CN110118090B - Protective structure for preventing earth surface bulge caused by tunnel grouting reinforcement - Google Patents
Protective structure for preventing earth surface bulge caused by tunnel grouting reinforcement Download PDFInfo
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- CN110118090B CN110118090B CN201910511046.2A CN201910511046A CN110118090B CN 110118090 B CN110118090 B CN 110118090B CN 201910511046 A CN201910511046 A CN 201910511046A CN 110118090 B CN110118090 B CN 110118090B
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- 230000002787 reinforcement Effects 0.000 title claims abstract description 28
- 230000001681 protective effect Effects 0.000 title claims abstract description 10
- 230000002441 reversible effect Effects 0.000 claims abstract description 87
- 238000005553 drilling Methods 0.000 claims abstract description 43
- 239000011435 rock Substances 0.000 claims description 45
- 239000002689 soil Substances 0.000 claims description 40
- 230000008093 supporting effect Effects 0.000 claims description 40
- 238000000034 method Methods 0.000 claims description 28
- 238000010276 construction Methods 0.000 claims description 22
- 239000002002 slurry Substances 0.000 claims description 19
- 238000005507 spraying Methods 0.000 claims description 16
- 239000000654 additive Substances 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 12
- 230000000996 additive effect Effects 0.000 claims description 10
- 230000000694 effects Effects 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 239000004568 cement Substances 0.000 claims description 9
- 229910000831 Steel Inorganic materials 0.000 claims description 8
- 239000010959 steel Substances 0.000 claims description 8
- 230000003247 decreasing effect Effects 0.000 claims description 3
- 230000002265 prevention Effects 0.000 claims 1
- 239000010410 layer Substances 0.000 description 37
- 239000004576 sand Substances 0.000 description 8
- 230000005641 tunneling Effects 0.000 description 7
- 238000009792 diffusion process Methods 0.000 description 4
- 230000001976 improved effect Effects 0.000 description 4
- 238000009412 basement excavation Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000002829 reductive effect Effects 0.000 description 3
- 230000003014 reinforcing effect Effects 0.000 description 3
- 230000000630 rising effect Effects 0.000 description 3
- 230000001133 acceleration Effects 0.000 description 2
- 238000009933 burial Methods 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 210000002268 wool Anatomy 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/12—Consolidating by placing solidifying or pore-filling substances in the soil
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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
- E21D11/15—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
- E21D11/14—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
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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
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D2250/00—Production methods
- E02D2250/003—Injection of material
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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)
- Life Sciences & Earth Sciences (AREA)
- Structural Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Civil Engineering (AREA)
- Architecture (AREA)
- Soil Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Agronomy & Crop Science (AREA)
- Paleontology (AREA)
- General Engineering & Computer Science (AREA)
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
- Excavating Of Shafts Or Tunnels (AREA)
- Lining And Supports For Tunnels (AREA)
Abstract
The invention relates to a protective structure for preventing earth surface bulge caused by tunnel grouting reinforcement, which comprises a tunnel body positioned below the surface of a stratum, wherein a reverse curved arch formed by earth surface grouting is arranged in the stratum right above the tunnel body, the reverse curved arch is in a downward convex arch shape, a support structure is arranged on the top wall of the inner contour of the tunnel body, the top wall of the inner contour of the tunnel body is surrounded, a forward curved arch formed by drilling grouting is arranged on the outer side of the support structure, the forward curved arch is in an upward convex arch shape, and a stress bearing body is formed by layering, grouting for multiple times and combining multiple passive support modes.
Description
Technical Field
The invention belongs to the technical field of geotechnical engineering and civil engineering, and particularly relates to a protective structure for preventing earth surface bulge caused by grouting reinforcement of a tunnel. The method is suitable for permanent tunnel engineering which is easy to cause a series of problems such as surface elevation, road cracking, building inclination and the like when the shallow tunnel passes through loose rock stratum and sand layer.
Background
With the development of economic globalization and the acceleration of urban process, subway engineering becomes more and more a main direction of urban public transportation development. The subway not only enhances the travel rapidness and saves the time of people, but also plays a good promoting role in the development of urban environment-friendly construction. In the period of industrialization and urban acceleration, millions of people are rushing into large cities, and huge pressure is brought to urban management and urban traffic. Compared with other projects, the subway project is a large civil engineering with large investment, long construction period and complex technology. The subway engineering has the characteristics of concealment, uncertainty of geological environment, construction technology complexity and the like, which can cause a large number of risks and complex types of engineering in the construction period, and even cause large economic loss after accidents.
