真空预压中真空度与孔隙水压力的关系分析

Analysis of relationship between vacuity and pore-water pressure in vacuum preloading

真空度与孔隙水压力是两个不同的概念,在土体中某点真空表测试的真空度与测点处的孔压差并不相同,但它们有着内在的联系。根据气体状态方程和平衡方程,推导出在某点真空表反映的真空度值与孔压计反映的孔压差的理论关系式。测点在地下水位以上时,两者的测试结果是一致的;测点在地下水位以下时,真空度小于孔压差,两者可按公式进行换算。测试结果表明:现场实测结果与理论计算结果基本吻合,证实了理论推导的正确性,也说明了真空表内真空度与孔隙水压力的关系。

Vacuity and pore-water pressure are two different conceptions, the vacuity measured by vacuum meter in the soft soil is different from the difference of pore-water pressure measured by piezometer; but there is an immanent relation between them. The theoretical formula about vacuity in vacuum tube and pore-water pressure at the observation point was obtained in this paper by using equation of gas state and equilibrium equation. When the observation point is above the groundwater surface, the vacuity is the same as the difference of pore-water pressure. When the observation point is under the groundwater surface, the vacuity is less than the difference of pore-water pressure, but they can be calculated each other by using the theoretical formula. The test results explain the relations between the vacuity and the pore-water pressure and show that the theoretical fnrmula is correct.