【作者】 张渊；

【导师】 梁顺；

【作者基本信息】 中国矿业大学 ， 采矿工程， 2022， 硕士

【摘要】 巷道掘进是煤矿开采最重要环节之一,掘进工效直接决定着煤矿开拓、准备进度和煤炭开采的正常生产接续,岩巷快速掘进为当前煤炭工业亟需研究并解决的关键性技术难题。近年来水力压裂作为一种煤岩体预裂处理技术,在冲击矿压防治、坚硬顶板弱化、煤层增透强化瓦斯抽采等方面应用较广泛,且取得较好效果。因此本文研究了基于水力压裂辅助破岩的岩巷快速掘进技术及工艺,对于提高岩巷掘进速度、缓解采掘接续紧张、保障煤矿的高产高效生产具有重要意义。同时建立了基于水力压裂辅助破岩的硬岩巷道快速掘进作业线,为水力压裂辅助预裂坚硬岩石巷道的现场推广应用提供了初步的理论基础与思路,进一步促进了水力压裂技术在保障煤矿安全高效生产中的应用。本文以多孔水力压裂技术预裂坚硬岩石巷道促进硬岩巷道快速掘进为研究核心,采用文献调研与理论分析、PFC颗粒流数值模拟、基础研究及工艺设计相结合的方法,研究了基于水力压裂技术辅助破岩的硬岩巷道快速掘进技术及工艺。研究成果丰富了硬岩巷道水力压裂下裂缝扩展理论,对水力压裂预裂坚硬岩石巷道具有现场指导意义。本文的研究路线及研究方法同时对预裂坚硬顶板、岩巷快速掘进等工程应用具有借鉴意义,主要研究结论如下:(1)基于PFC颗粒流数值模拟构建了多孔水力压裂流固耦合模型。基于招贤煤矿二采区+980 m水平带式输送机大巷岩石物理力学性质测试结果进行了PFC2D数值模拟细观参数的试错法标定。细观参数标定结果显示颗粒流数值模拟得到的单轴抗压强度同实验室测试结果仅相差1.0%;弹性模量为2.725 GPa仅相差0.7%,所标定的PFC颗粒流模拟细观参数具有合理性,为后续的不同参数条件下水力压裂数值模拟提供了较为科学的参数基础。(2)揭示了不同压裂参数影响下单孔水力压裂岩石裂缝扩展特性及规律。研究了压裂孔径及注水压力对水力压裂裂缝扩展规律的影响,研究发现随压裂孔径和注水压力的增加,拉伸/剪切裂缝数目不断递增,同时压裂影响半径扩大;设计了不同模型水平应力与垂直应力比值σ_h/σ_v(侧压系数)方案。研究得到随着σ_h/σ_v增加(巷道埋深减小),拉伸/剪切裂缝数目不断减少,压裂影响半径同时缩小。也即相对于浅埋深条件,埋深较大巷道所处地应力条件下水力压裂裂缝数目增加,水力压裂影响半径扩大。可初步认为水力压裂辅助破岩对于深部高应力巷道适用性及效果更好。(3)揭示了不同岩层组合形式条件下裂缝在软硬岩层交界面处的变化规律。通过对比4种不同“软”硬岩层组合形式条件下水力压裂裂缝扩展及裂缝击穿“软”硬岩层交界面的力学行为得到:水力压裂裂缝在由较软岩层进入硬度较高岩层后扩展速度变慢,且延伸扩展长度变小;水力压裂主裂缝在从较软岩层穿越较硬岩层交界面后会发生一定角度的偏转,且裂缝形态由“软”岩层中的短-宽裂缝变化为较硬岩层中的长-细裂缝。在较软岩层中易产生短-宽裂缝,而在较硬岩层中易产生长-细裂缝。(4)研究揭示了多孔水力压裂条件下水力压裂裂缝增长变化规律。受多孔水力压裂裂缝耦合影响,水力压裂裂缝的增长变化过程可划分为4个阶段:第一阶段,迅速产生拉伸裂缝,但剪切裂缝产生数目极少;第二阶段,拉伸裂缝继续增加,但裂缝增加速度逐渐降低;第三阶段,拉伸裂缝二次迅速增加,同时剪切裂缝也不断增加;第四阶段,裂缝数目不断增加但增速降低,逐渐趋于平缓,最终所产生剪切裂隙与拉伸裂隙数目比约为1:9,多孔水力压裂缝网中以拉伸裂缝为主。(5)设计优化了基于水力压裂辅助破岩的硬岩巷道快速掘进工艺及作业线。以招贤煤矿二采区+980 m水平带式输送机大巷为研究对象,根据前文数值模拟研究结果,针对不同注水方式、注水孔径、压裂孔间距进行了水力压裂基本参数优化;基于水力压裂辅助破岩工序对原劳动组织进行了优化协调,设计了基于水力压裂辅助破岩的硬岩巷道快速掘进工艺及作业线。预估可以降低单排割岩时间约40分钟,日进尺提高约20%,掘进工效提升较为明显。论文提出了利用多孔水力压裂使岩体内部生成复杂缝网,从而预裂坚硬岩石巷道,同时通过注水软化岩体,降低了综掘机截割头损耗,减少了工作面呼吸性粉尘浓度,显著改善井下岩巷掘进的作业环境。所设计的基于水力压裂辅助破岩的硬岩巷道快速掘进工艺及作业线具备一定的合理性和优势,有望促进我国煤矿坚硬岩石巷道掘进速度,且论文工作对促进水力压裂技术在保障煤矿安全高效生产中的应用具有重要意义。该论文有图55幅,表21个,参考文献101篇。更多还原

【Abstract】 Roadway excavation is one of the most important links in coal mining.The excavation work efficiency directly determines the coal mine development,preparation progress and the normal production continuation of coal mining.In recent years,hydraulic fracturing,as a pre-fracturing treatment technology for coal and rock mass,has been widely used in the prevention and control of rock burst,the weakening of hard roofs,and the enhancement of gas drainage in coal seams,and has achieved good results.Therefore,this thesis studies the fast excavation technology and process of rock roadway based on hydraulic fracturing assisted rock breaking,which is of great significance for improving the excavation speed of rock roadway,alleviating the tension of mining continuity,and ensuring high-yield and efficient production of coal mines.At the same time,a fast excavation operation line for hard rock roadways based on hydraulic fracturing-assisted rock breaking was established,which provided a preliminary theoretical basis and ideas for the field promotion and application of hydraulic fracturing-assisted pre-fracturing hard rock roadways,and further promoted the application of hydraulic fracturing technology in the field.Application in ensuring safe and efficient production of coal mines.This thesis takes porous hydraulic fracturing technology to pre-fract hard rock roadways to promote rapid excavation of