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针对砂土地基中不同L/d的抗拔桩进行了模型试验,模型桩采用了3种不同界面,结合界面剪切试验探讨了桩-土界面特性对抗拔桩荷载-位移曲线、极限承载力及残余承载力的影响,得到了以下几点结论:模型桩长径比L/d不同时,每种界面抗拔桩荷载-位移曲线是类似的,光滑钢桩上拔力达极限承载力后保持不变,粗糙界面模型桩上拔力达极限承载力后降低,直至达残余承载力;抗拔桩达极限承载力时的静止土压力系数K受桩-土界面粗糙程度的影响,界面越粗糙,K值越大;界面越粗糙,抗拔桩残余承载力与极限承载力的比值越小,该比值随L/d的变化较小;对于粗糙界面抗拔桩,残余承载力与极限承载力的差别一部分是由于桩-土界面摩擦角的降低引起的,另一部分是抗拔桩达到极限承载力后作用在桩表面上的水平土压力降低引起的。
Aiming at the different L / d uplift piles in sandy soil foundation, model tests were conducted. Three different interfaces were used in the model piles. Combining with the interfacial shear tests, the effects of pile-soil interface characteristics on load-displacement curves, ultimate bearing capacity And the influence of residual bearing capacity, the following conclusions are obtained: When the L / D of model pile is different, the load-displacement curves of each interface are similar, and the pulling force of smooth steel piles reaches the ultimate bearing capacity Remain unchanged, the rough interface model pile pull up to the ultimate bearing capacity reduced until the residual bearing capacity; anti-pile ultimate bearing capacity of the static earth pressure coefficient K by the pile-soil interface roughness, the interface Roughness and higher K value. The rougher the interface is, the smaller the ratio of residual bearing capacity and ultimate bearing capacity is, the smaller the ratio changes with L / d. For the unreinforced pile with rough interface, the residual bearing capacity and ultimate bearing capacity The difference of force is partly caused by the decrease of the friction angle of pile-soil interface. The other part is caused by the decrease of the horizontal earth pressure acting on the surface of the pile after the pile reaches the ultimate bearing capacity.