Tunnel local advanced pre-grouting water plugging method

Abstract

This invention provides a method for local pre-grouting and water plugging in tunnels, comprising: Step 1, drilling pre-exploration holes on the tunnel face using a water drill; inserting a pre-exploration pipe into the pre-exploration hole, the outlet of the pre-exploration pipe being equipped with a flow meter; recording the outflow rate of each pre-exploration hole and the total outflow rate based on the flow meter reading; Step 2, drilling grouting holes on the tunnel face along the direction of the outflow point using a water drill, inserting a grouting pipe into the grouting hole, the outlet of the grouting pipe being equipped with a rubber bag; the outer wall of the rubber bag having conical protrusions spaced apart, the rubber bag being able to withstand a predetermined pressure, the predetermined pressure being determined by a fitting curve of total outflow rate - predetermined pressure. The method for local pre-grouting and water plugging in tunnels provided by this invention is suitable for small fractured zones and water-rich soft soil layers, effectively saving overall costs, improving construction quality, and achieving the effect of local pre-grouting and water plugging, and reinforcing the strata.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering technology. More specifically, this invention relates to a method for local pre-grouting and water plugging in tunnels. Background Technology

[0002] In my country's existing road transportation system, there are numerous tunnel projects. During the construction of these tunnels, there are often sections that need to pass through water-rich areas. Indiscriminate drainage would damage the ecological environment. Therefore, grouting and water-blocking technology is widely used in tunnel engineering.

[0003] A search revealed a method for systematic full-section grouting and water plugging in low-pressure, water-rich tunnels, published in CN116357350A. However, this method, employing full-section grouting, presents challenges in addressing localized water seepage conditions such as small fractured zones and limited areas of water-rich, soft soil. Therefore, this invention proposes a method for localized pre-grouting and water plugging in tunnels to solve these problems, achieving both localized pre-grouting and water plugging, and strengthening the strata. Summary of the Invention

[0004] One objective of this invention is to provide a method for local pre-grouting and water plugging in tunnels. The method determines the use of local pre-grouting and water plugging by determining the outflow rate of the pre-exploration water hole. Rubber bags are added to the grouting and water plugging equipment to achieve local grouting and water plugging, thereby reinforcing the strata. This method can effectively improve construction quality, shorten the construction period, and save costs.

[0005] To achieve these objectives and other advantages of the present invention, the present invention provides a method for local pre-grouting and water plugging in tunnels, comprising: Step 1, drilling pre-exploration holes on the tunnel face using a water drill; inserting a pre-exploration pipe into the pre-exploration hole, wherein a flow meter is provided at the outlet of the pre-exploration pipe; recording the outflow rate of each pre-exploration hole and the total outflow rate according to the reading of the flow meter; Step 2, drilling grouting holes on the tunnel face along the direction of the water outlet using a water drill, inserting a grouting pipe into the grouting hole, wherein a rubber bag is provided at the grout outlet of the grouting pipe; the outer wall of the rubber bag is provided with conical protrusions at intervals, and the rubber bag can withstand a predetermined pressure, wherein the predetermined pressure is determined by a fitting curve of total outflow rate - predetermined pressure.

[0006] Furthermore, the total outflow rate is less than 15m³. 3 / h, the flow rate of some water exploration wells is greater than 3m³ / h. 3 / h, proceed to step two when both conditions are met simultaneously.

[0007] Furthermore, the bottom of the grouting hole is located in the middle of the water-rich area in the direction of the water outlet, and the water-rich area is determined according to the water flow rate of each of the water exploration holes.

[0008] Furthermore, the grouting pipe is inserted into the grouting hole, the outlet of the grouting pipe is equipped with a rubber bag, and the inlet of the grouting pipe is fixedly connected to the orifice pipe; the diameter of the orifice pipe is the same as the diameter of the grouting hole; one end of the orifice pipe is connected to the inlet of the grouting pipe, and the other end of the orifice pipe is fixedly connected to a flange, and the flange is connected to the grouting pump through the grouting pipe.

