降水引起的低承台群桩沉降特性分析

Analysis of the Settlement Behaviors for Pile Group with Low Cap under Precipitation

对沪杭城际高铁某桥墩低承台群桩桩基在承台上部加载及地下水位下降导致的沉降特性进行了研究,并对桩-土摩擦系数和群桩的桩间距对群桩沉降影响进行了分析。地下水位下降对群桩的影响机理分析表明:群桩周围一定范围内的水位下降土体所受浮力消失是导致桩体受到向下附加摩阻力及群桩附加沉降的起因;桩-土摩擦系数增大时,降水导致的桩体最大附加轴力出现位置深度越浅,因此,桩体受到向上附加摩阻力的区段长度越大,桩端的附加荷载与附加沉降越小;桩间距增大时,水位下降导致的桩体附加压缩量越大,同时桩端的附加荷载与附加沉降也越大。

The settlement behaviors of pile group of bridge pier for Shanghai-Hangzhou high speed railway is studied under the condition of loading from the cap and groundwater level falling,and the effects of pile-soil friction coefficient and the distance between piles on pile group settlement are analyzed. The analytical results of the influential mechanism for the pile group of dewatering are as follows：（ 1） The vanish of the buoyancy of the dewatering layer surrounding the pile group is the cause of downward additional friction and additional settlement of piles;（ 2） With the increase of pile-soil friction coefficient,the location of the maximum additional axial force of pile caused by dewatering become more shallow,accordingly,the length of the pile subjected to upward additional friction become longer,and the additional resistance and settlement at the pile tip become smaller;（ 3） With the increase of distance between piles,the amount of additional compression of the pile caused by dewatering become greater,and the additional resistance and settlement at the pile tip become larger,too.