CN109026031B - Reconstruction construction method for collapsed section of gas tunnel after strong earthquake - Google Patents

Reconstruction construction method for collapsed section of gas tunnel after strong earthquake Download PDF

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Publication number
CN109026031B
CN109026031B CN201810667775.2A CN201810667775A CN109026031B CN 109026031 B CN109026031 B CN 109026031B CN 201810667775 A CN201810667775 A CN 201810667775A CN 109026031 B CN109026031 B CN 109026031B
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phi
collapsed
concrete
collapse
steel
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CN109026031A (en
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苏春生
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Fifth Engineering Co Ltd of China Railway Construction Bridge Engineering Bureau Group Co Ltd
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Fifth Engineering Co Ltd of China Railway Construction Bridge Engineering Bureau Group Co Ltd
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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D9/00Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
    • E21D9/04Driving tunnels or galleries through loose materials; Apparatus therefor not otherwise provided for
    • 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
    • E21D11/04Lining 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
    • E21D11/105Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
    • 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
    • E21D11/18Arch members ; Network made of arch members ; Ring elements; Polygon elements; Polygon elements inside arches
    • E21D11/20Special cross- sections, e.g. corrugated
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D20/00Setting anchoring-bolts
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21FSAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
    • E21F13/00Transport specially adapted to underground conditions

Abstract

The invention discloses a reconstruction construction method for a collapsed section of a gas tunnel after a strong earthquake, which mainly comprises the following steps: step A, slag is discharged from a collapse cavity, and the height of a slag body is reduced until the height is 50cm above an excavation contour line; b, constructing an advanced support arch protection, and then constructing an advanced support; c, pre-embedding the concrete conveying pipe, filling slag, sealing, spraying concrete to stop grout, spraying sand to form an isolation layer, and performing advanced support grouting; d, after the sand blasting is carried out to form the isolation layer, C25 concrete is backfilled into the collapsed cavity through the pre-buried concrete conveying pipe. The invention has the advantages of effectively reducing vault load, effectively avoiding slag leakage between supports, high construction efficiency, good support effect, gas leakage prevention, lower cost and high construction safety.

Description

Reconstruction construction method for collapsed section of gas tunnel after strong earthquake
Technical Field
The invention relates to the technical field of tunnel construction, in particular to a reconstruction construction method for a collapsed section of a gas tunnel after a strong earthquake.
Background
In the existing collapse tunnel reconstruction construction, a pipe shed protection method is generally adopted to support a collapse tunnel, and then excavation and reconstruction operation of the collapse tunnel is carried out. However, in the reconstruction construction of the collapse gas tunnel in the strong earthquake area, adverse factors such as continuous aftershock, high gas concentration, extremely easy crushing of surrounding rocks, large collapse scale and the like exist, and if the tunnel reconstruction method based on the pipe shed protection is adopted, the defects of slow construction progress, low efficiency, high cost, easy leakage of gas in aftershock and easy secondary collapse of the surrounding rocks exist, so that the reconstruction construction method for the collapse section of the gas tunnel after the strong earthquake is provided for protecting the life safety of constructors to the maximum extent, accelerating the reconstruction construction progress of the collapse tunnel and reducing the reconstruction construction cost of the collapse tunnel.
Disclosure of Invention
The invention provides a reconstruction construction method for a collapsed section of a gas tunnel after a strong earthquake, which is used for rapidly, efficiently and safely reconstructing a gas collapsed tunnel based on cap protection and has the beneficial effects of high construction efficiency, short construction period, low construction cost and safe construction environment.
The invention is realized by the following technical scheme:
a construction method for reconstructing a collapsed section of a gas tunnel after a strong earthquake is characterized by further comprising the following steps:
step A, slag is discharged from a collapse cavity, and the height of a slag body is reduced until the height is 50cm above an excavation contour line;
b, constructing an advanced support arch protection, and then constructing an advanced support;
c, pre-embedding the concrete conveying pipe, filling slag, sealing, spraying concrete to stop grout, spraying sand to form an isolation layer, and performing advanced support grouting;
d, after the sand blasting is carried out to form the isolation layer, C25 concrete is backfilled into the collapsed cavity through the pre-buried concrete conveying pipe.
