【作者】 郭伟；

【导师】 冯国瑞； 李竹；

【作者基本信息】 太原理工大学 ， 矿业工程， 2024， 硕士

【摘要】 充填开采是控制岩层移动并减少地表沉陷与环境损害的重要途径,而充填材料来源不足和充填成本高昂已成为制约井工煤矿充填开采技术推广应用的主要瓶颈。探寻重点区域的低充填率充填新方法与配套技术是充填开采技术应对材料短缺困局亟待攻关的科学难题。本文结合煤矿井下“结构充填开采”的学术思想,从顶板岩层断裂特征及铰接形态出发,给出了井下工作面结构充填关键充填位置的确定方法,分析了关键位置充填体载荷分布特征及承载特性。论文主要研究内容及取得的创新成果如下:（1）通过理论分析探究了基本顶破断铰接形态、沉降规律。推导了首采工作面与临空工作面基本顶破断块体尺寸计算公式从而得到块体铰接线的分布位置;揭示了基本顶赋存参数及工作面采宽对基本顶破断块体尺寸的影响规律,并根据上述分析结果根据线性拟合对公式进行修正,得到了修正系数的计算公式。（2）利用弹塑性理论对基本顶“倒四坡顶”式沉降破断规律进行深入分析。基于基本顶破断沉降规律提出了重点控制基本顶最大挠度位置即板结构潜在张拉断裂位置（塑性铰发育位置）的“工字型”结构充填新方法。（3）通过FLAC^3D数值模拟软件探究了新阳矿2^#煤层首采及临空工作面“工字型”充填最佳方案,根据采宽以及推进方向的测线数据并结合塑性区分布特征,分析了“工字型”结构充填较其它充填方式在顶板控制及长效承载方面的优势。以全部充填及间隔2 m充填2 m方案为对照,分析了“工字型”结构充填新方法在经济效益即在节省充填用量方面的优越性。（4）基于关键位置充填体应力测线及云图数据,结合理论分析揭示了顶板非均匀沉降引起充填条带上覆载荷出现的非均匀分布特征,充填条带上覆应力呈现拱形,曲率即载荷非均匀程度随条带宽度的减少逐渐增加。顶板非均匀变形的程度同样会引起充填体上覆载荷非均匀程度的变化,整体呈正相关。（5）利用自主研发的非均匀加载装置,研究不同非均匀程度载荷下矸石胶结充填体的力学及破坏特征,并通过声发射（AE）和数字图像相关技术（DIC）联合监测,揭示了非均匀载荷作用下关键位置充填体的动态损伤演化规律。结果表明:载荷的非均匀程度η对矸石胶结充填体的强度有显著影响。随着η的增加,相同充填原材料及配比下试样单轴抗压强度先增大后减小。此外,随着η的增加,应力峰值点的振铃计数也呈先增加后减少的趋势。试样承受非均匀载荷时,试样内部骨料、胶结剂发生摩擦滑移,并随着应力差的增加而逐渐加剧,错动有利于剪切裂纹的发展和扩展。因此,随着η的增加,宏观裂纹位置逐渐从边界向中心移动,试样中剪切裂纹所占比例逐渐增大,破坏模式逐渐从以拉伸裂纹为主的“X”型过渡到拉伸-剪切复合裂纹再到以剪切裂纹为主的倒“Y”型。同时随着η的增加,试样表面宏观主贯通裂纹的开度先减小后增大,与基于声发射b值大小对裂纹尺寸的判断一致,即表现出“大裂纹小b值、小裂纹大b值”的典型特征。根据试验结果得到了充填体上覆载荷非均匀程度的临界值,若η大于40%应及时对充填体进行补强,增加其宽度或进行柱旁支护;在充填条带宽度设计时,应合理选择其宽度以使η在40%以下。研究结果可为结构充填开采充填体布设位置选取、充填方案设计以及充填体失稳防控提供参考和借鉴。更多还原

