高应变法模拟Q-s曲线误差分析

依据某静压桩工程试桩的单桩竖向抗压静载试验和高应变动力试验结果,结合其桩身材料特性、桩侧阻力和桩端阻力发挥性状的分析,对高应变动测模拟Q-s曲线误差进行了分析和研究。高应变动测计算的Q-s曲线和静载试验实测结果相比,在荷载较小时高应变动测计算的沉降较大,在荷载较大时高应变动测的沉降较小。高应变试验模拟计算结果与静载结果的不同,与其测试分析中采用的桩身材料和土阻力的数学模型有关。高应变动测分析时假定桩身是弹性的,但实际桩身混凝土是非线性的,使得高应变动测模拟计算的Q-s曲线产生了一定的误差;而高应变动测分析中土静阻力弹塑性的假定与实际土阻力发挥性状的不同,以及高应变测试时桩产生的位移较小,是高应变动测模拟Q-s曲线误差的主要原因,在采用高应变动测模拟Q-s曲线时应考虑这些因素的影响。

ERRORS STUDY ON Q-s CURVE OF PILE SIMULATED BY HIGH STRAIN DYNAMIC TESTING METHOD

Based on the test results of pressed piles by static load test and high strain dynamic test in an engineering test,as well as the analysis of mechanical behaviors of pile shaft material and developing behaviors of soil resistance and the load transfer behavior,an analysis of errors of Q-s curve simulated by high strain dynamic testing method is made. The settlement of pile calculated by high strain dynamic testing method is higher than that of pile tested by load test when load is smaller;and it is bigger than the result of load test when load is higher. These errors are relative with the mathematical model about pile shaft concrete and soil resistance in high strain testing. Concrete is thought as elastic body in high strain testing,but actually it is nonlinear,this brings about some errors in Q-s curve of pile simulated by high strain dynamic testing method. The model of static soil resistance in high strain testing,which is thought as elasto plastic model,is not the same as the actual developing behaviors of soil resistance;and the settlement of pile in high strain testing is smaller than that in static loading test;these are major factors which bring about errors in Q-s curve of pile simulated by high strain dynamic testing method. These factors should be considered when the Q-s curve is simulated by high strain dynamic testing method.