CN114086969B - Tunnel entering construction method - Google Patents
Tunnel entering construction method Download PDFInfo
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- CN114086969B CN114086969B CN202111442821.7A CN202111442821A CN114086969B CN 114086969 B CN114086969 B CN 114086969B CN 202111442821 A CN202111442821 A CN 202111442821A CN 114086969 B CN114086969 B CN 114086969B
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- 238000010276 construction Methods 0.000 title claims abstract description 63
- 239000004567 concrete Substances 0.000 claims abstract description 34
- 238000000034 method Methods 0.000 claims abstract description 24
- 239000011435 rock Substances 0.000 claims abstract description 23
- 229910000831 Steel Inorganic materials 0.000 claims description 27
- 239000010959 steel Substances 0.000 claims description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 20
- 239000002689 soil Substances 0.000 claims description 18
- 239000010410 layer Substances 0.000 claims description 15
- 230000003014 reinforcing effect Effects 0.000 claims description 9
- 239000011378 shotcrete Substances 0.000 claims description 9
- 239000004568 cement Substances 0.000 claims description 8
- 239000002002 slurry Substances 0.000 claims description 8
- 238000004140 cleaning Methods 0.000 claims description 7
- 238000003466 welding Methods 0.000 claims description 6
- 239000004927 clay Substances 0.000 claims description 5
- 210000001503 joint Anatomy 0.000 claims description 5
- 238000004873 anchoring Methods 0.000 claims description 4
- 239000003795 chemical substances by application Substances 0.000 claims description 4
- 241001532014 Xanthorrhoea Species 0.000 claims description 3
- 238000005056 compaction Methods 0.000 claims description 3
- 238000013461 design Methods 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 3
- 239000011150 reinforced concrete Substances 0.000 claims description 3
- 230000000630 rising effect Effects 0.000 claims description 3
- 239000007921 spray Substances 0.000 claims description 3
- 239000002344 surface layer Substances 0.000 claims description 3
- 238000009415 formwork Methods 0.000 claims description 2
- 238000009966 trimming Methods 0.000 claims description 2
- 230000001681 protective effect Effects 0.000 claims 1
- 230000002035 prolonged effect Effects 0.000 abstract description 3
- 238000012544 monitoring process Methods 0.000 description 6
- 238000009412 basement excavation Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000005507 spraying Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
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- 238000009826 distribution Methods 0.000 description 2
- 238000005553 drilling Methods 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 238000011835 investigation Methods 0.000 description 2
- 235000019353 potassium silicate Nutrition 0.000 description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 2
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- 238000012986 modification Methods 0.000 description 1
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- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000002352 surface water Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012876 topography Methods 0.000 description 1
- 230000005641 tunneling Effects 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
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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
- E21D11/003—Linings or provisions thereon, specially adapted for traffic tunnels, e.g. with built-in cleaning devices
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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
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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
- 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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- 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
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A10/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE at coastal zones; at river basins
- Y02A10/23—Dune restoration or creation; Cliff stabilisation
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Architecture (AREA)
- Structural Engineering (AREA)
- Civil Engineering (AREA)
- Environmental & Geological Engineering (AREA)
- Soil Sciences (AREA)
- Lining And Supports For Tunnels (AREA)
Abstract
According to the tunnel hole entering construction method, the open cut tunnel lining section and the sleeve arch section are built in place by means of open cut construction according to the sleeve arch position, the open cut tunnel lining section at the tunnel end is not smaller than 30m, the sleeve arch section covers at least 1/2 area of the open cut tunnel lining section, C15 element concrete is backfilled to the area at the two sides of the sleeve arch to the position above the arch top for at least 2m, the slope protection area is backfilled to the area at the top of the hole and extends to the position above the hidden hole, so that the slope protection area can be better protected, stability of broken rock bodies in the tunnel construction process and the using process is improved, meanwhile, the sleeve arch section is prolonged to cover the open cut tunnel lining longer area, the open cut tunnel lining section is reinforced, supporting strength and structural stability of the tunnel hole entering area are improved, meanwhile, the extending range of the slope protection area formed by backfilling above the reinforced hole section is wider, and influence degree of broken rock bodies on the tunnel construction process and the using process is reduced.