[0009] Furthermore, the opening of the rubber bag is fixedly fitted onto the slurry outlet, the body of the rubber bag is located at the bottom of the slurry hole, the body of the bag is ellipsoidal, the minor axis is 120-150mm, the major axis is 150-200mm, and the thickness of the rubber bag is determined by a predetermined pressure; the outer wall of the bag is provided with conical protrusions with a length of 20-30mm at intervals.

[0010] Furthermore, the predetermined pressure is determined by the total effluent flow rate - predetermined pressure fitting curve; the total effluent flow rate - predetermined pressure fitting curve is obtained from multiple sets of construction tests; the total effluent flow rate - predetermined pressure fitting curve is a polynomial function fitting curve.

[0011] Furthermore, the flow meter measures a total outflow rate of less than 2 m³ / h. 3 / h, and the flow rate of one of the aforementioned water exploration holes is less than 0.6m³ / h. 3 / h, the grouting and water plugging work ends when both conditions are met simultaneously. Further, the total outflow rate is less than 15m³ / h. 3 / h, the flow rate of some water exploration wells is greater than 3m³ / h. 3 / h, proceed to step two when both conditions are met simultaneously.

[0012] The present invention has at least the following beneficial effects:

[0013] This invention determines the need for localized pre-grouting for water plugging in tunnels by measuring the outflow rate of pre-exploration boreholes, and then uses grouting equipment to perform localized pre-grouting water plugging. For areas with small fracture zones and water-rich soft soil layers during tunnel construction, the rubber bags added to the grouting equipment can disrupt joints, fissures, or water channels in the fracture zones or water-rich soft soil layers, achieving localized grouting water plugging, reinforcing the strata, and improving construction quality. This solves the problem of using full-section grouting for water plugging due to localized water outflow in tunnels, which leads to cumbersome construction and wasted manpower and resources.

[0014] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the construction process of the present invention.

[0016] Figure 2 A schematic diagram of the rubber bag used in the tunnel pre-grouting and water-blocking method of the present invention;

[0017] In the picture: 1. Rubber bag; 2. Bag body; 3. Conical protrusion; 4. Bag opening. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0019] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0020] like Figure 1 As shown, the embodiments of this application provide a method for local pre-grouting and water plugging in tunnels, including: Step 1, drilling pre-exploration holes on the tunnel face using a water drill; optionally, a water drill, down-the-hole drill, or other drilling tools can be used; the water drill bit diameter is 55mm, the bit length is 500-600mm, the number of holes is 1-4, the spacing between holes is 1-2m, and the drilling angle and direction are determined according to geological exploration and the geological conditions of the tunnel face. Generally, the angle between the drilling direction and the horizontal direction is greater than 15°, and the holes are drilled obliquely upwards from the tunnel face towards the water outlet point. After the borehole is completed, the water detection pipe is inserted into the borehole. Optionally, the water detection pipe can be made of steel or PVC pipe with a thickness of less than 5mm, and the length of the water detection pipe is 200-300mm longer than the length of the borehole. A flow meter is installed at the outlet of the water detection pipe. Optionally, the flow meter can be an electromagnetic flow meter or a differential pressure flow meter. Water in the area near the bottom of the borehole flows out through the water detection pipe. The flow meter can display the water flow rate, record the outflow rate of each borehole and the total outflow rate, and comprehensively determine the water-rich area in front of the tunnel face based on the outflow rate, direction and position relationship of each advanced water detection borehole.

