Study On Stability Of Diaphragm Wall Construction In Water-rich Sandy Pebble Strata

Abstract:With the rapid development of the Ultra-High-rise building and the metro, nowadays, diaphragm wall has been used widely in the nationwide foundation engineering and the deep foundation pit supporting of subway station. Under the complex geologic environment, the safety of diaphragm wall construction has been increasingly emphasized. Base on research subject of "The Open Innovation Platform Fund Program of The University of Hunan Province"of the China Railway12th bureau group and on the engineering background of "Huangxing Plaza Station of Changsha Subway Line One", the paper research the construction techniques of the diaphragm wall in water-rich sandy pebble strata of densely build areas in detail with the method of theoretical analysis, Digital Computation,and spot test. The main contents and conclusion include:(1) according to the theory of trench stability,we set up the holistic and local slide mass model in water-rich sandy pebble strata, which has been compared with under the geology of Huangxing Plaza Station.(2) Using numerical calculation method to evaluate that different factors affect the trench stability,such as the heigh of pit level, groundwater level, the load around diaphragm wall,the length of grooves and the covering depth of sand.(3) Facing space limitations of the construction of diaphragm wall, we analyze the theory basis of the segments of Reinforcing cage, proposing the new technology of straight threaded coupling and a method of space localization to finish the connection of reinforcing cage(4) systemizing the consequence of ultrasonic testing, and comparing the test data with the theoretical result of the mud.