CN112502717B - Construction method for excavating connecting channels between shield sections of water-rich sand layer - Google Patents

Construction method for excavating connecting channels between shield sections of water-rich sand layer Download PDF

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Publication number
CN112502717B
CN112502717B CN202011372992.2A CN202011372992A CN112502717B CN 112502717 B CN112502717 B CN 112502717B CN 202011372992 A CN202011372992 A CN 202011372992A CN 112502717 B CN112502717 B CN 112502717B
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tunnel
grouting
stratum
shield
section
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CN112502717A (en
Inventor
宁振国
魏辉
李朝成
梁缄鑫
曹佳斌
张宝平
申晓莉
刘晓宁
赵晓娟
李博
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Fifth Engineering Co Ltd of China Railway 20th Bureau Group Co Ltd
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Fifth Engineering Co Ltd of China Railway 20th Bureau Group Co Ltd
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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D9/00Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/003Linings or provisions thereon, specially adapted for traffic tunnels, e.g. with built-in cleaning devices
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/04Lining with building materials
    • E21D11/08Lining with building materials with preformed concrete slabs
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/04Lining with building materials
    • E21D11/10Lining 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
    • E21D11/105Transport 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
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D9/00Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
    • E21D9/001Improving soil or rock, e.g. by freezing; Injections
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/20Hydro energy

Abstract

The invention discloses a construction method for excavating a connecting channel between shield sections of a water-rich sand layer, which comprises the following steps: 1. erecting a temporary support structure of the duct piece; 2. pre-reinforcing stratum; 3. constructing a vertical transportation channel; 4. cutting and dismantling the duct piece; 5. constructing a tunnel entrance section; 6. and excavating and constructing the front tunnel section. The method has the advantages of simple steps, reasonable design, simple and convenient construction, safe and reliable construction process, the temporary support structure of the duct piece is firstly erected at the joint of the shield tunnel and the connecting passage before the stratum is pre-reinforced, then the stratum pre-reinforcement is carried out by combining the grouting reinforcement of the stratum advance small guide pipe at the end part of the passage with the integral grouting reinforcement of the stratum sleeve valve pipe where the passage is positioned, the earthwork outward transportation and the material hoisting are carried out by constructing the vertical transportation passage after the stratum pre-reinforcement, the construction process of excavating the connecting passage of the shield section of the water-rich sand layer can be simply, conveniently and rapidly completed, and the construction process is safe and reliable.

Description

Construction method for excavating connecting channels between shield sections of water-rich sand layer
Technical Field
The invention belongs to the technical field of shield interval connection channel construction, and particularly relates to a water-rich sand layer shield interval connection channel excavation construction method.
Background
In subway tunnel construction engineering, a communication channel is required to be arranged in a shield zone for emergency evacuation and drainage. The construction risk of the connecting channel is high, and the connecting channel is always a part with frequent accidents in subway construction. The communication channel accident is liable to cause the destruction of ground cable and the destruction of buildings, even endangering the whole subway line. Therefore, the connection passage construction plays a very important role in the shield construction. However, in the water-rich sand layer area, the problems of loose sand structure, large void ratio, poor stratum self-stability and large excavation risk, how to ensure the construction quality and the safety of the communication channel, become the urgent challenges to be overcome. At present, the conventional construction scheme adopted by underground excavation of the connecting channel in the subway section in the water-rich sand layer is long in period, has serious influence on construction of other working procedures, and is most important in that the construction safety risk is large, and safety accidents are easy to occur. In the aspect of stratum reinforcement, jet grouting piles are mainly adopted at present, the influence on the ground is large in the jet grouting pile reinforcement process, and when the connection channel is large in burial depth, the construction difficulty is large, the input cost is high, and the construction period cannot be effectively ensured.
In the conventional construction of the connecting channel, in the aspect of excavation, when a weak area of a top support at the joint of the tunnel and the connecting channel is excavated (namely, when the tunnel enters a hole), the part is excavated in two stages, the first stage is excavated obliquely upwards from the elevation of a tunnel door to the design vault of the connecting channel in a gradient manner to form a transition section, and the second stage is excavated reversely to the design requirement after the primary support is penetrated, but the method still has great collapse risk under the condition that the stratum is a water-rich sand layer, and because the sand structure is loose, the void ratio is large, the stratum self stability is poor, and the excavation collapse risk of the weak area of the advanced support at the top of the joint of the tunnel and the connecting channel is larger, so that a safer construction method for excavating the connecting channel of the water-rich sand layer shield section is needed at present to reduce accidents.
Disclosure of Invention
The invention aims to solve the technical problems in the prior art and provides a construction method for excavating a water-rich sand layer shield section connecting channel, which has the advantages of simple steps, reasonable design, simple and convenient construction, safe and reliable construction process, firstly erecting a segment temporary supporting structure at the joint of a shield tunnel and the connecting channel before stratum pre-reinforcement, then carrying out stratum pre-reinforcement by combining stratum advanced small conduit grouting reinforcement at the end part of the channel with integral grouting reinforcement of a stratum sleeve valve pipe where the channel is positioned, carrying out earth outside transportation and material hoisting by constructing a vertical transportation channel after stratum pre-reinforcement, and being capable of simply, conveniently and rapidly completing the construction process of excavating the connecting channel of the water-rich sand layer shield section, and being safe and reliable in construction process.
In order to solve the technical problems, the invention adopts the following technical scheme: a water-rich sand layer shield interval connection channel excavation construction method is characterized by comprising the following steps of: the constructed communication channel is a subsurface tunnel which is connected between two shield tunnels and is positioned in the water-rich sand layer, and the constructed communication channel is divided into a tunnel portal section and a front tunnel section positioned at the front side of the tunnel portal section; when the constructed communication channel is excavated, the method comprises the following steps:
step one, erecting a temporary support structure of the duct piece: respectively erecting a group of duct piece temporary supporting structures in the two shield tunnels, and respectively enabling the two groups of duct piece temporary supporting structures to be positioned at the front side and the rear side of a constructed communication channel;
the segment temporary supporting structure is supported on the inner side of a shield segment ring in the shield tunnel;
step two, stratum pre-reinforcement: pre-reinforcing stratum where the constructed connecting channel is located, wherein the process is as follows:
step 201, grouting and reinforcing stratum at the end part of the channel: carrying out advanced small-conduit grouting reinforcement on stratum at the front end and the rear end of a constructed connecting channel through two shield tunnels respectively, and forming channel end stratum reinforcement structures at the outer sides of the two shield tunnels;
Step 202, grouting and reinforcing the whole channel stratum: respectively carrying out sleeve valve pipe grouting reinforcement on the whole stratum where the constructed communication channel is located through the two shield tunnels to obtain a sleeve valve pipe grouting reinforcement structure;
the two tunnel end stratum reinforcing structures constructed in the step 201 are slurry stopping structures used for sleeve valve pipe grouting reinforcement in the step, and the sleeve valve pipe grouting reinforcing structures and the two tunnel end stratum reinforcing structures are fixedly connected into a whole;
thirdly, constructing a vertical transportation channel: constructing a vertical transportation channel at the rear end of the front tunnel section from the ground to the bottom, wherein the vertical transportation channel is communicated with the inside of the constructed communication channel;
step four, segment cutting and dismantling: cutting and dismantling a shield segment ring at the hole entering position of the constructed connecting channel in the shield tunnel to obtain a portal of the constructed connecting channel;
fifthly, entering the tunnel construction at the tunnel portal section: excavating the opening section of the constructed communication channel from back to front through the portal in the fourth step; after excavation is completed, the hole section is communicated with the vertical transportation channel in the third step;
step six, front tunnel section excavation construction: and (3) excavating the front tunnel section of the constructed connecting channel from back to front by utilizing the vertical transportation channel in the step (III).
