A Hansbo's consolidation solution of sand-drained ground with impeded boundaries under vacuum and surcharge preloading
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摘要: 把砂井地基上下邊界視為半透水邊界,以研究頂部墊層和底部下臥層透水特性對砂井地基固結過程的影響.根據軸對稱固結方程和等應變假定,利用Hansbo法獲得了真空聯合堆載預壓下半透水邊界砂井地基的固結解答,分析了上下邊界透水系數對真空和堆載預壓固結度和沉降的影響,比較了真空單獨預壓下本文解與Indraratna等解答和周琦等解答的聯系和差別.研究表明,(1)不管真空預壓還是堆載預壓,固結時間因子相同時地基固結度隨邊界透水系數增大而增大.(2)對于真空預壓,下邊界透水系數越大,地基的最終沉降越小,固結期間時間因子相同時的沉降也越小;上邊界透水系數越大,固結期間時間因子相同時的沉降越大.(3)對于堆載預壓,不管上邊界還是下邊界,邊界透水系數越大,最終沉降不變,而固結期間時間因子相同時的沉降越大.(4)當真空預壓上邊界透水時,周琦等解答的固結度大于本文解答的固結度大于Indraratna等解答的固結度.為了提高真空預壓的最終沉降,需減少地基下邊界的透水性.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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參考文獻
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