【作者】 刘联伟；

【导师】 崔广心； 杨维好；

【作者基本信息】 中国矿业大学 ， 岩土工程， 2009， 博士

【摘要】 盾构法目前是地铁隧道施工的主要工法,在世界地铁建设中占据了主要的地位,但施工中不可避免地会对地层产生扰动,引起地表的沉降,对附近建筑物产生影响。本文采用理论分析、现场实测研究和数值模拟的方法,开展了“复合地层中盾构法建设地铁地表沉降规律研究”。通过三种方法的相互补充,相互验证,获得了地表沉降的影响因素及其变化规律,为预测、控制和进一步研究盾构隧道施工引起的地表沉降奠定了基础。通过对盾构隧道周围地层的弹性和弹塑性分析,得出“地层损失引起隧道周围地层应力变化是导致地表沉降的主要原因”的结论。分析了地表沉降的主要影响因素,并根据相似理论推导了相应的相似准则,为进一步通过数值模拟和实测研究获得地表沉降的变化规律创造了条件。运用表述矿山巷道压力的普氏理论,结合广州地区岩土复合地质条件和地表沉降实测数据,分类研究了盾构隧道免压拱高度,为地表沉降是否发生提供了前瞻性的判定方法。研究表明:普氏免压拱对隧道地表沉降具有很大的影响——能够形成免压拱的地层,地表最大沉降小,沉降范围小,沉降曲线和缓;反之地表的变化情况则相反。通过研究盾构推进过程中“沉降槽”随时空的变化规律来寻求地表沉降计算公式,改变了地表沉降传统的“沉降盆”(变形场)研究模式,并将该思路应用于实测研究和数值模拟研究。运用实测研究手段,结合广州地铁三号线【珠-客】区间盾构工程实测数据,采用相似准则从空间和时间的四维角度对盾构隧道施工引起的地表沉降进行了研究,得出了反映地表沉降的简洁有效的拟合方程(1),首次总体反映了盾构施工导致的地表沉降在四维空间的连续变化规律,只要“隧道两侧地表沉降观测点与隧道中线的距离”以及“盾构机通过监测断面后的推进时间及推进距离”与“隧道所处地层性质及埋深”确定,通过拟合方程都将推导出类似的地表沉降规律,对广州地区盾构施工引起的地表沉降预测具有借鉴意义。运用Ansys有限元软件建立了盾构推进过程的四维有限元模型,分析了隧道轴线??断面“沉降槽”的变化规律,由此确定地表沉降的分布形式;推导了地表沉降量及其分布与各影响参数间关系的计算公式,实际工程中可采用此公式对实测数据进行拟合。通过数值模拟和实测研究得到的地表沉降变化规律,与工程实际情况能很好地吻合,可以利用地表沉降的前期实测数据反演方程系数(或借用相近似地层中的有关参数),通过不断增加的实测数据进一步修正方程系数,从而较好地预测盾构隧道中后期地表沉降变化规律和最终沉降量。最后,将本论文的研究成果应用在深圳地铁的相关工程并通过对比研究发现:在取得地表沉降的初期实测数据后,可以计算和预测地表沉降的变化规律和最终沉降量;参与拟合的初期实测数据越多,计算与预测结果越接近后期实测结果。这对于指导工程施工、及早采取有效措施控制地表沉降具有重大意义。更多还原

【Abstract】 Shield tunnel method is one of the major methods of subway construction which occupies a dominated position in the underground construction in the world. However, shield tunnel construction could inevitably cause some disturbances on the stratum by causing the ground surface subsidence which has an negative impact on nearby buildings and infrastructures. In this thesis, theoretical analysis, field measurement and numerical simulation study methods are used to launch the research regarding“the ground surface subsidence induced by shield tunnel during underground constructing”.Through these three methods which complement and verify each other, this research reached to the influencing factors and their changing laws of the ground surface subsidence, which lays the foundation for predicting, controlling and further studying the ground surface subsidence induced by shield tunnel. In specifics:Through the elastic and plastic analysis of the stratum around the shield tunnel, this research gained the conclusion that‘the stress change caused by the stratum loss is the main reason causing the ground surface subsidence’. Then, the main influencing factors of ground surface subsidence were analysed. According to the similar theory, the similar criteria of calculating the ground surface subsidence was deduced which created basic theoretical conditions for both numerical simulation and field measurement of the further studying on ground surface subsidence.Based on the M.M. PROMOJIYFAKONOV theory which was used to state the mine roadway plats pressure, and combined with th??ological conditions and the measured ground surface subsidence data from compound stratum with rock and soil in Guangzhou, this research studied the height of the arching effect of shield tunnel which provides a predicting method to determine whether the ground surface subsidence will happen or not. Research showed that: the arching effect has great influence on the ground surface subsidence caused by shield tunnel——if the arch can be formed in stratum, the largest subsidence will be small, the affected subsidence scope will be limited, and the curve of subsidence will be gentle; on the contrary, all reversed.The research derived the formula for calculating the value of ground surface subsidence by studying the changes of“subsidence trough”with time and space during shield promoting, which brakes through the troditional research model of“subsidence basins“(deformation). This method then were used in the measured analysis and numerical simulation study of subsidence. By adopting the similar criteria to study the ground surface subsidence induced by the shield tunnel from the perspective of four-dimensional (3Dspace and time), the measured data are analysed which are from the shield project of ZHU-KE area within the third line of Guangzhou Subway. A simple and effective equation S ? ke? k X?e?kL which is the first formula reflecting the continuous dynamic changes of the ground surface subsidence in the four-dimensional space.was regressed from the data analysis. By this equation, once“the distance between the points of the settlement monitoring on the tunnel’s both sides and the center line of the tunnel”,“the promoting time and length after the shield machine crossed the monitoring section”and“the stratum’s attribute and depth of the tunnel”are available, it is possible to derive the similar ground surface subsidence rule. This research result can be used for predicting the ground surface subsidence induced by the shield tunnel in Guangzhou area.The finite element software ANSYS was used to build a four-dimensional dynamic finite element model to simulate the process of shield promoting. This model analysed the changing law of“subsidence trough”in the transect section on tunnel axis thus to determine the shape of the ground surface subsidence;. This model was also used to derive the calculating formula between the ground surface subsidence value and its distribution with impact parameters. All these foundations can be used to regress the measured data.The law of the ground surface subsidence gained from numerical sim??ion and practical study inosculated well with the actual situation of the project. These law can be used to predict the latter and final settlement value through the coefficients regressed from the pre-measured data (or use relevant parameters of similar stratum for reference).Finally, the research results of this thesis were used to comparatively study the project of Shenzhen subway which which shows that,: once the parameters in the early stages of construction are gained, it is possible to calculate and predict the law and the final value of the ground surface subsidence, the predict results could be further improved by more pre-measured data. These research results have great significance in guiding construction and in early control of the subsidence.更多还原