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为了研究冻融循环对改良粉土强度的影响规律及其作用机制,开展了不同初始压实度和初始含水率试样的冻融循环试验。对经历不同冻融循环次数作用后的试样进行无侧限抗压强度试验,探讨了冻融循环作用对改良粉土的长期强度的影响规律。试验结果表明,随着冻融循环次数增加,改良粉土的抗压强度下降,最终在6次冻融循环后趋于稳定;相同的冻融循环次数条件下,初始含水率越大,改良粉土的抗压强度衰减幅度越大。为了寻找冻融循环作用对改良粉土孔隙结构的影响规律,进而揭示冻融循环对试样结构损伤的机制,开展了改良粉土的细观孔隙结构试验。试验结果表明,不同的冻融循环次数和初始含水率对小孔径孔隙(10 nm)之间的结构影响不大;冻融循环作用主要损伤了大孔径孔隙(0.01~100μm)之间的结构,从而降低了改良粉土的强度。
In order to study the law of the effect of freeze-thaw cycles on the improved silt strength and its mechanism of action, the freeze-thaw cycles of different initial compaction degree and initial moisture content were carried out. The unconfined compressive strength tests were carried out on the specimens subjected to different freeze-thaw cycles, and the influence of the freeze-thaw cycles on the long-term strength of the modified silt was discussed. The experimental results show that the compressive strength of the modified silt decreased with the increase of the number of freeze-thaw cycles, and finally stabilized after 6 freeze-thaw cycles. Under the same freeze-thaw cycles, the initial moisture content was higher, Soil compressive strength attenuation greater. In order to find out the law of the effect of freeze-thaw cycles on the pore structure of modified silt, and to reveal the mechanism of freeze-thaw cycles on the structural damage of the sample, a mesostructured pore structure test was carried out to improve the silt. The experimental results show that the number of freeze-thaw cycles and the initial moisture content have little effect on the structure of small pore size pores (10 nm). The freeze-thaw cycle mainly damages the structure of large pore size pores (0.01-100 μm) Thus reducing the strength of the improved silt.