The subway is in urban areas with noisy cities, dense population and dense construction, and the tunnel (roadway) excavated for constructing the subway is positioned at a shallow position of the whole crust, so that the difficulty of excavation and support is obviously increased when the underground is required to pass through loose rock stratum and sand soil layers. In the national field, subways are generally built at the depth of about 20 meters underground, and 4 metro cities of Beijing, tianjin, guangzhou and Shanghai are counted, and the depth of a five-wire line of Beijing reaches 24 meters when a tunnel (roadway) is built at about 20 meters underground. According to different soil, geology and line distribution, the depth of the subway is different, and some countries in the world such as Russian and London are all about 50 meters underground.
Aiming at the condition that a tunnel (roadway) is positioned on a loose rock layer and a sandy soil layer, and can penetrate through the loose rock soil layer, the existing road on the ground or other building structures during construction, the construction of the general tunnel (roadway) at present adopts an open excavation method at the end part of a few parts, and the route length of ninety percent adopts methods such as a drilling and blasting method, a shield method, a heading machine method, a new Otto method and the like in the undermining method. The original stress state is changed to cause stress redistribution by the original completion of the excavation of the stable rock-soil layer through tunneling (roadway). The weight of overburden and built structures causes deformation of the tunnel, so that the excavated tunnel must be supported, and loose rock and sand layers between the tunnel and the earth surface must be reinforced, which are called burial depths. At present, a grouting method is basically adopted for reinforcing the part of the rock-soil body, because the buried depth of a tunnel (roadway) is shallow, the tunnel (roadway) is a thin shell relative to the thickness of the whole stratum, and the tunnel (roadway) is close to the ground surface, so that the grouting reinforcement effect is achieved, generally, larger grouting pressure is required, but the excessive grouting pressure can cause the phenomenon that the rock-soil body arches up to the ground surface until the ground surface is raised, the original state of the ground surface is damaged, and the ground surface road is cracked and the built structures are unevenly settled. At this time, if the grouting pressure is reduced, the purpose of controlling the surface bulge deformation can be achieved, but too low pressure can directly lead to the reduction of the slurry diffusion radius, so that the effect of reinforcing the rock-soil body cannot be achieved. According to experience, the slurry diffusion radius is generally about 25cm, so that the grouting hole spacing is generally designed to be about 50cm in actual construction, so that the phenomenon that the slurry diffusion radii of two grouting holes are overlapped is ensured under effective grouting pressure, and the purpose that a rock-soil body between the grouting holes is sufficiently reinforced is achieved. If the grouting pressure is reduced, the diffusion radius of the slurry is reduced, the conventional grouting hole spacing cannot ensure that the surrounding rock and soil body is fully reinforced, the grouting body is discontinuous, and the stress state of the grouting rock and soil mixture is affected, so that the grouting device is imperative to improve and innovate.
Disclosure of Invention
Aiming at the situation, in order to overcome the defects of the prior art, the invention aims to provide a protection structure for preventing the earth surface from rising caused by grouting reinforcement of a tunnel and a tunnel advanced grouting method, which can effectively solve the problem of preventing the earth surface from rising caused by grouting reinforcement.
The technical scheme of the invention is as follows: the utility model provides a protective structure for preventing tunnel grouting reinforcement causes earth's surface to rise, is provided with the reverse curved arch that forms by earth's surface grouting including being located the tunnel body of stratum surface below in the stratum directly over the tunnel body, reverse curved arch is bellied arch downwards, is provided with supporting construction on the top group of tunnel body internal profile, surrounds the top group of tunnel body internal profile, is provided with the forward curved arch that forms by drilling grouting in supporting construction's outside, forward curved arch is the arch that makes progress, and forward curved arch, reverse curved arch and supporting construction form jointly and prevent that advanced grouting from causing the complex supporting construction of earth's surface to rise.
The supporting structure is an anchor rod net hanging and anchor spraying supporting or a steel arch supporting or a combined supporting formed by the anchor rod net hanging and anchor spraying supporting or the steel arch supporting.
The thickness of the reverse camber arch is 3-4m, and the thickness of the forward camber arch is more than 2m.
The projection length of the reverse camber in the width direction on the horizontal ground is L, the depth from the lowest point of the reverse camber to the horizontal ground is H as the span of the reverse camber, the sagittal ratio of the reverse camber is DeltaK as the sagittal height, and DeltaK=H/L, and DeltaK is 1/5-1/6.
The vertical center lines of the tunnel body, the forward camber and the reverse camber are collinear.
