CN109184747B - Supporting method for deep soft rock roadway - Google Patents

Supporting method for deep soft rock roadway Download PDF

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Publication number
CN109184747B
CN109184747B CN201811245148.6A CN201811245148A CN109184747B CN 109184747 B CN109184747 B CN 109184747B CN 201811245148 A CN201811245148 A CN 201811245148A CN 109184747 B CN109184747 B CN 109184747B
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roadway
support
supporting
deformation
anchor rod
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CN109184747A (en
Inventor
罗周全
吴亚斌
张智博
秦亚光
文磊
马少维
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Central South University
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Central South University
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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/04Lining with building materials
    • E21D11/10Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/14Lining predominantly with metal
    • E21D11/15Plate linings; Laggings, i.e. linings designed for holding back formation material or for transmitting the load to main supporting members
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D20/00Setting anchoring-bolts

Abstract

The invention discloses a supporting method of a deep soft rock roadway, which comprises the following steps: 1) measuring the thickness of the loosening zone of the surrounding rock of the roadway; 2) determining the relationship between roadway deformation and creep time; 3) primary guniting support; 4) installing an anchor rod and an anchor net; 5) carrying out second guniting support; 6) mounting a circular steel bracket; 7) and backfilling the bottom of the roadway. The invention adopts a supporting method of concrete-anchor rod-anchor net-concrete-shed pipe and steel support, belongs to a rigid-flexible combined supporting structure, and can effectively improve the supporting strength and reduce the repairing times. The same supporting structure is adopted at the bottom of the roadway, and gravel backfilling is carried out, so that the supporting strength of the bottom of the roadway can be effectively improved, and the problem of bottom heave is solved; then, the invention adopts a structure of shed pipes and steel supports, the shed pipes can bear a certain deformation, the influence of long-term roadway creep deformation on the steel support structure can be avoided, and the times of support repair are reduced.