The construction method for excavating the connecting channel between the water-rich sand layer shield sections is characterized by comprising the following steps of: the two shield tunnels are connected with the constructed connecting channel in a tunnel connection area, tunnel sections where the tunnel connection areas are located in each shield tunnel are tunnel sections to be reinforced, and the two groups of segment temporary supporting structures are respectively arranged in the tunnel sections to be reinforced of the two shield tunnels;
each group of segment temporary support structures comprises 2N segment temporary support structures for temporarily supporting shield segment rings in the tunnel segment to be reinforced one by one, the structures of the 2N segment temporary support structures in each group of segment temporary support structures are the same and are distributed from back to front along the longitudinal extension direction of the distributed shield tunnel, each segment temporary support structure is supported in one shield segment ring, and each segment temporary support structure is positioned on one tunnel cross section of the shield tunnel; wherein N is a positive integer and N is more than or equal to 2;
each group of duct piece temporary supporting structures is divided into two duct piece temporary supporting groups which are respectively positioned at two sides of the tunnel junction area, and each duct piece temporary supporting group comprises N duct piece temporary supporting structures.
The construction method for excavating the connecting channel between the water-rich sand layer shield sections is characterized by comprising the following steps of: in the fourth step, the portal is positioned at the rear side of the constructed connecting channel, the constructed connecting channel is divided into the portal section and a front tunnel section positioned at the front side of the portal section, the portal section is excavated twice from front to back, and the front tunnel section is excavated and formed from back to front; step five, when the tunnel entrance section is subjected to tunnel entering construction, the tunnel entrance section is excavated for the first time from back to front, and an excavation-shaped tunnel entrance transition section is obtained; the cross section of the tunnel portal transition section is smaller than that of the front tunnel section, and the cross section of the tunnel portal transition section is gradually increased from back to front;
in the process of entering a tunnel from a tunnel portal section, a plurality of rows of grouting pipes are pre-buried in the arch part of the tunnel portal transition section from back to front synchronously, the plurality of rows of grouting pipes are distributed from back to front, each row of grouting pipes comprises a plurality of grouting pipes distributed along the arch part excavation contour line of the tunnel portal transition section, and a plurality of grouting pipes in each row of grouting pipes are distributed on the same cross section of a constructed communication channel; each grouting pipe gradually inclines upwards from back to front;
And fifthly, in the process of excavating from back to front, the excavation-molded opening transition section is subjected to primary support synchronously from back to front, and a temporary primary support structure of the opening transition section is obtained.
The construction method for excavating the connecting channel between the water-rich sand layer shield sections is characterized by comprising the following steps of: in the sixth step, after the front tunnel section is excavated, advanced support is carried out on the arch stratum of the tunnel portal transition section through a plurality of rows of grouting pipes; then, breaking the temporary primary support structure in the opening transition section from front to back;
in the process of breaking the temporary primary support structure from front to back, carrying out secondary excavation on the hole section from front to back to obtain the excavation-shaped hole section; and in the process of carrying out secondary excavation on the hole section from front to back, carrying out primary support on the hole section formed by excavation synchronously from back to front.
The construction method for excavating the connecting channel between the water-rich sand layer shield sections is characterized by comprising the following steps of: in the third step, the vertical transportation channels are distributed vertically;
in the third step, when the vertical transportation channel is constructed, drilling is firstly carried out from top to bottom by adopting drilling equipment, and a steel casing is arranged in the formed drilling; the upper end of the steel protection cylinder extends out of the ground and is fixedly supported on the ground, and the bottom end of the steel protection cylinder is positioned below the vault of the front tunnel section.
The construction method for excavating the connecting channel between the water-rich sand layer shield sections is characterized by comprising the following steps of: in the step 201, when grouting reinforcement is carried out on stratum at the end part of the channel, a group of advance small guide pipes are respectively arranged on stratum at the front end and the rear end of the constructed communication channel through two shield tunnels, and the two groups of advance small guide pipes are symmetrically arranged; grouting and reinforcing stratum at the front end and the rear end of the constructed communication channel respectively through two groups of the advance small guide pipes;
each group of the leading small guide pipes comprises a plurality of leading small guide pipes which are uniformly distributed on the same plane, and the leading small guide pipes in each group of the leading small guide pipes are distributed from left to right along the width direction of the constructed communication channel and are distributed in parallel; each small advance conduit is arranged along the longitudinal extending direction of the constructed communication channel, one end of each small advance conduit is a stratum driving end driven into the stratum, and the other end of each small advance conduit is a grouting end; each of the leading small conduits is gradually inclined upward from the grouting end toward the formation driving end.
The construction method for excavating the connecting channel between the water-rich sand layer shield sections is characterized by comprising the following steps of: after the integral grouting reinforcement of the passage stratum in the step 202 is completed, the strata at the front end and the rear end of the constructed communication passage are respectively subjected to supplementary grouting reinforcement through the advance small guide pipes arranged in the step 201 to obtain a stratum grouting reinforcement structure at the end part of the passage, and the stratum grouting reinforcement structure at the end part of the passage and the sleeve valve pipe grouting reinforcement structure in the step 202 are fastened and connected into a whole;
And when the supplementary grouting reinforcement is actually carried out, the two groups of the advanced small guide pipes are used for respectively carrying out supplementary grouting reinforcement on stratum at the front end and the rear end of the constructed communication channel.
The construction method for excavating the connecting channel between the water-rich sand layer shield sections is characterized by comprising the following steps of: the advance small guide pipe arranged in the step 201 is a grouting pipe which is driven into a stratum through a pipe piece lifting hole on a shield pipe piece ring in the shield tunnel.
The construction method for excavating the connecting channel between the water-rich sand layer shield sections is characterized by comprising the following steps of: before grouting reinforcement of sleeve valve pipes in step 202, respectively constructing front and rear sleeve valve pipe grouting structures through two shield tunnels, wherein the two sleeve valve pipe grouting structures are symmetrically distributed and are grouting reinforcement structures for integrally reinforcing a stratum to be reinforced; each sleeve valve pipe grouting structure comprises a plurality of sleeve valve pipes which are driven into the ground to be reinforced from the same shield tunnel, and the sleeve valve pipes in each sleeve valve pipe grouting structure are radially distributed; the stratum to be reinforced is a stratum within the range of L meters outside the excavation contour line of the constructed communication channel, wherein the value range of L is 2.5-3.5;
each sleeve valve tube in one sleeve valve tube grouting structure is intersected with at least one sleeve valve tube in the other sleeve valve tube grouting structure.
The construction method for excavating the connecting channel between the water-rich sand layer shield sections is characterized by comprising the following steps of: the stratum to be reinforced is divided into a heavy overlaying and reinforcing area, an outer grouting weak area positioned at the outer side of the overlaying and reinforcing area and two end grouting weak areas positioned at the front side and the rear side of the overlaying and reinforcing area respectively, and the overlaying and reinforcing area is an area where grouting areas of the two sleeve valve pipe grouting structures are overlapped;
the two end grouting weak areas are respectively positioned above the front end and the rear end of the overlapped reinforcing area, and the advance small guide pipe arranged in the step 201 is positioned in the end grouting weak area; the two end grouting weak areas are all advanced small conduit grouting reinforcing areas which are reinforced by adopting advanced small conduits, and the overlapping reinforcing areas and the two end grouting weak areas form a core reinforcing area;
and the stratum where the constructed connecting channel body is positioned in the core reinforcing area.
Compared with the prior art, the invention has the following advantages:
1. the construction method has the advantages of simple steps, reasonable design, simple construction and low input cost.
2. The adopted advanced small conduit grouting reinforcement method for the end stratum has the advantages of simple construction, easy control of grouting process and good reinforcement effect, the adopted advanced small conduit grouting reinforcement for the end stratum is simple and convenient to lay and has good reinforcement effect, a stable-structure grouting stop ring is formed before the whole reinforcement of the stratum of the connecting channel, the stratum at the end of the connecting channel can be effectively reinforced, and meanwhile, the grouting reinforcement of the end stratum and the grouting reinforcement of the sleeve valve tube are mutually complemented, so that the final reinforcement effect of the stratum of the connecting channel can be effectively enhanced; moreover, the shield tunnel can be effectively reinforced from the outside through end stratum grouting reinforcement, and the reinforcement quality and the connection effect of the joint of the shield tunnel and the connecting channel can be ensured; in addition, through tip stratum slip casting reinforcement can be with connection passageway stratum reinforced structure and both ends shield tunnel fastening connection as an organic whole, further ensure shield tunnel and connection passageway's whole reinforcement effect to can be with shield tunnel's whole stability. According to the invention, the stratum reinforcing structures at the end parts of the channels are arranged to symmetrically reinforce stratum at the front and rear ends of the constructed connecting channel, and two symmetrical slurry stopping rings are formed by the stratum reinforcing structures at the end parts of the two channels, so that slurry backflow in the whole grouting reinforcing grouting process of the channel stratum can be prevented, underground water flows at the front and rear ends of the constructed connecting channel can be effectively cut off, the structural stability of the joint between the constructed connecting channel and two shield tunnels is ensured, and the construction safety is ensured.
