塔里木河流域河岸植被根系护坡的力学机制  

Mechanism of riverbank protection by desert riparian vegetation roots in Tarim River basin

作　　者：宗全利 冯博[2] 蔡杭兵[2] 陈志康 王建新 ZONG Quanli1, 2, FENG Bo2, CAI Hangbing2, CHEN Zhikang2, WANG Jianxin2(1. Key Laboratory of Yellow River Sediment, Ministry of Water Resourees, Zhengzhou, Henan 450003, China; 2. College of Water Conservancy and Civil Engineering, Shihezi University, Shihezi, Xijiang 832000, Chin)

机构地区：[1]水利部黄河泥沙重点实验室,河南郑州450003 [2]石河子大学水利建筑工程学院,新疆石河子832000

出　　处：《岩石力学与工程学报》2018年第5期1290-1300,共11页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51569029);水利部黄河泥沙重点实验室开放课题(2015005);石河子大学高层次人才专项(RCZX201529)~~

摘　　要：荒漠植被根系发达,能够有效稳定边坡、遏制水土流失。以塔里木河典型岸坡植被根系为研究对象,对塔里木河干流上、中游的6个典型河段进行现场勘查并取样,共取土样28组,17组为根–土复合体,包括红柳、甘草、骆驼刺、芦苇、胡杨、白刺6种植被根系。分别对6种不同植被的根–土复合体及相应的素土进行室内直接剪切试验,对比分析黏聚力和内摩擦角的变化规律,定量评价不同植被根系对河岸土体抗剪强度的增强效果;对6种植被根系进行单根抗拉试验,分析不同植被根系的抗拉强度及抗剪强度与根系直径的关系。试验结果表明:(1)根系能提高土体抗剪强度且主要是通过提高黏聚强度来实现的,对内摩擦角影响较小;(2)根–土复合体黏聚力普遍比素土高,6种植被根系下由3.14~16.51 kPa提高到9.43~28.30 kPa;(3)根系抗拉强度随直径的增大而减小,而抗拉力随直径增大而增大。通过分析根–土之间相互作用的力学特点,将根系假设为刚性状态和柔性状态,建立植物护坡中根–土相互作用的力学模型,分别推导出刚性状态下根系提高土体抗剪强度最大值以及柔性状态下根系提高土体抗剪强度最小值的计算公式,根据公式计算得出不同植被根系提高土体抗剪强度最大值和最小值范围,并与试验结果进行对比分析,结果表明:实测土体抗剪强度增加值全部在理论计算范围以内,说明模型计算方法的合理性,为实际工程植被护坡效应的评价提供理论依据。Desert riparian vegetation with rich roots can stabilize the slope and prevent soil erosion effectively. The vegetation of the riverside of Tarim River was studied. Six typical sections in the upper and middle reaches of Tarim River were surveyed. A total of 28 soil samples were obtained,of which 17 samples are root-soil composites including Tamarix ramosissima,Phragmites australis,Glycyrrhiza sp.,Alhagi sparsifolia,Nitraria sibirica and Populus euphratica. The direct shear tests were conducted for root-soil composites of six vegetation roots and soil samples without roots respectively. The cohesion and internal friction angle were compared and the effects of different vegetation roots on shear strength were analyzed. A single root tensile test was conducted forsix vegetation types to analyze the relationships between the tensile and shear strengths and the root diameter. The roots were found to enhance the shear strength of the soil through mainly the increasing of the cohesive strength,but had little effect on the internal friction angle. The root-soil composites have cohesions of 9.43 to 28.30 k Pa,higher than the rootless soil with values from 3.14 to 16.51 kPa. The tensile strength of root decreases with the increasing of root diameter,while the tensile force increases with the increasing of root diameter. Based on the analysis of mechanical characteristics of root-soil interaction,two models of the root and soil interaction were proposed with the assumptions of rigid and flexible roots respectively,representing the increased maximum and minimum shear strengths. The formulas of the increased maximum and minimum shear strengths with rigid and flexible roots were deduced. The calculated results agreed with the experimental values.

关 键 词：土力学 塔里木河干流 植被护坡 根–土复合体 力学模型 抗剪强度 

分 类 号：TU45[建筑科学—岩土工程]