A feather-shaped directional soft rock tunnel advance grouting pre-reinforcement structure and method

Abstract

A feather-shaped directional soft rock tunnel advance grouting pre-reinforcement structure and method, belonging to the field of underground engineering and geotechnical engineering construction. The reinforcement structure comprises a feather-shaped directional grouting borehole (1), a flexible drilling tool (2), a directional drill bit (3), and a drill bit guide controller (4); wherein the feather-shaped directional grouting borehole (1) comprises a central borehole and a plurality of branch boreholes dispersed in all directions, the central borehole is a long borehole pre-drilled by a drilling rig in the same direction as the axial length of the tunnel, a steel casing for protecting the well wall is inserted into the long borehole, and the branch boreholes are multiple curved boreholes extending from the central borehole to the surroundings and pointing to the inner wall of the tunnel (6), the number of branch boreholes in the circumference of the central borehole is 2-6, and the branch boreholes are evenly distributed along the axial length direction of the central borehole, and the overall structure of the central borehole and the branch boreholes is a feather-shaped structure; grouting is injected into the branch boreholes to form the reinforcement structure.

Description

Technical Field

[0001] The invention relates to a feather-shaped directional soft rock tunnel advance grouting pre-reinforcement method, belonging to the field of underground engineering and geotechnical engineering construction methods. Background Art

[0002] For soft rock tunnels, due to the low strength of the surrounding rock and poor self-stabilization ability, they are prone to construction risks and quality problems such as collapse and large deformation. Before tunnel excavation, grouting reinforcement is often used to pre-reinforce the surrounding rock in front of the face with full-section grouting. Grouting holes are arranged in a plum blossom shape on the face, and cement slurry is injected through drilling to reinforce the surrounding rock in front. However, due to the limited space on the tunnel face, it is difficult to put the construction equipment in place, which brings great difficulties to the construction. At the same time, a large number of grouting holes need to be constructed, resulting in waste of engineering and materials, and poor economic benefits.

[0003] The present invention discloses a feather-shaped directional soft rock tunnel advance grouting pre-reinforcement method, which constructs a small number of drilling holes, performs feather-shaped directional hole making and directional grouting, and performs full-section grouting pre-reinforcement on the surrounding rock in front of the tunnel face, effectively controlling construction risks and improving engineering quality. Summary of the invention

[0004] The feather-shaped directional soft rock tunnel advance grouting pre-reinforcement method of the present invention is a full-section grouting reinforcement structure for a soft rock tunnel, comprising a feather-shaped directional grouting borehole (1), a flexible drilling tool (2), a directional drill bit (3), and a drill bit guide controller (4); wherein the feather-shaped directional grouting borehole (1) comprises a central borehole and a plurality of branch boreholes dispersed in all directions, the central borehole being a long borehole pre-drilled by a drilling rig in the same direction as the axial length of the tunnel, a steel casing for protecting the well wall being lowered into the long borehole, the branch borehole being a plurality of curved boreholes extending from the central borehole in all directions and pointing to the inner wall of the tunnel (6), the number of branch boreholes in the circumferential direction of the central borehole being 2-6, and the branch boreholes being evenly distributed along the axial length direction of the central borehole, and the overall structure of the central borehole and the branch boreholes being a feather-shaped structure;

[0005] The flexible drilling tool (2) comprises a connecting thread (2.1), a connector (2.2), an ear piece (2.3), a pin / hole (2.4) and an outer wall rubber high-pressure protection structure (2.5); one end of the connector (2.2) is the connecting thread (2.1), and the other end is the ear piece (2.3), and the ear piece (2.3) is provided with a pin / hole (2.4); a plurality of connectors (2.2) are connected in the first place, and the connection part is: the connecting thread (2.1) and the ear piece (2.3) are connected and fixed by the pin / hole (2.4) to form a flexible long connector, and the outer periphery of the flexible long connector is the outer wall rubber high-pressure protection structure (2.5); one end of the flexible long connector extends into the borehole for drilling and grouting, and the other end is located outside the borehole for connection with a grouting pump; the end extending into the borehole is a directional drill bit (3);

[0006] The connector (2.2) is placed in the flexible drilling tool, is the main part of the drilling tool, and plays a role in transmitting pressure and torque;

[0007] The pin / hole (2.4) is placed in the flexible drilling tool, is the main part of the drilling tool, and is connected and fixed to the connecting body (2.2);

[0008] The outer wall rubber high pressure protection structure (2.5) is used to limit the position of the drilling tool connector and inject circulating mud and cement slurry, and the pressure resistance level is greater than the grouting pressure;

[0009] The directional drill bit (3) comprises a drill bit body and a drill bit guide controller (4) ， The drill bit guide controller (4) is fixed to the drill bit body, and the guide device (4) is controlled by the ground control system to measure the drill bit position and control the drilling direction of the drill bit;

[0010] The borehole diameter is larger than the outer diameter of the borehole casing;

[0011] The outer diameter of the casing is greater than the outer diameter of the directional drill bit (3);

[0012] The present invention is suitable for pre-reinforcing surrounding rock (8) in front of a tunnel face (7) in a soft rock (8) tunnel (6).

