A device and method for testing in-situ loess collapsibility coefficient in hole based on cutting load method

Abstract

The application discloses a hole in-situ loess collapsibility coefficient testing device and method based on a cutting load method; the hole cutting device comprises a first cylinder, a plurality of side surfaces of the first cylinder are provided with support rods, the support rods correspond to the output end position of the first cylinder, a conductive ring is connected with a first motor, and a tool bit is connected with the output shaft of a second motor; the collapsibility coefficient testing device comprises two support plates which are vertically arranged in a circular ring, a fourth cylinder and a bidirectional electric push rod are located in the middle of the support plates, the output ends on the two sides of the fourth cylinder are connected with the support plates, the upper and lower output shafts of the bidirectional electric push rod are connected with upper loading units and lower loading units which are the same in structure, the upper loading units and the lower loading units are all provided with pressure plates which can be expanded in the radial direction, and a plurality of radial water spray holes are arranged on the pressure plates of the lower loading units. The testing position is flexible, and the testing result is more accurate and reliable.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering testing and relates to a device and method for testing the collapsibility coefficient of loess in situ within a borehole based on the cutting load method. Background Technology

[0002] Collapsible loess undergoes significant deformation and its strength rapidly decreases when wetted under certain pressure. According to my country's "Building Standard for Collapsible Loess Areas" GB50025-2018, loess collapsibility testing mainly includes indoor single-line and double-line methods, as well as the field immersion method. Among these, field testing is widely used in engineering practice because it avoids disturbance to the sample compared to indoor testing. In some areas of my country, the depth of collapsible loess under its own weight can reach 50-60 meters. For deeply buried collapsible loess, the field immersion method is limited by site constraints, has a long testing cycle, and requires large amounts of water, often resulting in significant deviations from actual conditions. To meet the needs of engineering construction, how to quickly and accurately evaluate the collapsibility of loess at different burial depths has become a crucial issue that must be addressed to ensure the foundation stability of urban buildings in loess areas and the safe operation and maintenance of railway lines.

[0003] Although some studies have proposed testing devices and methods for the collapsibility coefficient of loess in boreholes, they are insufficient in terms of accuracy and efficiency. For example, the invention patent "Direct Measurement Device and Method for Loess Collapsibility Coefficient in Boreholes (CN109238866B)" uses a single-line method, but only one pressure is applied in a set of borehole tests, which does not meet the requirement of three or more static load tests for the single-line method. Another example is the invention patent "Test Device and Method for Loess Collapsibility Coefficient in Boreholes (CN117647443B)" which performs loading tests on annular soil masses in boreholes, but both the jacking end and the anchoring end of the annular soil mass are deformed under stress. If the jacking distance is not accurately obtained, it will seriously affect the accuracy of the collapsibility coefficient test. Clearly, there is still a lack of effective means and methods for obtaining the collapsibility coefficient of deep loess. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a device and method for testing the in-situ loess collapse coefficient in boreholes based on the cutting load method. The test location is flexible and the test results are more accurate and reliable.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A borehole in-situ loess collapsibility coefficient testing device based on cutting load method, comprising a borehole cutting device and a collapsibility coefficient testing device;

[0007] The in-hole cutting device includes a cross plate, a first cylinder, a first motor, a conductive ring, a second motor, and a cutting head connected in sequence from top to bottom; multiple sides of the first cylinder are provided with support rods, the support rods are positioned corresponding to the output end of the first cylinder, the conductive ring is connected to the first motor, and the output shaft of the second motor is connected to the cutting head;

[0008] The collapsibility coefficient testing device includes a support plate, a fourth cylinder, a bidirectional electric actuator, and a pressure plate. The two support plates are arranged vertically in a ring. The fourth cylinder and the bidirectional electric actuator are located in the middle of the support plate. The output ends on both sides of the fourth cylinder are connected to the support plate. The upper and lower output shafts of the bidirectional electric actuator are connected to the upper loading unit and the lower loading unit, which have the same structure. The top of the upper loading unit and the bottom of the lower loading unit are both equipped with pressure plates that can expand radially. The pressure plate located in the lower loading unit is equipped with multiple radial water spray holes.

