A negative pressure deep hole grouting material and construction method

Abstract

The application belongs to the technical field of building construction and relates to a material for negative pressure type deep hole grouting and a construction method, wherein the grouting material comprises cement 60-70 parts by weight, sodium gluconate 3-5 parts by weight, hydrophobic fiber 3-15 parts by weight, silicon dioxide 10-18 parts by weight, fly ash 20-25 parts by weight, thickening agent 1.5-5 parts by weight, water reducing agent 0.01-1 part by weight, expanding agent 0.01-1 part by weight and water 50-70 parts by weight. Through improvement of the grouting material, the application simultaneously adds sodium gluconate, hydrophobic fiber and silicon dioxide and controls the adding amount, so that the grouting material is more suitable for negative pressure grouting and the problem of holes in the concrete body is solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of building construction, and relates to a material for negative pressure type deep hole grouting and a construction method. BACKGROUND

[0002] Transmission line construction refers to the process of building infrastructure such as earthwork, concrete, and steel reinforcement to support and fix the transmission line, mainly including the steps of digging, erecting, laying out, connecting, tightening, and pulling.

[0003] In the process of transmission line construction, drilling anchor holes and grouting into the anchor holes to fix anchor rods are one of the construction steps. However, for the construction of transmission lines in mountainous areas, anchor holes are often drilled in rocks to install anchor rods. In this case, due to the limitation of the construction site, the anchor holes are usually small. In the narrow anchor holes, it is difficult for cement grouting material to fill the anchor holes by seepage under its own weight. Therefore, high-pressure grouting or negative pressure grouting is currently mainly used. High-pressure grouting technology involves inserting a grouting pipe into the bottom of the anchor hole and using pressure grouting. This method can also fill the anchor hole, but it requires high-resolution equipment, and excessive pressure may cause the slurry to seep along the rock fissures, resulting in slurry leakage and running, which reduces construction efficiency. Negative pressure grouting technology involves inserting a pipe into the anchor hole using a negative pressure pump to remove air from the anchor hole, forming a negative pressure, and using the pressure difference to drive the grout into the anchor hole. Since negative pressure grouting uses atmospheric pressure as the driving force for seepage, the pressure value is small, and there is no slurry leakage and running, so it is widely used.

[0004] However, there are still some problems when using negative pressure grouting technology for grouting, especially when used for narrow and deep hole grouting operations. Grouting is not complete, and there are holes in the formed concrete, which seriously affects the strength of the concrete in the anchor hole, thereby adversely affecting the fixation of the anchor rod. SUMMARY

[0005] To solve the above problems, the present application provides a material for negative pressure type deep hole grouting, a construction method, and a construction device.

[0006] In a first aspect, the present application provides a material for negative pressure type deep hole grouting. By improving the existing grouting material, it is more suitable for deep hole negative pressure grouting. The cured concrete formed after grouting is more compact and has no holes, which can improve the strength of the concrete and strengthen the fixation of the anchor rod.

[0007] The first aspect adopts the following technical solutions:

[0008] A grouting material for negative pressure deep hole grouting comprises 60-70 parts by weight of cement, 3-5 parts by weight of sodium gluconate, 3-15 parts by weight of hydrophobic fiber, 10-18 parts by weight of silica, 20-25 parts by weight of fly ash, 1.5-5 parts by weight of thickener, 0.01-1 parts by weight of water-reducing agent, 0.01-1 parts by weight of expansion agent, and 50-70 parts by weight of water. The amount of hydrophobic fiber added is 1-3 times the amount of sodium gluconate added, and the amount of hydrophobic fiber added does not exceed the amount of silica added.

[0009] When negative pressure grouting is used, the main focus is on controlling the negative pressure environment inside the anchor hole, so that the pressure P2 at the bottom of the deep hole is negative relative to the pressure P1 of the construction environment, forming a pressure difference ΔP=P1-P2; through ΔP, the grout flows downward to fill the voids in the aggregate and quickly flows to the bottom of the area to be filled.

