Study On Quantitative Analysis Of Defects And Application Of Wavelet Transform Theory In Exploration Of Geotechnical Concealed Structures

In the pile integrity detection, quantitative analysis of defects is a problem unsolved so far. As a hidden structure, it is important and difficult how to control construction quality of soil-cement seepage prevention wall. To solve the two problems, following researches have been done. Instantaneous response analytic solutions of the integrated pile in homogenous soil and the defective pile in layered soils are obtained along the pile by solving the mathematic problem. The degradation of stress wave along piles is analyzed on the solution, which supplys to the theory basis for the following laboratory experiments. The quantitative analysis method of defects is developed on reflecting wave theory and the degradation relation of stress wave, in which a ratio of the reflecting and incident wave amplitude is used to evaluate the degree of a defect. Laboratory and in-situ tests of pile-soil interaction at low-strain have been conducted in the sand, the silt and the silty clay of two different water contents to determine the damping coefficient. The correlation between the damping coefficient and effcitve overburden press of strata around pile is established. The correlation is combined with above analysis method to establish the model quantitatively analyzing the defects of piles. Because the traditional Fourier processing method can't detect the locations of the fracture, the break and shallow defects in pile, the multi-resolution analysis of wavelet transform is introduced to detect them. Here, the Db5 wavelet is used to analyzing signals of these defective piles. The results show that the method can identify those defects clearly. Finally, the quantitative synthetical evaluation standard is established by in-situ and laboratory tests on soil-cement seepage prevention wall to evaluate construction quality of walls. Then, the nondestructive technique detecting construction quality of the soil-cement seepage prevention wall is further studied on the instantaneous surface-wave principle by in-situ test. Key detection parameters are suggested for nondestructive detection of the wall.