發(fā)布時間：2018-11-21 17:07

【摘要】：隧道施工中,由地表坡度引起的淺埋隧道偏壓現(xiàn)象,使得隧道在開挖過程中,支護結構受力及變形不對稱,嚴重時會引起塌方、冒頂?shù)葹暮ΜF(xiàn)象,影響隧道圍巖的穩(wěn)定性。本文以婁邵鐵路改擴建工程陳家灣隧道為工程背景,采用強度折減法結合突變理論,對軟弱圍巖淺埋偏壓隧道穩(wěn)定性等問題進行分析研究。根據(jù)陳家灣隧道現(xiàn)場量測數(shù)據(jù),采用BMP系統(tǒng),對隧道圍巖物理參數(shù)進行反演,并參考現(xiàn)行鐵路隧道設計規(guī)范,綜合確定隧道圍巖物理參數(shù)。以所得圍巖物理參數(shù),采用有限元強度折減法進行數(shù)值模擬,分析圍巖塑性區(qū)隨強度折減系數(shù)的變化趨勢,找到圍巖潛在破壞面,結合突變理論,給出洞周典型位置的臨界折減系數(shù)及位移值。分析結果表明,軟弱圍巖淺埋偏壓隧道的潛在破壞面與現(xiàn)行鐵路、公路規(guī)范中所假定的破壞面形式不同,圍巖破壞形式不僅僅是從坡頂向坡底的整體滑動,淺埋側拱頂貫通至地表的塑性區(qū)也影響了支護結構的受力情況。對不同橫坡坡度及不同巖體性質條件下的淺埋偏壓隧道進行數(shù)值模擬,采用前述研究方法,分析不同橫坡坡度及巖體性質對圍巖穩(wěn)定性的影響,比較洞周典型位置的臨界折減系數(shù)。結果表明,隨著坡度的增大,圍巖潛在破壞面出現(xiàn)的時間越來越早,圍巖穩(wěn)定性降低;隨著圍巖等級的提高,潛在破壞面出現(xiàn)的時間越來越晚,甚至不出現(xiàn),圍巖穩(wěn)定性增加。采用數(shù)值模擬的方法對臺階高度及臺階長度進行工法參數(shù)優(yōu)化,通過比較不同臺階高度及長度對隧道結構變形、支護結構內力及圍巖塑性區(qū)的影響,綜合分析,確定合理的臺階高度及臺階長度。最后,從超前支護、地表沉降控制等方面,給出相應的施工改進措施,使其對相似工程具有借鑒意義。
[Abstract]:In the tunnel construction, the phenomenon of shallow tunnel bias caused by the slope of the surface causes the asymmetry of the force and deformation of the supporting structure in the course of excavation, which will cause disasters such as collapse and roof fall when serious, which will affect the stability of the surrounding rock of the tunnel. Based on the Chenjiawan tunnel of Loushao railway reconstruction project, this paper analyzes and studies the stability of shallow buried bias tunnel in weak surrounding rock by using strength reduction method combined with catastrophe theory. Based on the field measurement data of Chenjiawan Tunnel, the physical parameters of surrounding rock of the tunnel are inversed by BMP system, and the physical parameters of surrounding rock of the tunnel are determined synthetically with reference to the current design code of railway tunnel. Based on the physical parameters of surrounding rock, the finite element strength reduction method is used to simulate the plastic zone of surrounding rock. The change trend of plastic zone with strength reduction coefficient is analyzed, and the potential failure surface of surrounding rock is found, which is combined with catastrophe theory. The critical reduction coefficient and displacement value of typical position around the hole are given. The results show that the potential failure surface of shallow buried bias pressure tunnel with weak surrounding rock is different from that of the existing railway and highway code, and the failure form of surrounding rock is not only sliding from the top of the slope to the bottom of the slope. The plastic zone from the shallow arch roof to the surface also affects the stress of the supporting structure. Numerical simulation of shallow buried bias tunnel with different slope gradient and rock mass property is carried out. The influence of slope degree and rock mass property on the stability of surrounding rock is analyzed by using the above-mentioned research method. The critical reduction coefficient of typical position around the hole is compared. The results show that with the increase of slope, the potential failure surface of surrounding rock appears earlier and the stability of surrounding rock decreases, and with the increase of surrounding rock grade, the time of occurrence of potential failure surface becomes more and more late, or even does not appear, and the stability of surrounding rock increases. The method of numerical simulation is used to optimize the working parameters of step height and step length. By comparing the influence of different step height and length on the deformation of tunnel structure, the internal force of supporting structure and the plastic zone of surrounding rock, the comprehensive analysis is made. Determine the reasonable height and length of the steps. Finally, from the aspects of advance support, surface subsidence control and so on, the corresponding construction improvement measures are put forward, which can be used for reference for similar projects.
【學位授予單位】：石家莊鐵道大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U451.2;U455

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