CN220621852U - Advance support structure for small-section tunnel - Google Patents

Abstract

The utility model discloses a small-section tunnel advanced support structure, relates to the field of tunnel engineering, and solves the problem that the existing directional grouting scheme cannot effectively control the slurry diffusion direction. The technical scheme adopted by the utility model is as follows: the utility model provides a small-section tunnel advance support structure, the tunnel is close to the position of face and sets up the steel support, the outside of tunnel arching line is equipped with the drilling, the drilling is inserted and is had a baffle that the face is fixed with the tubule, the baffle separates into first slip casting district and second slip casting district with the region between the outer wall of tubule and the pore wall of drilling, first slip casting district is located the one side that is close to the tunnel and fills mortar, be the thick liquid of pouring in the inner chamber of second slip casting district and slip casting pipe, consolidate hardened mortar, thick liquid and the rock soil body around the drilling, and the small duct forms holistic arch with the baffle and consolidates the casing jointly. The utility model is used for the advanced support of the small-section tunnel.

Description

Advance support structure for small-section tunnel

Technical Field

The utility model relates to the field of tunnel engineering, in particular to a small-section tunnel advance support structure.

Background

At present, the excavation construction of a small-section tunnel at a hole section which is broken in a weak state and has underground water mainly adopts an advanced small-conduit grouting method, rock and soil bodies after advanced drainage are pre-consolidated through advanced small-conduit grouting, an arch-shaped shell is formed above an excavation section, and the capability of resisting the top load of the tunnel is enhanced.

The conventional advance small conduit grouting method has the defects that when the small conduit grouting method is used for grouting the small conduit, the slurry is easier to enter the rock-soil body in the excavation range downwards in the weak broken hole section with underground water, so that the rock-soil body in the excavation range is solidified and hardened, and the actual grouting amount of the rock-soil body outside the excavation range is insufficient, thereby not only causing slurry waste, but also increasing the excavation difficulty and construction risk. In addition, the diameter of the drilling hole of the small guide pipe is matched with the outer diameter of the grouting pipe, and is generally not more than 50mm, so that the number of the drilling holes is large, and the construction speed is slow. In order to save the cost, the drilling intervals of the small guide pipes are generally controlled to be 20-50 cm, the intervals of the small guide pipes are larger, the rock-soil bodies in the middle parts of two adjacent small guide pipes are difficult to solidify and harden effectively, loose rock-soil bodies are caused to fall down, and potential safety hazards and even collapse risks exist.

The patent with publication number CN 112538850A discloses a device and a method suitable for advanced grouting of a pipe gallery for tree protection, and solves the problem of tree protection in construction of an underground comprehensive pipe gallery through directional grouting. The device comprises a directional grouting pipe, wherein the directional grouting pipe is provided with a grouting directional plate for limiting grouting liquid in the grouting pipe from a grouting hole to structural diffusion on one side of the grouting pipe, the grouting directional plate is positioned on the longitudinal outer wall on one side of the grouting pipe, the grouting pipe on the inner side of the grouting directional plate is provided with a grouting hole, the width of the grouting directional plate is larger than or equal to the diameter of the grouting pipe, and the length of the grouting directional plate is larger than or equal to the design length for limiting grouting liquid in the grouting pipe from the grouting hole to structural diffusion on one side of the grouting pipe. The directional grouting pipe blocks the diffusion direction of grouting liquid through the grouting directional plate, and because a gap exists inevitably between the wall of a drilled hole and the grouting directional plate and a gap exists inevitably in a rock-soil body of the wall of the drilled hole, grouting is completed once, the grouting directional plate has weak blocking effect on grouting liquid diffusion, and grouting liquid can not be blocked from diffusing upwards under the condition of sufficiently low grouting pressure, and grouting liquid cannot be blocked from diffusing downwards.

Disclosure of Invention

The utility model firstly provides a drilling directional grouting method, which solves the problem that the existing directional grouting scheme can not effectively control the slurry diffusion direction.

