Study on Earth Pressure Distribution Pattern of Ultra-deep Circular Shaft and Its Influential Factors

Taking the Shanghai deep tunnel storage project as engineering background, the mechanical parameters of deep soil layers are determined through geotechnical tests, and the earth pressure distribution pattern is obtained by a numerical simulation. On this basis, the influences of the insertion ratio, the stiffness of the retaining wall, the diameter of the shaft and thickness of the retaining wall on the earth pressure and lateral displacement are analyzed, respectively. The results show that when the insertion ratio is greater than 0.18, the increasement of the insertion ratio has no obvious effect on the lateral displacement and the earth pressure. When the elastic modulus is reduced by less than 50%, the lateral displacement increases slightly, which has a significant effect on the earth pressure above the excavation surface. Approximately 20 m below the excavation surface, the earth pressure and the shaft diameter are non-linearly negatively correlated, and the effect of increasing depth is weakened. The lateral displacement of the shaft increases with decrease in the wall thickness. However, it is not necessary to increase the thickness excessively due to the marginal effect.