Cross-hole Sonic Logging Research Articles

The Detection and Analysis of Reservoir Dam Crack Depth and Grouting Quality Analysis

Ultrasonic method is a considerably mature method to test the defects of concrete. As for a certain dam deep crack with merely one test surface, the operations can be done such as drilling holes on both crack sides, filling clean water as coupling agent and finally the crack depth is tested with cross-hole sonic logging, subsequently, the data processing and depth judgment with the test principle of the said method. The result manifests that before grouting treatment, the measured dam crack depth is 1.2~9.0m, and the tested point wave shape has not been obviously abnormal and the criterions of wave amplitude and wave speed against the intact local concrete remain no greater differences and the cracks grout in the tested zone are generally solid after the grouting.

Implementation of self-consolidating concrete in caisson construction for the Stalnaker Run Bridge

To utilize cast-in-place self-consolidating concrete (SCC) for caissons on a rural bridge replacement, specifications were first written as guidelines. A mix design was developed and tested in a reusable trial caisson that would simulate field casting conditions. A fresh sampling technique was devised to investigate the distribution of SCC within the trial caisson. Petrographic analysis of hardened samples was done to quantify the amounts of aggregates present at twenty different locations within the trial caisson. The SCC mix design was then successfully used to cast caissons of one of the two bridge abutments, with no major defects detected by cross-hole sonic logging (CSL). Hardened property tests revealed SCC compressive strengths and modulus of elasticity values that were similar to a traditional caisson concrete used on the project, while the total measured shrinkage and the splitting tensile strengths of the field SCC were seen to be lower than those of the traditional caisson concrete.

Application of Crosshole Sonic Logging in Foundation Pile Integrity Detection

This article introduces the application of crosshole sonic logging in foundation pile integrity detection and the basic theory and application of crosshole sonic logging, and narrates the detection technology and way to judge detection results by engineering projects.

Hollow Threaded Rebar for Cross Hole Sonic Logging Access Tubes Combined with Longitudinal Concrete Reinforcing in Drilled Shafts

AbstractCrosshole Sonic Logging (CSL) of drilled shafts requires 1.5-in (38-mm) or 2-in (51-mm) I.D. sonic access tubes to be installed inside the steel reinforcement cage. The sonic access tubes do not contribute to the structural capacity of the drilled shaft. The proposed use of Ischebeck TITAN T73/56 CSL/Hollow Threaded Rebar for Cross Hole Sonic Logging Access Tubes Combined with Longitudinal Concrete Reinforcing in Drilled Shafts (patent pending) is discussed as an alternative method of construction and CSL probe access. The T73/56 hollow threaded rebar/sonic access tube performs as a high strength rebar while at the same time creating a 2.2-in (56-mm) I.D. sonic access tube. The deformed high strength hollow bar provides better adhesion to concrete thus reducing the problem of debonding associated with smooth PVC and steel pipe. A cost comparison using conventional rebar with added sonic access tubes is discussed. The use of T73/56 CSL/Hollow Threaded Rebar as a value engineering alternative can re...

Integrity Problem of Large-Diameter Bored Piles

Bleeding is known to occur in bored piles (drilled pier). The generally accepted view is that bleeding in piles is confined to the upper part of the pile only. Under certain conditions during bleeding, channeling may happen. Practising engineers believed that the associated problems with bleeding and channeling in bored piles can be overcome by overcasting the piles. A case study of extensive integrity tests consisting of cross-hole sonic logging tests and dynamic load tests on bore piles, as well as continuous corings from top to bottom of the piles carried out, revealed that some bored piles have channeling of concrete at various depths. Most of them were larger diameter piles. The finding that bleeding and channeling are not confined to the upper part of the pile is contrary to the generally accepted view. This paper attempts to develop a theory for the bleeding and channeling of concrete to explain the mechanics of the occurrence of channeling in bored piles. The proposed theory is verified by the close correlation of the predictions of the theory with field observations of the case study. Based on the proposed theory, recommendation with regards to the quality of concrete will be made to avoid the occurrence of channeling of concrete in large-diameter bored piles. The implications on the structural performance pertaining to axial capacity, compressibility and durability of bored piles with channels will be investigated.