3. The sleeve valve pipe grouting reinforcement structure is simple and convenient to construct, the grouting process is easy to control, the reinforcement effect is good, the sleeve valve pipe grouting reinforcement structure formed by construction integrally and effectively reinforces the stratum where the constructed communication channel is located, the radial grouting reinforcement mode can fulfill the aim of reinforcing the stratum where the constructed communication channel is located in a full range, and the integral reinforcement effect is very good; the arrangement space of the advanced small guide pipes in the stratum at the two ends of the constructed communication channel is smaller, so that grouting density and grouting reinforcement effect in the stratum at the two ends of the constructed communication channel can be effectively ensured; while the leading small guide pipes in the middle part of the constructed communication channel are arranged at larger intervals, the leading small guide pipes on the front side and the rear side in the middle part of the constructed communication channel are mutually intersected, so that the grouting density and grouting reinforcement effect in the stratum can be ensured.
4. When the method is adopted for pre-reinforcing the stratum, grouting reinforcement of the small advanced guide pipe at the end part of the connecting channel is combined with integral reinforcement of the stratum sleeve valve pipe of the connecting channel, construction is simple and convenient, reinforcement quality is convenient to control, after grouting reinforcement is completed, the reinforced stratum and the shield segment in the constructed shield tunnel are fixedly connected into a whole, the structure stability of the shield tunnel can be effectively improved while the stratum reinforcement effect of the region where the constructed connecting channel is located is further improved, and the earth surface subsidence of the shield tunnel can be effectively limited or even avoided. The communication channel pre-reinforcement stratum in the water-rich sand layer area is divided into a plurality of reinforcement areas, and stratum pre-reinforcement construction is carried out on different reinforcement areas by adopting different reinforcement methods, so that the communication channel pre-reinforcement stratum is simply, conveniently, quickly and reliably reinforced, a foundation is laid for excavation of a subsequent communication channel, collapse risk during excavation of the communication channel is reduced, and construction safety is guaranteed.
5. The temporary support structure of the duct piece is reasonable in design, convenient to assemble and disassemble, good in reinforcing effect, small in occupied space and capable of meeting the requirement of track laying operation construction. The temporary support structure of the duct piece in the hole is combined with the stratum reinforcing structure at the end part of the passage outside the shield tunnel, and the inner side and the outer side of the joint part of the shield tunnel and the constructed connecting passage are provided with effective reinforcing supports, so that the duct piece deformation, cracking and damage caused by the prestress concentration caused by the duct piece opening at the door can be effectively prevented, the reinforcing support structure is reinforced outside the duct piece, and the inner side and the outer side reinforcing support structures are combined together, so that the reinforcing effect of the shield duct piece at the door of the connecting tunnel is better, and the construction is safer. When the prior connecting channel is constructed, the duct piece support adopts a door type support frame, and reserved personnel, small machines or shield storage battery cars pass through door openings, so that the follow-up track laying engineering construction can not be met.
6. The vertical transportation channel is simple in structure, reasonable in design, simple and convenient to construct and good in using effect, can accelerate the construction process of the connection channel, and can avoid risks brought by the construction process of the connection channel to track laying and rail car running in the shield tunnel, and the vertical transportation channel is formed at the position of 2m of a hole formed in the connection channel for carrying out earthwork outward and material hoisting.
7. The stratum pre-reinforcement method is reasonable in design, simple and convenient to construct and good in reinforcement effect, the advanced area to be reinforced of the stratum of the water-rich sand layer connecting channel is divided, the corresponding type grouting reinforcement method is adopted to effectively reinforce, the reinforced stratum and the shield segment of the constructed shield tunnel are fixedly connected into a whole, the structural stability of the shield tunnel can be effectively improved while the stratum reinforcement effect of the constructed connecting channel is further improved, the ground surface subsidence of the shield tunnel can be effectively limited or even avoided, a foundation is laid for the connecting channel excavation, the collapse risk of the connecting channel is reduced, and the construction safety is guaranteed. And erect the interim bearing structure of section of jurisdiction in shield tunnel and contact passageway junction earlier before stratum is strengthened in advance, effectively consolidate shield tunnel and contact passageway junction stratum in step when the stratum is strengthened in advance, ensure shield tunnel and contact passageway junction's steadiness to effectively reduce and avoid even rich water sand layer shield interval contact passageway to advance the cave construction risk.
In conclusion, the method has the advantages of simple steps, reasonable design, simple and convenient construction, safe and reliable construction process, the temporary support structure of the duct piece is firstly erected at the joint of the shield tunnel and the connecting passage before the stratum is pre-reinforced, then the stratum pre-reinforcement is carried out by combining the advanced grouting reinforcement of the stratum small guide pipe at the end part of the passage with the integral grouting reinforcement of the stratum sleeve valve pipe where the passage is positioned, the earthwork transportation and the material hoisting are carried out by constructing the vertical transportation passage after the stratum pre-reinforcement, the construction process of excavating the connecting passage in the shield section of the water-rich sand layer can be simply, conveniently and rapidly completed, and the construction process is safe and reliable. The invention adopts grouting reinforcement in the tunnel and the circular ring-shaped pipe piece support, thereby ensuring the safety of the formed tunnel pipe piece in the process of breaking the tunnel door and meeting the normal running of the track laying operation; meanwhile, in the excavation process, the construction task is safely and rapidly completed by adding temporary grid arches and vertical transportation measures.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
FIG. 1 is a block diagram of a construction method of the present invention.
Fig. 2 is a construction state diagram of the present invention when the pre-reinforcement of the stratum is performed.
FIG. 3 is a schematic diagram of the layout positions of the advance small catheter and the sleeve valve tube on the cross section of the shield tunnel.
FIG. 4 is a schematic view of the layout of the upper sleeve valve tube, the advance small conduit and the portal in the cross section of the communication channel of the present invention.
Fig. 5 is a schematic view showing a supporting state of the temporary supporting structure for duct pieces according to the present invention.
Fig. 6 is a schematic diagram of the excavation construction state of the communication channel of the present invention.
FIG. 7 is a schematic diagram of the cross-sectional layout position of the grouting pipe on the opening section of the connecting channel according to the present invention.
Reference numerals illustrate:
1-shield tunneling; 2-a communication channel; 3-a tunnel portal;
4-sleeve valve tube; 5-stratum to be reinforced; 6-overlapping the reinforced areas;
7-end grouting weak areas; 8-leading small catheter; 9-an outside grouting weak area;
10-a telescopic connection; 11-a hinge seat; 12-arc shaped steel support
13-supporting seats; 14-screw jack; 15-grouting pipe;
16-steel arches; 17-vertical transport channels; 18-steel casing.
Detailed Description
The construction method for excavating the connecting channel between the shield sections of the water-rich sand layer is shown in fig. 1, wherein the constructed connecting channel 2 is a subsurface tunnel which is connected between two shield tunnels 1 and the tunnel body of which is positioned in the water-rich sand layer, and the constructed connecting channel 2 is divided into a tunnel opening section and a front tunnel section positioned at the front side of the tunnel opening section; when the constructed communication channel 2 is excavated, the method comprises the following steps:
step one, erecting a temporary support structure of the duct piece: a group of segment temporary supporting structures are respectively erected in the two shield tunnels 1, and the two groups of segment temporary supporting structures are respectively positioned at the front side and the rear side of the constructed connecting channel 2, as shown in fig. 5 in detail;
the segment temporary supporting structure is supported on the inner side of a shield segment ring in the shield tunnel 1;
step two, stratum pre-reinforcement: referring to fig. 2, 3 and 4, the stratum where the communication channel 2 is constructed is pre-reinforced, and the process is as follows:
step 201, grouting and reinforcing stratum at the end part of the channel: carrying out advanced small-conduit grouting reinforcement on stratum at the front end and the rear end of a constructed connecting channel 2 through two shield tunnels 1 respectively, and forming channel end stratum reinforcement structures at the outer sides of the two shield tunnels 1;
Step 202, grouting and reinforcing the whole channel stratum: the sleeve valve pipe grouting reinforcement structure is obtained by respectively carrying out sleeve valve pipe grouting reinforcement on the whole stratum where the constructed communication channel 2 is located through the two shield tunnels 1;
the two tunnel end stratum reinforcing structures constructed in the step 201 are slurry stopping structures used for sleeve valve pipe grouting reinforcement in the step, and the sleeve valve pipe grouting reinforcing structures and the two tunnel end stratum reinforcing structures are fixedly connected into a whole;
thirdly, constructing a vertical transportation channel 17: constructing a vertical transportation channel 17 at the rear end of the front tunnel section from the ground to the bottom, wherein the vertical transportation channel 17 is communicated with the inside of the constructed communication channel 2, and the detail is shown in fig. 6;
step four, segment cutting and dismantling: cutting and dismantling a shield segment ring at the hole entering position of the constructed connecting channel 2 in the shield tunnel 1 to obtain a portal 3 of the constructed connecting channel 2;
fifthly, entering the tunnel construction at the tunnel portal section: excavating the opening section of the constructed communication channel 2 from back to front through the portal 3 in the fourth step; after the excavation is completed, the hole section is communicated with the vertical transportation channel 17 in the third step;
Step six, front tunnel section excavation construction: the front tunnel section of the constructed connecting channel 2 is excavated from the back to the front by means of the vertical transport channel 17 in step three.
