Testing and Evaluation of Statically-Loaded Large Diameter Steel Pipe with Native Backfill Soils

A large diameter steel pipe was tested under static soil loads at the Center for Underground Infrastructure Research and Education (CUIRE) laboratory at UT Arlington. The 19.75 ft (6 m), 73.75-in. (1873 mm) outside diameter, steel pipe with diameter to thickness ratio (D/t) of 230 was placed inside a concrete load cell and currently is being backfilled with native clayey soils obtained from the Integrated Pipeline (IPL) project site in the North Texas. The backfill soil was first tested in the geotechnical laboratory and currently is being placed while compacted to one foot above the crown of the pipe. Additional load equivalent to nine feet of native soil will be added incrementally. Vertical pressures at crown and bottom of the pipe and horizontal pressures at the springline of the pipe will be recorded as loading is increased. Also, changes in vertical as well as horizontal diameters of the pipe will be measured during and after installation of the pipe. The purpose of the test is to study behavior of a large diameter steel pipe under native backfill and calibrate the related Finite Element Model (FEM). This paper describes details of the test and presents the preliminary results obtained. Based on the results of this test and accompanied FEM, appropriate recommendations for using native soils for trench backfill materials will be made, providing cost saving measures and sustainable construction methods.