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依托同三高速公路扩建工程方正—哈尔滨段路基加宽一侧粉砂质黏土路堑边坡,采用室内三轴实验、现场监测、原位测试等方法,开展了路堑边坡冻融失稳及植被护坡实验研究。三轴实验结果表明:在土体含水率小于最佳含水率时,土体黏聚力随含水率的增加而增大,超过最佳含水率时,黏聚力随含水率增加而减小,在最佳含水率附近达到峰值;土体内摩擦角随含水率的增加而减小。土体黏聚力随冻融循环次数的增加而降低。现场监测结果表明:边坡土体冻结的过程中,水分向冻结锋面迁移;木本护坡植物要比草皮有明显的吸水作用,紫穗槐表现的更加明显。现场直剪实验得出:木本植物根系复合土的抗剪强度比素土的抗剪强度明显增大,在同一坡面相近位置,采用紫穗槐和胡枝子护坡时,其根系复合土的抗剪强度比素土的抗剪强度大2倍左右。理论分析表明:有效地减小坡面荷载,可增加边坡稳定安全系数。
Relying on the widening of silty clay cutting slope on the side of Forklift in Harbin-Forklift Section of Tong-San Expressway, three-axis experiment, on-site monitoring and in-situ testing were carried out to analyze the instability and vegetation of the slope Slope protection experiment research. The results of triaxial tests show that when the soil moisture content is less than the optimum moisture content, the cohesion of soil increases with the increase of water content. When the water content exceeds the optimum moisture content, the cohesion decreases with the increase of water content, Peaked near the best moisture content; soil friction angle decreased with the increase of water content. Soil cohesion decreased with the increase of the number of freeze-thaw cycles. The field monitoring results showed that during the freezing process of soil, the water migrated to the frost front; the wood-based slope protection plants had obvious water absorption effect on the turf and the Amorpha fruticosa appeared more obvious. The result of direct shear test shows that the shear strength of root complex soil of woody plants is obviously higher than that of plain soil. When using Amorpha fruticosa and Lespedeza bicolor on the same slopes, the root composite soil Shear strength than the shear strength of soil about 2 times larger. Theoretical analysis shows that the slope safety factor can be increased by effectively reducing the slope load.