按土强度参数确定弱化砂土层水平极限抗力的探讨

利用施加反压的方法模拟具有残余孔压的弱化饱和砂土层，针对相对密度为30％和40％的弱化饱和砂土层，进行了单桩水平承载力模型试验，研究了不同弱化状态饱和砂土层的水平极限抗力．结果表明，随饱和砂土层中残余孔压的增加，其水平极限抗力逐渐降低；土层液化后，其水平极限抗力降低约90％，这与已有的振动台及动力离心模型试验结果基本一致．按Reese建议的破坏模式，针对土层表面作用上覆压力的备件，推导了依据土强度参数确定土层水平极限抗力的理论关系式；据此确定了弱化饱和砂土层的水平极限抗力，并与模型试验结果进行了比较．结果表明：饱和砂土层液化前，其理论水平极限抗力与模型试验结果基本吻合；饱和砂土层液化后，其理论水平极限抗力小于模型试验结果．这说明饱和砂土液化前土层的破坏遵循Reese建议的破坏模式．

Ultimate Lateral Resistances of Degradation Stratum Determined Based on Soil Strength Parameter

Saturated degradation sand strata with the residual pore pressures were simulated by applying backpressures to saturated strata. Model tests were conducted to research the ultimate lateral capacity of a single pile in saturated degradation sand strata with relative densities of 30% and 40%. Test results show that ultimate lateral resistances of saturated sand strata gradually decrease with the residual pore pressures increasing. The ultimate lateral resistances of strata degrade by 90% after saturated sands liquefaction, which is consistent with shaking table and dynamic centrifugal model test results,The theoretic relationship to determine ultimate lateral resistances of strata using soil strength parameters was further derived based on the failure mode suggested by Reese, with consideration of the effect of the overburden pressure on the ultimate lateral resistance. Ultimate lateral resistances of saturated degradation sand strata being determined using the relationship compared with model test results. The comparison results show that theoretic ultimate lateral resistances are basically consistent with model test results before saturated sand strata liquefaction, while the theoretic ultimate lateral resistances are less than the model test result after saturated sand strata liquefaction, which indicateds that the failure of saturated degradation sand strata follows as the failure mode suggested by Reese.