渭北矿区长期受到基岩水威胁，由于开采扰动作用基岩水转变为采空水，防水煤柱长期受弱酸性采空区积水的浸泡将导致煤柱强度的衰减，加速煤柱的蠕变影响自身的稳定性，甚至导致防水煤柱破损稳，造成涌水溃帮灾害，威胁临近采面安全。从采空区积水以及煤体蠕变特性对煤柱留设宽度以及长期稳定性评价已十分必要。基于此，本文采用试验研究，理论分析，现场实测等手段对渭北矿区王村煤矿防水煤柱合理留设宽度及长期稳定性进行分析，研究结果表明：

（1）通过对王村煤矿所取煤样进行三轴压缩试验以及蠕变试验分析，同级围压下保水煤样的抗压强度、粘聚力较天然煤样低，蠕变变形增加，水对煤体强度有明显软化作用，加速了煤体蠕变；而在高围压条件下，煤体强度则较低围压高，变形能力变弱，围压增加一定程度限制了围岩变形，与对巷道围岩进行锚固机理一致。

（2）分析巷道掘进时煤柱弹塑性区宽度理论发现，巷道掘进时煤柱中部弹性核区主要与巷道高度、支承压力峰值系数有关。而煤柱两侧塑性破碎区受支承压力峰值、煤体强度以及支护力等因素影响，但影响幅度不同，随支承压力峰值巷道高度顶板下沉角增加而增加，随煤体强度支护力增加而减小。提高帮部锚固强度控与制顶板下沉可以有效抑制塑性区的增长。

（3）根据煤层回采煤柱弹塑性区宽度计算理论分析，煤柱弹性区宽度与水压成正比关系，当采空侧水压过大时，应该煤柱核区宽度获及时对排水可有效缓解采空区水压力；煤柱塑性区应力、应变以及位移都随时间变化而变化，塑性破碎区域随时间不断向煤柱中心转移，采空区侧塑性区宽度蠕变增量较大，验证了水对煤体弱化以及加速蠕变作用；煤体应变软化系数对煤柱塑性区初始值影响较大，对最终蠕变稳定量影响较小，而支护力的增加可有效抑制煤柱的蠕变作用。

（4）掘进巷道理论留设宽度相较与回采煤层时的理论留设宽度较小，但其值与煤层回采塑性区宽度初始值相近，验证了两种理论的合理性。巷道掘进塑性区宽度计算为煤柱理论留设宽度提供了参考作用，当回采后采空区积水较小，或煤体强度较高时，可直接采用该理论计算煤柱留设宽度。

（5）通过对锚索加固后的煤柱支承压力以及帮部与顶板的收敛量监测发现，锚索补强取得了良好的效果，煤柱支承压力峰值稳定在距煤壁处4m左右，煤柱帮部最大收敛量0.3m，进一步验证了理论公式的合理性，为两种工况下煤柱留设提供了理论参考。

Weibei mining area has been threatened by bedrock water for a long time. Due to mining disturbance, bedrock water is transformed into goaf water. The long-term immersion of waterproof coal pillar by weak acid goaf water will lead to the attenuation of coal pillar strength, accelerate the creep of coal pillar and affect its stability, and even lead to the damage and stability of waterproof coal pillar, resulting in water inrush and collapse disasters, threatening the safety of adjacent mining face. It is necessary to evaluate the coal pillar width and long-term stability from the goaf water accumulation and coal creep characteristics. Based on this, this paper analyzes the reasonable width and long-term stability of waterproof coal pillar in Wangcun Coal Mine of Weibei Mining Area by means of experimental research, theoretical analysis and field measurement. The results show that :

(1) Through triaxial compression test and creep test analysis of coal samples taken from Wangcun Coal Mine, the compressive strength and cohesion of water-retaining coal samples are lower than those of natural coal samples under the same confining pressure, and the creep deformation increases. Water has obvious softening effect on the strength of coal and accelerates the creep of coal. Under the condition of high confining pressure, the strength of coal is lower, the deformation capacity is weaker, and the increase of confining pressure limits the deformation of surrounding rock to a certain extent, which is consistent with the anchoring mechanism of roadway surrounding rock.

(2) According to the theoretical analysis of elastic-plastic coal pillar zone width of in roadway excavation, it is found that the elastic core area in the middle of coal pillar is mainly related to the height of roadway and the peak coefficient of abutment pressure. The plastic fracture zone on both sides of the coal pillar is affected by the peak value of abutment pressure, coal strength and support force, but the influence range is different. The roof subsidence angle increases with the increase of the peak value of abutment pressure, and decreases with the increase of coal strength support force. Improving the anchorage strength of the side and controlling the roof subsidence can effectively inhibit the growth of the plastic.

(3)According to the theoretical analysis of the elastic-plastic zone width calculation of the coal seam coal pillar, the elastic zone width of the coal pillar is proportional to the water pressure. When the water pressure of the goaf side is too large, the width of the coal pillar core area should be timely drainage, which can effectively alleviate the water pressure of the goaf. The stress, strain and displacement of the plastic zone of the coal pillar change with time, and the plastic fracture zone continuously transfers like the center of the coal pillar. The creep increment of the width of the plastic zone in the goaf side is large, which verifies the weakening and accelerating creep of the coal body by water. The strain softening coefficient of coal has great influence on the initial value of plastic zone of coal pillar, and has little influence on the final creep stability. The increase of support force can effectively inhibit the creep of coal pillar.

(4) The theoretical setting width of tunneling roadway is smaller than that of coal seam mining, but its value is close to the initial value of plastic zone width of coal seam mining, which verifies the rationality of the two theories. The calculation of plastic zone width of roadway excavation provides a reference for the theoretical setting width of coal pillar. When the goaf water is small or the coal strength is large after mining, this theory can be directly used to calculate the setting width of coal pillar.

(5) Through the monitoring of the abutment pressure of coal pillar and the convergence of the sidewall and roof after the anchor cable reinforcement, it is found that the anchor cable reinforcement has achieved good results. The peak value of the abutment pressure of coal pillar is stable at about 4 m away from the coal wall, and the maximum convergence of the sidewall of coal pillar is 0.3 m, which further verifies the rationality of the theoretical formula and provides a theoretical reference for the coal pillar retention in the two cases.

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