稻秸秆泥皮护坡材料对路基水分迁移影响的初步研究

为研究晴雨天气下,稻秸秆泥皮护坡材料对路基水分迁移的影响,在测定该材料渗透系数和干湿循环抗渗性能基础上,进行室内路堤边坡模拟试验,分别在连续的自然照射和坡面冲刷条件下,测定路基内部含水量变化,以此分析稻秸秆泥皮护坡材料在极端干旱和连续降雨条件下,对路基内部水分迁移特征的影响.结果表明:稻秸秆泥皮材料渗透系数较小,干湿循环不会导致其抗渗性能明显降低;该材料能有效避免坡面泥皮结构失水干裂,减少干旱天气下,路基内部水分向外过度蒸发迁移,保证路基含水量稳定,坡面植被发育后,保水防裂作用更加明显;该材料具备较强的水分隔阻能力,有效减少强降雨期间的坡面雨水人渗及水分进一步向路基内部扩散迁移,同时有效促进植被生长,泥皮+稻秸秆+草根复合泥皮结构,能进一步提高坡面抗雨水冲蚀性能,形成可靠的边坡生态防护系统.该研究对公路路基设计与施工具有重要的指导意义.

Effects of mud with rice straw as slope protection material on the water migrationin highway subgrade

Background] In the southern China moist region,rainwater infiltration of slope surface and water migration in subgrade are the main factors for its bearing capacity degradation.Lacking protection will lead to cracking or excessive erosion on slope surface.In order to reduce water content changing in subgrade in sunny or rainy weather,a new material consisting of clay and rice straw is developed,and its application for slope protection is probed in this paper.Methods] Firstly,the mud with rice straw was prepared by mixing the shredded clay with water and rice straw in 5-10 cm.And then the permeability coefficient and anti-Penetrability performance of compacted clay,pure mud,mud with rice straw and vegetation was determined by variable head permeability test and impermeability test.Afterwards,an indoor-test simulating embankment slope in continuous natural radiation and continuous slope scouring was executed to probe soil moisture inside subgrade in condition 1:bare slope,condition 2:slope under the protection of pure mud,condition 3:slope under the protection of mud with rice straw,condition 4:condition 2 + grass seeds,and condition 5:condition 3 + grass seeds.Through the sampling test of the water content distribution in subgrade center of 60 cm horizontal depth under above conditions,the water migration characteristics of the subgrade under extreme weather conditions were studied.Result] The permeability coefficient of the material of mud with rice straw was 0.81 × 10-5 cm/s.The permeation time of mud with rice straw and vegetation samples was 21 h in the 4th and 5th dry-wet cycle penetration tests.In the dry weather condition,the moisture content of the mud decreased to 13.6％ after 50 days in condition 3,and the moisture content was 17.2％-21.4% after 50 days in condition 5 in which the water content of the soil was stable.In the heavy rainfall scouring test,the water content of the condition 3 and condition 4 was only slightly increased at the 6th hour,while the water content of the soil in the horizontal depth of 20 cm was slightly increased in condition 5.Conclusions] Mud with rice straw presents small permeability coefficient and optimal permeability.The mud cracks was reduced in dry weather and soil moisture was effectively maintained,what was beneficial to the plant growth.The mud with rice straw can improve the moisture migration performance in slope surface under heavy rainfall erosion,and keep the stability of the internal moisture content in subgrade.After the vegetation root growth and development,it can form a green ecological environmental protection system,thus,it has a great significance to highway ecological construction.