粉砂土岸坡三维加筋生态护坡结构力学效应研究

加筋生态护坡是土工织物与植草相结合形成的一种护坡形式,在保证工程生态性的同时大大提高了生态护坡的强度,有广泛的应用前景。以黑龙江同抚堤防工程粉砂土岸坡防护工程为例,开展了三维加筋生态护坡结构的现场原位测试与加筋土体力学特性室内试验研究,揭示了该护坡技术固土护坡力学效应。试验结果表明:对比纯植被护坡和遮阳网表层覆盖护坡方式,三维加筋生态护坡结构对土体加筋作用最为有效。土工网可以帮助植被根系在岸坡表层形成良好的加筋层,而植被根系则帮助土工网与岸坡土体更紧密地结合。加筋生态结构效果主要表现为增加了土体黏聚力,但对内摩擦角影响不大;一个生长周期内草本型植被根系加筋区域集中在地面以下20cm左右的深度;土体含水率和含根量对根土复合体抗剪强度有明显影响,随着土体中含根量和含水率的增加,根土复合体抗剪强度呈先增加后减少的趋势,即对于高羊茅这类抗剪型根系,其加固土体时存在最佳含根量和含水率使其强度最高。

Mechanical effect of three-dimensional reinforced eco-structure on silty sand slopes

The reinforcement turf is a form of slope protection combined with geotextile and grass. It greatly improves the strength of ecological slopes and ensures the ecology and has a wide application prospect. Taking the bank slope protection of silty sand in Tongfu embankment in Heilongjiang Province as an example, the field in-situ tests on 3D reinforcement eco-structure for slope protection and laboratory experiments on the mechanical properties of reinforced soils are carried out, and the mechanical effects are revealed. The experimental results show that: (1) Compared to pure vegetation slope protection and slope protection of surface covering by sunshade net, 3D reinforced turf structure is the most effective for soil reinforcement. The geotextile mat can help vegetation roots to form a good reinforced layer on slope surface, and the vegetation root system helps geotextile mat to be more closely combined with slope soils. (2) The effect of reinforced turf mainly increases the soil cohesion, but has little effect on the internal friction angle. In a growth period, the root reinforcement effect of herbaceous vegetation is concentrated at the depth of 20 cm below the ground. (3) The effect of soil moisture content and root content on the shear strength of root-soil complex is obvious. With the increase of soil root content and moisture content, the shear strength of root-soil complex increases firstly and then decreases or remains unchanged. For the shear-resistant roots, such as tall fescue, there is an optimal root content and moisture content to make the soil strength be the highest.