摘要
为了研究石油套管柱的力学性能,采用统一强度理论,合理考虑中间主应力效应和材料拉压比的影响,推导了石油套管柱的单轴抗挤强度、双轴抗挤强度和三轴抗挤强度计算公式,建立了石油套管柱双轴抗挤强度和三轴抗挤强度与单轴抗挤强度的关系,并分析了材料的拉压比、中间主应力效应、径厚比、压缩屈服强度、荷载大小和荷载工况等因素对不同类型抗挤强度的影响特性。研究结果表明:材料的拉压强度不等特性(SD效应)对石油套管柱的单轴抗挤强度、双轴抗挤强度和三轴抗挤强度均有显著影响,材料拉压比越大,套管柱的单轴抗挤强度越小,双轴抗挤强度越大,而三轴抗挤强度与双轴抗挤强度的差值和材料拉压比的关系与外荷载有关;中间主应力效应对石油套管柱的单轴抗挤强度、双轴抗挤强度和三轴抗挤强度也有显著影响,随统一强度理论参数b值的增加,套管柱的单轴抗挤强度和双轴抗挤强度不断增大,考虑中间主应力效应可以充分发挥材料的自承载能力和强度潜能,具有可观的经济效益;径厚比、压缩屈服强度、荷载大小和荷载工况对套管柱的单轴抗挤强度、双轴抗挤强度和三轴抗挤强度也具有一定影响。该结果适用于具有SD效应和中间主应力效应的材料,并将多种屈服准则下石油套管柱的单轴抗挤强度、双轴抗挤强度和三轴抗挤强度表达式分别统一起来,具有广泛的适用性,可为石油套管柱的抗挤强度设计提供借鉴。
In order to study mechanical properties of petroleum casing, and take impacts of the intermediate principal stress effect, tension/pressure ratio of materials into logical consideration this research deduced computational formulas of uniaxial, biaxial and tri- axial collapsing strengths of petroleum casing according to unified strength theory. In addition, relational expressions of biaxial or triaxial collapsing strength of petroleum casing with uniaxial collapsing strength were established to examine influences of various fac- tors on different collapsing strengths, which include the intermediate principal stress effect, tension/pressure ratio of materials, di- ameter/thickness ratio, compression yield strength, load magnitude and load conditions. The results showed that the strength dis- parity (SD) effect of materials has a significant influence on the uniaxial, hiaxial and triaxial collapsing strengths of petroleum casing strings. For instance, the greater the tension/pressure ratio of materials is, the smaller the uniaxial collapsing strength of casing strings is, the greater the biaxial collapsing strength is. The correlation of the difference between the triaxial and biaxial collapsing strengths with the tension/pressure ratio is related to the external load. The intermediate principal stress effect also shows a signifi- cant impact on the uniaxial, biaxial and triaxial collapsing strengths of petroleum casing strings. With an increase in parameter of the unified strength theory, the uniaxial and biaxial collapsing strengths of casing strings will increase incessantly, which can bring great economic benefits because the intermediate principal stress effect can bring the self-bearing capacity and strength potential of materi- als into a full play. Moreover, the diameter/thickness ratio, compression yield strength, load magnitude and load conditions of mate- rials also have a certain influence on the uniaxial, biaxial and triaxial collapsing strengths of petroleum casing strings. The computa- tional formulas of this paper are suitable for all kinds of materials which have the SD effect and intermediate principal stress effect. As these formulas have, respectively, unified various expressions of the uniaxial, biaxial and triaxial collapsing strengths of petrole- um casing strings proposed on the basis of different yield criteria, their applicability is broader, therefore, they are of great signifi- cance in collapsing strength design for petroleum casing strings.
出处
《石油学报》
EI
CAS
CSCD
北大核心
2013年第5期969-976,共8页
Acta Petrolei Sinica
基金
国家自然科学基金项目(No.41202191)
中国博士后科学基金项目(2012M520079
2013T60868)
教育部博士点基金项目(20110205130001
20120205120001)
陕西省自然科学基金项目(2011JM7002)资助
关键词
统一强度理论
石油套管柱
抗挤强度
SD效应
中间主应力
unified strength theory
petroleum casing string
collapsing strength
SD effect
intermediate principal stress