High-pressure water injection test system and test method for similar material model

Abstract

The invention relates to the field of similar material model tests, and provides a high-pressure water injection test system and a high-pressure water injection test method for a similar material model. The high-pressure water injection test system comprises a pouring and center hole positioning device and a positioning and hole sealing device; the pouring and center hole positioning device comprises a mold, a drilling centering assembly and a drilling depth length fixing assembly. The positioning hole sealing device comprises an orifice water injection pipe, a sealing assembly and a locking piece. According to the high-pressure water injection test system for the similar material model, the problems that in the prior art, the similar material model is low in quality and poor in hole sealing effect can be effectively solved, and the high-pressure water injection test accuracy of the similar material model is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of similar material model test, in particular to a similar material model high-pressure water injection test system and test method. BACKGROUND

[0002] The similar material model test is widely used in various geotechnical engineering researches due to its simple test method, complete test means, real and reliable test data, and intuitive reproduction of engineering technology effect. The similar material model drilling high-pressure water injection test, as an important means of laboratory research on high-pressure water injection fracturing of rock strata, is related to the high-pressure water injection fracturing weakening of hard and thick roof rock strata in the process of coal mining, the high-pressure water injection fracturing stimulation in the process of oil and shale gas exploitation, and other engineering fields. In view of the engineering characteristics of drilling high-pressure water injection of rock strata, mature laboratory similar material model drilling high-pressure water injection test technology and equipment have been developed.

[0003] The laboratory uses the similar material model drilling high-pressure water injection test to study the high-pressure water injection fracturing characteristics of engineering rock mass, including the relationship between the water injection drilling diameter φ and the water injection section length L1 change, the stress environment of the rock strata, and the water injection pressure of the rock strata fracturing, which is used to determine and correct the parameter design of the rock strata high-pressure water injection fracturing construction. The similar material model drilling high-pressure water injection test follows the similar model theory, and the test system can apply mutual perpendicular X, Y, Z three-direction independent boundary stress to the similar material model. Before the test, a regular hexahedron similar material model with length A, width B, and height H is made according to the requirements of the test system, and the regular hexahedron surface corresponds to the parallel surface of the X, Y, Z three-dimensional loading system. The water injection drilling is processed on the upper surface of the model, and the orifice water injection pipe is installed in the drilling.

[0004] In the current high-pressure water injection test, the similar material model cannot well meet the test requirements (such as low drilling precision at the center, model damage, and other problems), the sealing effect is poor, and finally the test result accuracy is low. SUMMARY

[0005] The present application provides a similar material model high-pressure water injection test system to solve the problems of low quality and poor sealing effect of the similar material model in the prior art, and improve the accuracy of the similar material model high-pressure water injection test.

[0006] The present application also provides a similar material model high-pressure water injection test method.

[0007] According to the similar material model high-pressure water injection test system of the first aspect of the present application, the high-pressure water injection test system comprises a pouring and center hole positioning device and a positioning and sealing device. The pouring and center hole positioning device comprises: A mold, wherein the mold is configured to form a cavity for casting a model of a similar material, and the cavity has an opening at its upper end; A drilling centering assembly is disposed at the upper opening of the receiving cavity and has a mounting hole corresponding to the center position of the cross-section of the receiving cavity; A drilling depth fixed length assembly includes a limiting member and a drilling rod. The limiting member is connected to a preset position on the drilling rod. The limiting member is used to be installed at the mounting hole so that the lower end of the drilling rod extends into the receiving cavity, so that the similar material model formed by casting has a drilled hole in one piece. The positioning and sealing device includes: The orifice water injection pipe is configured to be partially installed in the borehole of a similar material model after casting, and partially extend out of the borehole; the orifice water injection pipe has a hollow channel for injecting water into the borehole; a limiting part is provided at the end of the orifice water injection pipe that extends into the borehole; A sealing assembly is fitted onto the outside of the orifice water injection pipe to seal the passage between the outer wall of the orifice water injection pipe and the inner wall of the borehole. A locking member is sleeved on one end of the water injection pipe at the orifice that extends out of the borehole, such that the sealing assembly is located between the locking member and the limiting part in the axial direction of the water injection pipe at the orifice; the locking member moves toward the limiting part in the axial direction of the water injection pipe at the orifice to squeeze the sealing assembly so that the sealing assembly abuts against the inner wall of the borehole.

[0008] According to one embodiment of this application, the mold includes two long-side templates, two wide-side templates, and a base plate, wherein the long-side templates, wide-side templates, and the base plate surround to form the receiving cavity; The base plate is provided with a first positioning groove that mates with the long side template and the wide side template; One of the long side template and the wide side template is provided with a second positioning slot for cooperating with the other.

[0009] According to one embodiment of this application, the drilling centering assembly includes a centering main beam and a centering secondary beam. The two ends of the centering main beam are respectively connected to the two long side templates, and the two ends of the centering secondary beam are respectively connected to the two wide side templates. The mounting holes include a first mounting hole provided on the centering main beam and a second mounting hole provided on the centering secondary beam.

[0010] According to one embodiment of this application, the drilling centering assembly further includes a centering sleeve, which passes through the first mounting hole and the second mounting hole to connect the centering main beam and the centering secondary beam; The centering sleeve forms a guide channel through which the drill rod passes.

[0011] According to one embodiment of this application, the orifice water injection pipe includes a water injection pipe body and a boss connected to one end of the water injection pipe body. An outlet communicating with the hollow channel is provided on the outer peripheral surface of the boss; the boss forms the limiting part. The borehole includes a water injection section and a sealing section connected along the depth direction. The sealing component corresponds to the sealing section. The cross-section at the middle position of the length direction of the water injection section and the cross-section at the middle position of the length direction of the boss are located in the same plane, and this plane coincides with the centerline plane in the height direction of the similar material model.

[0012] According to one embodiment of this application, the positioning and sealing device further includes a first adjusting pad assembly, which is disposed between one end of the orifice water injection pipe extending into the borehole and the bottom surface of the borehole, and both ends respectively abut against the one end of the orifice water injection pipe extending into the borehole and the bottom surface of the borehole to adjust the height of the boss.

[0013] According to one embodiment of this application, the positioning and sealing device further includes a second adjusting pad assembly, which is sleeved on the outside of the orifice water injection pipe and located between the limiting part and the sealing assembly; the second adjusting pad assembly abuts against the limiting part and the sealing assembly respectively.

[0014] According to one embodiment of this application, the length of the second adjusting pad assembly is the same as the length of the first adjusting pad assembly; The sum of the lengths of the first adjusting pad assembly, the second adjusting pad assembly, and the boss is the same as the length of the water injection section.

[0015] A high-pressure water injection test method for a similar material model according to a second aspect of this application, the high-pressure water injection test method using the aforementioned high-pressure water injection test system for a similar material model, includes: Assemble the casting and center hole positioning device, and cast a similar material model with drilled holes; A similar material model was placed on the test bench and a preload was applied; Combine the water injection pipe at the orifice with the sealing assembly and locking parts, and insert it into the drilled hole; The locking mechanism actuates to seal the passage between the outer wall of the water injection pipe at the orifice and the inner wall of the borehole. Connect the orifice water injection pipe to the high-pressure water injection pipeline; Apply boundary stress and inject water.

[0016] According to one embodiment of this application, the step of combining the orifice water injection pipe with the sealing assembly and locking member to form an assembly and inserting it into the borehole includes: The water injection pipe at the orifice is combined with the sealing component, the locking component, and the second adjusting pad component to form an assembly. The first adjusting pad component is placed at the bottom of the borehole, and then the assembly is placed into the borehole and pressed against the first adjusting pad component.

[0017] The above-described one or more technical solutions in the embodiments of this application have at least one of the following technical effects: The high-pressure water injection testing system for similar material models disclosed in this application includes a casting and center hole positioning device and a positioning and sealing device. The casting and center hole positioning device for the similar material model can form the center hole simultaneously with the casting of the similar material model, eliminating the need for transportation and processing after the model is manufactured, thus avoiding potential damage to the model during transportation and processing. The center hole's position on the similar material model is determined by a drilling centering component, and its processing depth on the model is determined by a drilling depth length fixing component, ensuring precise position and depth of the center hole and accurate subsequent test results. The positioning and sealing device is completely different from the adhesive sealing method in the existing technology. It uses a locking element to compress the sealing component, which causes the sealing component to expand radially to achieve a seal. The locking element squeezes the sealing component along the axial direction of the water injection pipe at the orifice, causing the sealing component to expand and press against the inner wall of the borehole, thereby sealing the gap between the water injection pipe at the orifice and the inner wall of the borehole. This not only has high sealing efficiency and does not require waiting for the adhesive to cure, but also has a good sealing effect, which can achieve 100MPa high-pressure water injection without leakage. Moreover, the above-mentioned rapid positioning and sealing device can be reused multiple times, which not only eliminates the problem of model scrapping, but also reduces the cost of sealing per operation.

