南水北调中线工程膨胀土渠道保护层厚度研究

Research on protection layer thickness for expansive soil channel of Middle Route Project of South-to-North Water Diversion

为有效确定膨胀土渠道保护层厚度,以南水北调中线工程河南南阳境内膨胀土渠道为例,从平衡膨胀力和维持膨胀土含水率相对稳定两个方面,对中、强膨胀土进行了研究。结果表明:平衡膨胀力时所需的膨胀土保护层厚度,可根据膨胀土的膨胀率、天然密度和保护层填筑施工前的初始含水率,通过K0应力状态下膨胀土的有荷膨胀率模型计算;根据现场试验数据的分析结果,水泥改性土的渗透系数不大于10-5cm/s时,埋深1 m以下的膨胀土含水率已基本不受外部环境影响。

For effectively determining the protection layer thickness for expansive soil channel, a typical channel of Middle Route Project of South-to-North Water Diversion in Nanyang area, Henan Province is selected as an example, and the medium and strong expansive soil are studied in terms of resisting expansion force and the water content maintaining soil body stable. The results show that the protection layer thickness required to resist the expansion could be determined by loaded expansion model of K0 stress condition, the model input parameters include expansion ratio, natural density and initial water content before protec-tion layer construction. According to analysis results of the in-situ data, when the permeability coefficient of cement-modified soil is less than 10 -5 , a protection layer with thickness of 1m could protect the water content of expansive soil from the influence of outside environment.