A rock crack stiffness measuring device, measuring method and measuring system

Abstract

The present application relates to the technical field of rock mechanics testing, and discloses a rock crack stiffness measuring device, a measuring method and a measuring system. The rock crack stiffness measuring device comprises a main body and a plurality of jackscrews. The main body comprises at least three fixing rings. The three fixing rings are arranged along the axial direction of the fixing rings to form a receiving cavity for receiving rock. An opening is formed on the fixing ring and communicates with the receiving cavity. Two adjacent openings are located on the same side of the central axis of the fixing ring to form an observation window. The number of the observation windows is at least two. The plurality of jackscrews are arranged along the circumferential direction of the fixing ring. The fixing ring is provided with an assembly hole along the radial direction of the fixing ring. The jackscrew is screwed with the assembly hole. The end of the jackscrew facing the central axis of the fixing ring is used to abut against the side surface of the rock. The present application solves the problem that the complete rock sample and the rock sample containing cracks are not taken from the same rock block, so it is difficult to completely eliminate the influence caused by the material heterogeneity, the difference in micro-crack distribution and the inconsistency of the end surface flatness.

Description

Technical Field

[0001] This invention relates to the field of rock mechanics testing technology, and in particular to a measuring device, measuring method and measuring system for measuring rock fracture stiffness. Background Technology

[0002] Fractures, as a common structure in Earth's crust, significantly influence a series of key responses, including the mechanical properties, hydrological characteristics, and seismic behavior of rock masses. Among these influencing parameters, fracture stiffness is an important indicator for evaluating the ability of rock fractures to resist deformation under normal external forces. It is commonly used to predict the mechanical responses of rocks, such as fracture characteristics and seepage behavior, and therefore has wide applications in underground engineering, mining, oil and gas development, and earthquake engineering.

[0003] Currently, traditional methods for measuring the normal stiffness of cracks primarily employ the dual-sample comparison method. This method requires preparing a complete rock sample and a rock sample containing artificial or natural cracks, and independently measuring their axial deformation under the same normal stress loading conditions. By comparing the deformation differences between the two samples under the same stress level, the additional deformation caused by the crack region is estimated, and then the normal stiffness of the crack is calculated in conjunction with the change in normal stress. Although this method is intuitive and relatively simple to operate, it carries a significant risk of systematic error. Since the complete rock sample and the cracked rock sample are not taken from the same rock block, even if the lithology is similar, it is still difficult to completely eliminate the influence of material heterogeneity, differences in microcrack distribution, and inconsistent end-face flatness. In addition, factors such as sample size processing deviations, loading center alignment errors, and boundary friction effects may also interfere with the strain measurement results, leading to distorted crack deformation assessments, and thus affecting the reliability and repeatability of the stiffness calculation results.

[0004] Therefore, how to develop crack stiffness measurement technology with stronger anti-interference ability based on existing methods and improve its data reliability and experimental repeatability has become a key problem that urgently needs to be solved in the field of rock mechanics and engineering. Summary of the Invention

[0005] This invention provides a device, method, and system for measuring rock fracture stiffness, which addresses at least one of the shortcomings in the existing rock fracture stiffness measurement process and improves the reliability and repeatability of rock fracture stiffness measurement.

[0006] This invention provides a device for measuring the stiffness of rock fractures, comprising: The main body includes at least three fixing rings; the three fixing rings are arranged at intervals along their own axial direction to form a receiving cavity for receiving rocks; the fixing rings are provided with openings communicating with the receiving cavities, and two adjacent openings are located on the same side of the central axis of the fixing rings to form observation windows, and the number of observation windows is at least two. Multiple set screws are arranged at intervals along the circumference of the fixing ring; the fixing ring has mounting holes constructed radially, and the set screws are threaded into the mounting holes. The end of the set screw facing the central axis of the fixing ring is used to abut against the side of the rock.

[0007] The rock fracture stiffness measuring device provided by the present invention further includes: The guide positioning rod has a through hole along its own axial direction, and the guide positioning rod is slidably assembled in the through hole.

[0008] According to the rock fracture stiffness measuring device provided by the present invention, there are multiple guide positioning rods, which are arranged circumferentially around the fixing ring.

[0009] According to the rock fracture stiffness measuring device provided by the present invention, the fixing ring comprises: Connecting plate; Two mounting plates; one end of the two mounting plates faces each other to form the opening, and the other ends of the two mounting plates are connected by the connecting plate to form the retaining ring.

[0010] According to the rock fracture stiffness measuring device provided by the present invention, the radial dimension of the mounting plate is larger than the radial dimension of the connecting plate.

[0011] The rock fracture stiffness measuring device provided by the present invention further includes: At least two LVDT sensor groups are provided, each corresponding to one of the observation windows; each LVDT sensor group includes at least one LVDT sensor; the LVDT sensor groups are mounted on the fixing ring, and the LVDT sensor groups are used to detect the normal deformation of the rock within the corresponding observation window.

[0012] According to the rock fracture stiffness measuring device provided by the present invention, the LVDT sensor group includes two LVDT sensors; the two LVDT sensors are symmetrically mounted on the fixed ring with the central axis of the fixed ring as the axis of symmetry.

[0013] The rock fracture stiffness measuring device provided by the present invention further includes: A DIC camera is used to acquire images of the rocks within the observation window; The control module is electrically connected to the LVDT sensor and the DIC camera.

[0014] A second aspect of the present invention provides a method for measuring the stiffness of rock fractures, employing the rock fracture stiffness measuring device described in any one of the preceding claims, the method comprising: After placing the rock into the receiving cavity of the testing device according to the testing requirements, during the process of applying normal stress to the rock, the first deformation information of the complete area of ​​the rock and the second deformation information of the crack area of ​​the rock are acquired simultaneously; the first deformation information includes the first normal deformation amount and the first image information of the complete area, and the second deformation information includes the second normal deformation amount and the second image information of the crack area. Based on the first normal deformation and the first image information, the first actual normal deformation of the intact rock region is determined; based on the second normal deformation and the second image information, the second actual normal deformation of the rock crack region is determined. The rock fracture stiffness is determined based on the first actual normal deformation, the second actual normal deformation, and the normal stress increment.

[0015] The method for measuring rock fracture stiffness according to the present invention further includes, before placing the rock into the receiving cavity of the testing device according to the testing requirements: Determine the parallelism between two adjacent fixed rings; If the parallelism is less than the parallelism threshold, place the rock in the containment cavity according to the test requirements.

[0016] A third aspect of the present invention provides a measurement system for the mechanical properties of rocks under humid conditions, including the rock fracture stiffness measuring device described in any of the preceding claims.

[0017] The rock fracture stiffness measuring device provided by this invention forms a receiving cavity by setting at least three fixing rings spaced apart along the axial direction to fix a single rock sample. Simultaneously, by opening at least two observation windows, it is possible to align the "intact region" and "fractured region" of the same sample separately. This solves the problem that traditional intact rock samples and fractured rock samples are not taken from the same rock block, making it difficult to completely eliminate the influence of material heterogeneity, differences in micro-fracture distribution, and inconsistent end-face flatness. Multiple set screws are threaded onto the fixing rings and abut against the side of the rock. When the rock undergoes axial deformation under normal stress, the deformation of the rock directly causes the fixing rings it contacts to undergo an equal axial displacement due to the tightening effect of the set screws. Therefore, the normal deformation of the rock between two fixing rings can be converted into the relative axial displacement between these two fixing rings. This provides a reliable mechanical basis for subsequent sensor installation to measure local deformation. In summary, this invention establishes a basic framework for simultaneously monitoring the zonal deformation of both intact and fractured regions on a single rock sample. This solves the systematic error problem caused by sample differences in traditional dual-sample comparison methods, improving the reliability and repeatability of rock fracture stiffness measurement. Furthermore, through its "top screw-fixed ring" structure, it can convert the normal deformation of a specific section of the rock into the relative axial displacement between the fixed rings, providing a reliable mechanical basis for subsequent high-precision sensor measurements.

