半透水边界砂井真空联合堆载预压Hansbo固结解

A Hansbo's consolidation solution of sand-drained ground with impeded boundaries under vacuum and surcharge preloading

  • 摘要: 把砂井地基上下边界视为半透水边界,以研究顶部垫层和底部下卧层透水特性对砂井地基固结过程的影响.根据轴对称固结方程和等应变假定,利用Hansbo法获得了真空联合堆载预压下半透水边界砂井地基的固结解答,分析了上下边界透水系数对真空和堆载预压固结度和沉降的影响,比较了真空单独预压下本文解与Indraratna等解答和周琦等解答的联系和差别.研究表明,(1)不管真空预压还是堆载预压,固结时间因子相同时地基固结度随边界透水系数增大而增大.(2)对于真空预压,下边界透水系数越大,地基的最终沉降越小,固结期间时间因子相同时的沉降也越小;上边界透水系数越大,固结期间时间因子相同时的沉降越大.(3)对于堆载预压,不管上边界还是下边界,边界透水系数越大,最终沉降不变,而固结期间时间因子相同时的沉降越大.(4)当真空预压上边界透水时,周琦等解答的固结度大于本文解答的固结度大于Indraratna等解答的固结度.为了提高真空预压的最终沉降,需减少地基下边界的透水性.

     

    Abstract: The top and bottom boundaries of sand-drained ground were visualized as impeded boundaries to investigate the effects of the pervious behaviors of the cushion above the top and the substratum below the bottom during the consolidation process of sand-drained ground. Based on the axisymmetric consolidation equations and the equal strain assumption, the consolidation solution of sand-drained ground with impeded boundaries was obtained using Hansbo's method for vacuum and surcharge preloading. The effects of the pervious coefficients of top and bottom boundaries on the consolidation degrees and settlements of vacuum preloading and surcharge preloading were analyzed. The similarities and differences between the solution and Indraratna et al.,'s solution and Zhou et al.,'s solution were compared under vacuum preloading alone. The results reveal the following:(1) for either vacuum or surcharge preloading, the consolidation degree of the ground increases with the increasing pervious coefficients of the boundaries when the consolidation time factor is the same; (2) for vacuum preloading, the larger the pervious coefficient of the bottom boundary is, the smaller the final settlement of the ground is, and the smaller is the settlement at the same time factor during the consolidation process; the larger the pervious coefficient of the top boundary is, the greater is the settlement at the same time factor during the consolidation process; (3) for surcharge preloading, the larger the pervious coefficient of the bottom or top boundary is, the larger is the settlement at the same time factor during the consolidation process while the final settlement remains constant; (4) when the top boundary is permeable during vacuum preloading, the consolidation degree of Zhou et al's solution is higher than the consolidation degree of the proposed solution, and the consolidation degree of the solution is higher than the consolidation degree of Indraratna et al's solution. The level of perviousness of the bottom boundary of ground should be reduced to increase the final consolidation settlement under vacuum preloading.

     

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