A test device for simulating natural fissures using geomembranes

Abstract

The utility model relates to a kind of test device for simulating primary fissure using geomembrane.The device includes split cylindrical mould assembly, HDPE geomembrane fissure simulation assembly and positioning adjusting assembly.Mould is constituted by upper mould cylinder, lower mould cylinder and side opening mould piece, and side opening mould piece is provided with opening groove in axial direction, and positioning pin is used to fix standardized geomembrane gasket, to realize the accurate adjustment of fissure penetration rate and inclination angle;HDPE geomembrane gasket has high strength and low deformation characteristics, and simulates the mechanical properties of non-swelling fissure;Anti-slip boss and positioning hole design ensure that fissure morphology is stable during sample preparation.The test device provided by the utility model is used to solve the technical problems of inaccurate fissure parameter control, unstable fissure surface strength and poor sample integrity in traditional test methods.

Description

Technical Field

[0001] This utility model relates to the field of experimental device technology, specifically to an experimental device that uses geomembrane to simulate native cracks. Background Technology

[0002] Fisted soil is a core component of geotechnical engineering research, and its mechanical properties directly affect the safety and durability of engineering structures. Currently, the mechanical properties of fisted soil are mainly studied through laboratory tests such as triaxial shear and unloaded creep. However, the quality of fisted soil preparation directly affects the accuracy of the test results. Specifically: 1. The simulation method is crude: it often uses blades to cut or insert into weak interlayer soil, which makes it difficult to control key parameters such as crack penetration rate and dip angle, and the batch samples have large dispersion.

[0003] 2. Unstable strength of fracture surface: The weak interlayer soil is prone to water absorption and softening, resulting in a large deviation between the mechanical properties of the fracture surface and the actual non-expansion and shrinkage fractures in the field; 3. Poor integrity: Cracks are prone to deformation and soil is prone to loosening during sample preparation. Utility Model Content

[0004] This invention provides a test device that uses geomembrane to simulate original cracks, which can achieve precise adjustment of crack penetration rate and inclination angle, ensure the strength stability of crack surface and the integrity of the sample, meet the standardization requirements of indoor geotechnical testing, and effectively improve test efficiency.

[0005] The technical solution of this utility model is as follows: A geomembrane simulation molding device containing fractured soil samples includes a sample mold assembly, a geomembrane fracture simulation assembly, and a positioning adjustment assembly; The sample mold assembly is a detachable cylindrical structure, consisting of an upper mold cylinder, a lower mold cylinder, and a side-opening mold piece; The side-opening mold piece is provided with an opening groove along the axial direction; The geomembrane crack simulation component includes at least one standardized crack pad made of HDPE geomembrane. The crack pad has a rectangular structure and anti-slip protrusions on both sides. The positioning adjustment assembly includes an inclination scale set on the outer wall of the side-opening mold piece and positioning pins set at both ends of the slit gasket. The inner wall of the opening groove of the side-opening mold piece is provided with positioning holes that are adapted to the positioning pins. The crack gasket is fixed in the opening groove by being inserted into the positioning hole by a positioning pin, so as to adjust the crack penetration rate and inclination angle.

[0006] The preferred embodiment of the test device for simulating native cracks using geomembrane is that the crack gasket is made of HDPE high-density polyethylene geomembrane with an elongation ≥1000% and a tear tension ≥900N.

[0007] The preferred embodiment of the test device for simulating native cracks in geomembranes is that the size of the sample mold assembly is adapted to the standard triaxial test sample, with a sample diameter of 61.8 mm and a height of 125 mm.

[0008] The preferred embodiment of the test device for simulating native cracks in geomembrane is that the inner walls of the upper and lower mold cylinders are provided with annular limiting grooves for fixing the side-opening mold pieces.

