深圳复合地层对盾构隧道衬砌管片结构受力和变形的影响分析

发布时间：2018-09-01 14:24

【摘要】：本文以深圳地铁11号线车公庙站—红树湾站和南山站—前海湾站区间盾构隧道为依托工程,首先选择具有代表性的基岩突起和软硬不均的地质条件断面进行数值模拟,分析对比不同工况对管片受力变形的影响；然后选择差异风化地层试验断面采用光纤光栅技术对管片表面和螺栓进行现场监测,再选择监测断面进行数值模拟分析,据此分析管片和螺栓的受力变形规律；最后将数值模拟结果与现场监测数据进行了对比。论文取得的主要成果和结论如下： (1)选取具有基岩突起的典型断面,分别考虑基岩突起宽度为Om,2m,4m,6m和8m五种工况进行管片受力变形的数值模拟。分析结果表明,基岩突起对管片的不均匀沉降影响明显；基岩突起的宽度越大,对管片的不均匀沉降影响越明显,与基岩突起接触的或者是基岩突起附近的管片的受力越不利。由于混凝土管片的抗拉强度低,随着基岩突起宽度的增加,管片被拉裂的风险也增大,因此将管片受拉破坏对应的一段隧道沉降差和基岩突起宽度的乘积和40环管片长度(60m)的比值作为基岩突起引起纵向不均匀沉降的警戒值。根据计算结果,若考虑一定的安全储备,该警戒值可取为0.3%o。 (2)选取上软下硬地层的典型断面,分别考虑硬岩侵入隧道为Om,1.75m,3.5m,5.25m和7m五种工况进行数值模拟,分析管片的受力和变形,结果显示,上软下硬地层中,硬岩侵入开挖面越多,有利于管片的受力,但会增大隧道施工的难度。 (3)采用光纤光栅传感器进行了现场螺栓和盾构管片的变形监测。通过现场监测数据分析,管片脱出盾构壳体后,螺栓的轴向应力会剧烈增大、增幅显著,原因是水土压力和注浆压力对螺栓的轴向应力影响比油缸推力的要大。由于注浆压力的影响有滞后性,在掘进7环管片(10.5m)后浆液凝固,螺栓受力趋于平稳。在掘进过程中,环向螺栓的轴向应力比纵向螺栓的大,环向螺栓中靠近油缸的螺栓比远离油缸的螺栓的轴向应力大,但都有足够的安全储备。监测数据显示,所有螺栓轴向应力的最大值为345.46MPa,仅达到螺栓屈服应力640MPa的53.98%,这说明螺栓受力处于安全状态。 (4)通过复合地层中管片受力变形的数值模拟分析,现场监测螺栓处在受力的最不利位置,说明了所确定监测方案的合理性。在隧道开挖过程中,盾构施工7环(10.5m)时对监测环的错台影响明显,且该7环管片位移变形大,随后变小,最后趋于平稳。和现场监测数据相同,盾构掘进时纵向螺栓主要以轴向拉应力为主；此外,壁后注浆对螺栓受力有较大影响。
[Abstract]:Based on Shenzhen Metro Line 11 Chegongmiao Station-Hongshu Bay Station and Nanshan Station-former Bay Station Shield Tunnel, the representative bedrock protrusions and sections with uneven soft and hard geological conditions are first selected for numerical simulation. This paper analyzes and compares the influence of different working conditions on the stress and deformation of the segment, then selects the section of the differential weathering stratum test section to monitor the segment surface and bolts by fiber Bragg grating technology, and then selects the monitoring section to carry on the numerical simulation analysis, and then selects the monitoring section to carry on the numerical simulation analysis. Finally, the numerical simulation results are compared with the field monitoring data. The main results and conclusions obtained in this paper are as follows: (1) A typical section with a bedrock protuberance is selected, and the stress deformation of the segment is simulated under five conditions, namely, the width of the protruding of the bedrock is Om,2m,4m,6m and the width of the protruding is 8m. The results show that the uneven settlement of the segment is obviously affected by the bedrock protrusions, and the larger the width of the bedrock protrusions, the more obvious the influence on the uneven settlement of the segments, and the more disadvantageous the stress is on the segments in contact with or near the bedrock protrusions. Because of the low tensile strength of the concrete segment, the risk of tensile crack increases with the increase of the width of the protruding of the bedrock. Therefore, the product of tunnel settlement difference and the width of bedrock bulge and the ratio of 40 annular segment length (60m) are taken as warning values of longitudinal uneven settlement caused by bedrock uplift. According to the calculation results, if a certain safety reserve is considered, the warning value should be 0.3o. (2) the typical sections of the upper soft and lower hard strata are selected, and the numerical simulation is carried out under the five working conditions of Om,1.75m,3.5m,5.25m and 7m, respectively, when the hard rock intrudes into the tunnel. The stress and deformation of the segment are analyzed. The results show that the more hard rock intrudes into the excavated surface in the upper soft and lower hard strata, the better the force of the segment is. But it will increase the difficulty of tunnel construction. (3) using fiber grating sensor to monitor the deformation of bolt and shield segment. Through the analysis of field monitoring data, the axial stress of bolt will increase dramatically after the segment is removed from shield shell, the reason is that the influence of soil and water pressure and grouting pressure on the axial stress of bolt is greater than the thrust of oil cylinder. Due to the effect of grouting pressure, the grouting fluid solidifies after driving 7 ring tube sheet (10.5m), and the force of bolt tends to be stable. In the process of driving, the axial stress of the annular bolt is greater than that of the longitudinal bolt, and the axial stress of the annular bolt near the cylinder is greater than that of the bolt far away from the cylinder, but there is sufficient safety reserve. The monitoring data show that the maximum axial stress of all bolts is 345.46 MPA, which only reaches 53.98% of the bolt yield stress 640MPa, which indicates that the bolt is in a safe state. (4) the numerical simulation analysis of the stress deformation of the segment in the composite stratum is carried out. The monitoring bolt is in the most unfavorable position of the force, which shows the rationality of the determined monitoring scheme. In the course of tunnel excavation, the influence of shield construction on the staggered platform of the monitoring ring is obvious during the 7 rings (10.5 m) of shield construction, and the displacement of the segment of the 7 rings is large, then becomes smaller, and finally tends to steady. The longitudinal bolts are mainly axial tensile stress in shield tunneling, in addition, grouting behind the wall has a great influence on the bolt force.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U455.43

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