Description
Technical Field
The invention relates to the technical field of tunnel construction, in particular to a tunnel entering construction method.
Background
The tunnel entering construction is a starting point of tunnel engineering, and is related to the quality of subsequent construction, for the entering construction of a region with poor stability of a downhill rock mass of a tunnel opening, due to uneven distribution thickness of a fully weathered and strongly weathered layer, larger gradient, easy collapse of the rock mass when encountering water, easy formation of shallow engineering collapse or collapse during excavation, influence on the tunnel entering construction, extremely crushing of the rock mass in a region below a tunnel inverted arch, poor stability, influence on the stability of the subsequent construction and the use process of the tunnel, and therefore, in the actual construction process, corresponding pre-treatment measures are needed for the tunnel entering, so that the smooth and safe execution of the tunnel entering is ensured, but the existing treatment measures are imperfect, the influence on the crushing degree of surrounding rock mass is easy to happen after the tunnel entering construction is finished, and the smooth execution of the subsequent construction and the safety stability of the tunnel entering region are influenced.
Therefore, in the tunnel entering construction process, how to reduce the influence of broken rock mass on the construction process and reduce the risk of tunnel entering becomes the technical problem to be solved urgently.
Disclosure of Invention
The invention aims at: aiming at the problems in the background technology, the tunnel entering construction method is provided.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a tunnel entering construction method comprises the following steps: s1: cleaning slope surface, namely cleaning surface soil, shrubs and hillside dangerous stones which collapse above and beside the tunnel portal, and excavating all collapsed soil; s2, constructing a water interception gutter: forming a groove at a position which is not smaller than 5m away from the slope bevel line, tamping, pouring 25-35cm thick groove bottom concrete in the groove, installing a groove body template next day, pouring groove body concrete, and forming a water interception gutter; s3, performing side elevation slope protection: leveling the slope, excavating a side elevation slope area step by step, supporting step by step, excavating the slope area at each level with the height not exceeding 1.5m, and excavating in place in one step according to the set arch lofting position; s4, constructing a sleeve arch section: applying a sleeve arch section outwards along the side of the blind tunnel, wherein the sleeve arch section covers at least 1/2 of the longitudinal area of the open cut tunnel lining section; s5, performing advanced pipe shed support: forming a pipe shed hole, grouting and forming an advance pipe shed support; s6, constructing an open cut tunnel lining section: adopting in-situ construction, full section and integral reinforced concrete lining, wherein the open cut tunnel lining section is not less than 30m and the thickness is not less than 60cm, one end of the open cut tunnel lining section is used as a tunnel portal end wall, and the other end is connected with a hidden tunnel lining side rock face; s7, backfilling a construction open cut tunnel: and backfilling C15 plain concrete to at least 2m above the arch crown in the areas at two sides of the arch, after the design strength is reached, sequentially backfilling gravels, a water-proof clay layer with the thickness of not less than 50cm and seed soil with the thickness of not less than 30cm in the area at the top of the opening by adopting a mode of layering compaction and not more than 30cm, planting grass trees on the surface layer, forming a slope protection area gradually rising along the side wall of the opening to the side of the blind hole, and extending and covering the protection area above the blind hole.
According to the tunnel hole entering construction method, the open cut tunnel lining section and the cover arch section are built in one step according to the position of the cover arch, the side slope area can be better protected, the stability of broken rock mass in the tunnel construction process and the use process is improved, meanwhile, the cover arch section is prolonged to cover the longer area of the open cut tunnel lining, the open cut tunnel lining section is reinforced, the supporting strength and the structural stability of the tunnel hole entering area are improved, meanwhile, the slope protection area formed by backfilling above the extended and reinforced tunnel hole section is wider in extension range, and the influence degree of the broken rock mass on the tunnel construction process and the use process is reduced.
