软土弯剪作用下大直径刚性桩水平承载性能试验

Experiment on Lateral Load Capacities of LargeDiameter Rigid Pile Against Toppling Moment and Shear Forces Under Soft Soil Site Conditions

摘要:

对软土中2根直径为0.90~1.09 m、埋深6.47 m的钢管单桩进行弯剪作用下的单向单循环快速维持荷载试验，获得桩身弯矩和桩顶位移随荷载的变化情况，探讨了桩周土地基加固对桩的水平承载能力的影响及刚性短柱法的适用性.试验结果表明：桩身弯矩沿埋深呈现先增大后减小的趋势，弯矩最大值出现在0.06~0.15倍埋深处；荷载水平小于0.23时，桩顶水平位移较未加固前减少20%~30%，地基加固提高了桩的水平承载性能，而荷载水平大于0.6以后，地基加固的影响消失；采用刚性短柱法的设计用钢量较实际需求多37%，存在较大安全余量.

Abstract:

Two steel piles with an embedded depth of 6.47 m and diameters ranging from 0.9 m to 1.09 m were constructed under soft soil site conditions against toppling moment and shear forces by using the oneway singlecycle quickmaintain load method. The pile bending moments and the horizontal displacements of pile top were recorded for different load levels. The lateral bearing capacities with and without the soil stabilization were then compared and the accuracy of the rigidshortcolumn (RSC) method was evaluated. The test results show that the recorded bending moment quickly increases to the maximum at 0.06 to 0.15 times of the embedded depth, and then decreases along the pile depth. When the load is less than 0.23, the displacements decrease by 20% to 30%, which are lower than those before soil stabilization, indicating that the soil stabilization improves the lateral loadbearing capacities of the piles. However, the positive influence of soil stabilization is not present when the load level is larger than 0.6. The steel consumption of piles designed by using the RSC method is 37% more than what is practically needed, indicating that this design method could be improved.