柔模混凝土沿空留巷技术已应用多年,在中厚煤层和薄煤层开采下均取得了较好的支护效果,但在厚煤层大采高工作面,因巷道高、巷旁支护压力大、混凝土早期强度低易受压损坏难以有效支撑顶板。大采高工作面矿压显现剧烈,巷旁维护难度大,故此提出一种新型的预浇墙柔模混凝土沿空留墙掘巷新技术,即在上工作面回采前,刷煤扩帮后提前预浇柔模混凝土墙体,提高煤帮整体支撑力的同时,解决柔模混凝土墙短期无法有效承载顶板来压的难题;待回采一定距离后,再沿墙滞后掘进下工作面回采巷道,且掘进方向与上工作面回采方向一致,缓解接续紧张,最终实现无煤柱开采。以王庄煤业3503工作面回采留设预浇墙为工程背景,建立了沿空留墙掘巷围岩结构力学模型,理论计算得出墙体力学支护参数,并通过现场应用验证了该技术的可实施性。结果表明:理论计算分析确定了墙体高宽比为5m×1.5m,混凝土强度C30即可满足留墙支护要求;沿墙掘进巷道总体变形量小,顶底板和两帮最大移近量仅为260mm和125mm,墙体最大受压18MPa,小于墙体自身承载力;下工作面临近巷道掘进115m后即趋于稳定。该技术应用全阶段效果良好,满足巷道使用要求,有效解决了大采高工作面沿空留巷重大技术难题,也可为相似工况无煤柱开采提供技术借鉴。

The technology of retaining roadway along goaf with flexible formwork concrete has beenused in China for many years. In the medium-thickness coal seam and thin coal seam mining it has achieved better support effect, but in the thick coal seam working face with large mining height, it is difficult to support the roof effectively because of the high roadway, high pressure of the roadway side support, and the low strength of the concrete in the early stage is easy to be damaged by the pressure. Inaddition, the mine pressure in the large mining height face is severe, and it is difficult to maintain theroadway, so a new technology of driving roadway along goaf with flexible form of concrete pre-cast wallis put forward. Before the mining of the last working face, the flexible formwork wall of concrete ispoured in advance after brushing coal to expand the slope, so as to improve the overall supporting forceof the coal side, and at the same time, to solve the problem that the flexible formwork concrete wall cannot effectively bear the roof pressure in a short period of time. After mining a certain distance, then lagging along the wall is propased to dig the lower working face back to mining roadway, and the directionof digging and in the upper working face back remains the same, to alleviate the succession of tensionand ultimately to achieve no coal pillar mining. This paper takes Wangzhuang Coal Industry 3503 working face back mining leaving pre-cast wall as the engineering example. In this paper, the mechanicalmodel of surrounding rock structure of roadway driving along goaf retaining wall is established, the wallmechanical support parameters are calculated theoretically, and the implementability of this technologyis verified by field application. The results show that: the theoretical calculation and analysis determinethe wall height and width ratio of 5 m × 1. 5 m, and the concrete strength of C30 can meet the requirements of retaining wall support. The overall deformation of the roadway driven along the wall is small,the maximum displacement of the roof and floor and the two sides is only 260 mm and 125 mm, and themaximum compression 18 MPa of the wall is less than the bearing capacity of the wall itself. The lowerworking face is stabilised after 115 m of tunneling near the roadway. The application of this technologyhas a good effect in the whole stage, possible to meet the requirements of roadway use, and effectivelysolves the major technical problems of retaining roadway along goaf in large mining height face. It canprovide a technical reference for coal pillar mining without coal pillar in similar conditions.