CN220621854U - 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 problems that slurry is wasted and excavation difficulty and construction risk are increased due to solidification and hardening of rock and soil bodies in an excavation range by an existing advanced small-conduit grouting method. The small-section tunnel advanced support structure is characterized in that a steel support is arranged at the position of the tunnel close to the tunnel face, a drill hole is arranged at the outer side of an arch line of the tunnel, a grouting pipe is inserted into the drill hole in an inclined way along the central line direction of the drill hole, the area between the outer wall of the grouting pipe and the wall of the drill hole is divided into a first grouting area and a second grouting area, the first grouting area is filled with mortar, the second grouting area and the inner cavity of the grouting pipe are filled with slurry, and the solidified mortar, the slurry, the rock-soil body around the drilling hole and the grouting pipe form an integral arch-shaped solidified shell together. The method is used for the construction 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.

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 method can not effectively control the diffusion direction of slurry.

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, inserting a grouting pipe into a drilled hole, and inserting the front end of the grouting pipe into the bottom of the drilled hole or a position deeper than the bottom of the drilled hole; the two sides of the drilling hole are respectively a control grouting side and a directional grouting side, on the section perpendicular to the drilling hole direction, the outer wall of the grouting pipe and the wall of the drilling hole are provided with at least two contact points or contact arcs, the area between the outer wall of the grouting pipe and the wall of the drilling hole is divided into at least two small areas, the small areas on the control grouting side of the drilling hole are all first grouting areas, and the small areas on the directional grouting side of the drilling hole are all second grouting areas; the solid pipe wall is arranged between the inner cavity of the grouting pipe and the first grouting area, the pipe wall between the inner cavity of the grouting pipe and the second grouting area is provided with grouting holes, and the rear section of the grouting pipe is provided with a grouting stopping section.

To facilitate insertion of the grouting pipe into the borehole, further: the front end of the grouting pipe is in a pointed cone shape and is inserted into the rock soil body at the bottom of the drilling hole.

In order to facilitate the processing of the grouting pipe and also to improve the strength of the grouting pipe, further: the grouting pipe is a concave steel pipe, the pipe wall of the grouting pipe is provided with at least two arc-shaped grooves protruding towards the central line of the grouting pipe, and the arc-shaped grooves are arranged along the length direction of the grouting pipe.

Specific: the pipe wall of the grouting pipe is uniformly provided with three arc-shaped grooves protruding towards the central line of the grouting pipe, the area between the outer wall of the grouting pipe and the wall of the drilled hole is divided into three small areas with the same shape, one small area is a first grouting area, and the other two small areas are second grouting areas.

The grouting pipe is generally inserted into a drilled hole in a driving or jacking mode, so as to avoid damage to the rear end of the grouting pipe, and also facilitate grouting through the grouting pipe, and further comprises: the rear end of the grouting pipe is provided with a stiffening hoop.

Specific: the aperture of the grouting holes of the grouting pipe is phi 8mm, the hole spacing of the grouting holes is 10cm, the grouting holes are arranged in a plum blossom shape, the length of the grouting section of the grouting pipe is not less than 30cm, and the rear end of the grouting pipe is welded with stiffening hoops with phi 6.5 mm.

S2, preparing mortar, pouring the mortar into the first grouting area, and closing the 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 slurry into a second grouting area through a grouting pipe. In order to ensure grouting quality, further: and (5) grouting after cleaning holes in the second grouting area.

The directional grouting method for drilling has the beneficial effects that: after the grouting pipe is inserted into the drilled hole, the drilling hole is divided into a first grouting area and a second grouting area by the grouting pipe, mortar is poured into the first grouting area, the holes and gaps of a rock-soil body on the grouting side are closed, grouting is performed on the second grouting area through the grouting pipe, and most of slurry can only diffuse to the rock-soil body on the directional grouting side because the gaps and gaps of the rock-soil body on the grouting side are closed, so that directional grouting is effectively realized.