In the step A, after the reinforcing operation of the collapse influencing section is completed, slag is discharged from the collapse cavity, and the height of slag is reduced to a position 50cm above an excavation contour line, so that the load of the slag above a vault is reduced, and the condition of a large amount of slag leakage among advanced supports in the excavation process caused by poor grouting effect is avoided.
In the step B, the step C and the step D, pre-constructing a forepoling arch protection, then constructing a forepoling, then carrying out sand blasting isolation and grouting at the forepoling position, finally backfilling C25 concrete and enabling the backfilled C25 concrete and the forepoling to jointly form a cap-type shell to carry out integral supporting and reinforcing on the collapsed tunnel.
In order to better implement the present invention, further, the step B includes the following steps:
b1, constructing an arch protection at a collapse influence section close to a collapse section, using I22b I-shaped steel as an arch protection steel frame, enabling the steel frame spacing to be 0.5 m/beam, adopting phi 22 steel bars with the circumferential spacing of 1m to connect the steel frames longitudinally, and then adopting 4 phi 32 self-advancing type anchor rods with the length of 4m as foot locking anchor rods on the left side and the right side of each steel frame respectively;
b2, placing a guide pipe on the arch protector, wherein the guide pipe is a zinc-plated pipe with the diameter phi of 75 and the central circumferential distance of 30cm, the zinc-plated pipe is arranged in a 150-degree fan-shaped range at the arch part, the upper external insertion angle is 3 degrees, and the left external insertion angle and the right external insertion angle are 6 degrees;
b3, after the guide pipe is completely laid, spraying C20 concrete with the thickness of 30cm on the collapse influencing section to form an arch protection;
step B4., using T40 high-strength self-advancing anchor rod and phi 51 self-advancing anchor rod to make sector advance support.
In step B2, the guide tube is arranged in a sector of 150 ° so that the front support is arranged in the guide tube and then also takes a sector shape, thereby enlarging the protection area of the front support.
In order to better realize the invention, the advanced support in the step B4 adopts a T40 high-strength self-advancing anchor rod and a phi 51 self-advancing anchor rod, the construction length of each ring is 6m, the lap joint length is 1.5m, the circumferential distance is 30m, the arch parts are arranged in 150 degrees, the upper external insertion angle is 3 degrees, and the left external insertion angle and the right external insertion angle are 6 degrees; and each section of the phi 51 self-advancing anchor rod is 1m in length, the phi 51 self-advancing anchor rod is connected by adopting a screw thread connecting sleeve, phi 8 grouting holes are drilled, and the circumferential distance of the grouting holes is 5cm multiplied by the longitudinal distance of 10cm, and the grouting holes are arranged in a quincunx manner.
In order to better implement the present invention, further, the step C includes the following steps:
c1, vertically embedding concrete conveying pipes with the lengths of 3m, 9m and 3m at the left side, the middle side and the right side respectively through contact gaps of the collapsed slag and the original primary support, and after the concrete conveying pipes are embedded, spraying C20 concrete with the thickness of 20cm at the joint of the collapsed slag and the original primary support to seal and form a grout stop wall;
c2., blasting sand to form an isolation layer in the area between the forepoling and the slag body;
step C3., grouting the forepoling with 1:1 cement paste, the grouting pressure is 1.0-1.5 Mpa.
The step C2 of forming the isolation layer by sandblasting is to avoid the invasion limit caused by excessive consolidation of slag or concrete leakage, and to cut off the passage where a large amount of gas overflows to the construction work surface in the collapsed cavity, thereby ensuring the safety of the construction work.
In order to better implement the invention, further, the height of the C25 concrete backfilled by the collapsed cavity in the step D is 3 m.
In order to better implement the method, the method further comprises a step S before the step A, before the step S, the collapse influencing section is erected before the collapse cavity is subjected to deslagging, and the step S comprises the following steps:
s1, erecting a reinforcing steel frame at a collapse influence section, wherein I18I-shaped steel is adopted as the steel frame, and the distance between the steel frames is 50 cm/truss;
and S2, connecting copper between adjacent steel frames of each truss through phi 22 threaded steel bars, wherein the circumferential distance between the steel bars is 1m, and after the steel frames are connected, respectively placing 4 phi 32 self-advancing type anchor rods with the length of 4m on two sides of each steel frame to serve as foot locking anchor rods.