In this embodiment, after the grouting reinforcement of the whole tunnel stratum in step 202 is completed, the front and rear end strata of the constructed communication tunnel 2 need to be respectively supplemented and grouting reinforced by the advance small guide pipes 8 arranged in step 201, so as to obtain a tunnel end stratum grouting reinforcement structure, and the tunnel end stratum grouting reinforcement structure and the sleeve valve pipe grouting reinforcement structure in step 202 are fastened and connected into a whole.
In this embodiment, in the third step, the vertical transportation channel 17 is vertically arranged;
in the third step, when the vertical transportation channel 17 is constructed, drilling is firstly carried out from top to bottom by adopting drilling equipment, and a steel casing 18 is arranged in the formed drilling; the upper end of the steel protection cylinder 18 extends out of the ground and is fixedly supported on the ground, and the bottom end of the steel protection cylinder 18 is positioned below the vault of the front tunnel section.
When the vertical transportation channel 17 is actually constructed, the designed elevation of the portal 3 at the rear end of the constructed communication channel 2 is obliquely upwards to the designed vault range of the constructed communication channel 2, the ending position of the gradual excavation transition section (namely the portal transition section or the portal transition section) is determined, the vertical transportation channel 17 which is downwards communicated to the inside of the constructed communication channel 2 from the ground is constructed at the corresponding position on the ground by adopting a rotary drilling pore-forming method, then the steel protection cylinder 18 is lowered in the vertical transportation channel 17, the bottom of the steel protection cylinder 18 extends below the initial supporting and erecting position of the vault of the constructed communication channel, the top of the steel protection cylinder 18 is higher than the ground, a gap exists between the steel protection cylinder 18 and the vertical transportation channel 17, the gap between the steel protection cylinder 18 and the vertical transportation channel 17 is tightly backfilled by adopting concrete, and then the steel protection cylinder 18 is fixed on the ground.
It should be noted that, since the transition section of the gradual excavation is required to be excavated reversely in the latter stage, the vertical transportation channel 17 cannot be disposed therein, and the earthwork excavated in order to satisfy the constructed connecting channel 2 can be transported out in time, so that the vertical transportation channel 17 is disposed at the position where the transition section of the gradual excavation ends. The vertical transportation channel 17 is constructed before the constructed communication channel 2 is excavated by earth and stone, so that the stability of the constructed communication channel 2 can be effectively ensured, and the possibility of collapse is reduced; the vertical conveying channel 17 is used for carrying out outward transport on the earthwork stones excavated by the constructed connecting channel 2, is also used for hoisting underground required materials, does not need to carry out the excavated earthwork stones through the shield tunnel 1, and effectively accelerates the construction speed. In this embodiment, the top of the steel casing 18 is fixed by using i-steel.
During actual construction, the aperture of the vertical transportation channel 17 is 1.2-1.5 m, the bottom of the steel pile casing 18 extends into 300-400 m below the arch crown primary support erection position of the constructed communication channel 2, the top of the steel pile casing 18 is 500-600 mm above the ground, and the wall thickness of the steel pile casing 18 is 10-15 mm.
The outer diameter of the steel pile casing 18 is 1 m-1.3 m, the outer diameter of the steel pile casing 18 is smaller than the aperture of the vertical transportation channel 17, the steel pile casing 18 is convenient to install and concrete is convenient to reinforce, and C15 concrete is used for concrete for filling gaps between the steel pile casing 18 and the vertical transportation channel 17. In this embodiment, the diameter of the steel casing 18 is phi 1m, the wall thickness of the steel casing is 10mm, the upper end of the steel casing 18 extends out of the ground by 500mm, and the bottom end of the steel casing is 300mm below the tunnel primary support structure of the front tunnel section.
In this embodiment, the areas where the two shield tunnels 1 are connected with the constructed connecting channel 2 are tunnel connection areas, the tunnel sections where the tunnel connection areas are located in each shield tunnel 1 are tunnel sections to be reinforced, and the two groups of segment temporary support structures are respectively arranged in the tunnel sections to be reinforced of the two shield tunnels 1;
each group of segment temporary support structures comprises 2N segment temporary support structures for temporarily supporting shield segment rings in the tunnel segment to be reinforced one by one, the structures of the 2N segment temporary support structures in each group of segment temporary support structures are the same and are distributed from back to front along the longitudinal extension direction of the distributed shield tunnel 1, each segment temporary support structure is supported in one shield segment ring, and each segment temporary support structure is positioned on one tunnel cross section of the shield tunnel 1; wherein N is a positive integer and N is more than or equal to 2;
each group of duct piece temporary supporting structures is divided into two duct piece temporary supporting groups which are respectively positioned at two sides of the tunnel junction area, and each duct piece temporary supporting group comprises N duct piece temporary supporting structures.
In this embodiment, each segment temporary supporting structure is supported at the middle part of the inner side of one shield segment ring. Thus, the spacing between two adjacent segment temporary support structures in each segment temporary support group is the same as the spacing between two adjacent shield segment rings in the shield tunnel 1.
In order to ensure the supporting effect, the segment temporary supporting structure is a circular supporting structure for carrying out full-section support on the shield segment ring.
In this embodiment, as shown in fig. 5, the annular supporting structure includes a plurality of circular arc-shaped supporting frames arranged on the same vertical surface along the circumferential direction, and a force application mechanism for applying prestress is disposed between two adjacent circular arc-shaped supporting frames, and a plurality of force application mechanisms in the annular supporting structure are arranged along the circumferential direction; the force application mechanism is a screw jack 14, each circular arc-shaped support frame is formed by splicing a plurality of circular arc-shaped steel brackets 12 distributed along the circumferential direction, and two adjacent circular arc-shaped steel brackets 12 in each circular arc-shaped support frame are connected in a hinged manner; a support 13 is arranged between each arc-shaped steel bracket 12 and the supported shield segment ring.
For the convenience of connection, two adjacent arc-shaped steel brackets 12 in each arc-shaped supporting frame are connected through a hinging seat 11. And a telescopic connecting piece 10 is connected between two adjacent circular arc-shaped supporting frames in the circular ring-shaped supporting structure, and the telescopic connecting piece 10 is an arc-shaped connecting piece. In this embodiment, the arc-shaped steel bracket 12 is formed by bending i-steel, so that the processing effect is good and the supporting effect is better.
To ensure the supporting force, in this embodiment, each of the force applying mechanisms includes a plurality of screw jacks 14. In actual construction, the number of screw jacks 14 included in each of the force applying mechanisms may be adjusted accordingly, as desired.
In this embodiment, n=4. Therefore, four-ring shield segments on the front side and the rear side of the portal 3 of the constructed connecting channel 2 are respectively and temporarily supported in each shield tunnel 1, and the temporary support structure of the segments adopts a circular support structure, so that the track laying operation and the track car passing can be met, and the influence caused by cross construction is avoided.
