不同卸荷路径下节理岩体的松动机理研究

Study on the Mechanism of Jointed Rock Masses′ Loosing in Different Unloading Ways

利用应力波理论研究了节理岩体在不同卸荷路径下高速卸荷后的运动规律,分别从理论和数值上进行了分析.结果表明,应用动力学的方法求解高速卸荷是适宜的,高速率的卸荷会使岩体产生整体的刚体位移,导致节理面张开,同时使岩体产生振动速度,这些都会造成岩体松动,延时卸荷对岩体的松动作用要低于瞬时卸荷对岩体的影响,相同的卸荷时间下岩体的松动效应受卸荷路径的影响.因此,在工程实践中,可以通过延长卸荷时间、减少一次卸荷量和控制卸荷速率的变化路径等措施来减小卸荷对保留岩体的松动损伤作用.

The rules of behaviors are studied for jointed rock masses subjected to quickly unload in different ways with the theory of stress wave ,and it is analyzed from theoretic results and numerical results. The results show that reasonable results can be obtained by dynamics;quickly unloading leads to a rigid body displacement which will induce the opening of the jointed rock faces, and give velocity to the jointed rock mass, this will make the rock mass loosen. It is also found that the loosing effect of rock mass induced by delayed unloading is less than by sudden unloading, and is different in different unloading ways with the same unloading time. So, in many projects, some actions can be taken to reduce the influence of delayed unloading to remain rock mass, for example, by extending unloading time, decreasing unloading amount in one time and controlling unloading velocities.