Monitoring And Analysis Of A Deep Circular Excavation In Small Diameter

The earth pressure on the circular retaining structure is reduced by the soil arching effect, and the high compression resistance character is fully used. As a result, more and more circular retaining structures are applied in the excavation. This thesis takes a deep circular excavation (5m in diameter, 35m in depth) as an example. Observed Data is collected to analyze the stress and deformation of the structures and the environment. And finite element analysis method is also adopted to study the stress and deformation characters of the structures and soil.An effective monitoring system is established to observe the construction and the environment. Monitoring objects conclude the lateral displacement and the settlement of the diaphragm walls and soil, the rebar stress in the walls and the top ring beam and the pore pressure in soil. Results show that, the lateral displacement of walls is small, effectively constrained by the ring beam located at -16m. The influence on environment is also small. The earth pressure and the pore pressure keep stable, mainly affected by dewatering of confined water. The top ring beam is compressed.The finite element analysis uses Modified Cam Clay Model as the constitutive model of soil. The soil is simulated by 8-node linear brick element, walls are simulated by 4-node shell element, and ring beams are simulated by 3-dimentional beam element. Results turn out that, heave of pit base is small. The lateral earth pressure is reduced after the excavation. The max lateral displacement of walls appears at the place with max positive bending moment. Computed results of lateral displacement of walls, lateral displacement of soil and the lateral earth pressure are compared with the...