基于蠕变试验的时滞型岩爆孕育机理研究

Study of Inoculation Mechanism of Delayed Rock Burst Based on Creep Test

岩爆按发生时间可以分为时滞型岩爆和即时型岩爆。其中,时滞型岩爆由于发生在围岩开挖完成后的数小时至数十小时,严重威胁到施工人员和施工设备的安全。本文通过单轴加载和三轴卸围压蠕变试验,结合声发射监测技术,研究了花岗岩在长期荷载作用下的蠕变特性,以及花岗岩在蠕变过程中的能量耗散规律和微裂隙扩散规律,并以此对时滞型岩爆的孕育机理进行了研究。研究结果表明,时滞型岩爆的孕育可以分为前期积累、开挖后应力调整、稳定发展和岩爆发生四个阶段。在围岩开挖过程中,由于施工扰动,围岩内部微裂隙扩展,有剥离现象产生。在开挖完成后,围压在短时间内产生应力重分布,变形和能量耗散有所激增,原始微裂隙扩展,并伴随少量新微裂隙的产生。之后,围岩进入稳定发展阶段,变形和能量耗散均维持在较低水平,微裂隙扩展缓慢,该阶段围岩在进行破坏前的能量积累,是进行岩爆预警的标志。在进入破坏阶段后,围岩在短时间内产生大量的能量耗散,微裂隙迅速扩展并最终贯通,围岩发生破坏,即产生时滞型岩爆。

Rock burst can be divided into delayed ruck burst and instant rock burst according to the time of happen,and the delayed rock burst may cause huge danger to people and equipment because it happens several hours to several decades after the excavation.We studied the creep properties,the law of energy dissipation and the law of micro-cracks diffusion in the process of creep of granite through uniaxial loading and triaxial unloading creep test with acoustic emission monitoring,and then studied the inoculation mechanism of delayed rock burst.The study shows that the inoculation mechanism of delayed rock burst can be divided into four stage:the former formulation stage,the stress redistribution stage,the steady develop stage and the happen stage.The inner micro-cracks begin to accompanied and the rock was peeled off in the process of excavation because of construction disturbance.After the excavation,the rock is subjected to stress redistribution in short time,and the deformation and energy dissipation are proliferated,the origin micro-cracks accompanied and a few new micro-cracks produced.Then,the rock enters the stage of stable development,the deformation and energy dissipation keep low,and the micro-cracks grow slow,and the rock accumulates energy before the destruction.This stage could be used as a key sign to warn the rock burst.In the stage of damage,rock gets huge energy dissipation in short time,and micro-cracks grow fast and eventually penetrate.The rock gets damage,and the delayed rock burst happens.