A pre-drilled tooth-shaped prismatic shear apparatus and an in-situ soil shear test method

Abstract

The application provides a pre-drilled tooth-shaped prism shear instrument and a soil in-situ shear test method, and belongs to the technical field of geotechnical engineering. The shear instrument comprises a probe, a driving unit and a dynamic torque tester. A driving rod is the execution end of the driving unit and can rotate around its own axis under the action of the driving unit. The lower part of the driving rod is provided with the probe. The outer circumference of the probe is uniformly and circumferentially spaced with a plurality of axially extending strip-shaped convex edges, and the width of the strip-shaped convex edges decreases along the radial direction. The dynamic torque tester is used for measuring the torque of the probe. The shear instrument is especially suitable for coarse-grained soil and can efficiently and reliably perform in-situ shear test on coarse-grained soil and treated soil.

Description

Technical Field

[0001] This invention relates to a shearing instrument and a shearing testing method thereof, specifically to a pre-drilled toothed prism shearing instrument and an in-situ soil shearing testing method, belonging to the field of geotechnical engineering technology. Background Technology

[0002] In the field of civil engineering, soil shear strength is a key indicator for the design and safety assessment of slopes, foundations, and other engineering projects. Among these, the composite internal friction angle (FAI value) is one of the core parameters reflecting the shear characteristics of soil. To accurately obtain this indicator, in-situ testing methods are preferred because they can preserve the original structure and stress state of the soil to the greatest extent, and the results are usually closer to actual engineering conditions.

[0003] Currently, the most common in-situ geotechnical shear test is the vane shear test. The vane shear test is mainly used to rapidly determine the undrained shear strength and sensitivity of saturated soft clay. Its core principle is to press a vane of a specific size into the soft clay and apply torque through ground equipment to make it rotate at a uniform speed. However, the vane shear test is mainly suitable for saturated soft clay. For stiff plastic clay, coarse-grained soil, and dense fill, its testing results are often poor, and it may even damage the instrument, limiting its applicability under various soil conditions.

[0004] In recent years, with the increasing number of coarse-grained fill sites in engineering construction, especially in slopes, foundations, and composite soils treated with dynamic compaction and grouting, the mechanical properties of the soil have changed significantly. Accurately and in-situ determining the comprehensive internal friction angle of such treated soils has become a challenge in current geotechnical engineering testing. Currently, there is a lack of efficient and reliable in-situ shear testing equipment suitable for coarse-grained soils and treated soils. Summary of the Invention In view of this, the present invention provides a pre-drilled toothed prism shearing instrument, which is particularly suitable for coarse-grained soils and can perform efficient and reliable in-situ shear tests on coarse-grained soils and treated soils.

[0005] The technical solution of the present invention is: a pre-drilled prism shearing instrument, comprising: a toothed prism probe, a drive unit, and a dynamic torque tester; The drive rod is the execution end of the drive unit and can rotate around its own axis under the action of the drive unit; a toothed prism probe is provided at the lower part of the drive rod; The toothed prism probe has multiple axially extending strip-shaped protrusions evenly spaced along its outer circumference, and the width of the strip-shaped protrusions decreases radially. The dynamic torque tester is used to measure the torque of the toothed prism probe; The outer diameter of the toothed prism probe is larger than the diameter of the pre-drilled hole.

[0006] As a preferred embodiment of the present invention, the drive unit includes: a large gear, a small gear, and a mounting plate; The large gear is coaxially connected to the upper part of the drive rod and is used to drive the drive rod to rotate. The small gear meshes with the large gear. An operating handle is installed on the gear shaft of the small gear. The large gear and the small gear are respectively supported on the mounting plate by bearings; The mounting plate is fixed to the ground at the location of the test point.

[0007] As a preferred embodiment of the present invention: the dynamic torque tester is mounted on the gear shaft of the pinion.

[0008] As a preferred embodiment of the present invention: the mounting plate comprises two steel plates, and the large gear and the small gear are clamped between the two steel plates.

[0009] As a preferred embodiment of the present invention, the upper end of the drive rod extends out of the large gear and can be connected to the drilling rig.

[0010] As a preferred embodiment of the present invention, the toothed prism probe is provided with a tapered tip at its end.

[0011] As a preferred embodiment of the present invention, the outer diameter of the toothed prism probe is 2 cm larger than the diameter of the pre-drilled hole.

[0012] As a preferred embodiment of the present invention, the length of the strip-shaped protrusion on the toothed prism probe is between 0.75 meters and 1 meter.

