不同含水率下石灰改良红层泥岩土的力学特性试验研究

为掌握不同含水率下石灰改良黔张常高铁地区红层泥岩的力学特性,对红层泥岩及其石灰改良土进行了击实试验,随后考虑最优含水率和饱和含水率进行了无侧限抗压,CBR,直剪等力学试验,结果表明:随石灰掺量增加,改良红层泥岩的最优含水率逐渐增大,而最大干密度则逐渐减小.石灰对红层泥岩土的强度和承载力有显著改善,但改善效果与红层泥岩土自身的含水率有关.饱和状态下,石灰掺量增加,对CBR值和黏聚力改善的效果越好,但对无侧限抗压强度和内摩擦角改善效果的增幅不如前者明显;最优含水率下,石灰掺量越高,无侧限抗压强度、黏聚力和CBR值逐渐增加,但对内摩擦角的改善效果并不明显,且当石灰掺量超过6％时,其内摩擦角略有减小.最终推荐利用石灰改良黔张常地区红层泥岩时最优掺比为6％.

Experimental Study on Mechanical Properties of Lime Modified Red Mudstone Soil with Different Moisture Content

In order to be specialized in the mechanical properties of lime-modified red-bed mudstone under different water content in Qianzhang-Changzhou high-speed rail area, compaction tests were carried out on red-bed mudstone and its lime- modified soil, and the mechanical tests of unconfined compression, CBR, direct shear and others were carried out afterwards considering both of the optimal water content and saturated water content. The test result shows that the optimal water content of the modified red mudstone gradually increases while the maximum dry density gradually decreases with the increase of lime content. Lime can significantly improve the strength and bearing capacity of the red mudstone. However, the improvement effect is related to the water content of the red mudstone itself. In the saturated state, the increase of lime content will improve the CBR value and cohesive force, while the improvement effect of unconfined compressive strength and internal friction angle is not as obvious as the former. On the of condition of optimal moisture content, the unconfined compressive strength, cohesion and CBR value gradually get high when the amount of lime blending increases, but the improvement effect on the internal friction angle is not obvious. In addition, the internal friction angle decreases slightly when the lime content exceeds 6%. So it is recommended to use lime to improve the red mudstone in Qianzhangchang area with an optimal mixing ratio of 6%.