Research On The Technique Of Diaphragm Wall Treatment And Its Application In The Metro Station Project

The Hongxing Road Station Project of Tianjin Metro Line 2 is located at the joint of Huachang Street and Hongxing Road and nearby Shunchi Bridge. The construction site used to be apartment buildings. The superstratum consists mostly of miscellaneous fill and waste building foundations and substratum consists mainly of sandy clay and sand. Diaphragm wall, which is a kind of highly mechanized complex construction technique affecting greatly on subsequent work, is adopted as the retaining structure of Hongxing Road Station. Its construction is an important subsection of this project due to the great influence of its quality on the safety of deep excavation and main structure.This paper discussed the internal force of diaphragm wall with m-method , designed reasonably each parameter of diaphragm wall, considered the circumstance of project, economic benefits, influence on surrounding circumstance during construction period, schedule arrangement of construction, carried out comparison analysis of excavation and main structure after considering fully the characteristic of site, building, and geological condition by combining this project. Design scheme, construction quality and safety control scheme of diaphragm wall is also presented in this thesis.The paper proposed the feasible precautionary measure according to the possible risk analysis of diaphragm wall. Firstly the guide wall should be built on the original state soil in case of the concrete in diaphragm wall exceeding the structure sideline during construction, increasing workload of concrete clearance and affecting on construction schedule and quality seriously. Secondly, much attention should be paid on the trench verticality directly affecting on the subsequent excavation and water precaution. The trench verticality mainly depends on the trenching machine operator's management of trench quality and the pitch metering device in trenching machine. Besides, guide hole can also be adopted to control the trench quality. Finally, high quality of bottom-clearing replacement should be ensured lest too thick sediment makes coarse gravel in the bottom and grout in the top affecting the seepage precaution of diaphragm wall.After the retaining treatment of the pit in this project using diaphragm wall, during excavation less deformation and seepage of pit and affection the buildings nearby the site on occur compared with the structure using retaining pile. Besides, there is little affection on environment around due to little noise in construction.Integrity of diaphragm wall concrete is confirmed through the inspection of concrete defect and its position with ultrasound wave undamaged inspection technique. The construction quality of diaphragm wall with technical research scheme erected in this thesis excels traditional method after comparison of two methods. It is found that the impermeability increases with the concrete strength and gradation.