project,the large-scale shaking table test scheme of the project is determined by using the similarity theory principle.(2)The distribution characteristics of site acceleration and amplification law of dynamic response are determined.① at the same height,the acceleration response near the fault is larger than that on both sides,and gradually decreases to both sides.The acceleration response of hanging wall is larger than that of footwall,and the fault has a certain amplification effect on the acceleration.At 0.4g,the peak acceleration of A7 in the fault is 6.316 m/s2,which is 6.3%higher than that of hanging wall A6 and 6.7%higher than that of footwall A8;② the acceleration response increases with the increase of height.At 0.6g,the peak acceleration of A1 point is 12.741 m/s2,which increases by 16%and 24%respectively compared with A5 and A10.The acceleration amplification factor increases first and then decreases with the increase of loading acceleration.(3)The response characteristics and distribution of dynamic earth pressure and pore water pressure are determined.① along the excitation direction,the dynamic earth pressure is the largest near the fault and decreases to both sides,and the earth pressure increases with the increase of the peak acceleration,and the vertical earth pressure increases with the increase of the depth,and the acceleration has a great influence on the vertical earth pressure at the surface.When the acceleration is 0.4g,the earth pressure of p14 in the fault is 13.15kpa,and that of p12 and p16 in the loess layer is 8.73kpa and 8.95kpa respectively;②under the action of seismic load,the pore water pressure ratio increases with the increase of height,and the pore water pressure ratio at O12,O11 and O10 is 0.5,0.9 and 1.0 at 0.6g,and the pore water pressure at the fault is the largest,which gradually decreases to both sides.(4)The dynamic response characteristics and deformation law of pipeline structure under earthquake load are determined.① the strain of the pipeline near the axial fracture is the largest,and the strain on both sides is smaller,and increases with the increase of acceleration;②the strain of cross section is larger at the top and bottom of arch before 0.4g,and larger at the left and right arches after 0.4g;③Before 0.4g,there is no obvious settlement and cracks on the surface of loess site.After 0.5g,the settlement increases gradually,and the cracks continue to expand.When the load reaches 0.9g,the loess site is completely destroyed into scattered blocks,and the maximum settlement displacement is 18cm.(5)The response characteristics of acceleration,pore pressure and pipeline structure are verified by numerical simulation,which provides the basis for the seismic fortification of the project. |
