Similar material model pouring and center hole positioning device

Abstract

The invention relates to the field of manufacturing of similar material models, and provides a similar material model pouring and center hole positioning device. The similar material model pouring and center hole positioning device comprises a mold, the mold defines a containing cavity used for pouring a similar material model, and the upper end of the containing cavity is open; the drilling centering assembly is arranged at an opening in the upper end of the containing cavity and provided with a mounting hole, and the mounting hole corresponds to the center position of the cross section of the containing cavity; the drilling depth fixed-length assembly comprises a limiting piece and a drilling rod, and the limiting piece is connected to the preset position of the drilling rod; the limiting piece is used for being mounted at the mounting hole so that the lower end of the drilling rod can stretch into the containing cavity. According to the similar material model pouring and center hole positioning device, the problems that in the prior art, a center hole is difficult to machine in a similar material model, the similar material model is prone to being damaged, and the machining precision of the center hole is low can be effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of similar material model manufacturing, in particular to a similar material model pouring and center hole positioning device. BACKGROUND

[0002] The similar material model drilling high-pressure water injection test, as an important means of laboratory research on high-pressure water injection fracturing of various rock layers, is widely used in geotechnical engineering research. It is related to the hard and thick roof rock layer high-pressure water injection fracturing weakening 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. According to the drilling high-pressure water injection engineering characteristics of rock layers, mature laboratory similar material model drilling high-pressure water injection test technology and equipment have been developed. 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 layer and the water injection pressure of the rock layer fracturing, which is used to determine and correct the parameter design of the rock layer high-pressure water injection fracturing construction.

[0003] The similar material model drilling high-pressure water injection test follows the similar model theory. A regular hexahedron similar material model with length, width and height of A, B and H is made for the test system. Before the test, a water injection drilling with diameter φ and depth L is processed on the upper surface of the model. The water injection drilling length L is composed of the water injection section length L1 and the hole sealing section length L2. A group of drilling high-pressure water injection tests includes similar material models with different water injection section lengths. The water injection sections with different lengths L1 are all distributed symmetrically along the model height center line plane. The hole sealing section length L2 and the drilling length L change with the water injection section length L1. The structure of the similar material model for drilling high-pressure water injection is shown in Figure 1 and Figure 2 .

[0004] The similar material model is generally made of cement mortar type solidifiable similar material, which is poured and formed by using a special mold, and the water injection drilling is processed after the model is poured and maintained. There are significant drawbacks in separately processing the water injection drilling after the model is made. Because the model size and weight are large, frequent moving can easily cause damage to the model. It is not easy to accurately position the center of the drilling, and the deviation of the center position causes the installation position of the drilling hole to deviate, which further affects the correct installation of the test system. When the drilling is separately processed, it is not easy to control the drilling depth, and the bottom of the drilling is not standardized, which causes substantial changes in the water injection section length L1, the drilling length L and the water injection section diameter φ, resulting in a decrease in the accuracy of the test results. SUMMARY

[0005] The present application provides a similar material model pouring and center hole positioning device to solve the problems of difficulty in processing the center hole on the similar material model in the prior art, easy damage to the similar material model, and low precision of the center hole processing.

[0006] According to an embodiment of the first aspect of the present application, a similar material model pouring and center hole positioning device comprises: a mold, which surrounds a containing cavity for pouring a similar material model, the upper end opening of the containing cavity is provided; a drilling centering assembly, which is provided at the upper end opening of the containing cavity, has a mounting hole corresponding to the center position of the cross section of the containing cavity; a drilling depth fixed length assembly, which comprises a limiting piece and a drilling rod, the limiting piece is connected to the drilling rod at a preset position; the limiting piece is used to be installed at the mounting hole, so that the lower end of the drilling rod extends into the containing cavity.

[0007] According to an embodiment of the present application, the mold comprises two long side templates, two wide side templates and a bottom plate, the long side templates, the wide side templates and the bottom plate surround the containing cavity; the bottom plate is provided with a first positioning clamping groove matched with the long side templates and the wide side templates; one of the long side templates and the wide side templates is provided with a second positioning clamping groove matched with the other.

[0008] According to an embodiment of the present application, the drilling centering assembly comprises a centering main beam and a centering auxiliary beam, the two ends of the centering main beam are respectively connected with two long side templates, and the two ends of the centering auxiliary beam are respectively connected with two wide side templates; the mounting hole comprises a first mounting hole provided on the centering main beam and a second mounting hole provided on the centering auxiliary beam.

[0009] According to an embodiment of the present application, the drilling centering assembly further comprises a centering sleeve, the centering sleeve is arranged in the first mounting hole and the second mounting hole to connect the centering main beam and the centering auxiliary beam; the centering sleeve is formed with a guide channel for the drilling rod to pass through.

[0010] According to an embodiment of the present application, the centering sleeve is provided with: a first mounting boss matched with the first mounting hole to make the centering sleeve abut and be fixed on the centering main beam; a mounting clamping groove matched with the second mounting hole to make the centering auxiliary beam fixed at the mounting clamping groove; a second mounting boss matched with the limiting piece to make the drilling rod mounted on the drilling centering assembly.

[0011] According to an embodiment of the present application, the lower end of the centering sleeve is provided with a clearance area to adapt the shape of the lower end of the centering sleeve to the second mounting hole. The avoiding empty area is communicated with the mounting slot, so that the centering auxiliary beam is clamped into the mounting slot through the avoiding empty area.

[0012] According to one embodiment of the present application, two ends of the centering main beam are provided with first bending parts which are matched with one side of the long-side formwork away from the accommodating cavity; The first bending part comprises a stepped slot with a guide inclined surface, and the top corner of the stepped slot is abutted with the upper end of the long-side formwork. Two ends of the centering auxiliary beam are provided with second bending parts which are matched with one side of the wide-side formwork away from the accommodating cavity.

[0013] According to one embodiment of the present application, the mold further comprises a connecting rod; The long-side formwork is provided with a fixing hole, and two ends of the connecting rod are connected in the fixing holes of the two long-side formworks respectively to clamp the two long-side formworks. According to one embodiment of the present application, the drilling rod is provided with a plurality of limiting clamping slots along the length direction of the drilling rod, and one of the plurality of limiting clamping slots is matched with the limiting part to adjust the length of the lower end of the drilling rod extending into the accommodating cavity.

[0014] According to one embodiment of the present application, the limiting part comprises a first half ring and a second half ring, and the first half ring and the second half ring are both provided with a limiting part matched with the limiting clamping slot. The first half ring and the second half ring are buckled to form a ring structure to be sleeved on the drilling rod.

[0015] The above one or more technical solutions in the embodiments of the present application have at least one of the following technical effects: The similar material model pouring and center hole positioning device can form a center hole while pouring the similar material model, and does not need to be transported and processed after the similar material model is manufactured, so as to avoid damage to the similar material model in the transportation and processing process. The position of the center hole in the similar material model is determined by the drilling centering assembly, and the processing depth of the center hole in the similar material model is determined by the drilling depth length assembly, so that the position and depth of the center hole are accurate, and the subsequent test result is accurate.

[0016] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the drawings needed to be used in the embodiments or the related art description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 is a structural schematic diagram of a similar material model provided by the present application Figure 1 (solid view).

[0019] Figure 2 is a structural schematic diagram of a similar material model provided by the present application Figure 2 (cross-sectional view).

[0020] Figure 3 is a structural schematic diagram of a similar material model provided by the present application (cross-sectional view).

[0021] Figure 4 is a structural schematic diagram of a mold provided by the present application (cross-sectional view).

