CN110671119A - High-performance bentonite for shield construction and preparation process of mud film of high-performance bentonite - Google Patents
High-performance bentonite for shield construction and preparation process of mud film of high-performance bentonite Download PDFInfo
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Images
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
- E21D9/06—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
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/001—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing unburned clay
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00724—Uses not provided for elsewhere in C04B2111/00 in mining operations, e.g. for backfilling; in making tunnels or galleries
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Ceramic Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Environmental & Geological Engineering (AREA)
- Dispersion Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Excavating Of Shafts Or Tunnels (AREA)
Abstract
The invention discloses a high-performance bentonite for shield construction and a preparation process of a mud film thereof, wherein the high-performance bentonite is prepared by reacting liquid A bentonite slurry with liquid B plasticizer, and the mass ratio of the bentonite slurry to the plasticizer is 14: 1-16: 1, the bentonite slurry is obtained by mixing sodium bentonite and water according to the mass ratio of 1:1.5-1: 2.5. The high-performance bentonite provided by the invention has the characteristics of good water resistance and wrapping property, strong adhesive force with different media and strong permeability under the action of different pressures. The high-performance bentonite clay film has good airtightness and adhesiveness, has better pressure stabilizing effect than a common bentonite clay film, and can ensure ground safety. The high-performance bentonite raw material has wide source, lower manufacturing cost and simple and convenient construction operation, is particularly suitable for a tool changing section needing high-frequency pressure opening under complex geological conditions, can shorten the tool changing period and improve the economic benefit.
Description
Technical Field
The invention belongs to the technical field of shield construction, and particularly relates to high-performance bentonite for shield construction and a manufacturing method of a mud film of the high-performance bentonite.
Background
With the continuous expansion of the subway construction scale, the shield tunnel construction is widely applied by the advantages of rapidness, safety, high efficiency and the like. However, when the shield tunneling machine does not have a stratum reinforcing condition under complex geological conditions such as a soft upper layer, a hard lower layer, a sand-egg layer, a soft stratum and the like, the shield tunneling machine needs to be checked and replaced by a cutter, and the shield tunneling machine also becomes one of important safety risk sources. At present, the tool changing operation is mainly carried out by applying the bentonite clay film breast wall under-pressure warehouse opening technology in China.
The traditional bentonite clay film wall protection construction method has the defects of poor stratum adaptability, difficult pressure stabilization, unstable later period and the like, a complete clay film is not easily formed on a tunnel face, the film needs to be built repeatedly, the construction period is prolonged, and the project investment is increased; the mud membrane protective wall is unstable, is sensitive to pressure change in the soil bin, is easy to release pressure, has serious potential safety hazard, and even causes safety accidents such as ground collapse and the like; meanwhile, under some special geological conditions, such as rivers and lakes on the ground and loose stratums, mud easily rises to cause water body pollution.
Disclosure of Invention
The invention aims to overcome the defects, provides high-performance bentonite for shield construction and discloses a process for preparing a mud film retaining wall by using the high-performance bentonite, and the high-performance bentonite has the advantages of good water resistance, good wrapping property, strong adhesive force with different media and strong permeability under the action of different pressures.
In order to achieve the purpose, the invention provides high-performance bentonite for shield construction, the high-performance bentonite is prepared by reacting liquid A bentonite slurry with liquid B plasticizer, and the mass ratio of the bentonite slurry to the plasticizer is 14: 1-16: 1, the bentonite slurry is obtained by mixing sodium bentonite and water according to the mass ratio of 1:1.5-1: 2.5.
The mass ratio of the bentonite slurry A to the plasticizer B is preferably 15:1, the mass ratio of sodium bentonite to water in the bentonite slurry is preferably 1:2. the plasticizer can be phthalate, the sodium bentonite is preferably modified sodium bentonite, and liquid A bentonite of Teddis materials Co., Ltd, of Fushan city can be selected.
The plasticizing viscosity of the A liquid bentonite slurry needs to reach more than 600dpa.s
The high-performance bentonite is prepared by circularly stirring modified sodium bentonite and water in a separate slurry tank to obtain bentonite slurry A, and preferably stirring for 10-20 min; pumping the liquid A into a synchronous slurry storage tank of the shield tunneling machine through a shear pump, adding a plasticizer of the liquid B into the synchronous slurry storage tank, and uniformly mixing and stirring the liquid A and the liquid B in the synchronous slurry storage tank to obtain the composite material.