The top side of the inner contour of the tunnel body is provided with an advanced grouting pipe which is obliquely arranged towards the trend of the tunnel, and an outlet of the advanced grouting pipe is positioned between the coverage areas of the forward curved arch and the reverse curved arch.
The tunnel advanced grouting method for preventing the surface bulge based on the protection structure comprises the following steps of:
A. surface drilling grouting
Before the tunnel is constructed to the section to be protected, surface drilling is carried out on the stratum surface with a loose rock soil layer right above the trend of the tunnel body along the trend of the tunnel body, the drilling holes are arranged in a quincuncial shape, the overlooking central connecting line of the same row of drilling holes is perpendicular to the trend of the tunnel, the drilling depth at the center is the largest in the same row of drilling holes, the drilling depths from the center to two sides are gradually decreased, and the lower ends of the same row of drilling holes are all positioned in the designed reverse camber range where the section is positioned;
placing a repeatable grouting pipe into the drill hole, and grouting through the repeatable grouting pipe to form an integral supporting structure by the slurry and the loose rock soil layer to form a reverse camber together;
B. tunnel support
When the tunnel is constructed to the section to be protected, firstly, the wool section of the tunnel body is dug, the concrete is sprayed initially, a supporting structure is installed, and finally, the concrete is sprayed again;
C. tunnel drilling grouting
After re-spraying concrete for 1 day, drilling and grouting around the top wall of the inner contour of the tunnel body to form a forward curved arch;
D. advanced grouting
Performing advanced grouting between the reverse camber and the forward camber;
E. bottom plate pouring
And (3) pouring concrete on the bottom plate of the tunnel to form the tunnel section size meeting the design requirement.
The method comprises the steps that the reverse curved arch is designed to be located in a loose rock soil layer right above the trend of a tunnel, the reverse curved arch is designed to be in a downward protruding arch shape, the projection length of the reverse curved arch on the horizontal ground in the width direction is L, the span of the reverse curved arch is used as the span, the depth from the lowest point of the reverse curved arch to the horizontal ground is H, the sagittal ratio of the reverse curved arch is delta K as the sagittal height, delta K=H/L, and the delta K is 1/5-1/6;
the space between the lower end of the repeatable grouting pipe and the lower end surface of the designed reverse camber is equal.
The grouting operation in the step A is as follows:
the lower end of the repeatable grouting pipe is not more than 10cm away from the bottom of the drill hole, initial grouting is firstly carried out, solidified slurry is injected into the grouting hole through the repeatable grouting pipe, the initial grouting adopts filling grouting, the grouting pressure is controlled to be less than 0.5Mpa, and the used grouting liquid consists of 325# cement, an additive and water, and the ratio of the grouting liquid to the additive is 1:0.08:2.
After the initial grouting is finished for 2-3 hours, the slurry reaches an initial setting state, the slurry is primarily bonded with loose rock stratum and sand soil layer in the loose rock soil layer to form a whole, after the initial grouting and loose rock soil layer have certain bearing strength, secondary grouting is carried out, the grouting pressure of the secondary grouting is larger than that of the primary grouting and is controlled to be smaller than 3Mpa, the reverse sectional grouting is adopted, the grouting is composed of 325# cement, additives and water, the proportion is 1:0.08:2, the reverse sectional grouting thickness is adopted to be 3-4m until a complete reverse camber is formed, so that the effect of improving the strength of the loose rock soil layer is achieved, an internal grouting reinforcement body is formed through the initial grouting and the secondary grouting, and the internal grouting reinforcement body and the surrounding loose rock soil layer form an integral supporting structure to form a reverse camber for bearing stress together.