In the actual construction process, the temporary support structure of the duct piece is combined with the stratum reinforcing structure at the end part of the channel outside the shield tunnel 1, and effective reinforcing supports are formed at the inner side and the outer side of the joint of the shield tunnel 1 and the constructed connecting channel 2, so that the duct piece deformation, cracking and damage caused by prestress concentration due to duct piece opening at the portal can be effectively prevented, the reinforcing support structure is reinforced at the outer part of the duct piece, and the reinforcing support structures at the inner side and the outer side are combined together, so that the reinforcing effect of the shield duct piece at the portal of the connecting tunnel is better, and the construction is safer.
In this embodiment, a distance between two adjacent duct piece temporary support structures in front and back in each duct piece temporary support group is 1.5m, and 8 rings of duct piece temporary support structures are arranged in each shield tunnel 1.
In order to further ensure the reinforcing effect, a plurality of segment temporary supporting structures in each segment temporary supporting structure are all fastened and connected into a whole through a plurality of longitudinal connecting pieces distributed along the circumferential direction, and each segment temporary supporting structure is distributed along the longitudinal extending direction of the shield tunnel 1. In this embodiment, the longitudinal connecting piece is longitudinal connection shaped steel, the longitudinal connecting piece with the arc shaped steel support 12 fastening connection of section of jurisdiction temporary support structure just is connected through connecting bolt between the two, and the design dismouting is simple and convenient. For simple and reliable connection, the longitudinal connecting pieces are straight I-steel, and the circumferential distance between every two adjacent longitudinal connecting pieces is 2m.
During actual construction, when the pipe piece temporary supporting structures are used for reinforcing, after a plurality of pipe piece temporary supporting structures in each group of pipe piece temporary supporting structures are erected and all pipe piece temporary supporting structures are fastened and connected into a whole through the longitudinal connecting pieces, a screw jack 14 is used for applying prestress, and the pressure of each jack is preset to be 100kN.
In the embodiment, in the fourth step, the portal 3 is located at the rear side of the constructed connecting channel 2, the constructed connecting channel 2 is divided into the portal section and a front tunnel section located at the front side of the portal section, the portal section is excavated twice from front to back, and the front tunnel section is excavated and formed from back to front; step five, when the tunnel entrance section is subjected to tunnel entering construction, the tunnel entrance section is excavated for the first time from back to front, and an excavation-shaped tunnel entrance transition section is obtained; the cross section of the tunnel portal transition section is smaller than that of the front tunnel section, and the cross section of the tunnel portal transition section is gradually increased from back to front;
in the fifth step, referring to fig. 6 and fig. 7, in the process of performing the tunnel entrance section tunnel entrance construction, a plurality of rows of grouting pipes 15 are pre-buried in the arch part of the tunnel entrance transition section from back to front, the plurality of rows of grouting pipes 15 are arranged from back to front, each row of grouting pipes 15 comprises a plurality of grouting pipes 15 arranged along the arch part excavation contour line of the tunnel entrance transition section, and a plurality of grouting pipes 15 in each row of grouting pipes 15 are arranged on the same cross section of the constructed connecting channel 2; each grouting pipe 15 is gradually inclined upwards from back to front;
and fifthly, in the process of excavating from back to front, the excavation-molded opening transition section is subjected to primary support synchronously from back to front, and a temporary primary support structure of the opening transition section is obtained.
In actual construction, the cross-sectional structures and the dimensions of the tunnel portal section and the front tunnel section are the same as those of the pre-designed constructed connecting passage 2. The length of the grouting pipe 15 is 2 m-3 m.
In this embodiment, the temporary primary support structure includes a plurality of steel arches 16 supporting the opening section from back to front and an anchor net spraying support structure supporting the opening section.
In order to improve the reinforcement effect and simplify the construction, the grouting pipe 15 is a small advance conduit for grouting reinforcement of the arch stratum of the tunnel portal section.
In this embodiment, the structure and the size of the portal 3 are the same as the cross-sectional structure and the size of the rear end of the portal section.
In this embodiment, after the front tunnel segment is excavated in the step six, the shield segment ring located at the front side of the constructed connecting channel 2 is cut and removed, so as to obtain the front tunnel portal of the constructed connecting channel 2.
In the sixth step, after the front tunnel section is excavated, advanced support is carried out on the arch stratum of the tunnel portal transition section through a plurality of rows of grouting pipes 15; then, breaking the temporary primary support structure in the opening transition section from front to back;
In the process of breaking the temporary primary support structure from front to back, carrying out secondary excavation on the hole section from front to back to obtain the excavation-shaped hole section; and in the process of carrying out secondary excavation on the hole section from front to back, carrying out primary support on the hole section formed by excavation synchronously from back to front.
In the embodiment, in the process of carrying out secondary excavation on the opening section from front to back, an advanced small guide pipe is adopted to carry out advanced support on the arch wall of the opening section.
And step four, when the duct piece is cut and removed, the shield duct piece ring positioned at the rear side of the constructed connecting channel 2 is cut and removed, and the portal 3 at the rear end of the constructed connecting channel 2 is obtained, wherein the structure and the size of the portal 3 are the same as those of the cross section of the pre-designed constructed connecting channel 2. Thus, the portal 3 at the rear end of the constructed connecting passage 2 is cut and removed twice before and after.
In actual construction, the length of the opening section is 1.5 m-3.5 m.
In this embodiment, the length of the hole section is 2m, and the length of the hole section can be adjusted accordingly according to specific needs.
Before the actual construction of the tunnel portal section, firstly carrying out predicted quantity line drawing on the tunnel portal 3 to be dismantled, then cutting the duct piece at the tunnel portal 3 and starting to excavate the earth and stone for the constructed connecting channel 2. In this embodiment, the earth and stone side excavation of the constructed communication channel 2 adopts a step-up and step-down method, which is favorable for the stability of the excavation surface, is suitable for water-rich sand areas, and ensures the construction safety.
In this embodiment, when the tunnel portal section is excavated, the slope is firstly excavated from the design elevation of the tunnel portal 3 to the design vault of the constructed communication channel 2, and the temporary primary support of the gradual excavation transition section (i.e. the tunnel portal section) is formed by timely performing the primary support, meanwhile, the grouting pipe 15 of the transition section is pre-buried, the external angle of the grouting pipe 15 pre-buried in the tunnel needs to ensure that the grouting small pipe does not penetrate through the top slope of the gradual excavation transition section and invades into the tunnel, so the external angle of the grouting pipe 15 is larger than the slope angle of the slope of the gradual excavation transition section, the temporary primary support of the gradual excavation transition section is broken from the opposite direction of the excavation after the primary support of the constructed communication channel 2 is penetrated, the gradual excavation transition section is excavated to the design requirement, and the permanent primary support structure is implemented.
Wherein, the water-rich sand layer refers to a sand layer positioned below the groundwater level.
In this embodiment, the constructed communication channel 2 is located below the groundwater level.
Because the constructed connecting channel 2 is connected between the two constructed shield tunnels 1, in order to avoid adverse effects on the structural stability of the two shield tunnels 1, the ground subsidence of the area where the two shield tunnels 1 are positioned and the like in the precipitation construction process, the stratum of the construction area where the constructed connecting channel 2 is positioned is not subjected to precipitation before the stratum is subjected to grouting reinforcement by adopting the method.
The grouting reinforcement is carried out by adopting the method, the construction is simple and convenient, the reinforcement quality is convenient to control, after the grouting reinforcement is finished, the reinforced stratum and the shield segment in the constructed shield tunnel 1 are fixedly connected into a whole, the stratum reinforcement effect of the area where the constructed communication channel 2 is positioned is further improved, the structural stability of the shield tunnel 1 can be effectively improved, and the earth surface subsidence of the shield tunnel 1 can be effectively limited or even avoided.
According to the method, the pre-reinforced stratum of the connecting channel 2 in the water-rich sand layer area is divided into a plurality of reinforced areas, and stratum pre-reinforcement construction is carried out on different reinforced areas by adopting different reinforcement methods, so that stable reinforcement of the pre-reinforced stratum of the connecting channel 2 is realized, a foundation is laid for excavation of the subsequent connecting channel 2, collapse risk during excavation of the connecting channel 2 is reduced, and construction safety is guaranteed.
In this embodiment, the constructed communication channel 2 is arranged horizontally, and the grouting end of the advance small pipe 8 is positioned below the vault of the constructed communication channel 2.
