木孔煤矿软弱围岩巷道支护技术研究

发布时间：2018-04-04 23:07

本文选题：软岩巷道　切入点：预应力桁架锚索　出处：《湖南科技大学》2015年硕士论文

【摘要】：本文以贵州木孔煤矿软岩巷道支护为工程背景,对+700运输顺槽的原支护方式失效的原因进行理论分析从而提出了以桁架锚索为核心的联合支护技术。木孔煤矿巷道顶板稳定性差,强度低,易风化和崩解,巷道采用锚杆锚索+钢带支护,由于参数设计不合理,支护强度不够,施工质量较差等造成顶板锚杆和托盘支护严重失效,钢带出现折断、扭曲等破坏现象。因为巷道开挖以前,地下岩体处于三轴应力平衡状态,巷道开挖后原有的平衡系统会被破坏,巷道围岩应力就会从新分布调整,变成二维应力状态,围岩强度变低。对于+700运输顺槽,由于巷道围岩强度低,同时受回采动压影响,巷道围岩产生变形破坏;另外由于巷道掘进后,不及时对支护施加预紧力或预紧力强度不够,巷道顶板只是自然的叠合梁,不能发挥组合梁的作用。尤其是在软岩巷道中,若不及时对锚杆、锚索施加一定量的预紧力,不能发挥其主动支护的作用,只有当顶板岩层变形到一定量时,才具有承载能力,此时巷道顶板已经离层和破坏,围岩自身承载能力大幅度降低。通过复变函数和弹性力学研究了矩形巷道围岩应力,以+700运输顺槽的工程地质资料为基础,建立FLAC数值模型,分析不同高宽比和侧压力系数下矩形巷道的变形情况,根据实际情况合理确定巷道尺寸。普通锚索相比于预应力桁架锚索,其影响的半径范围和轴线方向的深度较小,对围岩的应力状态改变较弱,因此提出桁架锚索支护技术。预应力桁架锚索由桁架连接器、高强度钢绞线、锚具、反扣装置等组成。可以有效的使中性轴趋近于巷道顶板上表面,减少巷道顶板岩梁拉应力区域,增大压应力区域,有效的改善围岩的应力状态,减少了锚固区岩梁因受拉应力作用而产生失稳、垮塌事故,提高了巷道顶板围岩整体的承载能力。预应力桁架锚索是将锚固点作用在巷道两肩窝深部围岩内形成类似倒楔体,通过张拉钢绞线将预应力传递到巷道顶板围岩中。当巷道围岩受到动压荷载影响时,倒“梯形体”卡在巷道顶板围岩两角处,上方压力越大,倒“梯形体”卡住越紧,在巷道顶板上方形成基点在两角处的承载拱区。预应力桁架锚索能够在水平和垂直方向同时对巷道顶板围岩提供压应力,使锚固区内的围岩处于双向应力状态。预应力桁架锚索产生的主动支护力能有效控制巷道顶板沿垂直方向向下移动,防止顶板离层。通过FLAC数值模拟的方法,研究+700运输顺槽预应力桁架锚索支护方案中不同桁架锚索长度、锚索直径、锚索和垂直方向的夹角、孔口和巷帮的距离、锚索的预应力以及顶板锚杆密度然后通过SPSS差分析正交试验,设计出+700运输顺槽预应力桁架锚索支护方案;最后通过对运输顺槽表面位移监测表明+700运输顺槽在预应力桁架锚索支护控制下,巷道围岩变形稳定,达到了预期效果。
[Abstract]:Based on the engineering background of soft rock roadway support in Mugong Coal Mine of Guizhou Province, this paper makes a theoretical analysis of the failure reasons of the original support mode of 700 transportation channel, and puts forward the combined support technology with truss anchor cable as the core.The roof of the roadway in Mugong coal mine is poor in stability, low in intensity, easy to weathering and collapsing, and the bolting cable steel belt is used in the roadway. Because of the unreasonable design of the parameters, the strength of the support is not enough.The poor construction quality results in serious failure of roof bolting and pallet support, breakage of steel strip, distortion and so on.Because the underground rock mass is in triaxial stress equilibrium state before tunnel excavation, the original equilibrium system will be destroyed after excavation, and the stress of surrounding rock will be adjusted from new distribution to two-dimensional stress state, and the strength of surrounding rock will become lower.For the 700 transportation along the channel, because of the low strength of surrounding rock of roadway and the influence of mining dynamic pressure, the surrounding rock of roadway is deformed and destroyed; in addition, the strength of pre-tightening force or pre-tightening force is not enough in time because of the failure to apply pre-tightening force or pre-tightening force to the support after roadway excavation.Roadway roof is only a natural composite beam, and can not play the role of composite beam.Especially in soft rock roadway, if a certain amount of pre-tightening force is not applied to the bolt and cable in time, it can not play the role of active support, and only when the roof rock is deformed to a certain amount, can it have the bearing capacity.At this time, the roof of roadway has been detached and destroyed, and the bearing capacity of surrounding rock itself has been greatly reduced.The stress of surrounding rock of rectangular roadway is studied by means of complex variable function and elastic mechanics. Based on the engineering geological data of 700 transports along the channel, the FLAC numerical model is established, and the deformation of rectangular roadway under different aspect ratio and lateral pressure coefficient is analyzed.According to the actual situation, reasonable determination of the tunnel size.Compared with prestressed truss anchor cable, the influence of common anchor cable on the radius and the depth of axis direction is smaller, and the stress state of surrounding rock is weaker, so the support technology of truss anchor cable is put forward.Prestressed truss Anchorage cable consists of truss connectors, high-strength steel strands, anchors, anti-buckling devices and so on.It can effectively make neutral axis approach the top surface of roadway roof, reduce tensile stress area of roof and slate beam of roadway, increase compressive stress area, effectively improve stress state of surrounding rock, and reduce instability of rock beam in Anchorage area due to tensile stress.Collapse accident improves the overall bearing capacity of roadway roof surrounding rock.The prestressed truss anchor cable acts on the anchor point in the deep surrounding rock of the two shoulder sockets of the roadway to form a similar inverted wedge, and the prestress is transferred to the surrounding rock of the roadway roof through the tensioning steel strands.When the surrounding rock of the roadway is affected by dynamic pressure, the inverted "trapezoid body" is stuck in the two corners of the roadway roof, the higher the pressure above the roadway is, the tighter the "trapezoidal body" is clamped, and the base point is formed in the bearing arch area at the two corners above the roof of the roadway.The prestressed truss Anchorage cable can provide compressive stress to the surrounding rock of roadway roof at the same time in both horizontal and vertical direction, which makes the surrounding rock in the Anchorage zone in the state of bidirectional stress.The active support force generated by prestressed truss anchor cable can effectively control the roadway roof moving down the vertical direction to prevent roof from leaving the layer.By means of FLAC numerical simulation, the length of different truss anchor cables, the diameter of anchor cables, the angle between anchor cables and vertical direction, the distance between the orifice and the side of the roadway are studied.The prestress of the anchor cable and the density of the roof anchor rod. Then through the orthogonal test of SPSS difference analysis, the anchor cable support scheme of the 700 transport pre-stressed truss along the channel is designed.Finally, through monitoring the surface displacement of the transport channel, it is shown that under the control of prestressed truss anchor cable support, the surrounding rock deformation of the roadway is stable and the expected effect is achieved.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD353

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