In the step S1, the steel frame spacing may be adjusted according to specific construction conditions.
In order to better implement the method, the method further comprises a step Z after the step D, after concrete backfilling of the collapsed cavity C25, excavating a collapsed section, primarily supporting the collapsed section and secondarily lining the collapsed section, wherein the step Z comprises the following steps:
z1., excavating the collapse section according to an upper step, a middle step and a lower step in sequence, wherein the excavation length is not more than 1m each time;
z2., after the upper pilot tunnel excavation and the initial support are finished, 1:1 cement paste pouring is needed to be carried out on two sides of the upper pilot tunnel for reinforcement by phi 42 small guide pipes, 1:1 cement paste pouring is needed to be carried out on surrounding rocks on two sides of the upper pilot tunnel for pre-reinforcement by phi 42 small guide pipes through an upper pilot tunnel arch foot before the middle pilot tunnel excavation, 1:1 cement paste pouring is needed to be carried out on the surrounding rocks on two sides of the lower pilot tunnel for pre-reinforcement by phi 42 small guide pipes through a middle pilot tunnel arch foot before the lower pilot tunnel excavation, and the grouting pressure is 1.0-1.5 Mpa;
z3. spraying C20 concrete with the thickness of 10cm on each circulating working face for sealing;
z4., adopting I22b I-shaped steel as a primary support steel frame of a collapse section, wherein the steel frames are at a distance of 50 cm/truss, the steel frames are longitudinally connected by phi 22 steel bars at an annular distance of 1m, and phi 32 self-advancing type anchor rods with the length of 4m, the annular distance of 80cm and the longitudinal distance of 50cm are respectively adopted at two sides of each steel frame as system anchor rods;
step Z5, spraying C20 concrete with the thickness of 30 cm;
step Z6., performing collapse section secondary lining on the collapse section, wherein the secondary lining main reinforcements are phi 25 reinforcements with a longitudinal distance of 20cm, the longitudinal reinforcements are phi 12 reinforcements with an annular distance of 20cm, the stirrups are phi 8 reinforcements with an annular distance of 20cm, and C20 concrete with a thickness of 70cm is sprayed after the steel reinforcement framework is built.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) according to the method, before tunnel support construction, the method of cavity collapse slag discharging and slag lowering are carried out in advance to the position 50cm above the excavation contour line, so that the load of slag bodies above the vault is reduced, and the condition of large amount of slag leakage among forepoling in the excavation process due to poor grouting effect is avoided; compared with the traditional tunnel reconstruction construction method, the method has the advantages of effectively reducing the load of the vault, effectively avoiding slag leakage between supports, and being safer and more reliable.
(2) The method realizes the advance support of the tunnel by constructing the advance support arch at the collapse influence part of the tunnel in advance, then constructing the advance sector support and performing grouting and sand blasting isolation.
(3) According to the method, after advance support is completed, C25 concrete is backfilled into the collapse cavity, the advance support and the backfilled C25 concrete form integral cap type protection, and the integral support reinforcement is carried out on the collapse tunnel, so that the integral support reinforcement of the collapse tunnel is realized, the capability of a support structure for resisting aftershock and resisting secondary collapse slag at the top of the collapse cavity is improved, and compared with the traditional collapse tunnel reconstruction method, the method has the beneficial effects of high construction efficiency, short construction period and higher safety.
Drawings
FIG. 1 is a schematic view of the construction process of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the following examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are merely illustrative of the present invention.
Example 1:
a reconstruction construction method for a collapsed section of a gas tunnel after a strong earthquake mainly comprises the following steps as shown in figure 1:
step A, slag is discharged from a collapse cavity, and the height of a slag body is reduced until the height is 50cm above an excavation contour line;
b, constructing an advanced support arch protection, and then constructing an advanced support;
c, pre-embedding the concrete conveying pipe, filling slag, sealing, spraying concrete to stop grout, spraying sand to form an isolation layer, and performing advanced support grouting;
d, after the sand blasting is carried out to form the isolation layer, C25 concrete is backfilled into the collapsed cavity through the pre-buried concrete conveying pipe.
