The Model Pseudo-dynamic Testing Study On Rigid Pile Composite Foundation

In recent years, with cities across the country, the development of the western, central China,and so on implementation of the strategy, more and more high-rise buildings, highways and railinfrastructure, the foundation works also will be increased, because my area is relatively large, in differentregions, the basic engineering of the underground environmental conditions is a complex, under normalcircumstances, the natural foundation can not meet the engineering requirements, composite foundation isdeveloped with this situation, rigid pile composite foundation is a more rapid development of compositefoundation, because the rigid pile composite foundation has the advantages of carrying capacity, low cost,etc. Rigid pile composite foundation for the actual project is not very good, especially the very limitedresearch on earthquake-resistance, in recent years, because the increase in the number of China’searthquake, the masses of the people on the seismic performance of buildings increased, and because of thecomplexity of the foundation, with some difficulty to study the seismic performance, in this regard, fewscholars to study it, we urgently need to study the seismic performance of rigid pile composite foundation.Based on the similarity theory, we establish a geometric similarity model than1:10rigid pilecomposite foundation, then we use the pseudo-dynamic test method,and research and design a test system,and study the response of rigid pile composite foundation under seismic action. In the trial, we paste in pileresistance strain gauge, laying the earth pressure sensor, strain gauge buried in the cushion, the outer wallin the sand box to connect the displacement sensor, we measured the pile strain, the value of earthpressure, cushion deformation, displacement value of the sand box. Analysis of the experimentalphenomena, we can get some conclusions, the peak ground acceleration of seismic waves increases,increased the destruction of the rigid pile composite foundation, however, when the upper part of the loadincreases, the peak acceleration is constant, although it increased the intensity of the destruction of therigid pile composite foundation, but its impact than the acceleration. By displacement of the sand boxanalysis, we can get some conclusions, constant load imposed by the upper structure and the peak of thelocal shock wave acceleration increases, the maximum displacement of the sand box also increases;unchanged when the peak of the acceleration of the seismic waves and the upper part of the load increases,the smaller the maximum displacement of the sand box, but decreases slightly; local shock wave peak acceleration increases and the upper load also increases when the maximum displacement of the sand boxis also increased. Through the comprehensive study of the Force Envelope Figure, we can get someconclusions, the maximum shear value of each pile at the top of the pile;corner pile shear values are greaterthan the edge of the pile and the center pile; the moment of each point in the angle of the pile to maintainmaximum, medial side of the pile located in the second, the value of the center pile is the smallest; theupper load remains constant and the acceleration increases, the shear force and bending moment valueincreases, the curve of the internal force envelope diagram change. Acceleration remain unchanged and theupper load increases, the shear and bending moment value increases, but increases the magnitude ofchange than the acceleration time increased substantially larger, while the internal force packet networkdiagram curve change; maximum acceleration and top load increases, the maximum shear and bendingmoment increases, and increased substantially larger.Comprehensive study on the pressure-time curveanalysis, we can draw some conclusions, under horizontal loads, the pile bear most of the load; when thepeak acceleration and top load increase at the same time, the pressure value in the sand box size change,level of lateral pressure of the sand box in central value increases and increased substantially faster, peakacceleration and top load increase at the same time, the pressure of the soil by the level of increasesrapidly; peak acceleration does not change the situation and the upper load increased, the maximumpressure increases; in the upper load does not change the situation and when the peak accelerationincreases, the maximum pressure increases, increase the rate lower than the upper load magnitude of thechanges is small, and the rest of the measuring point pressure value also increased, but increases of varyingmagnitudes; the study found that the internal pressure of the sand box does not change significantly,indicating that within the sand box has been in the elastic state.Through comprehensive research andanalysis on the cushion-time curve, we can draw some conclusions, in the elastic range, the upper part ofthe load constant and seismic wave acceleration increases, the deformation of the cushion also increases;seismic wave acceleration constant and the upper part of the load increases, the deformation of the cushiondecreases; the upper part of the load increases and the acceleration of the seismic waves increases, thedeformation of the cushion increases, but increases the amplitude is small. Finally, a summary of the abovecan be drawn, rigid pile composite foundation has a good seismic performance.