In order to determine the thickness of flat frozen soil wall with evident rheological properties

the triaxial creep properties of frozen soil are analyzed. Through theoretical analysis of rheological properties of frozen soil

the logarithmic creep equation of frozen clay is established under complex stress state. The triaxial creep tests for manual prepared frozen clay specimens are carried out by “cold box-triaxial pressure chamber” light test equipment system; so that the creep curves of frozen clay under complex stress state are obtained. According to the test results

the logarithmic creep equation parameters of frozen clay are obtained through regression analysis of logarithmical nonlinear creep equation. According to the rheological theory of frozen soil and the established creep equation

as well as the thickness formula of flat frozen soil wall

through adopting Visualc++ 6.0 and Matlab 6.0

the computer application software is exploited which can calculate thickness of frozen clay wall. With the software

the relationships between the thickness and the span

the pit exposure time

and the pit excavation depth are analyzed. The thickness of flat frozen soil wall possesses rapid growth trend with time extension in the short term and then gradually becomes stable. The thickness of flat frozen soil wall is affected lightly by the span; but it possesses gradual upward trend with the increasing of excavation depth of pit. The temperature affects the thickness of flat frozen soil wall significantly; the higher the temperature is

the larger the thickness is. Consequently

controlling the temperature is the key to the design of flat frozen soil wall. Thus

the results provide a basis for thickness determination of flat frozen soil wall with a large creep deformation.