New method for measuring groundwater level under vacuum preloading

Because of their technical disadvantages,the conventional methods are unsuitable to measure the groundwater level in the soft ground reinforced by vacuum preloading.The results obtained by the conventional methods are not the true groundwater level under negative pressure.A new method for measuring the groundwater level is introduced.The special design of inside and outside pipes is used to prevent the normal atmospheric pressure from entering the inside of the pipes.In addition,the groundwater level can be directly measured by the magnetic ring floating on the water surface.Based on the field tests for comparing the new method with the conventional methods,it is concluded that the working principles and apparatus of the new method are simple,with the advantage of no loss of vacuum pressure,so the groundwater level measured by the new method is reliable.Finally,some problems of the new method are discussed and some improvements are presented.