CN110792442B - Preparation process before pressure feeding in shield tunneling construction - Google Patents
Preparation process before pressure feeding in shield tunneling construction Download PDFInfo
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- CN110792442B CN110792442B CN201911166938.XA CN201911166938A CN110792442B CN 110792442 B CN110792442 B CN 110792442B CN 201911166938 A CN201911166938 A CN 201911166938A CN 110792442 B CN110792442 B CN 110792442B
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH 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
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
- E21D11/105—Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/38—Waterproofing; Heat insulating; Soundproofing; Electric insulating
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH 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
- E21D9/0635—Tail sealing means, e.g. used as end shuttering
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F17/00—Methods or devices for use in mines or tunnels, not covered elsewhere
- E21F17/18—Special adaptations of signalling or alarm devices
Abstract
The invention discloses a preparation process before pressure entry in shield tunneling construction, which comprises the steps of checking and backing up normal operation of shield opening related equipment, preparing a cabin opening operation tool, preparing wind, water and electricity in a tunnel, preparing a cabin cleaning tool, materials, emergency materials, living body detection and the like, comprehensively analyzing geological conditions of the position of a shield machine according to geological detailed exploration data, compensation data, recently-obtained muck composition and other information, determining the condition that the stratum is stable and has the pressure entry operation of the shield machine, and realizing the preparation before pressure entry in the shield tunneling construction by controlling a ground monitoring process, an air pressure value determining process, a shield tail sealing process, a mud film manufacturing process, a liquid level lowering process and a muddy water cabin sealing effect checking process so as to realize the smooth pressure entry in the shield tunneling construction.
Description
Technical Field
The application relates to a shield tunneling construction process, in particular to a preparation process before a belt pressure enters a bin in shield tunneling construction.
Background
The shield equipment is the key for success and failure of the project of the ultra-large diameter shield tunnel, and the ultra-large diameter shield tunnel inevitably encounters a plurality of soil layers in the tunneling process due to the cross section size and the structure top earthing requirement, so that the shield equipment needs higher reliability and technical advancement to meet the complex environments such as hydrology, geology and buildings along the line which may appear at the site of the tunnel.
According to the shield tunneling slag discharge condition and the geological investigation condition, comprehensively analyzing whether the geological condition of the shutdown tunnel face engineering is stable or not, and determining whether the safety requirement of pressurized warehouse entry construction can be met or not under the premise of taking effective protection measures. Under the condition of meeting, in order to ensure the continuity and the rapidness of the opening operation, sufficient construction preparation work must be made.
Disclosure of Invention
The invention provides a preparation process before pressure entering in shield tunneling construction, aiming at realizing smooth pressure entering in shield tunneling construction.
The invention adopts the following specific technical scheme:
a preparation process before a pressure enters a cabin in shield tunneling construction comprises the steps of checking and backing up normal operation of shield cabin opening related equipment, preparing a cabin opening operation tool, preparing wind, water and electricity in a tunnel, clearing tools and materials, emergency materials, detecting living bodies and the like, comprehensively analyzing geological conditions of the position of a shield machine according to information such as geological detailed exploration materials, compensation materials, recently-discharged soil composition and the like, and determining the condition that stratum stability has the pressure entering operation of the shield machine, wherein the preparation process specifically comprises the following aspects:
(1) a ground monitoring process;
(2) a pressure value determination process;
(3) a shield tail sealing process;
(4) a mud film manufacturing process;
(5) a liquid level lowering process;
(6) inspection process for sealing effect of muddy water bin.
Further, the ground detection process specifically comprises:
(1) arrangement of monitoring points
Pressing a tool changing position of a bin in a land section, arranging 1 monitoring section 5m behind the mileage of a cutter head, arranging 1 monitoring section at the cutter head, and arranging 2 monitoring sections in front of the cutter head at an interval of 5m, wherein 4 monitoring sections are provided in total; 1 line is arranged on the middle line of each section line, 1 line is arranged at each 5m of the two sides of the middle line of the line, and each section is provided with 3 earth surface monitoring points; monitoring the frequency for 4 times/day before entering the warehouse under pressure, wherein the sedimentation rate does not exceed 2 mm/day, and the warehouse opening condition is met when the accumulated sedimentation does not exceed 2 cm; monitoring the frequency for 5 times/day during the warehousing, wherein the sedimentation rate does not exceed 3 mm/day, and when the accumulated sedimentation does not exceed 3cm, the operation in the warehouse can be continued; monitoring the frequency for 2 times/day in the normal tunneling process after the pressure enters the cabin, wherein the sedimentation rate does not exceed 3 mm/day, and the accumulated sedimentation does not exceed 3 cm;
