A Study on Earth Pressure of Shaft at Deep Underground

The depth of shafts tends to be deeper with that of shield tunnel because of the high utilization of underground space. On the other hand, there are few cases where shafts are constructed below 40m in depth. It is considered that the distribution of lateral earth pressure acting on the shafts, which is important for their design, may be different from that of shallow shafts. This research, therefore, investigates the distribution of deep shafts by means of three-dimensional Finite Element Method analysis. At first, this paper proposes the calculation method of lateral earth pressure of deep shafts, considering the process of both excavation and concrete placement. The stress around the shafts and lateral earth pressure acting on them are discussed under various ground conditions based on the calculation earth pressure. It is found that the lateral earth pressure is smaller than the earth pressure at rest when the elastic modulus is more than 1.0×10 ⁶kN/ m ², corresponding to soft rock.