The invention has the advantages that the space stability theory of the curved arch is utilized to be organically combined with the conventional passive support forms such as anchor spraying support, steel arch plus anchor spraying support or combined support, and the like, the stress bearing bodies are formed by layering, grouting for multiple times and combining various passive support modes, the reverse curved arch structure and the forward curved arch structure are formed successively, the stress distribution state of loose rock layers such as loose rock stratum and sandy soil layer around the tunnel (roadway) is changed, the peak value of stress concentration is shifted out of the three-belt stress area of the tunnel (roadway), the characteristic of large bearing capacity of the curved arch shape is fully utilized, the influence of dynamic and static loads on the surface of the stratum on the tunnel (roadway) is blocked, meanwhile, the influence of the advanced grouting pressure of the tunnel (roadway) on the surface road and the building structure is also blocked, the mutual stability of the tunnel (roadway) and the tunnel (roadway) is respectively ensured, the high-pressure grouting can be realized, the deformation of the ground surface and the building structure is controlled, the bulge of the ground surface is prevented, and the grouting reinforcement effect of the loose rock layer is fully realized. The loose rock-soil body is repaired by high-pressure grouting, so that the integrity and bearing capacity of surrounding rock are improved, the loose rock-soil body at the upper part of a tunnel (roadway) is in a good stable state for a long time, and the high-pressure grouting can be formed by the protection of a reverse curved arch under the condition that the surrounding environment and the rock-soil property are not very accurately mastered. The method has wide application range, is suitable for both new tunneling and repairing tunneling (roadway), is especially suitable for engineering that the shallow tunneling (roadway) passes through loose rock stratum and sand soil layer, is easy to form a complete set of construction technical measures, has the characteristics of simple method, convenient implementation, convenient mechanized operation and good supporting effect, has engineering popularization and application value, and has remarkable economic benefit along with continuous development of shallow underground engineering.
Drawings
FIG. 1 is a schematic cross-sectional view of the overall arrangement of the present invention.
FIG. 2 is a schematic cross-sectional view of a reverse camber arrangement of the present invention;
FIG. 3 is a schematic cross-sectional view of a placement of a slip-cast reinforcement zone;
fig. 4 is an overall plan view of a method for preventing grouting reinforcement from causing surface elevation by reverse continuous camber.
Wherein: 1. a surface of the formation; 2. drilling holes on the earth surface; 3. a repeatable grouting pipe; 4. loosening a rock soil layer; 5. reverse camber; 6. an advanced grouting pipe; 7. shallow grouting holes; 8. a tunnel body; 9. the vertical center line of the tunnel body; 10. a bottom plate; 11. a forward camber arch; 12. advanced grouting reinforcement area; 13. a bolt; 14. a transverse centerline of the tunnel body; 15. a wool section of the tunnel body; 16. steel arch frame.
Detailed Description
The following describes the embodiments of the present invention in further detail with reference to the drawings.
As shown in fig. 1-4, the protection structure for preventing earth surface bulge caused by tunnel grouting reinforcement comprises a tunnel body 8 positioned below a stratum surface 1, wherein a reverse camber arch 5 formed by earth surface grouting is arranged in the stratum right above the tunnel body 8, the reverse camber arch 5 is in a downward convex arch shape, a support structure is arranged on the top wall of the inner contour of the tunnel body 8, the top wall of the inner contour of the tunnel body is surrounded, a forward camber arch 11 formed by drilling grouting is arranged on the outer side of the support structure, the forward camber arch 11 is in an upward convex arch shape, and the forward camber arch 11, the reverse camber arch 5 and the support structure jointly form a combined support structure for preventing earth surface bulge caused by advanced grouting.
In order to ensure the use effect, the supporting structure is a combined supporting formed by an anchor rod net hanging and anchor spraying supporting 13 or a steel arch supporting 16 or both which are arranged on the inner wall of the tunnel body 8.
The thickness of the reverse camber 5 is 3-4m, and the thickness of the forward camber 11 is more than 2m.
The projection length of the reverse camber 5 on the horizontal ground along the width direction is L, the depth from the lowest point of the reverse camber 5 to the horizontal ground is H as the span of the reverse camber, the sagittal ratio of the reverse camber is DeltaK as the sagittal height, and DeltaK=H/L, and DeltaK is 1/5-1/6.
If the surface of the stratum is not horizontal, the reference of the horizontal ground is the lowest point.
The distance between the forward curved arch 11 and the reverse curved arch 5 is larger than 2m, and the distance between the reverse curved arch (lowest point) and the forward curved arch (highest point) is selected according to practical conditions because of different burial depths of tunnels in underground space, and under the protection of the forward curved arch and the reverse curved arch, high-pressure grouting is performed in an interlayer between the forward curved arch and the reverse curved arch to achieve the effect of reinforcing surrounding rock bodies, so that the effect of supporting the surrounding rock bodies and grouting bodies together is achieved.
The vertical center lines 9, 11 of the tunnel body 8 and the reverse camber 5 are collinear.
The top side of the inner contour of the tunnel body 8 is provided with an advanced grouting pipe 6 which is obliquely arranged towards the trend of the tunnel, and the outlet of the advanced grouting pipe 6 is positioned between the coverage areas of the forward curved arch 11 and the reverse curved arch 5.
