A controllable negative pressure grouting test device and its grouting method

Abstract

This invention discloses a controllable negative pressure grouting test device, comprising a grouting model assembly, which includes a grouting bucket, a fixing unit, a first limiting unit, and a sealing unit; a filtering unit located at the lower part of the inner cavity of the grouting bucket; a second limiting unit located at the upper part of the inner cavity of the grouting bucket to limit the height of the sample inside the grouting bucket and prevent the sample from floating; a fastening unit located on the outer circumference of the grouting bucket to provide circumferential constraint; a negative pressure component connected to the upper end of the grouting model assembly to generate negative pressure and expel air from the grouting model assembly; and a grout delivery component connected to the lower end of the grouting model assembly to allow grout to flow into the grouting bucket when the negative pressure component generates negative pressure. This invention features a simple device, easy operation, strong anti-interference capability, and can effectively improve work efficiency and ensure the accuracy of the test.

Description

Technical Field

[0001] This invention relates to the field of indoor testing equipment for geotechnical engineering, and in particular to a controllable negative pressure grouting test device and its grouting method. Background Technology

[0002] Grouting technology can significantly improve the physical and mechanical properties of engineering geological soil, such as impermeability and shear strength, and can avoid engineering disasters such as collapse and landslide caused by poor engineering geological bodies. Therefore, it is widely used in engineering construction.

[0003] Determining grouting parameters through field tests typically faces challenges such as high construction difficulty, long processing time, and high cost. Therefore, there is an urgent need to set grouting parameters in an indoor environment. However, existing indoor grouting testing equipment usually has some significant shortcomings:

[0004] (1) When using a pressure grouting machine, the grouting pressure can reach 10 MPa. The grouting time is relatively short, and a large amount of grout may not be fully injected into the sample, thus increasing the error in the test. (2) When using a pressure grouting machine, the grout storage tank is generally required to be sealed. However, the cleaning process of the sealed grout tank requires the removal of all the bolts on the cover plate, which is a large cleaning workload and low test efficiency. In addition, the grout in the sealed tank is prone to segregation or sedimentation due to the lack of external stirring, resulting in uneven grout. (3) Pressure grouting machines are generally driven by electricity. Factors such as power outages and unstable current will affect the test. (4) Traditional grouting tests generally use pressure gauges, flow meters, etc. as monitoring components. The accuracy and sensitivity of these instruments will change with the increase of usage time, which will have a significant impact on the test. (5) Grouting machines, pressure gauges, flow meters, and other equipment are expensive. (6) Traditional grouting tanks are a single unit. However, the sample may expand during the curing process. Therefore, there may be a large frictional resistance between the cured sample and the tank wall, making it difficult to demold the sample. (7) In order to simulate field tests, conventional indoor grouting devices are large in size and have small sampling areas, and there are problems such as uneven grout distribution, excessive grout waste, and uneven sample distribution.

[0005] Therefore, there is an urgent need for a controllable negative pressure grouting test device and its grouting method to solve the above problems. Summary of the Invention

[0006] The main objective of this invention is to provide a controllable negative pressure grouting test device and its grouting method, thereby solving the technical problems in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A controllable negative pressure grouting test device, comprising:

[0009] The grouting model assembly includes an assemblable and sealable grouting bucket for containing a sample, and a fixing unit for fixing the grouting bucket; the grouting model assembly also includes a first limiting unit for limiting the grouting bucket and the fixing unit, and a sealing unit for sealing the grouting bucket and the space between the grouting bucket and the fixing unit.

[0010] A filter unit is located in the lower part of the inner cavity of the grouting bucket to ensure uniform grouting and prevent the sample in the grouting bucket from falling into the bottom surface of the grouting bucket and clogging the grout delivery assembly.

[0011] The second limiting unit is located in the upper part of the inner cavity of the grouting bucket to limit the height of the sample inside the grouting bucket and prevent the sample from floating.

[0012] A fastening unit is located on the outer periphery of the grouting barrel to provide a circumferential constraint to the grouting barrel;

[0013] A negative pressure assembly is connected to the upper end of the grouting model assembly to generate negative pressure and expel air from the grouting model assembly.

[0014] A grout delivery assembly is connected to the lower end of the grouting model assembly. When the negative pressure assembly generates negative pressure, the grout is injected into the grouting tank.

[0015] Preferably, the grouting tank includes a first mold segment and a second mold segment that interlock with each other; the fixing unit includes a counter-pressure cover plate and a counter-pressure base, the counter-pressure cover plate is located at the upper end of the first mold segment and the second mold segment, and the counter-pressure base is located at the lower end of the first mold segment and the second mold segment. Both the counter-pressure cover plate and the counter-pressure base have slots with the same cross-section as the first mold segment and the second mold segment, and the slots are used to limit and fix the first mold segment and the second mold segment; the first limiting unit includes at least three screws, the counter-pressure cover plate has first screw holes corresponding to the number of screws, and the counter-pressure base has second screw holes corresponding to the number of screws. Each screw passes through the first screw hole and is located inside the second screw hole, and each screw is correspondingly provided with a nut; the counter-pressure cover plate and the counter-pressure base are connected by screws and nuts for limiting; the screws are located outside the first mold segment and the second mold segment.

[0016] Preferably, the filtration unit includes a filter plate located at the lower part of the grouting tank cavity, and a pad layer is laid below the filter plate to support the filter plate and make the grouting uniform; the second limiting unit includes an anti-buoyancy plate located below the counter-pressure cover plate, and an anti-buoyancy frame is provided between the anti-buoyancy plate and the counter-pressure cover plate.

[0017] Preferably, the fastening unit includes at least three rings evenly arranged from bottom to top along the outer walls of the first and second mold segments, the rings applying lateral annular constraints to the first and second mold segments to tightly fit the first and second mold segments together.

[0018] Preferably, the negative pressure assembly includes a negative pressure cylinder, a drain unit is provided on the side wall near the bottom of the negative pressure cylinder, and an exhaust unit and a pressure guiding unit are respectively provided at the top of the negative pressure cylinder; a first pressure guiding pipe is provided at the end of the inlet pressure guiding pipe away from the negative pressure cylinder, and a second pressure guiding pipe is provided at the end of the first pressure guiding pipe away from the inlet pressure guiding pipe, and the second pressure guiding pipe is connected to the back pressure cover plate.

