Practical Use of Cone Penetration Test

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(A) The field performance of sandy soil deposits during previous earthquakes was reviewed with emphasis on Static Cone Penetration Test qc-value, fines content and mean grain size. Based on the correlation between cyclic stress ratio and normalized <q_(c1)> -value, it was indicated that (1) extensive damage due to liquefaction would not occur for clean sands having <q_(c1)> -value greater than about 150 kgf/ <cm^2> and for the induced stress ratio due to earthquake less than 0.1, (2) sands containing more than 10 % fines or having mean grain size smaller than 0.25 mm show much greater in liquefaction resistance than clean sand having the same qc-value. Apart from that the empirical relationships separating liquefaction and non-liquefaction were proposed in terms of critical normalized ( <q_(c1)> )cr, critical (qc)cr, cyclic stress ratio, fines content and mean grain size.(B) A series of static cone penetration test and a newly developed vibro-cone penetration test were carried out on the loose saturated sand in a large calibration chamber. The effects of vertical stress, horizontal stress, rate of penetration and location of porous filter on the excess pore water pressure, static cone and vibro-cone resistance were observed. The static cone resistances estimated on the bases of spherical cavity expansion theory were compared with those from chamber test, and it could be seen that the predicted static cone resistance values agree well with observed one. The evaluation of soil stratigraphy and the correlations between cyclic stress ratio and vibro-cone resistance obtained from in-situ test were also presented.