CN113047849B - Construction method for lining support of soft rock biased tunnel - Google Patents
Construction method for lining support of soft rock biased tunnel Download PDFInfo
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- CN113047849B CN113047849B CN202110549325.5A CN202110549325A CN113047849B CN 113047849 B CN113047849 B CN 113047849B CN 202110549325 A CN202110549325 A CN 202110549325A CN 113047849 B CN113047849 B CN 113047849B
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- 239000011435 rock Substances 0.000 title claims abstract description 110
- 238000010276 construction Methods 0.000 title claims abstract description 28
- 238000000034 method Methods 0.000 claims abstract description 26
- 238000002347 injection Methods 0.000 claims abstract description 12
- 239000007924 injection Substances 0.000 claims abstract description 12
- 239000011800 void material Substances 0.000 claims abstract description 6
- 229910000831 Steel Inorganic materials 0.000 claims description 36
- 239000010959 steel Substances 0.000 claims description 36
- 239000000463 material Substances 0.000 claims description 33
- 238000004873 anchoring Methods 0.000 claims description 30
- 238000005507 spraying Methods 0.000 claims description 15
- 230000002787 reinforcement Effects 0.000 claims description 12
- 238000009412 basement excavation Methods 0.000 claims description 11
- 239000002002 slurry Substances 0.000 claims description 9
- 238000005553 drilling Methods 0.000 claims description 8
- 230000009545 invasion Effects 0.000 claims description 8
- 238000005422 blasting Methods 0.000 claims description 6
- 239000004567 concrete Substances 0.000 claims description 6
- 238000005520 cutting process Methods 0.000 claims description 6
- 238000009434 installation Methods 0.000 claims description 6
- 229920000728 polyester Polymers 0.000 claims description 6
- 229920000642 polymer Polymers 0.000 claims description 6
- 229910001294 Reinforcing steel Inorganic materials 0.000 claims description 5
- 239000003795 chemical substances by application Substances 0.000 claims description 5
- 239000011347 resin Substances 0.000 claims description 5
- 229920005989 resin Polymers 0.000 claims description 5
- 239000011378 shotcrete Substances 0.000 claims description 5
- 239000004568 cement Substances 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- 238000003466 welding Methods 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 12
- 239000010410 layer Substances 0.000 description 22
- 230000000694 effects Effects 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 4
- 239000011398 Portland cement Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000002028 premature Effects 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- 230000000171 quenching effect Effects 0.000 description 3
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- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000000750 progressive effect Effects 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000000979 retarding effect Effects 0.000 description 2
- 239000003469 silicate cement Substances 0.000 description 2
- 239000010454 slate Substances 0.000 description 2
- 238000012876 topography Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
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- 230000003014 reinforcing effect Effects 0.000 description 1
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/001—Improving soil or rock, e.g. by freezing; Injections
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining 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
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining 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
- E21D11/105—Transport 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
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/14—Lining predominantly with metal
- E21D11/18—Arch members ; Network made of arch members ; Ring elements; Polygon elements; Polygon elements inside arches
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
- E21D20/003—Machines for drilling anchor holes and setting anchor bolts
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
- E21D20/02—Setting anchoring-bolts with provisions for grouting
- E21D20/028—Devices or accesories for injecting a grouting liquid in a bore-hole
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/20—Hydro energy
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Structural Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Soil Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Lining And Supports For Tunnels (AREA)
- Piles And Underground Anchors (AREA)
Abstract
The invention relates to an improved lining support construction method for a soft rock bias tunnel, which comprises an anchor injection combined support and a construction process of installing a front anchor and rear anchor injection combined pre-stressed anchor rod, wherein the integrity of raw rock is maintained mainly by controlling the expansion of an early loosening ring of the surrounding rock of the soft rock bias tunnel, and meanwhile, an RPC high-strength grouting pipe is provided as an effective means for the void pre-control treatment of the lining bias side surrounding rock, so that the void deformation of the bias side surrounding rock is effectively controlled, the stress condition of the tunnel support is improved, the primary support limit proportion of the tunnel is greatly reduced, and the safety of the tunnel surrounding rock support is reliably ensured.
Description
Technical Field
The invention relates to the technical field of soft rock biased tunnel construction, in particular to a soft rock biased tunnel lining support construction method.