[0018] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a structural schematic diagram of the similar material model provided in this application. Figure One (3D view).

[0021] Figure 2 This is a structural schematic diagram of the similar material model provided in this application. Figure Two (Cross-sectional view).

[0022] Figure 3This is a schematic diagram of the similar material model casting and center hole positioning device provided in this application.

[0023] Figure 4 This is a schematic diagram of the mold provided in this application.

[0024] Figure 5 This is a structural schematic diagram of the base plate provided in this application.

[0025] Figure 6 This is a structural diagram of the wide-side template provided in this application. Figure One .

[0026] Figure 7 This is a structural diagram of the wide-side template provided in this application. Figure Two .

[0027] Figure 8 This is a structural diagram of the long side template provided in this application. Figure One .

[0028] Figure 9 This is a structural diagram of the long side template provided in this application. Figure Two .

[0029] Figure 10 This is a schematic diagram of the drilling centering assembly provided in this application.

[0030] Figure 11 This is a structural schematic diagram of the centering main beam provided in this application.

[0031] Figure 12 This is a structural schematic diagram of the centering sub-beam provided in this application.

[0032] Figure 13 This is a schematic diagram of the centering sleeve provided in this application. Figure One .

[0033] Figure 14 This is a schematic diagram of the centering sleeve provided in this application. Figure Two .

[0034] Figure 15 This is a schematic diagram of the drilling depth fixed length component provided in this application.

[0035] Figure 16 This is a schematic diagram of the drill rod provided in this application.

[0036] Figure 17 This is a structural schematic diagram of the limiting component provided in this application.

[0037] Figure 18 This is a schematic diagram (three-dimensional view) of the structure of a quick-positioning sealing device installed on a similar material model provided in this application.

[0038] Figure 19 This is a schematic diagram of the structure of the rapid positioning and sealing device provided in this application. Figure One (Cross-sectional view).

[0039] Figure 20 This is a schematic diagram of the structure of the rapid positioning and sealing device provided in this application. Figure Two (Sectional view on the left).

[0040] Figure 21 This is a schematic diagram of the structure of the rapid positioning and sealing device provided in this application. Figure Three (The first adjusting pad assembly is not shown.)

[0041] Figure 22 This is a structural schematic diagram (top sectional view) of the orifice water injection pipe provided in this application.

[0042] Figure 23 This is a schematic diagram of the first adjusting pad assembly provided in this application installed in a borehole.

[0043] Figure 24 This is a schematic diagram of the structure of the adjustment pad unit provided in this application.

[0044] Figure 25 This is a structural schematic diagram of the locking component provided in this application.

[0045] Figure 26 This is a schematic diagram of the pressure equalizing pad provided in this application.

[0046] Figure 27 This is a schematic diagram of the sealing ring provided in this application.

[0047] Figure 28 This is a flowchart illustrating the high-pressure water injection test method for the similar material model provided in this application.

[0048] Figure label: 1. Mold; 11. Long side template; 111. Second positioning slot; 112. Fixing hole; 12. Wide side template; 13. Base plate; 131. First positioning slot; 14. Receiving cavity; 2. Drilling centering assembly; 21. Centering main beam; 211. First mounting hole; 212. First bend; 213. Stepped slot; 214. Guide slope; 215. Clearance area; 22. Centering secondary beam; 221. Second mounting hole; 222. Second bend; 23. Centering sleeve; 231. Guide channel; 232. First mounting boss; 233. Mounting slot; 234. Second mounting boss; 235. Clearance area 3. Hollow area; 4. Drilling depth fixed length component; 5. Limiting component; 6. First semi-circular ring; 7. Second semi-circular ring; 8. Limiting part; 9. Drilling rod; 10. Limiting slot; 11. Connecting rod; 12. Similar material model; 13. Drill hole; 14. Water injection section; 15. Sealing section; 16. Orifice water injection pipe; 17. Water injection pipe body; 18. Hollow channel; 19. Driving hole; 10. Internal threaded hole; 11. Boss; 12. Sealing component; 13. Pressure equalizing pad; 14. Locking component; 15. First adjusting pad assembly; 16. Second adjusting pad assembly; 17. Adjusting pad unit. Detailed Implementation

[0049] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this application, but should not be used to limit the scope of this application.

[0050] In the description of the embodiments of this application, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application 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. Therefore, they should not be construed as limitations on the embodiments of this application. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0051] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0052] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0053] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0054] According to an embodiment of the first aspect of this application, a high-pressure water injection testing system for a similar material model is provided. The high-pressure water injection testing system includes a casting and center hole positioning device and a positioning and sealing device. The casting and center hole positioning device includes: a mold 1 forming a cavity 14 for casting the similar material model 5, the cavity 14 having an opening at its upper end; a drilling and centering component 2, disposed at the upper opening of the cavity 14, having a mounting hole corresponding to the center position of the cross-section of the cavity 14; and a drilling depth fixing component 3, including a limiting member 31 and a drilling rod 32, the limiting member 31 being connected to a preset position on the drilling rod 32; the limiting member 31 is installed at the mounting hole so that the lower end of the drilling rod 32 extends into the cavity 14, so that the cast similar material model 5 is integrally formed. The drilling and positioning sealing device includes: a water injection pipe 6, which is partially installed in the drill hole 51 of the similar material model 5 after casting, and partially extends out of the drill hole 51; the water injection pipe 6 has a hollow channel 611 for injecting water into the drill hole 51; a limiting part is provided at the end of the water injection pipe 6 that extends into the drill hole 51; a sealing component 7, which is sleeved on the outside of the water injection pipe 6 to seal the channel between the outer wall of the water injection pipe 6 and the inner wall of the drill hole 51; a locking member 8, which is sleeved on the end of the water injection pipe 6 that extends out of the drill hole 51, so that the sealing component 7 is located between the locking member 8 and the limiting part in the axial direction of the water injection pipe 6; the locking member 8 moves towards the limiting part in the axial direction of the water injection pipe 6 to squeeze the sealing component 7 so that the sealing component 7 abuts against the inner wall of the drill hole 51.

[0055] The casting and center hole positioning device is used to form a similar material model 5 with a center hole (i.e., a drilled hole), and the positioning and sealing device is used to install the orifice water injection pipe 6 at the drilled hole 51 of the similar material model 5 and perform high-pressure sealing, thereby forming a high-pressure water injection test system for the similar material model.

[0056] The mounting hole of the drilling centering component 2 corresponds to the center position of the cross-section of the receiving cavity 14, which can determine the planar position reference of the center hole before the similar material model 5 is poured. Combined with the limiting component 31 of the drilling depth length fixing component 3 and the drilling rod 32, the limiting component 31 is connected to the preset position of the drilling rod 32 and installed at the mounting hole, which can fix the length of the lower end of the drilling rod 32 extending into the receiving cavity 14. Thus, the center hole is formed simultaneously during the pouring of the similar material model 5. There is no need to carry out transportation and secondary processing after the model is manufactured. This effectively avoids the damage caused by the large size and weight of the model during transportation, as well as the hidden damage to the model structure that may be caused during secondary processing, ensuring the integrity of the model structure and providing stable initial conditions for subsequent simulation of the actual rock stress environment.

[0057] By using the mounting hole of the drilling centering component 2 to correspond to the center of the receiving cavity 14, the position of the center hole on the similar material model 5 can be precisely controlled. This avoids the problem of misalignment of the water injection pipe caused by the positioning deviation of the center of the drilling hole 51 during traditional separate processing, ensuring that the water injection pipe is precisely connected to the center hole, reducing the risk of water injection leakage, and ensuring that the water injection pressure is transmitted in the model according to the design path. This avoids the lateral force from interfering with the real simulation of the rock fracturing process, and ensures the stability of the test system installation and operation.

[0058] The borehole 51, also known as the center hole, consists of a water injection section 511 and a sealing section 512.