Description

Supporting method for deep soft rock roadway
Technical Field
The invention belongs to the technical field of mining engineering roadway surrounding rock supporting, and particularly relates to a supporting method for a deep soft rock roadway.
background
The soft rock is a loose, scattered, soft and weak rock stratum which has low strength, large porosity, poor cementation degree, obvious influence by cutting and weathering of a structural surface or contains a large amount of easily expandable clay minerals. In the deep bottom layer, the surrounding rock is in a high stress environment, and due to the fact that the strength of the soft rock is low, the uniaxial saturated compressive strength is also low, and the deformation and the damage of the surrounding rock are very strong, the problems that the deformation speed of the surrounding rock is high, the deformation amount is large, and the duration is long exist in the deep soft rock roadway. And with the increase of the mining depth, the increase of the ground stress of the broken rock mass and the aggravation of the intensity of the ore pressure display of the soft rock tunnel, the soft rock tunnel is seriously deformed and damaged, so that the surrounding rock of the deep soft rock tunnel is stably influenced by the multi-factor comprehensive effect, and the control difficulty of the surrounding rock is increased. At present, soft rock roadway support is still a complex technical problem in the world mining and underground engineering, deep high-stress soft rock roadway support is an important research direction, and the deep high-stress soft rock roadway support is a key technology for expanding an old mine to a deep part and mining deep resources. The buried depth of the soft rock stratum exceeds 600m, the traditional support cannot adapt to, a metal rigid support is completely destroyed, a U-shaped steel yieldable support is seriously deformed, and the low-strength anchor bolt support cannot meet the maintenance requirement of a roadway, so that the traditional support method cannot keep the roadway stable.
At present, U-shaped steel support or semicircular arch support is mostly adopted as a support method for deep soft rock, for example, methods for controlling surrounding rocks of a broken soft rock roadway are provided in a patent 201710147579.8U-shaped steel composite support structure of a deep dynamic pressure soft rock roadway and a construction method thereof and a patent 201510637612.6 closed deep and shallow coupling yielding bolting and grouting support method for a broken soft rock roadway, U-shaped steel is adopted for reinforcing and supporting, the control difficulty for deformation of the deep soft rock roadway in the horizontal direction is high, practice proves that deformation of the lateral wall of the deep soft rock roadway is the largest, U-shaped supports cannot solve the problem of deformation of the lateral wall, and roadway floor heave is more uncontrollable; if the patent 201611040176.5 discloses a method for supporting a soft rock roadway in a coal mine, the method provides a method for supporting a round roadway, solves the problem of large stress deformation of a side wall, and divides a roadway supporting bracket into 5 parts, the difficulty in repairing the deformed bracket is large after the bracket is installed, the joint of a steel bracket at the top is easily damaged due to large stress, and the bottom is inconvenient to repair due to the damage of a bottom heave. The support method does not consider the problem of creep over time of deformation support, and both support methods have certain defects.
Disclosure of Invention
The invention aims to provide a supporting method of a deep soft rock roadway with good stability of the side wall and the bottom of the roadway.
The support method for the deep soft rock roadway comprises the following steps:
1) Determining the thickness of the surrounding rock loosening zone of the roadway: after a round tunnel is excavated, testing the thickness of a surrounding rock loosening ring of the tunnel by adopting a sound wave method and double probes;
2) Determining the relationship between roadway deformation and creep time: sliding inclinometers are arranged at the top and the side walls of the roadway with the same section of the roadway to measure the relationship between the roadway displacement and the deformation time at regular time, and a creep displacement and time relationship graph of different positions of the roadway is formed;
3) Primary guniting support: high-pressure guniting is carried out on all exposed surfaces of the roadway surrounding rock to form a concrete layer, so that the soft rock is prevented from weathering, and the deformation of the surrounding rock is conveniently observed;
4) Installing an anchor rod and an anchor net: drilling an anchor rod hole on the concrete layer in the step 3), constructing and installing an anchor rod, and hanging a metal net;
5) And (5) second-time guniting support: carrying out high-pressure guniting on the metal mesh in the step 4) to form a second concrete layer so as to improve the self-stability of the surrounding rock, provide strength and rigidity for the primary supporting structure, control the deformation of the primary surrounding rock after excavation and prevent the surrounding rock from falling;
6) Mounting a circular steel bracket: processing the U-shaped steel into a circular steel support with the inner diameter matched with the diameter of the roadway, and reserving a set deformation space between the circular steel support and the second layer of the coagulation coating of the roadway; firstly, placing a tunnel bottom pipe shed, splicing and combining the steel supports, and then uniformly installing side walls and top pipe sheds around the circular support in a reserved deformation space to form a circular steel support layer;
7) Backfilling the bottom of the roadway: and backfilling the bottom of the roadway by adopting the tunneled broken stones, and pouring by using cement paste to form a backfilled broken stone cemented body at the bottom of the roadway.
In the step 3), the pressure of the high-pressure guniting is 5-8 MPa, and the thickness of the first concrete layer is 10 mm.
In the step 4), the central angle corresponding to the arc distance between the adjacent anchor rod holes is 15-20 degrees; the anchor rod is a pipe seam type anchor rod; the length of the anchor rod is 300mm greater than the depth of the loosening ring; the anchor rod and the metal net are fixed through welding.
in the step 5), the pressure of the high-pressure guniting is 5-8 MPa, and the thickness of the second concrete layer is 50 mm.