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 20-40 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, grouting pipes are respectively inserted into the drilling holes, a first grouting area of each grouting pipe is positioned on one side, which is close to a tunnel, to be excavated, a second grouting area of each grouting pipe is positioned on one side, which is far away from the tunnel, to be excavated, and the rear ends of the grouting pipes are fixedly connected with a 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 to E of the small-section tunnel advanced grouting excavation method. The small-section tunnel advanced support structure is characterized in that steel supports are arranged at the position, close to a tunnel face, of a tunnel, drilling holes are arranged on the outer side of an arch line of the tunnel at intervals along the direction of the arch line, one side, close to the tunnel, of the drilling holes, which is to be excavated is a grouting control side, one side, opposite to the tunnel, of the drilling holes, which is to be excavated is a directional grouting side, the direction of a drilling center line is inclined upwards, grouting pipes are inserted into the drilling holes, the front ends of the grouting pipes are located at the bottoms of the drilling holes or at positions deeper than the bottoms of the drilling holes, the rear ends of the grouting pipes are fixedly connected with the steel supports, and grouting stop sections are arranged at the rear ends of the grouting pipes; on a section perpendicular to the drilling direction, the outer wall of the grouting pipe and the wall of the drilling hole are provided with at least two contact points or contact arcs, the area between the outer wall of the grouting pipe and the wall of the drilling hole is divided into at least two small areas, the small areas on the grouting control side of the drilling hole are all first grouting areas, and the small areas on the directional grouting side of the drilling hole are all second grouting areas; a solid pipe wall is arranged between the inner cavity of the grouting pipe and the first grouting area, and grouting holes are formed in the pipe wall between the inner cavity of the grouting pipe and the second grouting area; the first grouting area of the drilling hole is filled with mortar, the second grouting area of the drilling hole and the inner cavity of the grouting pipe are filled with slurry, and the solidified mortar, the slurry, the rock mass around the drilling hole and the grouting pipe form an integral arch-shaped solidified shell together.

To facilitate insertion of the grouting pipe into the borehole, further: the front end of the grouting pipe is in a pointed cone shape, and the front end of the grouting pipe is positioned in the rock soil body at the bottom of the drilling hole.

Specific: on the cross section of the grouting pipe, the outer contour of the grouting pipe can be polygonal, and the vertexes of the polygonal are contacted with the wall of the drilled hole. Or, on the cross section of the grouting pipe, the outer contour of the grouting pipe is in a spindle shape, or the middle part of the grouting pipe is rectangular, and two opposite sides of the grouting pipe are in a minor arc arch shape.

In order to facilitate the processing of the grouting pipe and also to improve the strength of the grouting pipe, further: the grouting pipe is a concave steel pipe, the pipe wall of the grouting pipe is provided with at least two arc-shaped grooves protruding towards the central line of the grouting pipe, and the arc-shaped grooves are arranged along the length direction of the grouting pipe.

Specific: the pipe wall of the grouting pipe is uniformly provided with three arc-shaped grooves protruding towards the central line of the grouting pipe, the area between the outer wall of the grouting pipe and the wall of the drilled hole is divided into three small areas with the same shape, one small area is a first grouting area, and the other two small areas are second grouting areas.

The grouting pipe is generally inserted into a drilled hole in a driving or jacking mode, so as to avoid damage to the rear end of the grouting pipe, and also facilitate grouting through the grouting pipe, and further comprises: the rear end of the grouting pipe is provided with a stiffening hoop.

Specific: the aperture of the grouting holes of the grouting pipe is phi 8mm, the hole spacing of the grouting holes is 10cm, the grouting holes are arranged in a plum blossom shape, the length of the grouting section of the grouting pipe is not less than 30cm, and the rear end of the grouting pipe is welded with stiffening hoops with phi 6.5 mm.

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 on the grouting side, the holes and gaps of the rock-soil body on the side, close to the tunnel, of the drilled holes are sealed, and when grouting is performed through the small guide pipe, the slurry is diffused into the rock-soil body outside the tunnel excavation range as much as possible, so that grouting quantity is saved, and excavation operation of the rock-soil body is facilitated. The solidified and hardened mortar, slurry, a rock-soil body around the drill hole and the grouting pipe form an integral arch-shaped solidified shell together, the strength of the arch-shaped solidified shell is high, a stable support can be provided for the rock-soil body above the tunnel 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, grouting pipe 2, first slip casting district 3, second slip casting district 4, steel support 5.

