阅读说明：本技术 一种用于隧道洞内加固的注浆浆液及注浆方法 (Grouting slurry for reinforcing tunnel and grouting method ) 是由 赵仲明 胡晖 胡军 梁忠旗 万怡 于 2021-07-28 设计创作，主要内容包括：本申请提供了一种用于隧道洞内加固的注浆浆液及注浆方法,注浆浆液包括A浆液以及B添加剂；A浆液是由水泥和水在注浆过程中先按照水灰比1:1的比例搅拌,再按照水灰比0.8～0.9：1的比例搅拌而成；B添加剂由速凝剂和高分子材料溶液在注浆过程中按照体积比1:1的比例配制而成,其中,速凝剂和高分子材料溶液的质量均占水泥质量的3％～5％。通过控制浆液凝胶时间来控制浆液的扩散范围,达到控制加固范围的目的,并且通过调节速凝剂和高分子材料溶液的添加比,从而控制浆液结石体在预设时间内的强度,即保证掌子面开挖时不会发生垮塌,又有利于隧道的掘进,解决了隧道穿越松散堆积体地层施工时,容易发生侵线,支护拱架变形的技术问题。(The application provides grouting slurry and a grouting method for reinforcing a tunnel, wherein the grouting slurry comprises slurry A and additive B; the grout A is prepared by mixing cement and water according to the proportion of 1:1 in the grouting process, and then mixing the cement and the water according to the water-cement ratio of 0.8-0.9: 1 by stirring; the additive B is prepared from an accelerator and a high polymer material solution according to the volume ratio of 1:1 in the grouting process, wherein the mass of the accelerator and the high polymer material solution accounts for 3% -5% of the mass of the cement. The diffusion range of the slurry is controlled by controlling the slurry gelling time, the purpose of controlling the reinforcing range is achieved, and the strength of the slurry concretion body in the preset time is controlled by adjusting the addition ratio of the accelerator and the high polymer material solution, so that the tunnel excavation is not prone to collapse when the tunnel face is excavated, the tunnel excavation is facilitated, and the technical problems that the tunnel easily suffers from line invasion and the support arch frame deforms when the tunnel passes through the loose accumulation body stratum are solved.)

1. The grouting slurry for reinforcing the tunnel is characterized by comprising slurry A and additive B; the grout A is prepared by mixing cement and water according to the water-cement ratio of 1-1.2: 1 in the grouting process, and then mixing the cement and the water according to the water-cement ratio of 0.8-0.9: 1 by stirring; the additive B is prepared from an accelerator and a high polymer material solution according to the volume ratio of 0.9-1.1: 1 in the grouting process, wherein the mass of the accelerator and the mass of the high polymer material solution both account for 3% -5% of the mass of the cement.

2. The grouting slurry for reinforcing the tunnel according to claim 1, wherein the grout A is prepared by mixing cement and water according to a water-cement ratio of 1:1, and then mixing the cement and the water according to a water-cement ratio of 0.85:1 by stirring; the additive B is prepared from an accelerator and a high polymer material solution according to the volume ratio of 1:1 in the grouting process, wherein the mass of the accelerator and the mass of the high polymer material solution both account for 4% of the mass of the cement.

3. The grouting slurry for reinforcing the interior of a tunnel according to claim 1, wherein the accelerating agent is a powder prepared from aluminum oxide clinker, sodium carbonate and quick lime according to a mass ratio of 1-1.2: 0.5.

4. A grouting slurry for reinforcement in a tunnel according to claim 1, wherein the solution of high molecular material is HJ520 acrylate grouting solution.

5. A grouting method for reinforcing in a tunnel hole is characterized by comprising the following steps:

s1, measuring the center line and the elevation of the tunnel, and marking the position of the small catheter according to the design;

s2, directly using the small guide pipe as a drill rod to drill holes outwards at an external insertion angle of 10 degrees along the longitudinal excavation contour line of the tunnel to reach the design depth;

s3, inserting a grouting pipe into the small guide pipe, and fixing the grouting pipe on the small guide pipe through a positioning steel plate;

s4, injecting the prepared grouting slurry into the grouting pipe, wherein the method specifically comprises the steps of mixing the additive B with the slurry A prepared by stirring cement and water according to the water-cement ratio of 1:1, injecting the mixed solution into the grouting pipe, and then injecting the additive B, the cement and the water according to the water-cement ratio of 0.8-0.9: 1 stirring and mixing the prepared slurry A, and injecting the mixed solution into the grouting pipe;

and S5, plugging the small guide pipes after grouting is finished, and repeating the step S4 to finish grouting reinforcement of each small guide pipe.

