Stress and deformation characteristics of 'dual-purpose diaphragm wall' in metro stations

Under the condition of a 'dual-purpose diaphragm wall', the stress states and deformation laws are quite different from theoretical calculation results, the transfer and distribution law of the earth pressure between the sidewall of the station structure and diaphragm wall and the internal force of the station structure are uncertain. Due to the complex interaction between the exterior wall of the station and the diaphragm wall of the retaining structure, model tests and numerical simulations were used to research the stress and deformation characteristics of the compound wall system and composite wall system. The research results show that the compound wall system has a great load reduction effect and can effectively improve the stress state of the station structure. However, the internal force of the embedded segment of diaphragm walls was surprisingly increased. The earth pressure distribution rate (K) of the composite wall system and compound wall system increases nonlinearly along the direction of the foundation pit depth, while the distribution rates of the earth pressure in both systems are between 0.302∼0.557 and 0.239∼0.455. Compared with the composite wall, the reduction of the earth pressure in the compound wall system can be divided into three parts: the released part, the transferred part and the converted part accounting for 57%, 23% and 20% of the reduction of the earth pressure, respectively. It is recommended to give priority to the use of the compound wall system in the practice.