CN110700842A - Advanced grouting reinforcement method suitable for water-rich sand layer section of shield end - Google Patents
Advanced grouting reinforcement method suitable for water-rich sand layer section of shield end Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 56
- 230000002787 reinforcement Effects 0.000 title claims abstract description 51
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 51
- 239000004576 sand Substances 0.000 title claims abstract description 38
- 239000002002 slurry Substances 0.000 claims abstract description 51
- 238000012544 monitoring process Methods 0.000 claims abstract description 49
- 238000006073 displacement reaction Methods 0.000 claims abstract description 46
- 239000004746 geotextile Substances 0.000 claims abstract description 40
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 23
- 230000000694 effects Effects 0.000 claims abstract description 20
- 239000004568 cement Substances 0.000 claims abstract description 19
- 238000013461 design Methods 0.000 claims abstract description 18
- 239000011440 grout Substances 0.000 claims abstract description 15
- 230000008569 process Effects 0.000 claims abstract description 15
- 238000005553 drilling Methods 0.000 claims abstract description 12
- 239000000463 material Substances 0.000 claims abstract description 12
- 239000011435 rock Substances 0.000 claims abstract description 8
- 238000004519 manufacturing process Methods 0.000 claims abstract description 5
- 239000007788 liquid Substances 0.000 claims description 17
- 238000007596 consolidation process Methods 0.000 claims description 6
- 235000019353 potassium silicate Nutrition 0.000 claims description 5
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 5
- 238000012360 testing method Methods 0.000 claims description 5
- 238000003825 pressing Methods 0.000 claims description 4
- 230000005641 tunneling Effects 0.000 claims description 3
- 238000010276 construction Methods 0.000 description 7
- 238000009412 basement excavation Methods 0.000 description 5
- 238000009792 diffusion process Methods 0.000 description 5
- 238000001125 extrusion Methods 0.000 description 5
- 238000007689 inspection Methods 0.000 description 5
- 230000014759 maintenance of location Effects 0.000 description 5
- 238000005507 spraying Methods 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000005056 compaction Methods 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 230000002411 adverse Effects 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000003487 anti-permeability effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009933 burial Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001879 gelation Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/001—Improving soil or rock, e.g. by freezing; Injections
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
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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
- E21D9/08—Making by using a driving shield, i.e. advanced by pushing means bearing against the already placed lining with additional boring or cutting means other than the conventional cutting edge of the shield
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- Environmental & Geological Engineering (AREA)
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- Soil Sciences (AREA)
- Civil Engineering (AREA)
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
Abstract
The invention discloses an advanced grouting reinforcement method suitable for a water-rich sand layer at a shield end, which solves the problems that cement slurry is difficult to effectively reserve in the water-rich sand layer, slurry is easy to return upwards and run out in the grouting process and the like in the prior art, and can effectively reinforce the water-rich sand layer at the shield end. The technical scheme is as follows: the method comprises the following steps: determining a target reinforcing area and designing a grouting drill hole; arranging ground surface deformation monitoring points and station structure displacement monitoring points; manufacturing an orifice pipe with a geotextile bag; drilling a grouting drill hole and putting an orifice pipe in the grouting drill hole; grouting the geotextile bag, compacting surrounding strata, and constructing a grout stopping rock tray; carrying out forward segmented grouting on a target reinforcement area by adopting a quick-setting grouting material, and monitoring surface deformation and station structure displacement in real time in the grouting process; performing feedback adjustment on grouting design through surface deformation and station structure displacement monitoring data; and finishing grouting work of all grouting drill holes and checking grouting effect.
Description
Technical Field
The invention relates to the field of tunnels and underground engineering, in particular to an advanced grouting reinforcement method suitable for a water-rich sand layer section at the end of a shield.
Background
When the shield is started or subjected to tunneling construction in the shield end area, the stress state of the stratum changes suddenly, the stability of the stratum is poor, and particularly when the shield end area is positioned on a water-rich sand layer, because the water-rich sand layer has the characteristics of loose structure, strong water-rich property, poor self-stability and the like, sand collapse accidents are easy to happen, and the shield cannot tunnel.
