A method for making a rock mass grouting test piece

Abstract

This invention discloses a method for preparing grouting specimens for rock mass, belonging to the field of geotechnical engineering testing technology. The invention employs multi-stage stepwise crushing and screening to obtain rock blocks with a standard particle size of 1-6 cm. An adjustable-diameter, fixed-height circular mold is fabricated using PVC pipes, along with a matching base and perforated top cover. After lubricating the inner wall of the mold and the base, rock blocks of 1-2 cm, 3-4 cm, and 5-6 cm are filled in a 3:2:1 ratio and numbered. A grouting pump injects cement grout at a uniform speed through the grouting holes on the top cover. After grouting, the specimen is allowed to stand for 3-5 minutes, allowing air to seep out under its own weight. After initial setting, the specimen undergoes standard curing. After seven days of curing, the specimen is demolded to obtain the final specimen. This invention solves the problems of traditional specimens failing to replicate the natural rock mass structure, incomplete grout filling, demolding damage, and large errors in test data. It significantly improves the specimen's density, dimensional accuracy, and appearance integrity. The equipment is simple, can be processed on-site, and produces specimens with uniform mechanical properties, providing highly reliable samples for rock mass grouting mechanical testing.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering technology, and in particular to a method for preparing grouting specimens for rock masses. Background Technology

[0002] The quality of grouting specimen fabrication in geotechnical engineering directly affects the accurate detection and evaluation of the mechanical properties and strength of the grouted specimens, and is a key technical step in conducting dynamic and static experiments. Multiple factors, such as raw material ratio deviations, uneven mixing, uneven pouring, and fluctuations in the curing environment, pose numerous challenges to the standardized fabrication of grouting specimens. Therefore, controlling and resolving these influencing factors in the grouting specimen fabrication process is both a core focus and a significant implementation difficulty. Traditional grouting specimen fabrication involves core drilling after grouting. Sandy rock masses are prone to breakage after grouting, and it is difficult to replicate the spatial structure of naturally weak rock masses, leading to significant errors in mechanical property test results. Compared to traditional processes, existing technologies still suffer from problems such as raw material ratio deviations, uneven pouring, insufficient grout filling, uneven specimen surfaces, and easy breakage during demolding, ultimately resulting in inaccurate test data. Summary of the Invention

[0003] To address the shortcomings of the aforementioned background technology, this invention proposes a method for preparing rock mass grouting specimens. This method solves the problem that multiple factors in existing technologies, such as raw material ratio deviations, uneven mixing, uneven pouring, and fluctuations in the curing environment, prevent the standard preparation of grouting specimens from being met. This invention utilizes a complete process including multi-stage crushing and screening to prepare standard-sized rock blocks, processing adjustable standard molds from PVC pipes, mold lubrication, quantitative graded filler, pump-pressurized grouting, gravity-fed static venting, post-initial setting curing, and periodic demolding. This significantly improves the dimensional accuracy, internal density, and surface smoothness of rock mass grouting specimens, reproducing the spatial structure of natural rock masses and providing highly reliable specimens for static and dynamic rock mechanics tests.

[0004] The technical solution of this invention is achieved as follows: a method for preparing rock mass grouting specimens, comprising the following steps:

[0005] S1 Raw Material Crushing and Screening: Take whole rock mass raw materials, process rock blocks using multi-stage step-by-step crushing process, and screen them with graded screens to obtain rock blocks of different target particle sizes;

[0006] S2 Standard mold preparation: Cut PVC pipe into a circular mold, and process a PVC base and a perforated top cover to match the circular mold.

[0007] S3 Mold Lubrication Treatment: Apply lubricating oil evenly to the inner wall of the standard circular mold and the contact surface of the PVC base, and assemble the PVC base and the circular mold into a rock block mold;

[0008] S4 Rock Block Mold Numbering: After screening, rock blocks of different target particle sizes are filled into the rock block mold according to the preset particle size distribution ratio and leveled. Each set of rock block molds is marked and numbered, and then the perforated top cover is fastened to form a casting mold.

[0009] S5 pump pressure grouting: The pre-mixed cement grout is injected into the casting mold at a uniform speed using a grouting pump, so that the cement grout fills all the gaps between the rock blocks and wraps the rock blocks.

[0010] S6 Self-weight seepage static setting: After grouting is completed, the cement grout is left to stand, relying on its own weight to fully seep and fill the gaps and expel the trapped air inside.