The preparation process of the high-performance bentonite clay film retaining wall for shield construction is characterized by comprising the following steps:
(1) shield tail seal ring: performing double-liquid grouting on the 5 th to 7 th rings from the shield tail to prepare a shield tail water stop ring, plugging a gap of the shield tail, and controlling water coming from the rear part of the duct piece; the double liquid is cement and water glass, and the mass ratio of the cement to the water glass can be 1: 0.8-1, wherein the water cement ratio of the cement can be 1: 1;
(2) mixing high-performance bentonite: mixing the solution A and the solution B by using a synchronous slurry storage tank on a shield machine;
(3) wrapping a shield tunneling machine body: injecting high-performance bentonite into the reserved holes on the shield machine body, and injecting the high-performance bentonite to fill and wrap the whole shield machine, namely a front shield, a middle shield and a tail shield of the shield machine, at the outer sides of the shield tail and 1-3 ring pipes out of the shield machine by using synchronous grouting pipes;
(4) slurry residue replacement, namely injecting high-performance bentonite into a soil bin of the shield tunneling machine to replace soil in the soil bin; the injection point position adopts a plurality of reserved holes between 9-3 points of the soil bin partition plate (namely 9 o 'clock position-3 o' clock position), and the injection is pressed from the top of the shield tunneling machine; discharging soil in the soil bin by using a screw machine;
(5) and (3) staged pressurization: pressurizing by injecting high-performance bentonite for a few times, and performing four-stage pressurization, wherein each stage is 0.2bar, the two stages in the front are dynamically stabilized for 2 hours, and the last stage requires 12 hours of pressure stabilization, so that the safe work of workers in a soil bin is ensured;
(6) and (3) slurry gas replacement, namely, inputting air into the soil bin by using a compressed air pipeline of the shield machine to pressurize the soil bin, and pumping and discharging the high-performance bentonite from the middle part of the soil bin by using a screw machine.
(7) Pressure maintaining: after the slurry gas replacement is finished, the pressure can be maintained for more than 6 hours under the condition that the pressure maintaining system is opened, and then the high-performance bentonite mud film is finished.
The storage capacity of the liquid A in the slurry storage tank in the high-performance bentonite mixing step cannot exceed 2/3 height of a horizontal stirring blade in the slurry storage tank.
In the slurry residue replacement step, the pressure in the soil bin needs to be determined to be stable, and the pressure fluctuation is controlled within +/-0.5 bar; the pressure in the soil bin is stabilized at 2.0-2.4 bar.
In the stage pressurization step, when the shield machine is between the second stage and the third stage, the shield machine is retreated by utilizing the pressure of injecting high-performance bentonite, and a gap is reserved to prevent the front end of the shield machine from being stuck; and before the third stage of pressurization, rotating the cutter disc at the rotating speed of less than 0.5 rpm.
In the slurry gas replacement step, the volume of the input air is consistent with that of the discharged high-performance bentonite, and the pressure in the soil bin is kept stable.
The shield machine is a conventional circular earth pressure balance shield machine, and the length of each ring of the pipe piece is 1.5 meters.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the high-performance bentonite, the specific ratio of the plasticizer to the sodium bentonite is combined with higher water absorption rate, stronger cohesiveness and better colloid performance of the sodium bentonite, and meanwhile, the plasticizer obviously improves the fluidity of bentonite slurry, increases the adsorption force and viscosity, and simultaneously keeps the sealing performance of the slurry, so that the high-performance bentonite is suitable for protecting a mud film wall and maintaining pressure in a shield under-pressure opening operation. The high-performance bentonite has the characteristics of good water resistance and wrapping property, strong adhesive force with different media and strong permeability under the action of different pressures. Compared with common bentonite, the bentonite has the advantages of better water-resisting effect, stronger adhesive capacity, difficult diffusion, good stability and obvious enhancement of stratum adaptability.
(2) The high-performance bentonite clay film prepared by the method has good airtightness and adhesiveness, has better pressure stabilizing effect than the common bentonite clay film, and can better ensure the ground safety.
(3) The high-performance bentonite raw material has wide source, lower manufacturing cost and simple and convenient construction operation, is particularly suitable for a tool changing section needing high-frequency pressure opening under complex geological conditions, can shorten the tool changing period and improve the economic benefit.
(4) The high-performance bentonite of the invention can be used for: maintaining pressure in the mud film protecting wall and the bin during opening the bin under pressure; gravel is wrapped and discharged during tunneling, so that discharge stagnation is prevented; the gushing can be controlled when the water quantity of the stratum is larger during tunneling; when the tunnel is tunneled in a complex stratum, the posture of the shield machine can be adjusted, and the ground settlement is controlled; stabilizing the end soil and stopping water at the time of origination and arrival.
Drawings
FIG. 1 is a schematic diagram of a preparation process of the high-performance bentonite clay film for shield construction.
Fig. 2 is a water-barrier test chart of the high-performance bentonite prepared in example 1.
Fig. 3 is a graph showing the entrapment test of high performance bentonite prepared in example 1.
Fig. 4 is an adhesion test chart of the high performance bentonite prepared in example 1.
In the figure: 1-high-performance bentonite, 2-water stop rings, 3-screw machines, 4-soil bins, 5-grouting pipes, 6-preformed holes and 7-pipe pieces.
Detailed Description
Preferred embodiments of the present invention will be described in more detail with reference to specific examples.
