悬挂式防渗墙后土体渗流试验研究
发布时间：2018-08-25 14:54
【摘要】：悬挂式防渗墙主要功能是限制管涌发展和改变渗流场流态。由于绕渗作用，墙后的水流速度会大大降低，流线方向会改变，有效渗径会增加；墙后水力坡降分布不均，有极大的，也有较小的，导致墙后土的渗透性发生改变，在流态的变化中形成新的平衡，直至最终破坏。 目前关于悬挂式防渗墙限制管涌发展方面研究较多，但墙后的流态是尚未研究透的内容。本文针对悬挂式防渗墙后土体渗流场的研究，做了以下工作： （1）对悬挂式防渗墙模拟试验技术做了改进。采用压力水袋模拟覆盖层，有效地防止了砂槽上部漏水和覆盖层地面产生空隙；使用透明纱布消除排水液面“张力”对下游排水顺畅性的影响。 （2）绘制试验流网图，对比砂槽内各区域等水头线的疏密变化，并与有限元计算结果对比，证明了墙后土的渗透性有发生变化。 （3）引入当量渗透系数K，相对水力坡降I 'x，测压管相对位势φi，结合试验总流量，从四个方面进一步论证墙后土的渗流场的变化。先利用K和I 'x分析砂槽整体的变化，然后利用I 'x和φi分区域分析砂槽局部的变化，证明了在渗透力的作用下，悬挂式防渗墙周围的砂质土层会有细颗粒的移动、淤积现象，达到从宏观的试验现场验证微观的砂颗粒移动淤积现象的目的。 （4）最终通过分析，找出了砂槽最主要的细颗粒淤积区是下游靠近挡板端部的砂层区域，最主要的细颗粒流失区是挡板正下方最接近挡板的区域。并根据分析结果，调整各区域的渗透系数，，通过有限元计算，验证试验分析结果的合理性。
[Abstract]:The main function of hanging cutoff wall is to limit the development of pipe and change the flow state of seepage field. As a result of the seepage around the wall, the velocity of water behind the wall will be greatly reduced, the direction of the streamline will be changed, the effective seepage diameter will be increased, the hydraulic slope behind the wall will be distributed unevenly, and there will be great and smaller, which will result in the change of the permeability of the soil behind the wall. A new equilibrium is formed in the variation of the flow state until it is finally destroyed. At present, there are many researches on the development of suspended cutoff wall, but the flow pattern behind the wall is not fully studied. In this paper, the following work has been done to study the seepage field of soil behind the suspended impervious wall: (1) the simulation test technology of the suspended cutoff wall has been improved. The pressure water bag is used to simulate the overburden, which effectively prevents the leakage of the upper part of the sand trough and the void on the ground of the overburden. The influence of the "tension" of the drainage surface on the downstream drainage smoothness is eliminated by the use of transparent gauze. (2) drawing the test flow net diagram, The density variation of the isobaric head lines in each area of the sand trough is compared and compared with the results of the finite element calculation. It is proved that the permeability of the soil behind the wall has changed. (3) the change of seepage field of soil behind the wall is further demonstrated from four aspects by introducing the equivalent permeability coefficient K, the relative hydraulic gradient I x, the relative potential 蠁 I of the pressure measuring pipe and the total experimental discharge. Using K and I x to analyze the overall change of sand trough, and then using I X and 蠁 I to analyze the local change of sand trough, it is proved that under the action of permeability, the movement and deposition of fine particles will occur in the sandy soil around the suspended impervious wall. In order to verify the microscopic sand particle moving and silting phenomenon from the macroscopic test site. (4) finally, through the analysis, we find out that the most important fine grain silt area in the sand trough is the sand bed area near the end of the baffle. The main fine particle loss area is the area closest to the baffle directly below the baffle. According to the analysis results, the permeability coefficient of each region is adjusted, and the rationality of the experimental results is verified by finite element calculation.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV543.8
本文编号：2203215
[Abstract]:The main function of hanging cutoff wall is to limit the development of pipe and change the flow state of seepage field. As a result of the seepage around the wall, the velocity of water behind the wall will be greatly reduced, the direction of the streamline will be changed, the effective seepage diameter will be increased, the hydraulic slope behind the wall will be distributed unevenly, and there will be great and smaller, which will result in the change of the permeability of the soil behind the wall. A new equilibrium is formed in the variation of the flow state until it is finally destroyed. At present, there are many researches on the development of suspended cutoff wall, but the flow pattern behind the wall is not fully studied. In this paper, the following work has been done to study the seepage field of soil behind the suspended impervious wall: (1) the simulation test technology of the suspended cutoff wall has been improved. The pressure water bag is used to simulate the overburden, which effectively prevents the leakage of the upper part of the sand trough and the void on the ground of the overburden. The influence of the "tension" of the drainage surface on the downstream drainage smoothness is eliminated by the use of transparent gauze. (2) drawing the test flow net diagram, The density variation of the isobaric head lines in each area of the sand trough is compared and compared with the results of the finite element calculation. It is proved that the permeability of the soil behind the wall has changed. (3) the change of seepage field of soil behind the wall is further demonstrated from four aspects by introducing the equivalent permeability coefficient K, the relative hydraulic gradient I x, the relative potential 蠁 I of the pressure measuring pipe and the total experimental discharge. Using K and I x to analyze the overall change of sand trough, and then using I X and 蠁 I to analyze the local change of sand trough, it is proved that under the action of permeability, the movement and deposition of fine particles will occur in the sandy soil around the suspended impervious wall. In order to verify the microscopic sand particle moving and silting phenomenon from the macroscopic test site. (4) finally, through the analysis, we find out that the most important fine grain silt area in the sand trough is the sand bed area near the end of the baffle. The main fine particle loss area is the area closest to the baffle directly below the baffle. According to the analysis results, the permeability coefficient of each region is adjusted, and the rationality of the experimental results is verified by finite element calculation.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV543.8
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