INFLUENCES OF GROUNDWATER LEVEL FLUCTUATION ON THE STABILITY OF GRAVITY RETAINING WALL OF PITS
YING Hongwei1，2，NIE Wenfeng3，HUANG Dazhong4
(1. Research Center of Coastal and Urban Geotechnical Engineering，Zhejiang University，Hangzhou，Zhejiang 310058，China； 2. MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering，Zhejiang University，Hangzhou，Zhejiang 310058，China；3. Kunming Survey，Design and Research Institute Co.，Ltd. of CREEC，Kunming，Yunnan 650200，China；
4. Third Railway Survey and Design Institute Group Corporation，Tianjin 300251，China)
Abstract：Groundwater level in coastal region fluctuates periodically due to wave or tides. The response of the pore pressures of the ground near the retaining wall is vital for pit excavation. In this study，a single layer ground with finite thickness around the pit to be excavated was considered to be isotropic and homogeneous. The fluctuating water level at the boundary was assumed to be a sinusoidal function. The seepage area around the pit was divided into three zones. Assuming the total stresses of soil keeping constant，the two-dimensional consolidation equations were decoupled. A semi-analytical solution of pore pressure of the ground around the pit with gravity retaining wall in response to the groundwater level fluctuation was derived with Laplace and Fourier transforms. The comparisons with the results from finite element software PLAXIS verified the proposed method. An example was presented to investigate the pore pressure response around the pit and its influence on the stability of the retaining wall via the above semi-analytical solution. The results show that the amplitude of pore pressure attenuated along the seepage path from the back to the front of the retaining wall，while the phase lag increased. The stability of the retaining wall fluctuates and has phase lags too as the groundwater level fluctuating.
2014, Vol. 33 