And D, the height of C25 concrete backfilled by the collapsed cavity in the step D is 3 m.
In the step A, after the reinforcing operation of the collapse influencing section is completed, slag is discharged from the collapse cavity, and the height of slag is reduced to a position 50cm above an excavation contour line, so that the load of the slag above a vault is reduced, and the condition of a large amount of slag leakage among advanced supports in the excavation process caused by poor grouting effect is avoided.
In the step B, the step C and the step D, pre-constructing a forepoling arch protection, then constructing a forepoling, then carrying out sand blasting isolation and grouting at the forepoling position, finally backfilling C25 concrete and enabling the backfilled C25 concrete and the forepoling to jointly form a cap-type shell to carry out integral supporting and reinforcing on the collapsed tunnel.
Example 2:
the embodiment is further optimized on the basis of embodiment 1, and the step B includes the following steps:
b1, constructing an arch protection at a collapse influence section close to a collapse section, using I22b I-shaped steel as an arch protection steel frame, enabling the steel frame spacing to be 0.5 m/beam, adopting phi 22 steel bars with the circumferential spacing of 1m to connect the steel frames longitudinally, and then adopting 4 phi 32 self-advancing type anchor rods with the length of 4m as foot locking anchor rods on the left side and the right side of each steel frame respectively;
b2, placing a guide pipe on the arch protector, wherein the guide pipe is a zinc-plated pipe with the diameter phi of 75 and the central circumferential distance of 30cm, the zinc-plated pipe is arranged in a 150-degree fan-shaped range at the arch part, the upper external insertion angle is 3 degrees, and the left external insertion angle and the right external insertion angle are 6 degrees;
b3, after the guide pipe is completely laid, spraying C20 concrete with the thickness of 30cm on the collapse influencing section to form an arch protection;
step B4., using T40 high-strength self-advancing anchor rod and phi 51 self-advancing anchor rod to make sector advance support.
The advance support in the step B4 adopts a T40 high-strength self-advancing anchor rod and a phi 51 self-advancing anchor rod, the construction length of each ring is 6m, the lap joint length is 1.5m, the circumferential distance is 30m, the arch parts are arranged in 150 degrees, the upper external insertion angle is 3 degrees, and the left external insertion angle and the right external insertion angle are 6 degrees; and each section of the phi 51 self-advancing anchor rod is 1m in length, the phi 51 self-advancing anchor rod is connected by adopting a screw thread connecting sleeve, phi 8 grouting holes are drilled, and the circumferential distance of the grouting holes is 5cm multiplied by the longitudinal distance of 10cm, and the grouting holes are arranged in a quincunx manner.
The step C comprises the following steps:
c1, vertically embedding concrete conveying pipes with the lengths of 3m, 9m and 3m at the left side, the middle side and the right side respectively through contact gaps of the collapsed slag and the original primary support, and after the concrete conveying pipes are embedded, spraying C20 concrete with the thickness of 20cm at the joint of the collapsed slag and the original primary support to seal and form a grout stop wall;
step C2. sand blasting the area between the forepoling and the slag body to form an isolation layer;
step C3., grouting the forepoling with 1:1 cement paste, the grouting pressure is 1.0-1.5 Mpa.