[0010] However, during the anchor hole grouting process in power transmission line construction in mountainous areas, the inventors found that the strength of the resulting concrete often failed to meet requirements. Observation of the concrete revealed numerous irregular pores within it, severely impacting its strength. Furthermore, given the deep and narrow nature of the anchor holes in mountainous power transmission line construction, it was speculated that the excessively rapid grout flow prevented timely air extraction and drainage, leading to pore formation. Adjustments to the negative pressure pump's suction pressure and the grout pouring speed were attempted, which had some effect, but the pore problem persisted. Moreover, the deep and narrow anchor holes in mountainous power transmission line construction, coupled with the presence of rock in the surrounding environment, meant that conventional vibration venting methods risked shattering the rock, making vibration an ineffective solution.

[0011] In the above-described solution of the present invention, the composition of the grout used for anchor holes is improved, thereby addressing the problem of hole formation by improving the performance of the grout. In the grouting material of the present invention, a certain amount of sodium gluconate, hydrophobic fibers, and silica are added, which can form air channels inside the grout during the grouting process. This allows the internal air to be promptly expelled under the suction of a negative pressure pump, resulting in a denser concrete formed by the solidification of the grout.

[0012] The key points of the above technical solution are as follows: First, sodium gluconate, hydrophobic fiber, and silica are added simultaneously. The absence of any one of them will prevent the achievement of the expected effect. Second, the relationship between the amount of hydrophobic fiber added and the amount of sodium gluconate added is crucial. Third, the amount of hydrophobic fiber added should not be too much and should not exceed the amount of silica added, otherwise a relatively complete air channel cannot be formed inside the slurry.

[0013] Further optimization involves grouting materials including 60-70 parts by weight of cement, 4 parts by weight of sodium gluconate, 12 parts by weight of hydrophobic fiber, 16-18 parts by weight of silica, 20-25 parts by weight of fly ash, 1.5-5 parts by weight of thickener, 0.01-1 parts by weight of water-reducing agent, 0.01-1 parts by weight of expansion agent, and 50-70 parts by weight of water.

[0014] Preferably, the cement is P·I 52.5 cement or P·II 52.5 cement. The effect is better with P·I 52.5 cement or P·II 52.5 cement.

[0015] Preferably, the thickener is hydroxypropyl methylcellulose, methylcellulose, or polyacrylamide, etc.

[0016] Preferably, the expanding agent is azodimethylamide or the like.

[0017] Preferably, the water-reducing agent is a polycarboxylate superplasticizer (PCE) or the like.

[0018] A second aspect of the present invention provides a deep-hole negative pressure seepage grouting construction method, comprising the following steps:

[0019] S1. Install the negative pressure pipe connected to the negative pressure pump into one side of the anchor hole until the front end of the negative pressure pipe reaches the lower part of the anchor hole, and at the same time place the anchor rod into the anchor hole;

[0020] S2. Fill the anchor holes with aggregate;

[0021] S3. Pour grouting material into the anchor hole and turn on the negative pressure pump at the same time;

[0022] S4. Control the negative pressure pipe to gradually move upward until the pipe opening reaches the anchor hole inlet position. Turn off the negative pressure pump. When the grouting material reaches the anchor hole inlet position and is roughly level, stop applying the grouting material to complete the construction.

[0023] Preferably, during the grouting process, the negative pressure pump is turned on intermittently, and during the periods when the negative pressure pump stops, an air inflation operation is performed into the anchor hole.

[0024] Specifically, the operation is as follows:

[0025] S1. Install the negative pressure pipe connected to the negative pressure pump and the air inflation pipe connected to the air inflation pump on one side of the anchor hole until the front end of the negative pressure pipe and the front end of the air inflation pipe reach the lower part of the anchor hole, and at the same time place the anchor rod in the anchor hole.

[0026] S2. Fill the anchor holes with aggregate;

[0027] S3. Pour grouting material into the anchor hole and turn on the negative pressure pump at the same time. Maintain for time T1, then turn off the negative pressure pump and turn on the air pump. Maintain for time T2, and repeat this cycle.

[0028] S4. Control the negative pressure pipe and the air inflation pipe to move upwards synchronously and gradually. During the upward movement, turn on the negative pressure pump and the air inflation pump according to the cycle in S3 until the pipe opening of the negative pressure pipe reaches the inlet position of the anchor hole. When the grouting material reaches the inlet position of the anchor hole and is roughly level, stop applying the grouting material and complete the construction.

