Argillaceous soft rock roadway short anchor supporting method based on surrounding rock reconstruction

Abstract

The invention discloses a short anchor supporting method for an argillaceous soft rock roadway based on surrounding rock reconstruction. According to the method, a supporting-increasing anchor rod is adopted, and trays are arranged at the two ends of the supporting-increasing anchor rod. When a soft rock roadway is tunneled, one end of the support-increasing anchor rod is fixed on the wall surface of the roadway or the surface of the roadway which is excessively deformed and broken is repaired by expanding, brushing and repairing, the support-increasing anchor rod is placed in a drill hole, only one side of the support plate is exposed in the roadway, and a reconstructed body is formed after grouting and solidification are carried out on surrounding rock of the roadway; the trays and the nuts are installed at the ends, exposed on the inner side of the roadway, of the supporting anchor rods, the nuts are screwed, higher pre-tightening force is applied to the reconstructed body on the basis of the anchoring interface bonding effect of the anchor rods and the relative effect between the trays on the two sides, and therefore the high supporting strength is achieved through the short anchoring length. Aiming at soft rock roadway surrounding rock supporting, higher pre-tightening force can be generated through a special action mode of the added supporting anchor rods, so that the reconstructed body has relatively high bearing capacity, displacement limitation is generated on outer side soft rock, the stability of roadway surrounding rock is kept, and efficient supporting is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of surrounding rock reinforcement, and in particular to a short anchor support method for a muddy soft rock tunnel based on surrounding rock reconstruction. Background Art

[0002] In the process of coal mining, soft coal-bearing sedimentary strata are very common, with low strength and easy deformation. Especially after entering the deep environment, the stress environment becomes more complicated. Once the tunnel is excavated and exposed, the surrounding rock will be broken and deformed in a short time. The cross-sectional shape of the tunnel is difficult to maintain, which seriously affects the coal mining operation and affects the safety of personnel. Figure 1 As shown in the figure. Grouting reconstruction or grouting to improve the mechanical properties of surrounding rock is currently a relatively effective control method, but grouting reconstruction alone cannot guarantee the reliability and durability of deep complex soft rock environment engineering safety, and additional anchoring support measures are required. However, traditional anchoring technology relies on the bonding effect between the anchor rod and the surrounding rock, and is restricted by the soft mud rock mass. Its reliable anchoring length needs to be limited to the reconstruction body. This leads to low anchoring strength due to insufficient effective anchoring length, and insufficient overall bearing capacity of the support structure. Summary of the invention

[0003] In order to overcome the defects in the prior art, the present invention proposes a short anchor support method for a muddy soft rock tunnel based on surrounding rock reconstruction, which can effectively support the soft rock and improve the safety of the tunnel.

[0004] The technical solution adopted by the present invention is: a short anchor support method for soft rock tunnels based on surrounding rock reconstruction, characterized in that the support method is based on a support anchor rod, both ends of the support anchor rod are provided with a tray and a nut, and the rod body is provided with a thread; the method comprises:

[0005] Step S1: excavate a new tunnel in the soft rock layer according to the engineering requirements to form a new tunnel; or remove the thickness of the damaged surrounding rock on the surface of the tunnel to form a repair tunnel;

[0006] Step S2, prepare the anchor rods, install the tray and nut on one side, and fix them inside the tunnel surrounding rock or damaged surrounding rock; arrange the anchor rods along the circumference and length direction of the tunnel according to the designed spacing parameters;

[0007] Step S3, build a grouting mold according to the contour of the newly excavated tunnel and then inject grout, or use the pre-arranged support anchor rods to inject grout into the surrounding rock of the repaired tunnel. After the grouting body solidifies, the outer side of the support anchor rod is exposed outside the surrounding rock reconstruction body; Step S4, install a tray and a nut on the outer end of the support anchor rod, and then tighten the nut to apply torque to form a pre-tightening force, complete the anchoring, and form a surrounding rock reconstruction support short anchor support structure.

[0008] As a further improvement of the present invention, an elastic support mechanism is also provided on the support anchor rod, and the elastic support mechanism includes an intermediate shaft, a support plate and an elastic connecting piece. The intermediate shaft is cylindrical and has an internal thread. The support plate consists of two pieces and is arc-shaped. One end of the elastic connecting piece is vertically connected to the intermediate shaft body, and the other end is connected to the inner wall of the support plate. The intermediate shaft is threadedly connected to the rod body and can rotate and move on the rod body.

