METHOD OF LAYING PIPELINE IN PERMAFROST Russian patent published in 1995 - IPC

FIELD: pipe laying. SUBSTANCE: this method involves determination of borders of sections with grounds unstable at defrosting, surface laying of pipelines on ground base on this section with fixing the pipeline at section borders by embankments or standard reinforced concrete weights. The section is diked over perimeter with formation of hydraulic fill graded section and positive buoyancy is given to pipeline. If length of pipe is not sufficient for rising to surface, traction means is used to make pipeline curvilinear in plan. Then pulp is delivered to hydraulic fill graded section and pipeline floats up under the action of buoyant force and attains upward convex shape thanks to which tension stresses are built in pipeline and artificial foundation is formed under pipeline by precipitation of solid fraction of pulp. After lifting the pipeline to required height its positive buoyancy is eliminated and ground covering is formed over pipeline by hydraulic filling. In service warming and setting of permafrost takes place, and pipeline is set in designed position. EFFECT: enhanced operation reliability, cut down amount of permafrost to be dug out. 3 cl, 5 dwg