[0029] Preferably, the aggregate has a particle size of 9-16 mm.

[0030] Preferably, the front end of the negative pressure tube is flush with the front end of the inflation tube, or the front end of the negative pressure tube extends beyond the front end of the inflation tube.

[0031] Preferably, the maximum inflation pressure of the air pump is no more than 5 MPa and the minimum inflation pressure is no less than 1 MPa.

[0032] Preferably, the anchor hole has a depth greater than 2m and a diameter less than 20cm.

[0033] Preferably, the negative pressure pump and the air pump are controlled to be turned on and off by a control component.

[0034] By implementing the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. This invention improves the grouting material by simultaneously adding sodium gluconate, hydrophobic fibers, and silica, and controlling the amount added, making it more suitable for negative pressure grouting, especially for deep and narrow anchor hole grouting, thus solving the problem of concrete pores.

[0036] 2. Based on the improved grouting material, this invention further optimizes the grouting construction method by taking into account the characteristics of the material, thereby achieving better grouting results and resulting in a concrete with fewer pores and greater strength after curing. Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0038] Example 1

[0039] This embodiment provides a grouting material for negative pressure deep hole grouting, comprising 60 parts by weight of cement, 3 parts by weight of sodium gluconate, 9 parts by weight of hydrophobic polypropylene fiber, 18 parts by weight of silica, 20 parts by weight of fly ash, 3 parts by weight of thickener, 0.05 parts by weight of water-reducing agent, 0.05 parts by weight of expanding agent, and 65 parts by weight of water. The cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0040] Example 2

[0041] This embodiment provides a grouting material for negative pressure deep hole grouting, comprising 60 parts by weight of cement, 4 parts by weight of sodium gluconate, 8 parts by weight of hydrophobic polypropylene fiber, 10 parts by weight of silica, 20 parts by weight of fly ash, 5 parts by weight of thickener, 1 part by weight of water-reducing agent, 1 part by weight of expanding agent, and 60 parts by weight of water. The cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0042] Example 3

[0043] This embodiment provides a grouting material for negative pressure deep hole grouting, comprising 65 parts by weight of cement, 5 parts by weight of sodium gluconate, 10 parts by weight of hydrophobic polypropylene fiber, 15 parts by weight of silica, 20 parts by weight of fly ash, 1.5 parts by weight of thickener, 1 part by weight of water-reducing agent, 1 part by weight of expanding agent, and 60 parts by weight of water. The cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0044] Example 4

[0045] This embodiment provides a grouting material for negative pressure deep hole grouting, comprising 70 parts by weight of cement, 3 parts by weight of sodium gluconate, 9 parts by weight of hydrophobic polypropylene fiber, 10 parts by weight of silica, 25 parts by weight of fly ash, 3 parts by weight of thickener, 1 part by weight of water-reducing agent, 1 part by weight of expanding agent, and 70 parts by weight of water. The cement is P·II 52.5 cement, the thickener is methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0046] Example 5

[0047] This embodiment provides a grouting material for negative pressure deep hole grouting, comprising 65 parts by weight of cement, 4 parts by weight of sodium gluconate, 12 parts by weight of hydrophobic polypropylene fiber, 15 parts by weight of silica, 20 parts by weight of fly ash, 1.5 parts by weight of thickener, 1 part by weight of water-reducing agent, 1 part by weight of expanding agent, and 60 parts by weight of water. The cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0048] Example 6

[0049] This embodiment provides a material for negative pressure deep hole grouting, comprising 60 parts by weight of cement, 4 parts by weight of sodium gluconate, 12 parts by weight of hydrophobic polypropylene fiber, 16 parts by weight of silica, 22 parts by weight of fly ash, 1.5 parts by weight of thickener, 1 part by weight of water-reducing agent, 1 part by weight of expanding agent, and 60 parts by weight of water. The cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0050] Comparative Example 1

[0051] Compared with Example 1, the grouting material of this comparative example includes 60 parts by weight of cement, 18 parts by weight of silica, 20 parts by weight of fly ash, 3 parts by weight of thickener, 0.05 parts by weight of water-reducing agent, 0.05 parts by weight of expanding agent, and 65 parts by weight of water. Among them, the cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0052] Comparative Example 2