(2) monitoring method
The transmitting transducer transmits acoustic pulses downwards from the sea surface, the acoustic pulses are transmitted downwards in water and reflected when encountering seabed media with different densities, and the reflected acoustic pulses are transmitted upwards in the sea water and received by the receiving transducer on the sea surface; according to the round-trip time of the acoustic pulse in the seawater and the sound velocity of the acoustic pulse in the seawater, the linear distance from the transducer to the seabed, namely the water depth, can be calculated, and the sinking condition of the seabed is judged according to the change of the water depth;
and (3) settlement calculation: uxiZ + H water, wherein: z is sea level height, H water is depth of water
For the same measuring point delta Ux ═ Uxi-Uxi-1
In the formula,. DELTA.Ux, Uxi、Uxi-1Respectively measuring the sinking value of the sea bed surface, the depth of the reference water surface from the sea bed surface for the ith time and the depth of the reference water surface from the sea bed surface for the ith-1 time for the measuring point at the x position;
(3) monitoring control criteria
The accumulated value of surface sedimentation is 25 mm;
controlling the change rate of the earth surface according to 3 mm/d;
thirdly, the accumulated value of vertical displacement and horizontal displacement of the shield tunnel structure is as follows: 30mm, rate of change: 3 mm/d;
fourthly, the clearance convergence accumulated value of the shield tunnel structure: 3% D, rate of change: 3 mm/d; wherein D is the tunnel excavation diameter;
(4) alarm value
According to design requirements and relevant specifications, when monitoring data reaches 70% of a monitoring control standard value, the monitoring data is determined as an alarm value, and monitoring frequency is increased; when the monitoring data reaches or monitors the control standard value, should stop the construction immediately, can continue the construction after revising the support parameter;
in the information-based construction, after monitoring, various monitoring data should be sorted and analyzed in time, the stability of a monitored object is judged, and the stability is fed back to the construction in time to guide the construction. According to the monitoring control standard, the monitoring frequency can be selected as follows: generally, the monitoring frequency can be properly amplified in the III-level management stage; in the stage II management, the encryption monitoring times are noticed; paying close attention to the I-level management stage, enhancing monitoring, and enabling the monitoring frequency to reach 1-2 times/day or more; the details are shown in the following table:
monitoring management meter
| Managing levels | Managing displacements | Construction state |
| Ⅲ | U0＜Un/3 | Can be normally constructed |
| Ⅱ | Un/3≤U0≤2Un/3 | Attention should be paid to and monitoring is enhanced |
| Ⅰ | U0＞2Un/3 | Should take measures such as strengthening support |
In the table, U0-a measured displacement value; u shapen-an allowed displacement value; u shapenThe value of (a), namely the monitoring control standard.
Further, the air pressure value determination process specifically comprises the following steps:
the working pressure value of the pressurized warehouse entering air pressure operation is determined according to the principle that the stability of the tunnel face can be ensured and the upper stratum is not punctured by high-pressure air; the calculation method is as follows:
P＝Pa+Pw+Ppreparation of
In the formula: p is the working pressure of air pressure operation;
pa-calculating the water and soil pressure to the top of the tunnel excavation;
pw is the water covering pressure on the upper part of the soil body;
Ppreparation of-a preparation pressure of 0.2 bar;
Pa＝KaλH
ka-initiative soil pressure coefficient, Ka ═ tan2(45°-φ/2)；
Lambda-soil mass gravity; phi is the internal friction angle of the filling behind the wall;
h-soil body burial depth.
Further, the shield tail sealing process specifically comprises the following steps:
increasing synchronous grouting amount when a shield machine is in a stop position, ensuring full synchronous grouting filling, and simultaneously increasing the injection amount of shield tail grease to avoid shield tail sealing failure caused by overlarge grouting pressure flowing into the shield tail;
secondly, secondary grouting hole openings on the pipe piece are utilized for cement-water glass slurry refilling in 2-10 rings behind the shield tail, polyurethane is injected from radial holes of the shield body, a closed water stop ring is formed outside the shield shell, filling compactness and water isolation effect of wall back grouting are guaranteed, and underground water flow behind the shield tail is prevented from entering a warehouse;
after the sealing measure is finished, adjusting the pressure of the gas bin to be the opening pressure, and judging the water stopping effect of the shield tail by observing the pressure change and the liquid level change of the muddy water bin;
if the water-stopping effect is not ideal, a hole is formed in the pipe piece at the rear part of the shield tail to perform polyurethane refilling, the sealing effect of the shield tail is ensured, and after the sealing effect of the shield tail meets the specified requirement, the mud film is prepared.
