Direct shear apparatus for geotechnical testing and method of testing

Abstract

This invention discloses a direct shear device and method for geotechnical testing. The direct shear device for geotechnical testing includes: a lower shear box with a groove on its top corresponding to the soil sample; an upper shear box placed on top of the lower shear box, with a first through hole on the upper shear box corresponding to the soil sample and engaging with the groove, the first through hole and the groove forming a top opening for accommodating the soil sample; and a limiting structure disposed between the lower and upper shear boxes, the limiting structure only restricting the upward movement of the upper shear box relative to the lower shear box and capable of releasing the restriction on the upper shear box. The above-mentioned direct shear device for geotechnical testing can selectively restrict the upward movement of the upper shear box relative to the lower shear box, thereby enabling selective direct shear tests with or without a fixed shear surface, which is beneficial for increasing the experimental data obtained during the direct shear test.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geotechnical test, in particular to a direct shear device for geotechnical test and a test method. BACKGROUND

[0002] In the existing geotechnical test, the direct shear test is usually used to test the shear strength of soil, wherein the direct shear test usually needs to use a direct shear apparatus. At present, the direct shear apparatus used in the direct shear test is generally composed of a horizontal loading system, a vertical loading system, an upper shear box, a lower shear box, a horizontal displacement monitoring device and a vertical displacement monitoring device. Due to the advantages of simple structure, easy operation, clear force transmission and large instrument rigidity, the direct shear apparatus is widely used in the test of shear strength of rock and soil materials at home and abroad.

[0003] However, the direct shear apparatus used in the direct shear test at home and abroad is generally a small direct shear apparatus for fine-grained soil or sand, and the sample is usually a cylindrical sample with a diameter of 61.8 mm and a height of 20 mm. It cannot be used for road materials or coarse-grained fillers, so a large direct shear apparatus is needed. The existing large direct shear apparatus is an enlarged version of the traditional small direct shear apparatus, and there is no big difference in the original function. In the test process, the test data obtained is still less, and only the strength of the test material and the displacement change of the shear box during the shearing process can be obtained. Specifically, a temperature control large direct shear apparatus can meet the test requirements of coarse-grained fillers and can perform direct shear test on soil samples under high temperature or negative temperature conditions. However, the upper shear box of the temperature control large direct shear apparatus is directly placed on the top of the lower shear box. During the process of driving the lower shear box to move relative to the upper shear box in the horizontal direction to shear the soil sample, the soil sample will generate an upward force acting on the upper shear box, so that the upper shear box will have a tendency to move upward. Although this can more accurately reflect the real mechanical state, it is not suitable for all working conditions. In actual direct shear test, some working conditions need to limit the upward movement of the upper shear box relative to the lower shear box, so as to realize the fixation of the shear surface to study the shear characteristics at the specific shear surface. At the same time, the temperature control large direct shear apparatus can only be used to study the shear characteristics at the shear surface with fixed height. In addition, when the temperature control large direct shear apparatus performs direct shear test on soil samples under negative temperature conditions, the interface between the upper shear box and the lower shear box is easy to freeze, which will affect the accuracy of the test results. SUMMARY

[0004] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application provides a direct shear device for geotechnical test, which can selectively limit the upward movement of the upper shear box relative to the lower shear box, so as to selectively perform direct shear test with fixed shear surface or direct shear test without fixed shear surface.

[0005] The application further provides a test method applied to the direct shearing device for geotechnical test.

[0006] The direct shearing device for geotechnical test according to the first aspect of the application comprises a lower shearing box, a top of the lower shearing box is provided with a groove corresponding to a soil sample; an upper shearing box is placed on the top of the lower shearing box, the upper shearing box is provided with a first through hole corresponding to the soil sample and butting against the groove, the first through hole and the groove cooperate to form a top opening and a containing cavity for containing the soil sample; a limiting structure is arranged between the lower shearing box and the upper shearing box, the limiting structure is only used to limit the upward movement of the upper shearing box relative to the lower shearing box and can release the limitation of the upper shearing box.