The technical scheme adopted by the utility model is as follows: the directional grouting method for drilling comprises the following steps:

s1, after drilling construction is completed, a partition board with a small guide pipe fixed on the board surface is inserted into a drilling hole, the front end of the partition board is inserted into the bottom of the drilling hole or a position deeper than the bottom of the drilling hole, the two sides of the drilling hole are respectively a control grouting side and a directional grouting side, and the partition board divides the area between the outer wall of the small guide pipe and the wall of the drilling hole into a first grouting area positioned on the control grouting side and a second grouting area positioned on the directional grouting side. Wherein, the pipe wall of the front section of the small pipe is provided with a grouting hole, and the rear section of the small pipe is a grouting section.

To facilitate insertion of the small conduit and baffle into the borehole, further: the front end of the baffle plate is provided with a triangular tip, the front end of the small guide pipe is provided with a pointed cone, and the front end of the baffle plate is inserted into the rock soil body at the bottom of the drilling hole.

In order to avoid that the first grouting area and the second grouting area are communicated with each other, it is further that: the width of the partition plate is larger than or equal to the diameter of the drilling hole, and the outer diameter of the small guide pipe is not larger than the radius of the drilling hole; or the width of the baffle is smaller than the diameter of the drilling hole, the small guide pipe is fixed at the center line position of the baffle, and the diameters of the two ends of the baffle and the circumcircle corresponding to the point of the small guide pipe farthest from the baffle are consistent with the diameter of the drilling hole on the cross section of the small guide pipe.

In order to increase the stability between the small duct and the partition, it is further: the baffle is strip steel sheet, and a face of baffle sets up the arc wall, and the diameter in arc wall and little pipe external diameter adaptation, little pipe welded fastening are in the arc wall of baffle.

In order to optimize the stress of the small ducts and the partition plates, it is further: the length of the small conduit is longer than that of the partition board, and the rear end of the small conduit is overlapped with the rear end of the partition board. For example, the small conduit is welded and fixed to the center line of the partition plate, and the small conduit is 20cm longer than the partition plate.

The small duct and the partition plate are used as a whole and are generally constructed in a driving or jacking mode, so that damage to the rear end of the small duct during construction is avoided, grouting of the small duct is facilitated, and further: the rear end of the small conduit is provided with a stiffening hoop. For example, the small conduit is made of hot rolled seamless steel pipe with wall thickness of 3.5mm and outer diameter of 42mm, and the aperture of the grouting holeThe grouting holes are arranged at a hole spacing of 20cm and in a quincuncial shape, and the length of the grouting section of the small guide pipe is not less than 30cm.

S2, preparing mortar, pouring the mortar into a first grouting area of the drill hole through a grouting pipe, and sealing an orifice of the first grouting area after the mortar is poured. In order to accelerate the setting speed of the mortar, it is further: and adding an accelerator when preparing mortar.

S3, preparing slurry, and grouting the second grouting area through a small guide pipe.

In order to ensure the grouting quality of the second grouting area, further: and cleaning holes of the second grouting area and the inner cavity of the small catheter, and grouting.

The directional grouting method for drilling has the beneficial effects that: the partition plate divides the area between the outer wall of the small guide pipe and the wall of the drilled hole into a first grouting area and a second grouting area, mortar is poured into the first grouting area, the holes and gaps of a rock-soil body on the grouting side are closed and controlled, grouting is conducted on the second grouting area through the small guide pipe, and most of slurry can only diffuse to the rock-soil body on the directional grouting side due to the fact that the gaps and gaps of the rock-soil body on the grouting side are closed, and therefore directional grouting is effectively achieved.

The utility model also provides a small-section tunnel advanced grouting excavation method, which solves the problems that the existing advanced small-conduit grouting method solidifies and hardens the rock and soil body in the excavation range, wastes slurry and increases the excavation difficulty and construction risk, and adopts the following technical scheme: the advanced grouting excavation method for the small-section tunnel comprises the following steps of:

A. and removing footing scum at a position close to the tunnel face, installing a steel support and carrying out supporting construction of the steel support.

B. Drawing an excavation outline on the tunnel face, marking drilling holes and drilling holes outside the arching line and along the arching line direction, wherein the drilling direction is inclined upwards. For example, adjacent boreholes may be spaced apart by 30-40 cm, with each borehole having an elevation angle of no more than 5 °.

