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CN-117054256-B - Single shear apparatus with uniformly distributed shear strain and shearing method

CN117054256BCN 117054256 BCN117054256 BCN 117054256BCN-117054256-B

Abstract

The invention provides a single shear apparatus with uniformly distributed shear strain and a shearing method, wherein the shearing method comprises the steps of installing a shearing assembly, installing a lamination stack of the shearing assembly with a sample, installing a vertical loading device and a shearing loading device, applying vertical load to the sample to consolidate the sample, installing a left sliding limiting device and applying horizontal load to the consolidated sample to shear.

Inventors

  • ZHU JUNGAO
  • ZHU CAIFENG
  • GAO FENG
  • CHEN GE
  • XIA YONG
  • LUO QIXUN
  • SHEN ZHIWEN
  • WANG TAO
  • JIANG BINGNAN
  • PENG WENMING
  • LI JIAN

Assignees

  • 河海大学
  • 中国电建集团成都勘测设计研究院有限公司

Dates

Publication Date
20260505
Application Date
20230727

Claims (7)

  1. 1. A shearing method for uniformly distributing shearing strain, comprising the steps of: step 1, installing a shearing assembly (20) and loading a sample into a lamination stack (24) of the shearing assembly (20); wherein, shearing subassembly (20) include dolly (22), lamination spacing frame (23) and lamination group (24), specifically include the following step: step 1A, assembling a stack (24) of laminations for providing shear space for the consolidated sample, comprising n laminations (241) stacked in the Z-direction, comprising in particular the steps of: Step 1A1, sequentially stacking n laminated sheets (241) along the Z direction; Step 1A2, inserting the same pin (242) into the corresponding waist holes in each laminated sheet (241) and the adjacent laminated sheets (241), and forming a shearing deformation space between the pin (242) and each laminated sheet (241); Wherein, each lamination sheet (241) is provided with a plurality of waist holes arranged along the Y direction; Step 1A3, putting a connecting rod for rotating the pins (242) into the through holes on the uppermost lamination sheet (241) along the Y direction, and enabling the connecting rod to sequentially pass through each pin (242) along the Y direction; step 1B, fixing a foundation slab (231) of a lamination limiting frame (23) on a trolley (22), and installing the lamination limiting frame (23) around a lamination group (24), wherein the method specifically comprises the following steps: step 1B1, fixing the lowermost lamination sheet (241) close to the trolley (22) to the foundation slab (231) so that the lowermost lamination sheet (241) can move along the X direction along with the trolley (22); Step 1B2, before consolidation in step 3, the uppermost lamination sheet (241) is detachably fixed on the top surface of a lamination limiting frame (23) by a limiting screw so as to prevent a lamination group (24) from moving along the Z direction in the process of consolidating samples in step 3, wherein the lamination limiting frame (23) is of a detachable structure, firstly is used in the sample preparation process in step 1C, prevents the lamination group (24) from sliding and reduces soil sample disturbance, secondly is used in the sample consolidation process in step 3, provides a limiting space for samples and prevents the samples from being extruded between the lamination sheets, and before shearing in step 4, a limiting member positioned in the X direction is detached from a base bottom plate (231); step 1C, placing a sample, namely placing the sample into a sample preparation cavity surrounded by a lamination stack (24); Step 2, installing a vertical loading device (31) and a shear loading device (33), wherein the vertical loading device (31) comprises a pressurizing cover plate (311), a vertical load loading lever (312) and a loading rod (313), and the shear loading device (33) comprises a roller group and a steel wire rope; The method specifically comprises the following steps: Step 2A, installing a vertical loading device (31), namely fixing the upper end of a vertical load loading lever (312) along the Z direction to a lever structure, hinging the lever structure to a support frame, arranging a sphere connecting piece at the lower end of the lever structure along the Z direction, putting the sphere connecting piece into a semicircular groove at the upper end of a loading rod (313) along the Z direction, and finally connecting the lower end of the loading rod (313) to a pressurizing cover plate (311) in a threaded manner, and enabling the pressurizing cover plate (311) to be matched with a sample preparation cavity enclosed by the uppermost lamination sheet (241); step 2B, installing a shear loading device (33), which specifically comprises the following steps: step 2B1, fixing a mounting seat provided with a roller group; step 2B2, a steel wire rope bypasses a roller group and passes through a concave block (321) to be connected with a trolley; and 3, applying a vertical load to the sample to consolidate the sample, wherein the method specifically comprises the following steps of: the vertical load loading lever (312) is inclined towards one side of the sample through weight configuration at two ends of the vertical load loading lever (312), so that vertical load is applied to the sample through the pressurizing cover plate (311), water in the sample is discharged to compress the sample, and finally the consolidated sample is obtained; the pressure