CN111678776B - Indirect stretching device for testing tensile strength of rock - Google Patents
Indirect stretching device for testing tensile strength of rock Download PDFInfo
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- CN111678776B CN111678776B CN202010330288.4A CN202010330288A CN111678776B CN 111678776 B CN111678776 B CN 111678776B CN 202010330288 A CN202010330288 A CN 202010330288A CN 111678776 B CN111678776 B CN 111678776B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A10/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE at coastal zones; at river basins
- Y02A10/23—Dune restoration or creation; Cliff stabilisation
Abstract
The invention discloses an indirect stretching device for testing the tensile strength of a rock, wherein a supporting block is placed on a loading platform of a compression testing machine; the upper part semi-cylindrical machining piece and the lower part semi-cylindrical machining piece are placed in the hollow rock sample, a groove is formed in the bottom of the lower part semi-cylindrical machining piece, and a supporting filler strip is arranged in the groove; the sample side loading block and the end loading block are respectively arranged on two sides of the upper surface of the loading base plate, a cutting groove is formed at the bottom of the sample side loading block, and the sample side loading block is erected on the support filler strip across the hollow rock sample through the cutting groove; one end of the fixing rod is connected with the end part loading block, the middle part of the fixing rod is fixed at the top of the supporting block, and the other end of the fixing rod is inserted into the upper part semi-cylindrical workpiece to be fixed with the hollow rock sample. The invention solves the problem of uneven tensile stress generated on the damaged surface in the indirect rock tensile test process.
Description
Technical Field
The invention relates to a demonstration material testing technology, in particular to an indirect stretching device for testing the tensile strength of a rock.
Background
In engineering practice, tensile failure is a major factor causing rock or rock mass failure. However, in engineering analysis, the focus of research is often the unconfined compressive strength of the whole rock test piece, and the tensile strength is neglected. However, rock material is a brittle material, and one of the most distinct characteristics is that the tensile strength is much less than the compressive strength, which is typically 4-10 times greater than the tensile strength of the rock material, and ignoring this parameter may result in unreliable final results. Therefore, the understanding of the tensile properties of rock materials under tensile loading is of great importance to the design and construction of rock-like structures.
The existing test methods for measuring the tensile strength of the rock are mainly divided into a direct method and an indirect method. Theoretically, uniaxial tensile test is the most scientific and effective method for determining uniaxial tensile strength, but the problems of eccentric load, asymmetric test piece, stress concentration, material defects and the like are difficult to solve in the uniaxial tensile test, so that the indirect method (splitting method) is mostly used for measuring the tensile strength of the rock. However, the cleavage tensile strength of the test piece obtained by the indirect test cannot generate uniform tensile stress on the failure surface, and the stress on the failure surface is usually not uniaxial, so that a reasonable and effective indirect tensile device needs to be developed urgently to obtain reliable tensile strength of the rock, and a reference is provided for the design of actual engineering.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to solve the problem that uneven tensile stress is generated on a damaged surface in the existing rock indirect tensile test process, and provides an indirect tensile device for testing the tensile strength of a rock.
The technical scheme is as follows: the invention discloses an indirect stretching device for testing the tensile strength of a rock, which comprises a loading base plate, a sample side loading block, an end loading block, a supporting filler strip, an upper semi-cylindrical machined part, a lower semi-cylindrical machined part, a fixed rod and a supporting block, wherein the sample side loading block is arranged on the upper part of the supporting base plate; the supporting block is placed on a loading platform of the compression testing machine; the upper semi-cylindrical workpiece and the lower semi-cylindrical workpiece are placed in the hollow rock sample, a groove is formed in the bottom of the lower semi-cylindrical workpiece, and a supporting filler strip is arranged in the groove; the sample side loading block and the end loading block are respectively arranged on two sides of the upper surface of the loading base plate, a cutting groove is formed at the bottom of the sample side loading block, and the sample side loading block is erected on the support filler strip across the hollow rock sample through the cutting groove; one end of the fixing rod is connected with the end part loading block, the middle part of the fixing rod is fixed at the top of the supporting block, and the other end of the fixing rod is inserted into the upper part semi-cylindrical workpiece to be fixed with the hollow rock sample.
Furthermore, a fixing hole is formed in a position, corresponding to the end part, of one end of the fixing rod, the fixing hole is matched with a through hole in the side edge of the end part loading block, and the fixing rod and the end part loading block are fixed by inserting a bolt into the fixing hole and the through hole; the middle part of the upper semi-cylindrical workpiece is provided with a cylindrical prefabricated hole, the diameter of the prefabricated hole is larger than that of the fixed rod, and the other end of the fixed rod penetrates through the prefabricated hole to fix the hollow rock sample; the middle part of the fixed rod is provided with a fixed hole, the fixed hole is matched with a through hole on the side surface of the supporting block, and the fixed rod is fixed with the supporting block by inserting a bolt into the fixed hole and the through hole.