[0022] Figure 5 is a structural schematic diagram of a bottom plate provided by the present application (cross-sectional view).

[0023] Figure 6 is a structural schematic diagram of a wide-side formwork provided by the present application Figure 1 (cross-sectional view).

[0024] Figure 7 is a structural schematic diagram of a wide-side formwork provided by the present application Figure 2 (cross-sectional view).

[0025] Figure 8 is a structural schematic diagram of a long-side formwork provided by the present application Figure 1 (cross-sectional view).

[0026] Figure 9 is a structural schematic diagram of a long-side formwork provided by the present application Figure 2 (cross-sectional view).

[0027] Figure 10 is a structural schematic diagram of a drilling centering assembly provided by the present application (cross-sectional view).

[0028] Figure 11 is a structural schematic diagram of a centering main beam provided by the present application (cross-sectional view).

[0029] Figure 12 is a structural schematic diagram of a centering auxiliary beam provided by the present application (cross-sectional view).

[0030] Figure 13 is a structural schematic diagram of a centering sleeve provided by the present application Figure 1 (cross-sectional view).

[0031] Figure 14 is a structural diagram of a centering sleeve provided by the present application Figure 2 .

[0032] Figure 15 is a structural diagram of a drilling depth fixed-length assembly provided by the present application.

[0033] Figure 16 is a structural diagram of a drilling rod provided by the present application.

[0034] Figure 17 is a structural diagram of a limiting piece provided by the present application.

[0035] Reference signs: 1, mold; 11, long-side mold plate; 111, second positioning clamping groove; 112, fixing hole; 12, wide-side mold plate; 13, bottom plate; 131, first positioning clamping groove; 14, accommodating cavity; 2, drilling centering assembly; 21, centering main beam; 211, first mounting hole; 212, first bending part; 213, stepped clamping groove; 214, guide inclined surface; 215, avoiding area; 22, centering auxiliary beam; 221, second mounting hole; 222, second bending part; 23, centering sleeve; 231, guide channel; 232, first mounting boss; 233, mounting clamping groove; 234, second mounting boss; 235, avoiding empty area; 3, drilling depth fixed-length assembly; 31, limiting piece; 311, first half ring; 312, second half ring; 313, limiting part; 32, drilling rod; 321, limiting clamping groove; 4, connecting rod; 5, similar material model; 51, drilling hole; 511, water injection section; 512, hole sealing section. DETAILED DESCRIPTION

[0036] The embodiments of the present application will be further described below in conjunction with the drawings and examples. The following examples are used to illustrate the present application, but cannot be used to limit the scope of the present application.

[0037] In the description of the embodiments of the present application, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only used for the purpose of facilitating the description of the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", "third" are only used for description purposes, and cannot be understood as indicating or implying relative importance.

[0038] In the description of the embodiments of the present application, it should be noted that unless specifically defined and limited otherwise, the terms "connected", "connected to", "connection" should be interpreted broadly, for example, can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0039] In the embodiments of the present application, unless specifically defined and limited otherwise, the first feature is "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0040] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0041] According to the first aspect of the present application, a similar material model pouring and center hole positioning device is provided, as shown in Figure 3 The similar material model pouring and center hole positioning device includes: a mold 1 surrounding a containing cavity 14 for pouring a similar material model 5, the upper end of the containing cavity 14 is open; a drilling centering assembly 2 is arranged at the upper end opening of the containing cavity 14, having a mounting hole corresponding to the center position of the cross section of the containing cavity 14; a drilling depth limiting assembly 3 includes a limiting piece 31 and a drilling rod 32, the limiting piece 31 is connected to the drilling rod 32 at a predetermined position; the limiting piece 31 is installed at the mounting hole, so that the lower end of the drilling rod 32 extends into the containing cavity 14.

[0042] The installation hole of the drilling centering assembly 2 corresponds to the center position of the cross section of the accommodating cavity 14, so that the planar position reference of the central hole can be determined before the similar material model 5 is poured, and the limiting piece 31 cooperates with the drilling rod 32 of the drilling depth fixed-length assembly 3, the limiting piece 31 is connected to the preset position of the drilling rod 32 and is installed at the installation hole, so that the length of the lower end of the drilling rod 32 extending into the accommodating cavity 14 is fixed, thereby synchronously forming the central hole during the pouring process of the similar material model 5, without the need for transportation and secondary processing operation after the model is manufactured, effectively avoiding the damage caused by the large size and heavy weight of the model during transportation, and the hidden damage of the model structure that may be caused during secondary processing, thereby protecting the integrity of the model structure and providing a stable initial condition for subsequent simulation of the actual rock stress environment.

[0043] The installation hole of the drilling centering assembly 2 corresponds to the center position of the cross section of the accommodating cavity 14, so that the planar position reference of the central hole can be determined before the similar material model 5 is poured, and the limiting piece 31 cooperates with the drilling rod 32 of the drilling depth fixed-length assembly 3, the limiting piece 31 is connected to the preset position of the drilling rod 32 and is installed at the installation hole, so that the length of the lower end of the drilling rod 32 extending into the accommodating cavity 14 is fixed, thereby synchronously forming the central hole during the pouring process of the similar material model 5, without the need for transportation and secondary processing operation after the model is manufactured, effectively avoiding the damage caused by the large size and heavy weight of the model during transportation, and the hidden damage of the model structure that may be caused during secondary processing, thereby protecting the integrity of the model structure and providing a stable initial condition for subsequent simulation of the actual rock stress environment.

[0044] The drilling hole 51, that is, the central hole, is composed of a water injection section 511 and a hole sealing section 512.

[0045] The drilling depth fixed-length assembly 3 sets the depth of the drilling rod 32 extending into the accommodating cavity 14 through the limiting piece 31 at the preset position of the drilling rod 32, thereby accurately determining the processing depth of the central hole, avoiding the out-of-control drilling depth of the drilling hole 51 and the non-standard forming of the bottom of the drilling hole 51 caused by the equipment precision and uneven material hardness in the traditional processing, effectively preventing substantial changes in key test parameters such as the length of the water injection section 511, the total length of the drilling hole 51 and the hole diameter of the water injection section 511, ensuring that the test parameters are consistent with the design values, providing reliable data support for the research on the relationship between the water injection drilling diameter, the length of the water injection section 511 and the rock stress environment, and the water injection pressure, and helping to accurately determine and correct the parameter design of the rock high-pressure water injection and fracturing construction, thereby improving the accuracy and reference value of the test results.

[0046] The similar material model pouring and central hole positioning device provided by the embodiments of the present application can effectively solve the problems in the center positioning and hole depth fixing process of the similar material model 5 in the drilling high-pressure water injection and fracturing test, improve the reliability of the test results, make the similar material model 5 and the drilling hole 51 one-time forming, simplify the model manufacturing and processing technology, and avoid the risk of damage caused by secondary processing and transportation.

[0047] According to one embodiment of the present application, as Figure 4As shown, the mold 1 includes two long side templates 11, two wide side templates 12 and a bottom plate 13, the long side templates 11, the wide side templates 12 and the bottom plate 13 are arranged to form a containing cavity 14; the bottom plate 13 is provided with a first positioning clamping groove 131 matched with the long side templates 11 and the wide side templates 12; one of the long side templates 11 and the wide side templates 12 is provided with a second positioning clamping groove 111 matched with the other. The following is described by taking “the long side template 11 is provided with a second positioning clamping groove 111 matched with the wide side template 12” as an example.

