CN118223894A - Stratum reinforcing method for shield side-penetrating river bridge pile foundation - Google Patents
Stratum reinforcing method for shield side-penetrating river bridge pile foundation Download PDFInfo
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- CN118223894A CN118223894A CN202410651241.6A CN202410651241A CN118223894A CN 118223894 A CN118223894 A CN 118223894A CN 202410651241 A CN202410651241 A CN 202410651241A CN 118223894 A CN118223894 A CN 118223894A
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- 230000003014 reinforcing effect Effects 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 44
- 238000010276 construction Methods 0.000 claims abstract description 44
- 238000005553 drilling Methods 0.000 claims abstract description 28
- 230000005641 tunneling Effects 0.000 claims abstract description 10
- 230000002093 peripheral effect Effects 0.000 claims abstract description 3
- 229910000831 Steel Inorganic materials 0.000 claims description 33
- 239000010959 steel Substances 0.000 claims description 33
- 230000000149 penetrating effect Effects 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 27
- 239000002689 soil Substances 0.000 abstract description 22
- 230000000903 blocking effect Effects 0.000 abstract description 4
- 230000002045 lasting effect Effects 0.000 abstract description 2
- 239000002002 slurry Substances 0.000 description 22
- 230000002787 reinforcement Effects 0.000 description 11
- 239000007788 liquid Substances 0.000 description 10
- 238000009412 basement excavation Methods 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- 239000004568 cement Substances 0.000 description 6
- 238000004062 sedimentation Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000007710 freezing Methods 0.000 description 3
- 230000008014 freezing Effects 0.000 description 3
- 239000010438 granite Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 230000001360 synchronised effect Effects 0.000 description 3
- 230000005856 abnormality Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000002955 isolation 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
- 239000002390 adhesive tape Substances 0.000 description 1
- 238000009933 burial Methods 0.000 description 1
- 239000011083 cement mortar Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000001112 coagulating effect Effects 0.000 description 1
- 238000007596 consolidation process Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- ONCZQWJXONKSMM-UHFFFAOYSA-N dialuminum;disodium;oxygen(2-);silicon(4+);hydrate Chemical compound O.[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[Na+].[Na+].[Al+3].[Al+3].[Si+4].[Si+4].[Si+4].[Si+4] ONCZQWJXONKSMM-UHFFFAOYSA-N 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000004088 foaming agent Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
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- 239000011435 rock Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 229940080314 sodium bentonite Drugs 0.000 description 1
- 229910000280 sodium bentonite Inorganic materials 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000002352 surface water Substances 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/001—Improving soil or rock, e.g. by freezing; Injections
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D15/00—Handling building or like materials for hydraulic engineering or foundations
- E02D15/02—Handling of bulk concrete specially for foundation or hydraulic engineering purposes
- E02D15/04—Placing concrete in mould-pipes, pile tubes, bore-holes or narrow shafts
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D19/00—Keeping dry foundation sites or other areas in the ground
- E02D19/06—Restraining of underground water
- E02D19/12—Restraining of underground water by damming or interrupting the passage of underground water
- E02D19/18—Restraining of underground water by damming or interrupting the passage of underground water by making use of sealing aprons, e.g. diaphragms made from bituminous or clay material
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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
-
- 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
- E21D11/08—Lining with building materials with preformed concrete slabs
-
- 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
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/06—Making by using a driving shield, i.e. advanced by pushing means bearing against the already placed lining
- E21D9/0607—Making by using a driving shield, i.e. advanced by pushing means bearing against the already placed lining the shield being provided with devices for lining the tunnel, e.g. shuttering
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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)
- Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Structural Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Civil Engineering (AREA)
- Architecture (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
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- Soil Sciences (AREA)
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Abstract
A stratum reinforcing method for a shield side-crossing river bridge pile foundation comprises the following steps: s1, drilling and grouting on the ground of one side of an existing bridge pile foundation in a tunnel path to be shield-excavated to construct a plurality of variable cross-section isolators in multi-row staggered arrangement; s2, drilling and grouting a vault reinforcing layer above the contour line of the tunnel to be shield excavated; s3, carrying out shield tunneling construction in a contour line of a tunnel to be shield excavated, and applying a secondary wall to the outer wall of the duct piece above the tunnel through the duct piece grouting holes and then reinforcing the grouting layer; the tunnel peripheral stratum of the pile foundation area of the river-passing bridge is reinforced by the variable cross section isolator, the vault reinforcing layer and the secondary wall rear reinforcing grouting layer. The method can play the reinforcing roles of blocking underground water, compacting soil around pile foundation and improving the overall stability of local soil, solves the problems of long construction period, high cost and the like of the traditional reinforcing method, reduces the risk of shield crossing construction, and ensures the safe operation and lasting stability of the existing bridge.