As a preferable scheme of the invention, arch protection foundations are respectively arranged on two sides of an arch springing of the open cut tunnel lining section, and the arch protection foundations are all formed by casting C35 concrete into a cube structure and are used for counteracting vault pressure, and the bottom of each arch protection foundation is at least 1m lower than the bottom of an inverted arch.
As the preferable scheme of the invention, the open cut tunnel lining section is divided into two sections for lining construction, one section extends from the end wall of the tunnel portal to the lofting position of the end surface of the sleeve arch, and the other section and the sleeve arch are synchronously constructed and extend to be capable of being in butt joint connection with the hidden tunnel lining.
As a preferable scheme of the invention, I22b I-steel is adopted for the arch ring, the longitudinal distance is 50cm, the thickness of the arch ring is not less than 60cm, and the arch protection foundation and the arch ring steel structure are welded through a 10mm thick steel plate.
As a preferable scheme of the invention, the sleeve arch section adopts a multi-arch frame assembly mode, the 1 st arch frame close to the hidden hole side is welded with a longitudinal anti-tilting anchor rod pre-installed at the arch frame after the construction is completed, and the circumferential position of the lofting guide tube is measured and marked on the arch frame after the construction of all the arch frames is completed.
As a preferred embodiment of the present invention, S4 specifically includes the following steps: s4.1: c15 concrete foundation with length, width and height of 200 multiplied by 70 multiplied by 100cm is longitudinally poured at the arch frame footing position according to the tunnel so as to prevent the arch frame from sinking; s4.2: dividing the arch steel arch frame into 7 standard units, processing the standard units in sections, assembling the standard units from bottom to top, and installing the standard units from inside to outside along the side of the blind hole to the open cut tunnel; s4.3: a plurality of guide pipes are arranged on the outer side surface of the arch frame, the guide pipes extend to the rock surface along the longitudinal direction of the tunnel, a pouring template is coated outside the arch frame, and a lower supporting system is made through the steel arch frame; s4.4: and symmetrically pouring the formed sleeve arch ring from the footings at two sides of the arch frame.
In S2, drainage of the water interception gutter and drainage of roadbed side gutters at two sides are connected, the water interception gutter performs curing work after concrete pouring, and the coverage curing period is not less than 7 days.
As a preferred scheme of the invention, the S3 specifically comprises the following steps: s3.1: digging out surface soil and virtual soil of the landslide of the upward slope surface; s3.2: c25 sprayed concrete with the thickness of 4cm is sprayed initially; s3.3: constructing a hollow grouting anchor rod, wherein the hollow grouting anchor rod adopts a grouting hole with phi of 110mm, a grouting steel flower pipe with phi of 50 multiplied by 4.5mm, the length of 4m, and plum blossom type arrangement with the length of 1.5mmultiplied by 1.5m or 1.0mmultiplied by 1.0 m; s3.4: after the anchor rod is installed, installing a reinforcing mesh, attaching the reinforcing mesh to the surface of the primary sprayed concrete, welding the reinforcing mesh with the tail part of the anchor rod, and plugging a gap between the pipe wall and the primary sprayed concrete by adopting an early strength anchoring agent; s3.5: grouting the hollow grouting anchor rod with 42.5-level cement slurry; s3.6: and C25 spray concrete with the thickness of not less than 10cm is sprayed repeatedly.
As a preferred scheme of the invention, in the open cut tunnel concrete construction process, connecting ribs are pre-buried and used for being connected with the tunnel portal end wall concrete, after the open cut tunnel lining is disassembled, an open cut tunnel waterproof layer is applied, and the open cut tunnel waterproof layer is welded with a reserved exposed section lap welding area of the hidden cut tunnel waterproof layer.
As a preferable scheme of the invention, the tunnel grouting is carried out at least 14 days after the tunnel grouting is completed, so that the tunnel tunneling and supporting operation is carried out.
