灌注桩水泥浆渗透规律及对承载力影响分析研究

发布时间：2018-05-29 11:40

本文选题：灌注桩 + 桩土界面　；参考：《东北大学》2013年硕士论文

【摘要】：灌注桩施工过程当中,混凝土水泥浆在桩周土体中有比较明显的渗透现象,这一现象将对桩土界面产生一定的影响。在目前的数值模拟计算当中,大多数情况均未考虑到渗透作用对桩土界面的影响,这样的处理模糊了桩基础实际的承载机理,使得计算结果不够精确。虽然现在国内外有了一定的研究,但仍未形成比较完善的理论体系,对不同因素影响下渗透作用的变化规律也未有明确的阐释。本文采用试验手段,根据工程经验选取了灌注高度、混凝土水灰比、初始孔径这三点作为试验的影响因素来对渗透规律进行探究,首先证明渗透现象的存在,并在此基础上给出渗透体的范围及强度等取值规律,为计算时模型的参数选取提供依据。通过桩周土孔隙水压力值、桩径变化、桩体渗透体强度、硬度这四方面的分析,研究了不同因素作用下的变化规律。首先根据桩周孔隙水压力增加及成型桩体的桩径增加证明渗透现象是一定存在的,根据桩体渗透体强度、硬度分析,明确渗透体在有限元计算时何时予以考虑。其次,通过对两个方向上不同位置的孔隙水压力值的分析得出,沿桩身径向和切向的孔隙水压力值变化规律；通过9组正交试验中桩径增加量的分析得出桩径变化规律,结果显示水灰比和灌注高度是桩径变化的主要影响因素；通过对渗透体化学成分的分析,得出了不同因素影响下渗透体强度的变化规律,分析得出水灰比是此项的显著性影响因素；通过显微维氏硬度测试法,得出了水灰比对渗透体硬度的下降影响最大。为计算桩基础极限承载力时参数的选取提供了依据。最后,通过对大直径人工挖孔灌注桩采用荷载增量法、强度折减法的极限荷载计算,验证了在计算桩基础极限承载力时考虑渗透作用的必要性及这种算法的可行性。
[Abstract]:During the construction of cast-in-place pile, concrete cement slurry has obvious seepage phenomenon in the soil around the pile, which will have a certain influence on the pile-soil interface. In the present numerical simulation calculation, the influence of permeation on the pile-soil interface is not considered in most cases, so the actual bearing mechanism of the pile foundation is blurred by this treatment, which makes the calculation results not accurate enough. Although there has been some research at home and abroad, a relatively perfect theoretical system has not been formed, and the law of osmotic change under the influence of different factors has not been clearly explained. In this paper, according to the engineering experience, we select three factors as the influencing factors, such as the pouring height, the concrete water-cement ratio and the initial pore size, to explore the permeability law. First, it is proved that the permeation phenomenon exists. On this basis, the range and strength of the osmotic body are obtained, which provides the basis for the parameter selection of the model. Through the analysis of pore water pressure of soil around pile, pile diameter change, the strength and hardness of percolation of pile body, the variation law of soil pore water pressure under the action of different factors is studied. Firstly, according to the increase of pore water pressure around the pile and the increase of the diameter of the formed pile, the seepage phenomenon is proved to exist. According to the analysis of the strength and hardness of the percolation of the pile, it is clear when the seepage body will be considered in the finite element calculation. Secondly, through the analysis of pore water pressure in different positions in two directions, the variation law of pore water pressure along the radial and tangential direction of pile body is obtained, and the variation law of pile diameter is obtained by analyzing the increment of pile diameter in nine orthogonal experiments. The results show that the water-cement ratio and the pouring height are the main influencing factors of the pile diameter change, and through the analysis of the chemical composition of the osmotic body, the change law of the osmotic strength under the influence of different factors is obtained. It is found that the water-cement ratio is the significant factor, and the water cement ratio has the greatest influence on the hardness of the permeate by the microhardness testing method. It provides a basis for the selection of parameters when calculating the ultimate bearing capacity of pile foundation. Finally, by using load increment method and ultimate load calculation of strength reduction method, the necessity and feasibility of considering seepage in calculating ultimate bearing capacity of pile foundation are verified.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU753.3

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