CN108533278B - Large-diameter slurry shield earth covering balance comprehensive receiving construction method under complex environment strong permeable stratum working condition - Google Patents
Large-diameter slurry shield earth covering balance comprehensive receiving construction method under complex environment strong permeable stratum working condition Download PDFInfo
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- CN108533278B CN108533278B CN201810342347.2A CN201810342347A CN108533278B CN 108533278 B CN108533278 B CN 108533278B CN 201810342347 A CN201810342347 A CN 201810342347A CN 108533278 B CN108533278 B CN 108533278B
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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
- E21D9/0607—Making by using a driving shield, i.e. advanced by pushing means bearing against the already placed lining the shield being provided with devices for lining the tunnel, e.g. shuttering
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- 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
- E21D9/08—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
Abstract
The invention discloses a soil covering balance comprehensive receiving construction method for a large-diameter slurry shield under the working condition of a strong permeable stratum in a complex environment, which comprises the following steps: constructing a closed wall and a receiving base in the well; secondly, receiving end foundation reinforcement; (III) breaking the tunnel portal; and (IV) connecting the hole outlet ring and welding and sealing the hole door steel plate. The invention has the beneficial effects that: the quality is high: the shield machine has good control of receiving posture, reasonable counter-force and compact segment assembly, and balanced front and back pressure of water and soil after filling and irrigating without risk of water leakage around the shell. The safety is high: the construction method effectively avoids the risks of tunnel portal leakage, large splicing gaps of shield machine carrying heads and tunnel outlet ring duct pieces, easy leakage and the like in the receiving process of the large-diameter shield, and greatly improves the production safety. The construction cost is low: compared with other measures, the mechanical equipment and materials used by the method are conventional materials, and the cost is low.
Description
Technical Field
The invention relates to a soil covering balance comprehensive receiving construction method for a large-diameter slurry shield under the working condition of a strong permeable stratum in a complex environment, and belongs to the technical field of building construction.
Background
The strengthening of national strength and the progress of technology make the shield construction more and more accepted domestically. At present, the cities of the domestic subway which uses the shield method include Shanghai, Guangzhou, Nanjing, Beijing, Shenzhen, Tianjin, Xian, Chengdu, Shenyang, Hangzhou, Qingdao and the like, and other cities are being established. Due to the advantages of shield construction in terms of construction period, safety, quality and the like, some cities, such as Shanghai, Nanjing, Wuhan and other river-crossing tunnel projects, are increasingly constructed by adopting a shield method. However, the construction technology quality requirement of each construction stage of the shield is strict, the safety requirement is high, and particularly, the construction of a large shield is carried out at a position close to a river section and with a higher underground water level, so that the receiving construction technology of the shield with the ultra-large diameter needs to be summarized and improved continuously.
According to projects such as Nanjing Yangtze river tunnel, Yangzhou thin West lake tunnel and Wuhan subway No. 8 line cross-river tunnel which are built by the medium-iron fourteen local group company, an ultra-large diameter shield tunnel is adopted for construction aiming at the projects, risks such as cave gate collapse removal, leakage, splicing dislocation of out-of-tunnel segments, leakage of the peripheral ring of a machine body and the like can exist in the shield receiving process, and the construction method is formed on the basis of summarizing successful completion of the Nanjing Yangtze river tunnel, the Yangzhou thin West lake tunnel and the Wuhan subway No. 8 line large-diameter cross-river tunnel projects.
The construction method solves the problems of collapse, leakage, failure of starting sealing, leakage and the like of a starting tunnel portal reinforcing body, and ensures the safety and reliability of shield starting. Practice proves that the construction method is mature and reliable, can ensure the safety and quality of engineering, quickens the production progress and creates good economic benefit. The construction method has good popularization value in the aspects of safe receiving and reliable quality of all large-diameter shields of underground railways, highway engineering, municipal engineering and the like.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the earth covering balance comprehensive receiving construction method for the large-diameter slurry shield under the working condition of the complex environment strong permeable stratum is provided.
In order to solve the technical problems, the invention adopts the technical scheme that:
the invention provides a soil covering balance comprehensive receiving construction method for a large-diameter slurry shield under the working condition of a complex environment strong permeable stratum, which comprises the following steps:
construction of (I) well inner closing wall and receiving base
1) And (3) construction of an inner closed wall:
the closed well structure is constructed during construction of the receiving well structure, the closed structure is formed according to the site occupation range of shield equipment in the receiving well, three end main body structures of the receiving well are used as three-face blocking walls, one blocking wall in front of shield tunneling is a temporary blocking wall, a steel-concrete structure is adopted, C25 concrete is poured, the thickness of the blocking wall is 25-30CM, and the receiving well is dismantled after cleaning in the receiving well is completed.