【Abstract】 Backfilling mining is an important way to controlling strata movement and reducing surface subsidence and environmental damage.However,insufficient sources of raw materials and high backfilling costs have become major bottlenecks,limiting the application of backfilling mining technology in underground coal mines.Exploring new methods and supporting technologies of backfill with low backfilling rate in key areas is a scientific problem that needs to be solved urgently by backfilling mining technology to deal with the shortage of materials.Based on the academic thought of“constructional backfill mining”in underground coal mine,this paper gave a method to determine the key backfilling position of constructional backfill in underground working face from the fracture characteristics and hinged form of roof strata,and the load distribution law and bearing characteristics of backfill in key position were analyzed.The main research contents and innovative achievements of this paper are as follows:（1）Through theoretical analysis to explore the main roof broken hinge form,settlement law.The first mining working face and the working face with one side goaf of the main roof broken block size calculation formulas were deduced so as to get the distribution of the block hinge line;the influence law of occurrence parameters of the main roof and the mining width of the working face on the size of the main roof breaking block was revealed,and according to the above analysis results according to the linear fitting to modify the formula,the calculation formula of the correction coefficient was obtained.（2）The elastic and plastic theory was used to in-depth analyze the“inverted hip roof”law of settlement and fracture of the main roof.Based on the fracture settlement law of the main roof,a new method of“I-shaped”constructional backfill was proposed,which focuses on controlling the position of the maximum deflection of the main roof,i.e.,the position of the potential tensile fracture of the plate structure（plastic hinge development position）.（3）FLAC^3Dnumerical simulation software was used to explore the best scheme of“I-shaped”backfill in the first mining working face and the working face with one side goaf of 2^#coal seam in Xinyang Mine.According to the survey line data of mining width and advancing direction,combined with the distribution characteristics of plastic zone,the advantages of“I-shaped”constructional backfill over other backfilling methods in roof control and long-term bearing were analyzed.Taking the scheme of full backfilling and interval 2 m backfilling 2 m as the control,the superiority of the new backfilling method of“I-shaped”in economic benefit,that is,saving the backfilling amount,was analyzed.（4）Based on the stress survey line and cloud chart data of the backfill at the key position,combined with theoretical analysis,the non-uniform distribution characteristics of the overlying load of the backfilling strip caused by the non-uniform settlement of the roof were revealed.The overlying stress on the backfilling strip shows an arch shape and the curvature,i.e.,the degree of non-uniformity of load,gradually increases with the decrease of the width of the strip,and the degree of the non-uniform deformation of the roof causes the non-uniformity of the overlying load of the backfill to change,which is positively correlated as a whole.（5）By using the self-developed non-uniform loading device,the mechanics and failure characteristics of cemented coal gangue backfill under different non-uniform degree of loads were studied.Through the joint monitoring of acoustic emission（AE）and digital image correlation（DIC）,the dynamic damage evolution law of backfill at key positions under non-uniform loads was revealed.The results show that the non-uniformity of the load has a significant effect on the strength and failure mode of cemented coal gangue backfill.With an increase in the degree of non-uniformity of load（η）,the uniaxial compressive strength of the specimen with the same backfilling material ratio increased and then decreased.In addition,with an increase inη,the ringing counts of the stress peak point also increased first and then decreased.When the specimen was subjected to non-uniform load,the friction slip occurred in the aggregate and cementing agent inside the specimen,and gradually increased with the increase of stress difference.The dislocation is beneficial to the development and expansion of shear cracks.Therefore,with an increase inη,the macroscopic crack position gradually moved from the boundary to the center,the proportion of shear cracks in the specimen gradually increased,and the failure mode gradually transitioned from the“X”type dominated by tensile cracks to the tensile-shear composite crack and then to the inverted“Y”type dominated by shear cracks.Meanwhile,with an increase inη,the opening displacement of the macroscopic main penetrating cracks on the surface of the specimen first decreased and then increased,which was consistent with the judgment of crack size based on the AE b-value,i.e.,it showed the typical characteristics of“small b-value–large crack and large b-value–small crack”.According to the test results,the critical value of the non-uniformity degree of the overlying load of the backfill is obtained.According to the test results,the critical value of the non-uniformity of the overlying load of the backfill is obtained.Ifηis greater than 40%,the backfill should be reinforced in time,its width should be increased or the backfill side support should be carried out;when designing the width of the backfilling strip,its width should be rationally chosen so thatηis below 40%.The research results can provide reference for the layout of backfill in constructional backfill mining,the design of backfilling scheme and the prevention and control of backfill instability.更多还原