CN109681212B - Excavation construction method of small-section loess tunnel - Google Patents
Excavation construction method of small-section loess tunnel Download PDFInfo
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- 238000009412 basement excavation Methods 0.000 title claims abstract description 39
- 238000010276 construction Methods 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 claims abstract description 28
- 229910000831 Steel Inorganic materials 0.000 claims description 39
- 239000010959 steel Substances 0.000 claims description 39
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- 238000005553 drilling Methods 0.000 claims description 9
- 230000002787 reinforcement Effects 0.000 claims description 7
- 239000004576 sand Substances 0.000 claims description 7
- 230000003014 reinforcing effect Effects 0.000 claims description 6
- 238000005507 spraying Methods 0.000 claims description 4
- 229910001294 Reinforcing steel Inorganic materials 0.000 claims description 3
- 239000004568 cement Substances 0.000 claims description 3
- 239000010881 fly ash Substances 0.000 claims description 3
- 239000011440 grout Substances 0.000 claims description 3
- 235000019353 potassium silicate Nutrition 0.000 claims description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 3
- CZDYPVPMEAXLPK-UHFFFAOYSA-N tetramethylsilane Chemical compound C[Si](C)(C)C CZDYPVPMEAXLPK-UHFFFAOYSA-N 0.000 claims description 3
- 239000002002 slurry Substances 0.000 claims 1
- 239000000843 powder Substances 0.000 description 6
- 239000011435 rock Substances 0.000 description 6
- 239000000126 substance Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 230000005526 G1 to G0 transition Effects 0.000 description 2
- 239000004927 clay Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000004062 sedimentation Methods 0.000 description 2
- 239000002689 soil Substances 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 235000009508 confectionery Nutrition 0.000 description 1
- 238000007596 consolidation process Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000009415 formwork Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000005641 tunneling Effects 0.000 description 1
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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
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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
- 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
-
- 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
- E21D11/15—Plate linings; Laggings, i.e. linings designed for holding back formation material or for transmitting the load to main supporting members
- E21D11/152—Laggings made of grids or nettings
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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
- E21D11/38—Waterproofing; Heat insulating; Soundproofing; Electric insulating
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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
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- Mining & Mineral Resources (AREA)
- Structural Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
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Abstract
The invention discloses an excavation construction method of a small-section loess tunnel, which is characterized in that the tunnel to be excavated is divided into five parts, namely a leading pit upper step, a leading pit lower step, a following leading pit upper step, a following leading pit lower step, reserved core earthwork between the following leading pit upper step and the following leading pit lower step, and the five parts are used for excavation; firstly, excavating an upper step of a leading pit, then excavating an upper step of a trailing pit, and then excavating a lower step of the leading pit and a lower step of the trailing pit simultaneously. The method can shorten the construction period and solve the settlement problem of the collapsible loess.
Description
Technical Field
The invention relates to an excavation supporting method for small-section loess tunnel construction, which is suitable for the excavation supporting method of a novel small-section tunnel of old loess and new loess V-level surrounding rock.
Background
China is wide in territory, with the vigorous development of the infrastructure of China, large-area development of loess areas such as Gansu, Shanxi, Shaanxi and the like is carried out successively, more and more tunnels penetrate through the loess, and due to the special collapsible characteristic of the loess areas, the current loess tunnel construction method is not only complex in working procedure, high in investment cost and long in time. The small-section loess tunnel excavation construction method not only well meets the special requirements of loess special condition geology, topographic condition, general route linearity and the like, but also saves cost and shortens construction period, and has good technical and economic effects and remarkable economic, social and environmental benefits.
Disclosure of Invention
The invention aims to provide an excavation construction method of a small-section loess tunnel, which can shorten the construction period and solve the problem of settlement of collapsible loess.
To achieve these objects and other advantages in accordance with the present invention, there is provided an excavation construction method of a small-section loess tunnel, characterized in that a tunnel to be excavated is divided into five parts, which are a leading pit upper step, a leading pit lower step, a trailing pit upper step, a trailing pit lower step, and reserved core earthwork between the leading pit lower step and the trailing pit lower step, when excavated:
firstly, excavating an upper step of a leading pit, then excavating an upper step of a trailing pit, and then excavating a lower step of the leading pit and a lower step of the trailing pit simultaneously.