The existing shield end head reinforcing method mainly comprises a jet grouting method, a dewatering method, a sleeve valve pipe grouting method and the like, wherein the jet grouting method mainly adopts a high-pressure jet technology to forcedly cut and stir a stratum and cement slurry to form a jet grouting pile body, and then a continuous reinforcing body is formed by occlusion among different jet grouting piles, so that the aim of stratum reinforcing and water stopping is finally achieved. The inventor finds that cement slurry is difficult to effectively remain in a water-rich sand layer in the rotary spraying construction process of the water-rich sand layer, so that the pile forming effect is poor, the engagement degree of a rotary spraying pile is not high, and the stratum reinforcing effect is difficult to meet the reinforcing requirement of a shield end.
The dewatering method is mainly used for pumping water to a target stratum so as to reduce the water content of the stratum and further achieve the purpose of improving the performance of the stratum, however, the dewatering causes the settlement of the surrounding stratum, so that the dewatering method is difficult to be applied to urban environments with densely distributed buildings and municipal pipelines. The sleeve valve pipe grouting method achieves the purpose of anti-permeability reinforcement by implementing retreating type grouting from the deep part of the stratum to the shallow part of the stratum. The method has three disadvantages when being applied to a water-rich sand layer, namely, the slurry retention rate and the grouting pressure in a target reinforcement area are low and the reinforcement effect is difficult to guarantee due to the fact that the slurry stopping measure of a sleeve valve pipe grouting method is weak and the problem that slurry returns upwards and runs out easily in the grouting process; secondly, slurry is easy to diffuse in the shallow part of the stratum, so that the ground surface is obviously raised, and if municipal pipelines exist on the ground surface, the safety of the municipal pipelines can be seriously threatened; thirdly, the water-rich sand layer is difficult to drill, the hole collapse of the drill hole is serious, the sleeve valve pipe is difficult to install in place, and the construction efficiency is low.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides an advanced grouting reinforcement method suitable for the water-rich sand section of the shield end, which has the effect of effectively reinforcing the water-rich sand section of the shield end.
The invention adopts the following technical scheme:
an advanced grouting reinforcement method suitable for a water-rich sand interval at a shield end comprises the following steps:
the method comprises the following steps: determining a target reinforcing area and designing a grouting drill hole;
step two: arranging ground surface deformation monitoring points and station structure displacement monitoring points;
step three: manufacturing an orifice pipe with an expandable geotextile bag;
step four: drilling a grouting drill hole and putting an orifice pipe in the grouting drill hole;
step five: grouting the geotextile bag positioned in the grouting drill hole, compacting surrounding strata, and constructing a grout stopping rock disk;
step six: carrying out forward segmented grouting on a target reinforcement area by adopting a quick-setting grouting material, and monitoring surface deformation and station structure displacement in real time in the grouting process;
step seven: performing feedback adjustment on grouting design through surface deformation and station structure displacement monitoring data;
step eight: and finishing grouting work of all grouting drill holes and checking grouting effect.
Further, in the first step, the plane range of the target reinforcement area is expanded by 3-4 m from the contour line of the shield tunnel in the direction vertical to the axis of the shield tunnel, and is translated by 6-8 m from the boundary of the station enclosure structure in the direction parallel to the axis of the shield tunnel; the vertical range of the target reinforcing area is that the height line of the arch top of the shield tunnel moves upwards by 3-4 m, and the height line of the arch bottom of the shield tunnel moves downwards by 1-1.5 m.
Furthermore, in the second step, the arrangement range of the ground surface deformation monitoring points is a set distance for the plane range of the target reinforcement area to be expanded, and the distance between adjacent ground surface deformation monitoring points is 3-5 m;
the displacement monitoring points of the station structure are arranged on the station enclosure structure, the distance between every two adjacent displacement monitoring points of the station structure is 3-5 m, and the displacement monitoring direction is the horizontal direction.
Furthermore, a flange plate is arranged at the top of the orifice pipe, and a grouting valve is arranged above the flange plate; the end of the orifice tube is flush with the upper boundary of the target consolidation area.
