砂土中边坡附近单桩水平抗力的模型试验研究

针对平地p-y曲线对临近边坡桩基的不适用性,开展了砂土中边坡存在对单桩水平抗力影响的室内物理模型试验。依据边坡坡角及边坡到单桩距离的不同,共进行了11次3组试验。采用分段3次多项式对实测桩身应变分布进行拟合,以推算桩身变形和桩侧抗力,有效克服了数据拟合点的奇异。对比无边坡时的试验p-y曲线、美国API规范曲线和双曲线模型,确认了平地p-y曲线的计算表达式。其次获得了边坡条件下的单桩荷载-位移曲线,揭示了边坡坡角和边坡到桩的距离对水平受荷单桩桩身弯矩分布的影响规律。根据试验结果采用折减系数修正浅层桩侧极限抗力,并引入边坡对桩侧初始刚度的削弱表达式,得到边坡条件下水平受荷单桩浅层区域双曲线p-y曲线表达式。最后通过与离心试验结果对比,验证了给出的p-y曲线考虑边坡影响时的合理性。

Model tests on effect of slopes on lateral resistance of near single piles in sand

In light of the inapplicability of common method to get p-y curves near a slope, a series of model tests on lateral static loading is carried out for single flexible piles near a slope. There are totally 11 series tests of different slope angle and distance between slope and pile. The strain curves of pile are fitted with piecewise cubic polynomial, which avoids singular points effectively. p curves and y curves are gained through derivation and integration of strain curves. The load-displacement curves are drawed, and the influence of slope on the distribution of bending moment is analyzed. Existing expression is introduced and revised according to test results to get the ultimate lateral resistance near a slope. Other reseracher’s expression is employed to get the initial stiffness of p-y curves near a slope. The final expression of p-y curves put forward in this paper is approved reasonable by comparison with a typical centrifuge test results.