hard rock roadways as the research core,using the method of combining literature research and theoretical analysis,PFC particle flow numerical simulation,basic research and process design,to study the hydraulic fracturing method based on hydraulic fracturing Rapid excavation technology and technology of hard rock roadway with the aid of cracking technology.The research results enrich the theory of crack propagation under hydraulic fracturing in hard rock roadways,and have field guiding significance for hydraulic fracturing pre-fracturing hard rock roadways.The research route and research method of this thesis also have reference significance for engineering applications such as pre-split hard roof and rapid excavation of rock roadway.The main research conclusions are as follows:(1)A fluid-solid coupling model of porous hydraulic fracturing was constructed based on the PFC particle flow numerical simulation.Based on the test results of rock physical and mechanical properties of the+980m horizontal belt conveyor roadway in the second mining area of Zhaoxian Coal Mine,the trial-and-error method was used to calibrate the meso-parameters of PFC2D numerical simulation.The calibration results of mesoscopic parameters show that the uniaxial compressive strength obtained by the numerical simulation of particle flow is only 1.0%different from the laboratory test results;the elastic modulus is 2.725 GPa,which is only 0.7%different.The calibrated PFC particle flow simulation mesoscopic parameters are reasonable It provides a scientific parameter basis for the subsequent numerical simulation of hydraulic fracturing under different parameter conditions.(2)The fracture propagation characteristics and laws of single-hole hydraulic fracturing rock under the influence of different fracturing parameters are revealed.The influence of fracturing pore size and water injection pressure on the propagation law of hydraulic fracturing cracks was studied.It was found that with the increase of fracturing pore size and water injection pressure,the number of tensile/shear fractures increased continuously,and the fracturing influence radius expanded;Model horizontal stress to vertical stress ratioσh/σv(lateral pressure coefficient)scheme.The research shows that with the increase ofσ_h/σ_v(the buried depth of the roadway decreases),the number of tensile/shear fractures decreases continuously,and the radius of influence of fracturing decreases at the same time.That is to say,compared with the shallow burial depth condition,the number of hydraulic fracturing cracks increases and the influence radius of hydraulic fracturing increases under the ground stress condition of the roadway with a larger burial depth.It can be preliminarily considered that hydraulic fracturing-assisted rock breaking has better applicability and effect for deep high-stress roadways.