In order to enhance the stability of the whole structure, the top of the supporting block and the bottom of the end loading block are respectively provided with a cutting groove for placing the fixing rod.
In order to improve the tensile property, the supporting block, the fixing rod and the bolt are all made of stainless steel.
Furthermore, the loading base plate is made of a steel plate, and the thickness of the loading base plate is 9-10mm; the diameter of the fixed rod is 18-20mm, and the length of the fixed rod is 330-350m; the diameter of the bolt is 8-10mm, and the diameters of the two fixing holes on the fixing rod are larger than the diameter of the bolt.
Further, the hollow rock sample is prism-shaped overall, for example, the overall size of the hollow rock sample is 120 × 120 × 40mm, a cylindrical hole is preset in the middle of the hollow rock sample, an upper semi-cylindrical workpiece and a lower semi-cylindrical workpiece are sequentially arranged in the cylindrical hole one above the other, the diameter of the cylindrical hole is 55-60mm, and the other end of the fixing rod penetrates into the cylindrical hole.
Further, the depth of the cutting groove on the supporting block is 58-60mm, the width of the cutting groove is wider than the diameter of the fixing rod, and the through hole on the side surface of the supporting block passes through the cutting groove; the depth of the bottom cutting groove of the end loading block is 24-25mm, the width of the cutting groove is larger than the diameter of the fixed rod, and a through hole on the side edge of the end loading block penetrates through the cutting groove.
Further, the lower semi-cylindrical workpiece is in a semi-annular shape integrally, the radial thickness of the lower semi-cylindrical workpiece is 4-5mm, the groove depth of a groove at the bottom of the lower semi-cylindrical workpiece is 2-3mm, and the groove width of the groove at the bottom of the lower semi-cylindrical workpiece is 19-20mm; the whole supporting cushion strip is in a prismatic shape, the size of the longitudinal section of the supporting cushion strip is 20 multiplied by 10mm, and the length of the supporting cushion strip is 128-130mm; the depth of the notch of the sample side loading block is 78-80mm, and the width of the notch is 48-50mm.
Has the advantages that: according to the invention, the compression load applied to the two loading blocks by the compression loading equipment is converted into the tensile load through the fixing rods fixed on the supporting blocks, and the tensile load acts on the prepared rock sample, so that uniform axial tension is generated on the rock sample damage surface, the rock sample is damaged in a tensile manner, and a simple and reliable indirect method is provided for measuring the tensile strength of the rock.
Drawings
FIG. 1 is a schematic view of the overall structure of the present invention;
FIG. 2 is a schematic view of a support block according to the present invention;
FIG. 3 is a schematic view of an end loading block of the present invention;
FIG. 4 is a schematic illustration of rock sample assembly according to the present invention;
FIG. 5 is a schematic view of two semi-cylindrical workpieces according to the present invention;
FIG. 6 is a schematic view of a test piece side loading block in the present invention;
FIG. 7 is a schematic diagram of the force applied to a rock sample according to the present invention;
fig. 8 is a perspective view of the overall structure of the present invention.
Detailed Description
The technical solution of the present invention is described in detail below, but the scope of the present invention is not limited to the embodiments.
As shown in fig. 1 and 8, an indirect stretching apparatus for testing tensile strength of rock of the present invention includes an upper semi-cylindrical workpiece 1, a lower semi-cylindrical workpiece 2, a support filler strip 3, a sample side loading block 4, an end loading block 5, a support block 6, a fixing rod 7, a hollow rock sample 9, and a loading filler plate 10.
As shown in fig. 2, the supporting block 6 is placed on a loading platform of the compression testing machine, a cutting groove is formed at the upper part of the supporting block 6, and a cylindrical fixing hole is formed at the side edge of the supporting block, and the cylindrical fixing hole penetrates through the cutting groove along the length direction.
As shown in figure 1, the fixing rod 8 is placed at the grooving position of the supporting block 6, fixing holes with the diameter of 10mm are formed in the middle of the fixing rod 8 and 50mm away from the end part, the fixing hole in the middle of the fixing rod 8 is aligned with the fixing hole in the side edge of the supporting block 6, the fixing hole penetrates through the fixing hole in the middle of the fixing rod 8 and penetrates through the fixing hole in the other side edge of the supporting block 6, and the bolt 7 penetrating out of the fixing hole in the other side edge of the supporting block 6 is fixed.