Background
The bias phenomenon caused by topography and geological factors occurs in the soft rock tunnel construction process, and at the moment, the load acting on the surrounding rock of the tunnel has the asymmetric characteristic, so that the soft rock on the bias side is extremely easy to shear and damage, and the surrounding rock on the bias side is induced to evolve from original stable state damage to surrounding rock deformation limit invasion damage. The anchoring and grouting are the most effective engineering means for controlling the cracking deformation of the surrounding rock of the biased tunnel, and aiming at the characteristics of the biased rock stratum of the tunnel, after the rock stratum of the tunnel face is revealed, the stress is released rapidly, the initial deformation rate of the rock stratum is fast, and the early control of the expansion of the loose ring of the surrounding rock is particularly important to maintain the integrity of the original rock as much as possible.
When the bias surrounding rock is subjected to limit invasion deformation, arch changing operation is needed, the surrounding rock which is subjected to limit invasion deformation by the primary support is manually removed, the principle of removing the limit invasion surrounding rock is to reduce surrounding rock disturbance as much as possible, and large-area operation is not suitable for preventing collapse and roof collapse accidents.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides an improved lining support construction method for a soft rock biased tunnel, which comprises the following steps of anchoring and grouting combined support and installation of a combined pre-stressed anchor rod:
the anchor injection combined supporting step comprises the following steps:
grouting small guide pipes are arranged on the tunnel face of the tunnel and grouting is carried out, advanced pre-reinforcement is carried out, the diameter of each small guide pipe is 42mm, the length of each small guide pipe is 4-5 m, 2-4 steel arch centering butts and arch centering positions are respectively arranged, and the steel arch centering is locked;
the bias side surrounding rock is provided with a hollow grouting anchor rope reinforcement support, the length of the anchor rope is 10-12m, the diameter is 22mm, the longitudinal annular distance is 50-70 cm during construction, and the pretightening force of the installed anchor rope is not less than 20t; after the anchor cable is installed, combining a plurality of layers of surrounding rocks into a whole thick layer in time by using early-strength grouting material, connecting the rock mass with joint development together in series, and preventing the rock mass from sliding along a fracture surface so as to form a bearing ring with a certain thickness on the periphery of the surrounding rocks of the tunnel;
the step of installing the combined type prestress anchor rod is carried out after the step of anchoring and grouting combined supporting, and specifically comprises the following steps:
the combined prestress anchor bolt support with the front anchor and rear injection functions is adopted, an anchor bolt is quickly installed by using an anchor bolt drilling machine, the pretightening force is not lower than 10t, and the anchor bolt is anchored in place at one time; the longitudinal and circumferential arrangement spacing of the anchor bolt supports is 0.5-0.7 m, and the anchor bolts are filled and reinforced in time by using early strength grouting materials after being installed.
Specifically, the construction method further comprises the following steps:
(1) Tunnel excavation, smooth blasting
Adopting a three-step excavation method; drilling and blasting a plurality of steps simultaneously;
(2) Primary spraying operation
Firstly, performing primary spraying on the rock surface after excavation by adopting a spraying-net-spraying method, spraying C30 sprayed concrete, wherein the thickness is not less than 200mm, and the thickness is based on the condition that the whole surface is covered and a relatively flat plane closed surrounding rock can be formed; then, paving metal meshes, welding reinforcing steel bars with the diameter of phi 8mm, wherein the mesh size is 1000 multiplied by 2000mm, the mesh size is 100 multiplied by 100mm, the meshes are overlapped by 100-200 mm, the meshes are connected by a clasp, the distance between the connecting points is not more than 200mm, and finally, re-spraying concrete;
(3) Steel arch mounting
Installing H175 steel arch centering, wherein the circumferential spacing is 0.6-0.8 m; the longitudinal connection adopts phi 22 steel bars;
(4) Anchor-grouting combined support
Grouting small guide pipes are arranged on the tunnel face of the tunnel and grouting is carried out, advanced pre-reinforcement is carried out, the diameter of each small guide pipe is 42mm, the length of each small guide pipe is 4-5 m, 2-4 steel arch centering butts and arch centering positions are respectively arranged, and the steel arch centering is locked;
the bias side surrounding rock is provided with a hollow grouting anchor rope reinforcement support, the length of the anchor rope is 10-12m, the diameter is 22mm, the longitudinal annular distance is 50-70 cm during construction, and the pretightening force of the installed anchor rope is not less than 20t; after the anchor cable is installed, combining a plurality of layers of surrounding rocks into a whole thick layer in time by using early-strength grouting material, connecting the rock mass with joint development together in series, and preventing the rock mass from sliding along a fracture surface so as to form a bearing ring with a certain thickness on the periphery of the surrounding rocks of the tunnel;
(5) The step of installing the combined type prestress anchor rod is carried out after the step of anchoring and grouting combined supporting, and specifically comprises the following steps:
the combined prestress anchor bolt support with the front anchor and rear injection functions is adopted, an anchor bolt is quickly installed by using an anchor bolt drilling machine, the pretightening force is not lower than 10t, and the anchor bolt is anchored in place at one time; the longitudinal and circumferential arrangement spacing of the anchor bolt supports is 0.5-0.7 m, and the anchor bolts are filled and reinforced in time by using early strength grouting materials after being installed.