[0011] S7 Standard curing after initial setting: After the specimens have been allowed to stand until they reach the initial setting state, they are moved into the curing environment for standard curing.

[0012] S8 Finished Product Demolding: After the standard curing cycle is completed, the casting mold is removed, and the rock mass grouting specimen is demolded and formed.

[0013] Preferably, the multi-stage step-by-step crushing process in S1 includes pre-crushing with a press, coarse crushing with an electric drill, and fine crushing with manual hammering, specifically:

[0014] (1) Press crushing: The whole large rock mass is crushed into large-diameter rock blocks using a press;

[0015] (2) Coarse crushing with electric drill: The large-diameter rock blocks after fracturing are crushed by electric drill to obtain medium and small-sized rock blocks;

[0016] (3) Manual crushing and screening: Use a hand hammer to manually hammer and shape small and medium-sized rock blocks, and then screen them through a grading screen to remove unqualified debris, so as to obtain rock blocks with target particle size grades of 1 to 6 cm.

[0017] Preferably, the standard ring mold processing steps in S2 are as follows:

[0018] (1) Pipe cutting: Mark the cutting scale h+5mm on the outer wall of the PVC pipe, where h is 45~55mm, and use an electric saw to cut the pipe section along the scale;

[0019] (2) End face grinding: Grind the end faces of the cut pipe sections to accurately control the finished height of the ring mold to h;

[0020] (3) Processing of supporting components: Cut PVC pipes of the same specification to make a flat PVC base plate that matches the circular mold, and a perforated top cover with grouting holes.

[0021] More preferably, in the standard ring mold processing step of S2, the standard inner diameter calibration is set to D, where D is 90~110mm: if the original inner diameter of the PVC pipe is greater than D, the PVC pipe is cut into PVC gaskets so that the PVC gaskets are lined inside the inner wall of the pipe section, and the inner diameter of the ring mold is adjusted to the standard inner diameter to form a standard ring mold.

[0022] More preferably, the preset particle size distribution ratio in S4 is: rock blocks with a particle size of 1-2cm: rock blocks with a particle size of 3-4cm: rock blocks with a particle size of 5-6cm in a ratio of 3:2:1.

[0023] More preferably, the rock block filling and numbering operation in S4 is as follows: rock blocks of different sizes are filled into the rock block mold in layers according to the ratio, and the gaps between the rock blocks are leveled by manual vibration; a unique number is marked on the outer wall of the mold with a marker, and the top of the mold is sealed by fastening the perforated cover after filling is completed.

[0024] Preferably, in the pump-pressurized grouting process of S5, the cement slurry output by the grouting pump is continuously and evenly injected into the mold through the grouting hole with the perforated cover. The grouting system simultaneously grouts multiple sets of molds in parallel to ensure that the cement slurry completely fills the gaps between the rock blocks and ensures grouting efficiency.

[0025] Preferably, the self-weight seepage settling time in S6 is 3 to 5 minutes. During the settling process, the cement slurry relies on its own gravity to seep downwards and fill the tiny gaps, while simultaneously expelling the closed air trapped between the rock blocks, thus eliminating the hollow defects inside the specimen.

[0026] Preferably, the standard curing precondition in S7 is to wait for the cement slurry to initially set and form under a static environment at room temperature, and then transfer the specimen to the standard curing process after the specimen has formed a preliminary bonding strength. During the curing process, external forces should be avoided to disturb the mold.

[0027] Preferably, the standard curing period before demolding of the finished product in S8 is seven days; after the seven-day curing is completed, the specimen has stable early strength, and the perforated top cover, PVC base and circular mold are removed to complete the demolding. After demolding, the specimen has no defects such as missing corners, chipped edges and surface damage.

[0028] The beneficial effects of this invention are as follows: after crushing the rock mass and filling it into a mold for grouting, this invention can reproduce the spatial structure of natural soft rock mass, and has the advantages of small mechanical property testing error and reliable experimental data, which can provide accurate technical support for the design and fabrication of grouting in geotechnical engineering.