And the two shield tunnels 1 are connected with the constructed connecting passage 2, and the areas are provided with the portal 3 of the constructed connecting passage 2.
After grouting reinforcement in step 201 is completed, the stratum at the front end and the back end of the constructed connecting channel 2 is symmetrically reinforced through two symmetrically arranged stratum reinforcing structures at the end of the channel, and meanwhile, two symmetrical grouting stopping rings are formed by the two stratum reinforcing structures at the end of the channel, so that slurry backflow in the whole grouting reinforcement grouting process of the channel stratum in step 202 can be prevented, underground water flows at the front end and the back end of the constructed connecting channel 2 can be effectively intercepted, the structural stability of the joint between the constructed connecting channel 2 and the two shield tunnels 1 is ensured, and construction safety is ensured.
It should be noted that, passageway tip stratum reinforced structure wraps up the stratum of connection passageway 2 gradual change excavation changeover portion, and the stratum that is located gradual change excavation changeover portion top when preventing gradual change excavation changeover portion back dig consolidates inadequately, guarantees the safety of follow-up connection passageway 2 excavation at any moment.
In this embodiment, referring to fig. 1, fig. 2, and fig. 3, when grouting reinforcement is performed on the stratum at the end of the tunnel in step 201, a group of small advance pipes 8 are firstly set up to the stratum at the front and rear ends of the constructed connecting tunnel 2 through two shield tunnels 1, and the two groups of small advance pipes 8 are symmetrically arranged; grouting and reinforcing stratum at the front end and the rear end of the constructed communication channel 2 respectively through two groups of small advance guide pipes 8;
each group of the advance small guide pipes 8 comprises a plurality of advance small guide pipes 8 which are uniformly distributed on the same plane, and the plurality of the advance small guide pipes 8 in each group of the advance small guide pipes 8 are distributed from left to right along the width direction of the constructed communication channel 2 and are distributed in parallel; each small leading guide pipe 8 is arranged along the longitudinal extending direction of the constructed communication channel 2, one end of each small leading guide pipe 8 is a stratum driving end driven into the stratum, and the other end of each small leading guide pipe is a grouting end; each of the small advance guide pipes 8 is gradually inclined upward from the grouting end to the stratum driving end;
And in the step 203, when the supplementary grouting reinforcement is carried out, the two groups of leading small guide pipes 8 are used for respectively carrying out the supplementary grouting reinforcement on the stratum at the front end and the back end of the constructed communication channel 2.
In actual construction, the two groups of the advance small guide pipes 8 are arranged simply and conveniently, and the construction is convenient.
The stratum driving end of the advance small guide pipe 8 is positioned above the vault of the constructed communication channel 2, and the vertical distance between the stratum driving end and the vault is 0.5 m-2 m.
In this embodiment, the vertical distance between the ground driving end of the leading small pipe 8 and the dome of the constructed communication passage 2 is 1.5m. Therefore, the advance small guide pipe 8 is adopted to carry out grouting reinforcement within the range of 1.5m outside the two ends of the constructed connecting channel 2.
In the actual construction process, the vertical distance between the stratum driving end of the advance small guide pipe 8 and the vault of the constructed communication channel 2 can be correspondingly adjusted according to specific requirements.
From the foregoing, it can be seen that the formation reinforcement structure at the end of the passage in step 201 is a leading small conduit grouting support structure. Therefore, in step 201, grouting is performed according to a conventional advanced small catheter grouting method, so that practical construction is simple and convenient, and grouting reinforcement effect is good.
In this embodiment, the constructed communication channel 2 is laid horizontally.
It should be noted that, because the stratum at the end of the passage near the side wall of the segment of the shield tunnel 1 is often provided with a water flow passage, when the sleeve valve pipe 4 which is arranged by punching on the opposite side portal 3 is adopted for reinforcement, the grouting effect of the stratum driving end is not good because the sleeve valve pipe 4 is long, and the two factors act together, so that the unset slurry is easily flushed away by water flow when the stratum at the end of the passage is reinforced by grouting through the sleeve valve pipe 4, so the grouting effect of the sleeve valve pipe 4 is very poor; furthermore, because the position is positioned at the top of the tunnel portal 3 and is close to the outer side wall of the segment of the shield tunnel 1, collapse risks exist at the position where the connecting channel is excavated, the reinforcing effect of the stratum can be guaranteed only by the extra grouting of the advanced small guide pipe 8, and the excavation safety of the subsequent connecting channel is guaranteed.
After grouting reinforcement of the tunnel end stratum is completed in step 201, the two tunnel end stratum reinforcing structures after construction is completed have the following beneficial effects: firstly, the reinforcement effect of the subsequent sleeve valve pipe grouting reinforcement can be effectively enhanced, and the two stratum reinforcement structures at the end parts of the channel can be used as grouting stopping structures for sleeve valve pipe grouting reinforcement in the step 202, so that leakage is prevented, the grouting density and the grouting pressure of sleeve valve pipe grouting are effectively improved, and the sleeve valve pipe grouting reinforcement strength is enhanced; secondly, the shield tunnels 1 on the two sides can be effectively protected, and any adverse effect on the shield tunnels 1 on the two sides in the subsequent construction process is prevented; thirdly, the shield segments at the joint between the two side shield tunnels 1 and the constructed connecting channel 2 are effectively reinforced, so that the construction quality of the joint between the constructed connecting channel 2 and the two side shield tunnels 1 can be effectively improved; fourthly, groundwater above the joint between the shield tunnel 1 and the constructed connecting channel 2 can be effectively intercepted, so that the construction quality of the joint between the shield tunnels 1 and the constructed connecting channel 2 on two sides is further ensured, the construction difficulty and the construction risk are reduced, the construction period is effectively saved, and the grouting reinforcement effect of the subsequent sleeve valve pipe can be further enhanced; meanwhile, the subsequent precipitation effect can be effectively improved; fifth, two stratum reinforcing structures at the end parts of the channel and sleeve valve pipe grouting reinforcing structures can be fastened and connected into a whole to form an integral reinforcing structure which is fastened and connected between two shield tunnels 1, so that the integrity and stability of the shield tunnels 1 at the two sides and the constructed connecting channel 2 can be effectively enhanced, and the long-term use effect is ensured; sixth, as the stratum at the two ends of the constructed connecting channel 2 is a reinforced weak area for grouting reinforcement of the subsequent sleeve valve pipe, the defect of grouting reinforcement of the subsequent sleeve valve pipe can be effectively overcome through grouting reinforcement of the stratum at the end part of the channel.
After the grouting reinforcement of the sleeve valve pipe in the step 202 is completed, the sleeve valve pipe grouting reinforcement structure integrally and effectively reinforces the stratum where the constructed communication channel 2 is located, and the sleeve valve pipe grouting reinforcement structure adopts a radial grouting reinforcement mode, so that the aim of reinforcing the stratum where the constructed communication channel 2 is located in a full range can be fulfilled, and the integral reinforcement effect is very good; the arrangement space of the advance small guide pipes 8 in the stratum at the two ends of the constructed communication channel 2 is smaller, so that grouting density and grouting reinforcement effect in the stratum at the two ends of the constructed communication channel 2 can be effectively ensured; while the leading small guide pipes 8 in the middle part of the constructed communication channel 2 are arranged at larger intervals, the leading small guide pipes 8 on the front side and the rear side of the middle part of the constructed communication channel 2 are mutually intersected, so that the grouting density and grouting reinforcement effect in the stratum can be ensured as well.
After the supplementary grouting reinforcement is actually performed, the grouting reinforcement effect of the stratum at the end part of the channel in step 201 is further enhanced, and the overall reinforcement effect of the stratum where the constructed communication channel 2 is located can be further enhanced.
In order to control the grouting reinforcement of the stratum at the end part of the channel in the step 201, stopping grouting when the grouting pressure of all the leading small pipes 8 in the two groups of leading small pipes 8 reaches P1, and completing the grouting reinforcement process of the stratum at the end part of the channel; wherein P1 is a preset grouting pressure value, and the value range of P1 is 0.7 MPa-0.8 MPa;
When the supplementary grouting reinforcement is actually carried out, stopping grouting when the grouting pressure of all the leading small pipes 8 in the two groups of leading small pipes 8 reaches P2, and completing the supplementary grouting reinforcement process; wherein P2 is a preset supplementary grouting pressure value, and the value range of P2 is 0.5MPa to 0.6MPa.