Furthermore, the geotextile bag is fixed on the outer side of the orifice pipe, a grouting pipe is arranged on one side of the orifice pipe, and the tail end of the grouting pipe extends into the geotextile bag.
Further, in the fifth step, rapid-hardening type slurry is adopted to carry out grouting on the geotextile bag through a grouting pipe, and the gel time of the rapid-hardening type slurry is less than 20 s.
Further, in the sixth step, a cement-water glass double-liquid slurry is adopted as the quick-setting grouting material, the water-cement mass ratio of the cement slurry is controlled to be 0.8-1 when W/C is equal to W/C, and the double-liquid volume ratio of the cement slurry to the water glass slurry is controlled to be 3-4: 1 when C: S is equal to S.
Further, in the sixth step, when the grouting pressure reaches the design grouting final pressure and the grouting amount reaches 80% of the design grouting amount, stopping grouting, when the grouting amount reaches 1.5 times of the design grouting amount and the grouting pressure does not reach the design grouting final pressure, stopping grouting, when the grouting pressure does not reach the design grouting final pressure and the grouting amount does not reach the design grouting amount, and when the ground surface deformation or the station structure displacement exceeds the early warning value, stopping grouting.
Further, in the seventh step, when the maximum ground surface uplift deformation amount caused by single grouting exceeds 0.3cm or the station structure displacement exceeds 0.2cm, the design grouting amount is reduced.
Further, in the eighth step, the grouting effect check includes a water pressing test, a drill coring and a drill television exploration.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the invention, the expandable geotextile bag is used for applying extrusion force to the stratum above the target reinforcement area, the stratum around the geotextile bag is compacted to form a stratum compaction area, the capability of the stratum to resist the fracture of slurry splitting is improved, and a slurry stopping rock tray is formed above the target reinforcement area through the lap joint of a plurality of stratum compaction areas, so that slurry is prevented from returning upwards in the grouting process;
(2) the rapid hardening slurry is adopted, the diffusion range of the slurry is effectively limited by utilizing the rapid hardening characteristic, and the retention rate of the slurry in a target reinforcing area is finally greatly improved, so that the grouting reinforcing effect is greatly improved, and the requirements of shield launching and receiving on the mechanical property of the stratum at the end of the shield are met;
(3) compared with a rotary spraying method and a sleeve valve pipe grouting method, the method can achieve a better water-rich sand layer reinforcing effect, and effectively ensures the construction safety in the starting and receiving processes of the shield; compared with a sleeve valve pipe grouting method, the method can prevent the grout from diffusing in the shallow part of the stratum and avoid the over-limit of the surface uplift value; compared with a rotary spraying method, the method has the advantages of simple equipment, high construction efficiency, shortened whole operation time and lower cost.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.
Fig. 1 is a plan view of a target reinforcement area of a water-rich sand interval of a shield tunnel according to a first embodiment of the present invention;
FIG. 2 is a longitudinal section of a target reinforcement area of a water-rich sand interval of a shield tunnel according to a first embodiment of the present invention;
fig. 3 is a cross-sectional view of a target reinforcement area of a water-rich sand interval of a shield tunnel according to a first embodiment of the present invention;
FIG. 4 is a schematic diagram of a stop-grouting rock formation and forward grouting according to a first embodiment of the invention;
the method comprises the following steps of 1, shield tunneling, 2, a water-rich sand layer, 3, a target reinforcing area, 4, grouting and drilling, 5, a station enclosure structure, 6, a ground surface deformation monitoring point, 7, a station structure displacement monitoring point and 8, and the arrangement range of the ground surface deformation monitoring point; 9. the method comprises the following steps of surface, 10, geotextile bags, 11, orifice pipes, 12, flange plates, 13, grouting valves, 14, grouting pipes, 15, grout stopping rock plates, 16, stratum compaction areas, 17, a first grouting section, 18, a second grouting section, 19 and a third grouting section.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an", and/or "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof;
for convenience of description, the words "up", "down", "left" and "right" in this application, if any, merely indicate correspondence with the directions of up, down, left and right of the drawings themselves, and do not limit the structure, but merely facilitate the description of the invention and simplify the description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the application.