2) Receiving base construction
The shield receiving adopts a scheme that earth covering and water filling are carried out to reach the receiving base in a dark mode, the receiving base simultaneously plays a role in supporting the shield tunneling machine and providing horizontal launching force for shield tunneling, the base needs to be cut off by means of the cutting function of the shield tunneling machine in the tunneling section in the shield tunneling process of the receiving base, therefore, the strength of the shield receiving base is not high enough, but the shield tunneling machine can not be prevented from carrying the head too low, the receiving base adopts an M10 cement mortar structure, mortar filling is carried out on a receiving well in advance, the surface height of the mortar is enabled to be at the 1/5 position of a shield cutter head, and the mortar base is cut by means of the tunneling function of the shield tunneling machine after the shield exits from a hole, so that. And a channel is reserved at the joint of the cutter head, the shield body and the shield tail and at the outer edge of the shield tail, so that the shield machine is convenient to disassemble.
The receiving base is divided into two rows and six blocks, and reserved cutting grooves are respectively designed among the six blocks of the base according to the boundary line of the shield body and the shield tail and the respective blocks. 1/5 that the elevation of the top of the receiving base is higher than the excavation diameter of the cutter head of the shield tunneling machine than the bottom of the cutter head is higher than the cutter head, and provides the counterforce when the shield tunneling machine moves forwards.
The width of the vertical reserved groove of the shield body and the shield tail is 1.1m, and the width of the reserved groove of the shield tail and the shield body disassembly block is 1 m. The base with the height of 50cm is filled at the bottom of the base, and the six bases are connected, so that the whole stress of the shield during forward movement is facilitated. The upper surface of the base is 2.7% uphill, consistent with the tunnel axis slope.
Foundation stabilization of (II) receiving end
The range requirement of the reinforcing body is as follows: the reinforcement length is greater than the length of a main engine of the shield machine, after a cutter head of the machine body breaks a tunnel portal, a shield tail is in a reinforcement area, it is guaranteed that a leakage channel is not formed between an unreinforced area behind the shield tail and the tunnel portal, the reinforcement width is 3 meters (including the position of a standby precipitation well) of the outer edge of the diameter of the shield machine, and end reinforcement is completed 1 month before the shield machine reaches the reinforcement area, so that the cement reinforcement strength of the reinforcement area is guaranteed.
Adopting a closed plain wall, a triaxial mixing pile and a high-pressure jet grouting pile to perform seam filling and reinforcing; in order to ensure the safety of the broken tunnel, a row of plain concrete walls are additionally arranged at the opening, the depth of each wall is 5m from the bottom plate of the channel structure to the position below the bottom of the tunnel, and the width of each wall is 3m of the two sides of the tunnel.
3-4 drainage dewatering wells are arranged in the range of the reinforced area, and once a problem occurs in the receiving process, the drainage dewatering wells are started emergently to ensure safety.
(III) door breaking
And the continuous wall breaking work in the portal area can be carried out under the condition that the reinforcing body meets the design strength requirement and ensures that the shield machine is provided with a receiving inlet.
Before the end wall enclosure structure is drilled, a horizontal probe hole is firstly constructed, the end soil body reinforcing effect is tested, part of probe holes are required to be only dripped, no silt exists in water, and the total amount of water seepage in 24 hours is not more than 5L. The number of the horizontal probing holes is not less than 5, the horizontal probing holes are distributed at the upper and lower, left and right quadrant points and the central point of the reserved hole of the main body structure, and the length of each horizontal probing hole is not less than 3 m.
In order to reduce the influence of tunnel portal breakage on soil in the range of the tunnel ring as much as possible and ensure that the shield machine enters the tunnel safely, the tunnel portal continuous wall is chiseled twice. Breaking the outer concrete for 10cm for the first time, stripping the reinforcing steel bars on the inner layer of the underground continuous wall, and continuously breaking for 70 cm; and the second breaking arrangement is carried out when the cutter head of the shield machine tunnels to the plain wall of the tunnel portal, the remaining 20cm tunnel portal is broken, and after the breaking is finished, concrete residues are cleaned up and lifted out of the foundation pit. And after the portal is broken, immediately backfilling sandy soil and recharging water.
Closely observing the displacement change of the wall body in the portal range in the breaking process, and immediately stopping the breaking of the portal continuous wall once the wall body or the soil body in the portal ring is greatly deformed or has a water leakage phenomenon, and grouting and plugging the water leakage position to prevent water and soil loss; if no abnormal condition is found, the destruction can be continued. The breaking can not be completed at one time, and delamination is needed.