Further, the mud film manufacturing process specifically comprises the following steps:
the proportion of the high-viscosity slurry can be properly adjusted according to the actual effect of the mud film on the face of the pressure opening person entering the warehouse to check, so as to ensure the quality of the mud film;
preparation of high viscosity slurry
The preparation of the high-viscosity slurry can be carried out by adopting a slurry preparation system of a slurry station, the preparation of the slurry is carried out strictly according to the mixing proportion, the high-viscosity slurry is required to be kept stand for 24 hours after the preparation, the performance of the prepared high-viscosity slurry is tested, and the high-viscosity slurry is transported to a shield machine by using a concrete transportation tank car after the specified requirements are met;
② pressure injection of high viscosity slurry
The pressure injection of the high-viscosity slurry is carried out by adopting a shield synchronous grouting system to carry out pressure injection into the slurry cabin through a slurry inlet pipe, the slurry in the cabin is replaced, and when a mud film is made, the mud film is produced in the cabinThe pressure needs to be higher than the working pressure by 0.2 bar-0.5 bar, the injection pressure of the high-viscosity slurry is not less than the opening pressure, and the pressure in the bin needs to be kept basically stable in the process of injecting the high-viscosity slurry to replace the slurry in the bin; the slurry is discharged in time in the process of injecting the high-viscosity slurry, the liquid level and the pressure in the bin are ensured to be stable, the slurry displacement amount is 1.2 times of the volume of the slurry in the bin, and when the size of the notch is 50mm, the square amount of the slurry to be displaced is 216.5m3(ii) a After replacement is finished, the cutter head is rotated at a low speed for a certain time, so that the quality of the formed mud film is ensured, and the ground breakdown caused by overlarge pressure is avoided;
③ slurry refilling
Along with the continuation of the opening time, in order to guarantee the continuous sealing effect of the excavation face mud film, after the last bin is finished every day, new high-viscosity slurry is injected in front of the cutter head in a pressing mode, the displaced slurry is discharged through the slurry outlet pipe, the pressure in the bin is guaranteed to be stable in the process, after the displacement is finished, a new mud film is formed in the bin, then the bin is kept still for not less than 2 hours, and the quality of the mud film is judged through the air supplement amount.
Further, the liquid level lowering process specifically comprises the following steps:
according to the storehouse operation purpose of pressing the area, confirm the liquid level and reduce the standard, generally divide and reduce muddy water storehouse liquid level and reduce atmospheric pressure storehouse liquid level, specifically do:
firstly, the liquid level of the air pressure bin is reduced
When parts such as a stone crusher and the like need to be overhauled only by pressing the slurry into the air bin or blockage at a slurry discharge port needs to be dredged, the liquid level of the air bin is reduced only by utilizing a slurry discharge pump equipped by a shield in a bypass circulation mode, meanwhile, the air pressure is increased for setting the pressure, and the liquid level reduction standard is generally slightly higher than a connecting channel between the bottom of the air bin and the muddy water bin; at the moment, the mud water bin is full-bin mud, the air pressure bin is small half-bin mud, and air pressure cannot flow into the mud water bin through the connecting channel of the two bins; in the process of reducing the liquid level and increasing the air pressure, gradient separation is carried out, namely when the liquid level is reduced by 1m, the pressure setting value is timely increased by 0.1bar, and the tunnel face instability caused by pressure mutation is avoided;
secondly, the liquid level of the muddy water bin is reduced
If the mud needs to enter the mud water bin for operations such as lower pressure sensor replacement, obstacle detection, cutter maintenance, boulder salvage and the like, the liquid level of the mud water bin needs to be reduced; after the liquid level of the air pressure bin is reduced to the designed position, a communicating valve between the muddy water bin and the air pressure bin is opened, so that the gas is communicated to the muddy water bin, and the air pressure setting value is adjusted; finally, the aim that the liquid levels of the two chambers are equal, the upper part is gas, and the lower part is muddy water is achieved, and the gas pressure is a calculated value for balancing the water and soil pressure in the middle of the tunnel face.
Further, the inspection process for the sealing effect of the muddy water bin specifically comprises the following steps:
performing a pressure maintaining test of an excavated bin before the initial bin opening, wherein the pressure maintaining time is not less than 2 hours; judging the pressure maintaining performance of the mud film according to the escape rate of mud water and gas in the bin, if the gas supply amount is less than 10% of the gas supply capacity, the pressure of the excavated bin can not change within 2 hours or does not fluctuate greatly, indicating that the pressure maintaining test is qualified, and if the gas supply amount is more than 50% of the gas supply capacity in the pneumatic bin opening process, stopping pneumatic operation and repairing the mud film by using slurry gas replacement until the pressure maintaining test is qualified;
the method for judging whether the air supply amount is greater than 50% of air supply capacity comprises the following steps:
4 air supply capacities of 12m are set for each shield tunneling machine pressure maintaining system3The total air supply capacity of the air compressor is 48m3/min；
If the gas supplement amount is less than 200m per hour3If the air supply quantity is less than 50% of the air supply capacity of the shield pressure maintaining system, the sealing effect meets the requirement of warehouse entry operation, and the pressure maintaining system can meet the requirement of pressure maintaining of gas in the warehouse;
if the air supplement amount is more than 200m per hour3If the gas supply capacity of the shield pressure maintaining system is 50% of the gas supply capacity of the shield pressure maintaining system with large gas supply amount, the relatively poor cabin inner sealing effect cannot meet the requirement of the warehouse entering operation, the pressure maintaining system cannot meet the requirement of the gas pressure maintaining in the cabin, the air pressure operation is stopped, and the slurry gas replacement is adopted to repair the mud film until the pressure maintaining and testing are qualified.
The method comprehensively analyzes the geological condition of the position of the shield tunneling machine according to geological detailed survey data, compensation data, recently-obtained muck composition and other information, determines the condition that the stratum is stable and has the shield tunneling machine pressure bin entering operation, and realizes preparation before pressure bin entering in shield tunneling construction and smooth pressure bin entering in shield tunneling construction by controlling a ground monitoring process, an air pressure value determining process, a shield tail sealing process, a mud film manufacturing process, a liquid level lowering process and a mud water bin sealing effect checking process.