[0009] As a further improvement of the present invention, in step S2, for the new tunnel, the method of fixing the anchor rod is specifically as follows:

[0010] Step S21, drilling a hole of a certain depth in the surrounding rock of the tunnel with a drill bit, the hole diameter being larger than the maximum width of the tray; the drilling depth of the newly excavated tunnel is 10-15% of the rod length;

[0011] Step S22, putting a tray on the support anchor rod, installing nuts on both the inner and outer sides of the tray, and then extending the support anchor rod into the top of the drill hole;

[0012] Step S23, rotating and moving the elastic supporting connector to the opening of the borehole, so that the supporting plate contacts the borehole wall through the elastic connector.

[0013] As a further improvement of the present invention, in step S2, the method for fixing the anchor rods for repairing the roadway is specifically as follows:

[0014] Step S24, drilling a hole of a certain depth on the surrounding rock of the tunnel with a drill bit, wherein the hole diameter is larger than the maximum width of the tray, and the drilling depth is 70%-80% of the rod length;

[0015] Step S25, put a tray on the inner side of the support anchor rod, install nuts on both sides of the tray, and then extend the support anchor rod into the top of the drill hole;

[0016] Step S26, rotating and moving the elastic supporting connector to the opening of the borehole, so that the supporting plate contacts the borehole wall through the elastic connector.

[0017] As a further improvement of the present invention, the length of the support anchor rod is less than 1 meter, and the tray is square or round.

[0018] As a further improvement of the present invention, in step S3, for the new tunnel, the grouting area includes the drilled hole and the inside of the grouting mold. After the grouting is completed and the slurry solidifies, the grouting area between the two trays constitutes a surrounding rock reconstruction body to support the soft rock.

[0019] As a further improvement of the present invention, in step S3, for repairing the tunnel, the grouting area includes the cracks of the drilled holes and broken surrounding rocks. After the grouting slurry solidifies, the grouting area between the two trays constitutes a surrounding rock reconstruction body to support the soft rock, and the crack grouting reinforces the soft rock.

[0020] The beneficial effects of the present invention are as follows: the present invention excavates a new tunnel in the soft rock to form a newly excavated tunnel, or expands the original deformed soft rock tunnel to form a repaired tunnel. The tray and nut at one end of the support anchor are fixed to the inner wall of the tunnel, and modeling and grouting are performed according to the outer contour of the tunnel, and a soft rock reconstruction body is formed after solidification; or the drill rod body is sent into the borehole in the repaired tunnel and then grouting is performed, and the slurry is used to drill holes and fill gaps in muddy soft rocks. The tray and nut are installed on the other side of the support anchor, and a pre-tightening force is applied to the nut, thereby improving the bearing capacity of the reconstruction body. In the present invention, for both types of tunnels, grouting and the pre-tightening of the double-tray support anchor are used to form a more stable reconstruction body, which can effectively block the deformation pressure generated by the weak surrounding rock, thereby ensuring the normal use of the tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] Figure 1 It is a schematic diagram of the deformation process of soft rock tunnel;

[0023] Figure 2 It is a schematic diagram of the support anchor structure of the present invention;

[0024] Figure 3 It is a structural schematic diagram of the elastic support mechanism on the support anchor rod of the present invention;

[0025] Figure 4 It is a schematic diagram of the structure of anchor bolt fixing in a newly built tunnel of the present invention;

[0026] Figure 5 It is a schematic diagram of the surrounding rock reconstruction body formed after the anchor grouting in the newly built tunnel of the present invention;

[0027] Figure 6 It is a schematic diagram of the structure of anchor bolt fixation in a repaired laneway of the present invention;

[0028] Figure 7 It is a schematic diagram of the surrounding rock reconstruction body formed after the anchor grouting in the repaired roadway of the present invention;

[0029] Figure 8 is a comparison diagram of the stress of the single-tray anchor rod and the stress of the double-tray anchor rod of the present invention;

[0030] Fig. 9 It is a general schematic diagram of the surrounding rock stabilizing body supporting soft rock in the present invention;

[0031] In the figure, 1-rod body, 2-tray, 3-nut, 4-intermediate shaft, 5-support plate, 6-elastic connecting piece, 7-surrounding rock reconstruction body. DETAILED DESCRIPTION

[0032] like Figure 1 As shown, due to the existence of soft rock, when excavating a tunnel in the soft rock, that is, the tunnel, although reinforced with conventional anchor rods, the tunnel will gradually deform after a period of time, and the surrounding rock reinforcement effect is not good.

