L51571 Pipe-Soil Interaction Tests on Sand and Soft Clay

Abstract

This project was performed to establish a basis for developing pipe-soil interaction models suitable for PRCI's pipeline design program: "PIPEDYN". Full-scale pipe-soil tests on loose and dense sand and soft clay were performed at the Norwegian Hydrotechnical Laboratory, affiliated with SINTEF. The program tested soil resistance to lateral motions of full-scale (0.5 m and 1.0 m OD) pipe sections on loose and dense sand and soft clay. A test rig was used with a soil flume 12.5 m long, 1.8 m wide, and 0.6 m high, and containing 13.5 m3 of sand or soft clay. Three control signals were applied to the test pipes: simple breakout, regular oscillatory tests and breakout, and random tests with force time histories. The parameters considered were pipe diameter, pipe weight, pipe oscillations, and oscillation amplitude. A total of 110 tests were performed in 25 test flumes (13 preliminary and 12 main) on loose sand, three test flumes on dense sand and ten test flumes on soft clay. Forty-five preliminary and 32 main tests were performed in 25 loose sand flume preparations, whereas 8 main tests were performed in 3 dense sand flumes and 25 main tests in 10 soft clay flumes, for a grand total of 110 pipe-soil tests in 38 soil flumes. Special plate and cone penetration tests were also performed as part of the soil bed tests. Based on the results of the tests, pipe penetration appears to be the most important factor influencing lateral soil resistance. Also, the soil resistance in loose sand was generally higher than in dense sand due to larger pipe penetration and an accordingly higher lateral earth pressure.