自Athy於1930年提出孔隙率隨深度變化之方程式，開啟了孔隙率隨深度變化相關之研究。為考慮力學壓密作用，許多研究提出孔隙率隨有效應力變化之方程式，大致上遵循指數律(exponential law)或冪次律(power law)。除了有效應力對孔隙率之影響，應力歷史對地質材料之力學行為影響亦甚巨，本研究以室內三軸均向壓縮詴驗，嘗詴建立沉積岩之應力歷史相依孔隙率模式。本研究採用詴體來自TCDP之鑽井，利用高圍壓三軸均向壓縮孔隙量測儀，以獲得車籠埔斷層上下盤之沉積岩孔隙率隨有效圍壓變化之加壓解壓曲線，考慮岩石對應力之「記憶性」，以應力歷史相依孔隙率模式，計算TCDP鑽井穿過地層之孔隙率，並與井測值進行比較。最後，以井測波速計算之統體模數與孔隙率模型推求之統體模數隨深度之變化進行比較，結果發現，根據室內三軸詴驗獲得之應力歷史相依孔隙率模型，可合理模擬地層孔隙率及波速隨深度變化之趨勢。 The proposed porosity-depth relationship has been widely studied since the well known Athy’s law was proposed in 1930. Regarding to the effect of mechanical compaction, porosity-effective stress relationships have forms of exponential law or power law. Besides the effective stress, stress history also plays an important role on the mechanical behavior of geological materials. This study proposed a stress-history dependent porosity model of sedimentary rock based on laboratory work. The samples are assembled from TCDP boreholes. The porosities varied with effective confining pressure are derived, and showing the estimated porosity-depth relation fit in TCDP borehole log data. Final, the bulk modulus from seismic velocity of well logging also well reproduced based on the suggested model. It indicates that the stress-history dependent porosity model can simulate the relationships between porosity/velocity and depth in formations.
