植被根系形态对边坡稳定性的影响分析

针对裸露边坡大量增加导致破坏自然植被、威胁边坡稳定性等问题,以植被护坡的力学效应为重点,采用的经典WU模型对植被根系附加凝聚力进行数值模拟,并在工程常用岩土软件Geo Studio的基础上建立了基于二维有限元方法的植被护坡模型。应用植被护坡模型分析了不同乔木类型以及不同边坡类型对边坡稳定性的影响,对JI模型和ZHANG模型进行模拟计算,验证了模型的可行性。结果表明:无论是直坡还是阶梯状边坡,植被根系都可以提高边坡稳定性,安全系数增量最高可达39.7%。相同附加凝聚力下,Tap型根系对安全系数的提高效果大于Plate型根系。黄土边坡平整为阶梯状后安全系数提高(刺槐坡安全系数增量为8.3%,侧柏坡为8.2%);砂土和粉土的直边坡更稳定。研究成果对植被根系护坡模拟和生态护坡基础建设具有重要的借鉴意义。

Analysis on effect of vegetation root-system morphology on slope stability

Aiming at the problems of that huge increase of bare slope leads to damage of natural vegetation，threat on slope stability，etc. ，the additional cohesion from vegetation root-system is simulated with the classical WU model by taking the mechanical effect of the vegetation slope protection as the key point of the study，while a 2 － D finite element method-based vegetation slope protection model is established on the basis of the conventional geotechnical software-GeoStudio. The vegetation slope protection model is applied to analyze the effects of various kinds of trees and various types of slopes on slope stability，and then simulative calculations are made on both JI model and ZHANG model，thus the feasibility of the model is verified. The result shows that whether it is a constant slope or a stepped slope，the vegetation root-system can improve the slope stability along with the maximum increment of the safety coefficient up to 39. 7%. Under the condition of the same additional cohesion，the enhancing effect of the root-system of Tap type on the safety coefficient is larger than that from the root-system of Plate type. The safety coefficient is to be increased after leveling loess slope into the slope of a stepped type( the increment of the safety coefficient is 8. 3% for the slope covered with acacia and is 8. 2% for the slope covered with arborvitae)，while the constant slopes of sandy soil and silty soil are more stable. The study result has an important referential significance for both the simulation of vegetation root-system slope protection and the fundamental construction of ecological slope protection.