Evaluation of reinforced concrete design for an underground outlet manifold in Shanxi Yellow River Diversion Project

In order to verify the design feasibility of the reinforced concrete lining of the outlet manifold in Shanxi Yellow River Diversion Project (YRDP), field investigations on rock mass deformability, in situ stress and hydraulic jacking measurements have been carried out. Based on the results obtained, 3-D FEM numerical analyses have been performed to calculate the stress distribution in a reinforced concrete lining under internal and external water pressure. Furthermore, the initial designed shape and steel ratio of concrete have been modified to satisfy the requirements for the limit crack width design criteria in China and decrease the tensile stress level in concrete. The new steel ratio of reinforced concrete has been calculated on the basis of the numerical results considering the modified shape of the outlet manifold. Both the owner and designer of YRDP have adopted the steel ratio of concrete in the working design and construction of the outlet manifold.