The portal is a large risk point, tracking monitoring and measurement are carried out for the portal, and measurement distribution points comprise a receiving end settlement observation point, a portal removal horizontal observation point and an inclinometry observation point. The settlement observation points are 9 points arranged on the tunnel door purlin, 16 points are arranged on the continuous wall, 4 points are respectively arranged on two sides of the central line of the reinforced section, the transverse distance is 4m, and the settlement observation points can be properly adjusted according to the terrain. The horizontal observation point adopts that a convergence instrument is arranged on a continuous wall surface of the portal to measure the horizontal displacement of the wall body, 5 lifting lugs are welded at the positions of the center line at the top of the embedded steel ring and the horizontal distances of 3m and 6m at two sides, and the displacement condition of the wall body is determined by measuring the distance change between the lifting wire and the wall surface by adopting a lifting wire and a steel ruler during measurement. The inclination measurement observation points are measured by utilizing the existing side inclination points of the receiving well end of the Huangpu road station during construction, and are monitored by adopting an inclinometer.
Filling sand and soil in the receiving well, irrigating water and cleaning after receiving
In order to stabilize the ground layer when the shield receives the ground layer and reduce mud gushing and sand gushing and ground surface settlement risks between the large-diameter shield and the portal ring, after the portal concrete is broken, the vertical shaft is backfilled with sandy soil (in order to facilitate pumping and drainage by a slurry discharge system of the shield machine, the sandy soil is more convenient to clean, sundries such as concrete lumps, reinforcing steel bars, templates and the like are prevented from being mixed in the sandy soil as much as possible, otherwise, the slurry outlet pump and the pipeline of the shield machine are blocked), the lower part of the shield machine passes through the portal ring and is supported by a soil body, the backfilling clay thickness is 3m below the top of the shield machine, and the backfilled sandy soil is leveled and compacted by adopting. In order to ensure the balance of internal and external pressure during receiving, clear water is filled into the working well after clay is backfilled, and meanwhile, the backfilled sandy soil in the working well is tightly filled with water, and the filling depth is that the top of the tunnel door is flush. Can continue to carry out muddy water circulation and synchronous slip casting forward the propulsion in-process at the shield entering working well, ensure that nearly portal segment section of jurisdiction ring can slip casting closely, control section of jurisdiction is out of shape and is subsided.
After the shield receiving is finished, the filled sandy soil is transported to a mud-water separation device through a pipeline by using a slurry circulating system of the shield machine to carry out slag-soil separation and outward transportation. And washing the sand in the receiving well by using a high-pressure water gun, and finally, manually cleaning the residual sand which does not fall dead corners.
(IV) go out hole ring connection and portal steel plate welding seal
After the shield machine goes out the tunnel portal, the shield machine reduces the counterforce for the duct piece, and 5 to 10 ring connections of going out the tunnel ring are similar to the ring that advances the tunnel ring for avoiding the phenomenon such as the assembling of duct piece is not tight, and normal hoop is vertical bolted connection back, adopts the inboard vertical and hoop reservation steel sheet welded connection of duct piece to strengthen.
The shield machine is driven into a receiving well, after the last steel wire brush of the shield tail is completely separated from a tunnel door, the last segment is arranged at the sealing ring, a steel plate with the width of 500mm is pre-embedded on one side of the outer side surface of the last segment, and the thickness of the pre-embedded steel plate is 10 mm. After the shield tail of the shield tunneling machine completely penetrates through the sealing plate, welding the edge of the circular ring plate with the embedded steel plate on the outer side of the final ring segment by using a sealing steel plate with the thickness of 20mm to form sealing so as to ensure the sealing effect of the tunnel outlet ring segment and ensure the safety and reliability of a permanent structure. The height of the secondary sealing weld joint is 10mm, and the weld joint is continuous and does not leak. The steel plate for sealing is 50mm higher than the circular ring plate, and the specific situation can be adjusted according to the gap between the circular ring plate and the final ring segment.
And (3) completing welding of the tunnel portal sealing steel plate, reserving a secondary grouting hole through the duct piece to perform secondary grouting after the wall of the duct piece goes out of the tunnel, ensuring that the wall is full and compact, and finishing the shield receiving process flow.
The application range is as follows:
the method is suitable for a shield receiving process adopting shield construction in tunnel engineering under complex geological conditions.