The terms "mounted", "connected", "fixed", and the like in the present application should be understood broadly, and for example, the terms "mounted", "connected", and "fixed" may be fixedly connected, detachably connected, or integrated; the two components can be connected mechanically or electrically, directly or indirectly through an intermediate medium, or connected internally or in an interaction relationship, and the terms used in the present invention should be understood as having specific meanings to those skilled in the art.
As introduced in the background art, the problems that cement grout is difficult to effectively retain in a water-rich sand layer, grout is easy to return and run in the grouting process and the like exist in the prior art, and in order to solve the technical problems, the invention provides an advanced grouting reinforcement method suitable for the water-rich sand layer section of a shield end.
The first embodiment is as follows:
the present invention is described in detail below with reference to fig. 1 to 4, and specifically, the structure is as follows:
the embodiment provides an advanced grouting reinforcement method suitable for a water-rich sand layer section of a shield end, which can realize effective reinforcement of a water-rich sand layer 2 of the shield end, and comprises the following steps:
the method comprises the following steps: determining a target reinforcement area 3 and designing a grouting drill hole 4;
in order to ensure the excavation stability of the tunnel, the range of the target reinforcing area is larger than a certain limit value, and the range of the target reinforcing area cannot be too large in consideration of engineering economy, so that the plane range of the target reinforcing area 3 is expanded by 3-4 m from the contour line of the shield tunnel 1 in the direction vertical to the axis of the shield tunnel 1, and is translated by 6-8 m from the boundary of the station enclosure structure 5 in the direction parallel to the axis of the shield tunnel 1.
The excavation safety risk of the vault part in the tunnel excavation process is larger than that of the vault part, so that the upward moving length of the vertical range of the target reinforcement area from the vault height line of the shield tunnel is larger than the downward moving length of the vault height line of the shield tunnel. In the embodiment, the vertical range of the target reinforcement area 3 is that the height line of the arch top of the shield tunnel 1 moves up by 3-4 m, and the height line of the arch bottom of the shield tunnel 1 moves down by 1-1.5 m. The grouting drill holes 4 are arranged in a quincunx mode, and the distance between every two adjacent grouting drill holes 4 is generally 1.5-2.5 m.
Step two: arranging a ground surface deformation monitoring point 6 and a station structure displacement monitoring point 7;
the ground surface deformation and the station structure displacement caused by the grouting process are not uniform in the ground surface area, so that the arrangement of the ground surface deformation monitoring points and the station structure displacement monitoring points meets certain density requirements to meet the monitoring precision requirement. As shown in fig. 1, the arrangement range 8 of the ground surface deformation monitoring points is 3m of the plane range of the target reinforcing area 3, and the distance between adjacent ground surface deformation monitoring points 6 is 3-5 m; the station structure displacement monitoring points 7 are arranged on the station enclosure structure 5, the distance between every two adjacent station structure displacement monitoring points 7 is 3-5 m, and the displacement monitoring direction is the horizontal direction.
Step three: manufacturing an orifice pipe 11 with an expandable geotextile bag 10;
the top of the orifice pipe 11 is provided with a flange 12, and in this embodiment, the flange 12 is welded and fixed with the orifice pipe 11. The diameter of the orifice pipe 11 can be selected according to actual conditions, and the orifice pipe 11 of the present embodiment adopts a steel sleeve pipe with a diameter of 108 mm. And a grouting valve 13 is arranged above the flange plate 12.
The geotextile bag 10 is fixed on the outer side of the orifice pipe 11, a grouting pipe 14 is welded on one side of the orifice pipe 11, the tail end of the grouting pipe 14 extends into the geotextile bag 10, and the top end of the grouting pipe 14 is located near the flange plate 12. The grouting pipe 14 is a steel pipe, the geotextile bag 10 is made of high-strength geotextile, two ends of the geotextile bag 10 are bound and fixed on the orifice pipe 11, and one end of the geotextile bag is bound at the tail end of the orifice pipe 11. The length of the geotextile bag is 1.5-2.5 m, and the perimeter of the geotextile bag is 1-1.3 m.
Step four: a grout borehole 4 is drilled below the surface 9 and an orifice tube 11 is lowered into the grout borehole 4 so that the end of the orifice tube 11 is flush with the upper boundary of the target consolidation area 3.
