Advanced pre-grouting method for tunnel

Abstract

The invention belongs to the field of railway tunnels, and particularly relates to a tunnel advanced pre-grouting method which comprises the following steps: forming grouting holes in a tunnel; positioning a grouting consolidation outer edge line; treating a grouting hole; drilling a grouting hole and grouting; selecting a grouting material and pressure; the grouting effect is checked; grouting holes are blocked; and the drilling arrangement and the hole number are adjusted and optimized. The method has the advantages of simple process, high pertinence, good water stopping effect and the like for fault fracture zones and sections with higher predicted water pressure and serious water inrush and mud inrush which are likely to occur.

Description

Technical Field

[0001] The invention belongs to the field of railway tunnels, in particular to a tunnel advance pre-grouting method. Background Art

[0002] When high-speed railways are laid in mountainous areas, they need to pass through the strata due to the influence of the terrain and existing ground buildings, and a large number of tunnels need to be set up. The waterproofing and drainage design of the tunnel adopts the principle of "combining prevention, drainage, blocking and interception, adapting to local conditions and comprehensive management"; for tunnels passing through karst and fault fracture zones, it is expected that the groundwater is large. When drainage is adopted as the main method, it may affect the ecological environment, and the drainage capacity of the drainage ditch is limited and discharge is required, the principle of "blocking as the main method and limited discharge" is adopted according to the actual situation. For fault fracture zones and areas with high predicted water pressure and the high possibility of severe water and mud inrush, it is necessary to intercept and block the groundwater, and cut off the water flow path between the groundwater and the tunnel within a certain range outside the tunnel excavation line to achieve the purpose of limiting the discharge of groundwater. Summary of the invention

[0003] In view of the problems in the prior art, the present invention provides a tunnel advance pre-grouting method.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] A tunnel advance pre-grouting method specifically comprises the following steps:

[0006] S1: Open grouting holes in the tunnel;

[0007] S2: grouting consolidation outer edge line positioning;

[0008] S3: treatment of grouting holes;

[0009] S4: grouting hole drilling and grouting;

[0010] S5: Selection of grouting materials and pressure;

[0011] S6: Check the grouting effect;

[0012] S7: grouting hole plugging;

[0013] S8: Adjust and optimize the drilling arrangement and number of holes.

[0014] Preferably, S1 specifically comprises the following steps:

[0015] S11: multiple grouting holes are arranged on the inner wall of the tunnel, and the multiple grouting holes are distributed in the form of multiple concentric rings from the inside to the outside, and the concentric rings are arranged at equal intervals;

[0016] S12: Multiple grouting holes in each concentric ring are arranged at equal distances, and the angle of the grouting hole is the angle between the projection of the grouting hole in the horizontal and vertical directions and the excavation contour line.

[0017] Preferably, S2 specifically includes: the outer edge line of grouting consolidation is 5m outside the excavation contour line.

[0018] Preferably, S3 specifically includes the following steps:

[0019] S31: The grouting length of each concentric ring is 30m, excavation is 22m, and 8m of grouting rock plate is retained;

[0020] S32: grouting hole diffusion radius 2m, face spacing 0.75m, hole bottom spacing 3m;

[0021] S33: The opening diameter of the grouting hole shall not be less than 108mm, and the final hole diameter shall not be less than 90mm: The orifice pipe of the grouting hole shall be a hot-rolled seamless steel pipe with a diameter of 108mm and a wall thickness of 5mm, and the pipe length is 1m.

[0022] Preferably, S4 specifically comprises the following steps:

[0023] S41: The drilling and grouting sequence of the grouting holes is from the outside to the inside of the concentric ring, and the holes in the same circle are constructed alternately;

[0024] S42: The grouting method adopts backward grouting. When the rock layer is broken and collapses, forward grouting is adopted;

[0025] S43: When water gushing out or the drill is stuck due to rock fragmentation during drilling, drilling should be stopped and grouting and hole sweeping should be carried out before drilling can continue.

[0026] Preferably, S5 specifically includes the following steps:

[0027] S51: The grouting material for drilling holes is pure cement slurry;

[0028] S52: Grouting pressure is the hydrostatic pressure at the grouting point plus 0.5-1.5MPa.

