煤系地层超声波激励与机械冲击复合破岩机理研究

There are some general problems in the rock engineering construction of underground coal mine, including the low strength of drilling, the slow speed of hole forming, and the great loss of machine and material and so on. In order to effectively solve the prominent contradiction between the construction speed and the maintenance effect, the ultrasonic technology is introduced into the rock crushing to reduce the difficulty of cutting and improve the rock breaking efficiency with the joint action of mechanical impact by promoting the expansion of rock cracks. This project uses the method of comprehensive research and by mastering the physical and mechanical response characteristics of rock to ultrasonic excitation, we can clarify the correlation rule between rock vibration volume and ultrasonic energy. In order to set up the dynamic model of a new type of rock breaking system, reveal the mechanism of rock breaking by composite ultrasonic vibration and mechanical impact load ,and make clear the effective mode of high efficiency rock breaking, the effects of ultrasonic power, mechanical impact load size and mode of action on the range of rock medium, and the crack propagation and fracture process are investigated. By analyzing the interaction process and bearing characteristics of rock breaking equipment and high-frequency vibratory rock, the influence rule of its structural parameters on the whole rock breaking effect are revealed, and finally, the principle and implementation criteria of "vibration and impact" high efficiency rock breaking are put forward. The research results will further enrich the basic theory of high efficient rock fragmentation, provide support for rapid construction of rock engineering, and provide reference for geological drilling, oil and gas development and comprehensive mechanized mining of metal mines.

煤矿井下岩石工程施工中普遍面临钻进效率低、成孔速度慢、机具与材料损耗大等问题，为有效解决施工速度与维护效果间的突出矛盾，将超声波技术引入到岩石破碎当中，通过超声波激励促进岩石裂隙扩展，降低截割难度，并与机械冲击共同作用提高破岩效率。项目采用综合研究的方法，通过掌握岩石对超声波激励的物理力学响应特征，明确其振动体量与超声能量的相关性规律；通过考察超声波功率与冲击载荷大小及作用方式变化对岩石作用范围、裂纹扩展及破裂过程的影响，建立新型破岩体系的动力学模型，揭示超声波激励与冲击载荷复合作用下岩石的破碎机理，确立高效破岩的有效模式；通过分析破岩机具与高频振动岩石的相互作用及其承载特性，揭示其结构参数对整体破岩效果的影响规律，最终提出“振动—冲击”高效破岩的原理与实施准则。研究成果将进一步充实岩石破碎的基础理论，为岩石工程快速施工提供支撑，也可为地质钻探、油气开发及金属矿山综合机械化落矿等提供借鉴。

本项目针对目前煤矿井下岩石工程尤其是硬岩掘进效率低、机具与材料损耗大等问题，将超声波技术引入到岩石破碎当中，通过超声振动激励促进岩石裂隙扩展，降低截割/钻凿难度，提高破岩效率。项目综合运用现场调研、理论分析、室内实验和数值计算等方法，围绕超声振动激励下的岩石物理力学响应特征及破碎机理开展了系统研究。主要成果如下：.①掌握了煤系地层代表性岩石振动频率基本特征，明确了岩石自身特性对其固有振动频率的影响，采用自主搭建的超声振动激励破岩装置，测得了不同功率、频率超声振动激励下岩石的力学响应及其物理力学特性的变化特征、受迫振动岩石的尺度关系，得出了频率、振幅、静载力等影响超声振动激励岩石破碎的关键因素。.②建立了“简谐激振力-粘弹性体”振动系统力学模型、岩石微元体运动方程，阐明了高频振动激励下岩石的动态效应，揭示了岩石微元体位移与加速度显著的空间差异性，明确了超声振动“激振力+静载力”复合作用破岩的有效性和优越性；建立了岩石受集中、均布振动载荷力学模型，明确了岩石在高频激振力和静载力复合作用下拉、剪等应力分量的演化特征。.③明确了超声振动激励与机械冲击能量、作用方式及其相互变化对岩石介质裂纹扩展及破裂过程的影响特征，获得了固定频率下超声振动循环激励岩石“裂纹萌生-裂纹扩展、上端部崩裂脱落-循环侵入”三阶段渐进破坏特征；掌握了岩石随激励时间增加环向应变增幅加大、轴向应变增幅减小的变形特征，提出了以应变率变化量为指标的岩石破裂判定方法。.④掌握了破岩过程中岩石破裂与能量演化特性，明确了振动频率、振幅、受载面积和围压等因素对破岩效率影响的敏感性。研究了超声振动激励下破岩机具与岩石的相互作用特征及其承载特性，提出了以岩性、超声功率/频率等为综合评价指标的超声振动激励弱化岩石强度、改善破岩效果的实施方式与基本原则，设计了超声振动激励及与机械复合破岩的初步方案。