[0007] The direct shearing device for geotechnical test according to the application has at least the following beneficial effects: when the shearing surface needs to be fixed, the direct shearing test is performed after the limiting structure limits the upward movement of the lower shearing box relative to the lower shearing box; when the shearing surface does not need to be fixed, the direct shearing test is performed after the limiting structure releases the limitation of the lower shearing box, that is, the direct shearing device for geotechnical test can selectively limit the upward movement of the upper shearing box relative to the lower shearing box, thereby enabling the direct shearing test with fixed shearing surface or the direct shearing test without fixed shearing surface, and further facilitating the increase of the test data obtained in the direct shearing test.

[0008] According to some embodiments of the application, the limiting structure comprises a connecting piece and a limiting piece, a lower part of the connecting piece is detachably connected to a side wall of the lower shearing box, the limiting piece is arranged on an upper part of the connecting piece, the side wall of the upper shearing box is provided with a limiting sliding groove arranged horizontally along the shearing direction of the soil sample corresponding to the limiting piece, and an end of the limiting piece away from the connecting piece is inserted into the limiting sliding groove, so that the limiting piece can move back and forth relative to the upper shearing box along the shearing direction of the soil sample with the lower shearing box and can limit the upward movement of the upper shearing box relative to the lower shearing box.

[0009] According to some embodiments of the application, the height adjusting structure for adjusting the height of the shearing surface is further included.

[0010] According to some embodiments of the present invention, the height adjustment structure includes a pad block for being sandwiched between the upper shear box and the lower shear box. The pad block is provided with a second through hole corresponding to the soil sample, which can respectively mate with the first through hole and the groove. The connector is provided with a plurality of insertion holes spaced apart along the vertical direction. The side wall of the lower shear box is fixedly provided with a first connecting part that can be inserted and engaged with the insertion holes. The side wall of the pad block is fixedly provided with a second connecting part that can be inserted and engaged with the insertion holes, so that the pad block can move synchronously with the lower shear box along the shearing direction of the soil sample.

[0011] According to some embodiments of the present invention, the sidewall of the upper shear box is provided with a plurality of limiting grooves at intervals along the vertical direction.

[0012] According to some embodiments of the present invention, the lower part of the upper shear box is provided with a transparent window for observing the shearing process of the soil sample.

[0013] According to some embodiments of the present invention, the bottom of the upper shear box is provided with an anti-icing coating.

[0014] According to some embodiments of the present invention, the rear sidewall of the lower shear box is provided with a first horizontal extension, and the end of the first horizontal extension away from the lower shear box is provided with a blocking part for preventing the upper shear box from falling.

[0015] According to some embodiments of the present invention, the front sidewall of the upper shear box is provided with a second horizontal extension, and the end of the second horizontal extension away from the upper shear box is provided with an abutment for limiting.

[0016] A test method according to a second aspect of the present invention, applied to a direct shear apparatus for geotechnical testing according to the first aspect of the present invention, includes the following steps:

[0017] When it is necessary to fix the shearing surface, the upper shearing box is restricted from moving upward relative to the lower shearing box by a limiting structure before a direct shearing test is performed.

[0018] When it is not necessary to fix the shearing surface, the direct shearing test can be carried out after the restriction structure on the upper shear box is removed.

[0019] When it is necessary to adjust the height of the shear plane, the height of the shear plane is adjusted by the height adjustment structure before a direct shear test is performed.

[0020] The test method according to the embodiments of the present invention has at least the following beneficial effects: it can adapt to different test requirements, thereby increasing the test data that can be obtained in the process of direct shear test, and thus facilitating a more comprehensive study of the shear process of soil.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0023] Figure 1 This is a schematic diagram of the direct shearing device for geotechnical testing when no pad is placed between the upper and lower shear boxes according to an embodiment of the present invention.

[0024] Figure 2 yes Figure 1 An exploded view of the upper and lower shear boxes in the structure shown.

[0025] Figure 3 This is a schematic diagram of the direct shearing device for geotechnical testing when a pad is sandwiched between the upper and lower shear boxes according to an embodiment of the present invention.