[0018] The rock fracture stiffness measurement method provided by the present invention uses the rock fracture stiffness measurement device described above, and therefore has at least the advantages mentioned above, which will not be repeated here.

[0019] The rock mechanical properties measurement system provided by the present invention includes the above-mentioned rock crack stiffness measurement device, and therefore has at least the above-mentioned advantages, which will not be repeated here. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the rock fracture stiffness measuring device provided by the present invention.

[0022] Figure 2 yes Figure 1 A schematic diagram of the rock fracture stiffness measuring device and its assembly structure.

[0023] Figure 3yes Figure 1 A schematic diagram of the structure of the provided rock fracture stiffness measuring device from a top-down perspective.

[0024] Figure 4 This is a flowchart illustrating the method for measuring rock fracture stiffness provided by the present invention.

[0025] Figure 5 This is a schematic diagram of the structure of the rock mechanical properties measurement system provided by the present invention for use in humid environments.

[0026] Figure 6 This is a cross-sectional structural diagram of the housing of the measurement system for rock mechanical properties under humid conditions provided by the present invention.

[0027] Figure 7 This is a schematic diagram of the mechanical loading module of the measurement system for the mechanical properties of rocks under humid conditions provided by the present invention.

[0028] Figure 8 yes Figure 7 A magnified structural diagram of point A in the middle.

[0029] Figure 9 This is a schematic diagram of the three-point loading indenter device of the rock mechanical properties measurement system provided by the present invention for use in humid environments.

[0030] Figure 10 This is a flowchart illustrating the method for measuring the mechanical properties of rocks under humid conditions provided by the present invention.

[0031] Figure label: 100. Main body; 110. Fixing ring; 101. Receiving cavity; 102. Opening; 111. Connecting plate; 112. Mounting plate; 200, set screw; 300, guide positioning rod; 400, LVDT sensor; 10. Rock; 11. Intact area; 12. Cracked area; 610. Mechanical loading module; 611. Loading base; 612. Mechanical loading structure; 613. Driving component; 614. Mounting plate; 615. Support rod; 6121. First loading component; 6122. Second loading component; 620. Enclosure; 621. Heated glass; 622. Door opening and closing; 630. Three-point loading head device; 631. First connecting piece; 632. First loading head; 633. Second loading head; 640. Lifting platform; 650, DIC camera; 660. Detection module; 661. Axial strain sensor; 662. Radial strain sensor; 671. Ultrasonic generating pressure head; 672. Ultrasonic receiving pressure head. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0033] In the description of this specification, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are used only for the convenience of describing this specification. They do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this specification. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] In the description of this specification, it should be noted that, unless otherwise expressly 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 invention based on the specific circumstances.

[0035] In this specification, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of 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.

[0036] 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 specification. 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.

[0037] In the embodiments of this specification, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0038] like Figures 1 to 3 As shown, a specific embodiment of the first aspect of the present invention provides a method for measuring the stiffness of a rock fracture. This method for measuring the stiffness of a rock fracture includes a main body 100 and a plurality of set screws 200.

[0039] The main body 100 includes at least three retaining rings 110; the three retaining rings 110 are spaced apart along their own axial direction to form a receiving cavity 101 for receiving the rock 10; the retaining rings 110 are provided with openings 102 communicating with the receiving cavity 101, and two adjacent openings 102 are located on the same side of the central axis of the retaining rings 110 to form observation windows, and the number of observation windows is at least two. In other words, when the rock 10 is received in the receiving cavity 101, the intact area 11 and the cracked area 12 of the rock 10 correspond to two observation windows respectively. The three retaining rings 110 are spaced apart along their own axial direction, which is equivalent to forming two gaps; along the axial direction of the retaining rings 110, each gap is connected to an opening 102 on both sides.

[0040] Multiple set screws 200 are arranged circumferentially around the fixing ring 110. The fixing ring 110 has mounting holes constructed radially, and the set screws 200 are threaded into the mounting holes. The end of the set screw 200 facing the central axis of the fixing ring 110 is used to abut against the side of the rock 10. In other words, when the rock 10 is received in the receiving cavity 101, the rock 10 is fixed by the circumferentially spaced set screws 200, and the reaction force on the set screws 200 also allows the fixing ring 110 to be stably spaced axially. When the upper end face of the rock 10 is subjected to normal stress, the rock 10 will drive the upper fixing ring 110 to move downward, converting the normal deformation of the rock 10 into the axial displacement of the fixing ring 110. The normal deformation of the rock 10 can be measured by measuring the axial displacement of the fixing ring 110.

[0041] In this embodiment, the testing device forms a receiving cavity 101 by setting at least three fixing rings 110 spaced apart along the axial direction to fix a single rock sample 10. Simultaneously, by opening at least two observation windows, the "intact region 11" and "fractured region 12" can be aligned on the same sample, respectively. This directly solves the problem that intact rock samples and fractured rock samples are not taken from the same rock block, making it difficult to completely eliminate the influence of material heterogeneity, differences in micro-fracture distribution, and inconsistent end-face flatness. Multiple set screws 200 are threaded onto the fixing rings 110 and abut against the side of the rock 10. When the rock 10 undergoes axial deformation under normal stress, the deformation of the rock 10 directly causes the fixing rings 110 in contact with it to undergo an equal axial displacement due to the tightening effect of the set screws 200. Therefore, the normal deformation of the rock 10 between two fixing rings 110 is converted into the relative axial displacement between these two fixing rings 110. This provides a reliable mechanical basis for subsequent sensor installation to measure local deformation. In summary, this embodiment constructs a basic framework capable of simultaneously monitoring the zonal deformation of both the intact region 11 and the cracked region 12 on a single rock sample 10. This solves the systematic error problem caused by sample differences in the traditional dual-sample comparison method, improving the measurement reliability and experimental repeatability of the crack stiffness of the rock 10. Furthermore, through the structure of "top screw 200 - fixing ring 110," it can convert the normal deformation of a specific section of the rock 10 into the relative axial displacement between the fixing rings 110, providing a reliable mechanical basis for subsequent sensor measurements.

[0042] In some embodiments of the present invention, the rock fracture stiffness measuring device includes a guide positioning rod 300; the fixing ring 110 has a through hole along its own axial direction, and the guide positioning rod 300 is slidably fitted into the through hole. Essentially, the guide positioning rod 300 is added to the above embodiments. The guide positioning rod 300 passes through all the fixing rings 110, acting like a "skeleton," forcing all the fixing rings 110 to remain coaxial and parallel to each other during installation. This facilitates rapid adjustment of the parallelism between adjacent fixing rings 110, laying the foundation for subsequent measurements. During the application of normal stress, the deformation of the rock 10 may not be completely uniform, and may produce slight tilting or torsion. Without the guide positioning rod 300, the fixing rings 110 may tilt accordingly, resulting in the measured displacement not being a purely normal deformation.

