Time-Saving Tips for Efficient CSL Testing with CHUM

A Technical Analysis

In deep foundation testing, the speed of Crosshole Sonic Logging (CSL) directly impacts construction schedules. Delays during the testing phase hold up subsequent excavation and concrete placement. The Piletest CHUM (Cross-Hole Ultrasonic Monitor) is engineered to optimize data acquisition rates, achieving operational speeds of up to 700 meters of CSL sections per hour and enabling a single operator to log up to 4,500 meters of CSL sections daily.

This efficiency is driven by specific hardware, software, and data processing architectures designed to eliminate manual intervention in the field.

1. Fast Equizition Rate  at 2 m/s

Data corruption from signal noise typically forces operators to pull sensors slowly to ensure clean waveforms. The CHUM utilizes high-output transceivers that deliver an industry-leading Signal-to-Noise Ratio (SNR), enabling the sending and measurement of 40 signal pulses per second. When using the default 5cm spacing, this acquisition speed translates to a pull speed of 2 meters per second through the access tubes, significantly reducing the duration of individual line pulls.

2. Real-Time Automatic Gain Control (AGC)

Variations in concrete density, tube debonding, and shifting tube spacing frequently alter signal attenuation. Rather than requiring the operator to manually pause testing to adjust amplification gains, the CHUM software incorporates Automatic Gain Control (AGC). The system dynamically optimizes signal amplification in real time during the pull, preventing signal clipping or loss without operator input. The operator never has to waste time modifying the system's gain.

3. Streamlined 3-Click Test Wizard

To minimize the time spent on-site configuring software parameters, the user interface relies on a structured Test Wizard. The software guides the operator through a sequential setup process that minimizes menu navigation. A test sequence can be initialized from system startup in exactly three clicks, reducing setup overhead between different shafts.

4. Edge Processing: Automated FAT pick and On-Site Tomography

Post-processing is frequently a bottleneck in CSL testing, but the CHUM shifts heavy computing tasks directly to the field:

• Automated First Arrival Time (FAT): Built-in algorithms automatically pick the first arrival time of the ultrasonic wave for every logged depth measurement, minimizing the need for manual post-test picking. In rate cases, the operator may manually override the automated FAT picking to improve the results.

• Instant 2D Tomography: 

  • The software processes the data stream dynamically, generating a 2D Tomography defect map in real time. Allowing immediate verification of shaft integrity before the equipment is packed up.

2D Pile Tomography

Instant pile slice2

• Instant pile slice - The CHUM software allows you to scroll through the pile and, at every depth, see a "heatmap" of the pile's (concrete) density.

  
  

5. PC-Based Architecture via USB

Instead of relying on proprietary, low-spec embedded processors that slow down under dense data loads, the CHUM hardware acts as a data acquisition interface that connects directly to a standard Windows laptop or tablet via USB. By leveraging the superior RAM and CPU processing power of modern consumer PCs, the software renders complex waterfall diagrams, charting, and multi-tube configurations instantaneously.

6. Real-Time 2-Dimensional Severity Measurement

The transition from raw data to a deliverable engineering flaw severity analysis is automated within the system software. The software automatically compiles:

• Traditional 1D plots and waterfall diagrams

• Relative Energy (RE) graphs

• FAT graph

Based on the RE and FAT, and using the DFI recommendation whitepaper, it generates a red, yellow, green severity graph that helps to locate the areas with flaws quickly.

DFI Severity Criteria Graph

CHUM CSL test output, combines Waterfall + FAT + RE + Severity graph

Based on the above criteria graph,

established by the IDF committee, CHUM presents a severity graph on a waterfall diagram (refer to the arrow on the right waterfall diagram output of the CHUM). The severity criteria set 3 levels: Class A (Green) - Acceptable

Class B (Yellow) - Conditionally Acceptable

Class C (Red) - Highly Abnormal

Performance Summary

Parameter	Operational Capacity	Impact on Workflow
Sensor Pull Speed	2.0 m/s	Reduces time per tube pair
Hourly Throughput	~700 meters	Minimizes total on-site footprint
Software Initialization	3-Click Wizard	Eliminates prolonged calibration delays
Data Processing	Real-time FAT & 2D Tomography	Eliminates mandatory office post-processing
Flaw Saverity Graph	Real-time flaw severity analysis	Immediate visibility of areas with a flaw or potential defect
Output Format	Native MS Word (.docx)	Instant report generation at the job site