坑外地下水位波动引起的基坑水土压力响应  

Pore and earth pressure response to groundwater fluctuation out of foundation pit

作　　者：应宏伟[1] 章丽莎[1] 谢康和[1] 黄大中[1] 

机构地区：[1]浙江大学滨海和城市岩土工程研究中心,软弱土与环境土工教育部重点实验室,浙江杭州310058

出　　处：《浙江大学学报（工学版）》2014年第3期492-497,共6页Journal of Zhejiang University：Engineering Science

基　　金：国家自然科学基金资助项目(51278462);国家自然科学基金重点资助项目(51338009)

摘　　要：考虑滨海地区基坑外侧经受的动水作用,建立边界孔压变化的单层饱和土地基一维固结模型,采用杜哈姆积分和傅里叶级数求解,得到边界孔压波动下均质饱和土基坑的超静孔压响应表达式,研究了坑外地下水位简谐波动引起的土体超静孔压响应、分布规律及影响因素.通过算例计算,分析地下水位波动对基坑支护结构水土压力变化的影响.结果表明:当无量纲因子值较小时,土体中超静孔压随着深度的增加迅速衰减,各个深度的孔压波动存在明显的相位差,随着无量纲因子值的增大,超静孔压沿深度方向衰减幅度减缓,相位差减小,其响应幅值和影响深度均增大;坑外地下水位波动对主动侧总孔压、土体竖向有效应力、总侧压力的影响比较明显,对被动侧的影响相对较小;当地下水位上升即超静孔压为正值时,对基坑支护结构受力、基坑稳定性不利.Considering the variation of groundwater table outside offshore foundation pits,a one-dimensional consolidation model for single-layer homogeneous saturated soil was established,assuming groundwater fluctuations as pore water pressure variations at the boundary.Analytical expressions of excess pore water pressure were derived by using Duhamel＇s theorem in conjunction with Fourier series,and the distribution and affecting factors of excess pore pressure under Hamonic groundwater fluctuation were analyzed.The influence of groundwater fluctuation on water and earth pressure on the retaining wall was examined through a case study.The results show that the excess pore pressures attenuate rapidly with depths and the phase lag of pore pressure fluctuation is significant at different depths when the dimensionless parameter is small.The groundwater-variation-associated excess pore pressure propagates into the ground with little damping and phase lag when the dimensionless parameter is comparatively large.The fluctuation of ground water outside the foundation pit has significant impact on the total pore pressure,the vertical effective stress of soil and the total lateral pressure in active zone;however＇its influence on those in passive zone is relatively small.When the ground water level rises,the total lateral pressure on the retaining structure will increase and lead to instability of the excavation.

关 键 词：地下水位波动 超静孔压 基坑 水土压力 解析解 

分 类 号：TU431[建筑科学—岩土工程]