Description
Technical Field
The invention relates to the technical field of underground construction, in particular to a stratum reinforcing method for a shield side-penetrating river bridge pile foundation.
Background
Along with the rapid development of the subway construction scale of China, more and more projects of subway lines penetrating through a three-dimensional urban road traffic network inevitably pass through the lower parts or the side surfaces of some existing municipal bridge foundations. The shield excavation construction can disturb surrounding soil layers, change the stable state of an original soil body and an existing underground structure, particularly the influence generated in the process of closely downwards penetrating or laterally penetrating bridge pile foundations is not negligible, and uneven settlement of the foundations and even unstable and damage of bridge span structures can be caused when the influence is severe. Due to the influence of complex geology, river-like wading, poor construction conditions and the like, once the shield tunnel has water inflow and the excavation face collapses, large-scale stratum settlement is easily caused, and the construction of crossing the bridge can face great potential safety hazards.
The existing reinforcement method adopted for the side-penetrating bridge pile foundation excavated by the shield method comprises the following steps: grouting method, filling pile isolation method, freezing method, etc. Grouting method mainly presses cement paste or other coagulating materials into soil to improve strength, water permeability and the like; the freezing method is to freeze water in the soil body into ice by utilizing a refrigeration technology, and improve the bearing capacity of the soil body while isolating a water outlet channel; the filling pile isolation rule is to space the existing bridge pile foundation and the underground tunnel by applying concrete filling columns, so that the disturbance influence of tunnel construction on the bridge pile foundation is reduced. The filling pile isolating method is limited by the clearance under the bridge, the pile forming period is long, and the freezing method construction has the characteristics of long period, high cost and the like. The grouting method is relatively simple and flexible in construction, but can be used for treating the conditions of upper soft and lower hard weathering grooves, river wading and the like, and the conditions of serious grouting of grouting reinforcement, difficult forming, poor water-proof performance and the like can occur.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a stratum reinforcing method for a bridge pile foundation of a shield side-penetrating river, which can play the roles of blocking underground water, compacting soil around the bridge pile foundation and improving the overall stability of local soil, solve the problems of long construction period, high cost and the like of the traditional reinforcing method, avoid accidents such as water inflow, ground subsidence collapse, bridge instability damage and the like of a shield tunnel, reduce the construction risk of shield crossing, and ensure the safe operation and lasting stability of the existing bridge.
A stratum reinforcing method for a shield side-crossing river bridge pile foundation comprises the following steps:
S1, drilling and grouting on the ground of one side of a to-be-shield tunnel passing through an existing bridge pile foundation to construct a plurality of variable cross-section separators which are arranged in a multi-row staggered mode, and combining and shielding the plurality of variable cross-section separators to form a waterproof curtain and a stratum reinforcing structure on one side of a contour line of the to-be-shield tunnel;
S2, drilling and grouting above the contour line of the tunnel to be shield-excavated to pour a vault reinforcing layer, wherein one side of the vault reinforcing layer is contacted and propped against the variable-section isolator;
s3, in a contour line of a tunnel to be shield-excavated, carrying out shield tunneling construction by downwards penetrating, and after the construction is completed, applying a secondary wall to the outer wall of the pipe piece above the tunnel through a pipe piece grouting hole and then reinforcing the grouting layer;
After the tunnel construction is completed, the tunnel peripheral stratum of the pile foundation area of the river-passing bridge is reinforced by the variable cross-section isolator, the vault reinforcing layer and the secondary wall rear reinforcing grouting layer.