[0048] The long side templates 11, the wide side templates 12 and the bottom plate 13 can be steel plates, and the thickness of the steel plates is a. The upper surface of the bottom plate 13 can be processed to have a first positioning clamping groove 131 with a width of a and a depth of t, matched with the long side templates 11 and the wide side templates 12, wherein the first positioning clamping groove 131 matched with the long side templates 11 is a through groove. The wide side template 12 defines a model width B and has a rectangular flat plate shape, with a plate surface width of B+2t and a plate surface height of H+t+T1.

[0049] The long side template 11 is a fixed-length and fixed-height template of the model, with a template height of H+t; the inner side surface is processed to have a second positioning clamping groove 111 with a width of a and a depth of t, matched with the wide side template 12, and the inner side plate surface width of the two parallel clamping grooves is A, and the clamping groove outer side is processed to have a bolt hole φ1 for clamping screw bolts of the mold.

[0050] The mold 1 is formed by the two long side templates 11, the two wide side templates 12 and the bottom plate 13 to form the containing cavity 14, providing a stable forming space for pouring of the similar material model 5, ensuring that the model maintains the preset length, width and height size form during pouring, avoiding model shape distortion caused by unstable mold 1 structure, and providing a regular basic carrier for subsequent center hole processing and high-pressure water injection test.

[0051] The bottom plate 13 is provided with the first positioning clamping groove 131 matched with the long side templates 11 and the wide side templates 12, which can quickly realize the positioning butt joint of the three components during the mold 1 assembly stage, reduce the error of manual alignment operation, avoid the size of the containing cavity 14 not meeting the design value due to the position offset of the template, and thus ensure the actual size accuracy of the similar material model 5. At the same time, the matching structure of the first positioning clamping groove 131 can enhance the stability of the connection between the template and the bottom plate 13, prevent the template from being displaced due to the influence of material side pressure during pouring, reduce the leakage problem during model pouring, and improve the model forming quality.

[0052] The long-side template 11 is provided with a second positioning clamping groove 111 to cooperate with the wide-side template 12, so as to strengthen the tightness of the joint of the two types of templates, further improve the sealing performance of the mold 1 as a whole, avoid material waste caused by pouring material overflowing from the joint gap of the templates, and prevent defects such as missing corners and recesses on the side surface of the model caused by the gap, and ensure the structural integrity of the model. The cooperation mode of the second positioning clamping groove 111 simplifies the assembly and disassembly process of the mold 1, and the templates can be fixed and separated without complex tooling, thereby improving the convenience of using the mold 1.

[0053] The length of the long-side template 11 and the length of the wide-side template 12 can be flexibly adjusted (same or different), so that a similar material model 5 with a square or rectangular cross section can be formed according to the test requirements, the differentiated requirements for the model size in different test scenarios are adapted, the investment cost of the test equipment is reduced, the versatility of the mold 1 is improved, and the diversified rock stratum high-pressure water injection fracturing simulation requirements are met.

[0054] In some cases, scale marks can be provided on the inner side walls of the long-side template 11 and the wide-side template 12, and the scale marks are distributed along the height direction of the templates. The scale marks can intuitively display the pouring height of the material when the similar material is poured, so as to facilitate the operator to control the pouring amount, avoid material overflow caused by excessive pouring, or affect the model height size caused by insufficient pouring, and further improve the model size precision. Meanwhile, elastic sealing pads can be provided on the inner sides of the first positioning clamping groove 131 and the second positioning clamping groove 111. The elastic sealing pads can fill the gap between the clamping groove and the template, enhance the sealing performance of the mold 1, reduce the risk of slurry leakage during pouring, and the elastic structure can reduce the collision and wear during assembly of the templates, thereby prolonging the service life of the mold 1.

[0055] According to one embodiment of the present application, as shown in Figure 10 The drilling centering assembly 2 includes a centering main beam 21 and a centering auxiliary beam 22. The two ends of the centering main beam 21 are respectively connected with the two long-side templates 11, and the two ends of the centering auxiliary beam 22 are respectively connected with the two wide-side templates 12. The mounting hole includes a first mounting hole 211 provided on the centering main beam 21 and a second mounting hole 221 provided on the centering auxiliary beam 22. The connection here can be lap joint. The first mounting hole 211 is located at the center position of the connection section of the centering main beam 21 and the long-side template 11 and the wide-side template 12; and the second mounting hole 221 is located at the center position of the connection section of the centering auxiliary beam 22 and the long-side template 11 and the wide-side template 12.

[0056] The two ends of the centering main beam 21 are respectively overlapped with the two long side molds 11, and the two ends of the centering auxiliary beam 22 are respectively overlapped with the two wide side molds 12, so that the positions of the centering main beam 21 and the centering auxiliary beam 22 are directly associated with the long side molds 11 and the wide side molds 12 of the mold 1 to avoid the position deviation caused by the independent setting of the centering assembly away from the mold 1. Since the two long side molds 11 and the two wide side molds 12 are respectively the oppositely arranged components in the mold 1, the distance therebetween corresponds to the width and length dimensions of the accommodating cavity 14, and when the two long side molds 11 and the two wide side molds 12 are cross-distributed, the mounting holes (the first mounting hole 211 and the second mounting hole 221) penetrating the two long side molds 11 and the two wide side molds 12 can be naturally aligned with the cross-sectional center of the accommodating cavity 14, effectively solving the problem of inaccurate center positioning when the traditional drilling is separately processed, providing a stable position reference for the center hole, and ensuring that the subsequent drilling rod 32 can be formed along the center axis when it extends into the accommodating cavity 14, thereby avoiding the installation deviation of the orifice water injection pipe.

[0057] The centering main beam 21 and the centering auxiliary beam 22 are connected to the opposite molds of the mold 1 in a lapping manner, can form a cross support structure, and enhance the installation stability of the drilling centering assembly 2 as a whole. In the similar material pouring process, even if subjected to the side pressure of the pouring material or the operation collision, the centering main beam 21 and the centering auxiliary beam 22 are not easy to be displaced, can always keep the center position of the mounting hole unchanged, avoid the position deviation of the center hole caused by the deviation of the centering assembly, and guarantee the position accuracy of the formed center hole, thereby providing a basis for the uniform conduction of the water injection pressure in the subsequent high-pressure water injection test.

[0058] The drilling centering assembly 2 also has good adaptability. Since the length of the long side mold 11 and the length of the wide side mold 12 of the mold 1 can be flexibly adjusted (to form the accommodating cavity 14 with a square or rectangular cross section), the dimensions of the centering main beam 21 and the centering auxiliary beam 22 can be set based on the required length and width dimensions of the similar material model 5, and then matched with the corresponding long side mold 11 and wide side mold 12 to form similar material models 5 with different sizes.

[0059] The lapping connection mode simplifies the installation and disassembly process of the drilling centering assembly 2. After the mold 1 is assembled, the centering main beam 21 and the centering auxiliary beam 22 can be quickly lapped onto the corresponding molds. After the similar material is poured and formed and the center hole is preliminarily formed, the centering main beam 21 and the centering auxiliary beam 22 only need to be taken off upwards, without the need for complex disassembly procedures, which reduces the operation time, improves the model manufacturing efficiency, and avoids damage to the model or the centering assembly during the disassembly process.

