岩石厚壁圆筒三向压缩下的卸荷试验与岩石强度破坏

Unloading experiment and rock strength failure of rock thick-walled cylinders under triaxial compression

为研究地下工程开挖影响,采用厚壁圆筒多轴应力试验,对试样施加较高的轴对称内、外壁压力及轴向荷载后,进行内、外壁卸荷破坏试验.试验的破坏结果是在厚壁圆筒壁间形成环向主要破裂面.这一破裂现象在以往相关文献中未见报道,与通常弹塑性理论分析的较高应力发生在圆筒内缘、破坏从内缘开始的结论不同.这一结果与深部矿山巷道围岩出现的分区破裂(zonal disintegration)现象类似.

In order to study the excavation effect in underground engineering,multiaxial tests were adopted on rock thick-walled cylinders.First,high axial pressure,confining pressure and inner pressure were applied on the cylinder samples.Then,inner and confining pressures were unloaded in time order.The experimental results show that a main ringlike failure surface forms in the thick wall of the cylinders.This kind of ringlike failure phenomenon,which is different from the result of failure initiated at the inner surface for the cylinders under high pressure based on general elastic-plastic analysis,has not been reported in published literatures so far.This experimental result is similar to intermittent zonal fracturing characteristics of deep underground roadways after excavation.