Experiences on Constructing Pipeline in the Swampy Forest Regions of Northeast China

During the construction of Harbin-Yilan Coal Gas Pipeline which goes through swampy forest regions, unfamiliar geological problems arise. In the course of problem-solving, valuable experiences are obtained. Introduced in the paper are the specific techniques applied in the engineering and construction of the project. Being of Class Ⅲ in stability and physical properties, the marshlands encountered consist of weak, movable peat of 2.4 m thickness. The frozen thickness of the swampy soil there is 0.8 m in winter months and thawing time comes 1~2 months later than in other areas. The areas around the marshland have a frozen depth of 1.8 m. As for the construction of the pipeline in the marshland, the following considerations are given: in order to facilitate construction and cut down construction cost, the section in the marshland shall be as short as possible and shall be so located as to pass through the areas having a thinner peat layer; construction road shall be built beforehand, and be duly checked and repaired after completion of the project; the upper peat in the pipeline bank protection shall be mixed with a certain amount of mineral soil so as to ease vegetation growth and prevent the peat from igniting in dry seasons.