Step five: grouting is carried out on the geotextile bags 10 positioned in the grouting drill holes 4, surrounding strata are compacted, and a grout stopping rock disk 15 is constructed.
Further, quick-setting type slurry is adopted to carry out grouting on the geotextile bag 10 through the grouting pipe 14, the grouting pressure is 2-3 MPa, the gelling time of the quick-setting type slurry is less than 20s, and the volume of the slurry after gelling is stable and does not shrink. The purpose of grouting the geotextile bag by adopting the quick-setting type slurry is to reduce the water precipitation amount of slurry concretion bodies in the geotextile bag, wherein the water precipitation can cause the volume shrinkage of the slurry concretion bodies, and further the extrusion stress of the geotextile bag to surrounding strata is reduced. The adoption of the quick-setting slurry can effectively shorten the slurry gelling time, reduce the slurry precipitation amount, keep the slurry stone volume stable and maintain the extrusion stress of the geotextile bag to the surrounding stratum.
Exerting the extrusion force to the stratum around through the inflation effect of geotechnological sack 10, crowded stratum forms stratum crowded district 16 around, its intensity is far higher than original stratum after the stratum is crowded densely, and then the ability of resisting the fracture of thick liquid splitting destruction is showing and is strengthened, after a plurality of geotechnological sacks 10 expand, adjacent stratum crowded district overlap joint each other, can form only thick liquid rock-tray 15 above target reinforcement region 3, play the effect that prevents that the thick liquid from going back, restriction thick liquid diffusion scope just lies in target reinforcement region 3, greatly improve the thick liquid retention rate in the target reinforcement region 3.
Step six: carrying out forward segmented grouting on the target reinforcement area 3 by adopting a quick-setting grouting material, and monitoring surface deformation and station structure displacement in real time in the grouting process; the purpose of monitoring the deformation of the earth surface in real time is to prevent the deformation of the earth surface and the deformation of municipal pipelines from exceeding the standard allowable value, and the purpose of monitoring the displacement of the station structure in real time is to ensure that the adverse effect of grouting on the station structure is controlled within the standard allowable value range.
The rapid-setting grouting material is used for limiting the diffusion range of the grout by utilizing the rapid-setting characteristic of the rapid-setting grouting material, so that the grout is retained in a target reinforcing area as much as possible, and the grouting reinforcing effect is improved. The quick-setting grouting material adopts cement-water glass double-liquid slurry, the mass ratio of water to cement of the cement slurry is controlled to be 0.8-1, and the volume ratio of the cement slurry to the water glass slurry is controlled to be 3-4: 1.
The grouting ending standard of single grouting adopts a grouting ending standard of three controls of 'volume, pressure and deformation', and grouting is stopped when the grouting pressure reaches the designed grouting final pressure and the grouting amount reaches 80% of the designed grouting amount; stopping grouting when the grouting amount reaches 1.5 times of the designed grouting amount and the grouting pressure does not reach the designed grouting final pressure; and stopping grouting when the grouting pressure does not reach the designed grouting final pressure, the grouting amount does not reach the designed grouting amount, and the surface deformation or the station structure displacement exceeds an early warning value. The designed grouting final pressure can be 1-1.5 MPa, and the designed grouting amount can be 1.5-2.5 m3And the early warning value of the ground surface deformation or the station structure displacement is determined according to the actual engineering requirement and the local standard requirement.
The grouting sequence of the grouting drill hole 4 is that the outer ring is firstly grouted, then the inner ring is firstly grouted, so that an enclosing structure is formed, the diffusion range of subsequent grouting slurry is limited, and the retention rate of the slurry in a target reinforcing area is improved.
The length of a section of the forward sectional grouting is 3-4 m, the shallow stratum of the target reinforcement area 3 is reinforced firstly through the forward grouting, and then the grouting depth is increased gradually from shallow to deep until the bottom boundary of the target reinforcement area 3 is reached. As shown in fig. 4, the first grouting section 17 is reinforced, and then the second grouting section 18 and the third grouting section 19 are reinforced in sequence. Because the shallow water-rich sand layer is reinforced in place by the preorder grouting, the problems of difficult drilling and serious hole collapse of the water-rich sand layer can be avoided in the subsequent grouting construction.