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 the construction of the drilling hole 1 is completed, the grouting pipe 2 is inserted into the drilling hole 1, and the front end of the grouting pipe 2 is inserted into the bottom of the drilling hole 1 or a position deeper than the bottom of the drilling hole.

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.

When the grouting pipe 2 is inserted into the borehole 1, attention should be paid to the relative control of the orientation of the grouting side and the directional grouting side of the grouting pipe 2. Referring to fig. 2, in a cross section perpendicular to the direction of the borehole 1, the outer wall of the grouting pipe 2 and the wall of the borehole 1 have at least two contact positions, the contact positions are contact points or contact arcs, the area between the outer wall of the grouting pipe 2 and the wall of the borehole 1 is divided into at least two small areas, the number of the small areas is consistent with that of the contact positions, all the small areas are divided into two types, one type is a small area positioned on the grouting control side of the borehole 1, the small areas are all the first grouting areas 3, and the other type is a small area positioned on the directional grouting side of the borehole 1, and the small areas are all the second grouting areas 4. The inner cavity of the grouting pipe 2 is a solid pipe wall between the first grouting area 3, namely the inner cavity of the grouting pipe 2 is not communicated with the first grouting area 3; the pipe wall between the inner cavity of the grouting pipe 2 and the second grouting area 4 is provided with grouting holes, namely the inner cavity of the grouting pipe 2 is communicated with the second grouting area 4. The inner cavity of the grouting pipe 2 is used for grouting the second grouting area 4, so that the rear section of the grouting pipe 2 is provided with a grouting stopping section. The grouting pipe 2 is generally a steel pipe, for example, the grouting pipe 2 is made of a hot rolled seamless steel pipe with a wall thickness of 3.5mm and an outer diameter of 42mm, the aperture phi of grouting holes is 8mm, the hole spacing of the grouting holes is 10cm, the grouting holes are arranged in a quincuncial shape, and the length of a grouting stopping section of the grouting pipe 2 is not less than 30cm.

The grouting pipe 2 can be inserted into the drill hole 1 by hammering, pressing or jacking. In order to facilitate insertion of the grouting pipe 2 into the borehole 1, the front end of the grouting pipe 2 is tapered. The front end of the grouting pipe 2 is inserted into a rock-soil body at the bottom of the hole of the drill hole 1, so that the grouting pipe not only plays a role in separating and forming the first grouting area 3 and the second grouting area 4, but also plays a role in fixing the grouting pipe 2 and avoiding the grouting pipe 2 from sliding out of the drill hole 1. In order to avoid damage to the rear end of the grouting pipe 2 during construction and to facilitate grouting through the grouting pipe 2, the rear end of the grouting pipe 2 is provided with stiffening hoops. For example, a stiffening cuff of 6.5mm is welded to the rear end of the grouting pipe 2.

The shape of the grouting pipe 2 is exemplified below. In the cross section of the grouting pipe 2 and the borehole, the outer contour of the grouting pipe 2 may be a regular polygon, such as a triangle, a quadrangle, etc., the diameter of the circumscribed circle of the polygon being identical to the diameter of the borehole 1. The outer contour of the grouting pipe 2 can also be irregularly shaped, such as spindle-shaped, or rectangular in the middle and with minor arc-shaped on opposite sides of the rectangle, in the cross section of the grouting pipe 2 and the borehole.

Referring to fig. 1 and 2, in order to facilitate the processing of the grouting pipe 2 and also to improve the strength of the grouting pipe 2, the grouting pipe 2 is a concave steel pipe. The pipe wall of the grouting pipe 2 is provided with at least two arc grooves protruding towards the central line of the grouting pipe 2, the arc grooves are arranged along the length direction of the grouting pipe 2, namely, on the cross section of the grouting pipe 2, the side wall and the bottom of the arc grooves are continuous arcs, the arcs protrude towards the center of the grouting pipe 2, and the central line of the arc grooves is parallel to the central line of the grouting pipe 2. Referring to fig. 1 and 2, three arc-shaped grooves protruding toward the center line of the grouting pipe 2 are uniformly formed in the pipe wall of the grouting pipe 2, the area between the outer wall of the grouting pipe 2 and the hole wall of the drill hole 1 is divided into three small areas with the same shape, one small area is a first grouting area 3, and the other two small areas are second grouting areas 4. The two small areas corresponding to the second grouting area 4 can be isolated from each other, and a notch communicated with the two small areas corresponding to the second grouting area 4 can be arranged on the outer wall of the grouting pipe.

