秦洪岩(1987-), 男, 博士, 讲师, 研究方向为矿山安全和煤岩动力灾害防治, (E-mail)
为分析综放工作面前方巷道变形特征,以河林煤矿j7401综放工作面为研究对象,采用理论分析和现场实测方法进行深入研究。根据超前支承压力的分布曲线,定义了工作面前方巷道的3个变形阶段,分别为急速变形阶段、减速变形阶段和稳定变形阶段。急速变形阶段和减速变形阶段的分界点是超前支承压力和原岩应力的交点,减速变形阶段和稳定变形阶段的分界点是超前支承压力的峰值点。对j7401工作面开采过程中的超前支承压力和巷道变形分别进行观测,并采用最小二乘拟合方法分析整理观测数据。根据超前支承压力观测数据对巷道围岩变形阶段进行划分,急速变形阶段和减速变形阶段的分界点位于工作面前方8.1 m,减速变形阶段和稳定变形阶段的分界点是工作面前方19.8 m。根据巷道变形观测数据划分变形阶段,急速变形阶段和减速变形阶段的分界点位于工作面前方8.9 m,减速变形阶段和稳定变形阶段的分界点是工作面前方20.1 m。该划分方法的两个误差分别为0.8 m和0.3 m,证明根据超前支承压力划分巷道围岩变形阶段的方法可行,精度较高。
To analyze the deformation characteristics of the mining roadway located in front of the fully mechanized top-coal caving face, we researched the j7401 fully mechanized top-coal caving face of the Helin Coal Mine with theoretical analysis and field measurement. According to the distribution curve of the advanced abutment pressure, three deformation stages of the roadway ahead of the working face are defined, which are the quick deformation stage, the deceleration deformation stage, and the stable deformation stage. The cut-off point of quick deformation stage and deceleration stage is the intersection of advanced abutment pressure and the original rock stress. The cut-off point of the deceleration deformation stage and stable deformation stage is the peak of the advanced abutment pressure. In this work, the advanced abutment pressure and roadway deformation of j7401 working face in mining were observed respectively, and the observation data was analyzed by the method of least squares fitting. The deformation of the roadway surrounding rock was partitioned based on the advanced abutment pressure observation data:the cut-off point of quick deformation stage and deceleration stage was 8.1 m ahead of the working face, and the cut-off point of deceleration deformation phase and stable stage was 19.8 m ahead of the working face. The deformation was also partitioned based on the roadway deformation observation data, in which way the cut-off point of quick deformation stage and deceleration stage was 8.9 m in front of the working face, and the cut-off point of deceleration deformation phase and stable stage was 20.1 m ahead of the working face. The deviations of the two classification methods were respectively 0.8 m and 0.3 m, indicating the method to partition the roadway surrounding rock deformation stage based on the advanced abutment pressure observation data is feasible and the precision is high.
随着中国煤矿开采技术和开采机械设备不断完善,大型矿井综合机械化放顶煤开采已变得非常普遍,而且中国的综放开采技术在国际上也处于领先地位。掌握综放开采超前支承压力显现和巷道围岩变形特征,对深入研究综放开采的矿压显现、巷道支护和设备选型具有重要的意义。
在钱鸣高院士和侯朝炯教授等老一辈采矿工作者的带领下,目前对工作面超前支承压力和巷道围岩变形研究取得了许多建设性成果[
