1999 Volume 9 Pages 253-258
Recently, a new tunneling method, called Outer-shell-driven method, is spotlighted because it can produce large section effectively. Although Terzaghi's formula and total overburden pressure is widely used to design earth pressure in various conditions, they do not clarify the earth pressure mechanism under very closely constructed condition.
To make this point clear, authors have carried out series of centrifuge model tests using trap-door apparatus. An elasto-plastic finite element analysis also was carried out to simulate the centrifuge model test. Obtained results with respect to the application of the optimum construction order can be summarized as follows.
·As for the construction order for the case of very closely constructed 3 tunnels, earth pressure distribution is most stable (small) when the central tunnel is lastly excavated.
·An elasto-plastic finite element analysis with multi-yield surface model can give reasonable earth pressure estimation quantitatively.
