Study On Sesimic Mechanism Of Anti-Sliding Sheet Pile Retaining Wall Based On Large Shaking Table Test

Due to the advantages of stablizing ability, safe, fast and simple construction, etc., the anti-sliding sheet pile retaining wall has widely applied to prevent landslide of slopes with overlaps and layers. From the investigation of retaining structure damage in the "5.12" Wenchuan earthquake, it was found that the anti-sliding sheet pile retaining wall has excellent seismic performance. However, domestic and foreign research mainly focus on static design, lack understanding of seismic mechanism, and there are few researches on seismic performance of the anti-sliding sheet pile retaining wall, therefore seismic design calculation method is not well developed. The situation restricts the application and development of the economic and reasonable structure in the field of seismic engineering. In view of this, based on the investigation of damaged retaining structures from highway and railways in the Wenchuan earthquake, large scale shaking table tests were performed, in which two structure models of anti-sliding sheet pile retaining wall for stabilizing slope were designed and completed with similitude ratio1:10, scaled acceleration time history of the Wolong station is used as an input motion. In addition, numerical simulation and theoretical analysis were used to expand the achievements. To further reveal seismic mechanism, complement structure work function and improve seismic design of anti-sliding sheet pile retaining wall, the research results propose powerful theory basis and reference. The main achievements and conclusions are summarized as follows:(1) Similitude ratio design of large scale shaking table testsBased on the situation of investigation, two typical worksites were chosen to perform large scale shaking table test. According to the model test (with similitude requirements), basic principles of similitude relationships were determined, similitude model design was completed with the method of dimension analysis, similitude constants involved in the tests were deduced, model materials and physico-mechanical parameters were confirmed, and loading program of shaking table was determined. In addition, the processes of making the modeled retaining structures and slopes were introduced in details, which will provide valuable references for the similar test.(2) Seismic response characteristics of stabilized slopes with anti-sliding sheet pile retaining wallAccording to the measured time histories of seismic earth pressure, displacement, acceleration and anchor axial force from above two structural model tests, detailed and system analysis were performed. Through the analysis, the dynamic response characteristics of internal force of the pile, deformation of the structure, and axial force and shear stress of the cable under the action of different ground motions were obtained, and acceleration response characteristics and seismic wave propagation laws in stabilized slope were known.(3) Numerical analysis of anti-sliding sheet pile retaing wallAccording to the finite difference method, the software FLAC3D was chosen, a three dimensional model with considering structure-soil-anchor interaction was established. Through normalization, acceleration time histories of the Wolong, Kobe and El Centro records were used to excite the shaking table, and the dynamic time history response calculation of multiple modes were completed. According to the main influence of seismic response to structure, the ground motion parameters of input wave, geotechnical material parameters and structure design parameters were focused on studying influence analysis of parameters respectively, seismic response characteristics with different parameters were obtained. In addition, numerical analysis is through other chapters of seismic mechanism research in stabilized slope with anti-sliding sheet pile retaining wall and validation of seismic design method.(4) Seismic mechanism of stabilized slope with anti-sliding sheet pileThrough research of model tests, numerical and theoretical analysis, with the methods of mathematics and mechanics, the deformation law of stabilized slope with sheet pile retaining wall under seismic effect was studied, the zoning characteristics with different displacements were obtained, and the structure-soil dynamic coupling mechanism was revealed focusing on the inconsistent movement of structure and soil around pile, In addition, the change characteristics of cohesive force of anchorage system in different stages of interface failure process and the influence of loading period to ultimate bearing capacity were studied through the MTS test analysis. The displacement control principle of anchorage system was put forward.(5) Seismic design method of anti-sliding sheet pile retaining wallFor sheet pile retaining wall, revised suggestions on pseudo static design was put forward through shaking table tests and numerical analysis. For prestressed anchor sheet pile retaining wall, considering the soil stress redistribution behind pile from anchor installation, a seismic design method was derived. In view of the influence of the ground motion and structural characteristics to seismic performance, the seismic design method with spectrum for sheet pile retaining wall and the R factor reduction estimation model considering near fault pulse effect were put forward, by using Pushover capacity spectrum method. Based on this, combined with performance design thought, the "three level fortification" standard for anti-sliding sheet pile retaining wall was established, which considered the differences of seismic performance from rigid pile and soft pile. The above revised suggestions and new seismic design methods were all verified through the shaking table tests and numerical analysis.