论文部分内容阅读
黄土中存在大量碳酸钙胶结物,该胶结物对黄土力学性状的影响很大。采用浓度为0.1,1和2 mol/L的盐酸溶液,开展了原状黄土试样的浸泡试验,测定了不同时间浸泡溶液中钙离子的浓度,开展了经不同时间浸泡土样的颗粒分析试验、固结试验及剪切试验,分析了酸性溶液浸泡下原状黄土力学特性及其变化规律。试验表明:黄土中胶结物主要是以粒径小于0.01 mm的颗粒存在,在酸性溶液浸泡作用下,土中钙质胶结物逐渐被溶蚀,试样中细小颗粒逐渐减少,尤其是颗粒直径小于0.005 mm的含量明显减少,浸泡液酸性越强,土体中钙质胶结物溶蚀的速度越快并且溶蚀得越充分。胶结物在土体中的作用主要是连接骨架颗粒,因此,胶结物对土体的黏聚力影响较大,而土体内摩擦角受胶结物溶蚀的影响不明显。经盐酸溶液浸泡后,试样的黏聚力随浸泡时间延长持续降低,浸泡60 d后,土体的黏聚力逐步趋于稳定。经0.1,1,2 mol/L盐酸溶液浸泡120 d后,试样的黏聚力分别降低约47%,63%,87%,且呈现出浸泡液酸性越强,黏聚力减少越多的情形。胶结物的溶蚀引起土体孔隙增加,压缩系数增大。随着胶结物的减少,土体的快剪应力–应变关系逐渐由应变硬化型向应变软化型转变。
Loess there is a lot of calcium carbonate cement, the cement on the mechanical properties of loess. The soaking test of undisturbed loess samples was carried out with hydrochloric acid solutions of 0.1, 1 and 2 mol / L concentrations. The concentration of calcium ions in the immersing solution was measured at different times, and the particle analysis test of soaking soil samples was carried out. Consolidation test and shear test, the mechanical properties of undisturbed loess under acidic solution immersion and its variation were analyzed. The results show that the cement in loess is mainly in the form of particles with the diameter of less than 0.01 mm. Under the action of acid solution, the calcareous cement in the soil gradually dissolves, and the fine particles in the sample gradually decrease, especially when the particle diameter is less than 0.005 mm significantly reduced the content, the stronger the acidity of the soaking liquid, the faster the dissolution of calcareous cement in the soil and the better dissolution. The role of cements in the soil is mainly to connect the skeleton particles, therefore, the cementation has a greater impact on the cohesion of the soil, while the friction angle within the soil is not obvious affected by the cementation dissolution. After immersed in hydrochloric acid solution, the cohesive strength of the sample continued to decrease with immersion time. After soaking for 60 days, the cohesion of the soil gradually stabilized. After soaking in 0.1, 1, 2 mol / L hydrochloric acid solution for 120 d, the cohesion of the samples decreased by 47%, 63% and 87% respectively, and the stronger the acidity and the more the cohesion decreased situation. The corrosion of cements causes the soil pores to increase and the compression coefficient to increase. With the reduction of cements, the fast shear stress-strain relationship of soil gradually changes from strain hardening to strain softening.