橡胶粉改良非饱和黏土体直剪试验研究

Study of Direct Shear Test on Unstaurated Clay Mixed with Rubber Powder

橡胶粉用于非饱和黏土体的改性,有望提高土体的强度。然而目前国内外对该课题的研究甚少,且其相关成果不足以支撑工程实践。为研究橡胶粉掺量对非饱和黏土体强度的影响,通过理论分析与试验研究相结合的方法,对0%、2%、4%、6%、8%、10%、15%、20%八组不同橡胶粉掺比下的固结黏土进行了一系列控制基质吸力的直剪试验。分析了有效黏聚力、有效内摩擦角、吸应力等抗剪强度参数的变化规律,并探究了最佳橡胶粉配比。试验结果表明:向非饱和黏土体中掺加2%或4%的橡胶粉可以有效改善土体抗剪强度;基质吸力恒定时,抗剪强度越大,吸应力对其影响越小。试验可为岩土工程加固、无支护挖方安全设计等领域的工程实践提供理论基础。

Rubber powder can be used as a kind of modified material to enhance the strength of unsaturated clay soils. At present,there are few studies on this issue at home and abroad. Meanwhile,related research results are insufficient to support engineering practices. In order to study the influence of rubber powder contents on strength of unsaturated clay,clay mixtures containing respective 0% 、2% 、4% 、6% 、8% 、10% 、15% 、20% rubber powder were prepared. Series of suction-controlled direct shear tests were conducted on eight groups of consolidated rubber powder-clay mixtures,then analyzed shear strength parameters such as effective cohesion intercept,effective angle of internal friction and suction stress,researched optimum contents of rubber powder of mixtures,combining coalescing theory analysis with experiment study. The results show that shear strength of unsaturated clay increases obviously when rubber powder contents are 2% and 4%; The greater of shear strength the smaller effect of suction stress under constant matric suction. The test results can provide theoretical basis for engineering practices such as geotechnical reinforcement and safety design in excavation without support,etc.