[0019] Preferably, the drainage unit includes a drainage pipe disposed on the side wall near the bottom of the negative pressure cylinder with the outlet facing upward, and a drainage valve is provided on the drainage pipe; the venting unit includes a venting pipe disposed at the upper end of the negative pressure cylinder and located on one side of the inlet pressure guiding pipe, and a venting valve is provided on the venting pipe; the pressure guiding unit includes an inlet pressure guiding pipe, a first pressure guiding pipe, a second pressure guiding pipe and a pressure guiding valve, one end of the second pressure guiding pipe is connected to the back pressure cover plate, the other end of the second pressure guiding pipe is connected to the first pressure guiding pipe, and a pressure guiding valve is provided on the second pressure guiding pipe.

[0020] Preferably, the grouting assembly includes a grout storage tank with an open top and a first grout guide pipe disposed at the bottom of the grouting tank, a second grout guide pipe communicating with the first grout guide pipe, the end of the second grout guide pipe away from the first grout guide pipe extending into the grout storage tank, and a grouting valve disposed on the first grout guide pipe; the filter plate is disposed at a position higher than the first grout guide pipe.

[0021] Preferably, the sealing unit includes a sealing strip disposed between the first mold segment and the second mold segment, and a circular sealing gasket disposed in the slot; the sealing unit also includes a sleeve connecting the liquid inlet pressure guide pipe to the first pressure guide pipe, the second pressure guide pipe to the first pressure guide pipe, and the first slurry guide pipe to the second slurry guide pipe.

[0022] Preferably, the controllable negative pressure grouting test device further includes a measuring unit, which includes a first scale located on the side wall of the negative pressure cylinder, a second scale located on the first or second mold segment, and a third scale located on the side wall of the grout storage tank.

[0023] A method for grouting using the controllable negative pressure grouting test device includes the following steps:

[0024] S1. Assemble the grouting bucket: Place the sealing strip between the first mold segment and the second mold segment, put the ring around the outside of the first mold segment and the second mold segment and tighten it so that the first mold segment and the second mold segment form the grouting bucket; place round sealing gaskets in the slots of the counter-pressure cover plate and the counter-pressure base, and then place the grouting bucket in the slot of the counter-pressure base;

[0025] S2. Laying the filter unit: Lay a cushion layer at the bottom of the grouting tank, so that the cushion layer covers the first grouting pipe, and then place the filter plate on the top of the cushion layer;

[0026] S3. Sample laying: Weigh the sample and lay it flat on the filter plate. After the sample is laid, place the anti-buoyancy plate on the top of the sample and place the anti-buoyancy frame on the anti-buoyancy plate.

[0027] S4. Assemble the counter-pressure cover plate and the second limiting unit: Place the counter-pressure cover plate on the grouting bucket and position the grouting bucket in the slot of the counter-pressure cover plate; then pass the screw through the first screw hole and position it in the second screw hole, and tighten the nut to make the counter-pressure cover plate and the counter-pressure base fit tightly against the grouting bucket.

[0028] S5. Assemble the slurry delivery assembly: Connect the first slurry pipe to the second slurry pipe, with the second slurry pipe extending into the slurry storage tank; prepare the slurry and place the prepared slurry into the slurry storage tank;

[0029] S6. Assemble the negative pressure assembly and connect it to the grouting assembly: Open the exhaust valve, close the drain valve, and inject negative pressure liquid into the negative pressure cylinder through the inlet pressure guide pipe; connect the inlet pressure guide pipe to the first pressure guide pipe with a sleeve, and connect the second pressure guide pipe to the first pressure guide pipe;

[0030] S7. Check the overall sealing performance of the controllable negative pressure grouting test device: Close the exhaust valve and grouting valve, and open the pressure guiding valve and drain valve to check the overall sealing performance of the controllable negative pressure grouting test device; if the negative pressure liquid level in the negative pressure cylinder drops rapidly, there are large areas of unsealed points in the device, and the device needs to be disassembled and reassembled; if the negative pressure liquid level in the negative pressure cylinder drops slowly, there are small areas of unsealed points in the device, and glass glue or Vaseline needs to be applied to each connection point of the device to seal it. If the liquid level still drops slowly, the device needs to be disassembled and reassembled; if the negative pressure liquid level in the negative pressure cylinder does not change, the controllable negative pressure grouting test device is sealed.

[0031] S8. Grouting: After the controllable negative pressure grouting test device is completely sealed, close the exhaust valve, open the pressure guiding valve, the liquid drain valve and the grouting valve, and start grouting;

[0032] S9. End of grouting: After the grout has submerged the anti-buoyancy plate, close the grouting valve and the drain valve, and open the exhaust valve to eliminate the negative pressure; after the negative pressure is eliminated, close the pressure guiding valve, remove the negative pressure component and the grout delivery component, and move the grouting model component to a cool, dark place to cure until initial setting.

[0033] S10. Sample Demolding and Curing: After the sample has initially set, loosen the nut to remove the bolt, then remove the counter-pressure cover plate, anti-buoyancy plate, anti-buoyancy frame, counter-pressure base, ring clamp, and sealing strip; apply a pair of upward and downward counter-pressures to the first and second mold segments respectively, and vertically separate the first and second mold segments to demold the grouting sample. After demolding, continue curing the grouting sample until a cured grouting sample is obtained.

[0034] The beneficial effects of this invention are as follows:

[0035] (1) This invention utilizes the negative pressure generated by gravity in a closed container as the power source for grouting. Compared with traditional presses, the negative pressure assembly has many advantages such as simple structure, easy operation, low cost, strong controllability, high safety, and no influence from electricity. In addition, the range of negative pressure generated can be adjusted by the height of the liquid level in the negative pressure cylinder and the density of the negative pressure liquid, which greatly improves the applicability of this invention.