The advanced grouting pipes 6 are arranged according to the existing specification, are generally arranged in a way of outwards inclining by 30-60 degrees according to the trend of the corresponding tunnel, the distance is generally controlled to be about 0.5m, and the drilling angle and the distance can be properly adjusted under special geological conditions, and the technology is the prior art. The method comprises the following steps: grouting holes with a certain depth are formed on the top side in a tunnel (roadway) to carry out medium-deep hole grouting operation, an internal grouting reinforcement is formed, the grouting pressure of medium-deep hole advanced grouting can be properly improved under the protection of a reverse continuous arch 5 and a forward arch 11, the grouting pressure is generally controlled below 8Mpa, and the grouting liquid is composed of 425# cement, an additive and water in a ratio of 1:0.08:2.
The top side of the inner contour of the tunnel body 8 is composed of an upper arc-shaped part and lower vertical edge parts connected with two ends of the arc-shaped part.
The tunnel advanced grouting method for preventing the earth surface from rising of the protective structure comprises the following steps of:
A. surface drilling grouting
Before the tunnel is constructed to the section to be protected, firstly transferring temporary facilities which are required to be transferred on the surface of the stratum due to construction, arranging a grouting station at a proper position, preparing for subsequent reverse camber grouting, carrying out surface drilling 2 on the surface of the stratum with a loose rock soil layer 4 right above the trend of the tunnel body, wherein the drilling diameter is preferably slightly larger than the diameter of a grouting pipe, the drilling is arranged in a quincuncial shape, the overlooking central connecting line of the same row of drilling is vertical to the trend of the tunnel, the drilling depth at the center is the largest in the same row of drilling, the drilling depths from the center to two sides are gradually decreased, and the lower ends of the same row of drilling are all positioned in the designed reverse camber range where the section is positioned;
the interval between the surface drilling holes 2 is 0.4-0.6m;
placing a repeatable grouting pipe 3 in the drilled hole, wherein the repeatable grouting pipe is a plastic pipe (PVC pipe) with good hardness and elasticity, the bottom end of the repeatable grouting pipe is sealed, a circle of grouting small holes (such as 3-4 grouting small holes) are drilled on the pipe wall at intervals (such as 15-20 cm), a certain number of grouting small holes are arranged at equal intervals in each circle, and the relative heights of the grouting small holes on each repeatable grouting pipe are the same, so that the slurry can uniformly and equivalently diffuse around the grouting holes.
Grouting operation is carried out through the repeatable grouting pipe 3, so that slurry and the loose rock soil layer 4 form an integral supporting structure to form a reverse camber 5 together;
B. tunnel support
When the tunnel is constructed to the section to be protected, firstly, mao Duanmian 15 of the tunnel body is excavated, primary spraying of concrete is carried out, a supporting structure is installed, and finally, the concrete is sprayed again;
the specific method comprises the following steps: when the tunnel is constructed to the section to be protected, firstly, the Mao Duanmian of the tunnel body is dug, the primary spraying concrete is immediately carried out, the thickness of the primary spraying concrete is generally 20-30mm, then, the tunnel (roadway) to be dug is carried out with anchor rod hanging net, anchor spraying and supporting 13 and steel arch supporting 16 or combined supporting of the two according to the characteristics and strength grades of surrounding rock soil layers to form a supporting structure, finally, the thickness of the secondary spraying concrete is generally 80-100mm, the underdug part is manually treated after the secondary spraying is finished, the overexcavated part is filled up, the leaked anchor rods and anchor rope ends are properly treated, and finally, the whole tunnel (roadway) is leveled, so that the shape and the size of the section of the whole tunnel (roadway) are ensured to be in accordance with the design.
C. Tunnel drilling grouting
After re-spraying concrete for 1 day, a positive camber 11 formed by grouting around a top wall drilling hole of the inner contour of the tunnel body;
the specific method comprises the following steps: after the concrete is sprayed again for 1 day, shallow grouting holes 7 with the depth below 2m are formed on the tunnel (roadway) top wall, then grouting pipes are installed for grouting, the grouting pressure is generally controlled below 5Mpa, the grouting liquid is composed of 425# cement, additives and water, the proportion of the grouting liquid is 1:0.08:2, and a forward curved arch 11 is formed around the tunnel (roadway) top wall shape, so that the forward curved arch and a supporting structure form a combined body supporting structure together.