Preferably, the step excavation step for the leading pit includes: a1. supporting the advanced grouting guide pipe; a2. mechanical excavation and manual finishing; a3. c25 concrete with the thickness of 3-5cm is sprayed on the tunnel face to be sealed; a4. installing an I20b section steel primary support steel frame; a5. cloth-hanging a double-sided 20x20cm reinforcing mesh with the diameter of 6 mm; a6. installing a locking angle anchor rod with the diameter of 25mm and the length of 350 cm; a7. spraying C25 primary support concrete with the thickness of 22-26 cm;
the backward pilot tunnel upper step excavation process is the same as the forward pilot tunnel upper step excavation process.
Preferably, the step of excavating the lower bench of the pilot tunnel includes: b1. mechanical excavation and manual finishing; b2. c25 concrete with the thickness of 3-5cm is sprayed on the tunnel face to be sealed; b3. installing an I20b section steel primary support steel frame; b4. cloth-hanging a double-sided 20x20cm reinforcing mesh with the diameter of 6 mm; b5. installing a locking angle anchor rod with the diameter of 25mm and the length of 350cm and a steel pipe pile with the diameter of 50mm and the length of 5 m; b6. spraying C25 primary support concrete with the thickness of 22-26 cm;
the backward pit guiding lower step excavation process is the same as the forward pit guiding lower step excavation process.
Preferably, the width of the reserved core earthwork is 1/5-1/6 of the width of the tunnel.
Preferably, after the excavation of the upper step of the leading pilot tunnel is finished, the upper step of the leading pilot tunnel and the upper step of the trailing pilot tunnel are separated by a vertical steel frame support.
Preferably, after the tunnel is looped, inverted arch construction and arch wall lining construction are carried out;
the inverted arch construction comprises the steps of dismantling a vertical steel frame support in sections and excavating reserved core earthwork in sections, dismantling the length to meet the requirement of one-ring lining operation as a standard, then binding inverted arch reinforcing steel bars, installing water stops through vertical molds, and pouring C30 inverted arch concrete with the thickness of 50 cm;
the arch wall lining construction comprises the following steps: laying circumferential and longitudinal drainage pipes and laying waterproof boards; binding steel bars; installing an end template and a water stop belt; and C30 arch wall concrete with the thickness of 50cm is poured at one time.
Preferably, in rainy days, the reserved core earthwork on one side of the upper step of the leading pit is subjected to reinforcement pretreatment while vertical steel frame supporting and erecting is carried out, and the reserved core earthwork on the side is subjected to reinforcement pretreatment after the upper step of the trailing leading pit is excavated;
the reinforcement treatment specifically includes: drilling below along reserving core earthwork to the bottom of reserving core earthwork, the aperture is 12mm, and the pipe is inserted and grouted, and the pipe arrangement mode is: arranged at intervals of 1m in the longitudinal direction of the tunnel and at intervals of 0.5m in the width direction of the arch. The solid needs to be dried for 10 to 12 hours after grouting.
Preferably, after the steel pipe pile is installed, first anti-settling structures are arranged at intervals of 5 meters in the longitudinal direction of the tunnel, and each group of the first anti-settling structures is 10 m;
the anti-settling structure is as follows: and (2) longitudinally drilling holes along the tunnel within the range of 1m outside the steel pipe pile, wherein the hole depth is at least 1/2 of the steel pipe pile, the drilling hole interval is 1m, then inserting pipe sleeves into the drilled holes, inserting grouting pipes, the grouting pipes are provided with grouting holes along the axial direction and the longitudinal direction, openings are formed in the bottom ends of the grouting pipes, the diameters of the grouting pipes are 2-3cm and are slightly smaller than the diameters of the pipe sleeves, after the grouting pipes are erected, the pipe sleeves are pulled out, grouting is performed on the grouting pipes, and the grouting pipes move on one side while grouting until the holes are filled with grout.
Preferably, the grouting liquid comprises, by weight, 500 parts of water, 600 parts of sand, 200 parts of fly ash, 200 parts of cement, 50 parts of tetramethylsilane and 80 parts of water glass.
The invention at least comprises the following beneficial effects: by adopting the construction method, the erection of vertical steel frame supports is reduced, and meanwhile, the lower step of the leading pit and the lower step of the trailing pit can be excavated simultaneously, so that the construction period is greatly shortened.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Drawings
Fig. 1 is an elevation view during construction according to the present invention.
Reference numerals
The method comprises the following steps of 1 leading a pit to be an upper step, 2 trailing a pit to be an upper step, 3 leading a pit to be a lower step, 4 trailing a pit to be a lower step and 5 reserving core earthwork.