C. According to the step S1 of the directional grouting method for drilling holes, a partition plate with a small guide pipe fixed on the plate surface is respectively inserted into each drilling hole, the first grouting area is positioned close to one side of the tunnel to be excavated, the second grouting area is positioned on the side facing away from the tunnel to be excavated, and the rear ends of the small guide pipe and/or the partition plate are fixedly connected with the steel support.

D. And (3) grouting mortar into the first grouting areas of the respective drilling holes according to the step S2 of the drilling hole directional grouting method.

E. And (3) grouting the second grouting areas of the holes respectively according to the step S3 of the directional grouting method for the holes to form an arch-shaped concreted shell.

F. And excavating, deslagging and supporting the tunnel.

The utility model also provides a small-section tunnel advanced support structure, which is constructed according to the steps A-E of the small-section tunnel advanced grouting excavation method. The utility model provides a small section tunnel advance support structure, the tunnel is close to the position of face and sets up the steel support, the arch line outside of tunnel and along arch line direction interval be equipped with the drilling, the direction slant of drilling central line is upwards, the baffle that a face was fixed with the tubule is inserted to the drilling, the front end of baffle is located the hole bottom of drilling or is deeper than the hole bottom position, the rear end and the steel support fixed connection of tubule and/or baffle, the pipe wall of tubule anterior segment sets up the slip casting hole, the tubule rear end sets up the slip casting section, the baffle separates the region between the outer wall of tubule and the pore wall of drilling into first slip casting district and second slip casting district, first slip casting district is located and fills the mortar near the tunnel needs excavation one side, the second slip casting district is located and is opposite to the tunnel needs excavation one side, the inner chamber of second slip casting district and slip casting pipe is the thick liquid that is the pouring, concreting thick liquid, thick liquid and around the drilling, and the small pipe and baffle jointly form holistic arch casing.

To facilitate insertion of the small conduit and baffle into the borehole, further: the front end of the baffle plate is provided with a triangular tip, the front end of the small guide pipe is provided with a pointed cone, and the front end of the baffle plate is positioned in the rock soil body at the bottom of the drilling hole.

In order to avoid that the first grouting area and the second grouting area are communicated with each other, it is further that: the width of the partition plate is larger than or equal to the diameter of the drilling hole, and the outer diameter of the small guide pipe is not larger than the radius of the drilling hole; or the width of the baffle is smaller than the diameter of the drilling hole, the small guide pipe is fixed at the center line position of the baffle, and the diameters of the two ends of the baffle and the circumcircle corresponding to the point of the small guide pipe farthest from the baffle are consistent with the diameter of the drilling hole on the cross section of the small guide pipe.

In order to increase the stability between the small duct and the partition, it is further: one plate surface of the partition plate is provided with an arc-shaped groove, and the guide pipe is welded and fixed in the arc-shaped groove of the partition plate.

In order to optimize the stress of the small ducts and the partition plates, it is further: the length of the small conduit is longer than that of the partition board, and the rear end of the small conduit is overlapped with the rear end of the partition board. For example, the small conduit is welded and fixed to the center line of the partition plate, and the small conduit is 20cm longer than the partition plate.

The small duct and the partition plate are used as a whole and are generally constructed in a driving or jacking mode, so that damage to the rear end of the small duct during construction is avoided, grouting of the small duct is facilitated, and further: the rear end of the small conduit is provided with a stiffening hoop. For example, the small conduit is made of hot rolled seamless steel pipe with wall thickness of 3.5mm and outer diameter of 42mm, and the aperture of the grouting holeThe grouting holes are arranged at a hole spacing of 20cm and in a quincuncial shape, and the length of the grouting section of the small guide pipe is not less than 30cm.

Specific: the distance between adjacent holes is 30-40 cm, and the elevation angle of the holes is not more than 5 degrees.

The small-section tunnel advanced grouting excavation method and the small-section tunnel advanced supporting structure have the beneficial effects that: by pouring mortar into the first grouting area, the holes and gaps of the rock-soil body on the grouting side are controlled by sealing the drilling holes, and the slurry is diffused into the rock-soil body outside the tunnel excavation range as much as possible when grouting is performed through the small guide pipe in the follow-up process, so that the grouting amount is saved, and the excavation operation of the rock-soil body is facilitated.

