Abstract: There are many geotechnical physical and mechanical parameters involved in the design and construction of a subway deep excavation support structures. These parameters include shear strength, lateral earth pressure coefficient and horizontal coefficient of subgrade reaction modulus, etc. Many methods insitu and laboratory testing methods available estimate these parameters in geotechnical engineering practice. Due its simplicity and matured in principles as well as easily operated, the flat dilatometer has its own advantages in the geotechnical investigations for the metro deep excavation supporting design. By comparing the parameters obtained by the flat dilatation test with the experimental data of a large number of projects in Wuhan, the studies show that the two series of parameters are in good agreement with each other.

Key words: dilatometers, geotechnical investigation, design of subway deep excavations, shear strength, static earth pressure coefficient