[0043] Optionally, the outer surface of the guide positioning rod 300 is smooth to reduce the friction of the guide positioning rod 300 retaining ring 110.

[0044] Furthermore, there are multiple guide positioning rods 300, which are arranged circumferentially around the fixing ring 110.

[0045] While a single guide positioning rod 300 provides basic guidance, the fixed ring 110 may still experience slight rotation around the rod or gap wobble in the direction perpendicular to the rod. However, using multiple (e.g., three or four) circumferentially distributed guide positioning rods 300 effectively forms a multi-point supported cage-like guide structure. This structure simultaneously constrains the fixed ring 110 from multiple directions, preventing it from tilting or rotating in any direction, thus ensuring greater stability and maintaining parallelism and purely axial movement among the fixed rings 110. In other words, by employing multiple circumferentially spaced guide positioning rods 300, the guiding stability and anti-overturning capability of the fixed ring 110 are enhanced. Compared to a single guide rod, its guiding effect is superior, further improving measurement accuracy and reliability.

[0046] In some embodiments of the present invention, the fixing ring 110 includes a connecting plate 111 and two mounting plates 112. One end of each mounting plate 112 faces each other to form an opening 102, and the other ends of the two mounting plates 112 are connected by the connecting plate 111 to form the fixing ring 110. Essentially, the fixing ring 110 is designed as a structure formed by splicing two mounting plates 112 and a connecting plate 111, with the opposite ends of the two mounting plates 112 naturally forming the opening 102 (i.e., part of the observation window). This design allows the two sides of the opening 102 area (i.e., the mounting plates 112) to be designed as planes or platforms suitable for instrument mounting. Compared to directly cutting the opening 102 into a complete ring, this split design is more direct and convenient in terms of manufacturing and functional implementation. In other words, this structure composed of the connecting plate 111 and two mounting plates 112 provides a clear, convenient, and stable structural foundation for the formation of the observation window and the installation of the measuring sensor, exhibiting good engineering feasibility.

[0047] Optionally, the mounting plate 112 and the connecting plate 111 are integrally formed, which can reduce the number of connection points and reduce the risk of stress concentration.

[0048] Optionally, the mounting plate 112 and the connecting plate 111 can also be connected together by welding, tenon and mortise joints, or other methods.

[0049] Furthermore, the radial dimension of the mounting plate 112 is larger than that of the connecting plate 111. The opening 102 on the retaining ring 110 disrupts its original mass symmetry, causing its center of gravity to deviate from the central axis. In a free state without external support, this eccentricity causes the retaining ring 110 to tilt naturally. Limiting the radial dimension of the mounting plate 112 (the side closer to the opening 102) to be larger than that of the connecting plate 111 (the side farther from the opening 102) is equivalent to adding a counterweight on the side of the opening 102, or reducing the weight on the opposite side. This design can actively adjust the weight distribution of the retaining ring 110, bringing its center of gravity back to or very close to the central axis. This ensures that the entire measuring device remains vertical and stable after assembly, avoiding tilting due to its own weight, thereby preventing the application of additional lateral forces or bending moments to the rock 10 and ensuring the purity of the test conditions.

[0050] In addition, sensors (such as LVDTs, camera mounts, etc.) typically require a certain amount of installation space and a sturdy support surface. Making the mounting plates 112 on both sides of the viewing window wider (larger radial dimension) can directly provide these sensors with ample mounting area and stronger structural rigidity. Meanwhile, the rest of the ring (connecting plate 111) can maintain a smaller radial dimension to reduce overall weight and material costs, achieving a good balance between structural strength and lightweight.

[0051] In some embodiments of the present invention, the rock fracture stiffness measuring device further includes at least two LVDT sensor groups. Each LVDT sensor group corresponds to an observation window; each LVDT sensor group includes at least one LVDT sensor 400; the LVDT sensor groups are mounted on a fixing ring 110 and are used to detect the normal deformation of the rock 10 within the corresponding observation window. In other words, one LVDT sensor group is used to detect the normal deformation of the intact region 11 of the rock 10 within the corresponding observation window, and the other LVDT sensor group is used to detect the normal deformation of the fractured region 12 of the rock 10 within the corresponding observation window.

[0052] In this embodiment, the LVDT sensor 400 is a high-precision displacement sensor. Installed between adjacent fixing rings 110 and corresponding to the observation windows (i.e., the intact region 11 and the cracked region 12), it allows direct measurement of the normal deformation of the rock 10 in these two regions under pressure (i.e., the relative displacement between the fixing rings 110). This provides the core raw data needed to calculate stiffness.

[0053] Furthermore, the LVDT sensor group includes two LVDT sensors 400; the two LVDT sensors 400 are symmetrically mounted on the fixing ring 110 with the central axis of the fixing ring 110 as the axis of symmetry. By symmetrically mounting two LVDT sensors 400 on a measurement cross-section, deformation data from both sides of the cross-section can be obtained simultaneously. The normal deformation detected by the two LVDT sensors 400 can be averaged to improve measurement accuracy. If the rock 10 undergoes slight non-uniform deformation or the fixing ring 110 has a slight tilt, one of the symmetrically arranged sensors will read too high and the other too low. Taking the average of their readings can offset this error, yielding an average deformation closer to the actual situation.

[0054] From the perspective of measurement principles, traditional measurement methods mainly rely on single deformation monitoring means, such as linear variable differential transformers (LVDTs) or strain gauges. Their basic logic is to measure the overall deformation of a fractured rock sample, subtract the deformation contribution of an intact rock sample under the same conditions, and thus infer the deformation of the fracture itself, ultimately calculating the normal stiffness—that is, the amount of normal closure of the fracture caused by a unit normal stress. However, this approach has several limitations: first, it does not fully consider the influence of the anisotropy of the rock material on the deformation response; second, the obtained deformation is actually the average value of the entire sample, making it difficult to characterize the non-uniform closure behavior that may occur on the fracture surface during normal compression; third, traditional measurements usually ignore the potential influence of environmental factors (such as temperature fluctuations, humidity changes, pore water pressure, etc.) on the mechanical behavior of the fracture. Especially in actual rock masses with complex fracture morphology or significant environmental disturbances, traditional techniques often struggle to obtain true and comprehensive information on fracture deformation.

[0055] To address the aforementioned problems, in some embodiments of the present invention, the rock fracture stiffness measuring device further includes a DIC camera and a control module. The DIC camera is used to acquire images of the rock 10 within the observation window. In other words, the DIC camera is used to acquire images of the complete region 11 and the fractured region 12 of the rock 10, respectively. The control unit is electrically connected to the LVDT sensor 400 and the DIC camera.

[0056] In this embodiment, the DIC camera (Digital Image Correlation Camera) can obtain two-dimensional deformation field information of the entire area within the observation window by analyzing the changes in the speckle pattern on the surface of rock 10. This complements the single-point (or two-point averaging) measurement of LVDT. The control module synchronously acquires the "point" deformation data from LVDT and the "field" deformation data from DIC. The "virtual normal deformation" corresponding to the LVDT measurement point position can be extracted from the image information (DIC data) and compared with the normal deformation directly measured by LVDT. If the two are consistent, the measurement is reliable; if the difference is too large, it may indicate a measurement anomaly (such as sensor slippage, electrical signal interference, etc.), and the data point can be discarded. This "point-field combination" verification mechanism solves the problem that traditional methods cannot prove their data quality and improves the reliability of the data.

[0057] Optionally, the control module includes an information acquisition unit, a first determination unit, and a second determination unit.