[0026] Figure 4 yes Figure 3 An exploded view of the upper shear box, the pad block, and the lower shear box in the structure shown.

[0027] Figure 5 This is a schematic diagram of the direct shearing device for geotechnical testing when two pads are sandwiched between the upper and lower shear boxes according to an embodiment of the present invention.

[0028] Figure label:

[0029] The components include: a lower shear box 100, a groove 110, a first connecting part 120, a first horizontal extension part 130, a blocking part 131, an upper shear box 200, a first through hole 210, a limiting slide groove 220, a second horizontal extension part 230, an abutting part 231, a connector 300, a plug hole 310, a limiting member 400, a pad 500, a second through hole 510, and a second connecting part 520. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0031] In the description of this invention, it should be understood that if directional descriptions are involved, such as up, down, front, back, left, right, etc., indicating the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings, it is only for the convenience of describing this invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0032] In the description of this invention, if words such as several, greater than, less than, exceeding, above, below, or within appear, then several means one or more, multiple means two or more, greater than, less than, exceeding, etc. are understood to exclude the number itself, and above, below, or within are understood to include the number itself.

[0033] In the description of this invention, the use of terms such as "first" and "second" is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0034] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0035] Reference Figure 1 and Figure 2 According to an embodiment of the present invention, a direct shearing device for geotechnical testing includes a lower shear box 100, an upper shear box 200, and a limiting structure.

[0036] The lower shear box 100 has a groove 110 on its top corresponding to the soil sample. The upper shear box 200 is placed on top of the lower shear box 100. The upper shear box 200 has a first through hole 210 on its top corresponding to the soil sample, which is connected to the groove 110. The first through hole 210 and the groove 110 cooperate to form a top opening and a receiving cavity for accommodating the soil sample. A limiting structure is provided between the lower shear box 100 and the upper shear box 200. The limiting structure is only used to restrict the upper shear box 200 from moving upward relative to the lower shear box 100 and can release the restriction on the upper shear box 200.

[0037] When it is necessary to fix the shear surface, the upper shear box 200 is restricted from moving upward relative to the lower shear box 100 by the limiting structure before a direct shear test is performed. When it is not necessary to fix the shear surface, the limiting structure is released from the lower shear box 100 before a direct shear test is performed. That is, the above-mentioned direct shear device for geotechnical testing can selectively restrict the upper shear box 200 from moving upward relative to the lower shear box 100, thereby enabling the selective performance of direct shear tests with or without a fixed shear surface, which is beneficial for increasing the test data obtained during the direct shear test.

[0038] Reference Figure 1 and Figure 2 In some embodiments, the limiting structure includes a connector 300 and a limiting member 400. The lower part of the connector 300 is detachably connected to the side wall of the lower shear box 100. The limiting member 400 is disposed on the upper part of the connector 300. The side wall of the upper shear box 200 is provided with a limiting groove 220 arranged horizontally along the shear direction of the soil sample corresponding to the limiting member 400. The end of the limiting member 400 away from the connector 300 is inserted into the limiting groove 220 so that the limiting member 400 can move back and forth relative to the upper shear box 200 along the shear direction of the soil sample with the lower shear box 100 and can restrict the upper shear box 200 from moving upward relative to the lower shear box 100.

[0039] It should be noted that in some embodiments, a height adjustment structure is also included for adjusting the height of the shear plane, which can adjust the height of the shear plane to study the shear characteristics at different heights of the shear plane.

[0040] Reference Figures 3 to 5 In some embodiments, the height adjustment structure includes a pad 500, which is sandwiched between the upper shear box 200 and the lower shear box 100. The pad 500 is provided with a second through hole 510 corresponding to the soil sample, which can respectively mate with the first through hole 210 and the groove 110. The connector 300 is provided with a plurality of insertion holes 310 spaced apart in the vertical direction. The side wall of the lower shear box 100 is fixedly provided with a first connecting part 120 that can be inserted and engaged with the insertion hole 310. The side wall of the pad 500 is fixedly provided with a second connecting part 520 that can be inserted and engaged with the insertion hole 310, so that the pad 500 can move synchronously with the lower shear box 100 along the shearing direction of the soil sample. When the height of the shearing surface needs to be adjusted, the required number of pads 500 can be placed between the upper shearing box 200 and the lower shearing box 100. The first connecting part 120 can be inserted into different insertion holes 310 to make the limiting structure adapt to shearing surfaces of different heights. Its structure is simple and easy to implement.

