干湿循环下花岗岩残积土强度衰减试验研究

EXPERIMENTAL STUDY ON DETERIORATION OF GRANITIC RESIDUAL SOIL STRENGTH IN WETTING-DRYING CYCLES

季节性的干湿交替循环作用可使边坡岩土体强度劣化,影响边坡安全性及耐久性。通过室内干湿循环模拟试验,探讨了干湿循环作用下花岗岩残积土抗剪强度随含水率、干湿循环次数的变化规律。试验结果表明:干湿循环下花岗岩残积土黏聚力前期衰减趋势明显,后期衰减趋势减缓,并逐渐趋于稳定;而花岗岩残积土内摩擦角在干湿循环下未呈现明显的变化规律,大小变化不定。在此基础上,采用S型曲线函数对花岗岩残积土强度衰减曲线进行拟合,拟合结果说明S型曲线函数能够较好地体现花岗岩残积土黏聚力随循环次数的衰减规律。研究成果对进一步揭示干湿循环下闽东南地区花岗岩残积土强度劣化机理具有重要的参考价值。

The safety and durability of the soil slope can be threatened when the strength of soil is deteriorated due to wetting-drying cycles. Experimental studies are undertaken on an undisturbed residual soil from southeast of Fujian area. It aims to discuss the variation of shear strength with the change of water contain and the cyclic number under wetting-drying cycles. It is shown that the cohesion of granite residual soil decreases in different degrees with increasing number of cycles and finally reaches to a constant state. However,the friction angle of granite residual soil keeps a stable with little influence of the wetting-drying effects. On the basis of the relationship between the amount of strength attenuation and cyclic number,the S-shaped function is adopted for fitting. The results show that the S-shaped function can well describe the attenuation rules of cohesion with the change of cyclic number. The results also have an important reference value for further reveal the influence of wetting-drying cycles on deterioration mechanism of granitic residual soil and long-term stability of residual soil slope in southeast of Fujian.