Pile Capacity Checking Tool based on Distributed Fibre Optic Sensing for Instrumented Pile Load Test

Abstract

Pile load test instrumented using Distributed Optical Fibre Sensing (DOFS) offers a superior ability to assess pile capacity through continuous strain profiles as opposed to the discrete measurement method such as Vibrating Wire Strain gauges. Due to the vast amount of spatial data generated by the sensor, processing the raw data from DOFS is not always straightforward, often done manually with careful interpretation of various factors affecting the measurements. Experts are reconciling with different data processing algorithms to assess pile capacity (t-z curve) from the DOFS data and verify it, leading to a demand for standard practice. Currently, the verification is done by comparing the pile capacity assessed from DOFS data to the analysis from the commercially available numerical software. The software typically requires input parameters such as extensive soil data, structure geometry, and loading intensity. Some of these parameters are limited (due to bureaucracy or trade secrecy) for the pile load test contractor to verify the pile capacity computation. This paper presents a checking tool that has been developed to automate the processes including raw file parsing, initial processes (trimming, positioning, and averaging), and post processes (pile capacity computation and checking). The post processes utilised the simplified Finite Element Method (FEM) to perform the checking which only utilised the DOFS data. In this paper, an application of the developed tool to a DOFS instrumented pile load test in Kuala Lumpur is reported. This exercise provides the information that the tool can be helpful to verify the pile capacity computation from DOFS data with promising performance reliability at 95%.