The Application of Compaction and Jet Grouting for Sinkhole Remediation-Paper

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A deep sinkhole measuring approximately 28 by 40 m developed above a proposed tunnel, causing soil and debris to migrate into the tunnel and damaging nearby shoring and buried services. The depression was backfilled with low-strength concrete, but the disturbed ground beneath remained vulnerable to further settlement and ground loss. Stabilization was therefore required to support continued tunneling and protect nearby infrastructure.<br /><br />The remediation combined jet grouting and compaction grouting. Jet grout columns formed a headwall at the western end of the treatment area, while low-mobility compaction grout was injected in stages to densify disturbed soils east of the headwall. Compaction grouting was also used near the existing tunnel to reduce the risk of jet grout backflow entering it. Probe drilling, utility daylighting and pre-production testing helped identify variable ground conditions, obstructions and suitable installation parameters.<br /><br />Quality assurance included stage-by-stage records of grout pressure and volume, monitoring of ground movement, and measurements of grout properties. Shape Accel Array surveys checked column alignment, while data acquisition systems recorded jetting parameters. Testing confirmed a minimum design diameter of 1.8 m for jet grout columns. Additional columns were installed where obstructions or inadequate interlock were identified.<br /><br />Work took place in challenging conditions, including collapsed shoring, steel obstructions, damaged and active utilities, limited space beside a busy road, and an accelerated schedule requiring continuous operations. Despite these constraints, the grouting program was completed successfully, filling voids and stabilizing loose soils. The paper highlights the importance of probing, testing, sequencing, comprehensive quality control and close coordination in complex sinkhole remediation.

Keywords

sinkhole remediation

jet grouting

compaction grouting

ground stabilization

tunnel support

soil settlement

quality assurance

ground loss

utility protection

probe drilling