[0036] (2) This invention divides the grouting bucket into two parts, a first mold segment and a second mold segment, which reduces the lateral pressure between the grouting bucket and the sample, thereby reducing the frictional resistance between the sample and the grouting bucket and significantly reducing the difficulty of demolding. During demolding, a pair of upward and downward opposing pressures are applied to the first mold segment and the second mold segment respectively, causing the first mold segment and the second mold segment to slide in opposite directions to demold, which greatly reduces the difficulty of demolding and sampling, and at the same time reduces the disturbance to the sample.

[0037] (3) The slurry storage tank of the present invention is set with a top opening and is located at a low position, so the slurry can be manually stirred during the grouting process, avoiding slurry segregation and sedimentation, and ensuring the uniformity of the slurry; the grouting model components of the present invention are reasonably arranged and evenly distributed, and the filter plate and the pad layer avoid the blockage of the slurry pipe and the piping phenomenon of the sample; the anti-floating plate and the anti-floating frame prevent the sample from floating.

[0038] (4) The fixing unit and sealing unit of the present invention ensure the sealing performance and feasibility of the device; the measuring unit enables the test personnel to easily and accurately observe the negative pressure value, grouting process and grouting volume, avoiding the errors caused by uncertain factors such as equipment accuracy of traditional pressure gauges and flow meters, ensuring the accuracy of the test while reducing the cost of test equipment.

[0039] (5) The present invention is simple to operate, has small experimental error, greatly reduces economic costs, and all components can be recycled and reused. Attached Figure Description

[0040] Figure 1 This is a front view of the controllable negative pressure grouting test device of the present invention;

[0041] Figure 2 This is a schematic diagram of the overall structure of the controllable negative pressure grouting test device of the present invention;

[0042] Figure 3 For the present invention Figure 1 Exploded view of the grouting model components;

[0043] Figure 4 For the present invention Figure 1 Schematic diagram of the structure of the medium and negative pressure components;

[0044] Figure 5 For the present invention Figure 2 Schematic diagram of the middle lobe structure;

[0045] Figure 6 For the present invention Figure 3 Schematic diagram of the structure of the anti-ship floating frame;

[0046] Figure 7 For the present invention Figure 3 Schematic diagram of the structure of the counter-pressure cover plate;

[0047] Figure 8 For the present invention Figure 3 Schematic diagram of the structure of the counter-pressure base;

[0048] Figure 9 For the present invention Figure 3 A schematic diagram of the structure of a medium-strength floating plate or filter plate;

[0049] Figure 10 For the present invention Figure 2 Schematic diagram of the structure of the medium-speed slurry transport assembly;

[0050] Figure 11 This is a flowchart of the grouting method of the present invention.

[0051] 100. Grouting model assembly; 110. Grouting bucket; 111. First mold segment; 112. Second mold segment; 120. Fixing unit; 121. Counterpressure cover plate; 122. Counterpressure base; 130. First limiting unit; 131. Screw; 132. Nut; 140. Sealing unit; 141. Sealing strip; 142. Circular sealing gasket; 143. Sleeve; 150. Filtering unit; 151. Filter plate; 160. Second limiting unit; 161. Anti-buoyancy frame; 162. Anti-buoyancy plate; 170. Fastening unit; 171. Ring clamp; 180. Measuring unit; 181. First scale; 182. Second scale; 183. Third scale; 200. Negative pressure assembly; 201. Negative pressure cylinder; 210. Drainage unit; 211. Drainage pipe; 212. Drainage valve; 220. Exhaust unit; 221. Exhaust pipe; 222. Exhaust valve; 230. Pressure guiding unit; 231. Liquid inlet pressure guiding pipe; 232. First pressure guiding pipe; 233. Second pressure guiding pipe; 234. Pressure guiding valve; 300. Grout delivery assembly; 301. Grout storage tank; 302. First grout guiding pipe; 303. Second grout guiding pipe; 304. Grouting valve. Detailed Implementation

[0052] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0053] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0054] Example 1:

[0055] like Figure 1 As shown, a controllable negative pressure grouting test device includes a grouting model assembly 100, a filter unit 150, a second limiting unit 160, a fastening unit 170, a negative pressure assembly 200, and a grout delivery assembly 300.

[0056] The grouting model assembly 100 includes an assemblable and sealable grouting tank 110 for containing samples, and a fixing unit 120 for fixing the grouting tank 110; the grouting model assembly 100 also includes a first limiting unit 130 for limiting the grouting tank 110 and the fixing unit 120, and a sealing unit 140 for sealing the grouting tank 110 and the space between the grouting tank 110 and the fixing unit 120; a filter unit 150 is located in the lower part of the inner cavity of the grouting tank 110 to ensure uniform grouting and prevent the sample in the grouting tank 110 from falling into the bottom surface of the grouting tank 110. The second limiting unit 160 is located in the upper part of the inner cavity of the grouting tank 110 to limit the height of the sample inside the grouting tank 110 and prevent the sample from floating; the fastening unit 170 is located in the outer circumference of the grouting tank 110 to provide a ring constraint for the grouting tank 110; the negative pressure component 200 is connected to the upper end of the grouting model component 100 to generate negative pressure and allow air in the grouting model component 100 to be discharged; the grout delivery component 300 is connected to the lower end of the grouting model component 100, and when the negative pressure component 200 generates negative pressure, it allows the grout to flow into the grouting tank 110.

[0057] like Figure 2 , Figure 4 , Figure 6 , Figure 7 As shown, the grouting tank 110 includes a first mold segment 111 and a second mold segment 112 that interlock with each other; the fixing unit 120 includes a pressure cover plate 121 and a pressure base 122. The pressure cover plate 121 is located at the upper end of the first mold segment 111 and the second mold segment 112, and the pressure base 122 is located at the lower end of the first mold segment 111 and the second mold segment 112. Both the pressure cover plate 121 and the pressure base 122 have slots with the same cross-section as the first mold segment 111 and the second mold segment 112. The slots are used to limit and fix the first mold segment 111 and the second mold segment. 112; The first limiting unit 130 includes at least three screws 131. The counter-pressure cover plate 121 has a first screw hole corresponding to the number of screws 131. The counter-pressure base 122 has a second screw hole corresponding to the number of screws 131. Each screw 131 passes through the first screw hole and is located in the second screw hole. Each screw 131 is provided with a nut 132. The counter-pressure cover plate 121 and the counter-pressure base 122 are limited and connected by screws 131 and nuts 132. The screws 131 are located on the outer walls of the first mold segment 111 and the second mold segment 112.

