EFFECT OF SOILCRETE CHARACTERISTICS ON SURFACE SETTLEMENT DURING TUNNELING IN VIETNAM

Excess surface settlement during construction of underground structures such as tunnels is concerned for historic buildings in big cities. A metro line No. 1 located at 20 m deep under the ground surface will be built in Ho Chi Minh City (HCMC) soon, and this metro crosses the City underneath many historic buildings. Reinforcing the soil mass surrounding the tunnel by soil-cement mixing (soilcrete) using jet grouting is considered a feasible solution to reduce surface settlement. However, appropriate characteristics of soilcrete for the HCMC’s geological conditions have not been thoroughly investigated. This study investigated the relationship between the characteristics of soilcrete (young modulus and thickness) and surface settlement at the city opera house, the historic building close to the metro, with a maximum allowable surface settlement of 10 mm.