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Deep beam specimen and composite fracture toughness test method for rock i‑ii composite fracture toughness test

A composite fracture, I-II technology, which is applied to rock specimens for fracture toughness testing and in the field of fracture toughness testing, can solve problems such as difficult processing of specimens, achieve high reliability of test results, simple loading test methods, and structural simple effect

Inactive Publication Date: 2017-12-12
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the CCNBD and SCB specimens can realize the I-II composite fracture toughness test in the entire composite loading range from pure I mode to pure II mode by adjusting the crack inclination angle and crack length, etc., but as mentioned above, the specimens (especially Large size test piece) Difficult to process

Method used

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  • Deep beam specimen and composite fracture toughness test method for rock i‑ii composite fracture toughness test
  • Deep beam specimen and composite fracture toughness test method for rock i‑ii composite fracture toughness test
  • Deep beam specimen and composite fracture toughness test method for rock i‑ii composite fracture toughness test

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Embodiment 1

[0054] The deep beam specimen described in this embodiment is used for rock I-II composite fracture toughness test, see Figure 1~4 , the test material is sandstone, and the test piece body 1 is a cuboid shape, and the body is provided with an opening along the center line of the lower end surface thickness B direction of the body, extending to the inside of the body, and running through the front and rear end faces of the body thickness direction. The length L is 180mm, the width W is 90mm, and the thickness B is 76mm; the groove length a is 54mm (ratio to the specimen width W is 0.6), the angle β is 0°, and the thickness b is 0.7mm. The operation of rock I / II composite fracture test with the above specimens is as follows:

[0055] (1) Adjust the half-distance d of the support according to the scale of the three-point bending fixture, so that d is 63mm (ratio to the width W of the specimen is 0.7), and the difference between the front and rear ends of the two supports after a...

Embodiment 2

[0063] The deep beam specimen used for rock I-II composite fracture toughness test described in this embodiment, the test material is sandstone, the specimen body 1 is cuboid shape, and the body is provided with a center line along the thickness B direction of the lower end surface of the body The opening extends to the inside of the body and runs through the slit 2 of the front and rear end faces in the thickness direction of the body. The length L of the test piece is 180mm, the width W is 90mm, and the thickness B is 76mm; different from Example 1, the length a of the slit 2 is 36mm ( The ratio to the width W of the test piece is 0.4), and the thickness b is 0.7mm; different from Example 1, the angle β in this example is 20°. The operation of rock I / II composite fracture test with the above specimens is as follows:

[0064] (1) Adjust the half-distance d of the support according to the scale of the three-point bending fixture, so that d is 45mm (ratio to the width W of the ...

Embodiment 3

[0073] The deep beam specimen used for rock I-II composite fracture toughness test described in this embodiment, the test material is sandstone, the specimen body 1 is cuboid shape, and the body is provided with a center line along the thickness B direction of the lower end surface of the body The opening extends to the inside of the body and runs through the slit 2 of the front and rear end faces in the thickness direction of the body. The length L of the test piece is 180mm, the width W is 90mm, and the thickness B is 76mm; different from Example 1, the length a of the slit 2 is 36mm ( The ratio to the width W of the test piece is 0.4), and the thickness b is 0.7mm; different from Example 1 and Example 2, in this example β is 45.92°. The operation of rock I / II composite fracture test with the above specimens is as follows:

[0074] (1) Adjust the half-distance d of the support according to the scale of the three-point bending fixture, so that d is 45mm (ratio to the width W ...

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Abstract

The invention provides a deep beam test piece for a rock I-II composite fracture toughness test. The deep beam test piece has a rectangular main body. The main body is provided with an opening along a center line in a main body lower end surface thickness direction, and the opening extends into the main body and goes through cutting grooves arranged at the front and rear end surface along a main body thickness direction. An included angle beta of the surface of the cutting groove (2) and the cross section of the test piece main body perpendicular to the length direction is greater than or equal to 0 degree and less than or equal to 60 degrees. The width W of the test piece main body is controlled in a range of 0.5L+ / -0.01L. The thickness B of the test piece main body is 0.4 times greater than or equal to the length L and is greater than or equal to 30mm. L represents the main body length. The invention also provides a rock I-II composite fracture toughness test method utilizing the deep beam test piece. The deep beam test piece has a simple structure, is conducive to rock block processing, and realizes a rock I-II composite fracture toughness test in the whole composite loading zone from the pure I-type zone to the pure II-type zone.

Description

technical field [0001] The invention belongs to the field of rock fracture toughness testing, in particular to a rock specimen for fracture toughness testing and a fracture toughness testing method. Background technique [0002] Research on rock fracture toughness testing methods is an important prerequisite for accurately obtaining rock fracture toughness values, and it is also an important way to explore the theory and application of rock fracture mechanics. The International Society of Rock Mechanics (ISRM) successively suggested the herringbone notched short round rod short round rod (SR) sample (Barker L M.A simplified method for measuring planestrain fracture toughness[J].Engineering Fracture Mechanics,1977,9(2) :361-369), herringbone groove three-point bending round bar (CB) sample (Ouchterlony F.Suggested methods fordetermining the fracture toughness of rock[J].International Journal of Rock Mechanics and Mining Sciences,1988,25(2) :71-96), herringbone notched Brazil...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N3/02G01N3/20
Inventor 艾婷任利谢凌志张茹何柏罗毅王俊高超
Owner SICHUAN UNIV
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