Detailed Description
The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.
It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials, if not otherwise specified, are commercially available; in the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
The tunnel surrounding rock is generally divided into 6 grades, and the first grade surrounding rock is the best and basically a whole block of hard stones; the worst grade six surrounding rock is basically broken loose soft soil. The construction method can be used for construction of old loess and new loess V-level surrounding rock (the structure is loose and the collapsibility is common), and the V class belongs to discrete bodies: sand layer landslide accumulation and crushed, pebbled and gravelly soil. Aiming at a small-section tunnel with the size of 3-10 m2。
Loess is one of powder clay, but loess will generally have the problem of collapsibility in comparison with powder clay, coarse powder grain and sand grain effect loess's skeleton in loess, its sand grain content is few, the colloidal substance through in the loess gathers on the coarse powder grain, consequently, under dry condition, loess has very high intensity, nevertheless when meetting rainwater weather, the colloidal substance in the loess can appear softening phenomenon, lead to loess intensity to descend suddenly, the collapsibility problem appears, lead to the tunnel can't be according to normal process tunnelling.
Example 1
The excavation method in the embodiment 1 is applied to a tunnel from qingcheng to Yonghe highway project Ningcounty in sweet water fort in Gansu province, wherein loess mainly is collapsible new loess and has the problem of easy settlement.
As shown in fig. 1, the invention provides a method for excavating a loess tunnel with a small cross section, which divides the tunnel to be excavated into five parts, namely a first pilot pit upper step 1, a first pilot pit lower step 3, a second pilot pit upper step 2, a second pilot pit lower step 4, reserved core earthwork 5 positioned between the first pilot pit lower step 3 and the second pilot pit lower step 4, wherein the width of the reserved core earthwork 5 is about 1/6 of the width of the tunnel, and the method is not particularly precise. The method specifically comprises the following steps:
firstly, excavating an upper step 1 of a pilot tunnel, wherein the excavating process comprises the following steps: a1. supporting the advanced grouting guide pipe; a2. mechanical excavation and manual finishing; a3. c25 concrete with the thickness of 3-5cm is sprayed on the tunnel face to be sealed; a4. installing an I20b section steel primary support steel frame; a5. cloth-hanging a double-sided 20x20cm reinforcing mesh with the diameter of 6 mm; a6. installing a locking angle anchor rod with the diameter of 25mm and the length of 350 cm; a7. c25 primary support concrete with the thickness of 22-26cm is sprayed. The excavation procedure of the backward pilot tunnel upper step 2 is the same as the excavation procedure of the forward pilot tunnel upper step 1.
And step two, adopting a vertical steel frame for supporting and separating the upper step 1 of the first guide pit and the upper step 2 of the second guide pit.
And step three, excavating the upper step 2 of the backward pilot tunnel, wherein the excavating process is the same as that of the upper step 1 of the forward pilot tunnel.
Step four, excavating the leading pit lower step 3 and the trailing pit lower step 4 simultaneously, wherein the excavating process comprises the following steps: b1. mechanical excavation and manual finishing; b2. c25 concrete with the thickness of 3-5cm is sprayed on the tunnel face to be sealed; b3. installing an I20b section steel primary support steel frame; b4. cloth-hanging a double-sided 20x20cm reinforcing mesh with the diameter of 6 mm; b5. installing a locking angle anchor rod with the diameter of 25mm and the length of 350cm and a steel pipe pile with the diameter of 50mm and the length of 5 m; b6. c25 primary support concrete with the thickness of 22-26cm is sprayed. The excavation process of the backward pit guiding lower step 4 is the same as the excavation process of the forward pit guiding lower step 3.
And fifthly, performing inverted arch construction and arch wall lining construction after the tunnel is looped.
The inverted arch construction comprises the steps of dismantling a vertical steel frame support in sections and excavating reserved core earthwork 5 in sections, dismantling the length to meet the requirement of one-ring lining operation as a standard, then binding inverted arch reinforcing steel bars, erecting a formwork and installing water stop belts, and pouring C30 inverted arch concrete with the thickness of 50 cm;
the arch wall lining construction comprises the following steps: laying circumferential and longitudinal drainage pipes and laying waterproof boards; binding steel bars; installing an end template and a water stop belt; and C30 arch wall concrete with the thickness of 50cm is poured at one time.
