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

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The project strengthened an operational quay serving the Sakata Kyodo Thermal Power Station ahead of increased design water depth at Sakata Port. Because the ground included reclaimed soil, sand and gravel, and locally cohesive soils, the design adopted V-JET large-diameter jet grouting and the MF150 multi-fan method.<br /><br />V-JET V-3A formed columns with a 5.0 m effective diameter, while MF150 created fan-shaped columns by controlling rod rotation. Mixing tests established a grout dosage of 780 kg/m³ to achieve the target unconfined compressive strength of 3 MPa. Field tests and construction checks assessed strength, shear-wave velocity, and column geometry. Average strength results met the target, and measured shear-wave velocities met or exceeded 600 m/s. Column dimensions and continuity were checked using cutting-sound monitoring, core sampling, and trial sonic prospecting; the methods gave consistent confirmation that the required geometry was achieved.<br /><br />Construction controls addressed risks to the quay and nearby coal-handling equipment. MF150 columns were aligned parallel to the quay’s steel pipe sheet piles, reducing the duration and energy of jet pressure acting on them and helping limit displacement. Near the coal-lifting facility’s pile tips, partial semicircular treatment was used to reduce temporary weakening of the supporting ground while maintaining structural capacity. An automatic total station continuously monitored quay displacement during construction.<br /><br />The case demonstrates how combining large-diameter and multi-fan jet grouting, with tailored treatment geometry and monitoring, can reinforce an in-service quay while managing construction effects on adjacent structures.

Keywords

quay strengthening

jet grouting

V-JET

MF150

Sakata Port

thermal power station

reclaimed soil

unconfined compressive strength

construction monitoring

multi-fan method