Research On The Technology Of Horizontal Directional Drilling Of Oil And Gas Pipeline Crossing Large And Medium-sized River

With the increasing demand on the environmental protection and construction culturally,no-dig (trenchless) technology,accepted and appreciated by the people in all fields,has been made a great development in the past few years.At present,it has been regarded as a very prosperous branch of the construction by the international civil engineering .Based on the analysis about all kinds of no-dig methods,the horizontal directional drilling(HDD) technology,the most efficient and prosperous categories, are selected by the author as research target,the author gives a systematical research on HDD by means of experiment and engineering practice in the complicated condition .The main contents are as following:1. Analysis the application range of HDD while drilling through large and medium-sized rivers,meanwhile, analyzed and classified the main characteristics of fluvial facies .Directing at rock strata,sandy soil strata and cobble gravelly strata,summarizing technical problems of HDD under the conditions of complicated strata,and predicted adverse effects may occur in construction process.2. Based on analyzing and comparison of several kinds of theoretical formula and analyzing the composition and influence factor,mainly targeted at unloading arch soil stress calculation, pure flotation calculation and traveler sprinkling calculations which commonly used in oil and gas pipeline pull strength calculation,from basic ideas,calculation,range application to discriminate.3. Improves a common formula used in calculating pull strength .and the theoretical results are compared with the actual result measured in the field.4. Using the Finite Element Analysis tool ANSYS to create the contact pair between the soil and pipeline. Some factors and parameters effect, such as the force of pulling, the diameter of pipe and the thickness of pipe and the material of soil, etc are analyzed through an example. Some conclusions are drawn. Such as ,the response of the pipeline is unsymmetrical,pipeline is easy damaged at the position of the head of pulling and the Corner of drilling. In the end,the existing problems which need to be studied are discussed briefly and the promising possible future research directions on the subject are suggested.