[0059] The borehole depth fixing component 3, through the setting of the limiting component 31 at the preset position of the borehole rod 32, clearly defines the depth to which the borehole rod 32 extends into the receiving cavity 14, thereby accurately determining the processing depth of the center hole. This avoids the problems of uncontrolled borehole depth 51 caused by uneven equipment precision and material hardness in traditional processing, as well as the problem of non-standard bottom forming of the borehole 51. It effectively prevents substantial changes in key test parameters such as the length of the water injection section 511, the total length of the borehole 51, and the diameter of the water injection section 511, ensuring that the test parameters are consistent with the design values. This provides reliable data support for studying the relationship between the diameter of the water injection borehole, the length of the water injection section 511, and the stress environment and water injection pressure of the rock strata. It also helps to accurately determine and correct the parameter design of high-pressure water injection fracturing construction of rock strata, and improves the accuracy and reference value of the test results.

[0060] The casting and center hole positioning device can effectively solve the problems of center positioning and hole depth determination of the similar material model 5 in the high-pressure water injection fracturing test, improve the reliability of the test results, and enable the similar material model 5 to be made and the hole 51 to be processed in one step, simplifying the model making and processing technology and avoiding the risk of damage during secondary processing and handling.

[0061] The water injection pipe 6 is partially installed in the borehole 51 of the similar material model 5 and partially extends out of the borehole 51. It not only realizes the core function of injecting water into the borehole 51 through its own hollow channel 611, but also provides a stable mounting carrier for the subsequent assembly of the sealing component 7 and the locking component 8. At the same time, the limiting part at one end of its extension into the borehole 51 can provide a reliable support foundation for the sealing component 7 in the axial direction, preventing the sealing component 7 from shifting into the borehole 51 during the compression process, thus laying the foundation for the stable deformation of the sealing component 7.

[0062] The sealing method differs fundamentally from existing adhesive sealing methods. By moving the locking member 8 along the axial direction of the water injection pipe 6 at the orifice towards the limiting part, the sealing component 7 is squeezed to cause radial expansion and press against the inner wall of the drill hole 51, thereby sealing the gap between the water injection pipe 6 at the orifice and the inner wall of the drill hole 51. This sealing method eliminates the need to wait for the adhesive to cure, significantly shortening the overall time of the sealing operation. It effectively solves the technical problems of long curing time and low sealing efficiency in existing adhesive sealing methods, and significantly improves sealing efficiency.

[0063] In terms of sealing performance, this structure can achieve 100MPa high-pressure water injection without leakage. By axially compressing and causing the sealing component 7 to expand radially, the sealing component 7 can tightly fill the gap between the water injection pipe 6 at the orifice and the inner wall of the borehole 51, forming a stable sealing surface. Even under high-pressure water injection environment, it can effectively resist water flow pressure and avoid leakage. This solves the technical problem of insufficient sealing performance of some existing sealing devices under high-pressure conditions.

[0064] Because mechanical compression sealing is used instead of adhesive fixing, when the device needs to be disassembled, the compression on the sealing component 7 can be released simply by moving the locking part 8 in the opposite direction. The entire device can then be removed from the drill hole 51 without damaging the similar material model 5, so there is no problem of model scrapping. At the same time, no irreversible wear and tear occurs in any component of the device, and it can be reused multiple times for different sealing operations, which greatly reduces the material cost and model wear cost of a single sealing operation. This solves the problem of high cost caused by the inability to recycle the device and easy damage to the model in the existing adhesive sealing method.

[0065] The axial cooperation between the limiting part and the locking part 8 ensures that the sealing component 7 is always within the limited space between them, so that the compressive force on the sealing component 7 is evenly distributed, avoiding the formation of sealing dead corners due to insufficient local deformation of the sealing component 7 caused by uneven compressive force, and further ensuring the stability of the sealing effect.

[0066] According to one embodiment of this application, such as Figure 4 As shown, mold 1 includes two long-side templates 11, two wide-side templates 12, and a base plate 13. The long-side templates 11, wide-side templates 12, and base plate 13 form a receiving cavity 14. The base plate 13 is provided with a first positioning groove 131 that mates with the long-side templates 11 and wide-side templates 12. One of the long-side templates 11 and wide-side templates 12 is provided with a second positioning groove 111 that mates with the other. The following description uses the example of "the long-side template 11 being provided with a second positioning groove 111 that mates with the wide-side template 12" to illustrate the process.

[0067] The long side template 11, the wide side template 12, and the base plate 13 can all be steel plates, each with a thickness of 'a'. A first positioning groove 131 with a width of 'a' and a depth of 't' can be machined on the upper surface of the base plate 13 to mate with the long side template 11 and the wide side template 12. The first positioning groove 131 mates with the long side template 11 is a through groove. The wide side template 12 defines the model width as 'B', has a rectangular flat plate shape, a plate width of 'B+2t', and a plate height of 'H+t+T1'.

[0068] The long side template 11 serves as the fixed length and fixed height template of the model, with a template height of H+t. The inner side of the template 12 is machined with a width of a and a depth of t in the height direction, forming a second positioning slot 111. The inner side of the two parallel slots has a width of A, and the outer side of the slots is machined with bolt holes φ1 for the mold clamping bolts.

[0069] In some cases, scale marks can be set on the inner walls of the long side template 11 and the wide side template 12. The scale marks are distributed along the height direction of the template, which can intuitively display the pouring height of the material when pouring similar materials. This makes it convenient for operators to control the pouring volume and avoid material overflow due to over-pouring or under-pouring affecting the height dimension of the model, thereby further improving the dimensional accuracy of the model. At the same time, elastic sealing gaskets can be set on the inner sides of the first positioning slot 131 and the second positioning slot 111. The elastic sealing gaskets can fill the gap between the slot and the template, enhance the sealing performance of the mold 1, reduce the risk of grout leakage during the pouring process, and the elastic structure can reduce collision wear during template assembly, extending the service life of the mold 1.

[0070] According to one embodiment of this application, such as Figure 10 As shown, the drilling centering assembly 2 includes a centering main beam 21 and a centering secondary beam 22. The two ends of the centering main beam 21 are connected to two long-side templates 11, and the two ends of the centering secondary beam 22 are connected to two wide-side templates 12. The mounting holes include a first mounting hole 211 on the centering main beam 21 and a second mounting hole 221 on the centering secondary beam 22. The connection here can be an overlap.

[0071] The two ends of the centering main beam 21 overlap with the two long side templates 11, and the two ends of the centering secondary beam 22 overlap with the two wide side templates 12. This allows the positions of the centering main beam 21 and the centering secondary beam 22 to be directly associated with the long side templates 11 and wide side templates 12 of the mold 1, avoiding positional offset caused by the centering components being set independently of the mold 1. Since the two long side templates 11 and the two wide side templates 12 are components set opposite to each other in the mold 1, and their spacing corresponds to the width and length dimensions of the receiving cavity 14, when they are distributed in an intersecting manner, the mounting holes (first mounting hole 211 + second mounting hole 221) passing through them can be naturally aligned with the center of the cross-section of the receiving cavity 14. This effectively solves the problem of inaccurate center positioning when drilling holes separately in traditional machining, provides a stable position reference for the center hole, and ensures that the subsequent drilling rod 32 can be formed along the central axis when it extends into the receiving cavity 14, avoiding the offset of the water injection pipe at the hole opening.

[0072] To prevent the centering components from sinking and bending, the centering main beam 21 can be machined using small channel steel. The outer surfaces of the two long side templates 11 after mold 1 assembly serve as the centering reference in the model width direction. A centering inner groove with a length equal to the sum of the model width and the thickness of the two side templates (B+2a) is machined. A first mounting hole 211, which mates with the centering sleeve 23, is machined at the center, and internal threaded holes for mounting limit screws are machined at intervals L1-1. The centering secondary beam 22 is made of stainless steel plate with a thickness of t2-1. The outer surfaces of the two wide side templates 12 after mold 1 assembly serve as the centering reference in the model length direction. A centering inner groove with a length equal to the sum of the model length and the thickness of the two side templates (A+2a) is machined. A second mounting hole 221, which engages with the centering sleeve 23, is machined at the center, and limit screw holes are machined at intervals L2-1, the same as the interval L1-1 between the set screw mounting holes of the centering main beam 21.

