Abstract Controlling the lateral deformation of retaining wall is one of the hot issues in deep excavation，and the lateral deformation during bottom excavation occupies considerable proportion of that in the whole excavation works. Based on measured data and practical work of a metro station construction in Shanghai City，lateral displacement with different soil exposure times during excavation is analyzed. As a result，the exposure time of bottom soil has notable influence on the retaining wall¢s lateral deformation during the periods of both soil exposure and bottom excavation. As the increasing of soil exposure time，incremental lateral deformation of retaining wall on the stage of bottom excavation construction can reach 30 percent of the total displacement. Shortening soil exposure time is the key point of controlling lateral displacement on the stage of bottom excavation. In addition，concrete cushion plays critical bracing function on controlling lateral deformation of the retaining wall，which is similar to the reinforcement concrete bottom plate. Accelerating the construction of concrete cushion as soon as possible can make full use of bracing effect on controlling the lateral deformation of retaining wall. Bracing effect of concrete cushion depends on several factors，such as concrete cushion¢s strength，stiff and flatness. The effect can be weakened with debasement of concrete cushion¢s entirety. Some proposals for lateral deformation controlling during bottom excavation of deep pit are offered. Shortening bottom excavation soil exposure time and bottom construction time are favorable of lateral deformation controlling. Increasing concrete cushion¢s entirety and promoting construction progress of the reinforcement concrete bottom plate can reduce retaining wall¢s lateral deformation on the excavation stage. The results can provide references to other similar deep excavation engineering.
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Received: 29 January 2007
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