In this example, p1=0.75 MPa and p2=0.55 MPa. In actual construction, the values of P1 and P2 can be correspondingly adjusted according to specific requirements.
In this embodiment, the areas where the two shield tunnels 1 are connected with the constructed connecting channel 2 are tunnel connection areas, and each group of the advance small pipes 8 are uniformly distributed outside one tunnel connection area; the distance D between the two leading small pipes 8 positioned at the leftmost side and the rightmost side in each group of the leading small pipes 8 is larger than the excavation width of the constructed communication channel 2;
the number of the advance small pipes 8 included in each group of the advance small pipes 8 is 2M, wherein M is a positive integer and M is more than or equal to 3; the number of the leading small pipes 8 positioned at the left and right sides of the central line of the tunnel of the constructed communication channel 2 in each group is M;
in step 201 and in step 203, grouting is performed by any group of the advance small pipes 8, and grouting is performed symmetrically from the middle to the left and right sides respectively.
Wherein D is 6 m-12 m larger than the excavation width of the constructed connecting channel 2.
In this embodiment, m=4. And d=16m.
In actual construction, the values of M and D can be correspondingly adjusted according to specific requirements.
In practical construction, all the advance small pipes 8 in each group of the advance small pipes 8 have the same size and the same layout height. The included angles between the plurality of the leading small pipes 8 in each group of the leading small pipes 8 and the horizontal plane are the same, and the grouting ends of all the leading small pipes 8 in each group of the leading small pipes 8 are positioned on the same horizontal plane.
In this embodiment, the included angle between the small advancing pipe 8 and the horizontal plane (i.e., the external inserting angle of the small advancing pipe 8) is 15 ° to 30 °.
In this embodiment, the advance small conduit 8 laid in step 201 is a grouting pipe driven into the stratum through a pipe piece lifting hole on a shield pipe piece ring in the shield tunnel 1.
It should be noted that, the advanced small conduit 8 is arranged through the pipe piece lifting hole, so that the integrity of the pipe piece ring is ensured to a great extent, the entity quality of the shield tunnel 1 is ensured, and the safety and stability of the tunnel structure are ensured.
In this embodiment, before grouting reinforcement of sleeve valve pipes in step 202, construction is performed on front and rear sleeve valve pipe grouting structures through two shield tunnels 1, where the two sleeve valve pipe grouting structures are symmetrically arranged and are grouting reinforcement structures for integrally reinforcing a stratum 5 to be reinforced; each sleeve valve pipe grouting structure comprises a plurality of sleeve valve pipes 4 driven into a stratum 5 to be reinforced from the same shield tunnel 1, and the sleeve valve pipes 4 in each sleeve valve pipe grouting structure are distributed radially; the stratum 5 to be reinforced is a stratum within the range of L meters outside the excavation contour line of the constructed connecting channel 2, wherein the value range of L is 2.5-3.5;
Each sleeve 4 in one sleeve grouting structure crosses at least one sleeve 4 in the other sleeve grouting structure.
In this embodiment, the value of L is 3. Thus, the formation 5 to be reinforced is a formation within 3 meters outside the excavated contour of the constructed connecting channel 2.
During actual construction, the value of L can be correspondingly adjusted according to specific requirements.
In this embodiment, the stratum to be reinforced 5 is divided into a overlapping reinforcing region 6, an outer grouting weak region 9 located at the outer side of the overlapping reinforcing region 6, and two end grouting weak regions 7 located at the front and rear sides of the overlapping reinforcing region 6, where the overlapping reinforcing region 6 is a region where grouting regions of two sleeve valve pipe grouting structures overlap;
the two end grouting weak areas 7 are respectively positioned above the front end and the rear end of the overlapped reinforcing area 6, and the advance small guide pipe 8 arranged in the step 201 is positioned in the end grouting weak areas 7; the two end grouting weak areas 7 are all advanced small guide pipe grouting reinforcing areas reinforced by adopting an advanced small guide pipe 8, and the overlapping reinforcing areas 6 and the two end grouting weak areas 7 form a core reinforcing area;
the stratum where the constructed connecting channel 2 is located in the core reinforcing area.
In actual construction, all the leading small ducts 8 in each group of the leading small ducts 8 are located in the same end grouting weak area 7.
It should be noted that, the outer grouting weak area 9 and the end grouting weak area 7 are non-overlapping areas of grouting areas of the two sleeve valve pipe grouting structures, and because the end grouting weak area 7 is more prone to collapse, the reinforcing effect of the non-overlapping areas of grouting areas of the two sleeve valve pipe grouting structures can meet the formation reinforcing requirement of the outer grouting weak area 9 but cannot meet the formation reinforcing requirement of the end grouting weak area 7, and therefore the end grouting weak area 7 needs to be additionally subjected to grouting reinforcing construction by the advance small guide pipe 8.
The outside grouting weak area 9 does not carry out grouting reinforcement additionally when stratum is pre-reinforced, construction period is saved, the outside grouting weak area 9 can be reinforced again through the advance small guide pipes which are arranged on the vault of the channel in a beating mode and are parallel to each other when the communication channel 2 is initially supported, and stability of the communication channel is guaranteed.
In this embodiment, the tunnel hole of the constructed communication channel 2 is divided into a lower hole body and an upper hole body located above the lower hole body;
each sleeve valve pipe grouting structure comprises a plurality of groups of upper sleeve valve pipes for reinforcing a stratum 5 to be reinforced in the area where the upper hole body is located and a plurality of groups of lower sleeve valve pipes for reinforcing the stratum 5 to be reinforced in the area where the lower hole body is located, wherein the plurality of groups of upper sleeve valve pipes and the plurality of groups of lower sleeve valve pipes are all distributed from inside to outside; each group of upper sleeve valve pipes comprises a plurality of sleeve valve pipes 4 which are distributed along the excavation outline of the upper hole body, and the external insertion angles of the sleeve valve pipes 4 of a plurality of groups of upper sleeve valve pipes are gradually increased from inside to outside; each group of lower sleeve valve pipes comprises a plurality of sleeve valve pipes 4 which are distributed along the excavation outline of the lower hole body, and the external insertion angles of the sleeve valve pipes 4 of a plurality of groups of lower sleeve valve pipes are gradually increased from inside to outside;
In the process of grouting reinforcement of the sleeve valve pipe in step 202, grouting reinforcement is carried out from outside to inside when grouting reinforcement of the sleeve valve pipe is carried out through any sleeve valve pipe grouting structure.
Wherein, the external insertion angle of the sleeve valve tube 4 refers to the included angle between the sleeve valve tube 4 and the central axis of the constructed communication channel 2. The external insertion angle of the sleeve valve tube 4 is not more than 30 degrees.
In this embodiment, the areas where the two shield tunnels 1 are connected with the constructed connecting channel 2 are tunnel connection areas, and the shield segment rings of the tunnel connection areas in the two shield tunnels 1 are provided with a plurality of sleeve valve tube mounting holes for the sleeve valve tubes 4 to be arranged.
And the tunnel connection areas in the two shield tunnels 1 are provided with a portal 3 of the constructed communication channel 2, the opening area of the portal 3 on the shield segment in the shield tunnel 1 is a portal opening area, and the sleeve valve tube mounting hole is positioned in the portal opening area.
It should be noted that, in order to ensure the integrity of the segment of the shield tunnel 1 except the region where the portal is opened, the sleeve valve tube 4 in the pre-reinforcing process of the formation of the connecting channel 2 can only be set into the formation by the region where the portal is opened, and the maximum elevation angle of the sleeve valve tube 4 is limited by the limit, so that the sleeve valve tube 4 cannot penetrate into the connection region between the shield tunnel 1 and the connecting channel 2, and the grouting of the sleeve valve tube 4 cannot completely cover the preset formation 5 to be reinforced of the connecting channel 2, thereby the end grouting weak region 7 occurs.
In this embodiment, the angle of the outer sleeve 4 above the portal 3 is in the range of 25 ° to 30 °.