The solidified and hardened mortar, slurry, a rock-soil body around the drill hole, the small guide pipe and the partition plate form an integral arch-shaped solidified shell together, the strength of the arch-shaped solidified shell is high, the rock-soil body above the tunnel can be stably supported in the process of excavation, collapse accidents in the process of excavation are prevented, and the safety risk in the process of construction is reduced; the rock-soil body below the arch-shaped consolidation shell is not or only provided with a small amount of grouting or mortar, so that the excavation difficulty is reduced.

Drawings

FIG. 1 is a schematic view of a small section tunnel advance support structure of the present utility model.

Fig. 2 is an enlarged view of the highest positioned borehole of fig. 1.

Reference numerals: drilling 1, small guide pipe 2, partition plate 3, first grouting area 4, second grouting area 5, steel support 6.

Detailed Description

The utility model is further described below with reference to the accompanying drawings.

The first subject of the utility model is a method of directional grouting of a borehole. Referring to fig. 2, the borehole directional grouting method includes the following steps S1 to S3.

S1, after construction of the drilling hole 1 is completed, a partition plate 3 with a small guide pipe 2 fixed on the surface of the partition plate is inserted into the drilling hole 1, the front end of the partition plate 3 is inserted into the bottom of the drilling hole 1 or a position deeper than the bottom of the drilling hole, and the partition plate 3 divides an area between the outer wall of the small guide pipe 2 and the wall of the drilling hole 1 into a first grouting area 4 positioned on the grouting control side and a second grouting area 5 positioned on the directional grouting side.

The two sides of the drilling hole 1 are respectively a control grouting side and a directional grouting side, the control grouting side is the side of the drilling hole 1 which does not need or only needs a small amount of grouting, the directional grouting side is the side of the drilling hole 1 which needs grouting, the central angle corresponding to the control grouting side is generally equal to or different from the central angle corresponding to the directional grouting side, and the sum of the central angle and the central angle is 360 degrees.

The small conduit 2 and the partition plate 3 need to be fixed in advance and then inserted into the drill hole 1 as a whole. The small guide pipe 2 is used for grouting, a grouting hole is formed in the pipe wall of the front section of the small guide pipe 2, and the rear section of the small guide pipe 2 reaches the grouting section. For example, the small conduit 2 is made of a hot rolled seamless steel pipe with a wall thickness of 3.5mm and an outer diameter of 42mm, and the diameter of the grouting holes is the same as that of the grouting holesThe grouting holes are arranged at a hole spacing of 20cm and in a quincuncial shape, and the length of the grouting stopping section of the small guide pipe 2 is not less than 30cm.

The partition 3 is used to divide the area between the outer wall of the small duct 2 and the wall of the borehole 1, and the partition 3 is preferably made of metal, typically steel strip, in view of the fact that the partition 3 will eventually be embedded in the borehole 1. The small conduit 2 and the partition plate 3 can be mechanically fixed or welded, and in order to influence the insertion of the drill hole 1 due to the structure of the small conduit 2 and the partition plate 3, the small conduit 2 is preferably welded and fixed on one plate surface of the partition plate 3. The plate surface of the separator 3 is the surface with the largest area of the separator 3. The cross section of the partition board 3 can be in a straight shape or in an obtuse angle shape, and the small guide pipe 2 is fixed on the board surface of the partition board 3 or in the obtuse angle. The small conduit 2 is fixed at any position on one plate surface of the partition plate 3, preferably at the center line position of the plate surface, and at this time, the axis of the small conduit 2 is parallel to the length direction of the partition plate 3. In order to improve the contact area between the small guide pipe 2 and the partition plate 3 and improve the stability of the small guide pipe 2 and the partition plate 3 after being welded, one plate surface of the partition plate 3 can be provided with an arc-shaped groove, the diameter of the arc-shaped groove is matched with the outer diameter of the small guide pipe 2, and the small guide pipe 2 is welded and fixed in the arc-shaped groove of the partition plate 3.

