Abstract: Strength of undisturbed soil has gained significant interest among researchers in the field of geotechnical engineering. However, there are difficulties for us to obtain the strength of undisturbed soil due to soil disturbance.Based on the physical concept of interpolation function on disturbance, we propose a new method to predict the strength of undisturbed soil according to the strength of disturbed soil. According to the definition of soil disturbance degree(D_d) by Z.Hong and K.Onitsuka, in association with elastoplastic damage mechanics model of clay, we assume that the relationship between disturbance function and D_d shows tendency of exponential function. Furthermore, we deduce the strength of undisturbed soil by using interpolation function and the results of compression test and strength of disturbed soil. Typical undisturbed soft clay in Lianyungang district of Jiangsu province is taken as an example. We carry out vibration test of the clay to verify the model, and the test results show that the prediction method in this paper could well reflect the undisturbed soil strength of typical soft clay in Lianyungang.

Key words: undisturbed soil, soil disturbance, interpolation function, soil disturbance degree(D_d), disturbance factor, soil strength