[0009] Preferably, a lifting ring is connected to the top of the cross plate.

[0010] Preferably, the support rod has an L-shaped structure, with its short side slidably connected to the top of the first cylinder and its long side located on the side of the first cylinder. The side of the first cylinder is provided with multiple air inlets facing the long side of the support rod.

[0011] Preferably, the top of the conductive ring is connected to the first motor via a disk, and the cross plate is connected to the disk via two connecting rods.

[0012] Preferably, the output shaft of the second motor is vertically connected to a gear, which meshes with two horizontal racks, each rack having a cutter head at its end.

[0013] Preferably, both output shafts of the bidirectional electric actuator are connected to a flange, the pressure plate is set on the disc, the flange and the disc are connected by a connecting rod, and a radial guide rail and a radial tilting guide rail are provided at the connection between the connecting rod and the disc;

[0014] Each pressure plate is composed of multiple large unfolding plates and multiple small unfolding plates interspersed. The multiple large unfolding plates are slidably arranged along radial guide rails, and the multiple small unfolding plates are slidably arranged along radial inclined guide rails.

[0015] Preferably, a second cylinder and a third cylinder are provided between the pressure plate and the flange. The second cylinder is connected to multiple large unfolding plates through a linkage mechanism, and the third cylinder is connected to multiple small unfolding plates through a linkage mechanism.

[0016] Preferably, displacement sensors for acquiring displacement data are respectively provided at the top of the upper loading unit and at the bottom of the lower loading unit.

[0017] Preferably, the water spray holes are evenly distributed around the circumference, and multiple water spray holes are arranged in a ring around the large unfolding plate at equal intervals.

[0018] A method for testing the in-situ loess collapsibility coefficient in borehole using the cutting load method-based in-situ loess collapsibility coefficient testing device includes the following steps:

[0019] Step 1: Select a drilling location on the ground and drill a hole;

[0020] Step 2: Lower the in-hole cutting device to the target depth and deploy the support rod using the first cylinder to anchor the in-hole cutting device.

[0021] Step 3: Start the first motor to drive the conductive ring to rotate, and the second motor to drive the cutter head to cut and form two upper and lower soil sample grooves to be tested. Then retract the cutting device in the hole.

[0022] Step 4: Lower the collapsibility coefficient testing device to the soil sample trough and unfold the support plate using the fourth cylinder;

[0023] Step 5: Unfold the pressure plate;

[0024] Step 6: Inject water into the sample through the spray nozzle;

[0025] Step 7: Apply pressure step by step using a bidirectional electric actuator and record the vertical displacement of the upper and lower specimens under each pressure level.

[0026] Step 8: Calculate the vertical loess collapse coefficient under each pressure level.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention provides an in-situ loess collapsibility coefficient testing device based on the cutting load method. By setting up an in-hole cutting device and a collapsibility coefficient testing device, it can form two annular soil sample grooves at any depth in the borehole. A radial unfolding structure and a bidirectional electric actuator are used to apply loading force, combined with a water jet to create a saturated state. This allows for simultaneous graded loading tests on samples in both natural and submerged states, minimizing disturbance to the loess and effectively obtaining the true deformation data of the upper and lower samples. The device is compact, reliably anchored, and the support rod is driven by a cylinder for adaptive unfolding. The pressure plate uses a multi-segment unfolding structure to improve fitting accuracy. It can efficiently complete loess collapsibility coefficient testing in complex geological environments, offering flexible testing positions with minimal disturbance. It is suitable for in-situ testing of deep collapsible loess, improving testing accuracy and engineering adaptability.

[0029] Furthermore, this invention employs gear and rack meshing, which, compared to single-blade rotary cutting, maintains a consistent feed rate, ensuring the quality of the sample formed inside the hole and improving testing efficiency. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the in-hole cutting device and its in-hole operation according to the present invention;

[0031] Figure 2 This is a schematic diagram of the collapsibility coefficient testing device and a schematic diagram of the working inside the borehole of the present invention;

[0032] Figure 3 This is a diagram illustrating the working process of the in-hole cutting device of the present invention.