[0041] Reference Figures 3 to 5In some embodiments, the sidewall of the upper shear box 200 is provided with multiple limiting grooves 220 at intervals along the vertical direction. When the height of the shearing surface is adjusted and the upper shear box 200 is not higher than the connecting member 300, the limiting member 400 can be inserted into different limiting grooves 220 accordingly, so that the limiting structure can adapt to shearing surfaces of different heights, which helps to simplify the operation steps of the direct shearing test.

[0042] It should be noted that in some other embodiments, the limiting structure can also be a U-shaped pin. One end of the U-shaped pin is movably inserted into the upper shear box along the shear direction of the soil sample, and the other end of the U-shaped pin is movably inserted into the lower shear box along the shear direction of the soil sample. The side wall of the upper shear box is provided with multiple pin holes for inserting the U-shaped pin at intervals along the vertical direction, so that the limiting structure can adapt to shear surfaces of different heights. This is not limited here.

[0043] It should be noted that, in some other embodiments, the height adjustment structure may also be a cylinder sandwiched between the upper shear box and the lower shear box and capable of moving synchronously with the lower shear box along the shearing direction of the soil sample. Specifically, the upper end of the cylinder is an opening structure that can connect with the first through hole, and the lower end of the cylinder is an opening structure that can connect with the groove. This is not limited here.

[0044] It should be noted that in some embodiments, the lower part of the upper shear box 200 is provided with a transparent window (not shown in the figure) for observing the shearing process of the soil sample, so that the tester can directly observe the shearing process of the soil sample. Specifically, the transparent window is made of tempered glass. Of course, the transparent window can also be made of epoxy resin or other transparent materials. In addition, the upper part of the lower shear box 100 and the pad 500 can also be provided with transparent windows to facilitate better observation of the shearing process of the soil sample. This is not limited here.

[0045] It should be noted that in some embodiments, the bottom of the upper shear box 200 is provided with an anti-icing coating (not shown in the figure). When the soil sample is subjected to a direct shear test under negative temperature conditions, it helps to prevent ice formation at the interface between the upper shear box 200 and the lower shear box 100, as well as at the interface between the upper shear box 200 and the pad 500, thereby improving the accuracy of the test results. Specifically, the anti-icing coating is made of anti-icing paint, which is an existing product. Its main components and working principle are existing technologies and will not be described in detail here.

[0046] Reference Figures 1 to 5In some embodiments, the rear sidewall of the lower shear box 100 is provided with a first horizontal extension 130. The end of the first horizontal extension 130 away from the lower shear box 100 is provided with a blocking part 131 for preventing the upper shear box 200 from falling. When the height of the shearing surface does not need to be adjusted, that is, when no pad 500 is sandwiched between the upper shear box 200 and the lower shear box 100, the blocking part 131 can block the upper shear box 200, thereby limiting the maximum distance that the lower shear box 100 can move forward relative to the upper shear box 200 along the shearing direction of the soil sample. This helps to prevent the upper shear box 200 from falling off the lower shear box 100 during the direct shear test. Of course, the height of the blocking part 131 can also be increased so that the blocking part 131 can also prevent the upper shear box 200 from falling even when a pad 500 is sandwiched between the upper shear box 200 and the lower shear box 100.

[0047] Reference Figures 1 to 5 In some embodiments, the front sidewall of the upper shear box 200 is provided with a second horizontal extension 230, and the end of the second horizontal extension 230 away from the upper shear box 200 is provided with an abutment portion 231 for limiting. During the direct shear test, the abutment portion 231 is driven to abut against the vertical surface that can limit the movement, and then the lower shear box 100 is directly driven to move forward relative to the upper shear box 200 along the shear direction of the soil sample to shear the soil sample. There is no need to use a complex limiting device to restrict the horizontal movement of the upper shear box 200, which helps to simplify the operation steps of the direct shear test.