As shown in fig. 3, the bottom of the end loading block 5 is provided with a groove, the groove depth is 25mm, the groove width is slightly larger than the diameter of the fixing rod, and the side of the loading block 5 is provided with a through fixing hole which penetrates through the preformed groove at the bottom of the loading block. The fixing hole is aligned with the fixing hole at the end part of the fixing rod 8, penetrates through the fixing hole at the side edge of the loading block 5, penetrates through the fixing hole at the end part of the fixing rod 8, and is fixed by a bolt 7 penetrating out of the fixing hole at the other edge of the loading block 5.
As shown in fig. 4 and 5, in the present embodiment, the size of the rock sample 9 for indirect tensile test is 120 × 120 × 40mm, and a cylindrical hole with a diameter of 60mm needs to be prefabricated in the middle of the rock sample 9 during sample preparation; the upper semi-cylindrical workpiece 1 and the lower semi-cylindrical workpiece 2 are placed in the hole, and the two semi-cylindrical workpieces are shown in FIG. 5; a cylindrical prefabricated hole is formed in the middle of the upper semi-cylindrical workpiece 1, the diameter of the hole is slightly larger than that of the fixing rod 8, and the other end of the fixing rod 8 penetrates through the hole to fix the rock sample 9; the lower semi-cylindrical workpiece 2 is integrally semi-annular, the bottom of the lower semi-cylindrical workpiece is provided with a groove, the width of the groove is 20mm, and the groove is used for placing the supporting filler strip 3; the support skid is 20 x 10mm in cross-section and 130mm long, and the sample side loading block 4 is assumed to be on the support skid across the rock sample 8.
As shown in fig. 6, the sample side loading block 4 is formed at the bottom thereof with a notch having a depth of 80mm and a width of 50mm, and is formed at the side thereof with a through hole having a rectangular cross section through which the fixing rod 8 is inserted into the prepared hole in the middle of the upper semi-cylindrical workpiece 1.
The loading base plate 10 is placed on the two loading blocks, so that the compression testing machine can apply compression load uniformly. The compressive load is converted into a tensile load through a fixing rod 8 placed at the supporting block 6 to be applied to a rock sample 9, so as to measure the tensile strength of the rock sample 8.
In the invention, in order to adapt to rock samples 9 with different sizes, the sizes of corresponding parts (such as the sample side loading block 4, the end loading block 5, the loading base plate 10 and the like) and corresponding grooves or cutting grooves can be adaptively adjusted.
The specific working principle of the invention is as follows:
two ends of the loading base plate 10 are respectively arranged on the sample side loading block 4 and the end part loading block 5, and the supporting block 6 is arranged on a loading platform of the compression testing machine. In actual operation, as shown in fig. 7, the sample side loading block 4 and the end loading block 5 are loaded at the same time, the compression load applied to the two loading blocks by the compression loading device is converted into a tensile load through the fixing rod 8 fixed on the supporting block 6 to act on the prepared rock sample 9, and a uniform axial tension is generated on the fracture surface of the rock sample 9, so that the rock sample 9 is fractured in tension.
Claims (8)
1. An indirect stretching device for testing tensile strength of rocks is characterized in that: the device comprises a loading base plate, a sample side loading block, an end loading block, a supporting filler strip, an upper semi-cylindrical workpiece, a lower semi-cylindrical workpiece, a fixing rod and a supporting block; the supporting block is placed on a loading platform of the compression testing machine; the upper semi-cylindrical workpiece and the lower semi-cylindrical workpiece are placed in the hollow rock sample, a groove is formed in the bottom of the lower semi-cylindrical workpiece, and a supporting filler strip is arranged in the groove; the sample side loading block and the end loading block are respectively arranged on two sides of the upper surface of the loading base plate, a cutting groove is formed at the bottom of the sample side loading block, and the sample side loading block is erected on the support filler strip across the hollow rock sample through the cutting groove; one end of the fixing rod is connected with the end loading block, the middle part of the fixing rod is fixed at the top of the supporting block, and the other end of the fixing rod is inserted into the upper part semi-cylindrical workpiece to be fixed with the hollow rock sample.
2. The indirect stretching apparatus for testing tensile strength of rock according to claim 1, wherein: a fixing hole is formed in one end of the fixing rod at a corresponding distance from the end, the fixing hole is matched with a through hole in the side edge of the end loading block, and the fixing rod is fixed with the end loading block by inserting a bolt into the fixing hole and the through hole;
the middle part of the upper semi-cylindrical workpiece is provided with a cylindrical prefabricated hole, the diameter of the prefabricated hole is larger than that of the fixed rod, and the other end of the fixed rod penetrates through the prefabricated hole to fix the hollow rock sample;
the middle part of the fixed rod is provided with a fixed hole, the fixed hole is matched with a through hole on the side surface of the supporting block, and the fixed rod is fixed with the supporting block by inserting a bolt into the fixed hole and the through hole.