D. Advanced grouting
Performing advanced grouting reinforcement in an advanced grouting reinforcement area 12 between the reverse camber arch 5 and the forward camber arch 11;
the specific method comprises the following steps: the grouting method is characterized in that grouting holes with a certain depth are formed in the top wall of a tunnel (roadway), an advanced grouting pipe 6 is arranged for medium-length hole grouting operation, an internal grouting reinforcement body is formed, the outlet of the advanced grouting pipe 6 is located between the coverage areas of a forward curved arch 11 and a reverse curved arch 5, grouting pressure of the medium-length hole advanced grouting 6 can be properly improved under the protection of the reverse curved arch 5 and the forward curved arch 11, grouting liquid is generally controlled to be below 8Mpa, the grouting liquid is composed of 425# cement, an additive and water, the ratio of the grouting liquid to the grouting hole is 1:0.08:2, the spacing of the advanced grouting pipe is generally controlled to be about 0.5m, and the drilling angle and the spacing of the grouting hole can be properly adjusted under special geological conditions.
E. Bottom plate pouring
And (5) pouring concrete on the bottom plate 10 of the tunnel to form the tunnel section size meeting the design requirements.
The reverse camber is designed to be in a loose rock soil layer 4 right above the trend of the tunnel, the reverse camber is designed to be in a downward convex arch shape, the projection length of the reverse camber 5 on the horizontal ground along the width direction is L, the span of the reverse camber is used as the span of the reverse camber, the depth from the lowest point of the reverse camber 5 to the horizontal ground is H, the sagittal ratio of the reverse camber is delta K, delta K=H/L, and delta K is 1/5-1/6;
the space between the lower end of the repeatable grouting pipe 3 and the lower end face of the designed reverse camber is equal.
The determination method of the surface drilling depth comprises the following two methods:
a. the ground reverse continuous arch grouting belongs to ground surface grouting, the drilling depth is generally 6-7m, the specific depth is determined according to the thickness of a loose rock soil layer formed by a loose rock layer and a sand soil layer or the distance between a tunnel (roadway) and the ground surface, and then L can be calculated according to the selected delta K;
b. in practice, the width of the building to be protected is easy to measure, then L is easy to determine, and after proper delta K is selected, the grouting hole depth H can be calculated, but the requirement that the distance between the forward curved arch 11 and the reverse curved arch 5 is larger than 2m must be met.
The grouting operation in the step A is as follows:
the lower end of the repeatable grouting pipe is not more than 10cm away from the bottom of the drill hole, initial grouting is firstly carried out, solidified slurry is injected into the grouting hole through the repeatable grouting pipe, the initial grouting adopts filling grouting, the grouting pressure is controlled to be less than 0.5Mpa (the shape of the reverse camber arch 5 is prevented from being damaged by overlarge grouting pressure, the bearing capacity of the whole loose rock layer is prevented from being influenced), and the grouting liquid is composed of 325# cement, an additive and water, wherein the ratio of the grouting liquid to the additive is 1:0.08:2.
After the initial grouting is finished for 2-3 hours, the slurry reaches an initial setting state, the slurry is primarily bonded with a loose rock layer and a sandy soil layer in a loose rock layer (4) to form a whole, after the slurry has a certain bearing strength, secondary grouting is carried out, the grouting pressure of the secondary grouting is larger than that of the primary grouting and is controlled to be smaller than 3Mpa, the adopted reverse sectional grouting is 325# cement, an additive and water, the proportion of the adopted grouting is 1:0.08:2, the thickness of the adopted reverse sectional grouting is 3-4m until a complete reverse camber 5 is formed, so that the effect of improving the strength of the loose rock layer is achieved, after grouting is finished, a grouting pipe is flushed by water, residual slurry in the pipe is removed, an internal grouting reinforcement body is formed through the initial grouting and the secondary grouting, and the internal grouting reinforcement body and the surrounding loose rock layer form a whole supporting structure together to form the reverse camber 5 for bearing stress.
The back sectional grouting is in the prior art, namely simply lifting the grouting pipe for a certain distance, such as 20-30cm, after the primary grouting is finished, performing secondary grouting, lifting the grouting pipe for 20-30cm again after the secondary grouting is finished, performing tertiary grouting, and repeating the steps until the grouting thickness reaches 3-4m.