S2, preparing mortar, pouring the mortar into the first grouting area 3, and sealing the orifice of the first grouting area 3 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. During the mortar pouring process, the pouring pipe is preferably inserted into the hole bottom, the pouring pipe is gradually pulled out at a constant speed along with the mortar pouring, the mortar is uniformly stirred, the mortar is used along with the stirring, and the mortar mixing ratio is in accordance with the design. The mortar in the first grouting area 3 is compact and full, and after the mortar is poured, a plugging material is used for sealing the orifice of the first grouting area 3 to prevent the mortar from leaking.

If the first grouting area 3 and the second grouting area 4 are communicated with each other, when grouting mortar, the mortar enters the second grouting area 4, so that grouting of the subsequent step S3 is affected, and therefore the grouting pipe 2 needs to completely separate the first grouting area 3 and the second grouting area 4. When the number of the small areas corresponding to the first grouting area 3 is two or more, grouting mortar can be respectively poured into each small area, and grouting mortar is poured into all the first grouting areas 3, so that the holes and gaps of a rock-soil body on the grouting side are closed by the drill hole 1; alternatively, the grouting pipe 2 is provided with channels or indentations that communicate with the respective small areas of the first grouting area 3 and do not communicate with the second grouting area 4, so that mortar can flow between the small areas of the first grouting area 3.

S3, preparing slurry, and grouting the slurry into a second grouting area 4 through a grouting pipe 2. In order to ensure grouting quality, grouting is performed after hole cleaning is performed on the second grouting area 4. For example, the sand in the second grouting area 4 is blown clean by high-pressure air, and plastic materials such as hemp threads or anchoring agents are used for plugging 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 5 and carrying out supporting construction of the steel support 5, wherein the steel support 5 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 included angles between the drilling holes 1 and the longitudinal central line of the tunnel in 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, a drill bit with a diameter phi of 150mm is used for drilling, the distance between adjacent drill holes 1 is 20-40 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 is performed strictly according to the determined drilling position, so that the accuracy of the position of the drilling 1 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 above-mentioned directional grouting method for drilling holes, grouting pipes 2 are respectively inserted into the respective drilling holes 1, the first grouting area 3 of the grouting pipe 2 is located at a side close to the tunnel to be excavated, the second grouting area 4 of the grouting pipe 2 is located at a side opposite to the tunnel to be excavated, that is, the interface between the first grouting area 3 and the second grouting area 4 is perpendicular to the radial direction of the arching line, and the first grouting area 3 is located at a side close to the tunnel to be excavated. After the grouting pipe 2 is inserted into the drilling hole 1, the rear end of the grouting pipe 2 is fixedly connected with the steel support 5.

D. Mortar is poured into the first grouting areas 3 of the respective boreholes 1 according to the step S2 of the borehole directional grouting method described above. The mortar permeates into the rock soil body of the side, close to the tunnel, to be excavated, of the drilling hole 1, and the first grouting area 3 is completely filled with the mortar.

E. Grouting is carried out on the second grouting areas 4 of the drilling holes 1 respectively according to the step S3 of the drilling hole directional grouting method, so as to form an arch-shaped concretion 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 should be strictly controlled within the allowable range during grouting, 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 grouting 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 to 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 5 is arranged at a position, close to a tunnel face, of the tunnel, and the steel support 5 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 °.