Example 1
The high-performance bentonite is prepared by reacting liquid A bentonite slurry with liquid B plasticizer (phthalate, excellent grade), wherein the mass ratio of the bentonite slurry to the plasticizer is 15:1, and the bentonite slurry is prepared by mixing sodium bentonite and water according to the mass ratio of 1:2. The high-performance bentonite is prepared by circularly stirring modified sodium bentonite (purchased from Taddis materials Co., Ltd., Fushan) and water in a separate slurry tank for 15min to obtain slurry of the bentonite A, wherein the plasticizing viscosity of the slurry reaches over 600dpa.s, pumping the liquid A into a synchronous slurry storage tank of a shield tunneling machine by a shear pump, adding a plasticizer of the liquid B into the synchronous slurry storage tank, and uniformly mixing and stirring the liquid A and the liquid B in the synchronous slurry storage tank.
The experiments for verifying the performance of the high performance bentonite prepared as described above are shown in fig. 2-4. As can be seen from fig. 2, the basin-shaped block made of high-performance bentonite is placed in a bucket filled with water, and the water in the bucket does not permeate into the basin-shaped block made of high-performance bentonite, so that the water-proof performance of the basin-shaped block is good. As can be seen from FIG. 3, the stones were all adhered to the cross bar by high performance bentonite, which proved to be good in binding. As can be seen from FIG. 4, the high performance bentonite can be adhered to different plastic basins and ceramic basins, and the adhesion of the high performance bentonite to different media is proved to be strong.
The preparation process of preparing high performance bentonite clay film with the high performance bentonite clay comprises the following steps:
(1) shield tail seal ring: performing double-liquid grouting on the 5 th to 7 th rings separated from the shield tail to prepare a shield tail water stop ring 2, plugging a gap of the shield tail, and controlling water coming from the rear part of the duct piece 7; the double liquid is cement and water glass, and the mass ratio of the cement to the water glass can be 1: 0.8-1, wherein the water cement ratio of the cement can be 1: 1;
(2) mixing high-performance bentonite: mixing the bentonite slurry A and the plasticizer B by using a synchronous slurry storage tank on a shield machine to prepare high-performance bentonite, wherein the storage capacity of the bentonite slurry A in the slurry storage tank cannot exceed 2/3 of a horizontal stirring blade in the slurry storage tank;
(3) wrapping a shield tunneling machine body: injecting high-performance bentonite 1 to fill and wrap the whole shield machine, namely a front shield, a middle shield and a tail shield of the shield machine, at the outer sides of shield tails and 1-3 ring segments 7 which are separated from the shield machine by using a synchronous grouting pipe 5 by utilizing a preformed hole 6 on a shield machine body;
(4) slurry residue replacement, namely injecting high-performance bentonite 1 into a soil bin 4 of the shield machine to replace soil in the soil bin; the injection point position adopts a plurality of reserved holes between 9-3 points of the soil bin partition plate (namely 9 o 'clock position-3 o' clock position), and the injection is pressed from the top of the shield tunneling machine; discharging soil in the soil bin 4 by using a screw machine 3; in the step, the pressure in the soil bin needs to be determined to be stable, the pressure is controlled to avoid overlarge pressure fluctuation, and the pressure fluctuation is controlled within +/-0.5 bar; the pressure in the general soil bin is stabilized at 2.0-2.4 bar;
(5) and (3) staged pressurization: pressurizing by injecting high-performance bentonite 1 for a few times, and performing four-stage pressurization, wherein each stage is 0.2bar, the two stages in the front are used for dynamically stabilizing the pressure for 2 hours, and the last stage is required to stabilize the pressure for 12 hours; when the shield machine moves between the second stage and the third stage, the shield machine is retreated by utilizing the pressure of injecting high-performance bentonite, and a gap is reserved to prevent the front end of the shield machine from being stuck; before the third stage of pressurization, rotating the cutter head, wherein the rotating speed is less than 0.5 rpm;
(6) and (3) slurry gas replacement, namely inputting air into the soil bin 4 by using a compressed air pipeline to pressurize the soil bin, and pumping and discharging the high-performance bentonite 1 from the middle part of the soil bin by using a screw machine 3. The volume of the input air is consistent with that of the discharged high-performance bentonite, and the pressure in the soil bin is kept stable.
(7) Pressure maintaining: after the slurry gas replacement is finished, the pressure can be maintained for more than 6 hours under the condition that the pressure maintaining system is opened, and then the high-performance bentonite mud film is finished.
Comparative example 1
The mud film is prepared by adopting common calcium bentonite according to the method described in the example 1, the mud film protective wall cannot be successfully built by repeatedly reconstructing the mud film due to low water absorption and poor viscosity, air breaks through the lake bottom due to too fast change of soil pressure in the process, and bentonite slurry flows to the lake bottom along with gaps of a landing layer to pollute the water quality of an artificial lake.
Comparative example 2
The raw materials of example 1 are adopted, wherein the bentonite slurry is obtained by mixing sodium bentonite and water according to the mass ratio of 1:3, and the other preparation methods are the same as example 1. The prepared bentonite has insufficient viscosity and poor water resistance, a mud film needs to be repeatedly reconstructed, and the constructed mud film is unstable, sensitive to pressure change in a soil bin and easy to relieve pressure.
