大直径泥水盾构隧道超挖引起地面沉降研究

发布时间：2018-04-15 21:32

本文选题：泥水盾构 + 超挖　；参考：《南京大学》2014年硕士论文

【摘要】：大直径泥水盾构具有广泛的地层适宜性,适合修建长距离、大断面、高水压下的隧道,它的这种特性使其成为兴建越江、跨海隧道的最佳选择。采用数值模拟方法对大直径泥水盾构掘进进行研究,可以给出隧道施工期间地层位移的发展变化规律,对于保护隧道附近建筑物及重要地下管线具有积极意义。该方法具有低成本、高效率的特点,随着计算机性能的增强以及数值模拟软件的发展,有广阔的应用前景。本文依托南京纬七路长江隧道工程,对右线隧道起始段盾构掘进过程中的若干实时监测数据进行了分析,并采用岩土工程分析软件PLAXIS3D对盾构掘进过程进行了模拟,得出以下结论： (1)大直径泥水盾构的超挖是导致地表沉降过大的主要因素。结合盾构掘进参数、开挖土体的含水率、比重,通过对开挖干土量的计算,可以粗略估算超大直径泥水盾构的平均超挖量,虽然有一定误差,但结果具有一定的参考价值。 (2)采用刚度迁移法模拟盾构掘进时,若按照盾壳的实际尺寸建立有限元模型,计算得到的地表沉降误差非常大,所得沉降发展曲线与实测沉降发展曲线相差很大；而采用等效面收缩法模拟土体超挖时,沉降计算结果与实测值比较接近,且所得沉降发展曲线与实测规律比较接近。这表明采用等效面收缩法模拟超大直径泥水盾构的掘进过程是更加合理的。 (3)PLAXIS3D中的土体硬化模型,由于采用了三轴加载刚度E50、三轴卸载刚度Eur和固结仪加载刚度Eoed三个刚度参数来考虑加载、卸载的区别和土体的硬化特性,在模拟隧道开挖问题方面有一定的优势。对于淤泥质粉质粘土,在无法取得其刚度参数时,可以用勘察报告中提出的压缩模量近似作为100kPa参考压下的Eso,并将三个刚度参数按1：1：3的比例取值。这种情况下的计算结果是具有一定参考价值的。 (4)在采用刚度迁移法模拟盾构掘进时,整体开挖与逐环开挖相比,得到的沉降量明显偏小,二者计算所得的土体应力重布情况差别很小。
[Abstract]:Large diameter mud shield is suitable for constructing long distance, large section and high water pressure tunnel, which makes it the best choice to build cross river tunnel and cross sea tunnel.The numerical simulation method is used to study the large-diameter mud water shield tunneling. The development and variation law of the stratum displacement during the tunnel construction can be given, which is of positive significance for the protection of the buildings near the tunnel and the important underground pipelines.This method has the characteristics of low cost and high efficiency. With the enhancement of computer performance and the development of numerical simulation software, it has a broad application prospect.In this paper, based on the Yangtze River tunnel project of Nanking Weiqi Road, some real time monitoring data during shield tunneling in the starting section of right line tunnel are analyzed, and the process of shield tunneling is simulated by using geotechnical engineering analysis software PLAXIS3D.Draw the following conclusions:1) the overexcavation of large diameter mud shield is the main factor that causes the surface subsidence to be too large.Combined with shield tunneling parameters, water content and specific gravity of excavated soil mass, the average overdigging amount of super-diameter mud shield can be roughly estimated by calculating the amount of dry soil excavated. Although there are certain errors, the results are of certain reference value.2) when using stiffness transfer method to simulate shield tunneling, if the finite element model is established according to the actual size of shield shell, the calculated surface subsidence error is very large, and the settlement development curve is very different from the measured settlement development curve.When the equivalent surface shrinkage method is used to simulate soil overexcavation, the settlement calculation results are close to the measured values, and the settlement development curve is close to the measured results.It shows that it is more reasonable to use equivalent surface shrinkage method to simulate the driving process of super diameter mud water shield.Due to the use of three stiffness parameters such as triaxial loading stiffness E50, triaxial unloading stiffness Eur and consolidation instrument loading stiffness Eoed, the difference between loading and unloading and the hardening characteristics of soil are considered.It has some advantages in simulating tunnel excavation.For silty silty clay, when the stiffness parameters can not be obtained, the compression modulus proposed in the survey report can be used as the reference pressure of 100kPa, and the three stiffness parameters can be calculated according to the 1:1:3 ratio.In this case, the calculation results are of certain reference value.4) in the simulation of shield tunneling by stiffness transfer method, the settlement obtained by the whole excavation is obviously smaller than that by the circular excavation, and the difference between the soil stress redistribution calculated by the two methods is very small.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U455.43;P642.26

【参考文献】