The Application of Compaction and Jet Grouting for Sinkhole Remediation-PPT Presentation

PPT Presentation

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A deep-seated sinkhole, approximately 28 m by 40 m and 30 m deep, developed beneath Rideau Street along a proposed tunnel alignment. It engulfed three traffic lanes, a parked van and a light standard, while soil and groundwater entered the partially built tunnel. The collapse also damaged shoring, grout pipes and buried utilities. After the surface depression was backfilled with low-strength concrete, ground improvement was needed to prevent further ground loss and create a stable block for tunneling.<br /><br />Subsurface conditions were highly variable, including granular backfill, a concrete plug of uneven thickness, and 7–8.7 m of fill and disturbed soil containing possible voids and concrete debris. Probe holes were advanced to investigate soil conditions, obstructions and rock levels. Jet-grouting test columns were assessed with an Acoustic Column Inspector, which verified a minimum diameter of 1.8 m.<br /><br />Stabilization combined compaction grouting and jet grouting. Compaction grout was injected in stages through drill casing, with pressure, volume and ground movement monitored. Jet-grout columns were constructed using a double-fluid system after predrilling. Operations ran continuously, seven days a week, to meet the project schedule.<br /><br />The work faced complex ground conditions, including collapsed shoring, steel grout tubes, equipment and dense utility networks. Every hole had to be daylighted to reduce the risk of striking utilities. Limited space on a busy street complicated site setup, and managing jet-grouting spoil required an on-site treatment plant that separated water from solids for reuse or disposal. Extensive coordination across day and night shifts was essential to maintain safety and meet the accelerated schedule.

Keywords

sinkhole

rideau street

tunnel alignment

ground stabilization

compaction grouting

jet grouting

subsurface investigation

utility damage

soil voids

acoustic column inspector