[0060] To prevent the centering assembly from sinking and bending, the centering main beam 21 can be processed using a small channel steel, with the outer side of the two side long formworks 11 after the assembly of the mold 1 as the centering reference in the width direction of the model, and the length of the centering inner notch being the sum of the width of the model and the thickness of the two side formworks (B+2a). The center is processed with the first mounting hole 211 matched with the centering sleeve 23, and the inner threaded hole with a spacing L1-1 is processed for mounting the limiting set screw. The centering auxiliary beam 22 is made of stainless steel plate with a thickness t2-1, with the outer side of the two side wide formworks 12 after the assembly of the mold 1 as the centering reference in the length direction of the model, and the length of the centering inner notch being the sum of the length of the model and the thickness of the two side formworks (A+2a). The center is processed with the second mounting hole 221 matched with the centering sleeve 23, and the limiting screw hole is processed with the same spacing L2-1 as the spacing L1-1 of the set screw mounting hole of the centering main beam 21.

[0061] According to one embodiment of the present application, as shown in Figure 10 The drilling centering assembly 2 further includes a centering sleeve 23, which is arranged in the first mounting hole 211 and the second mounting hole 221 to connect the centering main beam 21 and the centering auxiliary beam 22; and the centering sleeve 23 forms a guide channel 231 for the drilling rod 32 to pass through.

[0062] The centering sleeve 23 is an inner-outer variable diameter tubular structure and is 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 processed with a mounting clamping groove 233 for cooperation with the centering auxiliary beam 22, the clamping groove has an outer diameter φ3-2 which is the same as the diameter of the second mounting hole of the centering auxiliary beam 22, and the clamping groove has a width t3-1 which is slightly larger than the thickness of the centering auxiliary beam 22. The inner hole φ3-3 has the same diameter φ as the center hole of the similar material model 5 (i.e., the water injection drilling hole 51), and matches the hole diameter requirement of the subsequent water injection section 511; the inner hole φ3-4 matches the drilling depth fixed length assembly 3 of the model drilling hole 51, and the other end of the centering sleeve 23 is processed with a wrench opening S.

[0063] The centering sleeve 23 is arranged in the first mounting hole 211 of the centering main beam 21 and the second mounting hole 221 of the centering auxiliary beam 22, which can form a stable overall structure of the centering main beam 21 and the centering auxiliary beam 22 which are originally placed independently and cross each other, avoiding the relative displacement of the two due to pouring vibration, cement mortar side pressure or operation collision when only relying on lap positioning in the traditional way. The mounting holes of the centering main beam 21 and the centering auxiliary beam 22 are the core reference for the drilling rod 32 to extend into, and they need to be coaxially aligned at all times to ensure the accurate position of the center hole. The centering sleeve 23 can lock the relative position of the two by rigid connection through the two mounting holes, prevent the misalignment of the hole position, solve the problem of centering reference deviation that may occur when placed separately, and provide stable coaxial guidance for the subsequent drilling rod 32 to extend into the accommodation cavity 14, and guarantee the planar position accuracy and perpendicularity of the center hole.

[0064] The inner wall of the centering sleeve 23 can form a unified guide channel 231, which can limit the radial swing of the drilling rod 32 when the drilling rod 32 extends into the accommodating cavity 14 through the centering sleeve 23, avoid the inclination of the drilling rod 32 due to its own gravity or external interference, further ensure the perpendicularity of the center hole, reduce the probability of irregularities (such as uneven hole diameter, inclined hole wall) on the inner wall of the center hole, provide regular hole wall conditions for the subsequent sealing cooperation of the water injection pipe and the center hole, and reduce the risk of water injection leakage. At the same time, the centering sleeve 23 can isolate the drilling rod 32 from directly contacting the mounting hole wall of the centering main beam 21 and the centering auxiliary beam 22, reduce the friction and wear of the mounting hole wall when the drilling rod 32 is repeatedly inserted and extracted, avoid the enlargement of the mounting hole diameter or the distortion of the shape after long-term use, and prolong the service life of the centering main beam 21 and the centering auxiliary beam 22; if the centering sleeve 23 is worn, only the centering sleeve 23 needs to be replaced, without replacing the entire centering main beam 21 or auxiliary beam, thereby reducing the maintenance cost.

[0065] According to one embodiment of the present application, the drilling centering assembly 2 further comprises a rotation limiting screw (such as a cylindrical head limiting screw), which is arranged in the centering main beam 21 and the centering auxiliary beam 22 to limit the relative rotation of the two. Figure 11 In the specific implementation, the outer side of the first mounting hole 211 is provided with two through holes for the rotation limiting screw to pass through; Figure 12 In the specific implementation, the outer side of the second mounting hole 221 is provided with two through holes for the rotation limiting screw to pass through.

[0066] According to one embodiment of the present application, as shown in Figure 13 and Figure 14 The centering sleeve 23 is provided with a first mounting boss 232, a mounting clamping groove 233 and a second mounting boss 234. The first mounting boss 232 is used to cooperate with the first mounting hole 211 to abut and fix the centering sleeve 23 on the centering main beam 21. The mounting clamping groove 233 is used to cooperate with the second mounting hole 221 to fix the centering auxiliary beam 22 at the mounting clamping groove 233. The second mounting boss 234 is used to cooperate with the limiting piece 31 to install the drilling rod 32 on the drilling centering assembly 2.

[0067] The first mounting boss 232 of the centering sleeve 23 cooperates with the first mounting hole 211 of the centering main beam 21, which limits the radial movement of the centering sleeve 23 through the rigid contact between the first mounting boss 232 and the hole wall of the first mounting hole 211, and at the same time abuts and fixes the centering sleeve 23 on the centering main beam 21, avoids the axial sliding of the centering sleeve 23 during the pouring vibration or the insertion of the drilling rod 32, and ensures that the centering sleeve 23 is always in the preset position connected to the centering main beam 21, thereby providing a stable basis for the subsequent cooperation with the centering auxiliary beam 22.

[0068] The mounting clamping groove 233 on the centering sleeve 23 matches the second mounting hole 221 of the centering auxiliary beam 22, so that the centering auxiliary beam 22 is accurately clamped into the clamping groove, forming double limiting in the axial and radial directions, and avoiding relative displacement between the centering auxiliary beam 22 and the centering sleeve 23. The centering main beam 21 and the centering auxiliary beam 22 are rigidly connected through the first mounting boss 232 and the mounting clamping groove 233 of the centering sleeve 23, so as to ensure that the mounting holes of the two are always coaxial, solve the problem that the hole positions are easily dislocated due to external force when the traditional cross placement is used, provide a unified guide channel 231 for the drilling rod 32, guarantee the planar position accuracy of the center hole, avoid the center hole from being deviated or inclined, ensure that the subsequent water injection pipe can be accurately connected with the center hole, and reduce the risk of water injection leakage.

[0069] The second mounting boss 234 on the centering sleeve 23 matches the limiting piece 31, so as to provide a stable support reference for the limiting piece 31 and limit the movement range of the limiting piece 31 along the axial direction of the drilling rod 32. The limiting piece 31 itself is used to control the length of the drilling rod 32 extending into the accommodating cavity 14, and the cooperation between the second mounting boss 234 and the limiting piece 31 can further fix the position of the limiting piece 31, so as to avoid displacement of the limiting piece 31 due to vibration or operation collision, and further ensure the stability of the extension depth of the drilling rod 32, and reduce the deviation of the key test parameters L1, L, etc. At the same time, the second mounting boss 234 can isolate the direct contact between the limiting piece 31 and the centering auxiliary beam 22, reduce the wear of the centering auxiliary beam 22 when the limiting piece 31 is repeatedly disassembled and assembled, and prolong the service life of the centering auxiliary beam 22; if the centering sleeve 23 is worn, only the centering sleeve 23 needs to be replaced, without replacing the centering main beam 21, the centering auxiliary beam 22 or the limiting piece 31, thereby reducing the maintenance cost.

