Experimental study on variation of pore pressure of clay foundation during groundwater level fluctuation
Current research focuses on whether fluctuations in groundwater levels,induced by seasonal changes,i.e.,flood and dry season,and heavy rainstorms,can lead to flotation failure of underground structures in clay foundations.This study,employing a specially designed experimental setup,investigated the stress state of soil at three different depths.Firstly,the clay samples were subjected to initial consolidation pressure and water pressure to simulate the self-weight stress state at the respective depths.Subsequently,water pressure variations were applied to mimic the rising,falling,and declining water levels.The findings revealed that during water level elevation,pore water pressure escalated over time,stabilizing at over 92％of the theoretical value after 15 hours,and eventually approaching the theoretical value with a maximum deviation of 5％.Conversely,when the water level declined or fell back,pore pressure diminished over time,stabilizing at above 97％of the theoretical value after 15 hours,with a final variance of up to 4％from the theoretical value.Further analysis indicated that the pore water pressure remained stable at a hydraulic gradient range of 0.07 to 4.40.Under stable pore pressure,the denser the soil,the greater the hydraulic gradient was required for pore pressure stabilization.Notably,in practical engineering scenarios,a 20％fluctuation in water level generates a hydraulic gradient of approximately 0.067,below the minimum threshold inducing pore pressure changes.Therefore,such short-term fluctuations have minimal impact on the base water pressure,preventing flotation of underground structures.
国家科技期刊平台
NSTL
万方数据
维普