The small conduit 2 and the partition 3 are integrally formed, and can be inserted into the drill hole 1 by hammering or pressing. In order to facilitate the small guide pipe 2 and the partition plate 3 to be inserted into the drilling hole 1, the front end of the partition plate 3 is provided with a triangular tip, the front end of the small guide pipe 2 is provided with a pointed cone, the front end of the partition plate 3 is inserted into the rock soil body at the bottom of the drilling hole 1, and the first grouting area 4 and the second grouting area 5 are prevented from being communicated at the bottom of the drilling hole 1. The front end of the partition plate 3 is inserted into the rock-soil body at the bottom of the hole of the drill hole 1, and the function of fixing the partition plate 3 can be achieved, so that the partition plate 3 and the small guide pipe 2 are prevented from sliding out of the drill hole 1.

When the small conduit 2 and the partition plate 3 are inserted into the drill hole 1 as a whole, the small conduit 2 can be used as a main stress structure, and the partition plate 3 can be used as a main stress structure. Considering that the small conduit 2 has higher self strength, the small conduit 2 is generally taken as a main stress structure. In order to avoid damage to the rear end of the small pipe 2 during construction and to facilitate grouting of the small pipe 2, the rear end of the small pipe 2 is provided with a stiffening hoop, for example, the rear end of the small pipe 5 is weldedIs provided. When the partition plate 3 is the main stress structure inserted into the drill hole 1, the front ends of the small guide pipes 2 are shorter than or aligned with each other, that is, the depth of the small guide pipes 2 inserted into the drill hole 1 can be shallower than the depth of the partition plate 3 inserted into the drill hole 1, or the depth of the small guide pipes 2 inserted into the drill hole 1 is consistent. When the small conduit 2 is the main stress structure inserted into the drill hole 1, the front end of the small conduit 2 is longer than the front end of the partition board 3, or the front end of the small conduit 2 coincides with the front end of the partition board 3, that is, the depth of the small conduit 2 inserted into the drill hole 1 is deeper than the depth of the partition board 3 inserted into the drill hole 1, or the depth of the small conduit 2 and the partition board 3 inserted into the drill hole 1 are consistent. For example, the length of the small conduit 2 is longer than that of the partition board 3, the rear end of the small conduit 2 coincides with the rear end of the partition board 3, the small conduit 2 is welded and fixed at the center line position of the partition board 3, and the small conduit 2 is longer than the partition board 3 by 20cm.

In order to avoid that the first grouting area 4 and the second grouting area 5 are communicated with each other, the width of the partition plate 3 is larger than or equal to the diameter of the drilling hole 1, and the outer diameter of the small guide pipe 2 is not larger than the radius of the drilling hole 1. When the width of the partition plate 3 is larger than the diameter of the drilling hole 1, the width of the partition plate 3 is slightly larger than the diameter of the drilling hole 1, so that the problem that the partition plate 3 cannot be inserted into the drilling hole is avoided, and two sides of the partition plate 3 are embedded into a rock-soil body on the wall of the drilling hole 1. Alternatively, the width of the partition plate 3 is smaller than the diameter of the drilling hole 1, the small guide pipe 2 is fixed at the center line position of the partition plate 3, and the diameters of the two ends of the partition plate 3 and the circumcircle corresponding to the farthest point of the small guide pipe 2 from the partition plate 3 are consistent with the diameter of the drilling hole 1 on the cross sections of the small drilling hole 1 and the guide pipe 2.

S2, preparing mortar, pouring the mortar into the first grouting area 4 of the drilling hole 1 through a grouting pipe, and sealing the orifice of the first grouting area 4 after the mortar is poured. The mortar is used to close the side of the borehole 1 where no or only a small grouting is required, so the mortar is a dense cement mortar. In order to accelerate the setting speed of the mortar, an accelerator may be added when preparing the mortar. The grouting pipe is preferably inserted into the hole bottom firstly, the grouting pipe is pulled outwards at a constant speed along with the injection of the mortar, the mortar is uniformly stirred, the mortar is used along with the stirring, and the mixing ratio of the mortar is in accordance with the design. The mortar in the first grouting area 4 is compact and full, and after the mortar is poured, a plugging material is used for sealing the orifice of the first grouting area 4 to prevent the mortar from leaking.

And S3, preparing slurry, and grouting the second grouting area 5 through the small guide pipe 2. In order to ensure the grouting quality of the second grouting area 5, the second grouting area 5 and the inner cavity of the small guide pipe 2 are firstly cleaned, and then grouting is carried out. For example, the sand in the second grouting area 5 and the inner cavity of the small guide pipe 2 is blown clean by high-pressure air, and plastic materials such as hemp threads or anchoring agents are used for sealing the orifice and surrounding cracks.