After the collapse cavity slag is discharged, the collapse tunnel needs to be supported in advance, weak and broken surrounding rocks around the tunnel are reinforced, and the influence of secondary collapse cavity slag falling caused by aftershock on follow-up work is avoided. The method comprises the following steps that before the advance support of a collapse influencing section is carried out, advance support arch protection construction of the collapse influencing section needs to be carried out in advance, I22b I-shaped steel is used as an arch protection steel frame, self-advancing anchor rods are used on two sides of the arch protection steel frame for locking feet, guide pipes which are arranged in a sector shape are constructed after the steel frame is laid, the guide pipes are used for connection installation and guide of the following advance support, and concrete spraying is carried out to form an arch protection after the guide pipes are constructed; the guide pipe is connected with an anchor rod to form a sector advanced support, so that the support area is larger. After the advance support construction is completed, concrete spraying operation is carried out at the original initial support to form a grout stop wall, and then sand spraying is carried out in the areas below the advance support and above the slag body to form an isolation layer, so that the limit invasion caused by excessive solidification and concrete leakage of the slag body is avoided, the gas in a collapsed cavity is prevented from overflowing greatly, and the construction safety is improved. After the advance support grouting is completed, C25 concrete backfilling operation is carried out on the collapsed cavity, the backfilling height is about 3m, and after C25 concrete backfilling is carried out, the C25 concrete and the advance support form an integral cap type structure, so that the integral support reinforcement of the collapse tunnel is realized, and the capability of the support structure for resisting aftershock and resisting secondary collapsed slag at the top of the collapse cavity is improved.
In step B2, the guide tube is arranged in a sector of 150 ° so that the front support is arranged in the guide tube and then also takes a sector shape, thereby enlarging the protection area of the front support.
The step C2 of forming the isolation layer by sandblasting is to avoid the invasion limit caused by excessive consolidation of slag or concrete leakage, and to cut off the passage where a large amount of gas overflows to the construction work surface in the collapsed cavity, thereby ensuring the safety of the construction work.
The rest of this embodiment is the same as embodiment 1, and thus, the description thereof is omitted.
Example 3:
the embodiment is further optimized on the basis of the embodiment 1 or the embodiment 2, and the step a further includes a step S of erecting a collapse influencing section reinforcing steel frame before slag tapping of the collapsed cavity, where the step S includes the following steps:
s1, erecting reinforced steel frames at a collapse influence section, wherein I18I-shaped steel is adopted as the steel frames, the spacing between the steel frames is 50 cm/truss, and the spacing between the steel frames can be adjusted according to specific construction conditions;
and S2, connecting copper between adjacent steel frames of each truss through phi 22 threaded steel bars, wherein the circumferential distance between the steel bars is 1m, and after the steel frames are connected, respectively placing 4 phi 32 self-advancing type anchor rods with the length of 4m on two sides of each steel frame to serve as foot locking anchor rods.
Step D, after the concrete is backfilled into a collapsed cavity C25, excavating a collapsed section, primarily supporting the collapsed section and secondarily lining the collapsed section, wherein the step Z comprises the following steps:
z1., excavating the collapse section according to an upper step, a middle step and a lower step in sequence, wherein the excavation length is not more than 1m each time;
z2., after the upper pilot tunnel excavation and the initial support are finished, 1:1 cement paste pouring is needed to be carried out on two sides of the upper pilot tunnel for reinforcement by phi 42 small guide pipes, 1:1 cement paste pouring is needed to be carried out on surrounding rocks on two sides of the upper pilot tunnel for pre-reinforcement by phi 42 small guide pipes through an upper pilot tunnel arch foot before the middle pilot tunnel excavation, 1:1 cement paste pouring is needed to be carried out on the surrounding rocks on two sides of the lower pilot tunnel for pre-reinforcement by phi 42 small guide pipes through a middle pilot tunnel arch foot before the lower pilot tunnel excavation, and the grouting pressure is 1.0-1.5 Mpa;
z3. spraying C20 concrete with the thickness of 10cm on each circulating working face for sealing;
z4., adopting I22b I-shaped steel as a primary support steel frame of a collapse section, wherein the steel frames are at a distance of 50 cm/truss, the steel frames are longitudinally connected by phi 22 steel bars at an annular distance of 1m, and phi 32 self-advancing type anchor rods with the length of 4m, the annular distance of 80cm and the longitudinal distance of 50cm are respectively adopted at two sides of each steel frame as system anchor rods;
step Z5, spraying C20 concrete with the thickness of 30 cm;
step Z6., performing collapse section secondary lining on the collapse section, wherein the secondary lining main reinforcements are phi 25 reinforcements with a longitudinal distance of 20cm, the longitudinal reinforcements are phi 12 reinforcements with an annular distance of 20cm, the stirrups are phi 8 reinforcements with an annular distance of 20cm, and C20 concrete with a thickness of 70cm is sprayed after the steel reinforcement framework is built.
