In-situ testing device for concrete shear strength by double-side direct shear method

Abstract

The utility model provides a kind of in-situ detection device of concrete shear strength double-sided direct shear method, including H-shaped column test piece in entity concrete work pit, the H-shaped column test piece is provided with shear direction loading device in axial direction, makes H-shaped column test piece damage along the prescribed two shear surfaces, the H-shaped column test piece is provided with normal loading device embedded in work pit and the normal loading device is surrounded in H-shaped column test piece in vertical direction to the axis.The utility model applies different levels of normal load by normal loading device, obtains normal stress;While using shear direction loading device makes H-shaped column test piece damage along the prescribed two shear surfaces, measures corresponding shear load, obtains shear stress;According to normal stress and shear stress under each level of load, according to relevant standard, obtains shear strength, it is strong in practicality, accurate in detection, and reasonable in design.

Description

Technical Field

[0001] The invention relates to an in-situ detection device for concrete shear strength using a double-sided direct shear method. Background Art

[0002] Concrete shear strength is one of the fundamental physical and mechanical properties of concrete and is widely used in elastoplastic mechanics. In some projects, such as underground and tunnel construction, plain concrete composite linings in soft-hard rock transition zones and ground fissures are primarily in a plastic state, requiring the use of elastoplastic theory to analyze bearing capacity and failure states. Therefore, in-situ testing of concrete shear strength has become a crucial task.

[0003] In existing technology, in-situ testing of concrete shear strength primarily involves applying a normal load vertically to the top of the concrete surface using weights (such as iron or concrete blocks) and a shear load horizontally using a hydraulic jack. This method has shortcomings: Because weights are applied vertically, testing can only be performed on the top of the concrete surface, not on its sides (as is required for concrete linings in underground and tunnel projects), limiting its practicality. Furthermore, due to objective constraints, the load can generally only be applied to 6 MPa, resulting in limited data collection and inaccuracy.

[0004] In summary, the above detection methods have the disadvantages of being unable to be performed on the side of concrete, which affects their practicality; and limited data collection, which affects their accuracy, so design innovation is needed. Summary of the Invention

[0005] The present invention proposes a double-sided direct shear method in-situ detection device for concrete shear strength, which has strong practicality, accurate detection and reasonable design. The device can solve the problems in the prior art that it cannot be performed on the side of concrete, affecting practicality; and the collected data is limited, affecting accuracy.

[0006] The technical solution adopted by the present invention is: an in-situ detection device for concrete shear strength using a double-sided direct shear method, comprising an H-shaped column specimen located in a working pit in solid concrete, a shear loading device provided along the central axis of the H-shaped column specimen to cause the H-shaped column specimen to fail along two specified shear planes, and a normal loading device provided perpendicular to the central axis of the H-shaped column specimen, embedded in the working pit and enclosing the H-shaped column specimen. The present invention applies different levels of normal loads via the normal loading device to determine the normal stress; simultaneously, a shear loading device is used to cause the H-shaped column specimen to fail along two specified shear planes, measuring the corresponding shear loads and determining the shear stress; and based on the normal stress and shear stress under each level of load, the shear strength is determined in accordance with relevant standards.

[0007] Furthermore, the surface of the H-shaped column specimen is flush with the surface of the solid concrete; the wing plate has a side length of 150 mm in the direction perpendicular to the central axis, a side length of 50 mm in the direction parallel to the central axis, a height of 121 mm, and the bottom surface is connected to the solid concrete; the web plate has a side length of 100 mm in the direction perpendicular to the central axis, a side length of 50 mm in the direction parallel to the central axis, a height of 100 mm, and the bottom surface is parallel to the surface; an inner cavity is enclosed between the bottom surface of the web plate, the solid concrete and the wing plate.

[0008] Furthermore, the shear loading device includes a shear downward reaction steel plate, a shear upward reaction steel plate, a shear side steel plate, a shear H-shaped steel pad, and a shear hydraulic jack.