During, because the skeleton of coarse powder particle and grit effect loess in the collapsible loess, its sand grain content is few, through the colloidal substance gathering in the loess on the coarse powder particle, although under dry condition, the loess has very high intensity, when meetting rainwater weather, the softening phenomenon can appear in the colloidal substance in the loess, leads to loess intensity to descend suddenly, appears the collapsible problem: in the tunneling process of the tunnel, because the vertical steel frame support is arranged between the top of the tunnel and the reserved core earthwork 5, when colloidal substances are softened, the support strength of the reserved core earthwork 5 is reduced, the support force of the vertical steel frame support is weakened, and when the rainwater weather or the local part of the core earthwork is loose, the reserved core earthwork 5 on one side of the upper step 1 of the leading pit is reinforced and preprocessed while the vertical steel frame support is erected, and the reserved core earthwork 5 on the side is reinforced and preprocessed after the upper step 2 of the trailing pit is excavated; the reinforcement treatment specifically includes: drilling downwards to the bottom of reserving core earthwork 5 along the upper part of reserving core earthwork 5, wherein the aperture is 12mm, the conduit is inserted into the hole for grouting, and the conduit arrangement mode is as follows: arranging at intervals of 1m along the longitudinal direction of the tunnel, arranging at intervals of 0.5m along the width direction of the arch, and carrying out the third step after 8-10 hours are needed after grouting. The grouting liquid is the same as that of the anti-settling structure.
In addition, because subsidence problem appears after collapsible loess tunnel has been built easily, in order to solve this problem, install the steel-pipe pile after, set up first anti-settlement structure along the tunnel longitudinal direction interval 5 meters, every group is first to prevent that subsides the structure and is 10 m.
The anti-settling structure is as follows: and (2) longitudinally drilling holes along the tunnel within the range of 1m outside the steel pipe pile (namely along one side far away from the tunnel), wherein the hole depth is at least 1/2 of the steel pipe pile, the drilling distance is 1m, then inserting pipe sleeves into the drilled holes, inserting grouting pipes, the grouting pipes are provided with grouting holes along the axial direction and the longitudinal direction, the bottom ends of the grouting pipes are provided with openings, the diameters of the grouting pipes are 2-3cm and are slightly smaller than the diameters of the pipe sleeves, after the grouting pipes are erected, the pipe sleeves are pulled out, the grouting pipes are grouted, and the grouting pipes move on one side while grouting until the holes are full of grout.
The grouting liquid comprises, by weight, 500 parts of water, 600 parts of sand, 200 parts of fly ash, 200 parts of cement, 50 parts of tetramethylsilane and 80 parts of water glass.
In the embodiment, the grouting liquid is not easily diluted by underground water, the effect of consolidation and water stop is realized, the bearing capacity of the foundation is improved, and the deformation of surrounding rocks can be effectively resisted.
In rainy weather, respectively, the first group: adopting the construction of the first to fifth steps of the embodiment 1 for the tunnel; the second group adopts the construction of the first to the fifth steps and the anti-settlement structure construction of the embodiment 1 to the tunnel. The depths of the two groups of construction tunnels are the same, and through experimental comparison, the average daily settlement of the first group in the unstable period of the tunnel is 2mm, and the average daily settlement of the first group in the stable period is 0.5 mm. The second group had an average daily sedimentation amount of 0.8mm during the non-stationary phase of the tunnel and an average daily sedimentation amount of 0.2mm during the stationary phase.
While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.
