| 深埋公路隧道溶洞处置效果分析与隧道结构响应规律研究 |
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| 引用本文： | 崔炫,胡强.深埋公路隧道溶洞处置效果分析与隧道结构响应规律研究[J].中国岩溶,2022,41(1):34-46. |
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| 作者姓名： | 崔炫 胡强 |
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| 作者单位： | 贵州省交通规划勘察设计研究院股份有限公司，贵州 贵阳550008 |
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| 摘 要： | 卡罗Ⅱ号隧道为贵州省平塘至罗甸高速公路控制工程，施工时揭示溶洞发育于右幅隧道的拱底部位，左右线隧道中部岩柱薄易于坍塌，特提出洞渣回填以及桥梁跨越两种处置手段并在技术及经济方面进行比选，综合确定洞渣回填为该溶洞处理方式。为验证回填方案的合理性，以有限元软件Midas GTS建立溶洞回填前后隧道开挖施工模型，分析出溶洞处理前后围岩位移、锚杆轴力以及围岩塑性区变化规律，同时监测典型断面的累计拱顶沉降、收敛变形情况，结果表明:溶洞回填后，围岩位移、锚杆轴力峰值有较大降低，中部岩柱以及下部溶腔塑性区发展由于回填得以控制，溶洞回填可有效抑制围岩变形，施工期间也并未出现突泥、涌水灾害事故，其回填方案有较高的可行性。
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| 关 键 词： | 公路隧道 小净距 数值计算 溶洞回填 桥梁跨越 优化分析 结构响应规律 |
| 收稿时间： | 2020-12-17 |
Research on treatment effect of karst cave in deep-buried highway tunnel and response law of tunnel structure |
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| Institution: | Guizhou Transportation Planning Survey &Design Academe Co.， Ltd.，Guiyang， Guizhou550008，China |
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| Abstract: | Karst landform has brought great hidden dangers to the construction and operation of transportation infrastructure. In order to eliminate the risk of covered karst to tunnel construction and operation， two methods of tunnel slag backfilling and bridge crossing have been proposed for the treatment of covered karst cave exposed during construction in the engineering background of Pingluo Tunnel II of Pingtang-Luodian Expressway in Guizhou Province. After the comprehensive comparison of the two methods in terms of technology and economy， tunnel slag backfilling is decided as the optimal treatment method of the karst cave. To verify its rationality， a three-dimensional model under two conditions before and after treatment of karst cave was established by using finite element software Midas GTS. The treatment effect of backfilling of karst cave quantitatively was evaluated from four perspectives: displacement of surrounding rock， internal force of support structure， distribution characteristics of plastic zone of surrounding rock and its equivalent stress. The results show that the displacement peak value of surrounding rock decreased by 32.6% from -4.671 mm before the treatment to -3.148 mm after the treatment. Furthermore， after karst cave treatment， the peak value of settlement of left tunnel arch and of right tunnel arch respectively decreased 0.567 mm （by 15.6%） and 0.503 mm （by 21%）. Before and after the treatment， anchors in tunnel system were mainly tensioned， and few of them were under pressure. System anchors could effectively play their suspension role. The stress data of system anchor show that the peak value of system anchor force decreased by 32.6% from 35.37 kN to 32.48 kN after the backfilling of karst cave. Distribution characteristics of plastic zone of surrounding rocks are able to reflect the scope of loosening and destruction of surrounding rocks. Before the karst tunnel was filled and treated， excavation of the right tunnel had caused great disturbance to surrounding rocks below the arch shoulder of the tunnel and on both sides of the karst tunnel， especially to the left side of the karst tunnel and the right side of the tunnel. The surrounding rocks were basically in the state of plastic loosening. After the treatment with filling， the plastic zone of surrounding rock was only distributed in the range of side walls on both sides of the left and right tunnel， and the original cavity zone on the lower side of tunnel lining structure also changed from plastic loose zone to elastic zone. It indicates that the backfilling of karst cave can effectively limit the downward development of plastic zone of surrounding rocks and significantly improve the safety of rock pillars in tunnel. To verify the rationality of distribution characteristics of tunnel plastic zone， Von-Mises equivalent stresses at different parts of tunnel structure on left and right lines were extracted for analysis. The data shows that the equivalent stresses at right arch waist of the right line tunnel and 10 m below the right wall of the tunnel can be effectively reduced after the backfilling of the karst tunnel. The equivalent stresses of surrounding rocks at the two locations were reduced by 72.5% and 88.4%， respectively. The accumulated displacement values of YK16+595 section vault and camber of right-line tunnel do not exceed the standard warning values， and no mud burst， or water inrush accidents have occurred since the karst cave was exposed in 2016. Therefore， the higher feasibility of backfilling scheme has been verified，and the relevant achievements can provide new ideas for the treatment of karst tunnel in deep-buried highway with short clear distance. |
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