[0033] In view of the above situation, the present invention proposes a method for increasing anchor support in muddy soft rock tunnels based on surrounding rock reconstruction. Figure 2 The anchor rod shown in the figure includes a rod body 1, a tray 2 and a nut 3. The tray 2 and the nut 3 are provided at both ends of the rod body 1. The rod body 1 is provided with threads. The length of the rod body 1 is less than 1 meter. Compared with traditional anchor rods, this anchor rod is a short anchor rod. The length of the rod body 1 can be selected within 1 meter according to the strength of the weak surrounding rock. Figure 3 As shown, the anchor rod also includes an elastic support mechanism, including an intermediate shaft 4, a support plate 5 and an elastic connector 6. The intermediate shaft is cylindrical and has an internal thread. The support plate consists of two pieces and is arc-shaped. One end of the elastic connector is vertically connected to the intermediate shaft body, and the other end is connected to the inner wall of the support plate. The intermediate shaft is threadedly connected to the rod body and can rotate and move on the rod body.

[0034] Please structure Figure 4-Figure 7 The supporting method of the present invention is as follows:

[0035] Step S1: according to the engineering requirements, a new tunnel is excavated in the soft rock layer to form a newly excavated tunnel, or the thickness of the damaged surrounding rock on the tunnel surface is removed to form a repaired tunnel.

[0036] Step S2, prepare the anchor rods, install the tray 2 and the nut 3 on one side, and fix them inside the tunnel surrounding rock or damaged surrounding rock. The anchor rods are arranged along the circumference and length direction of the tunnel according to the designed spacing parameters.

[0037] Specifically, Figure 4 and Figure 5 As shown in the figure, for the new tunnel, the method of anchor bolt fixation is as follows:

[0038] Step S21, drilling a hole of a certain depth in the surrounding rock of the tunnel with a drill bit, wherein the hole diameter is larger than the maximum width of the tray; the drilling depth is 10-15% of the rod length;

[0039] Step S22, a tray is put on the inner side of the support anchor rod, a nut is installed on the outer side of the tray, and then the support anchor rod is extended into the top of the drill hole;

[0040] Step S23, rotate and move the elastic support connector to the orifice of the borehole, and the support plate contacts the borehole wall through the elastic connector. The function of the elastic support mechanism is to support the anchor rod in the borehole so that it will not fall off before grouting. During support, the distance from the center of the intermediate shaft 4 to the support plate 5 is slightly larger than the radius of the borehole. During support, the elastic connector (such as a spring or an elastic sheet) can use compression force to push the support plate against the borehole wall, thereby supporting the rod body 1. This support is very convenient for fixing the anchor rod before grouting, and does not affect grouting.

[0041] Specifically, Figure 6 and Figure 7 As shown in the figure, for the repair of the roadway, the method of fixing the anchor rod is as follows:

[0042] Step S24, drilling a hole of a certain depth on the surrounding rock of the tunnel with a drill bit, wherein the hole diameter is larger than the maximum width of the tray, and the drilling depth is 70%-80% of the rod length;

[0043] Step S25, put a tray on the inner side of the support anchor rod, install a nut on the outer side of the tray, and then extend the support anchor rod into the top of the drill hole;

[0044] Step S26, rotating and moving the elastic supporting connector to the opening of the borehole, so that the supporting plate contacts the borehole wall through the elastic connector.

[0045] Step S3: For new tunnels, build a grouting mold according to the tunnel contour, then inject grout into the grouting mold, remove the grouting mold after solidification, and expose the outer side of the anchor bolt outside the surrounding rock reconstruction body. The grouting area includes the borehole and the grouting mold. After the grouting is completed and the slurry solidifies, the grouting area between the two trays constitutes the surrounding rock reconstruction body to support the soft rock. For repaired tunnels, the grouting area includes the borehole and the cracks of the soft rock. After the grouting is completed and the slurry solidifies, the grouting area between the two trays constitutes the surrounding rock reconstruction body to support the soft rock. The crack grouting reinforces the soft rock.

[0046] Step S4: Install a tray and a nut on the outer end of the support anchor rod, then tighten the nut to apply torque to form a pre-tightening force, complete the anchoring, and form a surrounding rock reconstruction support short anchor support structure.

[0047] like Figure 8 (a) shows the reinforcement force diagram of the traditional single-tray anchor. It can be seen that the anchor stress action area is only a small part around the anchor rod body, such as Figure 8 As shown in (b), the anchor stress action area of ​​the double tray is relatively much larger. Fig. 9 It can be seen that on the wall of an integral arched tunnel, many double-support anchor rods are arranged in a matrix, and their anchoring stress action areas are superimposed, which can make the surrounding rock stabilizer more solid and its supporting force for soft rock will be stronger.