6. A grouting method for reinforcement in a tunnel according to claim 5, characterized in that after step S4, the grouting method further comprises determining the termination grouting pressure of the loose accumulation stratum according to the field grouting test and the related grouting construction experience, and ending the grouting when the real-time grouting pressure reaches the termination grouting pressure and the grouting speed is 1/4 of the starting grouting speed or the grouting amount reaches 80% or more of the designed grouting amount.

Technical Field

The invention relates to the field of tunnel construction, in particular to grouting slurry and a grouting method for reinforcing a tunnel.

Background

In tunnel construction, a loose accumulation body stratum can be encountered, a soil-rock mixture in the loose accumulation body stratum is a geologic body between a rock and a soil body, and the difference between the grouting of the accumulation body stratum and the general grouting of the rock-rock body exists because the particle size difference of rock blocks in the stratum is large and the porosity of the stratum is large. The loose accumulation body stratum is subjected to ordinary rock-soil body grouting, and due to poor stratum stability, the phenomena of line invasion and support arch frame deformation are easy to occur.

Therefore, when a loose accumulation body stratum is encountered in tunnel construction, grouting is carried out to reinforce the stratum environment, a tunnel grouting reinforcement process is developed, and slurry mixing ratio data is determined to achieve the effect of reinforcing the stratum and improving the geological environment, so that the method has very important significance.

Disclosure of Invention

In view of the above, the main purpose of the invention is to solve the technical problems that the tunnel is easy to generate line invasion and the supporting arch frame is easy to deform when the tunnel passes through the stratum of the loose accumulation body.

The invention provides grouting slurry for reinforcing a tunnel, which comprises slurry A and additive B; the grout A is prepared by mixing cement and water according to the water-cement ratio of 1-1.2: 1 in the grouting process, and then mixing the cement and the water according to the water-cement ratio of 0.8-0.9: 1 by stirring; the additive B is prepared from an accelerator and a high polymer material solution according to the volume ratio of 0.9-1.1: 1 in the grouting process, wherein the mass of the accelerator and the mass of the high polymer material solution both account for 3% -5% of the mass of the cement.

In some embodiments of the invention, the slurry A is prepared by mixing cement and water according to a water-cement ratio of 1:1, and then mixing the cement and the water according to a water-cement ratio of 0.85:1 by stirring; the additive B is prepared from an accelerator and a high polymer material solution according to the volume ratio of 1:1 in the grouting process, wherein the mass of the accelerator and the mass of the high polymer material solution both account for 4% of the mass of the cement.

In some embodiments of the invention, the accelerating agent is a powder prepared from aluminum oxide clinker, sodium carbonate and quick lime according to the mass ratio of 1-1.2: 0.5.

In some embodiments of the present invention, the polymer material solution is HJ520 acrylate grouting solution.

The invention also provides a grouting method for reinforcing the tunnel, which comprises the following steps: s1, measuring the center line and the elevation of the tunnel, and marking the position of the small catheter according to the design; s2, directly using the small guide pipe as a drill rod to drill holes outwards at an external insertion angle of 10 degrees along the longitudinal excavation contour line of the tunnel to reach the design depth; s3, inserting a grouting pipe into the small guide pipe, and fixing the grouting pipe on the small guide pipe through a positioning steel plate; s4, injecting the prepared grouting slurry into the grouting pipe, wherein the method specifically comprises the steps of mixing the additive B with the slurry A prepared by stirring cement and water according to the water-cement ratio of 1:1, injecting the mixed solution into the grouting pipe, and then injecting the additive B, the cement and the water according to the water-cement ratio of 0.8-0.9: 1 stirring and mixing the prepared slurry A, and injecting the mixed solution into the grouting pipe; and S5, plugging the small guide pipes after grouting is finished, and repeating the step (4) to finish grouting of each small guide pipe to finish the grouting reinforcement process.

