一軸引張応力下での岩石の破壊過程に関する研究(除荷・載荷試験)

1.はじめに

2.実験方法および試料岩石

3.実験結果

 3.1 応力と歪

 3.2 応力とコンプライアンス

 3.3 コンプライアンスと非弾性歪

4.考察

 4.1 圧縮試験結果との比較とグリフィス軌跡

 4.2 コンプライアンスと非弾性歪

 4.3 強度破壊点以降での応力とコンプライアンス

 4.4 砂岩の特徴

5.まとめおよび今後の課題

参考文献

キーワード:岩石,一軸引張,コンプライアンス,弾性歪,プロセスゾーン


Failure Process of Rock in Uniaxial Tension

Abstract

The behavior of rock in tension is considered to be as important as in compression for designing underground structures, especially large ones. But few results of tensile tests have been reported.

The servo-controlled testing machine was used in this study, and uniaxial tension tests were conducted on six rocks (one granite, one andesite, one tuff and three sandstones). Complete stress-strain curves were successfully obtained, and compliance and irrecoverable strain were evaluated by unloading-reloading test. The main results can be summarized as follows;

1) Compliance increases through the whole process. But in the pre-failure region, the increase rate is relatively slight. On the other hand, compliance in the post-failure region increases rapidly with decrease of the load bearing capacity.
2) Irrecoverable strain is closely correlated with compliance change, i.e. with crack growth. The failure process of rock was discussed in detail based on the evaluation of compliance as well as irrecoverable strain.
3) The shape of stress-elastic strain curves in uniaxial tension tests are similar to those in uniaxial compression tests.

KEY WORDS: Rock, Uniaxial tension, Compliance, Elastic strain, Process zone