硬岩中冻结管径向失稳规律研究
发布时间：2018-11-09 07:42
【摘要】：在冻结法施工中,冻结管的安全稳定是影响冻结施工顺利进行的关键性因素。近年来,在硬岩地层冻结法凿井工程中发生了多起冻结管径向失稳挤扁破坏事故,导致冻结工程失败,对工程进度和效益造成了较大影响。针对这一现象,本文通过解析分析、数值模拟和物理模拟相结合的方法对硬岩地层中冻结管径向失稳的机理和规律进行全面的研究。首先,建立“冻结管-已冻泥浆-未冻泥浆-围岩”多层筒力学模型,推导未冻泥浆区冻胀力的解析解,并获得未冻区冻胀力与泥浆冻结壁厚度及各影响因素的变化关系。其次,基于单管温度场、单管径向屈曲和岩石拉裂问题的模拟,对理想情况下受冻胀力作用的冻结管径向失稳问题进行数值计算。在考虑围岩水压致裂的情况下,掌握了冻结过程中泥浆冻结壁厚度、冻胀力变化和冻结管径向屈曲变形的规律,获得了相关因素与环形空间冻胀力和冻结管径向失稳的关系。数值计算结果表明:已冻泥浆的弹性模量、泥浆孔隙率和地层深度为影响环形空间冻胀力的主要因素,而地层初始水平应力为影响冻结孔内壁环向应力的关键因素;具体表现为已冻泥浆弹性模量越大、泥浆孔隙率越大、地层深度越大时未冻泥浆区冻胀力越大,而地层初始水平应力越大时冻结孔内壁环向应力越小。再次,采用自行设计的试验装置进行物理模型试验,对不同规格冻结管在不同工况下的冻结试验,获得了环形空间冻胀力变化规律和冻结管径向失稳规律。试验结果表明:冻结管径向失稳现象可分为加压、冷缩、冻胀和破坏四个阶段,获得的径向失稳临界荷载与水压试验和数值模拟结果相差较小,且失稳波数同特征值屈曲计算模态图;有压冻结工况时环形空间产生的冻胀力明显大于无压冻结工况;偏心情况时环形空间产生的冻胀力略大于理想情况,同一层位不同方位测点受力存在一定不均。最后,综合上述研究成果,总结得到,对比冻结管径向失稳和硬岩内侧拉裂的时间点,若硬岩拉裂先于冻结管失稳,冻结管处于安全状态;若冻结管失稳先于硬岩拉裂,则冻结管破坏。
[Abstract]:In freezing construction, the safety and stability of freezing pipe is the key factor affecting the smooth progress of freezing construction. In recent years, there have been many accidents of freezing pipe diametral instability, flattening and flattening in hard rock formation freezing method, which lead to the failure of freezing project, which has a great influence on the progress and benefit of the project. In view of this phenomenon, the mechanism and law of diametral instability of frozen pipes in hard rock strata are studied comprehensively by means of analytical analysis, numerical simulation and physical simulation. Firstly, a multi-layer mechanics model of "frozen pipe, frozen mud, unfrozen mud and surrounding rock" is established, and the analytical solution of frost heave force in unfrozen mud region is derived, and the relationship between frost heave force in unfrozen area and the thickness of frozen mud wall and the influence factors are obtained. Secondly, based on the simulation of single tube temperature field, single tube radial buckling and rock crack, the numerical calculation of the diametral instability of frozen pipe subjected to frost heave force is carried out. Considering the hydraulic fracturing of surrounding rock, the thickness, frost heave force change and diameter buckling deformation of frozen pipe during freezing process are grasped, and the relationship between relevant factors and frost heave force in annular space and diameter instability of frozen pipe is obtained. The numerical results show that the elastic modulus of frozen mud, mud porosity and formation depth are the main factors affecting the frost heave force in annular space, and the initial horizontal stress is the key factor to influence the circumferential stress of the inner wall of the frozen hole. The concrete performance is that the greater the elastic modulus of frozen mud, the greater the porosity of the slurry, the greater the formation depth, the greater the frost heave force in the unfrozen mud zone, and the smaller the circumferential stress of the inner wall of the frozen hole is when the initial horizontal stress of the formation is greater. Thirdly, the physical model test was carried out by using the self-designed test device, and the freezing test of different specification freezing pipes under different working conditions was carried out, and the variation law of frost heave force in annular space and the radial instability law of freezing pipe were obtained. The experimental results show that the radial instability of frozen pipes can be divided into four stages: compression, cold shrinkage, frost heave and failure, and the difference between the critical radial buckling load and the results of water pressure test and numerical simulation is small. And the instability wave number is the same as the eigenvalue buckling calculation modal diagram; The frost heaving force in annular space under pressure freezing condition is obviously larger than that in non-pressure freezing condition, and the frost heave force in annular space under eccentricity is slightly larger than that in ideal condition. Finally, by synthesizing the above research results, it is concluded that the frozen pipe is in a safe state if the hard rock fracture is prior to the freezing pipe instability, compared with the time points of the diametral instability of the frozen pipe and the inner tensile crack of the hard rock. If the freezing pipe is unstable before the hard rock crack, the freezing pipe will be destroyed.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD265.3