[0009] Furthermore, the shear downward reaction steel plate is a rectangular body with a length of 100 mm, a width of (48-49) mm, and a thickness of (15-20) mm. It runs through the inner cavity, and each side of the short side is evenly drilled with two fixing screw holes connected to the lower end of the shear side steel plate; the shear upward reaction steel plate has the same specifications and dimensions as the shear downward reaction steel plate, and each side of the short side is evenly drilled with two fixing screw holes connected to the upper end of the shear side steel plate; the shear side steel plate is a rectangular body with the same width as the shear downward reaction steel plate and a thickness of (10-15) mm. Two fixing circular holes are drilled at the upper and lower ends corresponding to the fixing screw holes, and the fixing bolts can pass through the fixing circular holes and screw into the fixing screw holes.

[0010] Furthermore, the shear H-shaped steel pad is located on the surface of the H-shaped column specimen, and its projection on the surface of the H-shaped column specimen coincides with the surface of the H-shaped column specimen; the side length of the wing plate in the direction perpendicular to the central axis is 150 mm, the side length in the direction parallel to the central axis is 50 mm, and the height is (25-35) mm; the side length of the web plate in the direction perpendicular to the central axis is 100 mm, the side length in the direction parallel to the central axis is 50 mm, and the height is 5 mm less than the height of the wing plate.

[0011] Furthermore, the shear hydraulic jack is located between the upper surface of the shear steel pad and the lower surface of the shear upward reaction steel plate, and its range meets the detection requirements; the shear hydraulic jack is equipped with a shear digital force gauge.

[0012] Furthermore, the normal loading device includes a normal rectangular steel pad, a normal hydraulic jack, and a normal steel reaction frame.

[0013] Furthermore, the normal rectangular steel pad is located on the side of the H-shaped column specimen perpendicular to the central axis, with a height of 120 mm, a width of 150 mm, and a thickness of (20-30) mm; the normal hydraulic jack is located on the normal steel pad, and its range meets the detection requirements; the normal hydraulic jack is equipped with a normal digital force gauge; the normal steel reaction frame is a rectangular ring body, with an inner side length of (155-170) mm in the direction perpendicular to the central axis, and the inner side length in the direction parallel to the central axis should be slightly larger than (150 + normal steel pad thickness + normal hydraulic jack original height), the ring body height is 120 mm, the ring body thickness is (20-30) mm, and the inner side of the rectangular ring body in the direction perpendicular to the central axis is in contact with the side of the H-shaped column specimen perpendicular to the central axis and the normal hydraulic jack respectively.

[0014] The beneficial effects of the present invention are as follows: (1) During the detection process, different levels of normal loads are applied through the normal loading system to obtain the normal stress; at the same time, the shear loading system is used to cause the concrete of the square column specimen to fail along the two specified shear planes, and the corresponding shear loads are measured to obtain the shear stress; based on the normal stress and shear stress under each level of load, the shear strength is obtained in accordance with relevant standards, and the invention has strong practicality, accurate detection, and reasonable design; (2) Since hydraulic jacks are used for loading in both the shear and normal directions, detection can be carried out on the side of the concrete, and the load can be arbitrarily selected within the range, and there is no problem of limited collected data affecting accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic structural elevation diagram of the present invention.

[0016] Figure 2 It is a schematic diagram of the aa cross-sectional structure of the present invention.

[0017] Figure 3 It is a schematic diagram of the bb cross-sectional structure of the present invention.

[0018] Figure 4 It is a schematic elevation view of the present invention in use.

[0019] Figure 5 It is a schematic diagram of the aa cross section of the present invention.

[0020] Figure 6 It is a schematic diagram of the use of the bb cross section of the present invention.

[0021] Figure 7 It is a schematic diagram of the groove grinding of the present invention.

[0022] Figure 8 It is a schematic diagram of the inverted inner cavity grinding of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all possible alternatives, improvements and equivalents within the scope of the claims.