The second subject of the utility model is a small-section tunnel advanced grouting excavation method. Referring to fig. 1, the advanced grouting excavation method for the small-section tunnel comprises the following steps a to F.

A. And removing footing scum at a position close to the tunnel face, installing the steel support 6 and carrying out supporting construction of the steel support 6, wherein the steel support 6 is a steel arch frame.

B. Drawing an excavation outline on the tunnel face, marking drilling holes and drilling holes outside the arching line and along the arching line direction respectively, and enabling the drilling hole 1 to be inclined upwards. The drilling holes can be one layer or two layers, and the elevation angles of the drilling holes 1 on each layer can be equal or can be set into two angles with different sizes. The borehole 1 is located outside the excavation range of the tunnel and extends longitudinally of the tunnel. For example, drilling is performed by using a drill bit with the diameter phi of 150mm, the distance between adjacent drill holes 1 is 30-40 cm, and the elevation angle of the drill holes 1 is not more than 5 degrees. An elevation angle of the borehole 1 of not more than 5 ° means that the borehole 1 is at an angle of not more than 5 ° to the horizontal. The drilling hole 1 should be drilled strictly according to the determined drilling hole position, so that the accuracy of the drilling hole 1 position is ensured. In the drilling process, the direction and the external inserting angle of the drill rod are observed in time, and when the deviation of the direction and the external inserting angle is found to be larger, the direction and the external inserting angle should be adjusted.

C. According to the step S1 of the directional grouting method for drilling holes, a partition plate 3 with a small guide pipe 2 fixed on the plate surface is respectively inserted into each drilling hole 1, a first grouting area 4 is positioned close to one side of a tunnel to be excavated, a second grouting area 5 is positioned on the side facing away from the tunnel to be excavated, and the rear ends of the small guide pipe 2 and/or the partition plate 3 are fixedly connected with a steel support 6. For example, the rear end of the small pipe 2 is welded to the steel support 6.

D. Mortar is poured into the first grouting areas 4 of the respective boreholes 1 according to the step S2 of the borehole directional grouting method described above. The mortar penetrates into the rock soil body on the side of the borehole 1 close to the tunnel, and the first grouting area 4 is also completely filled with the mortar.

E. Grouting is carried out to the second grouting areas 5 of the drilling holes 1 respectively according to the step S3 of the directional grouting method for drilling holes, and the solidified and hardened mortar, the slurry, the rock mass around the drilling holes 1, the small guide pipes 2 and the partition plates 3 form an integral arch-shaped solidified shell.

Grouting is performed by grouting equipment with good performance and working pressure meeting grouting requirements, and field test operation is performed. The highest pressure of the orifice during grouting is strictly controlled within an allowable range, so that single-pipe grouting can be diffused into a rock-soil body with the radius range of 0.5-1.0 m around the drilling hole 1, the grouting pressure is generally 0.5-1.0 MPa, and the fracture of the excavation surface is avoided. The grouting is controlled by taking care of controlling the grouting amount, namely, when each small guide pipe 2 reaches the specified grouting amount, the grouting is ended; if the orifice pressure has reached the prescribed pressure value, but the injection amount is still insufficient, the grouting should be stopped.

F. And excavating, deslagging and supporting the tunnel.

And after the slurry is solidified and reaches the preset strength, carrying out rock-soil body excavation construction, wherein the excavation is carried out in a weak blasting short-footage mode, and if necessary, carrying out slag discharging operation after the excavation is finished. After the slag is discharged, an anchor rod is arranged in the tunnel in a drilling mode, a reinforcing mesh is hung on the anchor rod, concrete is sprayed, and the thickness of the sprayed concrete is generally 8-10 cm, so that a protective layer is formed. And after multiple times of excavation, repeating the steps when the reinforcement range does not meet the requirement of continuous excavation.

The third subject of the utility model is a small-section tunnel advanced support structure, which is a structure constructed according to the steps A-E of the small-section tunnel advanced grouting excavation method of the second subject. As shown in fig. 1, in the small-section tunnel advanced support structure, a steel support 6 is arranged at a position, close to a tunnel face, of the tunnel, and the steel support 6 is a steel arch.