[0053] Compared with Example 1, the grouting material of this comparative example includes 60 parts by weight of cement, 15 parts by weight of hydrophobic polypropylene fiber, 18 parts by weight of silica, 20 parts by weight of fly ash, 3 parts by weight of thickener, 0.05 parts by weight of water-reducing agent, 0.05 parts by weight of expanding agent, and 65 parts by weight of water. Among them, the cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0054] Comparative Example 3

[0055] Compared with Example 1, the grouting material of this comparative example includes 60 parts by weight of cement, 3 parts by weight of sodium gluconate, 18 parts by weight of silica, 20 parts by weight of fly ash, 3 parts by weight of thickener, 0.05 parts by weight of water-reducing agent, 0.05 parts by weight of expanding agent, and 65 parts by weight of water. Among them, the cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0056] Comparative Example 4

[0057] Compared with Example 1, the grouting material of this comparative example includes 60 parts by weight of cement, 3 parts by weight of sodium gluconate, 15 parts by weight of hydrophobic polypropylene fiber, 20 parts by weight of fly ash, 3 parts by weight of thickener, 0.05 parts by weight of water-reducing agent, 0.05 parts by weight of expanding agent, and 65 parts by weight of water. Among them, the cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0058] Comparative Example 5

[0059] The grouting materials in this comparative example include: 10 parts P·I 52.5 cement, 30 parts silica fume, 24.89 parts fly ash, 30 parts polystyrene particles, 5 parts cellulose ether, 0.01 parts polycarboxylate superplasticizer (PCE), 0.01 parts azodimethylamide expansion agent, and 100 parts water.

[0060] Comparative Example 6

[0061] Compared with Example 1, the grouting material of this comparative example includes 60 parts by weight of cement, 2 parts by weight of sodium gluconate, 15 parts by weight of hydrophobic polypropylene fiber, 18 parts by weight of silica, 20 parts by weight of fly ash, 3 parts by weight of thickener, 0.05 parts by weight of water-reducing agent, 0.05 parts by weight of expanding agent, and 65 parts by weight of water. Among them, the cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0062] Comparative Example 7

[0063] Compared with Example 1, the grouting material of this comparative example includes 60 parts by weight of cement, 2 parts by weight of sodium gluconate, 10 parts by weight of hydrophobic polypropylene fiber, 18 parts by weight of silica, 20 parts by weight of fly ash, 3 parts by weight of thickener, 0.05 parts by weight of water-reducing agent, 0.05 parts by weight of expanding agent, and 65 parts by weight of water. Among them, the cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0064] Comparative Example 8

[0065] Compared with Example 1, the grouting material of this comparative example includes 60 parts by weight of cement, 3 parts by weight of sodium gluconate, 2 parts by weight of hydrophobic polypropylene fiber, 18 parts by weight of silica, 20 parts by weight of fly ash, 3 parts by weight of thickener, 0.05 parts by weight of water-reducing agent, 0.05 parts by weight of expanding agent, and 65 parts by weight of water. Among them, the cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0066] Comparative Example 9

[0067] Compared with Example 1, the grouting material in this comparative example includes 60 parts by weight of cement, 3 parts by weight of sodium gluconate, 15 parts by weight of hydrophobic polypropylene fiber, 18 parts by weight of silica, 20 parts by weight of fly ash, 3 parts by weight of thickener, 0.05 parts by weight of water-reducing agent, 0.05 parts by weight of expanding agent, and 65 parts by weight of water. Among them, the cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0068] Comparative Example 10

[0069] Compared with Example 1, the grouting material in this comparative example includes 60 parts by weight of cement, 3 parts by weight of sodium gluconate, 9 parts by weight of hydrophobic polypropylene fiber, 5 parts by weight of silica, 20 parts by weight of fly ash, 3 parts by weight of thickener, 0.05 parts by weight of water-reducing agent, 0.05 parts by weight of expanding agent, and 65 parts by weight of water. The cement is P·I 52.5 cement, the thickener is hydroxypropyl methylcellulose, the expanding agent is azodimethylamide expanding agent, and the water-reducing agent is polycarboxylate superplasticizer (PCE).

