非均匀载荷下厚壁套管抗挤强度分析

非均匀地应力下套管柱强度设计须考虑非均匀载荷对其强度的影响，对此国内外众多学者进行了大量研究，并取得许多有益成果。但这些研究主要以径向的非均匀外载为边界载荷，没有考虑套管外壁受非均匀剪切力的作用；其次，对非均匀载荷下套管磨损、残余应力、不圆度和壁厚不均度等缺陷的影响未作考虑。为此，建立了厚壁套管受径向非均匀挤压和周向受非均匀剪切的力学模型，应用弹性力学逆解法进行了求解，分析了非均匀载荷下厚壁套管的应力分布规律。研究表明，非均匀载荷作用下沿最小水平地应力方向、套管的内壁是承载危险区。由此提出了非均匀载荷等效为均匀外挤载荷的方法，给出了含缺陷套管在非均匀载荷下抗挤强度的分析方法。

Collapse Strength Analysis for Thick-wall Casing under Non-uniform Loads

During strength design for casing strings used in non-uniform earth stress conditions,the effects of non-uniform loads on casing strength should be considered.Much research has been done in China and abroad on the problem,with many achievements attained.But most of those research selected the non-uniform radial loads as the boundary loads,neither considering the effects of non-uniform shear stress on the external casing wall,nor considering the effects of defects like casing wear,residual stress,ovality and non-uniform wall thicknesses.Therefore,in this paper a new analysis method is demonstrated.A mechanical model of thick wall casing is established which considers both the radial non-uniform squeezing and non-uniform circumferential shearing.The inverse elasticity method is used to analyze the stress distribution on the thick casing wall under non-uniform loads.The research results indicate that the internal casing wall is the critical loads area under non-uniform loads along the direction of the minimum horizontal earth stress.The method used to convert the non-uniform loads to equivalent uniform collapsing loads is set up,which has combined the collapse strength analysis method used for defective casing under non-uniform loads.