The invention can be clearly seen from the above situation, the space stability theory of the curved arch is utilized to be organically combined with the conventional passive support forms such as the anchor spray support, the steel arch plus anchor spray support or the combined support, and the stress bearing bodies are formed by layering, grouting for multiple times and combining multiple passive support modes together, so that the reverse curved arch structure and the forward curved arch structure are formed successively, the stress distribution state of loose rock layers such as loose rock stratum and sand soil layer around the tunnel (roadway) is changed, the peak value of stress concentration is shifted out of the three-zone stress area of the tunnel (roadway), the characteristic of large bearing capacity of the curved arch shape is fully utilized, the influence of dynamic load and static load on the surface of the tunnel (roadway) is blocked, the influence of the advanced grouting pressure of the tunnel (roadway) on the surface road and the construction structure is also blocked, the mutual stability of the tunnel (roadway) is respectively ensured, the deformation of the ground surface and the construction structure is controlled, and the effect of the grouting reinforcement of the loose rock layer is fully realized. The loose rock-soil body is repaired by high-pressure grouting, so that the integrity and bearing capacity of surrounding rock are improved, the loose rock-soil body at the upper part of a tunnel (roadway) is in a good stable state for a long time, and the high-pressure grouting can be formed by the protection of a reverse curved arch under the condition that the surrounding environment and the rock-soil property are not very accurately mastered. The method has wide application range, is suitable for both new tunneling and repairing tunneling (roadway), is especially suitable for engineering that the shallow tunneling (roadway) passes through loose rock stratum and sand soil layer, is easy to form a complete set of construction technical measures, has the characteristics of simple method, convenient implementation, convenient mechanized operation and good supporting effect, has engineering popularization and application value, and has remarkable economic benefit along with continuous development of shallow underground engineering.
The applicant should additionally point out that the above description is only a description of the general implementation steps of the present invention, and is not intended to limit the present invention in any way, so any modifications and variations to the above-described construction steps depending on the theoretical basis and technical substance of the present invention are all within the scope of protection of the present invention.
Claims (6)
1. The utility model provides a protection structure for preventing tunnel grouting reinforcement causes earth's surface to rise, including being located tunnel body (8) below stratum surface (1), characterized by, be provided with in the stratum directly over tunnel body (8) reverse curved arch (5) that are formed by earth's surface grouting, reverse curved arch (5) are the arch that protrudes downwards, be provided with supporting construction on the top of tunnel body (8) inner profile, around the top of tunnel body inner profile, be provided with forward curved arch (11) that are formed by drilling grouting in the outside of supporting construction, forward curved arch (11) are the arch that protrudes upwards, forward curved arch (11), reverse curved arch (5) and supporting construction form jointly and prevent that advanced grouting causes earth's surface to rise's joint body supporting construction;
the projection length of the reverse camber (5) on the horizontal ground along the width direction is L, the span of the reverse camber is H from the lowest point of the reverse camber (5) to the horizontal ground, the sagittal ratio of the reverse camber is DeltaK, deltaK=H/L, and DeltaK is 1/5-1/6;
the supporting structure is a combined supporting formed by an anchor rod net hanging and anchor spraying supporting (13) or a steel arch supporting (16) or both which are arranged on the inner wall of the tunnel body (8).
2. The protective structure for preventing elevation of the earth's surface caused by grouting reinforcement of a tunnel according to claim 1, wherein the thickness of the reverse camber (5) is 3-4m, and the thickness of the forward camber (11) is greater than 2m.
3. The protective structure for preventing earth's surface elevation caused by grouting reinforcement of a tunnel according to claim 1, wherein a vertical center line (9) of the tunnel body (8), a vertical center line of the forward camber (11), and a vertical center line of the reverse camber (5) are collinear.
4. The protective structure for preventing earth surface bulge caused by tunnel grouting reinforcement according to claim 1, wherein the top wall of the inner contour of the tunnel body (8) is provided with a leading grouting pipe (6) which is obliquely arranged towards the trend of the tunnel, and the outlet of the leading grouting pipe (6) is positioned between the coverage areas of the forward camber arch (11) and the reverse camber arch (5).