[0013] The feather-shaped directional soft rock tunnel advance grouting pre-reinforcement method of the present invention is a full-section grouting reinforcement method for a soft rock tunnel, comprising the following steps:

[0014] Step 1: Locate the grouting holes on site and install the horizontal drilling equipment;

[0015] Step 2: Use a horizontal directional drill to drill a horizontal hole to the depth of the grouting area (A), i.e., the starting end area A of the center hole, and drive in the casing;

[0016] Step 3: insert the flexible drilling tool (2) and the directional drill bit (3) into the borehole, and make the first branch borehole inclined by controlling the drilling direction with the drill bit guide controller (4) along the designed grouting hole trajectory direction and position of the branch borehole; connect the grouting pump to the other end of the flexible drilling tool, pump cement slurry through the flexible drilling tool, and perform high-pressure rotary grouting on the first section (A-1) of the drill bit end at the end of the first branch borehole, and stop after the grouting time is reached at the designed grouting pressure; retract the drilling tool, and perform high-pressure rotary grouting when the drill bit reaches the second grouting section (A-2), and stop after the grouting time is reached at the designed grouting pressure; and so on, complete the grouting of all inclined holes in the first branch borehole; then prepare the second branch borehole and perform all inclined hole grouting, and so on, complete the preparation and all inclined hole grouting of all branch boreholes in the starting end area A of the central borehole;

[0017] Step 4: Continue to drill horizontal holes to the depth of the grouting area (B), i.e., the front area of ​​area A at the starting end of the central borehole, and continue to drive in casing; and prepare all branch boreholes in the grouting area (B) and perform grouting of all inclined holes in accordance with step 3;

[0018] Step 5: By analogy, continue to construct horizontal boreholes to different areas in front of the grouting area (B) according to step 4, continue to drive in casing and prepare all branch boreholes in each area and grout all inclined holes respectively until all branch boreholes corresponding to the entire central borehole are grouted.

[0019] The fifth step is to continue to construct horizontal drilling to different areas in front of the grouting area (B) in accordance with the fourth step by analogy. The grouting area is generally divided into A, B, C, D,,,, from near to far. The size of the grouting area is determined according to the design requirements, and the grouting sequence is from near to far.

[0020] In the third step, when grouting each branch hole, it is divided into A-1, A-2, A-3, etc. sections according to the distance from the central hole from far to near. The size of the grouting section is determined according to the formation properties and the capacity of the grouting equipment. The grouting sequence is from far to near.

[0021] The central drill hole in the first step is arranged in the middle of the tunnel face, and the grouting positions are arranged in a feather-like manner across the entire tunnel excavation section. The direction of the grouting hole trajectory is controlled by the ground control system and the guide controller (4) is used for inclination construction;

[0022] The deflection direction of the grouting holes in the same grouting area can also be carried out in different directions in a cross-sequence;

[0023] The present invention can also be used for vertical directional grouting;

[0024] The present invention includes but is not limited to the above.

[0025] Advantages of the present invention:

[0026] The feather-shaped directional soft rock tunnel advance grouting pre-reinforcement method of the present invention has the following advantages:

[0027] (1) Make full use of limited ground space, construct the least number of grouting holes, and perform full-section grouting pre-reinforcement of the surrounding rock in front of the tunnel face;

[0028] (2) The present invention uses flexible drilling tools and directional drill bits, which can control the direction and position of the grouting holes through a ground control system, and perform precise positioning grouting and grouting at any position on the tunnel surrounding rock;

[0029] (3) The present invention is applicable to directional grouting in any direction and directional grouting along a layer;

[0030] (4) The present invention realizes positioning and directional grouting, which can save a large amount of grouting materials and construction workload, effectively improve economic and social benefits, and realize green construction.

