干湿循环下花岗岩残积土的崩解试验与微观机理研究

Test and Micro-mechanism of Disintegration of Granite Residual Soil under Dry-Wet Cycles

针对花岗岩残积土遇水易软化、崩解的特性,通过干湿循环下花岗岩残积土的崩解试验,研究了花岗岩残积土的压实度和干湿循环次数对其崩解特性和崩解参数指标的影响。得到以下结论:花岗岩残积土的压实度越小、经历的干湿循环次数越多,崩解速率越快,试样完全崩解所需的时间越短;拟合了平均崩解速率与干湿循环次数、压实度之间的函数关系式。利用电镜扫描试验,分析干湿循环作用下花岗岩残积土的微观结构变化,解释了崩解机理:随着干湿循环次数增加,片状颗粒间的层叠结构遭到破坏,颗粒的团聚性减弱,平面孔隙率增大,结构趋向疏松,加速了花岗岩残积土的崩解。

Granite residual soil is prone to soften and disintegrate in contact with water.The effects of compactness and number of dry-wet cycles on the disintegration characteristics and disintegration indexes of granite residual soil were examined via disintegration test under dry-wet cycles.Results demonstrated that the smaller degree of compaction and the more times of dry-wet cycles, the faster the disintegration and the shorter the time required for the sample to completely disintegrate.The functional relations of average disintegration rate against number of dry-wet cycles and degree of compaction were fitted.The microstructure change of granite residual soil under dry-wet cycle was obtained by scanning electron microscope test.The micro-mechanism of disintegration was explained: with the number of dry-wet cycles increased, the lamellar structure of flake particles was destroyed, the agglomeration of particles was weakened, the plane porosity increased, and the structure tended to loose, which accelerated the disintegration of granite residual soil.