In some embodiments of the invention, after step S4, the grouting method further comprises determining a termination grouting pressure for the loosely piled formation based on the in-situ grouting test and related grouting construction experience, and ending the grouting when the real-time grouting pressure reaches the termination grouting pressure and the grout inlet rate is 1/4 of the start grout inlet rate or the grout inlet rate reaches 80% or more of the design grout inlet rate.

The invention provides grouting slurry for reinforcing a tunnel and a grouting method, wherein the cement slurry is stirred according to the water-cement ratio of 1-1.2: 1 in the grouting process, and then the cement slurry is stirred according to the water-cement ratio of 0.8-0.9: 1, the diffusion range of the grout can be controlled by controlling the grout gelling time, the purpose of controlling the reinforcing range is achieved, and the strength of the grout concretion body in the preset time is controlled by adding the accelerating agent and the high polymer material solution into the cement grout and adjusting the adding ratio of the accelerating agent and the high polymer material solution, so that the tunnel is ensured not to collapse when the tunnel face is excavated, the tunnel is favorable for tunneling, and the technical problems that the tunnel is easy to have line invasion and the support arch frame is deformed when passing through the loose accumulation body stratum are solved.

Drawings

Fig. 1 is a flowchart of a grouting method for reinforcing a tunnel according to an embodiment of the present invention.

Detailed Description

The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. It should be noted that, for convenience of description, only the portions related to the related invention are shown in the drawings. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

The application provides grouting slurry for reinforcing a tunnel, which comprises slurry A and additive B; the grout A is prepared by mixing cement and water according to the water-cement ratio of 1-1.2: 1 in the grouting process, and then mixing the cement and the water according to the water-cement ratio of 0.8-0.9: 1 by stirring; the additive B is prepared from an accelerator and a high polymer material solution according to the volume ratio of 0.9-1.1: 1 in the grouting process, wherein the mass of the accelerator and the mass of the high polymer material solution both account for 3% -5% of the mass of the cement.

By applying the technical scheme of the embodiment, the slurry A is prepared by firstly stirring cement and water according to the water-cement ratio of 1:1 in the grouting process, and then stirring the mixture according to the water-cement ratio of 0.8-0.9: 1, can realize that the loose stratum obtains better slip casting effect through the concentration of control thick liquid to its gel time of thick liquid of different concentrations is different, thereby controls the diffusion scope of thick liquid through adjusting gel time, reaches the purpose of control reinforcement scope. And the strength of the grout concretion body in the preset time is controlled by adjusting the addition ratio of the accelerating agent and the high polymer material solution, so that the tunnel face is guaranteed not to collapse during excavation, tunneling of a tunnel is facilitated, and the problems of easy occurrence of line invasion and deformation of a supporting arch frame during construction of the tunnel penetrating through a loose accumulation body stratum are solved.

In some optional embodiments, the slurry A is prepared by mixing cement and water according to a water-cement ratio of 1:1, and then mixing the cement and the water according to a water-cement ratio of 0.85:1 by stirring; the additive B is prepared from an accelerator and a high polymer material solution according to the volume ratio of 1:1 in the grouting process, wherein the mass of the accelerator and the mass of the high polymer material solution both account for 4% of the mass of the cement.

In some optional embodiments, the accelerating agent is a powder prepared from aluminum oxide clinker, sodium carbonate and quick lime according to the mass ratio of 1-1.2: 0.5.

In some embodiments of the present invention, the polymer material solution is HJ520 acrylate grouting solution. The HJ520 acrylate grouting solution is a high-strength, medium-expansion and low-elasticity rubber type grouting and plugging material taking acrylate as a main component; the HJ520 consists of three components of acrylate main agent, curing agent and accelerator. The product is grouted by a double-liquid (or single-liquid) grouting pump, and a gel with certain strength and viscoelasticity is formed after solidification, so that the product can be applied to water seepage and water stop grouting of cracks, expansion joints and settlement joints of a concrete structure; grouting a seepage-proofing curtain of a foundation of the reservoir dam; and (4) plugging water leakage in various building concrete projects and the like.

