Numerical Assessment of Factors Affecting Waveform Based on Low Strain Testing of Piles
In this paper dynamic testing of piles using the low strain method is performed by means of numerical analyses based on solid finite element model. To this end, velocity-time curves are presented investigating the influence of various parameters such as mesh density, impulse width, receiving point, and soil modulus on the waveform characteristics. Then, find regularity of waveform affected by different parameters to provide reference of the real project detection.
Low strain integrity tests in piles – 1-D and 3-D numerical modeling and comparisons with results obtained in the field
The risks associated with integrity problems in piles led to the inclusion of this matter in international standards. One of the tests available to evaluate piles integrity is known as low strain integrity test. Low costs, simple and fast execution and no waste generation are some of the main advantages of this test. However, between others, soil and reinforcement of the pile may affect the results and cause some difficulty to interpret them. In this paper two numerical models based on Finite Elements Method are presented: 1-D and 3-D. The results obtained in the numerical simulations of the tests are compared with those obtained in the field with focus in two main aspects: the signals attenuation effects and the reflections in the transition between the reinforced part of the pile and the part in simple concrete.
DYNAMIC RESPONSE OF FOOTINGS TO VERTICAL LOADING
A method is developed for analysis of the vertical mode of vibration of a rigid circular footing resting on the surface of an elastic half-space. This solution includes all ranges of frequencies for steady state vibration and it is shown how the transient response caused by a pulse-type loading can be calculated from the steady state solution by a simple Fourier technique. From this development, it is shown that the elastic half-space model behaves similarly to a simply damped oscillator and a simplified analog of the mass-spring-dashpot type is proposed for practical calculations. The theoretical results are supported by comparisons with both steady state and impact test results reported in the literature.