Comparative example 3
The raw materials of example 1 are adopted, wherein the mass ratio of the bentonite slurry to the plasticizer is 18:1, and the rest preparation method is the same as that of example 1. The prepared bentonite has too high fluidity and poor wrapping property, a mud film needs to be repeatedly reconstructed, and the constructed mud film is unstable and is easy to collapse.
Example 2
Construction example: high-frequency pressure open-cabin tool changing construction under complex geological conditions of shield between Changsha subway No. 3 line and 2 standard ocean lake New City station and ocean lake wetland station
Overview of engineering
1.1 engineering overview
The region from the Changsha subway No. 3 Yangtze lake New City station to the Yangtze lake wetland station is an underground project, and a shield method is adopted for construction. The shield is started from the south end of the ocean lake new city station, the tunneling task is completed when the shield reaches the ocean lake wetland station, and the shield is dismounted and hoisted. Starting and stopping mileage left line: ZDK7+ 809.070-ZDK 9+299.522, length 1481.696m (short chain 8.576m), right line: YDK7+ 809.070-YDK 9+299.522, length 1490.452m, 2 communication channels and No. 2 communication channel which is also used as a pump room.
Introduction of 1.2 interval under-pressure bin opening condition
According to shield construction experience of national subways and our units under similar stratum distribution conditions, our department predicts that shield construction needs to be carried out 12 times of opening and changing for a foreign-ocean region, and the actual opening and changing are accumulated for 19 times. Wherein, the bin opening is carried out for up to 9 times under pressure, and the cutters 107 are replaced in an accumulated way. Because the ground environment along the line is complex and limestone development conditions exist, the pressure opening tool changing place is mostly positioned in high risk areas, such as areas such as a high building of a residential quarter of a cross-country brook, an artificial lake of a downstream ocean lake wetland park, a downstream Xiangfu road approach bridge and the like, if the traditional bentonite is adopted to build a mud film pressure opening tool changing process, the construction risk is extremely high, and safety accidents are easily induced. This is described herein with the ring 584 on the right line and the tool changing location at the bottom of an artificial lake in a lake park as a typical example.
1.3 perimeter building
The ground position where the tool changing is carried out under pressure is an artificial lake in a lake wetland park, the area of the lake surface is about 295 x 275 meters, the water depth is about 2.5 meters, and the vault of the tunnel is 14 meters away from the bottom of the lake. Because the earth's surface is lake water, the ground can not be consolidated, adopts ordinary bentonite can't establish stable mud membrane dado simultaneously, presses area and opens the storehouse tool changing construction risk height, and the construction degree of difficulty is very big.
1.4 engineering geology and hydrogeology
The stratum at the position of opening the bin and changing the cutter is a silt layer <1-4-2>, a silty clay layer <2-1>, gravel sand <2-7> and round gravel <2-8> from top to bottom in sequence. The stratum within the face is the <2-8> stratum. The main formation properties are as follows:
sludge layer <1-4-2>
Is in a flow-plastic shape and is distributed sporadically in a field. The layer thickness is thin, the mucky soil has the characteristics of high water content, large pore ratio, high compressibility and low shear strength, and the compression deformation is easy to generate to cause ground settlement.
Layer of powdery clay <2-1>
Generally, the plastic is plastic to hard plastic and is widely distributed in the field; the upper renewal system is smaller than 2-2, slightly wet and dense, and is distributed sporadically in the field. The self-stability is better, and the mechanical property of the soil is better.
Gravel <2-7>
Wide distribution, large thickness, good water-rich property and medium-strong water permeability.
Round gravel <2-8>
Wide distribution, large thickness, good water-rich property and medium-strong water permeability.
Ground water level
The underground water is divided into fourth series loose layer pore water, layered bedrock fracture water and carbonate rock fracture karst cave water according to occurrence modes.
1. Pore water of fourth series loose layer
The fourth series water-bearing stratum mainly comprises a slightly compacted-compacted artificial fill layer and a gravel-washed layer:
① the artificial filling layer <1-2> is mainly the upper layer of stagnant water, the water-rich property is poor, the water permeability difference is large, the water permeability of the artificial filling layer with large content of coarse particles such as sand and gravel can reach medium, the water permeability of the plain filling mainly composed of cohesive soil is weak;
② the medium, coarse, gravel, round gravel and pebble layers are widely distributed, the thickness is large, the water-rich property is good, and the water permeability is medium to strong.
In addition, the water permeability of the alluvial soil layer, the residual soil layer and the rock completely weathered zone is poor, and the water permeability is a slightly-weakly permeable soil layer, but when the residual soil, the completely weathered rock and the strongly weathered rock contain more coarse particles or cracks develop, the water permeability is obviously enhanced.
2. Lamellar bedrock fracture water
The layered bedrock fracture water mainly exists in strong weathering zones and middle weathering zones of mud-basin-system limestone and sandstone, and the occurrence conditions are related to the weathering degree of rocks, the fracture development degree and the like.