In the step 6), the circular steel support is made of U25 section steel in four sections, and the connecting areas of adjacent sections are fixed by two clamping cables; the space interval of the set deformation space is consistent with the diameter of the pipe shed; the diameter of the pipe shed is 80mm, the wall thickness of the seamless steel pipe is 6mm, the length of the seamless steel pipe is 250cm, and the linear distance between the installation pipe sheds is 20 cm.
in the step 7), the backfill height is 600-800 mm.
The invention has the beneficial effects that: the invention adopts a supporting method of concrete-anchor rod-anchor net-concrete-pipe shed + steel support, belongs to a rigid-flexible combined supporting structure, and can effectively improve the supporting strength and reduce the repairing times. Aiming at the problems that a soft rock roadway for deep mining is easy to generate bottom heaving and two side walls of the roadway are easy to slice under the action of constructional stress, the same supporting structure is adopted at the bottom of the roadway, and broken stone backfilling is carried out, so that the supporting strength of the bottom of the roadway can be effectively improved, and the problem of bottom heaving is solved; then, the invention adopts a structure of the pipe shed and the steel support, the pipe shed can bear a certain deformation, the influence of long-term roadway creep deformation on the steel support structure can be avoided, and the times of support repair are reduced.
Drawings
FIG. 1 a roadway surrounding rock structure;
FIG. 2 is a graph of creep displacement of a roadway as a function of time;
FIG. 3 is a view showing a supporting structure;
wherein: 1. a roadway; 2. loosening the ring; 3. a plastic region; 4. an elastic region; 5. an anchor rod; 6. a 10mm concrete layer; 7. anchoring the net; 8. a 50mm concrete layer; 9. a pipe shed; 10. a U25 steel bracket; 11. clamping a cable; 12-backfilling the broken stone cemented body.
Detailed Description
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
the deep soft rock round roadway supporting method comprises the following steps:
First, basic measurement
(1) Tunnel surrounding rock loosening zone thickness measurement
after a round roadway is excavated, the structure of surrounding rock is shown in fig. 1 and comprises a loose circle 1, a plastic area 2 and an elastic area 3, and the thickness Lp of the loose circle after excavation of the roadway surrounding rock is tested to be 1.6m by adopting a sound wave method and a double probe.
(2) measuring relationship between roadway deformation and creep time
And arranging a sliding inclinometer at the top and the side wall of the roadway with the same section of the roadway to measure the relationship between the roadway displacement and the deformation time at regular time. In the embodiment, as shown in fig. 2, the relationship diagram shows that the deformation of the tunnel is large in the first 20h after tunneling, and the deformation tends to be stable after 20 h. And determining a stable period of the roadway according to a relationship graph of creep displacement of the roadway and time, wherein rigid support needs to be supported before the transition to the stable period after large deformation, so that the optimal support time of the embodiment is 20-40h after roadway excavation.
Concrete supporting structure
the specific supporting structure of the invention is shown in fig. 3, and comprises the following steps:
(1) Primary guniting support
Slag is discharged after tunneling blasting, and high-pressure guniting layers are carried out on all exposed surfaces of surrounding rocks of the roadway 1 to form a 10mm concrete layer 6, wherein the guniting pressure is 5-8 MPa; the primary guniting support can prevent the soft rock from weathering and is convenient for observing the deformation of the surrounding rock.
(2) Installing an anchor rod and an anchor net:
Drilling an anchor rod hole in the concrete layer 6, wherein the depth of the anchor rod hole is more than 300mm greater than the depth of the loose ring; the central angle that the circular arc interval between the anchor rod hole corresponds is 18 (totally 20 stock in the picture), installation anchor rod 5, the length of anchor rod is generally about 200cm, after the anchor rod installation, hang anchor net 7, anchor net is the metal mesh, and its diameter is 8mm, net 80 x 80mm, length 1200mm, wide 1000mm reinforcing bar net, every two inter-sheet connection length is 80mm, anchor net 7 is fixed on anchor rod 6 through the welded mode.
(3) Secondary guniting support
and (3) performing high-pressure guniting support on the anchor net 7 again to form a 50mm concrete layer, wherein the water-cement ratio is 1:0.7, the grouting pressure is about 8Mpa, and the concrete layer 8 is used for improving the self-stability of the surrounding rock, providing strength and rigidity for the primary support structure, controlling the deformation of the primary surrounding rock after excavation and preventing the surrounding rock from falling.
(4) Mounting of circular steel bracket
The U25 shaped steel is processed into a circular steel support with the inner diameter matched with the diameter of a roadway, the circular steel support is divided into four sections, every two sections are lapped by 400mm, and a connecting area is fixed by two clamping cables.
a set deformation space is reserved between the circular steel support and the second layer of the concrete coating of the roadway; firstly, placing a pipe shed at the bottom of a roadway, installing the pipe shed 9, wherein the diameter of the pipe shed is 80mm, the wall thickness of the pipe shed is 6mm, the length of the pipe shed is 250cm, and the linear distance between the pipe sheds is 20 cm; a set deformation space is reserved between the circular steel support and the second layer of the concrete coating of the roadway; then, mounting a pipe shed in a reserved deformation space at the side wall and the top of the roadway, wherein the pipe shed is mounted on a circular support to form a circular steel support layer; the support is stressed to form a roadway supporting structure when the deformation of the roadway is stable in a short period, and the creep deformation of the roadway in a long period is offset by the deformation of the hollow pipe shed, so that the circular support can be protected, and a rigid-flexible combined supporting mode is formed.
(5) Backfilling roadway bottom
And backfilling the bottom of the roadway by adopting the tunneled gravel, and pouring by using cement paste to form a backfilled gravel cemented body 12 at the bottom of the roadway, wherein the backfilling height is 600-800 mm.