[0070] The centering sleeve 23 cooperates with the centering main beam 21, the centering auxiliary beam 22 and the limiting piece 31 through three structures respectively, and integrates the three into a complete positioning system, thereby enhancing the structural rigidity of the whole drilling centering assembly 2.

[0071] According to one embodiment of the present application, as shown in Figure 13 The lower end of the centering sleeve 23 is provided with a relief area 235, so that the lower end of the centering sleeve 23 is matched with the shape of the second mounting hole 221; the relief area 235 is communicated with the mounting clamping groove 233, so that the centering auxiliary beam 22 is clamped into the mounting clamping groove 233 through the relief area 235.

[0072] The relief area 235 provided at the lower end of the centering sleeve 23 matches the shape of the second mounting hole 221, so as to avoid assembly jamming caused by the fact that the profile of the lower end of the centering sleeve 23 does not match the shape of the second mounting hole 221, provide a smooth clamping space for the second mounting hole 221 of the centering auxiliary beam 22, reduce the difficulty of alignment when the centering auxiliary beam 22 and the centering sleeve 23 are assembled, and is especially suitable for the scene that there is a small size deviation in the second mounting hole 221 or the lower end of the centering sleeve 23 has a machining round corner, thereby improving the assembly convenience.

[0073] The avoidance space 235 is communicated with the mounting slot 233, and a guide channel from the lower end of the centering sleeve 23 to the mounting slot 233 can be formed, and the second mounting hole 221 of the centering auxiliary beam 22 can be directly slid into the mounting slot 233 through the avoidance space 235, thereby improving the operation efficiency. After the second mounting hole 221 is mounted to the mounting slot 233, it can be limited to be out of the mounting slot 233 by rotating 90 degrees, thereby simplifying the fixing process and avoiding the fixing failure caused by the loss or improper installation of the fastener.

[0074] According to one embodiment of the present application, as shown in Figure 11 The two ends of the centering main beam 21 are provided with first bending parts 212, which are matched with the side of the long-side formwork 11 away from the accommodating cavity 14; the first bending part 212 comprises a stepped slot 213 with a guide slope 214, and the top corner of the stepped slot 213 is in abutment with the upper end of the long-side formwork 11. The two ends of the centering auxiliary beam 22 are provided with second bending parts 222, which are matched with the side of the wide-side formwork 12 away from the accommodating cavity 14.

[0075] After the centering main beam 21 and the centering auxiliary beam 22 are connected with the outer surfaces of the long-side formwork 11 and the wide-side formwork 12 after the mold assembly, the centering main beam 21 and the centering auxiliary beam 22 are automatically coincided with the center line of the accommodating cavity 14, and the intersection center of the two beams is coincided with the center of the accommodating cavity, thereby forming a horizontal centering point of the model top surface.

[0076] The first bending part 212 at the two ends of the centering main beam 21 is matched with the side of the long-side formwork 11 away from the accommodating cavity 14, and can form a transverse limit for the centering main beam 21 from the outside of the long-side formwork 11, thereby avoiding the deviation of the centering main beam 21 during the installation or pouring process, and ensuring that the centering main beam 21 always extends along the preset direction of the long-side formwork 11, thereby providing a transverse position guarantee for the subsequent alignment of the mounting hole to the center of the accommodating cavity 14. This side matching mode can further limit the displacement freedom degree of the centering main beam 21, reduce the position deviation of the centering main beam 21 caused by factors such as vibration and material side pressure, and improve the installation stability of the whole centering assembly.

[0077] The stepped slot 213 contained in the first bending part 212 has a guide slope 214, which can play a guiding role when the centering main beam 21 is assembled with the long-side formwork 11. The operator can slide the edge of the long-side formwork 11 into the stepped slot 213 along the guide slope 214 without precise alignment, thereby reducing the alignment difficulty during assembly and improving the assembly efficiency of the centering main beam 21 and the long-side formwork 11. Meanwhile, the top corner of the stepped slot 213 is in abutment with the upper end of the long-side formwork 11, thereby ensuring that the centering main beam 21 always maintains at a preset height, and further ensuring the longitudinal position accuracy of the center hole in the similar material model 5.

[0078] The cooperation structure of the stepped clamping groove 213 and the upper end of the long side template 11 does not need to additionally process a complex positioning structure on the long side template 11, and only through the stepped clamping groove 213 of the first bending part 212, the stable cooperation with the long side template 11 can be realized, the processing flow of the long side template 11 is simplified, the manufacturing cost of the whole mold 1 is reduced, meanwhile, the original assembly relationship of the long side template 11, the wide side template 12 and the bottom plate 13 is not affected, and the structural stability and the processing convenience are considered.

[0079] In some cases, an elastic buffer layer can be arranged on the inner side wall of the stepped clamping groove 213, and the elastic buffer layer is made of a material with wear resistance and certain elasticity. When the long side template 11 cooperates with the stepped clamping groove 213, the elastic buffer layer can fill the small gap between the two, enhance the close-fitting tightness, meanwhile, the impact force generated by material vibration can be absorbed during the pouring process, the influence of vibration on the position of the centering main beam 21 is reduced, and the centering accuracy is further improved; and the elastic buffer layer can also avoid the hard contact wear between the stepped clamping groove 213 and the long side template 11, prolong the service life of the first bending part 212 and the long side template 11.

[0080] The second bending part 222 at both ends of the centering auxiliary beam 22 cooperates with the side of the wide side template 12 away from the accommodating cavity 14, can form transverse limiting of the centering auxiliary beam 22 from the outside of the wide side template 12, avoid the deviation of the centering auxiliary beam 22 during installation, pouring or vibrating, and ensure that the centering auxiliary beam 22 always extends along the preset direction of the wide side template 12. Since the centering auxiliary beam 22 and the centering main beam 21 are distributed in cross (respectively along the length direction and the width direction of the accommodating cavity 14), the two together constitute the support frame of the drilling centering assembly 2, the transverse limiting of the centering auxiliary beam 22 by the second bending part 222 can complement the transverse limiting of the centering main beam 21 by the first bending part 212, further constrain the displacement degree of freedom of the whole drilling centering assembly 2, reduce the overall deviation of the assembly caused by external interference (such as vibrating vibration, material side pressure), ensure that the installation holes through the two are always aligned with the cross-sectional center of the accommodating cavity 14, effectively solve the problem that the center positioning is easy to deviate when the traditional drilling is processed alone, and provide accurate position reference for the center hole forming.

[0081] The cooperation of the second bending part 222 and the wide side template 12 can also enhance the installation stability of the centering auxiliary beam 22. Compared with the simple top lap, the second bending part 222 forms support from the side of the wide side template 12, ensures that the centering auxiliary beam 22 keeps the position unchanged during the whole pouring process, and then guarantees the longitudinal and transverse position accuracy of the installation hole, provides stable guidance for the subsequent drilling rod 32 to extend into the accommodating cavity 14, avoids the inclination of the center hole or the irregularity of the hole diameter, and guarantees the sealing of the subsequent water injection pipe installation and the uniformity of the water injection pressure conduction.

[0082] According to one embodiment of the present application, as Figure 11As shown, the centering main beam 21 is further provided with an avoiding area 215, which is arranged to form a first gap between the main body of the centering main beam 21 and the upper end opening of the accommodating cavity 14.

