The authors conducted trapdoor tests to examine the distribution of loosening earth pressure, which occurs in a series of ground excavation by Element Jacking Method. Consequently, the entire overburden pressure caused by the foregoing method was identical to those by single excavation; however, the distribution of the earth pressure indicated different results. Taking advantage of the experimental results, we accordingly developed a new simplified method to calculate the loosening earth pressure based on the foregoing jacking method. The method comprised of Terzaghi’s theory and Coulomb’s theory, not having any unknown quantity, thereby design of linings could be readily applicable.

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