[0029] During the grouting construction, due to the deviation of the drilling hole, the grouting liquid was slurried, and the grouting amount in each grouting pipe was very uneven; according to the rock and soil body within the range of 0.5m to 1m above and below the entire row of small pipes, the total grouting amount was estimated by the following formula;

[0030] The formula is: Q = (π × H / 360) × [(R + t) 2 -(Rt) 2 ]×G×L.

[0031] Where: Q--grouting volume, m3;

[0032] H--The angle of the grouting pipe layout range relative to the center of the circle;

[0033] R--The radius of the grouting pipe relative to the center of the circle;

[0034] t--slurry diffusion radius, 0.5m~1m;

[0035] L--effective length of grouting pipe, m;

[0036] G--Rock porosity, %; 3% to 5% for Grade I and V surrounding rocks, 2% to 3% for Grade III surrounding rocks, and 1% to 2% for soft rocks.

[0037] Preferably, after the grouting is completed, S6 specifically includes the following steps:

[0038] S61: After the grouting is completed, an inspection hole is drilled within the excavation contour to test the grouting effect;

[0039] S62: Each concentric ring is equipped with 5 inspection holes, including 2 in the arch, 1 on each of the left and right side walls, and 1 at the bottom. The diameter of the inspection hole is 110mm, the length is 30m, and the average water output is <0.2L / min;

[0040] S63: All grouting holes meet the single hole end condition, and the predicted water inflow of the tunnel after grouting is less than 1m 3 / (dxm); under a pressure of 1.0MPa, water absorption is <2L / min; the compressive strength of the reinforced body is not less than 3MPa; the RQD (rock quality index) of the rock mass reaches 75-80.

[0041] Preferably, S7 specifically includes: after the grouting effect inspection is completed, the grouting inspection hole should be fully sealed with M10 cement mortar in a timely manner.

[0042] Preferably, S8 specifically includes the following steps:

[0043] S81: Before grouting construction, comprehensive advanced geological prediction and forecasting methods should be adopted to explore the geological conditions in front of the tunnel face;

[0044] S82: Carry out advance grouting according to the water output of the advance water exploration holes, and optimize and adjust according to the water pressure test on the basis of the design, and adjust and optimize the drilling arrangement and number of holes accordingly.

[0045] Beneficial effects:

[0046] It has the advantages of simple process, strong targeting and good water-stopping effect for fault fracture zones and areas with predicted high water pressure and high possibility of severe water and mud suddens. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0048] Figure 1 It is a schematic diagram of the process of the present invention;

[0049] Figure 2 It is a front view of a tunnel advance pre-grouting method of the present invention;

[0050] Figure 3 It is a cross-sectional view of a tunnel advance pre-grouting method of the present invention;

[0051] Figure 4 It is a plan view of a tunnel advance pre-grouting method of the present invention.

[0052] In the figure: 1. Grouting hole; 10. Center hole; 11. First ring; 12. Second ring; 13. Third ring; 14. Fourth ring; 15. Fifth ring; 16. Sixth ring; 2. Excavation contour line; 3. Grouting consolidation outer edge line; 4. Head face; 5. Hole bottom. DETAILED DESCRIPTION

[0053] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0054] In one embodiment, Figure 1-4 As shown, a tunnel advance pre-grouting method specifically includes the following steps:

[0055] S1: Open grouting holes in the tunnel;

[0056] S2: grouting consolidation outer edge line positioning;

[0057] S3: treatment of grouting holes;

[0058] S4: grouting hole drilling and grouting;

[0059] S5: Selection of grouting materials and pressure;

[0060] S6: Check the grouting effect;

[0061] S7: grouting hole plugging;

[0062] S8: Adjust and optimize the drilling arrangement and number of holes.

[0063] In one embodiment, a plurality of grouting holes are provided on the inner wall of the tunnel, and the plurality of grouting holes are distributed in the form of a plurality of concentric rings from the inside to the outside, and the concentric rings are arranged at equal intervals.

[0064] The concentric rings include 7 circular rings and 120 grouting holes 1. The concentric rings are respectively the center hole 10, the first ring 11, the second ring 12, the third ring 13, the fourth ring 14, the fifth ring 15 and the sixth ring 16 from the inside to the outside. The rings are arranged at equal intervals. The parameters such as the number of holes in each ring, angle and oblique length are shown in Table 1.

[0065] Table 1 Grouting hole parameters

[0066]

[0067]

[0068] Multiple grouting holes in each concentric ring are arranged at equal distances, and the angle of the grouting hole is the angle between the projection of the grouting hole in the horizontal and vertical directions and the excavation contour line.

