不同颗粒粒径重塑与原状膨胀岩物理力学性质变化规律研究

THE VARIATIONS OF PHYSICAL AND MECHANICAL PROPERTIES OF REMODELING AND UNDISTURBED EXPANSIVE ROCKS OF DIFFERENT PARTICLE SIZES

以南宁盆地膨胀岩为研究对象,通过室内试验测定原状样与不同颗粒粒径重塑样的膨胀力、抗剪强度及热特性,研究其性质差异。结果表明:重塑后不同粒径范围膨胀岩土样的无荷膨胀率较原状样明显升高,而主应力差峰值、抗剪强度和热物理指标较原状样均有降低。因此,应选择合适粒径范围的土颗粒重塑代替原状样进行室内试验:无荷膨胀率和膨胀力试验应选择粒径范围1 mmd<2 mm的土颗粒;三轴试验和热物理指标测试应尽量选择粒径较小的土颗粒。

For the expansive rock in the Nanning basin,its expansibility,shear strength and thermal characteristics are measured by using,respectively,the undisturbed samples and the remolded samples of different particle sizes in the laboratory test,and the differences of their values are studied.The results show that the free swelling ratio of the remolded expansive soil samples in different particle size ranges sees a signi?cant increase,as compared with undisturbed ones,but the peak value of the principle stress difference,the shear strength and the thermal characteristic index are decreased.Therefore,the soil particles of appropriate sizes should be selected for remolding instead of undisturbed samples in the laboratory test.The free swelling ratio and the expansive force of the remolded samples take similar values as with the undisturbed samples when the soil particle size is in the range of 1 mm d<2 mm,and the properties of samples in the minimum range of the soil particle size are close to those of the undisturbed samples,as shown in the triaxial test and the thermophysical experiment.