cover plate (311) is compacted on the upper surface of the sample after consolidation, and meanwhile, the lower end surface of the pressure cover plate (311) along the Z direction is positioned in the uppermost lamination sheet (241) so as to prevent the pressure cover plate (311) from limiting the pin (242) to rotate around the connecting rod in the shearing process of the step 4; Step 4, installing a left sliding limiting device (32), which comprises a concave block (321) and a push rod top support (322), and specifically comprises the following steps: the pressing cover plate (311) is connected with the ejector rod propping support (322) in a sliding way in the Z direction so as to prevent the uppermost lamination sheet (241) from moving along the X direction along with the trolley (22) during shearing, and simultaneously, the friction force of the ejector rod propping support (322) on the pressing cover plate (311) and the bending moment generated by the loading rod (313) are eliminated; And 5, applying horizontal load to the solidified sample to shear, wherein the method specifically comprises the following steps of: Step 5A, keeping the vertical consolidation pressure unchanged, so that a part of the consolidation sample contacted with the vertical consolidation pressure is kept still under the action of the pressure exerted by the pressurizing cover plate (311); Step 5B, removing a limiting member of the lamination limiting frame (23) positioned in the X direction, and separating the uppermost lamination sheet (241) from the lamination limiting frame (23); And 5C, pulling the steel wire rope to enable the lowermost lamination sheet (241) connected with the trolley (22) to be subjected to the tensile force transmitted by the shear loading device (33), wherein the top of the pin (242) is limited on the uppermost lamination sheet (241) due to the rigidity of the pin (242), the bottom of the pin (242) is positioned on the lowermost lamination sheet (241), and the lowermost lamination sheet (241) is pulled, so that the pin (242) is inclined to enable the rest lamination sheets (241) to uniformly displace.
  2. 2. The shearing method of uniform distribution of shear strain according to claim 1, wherein when the shear loading device (33) is not in use, step 5 further comprises a step of shearing based on a horizontal loading device (34), the horizontal loading device (34) comprising a linear motor (341) and a force sensor (342), in particular comprising the steps of: Firstly, fixing a base of a linear motor (341), connecting a shell of a force sensor (342) with an output end of the linear motor (341), and enabling an induction end of the force sensor (342) to face a trolley (22); Starting the linear motor (341), and when the sensing end of the force sensor (342) contacts the trolley (22), starting the linear motor (341) to be closed so as to realize zero setting of the force sensor (342); then, the linear motor (341) is started again, and the lowest lamination sheet (241) connected with the trolley (22) receives the thrust transmitted by the horizontal loading device (34); Since the pins (242) are rigid, the tops of the pins (242) are limited to the uppermost lamination sheet (241), the bottoms of the pins (242) are positioned on the lowermost lamination sheet (241), and the lowermost lamination sheet (241) is pushed, the pins (242) incline to uniformly displace the rest lamination sheets (241).
  3. 3. The shearing method for uniform distribution of shear strain according to claim 1, wherein the lamination stop frame (23) further comprises two fixing plates (232) and two guide plates (233): the two guide plates (233) are oppositely arranged and distributed in the Y direction and fixed on the foundation slab (231), so that the Y direction of the lamination stack (24) can be limited; the top of each guide plate (233) is provided with a limit flange (234), and the limit flanges (234) extend towards the sample preparation cavity and are positioned at the upper part of the uppermost lamination sheet (241), and the limit flanges (234) and the uppermost lamination sheet (241) are detachably connected through limit screws (235); the two fixing plates (232) are oppositely arranged and distributed in the X direction and fixed on the foundation base plate (231), and can limit the X direction of the lamination stack (24).
  4. 4. A method of shearing as defined in claim 3 wherein the stop flange (234) is spaced from the uppermost laminate (241) in the Z-direction to prevent friction of the stack (24) by the guide plate (233) during shearing.
  5. 5. A shearing method for uniform distribution of shear strain as in claim 3, wherein the lamination stack (24) and each guide plate (233) have a spacing of 0.05mm to 0.1mm which prevents the guide plates (233) from rubbing sideways against the lamination stack (24) during shearing.
  6. 6. The shearing method of uniform distribution of shear strain as in claim 1, wherein each lamination (241) has a back-shaped configuration such that the tendency to topple and turn after shear deformation is less than that of a square or cylindrical specimen.
  7. 7. A single shear apparatus with uniform distribution of shear strain, based on the shearing method with uniform distribution of shear strain according to any one of claims 1-6, characterized in that the single shear apparatus comprises the shearing assembly (20), a vertical loading device (31), a shear loading device (33) and a left sliding limiting device (32).