According to the analysis of the investigation data, the core of the strong weathering zone of the bedrock is broken, and the core is in a broken block shape; the weathering zone rock in the bedrock has weathering cracks developing, the rock core is in short column shape, block shape and long column shape, the underground water occurrence condition is relatively poor, the water permeability is generally weak, and the water-rich property is poor, but when the rock weathering zone contains more broken stones and cracks develop, the water permeability can reach the medium level. Because the part of strong-stroke weathered bedrock covered with fully weathered rock and residual soil and the like is a relative water-resisting layer, the part of the weathered fissure water of the bedrock has the characteristic of bearing water.
The groundwater level burial depths disclosed in the survey are different, the stable water level burial depths of all drill holes measured in the survey period are 0.00-16.80 m and 6.39m on average, the change of the groundwater level is closely related to the occurrence, supply and drainage of groundwater, and is influenced by seasonal changes, and the annual change range is 2-5 m.
In a middle-subtropical humid monsoon climate area in an exploration field, rainfall is greater than evaporation capacity, atmospheric rainfall is a main supply source of underground water in the field, the underground water supply period is 4-9 months per year, and the underground water consumption period and the drainage period are 3 months from 10 months to the next year. The exploration site mainly belongs to a supply area and a runoff area, the supply source of fourth system pore water is mainly atmospheric precipitation, and the karst fissure water and the bedrock fissure water mainly depend on the overflow supply and atmospheric precipitation supply of the fourth system pore water. The underground water in the field is mainly present in the pores of the fourth sand layer, the gravel soil layer and the like, and karst cracks and bedrock cracks. The surface water system develops slightly, and the fourth system diving aquifer mainly discharges to rivers on both sides.
3. Carbonate rock fissure cavern water
The carbonate fissure cavern water mainly exists in mud basin series limestone, and the water-rich property and the permeability of the carbonate fissure cavern water are influenced by factors such as the development degree, the connectivity, the form, the scale size and the fissure filling condition of the karst.
According to the karst development characteristics revealed by drilling and the analysis of the water inflow of a drilled hole in the drilling process, the karst development of the carbonate rock fissure cavern water in the ZCK6+ 460-ZCK 6+780 and YCK6+ 080-YCK 6+740 sections is large in scale, the filling is mainly gravel and sticky particles, and is not filled locally, so that the water permeability of the karst filling is good, the water-rich property is good, the connectivity is good, the strong water permeability is generally realized, and the water inflow is large; in the undeveloped section of the karst fissure, the rock is complete or relatively complete rock, and the water-rich property and the water permeability of the rock stratum are poor.
The current warehouse opening tool changing mileage is right line 584 ring incision mileage: at ZDK8+419.124, the cut buried depth is 15.1 m, the range of the stratum tunnel at the position is mainly full-section pebbles, and the top of the stratum tunnel is provided with a 7.5m silty clay layer, partial gravel sand and pebbles.
1.5 reason for construction of high-performance bentonite clay-film breast wall
The operation of opening the cabin and changing the tool at the pressure starts to construct a water stop ring from 8 months and 10 days in 2017, and common bentonite is injected to establish a mud film at 8 months and 13 days. Because the stratum at the tunnel position is a small amount of clay and limestone, a part of sand and pebbles are mostly round gravels, the actual stratum and the geological exploration stratum come in and go out greatly, the stratum pores are enlarged, and the ground has gas leakage. The bentonite is directly exposed out of the lake bottom. Then the earth pressure is set to be reduced from 1.6 to 1.5 for operation, the repeated reconstruction of the mud film fails to establish the mud film protective wall, air breaks through the lake bottom due to the too fast change of the earth pressure in the process, and bentonite slurry flows to the lake bottom along with gaps of the landing layer to pollute the water quality of the artificial lake. The accumulated time for building the mud film by using the common bentonite is 19 days, and the failure is ended.
The bentonite that adopts many times in earlier stage establishes the pressure construction of opening a warehouse of mud membrane dado, summarizes and obtains experience: the traditional bentonite clay film retaining wall building process has a long construction period, a complete clay film is not easily formed on a tunnel face to cause repeated membrane building, and meanwhile, serious potential safety hazards exist. Through research of the department of project, the mud membrane retaining wall is determined to be formed by adopting high-performance bentonite, and the matching proportion adaptation is carried out for multiple times aiming at the stratum condition in the early stage, so that the optimal effect is strived to be achieved. Under the joint efforts of all personnel at the department of project, high-performance bentonite is injected in 2017 in 9, 8 months to establish a mud film and successfully stabilize the pressure, and the mud film is successfully established in 9, 12 months to open a warehouse for tool changing. Mud does not fall in the whole opening process, the phenomenon of air leakage does not occur, the opening process is carried out under pressure for 5 days, and the cutter is replaced by 5 handles. Compared with the common bentonite with pressure for opening the bin for tool changing, the method has the characteristics of short time, strong safety and stability, effective shortening of the construction period and the like.
Second, overall construction deployment
In order to ensure the construction safety, aiming at the actual situation at the present site, high-performance bentonite is firstly adopted as a mud film in a soil bin in a tunnel to strengthen the air tightness of opening the bin under pressure; high-performance bentonite is injected into the positions 3 and 9 of the shield tunneling machine and the shield tail to prevent the shield tunneling machine from being locked. And simultaneously, synchronous slurry and secondary slurry are added in the range of 571 rings to 577 of the right-line forming tunnel segment to form a water stop ring.
