为明确热力加固改变土体物理、化学性质和结构特征,影响强度、水稳等工程性质的具体过程,本文采用无侧限抗压强度、X射线衍射、压汞和扫描电镜等试验,研究高温(100~900 ℃)对杨凌压实黄土无侧限抗压强度和水稳性质的影响规律和作用机理。结果表明:与经100 ℃处理后土样的无侧限抗压强度(UCS)相比,经900 ℃处理后土样的UCS提高了1.15~5.26 MPa;当处理温度不低于500 ℃时,土样具有较好的水稳性;当处理温度为500~900 ℃时,伊利石、蒙脱石、方解石和石英等矿物含量变化较大;经700~900 ℃处理后土样的微孔(0.01 μm<d<0.1 μm)、超微孔(d<0.01 μm)数量和孔隙分形维数明显降低;高温熔融促使土粒形成了一些致密结构;经高温作用,土粒发生移动和重排、形成新化合物,提高了土样的抗压强度和水稳性。研究成果可为热力加固法的应用提供数据和机理支持。
In order to specific process of changing the physical, chemical and structural characteristics of soil by thermal reinforcement, and then affecting the engineering properties such as strength and water stability was clarified. The influence laws and action mechanisms of high temperature from 100℃ to 900℃ on the unconfined compressive strength and water-stability of compacted Yangling loess were discussed by four tests that are unconfined compressive strength, X-ray diffraction, mercury intrusion porosimetry and scanning electron microscopy. The results show that the unconfined compressive strength of samples treated after 900 ℃ was 1.15~5.26 MPa higher than that after 100 ℃; The samples had great water-stability when treatment temperature was not less than 500 ℃; The mineral contents of illite, montmorillonite, calcite and quartz changed under 500~900 ℃; The quantity of micro-pores (0.01 μm<d<0.1 μm), super micro-pores (d<0.01 μm) and pore fractal dimension of samples obviously decreased under 700~900 ℃; There are some high-temperature melting phenomena that promote the formation of some "dense structures" in soil particles; The soil particles are subjected to movement and rearrangement and forms some new compounds under the action of high temperature, which improves the compressive strength and water stability of samples. The research results can provide data and mechanism support for the application of thermal reinforcement method.
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