[0024] Reference Figure 1-8 A device for in-situ testing of concrete shear strength using a double-sided direct shear method includes an H-shaped column specimen 18 located within a working pit 2 in solid concrete 3. A shear loading device 8 is provided along the central axis of the H-shaped column specimen 18 to cause the H-shaped column specimen 18 to fail along two specified shear planes. A normal loading device 18 is provided perpendicular to the central axis of the H-shaped column specimen 18, embedded within the working pit 2 and enclosing the H-shaped column specimen 18. The present invention applies normal loads of varying levels via the normal loading device 18 to determine normal stress. Simultaneously, the shear loading device 8 is used to cause the H-shaped column specimen 18 to fail along two specified shear planes, measuring the corresponding shear loads and determining shear stress. Based on the normal stress and shear stress under each level of load, the shear strength is determined in accordance with relevant standards.

[0025] The surface of the H-shaped column specimen 18 described in this embodiment is flush with the surface of the solid concrete 3; the side length of the wing plate in the direction perpendicular to the central axis is 150 mm, the side length in the direction parallel to the central axis is 50 mm, the height is 121 mm, and the bottom surface is connected to the solid concrete 3; the side length of the web plate in the direction perpendicular to the central axis is 100 mm, the side length in the direction parallel to the central axis is 50 mm, the height is 100 mm, and the bottom surface is parallel to the surface; an inner cavity 19 is enclosed between the bottom surface of the web plate, the solid concrete 3 and the wing plate.

[0026] The shear loading device 8 described in this embodiment includes a shear downward reaction steel plate 20 , a shear upward reaction steel plate 13 , a shear side steel plate 1 , a shear H-shaped steel pad 11 , and a shear hydraulic jack 12 .

[0027] The shear downward reaction steel plate 20 described in this embodiment is a rectangular body with a length of 100 mm, a width of 49 mm, and a thickness of 20 mm. It runs through the inner cavity 19, and each side of the short side is evenly drilled with two M14 fixing screw holes 7 connected to the lower end of the shear side steel plate 1; the shear upward reaction steel plate 13 has the same specifications and dimensions as the shear downward reaction steel plate 20, and each side of the short side is evenly drilled with two M14 fixing screw holes 7 connected to the upper end of the shear side steel plate 1; the shear side steel plate 1 is a rectangular body with a width of 49 mm and a thickness of 14 mm, and two Ф15 fixing circular holes 6 are drilled at the upper and lower ends corresponding to the fixing screw holes 7, and the fixing bolts 4 can pass through the fixing circular holes 6 and screw into the fixing screw holes 7.

[0028] The shear-direction H-shaped steel pad 11 described in this embodiment is located on the surface of the H-shaped column specimen 18, and its projection on the surface of the H-shaped column specimen 18 coincides with the surface of the H-shaped column specimen 18; the side length of the wing plate in the direction perpendicular to the central axis is 150 mm, the side length in the direction parallel to the central axis is 50 mm, and the height is 25 mm; the side length of the web plate in the direction perpendicular to the central axis is 100 mm, the side length in the direction parallel to the central axis is 50 mm, and the height is 20 mm.

[0029] The shear hydraulic jack 12 of this embodiment is located between the upper surface of the shear steel pad 11 and the lower surface of the shear upward reaction steel plate 13, and its measuring range meets the detection requirements; the shear hydraulic jack 12 is installed with a shear digital force gauge 21.

[0030] The normal loading device 15 described in this embodiment includes a normal rectangular steel backing plate 14 , a normal hydraulic jack 9 , and a normal steel reaction frame 5 .

