直根系根-土复合体抗剪强度简易计算方法

为了简化直根系根-土复合体抗剪强度的计算,基于根-土相互作用机理,考虑复合土体中根系的破坏模式,对直根系根-土复合体进行受力分析,推导了根-土复合体抗剪强度计算公式,将计算结果与现场实测值进行对比,并对折减系数、含根量、植物种类根-土复合体抗剪强度的主要影响因素进行了参数分析。结果表明:根-土复合体黏聚力是土层深度的指数函数;法向应力不变时,复合土体的抗剪强度随折减系数的增大而增大,折减系数在0.84~0.86之间取值时,结果较接近实测值;且复合土体的抗剪强度随含根量的增大呈先增大后减小的趋势,存在一个使复合土体抗剪强度最大的最优含根量;法向应力增大时,直根系复合土体的抗剪强度也随之增大,采用理论公式计算的抗剪强度值与实测值相对误差在10%以内。研究成果可为边坡生态防护的设计和计算提供理论参考。

A Simplified Calculation Method for Shear Strength of Tap Root-Soil Composite

A simplified formula for calculating the shear strength of tap root-soil composite is derived based on the stress analysis of tap root-soil composite in consideration of the failure mode of root system. The calculation results are compared with field measured values. Moreover, the influences of reduction coefficient, root weight, and plant species on the strength of the root-soil composite are also investigated. Results imply that the cohesion of the composite is an exponential function of soil depth. When normal stress is constant, the shear strength of the composite increases with the augment of reduction coefficient. When the reduction coefficient is in the range of 0.84-0.86, the result is closer to the measured value. In addition, the shear strength of the composite increases with the increase of root weight, and then decreases gradually. A optimum root weight is found to make sure a maximum shear strength. With the normal stress increasing, the shear strength of the composite is also increasing. The relative error between calculated shear strength and measured strength is kept within 10%.