Step seven: and (4) performing feedback adjustment on grouting design through surface deformation and station structure displacement monitoring data. The total limit of the ground surface uplift amount and the total limit of the station structure displacement caused by the whole grouting process are selected according to the specification, and the grouting times, the total limit of the ground surface uplift amount and the total limit of the station structure displacement need to be comprehensively considered. When the maximum ground surface uplift deformation amount caused by single grouting exceeds 0.3cm or the station structure displacement exceeds 0.2cm, the designed grouting amount is properly reduced.
Step eight: and finishing grouting work of all grouting drill holes and checking grouting effect. The grouting effect inspection comprises a water pressing test, drilling coring and drilling television exploration, and the permeability coefficient of the stratum after reinforcement obtained in the water pressing test<1×10-6cm/s, core rate of drilled hole>And 50%, when the hole collapse does not exist in the hole drilling television exploration inspection hole, the grouting effect is considered to meet the requirement.
Example two:
in the embodiment, a tunnel in a certain subway engineering interval is taken as an example, a shield method is adopted for excavation, the vault burial depth of a shield tunnel 1 is 10m, the excavation diameter of the shield tunnel 1 is 6.5m, the clear distance between two shield tunnels 1 is 8m, the full section of the shield tunnel 1 passes through a water-rich sand layer 2 at the end part of the shield, and the construction risk is extremely high.
The following steps are adopted for reinforcement:
the method comprises the following steps: the target consolidation zone 3 is determined and the surface grouting borehole 4 is designed. The plane range of the target reinforcement area 3 is expanded by 4m from the contour line of the shield tunnel 1 in the direction vertical to the axis of the tunnel, the plane range is translated by 8m from the boundary of the station enclosure structure 5 in the direction parallel to the axis of the shield tunnel 1, the vertical range of the target reinforcement area 3 is the upward movement of 4m from the height line of the arch top of the shield tunnel 1, and the downward movement of 1m from the height line of the arch bottom of the shield tunnel 1. The ground surface grouting drill holes 4 are arranged in a quincunx mode, and the hole spacing is designed to be 2 m.
Step two: and arranging a ground surface deformation monitoring point 6 and a station structure displacement monitoring point 7. The arrangement range 8 of the surface deformation monitoring points is 3m of the plane range of the target reinforcing area 3, and the distance between the surface deformation monitoring points 6 is 5 m. The station structure displacement monitoring points 7 are arranged on the station enclosure structure 5, the distance between the station structure displacement monitoring points 7 is 5m, and the displacement monitoring direction is the horizontal direction.
Step three: manufacturing an orifice pipe 11 with the geotextile bag 10, welding a grouting pipe 14 on the side surface of the orifice pipe 11, and extending the end part of the grouting pipe 14 into the geotextile bag 10. The orifice pipe 11 is a steel sleeve with the diameter of 108mm, a flange plate 12 is welded at the upper part of the orifice pipe 11, and the flange plate 12 is connected with a grouting valve 13. The geotextile bag 10 is made of high-strength geotextile, two ends of the geotextile bag 10 are bound and fixed on the orifice pipe 11, one end of the geotextile bag 10 is bound at the end part (tail end) of the orifice pipe 11, the length of the geotextile bag 10 is 2m, and the circumference of the geotextile bag 10 after expansion is 1.2 m.
Step four: a grouting borehole 4 is drilled and an orifice pipe 11 is lowered. The depth of the orifice tube 11 is directly to the upper boundary of the target consolidation area 3.
Step five: grouting is carried out on all geotextile bags 10 of the grouting drill holes 4, surrounding strata are compacted, and a grout stopping rock disk 15 is constructed. Grouting all geotextile bags 10 of the grouting drill holes 4 by adopting quick-setting type slurry through the grouting pipes 14, wherein the grouting pressure is 2-3 MPa, and the gelation time of the quick-setting type slurry is required to be less than 20 s. In the embodiment, the quick-setting type slurry adopts cement-water glass slurry, the mass ratio of water to cement of the cement slurry is W/C-1, and the volume ratio of two liquids of the cement slurry and the water glass slurry is C: S-4: 1.