The grouting pipe 2 is inserted into the drilling hole 1, and the front end of the grouting pipe 2 is positioned at the bottom of the drilling hole 1 or at a position deeper than the bottom of the drilling hole, so that the isolated first grouting area 3 and the isolated second grouting area 4 which are separated by the grouting pipe 2 are not communicated. The rear end of the grouting pipe 2 is fixedly connected with a steel support 5, so that the stability of the grouting pipe 2 is ensured. The grouting pipe 2 is generally inserted into the drill hole 1 by driving or jacking, so that the grouting pipe 2 is conveniently inserted into the drill hole 1, the front end of the grouting pipe 2 is in a pointed cone shape, and the front end of the grouting pipe 2 is positioned in the rock soil body at the bottom of the drill hole 1. In order to avoid damage to the rear end of the grouting pipe 2 during construction and to facilitate grouting through the grouting pipe 2, the rear end of the grouting pipe 2 is provided with stiffening hoops. For example, a stiffener with a diameter of 6.5mm is welded to the tail of the grouting pipe 2.

The grouting pipe 2 is used for grouting on the one hand and plays a role of separation on the other hand. On the section perpendicular to the direction of the drilling hole 1, the outer wall of the grouting pipe 2 and the wall of the drilling hole 1 are provided with at least two contact points or contact arcs, the area between the outer wall of the grouting pipe 2 and the wall of the drilling hole 1 is divided into at least two small areas, the small areas on the grouting control side of the drilling hole 1 are all first grouting areas 3, and the small areas on the directional grouting side of the drilling hole 1 are all second grouting areas 4. In order to facilitate the processing of the grouting pipe 2 and also to facilitate the construction, the contact points and contact arcs between the outer wall of the grouting pipe 2 and the wall of the borehole 1 should be as few as possible. For example, in the cross section of the grouting pipe 2, the outer contour of the grouting pipe 2 is polygonal, the vertices of the polygon are all in contact with the wall of the borehole 1, and the polygon is triangle, quadrangle, or the like. For another example, on the cross section of the grouting pipe 2, the outer contour of the grouting pipe 2 is spindle-shaped, and at the moment, the outer wall of the grouting pipe 2 and the hole wall of the drilling hole 1 have only two contact points; or, the outer contour of the grouting pipe 2 is rectangular in the middle and the two opposite sides of the rectangle are in a shape of a minor arc, and at the moment, the outer wall of the grouting pipe 2 and the hole wall of the drilling hole 1 only have two sections of contact arcs. In addition, in order to facilitate the processing of the grouting pipe 2, and simultaneously, in order to improve the strength of the grouting pipe 2, the grouting pipe 2 can be a concave steel pipe, the pipe wall of the grouting pipe 2 is provided with at least two arc grooves protruding towards the central line of the grouting pipe 2, the arc grooves are arranged along the length direction of the grouting pipe 2, namely, on the cross section of the grouting pipe 2, the side wall and the groove bottom of the arc grooves are continuous arc lines, the arc lines protrude towards the center of the grouting pipe 2, and the central line of the arc grooves is parallel to the central line of the grouting pipe 2. Referring to fig. 1 and 2, three arc-shaped grooves protruding toward the center line of the grouting pipe 2 are uniformly formed in the pipe wall of the grouting pipe 2, and small areas between the outer wall of the grouting pipe 2 and the hole wall of the drill hole 1 are divided into three small areas with the same shape, wherein one small area is a first grouting area 3, and the other two small areas are second grouting areas 4. The two small areas corresponding to the second grouting area 4 can be isolated from each other, and a notch communicated with the two small areas corresponding to the second grouting area 4 can be arranged on the outer wall of the grouting pipe.

The inner cavity of the grouting pipe 2 is a solid pipe wall between the first grouting area 3, namely, the inner cavity of the grouting pipe 2 is not communicated with the first grouting area 3. The pipe wall between the inner cavity of the grouting pipe 2 and the second grouting area 4 is provided with grouting holes, for example, the aperture of the grouting holes of the grouting pipe 2 is phi 8mm, and the grouting holes are arranged in a quincuncial mode at a hole spacing of 10 cm. The rear section of the grouting pipe 2 is provided with a grouting stop section, for example, the length of the grouting stop section of the grouting pipe 2 is not less than 30cm.

With respect to the shape of the individual grouting pipe 2 and the relation to the grouting pipe 2 and the borehole 1, reference can be made to the description of the first subject borehole directional grouting method steps S1 and S2 described above.

