Experimental Study On Shaking Table Test Of Wrap Reinforced Soil Retaining Wall With Assembled Panel

As an important application form of the reinforced soil technology in engineering,the reinforced soil retaining wall has many advantages comparing with the traditional gravity retaining structure.In recent years,the reinforced soil retaining wall has been widely used in traffic engineering of earthquake-prone countries due to its excellent seismic performance,and obtained great helpful effects.However,due to the lack of understanding of the interaction between soil and reinforcement under the earthquake action,the description of seismic design theory is very confusing in the domestic related standards.Therefore,in order to resolve the contradiction that the theory seriously lags behind practice in the process of application,we still need to do study about seismic performance in-depth,seismic isolation technology,seismic design method and other aspects of the light retaining structure with great prospects for the development.In order to provide some references for the seismic design of the domestic same type retaining structures,based on the comprehensive literature review,we carried out a shaking table model test to study the seismic response of the wrap reinforced soil retaining wall with assembled panel,then compared the similarities and differences between the results of the test experimental and theoretical calculation.Through the analysis and research,conclusions as following:(1)There are obvious differences in the imaginary frequency curves of transfer function for different parts of the retaining wall,due to the different types of materials and methods of treatment;With the number of loading applied and the acceleration amplitude increases,the first-order natural frequency and damping ratio of each part respectively decreases and increases,the natural frequency decreases by about 0.5Hz,almost 2.5%of the first-order natural frequency,the increase of damping ratio is in the range of 3.5%-5%.(2)After the 0.25g dynamic load being applied,the PGA amplification coefficient doesn't increase unlimited along with the acceleration,which reflects the excellent seismic performance of the reinforced soil retaining wall;The vertical amplification effect of the acceleration increases significantly with the height of test point increases.In each part of the retaining wall,PGA amplification coefficients along the wall has similar distribution law which shows in broken line,and the current design theory can not perfectly reflect the amplification of seismic effect of the light retaining structures.(3)Under the active limit state,the horizontal earth pressure stress at the back of the panel and the end of the reinforcement show different trends along with the increasing of vibration acceleration amplitude.At the back of the panel,the horizontal earth pressure stress is positive and increases with the increasing of the acceleration.Along the wall height,the distribution act shows as a single peak type which in the lower part of the retaining wall;with the increase of the acceleration,the horizontal earth pressure stress at the end of the reinforcement is mostly negative and continue to increase,the maximum value appears at the top of the wall,which indicates that using the formula recommended in the standard to calculate the active earth pressure stress under earthquake action will lead to a safer external stability.(4)The horizontal displacement of the whole retaining wall has a nonlinear increase as the acceleration amplitude increase.There is an obvious increasing after 0.15g applied which showed the larger acceleration amplitude,the faster growth rate?In the loading process,no obvious settlement observes at the end of the reinforcement,while the vertical cumulative displacement of the position clinging panel increases with the increasing of the acceleration amplitude;After the peak acceleration 0.3 g sinusoidal harmonic applied,the horizontal and vertical cumulative displacement of the position clinging to the top panel increase significantly.This phenomenon is caused by the factors that the filler being dumped during loading,the larger local deformation of the panel and so on.It is suggested that the engineers and technicians should pay more attention to these unfavorable factors in the design and construction of the reinforced soil retaining wall.(5)The maximum dynamic strain of the grid along the wall is distributed as double peak type,the first peak appears at the wall height of 0.4m and the second peak 0.8m;The maximum dynamic stress is 126.8MPa,far less than its tensile strength,which indicates that the intensity of geogrid is not the controlling factor for the failure of the reinforced soil retaining wall.Along the wall height,the measured values of the grid tension and the theoretical results show different contrast rules:In the lower part of the retaining wall,the measured tensile force is less than the theoretical value,while in the upper part of the retaining wall,the measured value is greater than the theoretical results.The rules show that if the formula recommended in the standard is adopted to calculate the internal stability of the reinforced soil retaining wall is unsafe,the upper geogrid has high risk of being pulled out during actual application process.