[0070] Example 7

[0071] This embodiment provides a deep-hole negative pressure seepage grouting construction method, including the following steps:

[0072] S1. Install the negative pressure pipe connected to the negative pressure pump into one side of the anchor hole until the front end of the negative pressure pipe reaches the lower part of the anchor hole, and at the same time place the anchor rod into the anchor hole;

[0073] S2. Fill the anchor holes with aggregate stones, the filling amount should be enough to basically level the anchor holes. The particle size of the stones should be 9-16mm. Stones within this particle size range can leave a large number of pores for the grout to be poured in after filling. Moreover, under the action of negative pressure, the grout can be more easily and evenly dispersed in the pores between the aggregates, thus obtaining a denser concrete.

[0074] S3. Pour grouting material into the anchor hole and turn on the negative pressure pump at the same time;

[0075] S4. Control the negative pressure pipe to slowly move upward until the pipe opening reaches the anchor hole inlet position. Turn off the negative pressure pump. When the grouting material reaches the anchor hole inlet position and is roughly level, stop applying the grouting material to complete the construction.

[0076] Example 8

[0077] This embodiment provides a deep-hole negative pressure seepage grouting construction method, including the following steps:

[0078] S1. Install the negative pressure pipe connected to the negative pressure pump and the air inflation pipe connected to the air inflation pump on one side of the anchor hole until the front end of the negative pressure pipe and the front end of the air inflation pipe reach the lower part of the anchor hole, and at the same time place the anchor rod in the anchor hole.

[0079] S2. Fill the anchor holes with aggregate stones, the amount of which should be enough to basically level the anchor holes, and the particle size should be 9-16mm.

[0080] S3. Pour grouting material into the anchor hole and simultaneously turn on the negative pressure pump for time T1. Turn off the negative pressure pump and turn on the air pump for time T2. Repeat this process. During this process, control the negative pressure pipe and the air pump to move upwards gradually and slowly (try to ensure that the front end of the negative pressure pipe is higher than the grout surface) until the opening of the negative pressure pipe reaches the entrance of the anchor hole. Stop applying grouting material when the grouting material reaches the entrance of the anchor hole and is roughly level with it. The construction is now complete.

[0081] Application Example 1: Several deep holes, each 2.5 meters deep and approximately 15 cm in diameter, were constructed. The grouting materials used in the various embodiments and comparative examples, as well as the construction method of Example 7, were used to grout the deep holes.

[0082] Remove the solidified concrete and perform performance testing on the resulting concrete.

[0083] 28-day compressive strength: The compressive strength of standard test blocks cured for 28 days was measured in accordance with GB / T50081-2019 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete".

[0084] Porosity: The concrete was soaked in water for 24 hours, and the mass m1 of each sample after soaking was measured. Then, each sample was air-dried and the mass m2 of each sample was measured. The porosity P of the concrete specimen was calculated according to the following formula: P=[1-(m2-m1) / V×ρ]×100%, where: V is the volume of the cubic specimen and ρ is the density of water.

[0085] The test results are shown in Table 1.

[0086] Table 1. Performance of concrete obtained using the construction method shown in Example 7

[0087] concrete porosity 28-day compressive strength example 1 21% 79 MPa example 2 19% 81 MPa example 3 17% 86 MPa example 4 19% 82 MPa example 5 10% 92 MPa example 6 11% 90 MPa comparative example 1 41% 53 MPa comparative example 2 34% 61 MPa comparative example 3 44% 55 MPa comparative example 4 30% 49 MPa comparative example 5 39% 57 MPa comparative example 6 32% 64 MPa comparative example 7 30% 50 MPa comparative example 8 34% 66 MPa comparative example 9 39% 59 MPa comparative example 10 29% 52 MPa