[0058] The information acquisition unit is used to simultaneously acquire first deformation information of the complete region 11 and second deformation information of the cracked region 12 during the application of normal stress to the rock 10. The first deformation information includes the first normal deformation amount of the complete region 11 of the rock 10 and first image information, and the second deformation information includes the second normal deformation amount of the cracked region 12 of the rock 10 and second image information. In other words, both the first deformation information and the second deformation information are timestamped. Specifically, the information acquisition unit can obtain the first normal deformation amount with a timestamp, the first image information with a timestamp, the second normal deformation amount with a timestamp, and the second image information with a timestamp.

[0059] Optionally, the LVDT sensor 400 in the measuring device can be used to collect the first normal deformation and the second normal deformation. The information acquisition unit obtains the first normal deformation and the second normal deformation at different times from the LVDT sensor 400. Then, the normal deformation is correlated with time to obtain the first normal deformation and the second normal deformation with timestamps.

[0060] Optionally, a DIC camera in the test device can be used to acquire first image information and second image information; the information acquisition unit acquires first image information and second image information at different times from the DIC camera; then, by associating the image information with time, first image information and second image information with timestamps can be obtained.

[0061] The first determining unit is used to determine the first actual normal deformation of the complete region 11 of the rock 10 based on the first normal deformation and the first image information; and to determine the second actual normal deformation of the crack region 12 of the rock 10 based on the second normal deformation and the second image information.

[0062] The second determining unit is used to determine the stiffness of the rock 10 crack based on the first actual normal deformation, the second actual normal deformation, and the normal stress increment.

[0063] In this embodiment, the functions of the control module are specifically divided into an information acquisition unit, a first determination unit, and a second determination unit. The advantage of this modular functional limitation is that by constructing a closed-loop data processing flow of "synchronous acquisition-cross-validation-calculation", the measurement system is upgraded from a simple "data recorder" to an "intelligent analysis system" with self-diagnosis and correction capabilities, thereby ensuring the high reliability and objectivity of the final results.

[0064] The LVDT sensor 400 is a "point" measurement tool based on the principle of electromagnetic induction. It boasts high accuracy and fast frequency response, but it cannot reflect the overall deformation of a region and may fail due to loose mounting points. The DIC camera is a "field" measurement tool based on image correlation algorithms. It can provide the full-field deformation distribution, but it is sensitive to illumination and speckle quality, and data processing is relatively complex. These two technologies are completely independent in their physical principles. The task of the first determining unit is to "determine" the first actual normal deformation based on the first normal deformation of the LVDT and the first image information of the DIC. This inherently implies a comparison and verification process. For example, the control module can extract the "virtual deformation" that perfectly corresponds to the LVDT measurement point location from the full-field deformation data of the DIC. Then, this "virtual deformation" is compared in real time with the "physical deformation" directly measured by the LVDT. If the two are highly consistent, it proves that the two independent measurement methods have reached the same conclusion, and the confidence level of the data point is extremely high. If a significant deviation occurs between the two, the system can immediately identify measurement anomalies, such as slippage of the LVDT sensor 400 or failure of the DIC speckle due to crack propagation. Through this cross-validation, the system can filter out unreliable data points and only adopt valid data that has been double-verified, thus obtaining a much more reliable actual normal deformation than data from a single source.

[0065] In traditional measurement devices, a sensor malfunction can cause the entire experiment to fail or yield erroneous conclusions without the operator's knowledge. However, the first determining unit in this embodiment imbues it with "intelligence." As mentioned earlier, by comparing LVDT and DIC data, the system can automatically identify "bad pixels" and mark or remove them—this is fundamental robustness. Furthermore, this architecture also provides the possibility of data correction. For example, if the LVDT signal exhibits a brief spike due to electromagnetic interference, while the DIC data shows a smooth and continuous deformation, the algorithm of the first determining unit can determine that the LVDT data is abnormal and use the DIC data for interpolation correction. Conversely, if a frame of image calculation fails due to a sudden change in illumination, while the LVDT data remains continuous, the LVDT data can be trusted. This primary / backup redundancy and intelligent optimization capability allows the system to output stable, continuous, and reliable results even in complex experimental environments and with occasional failures, significantly enhancing system robustness.

[0066] The deformation and failure of rock 10 is a dynamic process, and the stress application and deformation response are tightly coupled in time. The information acquisition unit ensures that at any given moment, we can know the normal stress, LVDT reading of the intact region, deformation contour map of the intact region, LVDT reading of the fractured region, and deformation contour map of the fractured region by uniformly timestamping all data streams (intact region and fractured region) from LVDT and DIC.

[0067] Without strict synchronization and timestamps, data exported from different devices may have time delays or sampling rate differences. This could lead to incorrect correlation between stress at time A and deformation at time B, resulting in completely wrong stiffness calculations. This embodiment eliminates the possibility of such causal mismatch from the source of data acquisition, ensuring the effectiveness of subsequent analysis.

[0068] In this embodiment, the overall architecture of the control unit is clearly divided into an information acquisition unit, a first determination unit, and a second determination unit. This division defines a clear and fixed data flow and processing logic. Data is automatically collected, automatically verified and purified, and then automatically used for final calculations. The entire process requires little or no manual intervention, improving experimental efficiency and freeing researchers from tedious data alignment and screening tasks.

[0069] In traditional methods, researchers may need to rely on "experience" to determine whether a data point is "usable." This embodiment, however, embeds the judgment criteria into the algorithm of the first determining unit, replacing subjective human judgment with an objective algorithm. This ensures that the data processing standards are completely consistent for each experiment, thereby improving the objectivity and repeatability of the results. The second determining unit then executes a standardized stiffness calculation formula based on the high-quality data provided by the preceding units, guaranteeing the accuracy of the final calculation.

[0070] It should be noted that a specific embodiment of the second aspect of the present invention provides a method for testing the stiffness of rock fractures. The executing entity of this testing method can be a controller, or it can be applied to a cloud platform in the Internet field, or other types of cloud platforms in the Internet field, or it can also be applied to third-party devices. These third-party devices may include various types such as mobile phones, tablets, laptops, in-vehicle computers, and other smart terminals.

[0071] like Figure 4 As shown, a specific embodiment of the second aspect of the present invention provides a method for testing the stiffness of rock fractures. This testing method requires the rock fracture stiffness testing apparatus of any of the above embodiments. The testing method includes: S110. After placing the rock in the receiving cavity of the testing device according to the testing requirements, during the process of applying normal stress to the rock, the first deformation information of the complete area of ​​the rock and the second deformation information of the cracked area of ​​the rock are acquired simultaneously. The first deformation information includes the first normal deformation amount and the first image information of the complete area, and the second deformation information includes the second normal deformation amount and the second image information of the cracked area.

[0072] Optionally, an LVDT sensor in the measuring device can be used to collect the first normal deformation and the second normal deformation. The controller obtains the first normal deformation and the second normal deformation at different times from the LVDT sensor. Then, the normal deformation is correlated with time to obtain the first normal deformation and the second normal deformation with timestamps.

[0073] Optionally, a DIC camera in the test device can be used to acquire first image information and second image information; the controller obtains first image information and second image information at different times from the DIC camera; then, the image information is correlated with time to obtain first image information and second image information with timestamps.

[0074] S120. Based on the first normal deformation and the first image information, determine the first actual normal deformation of the intact rock region; based on the second normal deformation and the second image information, determine the second actual normal deformation of the rock crack region.

