Rock-soil in-situ direct shear apparatus
By designing a geotechnical in-situ direct shearing instrument suitable for in-situ inspection on construction sites, the problems of large disturbances in the test sample, low test accuracy and low automation in the existing technology are solved, and in-situ shear strength detection with high accuracy and automation are achieved, which is in-situ shear strength detection, which is in line with national standards.
Patent Information
- Application Number
- CN202422139188.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-02
- Publication Date
- 2025-06-17
- Estimated Expiration
- 2034-09-02
AI Technical Summary
The existing direct shear instruments cannot conduct in-situ direct shear tests on rock/soil samples at the construction site, resulting in large disturbances of the sample, changes in water content, low test accuracy, and small sample area that does not meet the specification requirements, and low degree of automation.
A geotechnical in-situ direct shear instrument is designed, and a base frame with a door-shaped three-dimensional frame structure is equipped with a normal pressure device and a shear device. The sample is detected in-situ through the normal angle adjustment mechanism and the rotary locking mechanism. The universal adjustment foot and displacement sensor are used to improve the stability and automation of the instrument.
In-situ shear strength detection is achieved in complex sites such as flat ground and slope, reducing disturbances and changes in water content of the sample, improving the accuracy and automation of the test results, complying with national standards, and facilitating observation of the deformation of the test pieces.
Smart Images
Figure CN222994209U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a direct shear apparatus, in particular to an in-situ direct shear apparatus for rock and soil. Background Art
[0002] The stability of a rock / soil layer mainly depends on the shear strength of the rock / soil itself. When the shear stress in the rock / soil mass exceeds its shear strength, the rock / soil mass will slide along any slip surface on its surface or inside, causing the whole rock / soil mass to fall apart, and thus extremely likely to cause natural disasters such as slope landslides.
[0003] The direct shear test apparatus, also known as the direct shear apparatus, is an instrument used to conduct direct shear tests on rock / soil specimens. The direct shear test is a method of directly measuring the shear strength of rock / soil specimens on a fixed shear plane by using a direct shear apparatus to apply different vertical pressures to several identical specimens and then applying shear forces to them until they are damaged.
[0004] At present, direct shear apparatuses are mainly of two types: those for laboratory testing and those for on-site testing. However, no matter which type it is, the following defects exist:
[0005] 1) It is impossible to conduct in-situ direct shear tests on rock / soil specimens at the construction site. Instead, the rock / soil specimens need to be moved to the direct shear apparatus for testing. This will inevitably cause great disturbance to the specimens, and the water content of the specimens will also change to a certain extent, thus destroying the original state and performance of the specimens and greatly reducing the accuracy of the direct shear test.
[0006] 2) The specimen areas of direct shear apparatuses are relatively small (about 0.04 m²), which is much lower than the requirements of the "Code for Geotechnical Investigation" (GB50021-2001) (the shear area of rock specimens is 0.25 m², and the shear area of soil specimens is 0.3 m²). Therefore, the results of direct shear tests do not meet the specification requirements, and the reference value of their test results is also greatly reduced.
[0007] 3) Existing direct shear apparatuses all adopt manual operation, which is time-consuming and laborious, with low automation, and the test accuracy is greatly affected by the manual operation level.
[0008] 4) Both the upper shear block and the lower shear block are of frame structures (square frames or circular frames) or box structures, which not only make it troublesome to install specimens but also are not conducive to observing the deformation of specimens during shear. Summary of the Utility Model
[0009] Aiming at the above defects existing in the prior art, the utility model aims to provide an in-situ direct shear apparatus for rock and soil with a simple structure, convenient operation, and suitable for conducting shear tests in-situ at the construction site.
