边载作用下桩基承载性能数值分析

桩基除了承受自身上部建筑物的荷载外,经常还承受各种形式的边载作用。边荷载会引起桩周土体的沉降,产生额外附加力,即负摩阻力。这些可导致桩基的承载力下降使结构破坏。通过建立桩土共同作用的三维数值模型,分析边载作用下桩基承载性能。主要研究了边载大小和边载距离对桩侧摩阻力的影响规律;桩长和边载距离组合对其的影响规律;得出了2个组合关系的表达式。同时应用最小二乘法得到不同边载组合的桩侧总摩阻力表达式,并依据离散系数的统计分析,验证了该函数表达式具有较高的精确度。得到结论：当边载距离s和边载大小Q的相对关系k值增加至32时,由边载产生的桩侧负摩阻力趋于0;当桩长L和边载距离s的相对关系c值增加至0.5时桩侧负摩阻力趋于0。即在这2个相对关系极限值以外,桩基承载性能将不受边载影响。

Numerical Analysis on Bearing Capacity of Piles Subjected to Side Loads

Besides the loading applied by the upper building,the piles are often subjected to indirect loading such as side loads.These kinds of loads would cause the pile bear additional force（negative skin friction）,which may be large enough to reduce the bearing capacity and cause structural failure of a pile.By establishing the numerical model of pile-soil interaction,the bearing capability of pile under side load was analyzed.The joint effect of different magnitude and the distance of the side load on the skin friction were focused.The joint effect of length of the pile and the distance of side load on the skin friction was discussed.The expression of the two combination relationship was obtained.Meanwhile,by using the least square method,the expression of total skin friction on different side load combination was achieved.And based on the statistical analysis of the dispersion coefficient,the function expression was proved to be of high precision.The results show that when k,which indicates the relative relation of side load distance s and the side load magnitude Q,increases to 32,the value of negative skin friction goes to zero.When c,indicating the relative relation between pile length L and side load distance s,increases to 0.5,the value of negative skin friction goes to zero.Beyond limit value of these two relative relationships,the bearing capability of the pile will not be affected by side loads.