[0029] 1. A step-by-step crushing method is used to prepare rock blocks of the target particle size: First, the intact rock blocks are crushed using a press to obtain large-diameter rock blocks; then, the large-diameter rock blocks are coarsely crushed using an electric drill to reduce the particle size to a preset small diameter range; finally, the coarsely crushed rock blocks are finely shaped by manual hammering and screened using a grading sieve to precisely control the particle size to the target size of 1-6 cm designed for the experiment, meeting the accuracy requirements of rock mechanics experiments for rock block particle size. This preparation method uses conventional and simple tools such as a pressure gauge, electric drill, and hammer, requiring no large crushing equipment, has strong site adaptability, can be carried out on-site, has a low operating threshold, and combines cost-effectiveness with ease of operation.

[0030] 2. Fabrication of a φ100mm×50mm circular ring mold using PVC pipe: First, mark the PVC pipe with a 55mm scale and cut it, then grind it to a designed height of 50mm. The inner diameter of the PVC pipe should conform to the preset size of 100mm. If the inner diameter of the PVC pipe is larger than the preset size, insert a cut PVC shim inside the pipe to reduce the size and make the inner diameter fit the 100mm manufacturing standard. Then, use this PVC pipe to fabricate a base and a perforated top cover to fit the circular ring mold. This method is low-cost, requires no custom-made molds, utilizes readily available PVC pipe material, and has low material waste. It also features high dimensional accuracy, allows for grinding allowance to avoid cutting errors, flexible adjustment of the inner diameter with the shim for convenient and efficient operation, easy processing of PVC material, rapid on-site fabrication, and flexible shim method to adapt to the needs of different sized specimens.

[0031] 3. Applying lubricating oil ensures smooth demolding of the specimen, preventing it from sticking to the mold and base and causing chipped corners or edges, thus ensuring the integrity of the specimen's appearance and dimensions. At the same time, it reduces the adhesion of aggregate to the inner wall of the mold, requiring only a simple wipe after demolding for cleaning, enabling mold reuse, saving materials, and improving construction efficiency.

[0032] 4. The particle size distribution selected in this operation method is consistent with actual engineering conditions: rock blocks of 1-2cm, 3-4cm, and 5-6cm are mixed in a 3:2:1 ratio, making the grouting rock samples more accurately simulate actual engineering grouting rock samples, and giving the test results certain engineering reference value. The molds are also numbered, which facilitates the subsequent classification, data recording, and result comparison and analysis of rock mechanics tests.

[0033] 5. By uniformly injecting cement grout through a grouting pump, the gaps between rock blocks can be fully filled and the rock blocks can be evenly wrapped, ensuring that the specimen is densely bonded, uniformly stressed, and has good structural integrity. This avoids local accumulation or leakage of grout and reduces shrinkage cracks during the curing stage. Allowing the grout to stand for 3-5 minutes allows it to seep through under its own weight to fill the gaps and expel internal air, preventing voids and further improving the density and integrity of the specimen. This reduces the problems of internal hollowing and cracking in the specimen later, ensuring the quality of specimen molding and the accuracy and reliability of subsequent mechanical test data. Moreover, this method is simple to operate and has no additional process costs. Attached Figure Description

[0034] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a flowchart of the step-by-step rock mass crushing process of the present invention;

[0036] Figure 2 This is a flowchart illustrating the PVC standard mold processing of the present invention.

[0037] Figure 3 This is a flowchart illustrating the overall fabrication process of the rock mass grouting specimen for this invention. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] like Figures 1-3 As shown in Example 1, a method for preparing grouting specimens for rock mass includes the following steps:

[0040] S1: Take whole granite or sandstone blocks as raw material. Use a press to crush the whole blocks into multiple large-diameter blocks. Use an electric drill to coarsely crush the large-diameter blocks to obtain medium and small-sized blocks. Since the electric drill is difficult to hold small-sized blocks and is prone to slipping, manual hammering is used to shape them. Then, they are manually screened through a grading screen to obtain blocks with a target particle size of 1-6cm. Manual hammering allows for adjustment of the hammering force according to the hardness and cracks of the blocks, avoiding excessive crushing and generating a large amount of powder, improving the yield of qualified blocks, and making on-site operation convenient.

[0041] S2: Select PVC pipe to make a circular mold, a matching PVC base, and a perforated top cover; set the standard mold height h=50mm, mark a 55mm scale (h+5mm) on the outer wall of the PVC pipe, and cut the pipe section along the scale with an electric saw; grind the end faces of the pipe section to accurately control the mold height to 50mm; set the standard inner diameter D=100mm. If the original inner diameter of the PVC pipe is greater than 100mm, cut a PVC gasket to line the inner wall of the pipe and calibrate the inner diameter to 100mm; cut a flat base and a perforated top cover with grouting holes from PVC sheet of the same specification.