[0031] The normal rectangular steel pad 14 described in this embodiment is located on the side of the H-shaped column specimen 18 perpendicular to the central axis, with a height of 121 mm, a width of 150 mm, and a thickness of 20 mm; the normal hydraulic jack 9 is located on the normal rectangular steel pad 14, and its measuring range meets the detection requirements; the normal hydraulic jack 9 is equipped with a normal digital force gauge 10; the normal steel reaction frame 5 is a rectangular ring body with an inner side length of 155 mm in the direction perpendicular to the central axis and an inner side length of 300 mm in the direction parallel to the central axis, a ring body height of 121 mm, and a ring body thickness of 25 mm. The inner side of the rectangular ring body in the direction perpendicular to the central axis contacts the side of the H-shaped column specimen 18 perpendicular to the central axis and the normal hydraulic jack 9 respectively.

[0032] The detection process of this embodiment is as follows: (1) Draw the boundary line, use a track-type concrete cutter to cut, and use chiseling and grinding tools to form a working pit 2 with a length × width × height = 350mm × 350mm × 121mm, and form Figure 7 、 Figure 8 As shown in the rectangular column with a length × width × height = 150mm × 150mm × 121mm, the rectangular column is divided into two from top to bottom in a direction perpendicular to the central axis, forming a vertical groove 22 with a length × width × height = 150mm × 30mm × 121mm; (2) as Figure 7 , using an angle grinder 25 with an extension rod 24 and a sintered grinding head 23, the extension rod 24 is close to the side wall of the vertical slot 22, and a slot 16 with a length × width × height = 50mm × 25mm × 121mm is ground along the central axis; (3) Figure 8, an angle grinder 25 is used in conjunction with an extension rod 24 and a sintered grinding head 23, and the extension rod 24 is pressed against the side wall of the vertical groove 22 to grind an inner cavity 19 with a length × width × height = 100mm × 30mm × 21mm along the surface direction; (4) the shear downward reaction steel plate 20 is passed through the inner cavity 19, pressed against the upper surface of the inner cavity 19, and the vertical groove 22 is filled with epoxy mortar 17; (5) after the epoxy mortar 17 is hardened, the normal loading device 15 and the shear loading device 8 are assembled; (6) different levels of normal loads are applied through the normal loading device 15 to calculate the normal stress; at the same time, the shear loading device 8 is used to make the H-shaped column specimen 18 fail along the two shear planes at the interface between the web and the flange, and the corresponding shear load is measured to calculate the shear stress; according to the normal stress and shear stress under each level of load, the shear strength is calculated in accordance with the relevant standards.

Claims

1. An in-situ detection device for concrete shear strength using a double-sided direct shear method, characterized by: It includes H-shaped column specimens located in a working pit in solid concrete; The surface of the H-shaped column specimen is flush with the surface of the solid concrete; the wing plate of the H-shaped column specimen has a side length of 150 mm in the direction perpendicular to the central axis, a side length of 50 mm in the direction parallel to the central axis, a height of 121 mm, and the bottom surface is connected to the solid concrete; the web plate of the H-shaped column specimen has a side length of 100 mm in the direction perpendicular to the central axis, a side length of 50 mm in the direction parallel to the central axis, a height of 100 mm, and the bottom surface is parallel to the surface; an inner cavity is enclosed between the bottom surface of the web plate of the H-shaped column specimen, the solid concrete, and the wing plate of the H-shaped column specimen; The central axis of the H-shaped column specimen is provided with a shear loading device that causes the H-shaped column specimen to fail along two specified shear planes; The shear loading device includes a shear H-shaped steel plate, which is located on the surface of the H-shaped column specimen, and its projection on the surface of the H-shaped column specimen coincides with the surface of the H-shaped column specimen; the flange of the shear H-shaped steel plate has a side length of 150 mm in a direction perpendicular to the central axis, a side length of 50 mm in a direction parallel to the central axis, and a height of 25 mm to 35 mm; the web of the shear H-shaped steel plate has a side length of 100 mm in a direction perpendicular to the central axis, and a side length of 50 mm in a direction parallel to the central axis, and the height of the web of the shear H-shaped steel plate is 5 mm less than the height of the flange; The shear loading device also includes a shear downward reaction steel plate, a shear upward reaction steel plate, a shear side steel plate, and a shear hydraulic jack; the shear downward reaction steel plate is a rectangular body with a length of 100mm, a width of 48mm-49mm, and a thickness of 15mm-20mm, which runs through the inner cavity, and each side of the short side is evenly drilled with 2 fixing screw holes connected to the lower end of the shear side steel plate; the shear upward reaction steel plate has the same specifications and dimensions as the shear downward reaction steel plate, and each side of the short side is evenly drilled with 2 fixing screw holes connected to the upper end of the shear side steel plate; the shear side steel plate is a rectangular body with the same width as the shear downward reaction steel plate and a thickness of 10mm-15mm, and two fixing circular holes are drilled at the upper and lower ends corresponding to the fixing screw holes, and the fixing bolts can pass through the fixing circular holes and screw into the fixing screw holes; the shear hydraulic jack is located between the upper surface of the shear steel pad and the lower surface of the shear upward reaction steel plate, and its measuring range meets the detection requirements; the shear hydraulic jack is equipped with a shear digital force gauge; The H-shaped column specimen is provided with a normal loading device in a direction perpendicular to the central axis, which is embedded in the working pit and surrounds the H-shaped column specimen.

