草根对开封城墙土抗剪性能影响

Grass Roots Influence on Shear Performance of Kaifeng City Wall Soil

为研究草本植物根系对开封城墙坡面土的影响,进行颗粒筛分实验、击实实验、界限含水率实验和直剪实验,研究城墙坡面土的颗粒级配、最佳含水率、最大干密度、塑性指数,探索5种典型草本植物不同根系掺量时根土复合体抗剪强度指标变化规律.实验表明:城墙坡面土为低液限黏土,级配良好,最佳含水率为13.918%,最大干密度为1.812g/cm^(3),塑性指数为11.27%;与不含根系素土相比,根土复合体黏聚力增幅为17.15%~500.74%,内摩擦角变化幅度为-8.28%~10.43%.总体来看:随着灯心草、艾蒿、小蓬草、酸模、沿阶草的分别加入,根土复合体黏聚力增幅越来越明显;根土复合体内摩擦角变化与植物根系种类有关.

To study the influence of herbaceous roots on the slope soil of Kaifeng city wall,the particle sieve test,compaction test,limit moisture content test and direct shear test were carried out,respectively.Then,the particle gradation,optimum moisture content,maximum dry density and plasticity index of the city wall soil were studied.Finally,the shear strength index of the root-soil composites of 5typical herbaceous plants with different root contents were explored.The results show that the soil in the slope of the city wall belongs to low liquid limit clay,with good grain size grading,the optimum moisture content of 13.918%,the maximum dry density of 1.812g/cm^(3),and plasticity index of 11.27%.Compared with the soil without roots,the cohesion of the root-soil composite increases by 17.15%-500.74%,and the internal friction angle changes from-8.28%to 10.43%.To sum up,the growing rate of the cohesion of the root-soil composite is more and more obvious,mixed with Juncus effusus,Artemisia argyi,Conyza canadensis,Rumex acetosa,and Ophiopogon bodinieri in order.The internal friction angle of root-soil composite varies with the types of plant root.