[0083] The avoiding area 215 arranged on the centering main beam 21 forms the first gap between the main body of the centering main beam 21 and the upper end opening of the accommodating cavity 14, which can establish a physical separation between the upper surface of the similar material model 5 and the drilling centering assembly 2 after the cement mortar is poured in the accommodating cavity 14, and avoid the un-solidified cement mortar from directly contacting the centering main beam 21 in space. When the un-solidified model is vibrated (vibration is to remove the air bubbles in the mortar and improve the compactness of the model), even if the mortar is shaken or slightly splashed due to vibration, the centering main beam 21 cannot be touched due to the existence of the first gap, thereby effectively preventing the cement mortar from adhering to the drilling centering assembly 2.

[0084] The arrangement of the avoiding area 215 does not affect the core positioning function of the centering main beam 21. The avoiding area 215 only acts on the main body of the centering main beam 21, and the first bending part 212 at both ends of the centering main beam 21 can still stably cooperate with the long-side formwork 11 to ensure the installation stability and position accuracy of the centering main beam 21 as a whole, and realize the dual requirements of “avoiding adhesion” and “precise positioning”. Moreover, the avoiding function can be realized only by optimizing the structure of the centering main beam 21 itself without the need for complex additional structures (such as additional isolation pieces), which simplifies the overall structure of the drilling centering assembly 2, reduces the manufacturing cost, and is also convenient for processing and assembly of the assembly.

[0085] In actual application, the centering main beam 21 and the centering auxiliary beam 22 can be: the centering main beam 21 on the top and the centering auxiliary beam 22 on the bottom (as shown in FIG. 1), or the centering auxiliary beam 22 on the top and the centering main beam 21 on the bottom. Figure 10 When the centering auxiliary beam 22 is on the top and the centering main beam 21 is on the bottom, the first gap can ensure that the centering auxiliary beam 22 is farther away from the upper end opening of the accommodating cavity 14; when the centering main beam 21 is on the top and the centering auxiliary beam 22 is on the bottom, the distance between the centering auxiliary beam 22 and the upper end opening of the accommodating cavity 14 is less than the first gap, at which time a certain distance between the centering auxiliary beam 22 and the upper end opening of the accommodating cavity 14 should still be ensured to avoid the centering auxiliary beam 22 from contacting the cement mortar.

[0086] According to an embodiment of the present application, as shown in FIG. 2, the centering auxiliary beam 22 is provided with an avoiding area 225. Figure 4As shown, the mold 1 further comprises a connecting rod 4; the long edge template 11 is provided with a fixing hole 112; the two ends of the connecting rod 4 are respectively connected in the fixing holes 112 of the two long edge templates 11 to clamp the long edge templates 11, the position of the wide edge template 12 is constrained by the bottom plate clamping groove (the first positioning clamping groove 131) and the long edge template clamping groove (the second positioning clamping groove 111), and the inclination of the wide edge template 12 is limited, the position of the long edge template 11 is constrained by the bottom plate clamping groove (the first positioning clamping groove 131), the width of the wide edge template and the connecting rod 4, and the inclination of the long edge template 11 is limited. The connecting rod 4 can be a double-headed bolt, the two ends of the double-headed bolt are used in cooperation with nuts, and an elastic washer can be arranged between the nut and the long edge template 11.

[0087] The connecting rod 4 can fix the two long edge templates 11, so that the long edge templates 11 and the wide edge template 12 form a position-fixed side combination. The connecting rod 4 can be provided in two groups to correspond to the two wide edge templates 12, and each group is provided as two in the height direction.

[0088] The connecting rod 4 is simple and efficient in installation mode, only needs to be inserted into the fixing holes 112 of the two long edge templates 11 at both ends, and the positioning and fixing can be completed, without the need for additional complex locking structures, without disturbing the original assembly relationship of the long edge template 11 and the wide edge template 12, the bottom plate 13 (such as the cooperation of the first positioning clamping groove 131 of the long edge template 11 and the bottom plate 13, the cooperation of the second positioning clamping groove 111 of the long edge template 11 and the wide edge template 12), which not only simplifies the assembly process of the mold 1, but also quickly forms support for the wide edge template 12, improves the overall assembly efficiency of the mold 1, and facilitates the disassembly of the connecting rod 4 after pouring is completed.

[0089] According to one embodiment of the present application, as shown in Figure 15 and Figure 16 As shown, the drill rod 32 is provided with a plurality of limiting clamping grooves 321 along the length direction of the drill rod 32, one of the plurality of limiting clamping grooves 321 cooperates with the limiting piece 31 to adjust the length of the lower end of the drill rod 32 extending into the accommodating cavity 14.

[0090] The prefabricated drill rod 32 is a threaded rod structure with one end, which is made of stainless steel. One prefabricated drill rod 32 can be used for a group of model drillings with different depths. The rod body is externally threaded at one end, and the other end has an outer diameter equal to the diameter of the prefabricated drilling end, which is the same as the diameter of the model drilling. The surface of the rod body is processed with a plurality of limiting clamping grooves 321 corresponding to the change of hole depth, the limiting clamping grooves 321 are used as hole depth positioning clamping grooves, and the distribution position of the limiting clamping grooves 321 is determined by the change of the drilling depth of the model and the installation structure of the centering assembly, that is, the length of each limiting clamping groove 321 from the end of the prefabricated drill rod 32 corresponds to different drilling depths, and the diameter of the limiting clamping groove 321 is slightly smaller than the diameter of the rod end.

[0091] The drilling rod 32 is provided with a plurality of limiting grooves 321 along the length direction of the drilling rod 32. By selecting one of the plurality of limiting grooves 321 to cooperate with the limiting piece 31, the length of the lower end of the drilling rod 32 extending into the accommodating cavity 14 can be flexibly adjusted, and the center hole machining with different depth requirements can be adapted without replacing the entire drilling rod 32. In the similar material model 5 high-pressure water injection test, different test groups often need different water injection section 511 lengths L1, and the corresponding total drilling length L (composed of L1 and the length L2 of the hole sealing section 512) is different. This structure can quickly adjust the extension depth of the drilling rod 32 by switching the cooperation position of the limiting groove 321 and the limiting piece 31 to meet the requirements of different test parameters, solve the problem that the traditional drilling rod 32 has a fixed depth and needs to be frequently replaced to adapt to multiple tests, and improve the test preparation efficiency.

[0092] At the same time, the cooperation mode of the limiting groove 321 and the limiting piece 31 can ensure the stability of the extension length of the drilling rod 32, avoid displacement of the drilling rod 32 due to pouring vibration or operation collision, and further ensure the depth precision of the center hole. Through the rigid cooperation of the limiting groove and the limiting piece 31, the extension length of the drilling rod 32 remains fixed, the depth deviation is reduced, the consistency of the test parameters is ensured, and the reliability of the data is ensured when the relationship between the water injection drilling diameter φ, L1 and the rock stress environment, the water injection pressure is studied subsequently.

[0093] This structure simplifies the operation process of depth adjustment, and the operator does not need to use complex measuring tools or adjust equipment parameters. Only by detaching the limiting piece 31 from the original groove and installing it into the target groove can the adjustment be completed, which reduces the operation difficulty and is especially suitable for rapid switching of multiple comparison tests. At the same time, a single drilling rod 32 can adapt to multiple depth requirements, and multiple drilling rods 32 do not need to be designed for different depths, which reduces the investment cost of test equipment, reduces the equipment storage space, and improves the equipment utilization.

