冻融循环影响下水泥、煤矸石改良粉土的力学特性研究

Mechanical Properties of Cement and Gangue Improved Silt under the Influence of Freeze-Thaw Cycles

为研究水泥、煤矸石改良粉土路基在冻融循环作用下的力学性质,以高速公路粉土填料为研究对象,制作了含5%水泥和20%煤矸石的改良粉土试件,对其进行了负温度分别为-25℃、-30℃、-35℃的冻融循环试验,并以冻融次数和围压为变量对改良粉土进行三轴压缩研究。研究结果表明:增加围压和冻融次数、降低温度是改良粉土应力-应变曲线由应变软化型向应变硬化型转变的因素;冻融循环次数的增加,改良粉土极限强度、弹性模量、粘聚力及内摩擦角等指标的衰减规律为快速、缓慢、稳定三个阶段,趋于稳定的冻融循环次数为8次;温度的降低对改良粉土极限强度、弹性模量、粘聚力劣化影响较大,而对内摩擦角的劣化影响较小,力学指标劣化程度有收敛趋势。此研究可为粉土在路基工程中的应用和防治灾害提供一定的工程价值。

In order to study the mechanical properties of cement and gangue improved silt subgrade under the action of freezing and thawing, taking the silt packing of expressway as the research object, the improved silt samples containing 5% cement and 20% gangue were made, and the freezing and thawing of negative temperatures were-25 ℃,-30 ℃,-35 ℃. Cyclic test, and the triaxial compression study of the improved silt was carried out with the number of freeze-thaw cycles and confining pressure as variables. Research indicates that increasing the confining pressure, freezing and thawing times and lowering the temperature are the factors that change the stress-strain curve of the silt from strain softening to strain hardening. The number of freezing and thawing cycles increases, and the attenuation laws of the modified soil ultimate strength, elastic modulus, cohesion and internal friction angle are fast, slow, stable three stages, and the number of freeze-thaw cycles tends to be stable 8 times. The decrease of temperature has great influence on the ultimate strength, elastic modulus and cohesive force deterioration of improved soil, but has little effect on the deterioration of internal friction angle, and the degree of deterioration of mechanical index has a convergence trend. This research can provide certain engineering value for the application of silt in subgrade engineering and disaster prevention.