Abstract: The horizontal consolidation coefficient of the soft soil is an important parameter for both the foundation settlement analysis and the numerical simulations. The consolidation value obtained from the laboratory test is often inconsistent with the field performance. The flat dilatometer test has obvious advantages in the accurate determination of horizontal consolidation coefficient of soft soil. This paper introduces the spatial and temporal distribution of pore water pressure of soft soil during the penetration process of flat dilatometer test and obtains the calculation formula of horizontal consolidation coefficient. Combined with the engineering practice, the analytical results are compared with the laboratory test values. The research results show that the horizontal consolidation coefficient measured by the laboratory test and the calculated value of flat dilatometer test for both peaty silty clay and silt can be obtained. The former is 11.0 times of the latter, and the latter has a larger discrete type.

Key words: flat dilatometer, in situ tests, soft soil, consolidation coefficients, dissipation tests