Detailed Description
A preparation process before a pressure enters a cabin in shield tunneling construction comprises the steps of checking and backing up normal operation of shield cabin opening related equipment, preparing a cabin opening operation tool, preparing wind, water and electricity in a tunnel, clearing tools and materials, emergency materials, detecting living bodies and the like, comprehensively analyzing geological conditions of the position of a shield machine according to information such as geological detailed exploration materials, compensation materials, recently-discharged soil composition and the like, and determining the condition that stratum stability has the pressure entering operation of the shield machine, wherein the preparation process specifically comprises the following aspects:
(1) a ground monitoring process;
(2) a pressure value determination process;
(3) a shield tail sealing process;
(4) a mud film manufacturing process;
(5) a liquid level lowering process;
(6) inspection process for sealing effect of muddy water bin.
Further, the ground detection process specifically comprises:
(1) arrangement of monitoring points
Pressing a tool changing position of a bin in a land section, arranging 1 monitoring section 5m behind the mileage of a cutter head, arranging 1 monitoring section at the cutter head, and arranging 2 monitoring sections in front of the cutter head at an interval of 5m, wherein 4 monitoring sections are provided in total; 1 line is arranged on the middle line of each section line, 1 line is arranged at each 5m of the two sides of the middle line of the line, and each section is provided with 3 earth surface monitoring points; monitoring the frequency for 4 times/day before entering the warehouse under pressure, wherein the sedimentation rate does not exceed 2 mm/day, and the warehouse opening condition is met when the accumulated sedimentation does not exceed 2 cm; monitoring the frequency for 5 times/day during the warehousing, wherein the sedimentation rate does not exceed 3 mm/day, and when the accumulated sedimentation does not exceed 3cm, the operation in the warehouse can be continued; monitoring the frequency for 2 times/day in the normal tunneling process after the pressure enters the cabin, wherein the sedimentation rate does not exceed 3 mm/day, and the accumulated sedimentation does not exceed 3 cm;
(2) monitoring method
The transmitting transducer transmits acoustic pulses downwards from the sea surface, the acoustic pulses are transmitted downwards in water and reflected when encountering seabed media with different densities, and the reflected acoustic pulses are transmitted upwards in the sea water and received by the receiving transducer on the sea surface; according to the round-trip time of the acoustic pulse in the seawater and the sound velocity of the acoustic pulse in the seawater, the linear distance from the transducer to the seabed, namely the water depth, can be calculated, and the sinking condition of the seabed is judged according to the change of the water depth;
and (3) settlement calculation: uxiZ + H water, wherein: z is sea level height, H water is depth of water
For the same measuring point delta Ux ═ Uxi-Uxi-1
In the formula,. DELTA.Ux, Uxi、Uxi-1Respectively measuring the sinking value of the sea bed surface, the depth of the reference water surface from the sea bed surface for the ith time and the depth of the reference water surface from the sea bed surface for the ith-1 time for the measuring point at the x position;
(3) monitoring control criteria
The surface deformation should be controlled according to the following criteria:
the accumulated value of surface sedimentation is 25 mm;
controlling the change rate of the earth surface according to 3 mm/d;
thirdly, the accumulated value of vertical displacement and horizontal displacement of the shield tunnel structure is as follows: 30mm, rate of change: 3 mm/d;
fourthly, the clearance convergence accumulated value of the shield tunnel structure: 3% D, rate of change: 3 mm/d; wherein D is the tunnel excavation diameter;
(4) alarm value
According to design requirements and relevant specifications, when monitoring data reaches 70% of a monitoring control standard value, the monitoring data is determined as an alarm value, and monitoring frequency is increased; when the monitoring data reaches or monitors the control standard value, should stop the construction immediately, can continue the construction after revising the support parameter;
in the information-based construction, after monitoring, various monitoring data should be sorted and analyzed in time, the stability of a monitored object is judged, and the stability is fed back to the construction in time to guide the construction. According to the monitoring control standard, the monitoring frequency can be selected as follows: generally, the monitoring frequency can be properly amplified in the III-level management stage; in the stage II management, the encryption monitoring times are noticed; paying close attention to the I-level management stage, enhancing monitoring, and enabling the monitoring frequency to reach 1-2 times/day or more; the details are shown in the following table:
monitoring management meter
| Managing levels | Managing displacements | Construction state |
| Ⅲ | U0＜Un/3 | Can be normally constructed |
| Ⅱ | Un/3≤U0≤2Un/3 | Attention should be paid to and monitoring is enhanced |
| Ⅰ | U0＞2Un/3 | Should take measures such as strengthening support |
In the table, U0-a measured displacement value; u shapen-an allowed displacement value; u shapenThe value of (a), namely the monitoring control standard.