The process principle is as follows:
the shield receiving is a big difficulty of shield construction, and the following problems exist during the construction:
1) the diameter of the tunnel portal is large, and the risk of breaking the tunnel portal of the concrete diaphragm wall is large;
2) the shield machine enters a receiving well and geological condition changes easily to form head carrying risks;
3) the counterforce of the pipe piece is reduced when a palm in front of a shield machine enters a receiving well, so that the assembly gap of the pipe piece is large and water leakage is easy to occur;
4) the water and soil pressure imbalance of the circumference of the machine body after the shield machine with strong water permeability of the stratum enters the receiving well easily causes water gushing and sand gushing of the circumference of the machine body.
Aiming at the characteristics, a corresponding processing method is determined to be adopted so as to overcome the risks. Firstly, the leakage risk when a tunnel portal is broken is reduced, receiving end reinforcement and precipitation auxiliary measures are made, secondly, a mortar base control measure of a shield machine loading prevention head is taken, thirdly, the counter-force guarantee of a tunnel outlet ring segment is ensured, sandy soil is backfilled in a well, necessary counter-force is formed for the shield machine, water is poured in the well to keep the water and soil pressure balance of the periphery of the shield machine body, and a leakage water channel is ensured not to be formed due to tunnel outlet.
The invention has the beneficial effects that:
the quality is high: the shield machine has good control of receiving posture, reasonable counter-force and compact segment assembly, and balanced front and back pressure of water and soil after filling and irrigating without risk of water leakage around the shell.
The safety is high: the construction method effectively avoids the risks of tunnel portal leakage, large splicing gaps of shield machine carrying heads and tunnel outlet ring duct pieces, easy leakage and the like in the receiving process of the large-diameter shield, and greatly improves the production safety.
The construction cost is low: compared with other measures, the mechanical equipment and materials used by the method are conventional materials, and the cost is low.
The Wuhan subway No. 8 line cross-river tunnel engineering starts in 2016, 5 and 28 days, the shield machine arrives at a receiving end reinforcing area in 2017, 8 and 3 days, the tunnel is smoothly communicated in 2017, 8 and 9 days, the tunnel door steel plate sealing is smoothly completed in 8 and 14 days, and the shield safety receiving is smoothly completed in only 10 days.
In the shield receiving process, in order to ensure the safety and smoothness of the project, a hole-front reinforcing measure of a plain wall and a stirring pile is adopted, and aiming at technical measures of hole door breaking, receiving base construction and sand filling and water filling, the provided measures are strong in pertinence, feasible, economical and reasonable, the safety and progress of the project are ensured, the total construction period is saved by 5 days, and indirect economic benefits are three million yuan. And 3000 cubes of foundation pit earthwork are utilized, the cost of purchasing sand outside is saved by 30 ten thousand yuan, and the method plays a very important role in ensuring the quality of engineering and accelerating the construction progress.
The adopted construction scheme and technical measures can well solve the problem of the receiving safety quality risk of the super-large-diameter shield, and can be well popularized in the safety receiving of the super-large-diameter shield in China
Detailed Description
Example 1
The earth covering balance comprehensive receiving construction method for the large-diameter slurry shield under the working condition of the complex environment strong permeable stratum comprises the following steps:
construction of (I) well inner closing wall and receiving base
1) And (3) construction of an inner closed wall:
the closed well structure is constructed during construction of the receiving well structure, the closed structure is formed according to the site occupation range of shield equipment in the receiving well, three end main body structures of the receiving well are used as three-face blocking walls, one blocking wall in front of shield tunneling is a temporary blocking wall, a steel-concrete structure is adopted, C25 concrete is poured, the thickness of the blocking wall is 25-30CM, and the receiving well is dismantled after cleaning in the receiving well is completed.
2) Receiving base construction
The shield receiving adopts a scheme that earth covering and water filling are carried out to reach the receiving base in a dark mode, the receiving base simultaneously plays a role in supporting the shield tunneling machine and providing horizontal launching force for shield tunneling, the base needs to be cut off by means of the cutting function of the shield tunneling machine in the tunneling section in the shield tunneling process of the receiving base, therefore, the strength of the shield receiving base is not high enough, but the shield tunneling machine can not be prevented from carrying the head too low, the receiving base adopts an M10 cement mortar structure, mortar filling is carried out on a receiving well in advance, the surface height of the mortar is enabled to be at the 1/5 position of a shield cutter head, and the mortar base is cut by means of the tunneling function of the shield tunneling machine after the shield exits from a hole, so that. And a channel is reserved at the joint of the cutter head, the shield body and the shield tail and at the outer edge of the shield tail, so that the shield machine is convenient to disassemble.
The receiving base is divided into two rows and six blocks, and reserved cutting grooves are respectively designed among the six blocks of the base according to the boundary line of the shield body and the shield tail and the respective blocks. 1/5 that the elevation of the top of the receiving base is higher than the excavation diameter of the cutter head of the shield tunneling machine than the bottom of the cutter head is higher than the cutter head, and provides the counterforce when the shield tunneling machine moves forwards.