[0088] Analyzing the results shown in Table 1, it can be seen that the technical solution of the present invention has significant advantages in porosity and compressive strength compared to the comparative examples. Specifically, in Comparative Example 1, no sodium gluconate or hydrophobic fiber was added, resulting in a significant increase in porosity (up to 20%) compared to Example 1, while the strength also decreased significantly. In Comparative Example 2, no sodium gluconate or silica was added, resulting in a significant increase in porosity and a significant decrease in strength compared to Example 1. In Comparative Example 3, no hydrophobic polypropylene fiber was added, resulting in a significant increase in porosity and a significant decrease in strength compared to Example 1. In Comparative Example 4, no silica was added, resulting in a significant increase in porosity and a significant decrease in strength compared to Example 1, but the decrease was smaller than that of the comparative example without hydrophobic fiber, indicating that hydrophobic fiber has a more significant impact on porosity in grouting materials. Comparative Example 5 uses a grouting material from the prior art, which has relatively poor porosity and compressive strength. Comparative Examples 6-9 adjusted the amount of sodium gluconate or hydrophobic fiber added. Compared with Comparative Example 1, the porosity was significantly increased and the compressive strength was significantly reduced. Comparative Example 10 reduced the amount of silica used, lower than the amount of hydrophobic fiber added, and the concrete performance also decreased.

[0089] The performance comparison of the various embodiments shows that the performance of Embodiments 5 and 6 is relatively superior. This may be because the ratio of sodium gluconate and hydrophobic fiber is the most suitable in these two embodiments. Under a specific ratio, sodium gluconate and hydrophobic fiber can significantly reduce porosity and improve compressive strength.

[0090] Based on the data from the combined examples and comparative examples, only when sodium gluconate, hydrophobic fibers, and silica are present simultaneously, along with basic materials such as cement, can a relatively superior porosity and strength be ultimately achieved.

[0091] Application Example 2

[0092] Several deep holes, each 2.5 meters deep and approximately 15 cm in diameter, were constructed. Grouting was performed on these deep holes using the grouting materials described in the various embodiments and comparative examples, and the construction method of Example 8. In each cycle, the negative pressure pump was maintained for 30 seconds, and the air pump was maintained for 20 seconds. The air pressure of the air pump was 3 MPa.

[0093] Remove the solidified concrete and perform performance testing on the obtained concrete, using the same method as above.

[0094] The test results are shown in Table 2.

[0095] Table 2. Performance of concrete obtained using the construction method shown in Example 8

[0096] concrete porosity 28-day compressive strength example 1 15% 86 MPa example 2 11% 91 MPa example 3 12% 94 MPa example 4 12% 93 MPa example 5 4% 112 MPa example 6 6% 108 MPa comparative example 1 45% 48 MPa comparative example 2 28% 66 MPa comparative example 3 46% 51 MPa comparative example 4 31% 49 MPa comparative example 5 42% 54 MPa comparative example 6 30% 69 MPa comparative example 7 27% 55 MPa comparative example 8 30% 66 MPa comparative example 9 34% 67 MPa comparative example 10 25% 59 MPa

[0097] Analyzing the results shown in Table 2, it can be seen that the trends in porosity and compressive strength corresponding to the examples and comparative examples are basically consistent with those in Table 1. Application Example 1 and Application Example 2 use different construction methods. In Application Example 2, the construction method of Example 8 is used, which adds an air-filling step compared to Example 7. From the perspective of porosity and compressive strength, the construction method of Example 8 is more advantageous than that of Example 7. The porosity corresponding to Examples 1-6 is significantly reduced, and the compressive strength is significantly improved. This indicates that intermittent air extraction and filling can further improve the grouting effect and has a positive effect on the porosity and compressive strength of the concrete. Although the performance of the comparative examples is also improved under the construction conditions of Example 8, the improvement is relatively small, indicating that the grouting material of the present invention has a more significant effect under the construction method of Example 8.

[0098] To further verify the key steps in the construction method of Example 8, the grouting material of Example 5 was used for the experiment in this embodiment.

[0099] Method 1: Construction method of Example 8.

[0100] Method 2: It is basically the same as Example 8, except that the inflation pressure of the air pump is set to 5MPa.

[0101] Method 3: It is basically the same as Example 8, except that the filler aggregate stone particles in step S2 are pre-added to the grouting material and mixed evenly with the grouting material, and then poured into the anchor hole together with the grouting material.

[0102] Method 4: It is basically the same as Example 8, except that the inflation pressure of the air pump is set to 7MPa.

[0103] Remove the solidified concrete and perform performance testing on the obtained concrete, using the same method as above.

[0104] The test results are shown in Table 3.