In the step Z2, after the excavation and the support of the upper pilot tunnel are completed, 1:1 cement paste needs to be poured on two sides of the upper pilot tunnel for reinforcement, 1:1 cement paste needs to be poured on surrounding rocks on two sides of the middle pilot tunnel through an arch foot of the upper pilot tunnel before the excavation of the middle pilot tunnel, 1:1 cement paste needs to be poured on surrounding rocks on two sides of the lower pilot tunnel through an arch foot of the middle pilot tunnel before the excavation of the lower pilot tunnel, and pre-grouting is performed to reinforce the surrounding rocks on two sides of the pilot tunnel so as to ensure the stability of the surrounding rocks on two sides and avoid collapse during the excavation.
The rest of this embodiment is the same as embodiment 1 or 2, and thus, the description thereof is omitted.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications and equivalent variations of the above embodiments according to the technical spirit of the present invention are included in the scope of the present invention.

Claims (6)

1. A reconstruction construction method for a collapsed section of a gas tunnel after a strong earthquake is characterized by mainly comprising the following steps:
step A, slag is discharged from a collapse cavity, and the height of a slag body is reduced until the height is 50cm above an excavation contour line;
b, constructing an advanced support arch protection, and then constructing an advanced support;
c, pre-embedding the concrete conveying pipe, filling slag, sealing, spraying concrete to stop grout, spraying sand to form an isolation layer, and performing advanced support grouting;
d, after sand blasting is carried out to form an isolation layer, backfilling C25 concrete to the collapsed cavity through a pre-buried concrete conveying pipe;
the step B comprises the following steps:
b1, constructing an arch protection at a collapse influence section close to a collapse section, using I22b I-shaped steel as an arch protection steel frame, enabling the steel frame spacing to be 0.5 m/beam, adopting phi 22 steel bars with the circumferential spacing of 1m to connect the steel frames longitudinally, and then adopting 4 phi 32 self-advancing type anchor rods with the length of 4m as foot locking anchor rods on the left side and the right side of each steel frame respectively;
b2, placing a guide pipe on the arch protector, wherein the guide pipe is a zinc-plated pipe with the diameter phi of 75 and the central circumferential distance of 30cm, the zinc-plated pipe is arranged in a 150-degree fan-shaped range at the arch part, the upper external insertion angle is 3 degrees, and the left external insertion angle and the right external insertion angle are 6 degrees;
b3, after the guide pipe is completely laid, spraying C20 concrete with the thickness of 30cm on the collapse influencing section to form an arch protection;
step B4., using T40 high-strength self-advancing anchor rod and phi 51 self-advancing anchor rod to make sector advance support.
2. The reconstruction construction method for the collapsed section of the gas tunnel after the strong earthquake according to claim 1, wherein the advanced support in the step B4 adopts a T40 high-strength self-advancing anchor rod and a phi 51 self-advancing anchor rod, the construction length of each ring is 6m, the lap joint length is 1.5m, the circumferential distance is 30m, the arch part is arranged in 150 degrees, the upper external insertion angle is 3 degrees, and the left external insertion angle and the right external insertion angle are 6 degrees; and each section of the phi 51 self-advancing anchor rod is 1m in length, the phi 51 self-advancing anchor rod is connected by adopting a screw thread connecting sleeve, phi 8 grouting holes are drilled, and the circumferential distance of the grouting holes is 5cm multiplied by the longitudinal distance of 10cm, and the grouting holes are arranged in a quincunx manner.
3. The reconstruction construction method for the collapsed section of the gas tunnel after the strong earthquake according to claim 1 or 2, wherein the step C comprises the following steps:
c1, vertically embedding concrete conveying pipes with the lengths of 3m, 9m and 3m at the left side, the middle side and the right side respectively through contact gaps of the collapsed slag and the original primary support, and after the concrete conveying pipes are embedded, spraying C20 concrete with the thickness of 20cm at the joint of the collapsed slag and the original primary support to seal and form a grout stop wall;
step C2., sand blasting in the area between the forepoling and the slag body to form an isolation layer;
step C3., grouting the forepoling with 1:1 cement paste, the grouting pressure is 1.0-1.5 Mpa.