In step S1, the bottom diameter of the variable-section separator is larger than the top diameter, and the bottom of the variable-section separator extends below the horizontal center line of the contour line of the tunnel to be shield-excavated.
In addition, the variable cross section isolator manufactured in the step S1 is provided with two rows and is distributed in a staggered way, the distance between the axis of the variable cross section isolator and the bridge pile foundation is not less than 3m, and the horizontal distance between the axis of the variable cross section isolator and the contour line of the tunnel to be shield-excavated is not less than 2m; the inclination angle of the variable cross section isolator is smaller than 10 degrees, the bottom of the variable cross section isolator extends to 3m below the horizontal central line of the contour line of the tunnel to be shield-excavated, the diameter of the top of the variable cross section isolator is 120mm, and the distance between two adjacent variable cross section isolators is 1m.
In addition, when the variable cross-section isolator manufactured in the step S1 is poured, the steel pipe with the holes is required to be inserted into the bottoms of the grouting holes, and the grouting steel with the holes is reserved in the variable cross-section isolator after pouring is completed and used as an internal support of the steel structure.
In step S2, the width of the dome reinforcement layer is greater than 2 times of the width of the bridge deck, one side of the dome reinforcement layer is supported on the variable cross-section isolator, and the orthographic projection range of the other side of the dome reinforcement layer horizontally protrudes out of the contour line of the tunnel to be excavated by the shield is not less than 2m.
And, a plurality of grouting holes are drilled on the ground before the vault reinforcing layer is applied in the step S2, the grouting holes are arranged in a plum blossom shape according to the interval of 1-2 m, and the bottoms of the grouting holes are drilled to be 1m above the contour line of the tunnel to be shield-excavated.
And in the step S3, the central angle of the reinforcing grouting layer behind the secondary wall relative to the axis of the profile line of the tunnel to be shield-excavated is 120 degrees.
The invention has the advantages and technical effects that:
(1) The stratum reinforcing method provided by the invention can fully play the roles of blocking underground water and compacting soil around the bridge pile foundation in the water-rich stratum by the double-liquid grouting mode, takes the steel pipe with holes as a framework to form the variable cross-section isolator, and forms a wall with certain strength, so that on one hand, the underground water is blocked from penetrating into a tunnel, and on the other hand, the shield is isolated from excavating, and the bridge foundation is prevented from deforming.
(2) According to the invention, the perforated steel pipe with a certain length is inserted into the side close to the bridge pile foundation in the river after the drilling, and the double-liquid slurry is injected into the steel pipe from bottom to top under the control of different grouting pressures to form the variable cross-section isolator with different cross sections.
(3) The ground deep hole grouting layer of the shield tunnel vault and the secondary wall rear reinforced arc grouting layer play a role in reinforcing together, so that the overall stability of surrounding rocks is improved, real-time settlement caused by shield excavation is reduced, and meanwhile, the waterproof pressure of the tunnel is reduced to meet the requirements.
(4) The stratum reinforcing method provided by the invention greatly reduces the construction risk of shield crossing, avoids the serious loss caused by tunnel water inflow, bridge collapse, pipeline damage and the like, is quick, simple and convenient in construction, has obvious reinforcing effect, and can be flexibly matched with shield excavation construction.
Drawings
FIG. 1 is a schematic cross-sectional view of a method of reinforcing a subterranean formation according to the present invention;
FIG. 2 is a top view of a method of formation consolidation according to the present invention;
FIG. 3 is a top plan view of a double-line construction of the method of reinforcing a subterranean formation of the present invention;
FIG. 4 is a schematic view of the structure of a steel pipe with grouting in a variable cross-section isolator hole in the invention;
in the figure: 1-a bridge pile foundation; 2-a variable cross-section separator; 3-a dome reinforcement layer; 4-reinforcing the grouting layer behind the secondary wall; 5-waiting for shield tunneling of a tunnel contour line; 6-a steel pipe; 7-bridge decks; 8-water pipe.
