【摘要】：地鐵建設(shè)在促進城市快速發(fā)展中占有重要地位,城市地下管線是保證城市正常運行的基礎(chǔ)設(shè)施,管變形破壞會影響城市地鐵隧道的施工和正常運營。因此,在地鐵隧道施工過程中,確保既有管線的安全至關(guān)重要。本文以西安地鐵4號線某暗挖隧道穿越既有地下管線工程為依托,采用理論分析、現(xiàn)場監(jiān)測和數(shù)值模擬相結(jié)合的手段,對暗挖隧道穿越既有管線的地表及管線變形規(guī)律及管線變形控制措施進行研究。主要內(nèi)容及結(jié)論有:(1)提出了影響既有管線變形的主要因素,研究了暗挖隧道施工誘發(fā)鄰近管線變形的規(guī)律,分析了不同類型管線的變形特性。(2)采用FLAC~(3D)軟件對黃土地區(qū)影響管線變形的各類因素進行了研究,并根據(jù)模擬結(jié)果得出了地層沉降槽寬度、最大沉降量與管線沉降槽寬度及沉降量之間的函數(shù)關(guān)系,計算了各種工況下的管線沉降槽曲線、管線最大轉(zhuǎn)角、附加彎矩及剪力。結(jié)論指出:(1)影響西安城區(qū)場地差異的土層主要為新黃土;(2)因隧道施工工法不同而引起的管線沉降量由大到小為:上下臺階法≥正臺階預(yù)留核心土法≥短臺階+臨時仰拱法≥CD法≥CRD法;(3)管材對管線變形的影響主要是因為材料剛度的不同,管線與下臥土層間會出現(xiàn)管土分離的情況,此時管線上方土體的壓力使得管線對其產(chǎn)生反作用,增大管線在接口處產(chǎn)生剪切破壞的可能性;(4)管徑越大,管線沉降越小,但其所受附加應(yīng)力卻越大;(5)與隧道垂直和平行的管線最大沉降值相差不大,但垂直工況管線受附加彎矩和剪力更大,更易破壞;(6)經(jīng)計算可知,埋深≤2m的管線,其轉(zhuǎn)角、所受彎矩和剪力均小于控制標準,在實際工程中,若埋深≤2m且無特殊狀況的管線可不予考慮;(7)與隧道平行的管線,當(dāng)管線距離隧道正上方水平距離≥1.5D時,管線沉降很小,若無特殊情況,則無需采取保護措施。(3)采用FLAC~(3D)軟件對實際工程中地鐵隧道暗挖施工誘發(fā)的既有管線的受力變形進行預(yù)測,數(shù)值模擬及理論計算結(jié)果表明:管線沉降主要集中在-1.5~1.5D的穿越過程中;實測結(jié)果與模擬及計算結(jié)果近似;在采用了短臺階+臨時仰拱法進行隧道開挖后,施工引起的管線變形量滿足規(guī)范要求,相關(guān)結(jié)論及控制措施可以為類似工程提供參考。
[Abstract]:Subway construction plays an important role in promoting the rapid development of the city. Urban underground pipeline is the infrastructure to ensure the normal operation of the city. Pipe deformation and failure will affect the construction and normal operation of urban subway tunnel. Therefore, it is very important to ensure the safety of existing pipelines in subway tunnel construction. Based on the underground pipeline project of a hidden tunnel in Xi'an Metro Line 4, this paper adopts the method of combining theoretical analysis, on-site monitoring and numerical simulation. The deformation law of surface and pipeline and the control measures of pipeline deformation are studied. The main contents and conclusions are as follows: (1) the main factors affecting the deformation of the existing pipeline are put forward, and the law of the deformation of the adjacent pipelines induced by the tunneling construction is studied. The deformation characteristics of different types of pipelines are analyzed. (2) various factors affecting pipeline deformation in loess area are studied by FLAC~ (3D) software, and the width of settlement trough is obtained according to the simulation results. The function relationship between the maximum settlement and the width and settlement of the channel is calculated. The curves of the channel, the maximum angle of the pipeline, the additional bending moment and the shear force are calculated. The conclusions are as follows: (1) New loess is the main soil layer that affects the site difference in Xi'an urban area; (2) the settlement amount of pipeline caused by different tunnel construction methods is as follows: upper and lower step method 鈮，

本文編號：2388147