Study On Propagation Characteristics And Test Method Of Share Wave In Cylindrical Compaction Specimen

Shear wave velocity which can reflect the dynamic characteristics of soil well is an important indicator in describing soil engineering properties. It is widely used in practical projects. So far, there are two main methods for measuring share wave velocity, which are in-situ test method and indoor test method. The actual shear wave velocity of soil could be gained with the former method. However, high testing expense, multifarious operations and the applicability of test result is narrow are the defects of this method. With the latter way, test process will be easier, different measure conditions could be taken into consideration, and parametric approach could be applied in study. While, this test method is always influenced by transducer, size of specimen, test position and couplant, which cause difficulties in getting precise share wave velocity of soil, and impede the application of this method. On account of this, based on the project of National Natural Science Foundation of China(NSFC)—The research of diagnosis technology in view of dam hidden trouble based on the three-dimensional wave to electric field coupling by the holographic imaging, inventive patent—a way to measure shear wave velocity of compaction specimen indoors, and elastic wave propagation theory, study on propagation characteristics and test method of share wave in cylindrical compaction specimen is proposed in this thesis. The main study contents are as follows:Firstly, on the basis of elastic wave propagation theory, three-dimensional cylindrical compaction specimen finite model is built. According to which, share wave propagation rules under the condition of different loading frequency, different load size and different model size are analyzed, respectively.Secondly, based on finite element analysis results, the influences of loading frequency, load size and model size on share wave propagation are studied. The results shows that, share wave velocity and attenuation of wave energy are increased with the growth of loading frequency, but in general, the impact of loading frequency on share wave velocity is mall, load size has little influence on share wave velocity, besides, the diameter of model has a significant influence on share wave velocity, when the diameter is over 0.2m, even make the model much bigger share wave velocity will be changed little, when the diameter is less than 0.2m, even reduce the size a little share wave velocity will has a great change, moreover, with the change of diameter, the share wave velocity varies linearly.Thirdly, with the way of testing share wave velocity suggested by the patent, share wave velocity of compaction specimens with different dry density are measured, the relationship between shear wave velocity and dry density is obtained. P-wave velocity of these specimens is measured with ultrasonic detection method, and the relationship between p-wave velocity and dry density is gained. The elastic parameters of soil are calculated based on the obtained share wave velocity and p-wave velocity,Fourthly, analyzing the results achieved by numerical analysis and measurement, the way to measure shear wave velocity is modified.