非饱和土在孔隙负压状态下的性能研究

Study on the performance of unsaturated soil under negative pore pressure

在近岸工程中,有许多的工程项目都面临软基处理问题.在软基处理中,真空-堆载联合预压最为常见,其原理就是利用孔隙负压来增加有效应力,因此,掌握孔隙负压的变化规律就尤为重要了.然而现阶段还未有成熟的试验装置可以准确测出孔隙负压.利用自主设计制作的试验装置进行室内试验,在试验室内准确测出孔隙负压及其变化规律,并将此装置应用推广到实际工程施工中.试验结果证明,非饱和土中确实存在孔隙负压,且孔隙负压的大小随地下水位的变化而改变;当地下水位低于测点处土体时,该处土体会出现孔隙负压,且其值随地下水位的下降而增大.

In the port engineering,there are many engineering projects facing the problem of soft foundation treatment.In the soft base treatment,vacuum surcharge preloading is the most common,and its principle is to use negative pore pressure to increase effective stress.Therefore,it is particularly important to master the changing law of negative pore pressure.However,there is no mature test device at this stage that can accurately measure the negative pore pressure.In this paper,the self-designed test device is used to carry out indoor test,and the pore negative pressure and its variation law are accurately measured in the laboratory,and the device is applied to the actual engineering construction.The test results show that pore negative pressure does exist in unsaturated soil,and the pore negative pressure changes with the change of groundwater level.When the groundwater level is lower than the soil at the measuring point,the pore negative pressure appears in the soil,and its value increases with the decrease of groundwater level.