Further, the air pressure value determination process specifically comprises the following steps:
the working pressure value of the pressurized warehouse entering air pressure operation is determined according to the principle that the stability of the tunnel face can be ensured and the upper stratum is not punctured by high-pressure air; the calculation method is as follows:
P＝Pa+Pw+Ppreparation of
In the formula: p is the working pressure of air pressure operation;
pa-calculating the water and soil pressure to the top of the tunnel excavation;
pw is the water covering pressure on the upper part of the soil body;
Ppreparation of-a preparation pressure of 0.2 bar;
Pa＝KaλH
ka-initiative soil pressure coefficient, Ka ═ tan2(45°-φ/2)；
Lambda-soil mass gravity; phi is the internal friction angle of the filling behind the wall;
h-soil body burial depth.
Further, the shield tail sealing process specifically comprises the following steps:
increasing synchronous grouting amount when a shield machine is in a stop position, ensuring full synchronous grouting filling, and simultaneously increasing the injection amount of shield tail grease to avoid shield tail sealing failure caused by overlarge grouting pressure flowing into the shield tail;
secondly, secondary grouting hole openings on the pipe piece are utilized for cement-water glass slurry refilling in 2-10 rings behind the shield tail, polyurethane is injected from radial holes of the shield body, a closed water stop ring is formed outside the shield shell, filling compactness and water isolation effect of wall back grouting are guaranteed, and underground water flow behind the shield tail is prevented from entering a warehouse;
after the sealing measure is finished, adjusting the pressure of the gas bin to be the opening pressure, and judging the water stopping effect of the shield tail by observing the pressure change and the liquid level change of the muddy water bin;
if the water-stopping effect is not ideal, a hole is formed in the pipe piece at the rear part of the shield tail to perform polyurethane refilling, the sealing effect of the shield tail is ensured, and after the sealing effect of the shield tail meets the specified requirement, the mud film is prepared.
Further, the mud film manufacturing process specifically comprises the following steps:
the proportion of the high-viscosity slurry can be properly adjusted according to the actual effect of the mud film on the face of the pressure opening person entering the warehouse to check, so as to ensure the quality of the mud film;
preparation of high viscosity slurry
The preparation of the high-viscosity slurry can be carried out by adopting a slurry preparation system of a slurry station, the preparation of the slurry is carried out strictly according to the mixing proportion, the high-viscosity slurry is required to be kept stand for 24 hours after the preparation, the performance of the prepared high-viscosity slurry is tested, and the high-viscosity slurry is transported to a shield machine by using a concrete transportation tank car after the specified requirements are met;
② pressure injection of high viscosity slurry
The pressure injection of the high-viscosity slurry is carried out in a manner that a synchronous grouting system of a shield is adopted to carry out pressure injection into the slurry cabin through a slurry inlet pipe, the slurry in the cabin is replaced, when a mud film is made, the pressure in the cabin needs to be higher than the working pressure by 0.2-0.5 bar, the injection pressure of the high-viscosity slurry is not less than the pressure of opening the cabin, and the pressure in the cabin needs to be kept basically stable in the process of injecting the high-viscosity slurry into the displacement cabin; the slurry is discharged in time in the process of injecting the high-viscosity slurry, the liquid level and the pressure in the bin are ensured to be stable, the slurry displacement amount is 1.2 times of the volume of the slurry in the bin, and when the size of the notch is 50mm, the square amount of the slurry to be displaced is 216.5m3(ii) a After replacement is finished, the cutter head is rotated at a low speed for a certain time, so that the quality of the formed mud film is ensured, and the ground breakdown caused by overlarge pressure is avoided;
③ slurry refilling
Along with the continuation of the opening time, in order to guarantee the continuous sealing effect of the excavation face mud film, after the last bin is finished every day, new high-viscosity slurry is injected in front of the cutter head in a pressing mode, the displaced slurry is discharged through the slurry outlet pipe, the pressure in the bin is guaranteed to be stable in the process, after the displacement is finished, a new mud film is formed in the bin, then the bin is kept still for not less than 2 hours, and the quality of the mud film is judged through the air supplement amount.
Further, the liquid level lowering process specifically comprises the following steps:
according to the storehouse operation purpose of pressing the area, confirm the liquid level and reduce the standard, generally divide and reduce muddy water storehouse liquid level and reduce atmospheric pressure storehouse liquid level, specifically do:
firstly, the liquid level of the air pressure bin is reduced
When parts such as a stone crusher and the like need to be overhauled only by pressing the slurry into the air bin or blockage at a slurry discharge port needs to be dredged, the liquid level of the air bin is reduced only by utilizing a slurry discharge pump equipped by a shield in a bypass circulation mode, meanwhile, the air pressure is increased for setting the pressure, and the liquid level reduction standard is generally slightly higher than a connecting channel between the bottom of the air bin and the muddy water bin; at the moment, the mud water bin is full-bin mud, the air pressure bin is small half-bin mud, and air pressure cannot flow into the mud water bin through the connecting channel of the two bins; in the process of reducing the liquid level and increasing the air pressure, gradient separation is carried out, namely when the liquid level is reduced by 1m, the pressure setting value is timely increased by 0.1bar, and the tunnel face instability caused by pressure mutation is avoided;
secondly, the liquid level of the muddy water bin is reduced
If the mud needs to enter the mud water bin for operations such as lower pressure sensor replacement, obstacle detection, cutter maintenance, boulder salvage and the like, the liquid level of the mud water bin needs to be reduced; after the liquid level of the air pressure bin is reduced to the designed position, a communicating valve between the muddy water bin and the air pressure bin is opened, so that the gas is communicated to the muddy water bin, and the air pressure setting value is adjusted; finally, the aim that the liquid levels of the two chambers are equal, the upper part is gas, and the lower part is muddy water is achieved, and the gas pressure is a calculated value for balancing the water and soil pressure in the middle of the tunnel face.