[0073] According to one embodiment of this application, such as Figure 10 As shown, the drilling centering assembly 2 also includes a centering sleeve 23, which is inserted into the first mounting hole 211 and the second mounting hole 221 to connect the centering main beam 21 and the centering secondary beam 22; the centering sleeve 23 forms a guide channel 231 through which the drilling rod 32 passes.

[0074] The centering sleeve 23 is a tubular structure with variable inner and outer diameters, made of stainless steel. The outer diameter φ3-1 of the centering sleeve 23 is the same as the diameter of the first mounting hole of the centering main beam 21. The end is machined with a mounting groove 233 for mating with the centering auxiliary beam 22. The outer diameter φ3-2 of the groove is the same as the diameter of the second mounting hole of the centering auxiliary beam 22. The groove width t3-1 is slightly larger than the plate thickness of the centering auxiliary beam 22. The inner hole φ3-3 is the same as the diameter φ of the center hole (i.e., the water injection hole 51) of the similar material model 5, and matches the hole diameter requirements of the subsequent water injection section 511. The inner hole φ3-4 mates with the drilling depth fixing component 3 of the model drilling hole 51. The other end of the centering sleeve 23 is machined with a wrench mouth S.

[0075] According to one embodiment of this application, the drilling centering assembly 2 further includes a rotation limiting screw (e.g., a cylindrical head limiting screw), which passes through the centering main beam 21 and the centering secondary beam 22 to limit their relative rotation. Figure 11 In the middle, two through holes are provided on the outer side of the first mounting hole 211 for the rotation limit screw to pass through; Figure 12 In the middle, the outer side of the second mounting hole 221 is provided with two through holes for the rotation limit screw to pass through.

[0076] According to one embodiment of this application, such as Figure 13 and Figure 14 As shown, the centering sleeve 23 is provided with: a first mounting boss 232, which is used to cooperate with the first mounting hole 211 so that the centering sleeve 23 abuts and is fixed on the centering main beam 21; a mounting slot 233, which is used to cooperate with the second mounting hole 221 so that the centering secondary beam 22 is fixed at the mounting slot 233; and a second mounting boss 234, which is used to cooperate with the limiting member 31 so that the drilling rod 32 is installed on the drilling centering assembly 2.

[0077] The first mounting boss 232 on the centering sleeve 23 engages with the first mounting hole 211 of the centering main beam 21. The rigid contact between the first mounting boss 232 and the wall of the first mounting hole 211 restricts the radial movement of the centering sleeve 23. At the same time, the centering sleeve 23 is fixed to the centering main beam 21, preventing the centering sleeve 23 from sliding axially during casting vibration or the insertion of the drilling rod 32. This ensures that the centering sleeve 23 is always in the preset position connected to the centering main beam 21, providing a stable foundation for subsequent engagement with the centering secondary beam 22.

[0078] The centering sleeve 23, through three structures, cooperates with the centering main beam 21, the centering secondary beam 22, and the limiting component 31 respectively, integrating the three into a complete positioning system, thereby enhancing the overall structural rigidity of the drilling centering assembly 2.

[0079] According to one embodiment of this application, such as Figure 13 As shown, the lower end of the centering sleeve 23 is provided with a clearance area 235 so that the lower end of the centering sleeve 23 is adapted to the shape of the second mounting hole 221; the clearance area 235 is connected to the mounting slot 233 so that the centering sub-beam 22 can be inserted into the mounting slot 233 through the clearance area 235.

[0080] The clearance area 235 provided at the lower end of the centering sleeve 23 allows the lower end of the centering sleeve 23 to match the shape of the second mounting hole 221, which can avoid assembly jamming caused by the mismatch between the outline of the lower end of the centering sleeve 23 and the shape of the second mounting hole 221. This provides a smooth insertion space for the second mounting hole 221 of the centering sub-beam 22, reduces the alignment difficulty when assembling the centering sub-beam 22 and the centering sleeve 23, and is especially suitable for scenarios where there are slight dimensional deviations in the second mounting hole 221 or where the lower end of the centering sleeve 23 has machined rounded corners, thus improving assembly convenience.

[0081] According to one embodiment of this application, such as Figure 11 As shown, the centering main beam 21 is provided with first bending portions 212 at both ends. The first bending portions 212 cooperate with the side of the long side template 11 facing away from the receiving cavity 14. The first bending portion 212 includes a stepped groove 213 with a guide slope 214. The top corner of the stepped groove 213 abuts against the upper end of the long side template 11.

[0082] The first bends 212 at both ends of the centering main beam 21 engage with the side of the long side template 11 facing away from the receiving cavity 14, thus providing lateral restraint to the centering main beam 21 from the outside of the long side template 11. This prevents the centering main beam 21 from shifting during installation or pouring, ensuring that the centering main beam 21 always extends along the preset direction of the long side template 11, providing lateral positional assurance for aligning the subsequent mounting holes with the center of the receiving cavity 14. This side engagement further restricts the displacement freedom of the centering main beam 21, reducing positional shifts caused by factors such as vibration and material lateral pressure, and improving the overall installation stability of the centering assembly.

[0083] In some cases, an elastic buffer layer can be provided on the inner wall of the stepped groove 213. The elastic buffer layer is made of a wear-resistant and elastic material. When the long side template 11 is fitted with the stepped groove 213, the elastic buffer layer can fill the tiny gap between them, enhancing the tightness of the fit. At the same time, it can absorb the impact force generated by material vibration during the pouring process, reducing the impact of vibration on the position of the centering main beam 21 and further improving the centering accuracy. In addition, the elastic buffer layer can also avoid hard contact wear between the stepped groove 213 and the long side template 11, extending the service life of the first bend 212 and the long side template 11.

[0084] According to one embodiment of this application, such as Figure 11 As shown, a clearance area 215 is also provided on the centering main beam 21. The clearance area 215 is configured to create a first gap between the main body of the centering main beam 21 and the upper opening of the receiving cavity 14.

[0085] The clearance zone 215 provided on the centering main beam 21 creates a first gap between the main body of the main beam and the upper opening of the receiving cavity 14. This gap allows for a physical separation between the upper surface of the similar material model 5 and the drilling centering component 2 after cement mortar is poured into the receiving cavity 14, thus spatially preventing the uncured cement mortar from directly contacting the centering main beam 21. When the uncured model is vibrated (to remove air bubbles inside the mortar and increase the density of the model), even if the mortar shakes or splashes slightly due to vibration, it will not touch the centering main beam 21 due to the existence of the first gap, thereby effectively preventing the cement mortar from adhering to the drilling centering component 2.

[0086] In practical applications, the centering main beam 21 and the centering secondary beam 22 can be positioned such that the centering main beam 21 is on top and the centering secondary beam 22 is on the bottom (e.g., ...). Figure 10 As shown), the centering sub-beam 22 can also be on top and the centering main beam 21 on the bottom. When the centering sub-beam 22 is on top and the centering main beam 21 is on the bottom, the first gap can ensure that the distance between the centering sub-beam 22 and the upper opening of the receiving cavity 14 is greater. When the centering main beam 21 is on top and the centering sub-beam 22 is on the bottom, the distance between the centering sub-beam 22 and the upper opening of the receiving cavity 14 is less than the first gap. At this time, a certain distance should still be maintained between the centering sub-beam 22 and the upper opening of the receiving cavity 14 to avoid the centering sub-beam 22 from contacting the cement mortar.

[0087] According to one embodiment of this application, such as Figure 4 As shown, the mold 1 also includes a connecting rod 4; a fixing hole 112 is provided on the long side template 11; the two ends of the connecting rod 4 are respectively connected to the fixing holes 112 of the two long side templates 11 to clamp the long side template 11, the position of the wide side template 12 is constrained by the bottom plate slot (first positioning slot 131) and the long side template slot (second positioning slot 111) to limit the tilt of the wide side template 12, and the position of the long side template 11 is constrained by the bottom plate slot (first positioning slot 131), the width of the wide side template and the connecting rod 4 to limit the tilt of the long side template 11.

[0088] The connecting rod 4 can be a double-ended bolt, with nuts at both ends, and an elastic washer can be set between the nut and the long side template 11.

[0089] According to one embodiment of this application, such as Figure 15 and Figure 16 As shown, the drilling rod 32 is provided with multiple limiting slots 321 along its own length direction. One of the multiple limiting slots 321 cooperates with the limiting member 31 to adjust the length of the lower end of the drilling rod 32 extending into the receiving cavity 14.

