承压水越流对地下结构浮力影响试验研究

Experimental study on influences of leakage of confined water on buoyancy of underground structures

针对承压水地层中地下结构受到浮力预测不准确的问题,开展存在地下结构的土层中竖向渗流模型试验,考察不同环境中的承压水渗流对地下结构的浮力影响。主要探讨不同水力梯度下均质土层中竖向渗流及承压水向上穿越弱透水层渗流时,所产生的孔隙水压力变化规律及其对地下结构的浮力的影响特点。试验表明:存在渗流时,土中孔压分布和地下结构浮力与静水压力不符;均质土中竖向渗流时,孔压和浮力较同深度理论值的提升比例与竖向水力梯度成正比;承压水在上覆弱透水层中渗流时,弱透水层中孔压和浮力的提升比例要大于强透水层,且土分层界面处孔压和浮力的提升比例最大,约为2倍的水力梯度。

In order to solve the problem that the prediction of the buoyancy of underground structures in confined aquifer is inaccurate,a series of model tests on the impact of confined aquifer seepage on the buoyancy of underground structures are conducted.Two cases are studied:(1)the vertical seepage in homogeneous soil layer;(2)the vertical seepage of the confined water through overlying aquiclude.The influences of the seepage on the buoyancy of the underground structure under different hydraulic gradients in both cases are investigated.The results show that the pore pressure distribution and the buoyancy of the underground structures are not consistent with those obtained from hydrostatic pressure when the seepage occurs.And they are usually larger than those obtained from hydrostatic pressure.The raising ratio of the pore pressure and buoyancy to the theoretical value based on hydrostatic pressure equals to the vertical hydraulic gradient in case the vertical seepage occurs in homogeneous soil.The raising ratio of the pore pressure and buoyancy to the theoretical value based on hydrostatic pressure is much larger than the hydraulic gradient in case the confined water seeps in the overlying aquiclude,which is obviously different from that in homogenous soil.In the case herein,the raising ratio is about 2 times the hydraulic gradient.