[0042] S3: Apply lubricating oil evenly to the entire inner wall of the PVC ring mold and the upper surface of the PVC base, and the lubricating oil forms an isolation layer; assemble the ring mold vertically onto the PVC base to obtain the rock block mold.

[0043] S4: Fill the assembled rock block mold with the sieved rock blocks in layers of 1-2cm: 3-4cm: 5-6cm in a 3:2:1 ratio. Manually vibrate lightly to level the gaps between the rock blocks. Mark a unique number on the outer wall of the mold with a marker. After filling, fasten the perforated top cover to seal the top of the mold, forming a casting mold.

[0044] S5: Connect the pre-prepared cement slurry to the grouting pump, connect the grouting pipeline to the grouting hole of the perforated cover, and continuously and evenly inject grout into the mold; the grouting system can simultaneously connect to multiple sets of casting molds for parallel grouting, and the cement slurry fills the gaps between the rock blocks layer by layer, completely wrapping each rock block.

[0045] S6: After grouting, let the entire casting mold stand at room temperature for 3 to 5 minutes; the cement grout will penetrate downwards by its own weight, filling the tiny gaps in the rock blocks, and at the same time expelling the closed air trapped in the gaps upwards, eliminating the hollow defects inside the specimen.

[0046] S7: After the static setting is completed, keep the mold in a static environment at room temperature and wait for the cement slurry to fully set. After the specimen has formed a preliminary bonding strength, transfer it to the standard curing room for standard curing. During the curing process, avoid moving, collision or other external forces that may disturb the mold to prevent cracking and damage of the uncured bonding structure.

[0047] S8: Demolding is carried out after seven days of continuous standard curing; at this time, the specimen has achieved stable early strength. The perforated top cover, PVC ring mold, and PVC base are removed in sequence to complete the demolding of the rock mass grouting specimen; the demolded specimen has intact edges and corners, a smooth surface, and no missing corners, chipped edges, or damage.

[0048] This invention employs a molding process involving filling molds with fractured rock mass followed by grouting. This process can highly replicate the spatial structure of natural, weak rock masses, resulting in densely cemented specimens with uniform mechanical properties. The static and dynamic test results accurately reflect the mechanical characteristics of the rock mass after grouting. The entire process, including particle size distribution, grouting, settling, curing, and demolding, is standardized, ensuring high specimen consistency and minimal data dispersion. The PVC mold material is readily available and recyclable. The entire method has a low operational threshold and can be implemented on-site, significantly reducing the testing cost of grouting specimens in soil and rock.

[0049] like Figures 1-3 As shown in Example 2, a method for preparing grouting specimens for rock mass is described below:

[0050] S1: Take rock raw materials and use a press to crush the whole rock blocks into multiple large-diameter blocks. Use an electric drill to further crush the large-diameter blocks to obtain small-diameter blocks. Because electric drills have problems with clamping and operating very small rock blocks, and are prone to slipping, the small-diameter blocks are manually hammered. Then, they are manually screened through a grading screen to obtain target rock blocks with a diameter of 1-6cm. Manual hammering can adjust the force according to the actual hardness and crack condition of the rock blocks, avoiding excessive mechanical crushing that produces a large amount of powdery debris, reducing the waste of rock raw materials, increasing the output rate of target-sized rock blocks, and requiring only hammers for subsequent crushing. This compensates for the shortcomings of electric drills in processing small-sized rock blocks and meets the needs of rapid on-site processing.

[0051] S2: Use an electric saw to cut the PVC pipe to make a circular mold, base, and perforated top cover. To ensure that the mold accurately reaches the specifications of 50mm in height and 100mm in diameter, first mark a 55mm height scale on the PVC pipe with a marker. After cutting with an electric saw, grind the end of the pipe to make the mold height accurate to the design size of 50mm. The original inner diameter of the PVC pipe is 100mm, which is consistent with the requirements for making a 100mm test piece. If the inner diameter of the PVC pipe is larger than the preset size, insert a shim after cutting the PVC pipe into the pipe to make the inner diameter of the mold fit the 100mm production standard.