[0021] Step two: Use a water drill to drill grouting holes diagonally upwards towards the water-rich area at the tunnel face. The drilling angle and direction are determined based on the water-rich area identified through advance water exploration and the geological conditions of the tunnel face. Generally, the angle between the drilling direction and the horizontal direction is greater than 15°. Optionally, the water drill bit diameter is 150mm, the length is 3-5m, and 1-2 grouting holes are drilled, with a spacing of 2-4m between the holes. The bottom of the grouting hole should be located near the water-rich area within the geological mass ahead of the tunnel face. Insert the grouting pipe into the... The grouting pipe is a steel pipe with a diameter of 108mm, a length matching the borehole length, and a thickness of 4.5mm. A rubber bag 1 is fitted over the grout outlet of the grouting pipe, with the bag opening 4 of the rubber bag 1 fitted over the outlet and secured with tape. Optionally, the length of the bag opening 4 is 150-200mm, which can be selected according to the predetermined pressure that the rubber bag 1 needs to withstand during construction. When the predetermined pressure is high, the length of the bag opening 4 can be increased to better connect the rubber bag 1 to the grouting pipe. Outside the rubber bag 1... The wall is provided with conical protrusions 3 with a length of 20-30 mm to disrupt water channels near the water-rich area; the shape of the bag body 2 of the rubber bag 1 can be ellipsoidal, and the thickness of the rubber bag 1 is determined by a predetermined pressure; optionally, the thickness of the rubber bag 1 is 1.5-3 mm, the minor axis of the bag body 2 of the rubber bag 1 is 120-150 mm, and the major axis is 150-200 mm; the grout outlet of the grouting pipe is inserted into the grouting hole, so that the grout outlet and the bag body 2 of the rubber bag 1 are located at the bottom of the grouting hole, and the grout inlet of the grouting pipe is connected to the hole opening pipe. The connection is fixed. The diameter of the orifice pipe is 150mm, the length is 200-300mm, and the thickness is 4.5mm. The diameter of the orifice pipe is the same as the diameter of the grouting hole. When the orifice pipe is inserted into the grouting hole, the outer wall of the orifice pipe is tightly connected to the inner wall of the grouting hole to prevent the grout from flowing back and overflowing out of the grouting hole during the grouting and water plugging construction. One end of the orifice pipe is fixedly connected to the grout inlet of the grouting pipe, and the other end of the orifice pipe is fixedly connected to the flange. The diameter of the flange is slightly larger than the diameter of the orifice pipe. The flange is connected to the grouting pump through the grouting pipe.During grouting, the pressure of the grouting pump is 0.5–3 MPa. As the pump increases the pressure, the grout enters the grouting pipe through the grouting pipeline. Air and some grout in the grouting pipe enter the rubber bag 1. The rubber bag 1 expands under pressure. At this time, the conical protrusions 3 on the outer wall of the bag 2 disrupt the water channels near the water-rich area. As the pressure increases, the rubber bag 1 gradually expands until it ruptures. The rupture of the rubber bag 1 releases the air and grout inside the bag 2, generating a huge impact force near the water-rich area, further disrupting the water channels there. Grouting then continues. During the process, the grout diffuses near the bottom of the injection hole after being pressurized, with an effective diffusion diameter of 3-5m. Optionally, the grout can be made from granular grout material, which can be either single-liquid or double-liquid. Single-liquid grout is pure cement grout using 425 ordinary Portland cement with a water-cement ratio of W / C = 0.6-1.1. When the outflow rate is large, cement-water glass double-liquid grout can be used, with a cement grout to water glass volume ratio of 1:0.5. The gelation time is determined according to the construction site conditions. After grouting, when the flow meter measures a total outflow rate of less than 2m from the grouting hole, the grout is ready for application. 3 / h, the flow rate from one water tracing well is less than 0.6m³ / h. 3 The grouting process can be completed when both conditions are met simultaneously, thus finishing the grouting and water plugging construction. During the grouting process, the rubber bag 1 added to the grouting pipe inlet expands until it ruptures, which can destroy the water channels near the water-rich area, improve the construction quality, achieve the effect of localized fixed-point grouting and water plugging, and reinforce the stratum.

[0022] In other embodiments, four advance water exploration holes can be drilled obliquely upwards at the tunnel face using a water drill bit with a diameter of 55mm and a length of 500mm. The holes are spaced 1m apart, and the specific drilling locations and angles are determined based on geological surveys and the geological conditions of the tunnel face. After water emerges from the exploration holes, an advance water exploration pipe is inserted into the holes. The pipe is made of steel, with a diameter of 55mm, a length of 700mm, and a thickness of 4.5mm. The outer wall of the pipe can be tightly fitted to the inner wall of the exploration hole. An electromagnetic flowmeter is installed at the outlet of the pipe. Water near the bottom of the exploration hole enters the pipe and flows out. The electromagnetic flowmeter displays the flow rate and records the outflow rates of the four exploration holes and the total outflow rate. Based on the outflow rate, direction, and positional relationship of each advance water exploration hole, the water-rich area in front of the tunnel face is determined. The total outflow rate is less than 15m³. 3 / h, the flow rate of some water exploration wells is greater than 3m³ / h. 3 When both conditions are met, the tunnel can be constructed using the method of local pre-grouting and water plugging.

