Improved TDR Method for Quality Control of Soil-Nailing Works

Chih Chung Chung, Chih Ping Lin, Kai Wang, Chih Sheng Lin, Yin Jeh Ngui

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Time domain reflectometry (TDR) has become an effective nondestructive testing method for soil-nailing inspection. Previous studies utilized a preinstalled, single-core, electric wire alongside the rebar within the soil nail. Measurements may be affected by possible grout defects and excessively overestimate the rebar length if the wire is coiled around the rebar. An improved TDR waveguide and a corresponding decoupled data reduction method (for both soil-nail length determination and grout condition inspection) are proposed herein. The feasibility and advantages of the new approach were experimentally verified with two types of TDR device. The proposed methodology makes it possible to use a portable, low-cost, and low-speed TDR device as a quick and economical tool for quality control of soil nailing.

Original languageEnglish
Article number06015011
JournalJournal of Geotechnical and Geoenvironmental Engineering
Issue number1
StatePublished - 1 Jan 2016


  • Integrity
  • Nondestructive testing (NDT)
  • Quality control
  • Soil nail
  • Time domain reflectometry (TDR).


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