As shown in fig. 1, it shows a grouting method for reinforcing in a tunnel hole of the present application, comprising the following steps: s1, measuring the center line and the elevation of the tunnel, and marking the position of the small catheter according to the design; s2, directly using the small guide pipe as a drill rod to drill holes outwards at an external insertion angle of 10 degrees along the longitudinal excavation contour line of the tunnel to reach the design depth; s3, inserting a grouting pipe into the small guide pipe, and fixing the grouting pipe on the small guide pipe through a positioning steel plate; s4, injecting the prepared grouting slurry into the grouting pipe, wherein the method specifically comprises the steps of mixing the additive B with the slurry A prepared by stirring cement and water according to the water-cement ratio of 1:1, injecting the mixed solution into the grouting pipe, and then injecting the additive B, the cement and the water according to the water-cement ratio of 0.8-0.9: 1 stirring and mixing the prepared slurry A, and injecting the mixed solution into the grouting pipe; and S5, plugging the small guide pipes after grouting is finished, and repeating the step (4) to finish grouting of each small guide pipe to finish the grouting reinforcement process.

Compared with the traditional cement slurry material grouting, the method of the embodiment has the advantages that the prepared novel grouting slurry has low slurry viscosity, good fluidity and stability and is not isolated in the grouting process, is more suitable for grouting reinforcement construction of loose accumulation body stratum, can well ensure the construction safety of the loose accumulation body stratum tunnel, and can save extra cost caused by slurry loss at a great depth.

In a specific embodiment, a grouting method for reinforcing a tunnel comprises the following steps:

1. design parameters

The small guide pipe is a hot-rolled seamless steel pipe with the outer diameter of 42mm, the wall thickness of 4mm and the length of 4.5 m. The adopted grouting pipe is 80cm long, two rows of 10 grout outlet holes with the diameter of 6mm are formed in the pipe wall of the grouting pipe within 50cm, the grout outlet holes are arranged in a quincunx shape, a mold bag with the length of 60cm is sleeved outside the grouting pipe, the mold bag is fixed at two ends of the mold bag by rubber hooping, and the mold bag is made of non-woven geotextile.

2. Measuring and positioning

And (3) accurately measuring the longitudinal line and the elevation of the tunnel, marking the position of the small guide pipe according to the design, releasing the drilling hole position on the construction working surface, and marking.

3. Grouting pipe installation

The grouting pipe is provided with a plum blossom-shaped grout outlet, the root part of the grouting pipe is connected with a positioning steel plate through threads, and the positioning steel plate is fixed on the steel arch frame through a steel wire. Firstly, connecting the grouting pipe with a positioning steel plate, sleeving a mold bag on the grouting pipe, wiping the grouting pipe into a small guide pipe, and fixing the positioning steel plate on a steel arch frame by adopting a steel wire.

4. Preparation of slurry

The cement grout is prepared by adopting a stirrer, and the porosity of the stratum of the loose accumulation body is high, and the concentration of the cement grout is adjusted to be diluted and concentrated first, so that a good grouting effect is obtained in a loose area, and therefore, the water-cement ratio is controlled to be 1:1 when each guide pipe starts grouting, and then is slowly adjusted to be 0.8: 1.

The mass of the accelerator and the mass of the HJ520 acrylate grouting solution respectively account for 3% of the mass of the cement, the mass of the accelerator and the HJ520 acrylate grouting solution is calculated according to the mass of the cement, then the accelerator and the HJ520 acrylate grouting solution are diluted by adding water and are uniformly stirred, and then the diluted accelerator and the HJ520 acrylate grouting solution are respectively poured into a stirrer.

5. Grouting

The grouting apparatus includes: grouting pump, slip casting pipe, air compressor machine, flowmeter, storage thick liquid bucket and shutoff equipment etc.. Wherein the working pressure of the grouting pump is 2.5Mpa, and the grouting pipe is a 40mm rubber pipe. The main grouting steps are as follows:

before grouting, whether equipment can normally work is firstly checked, all pipelines are communicated outside a hole for pressure testing, and the pressure testing can be carried out by using clean water. During pressure testing, if the pipeline is not communicated or the joint has water leakage, the water leakage is eliminated, and all parts of the pipeline system are kept intact and smooth. In order to prevent the grout from overflowing from the tunnel face, a closed grouting face with the thickness of 5-10 cm is required to be sprayed with concrete before grouting, and a grout stopping disc is formed. In order to prevent the grout from overflowing from other holes, grout stop plugs are required to be arranged on all the holes before grouting.

