Comparative Study On Shaking Table Test Of Single Pile Negative Friction Caused By Seismic Settlement Of Remolded Soft Soil

Seismic damage investigations have shown that the negative dynamic resistance of pile foundations caused by soft soil seismic trapping has led to serious seismic damage,resulting in substantial economic losses,and is a problem that cannot be ignored in engineering design,but at this stage the mechanism and development pattern of the negative dynamic resistance of pile foundations caused by soft soil seismic trapping is not clear enough,and relevant research needs to be further strengthened.In this paper,the negative dynamic resistance of pile foundations is investigated by means of direct shear,dynamic triaxial and shaking table tests.Based on the similar theory,the dynamic triaxial test and the direct shear test results are used to obtain two types of reshaped soft soil ratios that meet the dynamic properties and shear strength of soft soil.The results of the study provide theoretical support for the design of pile foundation projects in soft soil sites,and its specific results are as follows:（1）The test results show that the model soft soil with 1:1 kaolin to quartz sand ratio and 33% water content can meet the requirements of similar soft soil dynamic characteristics;the model soft soil with 2:1 kaolin to quartz sand ratio and 30% water content can meet the requirements of similar soft soil shear strength;and the model soft soil with 2:1 kaolin to quartz sand ratio and 30% water content can meet the requirements of similar soft soil shear strength.（2）The soft soil sites of both sets of shaking table tests produced U-shaped seismic traps parallel to the direction of vibration under high-frequency sinusoidal wave loading,and the difference in the amount of seismic traps between them was0.5cm.The choice of different similarity indexes had certain influence on the test results,therefore,future shaking table test studies on soft soil seismic traps should select suitable similarity indexes according to the research purpose.（3）The amplification coefficients of soft soil sites to ground shaking in the two sets of shaking table tests are basically the same,increasing with the increase of loading sine wave frequency and peak acceleration,and the difference between the values of the amplification coefficients of the two is small,so the shaking table test research on the amplification law of soft soil sites can ignore the influence of similar indicators.（4）The pile negative dynamic resistance distribution of the two sets of shaking table tests is more or less the same,but the value of the model single pile negative dynamic resistance with the soft soil dynamic properties as the similar index is greater than the model single pile negative dynamic resistance with the soft soil shear strength as the similar index,so the shaking table test study on the distribution of the pile negative dynamic resistance caused by soft soil seismic subsidence can ignore the influence of the similar index,for its numerical quantitative study should be based on the research purpose Further research is required to select suitable similar indicators.This paper presents a preliminary study on the shaking table test of the negative dynamic resistance of pile foundations due to soft soil subsidence.