Exerting the extrusion force to the stratum around through the inflation effect of geotechnological sack 10, crowded stratum forms stratum crowded district 16 around, its intensity is far higher than original stratum after the stratum is crowded densely, and then the ability of resisting the fracture of thick liquid splitting destruction is showing and is strengthened, after a plurality of geotechnological sacks 10 expand, adjacent stratum crowded district 16 overlap joint each other, can form only thick liquid rock-tray 15 above target reinforcement region 3, play the effect that prevents that the thick liquid from returning upward, restriction thick liquid diffusion range just lies in target reinforcement region 3, greatly improve the thick liquid retention rate in the target reinforcement region 3.
Step six: and (3) performing forward sectional grouting on the target reinforcement area 3 by adopting a quick-setting grouting material, and monitoring the deformation of the earth surface and the structural displacement of the station in real time in the grouting process.
The material used for grouting is a quick-setting grouting material, and can adopt cement-water glass double-liquid slurry, the mass ratio of water to cement of the cement slurry is W/C1, and the volume ratio of the cement slurry to the water glass slurry is C: S4: 1. The ground surface deformation and the station structure displacement are monitored in real time in the grouting process, the ground surface deformation and the municipal pipeline deformation are prevented from exceeding the standard allowable value, and the adverse effect of grouting on the station structure is controlled within the standard allowable value range.
The grouting ending standard of single grouting adopts a grouting ending standard of three controls of 'volume, pressure and deformation', and grouting is stopped when the grouting pressure reaches the designed grouting final pressure and the grouting amount reaches 80% of the designed grouting amount; stopping grouting when the grouting amount reaches 1.5 times of the designed grouting amount and the grouting pressure does not reach the designed grouting final pressure; and stopping grouting when the grouting pressure does not reach the designed grouting final pressure, the grouting amount does not reach the designed grouting amount, and the surface deformation or the station structure displacement exceeds an early warning value. The designed grouting final pressure is 1.2MPa, and the designed grouting amount is 2.5m3The early warning value of the ground surface deformation or the station structure displacement is determined according to the actual engineering requirement and the local standard requirement, the early warning value of the ground surface deformation displacement in the embodiment is 1.5cm, the early warning value of the station structure displacement is 0.5cm, and the length of a section of the forward sectional grouting is 4 m.
Step seven: and (4) performing feedback adjustment on grouting design through the ground surface deformation monitoring data and the station structure displacement monitoring data. When the maximum ground surface uplift deformation amount caused by single grouting exceeds 0.3cm or the station structure displacement caused by single grouting exceeds 0.2cm, the designed grouting amount is properly reduced.
Step eight: and finishing grouting work of all grouting drill holes and checking grouting effect. Permeability coefficient of consolidated formation obtained by pressurized water test<1×10-6cm/s, core rate of drilled hole>And 50%, when the hole collapse does not exist in the hole drilling television exploration inspection hole, the grouting effect is considered to meet the requirement. In this example, the average permeability coefficient of the formation after grouting and consolidation is 5.2 × 10-7cm/s, inspection of the wellsThe core-drilling rate is generally over 65 percent, the hole collapse phenomenon basically does not exist in the inspection hole, and the grouting effect meets the target requirement.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. The advanced grouting reinforcement method suitable for the water-rich sand layer section of the end of the shield comprises the following steps:
the method comprises the following steps: determining a target reinforcing area and designing a grouting drill hole;
step two: arranging ground surface deformation monitoring points and station structure displacement monitoring points;
step three: manufacturing an orifice pipe with an expandable geotextile bag;
step four: drilling a grouting drill hole and putting an orifice pipe in the grouting drill hole;
step five: grouting the geotextile bag positioned in the grouting drill hole, compacting surrounding strata, and constructing a grout stopping rock disk;
step six: carrying out forward segmented grouting on a target reinforcement area by adopting a quick-setting grouting material, and monitoring surface deformation and station structure displacement in real time in the grouting process;
step seven: performing feedback adjustment on grouting design through surface deformation and station structure displacement monitoring data;
step eight: and finishing grouting work of all grouting drill holes and checking grouting effect.
