Keller providing alternative retaining solution that resulted cost-savings and time-savings for client. The retaining structure completed ahead of project schedule enabling excavation works to start early. Deepest drilling depth (68m) throughout KVMRT line 2 project for rock fissure grouting technique.
Intervention Shaft 2 (IVS 2) is part of the MRT 2 tunnel project, approximately 17m in diameter and 57.5m deep. Keller was engaged to construct the retaining structure of the shaft based on the alternative Deep Soil Mixing (DSM) method we proposed. Rock Fissure Grouting was also carried out to improve the ground condition, generally underlain by limestone formation with overburden soil.
Apart from boulders, rebar and concrete slab that needed to be removed prior to the start of DSM work, multiple and repetitive cavities were encountered. The low slump grout specified for cavity filling did not flow into the cavities as expected. Our team proposed to an alternative cement mortar with higher slump value and a bentonite to improve the flow properties.
Keller proposed a more efficient alternative retaining solution using DSM instead of the conforming Secant Bored Pile design. To minimize the ground water inflow, Rock Fissure Grouting work was carried out as well as rock probing to have a better visualization of the ground condition and the rock profile. This enabled client to implement preventive measures before the start of excavation work.