Passive earth pressure analysis of berm-retained excavation by upper bound method

The passive earth pressure should be known for the design of the berm-retained excavation, but no reasonable method for calculating the passive earth pressure has been found until now. According to the characteristics of the berm-retained excavation, the upper bound method based on the limit analysis theory is used to analyze the passive earth pressure provided by the passive soil area. To use the upper bound method, the vertical slice blocks are used to separate the passive soil area of the berm-retained excavation, and a compatible speed field is constructed. The optimization analysis technology is used to obtain the minimum upper bound solution. In order to test the rationality of the proposed upper bound solution, the passive earth pressures with different wall heights, geological parameters and other conditions are calculated by the proposed upper bound method, and the values and failure envelops are compared with the classical Rankine’s solutions. By employing the proposed upper bound method, the value of the passive earth pressure, the distribution of the passive earth pressure along the retaining wall, the failure envelops of passive soil area are studied under different parameters such as the berm top width, berm bottom width, berm height and berm slope coefficient. The influences of these parameters on the passive earth pressure and the failure envelops are discussed. The proposed method may lay the foundation for the design and optimization design of the berm-retained excavation in the future.