According to the current construction condition and the actual condition of the tunneling process, high-performance bentonite clay film wall protection is required to be completed before opening the cabin under pressure, water stop rings are applied, and a shield body is injected with high-performance bentonite for anti-lock. And after the high-performance bentonite mud film is built, checking the air tightness of the soil bin, and opening the bin for tool changing.
Third, preparation of construction
3.1 Material preparation
TABLE 1 tool-changing tool Material Table
3.2 preparation of mud film by high-performance bentonite
Before opening the bin, the cutter head and the soil bin are filled with high-performance bentonite, the injection pressure is slightly higher than the soil bin pressure during tunneling and is controlled to be about 1.7Bar (the injection pressure is adjusted according to the actual situation on site to ensure the stability of the peripheral soil mass), so that slurry can have a certain diffusion range in a stratum with better injectability and form a layer of closed mud film on the face of the tunnel, the air tightness of the stratum in front of the cutter head is enhanced, and the self-stability capability of the tunnel face is improved.
Preparation of high-performance bentonite clay film protective wall
4.1 high Performance Bentonite A liquid preparation
And (3) mixing the liquid A by using a 55KW high-pressure shear pump beside the synchronous slurry tank of the shield machine, circularly stirring in an independent slurry tank for 10-20 min, and pumping the mixed liquid A into the synchronous slurry storage tank of the shield machine by using a shear pump after the liquid A is mixed.
4.2 high Performance Bentonite preparation
And (3) weighing the high-performance bentonite B by an electronic scale according to the proportion, adding the weighed high-performance bentonite B into the liquid A in the synchronous slurry tank, uniformly mixing, and automatically stirring and stirring by the synchronous slurry tank to prepare the high-performance bentonite. 1-2m each time3And the effect is visually observed after 2 min.
4.3 high-performance bentonite clay film breast wall pressurized bin opening process flow
The high-performance bentonite is adopted to protect the wall by a mud membrane, the high-performance bentonite replaces mud in a soil bin, and graded pressurization is started until the pressure of the top without the bin is kept constant, so that the high-performance bentonite is ensured to fully and uniformly permeate into the range of the tunnel face and the shield body.
Table 2: technological process for preparing mud film by using high-performance bentonite
Note: in the actual construction process, the step is slightly adjusted (for example, the pressure is determined in the replacement process and the like) according to the actual condition of the construction, which belongs to the conventional operation and does not belong to the change of the method.
Fifthly, checking related equipment of shield
In order to ensure the safety of air compression operation, the comprehensive inspection and maintenance of related equipment such as an air compressor, a man brake and the like on the shield machine are carried out.
Sixthly, opening the bin and changing the tool for construction
6.1 pressurization of the soil warehouse
Before the construction of the pneumatic warehouse opening operation, gas detection is needed, and warehouse opening operation can be carried out after the detection result meets the standard requirement.
6.2 staff enter the front cabin
The operation personnel are handed over before the opening operation, so that the operation personnel can firmly grasp the structure of the man gate system and the operation is ensured to be accurate and correct. After the pressure in the man gate is confirmed to reach the working pressure, the personnel entering the warehouse can enter the excavation warehouse after confirming the safety of the connection door of the man gate and the excavation warehouse again.
Human body change during entry: the higher the pressure, the more gas, especially nitrogen, is inhaled, first dissolving in the body's blood and then entering the tissues. The transition from a precipitate with positive pressure and negative pressure can produce strong symptoms (such as ear pain, headache, decreased balance, and dental pain. if the air compensation of the cavity portion (e.g., sinus, eardrum, gut) is impeded (e.g., cold, rhinitis, pharyngitis), disorders can result.
6.3 into the main chamber
1. Inspection display instruments, tape recorders, clocks, thermometers, interphones, emergency telephones, sealing valves, etc. The cleanliness of the sealing door was checked.
2. The person enters the main chamber.
3. And starting the double-belt recorder to check whether the double-belt recorder works normally and the paper storage amount.
4. The isolation door between the main chamber and the antechamber is closed, and proper latching is noted.
5. The man-gate on the main chamber pressure wall is in a sealed state.
6. The gatekeeper establishes telephone contact with the person sitting in the main chamber.
7. The man-gate manager slowly opens the 'main chamber is introduced into the air gate valve', and the pressure of the main chamber is slowly increased according to the regulation until the working pressure is reached. (the working pressure in the man gate can reach 3bar at most, and when the working pressure exceeds 3bar, the pressure can be automatically released through a safety valve.)
8. When the pressure of the main chamber is the same as the pressure in the soil bin, the personnel in the personnel lock slowly open the sealing door between the main chamber and the soil bin to enter the soil bin. The gatekeeper closes the tape recorder.
