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负压分布规律是真空预压机理研究的重要课题。通过讨论真空预压负压空间分布特点及负压相关概念,广义地定义了负压,分析了负压的测量方法及影响因素。设计高15.0 m的竖向大比尺室内模型,开展真空预压负压分布规律试验研究。试验结果表明,饱和黏土土中真空度测量存在滞后效应,本次试验真空度存在的极限深度为8.9 m;膜下真空度稳定后,零压面之上孔压及板中真空度沿深度呈对称线性分布,斜率均近似为静水压力梯度;负压沿深度为分段线性分布,在地下水位之上的非饱和段因提水做功而衰减,稳定期负压平均衰减值为21.4 k Pa,在水位之下排水板埋深范围内基本均匀分布而无衰减,稳定期平均负压为-67.0 k Pa。结合试验规律及等效排水管中气液两相流的流型分布,给出了真空预压稳定期竖向排水板中的分段线性负压边界。
Negative pressure distribution law is an important issue of vacuum preloading mechanism. By discussing the spatial distribution characteristics of vacuum preloading and the related concepts of negative pressure, the negative pressure is defined in a broad sense, and the measurement method of negative pressure and its influencing factors are analyzed. A vertical large-scale indoor model with a height of 15.0 m was designed to carry out experimental research on the distribution of vacuum preloading pressure. The experimental results show that there is a hysteresis effect on the measurement of vacuum in saturated clay soil. The ultimate depth of vacuum in this experiment is 8.9 m. After the vacuum under the membrane is stable, the pore pressure on the zero pressure surface and the degree of vacuum in the plate along the depth Symmetric linear distribution and slope are similar to the hydrostatic pressure gradient. The negative pressure along the depth is piecewise linear distribution, and the unsaturated section above the groundwater level declines due to the pumping work. The average attenuation value of negative pressure in steady state is 21.4 kPa, Under the water level within the depth of the drainage board within the distribution of uniform and without attenuation, the average steady-state negative pressure of -67.0 kPa. Combined with the experimental rule and the flow pattern distribution of gas-liquid two-phase flow in the equivalent drainage pipe, the piecewise linear negative pressure boundary in the vertical drainage plate under the vacuum preloading was given.