预应力长锚索对毛羽山隧道大变形控制效果研究

发布时间：2018-06-02 21:28

本文选题：预应力锚索 + 高地应力　；参考：《兰州交通大学》2014年硕士论文

【摘要】：毛羽山隧道为软弱围岩且埋深较大，并处于极高地应力环境下，且松动圈范围较大，普通的锚杆长度不足以穿越松动区锚固到稳定岩体中，这使得传统的锚喷支护不能充分发挥作用，严重影响施工进度并存在较大的安全隐患。针对上述的特点，选用预应力长锚索配合锚喷混凝土的支护结构来测试对大变形的改善情况。本文以兰渝铁路毛羽山隧道的预应力长锚索试验段为背景，围绕锚索对大变形的控制情况展开下列研究。（1）在隧道12m和18m长锚索试验段中各选一个监测断面作为研究对象，分别从围岩变形、围岩压力、接触压力和锚索受力等四个方面进行研究分析，得到了围岩的变形和应力应变的规律，以及二次衬砌受力情况。（2）采用FLAC3D软件对12m和18m长锚索试验段，以及将12m长锚索布设在18m长锚索位置处的换布设位置段的隧道施工过程进行数值模拟，分析得出隧道变形、围岩应力和接触应力随施工空间变化的规律。（3）通过毛羽山隧道预应力长锚索试验段现场实测变形、围岩压力和初支与二次衬砌接触压力与数值模拟中的结果比较分析，综合评选变形控制效果，选择最优的锚索施作方案。主要研究成果：（1）预应力长锚索是一种“主动”的支护形式，对围岩的变形能更容易控制，且12m和18m的锚索长度都可以穿过6m左右的围岩表层松动区范围，将表层松动的岩块锚固到深层未扰动的稳定岩体中，充分利用未扰动体的稳定性加固隧道洞室。（2）通过对现场围岩位移和应力值分析，得出预应力长锚索试验段隧道的变形和应力规律：各测点的位移量、围岩压力、接触压力的测量值受隧道三台阶施工工序的影响较大，有较长时间波动，其增大期较长，累积总量大，且还出现左右不对称的情况。12m长锚索试验段监控断面的拱顶累积沉降量为371mm，上台阶收敛值为438mm，中台阶收敛值为347mm，下台阶收敛值为269mm；18m长锚索试验段监控断面的拱顶累积沉降量为296mm，上台阶收敛值为387mm，中台阶收敛值为340mm，下台阶收敛值为279mm。当在预应力锚索施作后，施作部位的控制变形效果较明显，可以减小累积变形量，，且能有效的减小二次衬砌的受力情况。（3）通过12m和18m两个长锚索试验段及换布设位置段的三维数值模拟对比分析得出，12m长锚索试验段的支护结构在中台阶和下台阶收敛值比18m长锚索试验段约减小30%；18m长锚索试验段在拱顶沉降方面比12m长锚索试验段减小约15%，在上台阶水平收敛控制上减小约20%；换布设位置段在拱顶沉降控制方面比18m长锚索试验段略差5%。18m长锚索试验段的预应力锚索布设形式对上拱部的变形、围岩y应力和接触应力都有较好地控制，换布设位置段控制效果略差于18m长锚索试验段控制效果；12m长锚索试验段的支护结构对墙中范围控制效果较好。
[Abstract]:The Maoyu Mountain Tunnel is a weak surrounding rock with a large buried depth and is in the extremely high ground stress environment, and the loosening circle is large. The common anchor rod length is not enough to be anchored to the stable rock mass through the loose zone. This makes the traditional bolting and shotcrete support can not play a full role, seriously affect the progress of construction and there are larger safety risks. According to the above characteristics, the support structure of prestressed long anchor cable combined with shotcrete is selected to test the improvement of large deformation. Based on the test section of long prestressed Anchorage cable in Maoyushan Tunnel of Lanyu Railway, the following research is carried out around the control of large deformation of anchor cable. 1) in the 12m and 18m long cable test section of the tunnel, a monitoring section is chosen as the research object, and the deformation of surrounding rock, the pressure of surrounding rock, the contact pressure and the force of anchor cable are studied and analyzed, respectively, from four aspects: deformation of surrounding rock, pressure of surrounding rock, contact pressure and force of anchor cable. The law of deformation, stress and strain of surrounding rock and the stress of secondary lining are obtained. FLAC3D software is used to simulate the tunnel construction process of 12m and 18m long cable test section, and the section of 12m long anchor cable placed at the position of 18m long anchor cable, and the tunnel deformation is obtained by numerical simulation. The variation of surrounding rock stress and contact stress with construction space. 3) through the field measurement of deformation, the pressure of surrounding rock, the contact pressure between initial support and secondary lining and the numerical simulation results in the test section of long prestressed Anchorage cable in Maoyushan Tunnel, the optimal anchoring cable construction scheme is selected by synthetically selecting the effect of deformation control. Main findings: 1) Prestressed long anchor cable is a kind of "active" supporting form, which can easily control the deformation of surrounding rock, and the length of 12m and 18m Anchorage cable can pass through the loose zone of surrounding rock surface layer about 6m. The surface loose rock block is anchored to the deep undisturbed stable rock mass, and the stability of the undisturbed rock mass is fully utilized to reinforce the tunnel cavern. 2) by analyzing the displacement and stress of surrounding rock on site, the deformation and stress law of the tunnel in the test section of prestressed long anchor cable is obtained. The displacement of each measuring point, the pressure of surrounding rock and the measured value of contact pressure are greatly affected by the construction procedure of the three steps of the tunnel. There is a long period of fluctuation, and its increasing period is longer, and the accumulative total amount is large. The cumulative settlement of the monitoring section of the 12m long anchor cable test section is 371mm, the convergence value of the upper step is 438mm, the convergence value of the middle step is 347mm, and the convergence value of the lower step is 269mm / 18m long anchor cable test section. The cumulative settlement is 296mm, the convergence value of the upper step is 387mm, the convergence value of the middle step is 340mm, and the convergence value of the lower step is 279mm. When the prestressed anchor cable is applied, the effect of controlling deformation is obvious, which can reduce the amount of accumulated deformation and reduce the stress of secondary lining. Through the comparative analysis of 3D numerical simulation of the test section of 12m and 18m long anchor cable and the section of changing the position of anchor cable, it is concluded that the convergence value of the supporting structure of the test section of 12m long anchor cable is 30 ~ 18m shorter than that of the test section of 18m long anchor cable compared with that of the test section of 18m long anchor cable. The test section of anchor cable is about 15 less than that of 12m long cable test section in the settlement of arch roof, about 20 parts in horizontal convergence control of upper steps, and 5. 18 m long anchor cable test section is slightly less than 18 m long anchor cable test section in settlement control of arch roof in replacement position section The deformation of the upper arch in the form of the prestressed anchor cable in the section, Y stress and contact stress of surrounding rock are well controlled, and the control effect of changing position section is slightly worse than that of 18m long anchor cable test section. The supporting structure with 12m long anchor cable test section has better control effect on the scope of wall.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U451.2

【参考文献】