(6) Pre-buried RPC grouting pipe
Pre-burying RPC high-strength grouting pipes at the arch crown and the bias side surrounding rock, wherein the diameter phi is 36mm; the RPC grouting pipe is used as an effective means for the lining void pre-control treatment, grouting is not performed during pre-embedding, and grouting is performed in time after secondary lining pouring;
(7) Applying a buffer layer
A layer of high polymer polyester buffer layer material is applied between the primary supporting surface of the bias side surrounding rock and the molded lining, and the thickness is 200mm; the high polymer polyester buffer layer material has the characteristics of light weight, low elastic modulus and good ductility, can realize the absorption of surrounding rock stress, coordinate the integral deformation and remarkably reduce the premature stress of the molded lining.
(8) And (5) finishing lining support.
(9) When the primary support limit invasion phenomenon occurs after lining support is completed, arch replacement operation is needed, and the concrete method comprises the following steps:
(9-1) erecting temporary supports;
(9-2) loosening the impact hammer;
(9-3) cutting an RPC high-strength grouting pipe for invading the surrounding rock position;
(9-4) cutting and disassembling the anchor rod of the intrusion part;
(9-5) manually chiseling the intrusion limit surrounding rock;
(9-6) replacing the steel arch.
In addition to the method, the invention also provides a combined type prestress anchor rod, which specifically comprises an anchoring section and an anchor rod section;
the end part of the anchoring section is provided with a threaded connecting section; the threaded connection section is in threaded connection with the anchor rod section; the direction of the internal thread of the anchor rod section is opposite to the rotating direction of the combined type prestress anchor rod during installation;
the inside of the anchoring section is provided with solid steel bars, and the outside of the anchoring section is provided with a resin anchoring agent layer;
the anchor rod section is provided with a plurality of grout return holes at one end connected with the anchor section, and the grout return holes are staggered.
The combined type prestress anchor rod further comprises a base plate and a fixing nut.
And quenching one end of the anchor rod section connected with the anchoring section, and tempering at 500-650 ℃.
The invention also provides an RPC grouting pipe, which specifically comprises a plurality of stirrups arranged along the length direction of the grouting pipe and a plurality of longitudinal tie steel wires, wherein the stirrups and the longitudinal tie steel wires are embedded and fixed through RPC concrete; the wall of the RPC grouting pipe is provided with a plurality of grouting pipe grouting holes which penetrate through.
According to the anchoring and grouting process provided by the invention, the grouting material penetrates into the surrounding rock cracks while effective support is realized, the hardening is fast and early, and the surrounding rock consolidation effect is ensured. The integrity and stability of an early-stage large-deformation surrounding rock stress release layer at the initial stage after the tunnel face of the soft rock bias tunnel is excavated are effectively controlled through the field application of the soft rock tunnel in the Muzhai mountain. The invention effectively plays a role in reinforcing the limit-invasion side rock stratum, has good diffusivity and high early strength. The prestress early-strength anchoring technology provided by the invention plays an anchoring role in time, inhibits the progressive damage process of the surrounding rock, and reduces the plastic region of the surrounding rock; the effective anchoring length of the supporting system is prolonged, the contact pressure of surrounding rock and primary support is reduced, the stress condition of tunnel supporting is improved, and the primary support intrusion limit proportion of the tunnel is greatly reduced.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention.
Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:
FIG. 1 is a schematic diagram of a front-anchor rear-injection combined type prestressed anchor rod structure;
FIG. 2 is a schematic diagram of the structure in a tunnel after secondary lining pouring; wherein A is an H175 section steel arch frame, B is a combined type prestress anchor rod, C is a hollow grouting anchor cable, and D is an RPC grouting pipe;
fig. 3 is a schematic structural view of an RPC grouting pipe, wherein 11 is stirrup, 12 is RPC concrete, 13 is a longitudinal tie steel wire, 14 is a grouting pipe slurry return hole, the upper drawing is a cross-sectional view of a lower drawing grouting pipe, and the lower drawing is a schematic structural view of the grouting pipe.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.
Example 1
A front-anchoring and rear-injection combined type prestressed anchor rod comprises an anchoring section 3, an anchor rod section 7, a backing plate 8 and a fixing nut 9
The end part of the anchoring section 3 is provided with a threaded connection section 5; the threaded connection section 5 is in threaded connection with the anchor rod section 7; the direction of the internal thread of the anchor rod section 7 is opposite to the rotating direction of the combined type prestress anchor rod during installation;
the inside of the anchoring section 3 is provided with a solid reinforcing steel bar 1, and the outside is provided with a resin anchoring agent layer 2;
one end of the anchor rod section 7 connected with the anchor section 3 is provided with a slurry return hole 4, a plurality of slurry return holes 4 are arranged, and the slurry return holes 4 are staggered. The staggered slurry return holes 4 can realize uniform filling of grouting material during grouting. The diameter of the pulp return hole 4 is a round hole of 10-12 mm.
During the preparation of the anchor rod section 7, the quenching treatment is carried out at 500-650 ℃ after the quenching treatment is carried out at one end connected with the anchoring section 3. The processing can greatly adjust the performance and the material quality of the steel, not only improves the strength, but also maintains the toughness of the material, and improves the machinability of the material, thereby ensuring that the connecting section is not a weak stress part of the rod body.
The material of the resin anchoring agent layer is CK ultrafast resin anchoring agent produced by Shandong Yunhao support materials, inc.
Example 2
A construction method for soft rock bias tunnel lining support comprises the steps of anchoring and grouting combined support and installing a combined type prestressed anchor rod:
(1) Tunnel excavation, smooth blasting
Adopting a three-step excavation method; drilling and blasting a plurality of steps simultaneously;
(2) Primary spraying operation
Firstly, performing primary spraying on the rock surface after excavation by adopting a spraying-net-spraying method, spraying C30 sprayed concrete, wherein the thickness is not less than 200mm, and the thickness is based on the condition that the whole surface is covered and a relatively flat plane closed surrounding rock can be formed; then, paving metal meshes, welding reinforcing steel bars with the diameter of phi 8mm, wherein the mesh size is 1000 multiplied by 2000mm, the mesh size is 100 multiplied by 100mm, the meshes are overlapped by 100-200 mm, the meshes are connected by a clasp, the distance between the connecting points is not more than 200mm, and finally spraying C30 sprayed concrete;
(3) Steel arch mounting
Installing H175 steel arch centering, wherein the circumferential spacing is 0.6-0.8 m; the longitudinal connection adopts phi 22 steel bars;
(4) The anchor injection combined supporting step comprises the following steps:
grouting small guide pipes are arranged on the tunnel face of the tunnel and grouting is carried out, advanced pre-reinforcement is carried out, the diameter of each small guide pipe is 42mm, the length of each small guide pipe is 4-5 m, 2-4 steel arch centering butts and arch centering positions are respectively arranged, and the steel arch centering is locked;
the method comprises the steps of installing hollow grouting anchor cable reinforcement support on side surrounding rocks at a bias voltage, installing the anchor cable with the length of 10-12m and the diameter of 22mm and the longitudinal annular distance of 50-70 cm during construction, installing the anchor cable, combining a plurality of layers of surrounding rocks into an integral thick layer by using early strength grouting material, connecting the rock masses which are jointed and developed together in series, and preventing the rock masses from sliding along a fracture surface so as to form a bearing ring with a certain thickness on the periphery of a cavity;
(5) Installation combined type prestressed anchor rod
The combined prestress anchor bolt support with the front anchor and rear injection functions is adopted, an anchor bolt is quickly installed by using an anchor bolt drilling machine, the pretightening force is not lower than 10t, and the anchor bolt is anchored in place at one time; the longitudinal and circumferential arrangement spacing of the anchor bolt supports is 0.5-0.7 m, and the anchor bolts are filled and reinforced in time by using early strength grouting materials after being installed.