Detailed Description
For a further understanding of the nature, features, and efficacy of the present invention, the following examples are set forth to illustrate, but are not limited to, the invention. The present embodiments are to be considered as illustrative and not restrictive, and the scope of the invention is not to be limited thereto.
The invention discloses a stratum reinforcing method for a shield side-penetrating river bridge pile foundation, which comprises the following steps:
S1, drilling and grouting on the ground on one side of a pile foundation 1 of an existing bridge through which a tunnel to be shield-excavated passes to construct a plurality of variable cross-section separators 2 which are arranged in a multi-row staggered manner, and combining and shielding the variable cross-section separators to form a waterproof curtain and a stratum reinforcing structure on one side of a contour line 5 of the tunnel to be shield-excavated;
The specific construction steps of the step S1 are as follows:
1. measuring and positioning:
and (3) arranging grouting holes of the variable cross-section isolator and grouting holes of the shield tunnel vault reinforcing layer 3 according to the relative positions of the existing bridge pile foundation and the contour line of the tunnel to be shield excavated, and determining the reinforcing range, grouting depth and the like.
The diameter of grouting holes of the variable cross-section isolator between the bridge pile foundation and the tunnel is 120mm, the holes are arranged in two rows or three rows according to equilateral triangles with a distance of 1m, the distance between the center of the hole and the bearing platform measured at the outermost side is not less than 3m, the distance between the center of the hole at the innermost side and the contour line of the tunnel is not less than 2m, the angle of the grouting holes is not more than 10 degrees when the grouting holes are required to be obliquely arranged, and the depth of the grouting holes is not more than 3m below the burial depth of the transverse axis of the tunnel.
Planar extent of the dome reinforcement layer: the longitudinal direction is preferably larger than 2 times of the width of the bearing platform or the bridge deck 7 and is transversely larger than the contour line of the tunnel to be shield-excavated by 2m, grouting holes are arranged in a quincuncial shape according to the interval of 1-2 m, and the hole bottom is drilled to the position 1m above the arch top of the contour line of the tunnel to be shield-excavated.
2. Drilling:
the drilling operation can be implemented by using a small geological drilling machine, and the position deviation of all drilling planes is controlled within 50mm, the inclination is less than 1%, and the depth deviation is controlled within 150 mm. And drilling according to a preset point position after the machine tool is in place, wherein slow drilling is adopted when the machine tool is used for drilling, the machine tool is shifted to a normal drilling speed after the drilling depth is 50cm, and the angle is checked at any time and corrected in time in the drilling process.
In order to avoid hole collapse or incapability of maintaining the subsequent grouting pressure, interval type drilling and grouting are used, namely single-number holes are drilled first, and double-number holes are drilled after grouting is completed.
If the steel pipe 6 or the grouting pipe is difficult to insert after drilling is finished, the condition that the grouting hole is inclined or necked is possibly caused, and the drilling is needed to be repeated or the hole is scanned repeatedly until the requirement is met. If the stratum is extremely weak and the groundwater is abundant and difficult to form holes, the improvement of the drilling mud quality or the adoption of a pipe-following drilling process are considered.
3. Slurry configuration:
The cement slurry adopts double-liquid slurry with quick setting and good waterproof performance, cement slurry and water glass are respectively mixed and injected by a double-liquid variable grouting pump according to the volume ratio of 1:1, the cement slurry water-cement ratio is 1:1, the water glass concentration is controlled to be 40 Baume degrees, and the cement slurry is diluted by water 1:1. If the slurry is found to be seriously run, the slurry proportion is adjusted in time, and the initial setting time is reduced.