[0090] The pre-drilled rod 32 is a threaded rod structure made of stainless steel. One pre-drilled rod 32 can be used for pre-drilling a set of models at different depths. One end of the rod is machined with external threads, and the outer diameter of the other end is the same as the pre-drilled end diameter φ of the model. Multiple limiting slots 321 are machined on the surface of the rod corresponding to the changes in hole depth. These limiting slots 321 serve as hole depth positioning slots. The distribution of the limiting slots 321 is determined by the changes in the drilling depth of the model and the centering component installation structure. That is, the length of each limiting slot 321 from the end of the pre-drilled rod 32 should be different from the drilling depth, and the diameter of the limiting slot 321 is slightly smaller than the diameter of the rod end.

[0091] In some cases, depth markers can be installed next to each limiting slot 321. These markers indicate the length of the lower end of the corresponding drill rod 32 extending into the receiving cavity 14. Operators can quickly identify and select the desired slot without additional measurement, avoiding depth deviations due to incorrect slot selection and further improving operational convenience and adjustment accuracy. Simultaneously, the depth markers can be laser-engraved or printed with wear-resistant ink to ensure they remain clearly legible even after long-term use, preventing operational errors caused by marker wear and extending the service life of the drill rod 32.

[0092] According to one embodiment of this application, such as Figure 17 As shown, the limiting member 31 includes a first semicircular ring 311 and a second semicircular ring 312. Both the first semicircular ring 311 and the second semicircular ring 312 are provided with limiting parts 313 that cooperate with the limiting slot 321. The first semicircular ring 311 and the second semicircular ring 312 are fastened together to form an annular structure, so as to be sleeved on the drilling rod 32.

[0093] The limiting component 31 can be in the form of a positioning retaining ring, made of stainless steel, and is a variable inner diameter semi-circular ring structure. The structural dimensions of the positioning retaining ring match those of the centering sleeve 23 and the pre-drilled rod 32. The outer diameter of the positioning retaining ring is the same as the inner hole φ3-4 of the centering sleeve 23. The inner hole boss of the positioning retaining ring (i.e., the limiting part 313) corresponds to the limiting groove 321 of the pre-drilled rod 32. After being machined as a whole ring, the positioning retaining ring is split into two parts along the diameter centerline.

[0094] According to one embodiment of this application, such as Figure 15 As shown, the drilling depth fixed length assembly 3 also includes a nut disposed on the upper end of the drilling rod 32, and the upper end of the drilling rod 32 is provided with an external thread that mates with the nut; the nut is installed on the upper end of the drilling rod 32 to drive the drilling rod 32 to rotate.

[0095] The upper end of the drill rod 32 is threaded into a nut. Before the similar material model 5 hardens, the operator can rotate the nut to periodically rotate the drill rod 32, continuously disrupting the contact interface between the outer circumference of the drill rod 32 and the uncured cement mortar, thus preventing them from forming a strong bond during the curing process. The cement mortar commonly used in the similar material model 5 gradually develops adhesion to the solid surface it contacts during the curing stage. If the drill rod 32 hardens into the model, removing it later can easily lead to cracks, missing corners, or deformation of the central hole inside the model, damaging the structural integrity and affecting the accuracy of subsequent high-pressure water injection tests. Periodically rotating the drill rod 32 fundamentally avoids this problem, ensuring the model's forming quality and the regularity of the central hole.

[0096] The casting and center hole positioning device has several advantages: 1) It accurately positions the drilling center of the similar material model 5, avoiding the impact of drilling center deviation on the installation of the test system. 2) The drilling depth and diameter are controlled by the machined drilling depth length-fixing component 3. The drilling depth, length and position of the water injection section 511 can be accurately positioned. Moreover, a set of similar material model casting and center hole positioning devices is used for a group of tests, resulting in high consistency and accuracy of test conditions and significantly improving the reliability of test data. 3) Drilling is completed during the fabrication of the similar material model 5, eliminating the need for separate drilling operations, effectively preventing damage caused by repeated model handling, and shortening preparation time. 4) It can be widely applied to the preparation process of similar material models 5, such as drilling for water injection and drilling for grouting.

[0097] According to one embodiment of this application, such as Figure 18 to Figure 20 As shown, the orifice water injection pipe 6 includes a water injection pipe body 61 and a boss 62 connected to one end of the water injection pipe body 61. An outlet communicating with the hollow channel 611 is provided on the outer peripheral surface of the boss 62. The boss 62 forms a limiting part. The borehole 51 includes a water injection section 511 and a sealing section 512 connected along the depth direction of the hole. The sealing component 7 corresponds to the sealing section 512. The cross-section at the middle position of the length direction of the water injection section 511 and the cross-section at the middle position of the length direction of the boss 62 are located in the same plane, and this plane coincides with the centerline plane in the height direction of the similar material model 5, ensuring that the horizontal boundary stress conditions of the same group of tests with different lengths of water injection sections change in a consistent manner.

[0098] The rapid positioning and sealing device of this application can accurately locate the sealing position, so that the water injection section 511 is symmetrically distributed on both sides of the model height centerline, ensuring that the stress conditions of a set of test horizontal boundary are consistent for different water injection section lengths; accurately defining the length of the water injection section, the obtained relationship between the length of the water injection section and the water injection pressure is more accurate.

[0099] The boss 62 forms a limiting part, enabling it to simultaneously serve the dual functions of axially supporting the sealing assembly 7 and bearing the water outlet. This eliminates the need for an additional independent limiting structure on the orifice water injection pipe 6, reducing the processing and assembly steps of the components, simplifying the overall structure of the orifice water injection pipe 6, and lowering processing and assembly costs. Simultaneously, as a limiting part, the boss 62 is integrated with the main body 61 of the water injection pipe, resulting in higher structural strength. When the locking member 8 compresses the sealing assembly 7, it provides stable axial support for the sealing assembly 7, preventing it from shifting into the borehole 51. This ensures that the deformation of the sealing assembly 7 is concentrated in the radial direction, laying the foundation for the sealing assembly 7 to tightly press against the inner wall of the borehole 51. This solves the technical problem of insufficient connection strength between the existing independent limiting structure and the water injection pipe, and the tendency to loosen during compression.

[0100] According to one embodiment of this application, such as Figure 20 As shown, the rapid positioning and sealing device also includes a first adjusting pad assembly 81. The first adjusting pad assembly 81 is disposed between one end of the water injection pipe 6 extending into the borehole 51 and the bottom surface of the borehole 51, and both ends abut against the one end of the water injection pipe 6 extending into the borehole 51 and the bottom surface of the borehole 51, respectively, to adjust the height of the boss 62 and limit the depth of the water injection pipe 6 extending into the borehole 51, so that the cross-section at the middle position of the length direction of the boss 62 and the cross-section at the middle position of the length direction of the water injection section 511 are located on the same plane, thereby realizing rapid depth positioning of the water injection pipe 6.

[0101] The first adjusting pad assembly 81 has two ends that are respectively connected to the end of the water injection pipe 6 that extends into the borehole 51 and the bottom surface of the borehole 51. It can directly support and adjust the axial position of the water injection pipe 6 in the borehole 51. By changing its own length, the height of the boss 62 can be precisely adjusted to ensure that the cross-section of the middle position of the boss 62 in the length direction is always aligned with the cross-section of the middle position of the water injection section 511 in the length direction.

[0102] According to one embodiment of this application, such as Figure 20 and Figure 21 As shown, the quick positioning and sealing device also includes a second adjusting pad assembly 82, which is sleeved on the outside of the orifice water injection pipe 6 and located between the limiting part and the sealing assembly 7; the second adjusting pad assembly 82 abuts against the limiting part and the sealing assembly 7 respectively.

[0103] The second adjusting pad assembly 82 is fitted outside the orifice water injection pipe 6 and located between the limiting part and the sealing assembly 7. Its length can be adjusted to flexibly change the axial installation position of the sealing assembly 7 on the orifice water injection pipe 6. By replacing the second adjusting pad assembly 82 with different lengths (e.g., adjusting the number of adjusting pad units 83), the same set of orifice water injection pipe 6, limiting part, and locking part 8 can be adapted to sealing assemblies 7 of different specifications. This eliminates the need to customize corresponding limiting parts or orifice water injection pipes 6 for different sealing assemblies 7, reducing the cost of replacing parts and inventory pressure. Furthermore, the second adjusting pad assembly 82 has a simple structure and is easy to manufacture. Compared to adjusting the structure of the limiting part or orifice water injection pipe 6, it is more convenient to operate, can quickly respond to sealing requirements in different test scenarios, and improves the overall adaptability and flexibility of the device.

