Fracture Mechanics Study of Shear Type Fracture Process Zone in Microcracking Materials

微裂材料剪切型断裂过程区断裂力学研究

• 批准号: 10650068
• 负责人: HASHIDA Toshiyuki
• 金额: $ 2.24万
• 依托单位: TOHOKU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650068/
• 关键词: Geothermal Energy Extraction; Hydraulic Fracture Growth; Shear Type Fracture Process Zone; Multiple Cracking; Confining Pressure; Fracture Criterion; Shear Weakening Model; Embedded Crack Element; 水圧破砕き裂進展

The objective of this research is to develop a fracture mechanics method for predicting the growth of hydraulically driven cracks in deep-seated rock masses for next generation geothermal energy extraction. The research results are described below for the each research task (I-IV).Task (I) : Fracture criterion of rocksTension and compression tests of Iidate granite were conducted at confining pressures up to 150 MPa and pore pressure up to 50 MPa. Tension softening and shear weakening curves were deduced from the test results. It was shown that the deduced experimental curves were independent of the confining and pore pressures used in this study, and that the relationships can be employed for analyzing the mixed mode crack growth.Task (II) : Simulated hydraulic fracturing experimentMini-hydraulic fracturing tests were performed on thick-walled cylindrical specimens under a variety of confining pressure. The tests indicated that an opening type crack was created when the differential stress was less than 100 MPa and a shear type crack was initiated if the differential stress exceeded 100 MPa. This observation suggests that shear fracture may be induced by hydraulic injection in deep-seated rock masses.Task (III) : FEM code for analyzing the growth of hydraulically driven cracks A FEM code was newly developed by employing an embedded crack element. The fracture criterion determined in Task (I) was incorporated into the code the crack growth condition.Task (IV) : Numerical analysis of hydraulic fracturing and formation process of artificial reservoirs. The hydraulic crack growth at depth was examined using the FEM code under a typical tectonic stress condition. It was shown that the crack growth was opening type at shallower regime and at greater depth shear fracture was predicted to occur followed by the transition to open fracture.

本研究的目的是开发一种断裂力学方法，用于预测下一代地热能开采的深层岩体中水力驱动裂缝的生长。以下是每项研究任务（一至四）的研究结果。任务（一）：岩石的断裂准则在围压150 MPa和孔隙压力50 MPa条件下，对花岗岩进行了拉伸和压缩试验。根据试验结果，推导出了拉伸软化和剪切弱化曲线。结果表明，推导出的实验曲线与围压和孔隙压力无关，可以用于分析复合型裂纹扩展。任务（II）：模拟水压致裂实验对厚壁圆筒试件进行了不同围压下的小型水压致裂试验。试验结果表明，当差应力小于100 MPa时，产生张开型裂纹;当差应力大于100 MPa时，产生剪切型裂纹。这一观察表明，剪切断裂可能会引起液压注入在深层次的岩体。任务（III）：有限元代码用于分析的增长液压驱动的裂纹有限元代码是新开发的，采用嵌入式裂纹元素。将课题（I）中确定的断裂准则引入到裂缝扩展条件中。课题（IV）：人工油气藏水力压裂及成藏过程的数值分析。在典型的构造应力条件下，使用有限元程序研究了水力裂缝的深度扩展。结果表明，裂纹扩展是开放型在较浅的制度，并在更大的深度剪切断裂发生后，过渡到开放断裂。

项目成果

橋本健嗣、高橋亨、加藤愛太郎、大中康譽、橋田俊之: "高温・高圧水環境下における花こう岩のせん断破壊挙動に関する研究"日本機械学会 東北学生会学生員卒業研究発表講演会論文集(2000年3月4日、山形大学工学部). in press (2000)

桥本健二、高桥彻、加藤爱太郎、小中康孝、桥田敏之：《高温高压水环境下花岗岩剪切断裂行为研究》日本机械工程学会东北学生会学生会员毕业研究发表演讲会论文集（ 2000 年 3 月 4 日，山形大学工学部出版 (2000)。

A-M.Wulff,T.Hashida,K.Watanabe and H.Takahashi: "Attenuation behavior of tufaceous sandstone and granite during microfracturing"Geophysical Journal International. Vol.139. 395-409 (1999)

A-M.Wulff、T.Hashida、K.Watanabe 和 H.Takahashi：“凝灰质砂岩和花岗岩在微压裂过程中的衰减行为”国际地球物理杂志。

Kenji Hashimoto, Toru Takahashi, Aitaro Kato, Michiyasu Ohnaka, Toshiyuki Hashida: "Fracture Mechanics Study of Shear Faulting in Granite under High Temperature and Pressurized Water Environment"Proceedings of the 30th Annual Meeting of JSME Tohoku Region

Kenji Hashimoto、Toru Takahashi、Aitaro Kato、Michiyasu Ohnaka、Toshiyuki Hashida：《高温高压水环境下花岗岩剪切断层断裂力学研究》JSME东北地区第30届年会论文集

橋本健嗣、高橋 亨、加藤愛太郎、大中康譽、橋田俊之: "高温・高圧水環境下における花こう岩のせん断破壊挙動に関する研究"日本機械学会 東北学生会学生員卒業研究発表講演会論文集(2000年3月4日、山形大学工学部). (in press). (2000)

Kenji Hashimoto、Toru Takahashi、Aitaro Kato、Yasutaka Onaka、Toshiyuki Hashida：《高温高压水环境下花岗岩的剪切断裂行为研究》日本机械工程学会东北学生会学生会员毕业研究报告讲座（2000 年 3 月 4 日，山形大学工程学院）（2000 年出版）。

Z.Jing,J.Willis-Richards,K.Watanabe and T.Hashida: "A New 3-D Stochastic Model for HDR Geothermal Reservoir in Fractured Crystalline Rock"Proceedings of 4th International HDR Forum (Strasbourg). (in press). (2000)

Z.Jing、J.Willis-Richards、K.Watanabe 和 T.Hashida：“A New 3-D Stochastic Model for HDR Geo Thermal Reservoir in Fractured Crystalline Rock”第四届国际 HDR 论坛（斯特拉斯堡）论文集。