[0010] To achieve the above object, the utility model adopts the following technical solutions: It includes a normal pressure device and a shearing device located on a base frame; the base frame is a portal-shaped three-dimensional frame structure; the normal pressure device consists of a normal oil cylinder installed on the base frame through a normal angle adjusting mechanism and a backing plate assembly vertically and fixedly connected to the piston rod of the normal oil cylinder. The normal angle adjusting mechanism consists of a cross beam fixed on the base frame in an inverted concave shape, sliding grooves and locking grooves respectively located on both side walls of the cross beam, sliding pins with both ends respectively supported in the two sliding grooves and pivotally connected to the normal oil cylinder, locking plates respectively located on both sides of the cross beam and pivotally connected to both ends of the sliding pins, and two locking bolts passing through the corresponding locking grooves on both side walls of the cross beam and pressing the two locking plates tightly; the backing plate assembly consists of a lower backing plate with a number of circular arc-shaped positioning grooves arranged on its surface, rollers installed in each of the positioning grooves, and an upper backing plate covering each roller and vertically and fixedly connected to the piston rod of the normal oil cylinder; the shearing device consists of a shearing oil cylinder installed on the base frame through a rotation locking mechanism and a shearing assembly located on the rotation locking mechanism and connected to the piston rod of the shearing oil cylinder. The rotation locking mechanism consists of a mounting plate located below the backing plate assembly and pivotally connected to the base frame through a rotating shaft and having a window, guiding grooves opened on the base frame and respectively located on both sides of the mounting plate, and stud bolts respectively fixed on both sides of the mounting plate and extending outwards through the corresponding guiding grooves. The shearing oil cylinder is fixed on the mounting plate.
[0011] The shearing assembly in the above technical solution consists of a lower cutting block fixed on the mounting plate in an inverted concave shape, two groups of spherical positioning pits opened on the surface of the lower cutting block along the shearing direction, balls located in each of the positioning pits, and an upper cutting block covering the balls and connected to the piston rod of the shearing oil cylinder. Two rolling grooves adapted to the corresponding groups of balls are respectively opened on the back surface of the upper cutting block.
[0012] In the above technical solution, universal adjusting feet are fixed on the four supporting columns of the base frame. Each universal adjusting foot consists of a universal joint seat hinged to a foot plate through a pin shaft and a ball head support installed in the universal joint seat. The upper ends of each ball head support are respectively connected to the bottom ends of the corresponding supporting columns through threads.
[0013] In the above technical solution, a counterweight is fixed on the top of the base frame.
[0014] In the above technical solution, a force transmission plate is fixed on the right side of the base frame. There is a retaining wall fixed on the ground on the right side of the force transmission plate. A plurality of bolts installed on the force transmission plate are in contact with the retaining wall.
[0015] In the above technical solution, two normal displacement sensors and two shearing displacement sensors are fixed on the mounting plate. Each normal displacement sensor and each shearing displacement sensor are respectively electrically connected to a computer.
[0016] Compared with the prior art, the utility model adopts the above technical solution, and thus has the following advantages:
[0017] 1) The utility model is applicable to the in-situ sample shear strength test on flat ground, inclined slopes, and uneven ground, and can shear both rock samples and soil samples.
[0018] 2) Since in-situ detection (without moving the sample) is adopted, the disturbance and water content influence on the sample are extremely small, which can objectively and accurately reflect the original performance state of the sample and improve the accuracy of the test results.
[0019] 3) The sample preparation and test operation process are strictly carried out in accordance with the requirements of "Field Direct Shear Test" in Section 9, Chapter 10 of the "Code for Geotechnical Investigation" (GB50021-2001), fully meeting the national standards.
[0020] 4) By adopting a displacement sensor electrically connected to a computer, automatic detection and automatic display of the detection results can be realized, thus improving the automation degree and detection accuracy of the detection test.
[0021] 5) The upper shear block adopts an inverted concave-shaped structure, so it will not block the shear surface, which is beneficial to observing the deformation of the specimen during shearing.
