ISSUES AND CONTERMEASURES FOR MEASUREMENT AND ANALYSIS OF PORE WATER PRESSURE

Based on several traditional plugging methods in pore water pressure measurement with technical difficulties,a new plugging technique is presented,and some in-situ contrast tests in a soft soil engineering consolidated by vacuum preloading in Guangzhou Nansha was performed.Test results show that it is difficult to plug the hole among the piezometers using the traditional hole-breakdown method because the piezometers will not be separated and differences of the pore water pressure in different depths will be the same,which will cause great measure errors.The newly employed plugging device can effectively be separated,and the differences of the pore water pressure in the different depths will not be same.So the test results with more accuracy can be obtained,and it is convenient for construction and the positions of piezometers can be accurately controlled.The influences of variations of the settlement and groundwater level to pore water pressure are analyzed.The greater variations of the settlement and groundwater level are,the greater variation values of pore water pressure are.Test results also show that the variable values of pore water pressure caused by the variations of settlement and groundwater level can reach to 20 kPa,which should be deducted when analyzing the dissipation of the pore water pressure or the distribution mode of excess pore water pressure.