Description

Single shear apparatus with uniformly distributed shear strain and shearing method Technical Field The invention relates to a single shear apparatus with uniformly distributed shear strain and a shearing method, belongs to the field of geotechnical engineering geotechnical test, and is suitable for measuring mechanical characteristics such as stress strain and strength of fine soil. Background The accurate grasp of the mechanical properties of the soil body has important significance for the safe operation of engineering. At present, the test instruments adopted by students at home and abroad to study the mechanical properties of soil mainly comprise a direct shear instrument, a single shear instrument and a triaxial apparatus, and the single shear instrument has the advantages of constant shearing area, unfixed shearing damage surface, capability of better simulating on-site working conditions and the like in the shearing process, and is more suitable for studying the mechanical properties of soil. Chinese patent (publication No. 102269676A) discloses a high-precision geotechnical single shear device and a use method thereof, wherein the single shear device is provided with a plurality of horizontal displacement sensors which are connected with a lower shear box and an upper shear stack ring group, and can measure the displacement of each stack ring. Disclosure of Invention The invention aims to provide a single shear instrument and a shearing method for uniformly distributing shearing strain, which can accurately control the shearing direction, solve the problem of deflection of the shearing force direction in the prior art, enable a sample to realize uniform shearing and ensure uniform distribution of vertical shearing strain. A shearing method for uniformly distributing shearing strain, comprising the following steps: step 1, mounting a shear assembly 20 and loading a sample into a lamination stack 24 of the shear assembly 20; Wherein, shearing subassembly 20 includes dolly 22, lamination limiting frame 23 and lamination group 24, specifically includes the following step: Step 1A, assembling a stack 24 of laminations for providing shear space for the consolidated sample, comprising n laminations 241 stacked in the Z-direction, comprising the steps of: step 1A1, stacking n laminated sheets 241 in sequence along the Z direction; Step 1A2, inserting the same pin 242 into corresponding waist holes in each laminated sheet 241 and adjacent laminated sheets 241, wherein a shearing deformation space is formed between the pin 242 and each laminated sheet 241; Wherein, each laminated sheet 241 is provided with a plurality of waist holes arranged along the Y direction; step 1A3, placing a connecting rod for rotating the pins 242 in the through holes on the uppermost lamination sheet 241 along the Y direction, and enabling the connecting rod to sequentially pass through each pin 242 along the Y direction; step 1B, fixing the foundation plate 231 of the lamination limiting frame 23 to the trolley 22, and installing the lamination limiting frame 23 around the lamination group 24, specifically including the following steps: Step 1B1, fixing the lowermost lamination sheet 241 adjacent to the cart 22 to the base plate 231 such that the lowermost lamination sheet 241 can move in the X direction along with the cart 22; Step 1B2, before consolidation in step 3, the uppermost lamination sheet 241 is detachably fixed on the top surface of the lamination limiting frame 23 by a limiting screw so as to prevent the lamination group 24 from moving along the Z direction in the process of consolidating samples in step 3, wherein the lamination limiting frame 23 is of a detachable structure, firstly is used in the sample preparation process in step 1C to prevent the lamination group 24 from sliding and reduce soil sample disturbance, secondly is used in the process of consolidating samples in step 3 to provide a limiting space for the samples so as to prevent the samples from being extruded between the lamination sheets; step 1C, placing a sample in a sample preparation cavity surrounded by the lamination stack 24; Step 2, installing a vertical loading device 31 and a shear loading device 33, wherein the vertical loading device 31 comprises a pressurizing cover plate 311, a vertical load loading lever 312 and a loading rod 313, and the shear loading device 33 comprises a roller group and a steel wire rope; The method specifically comprises the following steps: Step 2A, installing a vertical loading device 31, namely fixing the upper end of a vertical load loading lever 312 along the Z direction to a lever structure, hinging the lever structure to a support frame, arranging a sphere connecting piece at the lower end of the lever structure along the Z direction, and placing the sphere connecting piece into a semicircular groove at the upper end of a loading rod 313 along the Z direction; Step 2B, installing a shear loading device 33,