[0105] Table 3 Properties of concrete obtained by different construction methods

[0106] concrete porosity 28-day compressive strength method 1 4% 112 MPa method 2 8% 101 MPa method 3 39% 48 MPa method 4 24% 57 MPa

[0107] The results shown in Table 3, comparing Methods 2 and 4 with Method 1, indicate that the air pressure has a certain impact on the grouting effect. The comparison between Method 3 and Method 1 shows that separating the aggregate from the grouting material during construction, and adding the aggregate to the anchor hole before grouting, is beneficial for reducing porosity and improving compressive strength when combined with negative pressure construction methods.

Claims

1. A grouting material for negative pressure deep hole grouting, characterized in that, The mixture comprises 60-70 parts by weight of cement, 3-5 parts by weight of sodium gluconate, 3-15 parts by weight of hydrophobic fiber, 10-18 parts by weight of silica, 20-25 parts by weight of fly ash, 1.5-5 parts by weight of thickener, 0.01-1 parts by weight of water-reducing agent, 0.01-1 parts by weight of expanding agent, and 50-70 parts by weight of water. The amount of hydrophobic fiber added is 1-3 times the amount of sodium gluconate added, and the amount of hydrophobic fiber added does not exceed the amount of silica added.

2. The grouting material for negative pressure deep hole grouting according to claim 1, characterized in that, The grouting material includes 60-70 parts by weight of cement, 4 parts by weight of sodium gluconate, 12 parts by weight of hydrophobic fiber, 16-18 parts by weight of silica, 20-25 parts by weight of fly ash, 1.5-5 parts by weight of thickener, 0.01-1 parts by weight of water-reducing agent, 0.01-1 parts by weight of expansion agent, and 50-70 parts by weight of water.

3. A construction method for deep-hole negative pressure seepage grouting using the grouting material described in claim 1 or 2, characterized in that, Includes the following steps: S1. Install the negative pressure pipe connected to the negative pressure pump into one side of the anchor hole until the front end of the negative pressure pipe reaches the lower part of the anchor hole, and at the same time place the anchor rod into the anchor hole; S2. Fill the anchor holes with aggregate; S3. Pour the grouting material into the anchor hole and turn on the negative pressure pump at the same time; S4. Control the negative pressure pipe to gradually move upward until the pipe opening reaches the anchor hole inlet position. Turn off the negative pressure pump. When the grouting material reaches the anchor hole inlet position and is level, stop applying the grouting material to complete the construction.

4. The construction method according to claim 3, characterized in that, During the grouting process, the negative pressure pump is turned on intermittently, and air is injected into the anchor hole when the negative pressure pump stops.

5. The construction method according to claim 4, characterized in that, Includes the following steps: S1. Install the negative pressure pipe connected to the negative pressure pump and the air inflation pipe connected to the air inflation pump on one side of the anchor hole until the front end of the negative pressure pipe and the front end of the air inflation pipe reach the lower part of the anchor hole, and at the same time place the anchor rod in the anchor hole. S2. Fill the anchor holes with aggregate; S3. Pour grouting material into the anchor hole and turn on the negative pressure pump at the same time. Maintain for time T1, turn off the negative pressure pump and turn on the air pump. Maintain for time T2, and repeat this cycle. S4. Control the negative pressure pipe and the air inflation pipe to move upwards synchronously and gradually. During the upward movement, turn on the negative pressure pump and the air inflation pump according to the cycle in S3 until the pipe opening of the negative pressure pipe reaches the inlet position of the anchor hole. Stop applying the grouting material when it reaches the inlet position of the anchor hole and complete the construction.

6. The construction method according to claim 3, characterized in that, The aggregate has a particle size of 9-16 mm.

7. The construction method according to claim 5, characterized in that, The front end of the negative pressure tube is flush with the front end of the inflation tube, or the front end of the negative pressure tube extends beyond the front end of the inflation tube.

8. The construction method according to claim 5, characterized in that, The maximum inflation pressure of the air pump shall not exceed 5 MPa, and the minimum inflation pressure shall not be lower than 1 MPa.

9. The construction method according to claim 3, characterized in that, The anchor hole has a depth greater than 2m and a diameter less than 20cm.