6.4 enter the soil bin
Under the condition of changing the tool under pressure, after a worker enters the soil bin, the most important thing is to ensure that the worker is not damaged by collapsed materials and sudden water gushing in the working process. Therefore, according to the geological condition, high-performance bentonite is added into the residue soil in the soil bin after the excavation is stopped, and the mixture is uniformly mixed by a cutter head to form a mud wall so as to stabilize and seal the excavated surface. Then the operation is carried out according to the following steps:
1. the pipes of the compressed air conditioning installation are flushed with water through a separate connection behind the pressure partition in order to prevent the excavated material from entering the compressed air circuit.
2. After cleaning, the compressed air device is pressurized (all gate valves on the pressure wall are closed).
3. Compressed air is injected into the soil bin.
4. The appropriate amount of muck must be removed until the pressure gauge above the pressure bulkhead of the earth reservoir indicates the air pressure set on the compressed air conditioning unit.
5. Stopping the rotation of the cutter head and the screw conveyer and closing the gate of the screw conveyer.
6. Personnel enter the main chamber, and the main chamber is adjusted to the pressure state of the soil bin by a man-lock safety manager.
7. Personnel get into the people's floodgate main chamber, wait soil storehouse and the pressure balance of main chamber back, then can open the soil cabin door carefully and get into soil storehouse, at this in-process, should pay attention to the face change constantly, soil storehouse bottom, incision ring change.
6.5 changing the tool
The specific replacement steps of the cutter can be referred to shield operation technical manual of medium iron construction and related drawings.
6.6 leave the main chamber
1. The man gate between the main chamber and the front chamber is in a closed state.
2. The person who will come out leaves the soil storehouse, gets into the main room.
3. The pressure wall door and the gate valve on the pressure wall for pressure equalization must be closed.
4. A phone contact is established between the gatekeeper and the person sitting in the gatekeeper.
5. The gatekeeper opens the tape recorder.
6. The man-lock administrator starts to slowly reduce the main chamber pressure using the main chamber exhaust valve while observing the pressure gauge main chamber pressure and the flowmeter main chamber exhaust. At the same time, the gate valve "main chamber aeration" is used to aerate the personnel lock. But not to allow the pressure to rise again.
7. The 'main chamber exhaust' gate valve and the 'main chamber air inlet' gate valve are adjusted, so that a stable and slow depressurization process meeting the specification is achieved under the condition of air inlet of the man gate. In this process, the flow indicated by the "main chamber exhaust" flow meter must not be less than 0.5m3/min。
8. When the pressure of the main chamber reaches the pressure, a sealing door communicated with the front chamber on the partition wall of the main chamber can be opened, and people can go out of the main chamber.
9. The gatekeeper closes the tape recorder and registers the in-out process (date, time, pressure, number of people, etc.) into the in-out gatekeeper registry.
6.7 forebay depressurization
When the staff reaches the limited working time (or discomfort), decompression is needed, and the specific steps are as follows:
1. the crew member arrives at the front compartment and closes the air tight doors of the main and front compartments.
2. The personnel in the main cabin use the telephone to contact with the gate attendant.
3. And reducing the pressure of the front cabin according to the requirement of the decompression meter, and observing a front cabin pressure meter and a front cabin air inlet flow meter.
4. At the same time, the man-lock attendant simultaneously opens the exhaust valve and starts the exhaust, at which point the pressure cannot rise again anyway.
5. Adjusting the intake valve and the exhaust valve until reaching a slow and constant pressure reduction speed specified by the exhaust process, wherein the flow rate value of the intake air flow meter is at least: 0.5m3/min。
6. And observing a front cabin pressure gauge, and when the air pressure in the front cabin is reduced to a first-stage pressure value, keeping the pressure constant within a specified time by a personnel gate attendant through regulating an air inlet valve and an air outlet valve. The personnel lock attendant should check the exhaust condition of the personnel lock through the intake air flow meter.
7. And repeating the steps 5-6 in the pressure maintaining process until the pressure in the cabin is the same as the external pressure.
8. And opening the cabin door between the front cabin and the outside, and enabling the personnel to come out of the front cabin.
9. The gatekeeper records the decompression process (date, time, pressure, number of people, etc.) on the gatekeeper notebook.
10. After decompression, it is necessary to ensure that the person working under pressure has a rest for a certain time at the work site, as specified in relation to the compression and decompression.
Seven, high performance bentonite clay film wall protection application achievement
The geological conditions between ocean and ocean regions are complex and changeable, the hardness is more uneven, the underground water content is rich, the ground environment is complex, and the under-pressure cabin opening tool changing operation is carried out for many times during the shield tunneling. The mud film dado that adopts traditional bentonite to establish carries out tool changing operation risk big, and the mud film establishes the cycle length, and difficult shaping has seriously influenced the time limit for a project progress. Aiming at the special geological conditions of the engineering, the project department summarizes through a plurality of tests, and introduces high-performance bentonite to replace the traditional bentonite, thereby obtaining remarkable effect.