[0031] (5) The present invention has theoretical and practical value, and is replicable and extensible. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of pre-grouting pre-reinforcement of feather-shaped directional soft rock tunnel at tunnel face;

[0033] Figure 2 Schematic diagram of the directional grouting zoning and construction sequence of the surrounding rock at the tunnel face;

[0034] Figure 3 Schematic diagram of directional grouting of surrounding rock in tunnel face;

[0035] Figure 4 Tunnel face structure diagram;

[0036] Figure 5 Relationship diagram of flexible drilling tools and drill bits;

[0037] in:

[0038] 1 Feather directional grouting drilling;

[0039] 2 Flexible drilling tool; 2.1 Connecting thread; 2.2 Connector; 2.3 Ear piece; 2.4 Pin / hole;

[0040] 3 Directional drill bit

[0041] 4 Drill guide controller

[0042] 5 Grouting zones

[0043] 6. Tunnel

[0044] 7 Palm face

[0045] 8 surrounding rock. DETAILED DESCRIPTION

[0046] The present invention is further described below in conjunction with an example of a subway tunnel in Beijing, but the present invention is not limited to the following example.

[0047] The underground of a subway tunnel in Beijing is 0-15 meters below the ground with interlayers of silty clay and sand. There is abundant groundwater, which is a mixture of phreatic water and confined water. The cross section of the subway tunnel is 100m 2 When the tunnel (6) is constructed in the soft rock formation (8) to the tunnel face (7), the surrounding rock in front of the tunnel face is pre-reinforced by grouting.

[0048] The first step of implementing the present invention is to put the drilling machine in place, carry out construction layout according to the tunnel design drawing, determine the location of the grouting hole, and the drilling position is arranged in principle at the center of the tunnel face;

[0049] The second step is to use a horizontal drilling rig to construct the grouting holes, and first construct to the A grouting area according to the designed grouting division position; drill the steel casing, the diameter of which is larger than the outer diameter of the drill bit;

[0050] The third step is to control the drill bit in a directional manner in the ground control room, control the position and direction of the drill bit guide controller (4), use a flexible drilling tool and a directional drill bit to directionally drill an inclined hole in the designed branch hole grouting direction, and drill to the A-1 section of the tunnel face A grouting area, and flush the hole;

[0051] The fourth step is to install a flange at the hole, connect the grouting pump, and use the flexible drilling tool and drill bit to perform high-pressure grouting on the A-1 section of the tunnel face grouting area. The grouting pressure is about 0.5, and the stable grouting time is about 1 hour.

[0052] Step 5: withdraw the drill bit by about 0.5 meters and perform high-pressure grouting on the A-2 section of the tunnel face grouting area. The grouting pressure is about 0.5 and the stable grouting time is about 1 hour.

[0053] Step 6: Retract the drill bit in sequence, about 0.5 meters at a time, and carry out high-pressure grouting in each grouting direction and each grouting section of the A grouting area in sequence. The grouting directions are carried out in a cross order to complete the grouting reinforcement of the A grouting area of ​​the tunnel face.

[0054] Step 7: According to the tunnel grouting zone (5), continue to construct grouting holes along the horizontal borehole to the B grouting zone, continue to drive the casing (1), and repeat steps 3 to 6 to complete the grouting reinforcement of each grouting direction and each grouting section of the B grouting zone; then complete the preparation and grouting of different branch boreholes in turn;

[0055] Step 8: Continue to construct grouting holes along the horizontal drilling hole to the C grouting area, continue to drive the casing (1), and repeat steps 3 to 6 to complete the grouting reinforcement of each grouting direction and each grouting section of each grouting area such as C, D, E, and F in sequence;

[0056] The above construction is carried out step by step and the grouting of all designed sections is completed to form a surrounding rock reinforcement area in front of the tunnel face, and then the excavation of the tunnel face is carried out.

[0057] The feather-shaped directional soft rock tunnel advance grouting pre-reinforcement method of the present invention includes but is not limited to the above content, and is also applicable to vertical equal drilling directional grouting related methods.

