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根据现场监测资料和检测数据,研究真空联合堆载预压处理大面积覆盖层下深厚淤泥质软土地基的表面沉降、超静孔压、深层沉降、侧向位移等固结变形特性和加固效果,结果表明:由于覆盖层的应力扩散和“顶托”作用,地表沉降曲线比较顺滑,高填土堆载过程中无明显“坡降”段;地基土体压缩变形主要发生在覆盖层下部的深厚淤泥质软土层,覆盖层较厚时不利于消除下卧层土体压缩量。孔隙水压的增长和消散受真空负压和填土堆载共同作用,与覆盖层厚度有一定的关系,覆盖层较薄时,孔隙水压响应较快,堆载引起的超静孔隙水压值较大;覆盖层较厚时,孔隙水压响应较滞后,孔隙水压曲线较平缓,堆载引起的超静孔隙水压值较小。厚覆盖层的存在不利于软土的排水加固,方案设计和施工时应予以重视。
According to the on-site monitoring data and testing data, the consolidation and deformation of the deep silty soft ground under large-area overburden by vacuum combined with surcharge preloading are studied, such as surface settlement, excess pore pressure, deep subsidence and lateral displacement The results show that the surface subsidence curve is relatively smooth due to the stress diffusion and the “top-supporting” effect of the overburden, and there is no obvious “slope fall” during the high-earth fill. The compressive deformation of the soil mainly occurs The deep muddy soft soil layer in the lower part of the overburden is not conducive to eliminating the amount of soil compression on the subsoil when the overburden is thick. The growth and dissipation of pore water pressure are affected by the vacuum negative pressure and the loading of fill soil and have a certain relationship with the thickness of the overburden. When the overburden is thinner, the pore water pressure response is faster and the overpressure When the cover is thicker, the pore water pressure response lags behind, the pore water pressure curve is gentle, and the excess pore water pressure caused by the pile loading is smaller. The existence of thick overburden is not conducive to the drainage of soft soil consolidation, program design and construction should be paid attention to.