[0022] 6) The use of universal adjustable feet can not only automatically adapt to uneven ground or inclined slopes of the construction site to ensure the stability of the base frame, but also adjust the height of the universal adjustable feet through threads to meet the needs of the height change of the sample shear surface. Description of the Drawings
[0023] Figure 1 is the structural schematic diagram of the utility model;
[0024] Figure 2 is Figure 1 the A-A cross-sectional view in
[0025] Figure 3 is Figure 1 the B-B cross-sectional view in
[0026] Figure 4 is Figure 1 the C-C cross-sectional view in
[0027] Figure 5 is Figure 3 the D-D cross-sectional view in
[0028] Figure 6 is Figure 2 the E-E cross-sectional view in
[0029] Figure 7 is Figure 5 the enlarged view at I in
[0030] Figure 8 This is a schematic diagram of the present utility model when working on an inclined slope.
[0031] Figure 9 This is a schematic structural diagram of the mounting plate of the present utility model.
[0032] Figure 10 is Figure 9 top view of.
[0033] In the figure: counterweight 1, base frame 2, normal cylinder 3, force transmission plate 4, bolt 5, retaining wall 6, shear cylinder 7, upper cutting block 8, rotating shaft 9, specimen 10, lower cutting block 11, mounting plate 12, universal adjusting foot 13, ball head support 13-1, universal seat 13-2, pin shaft 13-3, foot plate 13-4, gland 13-5, guide groove 14, stud 15, normal displacement sensor 16, locking groove 17, sliding groove 18, sliding pin 19, locking plate 20, cross beam 21, locking bolt 22, lower backing plate 23, roller 24, upper backing plate 25, cylinder seat 26, shear displacement sensor 27, ball 28, window 29. Specific embodiments
[0034] The present utility model will be further described below in conjunction with the accompanying drawings and specific embodiments.
[0035] As Figures 1 to 10 shown: The base frame 2 is a portal-shaped three-dimensional frame structure. The normal pressure device is composed of a normal cylinder 3 installed on the base frame 2 through a normal angle adjustment mechanism and a backing plate assembly perpendicularly and fixedly connected to the piston rod of the normal cylinder. The normal angle adjustment mechanism is composed of a cross beam 21 welded to the base frame 2 in an inverted concave shape (channel steel), sliding grooves 18 respectively opened on both side walls of the cross beam, locking grooves 17 opened on both side walls of the cross beam and located above and below the sliding grooves 18 respectively, sliding pins 19 with both ends respectively supported in the respective sliding grooves 18 and pivotally connected to the normal cylinder 3, locking plates 20 respectively located on both sides of the cross beam 21 and pivotally connected to the two ends of the sliding pins, and two locking bolts 22 passing through the corresponding locking grooves 17 on both side walls of the cross beam 21 and pressing the two locking plates 20 tightly.
[0036] The backing plate assembly is composed of a lower backing plate 23 with a number of arc-shaped positioning grooves (not marked in the figure) arranged on the surface, rollers 24 installed in the respective positioning grooves, and an upper backing plate 25 covering the rollers 24 and perpendicularly and fixedly connected to the piston rod of the normal cylinder 3.
[0037] The shearing device is mounted on the base frame 2 through a rotary locking mechanism. The rotary locking mechanism consists of a mounting plate 12 located below the backing plate assembly and pivotally connected to the base frame 2 through a rotating shaft 9, a window 29 formed on the mounting plate for the specimen 10 to pass through, kidney-shaped guiding grooves 14 formed on the base frame 2 and located on both sides of the mounting plate 12 respectively, and studs 15 fixed on both sides of the mounting plate 12 and extending outward through the corresponding guiding grooves 14. The shearing device consists of a shearing oil cylinder 7 fixed on the mounting plate 12 through an oil cylinder seat 26 and a shearing assembly located on the mounting plate 12. The shearing assembly consists of a lower cutting block 11 fixed on the surface of the mounting plate 12, two groups of spherical positioning pits (not marked in the figure) formed on the surface of the lower cutting block along the shearing direction, balls 28 located in each positioning pit, and an upper cutting block 8 covering the balls 28 and connected to the piston rod of the shearing oil cylinder 7. In order to ensure that the upper cutting block 8 moves in a straight line, two rolling grooves (not marked in the figure) adapted to the two groups of balls 28 are respectively formed on the back surface (the surface in contact with the balls) of the upper cutting block.
