In the deep sea, pipelines can undergo penetration during the laying process; therefore, lateral soil resistance is of great importance for shallowly embedded pipelines to maintain stability under high-temperature and high-pressure conditions; in this case, a pipeline may buckle due to release of stress, with a large amplitude over several pipe diameters. This paper reports on a series of large-scale plane strain model tests to study the lateral pipe-soil behavior in large-displacement conditions, and a fine sand collected from Bohai Gulf is chosen in view of Bohai sea geotechnical conditions. A 200 mm diameter model pipe section is integrated into a lateral pipe-soil interaction testing system to study the lateral soil resistance response as influenced by pipe weight W and relative embedment z/D. From the test results, three characteristic soil resistances are identified, derived from the soil resistance curves, namely, breakout resistance H-br, maximum resistance H-max, and residual resistance H(r)e(.) Experimental data indicate that lateral soil resistance depends on the soil passive pressure and berm resistance ahead of the pipe and that H-br is strongly coupled with H-max and H-re in deeper embedments. An observational test was conducted to study the mechanism of breakout resistance H-br. Simplifying H-br as the ultimate bearing capacity problem of a shallowly embedded cylindrical foundation under an inclined load, an upper-bound solution is proposed to calculate H-br, and both the failure mechanism and corresponding velocity are derived from experiments. Through comparison with existing calculation methods, the upper-bound solution is proven to provide an alternative prediction method for the breakout resistance H-br of pipeline in Bohai Gulf. (c) 2018 American Society of Civil Engineers.
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