In summary, due to the adoption of the technical scheme, the beneficial effects of the invention are as follows:
1. according to the sleeve arch position, the open cut tunnel lining section and the sleeve arch section are built in a one-step excavation in place by adopting an open cut construction mode, so that a side elevation slope area can be better protected, and the stability of broken rock mass in the tunnel construction process and the use process is improved;
2. the sleeve arch section is prolonged to cover a longer area of open cut tunnel lining, the open cut tunnel lining section is reinforced, and the supporting strength and the structural stability of a tunnel entering area are improved;
3. the slope protection area formed by backfilling above the extended and reinforced tunnel portal section has wider extension range, and reduces the influence degree of broken rock mass on the tunnel construction process and the use process.
Drawings
FIG. 1 is a schematic flow chart of a tunnel entering construction method of the invention;
FIG. 2 is a schematic longitudinal section of a tunnel portal segment according to example 1;
FIG. 3 is a schematic diagram of a cross section of a tunnel open cut tunnel lining segment in example 1;
FIG. 4 is a schematic diagram II of a cross section of a tunnel open cut tunnel lining segment in example 1;
fig. 5 is a schematic top protection view of a tunnel portal segment in example 1.
Icon:
1-open cut tunnel lining, 2-arch, 3-tunnel gate end wall, 4-water cut gutter, 5-open cut tunnel backfill, 6-C15 plain concrete, 7-arch protection foundation and 8-cut line of the light and dark tunnel.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings.
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Example 1
Taking the tunnel entering construction of a certain tunnel in southwest area of China as an example, geological investigation is carried out before construction, and the tunnel is found to be built in a mountain hilly landform area, multiple steep slopes and large topography fluctuation and belongs to a nonuniform foundation, a tunnel opening section is V-level surrounding rock, a rock soil layer at the tunnel opening is mainly composed of residual clay and full-strong weathered sandstone, the residual clay and the full-weathered sandstone are loose in structure and are easy to soften and disintegrate when meeting water, the lower strong weathered sandstone rock is extremely broken, the distribution thickness of the full-weathered and strong weathered layers is uneven, the gradient is larger, so that the stability of the tunnel opening upward slope rock is poor, shallow engineering slump or collapse is easy to form when excavation, and the on-site observation condition shows that the ground surface monitoring data key monitoring items are as follows: surface subsidence and slippage; the key monitoring items in the hole are as follows: the arch top in the hole is sunk, the periphery is converged, the primary support curve is deformed, corresponding monitoring equipment is arranged according to the conditions of each key monitoring project, and a monitoring and measuring scheme meeting the field construction requirement is assembled by combining the related specification requirements.
As shown in fig. 1, a tunnel entering construction method in this embodiment includes the following specific steps:
s1: cleaning a slope: and (3) cleaning surface soil, shrubs and hillside dangerous stones which collapse above and beside the tunnel portal, excavating all collapsed soil bodies, and increasing the amount of excavated soil and stones by at least 45 m < 3 > compared with the tunnel construction of the same type.
S2, constructing a water interception gutter: and (3) constructing a groove at a position 5m away from the slope bevel line, tamping, pouring 30cm thick groove bottom concrete in the groove, installing a groove body template the next day, and pouring groove body concrete to form the water interception gutter.
Specifically, the water interception gutter is connected with the drainage of the roadbed side ditches at the two sides in sequence, so that the direct flushing of structural objects or the pollution of water and soil are avoided, the anchor spraying is adopted for supporting when the slope excavation of the water interception gutter is unstable, the water interception gutter performs the curing work after concrete pouring, and the covering curing period is not less than 7 days.
S3: and (3) performing slope protection: and (3) before the hole construction, trimming the slope, excavating a side elevation slope area step by step, excavating the side elevation slope area at each stage with the height not exceeding 1.5m, and excavating the slope area according to the set arch lofting position by adopting a mode of retaining core soil until the open cut construction space meets the construction of open cut lining sections and set arch sections.
Preferably, the slope protection at the opening adopts a grade 2 slope, and the grade 1 slope rate is 1:1.25, height 10 meters; the second-level slope rate is 1:3, the height is 10 meters.