2. The advanced grouting reinforcement method suitable for the water-rich sand section at the end of the shield tunnel according to claim 1, wherein in the first step, the plane range of the target reinforcement area is expanded by 3-4 m from the contour line of the shield tunnel in the direction vertical to the axis of the shield tunnel, and is translated by 6-8 m from the boundary of the station enclosure structure in the direction parallel to the axis of the shield tunnel; the vertical range of the target reinforcing area is that the height line of the arch top of the shield tunnel moves upwards by 3-4 m, and the height line of the arch bottom of the shield tunnel moves downwards by 1-1.5 m.
3. The advanced grouting reinforcement method suitable for the water-rich sand interval at the end of the shield according to claim 1, wherein in the second step, the arrangement range of the surface deformation monitoring points is a set distance extended from the plane range of the target reinforcement area, and the distance between adjacent surface deformation monitoring points is 3-5 m;
the displacement monitoring points of the station structure are arranged on the station enclosure structure, the distance between every two adjacent displacement monitoring points of the station structure is 3-5 m, and the displacement monitoring direction is the horizontal direction.
4. The advanced grouting reinforcement method suitable for the water-rich sand section at the end of the shield according to claim 1, characterized in that a flange is installed at the top of the orifice pipe, and a grouting valve is arranged above the flange; the end of the orifice tube is flush with the upper boundary of the target consolidation area.
5. The advanced grouting reinforcement method for the water-rich sand section of the shield end according to claim 1, wherein the geotextile bag is fixed on the outer side of the orifice pipe, a grouting pipe is arranged on one side of the orifice pipe, and the tail end of the grouting pipe extends into the geotextile bag.
6. The advanced grouting reinforcement method for the water-rich sand interval at the end of the shield according to claim 1, wherein in the fifth step, quick-setting grout is adopted to perform grouting on the geotextile bag through a grouting pipe, and the gel time of the quick-setting grout is less than 20 s.
7. The advanced grouting reinforcement method suitable for the water-rich sand section at the end of the shield according to claim 1, wherein in the sixth step, a cement-water glass double-liquid slurry is adopted as a quick-setting grouting material, the water-cement mass ratio of the cement slurry is controlled to be 0.8-1 when W/C, and the double-liquid volume ratio of the cement slurry to the water glass slurry is controlled to be 3-4: 1 when C: S.
8. The advanced grouting reinforcement method suitable for the water-rich sand interval at the end of the shield according to claim 1, wherein in the sixth step, grouting is stopped when the grouting pressure reaches the design grouting final pressure and the grouting amount reaches 80% of the design grouting amount, grouting is stopped when the grouting amount reaches 1.5 times of the design grouting amount and the grouting pressure does not reach the design grouting final pressure, and grouting is stopped when the grouting pressure does not reach the design grouting final pressure, the grouting amount does not reach the design grouting amount, but the surface deformation or the station structure displacement exceeds an early warning value.
9. The advanced grouting reinforcement method for the water-rich sand interval at the end of the shield according to claim 1, wherein in the seventh step, when the maximum surface uplift deformation caused by single grouting exceeds 0.3cm or the station structure displacement exceeds 0.2cm, the designed grouting amount is reduced.
10. The advanced grouting reinforcement method for the water-rich sand interval at the end of the shield tunneling machine according to claim 1, wherein in the eighth step, the grouting effect check comprises a water pressing test, a drilling coring and a drilling television exploration.
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| CN112177620A (en) * | 2020-08-17 | 2021-01-05 | 山东大学 | Construction method for underground engineering TBM to penetrate complex soft and hard composite stratum |
| CN113417673A (en) * | 2021-07-22 | 2021-09-21 | 中交三航局第三工程有限公司 | Method for filling and grouting behind ground surface wall of tunnel or subway station |
| CN116025367A (en) * | 2022-10-28 | 2023-04-28 | 中国海洋大学 | Pre-applied horizontal stress, induced splitting and localized combined grouting reinforcement device and process |
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Application publication date: 20200117 |