(6) Pre-buried RPC grouting pipe
Pre-burying RPC grouting pipes at the arch crown and the bias side surrounding rock, wherein the diameter phi is 36mm; the RPC grouting pipe is used as an effective means for the lining void pre-control treatment, grouting is not performed during pre-embedding, and grouting is performed in time after the secondary lining is poured.
The positions between the primary lining and the secondary lining of the soft rock biased tunnel, which are easy to be subjected to the void phenomenon, are mainly two parts, namely a vault and biased side surrounding rock, and the secondary lining concrete pouring process of the tunnel is to pour from the arch springing upwards to the vault, and the uncompacted vault of the lining of the tunnel is a common quality common disease; in the soft rock tunnel construction process, the soft rock on the bias side is extremely easy to cause shearing damage due to the topography and geological factors, the primary support of the bias side wall rock of the tunnel is large in deformation and easy to crack and deform, and the bias side wall rock is induced to evolve from original stable state damage to surrounding rock deformation limit invasion damage, so that the RPC high-strength grouting pipe is pre-buried at the two positions.
(7) Applying a buffer layer
A layer of high polymer polyester buffer layer material is applied between the primary supporting surface of the bias side surrounding rock and the molded lining, and the thickness is 200mm; the new thinking of the buffer layer of 'reserving deformation and yielding buffer' realizes the new supporting mode of 'rigid-flexible combination', and realizes the conditions of absorbing surrounding rock stress, coordinating integral deformation and obviously relieving premature stress of the molded lining. The buffer layer is made of HD-HC high polymer polyester material produced by Shandong Huadi building technology Co-Ltd, has the characteristics of light weight, low elastic modulus and good ductility, can realize the absorption of surrounding rock stress, coordinates the integral deformation, and remarkably reduces the premature stress of the molded lining.
(8) And (5) finishing lining support.
The grouting material in the embodiment is HDL retarding early strength grouting material produced by Shandong Huadi building technology Co. Water-cement ratio of early strength grouting material: 0.4:1, grouting pressure: initial pressure is 0.5-1.0 mpa, and final pressure is 1.5mpa.
Example 3
When the limit invasion phenomenon of the primary support occurs after the lining support is finished, the arch changing operation is needed, the invention provides a method for changing the arch after the soft rock biased tunnel lining support construction,
the specific method comprises the following steps:
(10-1) erecting temporary supports;
(10-2) loosening the impact hammer;
(10-3) cutting an RPC high-strength grouting pipe for invading the surrounding rock position;
(10-4) cutting and disassembling the anchor rod of the intrusion part;
(10-5) manually chiseling the intrusion limit surrounding rock;
(10-6) replacing the steel arch.
Application example 1
The tunnel body of the Muzhai mountain railway has 11 fracture zones which are formed in total, the maximum fault bandwidth is about 1km, the number of fault fracture zones is large, the geological conditions are complex, and the high-ground stress soft rock bias deformation is a main engineering difficulty, and the construction risk is extremely high. The maximum deformation of the soft rock core area of the traditional support system reaches 4306mm, the average deformation reaches 1500 mm-2000 mm, the tunnel of the village is a typical soft rock bias tunnel, and the tunnel is one of the tunnels with the highest difficulty in deformation control so far in China. The surrounding rock is mainly made of medium-pressure carbonized slate, has a thin-layer broken structure, and passes through a plurality of fault broken zones in a tunnel address area; the bias side surrounding rock of the inclined shaft tunnel is mainly positioned at the left side of the tunnel, and the phenomenon of primary support intrusion caused by large deformation occurs for many times in the construction process. The tunnel face is fast in deformation speed after excavation, and the steel arch frame is high in disassembling and replacing proportion.
Original supporting technology: the primary support is of a single-layer structure, and the model of the steel arch is H150. The method comprises the steps that a high-strength foot locking anchor rod is arranged on a tunnel face for advanced pre-reinforcement, the foot locking anchor rod with the diameter phi of 25mm is adopted, the length of 4m, and 2 foot locking anchor rods are respectively arranged on a steel arch support wall foot and an arch support part; the system anchor rod adopts a common hollow anchor rod, the length is 3.5m, the grouting material is silicate cement, the early stage supporting strength is very low, the early deformation effect of the control surrounding rock is poor, the system anchor rod is not suitable for supporting a soft rock biased tunnel, the original grouting material is silicate cement, the early stage strength is very low, the 1d actual measurement compressive strength is only 2-3 MPa, the flexural strength is almost 0, the grouting reinforcement effect is poor, and the deformation effect for effectively controlling the surrounding rock is not ideal. The ordinary Portland cement has poor diffusivity in the carbonaceous slate, and when the bias surrounding rock intrusion deformation occurs in the construction process, the grouting material has insufficient strength to resist the surrounding rock deformation.
