改性钠羧甲基纤维素胶结固化土质边坡机制与抗冲蚀特性研究

Research on glue reinforcement mechanism and scouring resistant properties of soil slopes by modified carboxymethyl cellulose

改性钠羧甲基纤维素（简称改性CMC）溶液在岩土体表面具有较强的渗析胶结与吸附胶结作用,按一定浓度就地拌合原状土,形成12~15 cm固化层可对土质斜坡起到加固、防渗与抗冲蚀作用。取寒区公路边坡粉砂土,利用不同浓度改性CMC进行拌合加固,对干燥后的试样进行水稳（遇水崩解）,抗剪强度与渗透系数测试,并进行冻融循环条件下加固体强度与变形影响因素研究。结果显示,随改性CMC浓度增加,加固土水稳性增强,抗剪强度增大,渗透系数降低,至1.1%加量的改性CMC加固土,其崩解程度为0,黏聚力提高1.2倍,内摩擦角提高0.8倍,渗透系数从2.17×10-4 cm/s减小到1.0×10-5 cm/s,冻融强度损失小于25%。设计降雨冲刷试验研究改性CMC加固土抗冲蚀性能,结果表明：按120 mm/min雨强冲刷8.7 min,未加固土边坡即形成沟蚀,沟槽最大宽度13 cm,深9.0 cm,侵蚀面积占整个坡面30%,平均产沙速率达0.23 kg/min,而1.1%改性CMC加固土边坡冲刷60 min,无沟蚀产生,产砂量近于0,且坡面植被完好;改性材料已在多处现场应用,效果良好。

Modified carboxymethyl cellulose sodium exhibits the strong dialysis cementation and adsorption behavior on the surface of soils and rocks. When the slope surface is covered with a layer of soil mixed with the modified CMC of an appropriate concentration,a protective soil layer against the erosion with the thickness of 12–15 cm is created. Silty sand samples taken from the surface of excavation slopes alongside a highway were mixed with the modified CMC of different concentrations. The shear strength tests,the disintegration tests,the permeability tests and the tests under freezing-thawing cycles were carried out to obtain the basic physical and mechanical characteristics of the mixture. The test results show that,with the increase of the concentration of themodified CMC,the hydraulic stability and shear resistance increase and the permeability decreases. When the soil is mixed with 1.1% of the modified CMC,the disintegration phenomenon disappears,and the cohesion and the friction angle are respectively,1,2 and 0.8 times greater than the samples without the modified CMC. The permeability coefficient changes from 2.17×10-4 cm/s to 1.0×10-5 cm/s,and the loss of the strength due to the freezing-thawing is less than 25%. The erosion gully of 13 cm wide and 9.0 cm deep appears on the slope without the modified CMC and the erosion area occupies 30% of the surface area. For the slope with the modified CMC,no erosion phenomenon appears after one hour of rainfall. The modified CMC has already been applied to serval construction site successfully.