[0104] According to one embodiment of this application, such as Figure 20 As shown, the length of the second adjusting pad assembly 82 is the same as the length of the first adjusting pad assembly 81; the sum of the lengths of the first adjusting pad assembly 81, the second adjusting pad assembly 82, and the boss 62 is the same as the length of the water injection section 511.

[0105] The second adjusting pad assembly 82 is the same length as the first adjusting pad assembly 81, allowing them to be combined using adjusting units of the same specifications (such as adjusting pad units 83 of the same length). This eliminates the need to design and manufacture adjusting units of different lengths for the two adjusting pad assemblies separately, reducing mold development and parts inventory costs. Furthermore, when the adjusting device is adapted to drilled holes 51 of different depths, only the number of adjusting units in the first adjusting pad assembly 81 and the second adjusting pad assembly 82 needs to be increased or decreased synchronously to ensure that their lengths remain consistent. This eliminates the need to calculate or adjust the lengths of the two components separately, preventing mismatches due to operational errors and further improving operational convenience. It also solves the complex technical problem of requiring separate design and adjustment of different adjusting pad assemblies in existing technologies.

[0106] According to one embodiment of this application, both the first adjusting pad assembly 81 and the second adjusting pad assembly 82 include one or more adjusting pad units 83, and the lengths of the first adjusting pad assembly 81 and the second adjusting pad assembly 82 are adjusted by changing the number of adjusting pad units 83. The structure of the adjusting pad unit 83 is as follows: Figure 24 As shown.

[0107] Both the first adjusting pad assembly 81 and the second adjusting pad assembly 82 adopt a combination structure of "one or more adjusting pad units 83". The overall length can be adjusted by increasing or decreasing the number of adjusting pad units 83, allowing the two assemblies to flexibly adapt to boreholes 51 of different depths or sealing assemblies 7 of different specifications. When the depth of the borehole 51 increases, the number of adjusting pad units 83 in the first adjusting pad assembly 81 can be increased to raise the height of the water injection pipe 6 at the orifice, while the number of adjusting pad units 83 in the second adjusting pad assembly 82 can be increased simultaneously to adjust the position of the sealing assembly 7. When the depth of the borehole 51 decreases, the number of adjusting pad units 83 in both assemblies can be reduced accordingly. There is no need to design an integral adjusting pad assembly separately for each size requirement, which effectively solves the technical problem of the existing integral adjusting pad assembly of "one pad per hole" and poor adaptability, and greatly improves the adaptability range of the device to different test scenarios.

[0108] According to one embodiment of this application, such as Figure 25 As shown, the locking component 8 is a locking nut, and the end of the water injection pipe 6 extending out of the drill hole 51 is provided with an external thread that mates with the locking nut. The locking nut is rotated to adjust the distance between the locking nut and the limiting part.

[0109] The locking component 8 uses a locking nut, and the end of the water injection pipe 6 extending from the drill hole 51 is provided with an external thread that mates with the locking nut. The axial distance can be precisely adjusted by rotating the locking nut. Since the thread has a fixed pitch, the distance the locking nut moves axially along the water injection pipe 6 can be precisely controlled with each rotation. This ensures that the pressure exerted by the locking nut on the sealing component 7 remains stable and controllable, preventing excessive deformation or even damage to the sealing component 7 due to excessive pressure, or insufficient expansion and sealing effect due to insufficient pressure. This effectively solves the technical problem of difficulty in precisely controlling the pressure in existing non-threaded locking structures (such as snap-fit ​​and pin-type locks).

[0110] According to one embodiment of this application, such as Figure 22 As shown, the end of the water injection pipe 6 extending from the drill hole 51 is provided with a drive hole 612. The drive hole 612 is used to cooperate with the drive component to restrict the rotation of the water injection pipe 6. The drive hole 612 can be an internal hexagonal hole, and the drive component can be an internal hexagonal wrench.

[0111] A drive hole 612 is provided at one end of the water injection pipe 6 extending from the drill hole 51. The rotation of the water injection pipe 6 is restricted by the cooperation between the drive component and the drive hole 612, providing a stable basis for adjusting the locking nut. When the locking nut is rotated to compress the sealing assembly 7, if the water injection pipe 6 rotates synchronously with the locking nut, the locking nut will not be able to move axially, thus failing to effectively compress the sealing assembly 7. However, the cooperation between the drive hole 612 and the drive component can adjust the circumferential position of the water injection pipe 6, ensuring that the locking nut only moves axially when rotated, thus successfully completing the compression action on the sealing assembly 7.

[0112] According to one embodiment of this application, such as Figure 22 As shown, the end of the water injection pipe 6 extending out of the borehole 51 is also provided with an internal threaded hole 613, which is used to cooperate with the water pipe of the water injection device; the upper end of the hollow channel 611 forms a drive hole 612 and an internal threaded hole 613, and the internal threaded hole 613 is located on the side of the drive hole 612 away from the bottom of the borehole 51.

[0113] The water injection pipe 6 extends out of the drill hole 51 and is provided with an internal threaded hole 613. It cooperates with the water pipe of the water injection device. The threaded connection forms a stable sealing and fixing structure, which can effectively resist the water pressure during high-pressure water injection, prevent water leakage from the connection, and ensure that the water flow is stably transmitted to the hollow channel 611 during the water injection process, thus ensuring the continuity of the high-pressure water injection test.

[0114] The upper end of the hollow channel 611 forms both a drive hole 612 and an internal threaded hole 613, integrating the circumferential limiting function (drive hole 612) and the water injection connection function (internal threaded hole 613) into the same channel end. This eliminates the need for additional independent installation structures on the outer circumferential surface or other areas of the orifice water injection pipe 6, simplifying the overall structural design of the orifice water injection pipe 6, reducing processing steps (such as avoiding additional drilling 51 and milling grooves), and lowering production and manufacturing costs.

[0115] According to one embodiment of this application, such as Figure 21 As shown, the sealing assembly 7 includes multiple sealing rings 71, which are arranged sequentially along the axial direction of the orifice water injection pipe 6. The sealing assembly 7 also includes multiple pressure equalizing pads 72, which are sleeved on the outside of the orifice water injection pipe 6; pressure equalizing pads 72 are provided between adjacent sealing rings 71, and / or, pressure equalizing pads 72 are provided between sealing rings 71 and locking members 8, and / or, pressure equalizing pads 72 are provided between sealing rings 71 and the second adjusting pad assembly 82.

[0116] The sealing assembly 7 adopts a structure in which multiple sealing rings 71 are arranged sequentially along the axial direction of the water injection pipe 6 at the orifice, forming multiple independent sealing surfaces. Even if one of the sealing rings 71 experiences slight leakage due to wear or small gaps, the remaining sealing rings 71 can still maintain the sealing effect, greatly improving the overall sealing reliability and avoiding the technical problem of insufficient sealing performance of a single sealing ring 71 in high-pressure water injection or uneven inner wall of the drill hole 51.

[0117] The rapid positioning and sealing device provided in this application embodiment can effectively solve the problems of unstable sealing quality and difficulty in controlling the length and position of the water injection section 511 in the high-pressure water injection fracturing test of borehole 51 of similar material model 5, ensuring sealing quality, accurately limiting the length of the water injection section 511 in the borehole, and improving the accuracy of test results. Specifically, it can include the following advantages: 1) Accurately positioning the sealing position and limiting the length of the water injection section 511, resulting in high reliability of test results. By using the adjusting pad in conjunction with the orifice water injection pipe 6, it is suitable for controlling different water injection sections 511 in a set of tests. 2) High sealing quality and high reliability, capable of meeting the requirement of 100MPa high-pressure water injection without leakage. The sealing is achieved by utilizing the compression and expansion deformation characteristics of the elastic sealing sleeve. The deformation of the sealing sleeve forms a high squeezing force on the borehole wall and the water injection pipe, effectively eliminating gaps and preventing high-pressure water leakage. To improve the sealing performance between the sealing sleeve and the borehole wall, the sealing section 512 can be coated with grease or silicone sealant before the orifice water injection pipe 6 and the sealing device assembly are inserted into the borehole 51. 3) Significantly shortening the test preparation time. The rapid positioning and sealing device is installed on-site during testing, reducing the preparation time for adhesive sealing and curing. 4) It consumes less material and has a lower cost; the test success rate is high, avoiding model scrapping due to sealing quality problems. It is reusable; one set of rapid positioning and sealing devices can be used for water injection tests on models with the same borehole diameter and specifications. If leakage occurs at the borehole opening, the system can be removed and the borehole resealed without affecting the test results. 5) It is suitable for laboratory tests of various liquid materials. It can be applied to laboratory tests simulating high-pressure water injection fracturing and grouting reinforcement of rock formations, as well as different types of grout injection tests.

