深孔爆破预裂顶板及其对综放面初采期矿压与瓦斯影响规律的研究

发布时间：2018-04-19 23:34

本文选题：坚硬顶板 + 深孔爆破　；参考：《太原理工大学》2017年硕士论文

【摘要】：我国煤炭资源储量丰富,坚硬顶板煤层较多。厚硬顶板的存在严重威胁采煤工作面的安全生产,特别是在初采期间,顶板完整性较好,在短期内不会自行垮落,使得初次来压步距加大。一旦顶板大面积垮落,采空区瓦斯瞬间涌出,极易造成顶板和瓦斯事故,轻则设备损坏,重则人员伤亡。因此,使坚硬顶板提前垮落,从而避免顶板事故及瓦斯事故的发生得到了人们的高度重视。本文研究了采用深孔爆破技术对坚硬顶板进行预裂使其提前垮落的理论与技术,对深孔爆破岩石破碎基础理论进行了探讨,利用ANSYS/LSDYNA和UDEC软件分别对岩石爆破裂隙扩展和顶板初次断裂步距进行了模拟分析,并以大阳煤矿3404综放工作面为工程背景,设计和实施了爆破方案,并对深孔爆破预裂顶板改善综放面初采期顶板初次来压和瓦斯治理效果进行了实测分析。得出了以下主要结论:(1)确定了岩石爆破的相关参数。通过理论计算,得出岩石爆破形成的破碎区半径为38.5cm,裂隙区半径为195cm。利用ANSYS/LS-DYNA3D软件对岩石爆破后的裂隙扩展进行了数值模拟,得出岩石爆破形成粉碎区半径为39.5cm,裂隙区半径约为185cm。数值模拟结果同理论计算结果基本一致。(2)深孔爆破使顶板由固支梁结构变为悬臂梁结构,使顶板初次垮落步距减小。利用UDEC数值软件,对顶板在预裂条件下和非预裂条件下的初次垮落步距进行了模拟,结果表明:预裂爆破使顶煤的初次垮落步距减小了6.0m,直接顶初次垮落步距减小了9.6m,老顶初次来压步距减小了12.0m。(3)同一钻孔爆破前后进行窥视,爆破前钻孔壁比较完整,爆破后钻孔壁出现了较多的裂缝,证明爆破对顶板岩石起到了有效的预裂作用。(4)现场实测表明,与未进行预裂措施的3303工作面相比,3404综放面顶煤初次垮落步距和老顶初次来压步距分别提前了8m和11m;初次来压期间支架动载系数最小1.03、最大1.26,平均1.10。说明采取顶板预裂后,顶板初次来压期间,采场支护是安全的。(5)深孔预裂爆破能有效预防工作面初采期间瓦斯超限问题。初采前对顶板进行爆破预裂,使顶煤煤岩体内原生裂隙扩张,并产生新的裂隙,破坏了顶板的完整性,明显减小了顶煤的初次垮落和老顶的初次来压步距,减小了采空区的悬顶面积,使顶层辅助回风巷提前发挥作用,有利于工作面通风管理,降低了工作面和上隅角瓦斯浓度,确保了初采期间工作面的安全生产。(6)对高位钻孔瓦斯抽采浓度和抽采纯量的变化进行了实测分析,结果表明:高位钻孔瓦斯抽采浓度和抽采纯量的变化与顶板活动规律一致,说明预裂顶板使顶板岩层产生裂缝,并且老顶岩层提前断裂来压,导致大量瓦斯被高位钻孔抽出是初采期间工作面和上隅角瓦斯浓度降低的原因之一。
[Abstract]:China is rich in coal resources, and there are more hard roof coal seams. The existence of thick and hard roof seriously threatens the safety production of coal mining face, especially during the initial mining period, the roof integrity is good, and it will not collapse itself in the short term, which makes the initial pressure step increase. Once the roof collapses in a large area gas gushes out of the goaf easily causing roof and gas accidents light equipment damage and heavy casualties. Therefore, people attach great importance to the prevention of roof accidents and gas accidents by making hard roof collapse ahead of time. In this paper, the theory and technology of using deep-hole blasting technology to pre-crack hard roof to make it collapse ahead of time are studied. The basic theory of rock fragmentation in deep-hole blasting is discussed. ANSYS/LSDYNA and UDEC software are used to simulate the crack expansion of rock blasting and the initial breakage distance of roof, and the blasting scheme is designed and implemented with the 3404 fully mechanized caving face of Danyang Coal Mine as the engineering background. The effect of pre-split roof by deep hole blasting on the initial roof pressure and gas control in the initial mining stage of fully mechanized caving face is analyzed. The main conclusions are as follows: 1) the relevant parameters of rock blasting are determined. By theoretical calculation, the radius of fracture zone and fracture zone of rock blasting are 38.5 cm and 195 cm respectively. The crack propagation after rock blasting is simulated by ANSYS/LS-DYNA3D software. It is concluded that the radius of rock blasting is 39.5 cm and the radius of crack area is about 185 cm. The numerical simulation results are in good agreement with the theoretical results.) Deep hole blasting changes the roof structure from a fixed beam structure to a cantilever beam structure and reduces the initial collapse step distance of the roof. Using UDEC software, the initial collapse distance of roof under pre-cracking and non-pre-cracking conditions is simulated. The results show that the first caving distance of top coal is reduced by 6.0 m, the first collapse distance of direct roof is reduced by 9.6 m, and the initial pressure step of main roof is decreased by 12.0 m.f3) the borehole wall is relatively complete before and after blasting. There are many cracks in the borehole wall after blasting, which proves that blasting has an effective pre-splitting effect on roof rock. Compared with the 3303 working face without pre-splitting measures, the first collapse distance of top coal and the first starting step of main roof of No. 3404 top-coal caving face were 8m and 11m earlier, respectively, and the minimum dynamic load coefficient of the support during the initial loading period was 1.03m, the maximum 1.26m, and the average 1.10m. It is shown that after pre-splitting of roof, the stope support is safe during the initial pressure period of roof, and the deep-hole pre-splitting blasting can effectively prevent the gas over-limit during the initial mining of the working face. Before the initial mining, the roof was pre-cracked by blasting, which made the primary cracks in the top coal and rock expand, and produced new cracks, which destroyed the integrity of the roof, and obviously reduced the initial collapse of the top coal and the initial pressure step of the main roof. The suspended roof area of the goaf is reduced, and the auxiliary return air roadway of the top floor is brought into play in advance, which is beneficial to the ventilation management of the working face and the gas concentration in the working face and the upper corner. The change of gas extraction concentration and extraction scalar quantity in high borehole is measured and analyzed. The results show that the change of gas extraction concentration and scalar quantity in high borehole is consistent with the law of roof movement. It is shown that the pre-crack roof makes the roof rock layer crack and the main roof rock strata break and pressure ahead of time, which results in a large amount of gas being extracted from the high hole is one of the reasons for the decrease of the gas concentration in the working face and the upper corner during the initial mining.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712;TD235.33

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