[0023] In other embodiments, a water drill is used to drill two grouting holes obliquely upward on the tunnel face. The diameter of the water drill bit is 150mm and the length is 4m. The specific drilling points and drilling direction angles are determined based on the water-rich area determined by the advance water exploration and the geological conditions of the tunnel face. The grouting hole point is 1m away from the advance water exploration hole, and the two grouting holes are 2m apart. During drilling, the bottom of the grouting hole is located in the middle of the water-rich area.

[0024] In other embodiments, a grouting pipe is inserted into the grouting hole. The grouting pipe is a steel pipe with a diameter of 108 mm, a length of 3.8 m, and a thickness of 4.5 mm. A rubber bag 1 is provided at the outlet of the grouting pipe. The opening 4 of the rubber bag 1 is 150 mm long and 2 mm thick. The short axis of the bag body 2 of the rubber bag 1 is 120 mm, and the long axis is 150 mm. Conical protrusions 3 with a length of 30 mm are arranged at intervals on the outer wall of the bag body 2. The opening 4 of the rubber bag 1 is fitted over the outlet of the grouting pipe, and the opening 4 of the rubber bag 1 is secured with tape. It is fixed together with the grouting pipe; the grout inlet of the grouting pipe is fixedly welded to the orifice pipe, which is a steel pipe with a diameter of 150mm, a length of 200mm, and a thickness of 4.5mm. The orifice pipe and the grouting hole have the same diameter. When the orifice pipe is inserted into the grouting hole, the outer wall of the orifice pipe is tightly sealed to the inner wall of the grouting hole to prevent the grout from flowing back and overflowing during the grouting process; one end of the orifice pipe is welded and fixed to the grout inlet of the grouting pipe, and the other end is welded and fixed to a flange with a diameter of 195mm and a thickness of 20mm. mm; the flange is connected to the grouting pump via a grouting pipe; during construction, the grouting pump pressurizes the slurry, and the grouting material for water plugging is single-component slurry. The cement for the single-component slurry is 425 ordinary Portland cement, and the water-cement ratio is W / C = 0.6~1.1, which is determined according to the on-site construction conditions. The grouting pressure of the grouting pump is 0.5~3Mpa, and the initial pressure is 0.5Mpa. After being pressurized, the slurry enters the grouting pipe through the grouting pipe. The air and part of the slurry in the grouting pipe are squeezed into the rubber bag 1, and the rubber bag 1 is compressed. Then it begins to expand. At this time, the conical protrusions 3 on the outer wall of the bag 2 can destroy the water channels near the water-rich area. As the pressure increases, the rubber bag 1 gradually expands until it ruptures. The rupture of the rubber bag 1 can release the air and slurry inside the bag 2, generating a huge impact force near the water-rich area, further destroying the water channels near the water-rich area. After the rubber bag 1 ruptures, the grouting pump continues to pressurize and deliver the slurry to the grouting pipe. The slurry diffuses from the slurry outlet to the vicinity of the water-rich area. The effective diffusion radius of the slurry is 3.6m, so as to achieve the effect of local grouting and water blocking.

[0025] In other embodiments, the inventors summarized the relationship between the predetermined pressure and the total outflow of the exploratory borehole based on long-term construction experience, and obtained a fitting curve of total outflow - predetermined pressure through multiple sets of pre-construction tests. Specifically, when the thickness of the rubber bag 1 is between 1.5 and 3 mm, multiple sets of rubber bags 1 with different thicknesses are selected. The bag opening 4 of the rubber bag 1 is fixed to the grout outlet of the grouting pipe with tape. The grouting pump is used to apply air pressure, and the pressure displayed by the grouting pump when the rubber bag 1 ruptures is recorded. When the total outflow is between 3 and 15 m³ / h, the pressure is adjusted accordingly. 3 The water flow rate values ​​corresponding to the number of experimental groups are selected at intervals of / h. The polynomial function fitting curve plotted based on the pressure when rubber bag 1 ruptures and the selected water flow rate values ​​is the total water flow rate - predetermined pressure fitting curve. During construction, the predetermined pressure of rubber bag 1 is determined based on the total water flow rate of the advanced water exploration hole measured by the flow meter. Based on the predetermined pressure, rubber bag 1 with appropriate thickness is selected for local grouting and water plugging construction.