The outside of the arching line of the tunnel and along the direction of the arching line are provided with drilling holes 1 at intervals, one side, close to the tunnel, of the drilling holes 1, which needs to be excavated is a grouting control side, and one side, opposite to the tunnel, of the drilling holes 1, which needs to be excavated, is a directional grouting side. The distance between the adjacent holes 1 is determined according to practice, and the distance between the adjacent holes 1 is generally 30-40 cm; the borehole centerline of the borehole 1 is oriented obliquely upward, with the borehole 1 generally having an elevation angle of no more than 5 °.

A partition plate 3 with a small guide pipe 2 fixed on the plate surface is inserted into the drilling hole 1, the partition plate 3 divides the area between the outer wall of the small guide pipe 2 and the hole wall of the drilling hole 1 into a first grouting area 4 and a second grouting area 5, the first grouting area 4 is located on one side, close to a tunnel, needing to be excavated, and the second grouting area 5 is located on one side, facing away from the tunnel, needing to be excavated. The front end of the partition plate 3 is located at the bottom of the hole of the drill hole 1 or deeper than the bottom of the hole, ensuring that the first grouting area 4 and the second grouting area 5 are not communicated. The first grouting area 4 is filled with mortar, the second grouting area 5 and the inner cavity of the grouting pipe are filled with grouting slurry, and the solidified mortar, the grouting slurry, the rock mass around the drilling hole 1, the small guide pipe 2 and the partition plate 3 form an integral arch-shaped solidified shell together.

The small guide pipe 2 is mainly used for grouting, a grouting hole is formed in the pipe wall of the front section of the small guide pipe 2, and a grouting stopping section is arranged in the rear section of the small guide pipe 2. For example, the small conduit 2 is made of a hot rolled seamless steel pipe with a wall thickness of 3.5mm and an outer diameter of 42mm, and the diameter of the grouting holes is the same as that of the grouting holesThe grouting holes are arranged at a hole spacing of 20cm and in a quincuncial shape, and the length of the grouting stopping section of the small guide pipe 2 is not less than 30cm. The rear end of the small conduit 2 and/or the partition 3 is fixedly connected to the steel support 6, for example, the rear end of the small conduit 2 is welded to the steel support 6.

The small conduit 2 and the partition 3 are integrally constructed, and are generally constructed by driving or jacking in order to facilitate the small conduit2 and baffle 3 insert drilling 1, and baffle 3's front end sets up the triangular tip, and little pipe 2's front end sets up the pointed cone, and baffle 3's front end is located the ground of drilling 1 hole bottom, avoids first slip casting district 4 and second slip casting district 5 to be in the hole bottom intercommunication of changeing hole 1. In order to avoid damage to the rear end of the small pipe 2 during construction and also to facilitate grouting of the small pipe 2, the rear end of the small pipe 2 is provided with a stiffening hoop. For example, the rear end of the small duct 2 is weldedIs provided. In order to improve the stability between the small guide pipe 2 and the partition plate 3, the small guide pipe 2 and the partition plate 3 are prevented from falling off and separating during construction, an arc-shaped groove is formed in one plate surface of the partition plate 3, and the guide pipe is welded and fixed in the arc-shaped groove of the partition plate 3.

With respect to the relation of the borehole 1, the small conduit 2 and the partition 3, reference can be made to the description of step S1 of the first subject borehole directional grouting method described above.

In order to avoid that the first grouting area 4 and the second grouting area 5 are communicated with each other, the width of the partition plate 3 is larger than or equal to the diameter of the drilling hole 1, and the outer diameter of the small guide pipe 2 is not larger than the radius of the drilling hole 1. When the width of the partition plate 3 is larger than the diameter of the drilling hole 1, the partition plate 3 has enough strength, and the partition plate 3 is of a main stress structure, so that bending during construction of the partition plate 3 is avoided. When the width of the partition plate 3 is smaller than the diameter of the drill hole 1, on the cross section of the small guide pipe 2, the diameters of the two ends of the partition plate 3 and the circumscribed circles corresponding to the point of the small guide pipe 2 farthest from the partition plate 3 are consistent with the diameter of the drill hole 1, and at the moment, the small guide pipe 2 is of a main stress structure. The small conduit 2 is generally fixed to the partition 3 at the midline position. In order to optimize the stress of the small conduit 2 and the partition plate 3, the length of the small conduit 2 is longer than that of the partition plate 3, and the rear end of the small conduit 2 and the rear end of the partition plate 3 coincide. For example, the small conduit 2 is welded and fixed to the center line of the partition plate 3, and the small conduit 2 is 20cm longer than the partition plate 3.