Cleaning sediments in the pipe before grouting, sequentially grouting from arch feet at two sides to the vault, diluting the grout and then concentrating the grout, increasing the grouting amount and then decreasing the grouting pressure from small to large.

According to the field grouting test and the related grouting construction experience, the stopping grouting pressure of the stratum of the loose accumulation body is determined to be 1.5-2.0 Mpa, so the grouting is stopped when the grouting pressure reaches 1.5-2.0 Mpa and the grouting speed is 1/4 of the starting grouting speed or the grouting amount reaches 80% or more of the designed grouting amount.

In the above examples, the water cement ratio was controlled to 1:1 at the time of grouting, then slowly adjusted to 0.8:1, the grout gelling time was 6 hours, and the setting accelerator and the HJ520 acrylate grouting solution, each of which was 3% by mass of the cement, were added to the cement grout, and the strength of the grout stones was 72% of the strength required for the design in 2 hours.

In another specific embodiment, a grouting method for reinforcing a tunnel comprises the following steps:

1. design parameters

The small guide pipe is a hot-rolled seamless steel pipe with the outer diameter of 42mm, the wall thickness of 4mm and the length of 4.5 m. The adopted grouting pipe is 80cm long, two rows of 10 grout outlet holes with the diameter of 6mm are formed in the pipe wall of the grouting pipe within 50cm, the grout outlet holes are arranged in a quincunx shape, a mold bag with the length of 60cm is sleeved outside the grouting pipe, the mold bag is fixed at two ends of the mold bag by rubber hooping, and the mold bag is made of non-woven geotextile.

2. Measuring and positioning

And (3) accurately measuring the longitudinal line and the elevation of the tunnel, marking the position of the small guide pipe according to the design, releasing the drilling hole position on the construction working surface, and marking.

3. Grouting pipe installation

The grouting pipe is provided with a plum blossom-shaped grout outlet, the root part of the grouting pipe is connected with a positioning steel plate through threads, and the positioning steel plate is fixed on the steel arch frame through a steel wire. Firstly, connecting the grouting pipe with a positioning steel plate, sleeving a mold bag on the grouting pipe, wiping the grouting pipe into a small guide pipe, and fixing the positioning steel plate on a steel arch frame by adopting a steel wire.

4. Preparation of slurry

The cement grout is prepared by a stirrer, and the porosity of the stratum of the loose accumulation body is high, so that the concentration of the cement grout is adjusted to be diluted and concentrated first, and a good grouting effect is obtained in a loose area, therefore, the water cement ratio is controlled to be 1.2:1 when each guide pipe starts grouting, and then is slowly adjusted to be 0.9: 1.

The mass of the accelerator and the mass of the HJ520 acrylate grouting solution respectively account for 5% of the mass of the cement, the mass of the accelerator and the HJ520 acrylate grouting solution is calculated according to the mass of the cement, and then the accelerator and the HJ520 acrylate grouting solution are diluted by adding water and are uniformly stirred and are respectively poured into a stirrer.

5. Grouting

The grouting apparatus includes: grouting pump, slip casting pipe, air compressor machine, flowmeter, storage thick liquid bucket and shutoff equipment etc.. Wherein the working pressure of the grouting pump is 2.5Mpa, and the grouting pipe is a 40mm rubber pipe. The main grouting steps are as follows:

before grouting, whether equipment can normally work is firstly checked, all pipelines are communicated outside a hole for pressure testing, and the pressure testing can be carried out by using clean water. During pressure testing, if the pipeline is not communicated or the joint has water leakage, the water leakage is eliminated, and all parts of the pipeline system are kept intact and smooth. In order to prevent the grout from overflowing from the tunnel face, a closed grouting face with the thickness of 5-10 cm is required to be sprayed with concrete before grouting, and a grout stopping disc is formed. In order to prevent the grout from overflowing from other holes, grout stop plugs are required to be arranged on all the holes before grouting.