The support technology after optimization: installing H175 steel arches, wherein the circumferential spacing is 0.6m; the longitudinal connection adopts phi 22 steel bars; grouting small guide pipes with the diameter phi of 42mm are arranged on the tunnel face, the length is 5m, 4 steel arch frames are respectively arranged on the bottoms of the steel arch frames and the arch frames, and the steel arch frames are locked; the bias side surrounding rock is provided with an unbonded hollow grouting anchor rope reinforcement support, the length of the anchor rope is 10m, the diameter of the anchor rope is 22mm, and the longitudinal annular distance is 60cm during construction; the system anchor rod adopts the combined prestress anchor rod support with the front anchor and rear injection functions in the embodiment 1, the anchor rod is quickly installed by using an anchor rod drilling machine, the pretightening force is 10t, and the anchor rod is anchored in place at one time; the longitudinal annular arrangement space of the anchor bolt supports is 0.6m; the grouting material is HDL retarding early strength grouting material produced by Shandong Huadi building technology Co., ltd., water cement ratio: 0.4:1, grouting pressure: initial pressure 0.5mpa, final pressure 1.5mpa; the setting time of the grouting material meets the operation requirement, the early strength effect is good, the 8h strength can reach 14MPa, the 24h compressive strength can reach 25MPa, the 24h flexural strength actual measurement value is 3MPa, and the material does not shrink after setting. The bleeding rate of the pressure is greatly reduced by actual measurement on site, which is only 1/3 of that of the ordinary Portland cement grouting material, the fineness modulus is lower than that of the Portland cement, the dispersion is easy, and the grouting reinforcement effect is greatly improved. Pre-burying RPC grouting pipes at the arch crown and the bias side surrounding rock, wherein the length is 0.6-0.8 m, and the diameter phi is 36mm; a layer of high polymer polyester buffer layer material is applied between the primary supporting surface of the bias side surrounding rock and the molded lining, and the thickness is 200mm; and (5) finishing primary lining support.
The deformation of the biased side wall rock of the optimized supporting process is greatly reduced, the deformation of the biased side wall rock is effectively controlled, and the safety of the tunnel side wall rock structure is ensured.
Application example 2
The Yu railway Muzhai Ling tunnel belongs to a typical soft rock bias surrounding rock tunnel, and the quick closure and the collapse prevention are ensured in the construction process, so that the three-step excavation method is adopted in the construction, and the construction is performed in a short step, small scale and tight closure manner. The supporting system is carried out by using the optimized supporting process in the application example 1, the method plays an anchoring role in time, and the progressive damage process of the surrounding rock is restrained, so that the plastic area of the surrounding rock is reduced; the effective anchoring length of the supporting system is prolonged, the contact pressure of surrounding rock and primary support is reduced, the stress condition of tunnel supporting is improved, and the primary support intrusion limit proportion of the tunnel is greatly reduced.
