Earth Pressures Acting on a Vertical Shaft in Multi-layered c - Φ Soils

摘要

It is one of the important tasks to evaluate the earth pressure acting on a vertical shaft when designing underground structures. The earth pressure acting on a vertical circular shaft is less than that of a retaining wall in plain strain condition due to three dimensional arching effect. Several researchers have suggested equations to estimate the earth pressure on the vertical circular shaft and verified them by conducting model tests. However, each of estimations shows different results and is not applicable to the vertical shaft in multi-layered soils and/or c - Φ soils. In this study, a new equation for estimating the earth pressure acting on the vertical shaft in c - Φ soils is proposed by modifying the equations suggested by other researchers. A parametric study is performed to investigate the significance of the cohesion when estimating earth pressures in vertical shafts. A method which can estimate the earth pressure on vertical shafts in layered soils is also proposed by assuming a failure surface in layered soils and using the modified equation. To verify the proposed methods, measured data were collected from three in-situ vertical shafts constructed in multi-layered c - Φ soils and compared with analytical solutions.