不同細料含量貓羅溪砂土微型貫入試驗

台灣目前位於菲律賓海板塊與歐亞大陸板塊的交界面上，地震繁複。1999年921集集大地震造成嚴重災情，且於許多砂性土層地區發生了液化現象，這些地區包括台中港區、台中縣霧峰鄉與太平市、彰化縣員林鎮、南投縣草屯與南投市等地，並且發現這些液化土壤的細料含量都相當高，因此有必要針對台灣本土高細料含量的砂土液化問題進行研究。本研究改進前人之貫入錐，增加其精密度。並在標度槽中，K0狀況下，控制相同乾密度，細料含量不同的貓羅溪砂土進行微型貫入錐試驗，得到錐尖阻抗(qc)與摩擦阻抗(fs)。討論細料含量對錐尖阻抗與摩擦阻抗之影響，以及其土壤液化強度之關係。試驗結果顯示在隨著細料含量的增加錐尖阻抗會下降。在細料含量對摩擦阻抗影響方面，本研究在低細料含量有量得摩擦阻抗值，但在高細料含量卻無法量得。其原因可能為由於細料的增加，貫入時所激發的超額孔隙水壓使試體有效應力下降，在相同細料含量的情況下，不同埋設深度之水壓計超額水壓會隨著貫入深度增加而上升，直到貫入到其埋設位置後達最大值。依本研究結果推論，對圓錐貫入試驗所得的圓錐貫入阻抗值(qc)所作細料含量的修正是因為隨著細料含量的增加，qc1會下降而液化強度並無太大改變的緣故。本研究亦評估目前常用之CPT液化潛能評估法對本試驗結果之適合性，但結果並不理想。顯示這些評估法對於本土高細料含量土壤之適用性有待更進一步確認。

關鍵字

貫入試驗；液化強度；超額孔隙水壓；細料含量；錐尖阻抗

並列摘要

This study conducted mini-cone penetration test in the Maoluo River soils of different fines contents under K0 condition with improved precision of the sleeve friction measurement. The effect of fines content on cone penetration resistance and sleeve friction resistance was studied and its relation with the liquefaction resistance of the soil obtained in the cyclic triaxial tests was also evaluated. 　　The test result show the normalized cone penetration resistance decreased with increasing fines content of the Maoluo river soils and the excess pore water pressure increased with increasing fines content of the Maoluo river soils.This study descries that the effects of the excess pore water pressure generation on mini cone penetration resistance and sleeve friction resistance. The results of using the CPT-based liquefaction potential evaluation methods are not in good agreements with those of the laboratory test in this study. The reason maybe that the soils classification methods of the existing methods are not suitable for the local soils with high fines content in Taiwan.

並列關鍵字

cone penetration test ； fines contents ； cone penetration resistance ； liquefaction potential ； excess pore water pressure

參考文獻

[1] Seed, H. B., Tokimatsu, K., Harder, L. F. and Chung, R. M. (1985), “The influence of SPT procedures in soil liquefaction resistance evaluations,” Journal of Geotechnical Engineering Vol. 111, No. 12, pp. 1425-1445.

[2] Stark, T. D. and Olson, S. M. (1995), “Liquefaction resistance using CPT and field case histories,” Journal of Geotechnical Engineering, ASCE, Vol. 121, No. 12, pp. 856-869

[3] Robertson, P. K. and Wride, C. E. (1998), “Evaluating cyclic liquefaction potential using the cone penetration test,” Canada Geotech. J., Vol. 35, pp. 442-459.

[6] Shibata, T., and Teparaksa, W. (1988), “Evaluation of liquefaction potentials of soils using cone penetration tests,” Soils and Foundations, Vol. 28, No. 2, pp. 49-60.

[7] Olsen, R. S. (1997), “Cyclic Liquefaction based on the Cone Penetrometer Test,” Proceedings of the NCEER Workshop of Evaluation of Liquefaction Resistance of Soils, pp. 225-276.

國際替代計量

不同細料含量貓羅溪砂土微型貫入試驗

全文下載

主題瀏覽