[0048] According to an embodiment of the present invention, the test method applied to the above-mentioned direct shear device for geotechnical testing includes the following steps: when it is necessary to fix the shear surface, the upper shear box 200 is restricted from moving upward relative to the lower shear box 100 by a limiting structure before a direct shear test is performed; when it is not necessary to fix the shear surface, the limiting structure is released from the restriction on the upper shear box 200 before a direct shear test is performed; when it is necessary to adjust the height of the shear surface, the height of the shear surface is adjusted by a height adjustment structure before a direct shear test is performed.

[0049] The above-mentioned test methods can adapt to different test requirements, which helps to increase the test data obtained in the process of direct shear test, and thus facilitates a more comprehensive study of the shear process of soil.

[0050] In the description of this specification, the use of terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," and "some examples" indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0051] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A direct shear device for geotechnical testing, characterized in that, include: The lower shear box (100) has a groove (110) on its top corresponding to the soil sample. An upper shear box (200) is placed on top of the lower shear box (100). The upper shear box (200) is provided with a first through hole (210) corresponding to the soil sample, which is connected to the groove (110). The first through hole (210) and the groove (110) cooperate to form a top opening and a receiving cavity for accommodating the soil sample. A limiting structure is provided between the lower shear box (100) and the upper shear box (200). The limiting structure is only used to restrict the upper shear box (200) from moving upward relative to the lower shear box (100) and can release the restriction on the upper shear box (200). The limiting structure includes a connector (300) and a limiting member (400). The lower part of the connector (300) is detachably connected to the side wall of the lower shear box (100). The limiting member (400) is disposed on the upper part of the connector (300). The side wall of the upper shear box (200) is provided with a limiting groove (220) arranged horizontally along the shear direction of the soil sample corresponding to the limiting member (400). One end of the limiting member (400) away from the connector (300) is inserted into the limiting groove (220) so that the limiting member (400) can move back and forth relative to the upper shear box (200) along the shear direction of the soil sample with the lower shear box (100) and can restrict the upper shear box (200) from moving upward relative to the lower shear box (100). It also includes a height adjustment structure for adjusting the height of the shear plane; The height adjustment structure includes a pad (500) for clamping between the upper shear box (200) and the lower shear box (100). The pad (500) is provided with a second through hole (510) corresponding to the soil sample, which can respectively connect with the first through hole (210) and the groove (110). The connector (300) is provided with a plurality of insertion holes (310) spaced apart in the vertical direction. The side wall of the lower shear box (100) is fixedly provided with a first connecting part (120) that can be inserted and cooperated with the insertion hole (310). The side wall of the pad (500) is fixedly provided with a second connecting part (520) that can be inserted and cooperated with the insertion hole (310), so that the pad (500) can move synchronously with the lower shear box (100) along the shearing direction of the soil sample. The sidewall of the upper shear box (200) is provided with a plurality of limiting grooves (220) at intervals along the vertical direction.

2. The direct shear device for geotechnical testing as described in claim 1, characterized in that, The lower part of the upper shear box (200) is provided with a transparent window for observing the shearing process of the soil sample.

3. The direct shear device for geotechnical testing as described in claim 1, characterized in that, The bottom of the upper shear box (200) is provided with an anti-icing coating.

4. The direct shear device for geotechnical testing as described in claim 1, characterized in that, The rear side wall of the lower shear box (100) is provided with a first horizontal extension (130), and the end of the first horizontal extension (130) away from the lower shear box (100) is provided with a blocking part (131) for preventing the upper shear box (200) from falling.

5. The direct shear device for geotechnical testing as described in claim 1, characterized in that, The front sidewall of the upper shear box (200) is provided with a second horizontal extension (230), and the end of the second horizontal extension (230) away from the upper shear box (200) is provided with an abutment (231) for limiting.

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