[0026] In other embodiments, as the grouting and water-blocking construction progresses, the outflow rate of the exploratory boreholes continuously decreases. When the outflow rate decreases to a certain level, it indicates that the construction has achieved the expected grouting and water-blocking effect. In actual projects, the outflow rate of the exploratory boreholes is used as the standard to control the construction progress. When the flow meter measures a total outflow rate of less than 2 m³ / s, the construction is considered complete. 3 / h, and the flow rate from one of the water exploratory wells is less than 0.6m³ / h. 3 / h, the grouting can be stopped when both conditions are met at the same time, thus completing the grouting and water plugging construction.

[0027] The number of devices and processing scale described herein are for simplification of the invention. Applications, modifications, and variations of the present invention's method for localized pre-grouting and water plugging in tunnels will be readily apparent to those skilled in the art.

[0028] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for localized pre-grouting and water plugging in tunnels, characterized in that, include: Step 1: Drill advance water exploration holes on the tunnel face using a water drill; insert advance water exploration pipes into the advance water exploration holes, and install flow meters at the outlet of the advance water exploration pipes; record the outflow rate of each advance water exploration hole and the total outflow rate according to the reading of the flow meters. Step 2: Drill grouting holes along the direction of the water outlet on the tunnel face using a water drill, insert the grouting pipe into the grouting hole, and provide a rubber bag at the grout outlet of the grouting pipe; the outer wall of the rubber bag is arranged with conical protrusions at intervals, and the rubber bag can withstand a predetermined pressure, which is determined by the fitting curve of total water flow rate - predetermined pressure. When the total outflow rate is less than 15 m³ / h and the outflow rate of individual water exploration holes is greater than 3 m³ / h, step two is performed simultaneously. The opening of the rubber bag is fixedly fitted onto the slurry outlet, and the body of the rubber bag is located at the bottom of the slurry hole. The body of the bag is ellipsoidal, with a minor axis of 120~150mm and a major axis of 150~200mm. The thickness of the rubber bag is determined by a predetermined pressure. The outer wall of the bag is provided with conical protrusions with a length of 20~30mm at intervals. The total outflow rate - predetermined pressure fitting curve was obtained from multiple sets of construction tests; The total outflow rate - predetermined pressure fitting curve is a polynomial function fitting curve; During grouting, air and some grout enter the rubber bag. The rubber bag begins to expand under pressure. At this time, the conical protrusion on the outer wall of the bag destroys the nearby water channels. As the pressure increases, the rubber bag gradually expands until it ruptures. The rupture of the rubber bag releases the air and grout inside the bag, generating a huge impact force, which further destroys the water channels in the vicinity. Then, the grouting work continues. After being pressurized, the grout diffuses near the bottom of the grouting hole.

2. The method for local pre-grouting and water plugging in tunnels as described in claim 1, characterized in that, The bottom of the grouting hole is located in the middle of the water-rich area in the direction of the water outlet, and the water-rich area is determined according to the water flow rate of each of the water exploration holes.

3. The method for local pre-grouting and water plugging in tunnels as described in claim 2, characterized in that, The grouting pipe is inserted into the grouting hole, and a rubber bag is provided at the outlet of the grouting pipe. The inlet of the grouting pipe is fixedly connected to the orifice pipe. The diameter of the orifice pipe is the same as the diameter of the grouting hole. One end of the orifice pipe is connected to the inlet of the grouting pipe, and the other end of the orifice pipe is fixedly connected to a flange. The flange is connected to the grouting pump through the grouting pipe.

4. The method for local pre-grouting and water plugging in tunnels as described in claim 1, characterized in that, The grouting and water plugging work ends when the total outflow measured by the flow meter is less than 2 m³ / h and the outflow of one of the water probe holes is less than 0.6 m³ / h.

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