[0075] Optionally, after acquiring data from both the LVDT sensor and the DIC camera, the controller can extract a "virtual deformation" that perfectly corresponds to the LVDT measurement point location from the full-field deformation data of the DIC. This "virtual deformation" is then compared in real-time with the "physical deformation" directly measured by the LVDT. If they match closely, it proves that the two independent measurement methods have reached the same conclusion, indicating a very high confidence level for the data point. The system then outputs the current normal deformation as the actual normal deformation. If there is a significant deviation, the system can immediately identify measurement anomalies, such as possible slippage of the LVDT sensor or failure of the DIC speckle due to crack propagation. Through this cross-validation, the system can filter out unreliable data points and only adopt valid data that has undergone double verification, resulting in an actual normal deformation that is far more reliable than data from a single source.

[0076] Specifically, the controller can acquire first image information (i.e., full-field deformation data) from the DIC camera corresponding to the complete area of ​​the rock, and extract the "virtual deformation" that perfectly corresponds to the LVDT sensor measurement point position of the complete area. Then, this "virtual deformation" is compared in real time with the "physical deformation" (i.e., the first normal deformation) directly measured by the LVDT. If the two are highly consistent, it proves that the two independent measurement methods have reached the same conclusion, and the confidence level of this data point is extremely high. This first normal deformation is then taken as the first actual normal deformation. If there is a significant deviation between the two, it indicates that the acquired data is unreliable and can be discarded, thus improving the accuracy and reliability of the data measurement.

[0077] Specifically, the controller can acquire second image information (i.e., full-field deformation data) from the DIC camera corresponding to the crack area in the rock, and extract the "virtual deformation" that perfectly corresponds to the LVDT sensor measurement point position of the complete area. Then, this "virtual deformation" is compared in real time with the "physical deformation" (i.e., the second normal deformation) directly measured by the LVDT. If the two are highly consistent, it proves that the two independent measurement methods have reached the same conclusion, and the confidence level of this data point is extremely high; therefore, this second normal deformation is taken as the second actual normal deformation. If there is a significant deviation, it indicates that the acquired data is unreliable and can be discarded, thus improving the accuracy and reliability of the data measurement.

[0078] S130. Based on the first actual normal deformation, the second actual normal deformation, and the normal stress increment, determine the rock fracture stiffness.

[0079] Specifically, the controller uses the difference between the second actual normal deformation and the first actual normal deformation as the normal deformation of the crack region; then, it uses the ratio of the normal stress increment to the normal deformation of the crack region as the crack stiffness.

[0080] The method in this embodiment uses the rock fracture stiffness measuring device of any of the above embodiments, and therefore has at least any of the above advantages, which will not be repeated here.

[0081] Obviously, the test method in this embodiment uses the same rock when testing the stiffness of rock cracks. This solves the problem that intact rock samples and cracked rock samples are not taken from the same rock block, making it difficult to completely eliminate the influence caused by material heterogeneity, differences in microcrack distribution, and inconsistent end face flatness.

[0082] It should be noted that "placing the rock in the receiving cavity of the testing device according to the testing requirements" means that when placing the rock in the receiving cavity, the intact area and the cracked area of ​​the rock correspond to two different observation windows. In other words, the testing requirement is that the intact area and the cracked area of ​​the rock are located within different observation windows.

[0083] In some embodiments of the present invention, the method for measuring rock fracture stiffness further includes, before placing the rock into the receiving cavity of the testing device according to the testing requirements: Determine the parallelism between two adjacent fixed rings; If the parallelism is less than the parallelism threshold, place the rock in the containment cavity according to the test requirements.

[0084] Essentially, this adds a pre-inspection step to the above embodiment, namely, checking and ensuring that the parallelism between adjacent fixing rings meets the requirements. This is an important quality control step, which can reduce the impact of initial assembly errors on measurement results, thereby further ensuring the standardization of the entire testing process and the accuracy of the final results.

[0085] If the two adjacent fixing rings of the testing device are not parallel during initial installation, the displacement measured in the early stages of loading will partly come from correcting this initial parallelism error, rather than from actual rock deformation. This will introduce an initial systematic error into the entire measurement process. By explicitly requiring parallelism checks before testing and setting a parallelism threshold, it is ensured that the measurement starts from a geometrically defined "zero point," avoiding the misinterpretation of equipment assembly errors as rock deformation data, thereby improving measurement accuracy from the outset.

[0086] like Figures 5 to 9 As shown, a third aspect of the present invention provides a measurement system for the mechanical properties of rocks under humid conditions. The measurement system includes a mechanical loading module 610, a housing 620, and an environmental control module.

[0087] The mechanical loading module 610 is used to apply and unload normal stress to the rock 10. In other words, the mechanical loading module 610 can apply and control the stress acting on the rock 10 sample to simulate the complex stress environment in the earth's crust. Its loading and unloading capabilities can reproduce the real working conditions of stress increase, decrease or cyclic change.

[0088] The housing 620 has an internal cavity, and an inlet / outlet on one side, each equipped with a door 622. The housing 620 has a first position and a second position. In the first position, at least a portion of the mechanical loading module 610 is located inside the cavity; in the second position, the mechanical loading module 610 is located outside the cavity. In other words, the relative position of the housing 620 and the mechanical loading module 610 can be changed by adjusting the position of the housing 620. For example, during the movement of the housing 620 from the second position to the first position, at least a portion of the mechanical loading module 610 (i.e., the portion used to load the rock 10) enters the cavity through the inlet / outlet, and then the door 622 is closed. During the movement of the housing 620 from the first position to the second position, the door 622 is opened, and the mechanical loading module 610 exits the cavity through the inlet / outlet. This movable housing 620 design provides the testing system with greater flexibility. When the enclosure 620 is in the second position, the mechanical loading module 610 can be used as a conventional mechanical testing machine; however, when the enclosure 620 moves to the first position to enclose the core loading component, the system transforms into a powerful environmental-mechanical coupling testing platform. This design not only broadens the application range of the equipment and improves its utilization rate, but also, compared to designs that integrate the entire loading system into an environmental enclosure, this structure facilitates sealing and environmental control, reducing design and manufacturing costs.

[0089] The environmental control module includes a temperature regulation unit and a humidity regulation unit, both located within the enclosure 620. The temperature regulation unit regulates the temperature within the containment cavity, and the humidity regulation unit regulates the humidity within the containment cavity. In other words, during the process of applying normal stress to the rock 10 using the mechanical loading module 610 located within the containment cavity of the enclosure 620, the temperature of the containment cavity can be adjusted by the temperature regulation unit, and the humidity of the containment cavity can be adjusted by the humidity regulation unit, providing different temperature and humidity environments for the rock 10. This facilitates the study of the influence of humidity on the mechanical properties of the rock 10. The environmental control module can independently or collaboratively regulate temperature and humidity within the sealed containment cavity, thereby creating a stable, controllable, and reproducible specific temperature and humidity environment for the rock 10 sample. This is crucial for systematically studying the influence of humidity changes (such as continuous high humidity, wet-dry cycles, etc.) on the mechanical properties of the rock 10 (such as strength, deformation, and damage evolution), solving the problem that traditional experiments cannot simulate real multi-field coupled environments.