Closure to “Reliability Evaluation of Cross-Hole Sonic Logging for Bored Pile Integrity” by D. Q. Li, L. M. Zhang, and W. H. Tang

Closure to “Reliability Evaluation of Cross-Hole Sonic Logging for Bored Pile Integrity” by D. Q. Li, L. M. Zhang, and W. H. Tang

Discussion of “Reliability Evaluation of Cross-Hole Sonic Logging for Bored Pile Integrity” by D. Q. Li, L. M. Zhang, W. H. Tang

Discussion of “Reliability Evaluation of Cross-Hole Sonic Logging for Bored Pile Integrity” by D. Q. Li, L. M. Zhang, W. H. Tang

Evaluation of Self-Consolidating Concrete for Drilled Shaft Applications at Lumber River Bridge Project, South Carolina

Case studies have shown that when conventional concrete mixtures are used in congested drilled shafts, lack of adequate workability or flow between reinforcing bars may lead to trapped laitance or segregation between the inside and outside of the reinforcing cage. Due to its flow-ability and resistance to segregation, self-consolidating concrete (SCC) was evaluated as a viable material to overcome this problem. Several 1.8-m (6-ft) diameter drilled shafts were constructed using SCC as part of a field trial during the Lumber River Bridge Project, South Carolina. Identical shafts were constructed with SCC and a high slump gravel-aggregate concrete mixture typically used in coastal South Carolina. Both mixtures were observed to have excellent workability characteristics. Observations of the hardened concrete from exhumed drilled shafts indicate that generally good performance can be achieved in difficult construction conditions (congested cage, tremie placement, and lengthy placement times) if highly workable concrete is used. Some imperfections in the concrete were observed, even under these closely monitored conditions, and some degree of imperfection in this type of construction appears to be practically unavoidable. The imperfections observed in these field trials were detected by crosshole sonic logging, but they do not appear to have significant adverse consequences for foundation performance. On the basis of results of this project, it is concluded that SCC may be feasible for use in congested drilled shaft applications.

Quality assurance of concrete foundation elements using an ultrasonic evaluation technique

�This paper presents the approach and results adopted in a proactive quality assurance testing technique which was used to inspect, in a non-destructive manner, the integrity and homogeneity of over 200 different in-situ cast concrete foundation elements (ie bored piles, concrete barrette piles and diaphragm wall panels) in various Hong Kong construction sites. The test results were obtained from both public and private buildings and civil engineering projects in Hong Kong. These results show the effectiveness of the use of the Cross-hole Sonic Logging (CSL) method in revealing the different kinds of defects (such as honeycombing, voids, soil inclusions etc.) found during the construction process which under other forms of testing would otherwise remain undiscovered.

Reliability Evaluation of Cross-Hole Sonic Logging for Bored Pile Integrity

Defects present in a pile may not be encountered during a cross-hole sonic logging (CSL) test. Even when defects are indeed encountered, they may not always be detected. This paper proposes a probabilistic analysis procedure for evaluating the reliability of CSL, thereby providing a theoretical supplement to existing experimental evaluations of CSL. The reliability of this integrity testing method is represented by the inspection probability, which is expressed as the product of the encountered probability and the detection probability. Mathematical models to calculate the encountered probability are formulated and a detection probability model is suggested based on existing CSL test data. Several examples are presented to illustrate the proposed procedure. The results indicate that there exists a minimum detectable defect size below which the defect cannot be inspected. For a given number of access tubes, the minimum detectable defect size, as a percentage of the pile cross-sectional area, decreases with the pile diameter. The encountered probability can be taken as an index to determine the required number of access tubes. When the target encountered probability is specified as 0.95, three and four access tubes will be sufficient to encounter defects larger than 15 and 5% of the pile cross-sectional area, respectively.

