复合改性水玻璃固化黄土冻融特性试验研究

Study on the Peculiarity of Loess Solidified by Modified Sodium Silicate under Freeze-thaw Cycles

在我国季节温差变化较大的西北地区广泛分布着大量的黄土地层,强烈的冻融作用引起土体结构发生破坏,导致路基和边坡失稳;因此探求在冻融环境下新型岩土加固方式具有重大意义。研究了冻融循环条件下复合改性不同波美度水玻璃固化黄土的无侧限抗压强度、质量损失和微观结构等力学特性的变化。探讨了冻融循环对复合改性水玻璃固化黄土工程特性的影响。试验结果表明:复合改性水玻璃与未改性水玻璃固化黄土样的质量损失、强度损失与冻融循环次数存在一定相对值。冻融循环初期,冻融作用对复合改性水玻璃固化样强度有一定的补强作用;随着冻融循环次数的增多,强度随之减小;多次冻融循环后,试样微结构中部分骨架颗粒或晶体出现断裂,微结构出现损伤或破坏,固化样强度降低,甚至丧失。

There is great seasonal temperature difference in the northwest with numerous loess strata in our country. The intense freeze-thaw action cause the damage of soil structure, resulting in the instability of embank- ment and slope, thus it is so great significant to explore new type of rock and soil reinforcement method in freeze- thaw environment. The mechanical properties of loess, such as unconfined compressive strength, mass loss, micro- structure and so on is investigated, which are caused by different baume degree of compound modification sodium silicate on the condition of the freeze-thaw cycle. The freeze-thaw cycle effect on composite modified water glass cu- ring engineering properties of loess discussed. The experiments show that there is a critical value between composite modified sodium silicate and modified water glass curing loess in the loss of mass, strength, as well as the freeze- thaw cycles. The freeze-thaw action has a positive effect on strength of compound modification sodium silicate solidi- fied loess in early cycles and intensity decreases increased with the freeze-thaw cycles, framework grain or crystal of microstructure ruptured and microstructures damaged or breaked after repeated freeze-thaw cycles, the strength of solidified loess decrease, and even lost.