The width of the vertical reserved groove of the shield body and the shield tail is 1.1m, and the width of the reserved groove of the shield tail and the shield body disassembly block is 1 m. The base with the height of 50cm is filled at the bottom of the base, and the six bases are connected, so that the whole stress of the shield during forward movement is facilitated. The upper surface of the base is 2.7% uphill, consistent with the tunnel axis slope.
Foundation stabilization of (II) receiving end
The range requirement of the reinforcing body is as follows: the reinforcement length is greater than the length of a main engine of the shield machine, after a cutter head of the machine body breaks a tunnel portal, a shield tail is in a reinforcement area, it is guaranteed that a leakage channel is not formed between an unreinforced area behind the shield tail and the tunnel portal, the reinforcement width is 3 meters (including the position of a standby precipitation well) of the outer edge of the diameter of the shield machine, and end reinforcement is completed 1 month before the shield machine reaches the reinforcement area, so that the cement reinforcement strength of the reinforcement area is guaranteed.
Adopting a closed plain wall, a triaxial mixing pile and a high-pressure jet grouting pile to perform seam filling and reinforcing; in order to ensure the safety of the broken tunnel, a row of plain concrete walls are additionally arranged at the opening, the depth of each wall is 5m from the bottom plate of the channel structure to the position below the bottom of the tunnel, and the width of each wall is 3m of the two sides of the tunnel.
3-4 drainage dewatering wells are arranged in the range of the reinforced area, and once a problem occurs in the receiving process, the drainage dewatering wells are started emergently to ensure safety.
(III) door breaking
And the continuous wall breaking work in the portal area can be carried out under the condition that the reinforcing body meets the design strength requirement and ensures that the shield machine is provided with a receiving inlet.
Before the end wall enclosure structure is drilled, a horizontal probe hole is firstly constructed, the end soil body reinforcing effect is tested, part of probe holes are required to be only dripped, no silt exists in water, and the total amount of water seepage in 24 hours is not more than 5L. The number of the horizontal probing holes is not less than 5, the horizontal probing holes are distributed at the upper and lower, left and right quadrant points and the central point of the reserved hole of the main body structure, and the length of each horizontal probing hole is not less than 3 m.
In order to reduce the influence of tunnel portal breakage on soil in the range of the tunnel ring as much as possible and ensure that the shield machine enters the tunnel safely, the tunnel portal continuous wall is chiseled twice. Breaking the outer concrete for 10cm for the first time, stripping the reinforcing steel bars on the inner layer of the underground continuous wall, and continuously breaking for 70 cm; and the second breaking arrangement is carried out when the cutter head of the shield machine tunnels to the plain wall of the tunnel portal, the remaining 20cm tunnel portal is broken, and after the breaking is finished, concrete residues are cleaned up and lifted out of the foundation pit. And after the portal is broken, immediately backfilling sandy soil and recharging water.
Closely observing the displacement change of the wall body in the portal range in the breaking process, and immediately stopping the breaking of the portal continuous wall once the wall body or the soil body in the portal ring is greatly deformed or has a water leakage phenomenon, and grouting and plugging the water leakage position to prevent water and soil loss; if no abnormal condition is found, the destruction can be continued. The breaking can not be completed at one time, and delamination is needed.
The portal is a large risk point, tracking monitoring and measurement are carried out for the portal, and measurement distribution points comprise a receiving end settlement observation point, a portal removal horizontal observation point and an inclinometry observation point. The settlement observation points are 9 points arranged on the tunnel door purlin, 16 points are arranged on the continuous wall, 4 points are respectively arranged on two sides of the central line of the reinforced section, the transverse distance is 4m, and the settlement observation points can be properly adjusted according to the terrain. The horizontal observation point adopts that a convergence instrument is arranged on a continuous wall surface of the portal to measure the horizontal displacement of the wall body, 5 lifting lugs are welded at the positions of the center line at the top of the embedded steel ring and the horizontal distances of 3m and 6m at two sides, and the displacement condition of the wall body is determined by measuring the distance change between the lifting wire and the wall surface by adopting a lifting wire and a steel ruler during measurement. The inclination measurement observation points are measured by utilizing the existing side inclination points of the receiving well end of the Huangpu road station during construction, and are monitored by adopting an inclinometer.