[0058] Specifically, the first module 111 and the second module 112 are symmetrically divided from a transparent acrylic cylinder open at both ends. The counter-pressure cover 121 is made of transparent acrylic to facilitate observation of the grouting process and effect of the grouting tank 110, but its thickness should meet the rigidity requirements to prevent deformation under stress from adversely affecting the sealing performance of the grouting tank 110. The counter-pressure base 122 is made of acrylic or stainless steel plate with a certain thickness to ensure sufficient rigidity. Three nuts 132 are provided and are evenly spaced along the circumference of the grouting tank 110. The counter-pressure cover 121 and the counter-pressure base 122 are connected by three screws 131 and nuts 132 for limiting.

[0059] By dividing the grouting tank 110 into two parts, the first mold segment and the second mold segment, the lateral pressure between the grouting tank 110 and the sample is reduced, thereby reducing the frictional resistance between the sample and the grouting tank 110 and significantly reducing the difficulty of demolding. During demolding, a pair of upward and downward opposing pressures are applied to the first mold segment and the second mold segment respectively, causing the first mold segment and the second mold segment to slide in opposite directions for demolding, which greatly reduces the difficulty of demolding and sampling, and at the same time reduces the disturbance to the sample.

[0060] like Figure 2 , Figure 5 , Figure 8 The filter unit 150 shown includes a filter plate 151 located in the lower part of the inner cavity of the grouting tank 110. A pad layer (not shown in the figure) is laid below the filter plate 151 to support the filter plate 151 and to make the grouting uniform. The second limiting unit 160 includes an anti-buoyancy plate 162 located below the counter-pressure cover plate 121. An anti-buoyancy frame 161 is provided between the anti-buoyancy plate 162 and the counter-pressure cover plate 121.

[0061] Specifically, the anti-buoyancy plate 162 is located at the top of the sample, and the anti-buoyancy frame 161 is located between the counter-pressure cover plate 121 and the anti-buoyancy plate 162. The anti-buoyancy plate 162 and the anti-buoyancy frame 161 work together to control the sample height and prevent the sample from floating. The filter plate 151 is located at the bottom of the sample and is about 3cm-5cm higher than the grouting valve 304. It is used to prevent the sample from sinking and clogging the first grout guide pipe 302 and the grouting valve 304, and to ensure the uniformity of the grout. The anti-buoyancy frame 161 is welded from two stainless steel rings and three stainless steel rods. The anti-buoyancy frame 161 is located between the anti-buoyancy plate 162 and the counter-pressure cover plate 121. The position of the anti-buoyancy plate 162 is controlled by the height of the anti-buoyancy frame 161, thereby controlling the sample height and preventing the sample from floating. The sample height should be calculated in advance before the test to determine the height of the anti-buoyancy frame 161.

[0062] Specifically, both the anti-buoyancy plate 162 and the filter plate 151 are circular plates with the same inner diameter as the grouting tank 110, and have densely packed small holes. Both the anti-buoyancy plate 162 and the filter plate 151 are made of acrylic or stainless steel and have a certain thickness to prevent deformation due to insufficient rigidity, which would affect the sealing performance of the device and the integrity of the sample. The height of the anti-buoyancy frame 161 varies depending on the sample height; simply replace the anti-buoyancy frame 161 with one of the corresponding height for each sample height.

[0063] Furthermore, the fastening unit 170 includes at least three rings 171 evenly arranged from bottom to top along the outer walls of the first mold lobe 111 and the second mold lobe 112. The rings 171 apply lateral annular constraints to the first mold lobe 111 and the second mold lobe 112, so that the first mold lobe 111 and the second mold lobe 112 are tightly fitted together.

[0064] Specifically, at least two or three rings 171 are evenly provided on the outer walls of the first mold segment 111 and the second mold segment 112 from bottom to top, for assembling the first mold segment 111 and the second mold segment 112 into a grouting tank 110. The rings 171 are fitted onto the outside of the first mold segment 111 and the second mold segment 112 to reinforce the first mold segment 111 and the second mold segment 112 and prevent displacement or misalignment at the connection between the first mold segment 111 and the second mold segment 112.

[0065] like Figure 3 As shown, the negative pressure assembly 200 includes a negative pressure cylinder 201. A drain unit 210 is provided on the side wall near the bottom of the negative pressure cylinder 201, and an exhaust unit 220 and a pressure guiding unit 230 are respectively provided at the top of the negative pressure cylinder 201. A first pressure guiding pipe 232 is provided at the end of the inlet pressure guiding pipe 231 away from the negative pressure cylinder 201, and a second pressure guiding pipe 233 is provided at the end of the first pressure guiding pipe 232 away from the inlet pressure guiding pipe 231. The second pressure guiding pipe 233 is connected to the back pressure cover plate 121. The functions of the inlet pressure guiding pipe 231 are twofold: first, to inject negative pressure liquid into the negative pressure cylinder 201 before the experiment begins; and second, to connect with the first pressure guiding pipe 232 during the experiment for pressure conduction.

[0066] The drainage unit 210 includes a drainage pipe 211 disposed on the side wall near the bottom of the negative pressure cylinder 201 with the outlet facing upward, and a drainage valve 212 disposed on the drainage pipe 211; the venting unit 220 includes a venting pipe 221 disposed on the upper end of the negative pressure cylinder 201 and located on the side of the inlet pressure guiding pipe 231, and a venting valve 222 disposed on the venting pipe 221; the pressure guiding unit 230 includes an inlet pressure guiding pipe 231, a first pressure guiding pipe 232, and a second pressure guiding pipe 233, one end of the second pressure guiding pipe 233 is connected to the back pressure cover plate 121, the other end of the second pressure guiding pipe 233 is connected to the first pressure guiding pipe 232, and a pressure guiding valve 234 is disposed on the second pressure guiding pipe 233.

