| 摘要 |
PROBLEM TO BE SOLVED: To provide an open shield tunneling method which can prevent natural ground cave-in at a cutting face at the time of excavating the cutting face, to thereby allow discharge of excavated earth and advancement of an open shield machine under stable conditions. SOLUTION: The open shield tunneling method is carried out by using the open shield machine 1 which has its front, rear, and top surfaces opened, and consists of the following steps. In the first step, propelling jacks 2 are arranged along inner surfaces of right and left side wall plates 1a of the open shield machine 1, and earth and sand at the front of the open shield machine 1 are excavated and discharged from a front opening or a top opening. In the second step, the propelling jacks 2 are extended to advance the open shield machine 1 by using a concrete caisson 4 formed of right and left side plates and upper and lower floor slabs, as reaction. In the following step, the propelling jacks 2 are contracted in a tail portion 1c of the open shield machine 1, and another concrete caisson 4 is hung down from above at the rear of the propelling jacks 2. Then, the above steps are repeatedly carried out as appropriate, to thereby serially bury the concrete caissons 4. According to the open shield method thus carried out, in the step of excavating and discharging earth and sand at the front, a liquid stabilizer is injected into the cutting face 14 to stabilize the same, and then the earth and sand at the cutting face is excavated and discharged.
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