[0090] In this embodiment, by setting up a movable enclosure 620 that can cooperate with the mechanical loading module 610 and configuring an environmental control module, a multi-field coupled test system integrating temperature control, humidity regulation, and mechanical loading is constructed to realistically and controllably reproduce the humidity-stress coupling evolution process experienced by rock masses under natural environments in a laboratory setting. This system is ingeniously designed, efficiently combining mechanical loading and environmental simulation functions. It can be used as a conventional mechanical testing machine as well as perform complex humidity-stress coupling tests, expanding the functionality and application range of the equipment. This system can test the mechanical behavior of rock masses under different humidity paths and load histories, thereby revealing the intrinsic mechanism of rock mass damage accumulation and failure under the synergistic effect of humidity and stress, providing experimental evidence and theoretical support for the long-term stability assessment of geotechnical engineering.

[0091] In some embodiments of the present invention, the mechanical loading module 610 includes a loading base 611, a mechanical loading structure 612, and a driving component 613.

[0092] The loading base 611 slides into the housing 620. This sliding fit design ensures that the mechanical loading module 610 can smoothly enter and exit the housing 620, guaranteeing smooth switching between the first and second positions and accurate positioning.

[0093] The mechanical loading structure 612 includes a first loading member 6121 and a second loading member 6122; the first loading member 6121 and the second loading member 6122 are arranged coaxially along the axial direction; the end of the first loading member 6121 away from the second loading member 6122 is mounted on the loading base 611. In other words, the rock 10 is arranged between the first loading member 6121 and the second loading member 6122, and the rock 10 is clamped by the first loading member 6121 and the second loading member 6122. This coaxially arranged loading structure ensures that the force applied to the rock 10 sample is a pure axial force, effectively avoiding stress concentration and uneven deformation caused by eccentric loading, thereby ensuring the accuracy and reliability of the test results.

[0094] The driving component 613 is connected to the end of the second loading component 6122 furthest from the first loading component 6121, and is used to drive the second loading component 6122 to move axially. In other words, the driving component 613 can drive the second loading component 6122 to move axially, thereby achieving the loading and unloading of the normal force on the rock 10. The high-precision driving component 613 allows for control of the loading rate, displacement, and load, meeting the needs of different experimental schemes, whether for stress-controlled loading or strain-controlled loading, and providing technical support for studying the mechanical response of the rock 10 under different loading paths.

[0095] Optionally, the mechanical loading module 610 further includes a mounting plate 614 and a plurality of support rods 615. The mounting plate 614 and the loading base 611 are arranged axially spaced along the first loading member 6121; the plurality of support rods 615 are located between the mounting plate 614 and the loading base 611, and the two ends of the support rods 615 are respectively connected to the mounting plate 614 and the loading base 611; the driving member 613 is mounted on the mounting plate 614. In other words, the support rods 615 are used to support the mounting plate 614, and the mounting plate 614 provides a mounting base for the driving member 613. The plurality of support rods 615 are arranged axially spaced around the first loading member 6121; in other words, the mechanical loading structure 612 is arranged within the space enclosed by the plurality of support rods 615. In the first position, the housing 620 is also located within the space enclosed by the plurality of support rods 615; in other words, in the first position, the mechanical loading structure 612 is located within the housing 620.

[0096] Before the housing 620 moves from the second position to the first position, the second loading member 6122 is removed, and then the housing 620 is pushed to move radially along the first loading member 6121 (i.e., from the second position to the first position) until the first loading member 6121 enters the receiving cavity; finally, the second loading member 6122 is reinstalled onto the drive member 613.

[0097] In some embodiments of the present invention, the measurement system for rock mechanical properties under humid conditions further includes a guiding module. The guiding module includes a guide rail and a slider; one of the guide rail and the slider is mounted on the housing 620, and the other is mounted on the recording base; the slider is slidably engaged with the guide rail. The engagement of the guide rail and the slider enables stable movement of the housing 620. The housing 620 switches between a first position and a second position along the guide rail.

[0098] like Figure 7 and Figure 8As shown, in some embodiments of the present invention, the measurement system for rock mechanical properties under humid conditions further includes an ultrasonic indenter. By setting an ultrasonic indenter, the dynamic elastic modulus can be measured. In other words, a traditional method for measuring the dynamic elastic modulus typically requires an ultrasonic indenter. The ultrasonic indenter includes an ultrasonic transmitting indenter 671 and an ultrasonic receiving indenter 672. One of the first loading member 6121 and the second loading member 6122 is equipped with the ultrasonic transmitting indenter 671, and the other is equipped with the ultrasonic receiving indenter 672. Specifically, the ultrasonic receiving indenter 672 is installed at the end of the first loading member 6121 facing the second loading member 6122, and the ultrasonic transmitting indenter is installed at the end of the second loading member 6122 facing the first loading member 6121. By setting an ultrasonic indenter, changes in parameters such as ultrasonic wave velocity, amplitude, and frequency penetrating the rock sample 10 can be directly and non-destructively monitored in real time. Since the initiation, propagation, and penetration of microcracks inside rock 10 significantly affect the propagation characteristics of ultrasonic waves, this configuration can dynamically capture the damage evolution process inside rock 10 during loading and humidity changes, closely linking macroscopic mechanical behavior with microscopic structural damage, and providing an in-situ monitoring method for further revealing the fracture mechanism of rock 10 under the influence of humidity.

[0099] It should be noted that ultrasonic indenters are existing technology; in other words, they can be purchased according to actual needs. Therefore, ultrasonic indenters are not described in the embodiments of this invention.

[0100] like Figure 7 and Figure 8 As shown, in some embodiments of the present invention, the measurement system for rock mechanical properties under humid conditions includes a detection module 660. The detection module 660 includes an axial strain sensor 661 and a radial strain sensor 662. The axial strain sensor 661 is mounted on the rock sample 10 and is used to measure the axial strain information of the rock sample 10. The radial strain sensor 662 is also mounted on the rock sample 10 and is used to measure the radial strain information of the rock 10. In other words, when conducting a uniaxial compressor experiment using the measurement system for rock mechanical properties under humid conditions provided in this embodiment, an ultrasonic transmitting pressure head 671 can be mounted on the second loading member 6122, and an ultrasonic receiving pressure head can be mounted on the first loading member 6121; the axial strain sensor 661 is mounted axially on the rock 10, and the radial strain sensor 662 is mounted radially on the rock 10. Static strain information of the rock 10 can be obtained through the axial strain sensor 661 and / or the radial strain sensor 662. Monitoring static strain during the stress retention stage allows for the quantification of the creep deformation of the rock 10, thereby studying the influence of humidity on the long-term deformation characteristics of the rock 10. By combining dynamic ultrasonic damage monitoring and static macroscopic strain measurement, this method can more comprehensively reveal the complex mechanical behavior and damage mechanism of rock 10 under humidity-stress coupling.

[0101] In some embodiments of the present invention, the mechanical loading module 610 further includes a device for measuring the stiffness of rock cracks. By introducing this device, the system's functionality is expanded. It can quickly convert the original axial compression loading mode into a crack stiffness measurement mode, allowing the same device to not only perform uniaxial compression tests but also determine important parameters such as the crack stiffness of the rock 10. This modular and reconfigurable design significantly improves the system's versatility and cost-effectiveness, enabling it to adapt to more diverse mechanical testing needs of the rock 10. During mechanical loading experiments, the rock 10 can be placed on the upper end of the first loading member 6121 (i.e., the end facing the second loading member 6122), and the driving member 613 drives the second loading member 6122 to move towards the upper end of the rock 10 to apply a normal loading force to the rock 10.