Claims (9)

1. The utility model provides a small section tunnel advance support structure, the position that the tunnel is close to the face sets up steel support (6), the outside of the arch wire of tunnel and along the arch wire direction interval be equipped with drilling (1), the direction of drilling (1) central line is upwards inclined, its characterized in that: the partition board (3) with the small guide pipe (2) fixed on the board surface is inserted into the drill hole (1), the front end of the partition board (3) is located at the hole bottom of the drill hole (1) or at a position deeper than the hole bottom, the rear end of the small guide pipe (2) and/or the partition board (3) is fixedly connected with the steel support (6), the grouting holes are formed in the pipe wall of the front section of the small guide pipe (2), the grouting sections are formed in the rear section of the small guide pipe (2), the partition board (3) divides the area between the outer wall of the small guide pipe (2) and the hole wall of the drill hole (1) into a first grouting area (4) and a second grouting area (5), the first grouting area (4) is located at one side close to the tunnel to be excavated and filled with mortar, the second grouting area (5) is located at one side opposite to the tunnel to be excavated, grouting slurry is filled into the inner cavity of the second grouting area (5) and the grouting pipe, the hardened mortar, the grouting liquid and a rock soil body around the drill hole (1), and the small guide pipe (2) and the partition board (3) jointly form an integral arched shell.

2. The small section tunnel advance support structure of claim 1, wherein: the front end of the baffle plate (3) is provided with a triangular tip, the front end of the small guide pipe (2) is provided with a pointed cone, and the front end of the baffle plate (3) is positioned in the rock soil body at the bottom of the hole of the drill hole (1).

3. The small section tunnel advance support structure of claim 1, wherein: the width of the partition plate (3) is larger than or equal to the diameter of the drilling hole (1), and the outer diameter of the small guide pipe (2) is not larger than the radius of the drilling hole (1); or the width of the partition board (3) is smaller than the diameter of the drilling hole (1), the small guide pipe (2) is fixed at the center line position of the partition board (3), and the diameters of the circumscribed circles corresponding to the two ends of the partition board (3) and the farthest point of the small guide pipe (2) from the partition board (3) are consistent with the diameter of the drilling hole (1) on the cross section of the small guide pipe (2).

4. The small section tunnel advance support structure of claim 1, wherein: the baffle (3) is strip steel sheet, and a face of baffle (3) sets up the arc wall, and the diameter in arc wall and little pipe (2) external diameter adaptation, little pipe (2) welded fastening are in the arc wall of baffle (3).

5. The small section tunnel advance support structure of claim 1, wherein: the length of the small conduit (2) is larger than that of the partition board (3), and the rear end of the small conduit (2) is overlapped with the rear end of the partition board (3).

6. The small section tunnel advance support structure of claim 5, wherein: the small conduit (2) is welded and fixed at the center line position of the partition board (3), and the small conduit (2) is 20cm longer than the partition board (3).

7. The small section tunnel advance support structure according to any one of claims 1 to 6, characterized in that: the rear end of the small conduit (2) is provided with a stiffening hoop.

8. The small section tunnel advance support structure of claim 7, wherein: the small guide pipe (2) is made of hot rolled seamless steel pipes with the wall thickness of 3.5mm and the outer diameter of 42mm, the aperture phi of the grouting holes is 8mm, the hole spacing of the grouting holes is 20cm, the grouting holes are arranged in a plum blossom shape, and the length of a grout stopping section of the small guide pipe (2) is not less than 30cm.

9. The small section tunnel advance support structure according to any one of claims 1 to 6, characterized in that: the distance between adjacent drilling holes (1) is 30-40 cm, and the elevation angle of the drilling holes (1) is not more than 5 degrees.