[0033] Figure 4 This is a diagram illustrating the working process of the collapsibility coefficient testing device of the present invention;

[0034] Figure 5 This is a schematic diagram of the gear structure of the present invention;

[0035] Figure 6 This is a schematic diagram of the closing and unfolding structure of the large and small display panels of the present invention;

[0036] Figure 7 This is a schematic diagram of the bidirectional electric actuator structure of the present invention;

[0037] Figure 8 This is a schematic diagram of the support rod structure of the in-hole cutting device of the present invention;

[0038] Figure 9 The figures show the volume-pressure change test curves of loess under unhydrated and hydrated conditions, respectively, according to the present invention.

[0039] The components are: 1. Lifting ring, 2. Cross plate, 3. First cylinder, 31. Air inlet, 32. Air outlet, 4. Support rod, 5. Conductive ring, 6. Motor, 61. First motor, 62. Second motor, 7. Cutter head, 8. Gear, 9. Support plate, 10. Pressure plate, 101. Large unfolding plate, 102. Small unfolding plate, 11. Bidirectional electric actuator, 12. Water spray hole, 13. Connecting rod, 14. Side limiting ring, 34. Second cylinder, 35. Third cylinder, 36. Fourth cylinder. Detailed Implementation

[0040] Embodiments of the present invention are described in detail below, examples of which 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.

[0041] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do 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 the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terms “installation,” “connection,” and “linkage” should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection; a mechanical connection, an electrical connection, or a connection that allows communication; a direct connection or an indirect connection via an intermediate medium; or a connection within two elements or an interaction between two elements. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0043] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0044] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0045] The in-situ loess collapsibility coefficient testing device based on the cutting load method described in this embodiment mainly consists of two parts: an in-situ cutting device and a collapsibility coefficient testing device. Each part has a compact structure and coordinated functions, and can efficiently and accurately obtain loess collapsibility coefficient data under in-situ conditions.

[0046] like Figure 1 As shown, Ⅰ is the rotation control part of the in-hole cutting device; Ⅱ is the extension control part of the in-hole cutting device.

[0047] like Figure 1 As shown, the in-hole cutting device is mainly used to cut two soil sample annular grooves in situ at a predetermined depth in the borehole wall for subsequent loading tests of the collapsibility coefficient. The in-hole cutting device includes a lifting ring 1, a cross plate 2, a first cylinder 3, a support rod 4, a conductive ring 5, a motor 6, a cutter head 7, and a gear 8.

[0048] Before operation, the entire device is first lowered into the borehole of the predetermined depth using ropes via lifting ring 1. Lifting ring 1 is then connected and fixed to cross plate 2 with appropriate bolts. Cross plate 2 is further connected to four support rods 4. Figure 8 As shown, the support rod 4 is L-shaped, with its short side horizontally slidingly connected to the top and bottom of the first cylinder 3, and its long side located on the side of the first cylinder 3. Air inlets are provided on all four sides of the first cylinder 3, with the air inlets facing the long side of the support rod 4. The support rod 4 is driven to expand outward by the air blown from the first cylinder 3. After expansion, it tightens the hole wall, thereby stably anchoring the entire cutting device inside the hole to the hole wall. The first cylinder 3 is provided with an air inlet 31 and an air outlet 32 ​​for supplying air to the first cylinder 3.

[0049] Motor 6 includes a first motor 61 and a second motor 62, which are responsible for controlling the rotation of the conductive ring 5 and the extension and retraction of the cutter head 7, respectively. The first motor 61 is located below the first cylinder 3. The output shaft of the first motor 61 is vertically connected downwards to the conductive ring 5. The top of the conductive ring 5 is connected to the first motor 61 via a disc. The cross plate 2 is connected to the disc via two connecting rods. The bottom of the conductive ring 5 is connected to the second motor 62, driving the lower cutting mechanism to rotate. The extension and retraction of the cutter head 7 are controlled by the second motor 62.Figure 5 As shown, the output shaft of the second motor 62 is vertically connected to the gear 8, which is horizontally meshed with two racks. The end of the rack is equipped with a cutter head 7. Through the transmission of the gear 8 and the rack, a stable feed rate is ensured during the cutting process. The gear 8 and the rack are set in the bottom support housing.

