於Barton節理面剪力強度公式含有JRC、ψ/sub b/、及JCS三個參數，尤其在中高應力下節瘤會發生剪斷破裂機制時，JCS之貢獻更形重要。實務上，一般常以室內NX尺度大小之岩心單壓(屬劈裂方式)強度替代之，兩者破壞機制並不儘相同，且兩者尚具有規模效應問題，故以岩心單壓強度直接代表JCS值值得進一步確認。本文以長度不等(但JRC相近)之自我相仿節理面模擬試體進行直剪試驗，依其剪力強度反求試體長度不等之節理壁材強度JCS，並與單壓強度規模效應趨勢比較。文中並提一種以剖面儀製造二維節理剖面之方法。 According to the Barton's shear strength criterion, the value of JCS is given by the compression strength .sigma./sub c/ of a rock core. The scale effect exists in both the JCS and .sigma./sub c/. However, the failure pattern of rock cores under uniaxial compression, a split pattern, is different from the shear fracture of joint asperity. This equivalent JCS that obtained from .sigma./sub c/ is doubted. This paper uses the self-affine joint profiles (with the identical JRC) in different length to perform shear tests. Then the back-calculated JCS from the peak shear strength for the different sized joints is compared to the uniaxial strength trend. By extending the utility of profilometer, a method to cut the 2D joint profile is also proposed.
第九屆大地工程學術研討會論文集=Proceedings of 9th Conference on Current Researches in Geotechnical Engineering