[0069] Specifically, the outer edge of the grouting consolidation is 2m outside the excavation contour line, as shown in the attached manual. Figure 1 shown.

[0070] Specifically, the grouting length of each concentric ring is 30m, excavation is 22m, and 8m of grouting rock plate is retained. The first cycle uses a 1.5m thick C20 concrete grouting wall.

[0071] Specifically, the grouting holes have a diffusion radius of 2 m, the spacing of the 4 holes at the face is 0.75 m, and the spacing of the 5 holes at the bottom is 3 m.

[0072] Specifically, the opening diameter of the grouting hole 1 shall not be less than 108mm, and the final hole diameter shall not be less than 90mm: the orifice pipe shall adopt a hot-rolled seamless steel pipe with a diameter of 108mm and a wall thickness of 5mm, and a pipe length of 1m. The orifice pipe shall be firmly buried and have good slurry stopping measures.

[0073] Specifically, the drilling and grouting sequence of the grouting holes is from the outside to the inside of the concentric ring, and the holes in the same circle are constructed at intervals. The grouting form adopts backward grouting. The rock formation is easily collapsed, and forward grouting is used when the hole collapses.

[0074] Specifically, if water gushing occurs during drilling or the drill is stuck due to rock strata breaking, drilling should be stopped, and grouting and hole sweeping should be carried out before drilling can continue.

[0075] Specifically, the grouting material for drilling: Generally, pure cement slurry (water-cement ratio 1:1) is used. Grouting pressure: The design grouting pressure (final pressure value) is generally based on the hydrostatic pressure at the grouting point plus 0.5-1.5MPa.

[0076] Specifically, in actual construction, due to drilling deviation or geological reasons in the borehole, grouting liquid often flows or runs out, and the grouting amount in each grouting pipe is very uneven. Therefore, the theoretical single-hole grouting amount cannot be used as a control indicator for single-hole grouting. The theoretically estimated total amount of the entire row of grouting pipes should be used as a control indicator. Therefore, considering that the rock and soil body within the range of 0.5m to 1m above and below the entire row of small pipes has been grouted, the total grouting amount should be estimated using the following formula.

[0077] Q = (π × H / 360) × [(R + t) 2 -(Rt) 2 ]×G×L;

[0078] Where: Q--grouting volume, m3;

[0079] H--The angle of the grouting pipe layout range relative to the center of the circle;

[0080] R--The radius of the grouting pipe relative to the center of the circle;

[0081] t--slurry diffusion radius, 0.5m~1m;

[0082] L--effective length of grouting pipe, m;

[0083] G--Rock porosity, %; 3% to 5% for Grade I and V surrounding rocks, 2% to 3% for Grade III surrounding rocks, and 1% to 2% for soft rocks.

[0084] Specifically, after the grouting is completed, the grouting effect needs to be checked; after the grouting is completed, inspection holes are set within the excavation contour to detect the grouting effect. Each concentric ring has 5 inspection holes, including 2 in the arch, 1 on each of the left and right side walls, and 1 at the bottom. The diameter of the inspection hole is 110mm, the length is about 30m, and the average water output is <0.2L / min; the end standard of the whole section grouting: all grouting holes meet the single hole end conditions, and the predicted water inflow of the tunnel after grouting is <1m 3 / (dxm); water pressure inspection, under 1.0MPa pressure, water absorption <2L / min; reinforced body compressive strength is not less than 3MPa; rock mass RQD (rock quality index) reaches 75-80. If the above conditions are met, it is considered that grouting has achieved the effect, and excavation can be carried out only after the grouting has achieved the effect.

[0085] Specifically, after the grouting effect inspection is completed, the grouting inspection hole should be fully sealed with M10 cement mortar in a timely manner.

[0086] Specifically, before grouting construction, comprehensive advanced geological prediction and forecasting methods should be adopted to explore the geological conditions in front of the heading face, and advance grouting should be carried out according to the water output of the advance water exploration holes. On the basis of design, the grouting parameters (such as grouting concentration, diffusion radius, etc.) should be appropriately optimized and adjusted according to the water pressure test, and the drilling arrangement and number of holes should be adjusted and optimized accordingly.