Further, the inspection process for the sealing effect of the muddy water bin specifically comprises the following steps:
performing a pressure maintaining test of an excavated bin before the initial bin opening, wherein the pressure maintaining time is not less than 2 hours; judging the pressure maintaining performance of the mud film according to the escape rate of mud water and gas in the bin, if the gas supply amount is less than 10% of the gas supply capacity, the pressure of the excavated bin can not change within 2 hours or does not fluctuate greatly, indicating that the pressure maintaining test is qualified, and if the gas supply amount is more than 50% of the gas supply capacity in the pneumatic bin opening process, stopping pneumatic operation and repairing the mud film by using slurry gas replacement until the pressure maintaining test is qualified;
the method for judging whether the air supply amount is greater than 50% of air supply capacity comprises the following steps:
4 air supply capacities of 12m are set for each shield tunneling machine pressure maintaining system3The total air supply capacity of the air compressor is 48m3/min；
If the gas supplement amount is less than 200m per hour3If the air supply quantity is less than 50% of the air supply capacity of the shield pressure maintaining system, the sealing effect is achievedIf the fruits meet the requirement of warehouse entry operation, the pressure maintaining system can meet the requirement of maintaining the pressure of gas in the warehouse;
if the air supplement amount is more than 200m per hour3If the gas supply capacity of the shield pressure maintaining system is 50% of the gas supply capacity of the shield pressure maintaining system with large gas supply amount, the relatively poor cabin inner sealing effect cannot meet the requirement of the warehouse entering operation, the pressure maintaining system cannot meet the requirement of the gas pressure maintaining in the cabin, the air pressure operation is stopped, and the slurry gas replacement is adopted to repair the mud film until the pressure maintaining and testing are qualified.
The method comprehensively analyzes the geological condition of the position of the shield tunneling machine according to geological detailed survey data, compensation data, recently-obtained muck composition and other information, determines the condition that the stratum is stable and has the shield tunneling machine pressure bin entering operation, and realizes preparation before pressure bin entering in shield tunneling construction and smooth pressure bin entering in shield tunneling construction by controlling a ground monitoring process, an air pressure value determining process, a shield tail sealing process, a mud film manufacturing process, a liquid level lowering process and a mud water bin sealing effect checking process.
Claims (5)
1. The preparation process before the shield is pressed into the cabin in the shield tunneling construction is characterized by comprising the steps of checking and backing up normal operation of shield opening related equipment, preparing a cabin opening operation tool, preparing wind, water and electricity in a tunnel, clearing tools and materials, emergency materials and living body detection, comprehensively analyzing geological conditions of the position of a shield according to geological detailed exploration materials, reconnaissance materials and recently-obtained muck composition information, and determining the condition that the stratum is stable and has the shield machine pressing into the cabin operation, and specifically comprises the following aspects:
(1) a ground monitoring process;
(2) a pressure value determination process;
(3) a shield tail sealing process;
(4) a mud film manufacturing process;
(5) a liquid level lowering process;
(6) a muddy water bin sealing effect inspection process;
the shield tail sealing process specifically comprises the following steps:
increasing synchronous grouting amount when a shield machine is in a stop position, ensuring full synchronous grouting filling, and simultaneously increasing the injection amount of shield tail grease to avoid shield tail sealing failure caused by overlarge grouting pressure flowing into the shield tail;
secondly, secondary grouting hole openings on the pipe piece are utilized for cement-water glass slurry refilling in 2-10 rings behind the shield tail, polyurethane is injected from radial holes of the shield body, a closed water stop ring is formed outside the shield shell, filling compactness and water isolation effect of wall back grouting are guaranteed, and underground water flow behind the shield tail is prevented from entering a warehouse;
after the sealing measure is finished, adjusting the pressure of the gas bin to be the opening pressure, and judging the water stopping effect of the shield tail by observing the pressure change and the liquid level change of the muddy water bin;
if the water-stopping effect is not ideal, a hole is formed in the duct piece at the rear part of the shield tail to perform polyurethane refilling, so that the sealing effect of the shield tail is ensured, and the mud film is prepared after the sealing effect of the shield tail meets the specified requirement;
the ground monitoring process specifically comprises the following steps:
(1) arrangement of monitoring points
Pressing a tool changing position of a bin in a land section, arranging 1 monitoring section 5m behind the mileage of a cutter head, arranging 1 monitoring section at the cutter head, and arranging 2 monitoring sections in front of the cutter head at an interval of 5m, wherein 4 monitoring sections are provided in total; 1 earth surface monitoring point is arranged on the middle line of each section line, 1 earth surface monitoring point is arranged at each 5m of the two sides of the middle line of the line, and 3 earth surface monitoring points are arranged on each section; monitoring the frequency for 4 times/day before entering the warehouse under pressure, wherein the sedimentation rate does not exceed 2 mm/day, and the warehouse opening condition is met when the accumulated sedimentation does not exceed 2 cm; monitoring the frequency for 5 times/day during the warehousing, wherein the sedimentation rate does not exceed 3 mm/day, and when the accumulated sedimentation does not exceed 3cm, the operation in the warehouse can be continued; monitoring the frequency for 2 times/day in the normal tunneling process after the pressure enters the cabin, wherein the sedimentation rate does not exceed 3 mm/day, and the accumulated sedimentation does not exceed 3 cm;
