A Novel Sensor for Undrained Shear Strength Measurement in Very Soft to Soft Marine Sediments Based on Optical...

Area of Science:

• Geotechnical Engineering
• Marine Geology
• Sensor Technology

Background:

• Conventional fill materials for land reclamation are scarce.
• Dredged marine deposits offer a sustainable alternative but require strength assessment.
• Understanding soil strength is crucial for sedimentation and consolidation during reclamation.

Purpose of the Study:

• To develop and validate a novel sensor for measuring undrained shear strength in marine soils.
• To assess the sensor's performance in soft marine sediments.

Main Methods:

• A simple sensor utilizing optical frequency domain reflectometry (OFDR) technology was designed.
• The sensor comprises an optical fiber and polyoxymethylene coins.
• Calibration was performed on remolded marine deposits; validation occurred in physical model tests.

Main Results:

• The OFDR-based sensor demonstrated high resolution, distributed sensing, and electromagnetic immunity.
• Accurate undrained shear strength profiles were obtained for very soft to soft marine sediments.
• Sensor performance was validated in physical models of marine deposits treated with horizontal drains and vacuum preloading.

Conclusions:

• The novel OFDR sensor is a feasible and accurate tool for measuring undrained shear strength in marine soils.
• This technology supports safe and efficient land reclamation using dredged marine materials.