[0050] After activating the borehole cutting device, the cutter head 7 gradually extends and begins to rotate, performing cutting operations along the borehole wall. After completing the cutting of the first soil sample trench, the borehole cutting device is moved down to the second test position, and the above operation is repeated to cut out the second soil sample trench. The entire process can be completed at any depth within the borehole, maximizing the restoration of the original state of the soil.

[0051] like Figure 2 As shown, the collapsibility coefficient testing device is used for in-situ testing of the collapsibility deformation of loess in two soil sample trenches formed by cutting. It mainly includes a support plate 9, a pressure plate 10, a fourth cylinder 36, a bidirectional electric actuator 11, a water spray hole 12, a connecting rod 13, and a side-limiting ring 14.

[0052] like Figure 2 In the diagram, Ⅲ represents the collapsibility coefficient testing device under natural conditions, Ⅳ represents the anchoring part of the collapsibility coefficient testing device, and Ⅴ represents the collapsibility coefficient testing device under saturated conditions.

[0053] The support plate 9 is the main structure of the collapsibility coefficient testing device. Two arc-shaped support plates 9 are vertically arranged in a ring in the middle of the collapsibility coefficient testing device. The fourth cylinder 36 and the bidirectional electric push rod 11 are located in the center of the support plate 9. A connecting rod is set on each side of the fourth cylinder 36 to connect with the support plate 9.

[0054] The bidirectional electric actuator 11 has two output shafts, one upper and one lower, connected to a flange, such as... Figure 7 As shown, the bidirectional electric actuator 11 is the power core and adopts a telescopic structure to drive the two loading units, the upper natural condition sample and the lower water-immersed sample, respectively.

[0055] The upper loading unit and the lower loading unit have the same structure, both of which are equipped with a pressure plate 10 and a side limiting ring 14. The pressure plate 10 is set on the disc, and the flange and the disc are connected by a connecting rod. A radial guide rail and a radial inclined guide rail are provided at the connection between the connecting rod and the disc.

[0056] The pressure plate 10 is composed of multiple large unfolding plates 101 and multiple small unfolding plates 102 interleaved. The large unfolding plates 101 are slidably connected to the radial guide rail, and the small unfolding plates 102 are slidably connected to the radial inclined guide rail. After the multiple large unfolding plates 101 and multiple small unfolding plates 102 are contracted, the small unfolding plates 102 are located above the large unfolding plates 101. The multiple large unfolding plates 101 form a small diameter circle, and the multiple small unfolding plates 102 form a small diameter circle. After the multiple large unfolding plates 101 and multiple small unfolding plates 102 are unfolded, they interleave to form a disc structure.

[0057] A second cylinder 34 and a third cylinder 35 are provided between the pressure plate and the flange. The large unfolding plate 101 and the small unfolding plate 102 are controlled by the linkage mechanism driven up and down by the second cylinder 34 and the third cylinder 35, respectively. When the output shafts of the second cylinder 34 and the third cylinder 35 extend, the linkage mechanism drives the large unfolding plate 101 to extend along the radial guide rail, creating a gap between adjacent large unfolding plates 101. The linkage mechanism drives the small unfolding plate 102 to extend along the radial inclined guide rail, extending the small unfolding plate 102 between adjacent large unfolding plates 101. The large unfolding plate 101 and the small unfolding plate 102 form a large diameter circle.

[0058] After the collapsibility coefficient testing device is placed into the hole, the large unfolding plate 101 and the small unfolding plate 102 unfold and extend into the upper and lower soil sample troughs to be tested. The pressure plate 10 located in the upper soil sample trough is on top of the upper soil sample trough, and the top of the upper soil sample trough is the upper sample. The pressure plate 10 located in the lower soil sample trough is on top of the bottom of the lower soil sample trough, and the bottom of the lower soil sample trough is the lower sample.

[0059] The lateral confinement ring 14 is set at the top of the upper loading unit and the bottom of the lower loading unit. The lateral confinement ring 14 is located outside the two soil sample trenches to prevent the soil sample from becoming unstable due to lateral deformation during loading.

