Abstract
Quality of concrete for pile can be checked using Cross-hole Sonic Logging (CSL) Test. A processing method wide-band CSL data is presented herein. First Time Arrival (FTA) is an important consideration. In pile capacity analysis or CSL analysis, it is assumed that pile cross section is uniform with uniform value of elastic modulus of concrete but in real practice both are non-uniform. The procedure identifies the location accuracy and further characterizes the features of the defect. FTA is used to find out the location of the distress in the pile. This method identifies the exact location of any void or defect inside the rebar cage of a drilled shaft. This method provides a significant improvement to current techniques used in quality control during construction of bridges. In this present paper, the analysis has been carried out based on uniform and non-uniform values of pile cross section and E value of concrete. Cross hole sonic and pile load test using O-Cell were carried out on same pile at 7 and 28 days of concreting. Same pipes were used for base grout after cross hole sonic test. These results were used to analyze O-cell test results based on a case study and presented in this paper. The distribution of skin frication and skin friction force has also been presented herein with both uniform and non-uniform cross section and E values of concrete. Based on the field test results and analysis a simplified methodology, has been proposed in this paper, for development of Equivalent Top Down Loading with consideration of elastic shortening of pile and surrounding soil for both cases i.e., uniform and non-uniform E values and pile cross sections.
Highlights
The rivers widen near sea area than that at the origin of the river at hill
1.4 Objectives and approach The purpose of the present study is to present a method developed to detect the exact location of the defects after performing the Cross-hole Sonic Logging (CSL) test at 7 days of concreting to determine E value of concrete and non-uniform cross sections at different depths of drilled shaft
4 Conclusions Cross-hole sonic logging test is conducted to determine quality of concrete for deep pile and identifies the defect location based on ultrasonic pulse velocity
Summary
The rivers widen near sea area than that at the origin of the river at hill. Navigation vehicles use the river and wide spans of bridges are required at these locations. Soils near sea area generally have poor bearing capacity. Several methods of construction exist today for the construction of drilled shafts (Reese and O’Neill 1999). The most widely used method today is the wet method, i.e., shafts are cast under wet conditions using bentonite slurry in order to keep the borehole open vertical during drilling to avoid collapsing of soil and preventing proper casting of the concrete. Several defects in form of necking /bulging may be occurred. These defects occur due to failure of soft vertical strata after excavation of
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