坑外地下水位波动引起的基坑水土压力响应

发布时间：2018-11-03 08:41

【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.
[Abstract]:Considering the hydrodynamic action on the outside of the foundation pit in the coastal area, a one-dimensional consolidation model of single-layer saturated soil with the change of the boundary pore pressure is established, which is solved by Duham integral and Fourier series. The response expression of excess static pore pressure in homogeneous saturated soil foundation pit under boundary pore pressure fluctuation is obtained. The response, distribution law and influencing factors of soil excess static pore pressure caused by simple harmonic motion of underground water level outside the pit are studied. The influence of groundwater level fluctuation on soil and water pressure of foundation pit support structure is analyzed by example calculation. The results show that when the dimensionless factor value is small, the overstatic pore pressure in soil rapidly attenuates with the increase of depth, the pore pressure fluctuation of each depth has obvious phase difference, and with the increase of dimensionless factor value, The attenuation amplitude of overstatic pore pressure along the depth direction is slowed down, the phase difference decreases, and its response amplitude and influence depth increase. The influence of the fluctuation of groundwater level outside the pit on the total pore pressure of the active side, the vertical effective stress of soil and the total lateral pressure is obvious, but the influence on the passive side is relatively small. When the groundwater level rises, that is, the excess static pore pressure is positive, the stability of foundation pit is unfavorable to the supporting structure of foundation pit.
【作者单位】：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;
【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)
【分类号】：TU46

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