【摘要】：本文以國內某隧洞工程為實例，針對該隧洞凍結施工段擬定聯(lián)合支護措施，著重分析施工過程中和解凍后隧洞圍巖穩(wěn)定及支護受力規(guī)律，對支護結構在長期運行條件下的穩(wěn)定安全性進行校核分析評價并提出優(yōu)化或者加強建議。 本文采用三維有限元方法模擬各種加固方式(內襯混凝土、鋼筋網(wǎng)、鋼支撐、環(huán)向鋼筋、縱向鋼筋等)，并采用接觸單元模擬了管片與管片之間以及管片與豆礫石墊層之間的相互作用，考慮可能出現(xiàn)的不同計算條件，對擬定的兩種聯(lián)合支護方案進行結構分析并對多種加強方案進行了分析比選。 研究成果包括： （1）對于現(xiàn)有支護方案一，在極端校核荷載條件和疏松砂巖地勘參數(shù)下，不能夠保證工程運行安全的要求，需要采取有效注漿等措施提高洞周疏松砂巖彈性模量至100MPa左右，同時加密鋼拱架間距為40cm，，以保證長期運行下支護結構的安全。在實測土水壓力1.1MPa作為設計荷載的條件下，原疏松砂巖彈性模量對支護結構受力影響較大，取上限值60MPa時方案一能夠滿足隧洞穩(wěn)定及支護結構安全要求；而取下限值30MPa時支護結構并不具有設計安全裕度，存在較大風險。建議加密鋼拱架間距為40cm，同時建議施工中做好排水措施，有效降低洞周土水壓力。 （2）對于現(xiàn)有方案二，在極端校核荷載條件和疏松砂巖地勘參數(shù)下，并不能保證滿足工程運行安全的要求，而在實測土水壓力1.1MPa作為設計荷載的條件下，若疏松砂巖彈模在考慮擾動的地勘參數(shù)（20~60MPa）范圍內取值，方案二均基本能夠滿足要求。對疏松砂巖彈性模量的敏度分析結果表明，校核條件下需采用注漿措施提高洞周疏松砂巖彈性模量（建議提高至100MPa左右）等力學指標，并建議采用40cm間距的高強度鋼拱架。同時建議施工中做好排水措施，有效降低洞周土水壓力。 （4）對比現(xiàn)有兩個方案，在疏松砂巖彈性模量取地勘參數(shù)下限值30MPa和1.1MPa實測水土壓力下，方案二基本能夠滿足工程要求而方案一不能滿足要求，但在極端荷載條件下兩種方案均需要加強�？紤]到現(xiàn)有方案二較現(xiàn)有方案一在施工中需進行隧洞擴挖，可能不利于工程投資和工期方面的要求，推薦在現(xiàn)有方案一的基礎上進行加強支護方案的設計。
[Abstract]:Taking a domestic tunnel project as an example, this paper draws up combined support measures for the frozen construction section of the tunnel, and emphatically analyzes the stability of surrounding rock and the force law of support during construction and after thawing. The stability and safety of the supporting structure under the condition of long term operation are checked, analyzed and evaluated, and suggestions for optimization or strengthening are put forward. In this paper, three dimensional finite element method is used to simulate various reinforcement methods (lining concrete, steel mesh, steel bracing, circumferential steel bar, longitudinal steel bar, etc.). The interaction between segment and pea gravel cushion was simulated by contact element, and different calculation conditions were considered. The structural analysis of two kinds of combined support schemes and the comparison of various strengthening schemes are carried out. The research results include: (1) for the existing support scheme one, under the extreme check load condition and the loose sandstone geological prospecting parameter, can not guarantee the engineering operation safety request, Measures such as effective grouting should be taken to increase elastic modulus of loose sandstone around the hole to about 100MPa and the spacing of infilled steel arch frame is 40 cm in order to ensure the safety of supporting structure under long-term operation. Under the condition of measured soil water pressure (1.1MPa) as design load, the elastic modulus of loose sandstone has a great influence on the stress of supporting structure. When the upper limit value of 60MPa is taken, scheme one can meet the requirements of tunnel stability and support structure safety. However, the support structure does not have the design safety margin when the limit 30MPa is taken, so there is a great risk. It is suggested that the distance between the infilled steel arches is 40 cm, and that drainage measures should be done in construction to effectively reduce the pressure of surrounding soil water. (2) for the existing scheme two, under extreme check load conditions and loose sandstone geological prospecting parameters, it can not meet the requirements of engineering operation safety, but under the condition that the measured soil and water pressure (1.1MPa) is used as design load, If the elastic modulus of loose sandstone is obtained in the range of geological prospecting parameters (20~60MPa) considering disturbance, the second scheme can basically meet the requirements. The results of sensitivity analysis on elastic modulus of loose sandstone show that grouting should be used to improve elastic modulus of loose sandstone around the hole (about 100MPa) under checking condition, and high strength steel arch frame with 40cm spacing should be used. At the same time, it is suggested that drainage measures should be done well in construction to effectively reduce the pressure of soil water around the tunnel. (4) compared with the existing two schemes, under the condition that the elastic modulus of loose sandstone is measured under the lower limit values of geological prospecting parameters 30MPa and 1.1MPa, the second scheme can basically meet the engineering requirements, while the first scheme can not meet the requirements. However, both schemes need to be strengthened under extreme loads. Considering that the existing scheme two needs tunnel expansion and excavation compared with the existing scheme 1, it may be unfavorable to the requirements of project investment and construction period. It is recommended that the design of strengthening support scheme should be carried out on the basis of the existing scheme 1.
【學位授予單位】：天津大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TV672;TV554

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