冻融荷载下节理岩体的复合损伤模型

Compositedamage model of jointed rock mass under freezing and thawing load

摘要:

针对工程实际中的冻融受荷岩体,以岩石初始损伤状态为参考状态,将冻融与荷载作用引起的损伤视为细观损伤,节理引起的损伤视为宏观损伤,根据Lemaitre应变等效性假设,推导建立考虑宏细观缺陷的节理岩体复合损伤模型.应用该模型分析贯通率和冻融次数分别对岩体力学性质劣化的影响,结果表明:在贯通率一定时,损伤演化曲线随冻融次数的增加而增加,试验与理论峰值强度（或弹性模量）曲线随冻融循环次数增加而降低；在冻融次数一定时,损伤演化曲线与贯通率呈正相关关系,试验与理论峰值强度（或弹性模量）与贯通率呈负相关关系.说明贯通率与冻融次数对岩体的劣化产生一定影响,且饱和试验组受冻融效应较天然试验组力学性能劣化严重.将所建模型计算结果与试验值进行比较,理论曲线与试验曲线吻合良好,验证了所建模型的合理性与有效性.

Abstract:

For the frozen thawing rock mass in the engineering practice, taking the initial damage state of rock as the baseline state, the damage caused by freezing thawing and loading is considered as meso damage, and the damage caused by joints is regarded as macroscopic damage. According to the hypothesis of Lemaitre strain equivalence, a composite damage model of jointed rock mass considering macro and micro defects was derived. The effect of the penetration rate and the number of freezing and thawing on the deterioration of mechanical properties of rock mass was analyzed by this model. The results show that when the penetration rate was constant, the damage evolution curve increased with the increase of freeze-thaw times, and the experimental and theoretical peak strength (or modulus of elasticity) curves decreased with the increase of freeze-thaw times. When the freeze-thaw times were constant, the damage evolution curve was positively correlated with the penetration rate, and the experimental and theoretical peak strength (or modulus of elasticity) were negatively correlated with the penetration rate. It indicates that the penetration rate and the freezing thawing times have a certain effect on the deterioration of the rock mass, and the freezing thawing effect of the saturated test group is worse than the natural test group. The calculated results of the model were compared with the experimental values, and the theoretical curves are in good agreement with the experimental curves, which verified the rationality and validity of the model.