The first grouting area 3 of the drill hole 1 is filled with mortar, the grouting pipe 2 and the hole wall of the drill hole 1 are arranged around the first grouting area 3, and the hole wall corresponding to the first grouting area 3 is a rock-soil body filled with mortar. The second grouting area 4 of the drill hole 1 and the inner cavity of the grouting pipe 2 are filled with grouting liquid, and the solidified grouting liquid, the rock mass around the drill hole 1 and the grouting pipe 2 form an integral arch-shaped solidified shell together.

Claims (9)

1. The utility model provides a small-section tunnel advance support structure, the tunnel is close to the position of face and sets up steel support (5), the outside of the arching line of tunnel and along the arch line direction interval be equipped with drilling (1), the one side that drilling (1) is close to the tunnel needs to excavate is control slip casting side, the one side that drilling (1) is the directional slip casting side that is back to the tunnel needs to excavate, the direction of drilling (1) central line is upwards to the slant, slip casting pipe (2) have been inserted in drilling (1), the front end of slip casting pipe (2) is located the hole bottom of drilling (1) or is deeper than the hole bottom position, the rear end and the steel support (5) fixed connection of slip casting pipe (2) rear end setting up the grout stopping section; the method is characterized in that: on a section perpendicular to the direction of the drilling hole (1), the outer wall of the grouting pipe (2) and the hole wall of the drilling hole (1) are provided with at least two contact points or contact arcs, the area between the outer wall of the grouting pipe (2) and the hole wall of the drilling hole (1) is divided into at least two small areas, the small areas on the grouting control side of the drilling hole (1) are all first grouting areas (3), and the small areas on the directional grouting side of the drilling hole (1) are all second grouting areas (4); a solid pipe wall is arranged between the inner cavity of the grouting pipe (2) and the first grouting area (3), and grouting holes are formed in the pipe wall between the inner cavity of the grouting pipe (2) and the second grouting area (4); the first grouting area (3) of the drilling hole (1) is filled with mortar, the second grouting area (4) of the drilling hole (1) and the inner cavity of the grouting pipe (2) are filled with the poured mortar, and the solidified mortar, the rock soil body around the drilling hole (1) and the grouting pipe (2) form an integral arched solidified shell together.

2. The small section tunnel advance support structure of claim 1, wherein: the front end of the grouting pipe (2) is in a pointed cone shape, and the front end of the grouting pipe (2) 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: on the cross section of the grouting pipe (2), the outer contour of the grouting pipe (2) is polygonal, and the vertexes of the polygonal are contacted with the wall of the drilling hole (1).

4. The small section tunnel advance support structure of claim 1, wherein: on the cross section of the grouting pipe (2), the outer contour of the grouting pipe (2) is in a spindle shape or in a shape that the middle part is rectangular and two opposite sides of the rectangle are in a minor arc arch shape.

5. The small section tunnel advance support structure of claim 1, wherein: the grouting pipe (2) is a concave steel pipe, the pipe wall of the grouting pipe (2) is provided with at least two arc-shaped grooves protruding towards the central line of the grouting pipe (2), and the arc-shaped grooves are arranged along the length direction of the grouting pipe (2).

6. The small section tunnel advance support structure of claim 5, wherein: the pipe wall of the grouting pipe (2) is uniformly provided with three arc-shaped grooves protruding towards the central line of the grouting pipe (2), the area separation between the outer wall of the grouting pipe (2) and the hole wall of the drilling hole (1) is three small areas with the same shape, one small area is a first grouting area (3), and the other two small areas are second grouting areas (4).

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 grouting pipe (2) is provided with a stiffening hoop.

8. The small section tunnel advance support structure of claim 7, wherein: the aperture of the grouting holes of the grouting pipe (2) is phi 8mm, the hole spacing of the grouting holes is 10cm, the grouting holes are arranged in a plum blossom shape, the length of a grouting stopping section of the grouting pipe (2) is not less than 30cm, and a stiffening hoop with phi 6.5mm is welded at the rear end of the grouting pipe (2).

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.