不均质体对水泥土强度特性的影响规律试验研究

An Experimental Study on the Effect of Inclusions on Cement-Soil Admixtures

为了评价不均质体对水泥土材料力学性能的影响,室内在搅拌均匀的水泥土中填入球形的软黏土块作为不均质体,养护28 d后进行无侧限抗压强度试验,分析不均质体的体积百分比和尺寸等对强度特性的影响规律.试验结果表明,不均质体的存在会使水泥土试样的无侧限抗压强度和变形模量显著降低,1%的不均质体会导致7%的强度折减,8%的不均质体可使水泥土试样的强度折减率达65.6%.不均质体的总体积百分比一定时,水泥土试样的强度随着不均质体尺寸的减小而增大.均质的或不均质体较小的水泥土材料,其破坏模式为整体张裂破坏或整体剪切破坏;不均质体较大的水泥土材料,其破坏模式表现为局部破碎.水泥土搅拌桩的实际设计应考虑水泥土材料的非均质性.

To assess effects of heterogeneity on performance of soil-cement admixture, globate soft clay blocks were put to evenly stirred cement soils, functioning as heterogeneity. It was maintained for 28 days and then tested for unconfined compressive strength in an effort to study the impacts of its volume percentage and size on the strength performance. The test results show that there was a significant increase in unconfined compressive strength and deformation modulus of the samples because of heterogeneity. More specifically, unconfined compressive strength was reduced by 7 % due to 1 % of heterogeneity, and the strength of cement-soil samples was reduced by 65. 6 % by 1 % of heterogeneity. That is to say, the strength of such samples increases with the decreases in the size of heterogeneity provided that the volume of heterogeneity is fixed. Failures such as complete rifting damage or complete shear damage occur in homogeneous cement soil materials or inhomogeneous cement soil materials of small size, while local fragmentations often occur to large-size inhomogeneous cement soil materials. Therefore, the design of cement-soil piles should take account of the inhomogeneous features of cement soils.