4.4.4 Diaphragm walls

The design of a diaphragm wall includes specifying the wall thickness and the reinforcements.The thickness is usually determined according to the results of the stress analysis，the deformation analysis，and the feasibility of detailing of concrete reinforcements.According to the experience of excavations in Taipei，the thickness of a diaphragm wall can be assumed to be 5% He（He is the excavation depth）in the preliminary design.

The design of reinforcements usually follows the widely used strength design method（the LRFD method）.The major items of design include the vertical main reinforcement，the horizontal main reinforcement，the shear reinforcement，and the lap splice length and development length of the reinforcement.The design of reinforcements of a diaphragm wall is based on the bending moment and shear envelope obtained from the stress analysis.For the detailed design process，please refer to the ACI code.