陕北地区是我国煤炭资源的主产区，但该区域水资源短缺、生态脆弱，由煤炭开采引起的地表开裂和地下水渗漏等环境问题日益突出。因此，如何实现煤炭安全、高效开采的同时最大限度减小对生态脆弱区环境的损害，达到煤炭资源大开发与生态环境保护协调发展是当下的主要目标。

为深入研究陕北煤层群重复采动下覆岩导水裂隙发育及错距开采应力传递规律，从根本上揭示煤层群错距开采对覆岩的影响机理，本文从煤层群开采区段煤柱错距方面入手，以小保当二号井为工程背景，综合运用理论分析、数值模拟和相似材料模拟等研究手段，对煤层群错距开采减损力学机理进行分析，并对煤层群错距方案进行了优化。主要结果如下：

通过对煤层群错距开采区段煤柱应力传递机理进行分析，推导出合理的错距范围表达式；概化出煤层群错距开采模型，并结合小保当二号井工程实例计算出合理错距范围。

错距煤柱范围σ_zz曲线呈“峰”状分布，煤柱中心出现主应力峰值；错距煤柱中心范围Z方向下沉值呈现“几”字形分布，煤柱中心下沉值最小。覆岩应力分布、煤柱中心应力峰值及煤柱Z方向下沉值，三者存在一致的最佳状态。双煤层错距开采时，最优错距为40m，最不利（最劣）错距为0m；煤层群错距开采时，在保持双煤层最优错距（40m）不变的情况下，其最优错距也为40m，最不利（最劣）错距为0m。

最不利错距开采方案, 导水裂隙带最大发育高度210m，为最优方案的1.1倍；覆岩6条裂隙导通地表，是最优方案的1.5倍；地表裂缝最大宽度为0.75m，为最优方案的 1.67倍；地表裂缝最大错台为1.2m，是最优方案的20倍；地表下沉曲线发生2次突变，地表可见明显裂缝及隆起区3处。

煤层群错距减损最优方案能够有效降低覆岩导水裂隙带发育高度，减轻地表裂缝发育强度，充分地实现保水减损开采。研究结果可为陕北煤层群减损开采提供一定的理论依据和参考。

Northern Shaanxi is the main production area of ​​in China coal resources, but the short of water resources, ecologically fragile and environmental problems such as surface cracks and groundwater leakage caused by coal mining in the region have become increasingly enormous. Therefore, how to attain safe and efficient coal mining while minimizing environmental damage to ecologically fragile areas and achieving coordinated development of coal resource development and ecological environmental protection is the main goal at the moment.

In order to fundamentally reveal the influence mechanism on overburden of staggered distance mining in multiseam, the development law of water-conducting fissure zone and the stress transfer law of the staggered distance mining under repeated mining was been systematically studied in this paper. First, the coal pillar staggered distance mining in multiseam was consided. The theoretical analysis, numerical simulation and similar material simulation were comprehensively used to analyze the reduction damage mechanical mechanism of the staggered distance mining. And the staggered distance mining plans were optimized by the engineering background of the Xiaobaodang No.2 coal mine. The results are as follows:

Subsequence, the staggered distance mining model of the multiseam was generalized and a reasonable staggered distance range was derived. A reasonable range of staggered distance mining was calculated coupled with the of Xiaobaodang No.2 Coal Mine geological condition.

The σ_zz curve showed a “peak” shape and the principal stress peak value appeared in the center of the coal pillar. The Z displacement curve domenstrated a “Л” shape and the smallest settlement value illustrated in the center of the coal pillar. The optimal of stress distribution, the optimal of peak stress, and the optimal of Z displacement appeared in the same scheme. The optimal staggered distance value was 40 m, and the most unfavorable (worst) distance value was 0 m, in staggered distance mining of double seams. The optimal staggered distance value was 40 m, and the most unfavorable (worst) distance value was 0 m, under the condition of keeping the optimal staggered distance value of the double seams (40m) , in staggered distance mining of multiseam.

The most unfavorable staggered distance mining scheme had a maximum development height of 210 m in the water-conducting fissure zone, which was 1.1 times that of the optimal scheme. There was six fractured in the overburden conduct to the ground, which was 1.5 times the optimal scheme. The maximum width of surface cracks was 0.75 m, which was 1.67 times that of the optimal scheme, and the maximum vertical displacement of surface cracks was 1.2 m, which was 20 times that of the optimal scheme. The surface subsidence curve had two sudden changes, and the surface had three obvious cracks and heave areas.

The optimal scheme of reduction damage staggered distance mining in multiseam could effectively reduce the development height of water-conducting fissure zone in the overburden, sligten the development intensity of surface cracks, and fully realize water conservation and reduction damage mining. The research results could provide a certain theoretical basis and reference for the reduction damage mining of multiseam in northern Shaanxi.

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