[0067] Specifically, the negative pressure cylinder 201 is a closed cylinder at both ends, made of a material with high transparency and low deformation, preferably acrylic, to facilitate accurate reading of the liquid level inside the negative pressure cylinder 201. The outlet of the drain pipe 211 faces upward to prevent outside air from flowing back into the negative pressure cylinder 201 during drainage. The pressure guiding valve 234 is used to discharge air from the grouting tank 110 to create negative pressure; when installing the second pressure guiding pipe 233, it should first be fixed with special glue, and then sealed and reinforced with glass glue to ensure the firmness and sealing between it and the counterpressure cover plate 121.

[0068] The first module 111, the second module 112, and the negative pressure cylinder 201 are all cylindrical structures made of acrylic plates to facilitate observation of the entire test process.

[0069] The negative pressure cylinder 201 has a drain pipe 211 with the outlet facing upward on the side wall near the bottom. The drain pipe 211 is equipped with a drain valve 212. The top of the negative pressure cylinder 201 is equipped with an exhaust pipe 221 and an inlet pressure guiding pipe 231. The exhaust pipe 221 is equipped with an exhaust valve 222. The inlet pressure guiding pipe 231 is connected to the first pressure guiding pipe 232.

[0070] By utilizing the negative pressure generated by gravity within a sealed container as the power source for grouting, the negative pressure assembly 200 offers numerous advantages over traditional presses, including simple structure, easy operation, low cost, strong controllability, high safety, and independence from electrical interference. Furthermore, the range of negative pressure it generates can be adjusted by varying the liquid level within the negative pressure cylinder 201 and the density of the negative pressure liquid; different liquid densities greatly enhance the applicability of this invention. For example, if a higher grouting negative pressure is required, a high-density liquid such as saturated saline solution can be used to generate a greater negative pressure.

[0071] The grout delivery assembly 300 further includes a grout storage tank 301 with an open top and a first grout guide pipe 302 disposed at the bottom of the grouting tank 110, a second grout guide pipe 303 communicating with the first grout guide pipe 302, one end of the second grout guide pipe 303 away from the first grout guide pipe 302 extending into the grout storage tank 301, and a grouting valve 304 disposed on the first grout guide pipe 302; the filter plate 151 is disposed at a position higher than the first grout guide pipe 302.

[0072] Specifically, there can be two first grout pipes 302, which are symmetrically arranged on both sides of the bottom of the grouting tank 110. Each first grout pipe 302 is equipped with a grouting valve 304, and each first grout pipe 302 is connected to a second grout pipe 303. The two second grout pipes 303 output grout to a main pipe, and the other end of the main pipe extends into the grout storage tank 301.

[0073] Specifically, a round hole for installing the first grout guide pipe 302 is opened on one side of the bottom of the first mold segment 111 or the second mold segment 112. The grouting valve 304 is used to control the flow of grout into the grouting tank 110. When installing the first grout guide pipe 302, it should be fixed and connected with special glue first, and then sealed and reinforced with glass glue to ensure the firmness and sealing of the grouting tank 110. The upper end of the first mold segment 111 and the second mold segment 112 is provided with a pressure-reducing cover plate 121. The pressure-reducing cover plate 121 is connected to the second pressure guide pipe 233. The second pressure guide pipe 233 is provided with a pressure-reducing valve 234. The second pressure guide pipe 233 is connected to the first pressure guide pipe 232. The first mold segment 111 and the second mold segment 112 are provided with an anti-buoyancy frame 161, an anti-buoyancy plate 162 and a filter plate 151 from top to bottom. Before grouting, a cushion layer, preferably a pebble layer, is laid under the filter plate 151 to support the filter plate 151, prevent the sample from sinking and clogging the first grout guide pipe 302 and the grouting valve 304, and ensure the uniformity of grouting. The first grout guide pipe 302 is connected to the side wall of the first mold segment 111 and the second mold segment 112 near the bottom. The first grout guide pipe 302 is equipped with a grouting valve 304, which is connected to the second grout guide pipe 303. The main pipe of the second grout guide pipe 303 extends into the grout storage tank 301.

[0074] Specifically, the grout storage tank 301 is a non-sealed container with an opening at the top. Transparent and non-deformable materials are preferred to facilitate observation of the grout volume. During grouting, the grout should be continuously stirred to prevent segregation or sedimentation. Because the grout storage tank 301 has a top opening and is located at a relatively low height, the grout can be manually stirred during the grouting process, avoiding segregation and sedimentation and ensuring the uniformity of the grout.

[0075] Specifically, the drain valve 212, the pressure guide valve 234, and the grouting valve 304 are all double-way ball valves. The grout flow rate is controlled by turning the opening angle of each double-way ball valve, thereby controlling the grouting rate and the negative pressure.

[0076] Specifically, the grouting model components 100 are arranged reasonably and evenly, and the filter plate 151 and the cushion layer prevent the sample from clogging the grout pipe and causing piping; the anti-buoyancy plate 162 and the anti-buoyancy frame 161 prevent the sample from floating.

[0077] Furthermore, the sealing unit 140 includes a sealing strip 141 disposed between the first mold segment 111 and the second mold segment 112, and a circular sealing gasket 142 disposed in the slot; the sealing unit 140 also includes a sleeve 143 connecting the hydraulic pressure guide tube 4 with the first pressure guide tube 232, the second pressure guide tube 233 with the first pressure guide tube 232, and the first slurry guide tube 302 with the second slurry guide tube 303.

[0078] Specifically, the sealing assembly includes a sleeve 143, a sealing strip 141, and a circular sealing gasket 142. The sealing strip 141 is sandwiched between the first mold segment 111 and the second mold segment 112. A lateral annular constraint is applied to the first mold segment 111 and the second mold segment 112 by a ring clamp 171, ensuring that the first mold segment 111 and the second mold segment 112 are tightly fitted to the sealing strip 141. The sealing strip 141 is made of rubber, and its main function is to increase the friction between the first mold segment 111 and the second mold segment 112 while ensuring the sealing performance of the grouting tank 110, preventing grout leakage, air leakage, and other phenomena from occurring at the contact surface between the first mold segment 111 and the second mold segment 112. The circular sealing gasket 142 is also made of rubber, and circular sealing gaskets 142 are provided between the grouting tank 110 and the counterpressure cover plate 121 and the counterpressure base 122 to ensure the sealing performance of the grouting tank 110. The liquid inlet pressure guide pipe 231 is connected to the first pressure guide pipe 232 through the sleeve 143, and the second pressure guide pipe 233 is connected to the first pressure guide pipe 232 through the sleeve 143, which is used to ensure the conduction of negative pressure. The first slurry guide pipe 302 is connected to the second slurry guide pipe 303 through the sleeve 143, which is used to ensure the delivery of slurry.