[0060] The water spray holes 12 are radially arranged on the large unfolding plate 101 to apply uniform water injection to the lower soil sample, which can achieve annular water seepage and bring it to a saturated state, effectively accelerating the saturation rate of the sample.

[0061] After the collapsibility coefficient testing device is lowered to the testing position, the fourth cylinder 36 unfolds the support plate 9, which is then anchored to the borehole wall. Subsequently, the second cylinders 34 and 35 sequentially drive the large unfolding plate 101 and the small unfolding plate 102 to unfold, forming a complete enclosure and loading surface for the sample.

[0062] Displacement sensors are installed at the top of the upper loading unit and at the bottom of the lower loading unit.

[0063] The above-mentioned in-situ loess collapsibility coefficient testing device based on the cutting load method includes the following process when conducting in-situ loess collapsibility coefficient testing:

[0064] Step 1: Clean the test site and select the drilling location. Use a drill rod to drill to the predetermined depth to obtain the borehole.

[0065] Step 2: Hoist the in-hole cutting device to the test position using ropes, inflate the first cylinder 3 to expand the support rod 4, and provide anchoring force to fix the in-hole cutting device in the hole.

[0066] Step 3: After fixing the in-hole cutting device, start the first motor 61 and the second motor 62. While extending the blade to cut the soil sample groove to be tested, rotate the conductive ring 5 to form the soil sample groove to be tested. Repeat the operation at a suitable position below the first soil sample groove to obtain the second soil sample groove to be tested.

[0067] Step 4: After the two soil sample trenches are cut, retract the cutting device inside the hole.

[0068] Step 5: Use ropes to place the collapsibility coefficient testing device at the pre-cut soil sample trench, and use the fourth cylinder 36 to unfold the support plate 9 to provide sufficient anchoring force to fix the collapsibility coefficient testing device in the test position.

[0069] Step 6: The large unfolding plate 101 and the small unfolding plate 102 at the top of the upper loading unit and the bottom of the lower loading unit are unfolded by the second cylinder 34 and the third cylinder 35.

[0070] Step 7: Continuously inject water at the bottom of the lower loading unit through the water spray hole 12 to wet the sample and observe the water level. When the water in the borehole can no longer penetrate, the test soil layer is considered to be saturated.

[0071] Step 8: Apply a certain pressure with the bidirectional electric actuator until the vertical displacement of the sample at position 10 of the pressure plate changes by less than 0.10 mm over two consecutive hours. The deformation is then considered stable, and the vertical displacement is recorded as s. z and s z ',like Figure 9 As shown, the vertical displacement is measured by displacement sensors at the top of the upper loading unit and the bottom of the lower loading unit.

[0072] Step 9: Continue to control the bidirectional electric actuator to apply the next level of pressure until the vertical displacement of the specimen at the upper and lower unfolding plate positions changes by less than 0.10 mm over two consecutive hours. The deformation is then considered stable. Record the vertical displacement as s. z1 and s z1 ',like Figure 9 As shown.

[0073] Step 10: Calculate the vertical loess collapsibility coefficient under each pressure level:

[0074]

[0075] In the formula: This represents the vertical loess collapse coefficient. The height of the sample after it has stabilized under a certain pressure level and is saturated with water. The height of the specimen after natural deformation stabilizes under a certain pressure level.

[0076] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0077] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0078] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0079] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0080] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

[0081] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this patent should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. A device for testing the in-situ collapse coefficient of loess in boreholes based on the cutting load method, characterized in that, Includes in-hole cutting device and wet collapse coefficient testing device; The in-hole cutting device includes a cross plate (2), a first cylinder (3), a first motor (61), a conductive ring (5), a second motor (62), and a cutter head (7) connected from top to bottom. The first cylinder (3) has support rods (4) on multiple sides, and the support rods (4) correspond to the output end of the first cylinder (3). The conductive ring (5) is connected to the first motor (61), and the output shaft of the second motor (62) is connected to the cutter head (7). The in-hole cutting device is used to cut out two soil sample trenches to be tested, one above the other. The collapsibility coefficient testing device includes a support plate (9), a fourth cylinder (36), a bidirectional electric actuator (11), and a pressure plate (10). The two support plates (9) are arranged vertically in a ring. The fourth cylinder (36) and the bidirectional electric actuator (11) are located in the middle of the support plate (9). The output ends of the fourth cylinder (36) on both sides are connected to the support plate (9). The upper and lower output shafts of the bidirectional electric actuator (11) are connected to the upper loading unit and the lower loading unit with the same structure. The top of the upper loading unit and the bottom of the lower loading unit are provided with a pressure plate (10) that can be radially extended. The pressure plate (10) located in the lower loading unit is provided with multiple radial water spray holes (12). The two pressure plates (10) extend into the upper and lower soil sample tanks to be tested, respectively.

