沉管隧道地基处理砂流法的试验与数值分析及其施工优化
发布时间：2019-03-19 10:08
【摘要】：沉管隧道地基处理是沉管隧道施工中最重要的环节之一,砂流法由于其特有的优点,现已成为硬质地基上沉管隧道基础处理的首选。沉管隧道基础处理成功与否,直接关系到沉管隧道的服役与安全,一旦出现超过允许值的沉降或不均匀沉降,无论规模大小,后续的处理将非常困难,甚至是不可处理的。因此,对沉管隧道砂流法地基处理机理及设计方法的研究,确保管节与基础密实接触,具有重要的工程意义。砂流法砂盘成型过程复杂,砂的运动主要靠流场作为传输,而又反过来影响流体的流场,且目前对砂流法的研究较少涉及砂流法理论研究,故有必要从理论角度分析砂流法处理沉管隧道地基的全过程,实现优化、指导砂流法施工的目的。文中自行研制了砂流法施工的砂盘探测器,解决了水下基槽试验环境中的实时探测难题;设计了大型砂流法全尺度试验模型系统,同时实现了不同基槽深度、砂水比、施工边界等工况下的对比模型试验,得出试验中砂盘发展、水压力变化规律,进而分析得出砂盘成型过程以及试验中参数变化对砂流法施工的影响;依据固—液两相流理论,实现了砂、水两相间的耦合作用,为砂流法理论分析提供基础,数值实现砂流法砂盘成型过程;数值试验实现了不同砂水比、基槽深度、边界条件工况下的砂流法处理过程,以及不同河流流速、水位等对基槽内砂盘成型的影响,讨论砂流在各种复杂工况下的响应情况。本文得出的主要结论有以下几点:(1)砂流法中砂颗粒自喷入到沉积的运动轨迹经历了“上升区”、“输送区”与“沉积区”三个过程,砂盘的发展经历了“堆积”与“扩展”两个阶段。(2)砂流法中砂水比、基槽深度的变化均对基槽内水压力、砂盘轴向发展、冲击坑尺寸和流缝宽度等影响较大;砂流法施工中理想砂水比为0.1~0.15,较合理基槽深度为0.8m~1.0m。(3)砂流法在具有较小流速的基槽内施工,砂盘最终半径可达到设计要求,但形状将表现为下游边界曲率半径更小上游边界曲率半径更大的水滴形。(4)已成型砂盘的边界对拟施工砂盘小半径范围内的影响较小,但在砂盘相交处区域的填满度与密实度均不高。(5)相对于砂盘平行布置方案,交错布置方案中的密实度与填满度更高。砂盘设计与施工过程应保证砂盘对称布置,尽可能保证砂盘较大面积的重叠,避免砂盘施工过程中产生小锐角边界区域。
[Abstract]:The foundation treatment of the immersed tube tunnel is one of the most important links in the construction of the immersed tube tunnel, and the sand flow method has become the first choice for the foundation treatment of the immersed tube tunnel on the hard foundation due to its unique advantages. If the foundation treatment of the immersed tube tunnel is successful or not, it is directly related to the service and safety of the immersed tube tunnel. Therefore, the research on the foundation treatment mechanism and design method of the sand-flow method of the immersed tube tunnel ensures that the pipe joint is in close contact with the foundation and has important engineering significance. The sand-flow method is complicated in the forming process, the movement of the sand mainly depends on the flow field as the transmission, which in turn affects the flow field of the fluid, and the research on the sand flow method is less involved in the sand flow theory study, so it is necessary to analyze the whole process of the sand flow method to treat the immersed tube tunnel foundation from the theoretical angle. And the purpose of optimizing and guiding the construction of the sand flow method is realized. In this paper, a sand-disk detector for sand-flow construction is developed, and the real-time detection problem in the underwater base-tank test environment is solved; a large-scale sand-flow method full-scale test model system is designed, and a comparison model test under the conditions of different base groove depth, sand-water ratio, construction boundary and the like is realized, According to the two-phase flow theory of solid-liquid two-phase flow theory, the coupling effect between sand and water is realized, and the foundation is provided for the theoretical analysis of sand flow method. In this paper, the sand-flow process of sand-flow method is realized by numerical experiments, and the influence of different sand-water ratio, base-groove depth, boundary condition and sand-flow process under the condition of boundary condition, and the influence of different river flow rate and water level on the formation of the sand-plate in the base tank are realized, and the response of the sand-flow under various complicated working conditions is discussed. The main conclusions are as follows: (1) The self-injection of the sand particles in the sand-flow process through the three processes of the "rising area", the "transport area" and the "sedimentary area", and the development of the sand disk has experienced two stages of the "build up" and the "expand". (2) The change of the sand-water ratio and the base-groove depth in the sand-flow method has great influence on the water pressure in the base tank, the axial development of the sand disc, the size of the impact pit and the width of the flow, and the ideal sand-water ratio in the sand-flow method is 0.1-0.15, and the depth of the reasonable base groove is 0.8-1.0m. (3) The sand flow method is constructed in a base tank with a small flow velocity, and the final radius of the sand disk can reach the design requirements, but the shape will appear as a water drop with a smaller radius of curvature of the downstream boundary and a larger radius of curvature. (4) The influence of the boundary of the formed sand disk on the small radius of the sand disk to be constructed is small, but the filling degree and the compactness of the area at the intersection of the sand disc are not high. And (5) the arrangement scheme is arranged in parallel with respect to the sand table, and the compactness and the filling degree in the staggered arrangement scheme are higher. The design and construction process of the sand table shall ensure the symmetrical arrangement of the sand disk, ensure the overlapping of the large area of the sand disc as much as possible, and avoid the small acute angle boundary area during the construction of the sand disc.
