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Minato-ku, Japan

Bradley B.A.,University of Canterbury | Bradley B.A.,Chuo University | Araki K.,Chemical Grouting Co. | Ishii T.,Chuo University | Saitoh K.,Chuo University
Soil Dynamics and Earthquake Engineering

This manuscript presents the results of an investigation into the effect of various configurations of lattice-shaped soil improvement on the seismic response of liquefiable soil deposits using 3-dimensional seismic effective stress analysis with an advanced constitutive model for sandy soils. The particular problem considered is based on the soil stratigraphy of the down-hole seismic array site at Port Island, Kobe, and the input ground motion recorded at this location in the 1995 Kobe earthquake. Nine different soil improvement geometries are considered by changing the number and wall thickness of improved soil cells for the site. For each of the different improvement geometries, the salient features of the ground response are presented, including: (i) peak surface acceleration, displacement and response spectra; (ii) excess pore pressure, stress path, and stress-strain response of the enclosed unimproved soil; and (iii) peak deformations of the improved soil, among others. Finally, the obtained results for all considered improvement geometries are summarised based on improved area ratio (RIA); improvement length-to-height ratio (RLH); and normalised construction cost (RCC). The results demonstrate the complexity of the seismic response and interaction between improved and enclosed liquefaction-susceptible native soils when subjected to strong ground shaking; the dependence on both the improved area and length-to-height ratios; as well as the wealth of insightful information that advanced effective stress analyses can provide for assessing the seismic response of such soil deposits. © 2013 Elsevier Ltd. Source

Ishihara K.,Chuo University | Kamata T.,Chemical Grouting Co.
Geotechnical, Geological and Earthquake Engineering

Features of the 2011 earthquake in Japan are characterized by predominance of the ground failure due to liquefaction and scour of the ground caused by Tsunami. Unprecedented long duration of the shaking combined with large aftershocks have generated the worst situations resulting in the extensive damage due to liquefaction over the Tokyo Bay and the downstream plain areas of the Tone River 300 ~ 400 km distant away from the epicentral area. In this paper, focus is placed on the characteristic features in the occurrence of liquefaction and consequent damage in the area of the downstream reaches of the Tone River. © Springer International Publishing Switzerland 2015 Source

Komiya K.,Chiba Institute of Technology | Yamanobe J.,Chemical Grouting Co. | Endo M.,Chiba Institute of Technology | Shiozawa T.,Chiba Institute of Technology
6th Japan-China Geotechnical Symposium, SJGS 2015

In situ soil-cement mixing is frequently used to minimize soil liquefaction, enhance soil strength and reduce soil permeability. For quality assurance purposes, drill core samples are taken from the soil-cement mixtures and unconfined compressive strength tests are carried out 28 days after mixing and placement, which may delay construction works. Clearly, there is a need to accurately predict the strength of soil-cement mixtures early. In this study, we prepared soil-cement mixtures with different proportions of clay, silt, sand, cement and water. The as-prepared specimens were subsequently cured at standard and various temperature, pressure and time conditions. We then compared the strength characteristics of the as-prepared soil-cement specimens. Unconfined compressive strength increases between 24 h and 48 h of accelerated curing; however, increasing the curing temperature does not lead to increases in strength. Compressive strength slightly increases with the curing pressure. Finally, the compressive strength depends on the cement and fines content and WTotal/C of the soil-cement mixtures. Source

Chemical Grouting Co. and EOS Remediation LLC | Date: 2014-03-19

A contaminated soil remediation method activates a microorganism in soil contaminated with a toxic chemical substance. The contaminant is decomposed by a biodegradation reaction of the microorganism. The method involves forming a boring hole reaching into contaminated soil. A rod whose end is provided with a jet device is inserted into the boring hole. The contaminated soil is cut in a manner forming a flat-plate area in which the soil is intermittently cut by a microorganism activator, and the soil and the microorganism activator are mixed, by jetting water and/or the microorganism activator from the jet device.

Yoshida H.,Chemical Grouting Co. | Saito K.,Chuo University | Ishihara K.,Chuo University
Geotechnical Society of Singapore - International Symposium on Ground Improvement Technologies and Case Histories, ISGI'09

A brief description is given of the in-situ technique of drilling a long curved hole under the ground. As an example of utilizing this method, a conduct of in-situ pilot test in Japan is introduced in which jet-grouted column were installed in the horizontal direction in a saturated sand deposit. This example indicated viability and applicability of the technique for improving soil deposits in curved alignments. Copyright © 2009 by Geotechnical Society of Singapore (GeoSS). Source

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