The slurry concentration at the beginning of grouting should be lower, and the concentration is gradually increased to the designed concentration. And firstly, two holes are used as test holes, and key construction parameters such as grouting diffusion radius, grouting pressure, single-hole grouting quantity and the like are preliminarily determined and adjusted. The grouting radius is generally designed to be 80-120 cm, and can be estimated according to the following formula:
wherein R is grouting diffusion radius (cm), k is permeability coefficient (cm/s) of soil layer, P is grouting pressure (Mpa), t is grouting time(s), n is soil void fraction, and beta is slurry specific gravity.
4. Grouting construction of a variable cross section isolator:
After drilling and forming, inserting a steel pipe with an opening, wherein the outer diameter of the steel pipe is 108mm, the wall thickness of the steel pipe is 3-5 mm, and the steel pipe is a hot-rolled seamless steel pipe with the section length of 4m and 6m, and the steel pipe is connected by screw threads. The pipe orifice section of the steel pipe is 2.5m free of holes, and the grouting holes with the diameters of 15-20 mm are longitudinally staggered according to the intervals of 20-30 cm and the circumferential intervals of 10cm, and are sealed by waterproof adhesive tapes to prevent blockage. The bottom of the foremost section of the steel pipe is in a contracted shape so as to be conveniently inserted into the hole, the lengths of the spliced steel pipes are matched on site, joints at the same section of the steel pipe within the range of 5m nearby are ensured to be staggered, and finally the length of the spliced steel pipe is consistent with the set length of grouting.
After the steel pipe is inserted, gaps between the steel pipe and the hole wall within 30cm below the ground and between the grouting pipe and the steel pipe wall can be plugged by a grouting plug, and air outlet holes are formed. The back-type double-liquid grouting is carried out in the pipe from bottom to top, the grouting is started from the bottom of the hole, and the grouting length is generally in the range from 3m below the buried depth of the transverse axis of the tunnel to 3m below the ground surface. The grouting pressure is set according to three descending gradients from bottom to top, the grouting pressure in the range of 30-20 m of the underground, namely h3, is controlled to be 0.8-0.6 MPa, the grouting pressure in the range of 20-10 m of the underground is controlled to be 0.6-0.3 MPa, and the grouting pressure in the range of 10-3 m of the underground is controlled to be within 0.3 MPa. Lifting by 0.5-0.8 m in each step of back grouting, controlling the slurry flow at a constant speed and stabilizing the pressure for 10min, wherein the grouting step is completed. This cycle is followed by grouting while lifting to a set height. And after the single-hole grouting length meets the requirement, the residual length of the drilled hole is filled and compacted by using plain concrete.
Grouting construction sequence is constructed from outside to inside and from two sides to the direction close to the bridge pile foundation. Gradually constructing from the outermost row of grouting holes near the bridge pile foundation side of the river to the contour line side of the tunnel to be shield-excavated, and synchronously constructing each row of holes and grouting from two sides to the center of the bearing platform or the bridge pile foundation. The grouting quantity is uniform, the grouting pressure is stable and fast, the grouting body is well molded, or the reinforcement condition is timely judged by adopting drilling coring, so that the subsequent slurry configuration is adjusted.
S2, drilling and grouting above the contour line of the tunnel to be shield-excavated to pour a vault reinforcing layer, wherein one side of the vault reinforcing layer is contacted and propped against the variable-section isolator;
The specific construction steps of the step S2 are as follows:
And after the construction of the variable cross-section isolator between the bridge pile foundation and the tunnel is completed, the soil body in the range of more than 1m and 5m above the top of the tunnel is continuously pre-grouting and reinforced. The grouting material adopts double-liquid or single-liquid slurry according to the condition of underground water, and the grouting pressure is controlled to be 0.3-0.5 MPa. And the final pressure is controlled to be not more than 0.5Mpa by adopting a grouting amount and pressure double control measure.
