盐-冻耦合作用下水泥基风积沙改性土基坑填料的性能研究

Performance of Foundation Pit Filler with Cement-Based Drift-Sand Modified Soil under Salt-Freeze Coupling Effects

为了研究风积沙改性土基坑填料力学性质和结构受盐-冻作用的影响规律,观测不同循环次数下样品的腐蚀程度并进行化学成分分析,开展无侧限压缩试验,评价其力学性能的衰变规律。最后利用压汞试验对风积沙改性土的孔隙分布进行测量。结果表明:在盐-冻耦合作用下,由于化学反应导致水泥凝胶体减少,改性土的腐蚀程度逐渐增加;无侧限抗压强度、弹性模量随盐-冻次数增加而呈衰减趋势,且速率先快后慢;无侧限抗压强度与孔隙体积呈负线性关系,水泥基风积沙改性土微结构中的孔隙变化是宏观性能衰变的内在原因。

In order to study the influence of salt-freeze coupling on the mechanics and structural properties of cement-based drift-sand modified soil,the corrosion degree of the soil in different cycle numbers was observed and the chemical composition was analyzed.Unconfined compression tests were carried out to evaluate the decay law of mechanical properties.Finally,the pore distributions of drift-sand modified soil were measured by mercury injection tests.The results show that the degree of corrosion of soil-cement increases gradually due to the decrease of cement gel caused by chemical reaction under the action of salt-freeze coupling.The unconfined compressive strength(UCS)and elastic modulus(E)decrease with the increase of salt-freeze times(N).Unconfined compressive strength and porosity have a good negative linear relationship,indicating that the mechanical properties of drift-sand modified soil are closely related to pore changes.The change of porosity in microstructure of cement-based drift-sand modified soil is the intrinsic cause of macroscopic decay.