Abstract:

The high accuracy small strain triaxial apparatus (hereinafter inferred to as the new triaxial apparatus) developed and assembled by Shanghai Jiao Tong University adopts a built-in pressure chamber by integrating the stress and strain loading function automatically controlled by the program and the linear variable differential transformer (LVDT) function of measuring small strain. In this paper, the new triaxial apparatus is further expanded. Now it has the function of measuring K₀ coefficient of undisturbed soil sample and performing stress path loading along any direction of q-p (q is the deviatoric stress and p is the average principal stress) stress space. First, the development history of the new triaxial apparatus is briefly introduced and the control program algorithm of K₀ coefficient measurement and stress path test for the two new functions are described in detail. Then, the K₀ coefficient measurement and stress path test for deep soft clay in Shanghai are conducted, and the results are analyzed to verify the reliability of the new functions. The experience of the new triaxial apparatus can provide reference for the development of geotechnical instruments.

Key words: triaxial apparatus, coefficient of earth pressure at rest (K₀), stress path test, Shanghai deep clay