(3)Revealing the changing law of fractures at the interface of“soft”and hard rock layers under the conditions of different rock formations.By comparing the mechanical behavior of hydraulic fracturing fracture propagation and fracture penetration through the interface of“soft”hard rock layers under the conditions of four different“soft”hard rock layers,it is obtained:after the hydraulic fracturing fractures enter from the softer rock layer into the higher hardness rock layer The propagation speed becomes slower,and the extension length becomes smaller;the hydraulic fracturing main fracture will deflect to a certain angle after crossing the interface of the harder rock layer from the softer rock layer,and the fracture morphology is changed from the short-to-wide fracture in the“soft”rock layer.Changes to long-fine fractures in harder rock formations.Short-wide fractures are prone to occur in softer rock formations,while long-fine fractures are prone to occur in harder rock formations.(4)The study revealed the changing law of hydraulic fracturing fracture growth under porous hydraulic fracturing conditions.Affected by the coupling of porous hydraulic fracturing fractures,the growth and change process of hydraulic fracturing fractures can be divided into four stages:the first stage,tensile fractures are rapidly generated,but the number of shear fractures is very small;the second stage,tensile fractures Continue to increase,but the increase rate of cracks gradually decreases;in the third stage,the tensile cracks increase rapidly twice,while the shear cracks also continue to increase;in the fourth stage,the number of cracks increases but the growth rate decreases,and gradually tends to be flat,and finally The ratio of the number of shear fractures to tensile fractures is about 1:9,and tensile fractures are dominant in the porous hydraulic fracture network.(5)Design and optimize the fast excavation process and operation line of hard rock roadway based on hydraulic fracturing-assisted rock breaking.Taking the+980 m horizontal belt conveyor main road in the second mining area of Zhaoxian Coal Mine as the research object,according to the previous numerical simulation research results,the basic parameters of hydraulic fracturing were optimized for different water injection methods,water injection diameters,and fracturing hole spacing;The fracturing-assisted rock-breaking process optimizes and coordinates the original labor organization,and designs the hard rock roadway rapid excavation process and operation line based on hydraulic fracturing-assisted rock-breaking.It is estimated that the cutting time of a single row can be reduced by about 40 minutes,the daily footage can be increased by about 20%,and the tunneling efficiency has been improved significantly.The thesis proposes the use of porous hydraulic fracturing to generate a complex network of fractures inside the rock mass to pre-crack the hard rock roadway.At the same time,the rock mass is softened by water injection,which reduces the loss of the cutting head of the fully mechanized excavator and reduces the concentration of breathing dust on the working face.Improve the working environment of underground rock tunneling.The fast excavation process and operation line of hard rock roadway based on hydraulic fracturing-assisted rock breaking has certain rationality and advantages,and it is expected to promote the excavation speed of hard rock roadway in my country’s coal mines.And the work of the thesis is of great significance for promoting the application of hydraulic fracturing technology in ensuring the safe and efficient production of coal mines.The thesis has 55 figures,21 tables,and 101 references.更多还原