[0087] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A tunnel advance pre-grouting method, characterized in that: The specific steps include: S1: Open grouting holes in the tunnel; S2: grouting consolidation outer edge line positioning; S3: treatment of grouting holes; S4: grouting hole drilling and grouting; S5: Selection of grouting materials and pressure; S6: Check the grouting effect; S7: grouting hole plugging; S8: Adjust and optimize the drilling arrangement and number of holes.

2. A tunnel advance pre-grouting method according to claim 1, characterized in that: S1 specifically includes the following steps: S11: multiple grouting holes are arranged on the inner wall of the tunnel, and the multiple grouting holes are distributed in the form of multiple concentric rings from the inside to the outside, and the concentric rings are arranged at equal intervals; S12: Multiple grouting holes in each concentric ring are arranged at equal distances, and the angle of the grouting hole is the angle between the projection of the grouting hole in the horizontal and vertical directions and the excavation contour line.

3. A tunnel advance pre-grouting method according to claim 2, characterized in that: S2 specifically includes: the outer edge line of grouting consolidation is 5m outside the excavation contour line.

4. A tunnel advance pre-grouting method according to claim 3, characterized in that: S3 specifically includes the following steps: S31: The grouting length of each concentric ring is 30m, excavation is 22m, and 8m of grouting rock plate is retained; S32: grouting hole diffusion radius 2m, face spacing 0.75m, hole bottom spacing 3m; S33: The opening diameter of the grouting hole shall not be less than 108mm, and the final hole diameter shall not be less than 90mm: The orifice pipe of the grouting hole shall be a hot-rolled seamless steel pipe with a diameter of 108mm and a wall thickness of 5mm, and the pipe length is 1m.

5. A tunnel advance pre-grouting method according to claim 4, characterized in that: S4 specifically includes the following steps: S41: The drilling and grouting sequence of the grouting holes is from the outside to the inside of the concentric ring, and the holes in the same circle are constructed alternately; S42: The grouting method adopts backward grouting. When the rock layer is broken and collapses, forward grouting is adopted; S43: When water gushing out or the drill is stuck due to rock fragmentation during drilling, drilling should be stopped and grouting and hole sweeping should be carried out before drilling can continue.

6. A tunnel advance pre-grouting method according to claim 5, characterized in that: S5 includes the following steps: S51: The grouting material for drilling holes is pure cement slurry; S52: Grouting pressure is the hydrostatic pressure at the grouting point plus 0.5-1.5MPa.

7. A tunnel advance pre-grouting method according to claim 6, characterized in that: During the grouting construction, due to drilling deviation, grouting liquid slurrying, the grouting amount in each grouting pipe is uneven; according to the rock and soil body within the range of 0.5m to 1m above and below the entire row of small pipes, the total grouting amount is estimated by the following formula; The formula is: Q = (π × H / 360) × [(R + t) 2 -(Rt) 2 ]×G×L; Where: Q--grouting volume; H--The angle of the grouting pipe layout range relative to the center of the circle; R--The radius of the grouting pipe relative to the center of the circle; t--slurry diffusion radius; L--Effective length of grouting pipe; G--rock porosity.

8. A tunnel advance pre-grouting method according to claim 7, characterized in that: After the grouting is completed, S6 specifically includes the following steps: S61: After the grouting is completed, an inspection hole is drilled within the excavation contour to test the grouting effect; S62: Each concentric ring is equipped with 5 inspection holes, including 2 in the arch, 1 on each of the left and right side walls, and 1 at the bottom. The diameter of the inspection hole is 110mm, the length is 30m, and the average water output is <0.2L / min; S63: All grouting holes meet the single hole end condition, and the predicted water inflow of the tunnel after grouting is less than 1m 3 / (dxm); Under a pressure of 1.0MPa, water absorption is <2L / min: the compressive strength of the reinforced body is not less than 3MPa; The RQD of the rock mass reaches 75-80.

9. A tunnel advance pre-grouting method according to claim 8, characterized in that: S7 specifically includes: After the grouting effect inspection is completed, the grouting inspection hole should be fully sealed with M10 cement mortar in a timely manner.

10. A tunnel advance pre-grouting method according to claim 9, characterized in that: S8 specifically includes the following steps: S81: Before grouting construction, comprehensive advanced geological prediction and forecasting methods should be adopted to explore the geological conditions in front of the tunnel face; S82: Carry out advance grouting according to the water output of the advance water exploration holes, and optimize and adjust according to the water pressure test on the basis of the design, and adjust and optimize the drilling arrangement and number of holes accordingly.

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