基于新型防渗护壁材料的膨胀土边坡抗入渗及抗冲刷特性

Anti-infiltration and anti-scour characteristics of expansive soil slopes based on rubber polymer waterproof coating

为有效防护膨胀土边坡在降雨−蒸发循环作用下的失稳破坏,采用新型防渗护壁材料防护膨胀土边坡,但其抗入渗、抗冲刷性能及工作机理尚不清晰。为此,制作未防护、防渗护壁材料防护和三维植被网+防渗护壁材料防护3组膨胀土边坡模型,研究降雨−蒸发循环作用下边坡体积含水率、孔隙水压力、径流量、土体冲刷量、坡面冲蚀过程以及裂隙的变化规律,揭示新型防渗护壁材料防护膨胀土边坡的作用机理。研究结果表明:降雨入渗引起的含水率和孔隙水压力变化均具有一定的滞后性;防渗护壁材料防护边坡在同一深度的含水率对降雨入渗的响应时间最长,而素土边坡的最短;边坡的抗入渗能力由大到小顺序为防渗护壁材料防护边坡、三维植被网+防渗护壁材料防护边坡和素土边坡;各循环中孔隙水压力峰值差总体上防渗护壁材料防护边坡最大,素土边坡最小;防渗护壁材料防护边坡的径流量最大,3组边坡径流量均随循环次数增加呈“S”形变化;膨胀土边坡坡面在降雨−蒸发循环作用下发生渐进性侵蚀破坏,土体冲刷量与降雨−蒸发循环次数呈二次函数关系;防渗护壁材料防护边坡的抗冲刷系数最大,抗冲刷性能最显著。总体而言,防渗护壁材料防护层可有效防止雨水入渗及边坡水分蒸发,并能有效降低雨水和径流作用对坡面的侵蚀破坏,有利于增强边坡长期稳定性。

In order to effectively protect the expansive soil slopes from instability and damage in the precipitationevaporation cycles,the rubber polymer waterproof coating was used to protect the slope.However,its antiinfiltration,anti-scour performance and working mechanism are still unclear.For this reason,three groups of slopes were made in this experiment,including plain soil slope,the slope protected by rubber polymer waterproof coating and the slope protected by 3D vegetation net+rubber polymer waterproof coating.The variation law of the volumetric water content,pore water pressure,slope runoff,soil scour,slope erosion process and cracks under the action of precipitation-evaporation cycles were studied.Then,the mechanism of the rubber polymer waterproof coating protecting the expansive soil slope was revealed.The results show that the changes of water content and pore water pressure caused by rainfall infiltration are hysteretic.At the same depth,the water content of the slope protected by rubber polymer waterproof coating has the longest response time to rainfall infiltration,while the plain soil slope is the shortest.The anti-infiltration ability from big to small is the slope protected by rubber polymer waterproof coating,slope protected by 3D vegetation net+rubber polymer waterproof coating,and plain soil slope.During each cycle,the peak difference of pore water pressure is generally the largest for the slope protected by rubber polymer waterproof coating and the smallest for the plain soil slope.Compared with the other two sets of slopes,the runoff of the slope protected by rubber polymer waterproof coating is the largest,and the runoff of the three groups of slopes all shows S-shaped change with the increase of the number of cycles.Expansive soil slope will undergo gradual erosion damage under the action of precipitation-evaporation cycles.The soil erosion amount is a quadratic function with the change of precipitation-evaporation cycles.In the same cycle,the slope protected by rubber polymer waterproof coating has the largest anti-scour coefficient and the most remarkable anti-scour performance.In general,the protective layer of rubber polymer waterproof coating can effectively reduce the infiltration of rainwater and evaporation of slope water,and can effectively reduce the erosion and damage of slope caused by rainwater and runoff,which is conducive to increasing the long-term stability of slope.