针对沟谷区工作面厚煤层分层开采过程中出现的应力集中、矿压显现强烈等问题，本文以白芨沟煤矿为研究对象，采用现场调研实测、相似模拟实验、数值计算和理论分析相结合的研究方法，深入研究了沟谷区工作面分层开采矿压显现规律、覆岩运移及光纤表征、应力演化规律和工作面强矿压显现机理。具体研究成果如下：

（1）掌握了沟谷区分层开采工作面重复采动覆岩运移特征。工作面上分层开采，背沟开采采动裂缝直通地表，岩块偏转和回转运动明显；山顶开采山体岩块会以山体稳定关键区煤体作为支点产生偏转运动；向沟开采覆岩弯曲下沉结构较为稳定。中、下分层重复采动影响下，采动裂隙呈周期性开裂—闭合，开裂程度逐层加剧，采动裂缝包裹的梯形岩块和山体岩块会周期性偏转和回转。岩层断裂角逐层增大，直至近乎“直角”。

（2）揭示了沟谷区分层开采工作面过地表山体的来压规律。工作面上分层来压特征呈明显的分阶段性，呈3段分布。背沟开采工作面平均来压步距最小，动载矿压严重；山顶开采来压步距次之，强矿压显现明显；向沟开采来压步距最大，来压强度较为缓和。工作面中、下分层开采受重复采动影响，来压步距和来压强度皆呈逐层减小趋势，来压分阶段性不明显，矿压显现较为缓和，呈现小周期来压特征。

（3）得到了沟谷区工作面原岩应力分布特征及支承应力演化规律。原岩应力分布形态与地表山体起伏相一致，呈山体中部应力大，两侧应力小，并随埋深的增加，原岩应力不断增大，应力梯度差越明显。随分层开采累计采厚的增加，上、中、下三分层应力分布呈逐层减小趋势，应力集中区呈“条带”分布。

（4）建立了地表山体静载力学模型，揭示了沟谷区工作面强矿压显现机理。工作面受地表山体影响，山顶部分区域处于工作面强矿压显现临界状态。当山体稳定关键区煤体被采出，山体岩块随固支点偏转，引起工作面强矿压显现。

To address the problems of mine stress concentration and strong mine pressure appearing in the process of stratified mining of thick coal seams in the working face of the gully area, this paper takes Baijigou coal mine as the research object. Using a research methodology that combines actual measurements from on-site research, similar simulation experiments, numerical calculations, and theoretical analyses, in-depth research was conducted on the mining pressure manifestation law, overlying rock migration and fiber optic characterization, stress evolution law, and strong mining pressure manifestation mechanism of the working face in the valley area. Specific research findings are listed below:

(1) Mastered the overlying rock transport characteristics of the working face affected by repeated mining under the conditions of stratified mining in the valley area. During the layered mining on the working face, the mining-induced cracks generated during the back ditch mining have been directly connected to the surface, and the deviation and rotation movement of the rock blocks are obvious. During the mountaintop mining, the rock blocks on the mountain have deflected and moved with the coal seams in the stable key area of the mountain as the fulcrum. During the trench mining, the overlying rock has bent and sunk, and the overlying rock structure has remained relatively stable. Under the influence of repeated mining, the fractures in the middle and lower layers have periodically cracked and closed, and the degree of cracking has intensified layer by layer. Trapezoidal rock blocks and mountain rock blocks enclosed by mining cracks have periodically deflected and rotated. The fracture angle of the rock layer has increased layer by layer until it is almost at the right angle.

(2) The mining pressure manifestation law of the working face passing through surface mountains under the condition of stratified mining in the valley area has been obtained. The pressure characteristics of layered mining on the working face show a clear phased distribution with a three-stage distribution. During the back ditch mining stage, the average pressure step distance of the working face is the smallest, and the dynamic loading ore pressure is severe. The average pressure step distance of the working face during the mountaintop mining stage is second, and the strong mining pressure is evident. The average pressure step distance of the working face during the trench stage is the largest, and the pressure intensity is relatively gentle. The middle and lower layers are affected by repeated mining, and the step distance and intensity of the pressure decrease layer by layer. The staged pressure is not obvious, and the mining pressure is relatively gentle, showing a small periodic pressure characteristic.

(3) The stress distribution characteristics and stress evolution law of the original rock in the working face of the valley area have been obtained. The stress distribution pattern of the original rock is consistent with the undulation of the surface mountain. The stress of the original rock is higher in the middle of the mountain and lower on both sides. As the burial depth increases, the original rock stress continuously increases, and the difference in stress gradient becomes more obvious. As the cumulative thickness of layered mining increases, the stress distribution in the upper, middle, and lower layers shows a decreasing trend layer by layer, and the stress concentration area shows a "strip" distribution.

(4) A mechanical model of static compressive stress on surface mountains was constructed, revealing the mechanism of strong mining pressure manifestation in working faces in valley areas. The working face is affected by the surface mountains, causing some areas on the mountaintop to be in a critical state of strong mining pressure manifestation on the working face. When the coal seam in the stable key area of the mountain is mined out, the rock blocks of the mountain deflect with the fixed support point, causing strong mining pressure to appear on the working face.

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