DISCUSSION ON THE LIMIT STANDARD OF CRACK RESISTANCE DESIGN OF CONCRETE DIAPHRAGM WALL IN SOFT SOIL

摘要

In order to define authentic law and magnitude of internal force of ultra-deep excavation concrete diaphragm walls, the author, through analyzing a great of field datum and using back analysis method, finds out stress laws of concrete diaphragm wall and brings forward a model of internal force envelope diagram on the basis of quantization and comparison. Then it analyses the relationship between crack control limit value and ratio of reinforcement. The author found that the design of diaphragm wall is conservative, because the stress of reinforcing steel and the moment of wall are less than the design value from the survey results of some excavations. The paper thinks that the conservative design is caused by the allowable width of structure crack w_(lim) = 0.2. It is concluded if the allowable widths of structure crack broaden to w_(lim) =0.3, the ratio of reinforcement will decrease and project invests will be controlled, at the same time the safety of the excavation is guaranteed.