After drilling to the designed depth, the grouting pipe is inserted to perform grouting from bottom to top, and the back type grouting is adopted. The length of each grouting section is about 0.6m, and the grouting pressure is slowly increased to the specified pressure and then stabilized for 10min. After the first section of slurry is injected, a slurry injection core pipe is lifted up, and the second section of slurry injection construction is carried out until the reinforcement of 5m range above the arch top is completed. If slurry leakage and slurry overflow occur in the process, the concentration of the slurry should be properly increased and the setting time should be reduced so as to avoid the influence of slurry leakage on the reinforcing effect. And when the grouting amount of the last section of grouting is smaller and smaller, the grouting reaches the final grouting pressure and lasts for half an hour, the grouting of the hole is completed, and then the hole is sealed to the ground by plain concrete or cement mortar.
The grouting pressure and the slurry amount in the whole grouting process should be recorded once per minute, and the grouting pressure is used as the main and the grouting amount is used as the auxiliary for controlling. And taking the constant pressure reaching the designed grouting final pressure as a first control principle, and if the grouting pressure does not rise for a long time, performing grouting control according to a quantitative standard. The control mode is also suitable for grouting construction of the variable cross-section isolator.
Grouting holes of the vault reinforcing layer are arranged in a quincuncial shape with a distance of 1-2 m, the construction sequence is gradually improved from inside to outside, the water permeability of the vault weak layer is gradually improved, and the underground water of the soil layer in the range is jacked to the far distance, so that a plate reinforcing structure is formed.
S3, in a contour line of a tunnel to be shield-excavated, carrying out shield tunneling construction by downwards penetrating, and after the construction is completed, applying a secondary wall to the outer wall of the pipe piece above the tunnel through a pipe piece grouting hole and then reinforcing the grouting layer 4;
The specific construction steps of the step S3 are as follows:
In the shield tunneling process, slag soil is mixed and improved by adopting a foaming agent and high-quality sodium bentonite, related tunneling parameters are strictly controlled, splicing quality of the segments is strictly controlled, and synchronous grouting construction is enhanced.
After the shield tail is separated from 4-5 rings, secondary wall post-reinforcing grouting is implemented by utilizing the range of 120 DEG of the reserved grouting Kong Duigong parts of the duct pieces, and double-liquid grouting is used as grouting materials. The arc grouting layer and the ground deep hole grouting layer of the shield tunnel vault jointly play a role in reinforcement, so that the overall stability of soil is improved, sedimentation caused by shield excavation is reduced, and meanwhile, the waterproof pressure of the tunnel is reduced.
According to relevant construction experience, when the tunneling construction is carried out under the geological conditions, the total thrust of the shield is preferably controlled to be 2000-2200 t, the torque is preferably controlled to be 2000-3000 KN m, the soil pressure of the soil warehouse is kept to be 0.25-0.27 Mpa, the propelling speed is kept to be 20-30 mm/min, and the synchronous grouting amount is 11-12 m 3/ring.
In order to more clearly describe the specific embodiments of the present invention, a construction example is provided below:
As shown in FIG. 3, in the section from Guangzhou subway No. 18 line Guanan No. 2 well to middle wind well, double-line shield construction needs to pass through a Longmei middle bridge, the intersection angle of the bridge and the tunnel axis is about 40 degrees, the horizontal distance between the left-side tunnel and the bridge pile foundation is 5-6 m and is close to a river channel, the urban water channel is a side stream of the Zhujiang river, the water flow is large, and the surface water is extremely rich. The tunnel axis buries deeply about 25~28m, and the geology of being located is from top to bottom with plain fill, cohesive soil, full weathered mixed granite, and strong weathered mixed granite, and the soft top and hard bottom funnel formula weathered groove has been formed to the well weathered mixed granite layer. If the shield is tunneled up to this point, the water outlet channel is formed to cause the abnormality of water inflow, sedimentation collapse and the like of the tunnel, the crossing risk is greatly increased, and a phi 1000 tap water pipe 8 is arranged above the contour line of the tunnel to be tunneled, the material is DN1000 steel pipe, the pipe wall is 1cm, and the crossing length of the tunnel is about 46m. The water pipe is the only main water pipe for daily life in the luxury area from the south to the north, the water supply amount reaches 9 ten thousand meters per day, and the water pressure is 0.3Mpa. According to the relevant regulations, the absolute sedimentation of the pipeline is required to be less than 30mm, and the local inclination value between two joints is required to be less than 2mm; the accumulated sedimentation control value of the built bridge abutment is less than or equal to 20mm, and the sedimentation difference of the adjacent abutment is less than or equal to 2mm. Therefore, the settlement control requirements of the upper building (structure) of the shield tunnel are strict, for example, the shield tunneling forms a water outlet channel so far to cause the abnormality of tunnel water inflow, settlement collapse and the like, the crossing risk is greatly increased, and the existing bridge traffic safety and pipeline water supply operation are seriously influenced.