[0038] In order to facilitate the rapid positioning of the specimen 10, both the lower cutting block 11 and the upper cutting block 8 adopt an inverted concave-shaped structure, and the opening directions of the upper cutting block 8 and the lower cutting block 11 are arranged oppositely. In order to ensure the reliable positioning of the specimen 10, the opening length of the lower cutting block 11 is equal to or greater than the length of the specimen 10; in order to facilitate the observation of the deformation of the specimen 10, the opening length of the upper cutting block 8 is less than the length of the specimen 10.
[0039] In order to adapt to uneven or sloping construction sites, universal adjusting feet 13 are fixed on the four support columns of the base frame 2. Each universal adjusting foot 13 consists of a universal joint seat 13-2 hinged to a foot plate 13-4 through a pin shaft 13-3, a ball head support 13-1 installed in the universal joint seat, and a gland 13-5 fixed on the universal joint seat 13-2 and covering the ball head support 13-1. The upper ends of the ball head supports 13-1 are respectively connected to the bottom ends of the corresponding support columns through threads.
[0040] In order to prevent the base frame 2 from tipping over during the shearing process, a counterweight block 1 is fixed on the top of the base frame. In order to prevent the base frame 2 from moving during the shearing process, a force transmission plate 4 is fixed on the right side of the base frame 2. There is a retaining wall 6 fixed on the ground on the right side of the force transmission plate, and multiple bolts 5 installed on the force transmission plate 4 are in contact with the retaining wall.
[0041] In order to improve the automation degree of the instrument, two normal displacement sensors 16 and two shear displacement sensors 27 are fixed on the mounting plate 12. Each normal displacement sensor 16 and each shear displacement sensor 27 are respectively electrically connected to a computer (not shown in the figure).
[0042] To facilitate the measurement of the inclination angle of the normal oil cylinder 3, an angle sensor (not shown in the figure) electrically connected to the computer is fixed on the normal oil cylinder 3.
[0043] Working principle:
[0044] 1) Make the specimen 10 at the construction site in accordance with the "Code for Geotechnical Investigation" (GB50021 - 2001). Install and fix the base frame 2 in situ on the specimen, so that the specimen 10 passes through the window 29 and the lower cutting block 11, and exposes a certain distance upward. Then adjust the attitude of the base frame 2 through the universal adjusting feet 13 and make it stable and reliable.
[0045] 2) Adjust the normal oil cylinder 3 through the normal angle adjusting mechanism according to the inclination angle of the specimen 10 to make it consistent with the inclination angle of the specimen 10.
[0046] 3) Install the ball 28 in the positioning pit of the lower backing plate 23, and install the upper cutting block 8 on the surface of the lower cutting block 11. Place the lower backing plate 23 on the top of the specimen 10, install the roller 24 in the positioning groove, and cover the upper backing plate 25 on the surface of the lower backing plate 23.
[0047] 4) The computer controls the normal oil cylinder 3 and applies pressure to the specimen 10 through the backing plate assembly. After the pressure reaches the predetermined value, the computer controls the shear oil cylinder 7 and shears the specimen through the upper cutting block 8 until the specimen 10 breaks.
[0048] 5) During the shearing process, each normal displacement sensor 16 and each shear displacement sensor 27 transmit the collected data to the computer. The computer automatically draws the shear stress - shear displacement curve, shear force - vertical displacement curve, etc. according to data such as the area pressure of the specimen 10, the magnitude of the normal pressure, and the magnitude of the shear force. Automatically determine parameters such as the proportional strength, yield strength, peak strength, and shear strength, and the curves of normal stress - proportional strength, yield strength, peak strength, and residual strength, and automatically output the corresponding test report for future use.
