位于三峡库区巫峡段消落带的塔柱状危岩,其底部多损伤因素的耦合作用下常呈压裂诱发座溃整体失稳模式,危岩底部耦合损伤至突变机制是研究该类库岸危岩体失稳预警的关键科学问题.以三峡库区库岸巫峡段箭穿洞塔柱状危岩体为例,将危岩体简化为中上部非劣化区和下部劣化区的二元地质力学模型,基于应变等价原理获得其危岩体下部劣化区的荷载效应、溶蚀效应、干湿循环弱化效应的耦合损伤本构模型和总损伤度演化方程,根据地质力学模型概化为等效弹簧模型转化为力-位移的耦合损伤本构方程;基于能量平衡原理和突变理论建立了塔柱状危岩的耦合损伤-折叠突变模型,获取了其失稳判据和临界位移的表达式.通过案例分析结果表明:该危岩体突变失稳时的系统控制变量为-0.007 3,预测模型计算理论的突变起点垂向位移为 42.2 mm,终止点位移为 60.5 mm,当监测数据危岩体最大垂向累积位移为 26.2 mm 时,小于突变起始位移时就采用及时治理措施,与危岩未失稳的状态吻合.其研究成果可为三峡库区灰岩地区库岸塔柱状压溃型危岩的监测预警与防治提供重要的理论支撑.
Prediction of Fracture Coupling Damage and Abrupt Instability of Reservoir Bank Tower Pillar Unstable Rock
The fracture-collapse instability model of the Tower-column unstable rock mass associated with bottom compression induced fracture frequently occurs on bank of Wuxia section in the Three Gorges Reservoir area.The key issue for the instability early warning of that of instability model is related to damage-catastrophe mechanism.Taking Wuxia Jian Chuan-dong Tower-column unstable rock mass as an example,the geological model of tower-column unstable rock mass was divided into two zones,i.e.,the non-degraded area on upper-middle zone and the lower degraded area of the bottom zone.The damage-constitutive geomechanical model of the lower degraded area was established based on the coupling action of the load,corrosion and dry-wet weakening effect.A damage constitutive equation and a total damage degree evolution were derived based on the strain equivalence principle.Then,the geomechanical model was simplified into an equivalent spring model and the damage-fold catastrophe model was established by the energy balance theory.Finally,the damage-folding sudden change model of tower-column unstable rock mass was established,and its instability criterion and critical displacement expression were obtained.The results of theoretical calculations show that when the unstable rock mass of Wuxia Jian Chuan-dong fails,the control variant determining the stability of a fold catastrophe model is-0.0073,demonstrating that the system turns into an unstable state.The vertical displacement of the mutation starting point and the displacement of the termination point of the unstable rock mass mutation prediction model are 42.2 mm and 60.5 mm respectively.While,the monitoring data in the vertical displacement of the degraded area is 26.2 mm.According to the deformation coordination equation,the monitored data is smaller than the initial displacement of the mutation,which is in consistent with the state of the unstable rock mass without instability.The research results have important theoretical support for the monitoring,early warning and prevention of the tower-shaped unstable rock mass in the limestone area of the Three Gorges reservoir area.
tower-column unstable rock mass on reservoir bankcollapse and instability typecoupling damagemutation model
万方数据