The stratum reinforcing method for the shield side-penetrating river bridge pile foundation comprises the following concrete construction steps:
In the above engineering examples, a combined stratum reinforcing structure using ground grouting as a main means is designed according to the relative positions of the built bridge foundation and the important pipelines. And a variable cross section isolator is arranged between the bridge pile foundation and the contour line of the tunnel to be shield-excavated, double-liquid grouting is adopted for the steel pipe, the outer diameter of the used steel pipe is 108mm, the wall thickness is 3-5 mm, and the steel pipe is a hot rolling seamless steel pipe with the section length of 4m and 6m, and screw thread connection or field welding is adopted. The sections 2.5m away from the steel pipe opening are not perforated, and the guniting holes with the diameters of 10-15 mm are longitudinally staggered according to the interval of 20-30 cm and the circumferential interval of 10 cm. The grouting pressure is set according to three descending gradients from bottom to top, the grouting pressure in the range of 30-20 m underground is controlled to be 0.8-0.6 MPa, the grouting pressure in the range of 20-10 m underground is controlled to be 0.6-0.3 MPa, and the grouting pressure in the range of 10-3 m underground is controlled to be within 0.3 MPa. The grouting holes are arranged in two or three rows according to equilateral triangles with 1m intervals, and after construction, the variable-section isolator with the upper width of 2m, the lower width of 3m, the longitudinal length of 50m and the height of about 22m and containing steel pipes as a framework is formed, so that the variable-section isolator plays an important role in blocking underground water and isolating shield excavation to cause bridge foundation deformation.
Because the longitudinal rigidity of the upper pipeline is smaller, the joints are more, so that the pipeline is prevented from being damaged by a settling tank formed by shield excavation, a vault reinforcing layer is further formed by utilizing ground grouting within a range of 1m and more of 5m, and the influence of settling effect on the upper soil body is reduced. The grouting holes strictly avoid the trend of pipelines and draw a safety area with an interval of 2m, deep hole back single-liquid grouting is adopted, the grouting depth is in the range of 1m and 5m above of a vault, quincuncial arrangement is carried out according to the interval of 2m, and the plane reinforcement range is 50m x 15m.
On the other hand, the shield underpass construction is strictly controlled, so that the construction risk is reduced. The total thrust in the shield tunneling process is controlled at 2000-2500 t, the torque is 2000-3000 KN m, the soil pressure of the soil bin is kept at 0.25-0.27 Mpa, the propelling speed is kept at 20-30 mm/min, the synchronous grouting amount is ensured to be 11-12 m 3/ring, and temporary stop is avoided. And simultaneously, after the shield tail is separated from 4-5 rings, carrying out secondary wall post-reinforcing grouting by utilizing the range of 120 DEG of the grouting Kong Duigong reserved by the duct piece.
Finally, the invention adopts the mature products and the mature technical means in the prior art.
While the methods and techniques of the present invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the art from this disclosure that variations and rearrangements of the methods and techniques can be made by those skilled in the art to arrive at a final preparation technique without departing from the spirit and scope of the invention. It is expressly intended that all such similar substitutes and modifications apparent to those skilled in the art are deemed to be included within the spirit, scope and content of the invention. And it should be understood that modifications and variations can be made by those skilled in the art in light of the foregoing description and all such modifications and variations are intended to be included within the scope of the invention as defined in the following claims.
