植筋带联合植物护坡的水力特性数值分析

Numerical analysis of hydraulic characteristics of slopes reinforced by vertical geotextile belts and vegetation

植筋带(延长根)的抗拉强度能发挥比根系更长的力学加筋作用,但又会对降雨影响深度等产生影响,进一步改变边坡内部水力响应情况。因此本文对植被联合植筋带加固黏土边坡的水力特性开展数值计算,并结合裸土边坡和植被边坡进行对比分析。结果表明:降雨时植筋带很好地发挥了将雨水传送至深层坡土、干燥时将深处的水分运送至浅层坡土的作用。经历10 d降雨后,裸土边坡、植被边坡、植被联合植筋带加固的边坡(植被加固层20 cm厚、植筋带50 cm长)的降雨影响深度分别为0.6,0.9,1.2 m;再经历14 d的干燥过程后,坡体表层土含水率的大小顺序为:植被联合植筋带加固的边坡>植被边坡>裸土边坡。另外,竖向植筋带的设计参数例如长度和间距会影响坡土的降雨影响深度和坡面的雨量分配,植筋带长度越大,降雨影响深度越大;植筋带间距越小,坡面径流越小。布置细而密的植筋带可以改善坡脚积水状况,并抑制坡土表层裂隙开展,减小降雨滑坡风险。

The tensile strength of the vertical geotextile belts(the extended roots)can play a longer mechanical reinforcement than the plant roots,but it will also have an impact on the depth of rainfall,further change the hydrological response of slopes.The hydraulic characteristics of clay slopes reinforced by vegetation and vertical geotextile belts are calculated,and the comparison between bare clay slope and vegetated slope is made.The results show that the vertical geotextile belts play a good role in transferring rainwater to deep slope soils during rainfall and moisture from deep to shallow slope soils during drying.After 10 days of rainfall,the rainfall infiltration depths of the bare clay slope,the vegetated slope and the slope reinforced by vegetation and vertical geotextile belts(the vegetation reinforcement layer is 20 cm thick and the vertical geotextile belt is 50 cm long)are 0.6 m,0.9 m and 1.2 m,respectively.After drying process for 14 days,the moisture contents of soils in the surface layer of slopes are as follows:the slope reinforced by vegetation and vertical geotextile belts>the vegetated slope>the bare clay slope.In addition,the design parameters such as length and spacing of the vertical geotextile belts will affect the rainfall infiltration depth of slope soils and rainfall distribution on slope surface.The longer the vertical geotextile belts,the deeper the rainfall influence depth;the smaller the spacing of vertical geotextile belts,the smaller the slope runoff,and the less the water accumulation at the toe of slopes.Planting thin and dense vertical geotextile belts can improve the water accumulation at the toe of slopes,restrain the development of surface cracks,and reduce the risk of landslides under rainfall.