The Dynamic Characteristics Of Sands Under Anisotropic Consolidation Conditions And Intensity Normalized Characterization

The dynamic characteristics of soil are not only related to the complex stress conditions under dynamic load, but also closely related to the initial stress state. Accordingly, the further study of the static and dynamic characteristics of saturated soil under the complex stress conditions in various initial condition is not only the key subject of soil dynamics and geotechnical earthquake engineering, but also the practical problem that have to solve for marine construction project.In the current study, a series of triaxial tests were conducted to analyze the relationship of stress and strain as well as the regularity of pore pressure under different back pressure and confined pressure. The effects of the back pressure saturation on the test results under several failure valuation standards were also analyzed, so that we can provide robust condition for the complex dynamic stress test. Furthermore, Fujian Standard sand was chosen as the object of study, a series of complex dynamic stress path tests were carried out using cyclic hollow cylinder torsional tests to study the deformation, pore pressure and the dynamic characteristics of saturated sand in different initial consolidation conditions. The essential reasons of the dynamic strength difference under various dynamic stress path were also discussed. The main conclusions can be drawn as follows:First of all, in the consolidated undrained triaxial tests, back pressure had obvious effects on stress-strain relationship and pore water pressure development of sand, thus affecting detemination of strength. While in the consolidated drained test, sand shear strength was slightly influenced by back pressure. In the undrained shear tests, set back pressure as300～500kPa, Use the same back pressure in the same group. Take the maximum effective principle stress ratio (σ1’/σ3’)max as undrained shear strength of sand. Secondly,in the isotropic and anisotropic consolidation complex dynamic stress tests, strain has larger difference with the development of pore pressure, the variation law of residual pore pressure ratio u/umax with residual generalized shear strain γ g have no correlation with dynamic stress path, but the hyperbolic shape becoming more obvious with the increasing of Kc value. Under the isotropic consolidation conditions, the value of dynamic strength of saturated sand relate to dynamic stress path, cyclic triaxial and cyclical torsional were the highest, oblique elliptic took second place and circular dynamic stress path was least. Dynamic strength was positive correlation with Kc under the same dynamic stress path. In cyclic triaxial or cyclical torsional test, dissipated energy was slightly influenced by generalized shear strain ratio. The simplified calculation methods available for analysis accumulation shear dissipated energy of unit volume has no general applicability. There are linear relationship between Loading efficiency and failure vibration frequency. Consolidation ratio influence interceptand the relative density influence slop.