本文编号：2319785
[Abstract]:In freezing construction, the safety and stability of freezing pipe is the key factor affecting the smooth progress of freezing construction. In recent years, there have been many accidents of freezing pipe diametral instability, flattening and flattening in hard rock formation freezing method, which lead to the failure of freezing project, which has a great influence on the progress and benefit of the project. In view of this phenomenon, the mechanism and law of diametral instability of frozen pipes in hard rock strata are studied comprehensively by means of analytical analysis, numerical simulation and physical simulation. Firstly, a multi-layer mechanics model of "frozen pipe, frozen mud, unfrozen mud and surrounding rock" is established, and the analytical solution of frost heave force in unfrozen mud region is derived, and the relationship between frost heave force in unfrozen area and the thickness of frozen mud wall and the influence factors are obtained. Secondly, based on the simulation of single tube temperature field, single tube radial buckling and rock crack, the numerical calculation of the diametral instability of frozen pipe subjected to frost heave force is carried out. Considering the hydraulic fracturing of surrounding rock, the thickness, frost heave force change and diameter buckling deformation of frozen pipe during freezing process are grasped, and the relationship between relevant factors and frost heave force in annular space and diameter instability of frozen pipe is obtained. The numerical results show that the elastic modulus of frozen mud, mud porosity and formation depth are the main factors affecting the frost heave force in annular space, and the initial horizontal stress is the key factor to influence the circumferential stress of the inner wall of the frozen hole. The concrete performance is that the greater the elastic modulus of frozen mud, the greater the porosity of the slurry, the greater the formation depth, the greater the frost heave force in the unfrozen mud zone, and the smaller the circumferential stress of the inner wall of the frozen hole is when the initial horizontal stress of the formation is greater. Thirdly, the physical model test was carried out by using the self-designed test device, and the freezing test of different specification freezing pipes under different working conditions was carried out, and the variation law of frost heave force in annular space and the radial instability law of freezing pipe were obtained. The experimental results show that the radial instability of frozen pipes can be divided into four stages: compression, cold shrinkage, frost heave and failure, and the difference between the critical radial buckling load and the results of water pressure test and numerical simulation is small. And the instability wave number is the same as the eigenvalue buckling calculation modal diagram; The frost heaving force in annular space under pressure freezing condition is obviously larger than that in non-pressure freezing condition, and the frost heave force in annular space under eccentricity is slightly larger than that in ideal condition. Finally, by synthesizing the above research results, it is concluded that the frozen pipe is in a safe state if the hard rock fracture is prior to the freezing pipe instability, compared with the time points of the diametral instability of the frozen pipe and the inner tensile crack of the hard rock. If the freezing pipe is unstable before the hard rock crack, the freezing pipe will be destroyed.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD265.3
【参考文献】
相关期刊论文 前4条
1 童文林;;大直径瓦斯管径向稳定性力学性能数值分析[J];山西建筑;2007年26期
2 谭一中,胡积龄,杨若琼,潘玉华;水电站埋藏式钢管外压失稳的试验研究[J];水力发电学报;1985年03期
3 蔡晓闻;高连新;常龙;杜建青;;石油套管几何缺陷对抗挤强度的影响[J];石油矿场机械;2009年02期
4 韩建增,李中华,于百勤,练章华,施太和;几何缺陷对套管抗挤强度影响的有限元分析[J];天然气工业;2004年05期
，本文编号：2319785
本文链接：https://www.wllwen.com/kejilunwen/kuangye/2319785.html