[0013] Furthermore, based on the aforementioned pre-drilled toothed prism shear apparatus, this invention provides an in-situ soil shear testing method: S1: First, hammer or press the toothed prism probe into the pre-drilled hole in the soil to a set depth. S2: Install a drive unit and a dynamic torque tester on the soil surface so that the drive unit can drive the toothed prism probe to rotate via the drive rod; S3: Drive the toothed prism probe to rotate, so that it performs progressive shearing on the soil; During the shearing process, the applied torque and rotation angle are continuously recorded by the dynamic torque tester until the soil is sheared and the torque reaches its peak. Then, the rotation continues to obtain residual strength.

[0014] 10. The soil in-situ shear test method as described in claim 9, characterized in that, after completing a test at one depth, the drive rod is connected to the drilling rig, and the drilling rig is used to hammer or press the toothed prism probe into the next predetermined depth, and then the toothed prism probe is driven to rotate so that it produces progressive shear on the soil.

[0015] Beneficial effects: (1) The pre-drilled toothed prism shearing instrument of the present invention uses a toothed prism probe with strip-shaped protrusions distributed on the outer circumference to perform in-situ shearing tests, which is suitable for shearing tests of coarse-grained soil.

[0016] (2) In the pre-drilled toothed prism shearing device of the present invention, the drive unit uses a small gear to drive a large gear, which can reduce the peak force of the small gear: the small gear has fewer teeth and the tooth surface contact area is smaller when the module is the same. The drive wheel is designed as a small gear, which can avoid the problem of excessive tooth root bending stress caused by torque concentration when the large gear is the drive wheel, and improve the overall durability of the gear pair; and can realize torque amplification and deceleration matching.

[0017] (3) In the pre-drilled toothed prism shearing instrument of the present invention, a large gear extends from the upper end of the drive rod to connect to the drill rod of the drilling machine, thereby enabling continuous measurement at different depths in situ.

[0018] (4) In the pre-drilled toothed prism shearing instrument of the present invention, the end of the probe is provided with a conical tip, which is conducive to hammering or pressing the probe downward.

[0019] (5) The pre-drilled toothed prism shearing instrument of the present invention has a simple overall structure and is particularly suitable for in-situ shearing tests.

[0020] (6) The pre-drilled toothed prism shearing instrument of the present invention can be used to perform in-situ shearing tests on coarse-grained soil and treated soil in an efficient and reliable manner. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the pre-drilled toothed prism shearing device of the present invention; Figure 2 This is a schematic diagram showing the usage state of the pre-drilled toothed prism shearing instrument of the present invention; Figure 3 This is a schematic diagram of the transmission unit in the pre-drilled toothed prism shearing device of the present invention; Figure 4 This is a schematic cross-sectional view of the prism probe in the pre-drilled toothed prism shearing instrument of the present invention.

[0022] Among them: 1-toothed prism probe, 101-strip-shaped convex ridge, 102-conical tip, 2-drive rod, 3-large gear, 4-small gear, 5-dynamic torque tester, 6-mounting plate, 7-pre-drilled hole, 8-operating handle. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0024] Example 1: This embodiment provides a pre-drilled toothed prism shearing instrument, which uses a toothed prism probe with strip-shaped convex edges distributed on the outer circumference to perform in-situ shearing tests, and is suitable for shearing tests of coarse-grained soils.

[0025] like Figure 1 and Figure 2 As shown, the pre-drilled prism shearing device includes: a toothed prism probe 1, a drive unit, and a dynamic torque tester 5.

[0026] The drive rod 2 is the execution end of the drive unit. The drive rod 2 can rotate around its own axis under the action of the drive unit. The lower part of the drive rod 2 is provided with a toothed prism probe 1. The drive rod 2 can also be integrated with the toothed prism probe 1. The drive rod 2 drives the toothed prism probe 1 to rotate around its own axis.

[0027] The toothed prism probe 1 has a structure in which multiple axially extending strip-shaped protrusions 101 (protruding stripes, i.e., strip teeth) are evenly distributed along the circumference of the outer circumference, and the width of the strip-shaped protrusions 101 decreases radially, so the cross-section of the strip-shaped protrusions 101 is trapezoidal or triangular; the strip-shaped protrusions 101 are made of wear-resistant material.

[0028] As an example, the toothed prism probe 1 has eight axially extending strip-shaped protrusions 101 evenly spaced along the circumference.

[0029] As an example, the toothed prism probe 1 has a tapered tip 102 at its end, which facilitates hammering or pressing the toothed prism probe 1 downwards; the tapered tip 102 is also made of wear-resistant material.

