ABSTRACT

This research made use of the structured query language (SQL) of the Geographic Information Systems (GIS) to evaluate the soil liquefaction analysis. The optimization of the parameter analysis with the 298 sets liquefaction data after the Chi-Chi earthquake was discussed. The parameters considered in this study were depth of stratum, fine content, D50, depth of water level, plastic index, SPT-N and PGA. The threshold values of each parameter affected to liquefy could be determined to evaluate the soil liquefaction. The maximum correct probability to judge the soil liquefaction under different step analysis is 67.79% increasing to 88.93%by step optimization of the parameter analysis. Whole processes were only carried out in the GIS, which were not need other software to calculate, then converted the results to display by lapping the leveled liquefaction evaluation of the GIS. Based on this evaluating system by GIS, it could improve to establish the localization method of the soil liquefaction evaluation.

INTRODUCTION

According to the present simplify evaluation methods of liquefaction potential, the results of one site show only one-point potential after analyzing from field or laboratory experiments. However, the stratum was non-homogenous greatly. The result of liquefaction potential analysis on one location could not indicate the potential of a boring hole. To avoid the difference of soil properties, the geology statistics method were adopted to analysis liquefaction potential that considered the related parameters of soil by probability and displays the results with regional map. Based on the related study of liquefaction and earthquake, at least four kinds that affect liquefaction potential have been studied as follows:

  1. Soil properties: the characteristic of soil particle, fine content, plastic index, relative density, void ratio and clay content etc.

  2. Field conditions: overburden, water level, density, structure, distance of fault etc.

  3. Earthquake types: intensity, magnitude, duration etc.

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