考虑土体强度空间变异性的单桩水平承载力研究

空间变异性是土体的固有天然属性，在确定桩基础承载力时理应考虑土的这一特性。应用已有的土体参数随机模拟方法，考虑不同的变异系数和相关距离，通过数值方法研究了土体强度的空间变异性对单桩水平承载力的影响。研究发现:确定性分析得到的单桩水平承载力明显大于考虑土体强度空间变异性后的单桩水平承载力均值，应用规范方法设计的单桩基础仍有失效的可能；相关距离对单桩水平承载力均值无明显影响，但承载力标准差随相关距离的增大而增大；随着变异系数的增大，单桩水平承载力均值随之减小，但承载力标准差随之增大。因土体强度空间变异性导致单桩承载力的不确定性，其分布规律可以用对数正态分布进行描述，据此规律可获得任一荷载下单桩基础的失效概率。

Study on the horizontal bearing capacity of single pile foundation considering spatial variability of soil strength

Spatial variability is the inherent nature of soil, which needs to be considered when calculating the bearing capacity of piles. Different coefficients of variation and correlation distance will be considered. Based on the numerical method, the existing simulation method of random field will be used to generate soil parameters so as to study the effect of spatial variability of soil strength on the horizontal bearing capacity of a single pile. The results show that after considering the spatial variability of soil strength, the average value of the single pile horizontal bearing capacity is significantly less than that obtained by the deterministic analysis, and the single pile foundation designed by the standard method is still possible to fail; the correlation distance has no significant effect on the average value of the single pile horizontal bearing capacity, but the standard deviation of bearing capacity increases with the increase of the correlation distance; with the increase of the coefficient of variation, the average value of the horizontal bearing capacity of the pile foundation decreases, while the standard deviation of the bearing capacity increases. The distribution law of horizontal bearing capacity of the pile foundation considering the spatial variability can fit log-normal distribution. According to this law, the failure probability of the pile foundation under any load can be obtained.