Abstract
Rinkai Oimachi station was constructed by removing part of segments of shield tunnel and excavate the soil between tunnel and the adjacent shaft. As the lower tunnel was located in the Tokyo gravel layer which pore water pressure was greater than 300kN/m2, cutoff measure for this layer was the key for the safety construction. Chemical grouting was adopted due to the restriction of construction period. The grouting work was planned in three steps, first, second and complementary grouting. Resistivity tomography and so on were carried out to confirm the effect. The result was satisfactory and the volume of complementary grouting was less than 1/10 of first one. In addition, deep well was performed to reduce the risk of leakage and safety construction was achieved.
