The Application Of Transient Wave Test Technique In Estimating The Bearing Capacity Of Pile

Transient wave test technique is a new kind of geophysics exploration method for shallow layer. Using the dispersion characteristics of Rayleigh wave and relativity between wave velocity and physical mechanical character of site soil it can resolve many engineering geological problem. In this paper, the Spectral Analysis of Surface Wave (SASW) method is viewed, schematic of experimental arrangement, various test setups and corresponding data reduction procedures are discussed. This technique can be used for monitoring the various foundation treatment methods such as dynamic consolidation, vacuum preloading, and vibro replacement stone column and grout injection. Test and results show that using this technique and comparing the velocity before and after consolidating can estimate the horizontal and vertical effect of consolidation macroscopically. Many methods for check the bearing capacity of single pile is used at present but they all have some deficiency. In this paper, an indirect method, using transient Rayleigh wave technique, is raised. On the basis of summarizing and analyzing the model of standard penetration test blow and shear velocity and the method of using the standard penetration test blow for estimating the bearing capacity of pile, the model of shear velocity and lateral friction of pile and the model of shear velocity and tip resistance of pile is founded through standard penetration test blow. Because of regional specialty and complicated classification of soil, three kinds of various regional models are founded. Using the transient Rayleigh wave method can measure the shear velocity of site soil and estimate the bearing capacity of pile. Comparing with the result of static load test, the regulative coefficient is received. The program written through Matlab software has two sections: one is using the existent model for estimating; the other is forecasting the model and using this model for estimating. The program has various models for choosing according to various regions. Results of the engineering case show that this method is quite accurate and very efficient. It provides a new method for estimating the bearing capacity of pile. Comparing with the static load test and high strain dynamic test, this method is cheaper and nondestructive. It can check all the piles of site and make up the deficiency of other methods.