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鄂西志留系罗惹坪组砂岩结构面法向循环加卸载试验结果表明,在中低法向应力范围内,结构面加载变形曲线呈上凸型,卸载变形曲线呈上凹型,结构面卸载后产生残余变形,形成明显的回滞环。目前已提出的结构面法向变形本构方程都是在试验的基础上总结出的经验方程,因结构面的初始法向刚度和最大闭合变形量难以确定,使模型的计算精度受到一定的限制。因此,针对浅表工程岩体应力状态较低的特性,提出了结构面法向变形的半对数-圆弧线联合本构模型,加载曲线采用半对数模型表征,卸载曲线则采用圆弧线模型表征。其中,半对数函数的模型参数可根据加载试验结果回归分析得出,圆弧线模型方程则由本级加载曲线的起点、终点与卸载曲线的终点三点坐标确定。通过模型计算结果与试验结果对比分析表明,半对数-圆弧线模型计算结果与试验结果相吻合,较好地体现了结构面法向加载曲线为上凸型与卸载曲线为上凹型的特征,重现了卸载-加载过程的回滞圈。新的模型回避了最大闭合变形量和初始刚度的确定难题,并且不需引入新的模型参数,便于实际应用。
The results of normal cyclic loading and unloading tests of sand-rock structural plane of Silurian in Silurian of Silurian in Silurian of western Hubei show that in the middle and low normal stress range, the deformation curve of the structural plane is convex, the unloading deformation curve is concave, Residual deformation after the formation of significant hysteresis ring. At present, the constitutive equations of the normal deformation of the structural plane are all empirical equations which are concluded on the basis of the experiment. Because the initial normal stiffness and the maximum closing deformation of the structural plane are difficult to be determined, the calculation accuracy of the model is limited . Therefore, aiming at the low stress state of rock mass in superficial engineering, a semi-logarithm-arc combined constitutive model of normal deformation of structural plane is proposed. The loading curve is characterized by semi-logarithmic model, and the unloading curve is arc Line model characterization. Among them, the model parameters of the semi-logarithmic function can be obtained by regression analysis based on the loading test results. The circular arc model equation is determined by the three-point coordinates of the starting point, ending point and end point of the unloading curve. The comparison between the calculated results and the experimental results shows that the calculated results of the semi-logarithmic-circular arc model are in good agreement with the experimental results, which shows that the normal loading curve of the structural plane is convex and the unloading curve is concave. , Reproduced the unloaded - loading process of the hysteresis circle. The new model avoids the problem of determining the maximum closed deformation and the initial stiffness, and does not need to introduce new model parameters for practical application.