2. The in-situ loess collapsibility coefficient testing device based on the cutting load method according to claim 1, characterized in that, The top of the cross plate (2) is connected to a lifting ring (1).

3. The in-situ loess collapsibility coefficient testing device based on the cutting load method according to claim 1, characterized in that, The support rod (4) has an L-shaped structure. Its short side is slidably connected to the top of the first cylinder (3), and its long side is located on the side of the first cylinder (3). The side of the first cylinder (3) is provided with multiple air inlets facing the long side of the support rod (4).

4. The in-situ loess collapsibility coefficient testing device based on the cutting load method according to claim 1, characterized in that, The top of the conductive ring (5) is connected to the first motor (61) via a disk, and the cross plate (2) is connected to the disk via two connecting rods.

5. The in-situ loess collapsibility coefficient testing device based on the cutting load method according to claim 1, characterized in that, The output shaft of the second motor (62) is vertically connected to the gear (8), which meshes with two horizontal racks. Each rack has a cutter head (7) at its end.

6. The in-situ loess collapsibility coefficient testing device based on the cutting load method according to claim 1, characterized in that, The two output shafts of the bidirectional electric actuator (11) are connected to a flange, and the pressure plate (10) is set on the disc. The flange and the disc are connected by a connecting rod. A radial guide rail and a radial tilting guide rail are provided at the connection between the connecting rod and the disc. Each pressure plate (10) is composed of multiple large unfolding plates (101) and multiple small unfolding plates (102) interleaved. The multiple large unfolding plates (101) are slidably arranged along the radial guide rail, and the multiple small unfolding plates (102) are slidably arranged along the radial inclined guide rail.

7. The in-situ loess collapsibility coefficient testing device based on the cutting load method according to claim 6, characterized in that, A second cylinder (34) and a third cylinder (35) are provided between the pressure plate (10) and the flange. The second cylinder (34) is connected to multiple large unfolding plates (101) through a linkage mechanism, and the third cylinder (35) is connected to multiple small unfolding plates (102) through a linkage mechanism.

8. The in-situ loess collapsibility coefficient testing device based on the cutting load method according to claim 6, characterized in that, The water spray holes (12) are evenly distributed around the circumference, and multiple water spray holes (12) are arranged in a ring along the large unfolding plate (101) at equal intervals.

9. The in-situ loess collapsibility coefficient testing device based on the cutting load method according to claim 1, characterized in that, Displacement sensors for acquiring displacement data are respectively installed at the top of the upper loading unit and at the bottom of the lower loading unit.

10. A method for testing the in-situ loess collapsibility coefficient in a borehole based on the cutting load method of any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Select a drilling location on the ground and drill a hole; Step 2: Lower the in-hole cutting device to the target depth and deploy the support rod (4) through the first cylinder (3) to anchor the in-hole cutting device; Step 3: Start the first motor (61) to drive the conductive ring (5) to rotate, and the second motor (62) to drive the cutter head (7) to cut and form the upper and lower soil sample grooves to be tested. Then retract the cutting device in the hole. Step 4: Lower the collapsibility coefficient testing device to the soil sample trough and unfold the support plate (9) using the fourth cylinder (36). Step 5, unfold the pressure plate (10); Step 6: Inject water into the sample through the water spray hole (12); Step 7: Apply pressure step by step using a bidirectional electric actuator (11) and record the vertical displacement of the upper and lower specimens under each pressure level. Step 8: Calculate the vertical loess collapse coefficient under each pressure level.

Images