FEATURE ARTICLE A Brief History of Deep Mixing Methods ISSUE :LANDMARKS SPECIAL It is a common misconception that the history of Deep Mixing Methods (DMM) in the United States dates from 1986 when SMW Seiko Inc., a subsidiary of Japan’s Seiko Kogyo Company, established itself in the Bay area of California. However, we believe that Intrusion Prepakt Co.’s patented MIP (Mixed in Place) system had been used, albeit sporadically (about 30 projects are recorded), since 1954. Ironically, by 1961 this single auger method was extensively used under license in Japan for excavation support and groundwater control, by Seiko Kogyo Company. By 1972, the original MIP technique had been succeeded by more advanced Japanese methods, involving multiple augers. Intrusion Prepakt had long since become defunct. The first systematic studies of contemporary DMM in Japan began in 1967 when the Port and Harbor Research Institute of the Ministry of Transportation AUTHORS began laboratory testing using granular and powdered lime for treating soft marine soils. Fundamental studies continued through the early 1970s, by which time the development of industrial scale equipment was well advanced, having its first application on a marine trial near Haneda Airport. Coincidentally, laboratory and field research also began in 1967 in Sweden (“Swedish Lime Column Method”) for treating soft clays using unslaked lime. Reportedly the progenitor was a Norwegian, Kjeld Paus, who had made observations on fluid lime columns in the United States. Developments in Japan and the Nordic countries seem to have proceeded independently until 1975 when the technology leaders from each group (Broms and Boman; and Okumura and Terashi, respectively) presented their very similar findings at a conference in Bangalore, India. Limited technical exchanges ensued. The Nordic developments continued to focus on the use of dry reagents (cement and lime) and relatively light equipment, while the Japanese progressed into using fluid reagents (cement-based grouts) and heavier equipment for both marine and land-based projects. By 1986, there were a large number of proprietary (wet and dry) DMM systems (16,000,000 yd ) of ground treatment. In retrospect, it is surprising that SMW already accounting for over 12,000,000 m 3 Seiko’s move to the U.S. was not replicated by Japanese contractors (e.g., Tenox, Raito) until several years later, while Lime Cement Columns were not installed commercially in the U.S. until 1996 (by Stabilator). Instead, the trend in the U.S. market was for Ameri- can contractors to develop their own multi- axis systems, with Geo-Con leading in 1988 with DSM (Deep Soil Mixing) and, in 1989, with single-axis SSM (Shallow Soil Mixing), primarily for environmental remediations. Donald A. Bruce, President, Geosystems, L.P., Venetia, PA., and George M. Filz, P.E., Professor, Virginia Polytechnic Institute and State University, Department of Civil Engineering, Blacksburg, VA DEEP FOUNDATIONS • NOV/DEC 2013 • 53 in Japan, and a rapidly growing market 3