It should be noted that the curing device and the curing method in the invention have the same principle, and the related parts can be referred to each other.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (5)
1. The construction method for the soft rock biased tunnel lining support is characterized by comprising the steps of anchoring and grouting combined support and installing a combined type prestressed anchor rod: the method specifically comprises the following steps:
(1) Tunnel excavation, smooth blasting
Adopting a three-step excavation method; drilling and blasting a plurality of steps simultaneously;
(2) Primary spraying operation
Firstly, performing primary spraying on the rock surface after excavation by adopting a spraying-net-spraying method, spraying C30 sprayed concrete, wherein the thickness is not less than 200mm, and the thickness is based on the condition that the whole surface is covered and a relatively flat plane closed surrounding rock can be formed; then, paving metal meshes, welding reinforcing steel bars with the diameter of phi 8mm, wherein the mesh size is 1000 multiplied by 2000mm, the mesh size is 100 multiplied by 100mm, the meshes are overlapped by 100-200 mm, the meshes are connected by a clasp, the distance between the connecting points is not more than 200mm, and finally spraying C30 sprayed concrete;
(3) Steel arch mounting
Installing H175 steel arch centering, wherein the circumferential spacing is 0.6-0.8 m; the longitudinal connection adopts phi 22 steel bars;
(4) The anchor injection combined supporting step comprises the following steps:
grouting small guide pipes are arranged on the tunnel face of the tunnel and grouting is carried out, advanced pre-reinforcement is carried out, the diameter of each small guide pipe is 42mm, the length of each small guide pipe is 4-5 m, 2-4 steel arch centering butts and arch centering positions are respectively arranged, and the steel arch centering is locked;
the method comprises the steps of installing hollow grouting anchor cable reinforcement support on side surrounding rocks at a bias voltage, installing the anchor cable with the length of 10-12m and the diameter of 22mm and the longitudinal annular distance of 50-70 cm during construction, installing the anchor cable, combining a plurality of layers of surrounding rocks into an integral thick layer by using early strength grouting material, connecting the rock masses which are jointed and developed together in series, and preventing the rock masses from sliding along a fracture surface so as to form a bearing ring with a certain thickness on the periphery of a cavity;
(5) Installation combined type prestressed anchor rod
The combined prestress anchor bolt support with the front anchor and rear injection functions is adopted, an anchor bolt is quickly installed by using an anchor bolt drilling machine, the pretightening force is not lower than 10t, and the anchor bolt is anchored in place at one time; the longitudinal annular arrangement distance of the anchor rod supports is 0.5-0.7 m, and the anchor rods are filled and reinforced in time by using early strength grouting materials after being installed;
(6) Pre-buried RPC grouting pipe
Pre-burying RPC grouting pipes at the arch crown and the bias side surrounding rock, wherein the diameter phi is 36mm; the RPC grouting pipe is used as an effective means for the lining void pre-control treatment, grouting is not performed during pre-embedding, and grouting is performed in time after secondary lining pouring;
(7) Applying a buffer layer
A layer of high polymer polyester buffer layer material is applied between the primary supporting surface of the bias side surrounding rock and the molded lining, and the thickness is 200mm;
(8) Finishing lining support;
the combined type prestress anchor rod comprises an anchor section (3) and an anchor rod section (7);
the end part of the anchoring section (3) is provided with a threaded connection section (5); the threaded connection section (5) is in threaded connection with the anchor rod section (7); the direction of the internal thread of the anchor rod section (7) is opposite to the rotating direction of the combined prestress anchor rod during installation;
the inside of the anchoring section (3) is provided with a solid reinforcing steel bar (1), and the outside is provided with a resin anchoring agent layer (2);
one end of the anchor rod section (7) connected with the anchor section (3) is provided with a slurry return hole (4), a plurality of slurry return holes (4) are arranged in a staggered manner, and the slurry return holes (4) are arranged in a staggered manner;
water-cement ratio of early strength grouting material: 0.4:1, grouting pressure: initial pressure is 0.5-1.0 mpa, and final pressure is 1.5mpa.
2. A soft rock biased tunnel lining support construction method according to claim 1, characterized in that the combined pre-stressing anchor rod further comprises a backing plate (8) and a fixing nut (9).
3. A soft rock biased tunnel lining support construction method according to claim 1, characterized in that the end of the anchor rod section (7) connected with the anchoring section (3) is quenched and then tempered at 500-650 ℃.
4. The soft rock biased tunnel lining support construction method according to claim 1, wherein the RPC grouting pipe comprises a plurality of stirrups (11) and a plurality of longitudinal tie steel wires (13) which are arranged along the length direction of the grouting pipe, and the stirrups (11) and the longitudinal tie steel wires (13) are embedded and fixed through RPC concrete (12); a plurality of through grouting pipe slurry return holes (14) are formed in the wall of the RPC grouting pipe.
5. The construction method for soft rock biased tunnel lining support according to claim 1, wherein if the primary support limit invasion phenomenon occurs after lining support is completed, arch replacement operation is required, and the specific method comprises the following steps:
(9-1) erecting temporary supports;
(9-2) loosening the impact hammer;
(9-3) cutting an RPC high-strength grouting pipe for invading the surrounding rock position;
(9-4) cutting and disassembling the anchor rod of the intrusion part;
(9-5) manually chiseling the intrusion limit surrounding rock;
(9-6) replacing the steel arch.
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