Cleaning sediments in the pipe before grouting, sequentially grouting from arch feet at two sides to the vault, diluting the grout and then concentrating the grout, increasing the grouting amount and then decreasing the grouting pressure from small to large.

According to the field grouting test and the related grouting construction experience, the stopping grouting pressure of the stratum of the loose accumulation body is determined to be 1.5-2.0 Mpa, so the grouting is stopped when the grouting pressure reaches 1.5-2.0 Mpa and the grouting speed is 1/4 of the starting grouting speed or the grouting amount reaches 80% or more of the designed grouting amount.

In the above examples, the water cement ratio was controlled to 1.2:1 at the time of grouting, then slowly adjusted to 0.9:1, the grout gelling time was 7 hours, and the setting accelerator and the HJ520 acrylate grouting solution, each of which was 5% by mass of the cement mass, were added to the cement grout, and the strength of the grout stones was 80% of the strength required for the design within 2 hours.

In another specific embodiment, a grouting method for reinforcing a tunnel comprises the following steps:

1. design parameters

The small guide pipe is a hot-rolled seamless steel pipe with the outer diameter of 42mm, the wall thickness of 4mm and the length of 4.5 m. The adopted grouting pipe is 80cm long, two rows of 10 grout outlet holes with the diameter of 6mm are formed in the pipe wall of the grouting pipe within 50cm, the grout outlet holes are arranged in a quincunx shape, a mold bag with the length of 60cm is sleeved outside the grouting pipe, the mold bag is fixed at two ends of the mold bag by rubber hooping, and the mold bag is made of non-woven geotextile.

2. Measuring and positioning

And (3) accurately measuring the longitudinal line and the elevation of the tunnel, marking the position of the small guide pipe according to the design, releasing the drilling hole position on the construction working surface, and marking.

3. Grouting pipe installation

The grouting pipe is provided with a plum blossom-shaped grout outlet, the root part of the grouting pipe is connected with a positioning steel plate through threads, and the positioning steel plate is fixed on the steel arch frame through a steel wire. Firstly, connecting the grouting pipe with a positioning steel plate, sleeving a mold bag on the grouting pipe, wiping the grouting pipe into a small guide pipe, and fixing the positioning steel plate on a steel arch frame by adopting a steel wire.

4. Preparation of slurry

The cement grout is prepared by a stirrer, and the porosity of the stratum of the loose accumulation body is high, so that the concentration of the cement grout is adjusted to be diluted and concentrated first, and a good grouting effect is obtained in a loose area, therefore, the water cement ratio is controlled to be 1.1:1 when each guide pipe starts grouting, and then is slowly adjusted to be 0.85: 1.

The mass of the accelerator and the mass of the HJ520 acrylate grouting solution respectively account for 4% of the mass of the cement, the mass of the accelerator and the HJ520 acrylate grouting solution is calculated according to the mass of the cement, and then the accelerator and the HJ520 acrylate grouting solution are diluted by adding water and are uniformly stirred and are respectively poured into a stirrer.

5. Grouting

The grouting apparatus includes: grouting pump, slip casting pipe, air compressor machine, flowmeter, storage thick liquid bucket and shutoff equipment etc.. Wherein the working pressure of the grouting pump is 2.5Mpa, and the grouting pipe is a 40mm rubber pipe. The main grouting steps are as follows:

before grouting, whether equipment can normally work is firstly checked, all pipelines are communicated outside a hole for pressure testing, and the pressure testing can be carried out by using clean water. During pressure testing, if the pipeline is not communicated or the joint has water leakage, the water leakage is eliminated, and all parts of the pipeline system are kept intact and smooth. In order to prevent the grout from overflowing from the tunnel face, a closed grouting face with the thickness of 5-10 cm is required to be sprayed with concrete before grouting, and a grout stopping disc is formed. In order to prevent the grout from overflowing from other holes, grout stop plugs are required to be arranged on all the holes before grouting.

Cleaning sediments in the pipe before grouting, sequentially grouting from arch feet at two sides to the vault, diluting the grout and then concentrating the grout, increasing the grouting amount and then decreasing the grouting pressure from small to large.

