温州浅滩区袋装淤泥筑堤变形特性研究

发布时间：2018-06-07 04:27

本文选题：浅滩区 + 土工织物　；参考：《辽宁工程技术大学》2014年硕士论文

【摘要】：袋装淤泥筑堤是通过充填器具直接挖取浅滩区淤泥充填到铺设好的土工织物袋体内,达到设计强度后逐层充填最终形成堤坝。将这种工程性质差的淤泥作为堤坝组成材料的主体,结合土工织物袋的加筋保土作用,形成具有结构性强度的构筑物。目前该技术还处于现场试验阶段,对其理论研究及袋装淤泥堤坝变形特性分析仍很少见。本文依托苍南县江南海涂围垦区吹填及软基处理一期(A1区)工程充填土袋筑堤试验工程,结合加筋土加筋机制、土工织物袋充填特性、土体固结机理、加筋土稳定性计算有限元法,开展了袋装淤泥筑堤的变形特性研究,具体研究成果如下：(1)通过对袋装淤泥强度来源分析,提出了袋装淤泥前期强度主要由土工织物的加筋保土作用所提供,后期强度主要由固结土体的结构性强度所提供。(2)通过对土工织物袋的受力分析,建立了描述充填袋几何形状的方程组,并运用Matlab软件求得数值解。发现充填袋的高度与泵压之间呈对数关系,接触面宽度与泵压之间呈指数关系,土工织物袋张力与泵压之间呈线性关系。结合现场大尺度土工织物袋的充填形状,建立了单层土工织物袋张力的计算公式。(3)通过算例的优化分析,建立了试验段的有限元模型,对比分析了Hardening-Soil模型与莫尔-库仑模型的模拟结果,得到以下结论：堤坝宽度范围内,基底面的垂直位移是向下的,且随着填筑的进行,垂直位移逐渐增大；堤坝宽度范围以外,基底面产生了一定量的隆起；随着填筑的进行,基底面垂直位移隆起与压缩的分界点逐渐远离堤坝中轴线。基底面的水平位移在堤坝修筑过程中呈开口向下的抛物线分布,且距堤坝中轴线9m范围内的水平位移增加的速度较小。随着断面深度的增加垂直位移逐渐减小,同一深度的垂直位移在填筑过程中也迅速增加。水平位移随断面深度增加先增大后减小；随着填筑的进行,断面同一深度各点的水平位移均有所增加。采用Hardening-Soil模型计算土体的超静孔隙水压力消散的较快,一年后的孔隙水压力为2.7 KN/m2,莫尔-库仑模型计算的结果为5.2 KN/m2,与实测值4.4KN/m2相比相差较小。随着距堤坝中轴线距离的增加袋体轴力逐渐减小；随着填筑的进行,基底面袋体轴力略有增加,且轴力增加的速度逐渐减小。(4)基于强度折减的有限元法计算袋装淤泥堤坝稳定性发现加筋土条分法不适用计算此类加筋土的稳定性。
[Abstract]:The bagged silt embankment is directly excavated and filled into the geotextile bag in the shoal area by filling apparatus. After the design strength is reached, the embankment is formed layer by layer after filling. This kind of silt with poor engineering properties is used as the main body of the embankment material, and the structure with structural strength is formed by combining the reinforcement and soil preservation of geotextile bags. At present, the technology is still in the field test stage, the theoretical research and the analysis of the deformation characteristics of the bag silt dyke are still very rare. This paper relies on the filling soil bag embankment test project in Jiangnan coastal reclamation area of Cangnan county, combined with reinforcing mechanism of reinforced soil, filling characteristics of geotextile bag and consolidation mechanism of soil. The finite element method for calculating the stability of reinforced soil is used to study the deformation characteristics of the bagged silt embankment. The concrete research results are as follows: (1) through the analysis of the strength source of the bagged silt, It is proposed that the early strength of bagged silt is mainly provided by geotextile reinforcement and soil conservation, and the later strength is mainly provided by the structural strength of consolidated soil. (2) the stress of geotextile bag is analyzed by means of the stress analysis of geotextile bag. The equations describing the geometric shape of the filling bag are established, and the numerical solution is obtained by using Matlab software. It is found that there is a logarithmic relationship between the height of filling bag and pump pressure, an exponential relationship between the width of contact surface and pump pressure, and a linear relationship between the tension of geotextile bag and pump pressure. Combined with the filling shape of large-scale geotextile bags in the field, a formula for calculating the tension of single-layer geotextile bags is established. The finite element model of the test section is established through the optimization analysis of an example. The simulation results of Hardening-Soil model and Mohr Coulomb model are compared and analyzed. The following conclusions are obtained: the vertical displacement of the base surface is downward in the width range of the embankment, and the vertical displacement increases gradually with the construction of the embankment, and beyond the width range of the embankment, There is a certain amount of uplift on the base surface, and with the construction of the foundation surface, the vertical displacement uplift of the base surface and the compression boundary point are gradually far away from the central axis of the embankment. The horizontal displacement of the base surface is distributed as a parabola with an opening down during the construction of the dam, and the increasing speed of the horizontal displacement within the range of 9 m from the central axis of the dam is relatively small. With the increase of section depth, the vertical displacement decreases gradually, and the vertical displacement of the same depth increases rapidly during the filling process. The horizontal displacement increases first and then decreases with the depth of the section, and the horizontal displacement at the same depth of the section increases with the filling. Using Hardening-Soil model to calculate the excess pore water pressure of soil mass dissipates rapidly, the pore water pressure after one year is 2.7 KN / m ~ (2), and the result of Mohr Coulomb model is 5.2 KN / m ~ (2), which is smaller than the measured value 4.4KN/m2. With the increase of the distance from the center axis of the dam, the axial force of the bag body decreases gradually, and the axial force of the bag body of the base surface increases slightly with the construction of the dam. And the increasing speed of axial force decreases gradually.) based on the finite element method of strength reduction, it is found that the reinforced soil strip method is not suitable to calculate the stability of the reinforced earth.
【学位授予单位】：辽宁工程技术大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U656

【参考文献】