[0052] S3: Apply lubricating oil evenly to the inner wall and base surface of the completed PVC ring mold. The lubricating oil can form an isolation layer between the mold, base and specimen, ensuring smooth demolding and reducing the adhesion of the specimen aggregate to the inner wall of the mold, making the mold easier to clean and reuse.

[0053] S4: Granite and sandstone fragments are layered into a ring mold with a base plate in a ratio of 3:2:1, with particle sizes of 1~2cm, 3~4cm, and 5~6cm respectively. The mixture is then manually filled and evenly distributed. The outer wall of the mold is marked with a marker to facilitate classification and testing in subsequent mechanical experiments.

[0054] S5: The pre-prepared cement slurry is evenly injected into multiple ring molds through the holes in the perforated cover using a grouting pump, so that the cement slurry fully covers the surface of the rock block, gradually fills the gaps between the rock blocks, ensures that the slurry evenly coats the rock block, and ensures grouting efficiency.

[0055] S6: After the cement grout is injected, let the ring mold stand for 3 to 5 minutes to allow the cement grout to fully penetrate into the gaps in the rock blocks by its own weight, while expelling any residual air in the gaps to avoid leaving voids.

[0056] S7: After the static setting is completed, place the ring mold in a room temperature environment. After the specimen reaches the initial setting state, carry out standard curing treatment on the specimen to avoid external disturbances during the curing process from damaging the unformed cemented structure of the specimen.

[0057] S8: After seven days of standard curing, the specimen is demolded. At this time, the specimen has a certain early strength, which can effectively reduce the damage caused to the specimen by the demolding operation and ensure the integrity of the specimen's size and appearance.

[0058] This invention employs a specimen fabrication process involving grouting in fractured rock mass. This process replicates the spatial structure of natural, weak rock masses, ensuring consistency between the grouted specimens and the actual rock mass in engineering projects, and improving the accuracy of mechanical property testing. During fabrication, cement grout fills the gaps between rock fragments and, through pressurized pumping and static settling, ensures thorough seepage and bonding. This effectively improves the bonding density and structural integrity of the fractured rock specimens, facilitating subsequent mechanical testing. After the cement grout is injected into the gaps between rock blocks, the hardened grout forms a robust integral structure with the rock blocks. The resulting grouted specimens exhibit uniform mechanical properties. Compared to loose, fractured rock masses, the mechanical data obtained under the same testing conditions better reflect the actual engineering conditions when applied to a well-bonded specimen. In practice, the test results are more reliable. To match the particle size distribution characteristics of the engineering rock mass, the rock blocks are graded in a 3:2:1 ratio of 1-2cm, 3-4cm, and 5-6cm. This can reproduce the spatial structure of the actual grouting rock mass and ensure that the test load is evenly applied to the specimen. While ensuring the quality of the grouting specimen, it also improves the reliability of the mechanical test data, reduces material waste, and lowers the test cost. The screening of rock blocks before preparation, the control of the molding process during preparation, and the surface polishing after preparation can avoid the molding defects of the specimen in a timely manner, which can effectively ensure the accuracy of the mechanical test. Applying lubricating oil to the inner wall of the mold and the base during preparation can make the specimen demolding smooth, avoid the specimen chipping and corner breaking, improve the specimen preparation efficiency, and reduce the test preparation period.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing grouting specimens for rock mass, characterized in that, Includes the following steps: S1 Raw Material Crushing and Screening: Take whole rock mass raw materials, process rock blocks using multi-stage step-by-step crushing process, and screen them with graded screens to obtain rock blocks of different target particle sizes; S2 Standard mold preparation: Cut PVC pipe into a circular mold, and process a PVC base and a perforated top cover to match the circular mold. S3 Mold Lubrication Treatment: Apply lubricating oil evenly to the inner wall of the standard circular mold and the contact surface of the PVC base, and assemble the PVC base and the circular mold into a rock block mold; S4 Rock Block Mold Numbering: After screening, rock blocks of different target particle sizes are filled into the rock block mold according to the preset particle size distribution ratio and leveled. Each set of rock block molds is marked and numbered, and then the perforated top cover is fastened to form a casting mold. S5 pump pressure grouting: The pre-mixed cement grout is injected into the casting mold at a uniform speed using a grouting pump, so that the cement grout fills all the gaps between the rock blocks and wraps the rock blocks. S6 Self-weight seepage static setting: After grouting is completed, the cement grout is left to stand, relying on its own weight to fully seep and fill the gaps and expel the trapped air inside. S7 Standard curing after initial setting: After the specimens have been allowed to stand until they reach the initial setting state, they are moved into the curing environment for standard curing. S8 Finished Product Demolding: After the standard curing cycle is completed, the casting mold is removed, and the rock mass grouting specimen is demolded and formed.