4. The reconstruction construction method for the collapsed section of the gas tunnel after the strong earthquake as claimed in claim 1, wherein the height of C25 concrete backfilled by the collapsed cavity in the step D is 3 m.
5. The reconstruction construction method for the collapsed section of the gas tunnel after the strong earthquake according to claim 1 or 2, wherein the step A is preceded by a step S. before the collapsed cavity is tapped, the collapse influencing section is erected to form a reinforced steel frame, and the step S comprises the following steps:
s1, erecting a reinforcing steel frame at a collapse influence section, wherein I18I-shaped steel is adopted as the steel frame, and the distance between the steel frames is 50 cm/truss;
and S2, connecting adjacent steel frames of each truss through phi 22 threaded steel bars, wherein the circumferential distance between the steel bars is 1m, and after the steel frames are connected, respectively placing 4 phi 32 self-advancing type anchor rods with the length of 4m on two sides of each steel frame to serve as foot locking anchor rods.
6. The reconstruction construction method for the collapsed section of the gas tunnel after the strong earthquake as claimed in claim 1 or 2, wherein the step D is followed by the step Z of excavating the collapsed section, primarily supporting the collapsed section and secondarily lining the collapsed section after the concrete backfilling of the collapsed cavity C25 is completed, and the step Z comprises the following steps:
z1., excavating the collapse section according to an upper step, a middle step and a lower step in sequence, wherein the excavation length is not more than 1m each time;
z2., after the upper pilot tunnel excavation and the initial support are finished, 1:1 cement paste pouring is needed to be carried out on two sides of the upper pilot tunnel for reinforcement by phi 42 small guide pipes, 1:1 cement paste pouring is needed to be carried out on surrounding rocks on two sides of the upper pilot tunnel for pre-reinforcement by phi 42 small guide pipes through an upper pilot tunnel arch foot before the middle pilot tunnel excavation, 1:1 cement paste pouring is needed to be carried out on the surrounding rocks on two sides of the lower pilot tunnel for pre-reinforcement by phi 42 small guide pipes through a middle pilot tunnel arch foot before the lower pilot tunnel excavation, and the grouting pressure is 1.0-1.5 Mpa;
z3. spraying C20 concrete with the thickness of 10cm on each circulating working face for sealing;
z4., adopting I22b I-shaped steel as a primary support steel frame of a collapse section, wherein the steel frames are at a distance of 50 cm/truss, the steel frames are longitudinally connected by phi 22 steel bars at an annular distance of 1m, and phi 32 self-advancing type anchor rods with the length of 4m, the annular distance of 80cm and the longitudinal distance of 50cm are respectively adopted at two sides of each steel frame as system anchor rods;
step Z5, spraying C20 concrete with the thickness of 30 cm;
step Z6., performing collapse section secondary lining on the collapse section, wherein the secondary lining main reinforcements are phi 25 reinforcements with a longitudinal distance of 20cm, the longitudinal reinforcements are phi 12 reinforcements with an annular distance of 20cm, the stirrups are phi 8 reinforcements with an annular distance of 20cm, and C20 concrete with a thickness of 70cm is sprayed after the steel reinforcement framework is built.
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CN101781990B (en) * 2009-12-30 2011-09-28 中铁十二局集团有限公司 Construction method for dealing with tunnel collapses
CN102182472B (en) * 2011-04-02 2013-02-13 中国建筑第五工程局有限公司 Backfill repairing method for tunnel collapse cavity
CN103244149B (en) * 2013-05-16 2015-05-20 中国十七冶集团有限公司 Construction method for repairing tunnel collapse through insertion pipe grouting
CN104481550A (en) * 2014-10-23 2015-04-01 中国二十冶集团有限公司 Tunnel collapse treatment advance support method
CN105041333B (en) * 2015-07-13 2017-12-01 中铁十九局集团第二工程有限公司 It is a kind of first to fill out the method for digging method processing Tunnel Landslide afterwards
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