软岩反底拱优化加固技术及应用——以上海庙矿区为例

Research of optimal floor heave control technology and its engineering application in soft rock roadway

  • 摘要: 在西部软岩矿区,巷道底臌是一种常见的巷道破坏形式,由底臌所引起的围岩变形已成为阻碍矿井高效生产的主要难题,也是目前西部矿区亟待解决的关键问题。目前广泛使用的底臌控制方案为浇筑混凝土材料配合反底拱与锚杆支护技术联合控制巷道底臌。然而,分析现场破坏结果,浇筑反底拱的普通C20混凝土材料存在强度低、密实度差等明显缺陷,并不能有效控制底臌,巷道现场底角与两帮呈现大面积破坏。据此提出一种优化浇筑材料方案,提高其初凝时间和强度。优化混凝土浇筑材料治理方案是将生石灰按照不同配制比例掺入混凝土浆液中,制备试件;在不同龄期下测试不同生石灰掺入量的试件强度,进而选出最优配比方案;利用扫描电镜对浇筑材料的结构进行观察分析,确定优化后的浇筑材料满足反底拱结构中浇筑材料的性能要求。结果表明:在养护龄期内,材料最大单轴抗压强度为30.15 MPa,是普通C20混凝土材料强度的1.39倍,抗拉强度为1.75 MPa,是未掺入生石灰试件强度的1.41倍。利用扫描电镜观测分析,在生石灰掺量为10% 时,试件结构致密,浆体中的Ca(OH)2,AFt和孔隙数量明显减少,浇筑材料的力学性能有效提高。工程实践表明,采用优化后的浇筑材料进行反底拱设计,在50 d监测期内,最大底臌量仅为101 mm,巷道底臌量减少为原支护方案的34%,底臌控制效果明显。

     

    Abstract: In the soft rock mining area of western China,the floor heave is a kind of common form of soft roadway distortion and failure.The deformation of surrounding rock caused by floor heave has become a major problem that hinders the efficient mine production.It is also an urgent problem in the western mining area.At present,the widely used control scheme is to control the floor heave of roadway by pouring concrete material,inverse arch and bolt support.However,according to the on-site destruction results,the ordinary C20 concrete material with inverted bottom arch has defects such as low strength and poor compaction,and cannot effectively control the floor heave.The large-scale destruction of the bottom corner of roadway and its two walls reveal the shortcomings of the support scheme.Based on this,a scheme of optimizing the pouring material was proposed to improve its initial setting time and strength,the optimal treatment scheme of concrete pouring material was to mix quicklime into concrete slurry in different proportion.The strengths of the test pieces with different quicklime incorporation at different ages were tested,and then the optimal ratio scheme was selected.Scanning electron microscope was used to observe and analyze the structure of pouring material,and the optimized pouring material was determined to meet the performance requirements of the pouring material in the inverted arch structure.The optimized support scheme was optimized for the bottom corner of the roadway and the weak area of the two sides of the support to strengthen the support strength of the roadway,and control the floor heave by combining with the bottom arch.The results show that during the curing period,the maximum uniaxial compressive strength of the test piece is 30.15 MPa,which is 1.39 times the strength of the ordinary C20 concrete material,and the tensile strength is 1.75 MPa,which is 1.41 times the strength of the test piece not mixed with quicklime.Scanning electron microscope observation and analysis show that when the content of quicklime is 10%,the structure of the test piece is dense,the amount of Ca (OH)2,AFt and pores in the slurry is significantly reduced,and the mechanical properties of the casting material are effectively improved.Engineering practice shows that with the optimized pouring material the maximum bottom drum volume is only 101 mm during the 50-day monitoring period,and the roadway bottom heave volume is reduced to 34% of the original supporting scheme.The surrounding rock control effect is obvious.

     

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