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U455.4;U459.5
本文编号：2443425
[Abstract]:The foundation treatment of the immersed tube tunnel is one of the most important links in the construction of the immersed tube tunnel, and the sand flow method has become the first choice for the foundation treatment of the immersed tube tunnel on the hard foundation due to its unique advantages. If the foundation treatment of the immersed tube tunnel is successful or not, it is directly related to the service and safety of the immersed tube tunnel. Therefore, the research on the foundation treatment mechanism and design method of the sand-flow method of the immersed tube tunnel ensures that the pipe joint is in close contact with the foundation and has important engineering significance. The sand-flow method is complicated in the forming process, the movement of the sand mainly depends on the flow field as the transmission, which in turn affects the flow field of the fluid, and the research on the sand flow method is less involved in the sand flow theory study, so it is necessary to analyze the whole process of the sand flow method to treat the immersed tube tunnel foundation from the theoretical angle. And the purpose of optimizing and guiding the construction of the sand flow method is realized. In this paper, a sand-disk detector for sand-flow construction is developed, and the real-time detection problem in the underwater base-tank test environment is solved; a large-scale sand-flow method full-scale test model system is designed, and a comparison model test under the conditions of different base groove depth, sand-water ratio, construction boundary and the like is realized, According to the two-phase flow theory of solid-liquid two-phase flow theory, the coupling effect between sand and water is realized, and the foundation is provided for the theoretical analysis of sand flow method. In this paper, the sand-flow process of sand-flow method is realized by numerical experiments, and the influence of different sand-water ratio, base-groove depth, boundary condition and sand-flow process under the condition of boundary condition, and the influence of different river flow rate and water level on the formation of the sand-plate in the base tank are realized, and the response of the sand-flow under various complicated working conditions is discussed. The main conclusions are as follows: (1) The self-injection of the sand particles in the sand-flow process through the three processes of the "rising area", the "transport area" and the "sedimentary area", and the development of the sand disk has experienced two stages of the "build up" and the "expand". (2) The change of the sand-water ratio and the base-groove depth in the sand-flow method has great influence on the water pressure in the base tank, the axial development of the sand disc, the size of the impact pit and the width of the flow, and the ideal sand-water ratio in the sand-flow method is 0.1-0.15, and the depth of the reasonable base groove is 0.8-1.0m. (3) The sand flow method is constructed in a base tank with a small flow velocity, and the final radius of the sand disk can reach the design requirements, but the shape will appear as a water drop with a smaller radius of curvature of the downstream boundary and a larger radius of curvature. (4) The influence of the boundary of the formed sand disk on the small radius of the sand disk to be constructed is small, but the filling degree and the compactness of the area at the intersection of the sand disc are not high. And (5) the arrangement scheme is arranged in parallel with respect to the sand table, and the compactness and the filling degree in the staggered arrangement scheme are higher. The design and construction process of the sand table shall ensure the symmetrical arrangement of the sand disk, ensure the overlapping of the large area of the sand disc as much as possible, and avoid the small acute angle boundary area during the construction of the sand disc.
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U455.4;U459.5
【引证文献】
相关会议论文 前1条
1 茹玉英;王开荣;;泥沙沉降计算公式对比分析[A];水文泥沙研究新进展——中国水力发电工程学会水文泥沙专业委员会第八届学术讨论会论文集[C];2010年
，本文编号：2443425
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