The Disturbance Effect Research On The Anchored Caverns Under The Dynamic Load Of Explosion

With the rapid development of economy, the development and utilization of underground space has become the development trend. The explosive stress wave that are generated by blasting excavation will damage the anchoring system and surrounding rock mass, which have the disturbance effect on the safety and stability of the cavern directly. It has become heat and difficult topic in rock mechanics research.In this dissertation, according to the similar model theory of Froude, the anchored cavern with integrated and jointed rock masses was produced and processed. According to the theory of stress wave propagation, the stress wave propagation and the energy of attenuation in jointed rock mass were researched by using fast Fourier transformation method. Dynamic analysis was carried on the anchor system of anchored cavern, the modern signal processing technology was used to analyze the dynamic response of caverns and anchored bolt cavern under the disturbing load. According to the theory of rock blasting shock and the rock’s damage theory, the failure characteristics and accumulation of damage of integrated and jointed caverns were studied under blasting load. Through the model test and theoretical analysis, the main results are shown as follows:(1) Adopt the method of fast Fourier transform in signal processing and analyzes the propagation law of stress wave in the joint rock mass and energy attenuation. When the stress wave propagates in jointed rock mass, it can occur several transmission and reflection effects. Due to the iris action of joints, there is energy attenuation continuously. The maximum of duration signals passing through the joint are not at in beginning of jumping time but a later time after the beginning; Spectral curve of test signals has a significant change when the stress wave began to pass or passed across the joint, the high-frequency components of the signals are absorbed gradually, maximum amplitudes of frequency and domain frequency decrease in nonlinear gradually.(2) Through the analysis of the time history curve of strain and acceleration for anchored cavern, the response of the anchor and cavity has been researched. Under the disturbance load, the peaks of strain in different parts of the anchor are near the middle of the anchor, followed are at the anchor tail, the end of the anchor are smallest. After the anchor being impacted by the explosion of stress wave, the peak of strain begin to appear, then the larger secondary peak of strain appear due to the reflected and transmitted wave of the chambers and model interface. After the vault being suffered by the direct impact, surrounding rock is compacted quickly, there is a small negative displacement. After the surrounding rock compaction process, there is a displacement downward of the entire dome, and increasing gradually.(3) According to the theory of blasting shock and damage of rock mass under blasting load, the damage accumulation and damage characteristics of complete and joint caverns have been studied. Under the pre-split blasting, there are the micro-cracks only on wall, no rock injury around the bolt. There is no obvious fracture on the surrounding rock. The micro-cracks of the wall under the intensity blasting vibration develop rapidly into the big cracks through the whole wall, the strain of the vault is far greater than other parts, and there are a few main cracks through the surrounding rock. The crack of surrounding rock of the joint cavity vault presents the horizontal and through shape, it develops horizontally in the bedding joint coverage, it develops through and inclined shape to the edge of the model outside the bedding joint coverage. Because the bedding joint influences the tensile strength of rock mass, the damage of the roadway is more serious than that of the complete cavity obviously.