真空预压地基土体沉降及强度增长特征

Soil settlement and strength increasing characteristics in vacuum-preloaded foundation

结合目前对真空预压的理论认识和工程实践,对某工程真空预压地基土体的孔隙水压力消散、沉降、物性参数、强度参数的变化特征进行分析。结果表明:孔隙负压消散量受土体扰动及沉降导致的排水板弯折和淤堵的影响较大,可能导致其不简单地随深度增大而减小;计算吹填土的沉降量时,经验系数可取大些,下部原位土体的沉降经验系数可适当取小些;加固后的土体物性参数及强度参数明显变好,且在排水板底深度以下仍有强度增长。结合监测数据的分析结果,对真空预压的有效深度和加固效果进行讨论。结果表明:土体的有效加固深度受真空负压和土体排水阻力的综合影响;在排水板深度范围内的土体加固效果明显,而该深度以下的加固效果则随深度增大逐渐降低并最终趋于无。

Based on the theoretical understanding and engineering practice, we analyze the variation characteristics of pore water pressure dissipation, settlement, physical properties and strength properties of vacuum- preloaded foundation soil, which indicates that： The value of pore water pressure dissipation is affected significantly by curving and clogging of PVD caused by disturbances of soil structure and settlement, making it do not simply decrease with the increase of the depth; The empirical coefficient of dredger fill can be a little larger, and the undisturbed soil can be a little smaller; The physical properties and the strength properties are improved obliviously, and the soil under the depth of drain boards are also improved. According to the analyzing result of the monitoring data, we discuss the effective depth and strengthening effect of vacuum preloading method, which reveals that： The effective strengthen depth of soil is affected by the value of vacuum and drainage resistance; The strengthening effect of soil within the depth range of drainage board is obvious, and that below the depth range of drainage board will reduce gradually with the depth increase and reach to no effect at last.