[0102] like Figure 9 As shown, in some other embodiments of the present invention, the mechanical loading module 610 further includes a three-point loading indenter device 630. By introducing the three-point loading indenter device 630, the functionality of this testing system is further expanded. It can quickly convert the original axial compression loading mode into a three-point bending loading mode, thus enabling the same device to not only perform uniaxial compression tests but also to determine important parameters such as the bending strength and fracture toughness of rock 10. This modular and reconfigurable design significantly improves the system's versatility and cost-effectiveness, allowing it to adapt to more diverse mechanical testing needs of rock 10.

[0103] like Figure 9 As shown, in some embodiments of the present invention, the three-point loading head device 630 includes a first connector 631, two first loading heads 632 and a second loading head 633.

[0104] The first connector 631 is detachably connected to the second loading member 6122. In other words, the pressure head installed on the second loading member 6122 can be replaced as needed.

[0105] Both first loading heads 632 are located on the side of the first connector 631 away from the second loading member 6122, and are both installed on the first connector 631; the two first loading heads 632 are arranged radially spaced along the second loading member 6122, and the end of the first loading head 632 away from the second loading member 6122 is used to abut against the rock 10. The second loading head 633 is detachably installed on the first loading member 6121; the end of the second loading head 633 away from the first loading member 6121 is used to abut against the rock 10.

[0106] Traditional three-point bending loading tests typically involve one loading point on the upper surface of the rock 10 and two loading points on the lower surface. In this embodiment, however, two loading points are located on the upper surface of the rock 10, and one loading point is located on the lower surface, effectively inverting the traditional three-point loading indenter device 630 onto the loading member. This design allows the loading points to avoid rock cracks.

[0107] Furthermore, the first loading head 632 and the first connecting member 631 slide along the radial direction of the second loading member 6122. This allows the first loading head 632 to slide and adjust radially, meaning that the loading span of the three-point bending test can be easily changed according to the test standards or the size of the rock sample 10. This function is crucial for meeting the span-to-height ratio requirements of different international standards, ensuring the standardization of the test and the validity of the results, further enhancing the adaptability of the system and the rigor of scientific research.

[0108] Understandably, after the first loading head 632 moves to the target position, it can be fixed to the first connector 631 by fasteners, such as fastening screws.

[0109] In some embodiments of the present invention, the housing 620 includes an observation port, at which a heated glass 621 is installed. The heated glass 621 installed at the observation port effectively prevents condensation and fogging on the glass surface caused by temperature differences between the inside and outside in high humidity environments. This design ensures a clear field of view under any temperature and humidity conditions, which is essential for direct observation by operators and the normal operation of high-precision optical measurement equipment (such as high-speed cameras and DIC systems), thus improving the observability and data quality of the experimental process.

[0110] Optionally, the heated glass 621 can be an electrically heated glass 621.

[0111] like Figure 5 As shown, in some embodiments of the present invention, the measurement system for the mechanical properties of rocks under humid conditions further includes a lifting platform 640 and a DIC camera 650. The DIC camera 650 is placed on the lifting platform 640, which is located outside the housing 620, and is used to adjust the height of the DIC. The DIC can acquire image information of the rock 10 through the observation port.

[0112] In some embodiments of the present invention, the temperature regulating unit may include a compressor, a four-way valve, a first heat exchanger, a second heat exchanger, an expansion valve, and a fan. The compressor and the first heat exchanger are both installed outside the housing 620, the second heat exchanger is installed inside the housing 620, and the fan is located on one side of the second heat exchanger to blow the air around the second heat exchanger into the receiving cavity.

[0113] When it is necessary to lower the temperature inside the containment cavity, the high-temperature, high-pressure refrigerant discharged from the compressor passes sequentially through a four-way valve, the first heat exchanger, the expansion valve, and the second heat exchanger before returning to the compressor. The high-temperature, high-pressure refrigerant undergoes heat exchange in the first heat exchanger, transforming into a low-temperature, high-pressure refrigerant. The low-temperature, high-pressure refrigerant discharged from the first heat exchanger passes through the expansion valve into the second heat exchanger, where it condenses to lower the temperature of the air surrounding the second heat exchanger. This low-temperature air is then blown into the containment cavity by a fan, thus achieving the cooling effect on the containment cavity.

[0114] When the temperature inside the containment cavity needs to be increased, the high-temperature, high-pressure refrigerant discharged from the compressor passes sequentially through a four-way valve, the second heat exchanger, the expansion valve, and the first heat exchanger before returning to the compressor. The high-temperature, high-pressure refrigerant undergoes heat exchange in the second heat exchanger, transforming into a low-temperature, high-pressure refrigerant. The low-temperature, high-pressure refrigerant discharged from the second heat exchanger passes through the expansion valve and enters the first heat exchanger, where it condenses. The high-temperature air surrounding the first heat exchanger is blown into the containment cavity by a fan, thus heating the cavity.

[0115] Understandably, the environmental control module also includes a temperature sensor; the temperature sensor is used to detect the temperature inside the containment cavity. When the detected actual temperature is lower than the target temperature, the temperature regulation unit activates the heating mode (i.e., the high-temperature, high-pressure refrigerant discharged from the compressor passes through the four-way valve, the second heat exchanger, the expansion valve, and the first heat exchanger before returning to the compressor). When the actual temperature is higher than the target temperature, the temperature regulation unit can activate the cooling mode (i.e., the high-temperature, high-pressure refrigerant discharged from the compressor passes through the four-way valve, the first heat exchanger, the expansion valve, and the second heat exchanger before returning to the compressor).

[0116] Optionally, the temperature control unit may also include a radiator. The radiator is used to dissipate heat from the compressor, etc.

[0117] In some embodiments of the present invention, the humidity regulating unit includes, but is not limited to, a humidifier.

[0118] A specific embodiment of the fourth aspect of the present invention provides a method for measuring the mechanical properties of rocks under humid conditions. This measurement method employs the measurement system for measuring the mechanical properties of rocks under humid conditions described in any of the above embodiments. Therefore, the test method of this embodiment possesses at least the advantages of the aforementioned test systems, which will not be elaborated further here.

[0119] like Figure 10 As shown, in some embodiments, the method for measuring the mechanical properties of rocks under humid conditions includes: S210. The rock 10 is pre-treated, and then the treated rock 10 is placed on the second loading head 633 connected to the first loading member 6121; wherein, the pre-treatment includes pre-cutting an induction groove in the middle of the rock 10 and installing a crack opening sensor in the induction groove.

[0120] Specifically, an induction groove with dimensions of 400mm × 90mm × 90mm and a pre-cut width of 1mm and depth of 3mm in the middle is selected to induce crack formation. When installing the rock 10 sample, ensure that the center of the sample is directly aligned with the second loading head 633 of the three-point loading head device 630 on the base. The two first loading heads 632 are symmetrically arranged on both sides of the induction groove to prevent uneven stress on the sample. Then, the crack aperture sensor is inserted into the induction groove. The transmitting part of the ultrasonic sensor is installed on the first loading member 6121, and the receiving part of the ultrasonic sensor is installed on the second loading member 6122. The ultrasonic waves emitted by the transmitting part are received by the receiving part after passing through the rock 10 sample.

[0121] S220. After the humidity in the containment cavity reaches the target humidity, the driving component 613 of the mechanical loading module 610 is activated to drive the second loading component 6122 to move toward the first loading component 6121, and the two first loading heads 632 apply stress to the rock 10.

