INFLUENCE OF GROUND IMPROVEMENT ON DEFLECTIONS OF DIAPHRAGM WALLS IN DEEP EXCAVATIONS

In order to reduce wall movements induced by deep excavations in soft clay, grouted slabs are frequently adopted to brace diaphragm walls. The effectiveness of a slab will depend on the stiffness of the slab which is proportional to the thickness and the Young's modulus of the slab and is inversely proportional to the span of the slab. Numerical analyses indicate that, for an excavation carried out to a depth of 18.5 m in the Taipei Basin, the maximum wall deflection of 1 m diaphragm walls was reduced by 38%, 56% and 63% by installing grouted slabs of 1 m, 5 m and 12 m in thickness and 27 m in span below the formation level.