3. The indirect stretching apparatus for testing tensile strength of rock according to claim 1, wherein: and the top of the supporting block and the bottom of the end loading block are respectively provided with a cutting groove for placing a fixed rod.
4. The indirect stretching apparatus for testing tensile strength of rock according to claim 2, wherein: the supporting block, the fixing rod and the bolt are all made of stainless steel.
5. The indirect stretching apparatus for testing tensile strength of rock according to claim 1, wherein: the loading base plate is made of a steel plate, and the thickness of the loading base plate is 9-10mm; the diameter of the fixed rod is 18-20mm, and the length of the fixed rod is 330-350m; the diameter of the bolt is 8-10mm, and the diameter of the two fixing holes on the fixing rod is larger than that of the bolt.
6. The indirect stretching apparatus for testing tensile strength of rock according to claim 1, wherein: the hollow rock sample is integrally prismatic, a cylindrical hole is preset in the middle of the hollow rock sample, an upper semi-cylindrical workpiece and a lower semi-cylindrical workpiece are sequentially arranged in the cylindrical hole from top to bottom, the diameter of the cylindrical hole is 55-60mm, and the other end of the fixing rod penetrates into the cylindrical hole.
7. The indirect stretching apparatus for testing tensile strength of rock according to claim 3, wherein: the depth of the cutting groove on the supporting block is 58-60mm, the width of the cutting groove is wider than the diameter of the fixing rod, and the through hole on the side surface of the supporting block penetrates through the cutting groove;
the depth of the bottom cutting groove of the end loading block is 24-25mm, the width of the cutting groove is larger than the diameter of the fixed rod, and a through hole on the side edge of the end loading block penetrates through the cutting groove.
8. The indirect tension apparatus for testing tensile strength of rock as claimed in claim 1, wherein: the lower semi-cylindrical workpiece is integrally semi-annular, the radial thickness of the lower semi-cylindrical workpiece is 4-5mm, the groove depth of a groove at the bottom of the lower semi-cylindrical workpiece is 2-3mm, and the groove width of the groove at the bottom of the lower semi-cylindrical workpiece is 19-20mm;
the whole supporting cushion strip is in a prismatic shape, the size of the longitudinal section of the supporting cushion strip is 20 multiplied by 10mm, and the length of the supporting cushion strip is 128-130mm;
the depth of the notch groove of the sample side loading block is 78-80mm, and the width of the notch groove is 48-50mm.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010330288.4A CN111678776B (en) | 2020-04-24 | 2020-04-24 | Indirect stretching device for testing tensile strength of rock |
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| CN202010330288.4A CN111678776B (en) | 2020-04-24 | 2020-04-24 | Indirect stretching device for testing tensile strength of rock |
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| CN111678776A CN111678776A (en) | 2020-09-18 |
| CN111678776B true CN111678776B (en) | 2023-04-18 |
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| CN113218769B (en) * | 2021-04-23 | 2022-06-10 | 河海大学 | Indirect stretching device and method for testing tensile strength of rock |
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| RU1837199C (en) * | 1990-03-05 | 1993-08-30 | Институт Проблем Прочности Ан Усср | Method of predicting crack-resistance of material with regard to construction service conditions |
| CN2884182Y (en) * | 2006-01-26 | 2007-03-28 | 中国科学院武汉岩土力学研究所 | Dynamic draw-load testing equipment for rock |
| CN101629886A (en) * | 2009-01-13 | 2010-01-20 | 西安科技大学 | Method for testing high-temperature indirect tensile strength of bituminous mixture |
| CN201548457U (en) * | 2009-11-18 | 2010-08-11 | 西安科技大学 | Indirect tensile strength test instrument |
| CN103837420B (en) * | 2014-03-14 | 2016-06-29 | 唐山轨道客车有限责任公司 | Pulse fatigue testing machine fatigue experimental device and pulse fatigue testing machine |
| KR101748809B1 (en) * | 2015-05-29 | 2017-06-23 | 대구대학교 산학협력단 | Test method for direct tensile strength measurement utilizing hollow hole and testing device for tensile strength using thereof |
| CN206132504U (en) * | 2016-08-06 | 2017-04-26 | 中咨公路工程监理咨询有限公司 | Cylinder test block brazilian test anchor clamps |
| CN207937266U (en) * | 2018-01-09 | 2018-10-02 | 山西大学 | polluted soil tensile strength tester |
| JP7159720B2 (en) * | 2018-09-11 | 2022-10-25 | 日本製鉄株式会社 | Method for evaluating relative strength of multiple types of sintered ore |
| AU2019101006A4 (en) * | 2019-09-04 | 2019-10-10 | The University Of Adelaide | Snap-Back Indirect Tensile Test |
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