Study on the Nonlinear Dynamic Characteristic of Cone Penetrate Test Curve

Soil on the surface of the earth is the remnants of weathered rock and strata with layer structure appear a time series feature. Static cone penetrate test (CPT) is an exploration technology which can obtain the physical indices of strata accurately. Study shows that specific penetration resistances (Ps values) of soil vary with the buried depth of strata and the curves of Ps values have fractal characteristics. In this paper, we adopted nonlinear dynamic theory to analyze the chaos and multi-fractal properties of these curves. At the same time, we also discussed the Hurst exponents of CPT data sets. The results suggest that chaos characteristics of the test data are not clear, however the multi-fractal spectrum of each CPT curve can identify nonhomogeneity degree of soil, also it can distinguish the difference of sedimentary environments. Furthermore, rescaled range analysis indicates that the soil layers deposited later had long range dependence on those deposited early.