Earth pressure acting on underground rigid pipes installed in a ditch with sheetpiling or under an embankment is studied by centrifuged models under various conditions. A rigid model pipe designed to measure both normal and tangential stresses on the pipe surface is buried in a dense or loose dry sandy ground without a concrete bedding. The measured stresses show that the total value and distribution of earth pressure are both affected considerably by the following factors: 1) methods of pipe

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... stallation, 2) roughness of pipe surface, 3) cover depth, 4) thickness of sand bedding, and 5) ditch width. The measured earth pressures and the bending moments of pipe section calculated from them show that the ordinary design method is dangerous in most cases because it ignores the earth pressure concentration onto the top or bottom of pipes.