【摘要】：摘要：隨著經(jīng)濟(jì)發(fā)展和城市化進(jìn)程的不斷加快,城市地下軌道交通開始大量修建以緩解日益擁堵的地上交通,由于地鐵一般沿城市的主干路修建,會不可避免的穿越橋梁的基礎(chǔ),使其產(chǎn)生位移并產(chǎn)生內(nèi)力的重分布,影響結(jié)構(gòu)的正常使用。本文以北京地鐵10號線所穿越橋梁為主要工程背景,利用有限元方法來模擬不同工程地質(zhì)條件、樁基形式、樁與隧道位置關(guān)系、隧道施工控制條件時隧道開挖穿越樁基礎(chǔ)后,對樁身位移和受力特性的影響,得出主要結(jié)論如下： 1)樁沉降值隨土體壓縮性、泊松比、抗剪強(qiáng)度、樁與隧道距離的增大而減小,樁基嵌入深度大于隧道埋深時,沉降值隨樁長增大而減小,兩樁承臺基礎(chǔ)樁間沉降差和承臺傾斜率減小。粉土層中隧道下穿單樁,樁位于隧道開挖面正上方附近時產(chǎn)生背離隧道方向傾斜,樁與隧道距離大于5m時產(chǎn)生向隧道方向傾斜,位于隧道軸線正上方時不產(chǎn)生傾斜；隧道側(cè)穿后,水平位移沿樁深非線性分布,樁產(chǎn)生彎曲,土體抗剪強(qiáng)度越弱,彎曲變形越大,土體泊松比增大,樁彎曲方向由與隧道襯砌相同變?yōu)橄喾础蓸冻信_基礎(chǔ)樁頂處傾斜方向與承臺相同。 2)樁位于隧道結(jié)構(gòu)正上方時,樁軸力減小,位于隧道結(jié)構(gòu)側(cè)上方時,軸力增大,影響程度隨樁與隧道距離增大而減小,受土體抗剪強(qiáng)度、壓縮性、泊松比變化影響較小。兩樁承臺基礎(chǔ)中近隧道樁承受荷載減小,該部分荷載由遠(yuǎn)隧道樁承擔(dān),影響程度隨樁嵌入深度增加而減小。 3)隧道下穿單樁后樁身承受附加彎矩較小,側(cè)穿使樁承受較大彎矩,最大值一般位于與隧道軸線相同標(biāo)高處,與樁和隧道距離有關(guān),粉土層中其值為6m時最大,樁身近隧道側(cè)正應(yīng)力增大、遠(yuǎn)隧道側(cè)減小,對樁深與隧道軸線同標(biāo)高處正應(yīng)力影響最大。附加正彎矩值和正應(yīng)力變化量隨土體泊松比、抗剪強(qiáng)度的增大而減小。兩樁承臺基礎(chǔ)近隧道樁頂由于承臺的連接作用承受較大的附加彎矩作用,該處遠(yuǎn)隧道側(cè)混凝土承受拉應(yīng)力作用。 4)地表沉降值與樁身沉降和水平位移間呈線性相關(guān)關(guān)系,與樁身軸力、彎矩、正應(yīng)力值間呈非線性關(guān)系,地表沉降值增大,對樁內(nèi)力影響程度增大,并且對其影響增大速率也呈增大趨勢�；谝陨戏治龇謩e給出了樁豎向和水平位移與隧道施工引起地表沉降、樁與隧道水平距離、樁長之間的函數(shù)關(guān)系式。
[Abstract]:Abstract: with the development of economy and the acceleration of urbanization, urban underground rail transit (UMT) has been built in large quantities to alleviate the traffic congestion, because the subway is built along the main road of the city. It will inevitably cross the foundation of the bridge, causing displacement and redistribution of internal force, which will affect the normal use of the structure. Based on the bridge crossing of Beijing Metro Line 10 as the main engineering background, the finite element method is used to simulate the different engineering geological conditions, the form of pile foundation, the relationship between pile and tunnel position, and the tunnel construction control condition. The main conclusions are as follows: 1) the pile settlement decreases with the increase of soil compressibility, Poisson's ratio, shear strength and the distance between pile and tunnel. The settlement value decreases with the increase of pile length, and the settlement difference between two pile caps and the slope ratio of pile cap decrease. When the pile is located near the tunnel excavation surface, the pile deviates from the tunnel direction, when the distance between the pile and the tunnel is larger than 5m, the pile tilts towards the tunnel direction, and does not tilt when the pile is located directly above the tunnel axis. The lateral displacement of the tunnel is nonlinear distribution along the depth of the pile, the pile is bending, the shear strength of the soil is weaker, the bending deformation is larger, the Poisson's ratio of the soil is increased, and the bending direction of the pile is changed from the same as the tunnel lining to the opposite. The inclined direction of the top of the two pile caps is the same as that of the cap. 2) when the pile is located directly above the tunnel structure, the axial force of the pile decreases, while the axial force increases when the pile is located on the side of the tunnel structure, and the influence degree decreases with the increase of the distance between the pile and the tunnel. The influence of the change of soil shear strength, compressibility and Poisson's ratio is small. In the foundation of two pile caps, the load of near tunnel pile decreases, which is borne by the pile of far tunnel, and the influence degree decreases with the increase of the depth of pile embedding. 3) the pile is subjected to small additional bending moment after single pile under tunnel, and the maximum value is generally located at the same elevation as the axis of the tunnel, which is related to the distance between pile and tunnel, and the maximum value in silt soil is 6 m, the maximum value is at the same elevation as the tunnel axis, and the maximum value is 6 m in silt soil. The normal stress of the pile near the tunnel side increases and the far side of the tunnel decreases, which has the greatest effect on the normal stress at the same elevation between the pile depth and the tunnel axis. The value of additional positive moment and the variation of normal stress decrease with the increase of Poisson's ratio and shear strength. Two pile caps near the pile top of the tunnel bear greater additional bending moment because of the connecting action of the cap, and the concrete in the far side of the tunnel is subjected to tensile stress. 4) the surface settlement value is linearly correlated with pile settlement and horizontal displacement, and is nonlinear with pile axial force, bending moment and normal stress. The surface settlement value increases and the influence degree on pile internal force increases. And the influence of the increase rate also showed an increasing trend. Based on the above analysis, the functional relations between the vertical and horizontal displacement of pile and the ground settlement caused by tunnel construction, the horizontal distance between pile and tunnel, and the length of pile are given.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U455.43

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