含水率变化对荆江河岸黏性土体力学特性的影响

河岸土体的物理及力学特性是影响崩岸过程的主要因素之一。为研究土体含水率对荆江河岸土体力学特性的影响,于2017年对荆江8个典型崩岸断面进行调查取样,采用实测资料分析、室内土工试验和理论分析相结合的方法,全面地分析了荆江河岸土体组成及力学特性;并结合2016年实测数据定量研究了含水率对荆江河岸黏性土体抗剪强度指标的影响,以及含水率变化对河岸稳定性的影响。结果表明:荆江河岸为上部黏性土、下部非黏性土的二元结构;随含水率的增大,黏聚力先增大后减小,而内摩擦角持续减小;通常黏粒含量越大,其黏聚力峰值越大;含水率与抗剪强度指标存在定量关系;河岸在枯水期稳定性较高,在涨水期较为稳定,在洪水期和退水期稳定性较差。研究结果可供河岸崩岸治理工程技术人员参考。

Influence of Water Content Variation on Mechanical Properties of Riverbank Cohesive Soil of Jingjiang River Reach

Bank retreat is affected by the physical and mechanical properties of riverbank soil as a major factor. To research the influence of water content on the mechanical properties of riverbank soil of Jingjiang River reach, the composition and mechanical properties of soils on Jingjiang riverbank were examined in a holistic sense via data analysis, indoor test and theoretical analysis; moreover, the effect of water content variation on the shear strength indicators of cohesive soil on Jingjiang riverbank and further on the riverbank stability was quantified using measured data of 2016. Eight typical bank retreat sections were sampled in 2017. Results suggest that the soil composition in the Jingjiang River reach is characterized by a typical composite structure involving cohesive upper layer and non-cohesive lower layer. With the augment of water content, cohesion of soil increased first and then decreased, while internal friction angle reduced continuously. In general, higher content of cohesive particles leads to greater peak value of cohesion. In addition, the formulae between water content and shear strength indicators are given. The stability of riverbank in dry season is fairly good, larger than that in rising stage; but in flood season and recession stage, riverbank stability is undesirable.