本研究針對花崗岩石材分別進行雙扭試驗及雙懸臂樑試驗求取I型破裂韌度。在選擇影響破裂韌度的因子方面，於雙扭試驗部份，改變試體幾何條件，加載速率、初始裂紋長度；雙懸臂樑方面，改變試體幾何條件、初始裂紋長度、溝槽條件。本研究並利用有限元素分析軟體ABAQUS，來驗証吾人建議之無溝槽雙懸臂樑試驗破裂韌度解析解及求解有溝槽試體的數值解。在試驗過程中使用改良式裂紋量測系統分別對上述試驗求取裂紋擴展速度。
研究結果顯示：(1).雙扭試驗的破裂韌度，在選定的幾何條件下，隨初始裂紋長度變化而變化，但試體尺寸及加載速率對破裂韌度值影響並沒有顯著的不同。(2).以楔形塊施加荷重之雙懸臂樑試驗破裂韌度值隨初始裂紋長度無顯著變化；不同試體尺寸的試驗結果顯示，較大的試體有較大的破裂韌度；在溝槽條件的影響下，較大的試體有較大的差距。(3).以ABAQUS軟體模擬以楔形塊施加荷重之無溝槽雙懸臂樑試驗，破裂韌度數值解與吾人建議的解析解結果比較後，誤差在-0.16％～1.9％。(4).在裂紋擴展速度的結果中，雙扭試驗的試體較大時，其裂紋擴展速度試驗值與解析解值差距較大。另外，其試驗值與雙懸臂樑試驗結果相較之下大了1.83倍。

This study proposes double torsion(DT) test and double cantilever beam(DCB) test to determine the fracture toughness of granite plates. In DT test, the effects of specimen geometry, loading rate, and initial crack length are investigated. In DCB test, the effects of specimen geometry, initial crack length, and specimen with or without groove are investigated. A finite element software, ABAQUS, is carried out to obtain the numerical solution of fracture toughness of DCB specimen by wedge loading. The numerical results are compared with the analytical solution of ungroove specimen. Additionally, a KYOWA crack measurement system is modified to measure the crack growth velocity in DT test and DCB test.
The major findings are as following: (1) The fracture toughness of DT test varies with initial crack length in specimen geometry. (2) The fracture toughness of the bigger DCB specimen are greater than the one from small DCB specimen. (3) In DCB test, the discrepancy between the numerical solution and analytic solution is -0.16% ~ 1.9%. (4) The difference of crack growth velocity in big size DT specimen between experimental results and analytic solution is large. Besides, the crack growth velocity measured from DT test is 1.83 times the one from DCB test.

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