Experimental research and computer simulation on the dynamics characteristics of soils subjected to the impact load

ABSTRACT In this paper, site tests of dynamic compaction and the corresponding computer simulations were carried out to explore the dynamics character of the soils (II-class self-weight collapse loess). The researches give the spatial and temporal distribution of the dynamic stress and their development with time increase. Results show that the impact between Drop hammer and the soil produce the pulse stress in the soil near th e contact zone firstly and then the stress will transmit into other part of the soils. The distribution of dynamic stress at some time is that it is greater in the superficial part of groun d and decreases gradually with depth increase during the process of impact. With the propagation of the dynamic stress a compacted soils region with the shape of ellipse are formed. The scope of the reinforced area of DCM (dynamic consolidation method) is given. Keywords: Dynamics character, Soils; Im pact load, dynamic compaction 1 INTRODUCTION The dynamics characteristics of soils subjected to the impact loading have not been understood clearly. There is no precise or appropriated theory to describe the complicated behavior of the soils in dynamic consolidation and the reinforcement mechanism. In this paper, site tests of dynamic compaction were carried out to explore the dynamics character of the soils (II-class self-weight collapse loess). In the tests, explore well, dynamic penetration, standard penetration, static cone penetration, pressure test were carri ed out. During the tests the gr ound surface displacement, ash mark side displacement, pore water pressure, dynamic stress beneath hammer and in deep soils, and the density change of ground were recorded. We also monito r the vibration of surface of ground and the consolidation time after impact. Secondly, numerical simulations of these impact scenarios, identical to the experiments were performed using the commercial finite element code LS-DYNA. The simulation resu lts were compared with the experimental data and good agreements were acquired. This process tested the validity of numerical model. Finally, the numerical model was explored for more exhaustive analysis about the dynamics behaviors of soils.