排水板施工对软黏土扰动的现场试验研究

通过软黏土地基上塑料排水板施工过程的孔隙水压力观测及现场十字板强度试验,研究了排水板施工前后地基土体孔隙水压力增长和消散的规律,并且从软黏土地基的有效应力变化和结构扰动等方面分析了土体强度损失及恢复过程.结果表明:单根排水板施工引起的孔隙水压力增长较小,仅对表层孔隙水压力影响大;板群的施工对4 m范围内土体孔隙水压力的增长有叠加效应;排水板施工一方面使软土地基内的孔隙水压力增长,有效应力减小,导致软土强度的降低,另一方面使地基软土结构发生破坏而引起软土强度降低;孔隙水压力的增长引起的地基土强度损失恢复较快,而结构扰动引起的强度损失恢复较慢.

Field experimental study on soft clay disturbance due to construction of prefabricated vertical drains

Pore water pressure monitoring and vane shear testing were conducted during the construction of prefabricated vertical drains.The increase and dissipation of the pore water pressure before and after the vertical drain construction were investigated.According to the effective stress change and structure disturbance of soft ground,the process of soil strength loss and recovery were studied.Some conclusions are drawn: the increase of pore water pressure due to the construction of a single vertical drain is insignificant except for soil near the ground surface;the construction of group drains is of superposition effect on the increase of pore water pressure within a range of 4m;the vertical drain construction results in the decrease of soil strength because it increases the pore water pressure,decreases the effective stress,and destroys the soil structure;the recovery of soil strength loss caused by the increase of pore water pressure is fast,whereas,the recovery of that caused by structure disturbance is slow.