5. A tunnel advanced grouting method for preventing surface elevation based on the protective structure of claim 1, comprising the following steps:
A. surface drilling grouting
Before the tunnel is constructed to the section to be protected, surface drilling (2) is carried out on the stratum surface with a loose rock soil layer (4) right above the trend of the tunnel body, the drilling holes are arranged in a quincuncial shape, overlooking center connecting lines of the same row of drilling holes are perpendicular to the trend of the tunnel, the drilling hole depth at the center is the largest in the same row of drilling holes, the drilling hole depths from the center to two sides are gradually decreased, and the lower ends of the same row of drilling holes are all located in the reverse camber design range of the section where the drilling holes are located;
placing a repeatable grouting pipe (3) in the drilled hole, and grouting through the repeatable grouting pipe (3) to form an integral supporting structure by the slurry and the loose rock soil layer (4) to form a reverse camber (5) together;
B. tunnel support
When the tunnel is constructed to the section to be protected, firstly, mao Duanmian (15) of the tunnel body is dug out, primary spraying of concrete is carried out, a supporting structure is installed, and finally, the concrete is sprayed again;
C. tunnel drilling grouting
After re-spraying concrete for 1 day, forming a forward camber arch (11) by drilling and grouting around the top wall of the inner contour of the tunnel body;
D. advanced grouting
Performing advanced grouting between the reverse camber (5) and the forward camber (11);
E. bottom plate pouring
Concrete pouring is carried out on a bottom plate (10) of the tunnel, so that the section size of the tunnel meeting the design requirement is formed;
the grouting operation in the step A is as follows:
the lower end of the repeatable grouting pipe is not more than 10cm away from the bottom of the drill hole, initial grouting is firstly carried out, solidified slurry is injected into the grouting hole through the repeatable grouting pipe, the initial grouting adopts filling grouting, the grouting pressure is controlled to be less than 0.5Mpa, the used grouting liquid consists of 325# cement, an additive and water, and the ratio of the grouting liquid to the additive is 1:0.08:2;
after the initial grouting is finished for 2-3 hours, the slurry reaches an initial setting state, the slurry is primarily bonded with a loose rock layer and a sandy soil layer in a loose rock layer (4) to form a whole, after the initial grouting and the secondary grouting have a certain bearing strength, the secondary grouting is performed, the grouting pressure of the secondary grouting is larger than that of the primary grouting and is controlled to be smaller than 3Mpa, the reverse sectional grouting is adopted, the grouting is adopted to be 325# cement, an additive and water, the ratio of the grouting is 1:0.08:2, the reverse sectional grouting thickness is adopted to be 3-4m until a complete reverse curved arch (5) is formed, so that the effect of improving the strength of the loose rock layer is achieved, an internal grouting reinforcement body is formed through the initial grouting and the secondary grouting, and the internal grouting reinforcement body and the surrounding loose rock layer form a whole supporting structure to form a reverse curved arch (5) for bearing stress together.
6. The advanced grouting method for tunnel with earth surface bulge prevention according to claim 5, wherein the lower end of each of the repeatable grouting pipes (3) is equally spaced from the lower end face of the reverse camber.
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| CN201910511046.2A CN110118090B (en) | 2019-06-13 | 2019-06-13 | Protective structure for preventing earth surface bulge caused by tunnel grouting reinforcement |
| PCT/CN2020/070390 WO2020248596A1 (en) | 2019-06-13 | 2020-01-06 | Protection structure for preventing ground heave caused by tunnel grouting reinforcement and grouting method |
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| CN201910511046.2A CN110118090B (en) | 2019-06-13 | 2019-06-13 | Protective structure for preventing earth surface bulge caused by tunnel grouting reinforcement |
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| CN110118090B true CN110118090B (en) | 2024-03-22 |
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| CN110118090B (en) * | 2019-06-13 | 2024-03-22 | 河南理工大学 | Protective structure for preventing earth surface bulge caused by tunnel grouting reinforcement |
| CN110985055B (en) * | 2019-12-20 | 2021-04-09 | 中铁南方投资集团有限公司 | Tunnel grouting and drainage synchronous construction method for controlling surface uplift |
| CN112942307B (en) * | 2021-01-27 | 2022-10-25 | 山东大学 | Loose soil layer grouting reinforcement method and coastal karst area grouting reinforcement method |
| CN113153379B (en) * | 2021-04-27 | 2024-01-09 | 重庆永昂实业有限公司 | Tunnel waterproof and drainage system and construction process |
| CN113551655B (en) * | 2021-07-20 | 2023-04-07 | 杭州伟业建设集团有限公司 | Tunnel surpasses owes detection device and detecting system who digs |
| CN114483091B (en) * | 2021-12-02 | 2024-06-21 | 中南大学 | Sectional grouting method for tunnel greenhouse |
| CN114263163A (en) * | 2021-12-29 | 2022-04-01 | 成都大学 | Grouting reinforcement method for diversion culvert passing through gravel stratum in high and cold regions and construction method |
| CN114856578A (en) * | 2022-04-20 | 2022-08-05 | 中铁一局集团有限公司 | Freezing and in-hole grouting improved combined bearing stratum reinforcing scheme |
| CN115045299B (en) * | 2022-07-26 | 2024-02-02 | 杭州市西站枢纽开发有限公司 | Deep foundation pit side wall reinforcing structure with electroosmosis drainage function and construction method |
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