[0079] Specifically, during the test, an appropriate amount of glass glue or petroleum jelly should be applied to the locations of sleeve 143, sealing strip 141 and round sealing gasket 142 to ensure the sealing of the entire device.

[0080] Furthermore, the controllable negative pressure grouting test device also includes a measuring unit 180. The measuring unit 180 includes a first scale 181 located on the side wall of the negative pressure cylinder 201, a second scale 182 located on the first mold segment 111 or the second mold segment 112, and a third scale 183 located on the side wall of the grout storage tank 301. The measuring unit 180 allows test personnel to easily and accurately observe the negative pressure value, grouting process, and grouting volume, avoiding errors caused by uncertainties such as equipment accuracy in traditional pressure gauges and flow meters, ensuring test accuracy while reducing the cost of test equipment.

[0081] Specifically, the drain valve 212 is used to control the discharge of negative pressure liquid from the negative pressure cylinder 201 to form a negative pressure; the exhaust valve 222 is used to control the discharge of gas from the negative pressure cylinder 201 to facilitate the injection of negative pressure liquid into the negative pressure cylinder 201; the pressure guiding valve 234 is used to control the discharge of gas from the grouting tank 110; the grouting valve 304 is used to control the flow of grout; and the first scale 181 is used to observe the liquid level height in the negative pressure cylinder 201 to facilitate the calculation of the negative pressure value. The experimenter can use the liquid pressure formula p = -ρ 液 gh calculates the negative pressure value, where p is the unit of negative pressure: kPa, ρ 液The unit for density of the negative pressure liquid is kg / m³, g is the unit for gravity coefficient (N / kg), and h is the unit for the liquid level height of the negative pressure liquid inside the negative pressure cylinder 201 (m). The second scale 182 is used to observe the grouting progress. The third scale 183 is used to observe the remaining grout height, which is convenient for calculating the grouting volume. The experimenter can calculate the grouting volume using the volume formula V = SΔh, where V is the volume of grouting liquid already injected, i.e., the grouting volume (m³). 3 S represents the bottom area of ​​the slurry storage tank 301, in m². 2 △h is the height of the slurry drop in the slurry storage tank 301, in meters.

[0082] Example 2

[0083] like Figure 9 As shown, the method for grouting using a controllable negative pressure grouting test device includes the following steps:

[0084] S1. Assemble the grouting tank 110: Place the sealing strip 141 between the first mold segment 111 and the second mold segment 112, and put the ring hoop 171 on the outside of the first mold segment 111 and the second mold segment 112 and tighten it so that the first mold segment 111 and the second mold segment 112 form the grouting tank 110; place the round sealing gasket 142 in the slots of the counter-pressure cover plate 121 and the counter-pressure base 122, and then place the grouting tank 110 in the slot of the counter-pressure base 122.

[0085] S2. Laying the filter unit 150: Lay a pebble layer at the bottom of the grouting tank 110, so that the pebble layer is above the first grout pipe 302 to a certain height, and then place the filter plate 151 on the upper end of the pebble layer.

[0086] S3. Sample laying: Select samples according to the test requirements, weigh the samples, and slowly lay the samples flat on the filter plate 151. After the samples are laid, place the anti-buoyancy plate 162 on the upper end of the samples and place the anti-buoyancy frame 161 on the anti-buoyancy plate 162. The height of the anti-buoyancy frame 161 is pre-selected according to the required height of the samples.

[0087] S4. Assemble the counter-pressure cover plate 121 and the second limiting unit 160: Place the counter-pressure cover plate 121 on the grouting bucket 110 and position the grouting bucket 110 in the slot of the counter-pressure cover plate 121; then pass the screw 131 through the first screw hole and position it in the second screw hole, and tighten the nut 132 to press the counter-pressure cover plate 121 and the counter-pressure base 122 together and fit tightly against the grouting bucket 110.

[0088] S5. Assemble the slurry delivery assembly 300: Connect the first slurry guide pipe 302 to the second slurry guide pipe 303, with the main pipe of the second slurry guide pipe 303 extending into the slurry storage tank 301; prepare the slurry and place the prepared slurry into the slurry storage tank 301.

[0089] S6. Assemble the negative pressure assembly 200 and connect it to the grouting assembly. Open the exhaust valve 222, close the drain valve 212, and inject negative pressure liquid into the negative pressure cylinder 201 through the inlet pressure guide pipe 231; connect the inlet pressure guide pipe 231 to the first pressure guide pipe 232 with the sleeve 143, and connect the second pressure guide pipe 233 to the first pressure guide pipe 232;

[0090] S7. Check the overall sealing of the device.

[0091] Close the exhaust valve 222 and the grouting valve 304, and open the pressure guiding valve 234 and the drain valve 212. If the negative pressure liquid level in the negative pressure cylinder 201 drops rapidly, it indicates that there are large-scale unsealed points in the device, and the device needs to be disassembled and reassembled. If the negative pressure liquid level in the negative pressure cylinder 201 drops slowly, it indicates that there are small-scale unsealed points in the device, and glass glue or petroleum jelly needs to be applied to each connection point to seal it. If the liquid level still drops slowly, the device needs to be disassembled and reassembled. If the negative pressure liquid level in the negative pressure cylinder 201 does not change, the controllable negative pressure grouting test device is sealed.

