CASE STUDIES OF STONE COLUMNS IMPROVEMENT IN SEISMIC AREAS
Soil improvement with stone columns is often implemented in seismic areas in particular as a countermeasure against liquefaction. The efficiency of stone columns can be explained by the compaction effect during their execution, by the reduction of the seismic stress on the soil, and by their draining effect as well. A historical evolution of the first realisations is presented, followed by an inventory of the observed performance of such systems in seismic conditions. Then, recent applications of stone columns combined with pile foundations are presented. Key-Words: seismic area, stone columns, liquefaction, case study, pile foundation.
Mitigation of liquefaction and associated ground deformations by stone columns
Soil liquefaction and associated ground failures have been a major source of damage during the past earthquakes. The risk of liquefaction and associated ground deformation can be reduced by various ground-improvement methods including the stone column (gravel drain) technique. This paper presents the current state of the stone column technologies as a liquefaction countermeasure. A comprehensive review is provided aiming to: (a) identify key considerations for the general use of stone columns as a liquefaction countermeasure, (b) provide insights for design and construction, (c) compile the latest research developments, and (d) identify sources of useful information. Case histories of field applications and observed field performance are cited to portray different stone column applications and observed effectiveness. The paper identifies areas where more research is needed and includes recommendations for future research and development.
The Illinois Legislature
It further provides that the county must have voted "for license" at the last general election on that subject. Also, that the petition, together with all names and addresses on it, must first be published in at least two issues of some newspaper published in the town where the petition was circulated, for at least ten days before the petition is acted upon. Any officer authorized to issue licenses violating the provisions of this act is liable to a fine of from $500 to $1000 and imprisonment in the county jail for from two to twelve months. The act does not repeal any local laws forbidding the sale of liquor, but is cumulative to all anti-liquor laws now in force. The final section is: "This Act being necessary for the public peace, health, and safety, shall take effect and be in force from and after December 31, 1913." The postponement of the time for going into effect was made io order not to interfere with licenses already issued and to give the liquor dealers time to adjust themselves to the provisions of the act. But the liquor people denied that the emergency clause could be attached to an act the operation of which was postponed nearly a year. They called attention to the omission of the word "immediate," and declared that the postponement was in itself sufficient evidence that it was not necessary for the "immmediate preservation of the public health, peace and safety." A petition for reference was circulated and the necessary number of signatures was secured. The attorney-general was first asked for his opinion as to whether the act was subject to the referendum. That officer stated that he could find no precedent for such a case. Basing his decision on reason and common sense he declared the act not subject to the referendum. The circuit court was then asked for a write of mandamus against the secretary of state to compel him to submit the act, but the court refused to grant it, saying that the attachment of the emergency clause was evidence that the legislature intended to prevent its submission. At this writing the question is pending on appeal before the supreme court.