真空预压全过程有效应力变化

真空负压在地下水位线以上及以下的传递规律、真空预压过程中地下水位线以上及以下部分有效应力增加的机理等问题,目前学界各方的认识并不统一。通过对真空预压全过程孔隙总水头的变化引起有效应力变化规律的分析,从另一角度探讨了真空负压在软土中的传递规律。结果表明:真空负压在软土水位线以上及以下均会传递,并随渗透阻力而衰减;真空负压及地下水位下降均会引起软土水上、水下任一点有效应力的增加,水上、水下有效应力增量的表达形式是统一的;地下水位埋深与真空预压的加固效果相关,埋深越大,加固效果越差;加固过程中,地下水位下降,但下降幅度不大。

Changing of effective stress in the whole process of vacuum preloading

At present,academic circles do not have a unified understanding of vacuum negative pressure transfer law above and below the underground water level,and of mechanism of effective stress increase above and below the underground water level in the process of vacuum preloading.This paper analyzes the changing of effective stress caused by the total pore water-head change in the whole press of vacuum preloading,and discusses the transfer law of vacuum negative pressure in soft soil from another angle.The research results show that the vacuum pressure can be transferred not only above the underground water level,but also below it.It will decrease with the penetration resistance;both the vacuum pressure and the lowering of groundwater level will cause the increase of soft soil effective stress at any point,and the increasing effective stress expression is uniform for any point both above the underground water level and below it;the degree of vacuum preloading reinforcement is associated with the depth of the underground water level,and the deeper,the worse the reinforcement effect;in the process of reinforcement,the groundwater level will decline,but do not drop.