[0092] S8. Grouting: Close the exhaust valve 222, open the pressure guide valve 234, the liquid drain valve 212 and the grouting valve 304, and start grouting;

[0093] Record the liquid level in the negative pressure cylinder 201 at all times and calculate the magnitude of the negative pressure it generates (using the liquid pressure formula p = -ρ). 液 gh calculates the negative pressure value, where p is the unit of negative pressure: kPa, ρ 液 The unit for density of the negative pressure liquid is kg / m³, g is the unit for gravity coefficient (N / kg), and h is the unit for the liquid level height of the negative pressure liquid in the negative pressure cylinder 201 (m). The flow rate of the negative pressure liquid in the negative pressure cylinder 201 is controlled by the opening of the drain valve 212, thereby controlling the negative pressure. The grouting speed is controlled by the opening of the grouting valve 304. During the grouting process, the grout in the grout storage tank 301 needs to be continuously stirred to avoid segregation or sedimentation.

[0094] S9. End of grouting: After the grout has submerged the anti-buoyancy plate 162, close the grouting valve 304 and the drain valve 212, and open the exhaust valve 222 to eliminate the negative pressure; after the negative pressure is eliminated, close the pressure guiding valve 234, remove the negative pressure component 200 and the grout delivery component 300, and move the grouting model component 100 to a cool, dark place for sealed curing until initial setting.

[0095] S10. Sample demolding and curing: After the sample has initially set, tighten nut 132 to remove screw 131, then remove counterpressure cover plate 121, anti-buoyancy plate 162, anti-buoyancy frame 161, counterpressure base 122, ring hoop 171 and sealing strip 141; apply a pair of upward and downward reverse pressures to the first mold piece 111 and the second mold piece 112 respectively, and slowly vertically remove the first mold piece 111 and the second mold piece 112 to demold the grouting sample. After demolding, continue curing the grouting sample until the cured grouting sample is obtained.

[0096] If demolding still fails when a pair of reverse pressures are applied to the first mold segment 111 and the second mold segment 112, do not force demolding by increasing the pressure excessively. Instead, slowly and repeatedly insert a narrow, long steel strip vertically between the inner wall of the grouting bucket 110 and the outer periphery of the sample along the circumference, and then pull out the narrow, long steel strip to reduce the frictional resistance between the sample and the grouting bucket 110. Then repeat the above steps of applying reverse pressure until demolding. After demolding, continue to cure the sample for the predetermined time.

[0097] In summary, the device of this invention is suitable for grouting tests on various soil samples in the laboratory, including but not limited to peat soil, silt, silt, and sand. After grouting, the samples need to be cured until initial setting before demolding. The initial setting time varies for different soil samples, depending on factors such as soil type, type of curing agent, water-cement ratio, ambient temperature, and humidity. The demolding time should be determined based on the actual conditions during the test.

[0098] As can be seen, the present invention is simple to operate, has small experimental error, greatly reduces economic costs, and all components can be recycled and reused.

[0099] The specific embodiments of the invention have been described in detail above, but these are merely examples, and the invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications or substitutions to the invention are also within the scope of this invention. Therefore, all equivalent transformations, modifications, and improvements made without departing from the spirit and principles of this invention should be included within the scope of this invention.

Claims

1. A controllable negative pressure grouting test device, characterized in that, include: Grouting model assembly (100) includes an assemblable and sealable grouting bucket (110) for holding a sample, and a fixing unit (120) for fixing the grouting bucket (110). The fixing unit (120) includes a counter-pressure cover plate (121) and a counter-pressure base (122). The grouting model assembly (100) also includes a first limiting unit (130) for limiting the grouting bucket (110) and the fixing unit (120), and a sealing unit (140) for sealing the grouting bucket (110) and the fixing unit (120). A filter unit (150) is located in the lower part of the inner cavity of the grouting tank (110) to ensure uniform grouting and prevent the sample in the grouting tank (110) from falling into the bottom surface of the grouting tank (110) and clogging the grout delivery assembly (300). The second limiting unit (160) is located in the upper part of the inner cavity of the grouting bucket (110) to limit the height of the sample inside the grouting bucket (110) and prevent the sample from floating. A fastening unit (170) is located on the outer periphery of the grouting barrel (110) to provide a circumferential constraint to the grouting barrel (110); A negative pressure assembly (200) is connected to the upper end of the grouting model assembly (100) to generate negative pressure and expel air from the grouting model assembly (100); A grout delivery assembly (300) is connected to the lower end of the grouting model assembly (100). When the negative pressure assembly (200) generates negative pressure, the grout is injected into the grouting tank (110). The negative pressure assembly (200) includes a negative pressure cylinder (201), a drain unit (210) is provided on the side wall near the bottom of the negative pressure cylinder (201), and an exhaust unit (220) and a pressure guiding unit (230) are respectively provided on the top of the negative pressure cylinder (201). The draining unit (210) includes a drain pipe (211) disposed on the side wall near the bottom of the negative pressure cylinder (201) with the outlet facing upward, and a drain valve (212) is provided on the drain pipe (211); the pressure guiding unit (230) includes an inlet pressure guiding pipe (231), a first pressure guiding pipe (232), a second pressure guiding pipe (233) and a pressure guiding valve (234), one end of the second pressure guiding pipe (233) is connected to the back pressure cover plate (121), and the other end of the second pressure guiding pipe (233) is connected to the first pressure guiding pipe (232), and a pressure guiding valve (234) is provided on the second pressure guiding pipe (233); the exhaust unit (220) includes an exhaust pipe (221) disposed at the upper end of the negative pressure cylinder (201) and located on one side of the inlet pressure guiding pipe (231), and an exhaust valve (222) is provided on the exhaust pipe (221).

2. The controllable negative pressure grouting test device as described in claim 1, characterized in that, The grouting tank (110) includes a first mold segment (111) and a second mold segment (112) that interlock with each other; the counter-pressure cover plate (121) is located at the upper end of the first mold segment (111) and the second mold segment (112), and the counter-pressure base (122) is located at the lower end of the first mold segment (111) and the second mold segment (112). Both the counter-pressure cover plate (121) and the counter-pressure base (122) have slots with the same cross-section as the first mold segment (111) and the second mold segment (112). These slots are used to limit and fix the first mold segment (111) and the second mold segment (112); the first limiting unit (130) includes... It includes at least three screws (131), the counter-pressure cover plate (121) is provided with a first screw hole corresponding to the number of screws (131), the counter-pressure base (122) is provided with a second screw hole corresponding to the number of screws (131), each screw (131) passes through the first screw hole and is located in the second screw hole, and each screw (131) is provided with a nut (132); the counter-pressure cover plate (121) and the counter-pressure base (122) are connected by screws (131) and nuts (132) for limiting connection; the screws (131) are located outside the first mold segment (111) and the second mold segment (112).

