Experimental investigation of tunnel squeezing problem in soft ground

Ground squeezing resulting in large plastic zone and large convergence is one of the most challenging problems in tunneling. The squeezing problem in tunnels is often associated with high overburden, low compressive strength of geomaterial, tunnel excavation sequence, competency ratio, tangential strains or the mineralogy of the rock or soil. One or more factor(s) have been used in the literature to define problem of squeezing. Various empirical, semi-empirical and analytical correlations have been developed over the years, but many correlations are problem specific and contradicts with each other. In this work, an experiment will be designed that will study the squeezing problem in tunnel under soft ground conditions. The experimental will be performed on a cubical specimen of a soft rock/soil/synthetic material with a size of 30x30x30 cm³. The specimen will be subjected to compressive poly-axial stress state in all three directions, i.e. σ1>σ2>σ3. A small model earth pressure balance (EPB) tunnel boring machine (TBM) will be designed that can simulate excavation similar to real on site tunneling. Monitoring will be done using acoustic emission (AE), borehole extensometer, strain gages and accelerometers will be installed in TBM and on the cubical specimen. The critical conclusions and correlation developed from the experimental results will contribute significantly and will be give better insight into the problem of tunnel squeezing.

• Record URL:
  https://zenodo.org/communities/utc-uti/

Language

• English

Project

• Status: Completed
• Funding: $330000
• Contract Numbers:

  69A3551747118

• Sponsor Organizations:

  University Transportation Center for Underground Transportation Infrastructure

  Colorado School of Mines
  Golden, CO  United States  80401

  Maptek

  Dever, co  United States  80401

  Colorado School of Mines

  1500 Illinois St
  Golden, CO  United States  80401

  Office of the Assistant Secretary for Research and Technology

  University Transportation Centers Program
  Department of Transportation
  Washington, DC  United States  20590
• Managing Organizations:

  Colorado School of Mines

  1500 Illinois St
  Golden, CO  United States  80401
• Performing Organizations:

  Colorado School of Mines

  1500 Illinois St
  Golden, CO  United States  80401
• Principal Investigators:

  Gutierrez , Marte

  Hedayat, Ahmadreza

• Start Date: 20170801
• Expected Completion Date: 20191231
• Actual Completion Date: 0
• USDOT Program: University Transportation Centers

Subject/Index Terms

• TRT Terms: Accelerometers; Acoustic emission; Compressive strength; Excavation and tunneling; Extensometers; Simulation; Soft soils; Strain gages; Tunnels
• Subject Areas: Bridges and other structures; Geotechnology; Highways;

Filing Info

• Accession Number: 01660189
• Record Type: Research project
• Source Agency: University Transportation Center for Underground Transportation Infrastructure
• Contract Numbers: 69A3551747118
• Files: UTC, RIP
• Created Date: Feb 16 2018 7:26PM