天津软土地区盾构施工端头加固及对周边环境影响效应

发布时间：2018-06-10 21:29

本文选题：盾构隧道 + 端头加固　；参考：《天津城建大学》2014年硕士论文

【摘要】：在我国地铁事业迅猛发展的今天，盾构技术被越来越广泛的采用。选择合理的始发端头土体加固范围以及准确掌握盾构施工对周围环境的影响规律对于软土盾构施工是极其重要的。本文以天津地铁2号线机场延长线盾构隧道施工段为背景，结合现场实测资料，运用ABAQUS有限元程序计算了天津地区盾构始发端头合理纵向加固范围、盾构施工造成地层沉降的规律以及盾构近接桩基施工对其的影响，主要得到以下结论：（1）通过理论计算与模拟结果的对比，发现理论计算得出的加固长度范围偏小。基于不同加固长度下破除封门和开挖时土体位移和应力比较，结合本区实际工程情况，认为天津软土地区盾构始发端头的合理纵向加固范围大致为8.2m~11.5m。若设计时考虑较大的安全余量，可采用在端头加固后段的三轴搅拌桩中适当减小水泥掺量的方法达到既安全又有利于盾构掘进控制和降低造价的目的。（2）地表任一断面在盾构施工过程中都要经历一个随距开挖面相对位置不同而不断变化的沉降过程；同一断面不同深度处土层的沉降量及沉降影响范围不同，深层土体受施工扰动响应较地表更为敏感；通常情况下浅表层与深层土体沉降趋势一致，，但由于城市地表硬壳层的存在，会导致监测数据较实际沉降值偏小，实际工程中应重视这种现象。（3）由于遮挡效应的存在，近隧道建筑物桩基础中靠近隧道的单桩水平位移要大于远离隧道的单桩。桩与隧道之间的距离将影响盾构施工对邻近桩体的扰动程度。距离隧道越近，盾构施工引起的桩身水平和竖向位移就越大。桩端与隧道轴线的相对位置也会影响到桩体水平位移的变化规律。当桩端位于隧道轴线以下时，桩身水平位移要小于桩端在隧道轴向上方和与轴线齐平时的位移。
[Abstract]:With the rapid development of the subway industry in China, the shield technology is becoming more and more widely used. It is very important for the shield construction to select the reasonable range of soil reinforcement and to accurately grasp the influence of the shield construction on the surrounding environment. This paper takes the construction section of the shield tunnel of the airport extension line of Tianjin Metro Line 2 as the construction section. Background, combined with the field measured data, the ABAQUS finite element program is used to calculate the reasonable longitudinal reinforcement range of the beginning end of the shield in Tianjin area, the law of the stratum settlement caused by the shield construction and the influence of the shield construction on the pile foundation construction. The following conclusions are mainly obtained.
(1) through the comparison of theoretical calculation and simulation results, it is found that the reinforcement length range of the theoretical calculation is small. Based on the comparison of the soil displacement and stress when the door is broken and excavated under the different reinforcement lengths, the reasonable longitudinal reinforcement range of the shield starting end of the Tianjin soft soil area is approximately 8.2m~11.5m.. If the large safety allowance is considered in the design, the method of reducing the cement content in the three shaft mixing pile after the end reinforcement can be used to achieve the purpose of safety, shield driving control and cost reduction.
(2) in the course of the shield construction, any section of the surface of the earth must undergo a process of settlement that varies with the relative position of the distance between the surface of the excavation; the settlement and the influence range of the soil layer are different at different depths of the same section, and the deep soil soil is more sensitive to the ground surface and the deep soil under the normal condition. The settlement trend is the same. However, due to the existence of hard crust in the urban area, the monitoring data will be smaller than the actual settlement value. This phenomenon should be emphasized in practical engineering.
(3) because of the occlusion effect, the horizontal displacement of the single pile near the tunnel in the pile foundation of the near tunnel building is greater than that of the single pile far away from the tunnel. The distance between the pile and the tunnel will affect the disturbance degree of the shield construction to the adjacent pile. The closer the tunnel is to the tunnel, the greater the horizontal and vertical displacement of the pile is caused by the shield construction. The pile end and the tunnel shaft will be more and more. The relative position of the line also affects the change law of the horizontal displacement of the pile body. When the pile end is below the axis of the tunnel, the horizontal displacement of the pile body is less than that of the pile end in the axial and the axis of the tunnel.
【学位授予单位】：天津城建大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U455.43

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