Preferably, S3 specifically includes the following steps: s3.1: digging out surface soil and virtual soil of the landslide of the upward slope surface; s3.2: c25 sprayed concrete with the thickness of 4cm is sprayed initially; s3.3: constructing a hollow grouting anchor rod, wherein the hollow grouting anchor rod adopts a grouting hole with phi of 110mm, a grouting steel flower pipe with phi of 50 multiplied by 4.5mm, the length of 4m, and plum blossom type arrangement with the length of 1.5mmultiplied by 1.5m or 1.0mmultiplied by 1.0 m; s3.4: after the anchor rod is installed, installing a reinforcing mesh, attaching the reinforcing mesh to the surface of the primary sprayed concrete, welding the reinforcing mesh with the tail part of the anchor rod, and plugging a gap between the pipe wall and the primary sprayed concrete by adopting an early strength anchoring agent; s3.5: grouting the hollow grouting anchor rod with 42.5-level cement slurry; s3.6: and C25 spray concrete with the thickness of not less than 10cm is sprayed repeatedly.
Specifically, pit on the surface of the top of the hole is filled and subjected to surface water seepage prevention treatment, after the collapsed soil body is completely removed, grouting protection is carried out on the side slope area in time, the investigation of slope seepage and water penetration points is carried out before the primary concrete spraying, drainage measures are adopted in time, the spraying concrete is not blocked by the water pipe orifice, and specific parameters can be adaptively adjusted according to actual construction conditions.
S4: and (3) constructing a sleeve arch section: and (5) applying a sleeve arch section outwards along the side of the blind tunnel, wherein the sleeve arch section covers at least 1/2 of the longitudinal area of the open cut tunnel lining section.
S6: and (3) constructing an open cut tunnel lining section: the open cut tunnel lining section is constructed in situ, is full-section and is integrally reinforced concrete lined, the thickness of the open cut tunnel lining section is not less than 30m, the thickness of the open cut tunnel lining section is not less than 60cm, one end of the open cut tunnel lining section is used as a tunnel portal end wall, and the other end of the open cut tunnel lining section is connected with a hidden tunnel lining side rock face.
Specifically, as shown in fig. 2, in this embodiment, the open cut tunnel lining section is divided into two sections for lining construction. One section of pile number is K0+575~ K0+588, and length is 13m, extends to the cover arch terminal surface lofting position from the door end wall, and the vault does not have the arch arrangement, and another section of pile number is K0+588~ K0+605, length is 17m, and the synchronous construction of cover arch to extend to can be connected with dark tunnel lining butt joint, open cut tunnel lining adopts C35 concrete, and thickness all reaches 60cm.
Specifically, as shown in fig. 3-4, in this embodiment, arch protection foundations are respectively disposed on two sides of the arch feet of the open cut tunnel lining, and are all formed by casting C35 concrete into a cube structure, so as to offset vault pressure, protect an arch ring, wherein the bottom of the arch protection foundations is at least 1m lower than the bottom of an inverted arch, the size of the arch protection foundations of sections K0+575-K0+598 is 3.1mx 4.15mx 23m, and the size of the arch protection foundations of sections K0+598-K0+603 is 3.0mx 4.15mx 5m, so that the bearing capacity of the arch protection foundations of two sections of the open cut tunnel lining is not less than 350kPa, the effect of offsetting vault pressure is better, the integrity of the open cut tunnel lining is improved, and the use effect is better.
Specifically, in the open cut tunnel concrete construction process, pre-buried connecting ribs are used for being connected with the tunnel portal end wall concrete, so that the tunnel portal end wall concrete can be tightly attached to the wall after pouring, after the open cut tunnel lining is removed from a formwork, an open cut tunnel waterproof layer is applied, and the open cut tunnel waterproof layer is welded with a reserved exposed section lap welding area of the hidden cut tunnel waterproof layer.
