Study on Change of Vacuum Degree and Pore Water Pressure in Silt Foundation

Analyzing the relations between the vacuum degree and pore water pressure in silt is of great significance to the research on vacuum preloading.According to the field measured data of vacuum-surcharge preloading,the change of the vacuum degree and excess pore water pressure in silt foundation is analyzed here,and the inquisition to the relevance of them is made.The test results show that the vacuum degree in silt has a start-up process,with the increase of vacuum time,its value falls gradually to a steady state;During vacuum pumping,the biggest dissipation values along the depth direction of pore water pressure are basically same,and the excess pore water pressure and vacuum degree are same above the groundwater level in silt,but below the groundwater level,the vacuum degree is smaller than the excess pore water pressure,the dissipation of pore water pressure is mainly caused by the drop of groundwater level due to vacuum pumping.