[0009] The preferred embodiment of the test device for simulating original cracks in geomembrane is that the thickness of the crack pad is 2mm, the length is set to 102mm, 153mm or 204mm according to the crack penetration rate requirement, corresponding to penetration rates of 33.3%, 50.0% and 66.7% respectively, and the width is 125mm, which is consistent with the height of the sample.

[0010] The preferred embodiment of the test device for simulating native cracks in a geomembrane is that the inclination scale ranges from 0° to 90°, and the positioning accuracy is ±1°; the gap between the width of the opening groove and the thickness of the membrane crack gasket is ≤0.1mm.

[0011] The preferred embodiment of the test device for simulating native cracks in geomembrane is to fix the crack inclination angle, which is generally 45°, by matching the appropriate positioning pin with the positioning holes of different angles on the crack pad. Beneficial effects

[0012] 1. Precise and controllable fracture parameters: The fracture penetration rate and inclination angle can be precisely adjusted through standardized geomembrane pads, and the consistency of batch samples is good; 2. Realistic simulation of fracture surface: HDPE geomembrane is used as the fracture surface, with stable strength parameters (cohesion ≈ 3.7 kPa, internal friction angle ≈ 9.9°), which matches the strength of the non-expansion fracture surface on site, making the simulation effect closer to reality; 3. Strong integrity of the sample: The geomembrane gasket is equipped with anti-slip protrusions, which, together with the mold, form a sealed structure to prevent the soil from becoming loose or the gasket from shifting during sample preparation, thus ensuring the integrity of the sample. 4. Convenient and efficient operation: The device has a detachable design, which facilitates the replacement of geomembrane and the removal of samples, adapts to the needs of batch sample preparation in the laboratory, and reduces the difficulty of operation. Attached Figure Description

[0013] Figure 1 An exploded view of the test setup for simulating native cracks in geomembranes; Figure 2 This is a schematic diagram of the interior of the side-opening mold piece; Figure 3 This is a schematic diagram of a geomembrane crack gasket.

[0014] Among them, 1-upper mold cylinder, 2-side opening mold piece, 3-lower mold cylinder, 4-opening groove, 5-tilt scale, 6-crack gasket, 7-positioning pin, 8-anti-slip boss. Detailed Implementation

[0015] A test apparatus for simulating native cracks using geomembrane includes a sample mold assembly, a geomembrane crack simulation assembly, and a positioning adjustment assembly; The sample mold assembly is a split cylindrical structure, consisting of an upper mold cylinder 1, a lower mold cylinder 3, and a side-opening mold piece 2; the side-opening mold piece 2 is provided with an opening groove 4 along the axial direction. The geomembrane crack simulation component includes at least one crack pad 6 made of HDPE geomembrane. The crack pad 6 has a rectangular structure and anti-slip protrusions 8 are provided on both sides of its edge. The positioning adjustment assembly includes an inclination scale 5 on the outer wall of the side-opening mold plate 2 and positioning pins 7 on both ends of the slit gasket 6. The inner wall of the opening groove 4 of the side-opening mold plate 2 is provided with positioning holes that are adapted to the positioning pins 7. The crack gasket 6 is fixed in the opening slot 4 by being inserted into the positioning hole by the positioning pin 7, so as to realize the adjustment of crack penetration rate and inclination angle.

[0016] The dimensions of the sample mold assembly are adapted to the standard triaxial test sample, with a sample diameter of 61.8 mm and a height of 125 mm.

[0017] The inner walls of both the upper mold cylinder 1 and the lower mold cylinder 3 are provided with annular limiting grooves to fix the side-opening mold piece 2 and ensure the overall sealing of the mold.

[0018] The thickness of the crack gasket 6 is 2mm, and the length is set to 102mm, 153mm or 204mm according to the crack penetration rate requirement, which correspond to penetration rates of 33.3%, 50.0% and 66.7% respectively. The width is 125mm, which is the same as the height of the sample.

[0019] The tilt angle scale 5 ranges from 0° to 90°, with a positioning accuracy of ±1°; the gap between the width of the opening groove 4 and the thickness of the slit gasket 6 is no greater than 0.1 mm.

