Abstract
This article studies the applicability of the Non-Destructive Techniques (NDT) into semi-rigid structures, particularly in soil-cement columns. A numerical model for the semi-rigid soil-cement column is first created. Different kinds of defects are intentionally allocated in the model, including necking, bulging, and degraded stiffness. The assumption is that by using an excitation as an impact load at the structure head and then letting the structure vibrating freely, studying the wave characteristics inside the structure, i.e., responsive velocity and displacement at various points along the column shaft, the impedance could be determined. If there is any variation in the mechanical impedance Z, which is defined to be the product of mass density, area of the cross-section, and the wave velocity, the defects are confirmed. The shape of the impedance curves with respect to combined defects is analyzed, and spectral response curves are plotted. The process of analysis in the time domain and frequency domain for the soil-cement column is conducted using Fast Fourier Transformation. The theoretical and computed impedance of the structure from the numerical model will be compared with each other, in the shape of the responsive curves, and the distinguished issues; some discussions on the propagation of waves through semi-rigid structures are summarized. There is no distinguishing feature in the characteristics of the impedance of the structure revealed. It comes to the conclusion that the applicability of the vibration test is not clearly recognized. There is quite a difficulty in evaluating the performance of the semi-rigid structures like soil-cement columns by using vibration or impact load test. This outcome suggests that the column is not the same as the pile, and another alternative and/or approach is recommended to apply in quality assurance/control QA/QC for such embedded semi-rigid structures.
Highlights
Soil-Cement Columns has gradually proved to be a satisfactory solution for a deep foundation
Several common questions for this structure are how to assess the quality of the material and what is the most typical factor for evaluating the strength or the rigidity of this semi-rigid structure? This article would study the possibility of applying the techniques which are well-applied to pile into a soilcement column for detecting the defects inside it
The impedance curve is quite different from that of the theoretical one. This implies that the semi-rigid structure like the soilcement column absorbs the vibration caused by the stress wave due to the impact load, no reflection from the bottom of the column found, and no indicator of the defects are detected
Summary
Soil-Cement Columns has gradually proved to be a satisfactory solution for a deep foundation. The soil plays the role of being a material for the purpose of supporting the gravity load from the superstructure The quality of this kind of structure depends on many factors, including the quality of the material ingredients at the site, the technology of mixing, the depth of work ability, soil stratification, and others, etc. Testing the integrity of a soil-cement column is vital. Because it is mixed at the site, the columns may have some defects. This article would study the possibility of applying the techniques which are well-applied to pile into a soilcement column for detecting the defects inside it. There are numerous methods of testing the structures It depends on which kind of damage and the purpose, Cite this article : Duong T H.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
