Construction Example Using V-Jet Method and Multi-Fan Method for Aseismic Reinforcement of Coal Quay in Service-PPT Presentation

PPT Presentation

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The presentation describes seismic ground improvement at an operating coal quay in Sakata Port, undertaken in connection with an increase in the port’s design water depth. The project used two jet-grouting techniques: the V-JET method, producing columns with an effective diameter of 5.0 m, and the multi-fan method, forming walls with an effective thickness of 1.5 m.<br /><br />Mixing tests were carried out on samples from three work areas. Because initial results did not meet the target unconfined compressive strength of 3.0 MPa, the required solidifier dosage was established by extrapolating the test results. Field tests then confirmed that both methods met the specified strength and elastic-wave velocity criteria: at least 3.0 MPa and 0.6 km/s, respectively. Column dimensions were checked using cutting-sound monitoring and sonic prospecting.<br /><br />Key construction challenges involved protecting the quay and existing equipment foundations. Near the steel-pipe-sheet-pile quay wall, the multi-fan method was selected to reduce the effects of injection pressure and limit wall deformation. Around the foundations of existing coal-handling equipment, swing-type improvement was used to avoid the foundation piles’ supporting ground and help maintain bearing capacity during construction. Quay deformation was also monitored.<br /><br />The project demonstrates how large-scale jet grouting can be adapted to improve seismic performance while managing quality, column geometry, and risks to structures that remain in service.

Keywords

seismic ground improvement

jet grouting

Sakata Port

coal quay

V-JET method

multi-fan method

unconfined compressive strength

elastic-wave velocity

quay deformation monitoring

swing-type improvement