Claims

1. A method for grouting pre-reinforcement using a feather-shaped directional soft rock tunnel advance grouting pre-reinforcement structure, characterized in that: A feather-shaped directional soft rock tunnel advance grouting pre-reinforcement structure, comprising a feather-shaped directional grouting borehole (1), a flexible drilling tool (2), a directional drill bit (3), and a drill bit guide controller (4); wherein the feather-shaped directional grouting borehole (1) comprises a central borehole and a plurality of branch boreholes dispersed in all directions, the central borehole being a long borehole pre-drilled by a drilling rig in the same direction as the axial length of the tunnel, a steel casing for protecting the well wall being lowered into the long borehole, and the branch boreholes being a plurality of curved boreholes extending from the central borehole in all directions and pointing to the inner wall of the tunnel (6), the number of branch boreholes being 2 to 6 in the circumferential direction of the central borehole, and the branch boreholes being evenly distributed in the axial length direction of the central borehole, and the overall structure of the central borehole and the branch boreholes being a feather-shaped structure; The flexible drilling tool (2) comprises a connecting thread (2.1), a connector (2.2), an ear piece (2.3), a pin / hole (2.4) and an outer wall rubber high-pressure protection structure (2.5); one end of the connecting body (2.2) is a connecting thread (2.1), and the other end is an ear piece (2.3), and the ear piece (2.3) is provided with a pin / hole (2.4); a plurality of connecting bodies (2.2) are connected end to end, and the connection is as follows: the connecting thread (2.1) and the ear piece (2.3) are connected and fixed by the pin / hole (2.4), so as to form a flexible long connection. The outer periphery of the flexible long connector is an outer wall rubber high-pressure protective structure (2.5); one end of the flexible long connector extends into the borehole for drilling and grouting, and the other end is located outside the borehole for connection with a grouting pump; the end of the flexible long connector extending into the borehole is a directional drill bit (3); the directional drill bit (3) comprises a drill bit body and a drill bit guide controller (4), the drill bit guide controller (4) is fixed to the drill bit body, and the drill bit guide controller (4) is controlled by a ground control system to measure the drill bit position and control the drill bit drilling direction; The specific method includes the following steps: Step 1: Locate the grouting holes on site and install the horizontal drilling equipment; Step 2: The grouting area is divided into A, B, C, D... areas from the starting point of the central drilling hole to the farthest point. The size of the grouting area is determined according to the design requirements, and the grouting sequence is from near to far. Use a horizontal drilling rig to drill the central hole to the depth of the grouting area A, and drive in the casing; Step 3: insert the flexible drilling tool (2) and the directional drill bit (3) into the borehole, and drill the first branch borehole along the designed grouting hole trajectory direction and position of the branch borehole, with the drill bit guide controller (4) controlling the drilling direction to create an inclination; pump cement slurry into the branch boreholes through the flexible drilling tool, and divide the branch boreholes into A-1, A-2, A-3, etc. sections according to the distance from the central borehole from far to near during grouting. The size of the grouting section is determined according to the formation properties and the capacity of the grouting equipment, and the grouting sequence is carried out from far to near; the first branch borehole end is grouted. The first section A-1 of the first branch is subjected to high-pressure rotary grouting, and the grouting time is reached at the designed grouting pressure, and the grouting is stopped; the drill is retracted, and the high-pressure rotary grouting is carried out when the drill bit reaches the second grouting section A-2, and the grouting time is reached at the designed grouting pressure, and the grouting is stopped; and so on, the grouting work of all the inclined holes in the first branch borehole is completed; then the second branch borehole is drilled and the grouting work of all the inclined holes is completed, and so on, the drilling and grouting of all the branch boreholes in the starting end area A of the central borehole are completed; Step 4: Continue to drill the center hole to the depth of the second grouting area B, and continue to drive the casing; and drill all the branch holes in the grouting area B and grout all the inclined holes in turn according to the third step; Step 5: By analogy, continue to construct the central borehole to different areas in front of the grouting area B according to step 4, continue to drive in casing and drill all branch boreholes in each area and grout all inclined holes respectively until all branch boreholes corresponding to the entire central borehole are grouted.

2. The method according to claim 1, characterized in that In the first step, the center drill hole is arranged in the middle of the tunnel face, and the grouting positions are distributed in a feather-like manner across the entire tunnel excavation section. The direction of the grouting hole trajectory is controlled by the ground control system using the drill guide controller (4) to create an inclination for construction.

3. The method according to claim 1, characterized in that The inclination directions of the grouting holes in the same grouting area are carried out in a cross sequence in different directions.

4. The method according to claim 1, characterized in that The connector (2.2) is placed in the flexible drilling tool, is the main part of the drilling tool, and plays a role in transmitting pressure and torque; the pin / hole (2.4) is placed in the flexible drilling tool, is the main part of the drilling tool, and connects and fixes the connector (2.2).

5. The method according to claim 1, characterized in that The borehole diameter is larger than the outer diameter of the casing; and the outer diameter of the casing is larger than the outer diameter of the directional drill bit (3).

6. The method according to claim 1, characterized in that The feather-shaped directional soft rock tunnel advance grouting pre-reinforcement structure is located in front of the tunnel face (7) in the tunnel (6) and is used for pre-reinforcement of the surrounding rock (8).

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