During the operation of opening the bin with pressure of the high-performance bentonite material, the ground is stable without obvious settlement, the face surface of the cutter is stable without water seepage, and the operation environment is safe and reliable. Compared with the traditional bentonite, the tool of the shield machine is seriously worn in the upper soft and lower hard strata, the problem of pressurized bin entry in the upper soft and lower hard strata can be effectively solved, the safety and reliability of the whole process of replacing the tool of the shield machine are ensured, the tool changing period is shortened, powerful support is provided for the shield machine to smoothly complete the tunneling task, and valuable experience is provided for shield construction of similar strata in the future.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (10)
1. The utility model provides a high performance bentonite for shield constructs construction which characterized in that high performance bentonite is prepared by the reaction of A liquid bentonite slurry and B liquid plasticizer, and the mass ratio of bentonite slurry and plasticizer is 14: 1-16: 1, the bentonite slurry is obtained by mixing sodium bentonite and water according to the mass ratio of 1:1.5-1: 2.5.
2. The high-performance bentonite for shield construction according to claim 1, wherein the mass ratio of the A liquid bentonite slurry to the B liquid plasticizer is 15:1, the mass ratio of sodium bentonite to water in the bentonite slurry is 1:2.
3. the high-performance bentonite for shield construction according to claim 1 or 2, wherein the plasticization viscosity of the fluid A bentonite slurry is more than 600 dpa.s.
4. The high-performance bentonite according to claim 3, wherein the high-performance bentonite is prepared by circularly stirring sodium bentonite and water in a separate slurry tank to obtain a bentonite slurry A, pumping the bentonite slurry A into a synchronous slurry storage tank of a shield tunneling machine by a shear pump, adding a plasticizer B into the synchronous slurry storage tank, and uniformly mixing and stirring the bentonite slurry A and the liquid B in the synchronous slurry storage tank.
5. The process for preparing a mud film of high-performance bentonite for shield construction according to claim 4, characterized in that the process comprises the following steps:
(1) shield tail seal ring: performing double-liquid grouting on the 5 th to 7 th rings from the shield tail to prepare a shield tail water stop ring, wherein the double liquid is cement and water glass;
(2) mixing high-performance bentonite: mixing the bentonite slurry A and the plasticizer B by using a synchronous slurry storage tank on a shield machine to prepare high-performance bentonite;
(3) wrapping a shield tunneling machine body: injecting high-performance bentonite into the reserved holes on the body of the shield tunneling machine and outside 1-3 ring pipes of the shield tunneling machine by using synchronous grouting pipes to fill and wrap a front shield, a middle shield and a tail shield of the shield tunneling machine;
(4) slurry residue replacement, namely injecting high-performance bentonite into a soil bin of the shield tunneling machine to replace soil in the soil bin; the injection point position adopts a plurality of reserved holes between 9-3 point positions of the soil bin partition plate, and the injection is pressed from the top of the shield tunneling machine; discharging soil in the soil bin by using a screw machine;
(5) and (3) staged pressurization: pressurizing by injecting high-performance bentonite for a few times, and performing four-stage pressurization, wherein each stage is 0.2bar, the two stages in the front are dynamically stabilized for 2 hours, and the last stage is required to be stabilized for 12 hours;
(6) the slurry gas replacement comprises the steps of utilizing a compressed air pipeline of a shield machine to input air into a soil bin to pressurize the soil bin, and simultaneously utilizing a screw machine to pump and discharge high-performance bentonite from the middle part of the soil bin;
(7) pressure maintaining: and after the slurry gas replacement is finished, maintaining the pressure for more than 6 hours under the condition that the pressure maintaining system is opened, and thus finishing the high-performance bentonite mud film.
6. The process for preparing the mud film of the high-performance bentonite for shield construction according to claim 5, wherein the storage amount of the solution A in the slurry storage tank in the high-performance bentonite mixing step cannot exceed 2/3 of the horizontal stirring blade in the tank.
7. The process for preparing the mud film of the high-performance bentonite for shield construction according to claim 5, wherein the pressure in the soil bin is determined to be stable in the slurry-residue replacement step, and the pressure fluctuation is controlled within +/-0.5 bar.
8. The process according to claim 5, wherein the step of pressurizing in stages comprises moving the shield tunneling machine backward by the pressure of the high-performance bentonite during the period between the second stage and the third stage.
9. The process according to claim 5, wherein in the step of pressing in stages, the cutter head is rotated at a speed of less than 0.5rpm before the third stage of pressing.
10. The process according to claim 5, wherein the slurry gas displacement step is performed so that the volume of the introduced air is equal to the volume of the discharged high-performance bentonite.
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| CN113685203A (en) * | 2021-07-12 | 2021-11-23 | 广州轨道交通建设监理有限公司 | Spraying method of reinforced mud film during opening of shield under pressure and system for reinforcing mud film |
| CN113622935A (en) * | 2021-08-25 | 2021-11-09 | 中国铁建重工集团股份有限公司 | Junctional passage tunneling equipment |
| CN113622935B (en) * | 2021-08-25 | 2024-04-09 | 中国铁建重工集团股份有限公司 | Communication channel tunneling equipment |
| CN113738385A (en) * | 2021-09-24 | 2021-12-03 | 湖南中天凿岩科技有限公司 | Under-pressure entry method of mud-restraining effect auxiliary shield |
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Application publication date: 20200110 |