真空预压中地下水位测试技术探讨与改进

阐述了地下水位的基本概念，分析了大气压状态和真空状态下地下水位的特征，认为地下水位就是重力水面，即重力水与毛细水的分界面。在大气压状态下，零压线就是地下水位；在真空状态下，零压线不是地下水位。根据受力平衡方程和气体状态方程，分析了传统测试技术存在的问题，认为传统水位测试管无法测得真实的地下水位，当水位管敞口时，所测得水位高度是零压线高度，水位变化实质上反映水位管滤管段的孔隙水压力平均消散情况；当水位管口密封时，也因无法保证水位管与加固区内膜下具有相同的真空度，导致测试结果具有较大的误差，且随着测试次数增多而增大。为此，提出了一种新的利用水位管内孔压计和真空表的读数计算得到真实地下水位变化值的测试技术，该技术能连续测试地下水位而不影响其测试结果。

Discussion and reform of groundwater level measuring technique in soft soil reinforced by vacuum preloading

The conception of the groundwater level is described; and the characters of the groundwater under the normal atmosphere pressure and vacuum pressure are analyzed; thus coming to the conclusion that the groundwater level is the top surface of the gravity water or the interface between the gravity and capillary water; and the zero pressure line is the ground water level when under the normal atmospheric pressure but not when under the vacuum pressure. Based on the force equilibrium equation and gas state equation, the existing problem for the conventional technique is analyzed. It is concluded that the conventional technique can’t measure the true groundwater level. The water height measured is really the zero pressure line and the water-level fluctuation essentially reflect the average dissipation of pore water pressure in filter zone when the mouth of pipe is always open; the big error will occur due to the difference of the vacuity between in the sighting pipe and under the sealed film when the mouth of pipe is always sealed and it will become bigger and bigger as the reading times increase. So a new measuring technique that the true groundwater level can be calculated according to the force equilibrium equation by using the readings of the pore pressure gauge and vacuum meter in the sighting pipe is presented. The new measurement device can continually measure the variation of the groundwater level but not influence the results.