Specifically, as shown in fig. 4, S4 includes the following steps: s4.1: c15 concrete foundation with length, width and height of 200 multiplied by 70 multiplied by 100cm is longitudinally poured at the arch frame footing position according to the tunnel so as to prevent the arch frame from sinking; s4.2: the method comprises the steps of dividing a sleeve arch steel arch frame into 7 standard units, processing the standard units in sections, assembling the standard units from bottom to top, installing the standard units from inside to outside along the side of a dark tunnel to the open cut tunnel, ensuring the accuracy of a central line and a normal line when the sleeve arch section arch frame is installed, ensuring that the installation error is within an allowable error range, ensuring that the sleeve arch section arch frame is unbiased, front prone and back prone, and checking the clearance of the arch frame; s4.3: a plurality of guide pipes are arranged on the outer side surface of the arch frame, the guide pipes extend to the rock surface along the longitudinal direction of the tunnel, a pouring template is arranged outside the arch frame in a coating mode, the template takes a pine board as a main part, a light panel is arranged on the inner mould, and a lower supporting system is formed by the steel arch frame; s4.4: and symmetrically pouring the formed sleeve arch ring from the footings at two sides of the arch frame.
Specifically, I22b I-steel is adopted for the arch ring, the longitudinal distance is 50cm, the thickness of the arch ring is 60cm, and the arch protection foundation and the arch ring steel structure are welded through a 10mm thick steel plate.
Specifically, the sleeve arch section is formed by adopting a plurality of arch frames in an assembling mode, the 1 st arch frame close to the hidden hole side is welded with a longitudinal anti-tilting anchor rod pre-installed at the arch frame after being arranged, all the steel arch frames are arranged, the circumferential position of a lofting guide pipe is measured, and the hoop position is marked on the steel arch frames.
Preferably, in this embodiment, the sleeve arch section is performed in two sections, wherein one section is close to the side of the blind hole, the construction is performed for 2m, after the construction of the sleeve arch section is completed, the construction of the advance pipe shed support is performed, and after the construction of the advance pipe shed support, the sleeve arch section is extended towards the open cut tunnel lining side without the protection arch for the remaining 15m.
Specifically, the method comprises the following steps of S5: and (3) performing support of a forepoling shed: and (5) performing hole grouting on the pipe shed to form the advanced pipe shed support.
Specifically, S5, drilling by adopting a crawler-type down-the-hole drill, drilling by adopting a mode of separating the jump drill, numbering the pipe shed holes, preventing disturbance from collapsing the holes, performing a hold down test before grouting, determining proper grouting effect, grouting pressure, grouting flow and grouting quantity, enabling grouting parameters to be suitable for actual surrounding rock, and adopting sequential, backward and symmetrical grouting from bottom to top.
Specifically, in this embodiment, the slurry is 42.5 grade cement paste, and the cement paste cement ratio is 1:1, the water glass concentration is 35 Baume degrees, the water glass modulus is 2.4, the initial pressure of grouting pressure is 0.5-1.0 MPa, the final pressure is 2.0MPa, the pressure stabilizing time is 1-5 minutes, and the grouting pressure is controlled according to a graded boosting method; the slurry diffusion radius is not less than 0.6m, and in order to meet the requirement of the slurry diffusion radius, the setting time is adopted in the embodiment as follows: the general section is 3min, the water-rich section is 1-2 min, the grouting mode adopts orifice grouting, before grouting, firstly, the steel pipe with orifice of 1.5-2 m is solidified with the hole wall by using anchoring agent to prevent slurry leakage, then the steel pipe is sealed, and a steel pipe connected with the grouting pipe is welded at the port of the steel pipe.
Preferably, a pipe shed is processed by adopting phi 108 mm seamless pipes, the number of pipe shed joints on the same section is not more than 50%, all pipe joints are classified, grouped and stored, the front end of each pipe shed is in a pointed cone shape when a steel pipe is constructed, phi 10 stiffening hoops are welded at the tail part, phi 15mm grouting holes are alternately drilled around the pipe wall, surrounding rocks are driven into along the periphery of a tunnel at an external insertion angle of 0.5-2 degrees (with an included angle of a longitudinal slope line), the holes are flat and smooth, compressed air is adopted for cleaning after the holes are drilled, then the pipe shed is installed, and a slurry stop valve is welded at the tail end of the pipe shed.
