基于冻结黏土蠕变特性下井壁的受力特性研究

发布时间：2019-03-12 18:15

【摘要】：对于深厚冲积层的人工冻结法凿井施工,其安全性大部分决定于冻结壁的强度稳定性。因此,冻结壁的稳定性研究对工程的成功进展与经济效益具有十分重要的意义。近年来,研究者们提出了多种对于冻结壁在井壁砌筑前后的稳定性分析模型,大部分研究的即为冻结壁与井壁之间的相互作用关系,很少考虑到两者之间泡沫板的因素。泡沫板作为独立结构存在于冻结壁与井壁之间,其显著的改变了在混凝土井壁浇筑初期外壁与冻结壁之间的共同作用关系,改变了冻结压力的初期增长速率。本文基于对淮南顾北矿副井第一水平埋深处黏土层的研究,结合室内科学试验,理论计算推导,现场实时监测的方法,研究分析了井壁的受力特征及冻结壁、井壁、泡沫板的共同作用关系。室内试验主要针对冻土及泡沫板的物理力学性质进行分析,试验结果表明,冻结黏土的抗压强度、弹性模量、泊松比与温度呈线性变化的关系,并根据其蠕变试验参数得出本文需要的蠕变回归方程。聚苯乙烯泡沫板的试验包括单轴压缩试验及单轴蠕变试验,结果表明,泡沫板的压缩分为三个阶段,即直线变形阶段、曲线变形阶段和刚性阶段。泡沫板的三个不同阶段对于冻结壁的分析有着不同的作用。理论分析是基于冻结壁的黏弹塑性特征,采用西元流变模型进行研究,针对泡沫板的三个不同压缩阶段,推导建立出其冻结壁的冻结压力的计算公式。现场监测针对冻结压力、环向及竖向受力钢筋进行监测,得出其受力随着时间的变化规律。分析结果表明,对于稳定蠕变冻结壁,泡沫板的存在不仅降低了外壁的冻结压力,而且减小了冻结压力的增长速率,起到缓冲作用。本文针对于井壁、泡沫板及冻结壁的相互作用机理推导得出冻结压力的计算公式及其共同作用规律,对于外层井壁设计及冻结压力的增长规律和计算方法提供参考。
[Abstract]:The safety of artificial freezing method for deep alluvial layer is mainly determined by the strength stability of frozen wall. Therefore, the research on the stability of frozen wall is of great significance to the successful progress of the project and the economic benefit. In recent years, researchers have proposed a variety of stability models for frozen walls before and after wall masonry. Most of the researches are on the interaction between frozen walls and shaft walls, and the foam plate between them is seldom taken into account. Foam slab, as an independent structure, exists between freezing wall and shaft wall, which significantly changes the interaction between the outer wall and freezing wall at the initial stage of concrete wall pouring, and changes the initial growth rate of freezing pressure. Based on the study of the clay layer in the first horizontal depth of the auxiliary well of Gubei Mine in Huainan, combined with the scientific experiment in the laboratory, theoretical calculation and derivation, and on-site real-time monitoring, the stress characteristics of the shaft wall, the freezing wall and the shaft wall are studied and analyzed in this paper. The interaction of foam plates. The physical and mechanical properties of frozen soil and foam plate are analyzed in laboratory tests. The results show that the compressive strength, elastic modulus and Poisson's ratio of frozen clay vary linearly with temperature, and the experimental results show that the compressive strength, elastic modulus and Poisson's ratio of frozen clay vary linearly with temperature. According to the creep test parameters, the creep regression equation needed in this paper is obtained. The tests of polystyrene foam plate include uniaxial compression test and uniaxial creep test. The results show that the compression of foam plate is divided into three stages: straight-line deformation stage, curve deformation stage and rigid stage. Three different stages of foam plate play different roles in the analysis of frozen wall. The theoretical analysis is based on the viscoelastic-plastic characteristics of the frozen wall, and the rheological model is used to study it. According to the three different compression stages of the foam plate, the formula for calculating the freezing pressure of the frozen wall of the foam plate is derived and established. In-situ monitoring of frozen pressure, circumferential and vertical stress bars is carried out, and the variation rule of stress with time is obtained. The results show that the presence of foam plate not only reduces the freezing pressure of the external wall, but also decreases the growth rate of the freezing pressure and acts as a buffer for the stable creep frozen wall. In this paper, according to the interaction mechanism of well wall, foam plate and freezing wall, the formula of freezing pressure and its interaction rule are deduced, which can be used as reference for the design of outer shaft wall and the increasing law and calculation method of freezing pressure.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD265.32

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