Claims (7)

1. A supporting method for a deep soft rock roadway comprises the following steps:
1) Determining the thickness of the surrounding rock loosening zone of the roadway: after a round tunnel is excavated, testing the thickness of a surrounding rock loosening ring of the tunnel by adopting a sound wave method and double probes;
2) Determining the relationship between roadway deformation and creep time: sliding inclinometers are arranged at the top and the side walls of the roadway with the same section of the roadway to measure the relationship between the roadway displacement and the deformation time at regular time, and a creep displacement and time relationship graph of different positions of the roadway is formed;
3) primary guniting support: high-pressure guniting is carried out on all exposed surfaces of the roadway surrounding rock to form a first concrete layer, so that the soft rock is prevented from weathering, and the deformation of the surrounding rock is conveniently observed;
4) installing an anchor rod and an anchor net: drilling an anchor rod hole on the concrete layer in the step 3), constructing and installing an anchor rod, and hanging a metal net;
5) and (5) second-time guniting support: carrying out high-pressure guniting on the metal mesh in the step 4) to form a second concrete layer so as to improve the self-stability of the surrounding rock, provide strength and rigidity for the primary supporting structure, control the deformation of the primary surrounding rock after excavation and prevent the surrounding rock from falling;
6) Mounting a circular steel bracket: processing the U-shaped steel into a round steel bracket with the inner diameter matched with the diameter of the roadway,
A set deformation space is reserved between the circular steel support and the second concrete layer of the roadway; firstly, placing a tunnel bottom pipe shed, splicing and combining the steel supports, and then uniformly installing side walls and top pipe sheds around the circular steel supports in a reserved deformation space to form a circular steel support layer;
7) Backfilling the bottom of the roadway: backfilling the bottom of the roadway by adopting the tunneled broken stones, and pouring by using cement paste to form a backfilled broken stone cemented body at the bottom of the roadway;
In the step 6), the circular steel support is made of U25 section steel in four sections, and the connecting areas of adjacent sections are fixed by two clamping cables; the space interval of the set deformation space is consistent with the diameter of the pipe shed.
2. The deep soft rock roadway supporting method according to claim 1, wherein in the step 3), the pressure of the high-pressure guniting is 5 ~ 8MPa, and the thickness of the first concrete layer is 10 mm.
3. The deep soft rock roadway support method according to claim 1, wherein in the step 4), the circular arc interval between the adjacent anchor rod holes corresponds to a central angle of 15 ~ 20 degrees.
4. the deep soft rock roadway support method according to claim 1 or 3, wherein in the step 4), the anchor rod is a tube seam type anchor rod; the length of the anchor rod is 300mm greater than the depth of the loosening ring; the anchor rod and the metal net are fixed through welding.
5. The deep soft rock roadway supporting method according to claim 1, wherein in the step 5), the pressure of the high-pressure guniting is 5 ~ 8MPa, and the thickness of the second concrete layer is 50 mm.
6. The deep soft rock roadway supporting method according to claim 1, wherein the pipe sheds are seamless steel pipes with the diameter of 80mm and the wall thickness of 6mm, the length of the pipe sheds is 250cm, and the linear distance between the pipe sheds is 20 cm.
7. The deep soft rock roadway support method according to claim 1, wherein in the step 7), the backfill height is 600 ~ 800 mm.
CN201811245148.6A 2018-10-24 2018-10-24 Supporting method for deep soft rock roadway Active CN109184747B (en)

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CN111779500A (en) * 2020-06-29 2020-10-16 中铁第一勘察设计院集团有限公司 Method for constructing tunnel structure

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