Specifically, the tunnel excavation supporting operation is carried out after the grouting of the pipe shed is completed for at least 14 days.
S7: backfilling a construction open cut tunnel: and backfilling C15 plain concrete to at least 2m above the arch crown in the areas at two sides of the arch, after the design strength is reached, sequentially backfilling gravels, a water-proof clay layer with the thickness of not less than 50cm and seed soil with the thickness of not less than 30cm in the area at the top of the opening by adopting a mode of layering compaction and not more than 30cm, planting grass trees on the surface layer, forming a slope protection area gradually rising along the side wall of the opening to the side of the blind hole, and extending and covering the protection area above the blind hole.
Specifically, in order to further ensure the stability of the side elevation slope region and improve the reinforcement effect of the side elevation slope region, common grass planting protection is adopted for the 10m (K0+600-K0+610) above the tunnel, anchor spraying protection and vine planting protection are adopted for the side elevation slope of K0+610-K0+620, phi 50 multiplied by 4.5cm hollow grouting anchor rods are adopted for the anchor rods, the length is 4m, and the construction interval is 100 multiplied by 100cm; the size of the reinforcing steel bar mesh of the phi 8 reinforcing steel bar mesh support is 20cm multiplied by 20cm, and the thickness of the sprayed C25 concrete support is at least 10 cm; for K0+620-K0+657, grouting steel flowtube protection is adopted, a phi 50 multiplied by 4.5cm hollow grouting anchor rod is adopted as the steel flowtube, quincuncial arrangement with the application spacing of 150 multiplied by 150cm is adopted, 42.5-level cement paste is adopted as the grouting of the hollow grouting anchor rod, and the water-cement ratio is 0.35: 1-0.38: 1, forming a hole top protection diagram as shown in fig. 5.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (8)
1. The tunnel entering construction method is characterized by comprising the following steps of:
s1: cleaning slope surface, namely cleaning surface soil, shrubs and hillside dangerous stones which collapse above and beside the tunnel portal, and excavating all collapsed soil;
s2, constructing a water interception gutter: forming a groove at a position which is not smaller than 5m away from the slope bevel line, tamping, pouring 25-35cm thick bottom concrete into the groove, installing a groove body template next day, pouring groove body concrete, and forming a water interception gutter;
s3, performing side elevation slope protection: trimming and leveling the slope, excavating a side elevation slope area step by step, supporting step by step, excavating each stage until the height is not more than 1.5m, and excavating in place in one step by adopting a mode of retaining core soil according to the lofting position of the sleeve arch until the open cut construction space for constructing the open cut lining section and the sleeve arch section is met;
s4, constructing a sleeve arch section: the method comprises the steps of (1) outwards applying a sleeve arch section along a dark hole side, wherein the sleeve arch section can cover at least 1/2 area of the open cut tunnel lining section in the longitudinal direction, one section is close to the dark hole side, applying 2m, applying a forepoling shed support after the sleeve arch section is applied, extending the sleeve arch section for 15m towards the open cut tunnel lining side without a protective arch after the forepoling shed support is applied, performing lining construction by dividing the open cut tunnel lining section into two sections, wherein one section extends from a tunnel door end wall to a sleeve arch end face lofting position, and synchronously constructing the other section and the sleeve arch and extending to be capable of being in butt joint with the dark cut tunnel lining;
s5, performing advanced pipe shed support: forming a pipe shed hole, grouting and forming an advance pipe shed support;
s6: and (3) constructing an open cut tunnel lining section: adopting local construction, full section and integral reinforced concrete lining, wherein the open cut tunnel lining section is not less than 30m, the thickness is not less than 60cm, one end of the open cut tunnel lining section is used as a tunnel portal end wall, the other end is connected with a hidden tunnel lining side rock face, arch protection foundations are respectively arranged on two sides of an arch foot of the open cut tunnel lining section, the arch protection foundations are all cast into a cube structure by adopting C35 concrete and are used for counteracting vault pressure, and the bottom of the arch protection foundations is at least 1m lower than the bottom of an inverted arch;
s7, backfilling a construction open cut tunnel: and backfilling C15 plain concrete to at least 2m above the arch crown in the areas at two sides of the arch, after the design strength is reached, sequentially backfilling gravels, a water-proof clay layer with the thickness of not less than 50cm and seed soil with the thickness of not less than 30cm in the area at the top of the opening by adopting a mode of layering compaction and not more than 30cm, planting grass trees on the surface layer, forming a slope protection area gradually rising along the side wall of the opening to the side of the blind hole, and extending and covering the protection area above the blind hole.
