Numerical Modeling Of Wave-Propagation In Elastic-Half-Space With Imperfections

Soil deforms under impact. If the strains are small enough (5×10-4 or less), the material approximates elastic behavior. In geotechnical engineering analysis, soil properties are assumed to be<br>isotropic and the state of stress is often modeled as an equivalent isotropic state. Thus, the compression wave velocity and the shear wave velocity can be used to characterize the material in the stress-strain range of mechanical waves. Shear modulus and Poisson's ratio are then estimated from these wave velocities. Elastic properties of soils are important in determining the small-strain response of soils under dynamic and static loading and are of major concern in site assessment. In the field seismic crosshole and seismic down-hole tests are performed to evaluate small-strain, elastic properties of soils. Ultrasonic testing has been used to determine small-strain, isotropic, elastic properties of soils in the laboratory. Seismic testing methods have the advantage of providing fast and reliable results. In this paper wave propagation in isotropic elastic half space is simulated with Finite Element and Finite Difference numerical models. P-wave and S-wave arrival times are compared to the theoretical arrival times and elastic properties are back-calculated. Imperfections on the surface are detected in terms of change in the wave arrival time. Errors for input versus back calculated values are provided. Finite element and finite difference methods can be used to simulate complex problems. Numerical tools can assist in the interpretation of field and laboratory test results.