岸坡荒漠植被根系对土体力学性能的影响研究(摘要)

宗全利1，2，冯博1，袁寄望1，王建新1，唐建3

(1.石河子大学水利建筑工程学院，新疆　石河子　832000；2.水利部黄河泥沙重点实验室，河南　郑州　450003；3.塔里木河流域干流管理局上游管理处，新疆　阿拉尔　843300)

【摘　要】　干旱地区荒漠植被根系发达，其增强土体力学性能并保持河岸稳定和固土护堤的作用尤为重要。为研究塔里木河干流上游岸坡荒漠植被根系对土体抗剪强度的增强作用，本文在初步分析流域植被覆盖现状基础上，对上游5个典型河岸进行了现场勘查，对无植被覆盖原状土体和植被覆盖根-土复合体分别进行了9组和11组的对比取样，并进行了室内土工试验。试验结果表明植被覆盖土体的黏聚力明显比无植被覆盖土体黏聚力大，增加的幅度为31.5%～1341.9%；而内摩擦角变化不明显，增加幅度为0.8%～7.1%.结合准黏聚力原理和加筋土原理，定量分析了典型荒漠植被根系(骆驼刺、红柳、芦苇)对河岸土体抗剪强度的影响，得到了不同类型植被根系覆盖土体附加黏聚力与根面积比的线性函数关系以及根-土复合体抗剪强度的表达式。根据结果，对骆驼刺、红柳和芦苇三种植被不同根面积比对应的根-土复合体抗剪强度进行了计算，并与实测结果进行对比，结果表明计算结果与实测值基本一致，平均相对误差为3.17%，充分说明得到的根-土复合体抗剪强度计算公式完全可以用于上述三种典型荒漠植被根系影响下的抗剪强度计算，为定量评价荒漠植被根系的固土能力提供一定的参考。

【关键词】　塔里木河干流；荒漠植被根系；根-土复合体；抗剪强度；根面积比

基金项目：国家自然科学基金项目(51569029)；水利部黄河泥沙重点实验室开放基金(2015005)。

作者简介：宗全利(1979—　)，男，山东临朐人，教授，博士，主要从事河流动力学研究。

E-mail：quanli1871@126.com

Study on Increased Soil Shear Strength from the Roots of Desert Riparian Vegetation

ZONG Quanli1,2,FENG Bo1,YUAN Jiwang1,WANG Jianxin1,TANG Jian3

(1.College of Water Conservancy and Civil Engineering,Shihezi University,Shihezi Xinjiang Uygur Autonomous Region　832000;2.Key Laboratory of Yellow River Sediment,Ministry of Water Resources,Zhengzhou Henan Province　450003;3.Upstream Management Office of Main Stream Management Bureau of Tarim River,Alar Xinjiang Uygur Autonomous Region　843300)

Abstract:The roots of desert riparian vegetation in arid areas are well developed,which have important influences on strengthening the soil mechanics performance,maintaining the stability of the river bank,keeping the soil and protecting the embankment.In order to investigate quantitatively the increased soil shear strength from the roots of desert riparian vegetation in the upper reach of the main stem Tarim River,a field observation and indoor soil tests were first conducted at 5 typical riverbanks in the reach with the vegetation covering being analyzed preliminarily.9 soil samples with no vegetation being covered and 11 root-soil composites samples with vegetation being covered were obtained,respectively.Through analyzing the experimental results,the cohesive and internal friction angle of root-soil composite with vegetation being covered were identified,which indicated that the cohesive with vegetation being covered is obviously larger than that of no vegetation being covered soil with an increase of 31.5%-1341.9%,but the increase of the internal friction angle is not obvious with an increase of 0.8%-7.1%.Based on the principle of quasi-cohesion and reinforced soil,the influences of typical roots of desert riparian vegetation on the soil shear strength were analyzed quantitatively,which the typical vegetation are manaplant alhagi,branchy tamarisk and bulrush.A new linear function relation between the additional cohesion and the area ratio between the root and soil,and the shear strength relationship of root-soil composites were then proposed,under different types of vegetation roots.The shear strength values of root-soil composites were calculated with different area ratio between the root and soil for manaplant alhagi,branchy tamarisk and bulrush.The calculated results were compared with the measured values which indicated that the calculated results are in agreement with the measured values with the average relative error 3.17%.It was concluded that the calculated formula of shear strength of root-soil composite can be used to calculate the soil shear strength influenced by above three typical desert vegetation roots,which can provide some reference on evaluating the capacity of keeping soil of desert riparian vegetation roots.

Key words:Main Stem Tarim River;Roots of Desert Riparian Vegetation;Root-soil Composite;Shear Strength;Area Ratio Between the Root and Soil