Effects of Different Sonic Access Tube Materials on the Signal Strength of Ultrasonic Waves in the Cross-hole Sonic Logging Technique

The Cross-hole Sonic Logging (CSL) technique is one of the most effective quality assurance methods for testing foundations in terms of assessing the homogeneity and integrity of in-situ concrete foundation elements. This paper aims to study the effects of sonic access tube materials (such as polyvinyl chloride (PVC) and steel) on the signal strength of ultrasonic waves when carrying out a CSL test. This aim was achieved by the use of an in-house developed multi-channel ultrasonic data acquisition prototype, referred to as the ‘Multiple Referencing System’ (MRS). The prototype was developed based on National Instruments (NI) hardware in a LabVIEW (Laboratory Virtual Instrument Engineering Workbench) environment. It was designed for pre-programmed data acquisition, processing and visualising. With the development of the in-house developed prototype MRS, the transmission velocity and signal strength of the acquired waveforms were determined by the use of different sonic access tubes. According to the experi...

Class-A Prediction of Construction Defects in Drilled Shafts

The results of a blind Class-A prediction symposium of construction defects in drilled shafts are presented. Six drilled shafts were constructed at the National Geotechnical Experimentation Site in Amherst, Massachusetts. Several types of defects were integrated into the shafts, including necking, voids, caving, and soft bottoms. Seven organizations participated in a blind defect prediction symposium and used a variety of nondestructive testing techniques, including down-hole techniques, such as cross-hole sonic logging, single-hole sonic logging, and cross-hole tomography, and surface techniques, such as pulse echo and sonic mobility. Most participants found defects that were larger than 10 percent of the cross-sectional area. However, false positives and an inability to locate smaller defects and multiple defects in the same shaft were encountered.

Nondestructive Diagnosis of Drilled Shaft Foundations

Nondestructive methods based on propagation of sonic and ultrasonic waves are being used increasingly in the United States and internationally for forensic investigations of existing structures and for quality assurance of new construction. Of particular interest is the quality assurance of newly constructed drilled shaft foundations. Many state departments of transportation specify nondestructive testing of drilled shaft foundations, particularly for shafts drilled and placed under wet construction conditions. For quality assurance of drilled shaft foundations of bridges, the crosshole sonic logging (CSL) and sonic echo and impulse response (SE/IR) methods routinely are used. In the CSL method, access tubes are installed in the shaft before concrete placement. SE/IR measurements require that the top of the shaft be accessible after concrete placement. Proper test setups, specifications, and case studies are presented to illustrate the advantages and disadvantages of each of these methods. Also presented are recommendations for repair when a defect is identified in a drilled shaft foundation. The CSL method is more effective for locating defects. CSL measurements are effective for determining anomalies and defects between two access tubes. However, an accurate image of the defect cannot be determined from a CSL test alone. The crosshole tomography (CT) method uses multiple CSL logs with varying receiver locations to produce a two-dimensional image of the defect. The CT method is discussed and a dataset obtained from a drilled shaft foundation is presented. CT data collection and analysis require more time than the CSL method, and the CT method is used only for critical drilled shaft foundations.

Nondestructive Evaluation of Concrete Radioactive Waste Tanks

Partially or totally buried concrete hazardous-waste tanks pose a difficult problem when evaluation of their integrity and concrete quality is required. A visual survey is very limited, and destructive sampling is usually not practical because of poor access to the tank walls and the risk of spillage from the tank into the surrounding environment. This paper introduces several nondestructive testing (NDE) techniques to overcome the foregoing difficulties, including ultrasonic pulse velocity, impulse response, parallel seismic, and cross-hole sonic logging. These test methods are described, and their application is illustrated by case records from a tank evaluation program implemented at Los Alamos National Laboratory, New Mexico, to determine the residual life of 14 low-level nuclear waste tanks, most of which have been in service for more than 30 years.