南水北调南阳段弱膨胀土增湿膨胀与力学特性试验研究

为了研究膨胀土自然状态下的膨胀及力学特性，对南阳弱膨胀土进行了不同增湿程度时的膨胀及力学特性试验。通过对相同初始条件下不同增湿程度膨胀土的膨胀特性试验得到，随着含水率的增大自然膨胀力和有荷自然膨胀率均是先逐渐增大后有小幅减小再逐渐稳定，无荷膨胀率的变化趋势是前期接近线性的增大后逐渐稳定。通过不同增湿程度膨胀土的抗剪强度试验，建立了黏聚力、内摩擦角与增湿含水率的线性关系曲线及关系式。对于已建工程，通过监测含水率得到膨胀土的实时膨胀特性以及抗剪强度，进而评价工程的安全运行情况。

Experimental study of wetting expansibility and mechanical properties of weak expansive soil in Nanyang section of South-to-North Water Diversion Project

To study the expansibility and mechanical property of expansive soil in natural state, a series of expansion and mechanical property experiments, were carried out on Nanyang weak expansive soil with different humidifying degrees under the same initial condition. Through the experiments, the following conclusions are drawn: with the increase of humidifying moisture content, both natural expansibility and loaded natural expansion rate gradually increased at first, then slightly reduced, and finally became stable step by step. Load-free expansion rate almost increased in linear manner in earlier stage, then gradually became stable. By shearing strength experiments of expansive soil with different humidifying degrees, linear relation curve and relational expression between cohesion, internal friction angle and humidifying moisture content were developed. For completed projects, actual expansion property and shearing strength of expansive soil can be obtained by moisture content monitoring, which can be used to assess safety conditions of projects.