[0094] This structure can also adapt to similar material models 5 of different heights (such as regular hexahedral models with different H values), and when the model height changes, the required center hole depth changes, the drilling rod 32 does not need to be replaced, only the groove cooperation position needs to be adjusted, which further enhances the universality of the device, meets the needs of diversified test scenarios, avoids equipment idling due to changes in model size, and improves the comprehensive utilization value of the test equipment.

[0095] In some cases, a depth mark can be provided beside each limiting slot 321, which indicates the length value of the lower end of the drill rod 32 extending into the accommodating cavity 14 corresponding to the slot. The operator can quickly identify and select the required slot without additional measurement, avoid depth deviation caused by misselection of the slot, and further improve the operation convenience and adjustment accuracy. At the same time, the depth mark can be laser engraved or printed with wear-resistant ink to ensure that it is still clear after long-term use, avoid operation errors caused by mark wear, and prolong the service life of the drill rod 32.

[0096] According to one embodiment of the present application, as shown in Figure 17 The limiting member 31 includes a first semicircular ring 311 and a second semicircular ring 312, and the first semicircular ring 311 and the second semicircular ring 312 are both provided with a limiting portion 313 matched with the limiting slot 321; the first semicircular ring 311 and the second semicircular ring 312 are buckled to form an annular structure to be sleeved on the drill rod 32.

[0097] The limiting member 31 can adopt the form of a positioning clasp ring, which is made of stainless steel and has a variable inner diameter semicircular ring structure. The structure size of the positioning clasp ring is matched with the centering sleeve 23 and the prefabricated drill rod 32. The outer diameter of the positioning clasp ring is the same as the inner hole φ3-4 of the centering sleeve 23. The inner hole boss (i.e., the limiting portion 313) of the positioning clasp ring corresponds to the limiting slot 321 of the prefabricated drill rod 32. After the positioning clasp ring is processed as a whole annular ring, it is divided into two parts along the diameter center line.

[0098] The first semicircular ring 311 and the second semicircular ring 312 are both provided with a limiting portion 313 matched with the limiting slot 321, and after buckling, the two limiting portions 313 can be symmetrically clamped into the limiting slot 321 from the circumferential direction of the drill rod 32 to form bidirectional limiting, thereby enhancing the stability of the limiting member 31 matched with the drill rod 32.

[0099] The annular structure formed by buckling can be closely combined with the outer peripheral surface of the drill rod 32 to improve the matching stability and at the same time avoid local pressure concentration to cause surface damage of the drill rod 32. The structure of the limiting member 31 also facilitates the maintenance and replacement of the limiting member 31. If the first semicircular ring 311 or the second semicircular ring 312 is damaged (such as the limiting portion 313 is worn or the semicircular ring is deformed), only the damaged single semicircular ring needs to be replaced, without replacing the whole limiting member 31, thereby reducing the accessory loss cost, prolonging the overall service life of the limiting member 31, and at the same time facilitating the quick replacement of the limiting member 31 in the test to adapt to different limiting slot 321 positions, thereby improving the operation flexibility.

[0100] According to one embodiment of the present application, as shown in Figure 15 The drill depth fixed-length assembly 3 further includes a nut arranged on the upper end of the drill rod 32, and the upper end of the drill rod 32 is provided with an external thread matched with the nut; the nut is installed on the upper end of the drill rod 32 to drive the drill rod 32 to rotate.

[0101] The upper end of the drilling rod 32 is matched with the nut through external threads. Before the similar material model 5 is not cured, the operator can drive the drilling rod 32 to rotate in time by rotating the nut, continuously destroy the contact interface between the outer periphery of the drilling rod 32 and the uncured cement mortar, and avoid the firm bonding between the two during the curing process. The commonly used cement mortar material of the similar material model 5 will gradually produce bonding force with the contacted solid surface during the curing stage. If the drilling rod 32 is integrated with the model after curing, the subsequent removal of the drilling rod 32 will easily cause cracks, missing corners or deformation of the central hole in the model, damage the structural integrity of the model, and affect the accuracy of the subsequent high-pressure water injection test. The timed rotation of the drilling rod 32 can fundamentally avoid this problem and ensure the model forming quality and the regularity of the central hole.

[0102] The setting of the nut provides a stable force carrier for the timed rotation of the drilling rod 32. Compared with directly holding the upper end of the drilling rod 32 to rotate, the planar structure of the nut matched with the threads can disperse the hand force, avoid unstable holding due to the small size of the upper end of the drilling rod 32, and simultaneously control the rotation speed and frequency of the nut to ensure the uniform rotation of the drilling rod 32 and not damage the overall shape of the uncured model (such as avoiding the model surface depression and internal material disturbance caused by too fast rotation). The threaded cooperation has good transmission stability, and the drilling rod 32 can be coaxially rotated when the nut is rotated, avoiding the inclination of the drilling rod 32 due to uneven force, further ensuring the perpendicularity of the central hole, and ensuring the smoothness of the inner wall of the central hole and the consistency of the hole diameter, providing a basis for the sealing of the subsequent water injection pipe installation and the uniform conduction of the water injection pressure.

[0103] The structure can also cooperate with the limiting piece 31 to limit the extension length of the drilling rod 32 through the limiting clamping groove 321. When the nut drives the drilling rod 32 to rotate, the limiting piece 31 can prevent the axial displacement of the drilling rod 32, ensure that the depth of the drilling rod 32 extending into the accommodating cavity 14 remains unchanged during the rotation process, avoid the central hole depth deviation caused by rotation, and ensure the accuracy of the key test parameters such as L1 and L. At the same time, the threaded cooperation has strong disassembly and assembly convenience. After the test is completed, the nut and the drilling rod 32 can be quickly disassembled, and the worn parts of the nut and the drilling rod 32 can be replaced individually without replacing the entire drilling depth fixed length assembly 3, reducing the equipment maintenance cost and prolonging the overall service life of the assembly.

[0104] The design does not need to additionally add an anti-bonding device (such as coating a release agent), but only through the cooperation of the existing nut and the drilling rod 32 to achieve the anti-bonding function, which simplifies the test process, avoids the potential influence of the release agent on the performance of the similar material, ensures the similarity of the model material performance and the actual rock stratum, and improves the reliability of the test data.

[0105] The similar material model pouring and center hole positioning device provided by the embodiments of the present application has multiple advantages: 1) accurately positioning the drilling center of the similar material model 5, avoiding the influence of drilling center deviation on the installation of the test system. 2) The drilling depth and diameter are controlled by the mechanically processed drilling depth fixed-length assembly 3, the drilling depth, the length and position of the water injection section 511 can be accurately positioned, and the same set of similar material model pouring and center hole positioning device is used for a group of tests, the consistency and accuracy of the test conditions are high, and the reliability of the test data is significantly improved. 3) The drilling is completed during the manufacturing process of the similar material model 5, and separate drilling processing is not required, which effectively prevents damage caused by multiple model handling and shortens the preparation time. 4) It can be widely applied to the preparation process of similar material models 5 such as drilling and water injection, drilling and grouting.

[0106] The following exemplary describes the use method of the similar material model pouring and center hole positioning device of the embodiments of the present application: 1) Mould 1 assembly. When the mould 1 is assembled, the length A and height H of the model are determined by the long edge template 11, and the width B of the model is determined by the wide edge template 12. The long edge template 11 is inserted into the long edge through slot of the bottom plate 13, then the wide edge template 12 is inserted into the wide edge clamping groove of the bottom plate 13 and the clamping groove of the long edge template 11, after that, double-headed bolts are passed through both ends of the long edge template 11, and elastic washers and nuts are installed and tightened, the similar material model 5 mould 1 assembly is completed, and the height difference T1 between the long edge template 11 and the wide edge template 12, that is, T1 is the difference between the height of the wide edge template and the height of the long edge template.

