This is a ground improvement method suitable for liquefaction countermeasures, achieved through extensive infiltration and rapid construction of large-volume soil. The consolidation over 19 years has been demonstrated through large-scale outdoor injection tests!
The "Permanent Grout Injection Method" is one of the chemical injection methods. The purpose of improving this method is for permanent improvement, but in recent years, its application range has also expanded as an injection method for temporary improvement. The injection material used is "Permanent Grout," which has been theoretically and empirically validated for permanence, and the injection form is designed to be permeation injection that does not disturb the sedimentary state (skeletal structure) of the ground, with the principle of uniformly improving the ground. The "Expakka Method" involves attaching bag bodies (geo-bags) at intervals to the injection outer pipe, inflating these bag bodies to anchor them in the ground and form soil packers, which enables permeation injection by injecting from a large space, allowing for rapid improvement over a wide area. The Expakka Method series includes Expakka-N Method, Expakka NEO Method, 3D-EX (Expakka) Method, and Expakka Lotus Route Method. [Demonstration of Long-Term Durability Over 19 Years Through Large-Scale Field Injection Tests] The results of demonstration tests on permeation solidification and aging solidification through large-scale field injection tests combining Permanent Grout (injection material) and injection methods (such as the Expakka Method) have been evaluated, and the method received the 2002 Technical Development Award from the Japanese Geotechnical Society (Yonekura, Shimada).
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basic information
Long-term durability confirmation tests continue even after large-scale field injection tests, and in 2018, the consolidation properties were confirmed 19 years after the tests. Additionally, a follow-up survey was conducted on areas where liquefaction countermeasures were implemented using this injection material before the Great East Japan Earthquake, confirming that there was no damage to the improved ground. 【Construction Procedure and Features】 1) After installing the injection outer pipe, inflate the geo-bag (sack body) to create a columnar permeation source. 2) The geo-pack grout (injection material) filled inside the geo-bag partially permeates, alkalizing the surrounding ground (soil packer). 3) The soil packer prevents leaks along the injection pipe. 4) Injection can be performed at low pressure even with large columnar permeation sources. 【Completion of the Dedicated Injection Test Center】 At the dedicated injection test center, preliminary mixing tests are conducted using soil samples taken from the site, and by adding insights gained from long-term industry-academia collaborative research to the data obtained, we provide a more reliable quality to construction companies, clients, and other related parties.
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Applications/Examples of results
【Special Injection Materials】 The Expakka method uses the following special injection materials: - High-strength permanent grout: Inorganic suspension type "Hybrid Silica Series" / Application: High-strength ground improvement, Gel time: Several seconds to several tens of minutes - Solution-type permanent grout: Inorganic solution type "Permalock Series" / Application: Liquefaction prevention, Gel time: Several seconds to several tens of hours - Silica sol grout: Inorganic solution type "Hard Riser Series" / Application: Water stopping and ground improvement, Gel time: Several seconds to several tens of hours - Special grout: Inorganic suspension type "Geopack Grout" / Application: Geobag filling material, sealing material, Gel time: Several tens of minutes 【Construction Examples】 - Reinforcement and liquefaction countermeasures directly beneath structures - Seismic reinforcement of foundations - Base improvement associated with open-cut construction - Construction of water-stopping walls for tank foundations - Prevention of water extraction and reinforcement of riverbanks - Reinforcement associated with tunnel excavation work - Reinforcement of missing sections of underground diaphragm walls, etc., over 70 cases *For detailed technical materials and catalogs, please request them through the inquiry form on our company website.*
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Company information
Since its establishment in 1969, Kyoka Soil Engineering has embraced the three keywords of Creativity, Challenge, and Collaboration, under the corporate philosophy of "Continuity is Strength." We have been committed to technological innovation and the creation of new markets in the field of ground reinforcement through collaborative research with academia and joint research across different industries. Our strengths lie in our ability to plan and develop cutting-edge technologies in the field of ground improvement and reinforcement, as well as our capability to communicate these technologies to the market through our ground injection development mechanisms. We are determined to advance our efforts towards social contribution through the various intellectual properties we possess.