3. The controllable negative pressure grouting test device as described in claim 2, characterized in that, The filter unit (150) includes a filter plate (151) located in the lower part of the inner cavity of the grouting tank (110), and a pad layer is laid under the filter plate (151) to support the filter plate (151) and make the grouting uniform; the second limiting unit (160) includes an anti-buoyancy plate (162) located below the counter-pressure cover plate (121), and an anti-buoyancy frame (161) is provided between the anti-buoyancy plate (162) and the counter-pressure cover plate (121).

4. The controllable negative pressure grouting test device as described in claim 3, characterized in that, The fastening unit (170) includes at least three rings (171) evenly arranged from bottom to top along the outer walls of the first mold lobe (111) and the second mold lobe (112). The rings (171) apply lateral ring constraints to the first mold lobe (111) and the second mold lobe (112) so that the first mold lobe (111) and the second mold lobe (112) are tightly fitted together.

5. The controllable negative pressure grouting test device as described in claim 3, characterized in that, The grouting assembly (300) includes a grout storage tank (301) with an open top and a first grout guide pipe (302) disposed at the bottom of the grouting tank (110), a second grout guide pipe (303) communicating with the first grout guide pipe (302), the end of the second grout guide pipe (303) away from the first grout guide pipe (302) extending into the grout storage tank (301), and a grouting valve (304) provided on the first grout guide pipe (302); the filter plate (151) is positioned higher than the first grout guide pipe (302).

6. The controllable negative pressure grouting test device as described in claim 5, characterized in that, The sealing unit (140) includes a sealing strip (141) disposed between the first mold segment (111) and the second mold segment (112), and a circular sealing gasket (142) disposed in the slot; the sealing unit (140) also includes a sleeve (143) connecting the liquid inlet pressure guide pipe (231) with the first pressure guide pipe (232), the second pressure guide pipe (233) with the first pressure guide pipe (232), and the first slurry guide pipe (302) with the second slurry guide pipe (303).

7. The controllable negative pressure grouting test device as described in claim 6, characterized in that, The controllable negative pressure grouting test device also includes a measuring unit (180), which includes a first scale (181) located on the side wall of the negative pressure cylinder (201), a second scale (182) located on the first mold (111) or the second mold (112), and a third scale (183) located on the side wall of the grout storage tank (301).

8. A method for grouting using the controllable negative pressure grouting test device according to any one of claims 2-7, comprising the following steps: S1. Assemble the grouting bucket (110): Place the sealing strip (141) between the first mold segment (111) and the second mold segment (112), put the ring hoop (171) on the outside of the first mold segment (111) and the second mold segment (112) and tighten it so that the first mold segment (111) and the second mold segment (112) form the grouting bucket (110); place the round sealing gasket (142) in the slots of the counter-pressure cover plate (121) and the counter-pressure base (122), and then place the grouting bucket (110) in the slot of the counter-pressure base (122); S2, Laying the filter unit (150): Lay a cushion layer at the bottom of the grouting tank (110) so that the cushion layer covers the first grouting pipe (302), and then place the filter plate (151) on the upper end of the cushion layer; S3. Laying the sample: Weigh the sample and lay it flat on the filter plate (151). After the sample is laid, place the anti-buoyancy plate (162) on the upper end of the sample and place the anti-buoyancy frame (161) on the anti-buoyancy plate (162). S4. Assemble the counter-pressure cover plate (121) and the second limiting unit (160): Place the counter-pressure cover plate (121) on the grouting bucket (110) and position the grouting bucket (110) in the slot of the counter-pressure cover plate (121); then pass the screw (131) through the first screw hole and position it in the second screw hole, and tighten the nut (132) so that the counter-pressure cover plate (121) and the counter-pressure base (122) fit tightly against the grouting bucket (110); S5. Assemble the slurry delivery assembly (300): Connect the first slurry guide pipe (302) to the second slurry guide pipe (303), with the second slurry guide pipe (303) extending into the slurry storage tank (301); prepare the slurry and place the prepared slurry into the slurry storage tank (301); S6. Assemble the negative pressure assembly (200) and connect it to the grouting assembly: Open the exhaust valve (222), close the drain valve (212), and inject negative pressure liquid into the negative pressure cylinder (201) through the inlet pressure guide pipe (231); connect the inlet pressure guide pipe (231) to the first pressure guide pipe (232) with the sleeve (143), and connect the second pressure guide pipe (233) to the first pressure guide pipe (232); S7. Check the overall sealing performance of the controllable negative pressure grouting test device: Close the exhaust valve (222) and the grouting valve (304), and open the pressure guiding valve (234) and the drain valve (212) to check the overall sealing performance of the controllable negative pressure grouting test device. S8. Grouting: After the controllable negative pressure grouting test device is completely sealed, close the exhaust valve (222), open the pressure guiding valve (234), the liquid drain valve (212) and the grouting valve (304) to start grouting; S9. End of grouting: After the grout has submerged the anti-buoyancy plate (162), close the grouting valve (304) and the drain valve (212), and open the exhaust valve (222) to eliminate the negative pressure; after the negative pressure is eliminated, close the pressure guiding valve (234), remove the negative pressure component (200) and the grout delivery component (300), and move the grouting model component (100) to a cool, dark place to cure until initial setting; S10. Sample demolding and curing: After the sample has initially set, tighten the nut (132) to remove the screw (131), and then remove the counter-pressure cover plate (121), anti-buoyancy plate (162), anti-buoyancy frame (161), counter-pressure base (122), ring hoop (171) and sealing strip (141); apply a pair of upward and downward reverse pressures to the first mold piece (111) and the second mold piece (112) respectively, and vertically separate the first mold piece (111) and the second mold piece (112) to demold the grouting sample. Then continue to cure the grouting sample until the cured grouting sample is obtained.

Images