[0030] As an example, the drive rod 2 and the toothed prism probe 1 are detachably connected, which facilitates maintenance, replacement of worn parts, or adaptation to different testing needs.

[0031] The dynamic torque tester 5 is used to measure the torque of the toothed prism probe 1, that is, to determine the resisting torque that the toothed prism probe 1 experiences when rotating and shearing in the soil.

[0032] This shearing device is a pre-drilled in-situ testing instrument, and as... Figure 4 As shown, the outer diameter of the toothed prism probe 1 (the diameter at the tip of the strip convex 101 of the toothed prism probe 1, i.e. the diameter of the circumscribed circle of the toothed prism probe 1) is greater than the diameter of the pre-drilled hole 7; preferably, the outer diameter of the toothed prism probe 1 is 2 cm greater than the diameter of the pre-drilled hole 7.

[0033] As an example, the length of the strip-shaped protrusions 101 on the toothed prism probe 1 is between 0.75 meters and 1 meter, which can cover the particle size of most coarse soils while ensuring rigidity.

[0034] In use, the toothed prism probe 1 is hammered or pressed into the pre-drilled hole 7 to a set depth. During the hammering or pressing process, ensure that it is vertically downward and avoid tilting (to avoid introducing additional friction or torque, which would interfere with the accurate measurement of torque). Then, the drive unit drives the toothed prism probe 1 to horizontally cut the soil. The torque of the entire contact area between the toothed prism probe 1 and the soil (i.e., the surface area of ​​the cylinder formed by the outer diameter of the toothed prism probe 1 rotating one revolution) is converted into shear strength (this calculation formula is a known formula and will not be elaborated here).

[0035] Example 2: Based on the above embodiment 1, a preferred embodiment of the driving unit is given.

[0036] like Figure 3 As shown, the drive unit includes a large gear 3, a small gear 4 (here, "large" and "small" refer to two gears relative to each other), and a mounting plate 6. The large gear 3 is coaxially connected to the upper part of the drive rod 2 to drive the drive rod 2 to rotate. The small gear 4 meshes with the large gear 3. An operating handle 8 is mounted on the gear shaft of the small gear 4. Therefore, when the small gear 4 is rotated by operating handle 8, the drive rod 2 will be rotated through the large gear 3, thereby driving the probe 1 to rotate.

[0037] The large gear 3 and the small gear 4 are supported on the mounting plate 6 by bearings.

[0038] In this design, the drive unit uses a small gear 4 to drive a large gear 3, which reduces the peak force on the small gear. The small gear 4 has fewer teeth and a smaller tooth surface contact area for the same module. Designing the small gear 4 as the driving gear avoids the problem of excessive tooth root bending stress caused by torque concentration when the large gear is used as the driving gear, thus improving the overall durability of the gear pair. Furthermore, it achieves torque amplification and speed reduction matching: the small gear 4 driving the large gear 3 is a speed reduction transmission. With stable input power, the output torque increases with the transmission ratio, meeting the low-speed, high-torque operating requirements of heavy-duty equipment (such as construction machinery and lifting equipment), while also allowing the force to be more evenly distributed across multiple tooth surfaces of the large gear 3.

[0039] As an example, the dynamic torque tester 5 is mounted on the gear shaft of the pinion 4. The connection between the large gear 3 and the drive rod 2 ensures that the large gear 3 can drive the drive rod 2 to rotate, and the drive rod 2 can move axially relative to the large gear 3 (e.g., the large gear 3 is coaxially connected to the drive rod 2 via a spline connection or a sliding key connection). The upper end of the drive rod 2 extends out of the large gear 3 to connect to the drill rod of the drilling rig, thereby enabling continuous measurement at different depths in situ. After the soil test at the current depth is completed, the drill rod of the drilling rig is connected to the upper end of the drive rod 2, and the drill rod of the drilling rig is hammered, thereby striking the toothed prism probe 1 at the stratum at the set depth below.

[0040] As an example, mounting plate 6 comprises two steel plates, with a large gear 3 and a small gear 4 sandwiched between them. The upper and lower end faces of the large gear 3 and the small gear 4 are connected to the corresponding steel plates via bearings. The two plates are fixed to the ground at the test point location using fasteners.

[0041] Example 3: Based on the drilling prism shear apparatus in Embodiment 1 or Embodiment 2 above, this embodiment provides an in-situ shear testing method, the specific steps of which are as follows: S1: First, connect the drive rod 2 to the exploration drilling rig (at this time, the drive rod 2 is not connected to the drive unit). Use the hammering or pressing function of the exploration drilling rig to hammer or press the toothed prism probe 1 into the pre-drilled hole in the soil at the set depth (i.e., the predetermined test depth). S2: Install the drive unit and dynamic torque tester 5 on the soil surface so that the drive unit can drive the toothed prism probe 1 to rotate through the drive rod 2, and use fasteners (such as rivets) to fix the mounting plate 6 in the drive unit to the ground.