[0048] The inventive concept of the present invention focuses on effectively resisting and supporting surrounding rock deformation by increasing the firmness of the surrounding rock reconstruction body itself: by using support anchor rods to build the surrounding rock reconstruction body, on the one hand, the reconstruction body supports the soft rock outside it, and on the other hand, by applying a pre-tightening force to the support anchor rods, the bonding force between the reconstruction body and the soft rock and the firmness of the reconstruction body itself can be improved, thereby more effectively resisting tunnel deformation.

[0049] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited thereto. Various changes that can be made within the knowledge scope of technicians in the relevant technical field without departing from the spirit of the present invention are all within the protection scope of the claims of the present invention.

Claims

1. A short anchor support method for muddy soft rock tunnel based on surrounding rock reconstruction, characterized in that: The support method is based on a support anchor rod, both ends of which are provided with trays and nuts, and the rod body is provided with threads; the method comprises: Step S1: excavate a new tunnel in the soft rock layer according to the engineering requirements to form a new tunnel; or remove the thickness of the damaged surrounding rock on the surface of the tunnel to form a repair tunnel; Step S2, prepare the anchor rods, install the tray and nut on one side, and fix them inside the tunnel surrounding rock or damaged surrounding rock; arrange the anchor rods along the circumference and length direction of the tunnel according to the designed spacing parameters; Step S3, grouting is performed after building a grouting mold according to the contour of the newly excavated tunnel, or grouting is performed in the surrounding rock of the repaired tunnel through pre-arranged support anchor rods. After the grouting body is solidified, the outer side of the support anchor rod is exposed outside the surrounding rock reconstruction body; Step S4: Install a tray and a nut on the outer end of the support anchor rod, then tighten the nut to apply torque to form a pre-tightening force, complete the anchoring, and form a surrounding rock reconstruction support short anchor support structure.

2. The short anchor support method for muddy soft rock tunnel based on surrounding rock reconstruction according to claim 1 is characterized in that: The support anchor rod is also provided with an elastic support mechanism, which includes an intermediate shaft, a support plate and an elastic connecting piece. The intermediate shaft is cylindrical and has an internal thread. The support plate consists of two pieces and is arc-shaped. One end of the elastic connecting piece is vertically connected to the intermediate shaft body, and the other end is connected to the inner wall of the support plate. The intermediate shaft is threadedly connected to the rod body and can rotate and move on the rod body.

3. The short anchor support method for muddy soft rock tunnel based on surrounding rock reconstruction according to claim 2 is characterized in that: In step S2, for the new tunnel, the method of fixing the anchor bolt is as follows: Step S21, drilling a hole of a certain depth on the surrounding rock of the tunnel with a drill bit, the hole diameter being larger than the maximum width of the tray; the drilling depth of the newly excavated tunnel is 10-15% of the rod length; Step S22, putting a tray on the anchor rod, installing nuts on both the inner and outer sides of the tray, and then extending the anchor rod into the top of the drill hole; Step S23, rotating and moving the elastic supporting connector to the opening of the borehole, so that the supporting plate contacts the borehole wall through the elastic connector.

4. The short anchor support method for muddy soft rock tunnel based on surrounding rock reconstruction according to claim 2 is characterized in that: In step S2, for the repaired roadway, the method of fixing the anchor rod is as follows: Step S24, drilling a hole of a certain depth on the surrounding rock of the tunnel with a drill bit, wherein the hole diameter is larger than the maximum width of the tray, and the drilling depth is 70%-80% of the rod length; Step S25, put a tray on the inner side of the support anchor rod, install nuts on both sides of the tray, and then extend the support anchor rod into the top of the drill hole; Step S26, rotating and moving the elastic supporting connector to the opening of the borehole, so that the supporting plate contacts the borehole wall through the elastic connector.

5. The short anchor support method for muddy soft rock tunnel based on surrounding rock reconstruction according to claim 1 is characterized in that: The length of the support anchor rod is less than 1 meter, and the tray is square or round.

6. The short anchor support method for muddy soft rock tunnel based on surrounding rock reconstruction according to claim 3 is characterized in that: In step S3, for the new tunnel, the grouting area includes the drilled hole and the inside of the grouting mold. After the grouting is completed and the slurry solidifies, the grouting area between the two trays constitutes a surrounding rock reconstruction body to support the soft rock.

7. The short anchor support method for muddy soft rock tunnel based on surrounding rock reconstruction according to claim 4 is characterized in that: In step S3, for the repaired roadway, the grouting area includes the drilled hole and the cracks of the mud soft rock. After the grouting slurry solidifies, the grouting area between the two trays constitutes a surrounding rock reconstruction body to support the soft rock, and the crack grouting reinforces the soft rock.

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