Claims (5)
1. The excavation construction method of the small-section loess tunnel is characterized in that the tunnel to be excavated is divided into five parts, namely a leading pit upper step, a leading pit lower step, a following leading pit upper step and a following leading pit lower step, reserved core earthwork between the leading pit lower step and the following leading pit lower step is positioned, and during excavation:
firstly, excavating an upper step of a leading pit, then excavating an upper step of a trailing pit, and then excavating a lower step of the leading pit and a lower step of the trailing pit simultaneously;
reserving 1/5-1/6 of the width of the core earthwork as the width of the tunnel;
the working procedure of excavation of the lower step of the pilot tunnel comprises the following steps: b1. mechanical excavation and manual finishing; b2. c25 concrete with the thickness of 3-5cm is sprayed on the tunnel face to be sealed; b3. installing an I20b section steel primary support steel frame; b4. cloth-hanging a double-sided 20x20cm reinforcing mesh with the diameter of 6 mm; b5. installing a locking angle anchor rod with the diameter of 25mm and the length of 350cm and a steel pipe pile with the diameter of 50mm and the length of 5 m; b6. spraying C25 primary support concrete with the thickness of 22-26 cm;
the backward pit guiding lower step excavation process is the same as the forward pit guiding lower step excavation process;
after installing the steel pipe piles, arranging first anti-settling structures at intervals of 5 meters in the longitudinal direction of the tunnel, wherein each group of the first anti-settling structures is 10 meters;
the first anti-settling structure is as follows: drilling holes along the longitudinal direction of the tunnel within the range of 1m outside the steel pipe pile, wherein the hole depth is at least 1/2 of the steel pipe pile, the drilling hole interval is 1m, then inserting pipe sleeves into the drilled holes, inserting grouting pipes, the grouting pipes are provided with grouting holes along the axial direction and the longitudinal direction, openings are arranged at the bottom ends of the grouting pipes, the diameters of the grouting pipes are 2-3cm and are slightly smaller than the diameters of the pipe sleeves, after the grouting pipes are erected, the pipe sleeves are pulled out, grouting is carried out on the grouting pipes, and the grouting pipes move upwards while grouting until the holes are filled with grout;
the slurry comprises, by weight, 500 parts of water, 600 parts of sand, 200 parts of fly ash, 200 parts of cement, 50 parts of tetramethylsilane and 80 parts of water glass.
2. The excavation construction method of a small-section loess tunnel according to claim 1, wherein the preliminary pit guiding and upper step excavation process comprises: a1. supporting the advanced grouting guide pipe; a2. mechanical excavation and manual finishing; a3. c25 concrete with the thickness of 3-5cm is sprayed on the tunnel face to be sealed; a4. installing an I20b section steel primary support steel frame; a5. cloth-hanging a double-sided 20x20cm reinforcing mesh with the diameter of 6 mm; a6. installing a locking angle anchor rod with the diameter of 25mm and the length of 350 cm; a7. spraying C25 primary support concrete with the thickness of 22-26 cm;
the backward pilot tunnel upper step excavation process is the same as the forward pilot tunnel upper step excavation process.
3. The excavation construction method of the small-section loess tunnel according to claim 1, wherein after the excavation of the upper step of the leading pit is completed, the upper step of the leading pit and the upper step of the trailing pit are separated by a vertical steel frame support.
4. The excavation construction method of the small-section loess tunnel according to claim 3, wherein inverted arch construction and arch wall lining construction are performed after the tunnel is looped;
the inverted arch construction comprises the steps of dismantling a vertical steel frame support in sections and excavating reserved core earthwork in sections, dismantling the length to meet the requirement of one-ring lining operation as a standard, then binding inverted arch reinforcing steel bars, installing water stops through vertical molds, and pouring C30 inverted arch concrete with the thickness of 50 cm;
the arch wall lining construction comprises the following steps: laying circumferential and longitudinal drainage pipes and laying waterproof boards; binding steel bars; installing an end template and a water stop belt; and C30 arch wall concrete with the thickness of 50cm is poured at one time.
5. The excavation construction method of the small-section loess tunnel according to claim 1, wherein the reinforcement pretreatment is performed on the reserved core earthwork on one side of the upper step of the leading pit while the primary support steel frame of the I20b steel is erected, and the reinforcement pretreatment is performed on the reserved core earthwork on the side after the upper step of the following leading pit is excavated;
the reinforcement pretreatment specifically comprises: drilling below along reserving core earthwork to the bottom of reserving core earthwork, the aperture is 12mm, and the pipe is inserted and grouted, and the pipe arrangement mode is: arranged at intervals of 1m in the longitudinal direction of the tunnel and at intervals of 0.5m in the width direction of the tunnel.
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| CN110145314B9 (en) * | 2019-05-10 | 2020-11-20 | 中建隧道建设有限公司 | Method for removing high and large core soil of extra-large section underground tunnel |
| CN111535818A (en) * | 2020-04-21 | 2020-08-14 | 中铁广州工程局集团有限公司 | Rapid construction method for large-section tunnel of high-speed railway |
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| CN201459525U (en) * | 2009-06-29 | 2010-05-12 | 中铁二院工程集团有限责任公司 | Foundation structure at tunnel-to-bridge junction of high-speed railway in loess regions |
| CN102606176B (en) * | 2012-03-16 | 2014-04-02 | 西安理工大学 | Collapsible loess tunnel construction method |
| CN106246200A (en) * | 2016-08-30 | 2016-12-21 | 中铁第勘察设计院集团有限公司 | Tunnel weakness substrate small-sized pile tube reinforcement system and construction method thereof |
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