[0122] Specifically, the temperature inside the containment cavity is adjusted to the target temperature by the temperature adjustment unit, and the humidity inside the containment cavity is adjusted to the target humidity by the humidity adjustment unit. Then, the drive unit 613 is activated, which drives the second loading member 6122 and the two first loading heads 632 to move towards the first loading member 6121. At the same time, the DIC camera 650 is activated to periodically acquire image information of the rock 10.

[0123] S230. After the stress reaches the preset value, stop the drive component 613 and maintain the stress. Once the change in the crack opening sensor is within the threshold range, complete the mechanical property test under the target humidity.

[0124] Specifically, once the stress reaches the preset value, the drive component 613 is stopped, and the pressure is maintained at the preset value for more than 5 days to ensure that the sample is stable under these conditions and will not creep and fracture. During the pressure maintenance process, the detection value of the crack aperture sensor is collected in real time. If the change in the detection value of the crack aperture sensor before and after is within the threshold range, it indicates that the mechanical property test is completed.

[0125] If it is necessary to study the mechanical properties of rock 10 under different humidity levels, only the specific value of the target humidity needs to be adjusted, and the specific test method remains unchanged.

[0126] In other embodiments of the present invention, the method for measuring the mechanical properties of rocks under humid conditions includes: S310. An axial strain sensor 661 is installed along the axial direction of the rock 10, and a radial strain sensor 662 is installed in the radial direction of the rock 10.

[0127] S320. The treated rock 10 is placed on the ultrasonic receiving head 672. After the humidity in the installation cavity reaches the target humidity, the driving component 613 of the mechanical loading module 610 is activated to drive the second loading component 6122, which in turn moves the ultrasonic transmitting head 671 toward the first loading component 6121 to apply normal stress to the rock 10. The ultrasonic head can be used to capture in real time the characteristics of ultrasonic velocity and energy changes during elastic loading and unloading of the rock 10 at different humidity stages (such as the initiation and development of microcracks), and the dynamic elastic modulus can be calculated to obtain dynamic information about elastic deformation.

[0128] S330. After the stress reaches the preset value, stress is unloaded, and then the stress is maintained.

[0129] During stress holding, static strain information of rock 10 is acquired using axial stress sensor 661 and / or radial strain sensor 662. Monitoring static strain during the stress holding stage allows for the quantification of the static elastic modulus of rock 10, thereby studying the influence of humidity on the long-term deformation characteristics of rock 10. By combining dynamic ultrasonic damage monitoring and static macroscopic strain measurement, this method can more comprehensively reveal the elastic deformation behavior of rock 10 under humidity-stress coupling.

[0130] In some embodiments of the present invention, a method for measuring the mechanical properties of rocks under humid conditions includes: S410, An axial strain sensor 661 is installed in the axial direction of the rock 10, and / or, an axial strain sensor 661 is installed in the radial direction of the rock 10.

[0131] Among them, both the axial strain sensor 661 and the axial strain sensor 661 can be LVDT sensors.

[0132] S420. Place the processed rock 10 on the first loading member 6121. After the humidity in the installation cavity reaches the target humidity, start the driving member 613 of the mechanical loading module 610 to drive the second loading member 6122 to move toward the first loading member 6121 so as to apply normal stress to the rock 10.

[0133] In other words, in this embodiment, instead of using an ultrasonic indenter, two loading elements can be used directly to apply normal stress to the rock.

[0134] S430. After the stress reaches the first preset value, a cyclic stress loading and unloading experiment is performed at a preset loading and unloading frequency until the stress loading and unloading time reaches the preset time. The stress loading and unloading experiment includes unloading the stress to the second preset value immediately after the stress reaches the first preset value, and then loading the stress to the first preset value again, and repeating the cycle.

[0135] Specifically, after the stress reaches 1.5 MPa, it is immediately unloaded to 0.5 MPa at a preset loading / unloading frequency, and then the stress is immediately loaded back to 1.5 MPa at the same preset loading / unloading frequency. This process is repeated until the stress loading / unloading time reaches the preset time. This method allows for rapid cyclic loading within a range of 1 ± 0.5 MPa while the sample is under a certain stress (e.g., 1 MPa), with the loading frequency typically in the kHz range. This method can reflect the mechanical response characteristics of materials in the mid-frequency range, thus enabling a more comprehensive dynamic and static elastic modulus testing system when combined with static and ultrasonic dynamic testing.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for measuring the stiffness of rock cracks, characterized in that, include: The main body (100) includes at least three fixing rings (110); the three fixing rings (110) are spaced apart along their own axial direction to form a receiving cavity (101) for receiving a rock (10); the fixing rings (110) are provided with openings (102) communicating with the receiving cavity (101), and two adjacent openings (102) are located on the same side of the central axis of the fixing rings (110) to form observation windows, and the number of observation windows is at least two; Multiple set screws (200) are arranged circumferentially around the fixing ring (110); the fixing ring (110) has mounting holes in its radial direction, the set screws (200) are threaded into the mounting holes, and one end of the set screw (200) facing the central axis of the fixing ring (110) is used to abut against the side of the rock (10). Multiple guide positioning rods (300), the fixing ring (110) is constructed with a through hole along its own axial direction, and the guide positioning rods (300) are slidably assembled in the through hole; the multiple guide positioning rods (300) are arranged circumferentially around the fixing ring (110); At least two LVDT sensor groups are provided, each corresponding to one of the observation windows; each LVDT sensor group includes two LVDT sensors (400); the LVDT sensor groups are installed on the fixing ring (110), and the LVDT sensor groups are used to detect the normal deformation of the rock (10) in the corresponding observation window; the two LVDT sensors (400) are symmetrically installed on the fixing ring (110) with the central axis of the fixing ring (110) as the axis of symmetry.

2. The device for measuring the stiffness of rock fractures according to claim 1, characterized in that, The fixing ring (110) includes: Connecting plate (111); Two mounting plates (112); one end of the two mounting plates (112) is opposite to each other to form the opening (102), and the other ends of the two mounting plates (112) are connected by the connecting plate (111) to form the retaining ring (110).

3. The device for measuring the stiffness of rock fractures according to claim 2, characterized in that, The mounting plate (112) is larger in the radial direction than the connecting plate (111).

4. The measuring device for rock fracture stiffness according to any one of claims 1 to 3, characterized in that, Also includes: A DIC camera is used to acquire images of the rocks (10) within the observation window; The control module is electrically connected to the LVDT sensor (400) and the DIC camera.

5. A method for measuring the stiffness of rock fractures, characterized in that, The measuring device for measuring rock fracture stiffness according to any one of claims 1 to 4, the measuring method comprising: After placing the rock (10) into the receiving cavity (101) of the measuring device according to the test requirements, during the process of applying normal stress to the rock (10), the first deformation information of the complete area (11) of the rock and the second deformation information of the cracked area (12) of the rock are acquired simultaneously; the first deformation information includes the first normal deformation amount and the first image information of the complete area (11), and the second deformation information includes the second normal deformation amount and the second image information of the cracked area (12); Based on the first normal deformation and the first image information, the first actual normal deformation of the intact rock region (11) is determined; based on the second normal deformation and the second image information, the second actual normal deformation of the rock crack region (12) is determined. The crack stiffness of rock (10) is determined based on the first actual normal deformation, the second actual normal deformation and the normal stress increment.

6. A system for measuring the mechanical properties of rocks under humid conditions, characterized in that, The measuring device for rock fracture stiffness as described in any one of claims 1 to 4.

Images