Abstract: Based on the theory of multi-layer composed thick-wall cylinder, the elastic-plastic analysis of the casing-concrete sheath-rock combination was made. The equations for expressing the distribution of stress in the combination under elastic and elastic-plastic conditions were deduced. Also the characteristics of the force on the composed cylinder in the different working status such as elastic and plastic conditions were analyzed. The research results show that the ideal property of concrete sheath should be of high strength and low stiffness. The high strength of concrete sheath could resist higher loads of formation stress. At the same time, the low stiffness of that could reduce the transfer coefficient of stress greatly. From this point, the development of new type plastic concrete with high strongth and low stiffness should be enhanced.

Key words: casing, concrete sheath, combination, elastic-plastic analysis, plastic concrete

摘要： 基于多层组合厚壁圆筒理论,建立了套管、水泥环及井壁围岩组合体的力学模型,对均匀地应力作用下的组合体进行了弹塑性分析。推导了弹塑性条件下套管、水泥环及井壁围岩组合体的应力分布表达式,分析了线弹性、完全塑性等不同状态下组合体的受力特点,分别讨论了水泥环弹性模量对不同性质地层内套管外挤载荷的影响规律以及组合体的塑性极限问题。研究结果表明,水泥环的理想性能应为高强度、低刚度。其机理是利用高强度抵御地层载荷,利用低刚度降低载荷传递系数,从而达到保护套管的目的。由此,应加强新型高强低刚塑性水泥的开发。

关键词: 套管, 水泥环, 组合体, 弹塑性分析, 塑性水泥