Filling sand and soil in the receiving well, irrigating water and cleaning after receiving
In order to stabilize the ground layer when the shield receives the ground layer and reduce mud gushing and sand gushing and ground surface settlement risks between the large-diameter shield and the portal ring, after the portal concrete is broken, the vertical shaft is backfilled with sandy soil (in order to facilitate pumping and drainage by a slurry discharge system of the shield machine, the sandy soil is more convenient to clean, sundries such as concrete lumps, reinforcing steel bars, templates and the like are prevented from being mixed in the sandy soil as much as possible, otherwise, the slurry outlet pump and the pipeline of the shield machine are blocked), the lower part of the shield machine passes through the portal ring and is supported by a soil body, the backfilling clay thickness is 3m below the top of the shield machine, and the backfilled sandy soil is leveled and compacted by adopting. In order to ensure the balance of internal and external pressure during receiving, clear water is filled into the working well after clay is backfilled, and meanwhile, the backfilled sandy soil in the working well is tightly filled with water, and the filling depth is that the top of the tunnel door is flush. Can continue to carry out muddy water circulation and synchronous slip casting forward the propulsion in-process at the shield entering working well, ensure that nearly portal segment section of jurisdiction ring can slip casting closely, control section of jurisdiction is out of shape and is subsided.
After the shield receiving is finished, the filled sandy soil is transported to a mud-water separation device through a pipeline by using a slurry circulating system of the shield machine to carry out slag-soil separation and outward transportation. And washing the sand in the receiving well by using a high-pressure water gun, and finally, manually cleaning the residual sand which does not fall dead corners.
(IV) go out hole ring connection and portal steel plate welding seal
After the shield machine goes out the tunnel portal, the shield machine reduces the counterforce for the duct piece, and 5 to 10 ring connections of going out the tunnel ring are similar to the ring that advances the tunnel ring for avoiding the phenomenon such as the assembling of duct piece is not tight, and normal hoop is vertical bolted connection back, adopts the inboard vertical and hoop reservation steel sheet welded connection of duct piece to strengthen.
The shield machine is driven into a receiving well, after the last steel wire brush of the shield tail is completely separated from a tunnel door, the last segment is arranged at the sealing ring, a steel plate with the width of 500mm is pre-embedded on one side of the outer side surface of the last segment, and the thickness of the pre-embedded steel plate is 10 mm. After the shield tail of the shield tunneling machine completely penetrates through the sealing plate, welding the edge of the circular ring plate with the embedded steel plate on the outer side of the final ring segment by using a sealing steel plate with the thickness of 20mm to form sealing so as to ensure the sealing effect of the tunnel outlet ring segment and ensure the safety and reliability of a permanent structure. The height of the secondary sealing weld joint is 10mm, and the weld joint is continuous and does not leak. The steel plate for sealing is 50mm higher than the circular ring plate, and the specific situation can be adjusted according to the gap between the circular ring plate and the final ring segment.
And (3) completing welding of the tunnel portal sealing steel plate, reserving a secondary grouting hole through the duct piece to perform secondary grouting after the wall of the duct piece goes out of the tunnel, ensuring that the wall is full and compact, and finishing the shield receiving process flow.
EXAMPLE 2 engineering example
Overview of the engineering
The Wuhan subway No. 8 line first-stage civil engineering three-standard comprises a station section and a section, wherein the section is a cross-river tunnel, a single-hole double-line design is adopted, the outer diameter of the tunnel is 12.1 meters, the diameter of a shield machine is 12.51 meters, a shield receiving site is located at the intersection of a Lu ditch bridge road and a Jinghan road and is only 13 meters closest to a subway first-line viaduct, the distance of a contact channel at the top of a shield receiving end is only 2.8 meters, the shield receiving end penetrates through a geological fine sand stratum, and underground water is communicated with Yangtze river water. The shield is successfully received by the engineering method of covering soil and irrigating water and reaching the shield in a dark way.
Construction conditions
The Wuhan subway No. 8 line cross-river tunnel shield reaches a receiving and reinforcing area in 2017 in 8 and 3 months, is communicated in 2017 in 8 and 9 months, and finishes in-place shutdown and sealing steel plate welding of the shield machine in 8 and 14 months.
Evaluation of engineering results
The construction method aims at the quality defects and safety risks such as tunnel portal leakage after receiving, duct piece assembling infirm, slab staggering cracking and the like which are the safety problems easily occurring in shield receiving, determines the construction technology and process for shield arrival receiving, and has the advantages that the tunnel outlet ring duct piece assembling precision is high, deformation is avoided, and the tunnel portal ring position does not have leakage. Has good popularization value in the same engineering construction.