[0020] The working process of an experimental device that uses geomembranes to simulate native fractures is as follows: Soil pretreatment: The obtained expansive soil is air-dried, crushed, and passed through a 2mm sieve. After controlling the moisture content of the soil sample according to the test requirements, it is sealed and left to stand for 24 hours for later use. 2. Mold assembly: Insert the side-opening mold piece 2 into the annular limiting groove of the upper mold cylinder 1 and the lower mold cylinder 3 to ensure the coaxiality of the mold; 3. Gasket installation: Select geomembrane crack gasket 6 with α=50.0%, insert the positioning pins 7 at both ends into the positioning holes of the side opening mold plate 2, adjust to 45° according to the tilt angle scale, and make the anti-slip boss 8 face the inside of the mold. 4. Layered compaction: Fill the mold with the pretreated soil in 3 layers, and control the number of compaction times for each layer to 93% of the compaction degree. Avoid touching the geomembrane pad during the compaction process. 5. Demolding: After the soil sample is formed, remove the upper mold 1, the side mold piece 2, and the lower mold 2 in sequence to obtain an expansive soil sample with a crack inclination angle of 45° and a penetration rate of 50%. 6. Sample curing: The sample is continuously treated with a vacuum saturation device for 24 hours to reach saturation. It can then be used for triaxial shear or creep tests.

Claims

1. A test apparatus for simulating native fractures using geomembranes, characterized in that, Includes sample mold assembly, geomembrane crack simulation assembly, and positioning adjustment assembly; The sample mold assembly is a detachable cylindrical structure, consisting of an upper mold cylinder, a lower mold cylinder, and a side-opening mold piece; The side-opening mold piece is provided with an opening groove along the axial direction; The geomembrane crack simulation component includes at least one standardized crack pad made of HDPE geomembrane. The crack pad has a rectangular structure and anti-slip protrusions on both sides. The positioning adjustment assembly includes an inclination scale set on the outer wall of the side-opening mold piece and positioning pins set at both ends of the slit gasket. The inner wall of the opening groove of the side-opening mold piece is provided with positioning holes that are adapted to the positioning pins. The crack gasket is fixed in the opening groove by inserting a positioning pin into the positioning hole, thereby realizing the adjustment of crack penetration rate and inclination angle.

2. The experimental apparatus for simulating primary fractures using geomembranes according to claim 1, characterized in that, The dimensions of the sample mold assembly are adapted to the standard triaxial test sample, with a sample diameter of 61.8 mm and a height of 125 mm.

3. The experimental apparatus for simulating primary fractures using geomembranes according to claim 1, characterized in that, The inner walls of the upper and lower mold cylinders are provided with annular limiting grooves to fix the side-opening mold pieces and ensure the overall sealing of the mold.

4. The experimental apparatus for simulating primary fractures using geomembranes according to claim 1, characterized in that, The thickness of the crack gasket is 2mm, and the length is set to 102mm, 153mm or 204mm according to the crack penetration rate requirement, corresponding to penetration rates of 33.3%, 50.0% and 66.7% respectively. The width is the same as the height of the sample, which is 125mm.

5. The experimental apparatus for simulating primary fractures using geomembranes according to claim 1, characterized in that, The tilt angle scale ranges from 0° to 90°, with a positioning accuracy of ±1°; the gap between the width of the opening groove and the thickness of the membrane slit gasket is ≤0.1mm.

6. The experimental apparatus for simulating primary fractures using geomembranes according to claim 1, characterized in that, The crack gasket is made of HDPE high-density polyethylene geomembrane with an elongation of ≥1000% and a tear tension of ≥900N.

7. The experimental apparatus for simulating primary fractures using geomembranes according to claim 1, characterized in that, By matching the appropriate locating pin with the locating holes of different angles on the crack gasket, the crack inclination angle is generally fixed at 45° by default.

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