[0107] 2) Centering assembly assembly. The centering main beam 21 and the centering auxiliary beam 22 are stacked in the same direction, the center hole is inserted into the centering sleeve 23, the angle of the centering main beam and the centering auxiliary beam is adjusted to be perpendicular, the centering auxiliary beam 22 is rotated to make the centering auxiliary beam 22 enter the installation clamping groove 233 (i.e., t3-1) at the small diameter end of the centering sleeve 23, the cylindrical head limiting screw is screwed into the limiting screw hole of the centering main beam 21, and the cylindrical end of the screw falls into the limiting screw hole of the centering auxiliary beam 22, the centering assembly assembly is completed, and the depth T2 from the main beam clamping groove positioning surface to the bottom surface of the auxiliary beam clamping groove is greater than the height difference T1 between the long edge template 11 and the wide edge template 12 after assembly.

[0108] 3) Drilling depth fixed-length assembly 3 assembly. The threaded end of the prefabricated drilling rod 32 is screwed into the double nut, the corresponding positioning clamping groove on the prefabricated drilling rod 32 is determined according to the drilling depth of the model, the small hole end of the positioning clamping ring is directed to the prefabricated drilling end of the prefabricated drilling rod 32, and the two parts are buckled in the same positioning clamping groove of the prefabricated drilling rod 32, and the drilling depth fixed-length assembly 3 is assembled.

[0109] 4) Model drilling positioning device overall assembly. Level the assembled mold 1, then install the centering assembly as a whole, and finally install the drilling depth fixed length assembly 3. The centering inner notch (B+2a) of the centering main beam 21 is clamped outside the two long side mold plates 11 of the mold 1, and the positioning inner notch (A+2a) of the centering auxiliary beam 22 is clamped outside the two wide side mold plates 12 of the mold 1, so that the bottom surface of the centering inner notch of the main beam coincides with the top surface of the two long side mold plates 11. Then insert the drilling depth fixed length assembly 3 into the centering sleeve 23 center hole of the centering assembly as a whole, so that the bottom end face of the positioning clasp ring coincides with the bottom end face of the inner hole of the centering sleeve 23, and the assembly is completed.

[0110] 5) Similar material model 5 and drilling are made at one time. After the similar material model pouring and the centering hole positioning device assembly are completed, the model is made and maintained according to the normal process. Before the model solidifies, the nut installed at the top of the pre-drilling rod 32 is used to rotate the pre-drilling rod 32 at irregular times to prevent the model from being bonded as a whole when it solidifies. After the model is completely solidified and reaches the preset strength, the pre-drilling rod 32 is pulled out, and the water drilling is formed. After the model maintenance reaches the test strength requirement, the drilling water fracturing test is directly carried out.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the present application, and are not limited to the present application. Although the present application is described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications or equivalent replacements of the technical solutions of the present application do not deviate from the spirit and scope of the present application, and should be covered in the scope of the claims of the present application.

Claims

1. A similar material model pouring and center hole positioning device, characterized in that, The application relates to a mold (1) for casting a similar material model (5), which comprises a containing cavity (14) formed by the mold (1) and an open upper end of the containing cavity (14); a drilling centering assembly (2) arranged at the open upper end of the containing cavity (14) and having a mounting hole corresponding to the center position of the cross section of the containing cavity (14); and a drilling depth limiting assembly (3) comprising a limiting piece (31) and a drilling rod (32), wherein the limiting piece (31) is connected to the drilling rod (32) at a preset position, and the limiting piece (31) is arranged at the mounting hole so that the lower end of the drilling rod (32) extends into the containing cavity (14). The mold (1) comprises two long side templates (11), two wide side templates (12) and a bottom plate (13), and the long side templates (11), the wide side templates (12) and the bottom plate (13) form the containing cavity (14). The bottom plate (13) is provided with a first positioning clamping groove (131) matched with the long side templates (11) and the wide side templates (12). One of the long side templates (11) and the wide side templates (12) is provided with a second positioning clamping groove (111) matched with the other.

2. The similar material model pouring and center hole positioning device according to claim 1, characterized in that, The drilling centering assembly (2) comprises a centering main beam (21) and a centering auxiliary beam (22), wherein the two ends of the centering main beam (21) are connected with the two long side templates (11) respectively, and the two ends of the centering auxiliary beam (22) are connected with the two wide side templates (12) respectively. The mounting hole comprises a first mounting hole (211) arranged on the centering main beam (21) and a second mounting hole (221) arranged on the centering auxiliary beam (22). The drilling centering assembly (2) further comprises a centering sleeve (23) arranged in the first mounting hole (211) and the second mounting hole (221) to connect the centering main beam (21) and the centering auxiliary beam (22).

3. The similar material model pouring and center hole positioning device of claim 2, wherein, The centering sleeve (23) is provided with a first mounting boss (232) matched with the first mounting hole (211) to abut and fix the centering sleeve (23) on the centering main beam (21), a mounting clamping groove (233) matched with the second mounting hole (221) to fix the centering auxiliary beam (22) at the mounting clamping groove (233), and a second mounting boss (234) matched with the limiting piece (31) to mount the drilling rod (32) on the drilling centering assembly (2). The lower end of the centering sleeve (23) is provided with an avoiding empty area (235) matched with the shape of the second mounting hole (221).

4. The similar material model pouring and center hole positioning device according to claim 3, characterized in that, The avoiding empty area (235) is communicated with the mounting clamping groove (233), so that the centering auxiliary beam (22) is clamped into the mounting clamping groove (233) through the avoiding empty area (235). ​ 5. The similar material model pouring and center hole positioning device of claim 4, wherein, ​ ​ ​ ​ 6. The similar material model pouring and center hole positioning device of claim 5, wherein, ​ ​ 7. The similar material model pouring and center hole positioning device of claim 3, wherein, Two ends of the centering main beam (21) are provided with first bending parts (212) which are matched with the back side of the long side mold plate (11) away from the accommodating cavity (14); The first bending part (212) comprises a stepped clamping groove (213) with a guide inclined surface (214), and the top corner of the stepped clamping groove (213) is abutted with the upper end of the long side mold plate (11); Two ends of the centering auxiliary beam (22) are provided with second bending parts (222) which are matched with the back side of the wide side mold plate (12) away from the accommodating cavity (14).

8. The similar material model pouring and center hole positioning device of claim 2, wherein, The mold (1) further comprises a connecting rod (4); The long side mold plate (11) is provided with a fixing hole (112), and two ends of the connecting rod (4) are respectively connected in the fixing holes (112) of the two long side mold plates (11) to clamp the two long side mold plates (11).

9. The similar material model pouring and center hole positioning device according to any one of claims 1 to 8, characterized in that, The drilling rod (32) is provided with a plurality of limiting clamping grooves (321) along the length direction of the drilling rod (32), and one of the plurality of limiting clamping grooves (321) is matched with the limiting piece (31) to adjust the length of the lower end of the drilling rod (32) extending into the accommodating cavity (14).

10. The similar material model pouring and center hole positioning device of claim 9, wherein, The limiting piece (31) comprises a first half ring (311) and a second half ring (312), and the first half ring (311) and the second half ring (312) are both provided with limiting parts (313) matched with the limiting clamping grooves (321); The first half ring (311) and the second half ring (312) are buckled to form a ring structure to be sleeved on the drilling rod (32).

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