(2) monitoring method
The transmitting transducer transmits acoustic pulses downwards from the sea surface, the acoustic pulses are transmitted downwards in water and reflected when encountering seabed media with different densities, and the reflected acoustic pulses are transmitted upwards in the sea water and received by the receiving transducer on the sea surface; according to the round-trip time of the acoustic pulse in the seawater and the sound velocity of the acoustic pulse in the seawater, the linear distance from the transducer to the seabed, namely the water depth, can be calculated, and the sinking condition of the seabed is judged according to the change of the water depth;
and (3) settlement calculation: uxiZ + H water, wherein: z is sea level height, H water is depth of water
For the same measuring point delta Ux ═ Uxi-Uxi-1
In the formula,. DELTA.Ux, Uxi、Uxi-1Respectively measuring the sinking value of the sea bed surface, the depth of the reference water surface from the sea bed surface for the ith time and the depth of the reference water surface from the sea bed surface for the ith-1 time for the measuring point at the x position;
(3) monitoring control criteria
The surface deformation should be controlled according to the following criteria:
the accumulated value of surface sedimentation is 25 mm;
controlling the change rate of the earth surface according to 3 mm/d;
thirdly, the accumulated value of vertical displacement and horizontal displacement of the shield tunnel structure is as follows: 30mm, rate of change: 3 mm/d;
fourthly, the clearance convergence accumulated value of the shield tunnel structure: 3% D, rate of change: 3 mm/d; wherein D is the tunnel excavation diameter;
(4) alarm value
According to design requirements and relevant specifications, when monitoring data reaches 70% of a monitoring control standard value, the monitoring data is determined as an alarm value, and monitoring frequency is increased; when the monitoring data reaches or monitors the control standard value, should stop the construction immediately, can continue the construction after revising the support parameter;
in the information-based construction, after monitoring, various monitoring data should be sorted and analyzed in time, the stability of a monitored object is judged, and the stability is fed back to the construction in time to guide the construction; according to the monitoring control standard, selecting a monitoring frequency: monitoring the frequency in a III-level management stage and properly amplifying the frequency; in the stage II management, the encryption monitoring times are noticed; paying close attention to the I-level management order, enhancing monitoring, and enabling the monitoring frequency to reach 1-2 times/day or more; the details are shown in the following table:
monitoring management meter
In the table, U0-a measured displacement value; u shapen-an allowed displacement value; u shapenThe value of (a), namely the monitoring control standard.
2. The process of claim 1, wherein the pressure value determination process specifically comprises:
the working pressure value of the pressurized warehouse entering air pressure operation is determined according to the principle that the stability of the tunnel face can be ensured and the upper stratum is not punctured by high-pressure air; the calculation method is as follows:
P＝Pa+Pw+Ppreparation of
In the formula: p is the working pressure of air pressure operation;
pa-calculating the water and soil pressure to the top of the tunnel excavation;
pw is the water covering pressure on the upper part of the soil body;
Ppreparation of-a preparation pressure of 0.2 bar;
Pa＝KaλH
ka-initiative soil pressure coefficient, Ka ═ tan2(45°-φ/2)；
Lambda-soil mass gravity; phi is the internal friction angle of the filling behind the wall;
h-soil body burial depth.
3. The process as claimed in claim 1, wherein the mud film manufacturing process specifically comprises:
the proportion of the high-viscosity slurry is properly adjusted according to the actual effect of the mud film on the face of the pressure opening person entering the warehouse to check, so as to ensure the quality of the mud film;
preparation of high viscosity slurry
The preparation of the high-viscosity mud is carried out by adopting a slurry preparation system of a mud station, the preparation of the mud is carried out strictly according to the mixing ratio, the high-viscosity mud is required to stand for 24 hours after the preparation is finished, the performance of the prepared high-viscosity mud is tested, and the high-viscosity mud is transported to a shield machine by using a concrete transportation tank car after the specified requirements are met;
② pressure injection of high viscosity slurry
The pressure injection of the high-viscosity slurry is carried out in a manner that a synchronous grouting system of a shield is adopted to carry out pressure injection into the slurry cabin through a slurry inlet pipe, the slurry in the cabin is replaced, when a mud film is made, the pressure in the cabin needs to be higher than the working pressure by 0.2-0.5 bar, the injection pressure of the high-viscosity slurry is not less than the pressure of opening the cabin, and the pressure in the cabin needs to be kept basically stable in the process of injecting the high-viscosity slurry into the displacement cabin; the slurry is discharged in time in the process of injecting the high-viscosity slurry, the liquid level and the pressure in the bin are ensured to be stable, the slurry displacement amount is 1.2 times of the volume of the slurry in the bin, and when the size of the notch is 50mm, the square amount of the slurry to be displaced is 216.5m3(ii) a After the replacement is finished, the cutter head is rotated at a low speed for a certain time, so that the quality of the formed mud film is ensured, and the ground caused by overlarge pressure is avoidedIs broken down;
③ slurry refilling
Along with the continuation of the opening time, in order to guarantee the continuous sealing effect of the excavation face mud film, after the last bin is finished every day, new high-viscosity slurry is injected in front of the cutter head in a pressing mode, the displaced slurry is discharged through the slurry outlet pipe, the pressure in the bin is guaranteed to be stable in the process, after the displacement is finished, a new mud film is formed in the bin, then the bin is kept still for not less than 2 hours, and the quality of the mud film is judged through the air supplement amount.