2. The in-situ detection device for concrete shear strength using a double-sided direct shear method according to claim 1, characterized in that: The normal loading device comprises a normal rectangular steel pad, a normal hydraulic jack and a normal steel reaction frame.

3. The in-situ detection device for concrete shear strength using a double-sided direct shear method according to claim 2, characterized in that: The normal rectangular steel pad is located on the side of the H-shaped column specimen perpendicular to the central axis, with a height of 120mm, a width of 150mm, and a thickness of 20mm-30mm; the normal hydraulic jack is located on the normal steel pad, and its range meets the detection requirements; the normal hydraulic jack is equipped with a normal digital force gauge; the normal steel reaction frame is a rectangular ring body, with an inner side length of 155mm-170mm in the direction perpendicular to the central axis, and the inner side length in the direction parallel to the central axis should be slightly larger than 150mm + the thickness of the normal steel pad + the original height of the normal hydraulic jack, the ring body height is 120mm, the ring body thickness is 20mm-30mm, and the inner side of the rectangular ring body in the direction perpendicular to the central axis contacts the side of the H-shaped column specimen perpendicular to the central axis and the normal hydraulic jack respectively.

4. A detection method using the in-situ detection device for concrete shear strength using a double-sided direct shear method according to claim 1, characterized in that: The inspection steps include the following: (1) Draw the boundary line, cut with a track-type concrete cutter, and use chiseling and grinding tools to form a working pit with a length × width × height = 350mm × 350mm × 121mm, and at the same time form a rectangular column with a length × width × height = 150mm × 150mm × 121mm. The rectangular column is divided into two from top to bottom in the direction perpendicular to the central axis, forming a vertical groove with a length × width × height = 150mm × 30mm × 121mm; (2) Use an angle grinder with an extension rod and a sintered grinding head, with the extension rod close to the side wall of the vertical groove, and grind a slot with a length × width × height = 50mm × 25mm × 121mm along the central axis; (3) Use an angle grinder to grind a slot with a length × width × height = 50mm × 25mm × 121mm. With the extension rod and sintered grinding head, the extension rod is pressed against the side wall of the vertical groove, and an inner cavity with a length × width × height = 100mm × 30mm × 21mm is ground along the surface direction; (4) the shear downward reaction steel plate is passed through the inner cavity, pressed against the upper surface of the inner cavity, and the vertical groove is filled with epoxy mortar; (5) after the epoxy mortar hardens, the normal loading device and the shear loading device are assembled; (6) different levels of normal loads are applied through the normal loading device to calculate the normal stress; at the same time, the shear loading device is used to make the H-shaped column specimen fail along the two shear planes at the interface between the web and the flange, and the corresponding shear load is measured to calculate the shear stress; according to the normal stress and shear stress under each level of load, the shear strength is calculated in accordance with the relevant standards.

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