本文選題：隧道開挖 + 群樁�。� 參考：《廣西大學(xué)》2015年碩士論文

【摘要】：由于地鐵隧道多修建在建筑結(jié)構(gòu)集中的市區(qū),并且城市建筑基礎(chǔ)大多采用樁基形式,則地鐵隧道施工會不可避免的接近或穿越既有建筑物,引起地層損失和地應(yīng)力變化,產(chǎn)生地面變形及樁基的附加軸力和附加彎矩,使樁基發(fā)生變形和產(chǎn)生沉降力,降低了周圍既有樁基的承載能力。本文在現(xiàn)有的研究基礎(chǔ)上,首先通過離心模型試驗分別研究了廣西南寧地區(qū)單隧道和雙隧道施工對既有群樁的影響,接著對離心試驗進行了數(shù)值分析,對二者的結(jié)果進行了相互驗證。然后,基于已經(jīng)驗證的數(shù)值模型進一步分析不同埋置深度的單隧道和雙隧道施工對臨近群樁的地表豎向位移、樁身附加變形、樁身附加彎矩和附加軸力的影響規(guī)律。通過研究可得到如下的結(jié)論：(1)隧道在不同埋深時開挖引起的地表豎向位移影響規(guī)律相似,地表沉降最大值在隧道中心的正上方取得；(2)隧道開挖過程中,樁頂沉降隨著隧道開挖的進行而逐漸增加,且隧道的分步開挖會導(dǎo)致承臺傾斜,從而引起樁基的內(nèi)力重分布；(3)當(dāng)隧道埋深大于等于群樁埋深時,隧道開挖引起的鄰近樁基受力形式表現(xiàn)為懸臂梁模式,當(dāng)隧道埋深小于群樁埋深時,隧道開挖引起的鄰近樁基受力形式表現(xiàn)為兩端鉸支的簡支梁模式。隧道埋深越深,群樁受隧道開挖的影響越�。�(4)雙隧道開挖完成后,無論隧道埋置的深淺,前樁的附加軸力均表現(xiàn)為正值,樁身軸力增加。隧道軸線埋深小于等于樁的埋深時,后樁的附加軸力均表現(xiàn)為正值,樁身軸力增加,隧道軸線埋深大于樁的埋深時,后樁所受到的附加軸力為負(fù)值,樁身軸力減少。本文研究成果可為廣西地區(qū)臨近建筑物隧道的設(shè)計和施工提供相應(yīng)的理論指導(dǎo),從而使其具有實際意義。
[Abstract]:Because the subway tunnel is built mostly in the urban area where the building structure is concentrated, and the urban building foundation is mostly in the form of pile foundation, the subway tunnel construction will inevitably approach or pass through the existing building, which will cause the ground loss and the change of ground stress. The deformation of the ground and the additional axial force and bending moment of the pile foundation result in the deformation and settlement of the pile foundation and reduce the bearing capacity of the existing pile foundation around the pile foundation. On the basis of existing research, the influence of single tunnel construction and double tunnel construction on existing pile groups in Nanning region of Guangxi is studied by centrifugal model test, and then the numerical analysis of centrifugal test is carried out. The results are verified by each other. Then, based on the verified numerical model, the effects of single and double tunnel construction with different buried depths on the surface vertical displacement, additional deformation of pile body, additional bending moment and additional axial force of pile body are further analyzed. The following conclusions can be drawn from the study: the vertical displacement caused by tunnel excavation at different burial depths is similar, and the maximum surface subsidence is obtained at the top of the tunnel center. The settlement of the pile top increases gradually with the excavation of the tunnel, and the gradual excavation of the tunnel will lead to the inclination of the pile cap, thus causing the redistribution of the internal force of the pile foundation. (3) when the buried depth of the tunnel is greater than or equal to the buried depth of the pile group, The stress form of adjacent pile foundation caused by tunnel excavation is cantilever beam mode. When the buried depth of tunnel is less than that of pile group, the force form of adjacent pile foundation caused by tunnel excavation is simply supported beam mode with two ends hinged. The deeper the tunnel is, the less the pile group is affected by the tunnel excavation. After the double tunnel excavation is completed, no matter the depth of the tunnel is shallow, the additional axial force of the front pile is positive, and the axial force of the pile body increases. When the buried depth of the tunnel axis is less than or equal to that of the pile, the additional axial force of the rear pile is positive, and the axial force of the pile body increases. When the buried depth of the tunnel axis line is greater than the buried depth of the pile, the additional axial force of the rear pile is negative and the axial force of the pile body decreases. The research results of this paper can provide corresponding theoretical guidance for the design and construction of adjacent building tunnels in Guangxi area, thus making it of practical significance.
【學(xué)位授予單位】：廣西大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU473.1;U456.3

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