2. The method for preparing grouting specimens for rock mass according to claim 1, characterized in that, The multi-stage step-by-step crushing process in S1 includes press pre-crushing, electric drill coarse crushing, and manual hammer fine crushing, specifically: (1) Press crushing: The whole large rock mass is crushed into large-diameter rock blocks using a press; (2) Coarse crushing with electric drill: The large-diameter rock blocks after fracturing are crushed by electric drill to obtain medium and small-sized rock blocks; (3) Manual crushing and screening: Use a hand hammer to manually hammer and shape small and medium-sized rock blocks, and then screen them through a grading screen to remove unqualified debris, so as to obtain rock blocks with target particle size grades of 1 to 6 cm.

3. The method for preparing grouting specimens for rock mass according to claim 2, characterized in that, The processing steps for the standard circular mold in S2 are as follows: (1) Pipe cutting: Mark the cutting scale h+5mm on the outer wall of the PVC pipe, where h is 45~55mm, and use an electric saw to cut the pipe section along the scale; (2) End face grinding: Grind the end faces of the cut pipe sections to accurately control the finished height of the ring mold to h; (3) Processing of supporting components: Cut PVC pipes of the same specification to make a flat PVC base plate that matches the circular mold, and a perforated top cover with grouting holes.

4. The method for preparing grouting specimens for rock mass according to claim 3, characterized in that, In the standard ring mold processing step of S2, the standard inner diameter calibration is set to D, where D is 90~110mm. If the original inner diameter of the PVC pipe is greater than D, the PVC pipe is cut into PVC gaskets so that the PVC gaskets are lined inside the inner wall of the pipe section. The inner diameter of the ring mold is adjusted to the standard inner diameter to form a standard ring mold.

5. The method for preparing grouting specimens for rock mass according to claim 4, characterized in that, The preset particle size distribution ratio in S4 is: rock blocks with a particle size of 1-2cm: rock blocks with a particle size of 3-4cm: rock blocks with a particle size of 5-6cm in a ratio of 3:2:

1.

6. The method for preparing grouting specimens for rock mass according to claim 5, characterized in that, The rock block loading and numbering operation in S4 is as follows: rock blocks of different sizes are filled into the rock block mold in layers according to the ratio, and the gaps between the rock blocks are leveled by manual vibration; a unique number is marked on the outer wall of the mold with a marker, and the top of the mold is sealed by fastening the perforated cover after the filling is completed.

7. A method for preparing rock mass grouting specimens according to any one of claims 1 to 6, characterized in that, In the S5 pump-pressurized grouting process, the cement slurry output by the grouting pump is continuously and evenly injected into the mold through the grouting hole with the perforated cover. The grouting system simultaneously grouts multiple sets of molds in parallel to ensure that the cement slurry completely fills the gaps between the rock blocks and ensures grouting efficiency.

8. A method for preparing grouting specimens for rock mass according to claim 7, characterized in that, The self-weight seepage settling time in S6 is 3 to 5 minutes. During the settling process, the cement slurry relies on its own gravity to seep downwards and fill the tiny gaps, while simultaneously expelling the closed air trapped between the rock blocks, thus eliminating the hollow defects inside the specimen.

9. A method for preparing grouting specimens for rock mass according to claim 8, characterized in that, The standard curing preconditions in S7 are to wait for the cement slurry to initially set and form under a static environment at room temperature, and then transfer the specimen to the standard curing process after the specimen has formed a preliminary bonding strength. During the curing process, external forces should be avoided to disturb the mold.

10. A method for preparing rock mass grouting specimens according to any one of claims 1 to 6, 8, and 9, characterized in that, The standard curing period before demolding the finished product in S8 is seven days. After seven days of curing, the specimen has stable early strength. The perforated top cover, PVC base and circular mold are removed to complete the demolding. After demolding, the specimen has no defects such as missing corners, chipped edges or surface damage.

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