高强度开采综放工作面区段煤柱合理宽度与控制技术

针对高强度开采综放工作面区段煤柱合理宽度留设问题,以羊场湾煤矿为工程背景,建立了综放工作面侧向基本顶破断结构模型,推导出低应力区范围表达式及其影响因素;采用FLAC3D数值模拟软件分析巷道掘进和本工作面回采期间不同煤柱宽度下巷道围岩应力与位移演化特征。研究表明:(1)高强度开采综放工作面因采场尺寸大、推进速度快、断裂步距大,导致内应力场范围亦大于常规工作面。(2)高强度开采综放工作面区段煤柱宽度的确定,应充分考虑多次剧烈采动、基本顶破断、巷道大断面等因素,结合试验工作面地质生产条件确定内应力场范围6.31~7.58 m,合理煤柱宽度为9~14 m。(3)本工作面回采期间,覆岩结构被再次激活,致使围岩变形破坏加剧,煤柱宽度10~14 m时,煤柱具有一定自稳能力并承担较少的顶板载荷,综合考虑各因素确定合理煤柱宽度为10 m。(4)受高强度开采及基本顶破断等因素影响,窄煤柱沿空巷道可能诱发大范围破碎、煤柱帮大变形及顶板不对称下沉等变形破坏,要实现此类巷道围岩稳定性控制应对煤柱帮和顶板重点加固,据此,提出了非对称围岩控制技术,并进行现场应用,巷道控制效果明显。

Reasonable width and control technique of segment coal pillar with high-intensity fully-mechanized caving mining

In order to investigate the problem of reasonable pillar width with high-intensity fully mechanized caving mining，taking Yangchangwan coal mine as an engineering background，the breakage structural model of lateral main roof of fully-mechanized caving mining was established and the width of low stress field and its influencing factors were derived.Also，the stress and deformation evolution laws of surrounding rock with different widths of coal pillar during the excavation and mining were analyzed by using FLAC3D.The results show that ① Due to large-size in working face，high advance speed and long caving interval，the width of internal stress field in high-intensity mining face is larger than that in ordinary coalface.② The factors such as multiple times mining influences，main roof fracture and large cross-section should be considered in determining the reasonable width of segment pillar.Combining with geological conditions of the test site，the width of internal stress field is calculated to be 6.31-7.58 m and the reasonable pillar width is 9-14 m.③ The strata structure is activated again during the retreat of mining face，which deteriorates the deformation and failure of surrounding rock.The overall displacement of surrounding rock is smaller when the pillar width is 10-14 m and the reasonable pillar width is determined as 10 m by considering comprehensively.④ The gob-side entry with small pillar may induce large-area broken，large deformation of coal pillar sides and asymmetric subsidence of roof.To achieve the stability control to similar roadway，the key control strategy is to reinforce pillar and roof.Afterward，the asymmetric control technology of surrounding rock was proposed and applied in field test.The surrounding rock deformation of gob-side entry was effectively controlled.