[0118] The following examples illustrate the relevant dimensions and operation of the rapid positioning and sealing device.

[0119] The orifice water injection pipe 6 is a hollow pipe with varying outer diameters D11 and D12, and a central through hole with a diameter of d11. The diameter D11 of the boss 62 is 4-6 mm smaller than the diameter φ of the model water injection borehole 51, and the length L11 of the boss 62 is the same as the length of the minimum water injection section 511 in the same group of tests. On the circumferential surface of the centerline of the boss 62 with a length L11, a set of radial through holes with a diameter of d12 are machined along the orifice water injection pipe 6, connecting to the central hole d11. The diameter D12 of the water injection pipe is 3-5 mm smaller than the diameter D11 of the boss 62. The end of the diameter D12 is machined with internal threads M1 and external threads M11. The internal thread M1 is consistent with the connection thread of the high-pressure water injection pipeline of the test system, and the bottom of the internal thread is machined with an internal hexagonal wrench head with a width S across the flats. The total length L01 of the orifice water injection pipe 6 is determined by the exposed length L0 of the drilled hole 51 required for the installation and connection of the water injection pipeline, the height H of the similar material model 5, and the minimum length L11 of the water injection section 511 in the same group of tests (the minimum height of the water injection section 511 is the length of the boss 62). L01 = L0 + H / 2 + L11 / 2. The orifice water injection pipe 6 is made of stainless steel and tempered to improve its toughness.

[0120] A rapid positioning and sealing device uses an adjusting pad in conjunction with the orifice water injection pipe 6 to adjust the length L1 of the water injection section 511 and accurately position the sealing hole, meeting the length requirements of different water injection sections 511. The adjusting pad is made of stainless steel and consists of a set of short cylindrical pipes of different lengths. The length L21 of the adjusting pad is determined according to the variation of the length L1 of the water injection section 511 and the minimum length L11 of the water injection section 511. The length of the water injection section 511 can be adjusted by selecting adjusting pads of different lengths. The designed adjusting pad lengths should be used in pairs within a water injection section 511 to limit and fix the installation position of the orifice water injection pipe 6 relative to the model height. The outer diameter of the adjusting pad is the same as the diameter D11 of the boss 62 of the orifice water injection pipe 6, and the diameter of the center hole of the adjusting pad is the same as the outer diameter D12 of the orifice water injection pipe 6. Radial through holes are machined along the circumference of the center line of the adjusting pad and connect to the center hole.

[0121] The elastic sealing sleeve (i.e., sealing ring 71) is made of nitrile rubber or polytetrafluoroethylene and is a cylindrical tube. The outer diameter of the elastic sealing sleeve is 0.5 to 1.0 mm smaller than the diameter φ of the water injection borehole 51, and the inner diameter of the elastic sealing sleeve is the same as the diameter D12 of the water injection pipe 6 at the orifice. To avoid uneven deformation of the elastic sealing sleeve, multiple elastic sealing sleeves are used to seal the hole in combination. The length of the elastic sealing sleeve is 20 to 30 mm, and the actual length of the sealing sleeve is determined based on the length variation of the sealing section 512 in the same group of tests.

[0122] The high-pressure water injection rapid positioning and sealing device in the similar material model 5 seals the hole by tightening the locking nut at the end of the water injection pipe 6 at the orifice. This causes the elastic sealing sleeve to deform radially after axial compression. To prevent the elastic sealing sleeve from twisting due to friction, reduce friction on the end face of the sealing sleeve, and ensure uniform compression force, pressure equalizing pads 72 are installed between the elastic sealing sleeves and at both ends of the sealing section 512. The pressure equalizing pads 72 are smooth, thin-plate circular structures made of stainless steel and hardened to improve rigidity. The pressure equalizing pads 72 are 2mm thick, and their outer diameter is the same as that of the elastic sealing sleeves. The diameter of the central hole of the pressure equalizing pads 72 is the same as the outer diameter D12 of the water injection pipe 6 at the orifice.

[0123] The locking nut is a flange nut made of stainless steel. The flange outer diameter of the nut is the same as the outer diameter of the equalizing gasket 72, and the thread specification matches the external thread at the end of the orifice water injection pipe 6.

[0124] A high-pressure water injection test method for a similar material model according to an embodiment of the second aspect of this application, such as Figure 28 As shown, the high-pressure water injection test method uses the aforementioned high-pressure water injection test system based on a similar material model, including: Assemble the casting and center hole positioning device, and cast a similar material model with drilled holes; A similar material model was placed on the test bench and a preload was applied; Combine the water injection pipe at the orifice with the sealing assembly and locking parts, and insert it into the drilled hole; The locking mechanism actuates to seal the passage between the outer wall of the water injection pipe at the orifice and the inner wall of the borehole. Connect the orifice water injection pipe to the high-pressure water injection pipeline; Add a Z-axis top loading plate to apply triaxial boundary stress; Add water.

[0125] According to one embodiment of this application, the step of combining the orifice water injection pipe with the sealing assembly and locking member to form an assembly and inserting it into the borehole includes: The water injection pipe at the orifice is combined with the sealing component, the locking component, and the second adjusting pad component to form an assembly. The first adjusting pad component is placed at the bottom of the borehole, and then the assembly is placed into the borehole and pressed against the first adjusting pad component.

[0126] Specifically, the high-pressure water injection test method for similar material models can include the following detailed steps: 1) Mold Assembly. During mold assembly, the length A and height H of the model are determined by the long side template, and the width B of the model is determined by the wide side template. The long side template is inserted into the long side through slot of the base plate 13, and then the wide side template is inserted into the wide side slot and the long side template slot of the base plate 13. After that, double-ended bolts are inserted into both ends of the long side template, elastic washers are installed, and nuts are tightened. The assembly of the similar material model mold is completed, and the height difference T1 between the long side template and the wide side template is achieved.

[0127] 2) Centering component assembly. The centering main beam and centering secondary beam are stacked together with their slots facing the same direction. The centering sleeve is inserted into the center hole. The angle of the centering main beam and centering secondary beam is adjusted to be perpendicular. The centering sleeve is rotated so that the centering secondary beam enters the mounting slot 233 (i.e., t3-1) at the small diameter end of the centering sleeve. The cylindrical head limit screw is screwed into the limit screw hole of the centering main beam so that the cylindrical end of the screw falls into the limit screw hole of the centering secondary beam. The centering component assembly is completed. After assembly, the depth T2 from the positioning surface of the main beam slot to the bottom surface of the secondary beam slot is greater than the height difference T1 between the long side template and the wide side template.

[0128] 3) Assembly of the drilling depth fixed length component. Screw the double nuts into the threaded end of the prefabricated drilling rod. Determine the corresponding positioning slot on the prefabricated drilling rod according to the drilling depth of the model. Position the small hole end of the positioning ring toward the prefabricated drilling end of the drilling rod 32. Attach the two parts to the same positioning slot on the prefabricated drilling rod. The drilling depth fixed length component assembly is now complete.

[0129] 4) Assembly of the model drilling and positioning device. Level and assemble the mold, then install the centering assembly, and finally install the drilling depth fixing assembly. Secure the centering inner groove (B+2a) of the main centering beam to the outside of the two long side templates of the mold, and secure the positioning inner groove (A+2a) of the secondary centering beam to the outside of the two wide side templates of the mold, ensuring the bottom surface of the main beam's centering inner groove coincides with the top surface of the two long side templates. Then, insert the drilling depth fixing assembly into the center hole of the centering sleeve of the centering beam assembly, ensuring the bottom end face of the positioning ring coincides with the bottom end face of the centering sleeve's inner hole. Assembly is now complete.

