本文選題：深基坑 + 監(jiān)測��； 參考：《合肥工業(yè)大學(xué)》2014年碩士論文

【摘要】：列車動荷載對鄰近基坑圍護(hù)結(jié)構(gòu)影響的研究已逐漸成為巖土工程領(lǐng)域研究的難點(diǎn)與熱點(diǎn)問題之一。本文以上跨地鐵2號線的基坑為工程背景，針對基坑開挖時既有地鐵隧道的變形情況以及列車動荷載對基坑圍護(hù)結(jié)構(gòu)的影響進(jìn)行研究。采用MIDAS/GTS通用有限軟件建立模型，全過程模擬基坑的開挖施工。研究分析了下穿基坑的既有地鐵隧道變形的原因及控制其變形的措施，并且從地表沉降、基坑圍護(hù)結(jié)構(gòu)的受力變形與振動及既有地鐵隧道穩(wěn)定等方面，研究分析了列車移動荷載對上部基坑穩(wěn)定性的影響。本文所做工作與結(jié)論如下： （1）以南京城西干道綜合改造工程作為工程背景，設(shè)計了基坑監(jiān)測方案并完成現(xiàn)場實(shí)際監(jiān)測工作，通過對監(jiān)測數(shù)據(jù)進(jìn)行分析，得出了基坑圍護(hù)結(jié)構(gòu)的變形規(guī)律。研究表明，圍護(hù)樁深層水平位移最大值出現(xiàn)在樁頂，圍護(hù)樁底的水平位移很�。◣缀鯙榱悖�。支撐軸力與圍護(hù)樁樁頂位移隨著開挖深度的增加而變大；在基坑底板澆筑完成后，軸力與樁位移保持穩(wěn)定。 （2）采用MIDAS/GTS建立模型，模擬基坑的開挖施工，數(shù)值模擬結(jié)果與現(xiàn)場實(shí)測數(shù)據(jù)基本一致。研究分析在基坑開挖過程中影響下穿隧道變形的原因，探討了控制既有隧道變形的施工措施。通過把監(jiān)測數(shù)據(jù)與數(shù)值模擬結(jié)果相結(jié)合分析，得出由于基坑開挖卸載所引起的下穿既有隧道變形規(guī)律，如既有隧道縱向隆起曲線呈正態(tài)分布，地鐵隧道縱向隆起的范圍大約為基坑沿隧道方向開挖長度的2到3倍。研究結(jié)果表明采用的施工措施可以有效的控制隧道的上抬變形。 （3）列車移動荷載對基坑圍護(hù)結(jié)構(gòu)的作用所產(chǎn)生的影響不能忽視。通過分析表明，當(dāng)基坑下部既有隧道有列車運(yùn)行時，列車移動荷載對基坑圍護(hù)結(jié)構(gòu)產(chǎn)生的內(nèi)力較小，工程中可以不考慮；列車動荷載對圍護(hù)結(jié)構(gòu)在Z方向上的振動較為明顯，但圍護(hù)墻的振動依然處于安全可控的范圍內(nèi)。通過有限元計算，預(yù)測既有隧道結(jié)構(gòu)在長期地鐵移動荷載作用下，，列車動荷載對既有隧道結(jié)構(gòu)的正常使用與耐久性會產(chǎn)生一定的危害。為確保地鐵的安全運(yùn)營，需要采用相應(yīng)的減震措施來降低列車動荷載對既有隧道的影響。因此，既有隧道需要采取一些抗震措施如在鋼軌上添加一些減震性扣件來降低列車動荷載的振動影響。
[Abstract]:The research on the influence of train dynamic load on the surrounding structure of adjacent foundation pit has gradually become one of the difficult and hot problems in geotechnical engineering field. In this paper, the foundation pit which spans Metro Line 2 is the engineering background. The deformation of the existing subway tunnel and the influence of the train dynamic load on the retaining structure of the foundation pit are studied during the excavation of the foundation pit. The model is built by MIDAS-GTS software, and the excavation of foundation pit is simulated in the whole process. This paper studies and analyzes the causes of deformation of existing subway tunnel under foundation pit and the measures to control its deformation, and from the aspects of ground subsidence, mechanical deformation and vibration of foundation pit enclosure structure and the stability of existing subway tunnel, etc. The influence of train moving load on the stability of upper foundation pit is studied and analyzed. The work and conclusions of this paper are as follows: (1) based on the comprehensive reconstruction project of Nanjing West main Road, the monitoring scheme of foundation pit is designed and the actual monitoring work is completed, and the monitoring data are analyzed. The deformation law of foundation pit enclosure structure is obtained. The results show that the maximum horizontal displacement of the retaining pile appears at the top of the pile, and the horizontal displacement at the bottom of the retaining pile is very small (almost zero). The axial force of support and the displacement of the top of retaining pile become larger with the increase of excavation depth, and the axial force and displacement of pile remain stable after the foundation pit floor is cast. (2) MIDAS-GTS is used to establish a model to simulate the excavation of foundation pit. The numerical simulation results are in good agreement with the field measured data. This paper analyzes the causes of tunnel deformation in the process of foundation pit excavation, and discusses the construction measures to control the deformation of existing tunnel. By combining the monitoring data with the numerical simulation results, the deformation law of the existing tunnel caused by excavation and unloading of the foundation pit is obtained, such as the normal distribution of the longitudinal uplift curve of the existing tunnel. The longitudinal uplift of the subway tunnel is about 2 to 3 times the length of the excavation along the tunnel direction. The results show that the construction measures can effectively control the uplift deformation of the tunnel. 3) the effect of the moving load on the foundation pit enclosure structure can not be ignored. The analysis shows that when there is train running in the existing tunnel in the lower part of the foundation pit, the internal force generated by the train moving load on the foundation pit enclosure structure is relatively small, which can be ignored in the engineering, and the vibration of the supporting structure in Z direction is obvious under the train dynamic load. However, the vibration of the retaining wall is still in a safe and controllable range. Through finite element calculation, it is predicted that the train dynamic load will cause certain harm to the normal use and durability of the existing tunnel structure under the action of long term subway moving load. In order to ensure the safe operation of subway, it is necessary to adopt corresponding seismic absorption measures to reduce the influence of train dynamic load on the existing tunnel. Therefore, it is necessary to take some seismic measures such as adding some dampening fasteners to the existing tunnel to reduce the vibration effect of train dynamic load.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：U451.3;TU753

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