Engineering of Ground for Liquefaction Mitigation Using Granular Columnar Inclusions: Recent Developments

Abstract

Problem statement: Liquefaction was the most hazardous damage during an earthquake. Ground improvement techniques were employed to mitigate liquefaction hazards. Most common methods to improve engineering properties of soils are densification, reinforcement, grouting/mixing and drainage. Among various remedial measures available, installation of columnar granular inclusions is the most widely adopted method for liquefaction mitigation. Approach: Columnar granular inclusions function as drains and permit rapid dissipation of earthquake induced pore pressures by virtue of their high permeability. Results: One of the chief benefits of ground treatment with granular piles is the densification of in situ ground by which the in-situ properties of the ground get modified to mitigate liquefaction potential. Further, the very high deformation modulus and stiffness of the granular pile material provide reinforcement for the in situ soil and offer another mechanism to mitigate liquefaction. The study described briefly the phenomenon of liquefaction and the associated features. A short discussion on various ground improvement methods available for liquefaction mitigation was presented highlighting the importance of columnar inclusions. Construction methods of different granular columnar inclusions like sand compaction piles/ granular piles were discussed briefly. Recent developments in the research of columnar granular inclusions as liquefaction counter measures were presented in relation to physical, numerical and analytical model studies. Conclusion/Recommendations: Columnar granular inclusions were demonstrated to be very effective for liquefaction mitigation in different case studies and research investigations.

Numerical and Larg-Scale Laboratory Study of Rock Column Groups in Sandy Soil Behavior Improvement

“…e rupture will occur conically in the form of a general shear failure. Under these conditions, column deformation in various forms such as lateral expansion, punching, shear, and bending has been observed, but the failure of the rock column group is a general shear failure [5]. Failure due to buckling in the side columns of a group is possible when the column length is less than the critical length.…”

Centrifuge shaking table tests on effect of vertical drain systems for liquefied soil

“…As the historical document, this type dangerous catastrophe come along with strong earthquake and bring a lot of damages to those regions such as in the earthquakes of Niigata, Japan 1964 [1], Dagupan City, Philippines 1990, [2], Chi-Chi, Taiwan 1999 [3], Kocaeli, Turkey 1999 [4], and recent Tohoku earthquake, Japan 2011 [5]. On the major concerns for engineers, the prevention of those damage in seismically active regions is essential to research; besides, drainage methods are well known as liquefaction remediation that have been studied for several years and have traditionally included stone columns, gravel drains [6][7][8][9][10][11][12][13][14] or geosynthetic material drains. Apparently, for large soil areas with liquefiable deposits extending deep below the surface, soil replacement or densification is not an option [6].…”