According to the field grouting test and the related grouting construction experience, the stopping grouting pressure of the stratum of the loose accumulation body is determined to be 1.5-2.0 Mpa, so the grouting is stopped when the grouting pressure reaches 1.5-2.0 Mpa and the grouting speed is 1/4 of the starting grouting speed or the grouting amount reaches 80% or more of the designed grouting amount.

In the above examples, the water cement ratio was controlled to 1.1:1 at the time of grouting, then slowly adjusted to 0.85:1, the grout gelling time was 6 hours, and the setting accelerator and the HJ520 acrylate grouting solution, each accounting for 4% by mass of the cement mass, were added to the cement grout, and the strength of the grout stones in 2 hours was 76% of the strength required for the design.

In a comparative embodiment, a grouting method for reinforcing a tunnel comprises the following steps:

1. design parameters

The small guide pipe is a hot-rolled seamless steel pipe with the outer diameter of 42mm, the wall thickness of 4mm and the length of 4.5 m. The adopted grouting pipe is 80cm long, two rows of 10 grout outlet holes with the diameter of 6mm are formed in the pipe wall of the grouting pipe within 50cm, the grout outlet holes are arranged in a quincunx shape, a mold bag with the length of 60cm is sleeved outside the grouting pipe, the mold bag is fixed at two ends of the mold bag by rubber hooping, and the mold bag is made of non-woven geotextile.

2. Measuring and positioning

And (3) accurately measuring the longitudinal line and the elevation of the tunnel, marking the position of the small guide pipe according to the design, releasing the drilling hole position on the construction working surface, and marking.

3. Grouting pipe installation

The grouting pipe is provided with a plum blossom-shaped grout outlet, the root part of the grouting pipe is connected with a positioning steel plate through threads, and the positioning steel plate is fixed on the steel arch frame through a steel wire. Firstly, connecting the grouting pipe with a positioning steel plate, sleeving a mold bag on the grouting pipe, wiping the grouting pipe into a small guide pipe, and fixing the positioning steel plate on a steel arch frame by adopting a steel wire.

4. Preparation of slurry

Preparing the slurry by adopting a stirrer, wherein the cement slurry is prepared according to the water-cement ratio of 1:1, and stirring the mixture.

5. Grouting

The grouting apparatus includes: grouting pump, slip casting pipe, air compressor machine, flowmeter, storage thick liquid bucket and shutoff equipment etc.. Wherein the working pressure of the grouting pump is 2.5Mpa, and the grouting pipe is a 40mm rubber pipe. The main grouting steps are as follows:

before grouting, whether equipment can normally work is firstly checked, all pipelines are communicated outside a hole for pressure testing, and the pressure testing can be carried out by using clean water. During pressure testing, if the pipeline is not communicated or the joint has water leakage, the water leakage is eliminated, and all parts of the pipeline system are kept intact and smooth. In order to prevent the grout from overflowing from the tunnel face, a closed grouting face with the thickness of 5-10 cm is required to be sprayed with concrete before grouting, and a grout stopping disc is formed. In order to prevent the grout from overflowing from other holes, grout stop plugs are required to be arranged on all the holes before grouting.

Cleaning sediments in the pipe before grouting, sequentially grouting from arch feet at two sides to the vault, diluting the grout and then concentrating the grout, increasing the grouting amount and then decreasing the grouting pressure from small to large.

According to the field grouting test and the related grouting construction experience, the stopping grouting pressure of the stratum of the loose accumulation body is determined to be 1.5-2.0 Mpa, so the grouting is stopped when the grouting pressure reaches 1.5-2.0 Mpa and the grouting speed is 1/4 of the starting grouting speed or the grouting amount reaches 80% or more of the designed grouting amount.

In the above examples, the cement slurry was poured in a water-cement ratio of 1:1, the quick-setting admixture slurry and the HJ520 acrylate grouting solution are not added, the gelling time of the slurry is 10 hours, and the strength of the slurry concretion body in 2 hours is 68% of the designed required strength.

What has been described above are merely some embodiments of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the inventive concept thereof, and these changes and modifications can be made without departing from the spirit and scope of the invention.