Claims (7)
1. The stratum reinforcing method of the pile foundation of the shield side-penetrating river bridge is characterized by comprising the following steps of:
S1, drilling and grouting on the ground of one side of a to-be-shield tunnel passing through an existing bridge pile foundation to construct a plurality of variable cross-section separators which are arranged in a multi-row staggered mode, and combining and shielding the plurality of variable cross-section separators to form a waterproof curtain and a stratum reinforcing structure on one side of a contour line of the to-be-shield tunnel;
S2, drilling and grouting above the contour line of the tunnel to be shield-excavated to pour a vault reinforcing layer, wherein one side of the vault reinforcing layer is contacted and propped against the variable-section isolator;
s3, in a contour line of a tunnel to be shield-excavated, carrying out shield tunneling construction by downwards penetrating, and after the construction is completed, applying a secondary wall to the outer wall of the pipe piece above the tunnel through a pipe piece grouting hole and then reinforcing the grouting layer;
after the tunnel construction is completed, the tunnel peripheral stratum of the pile foundation area of the river-passing bridge is reinforced by the variable cross-section isolator, the vault reinforcing layer and the secondary wall rear reinforcing grouting layer.
2. The stratum reinforcing method of the shield side-through river bridge pile foundation according to claim 1, which is characterized by comprising the following steps: in the step S1, the bottom diameter of the variable-section separator is larger than the top diameter, and the bottom of the variable-section separator extends below the horizontal midline of the contour line of the tunnel to be shield-excavated.
3. The stratum reinforcing method of the shield side-through river bridge pile foundation according to claim 2, which is characterized by comprising the following steps: the variable cross-section isolator manufactured in the step S1 is provided with two rows and is distributed in a staggered manner, the distance between the axis of the variable cross-section isolator and the bridge pile foundation is not less than 3m, and the horizontal distance between the axis of the variable cross-section isolator and the contour line of the tunnel to be shield-excavated is not less than 2m; the inclination angle of the variable cross section isolator is smaller than 10 degrees, the bottom of the variable cross section isolator extends to 3m below the horizontal central line of the contour line of the tunnel to be shield-excavated, the diameter of the top of the variable cross section isolator is 120mm, and the distance between two adjacent variable cross section isolators is 1m.
4. The stratum reinforcing method of the shield side-through river bridge pile foundation according to claim 2, which is characterized by comprising the following steps: when the variable cross-section isolator manufactured in the step S1 is poured, the steel pipe with the holes is required to be inserted into the bottoms of the grouting holes, and the grouting steel with the holes is reserved in the variable cross-section isolator after pouring is completed and used as an internal support of the steel structure.
5. The stratum reinforcing method of the shield side-through river bridge pile foundation according to claim 1, which is characterized by comprising the following steps: in the step S2, the width of the vault reinforcing layer is 2 times larger than that of the bridge deck, one side of the vault reinforcing layer is propped against the variable cross-section isolator, and the orthographic projection range of the outline of the tunnel to be shield-excavated horizontally extends out of the other side of the vault reinforcing layer is not smaller than 2m.
6. The stratum reinforcing method of the shield side-through river bridge pile foundation according to claim 1, which is characterized by comprising the following steps: and (2) drilling a plurality of grouting holes on the ground before the vault reinforcing layer is formed in the step (S2), wherein the grouting holes are arranged in a plum blossom shape according to the interval of 1-2m, and the bottoms of the grouting holes are drilled to be 1m above the contour line of the tunnel to be shield-excavated.
7. The stratum reinforcing method of the shield side-through river bridge pile foundation according to claim 1, which is characterized by comprising the following steps: and in the step S3, the central angle of the reinforcing grouting layer behind the secondary wall relative to the axis of the profile line of the tunnel to be shield-excavated is 120 degrees.
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