[0130] 5) Simultaneous fabrication of the similar material model and drilling. After the similar material model is cast and the central hole positioning device is assembled, the model is fabricated and cured according to normal procedures. Before the model solidifies, the pre-drilled rod is rotated intermittently using the nut installed on the top of the pre-drilled rod to prevent it from sticking to the model during solidification. After the model has completely solidified and reached a certain strength, the pre-drilled rod is removed, and water is injected to form the hole. After the model has cured to the required test strength, the drilling and water injection fracturing test is carried out directly.

[0131] 6) Install the model and apply boundary constraints. Before the test, place the similar material model on the bottom loading plate in the Z direction of the test bench, and install the loading plates in the X and Y directions on the sides of the model. Start the test system and apply boundary surface stresses of 0.5–1.0 MPa in the X and Y directions to clamp the model and prevent it from cracking during the sealing process.

[0132] 7) Installation and positioning of the bottom adjusting pad in the water injection section. Based on the length of the water injection section L1 and the length of the water injection pipe boss at the borehole (minimum length of the water injection section) L11, determine the length of the bottom adjusting pad in the water injection section L1d, L1d = (L1 - L11) / 2. Select adjusting pads with a thickness of L1d and assemble them into the borehole to position the insertion depth of the water injection pipe at the borehole opening.

[0133] 8) Orifice water injection pipe and sealing device assembly. First, an adjusting shim of the same specification and quantity as the one inside the orifice is fitted onto the threaded end of the orifice water injection pipe. The bottom boss of the orifice water injection pipe and the adjusting shim form a water injection section of length L1d+L11. Then, pressure equalizing shims and elastic sealing sleeves are fitted at intervals until the sealing sleeve is close to the middle of the thread length. Finally, one more pressure equalizing shim is added, and a lock nut is screwed in to form the orifice water injection pipe and sealing device assembly.

[0134] 9) Positioning and sealing the water injection section length L1. Insert the water injection pipe and sealing device assembly into the water injection borehole, ensuring the bottom surface of the water injection pipe contacts the adjusting pad inside the hole. Insert the wrench into the internal hexagonal wrench slot S of the water injection pipe to restrict its rotation and press the adjusting pad inside the hole. Tighten the locking nut to compress the elastic sealing sleeve. Once the sealing sleeve completely presses against the hole wall and grips the outer wall of the water injection pipe, the sealing is complete. A sealed water injection section with a total length L1 is formed at the bottom of the hole. The center of the radial water outlet of the water injection pipe boss is located on the midline plane of the model height, and the water injection sections are symmetrically distributed on the upper and lower sides of the midline plane of the model height.

[0135] 10) Cover the top loading plate in the Z direction, place the pressure plate on top of the water injection pipe at the orifice, and screw the hollow limit nut into the threaded hole of the top loading plate in the Z direction to fit the pressure plate. The high-pressure water injection pipeline of the test system is connected to the threaded connection of the water injection pipe at the orifice, and the high-pressure water injection test system is formed.

[0136] During the test, after the boundary stress was applied, the water injected by the water injection system entered the central hole of the orifice water injection pipe and the bottom adjusting pad, and was introduced into the borehole water injection section L1 through the radial connecting hole on the cylindrical surface.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate this application and are not intended to limit this application. Although this application has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of this application do not depart from the spirit and scope of the technical solutions of this application and should be covered within the scope of the claims of this application.

Claims

1. A high-pressure water injection test system based on a similar material model, characterized in that, Includes a casting and center hole positioning device and a positioning and sealing device; The casting and center hole positioning device includes: A mold, wherein the mold is configured to form a cavity for casting a model of a similar material, and the cavity has an opening at its upper end; A drilling centering assembly is disposed at the upper opening of the receiving cavity and has a mounting hole corresponding to the center position of the cross-section of the receiving cavity; A drilling depth fixed length assembly includes a limiting member and a drilling rod. The limiting member is connected to a preset position on the drilling rod. The limiting member is used to be installed at the mounting hole so that the lower end of the drilling rod extends into the receiving cavity, so that the similar material model formed by casting has a drilled hole in one piece. The positioning and sealing device includes: The orifice water injection pipe is configured to be partially installed in the borehole of a similar material model after casting, and partially extend out of the borehole; the orifice water injection pipe has a hollow channel for injecting water into the borehole; a limiting part is provided at the end of the orifice water injection pipe that extends into the borehole; A sealing assembly is fitted onto the outside of the orifice water injection pipe to seal the passage between the outer wall of the orifice water injection pipe and the inner wall of the borehole. A locking member is sleeved on one end of the water injection pipe at the orifice that extends out of the borehole, such that the sealing assembly is located between the locking member and the limiting part in the axial direction of the water injection pipe at the orifice; the locking member moves toward the limiting part in the axial direction of the water injection pipe at the orifice to squeeze the sealing assembly so that the sealing assembly abuts against the inner wall of the borehole.

2. The high-pressure water injection test system for similar material models according to claim 1, characterized in that, The mold includes two long-side templates, two wide-side templates, and a base plate, which together form the receiving cavity. The base plate is provided with a first positioning groove that mates with the long side template and the wide side template; One of the long side template and the wide side template is provided with a second positioning slot for cooperating with the other.

3. The high-pressure water injection test system for similar material models according to claim 2, characterized in that, The drilling centering assembly includes a centering main beam and a centering secondary beam. The two ends of the centering main beam are respectively connected to the two long side templates, and the two ends of the centering secondary beam are respectively connected to the two wide side templates. The mounting holes include a first mounting hole provided on the centering main beam and a second mounting hole provided on the centering secondary beam.

4. The high-pressure water injection test system for similar material models according to claim 3, characterized in that, The drilling centering assembly also includes a centering sleeve, which passes through the first mounting hole and the second mounting hole to connect the centering main beam and the centering secondary beam; The centering sleeve forms a guide channel through which the drill rod passes.

5. The high-pressure water injection test system for similar material models according to claim 1, characterized in that, The orifice water injection pipe includes a water injection pipe body and a boss connected to one end of the water injection pipe body. The outer peripheral surface of the boss is provided with a water outlet communicating with the hollow channel; the boss forms the limiting part. The borehole includes a water injection section and a sealing section connected along the depth direction. The sealing component corresponds to the sealing section. The cross-section at the middle position of the length direction of the water injection section and the cross-section at the middle position of the length direction of the boss are located in the same plane, and this plane coincides with the centerline plane in the height direction of the similar material model.

6. The high-pressure water injection test system for similar material models according to claim 5, characterized in that, The positioning and sealing device further includes a first adjusting pad assembly, which is disposed between one end of the water injection pipe extending into the borehole and the bottom surface of the borehole, and its two ends respectively abut against the one end of the water injection pipe extending into the borehole and the bottom surface of the borehole to adjust the height of the boss.

7. The high-pressure water injection test system for similar material models according to claim 6, characterized in that, The positioning and sealing device further includes a second adjusting pad assembly, which is sleeved on the outside of the water injection pipe at the orifice and located between the limiting part and the sealing assembly; the second adjusting pad assembly abuts against the limiting part and the sealing assembly respectively.

8. The high-pressure water injection test system for similar material models according to claim 7, characterized in that, The length of the second adjusting pad assembly is the same as the length of the first adjusting pad assembly; The sum of the lengths of the first adjusting pad assembly, the second adjusting pad assembly, and the boss is the same as the length of the water injection section.

9. A high-pressure water injection test method for a similar material model, characterized in that, A high-pressure water injection test system using a similar material model as described in any one of claims 1 to 8, comprising: Assemble the casting and center hole positioning device, and cast a similar material model with drilled holes; A similar material model was placed on the test bench and a preload was applied; Combine the water injection pipe at the orifice with the sealing assembly and locking parts, and insert it into the drilled hole; The locking mechanism actuates to seal the passage between the outer wall of the water injection pipe at the orifice and the inner wall of the borehole. Connect the orifice water injection pipe to the high-pressure water injection pipeline; Apply boundary stress and inject water.

10. The high-pressure water injection test method for a similar material model according to claim 9, characterized in that, The process of assembling the orifice water injection pipe with the sealing assembly and locking element to form an assembly, and then inserting it into the borehole, includes: The water injection pipe at the orifice is combined with the sealing component, the locking component, and the second adjusting pad component to form an assembly. The first adjusting pad component is placed at the bottom of the borehole, and then the assembly is placed into the borehole and pressed against the first adjusting pad component.

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