[0042] S3: The dynamic torque tester 5 is rotated by ground equipment (such as manual or electric), which in turn drives the toothed prism probe 1 to rotate, causing it to perform progressive shearing on the soil.

[0043] The applied torque and rotation angle are continuously recorded until the soil is sheared and the torque reaches its peak. Rotation continues to obtain the residual strength. The peak strength and residual strength are the key data for calculating the shear strength index. After completing a depth test, connect the drive rod 2 to the exploration drilling rig, and use the drilling rig to hammer or press the toothed prism probe 1 into the next predetermined depth, repeating steps S2 and S3.

[0044] Therefore, by conducting multiple tests at different depths, a continuous profile of soil shear strength variation with depth can be obtained, thus providing a more comprehensive evaluation of the stratum's mechanical properties.

[0045] As an example, before testing, the dynamic torque tester 5 is zeroed and its readings are calibrated to eliminate systematic errors and ensure data accuracy.

[0046] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A pre-drilled toothed prism shearing instrument, characterized in that, include: Toothed prism probe (1), drive unit and dynamic torque tester (5); The drive rod (2) is the execution end of the drive unit and can rotate around its own axis under the action of the drive unit; a toothed prism probe (1) is provided at the lower part of the drive rod (5). The toothed prism probe (1) has multiple axially extending strip-shaped protrusions (101) evenly distributed along the circumference of its outer circumference, and the width of the strip-shaped protrusions (101) decreases radially. The dynamic torque tester (5) is used to measure the torque of the toothed prism probe (1); The outer diameter of the toothed prism probe (1) is larger than the diameter of the pre-drilled hole (7).

2. The pre-drilled toothed prism shearing instrument as described in claim 1, characterized in that, The drive unit includes: a large gear (3), a small gear (4), and a mounting plate (6); The large gear (3) is coaxially connected to the upper part of the drive rod (2) to drive the drive rod (2) to rotate. The small gear (4) meshes with the large gear (3). An operating handle (8) is installed on the gear shaft of the small gear (4). The large gear (3) and the small gear (4) are respectively supported on the mounting plate (6) by bearings; The mounting plate (6) is fixed to the ground at the location of the test point.

3. The pre-drilled prism shearing device as described in claim 2, characterized in that, The dynamic torque tester (5) is mounted on the gear shaft of the pinion (4).

4. The pre-drilled prism shearing device as described in claim 2 or 3, characterized in that, The mounting plate (6) comprises two steel plates, with the large gear (3) and the small gear (4) sandwiched between the two steel plates.

5. The pre-drilled prism shearing device as described in claim 2 or 3, characterized in that, The upper end of the drive rod (2) extends out of the large gear (3) and can be connected to the drilling rig.

6. The pre-drilled prism shearing device as described in claim 1, 2, or 3, characterized in that, The toothed prism probe (1) is provided with a tapered tip (102) at its end.

7. The pre-drilled prism shearing device as described in claim 1, 2, or 3, characterized in that, The outer diameter of the toothed prism probe (1) is 2 cm larger than the diameter of the pre-drilled hole (7).

8. The pre-drilled prism shearing device as described in claim 1, 2, or 3, characterized in that, The length of the strip-shaped protrusion (101) on the toothed prism probe (1) is between 0.75 meters and 1 meter.

9. A method for in-situ shear testing of soil, characterized in that, Based on any one of claims 1-8, the pre-drilled prism shearing device S1: First, hammer or press the toothed prism probe (1) into the pre-drilled hole in the soil to a set depth. S2: Install a drive unit and a dynamic torque tester (5) on the soil surface so that the drive unit can drive the toothed prism probe (1) to rotate through the drive rod (2); S3: Drive the toothed prism probe (1) to rotate, so that it produces progressive shear on the soil; During the shearing process, the applied torque and rotation angle are continuously recorded by the dynamic torque tester (5) until the soil is sheared and the torque reaches its peak value. Then, the rotation continues to obtain residual strength.

10. The in-situ soil shear test method as described in claim 9, characterized in that, After completing a depth test, the drive rod (2) is connected to the drilling rig, and the drill rig is used to hammer or press the toothed prism probe (1) to the next predetermined depth. Then the toothed prism probe (1) is driven to rotate, so that it produces progressive shearing on the soil.

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