Claims (1)
1. The earth covering balance comprehensive receiving construction method for the large-diameter slurry shield under the working condition of the highly permeable stratum in the complex environment is characterized by comprising the following steps of:
construction of (I) well inner closing wall and receiving base
1) And (3) construction of an inner closed wall:
the method comprises the following steps that a closed well structure is constructed during construction of a receiving well structure, a closed structure is formed according to the site occupation range of shield equipment in the receiving well, three end head main body structures of the receiving well are used as three-side blocking walls, one blocking wall in front of shield tunneling is a temporary blocking wall, a steel-concrete structure is adopted, C25 concrete is poured, the thickness of the blocking wall is 25-30CM, and the receiving well structure is dismantled after cleaning in the receiving well is completed;
2) receiving base construction
The shield receiving adopts a scheme that earth covering and water filling are carried out to reach the receiving in a dark mode, a receiving base adopts an M10 cement mortar structure, mortar filling is carried out on a receiving well in advance, the height of the surface of the mortar is enabled to be 1/5 of a shield cutter head, and after the shield exits from a hole, the mortar base is cut by utilizing the tunneling function of the shield machine to become a bearing base which is 100% identical with the shield machine; a channel is reserved at the joint of the cutter head, the shield body and the shield tail and at the outer edge of the shield tail respectively, so that the shield machine is convenient to disassemble;
the receiving base is divided into two rows and six blocks, and reserved cutting grooves are respectively designed among the six blocks of the base according to the boundary line of the shield body and the shield tail and the respective blocks; 1/5 that the elevation of the top of the base is higher than the excavation diameter of the cutter head of the shield tunneling machine than the bottom of the cutter head is received, and the counterforce of the shield tunneling machine in the forward process is provided;
the width of a vertical reserved groove of the shield body and the shield tail is 1.1m, and the width of a reserved groove of a shield tail and shield body disassembly block is 1 m; a foundation with the height of 50cm is filled at the bottom of the base, and six bases are connected; the upper surface of the base is an uphill slope of 2.7 percent, and the uphill slope is consistent with the gradient of the axis of the tunnel;
foundation stabilization of (II) receiving end
The range requirement of the reinforcing body is as follows: the reinforcement length is greater than the length of a main engine of the shield tunneling machine, and the reinforcement width is 3 meters of the outer edge of the diameter of the shield tunneling machine respectively, wherein the reinforcement width comprises the position of a standby dewatering well; end reinforcement is completed 1 month before the shield machine reaches a reinforcement area;
adopting a closed plain wall, a triaxial mixing pile and a high-pressure jet grouting pile to perform seam filling and reinforcing; a row of plain concrete walls are additionally arranged at the opening, the depth of each wall is 5m from the bottom plate of the channel structure to the position below the tunnel bottom, and the width of each wall is 3m of the range of each side of the tunnel;
3-4 drainage dewatering wells are arranged in the range of the reinforced area;
(III) door breaking
Under the condition that the reinforcing body meets the design strength requirement and ensures that the shield machine has the capability of receiving the inlet hole, the continuous wall breaking work of the portal area can be carried out;
before the end wall enclosure structure is drilled, a horizontal probe hole is firstly constructed, the soil body reinforcing effect of an end head is tested, the probe hole is required to be only dripped, no silt exists in water, and the total amount of water seepage in 24 hours is not more than 5L; the number of the horizontal detecting holes is not less than 5, the horizontal detecting holes are distributed at the upper, lower, left and right quadrant points and the central point of the reserved hole of the main body structure, and the length of the horizontal detecting holes is not less than 3 m;
chiseling the tunnel portal continuous wall twice; breaking the outer concrete for 10cm for the first time, stripping the reinforcing steel bars on the inner layer of the underground continuous wall, and continuously breaking for 70 cm; the second breaking is carried out when the cutter head of the shield machine tunnels to the plain wall of the tunnel portal, the remaining 20cm tunnel portal is broken, concrete residues are cleaned after the breaking is finished, and the foundation pit is hoisted; after the portal is broken, immediately backfilling sandy soil and recharging water;
closely observing the displacement change of the wall body in the portal range in the breaking process, and immediately stopping the breaking of the portal continuous wall once the wall body or the soil body in the portal ring is greatly deformed or has a water leakage phenomenon, and grouting and plugging the water leakage position to prevent water and soil loss; if no abnormal condition is found, the damage can be continuously removed; the breaking can not be completed at one time, and the delamination is needed;
