地下水位升降过程中的黏土地基孔压变化试验研究
Experimental study on variation of pore pressure of clay foundation during groundwater level fluctuation
唐逸凡 1焦艳梅 1刘新原 1齐大洪 2宋林辉1
作者信息
- 1. 南京工业大学数理科学学院,江苏 南京 211800
- 2. 徐州地铁集团有限公司,江苏徐州 221000
- 折叠
摘要
季节性丰枯水期和暴雨导致的地下水位升降是否会导致黏土地基中的地下结构上浮失效是目前备受关注的问题.采用研制的装置开展试验,参照3个深度处土体的应力状态,先对黏土试样施加初始固结压力和水压使其达到对应深度处的自重应力,后增减水压模拟水位上升、回落和下降.结果表明:当水位上升时,孔压随着时间的延长而增大,15 h后进入稳定状态,并在达到理论孔压的92％以上后缓慢增长,最后接近理论值,最终与理论值最大相差5％;当水位回落和下降时,孔压随着时间的延长而减小,15 h后进入稳定状态,在达到理论孔压的97％以上后缓慢降低,最终与理论值最大相差4％.测试结果的进一步分析发现,当水力梯度为0.07～4.40时,孔压处于稳定状态,土体越密实,孔压稳定时的水力梯度越大,而实际工程中20％幅度的升降水位形成的水力梯度约为0.067,未达到引起孔压变化的下限值,故其短期内对基底水压基本没有影响,地下结构不会上浮.
Abstract
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.
关键词
地下水位升降/黏土地基/孔压/水压/水力梯度Key words
groundwater level fluctuation/clay foundation/pore pressure/hydraulic pressure/hydraulic gradient引用本文复制引用
基金项目
国家自然科学基金(51578164)
国家自然科学基金(52106246)
江苏省自然科学基金(BK20200687)
江苏省研究生科研与实践创新计划(KYCX22-1280)
出版年
2024
国家科技期刊平台
NSTL
维普
万方数据