Claims
1. A geotechnical in-situ direct shear apparatus, comprising a normal pressure device and a shear device located on a base frame; characterized in that: The base frame (2) is a three-dimensional frame structure in the shape of a door; The normal pressure device is composed of a normal oil cylinder (3) mounted on a base frame (2) through a normal angle adjustment mechanism, and a pad assembly vertically fixed to the piston rod of the normal oil cylinder. The normal angle adjustment mechanism is composed of a crossbeam (21) fixed to the base frame (2) in an inverted concave shape, a slide groove (18) and a locking groove (17) respectively located on the two side walls of the crossbeam, a sliding pin (19) supported at both ends in the two slide grooves (18) and pivotally connected to the normal oil cylinder (3), and two sliding pins (19) respectively located on the crossbeam. The crossbeam (21) is provided with a locking plate (20) pivotally connected to the two ends of the sliding pin, and two locking bolts (22) pass through the corresponding locking grooves (17) on the two side walls of the crossbeam (21) and press the two locking plates (20) together; the pad assembly is composed of a lower pad (23) with a plurality of arc-shaped positioning grooves arranged on the surface, a roller (24) installed in each of the positioning grooves, and an upper pad (25) covering each roller (24) and vertically fixed to the piston rod of the normal oil cylinder (3); The shearing device is composed of a shearing cylinder (7) mounted on a base frame (2) via a rotary locking mechanism, a shearing assembly located on the rotary locking mechanism and connected to the piston rod of the shearing cylinder, the rotary locking mechanism being composed of a mounting plate (12) located below the pad assembly and pivotally connected to the base frame (2) via a rotating shaft (9) and having a window (29), guide grooves (14) opened on the base frame (2) and respectively located on both sides of the mounting plate, and studs (15) respectively fixed on both sides of the mounting plate (12) and extending outward through the corresponding guide grooves (14), and the shearing cylinder (7) is fixed on the mounting plate (12).
2. The rock and soil in-situ direct shear apparatus according to claim 1, characterized in that: The shearing assembly comprises a lower cutting block (11) having an inverted concave structure and fixed on a mounting plate (12), two groups of spherical positioning pits provided on the surface of the lower cutting block along the shearing direction, balls (28) located in the positioning pits, and an upper cutting block (8) covering the balls (28) and connected to the piston rod of the shearing cylinder (7), wherein the back of the upper cutting block is provided with two rolling grooves adapted to the corresponding groups of balls (28).
3. The rock and soil in-situ direct shear apparatus according to claim 1, characterized in that: Universal adjustment feet (13) are fixed to the four support columns of the base frame (2), and each of the universal adjustment feet (13) is composed of a universal seat (13-2) hinged on a foot plate (13-4) through a pin shaft (13-3), and a ball head support (13-1) installed in the universal seat, and the upper end of each ball head support (13-1) is connected to the bottom end of the corresponding support column through a thread.
4. The rock and soil in-situ direct shear apparatus according to claim 1, characterized in that: A counterweight (1) is fixed on the top of the base frame (2).
5. The rock and soil in-situ direct shear apparatus according to claim 1, characterized in that: A force transmission plate (4) is fixed on the right side of the base frame (2), and a force retaining wall (6) fixed to the ground is provided on the right side of the force transmission plate. A plurality of bolts (5) mounted on the force transmission plate (4) are in contact with the force retaining wall.
6. The rock and soil in-situ direct shear apparatus according to claim 1, characterized in that: Two normal displacement sensors (16) and two shear displacement sensors (27) are fixed on the mounting plate (12), and each normal displacement sensor (16) and each shear displacement sensor (27) are electrically connected to a computer respectively.