真空预压技术加固软土地基的现场试验研究

A Field Study of Reinforcing Soft Foundation by Vacuum Preloading Method

结合上海某机场跑道真空预压加固软基的试验成果,对加固试验区的地表沉降及其估算方法,不同深度处的超孔隙水压力消散和加固效果等方面进行了研究。结果表明,加固区土体沉降从大到小依次为场地中央、场地边缘和场地角落,反映出真空预压的空间效应;当真空度发生变化时,加固区竖向排水体负压沿深度的分布基本一致,负压范围集中在58～65kPa,约占膜下真空度的68%～76%;该地基表面沉降能够联合竖向等效渗透系数、一维太沙基固结理论和分层总和法进行估算。

Through studying the experimental results on reinforcing soft foundation by vacuum preloading on an airdrome runway in Shanghai City, surface settlement and its calculation method, dissipation of excessive pore water pressure, and reinforcing effects on test zone are discussed. The testing data indicate that the set- tlement in test zone, from large to small, is observed in center, margin, and corner of site and this reflects the effects of vacuum preloading method. When vacuum degree changes, the distribution of suction pressure with depth in drained body of test zone is almost equal. The range of suction pressure is 58~65 kPa, i. e. , 68~76~ of vacuum degree under seal membrane. Furthermore, the analysis show that the estimation of surface settlement of soft foundation may be carried out through combining vertical equivalent penetration coefficient, Terzaaghi＇s one dimensional-consolidation theory, and layerwise summation method.