基于Burgers模型的岩层弯曲变形分析

Analysis on Bending Deformation of Strata Based on Burgers Model

由于岩石材料抗拉与抗压性能的明显差异,使岩层受蠕变作用时,其弯曲中性层位置及变形曲率都将随时间变化.基于Burgers流变本构模型,对岩层的中性层位置和相对蠕变函数随时间的变化特征进行了系统研究.研究结果表明:岩层弯曲中性层和曲率的初始状态决定于岩石材料的弹性参数,而最终状态决定于它的黏性参数;蠕变前期,岩层弹性、黏性参数对中性层位置和变形曲率都有较大影响,但随着时间增加这种影响迅速减弱;若岩石的抗拉、抗压、黏性性质相同,则中性层最终趋于几何中面,否则趋于某一确定位置;由于蠕变的作用,岩层曲率随时间不断增大,直至岩层发生破断;对于稳定蠕变情况,岩层弯曲中性层要偏离初始状态,但经过一定时间后又将回到初始状态,而岩层的变形曲率则随时间单调增加,但最终趋于某一定值.

Due to the distinct difference in tensile and compressive properties, the position and deformation curvature of curved neutral layer will change with time for the strata in a creep state. The variation characteristics of the position of curved neutral layer and the relative creep function with time are studied systemically based on the rheological constitutive Burgers model. The study results indicate that the initial state of the bending neutral layer and curvature of strata is dependent on the elasticity parameters while the final state is dependent on the viscosity parameters. During the earlier time of creep function, the elasticity and viscosity parameters have a great effect on the position and deformation curvature of curved neutral layer. However, this effect gets weaker quickly with the time passing. If the tensile strength, compressive strength and viscosity have the same property, the neutral layer tends to the geometrical middle plane. Otherwise, it tends to a certain position. The curvature of the strata increases continuously with time passing till the breaking takes place at last because of the creep. For the steady creep, the bending neutral layer would deviate from the initial state during the early time, but it will tend to be the initial state after a period of time. However, the curvature of strata ap- pears a monotone increase with time and reaches a constant finally.