由于在工作面推进过程中有梁结构存在,显然在工作面前方会形成一个应力增高区,如
超前支承压力示意图
Sketch map of advanced support pressure
在塑性区内任意位置水平方向和垂直方向上的应力平衡方程为:
式中:
采用摩尔库伦准则对式(1)进行整理,得到
式中:
令:
式中:
在
式中
工作面前方超前支承压力的峰值出现在
在破坏区内煤岩层已经失去了完整性,承载能力很差,承载的压力一般都小于原岩应力,所以会造成巷道围岩变形量非常大,而且变形速度快,将此阶段称为巷道围岩急速变形阶段。在极限平衡区内煤岩层虽然发生了塑性变形,但还是一个非连续排列的整体,完整性和承载能力明显优于破坏区,承载的压力逐渐变大,且承载的压力一般都大于原岩应力,此区域的巷道变形量逐渐减小,变形速度放缓,将此阶段称为巷道围岩减速变形阶段。破坏区和极限平衡区统称为塑性区,塑性区的巷道变形量大,称为大变形阶段。在弹性变形区内煤岩层状态完好,岩层具有很好的承载能力,由于该阶段巷道受到的力大于原岩应力,巷道变形必然大于原岩应力状态下的巷道变形,但巷道变形量小,将此阶段称为稳定小变形阶段。可以得到超前支承压力与巷道围岩变形的位置关系,如
超前支承压力与巷道围岩变形的位置关系
The location relationship between advancing abutment pressure and surrounding rock deformation of roadway
河林煤矿j7401工作面为7(4)煤层的首采工作面,工作面布置如
j7401综放工作面布置图
Layout of j7401 fully mechanized caving face
J7401工作面推进100.0 m后初次来压已经结束,而且在此段煤层趋于近水平煤层,煤层厚度稳定,地质构造简单。故超前j7401综放工作面100.0 m开始布置4组观测站,每组布置2个钻孔,2个钻孔分别在运输巷道和回风巷道。为使监测得到的数据具有代表性,得到不同深度的应力显现特征,4组观测站的钻孔深度各不相同:第1组钻孔的孔深为3.0 m;第2组6.0 m;第3组12.0 m;第4组15.0 m。每个钻孔内布置1台钻孔应力计,钻孔高度距回采巷道底板1.5 m。应力计和钻孔在工作面内的布置参数如
应力钻孔测点布置示意图
Measuring point arrangement sketch map of stress drilling
随着j7401综放工作面不断向前推进,现场观测并记录工作面推进过程中各个钻孔内应力计的读数,对4组观测站8个钻孔观测到的数据进行整理,结果见
各深度钻孔超前压力变化
Advanced abutment pressure with diggerent drilling depth
为得出综放工作面前方不同位置超前支承压力的变化曲线,采用最小二乘拟合的数学方法对
将
超前支承压力拟合曲线
Fitting curve of advance supporting pressure
从
可确定巷道围岩的变形阶段:0.0~8.1 m为急速变形阶段;8.1~19.8 m为减速变形阶段;19.8~65.0 m为稳定小变形阶段;大变形阶段的范围是0.0~19.8 m。
为了掌握j7401综放面运输巷道和回风巷道受采动影响的围岩变形特征,研究分析综放工作面采动对回采巷道围岩变形的影响,需要进行回采巷道变形观测。根据巷道围岩变形观测的内容,确定在两条回采巷道内各布置一条观测线,每个观测线分别布置3个测站,测站间距为30.0 m,并采用“十”字交叉布点法对回采巷道的表面移近量进行观测,巷道内测站的布置参数如
巷道测站布置图
Layout of station in mining roadway
通过在j7401综放工作面回采巷道布置“十”字交叉测站,对回采巷道围岩变形量进行连续观测,对观测数据进行整理和分析,绘制出j7401综放工作面运输巷道和回风巷道各测站的巷道围岩日移近量的变化过程,如
工作面前方巷道围岩移近的速度变化
Moving speed of the surrounding rock in the roadway in front of the working face
通过对
上述分析说明工作面前方0.0~20.0 m范围内围岩变形活动程度非常强,20.0~60.0 m以外的围岩变形活动减弱,60.0 m以外围岩基本不受采动影响。
同样采用最小二乘拟合的方法对
工作面前方巷道日变形量拟合曲线
Fitting curve of daily deformation of roadway in front of the working face
从
对比
采用理论分析和现场实测方法,对综放工作面的超前支承压力和巷道围岩变形二者的关系进行了分析,得出以下主要结论:
1) 提出了工作面前方巷道的围岩变形阶段划分方法,将巷道围岩变形阶段划分为急速变形、减速变形和稳定小变形3个阶段,急速变形阶段和减速变形阶段统称为大变形阶段。急速变形阶段和减速变形阶段的分界为超前支承压力与原岩应力的交点,减速变形阶段与稳定变形阶段的分界为超前支承压力的峰值位置。
2) 对现场观测得到的超前支承压力和巷道围岩变形数据采用最小二乘拟合的方法进行分析,分析结果显示:根据超前支承压力曲线划分的巷道急速变形阶段和减速变形阶段的分界点与巷道围岩变形观测数据得到的二者分界点误差为0.8 m;根据超前支承压力曲线划分的巷道减速变形阶段和稳定变形阶段的分界点与巷道围岩变形观测数据得到的分界点的误差为0.3 m。可见根据超前支承压力划分工作面前方巷道围岩变形阶段的方法可行,精度较高。
3) 揭示了煤壁前方区域巷道围岩变形阶段与超前支承压力之间的联系:破坏区(急速变形阶段)和极限平衡区(减速变形阶段)的分界为超前支承压力曲线与原岩应力曲线的交点;塑性区(大变形阶段)和弹性区(稳定小变形阶段)的分界为超前支承压力峰值位置。
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