tracking, monitoring and measuring, wherein the measuring and distributing points comprise a receiving end head settlement observation point, a portal breaking horizontal observation point and an inclinometry observation point; 9 points are arranged on the hole door purlin at the settlement observation point, 16 points are arranged on the continuous wall, 4 points are respectively arranged on two sides of the central line of the reinforced section at a transverse interval of 4m, the horizontal observation point adopts the mode that a convergence instrument is arranged on the continuous wall surface of the hole door to measure the horizontal displacement of the wall, 5 lifting lugs are welded at the positions of the central line at the top of the embedded steel ring and the horizontal distances of 3m and 6m at two sides, and the distance change between the lifting wire and the wall surface is measured by adopting the lifting wire and the steel ruler during measurement to determine the displacement condition of the wall; measuring an inclination measurement observation point by using an existing side inclination point during construction of the receiving well end of the Huangpu road station, and monitoring by using an inclinometer;
filling sand and soil in the receiving well, irrigating water, and cleaning after receiving;
after the tunnel portal concrete is broken, backfilling sandy soil into the vertical shaft, enabling the lower part of the shield tunneling machine to be supported by soil after passing through a tunnel portal ring, wherein the thickness of the backfilled clay is 3m below the top of the shield tunneling machine, and the backfilled sandy soil is layered, leveled and compacted by adopting excavator equipment; in order to ensure that the internal pressure and the external pressure are balanced during receiving, clear water is filled into the working well after clay is backfilled, and meanwhile, sand soil backfilled in the working well is tightly filled with water, and the filling depth is that the top of a tunnel door is flush; slurry circulation and synchronous grouting are continuously carried out in the forward propelling process of the shield entering the working well, so that the close-hole portal segment pipe piece ring can be tightly grouted, and the deformation and the settlement of the pipe piece are controlled;
after the shield receiving is finished, transporting the piled sandy soil to a mud-water separation device through a pipeline by using a slurry circulating system of the shield machine to carry out slag-soil separation and outward transportation; washing the sand in the receiving well by using a high-pressure water gun, and finally, manually cleaning the residual sand which does not fall dead corners;
(IV) go out hole ring connection and portal steel plate welding seal
After the shield machine leaves the tunnel door, the counterforce of the shield machine on the duct piece is reduced, 5-10 ring exit rings are connected, similar to the entry ring, and after the normal ring is connected with the longitudinal bolt, the welding connection and the reinforcement are carried out by adopting the longitudinal and circumferential reserved steel plates at the inner side of the duct piece;
the shield tunneling machine is driven into a receiving well, after the last steel wire brush of the shield tail is completely removed from a tunnel door, the last ring segment is arranged at the sealing ring, a steel plate with the width of 500mm is pre-embedded on one side of the outer side surface of the last ring segment, and the thickness of the pre-embedded steel plate is 10 mm; after the shield tail of the shield tunneling machine completely passes through the sealing plate, welding the edge of the circular ring plate with the embedded steel plate on the outer side of the tail ring segment by using a sealing steel plate with the thickness of 20mm to form sealing so as to ensure the sealing effect of the tunnel outlet ring segment, wherein the height of a secondary sealing welding line is 10mm, and the welding line is continuous and does not leak; the steel plate for sealing is 50mm higher than the circular plate;
and (3) completing welding of the tunnel portal sealing steel plate, reserving a secondary grouting hole through the duct piece to perform secondary grouting after the wall of the duct piece goes out of the tunnel, ensuring that the wall is full and compact, and finishing the shield receiving process flow.
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| CN109356596B (en) * | 2018-10-30 | 2020-05-12 | 中建交通建设集团有限公司 | Method for launching and receiving shield tunneling machine by utilizing recyclable underground continuous wall and steel sleeve |
| CN109630127B (en) * | 2018-11-22 | 2020-05-05 | 中铁隧道集团二处有限公司 | Construction method of ultra-deep shield vertical shaft for water-rich weak stratum |
| CN109403988A (en) * | 2018-12-27 | 2019-03-01 | 中铁隧道集团三处有限公司 | A kind of multiple received construction of special formation arrival |
| CN110145319B (en) * | 2019-05-31 | 2020-02-21 | 粤水电轨道交通建设有限公司 | Shield receiving method for quickly recharging mud into steel sleeve by using circulation pressure maintaining system |
| CN110905536A (en) * | 2019-12-12 | 2020-03-24 | 中铁十二局集团有限公司 | Construction method for receiving complex stratum earth pressure shield in underground excavation tunnel |
| CN113931642B (en) * | 2021-11-12 | 2023-06-27 | 中国水利水电第四工程局有限公司 | Temporary treatment method for water and sand leakage of tail of earth pressure balance shield machine |
| CN114370286A (en) * | 2021-12-08 | 2022-04-19 | 上海市基础工程集团有限公司 | Shield tunneling machine safe hole entering method for open caisson structure |
| CN114233307A (en) * | 2021-12-20 | 2022-03-25 | 中铁十四局集团大盾构工程有限公司 | Major diameter slurry shield does receiving arrangement |
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