【作者】 王涛；

【导师】 党发宁； 黄金廷；

【作者基本信息】 西安理工大学 ， 岩土工程（专业学位）， 2016， 硕士

【摘要】 随着国家轨道交通建设的发展,作为大城市中不可或缺的交通方式,地铁隧道在人口众多的综合性城市中越来越普及,特别是近些年伴随浅埋暗挖施工方法的日臻成熟。由于隧道开挖以及蠕变使洞周围岩的变形变的复杂,而二次衬砌作为隧道的安全储备,是隧道施工、运行安全以及运行寿命的首要保障,其合理的支护时机,就显得特别重要。因此,提出合理的二次衬砌支护时机势在必行,而且对类似隧道的施工具有重要的参考价值。本文以西安地铁二号线为工程背景,采用有限元软件ABAQUS进行隧道开挖模拟,对影响二次衬砌合理支护时机的因素进行总结,并分析各种影响因素下的结果,来判断各种情况下的二次衬砌合理支护时机。本文对隧道二次衬砌的支护时机主要进行了以下研究:(1)对目前国内外的研究方法与成果进行列举分析,并对黄土的蠕变机理以及蠕变理论进行了阐述。(2)根据黄土的蠕变特性,选取扩展的DRUCKER-PRAGER与蠕变耦合模型,基于围岩应力-应变时间曲线,确定了黄土的蠕变参数。(3)以西安地铁二号线为背景,对隧道进行二维开挖模拟,对隧道初衬厚度在200mm、250mm、300mm、350mm和400mm下,根据洞周位移、应力与时间曲线,依据“变形速率”准则和“极限位移”准则得出二次衬砌合理支护时机分别为7d、8d、16d、17d和19d。研究成果表明,初衬厚度的变化对二次衬砌支护时机的影响比较显著,初衬厚度愈大愈可以延迟二次衬砌的支护时机。(4)分别探究隧道初期支护强度在c15、c20、c25、c30和c35工况下的洞周位移、应力与时间关系,得出各工况二次衬砌合理支护时机分别为7.5d、8.3d、8d、13d和12d。研究成果表明,初期支护强度达到c30时对二次衬砌支护时机延缓较大,之后变化较小。(5)研究隧道埋深和不同洞间距变化对洞周位移、应力时间曲线的影响,得出这两种因素对二次衬砌的支护时机影响规律。研究成果表明,当隧道埋深较浅时,隧道埋深在一定范围内埋深越浅,二次衬砌的施做越可以延迟,但埋深增大到一定程度时,二次衬砌的支护时机基本相同。与埋深因素相比,洞间距的变化对二次衬砌支护时机的影响规律不是很明显。(6)基于初衬厚度、初期支护强度、埋深和洞间距中各工况所对应的二次衬砌支护时机,应用最小二乘法,对二次衬砌支护时机与初衬厚度、初期支护强度、埋深和洞间距之间建立回归方程。(7)建立三维数值计算模型,研究不同开挖进尺的拱顶位移与时间曲线,分析得出二次衬砌的合理支护时机。研究成果表明,开挖进尺对二次衬砌合理支护时机影响较小,在工程建设中可以忽略其的影响。更多还原

【Abstract】 With the development of the national rail transit construction,as an integral part of metropolitan transportation,subway tunnels populous city in general is becoming increasingly popular,especially in recent years along with maturity driving tunnel methods.Since the tunnel excavation and creep deformation around the hole to make rock becomes complicated,and the secondary lining as a safety reserve of the tunnel is the primary guarantee of tunnel construction,operational safety and operating life,which is reasonable support timing is particularly important.Therefore,a reasonable secondary liner supporting time is imperative,but also an important reference value for similar tunnel construction.Taking Xi’an Metro Line engineering background,using the finite element software ABAQUS simulation of tunnel excavation,the factors affecting the timing of the appropriate support secondary lining summarize,and analyze the results under a variety of factors to determine the various secondary lining in case of reasonable supporting time.In this paper,supporting time tunnel secondary lining mainly for the following studies:(1)The current research methods and results will be listed at home and abroad are analyzed,and the mechanism of creep and creep theory loess described.(2)According to the creep characteristics of loess,select the extended DRUCKER-PRAGER coupled creep model,based on surrounding rock stress-strain curves of time to determine the creep parameters of loess.(3)In the background of Xi’an metro line,two-dimensional simulation of excavation of the tunnel,the tunnel lining thickness at the beginning of 200mm、250mm、300mm、350mm and under 400 mm,according to hole displacement,stress and time curve,based on " deformation rate" guidelines and " limit displacement " reasonable guidelines drawn secondary lining supporting time was 7d、8d、16d、17d and 19 d.Research results show that the effect of changes in the thickness of the lining of the beginning of the second liner supporting time is more significant,the greater the thickness of the lining more early support can delay the timing of the secondary lining.(4)Respectively,to explore the Tunnel Lining strength c15 、 c20 、 c25 、 c30 and c35 displacement hole week working conditions,stress and time constraints,each obtained secondary lining conditions were reasonable opportunity to support 7.5d、8.3d、8d、13d and 12 d.Study results indicate that the strength of c30 initial support at the secondary liner supporting time delay is large,then small changes.(5)Effect research tunnel depth and different hole spacing changes Cave weeks displacement,stress-time curve,conclude that these two factors on the supporting influence of the timing of the secondary lining.Research shows that when the tunnel depth shallower depth of the tunnel within a certain range the more shallow depth,the secondary lining of the facilities to do can be delayed,but the depth increases to a certain extent,the secondary lining support substantially the same time.Compared with the depth factor,hole spacing variation influence of the secondary liner supporting time is not very obvious.(6)Based on early lining thickness,initial support strength,depth and spacing of holes in each operating mode corresponding to the secondary liner supporting time,least squares method,the secondary liner supporting time and the beginning of lining thickness,initial The regression equation between the supporting strength,depth and hole spacing.(7)The establishment of a three-dimensional numerical models to study different footage of the excavation crown displacement versus time curve analysis reveals that a reasonable opportunity to support secondary lining.Research shows footage of the excavation secondary lining reasonable opportunity to support smaller impact can be ignored in the construction of its impact.更多还原