砂土在液化時滲透係數之量測

Measuring the Coefficient of Permeability of Sand during Liquefaction in Soil Column Tests

朱民虔(Min-Chien Chu)

指導教授 ： 葛宇甯

共同指導教授 ： 翁作新(Tzou-Shin Ueng)

國立臺灣大學/工學院/土木工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201601064

摘要

砂土在液化時，砂土的滲透係數是提供判讀、分析和模擬液化相關行為的重要參數。過去多藉由假設土壤排水狀況，或壓密理論及固化理論推得液化砂土的滲透性變化，但針對水流及土壤顆粒運動之假設，與實際情況並不相符，故本篇研究繼續針對先前台大土壤力學實驗室所做出但尚未完整的部分繼續進行實驗和探討。Wang (2014) 提出新的實驗方法，將液化及滲流實驗結合，探討越南石英砂液化前、中、後的試體的行為變化。而本論文研究中試驗包含兩部分 : 單純液化試驗、液化且向上滲流試驗。藉由實驗過程中求得的水力梯度與流速之關係，直接計算試體滲透係數。由實驗之結果發現，砂土液化時滲透性能夠達到初始未液化前滲透係數的五倍，而在液化期間砂土滲透性也會符合達西定律。

關鍵字

液化滲流 ； 達西定律 ； 滲透係數 ； Kozeny-Carman equation

並列摘要

The previous studies found that permeability was an important factor on excess pore water pressure dissipation and settlement after dynamic loading. Most researchers calculated the permeability during liquefaction from the settlement data based on consolidation theory assuming an upward flow through the soil during consolidation after liquefaction. The phenomenon of particle movements after liquefaction is better interpreted as sedimentation rather than consolidation. The solidification and consolidation theory may not be appropriate for considering the permeability after liquefaction. Therefore, a new experimental approach was proposed by Wang (2014), which combined the seepage and the liquefaction test on two different types of sand specimens to measure the permeability directly. This study was made to verify the behavior discovered by Wang, and to make the project more complete. The permeability of sand during liquefaction was about five times its initial value. From the test results, Darcy’s law was valid during liquefaction.

並列關鍵字

liquefaction and seepage ； Darcy’s Law ； permeability ； Kozeny-Carman equation

參考文獻

ASTM D4253 – 00 (2006), “Standard test methods for maximum index density and unit weight of soil using a vibratory table,” Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA.

ASTM D4254 – 00 (2006), “Standard test methods for minimum index density and unit weight of soils and calculation of relative density,” Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA.

Ha, S. I., Park, Y. H., Kim, and M. M. (2003), “Dissipation pattern of excess pore pressure after liquefaction in saturated sand deposits,” Transportation Research Record, Vol. 1821, No. 1, pp. 59-67.

Kim, S. R., Hwang, J. I., Ko, H. Y., Kim, M. M. (2009), “Development of dissipation model of excess pore pressure in liquefied sandy ground,” Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 135, No. 4, pp. 544-554.

Scott, R. F. (1986), “Solidification and consolidation of a liquefied sand column,” Soils and Foundations, Vol. 26, No. 4, pp. 23-31.