4. The process of claim 1, wherein the level-lowering process specifically comprises:
according to the storehouse operation purpose of pressing the area, confirm the liquid level and reduce the standard, divide and reduce muddy water storehouse liquid level and reduce atmospheric pressure storehouse liquid level, specifically do:
firstly, the liquid level of the air pressure bin is reduced
When the pressure is only needed to enter the air pressure bin to overhaul stone crusher parts or dredge blockage at a slurry discharge port, the liquid level of the air pressure bin is reduced only by utilizing a slurry discharge pump equipped by a shield in a bypass circulation mode, and the air pressure is increased to set the pressure, wherein the liquid level reduction standard is slightly higher than a connecting channel between the bottom of the air pressure bin and the muddy water bin; at the moment, the mud water bin is full-bin mud, the air pressure bin is small half-bin mud, and air pressure cannot flow into the mud water bin through the connecting channel of the two bins;
in the process of reducing the liquid level and increasing the air pressure, gradient separation is carried out, namely when the liquid level is reduced by 1m, the pressure setting value is timely increased by 0.1bar, and the tunnel face instability caused by pressure mutation is avoided;
secondly, the liquid level of the muddy water bin is reduced
If the mud needs to enter the mud water bin for the operations of lower pressure sensor replacement, obstacle detection, cutter maintenance and boulder salvage, the liquid level of the mud water bin needs to be reduced; after the liquid level of the air pressure bin is reduced to the designed position, a communicating valve between the muddy water bin and the air pressure bin is opened, so that the gas is communicated to the muddy water bin, and the air pressure setting value is adjusted; finally, the aim that the liquid levels of the two chambers are equal, the upper part is gas, and the lower part is muddy water is achieved, and the gas pressure is a calculated value for balancing the water and soil pressure in the middle of the tunnel face.
5. The process as claimed in claim 1, wherein the inspection process for the sealing effect of the muddy water bin specifically comprises the following steps: performing a pressure maintaining test of an excavated bin before the initial bin opening, wherein the pressure maintaining time is not less than 2 h; judging the pressure maintaining performance of the mud film according to the escape rate of mud water and gas in the bin, if the gas supply amount is less than 10% of the gas supply capacity, the pressure of the excavated bin can not change within 2 hours or does not fluctuate greatly, indicating that the pressure maintaining test is qualified, and if the gas supply amount is more than 50% of the gas supply capacity in the pneumatic bin opening process, stopping pneumatic operation and repairing the mud film by using slurry gas replacement until the pressure maintaining test is qualified;
the method for judging whether the air supply amount is greater than 50% of air supply capacity comprises the following steps:
each pressure maintaining system of the shield machine is provided with 4 air compressors with the air supply capacity of 12m3/min and the total air supply capacity of 48m3/min；
If the gas supplement amount is less than 200m per hour3If the air supply quantity is less than 50% of the air supply capacity of the shield pressure maintaining system, the sealing effect meets the requirement of warehouse entry operation, and the pressure maintaining system meets the requirement of pressure maintaining of gas in the warehouse;
if the air supplement amount is more than 200m per hour3If the air supply amount is larger than 50% of the air supply capacity of the shield pressure maintaining system, the warehouse sealing effect is poor and the warehouse entering operation requirement cannot be met, the pressure maintaining system cannot meet the warehouse gas pressure maintaining requirement, the air pressure operation is stopped, and the slurry gas replacement is adopted to repair the mud film again until the pressure maintaining and pressure testing are qualified.
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| CN111502678A (en) * | 2020-05-13 | 2020-08-07 | 中铁二十二局集团轨道工程有限公司 | Method for forming mud film of slurry shield in highly permeable stratum |
| CN113323679B (en) * | 2021-06-24 | 2023-03-24 | 广州地铁设计研究院股份有限公司 | Shield opening operation method for water-rich stratum |
| 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 |
| CN114735971B (en) * | 2022-02-28 | 2023-03-24 | 中铁隧道局集团有限公司 | Composite paste mud paste and preparation and application thereof |
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| CN101666231A (en) * | 2009-06-24 | 2010-03-10 | 中铁隧道股份有限公司 | Shield machine warehouse entry method |
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