Study on the Quality of Multifan Shaped Jet Grouting-Paper

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The study evaluates the MultiFan jet grouting method, developed to reduce unnecessary soil improvement, cement use, construction costs, and industrial waste in wall-shaped ground improvements. Conventional round columns create excess treated soil, while oval columns reduce excess but require closer spacing and more columns.<br /><br />The MultiFan method creates partially formed fan-shaped columns by intermittently changing the jet monitor’s rotation speed. Geometric comparisons showed that MultiFan columns require the same column spacing and number of columns as round columns, while producing less redundant improved soil. They also reduce excess soil more effectively than oval columns, making them a more efficient option for wall construction.<br /><br />Researchers developed control equipment to regulate the fan radius and central angle, then tested it in soft cohesive silt with sand. Excavation confirmed that the equipment could construct the intended MultiFan shapes. Core samples were tested for unconfined compressive strength. Strengths were generally between 1.0 and 3.0 MN/m², with no significant difference between the large- and small-diameter fan sections. Strength variability was also similar across the column and comparable to conventional jet grouting.<br /><br />The results indicate that MultiFan jet grouting can produce consistently improved soil while reducing unnecessary treatment. The method is suitable for applications including wall-form ground improvements, cutoff walls, and diaphragm-wall guide walls.

Keywords

MultiFan jet grouting

ground improvement

soil stabilization

wall-shaped columns

jet grouting method

cement reduction

construction cost efficiency

soft cohesive silt

unconfined compressive strength

cutoff walls