泥浆颗粒级配和地层孔径对泥水盾构泥膜形成的影响

发布时间：2018-04-29 06:15

本文选题：盾构隧道 + 泥水盾构　；参考：《中国公路学报》2017年08期

【摘要】：为了研究影响泥水盾构开挖面上泥膜形成质量的主要因素,通过三维颗粒流程序(PFC3D)模拟了不同颗粒级配和不同密度的泥浆在泥浆压力作用下向不同孔径的地层中移动和泥膜的形成情况。模拟结果表明:增大泥浆d_(85)和泥浆密度有助于在地层表面形成良好的泥膜;地层孔径较大时,不易形成良好的泥膜,需要选择与之匹配的泥浆颗粒级配和泥浆密度。数值模拟得到了与室内试验一致的3种泥浆颗粒堆积形态:泥皮型、泥皮+渗透带型和渗透带型。当泥浆d_(85)与地层平均孔径Dp的比值d_(85)/D_p和泥浆密度较大时,堆积形态为泥皮型;当d_(85)/D_p和泥浆密度较小时,堆积形态为渗透带型。3种泥浆颗粒堆积形态中地层水压力从大到小排序为渗透带型、泥皮+渗透带型、泥皮型,而地层水平应力从大到小排序为泥皮型、泥皮+渗透带型、渗透带型。泥膜的支护机理为由泥浆和地层的水压力差对泥膜的作用力平衡地层的侧向土压力来保持开挖面的稳定。因此,形成的泥膜质量越好,泥膜的渗透系数就越小,泥膜处产生的水压力梯度就越大,可以提供的维持开挖面稳定的水平有效应力也就越大。影响泥膜形成质量的主要因素是泥浆颗粒级配、泥浆密度和地层孔径;在泥水盾构施工时,可以根据地层孔径调整泥浆颗粒级配和泥浆密度,使开挖面上能够形成良好的泥膜,从而保证开挖面的稳定。
[Abstract]:In order to study the main factors that affect the quality of mud film formation on the dredging surface of mud water shield, The movement of mud with different particle gradation and density to different pore size formation and the formation of mud film under mud pressure were simulated by using the three-dimensional particle flow program (PFC3D). The simulation results show that increasing mud density and mud density can help to form a good mud film on the formation surface, and when the pore diameter of the formation is larger, it is difficult to form a good mud film, so it is necessary to select the matching mud particle gradation and mud density. Numerical simulation results show that three kinds of mud particle accumulation patterns are consistent with the laboratory tests: mud crust, mud permeable zone and permeable zone. When the ratio of mud to average pore diameter (d_(85)/D_p) and mud density is high, the accumulation pattern is mud crust type, and when d_(85)/D_p and mud density are small, The formation water pressure is classified from large to small to permeable zone type, mud crust type, and horizontal stress from big to small is mud crust type, mud skin permeable zone type. Osmotic zone type. The supporting mechanism of mud film is that the interaction force between mud and formation water pressure balance the lateral earth pressure of formation to maintain the stability of excavating surface. Therefore, the better the quality of the sludge membrane is, the smaller the permeability coefficient is, the greater the water pressure gradient in the mud membrane is, and the greater the horizontal effective stress can be provided to maintain the stability of the excavated surface. The main factors affecting the quality of mud film formation are slurry particle gradation, mud density and formation pore diameter. In mud shield construction, mud particle gradation and mud density can be adjusted according to formation pore diameter, so that good mud film can be formed on excavated surface. So as to ensure the stability of the excavated surface.
【作者单位】：天津大学建筑工程学院;天津大学滨海土木工程结构与安全教育部重点实验室;河海大学岩土力学与堤坝工程教育部重点实验室;
【基金】：国家重点基础研究发展计划(“九七三”计划)项目(2015CB057803) 国家自然科学基金项目(51509181) 天津市应用基础与前沿技术研究计划项目(15JCQNJC43800)
【分类号】：U455.43

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