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围岩的流变特性是影响地下洞室变形及长期稳定的重要因素。在长期荷载作用下岩体会发生流变现象,特别软弱夹层在较高应力作用下其流变特性更为显著。以某水电站大型地下洞室为例,针对该地下洞室附近围岩存在着软弱夹层,且有些软弱夹层与开挖的洞室相互交汇,基于大型岩土工程分析软件FLAC3D,采用黏弹塑性流变本构模型(Cvisc),模拟了地下洞室围岩的流变力学行为;根据主厂房顶拱位移变化率规律确定出了开挖洞室2次支护的时间,对比分析了瞬时弹塑性条件下与考虑流变特性条件下洞室开挖后围岩的位移变形、应力场及塑性区的分布。数值模拟结果表明,由于着软弱夹层的影响,洞室围岩发生较大的变形,特别是在开挖洞室与软弱夹层的交汇处围岩随着时间的长期变形量会更大,这对洞室的稳定性有着一定的影响;对于水电站地下洞室的长期稳定性分析,充分考虑岩体流变效应是非常重要和必要的。
The rheological properties of surrounding rock are important factors that affect the deformation and long-term stability of underground caverns. Under the action of long-term load, the rheology of rock mass occurs. The rheological properties of especially weak interbed under higher stress are more obvious. Taking a large underground cavern of a hydropower station as an example, aiming at the existence of weak intercalations in the surrounding rock of the underground caverns, and some weak intercalations and caverns intersected with each other, based on the large-scale geotechnical analysis software FLAC3D, (Cvisc) was used to simulate the rheological behavior of surrounding rock in underground caverns. According to the rule of rate of change of roof arch displacement in main workshop, the time of secondary support was determined. The transient elasto-plasticity Displacement, stress field and plastic zone distribution of surrounding rock after cavern excavation considering rheological behavior. Numerical simulation results show that due to the influence of weak intercalations, the surrounding rock of the cavern is greatly deformed, especially the long-term deformation of the surrounding rock along the time when the caverns and weak intercalations intersect, The stability of the cavern has a certain impact. For the long-term stability analysis of the underground cavern of the hydropower station, it is very important and necessary to fully consider the rheological effect of the rock mass.