2. The tunnel entering construction method as claimed in claim 1, wherein the arch ring is I22b I-steel, the longitudinal distance is 50cm, the thickness of the arch ring is not less than 60cm, and the arch protection foundation and the arch ring steel structure are welded by a 10mm thick steel plate.
3. The tunnel entering construction method as claimed in claim 1, wherein the sleeve arch section is formed by assembling a plurality of arches, the 1 st arch near the hidden hole side is welded with a longitudinal anti-tilting anchor rod pre-installed at the arch after the arch is built, and the circumferential position of the lofting guide tube is measured and marked on the arch after the arch is built.
4. The tunnel entering construction method as claimed in claim 1, wherein S4 specifically comprises the steps of:
s4.1: c15 concrete foundation with length, width and height of 200 multiplied by 70 multiplied by 100cm is longitudinally poured at the arch frame footing position according to the tunnel so as to prevent the arch frame from sinking;
s4.2: dividing the arch steel arch frame into 7 standard units, processing the standard units in sections, assembling the standard units from bottom to top, and installing the standard units from inside to outside along the side of the blind hole to the open cut tunnel;
s4.3: a plurality of guide pipes are arranged on the outer side surface of the arch frame, the guide pipes extend to the rock surface along the longitudinal direction of the tunnel, a pouring template is coated outside the arch frame, and a lower supporting system is made through the steel arch frame;
s4.4: and symmetrically pouring the formed sleeve arch ring from the footings at two sides of the arch frame.
5. The tunnel entrance construction method according to claim 1, wherein in the step S2, drainage of the water interception gutter and the roadbed side gutters at two sides is connected, the water interception gutter performs curing work after concrete pouring, and the coverage curing period is not less than 7 days.
6. The tunnel entering construction method as claimed in claim 1, wherein S3 comprises the steps of:
s3.1: digging out surface soil and virtual soil of the landslide of the upward slope surface;
s3.2: c25 sprayed concrete with the thickness of 4cm is sprayed initially;
s3.3: constructing a hollow grouting anchor rod, wherein the hollow grouting anchor rod adopts a grouting hole with phi of 110mm, a grouting steel flower pipe with phi of 50 multiplied by 4.5mm, the length of 4m, and plum blossom type arrangement with the length of 1.5mmultiplied by 1.5m or 1.0mmultiplied by 1.0 m;
s3.4: after the anchor rod is installed, installing a reinforcing mesh, attaching the reinforcing mesh to the surface of the primary sprayed concrete, welding the reinforcing mesh with the tail part of the anchor rod, and plugging a gap between the pipe wall and the primary sprayed concrete by adopting an early strength anchoring agent;
s3.5: grouting the hollow grouting anchor rod with 42.5-level cement slurry;
s3.6: and C25 spray concrete with the thickness of not less than 10cm is sprayed repeatedly.
7. The tunnel entrance construction method of claim 1, wherein in the open cut tunnel concrete construction process, connecting ribs are pre-embedded and used for being connected with the end wall concrete of the tunnel door, after the open cut tunnel lining is removed from the formwork, an open cut tunnel waterproof layer is applied, and the open cut tunnel waterproof layer is welded with a welding area where an exposed section reserved by the hidden cut tunnel waterproof layer is lapped.
8. A tunnel boring method according to claim 1, wherein the tunnel boring support is carried out at least 14 days after grouting of the pipe shed is completed.
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