When the constructed communication channel 2 is actually excavated, the construction is performed from the rear to the front along the longitudinal extending direction. In order to ensure the structural stability of the joint between the constructed connecting channel 2 and the shield tunnel 1 and reduce the construction risk, the portal 3 positioned at the rear side of the constructed connecting channel 2 is rectangular, and the portal opening area positioned in the shield tunnel 1 at the rear side of the constructed connecting channel 2 is rectangular and has the same structure and size as the portal 3. The width of the cavity door 3 positioned at the rear side of the constructed communication channel 2 is smaller than the excavation width of the constructed communication channel 2, and the height of the cavity door 3 is smaller than the excavation height of the constructed communication channel 2. At the same time, the roof of the portal 3 at the rear side of the constructed communication channel 2 is lower than the dome of the constructed communication channel 2. The grouting end of the leading small conduit 8 is positioned above the tunnel portal 3, and the grouting end of the leading small conduit 8 is positioned below the vault of the constructed communication channel 2.
In this embodiment, a plurality of the advance small pipes 8 in each group of the advance small pipes 8 are uniformly distributed, the distance between two adjacent advance small pipes 8 is the same as the distance between two adjacent shield segment rings in the shield tunnel 1, and the grouting end of each advance small pipe 8 is supported on one shield segment ring.
In step 202, a conventional sleeve grouting reinforcement method is used for sleeve grouting. The length of the constructed connecting channel 2 is 10 m-20 m. In the embodiment, the buried depth of the constructed communication channel 2 is 11.55m, the length is 15.80m, the section size is 3.80m multiplied by 4.57m, the mixed filling soil, the silt and the middle sand are distributed from top to bottom, the stable water level buried depth of the underground water is between 10.30m and 11.80m, and the cavity of the constructed communication channel 2 is positioned in the water-rich middle sand layer.
In the embodiment, the sleeve valve tube 4 is a PVC tube with the diameter phi of 48mm, the interval is 300mm multiplied by 300mm, the grouting liquid is cement-water glass double-liquid slurry, the volume ratio of cement to water glass is 1:1, the water glass concentration is 35Be, the water-cement ratio of cement is 1:1, the normal diffusion of the slurry is ensured, and the grouting is performed in a mode of gradually increasing the pressure. In step 202, the sleeve valve pipe grouting is performed, and the reinforcement range is 3m outside the tunnel contour of the constructed communication channel 2.
In this embodiment, the small advance pipe 8 is a steel pipe with a diameter Φ50mm and a length of 2 m. The grout injected into the small advance pipe 8 is the same as that injected into the sleeve valve tube 4.
In summary, when grouting is performed in step 201, when grouting is performed in step 202 and when supplementary grouting is actually performed, grouting is performed in a hole (namely, in a tunnel hole of a shield tunnel 1), grouting is simple and convenient, grouting reinforcement is not needed from outside the hole (namely, the ground), construction cost can be reduced, construction period is saved, the problems that the ground is greatly influenced, construction difficulty is high, input cost is high, construction period cannot be effectively ensured and the like in the existing jet grouting pile reinforcement process can be effectively avoided, and the stratum where a constructed communication channel 2 is located can be effectively reinforced while the stratum where two shield tunnels 1 are connected with the constructed communication channel 2 is simultaneously reinforced; meanwhile, the shield tunnel 1 can be effectively reinforced, and particularly the shield segment ring at the joint between the two shield tunnels 1 and the constructed connecting channel 2 can be effectively reinforced. In addition, the leading small guide pipe 8 is inserted into the stratum through the pipe piece lifting hole, and the sleeve valve pipe 4 is inserted into the stratum through the tunnel portal opening area, so that the leading small guide pipe 8 and the sleeve valve pipe 4 are arranged so as not to cause any damage to the shield pipe piece ring of the shield tunnel 1, the integrity of the pipe piece ring is ensured to a great extent, the entity quality of the shield tunnel 1 is ensured, and the safety and stability of the tunnel structure are ensured.
In the embodiment, the excavation of the constructed connecting channel 2 adopts a step-up and step-down method, and the construction of the primary support and the secondary lining adopts a conventional construction scheme.
The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and any simple modification, variation and equivalent structural changes made to the above embodiment according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.

Claims (6)

1. A water-rich sand layer shield interval connection channel excavation construction method is characterized by comprising the following steps of: the constructed connecting channel (2) is a subsurface tunnel which is connected between two shield tunnels (1) and the tunnel body of which is positioned in the water-rich sand layer, and the constructed connecting channel (2) is divided into a tunnel opening section and a front tunnel section positioned at the front side of the tunnel opening section; when the constructed connecting channel (2) is excavated, the method comprises the following steps:
step one, erecting a temporary support structure of the duct piece: a group of duct piece temporary supporting structures are respectively erected in the two shield tunnels (1), and the two groups of duct piece temporary supporting structures are respectively positioned at the front side and the rear side of the constructed connecting channel (2);
the segment temporary supporting structure is supported on the inner side of a shield segment ring in the shield tunnel (1);
Step two, stratum pre-reinforcement: pre-reinforcing stratum where the constructed connecting channel (2) is located, wherein the process is as follows:
step 201, grouting and reinforcing stratum at the end part of the channel: carrying out advanced small-conduit grouting reinforcement on stratum at the front end and the rear end of a constructed connecting channel (2) through two shield tunnels (1), and forming a channel end stratum reinforcement structure at the outer sides of the two shield tunnels (1);
step 202, grouting and reinforcing the whole channel stratum: respectively grouting and reinforcing sleeve valve pipes on the whole stratum where the constructed connecting channel (2) is located through the two shield tunnels (1) to obtain a sleeve valve pipe grouting and reinforcing structure;
the two tunnel end stratum reinforcing structures constructed in the step 201 are slurry stopping structures used for sleeve valve pipe grouting reinforcement in the step, and the sleeve valve pipe grouting reinforcing structures and the two tunnel end stratum reinforcing structures are fixedly connected into a whole;
thirdly, constructing a vertical transportation channel (17): constructing a vertical transportation channel (17) at the rear end of the front tunnel section from the ground to the bottom, wherein the vertical transportation channel (17) is communicated with the inside of the constructed communication channel (2);
step four, segment cutting and dismantling: cutting and dismantling shield segment rings at the hole entering position of the constructed connecting channel (2) in the shield tunnel (1) to obtain a portal (3) of the constructed connecting channel (2);
Fifthly, entering the tunnel construction at the tunnel portal section: excavating the opening section of the constructed connecting channel (2) from back to front through the opening (3) in the fourth step; after excavation is completed, the hole section is communicated with the vertical transportation channel (17) in the third step;
step six, front tunnel section excavation construction: excavating the front tunnel section of the constructed connecting channel (2) from back to front by using the vertical transportation channel (17) in the step three;
in the step 201, when grouting reinforcement is carried out on stratum at the end part of a channel, a group of advance small guide pipes (8) are respectively arranged at the front end and the rear end of a constructed connecting channel (2) through two shield tunnels (1), and the two groups of advance small guide pipes (8) are symmetrically arranged; grouting and reinforcing stratum at the front end and the rear end of the constructed connecting channel (2) respectively through two groups of small advance guide pipes (8);
each group of the advance small guide pipes (8) comprises a plurality of advance small guide pipes (8) which are uniformly distributed on the same plane, and the plurality of the advance small guide pipes (8) in each group of the advance small guide pipes (8) are distributed from left to right along the width direction of the constructed communication channel (2) and are distributed in parallel; each small leading conduit (8) is arranged along the longitudinal extending direction of the constructed connecting channel (2), one end of each small leading conduit (8) is a stratum driving end driven into the stratum, and the other end of each small leading conduit is a grouting end; each leading small guide pipe (8) gradually inclines upwards from the grouting end to the stratum driving end;
After the integral grouting reinforcement of the passage stratum in the step 202 is completed, the stratum at the front end and the back end of the constructed connecting passage (2) is respectively subjected to supplementary grouting reinforcement through the advance small guide pipes (8) arranged in the step 201 to obtain a stratum grouting reinforcement structure at the end part of the passage, and the stratum grouting reinforcement structure at the end part of the passage is fastened and connected with the sleeve valve pipe grouting reinforcement structure in the step 202 into a whole;
when the supplementary grouting reinforcement is actually carried out, the two groups of leading small guide pipes (8) are used for respectively carrying out supplementary grouting reinforcement on stratum at the front end and the rear end of the constructed connecting channel (2);
before sleeve valve pipe grouting reinforcement is carried out in step 202, construction is carried out on front and rear sleeve valve pipe grouting structures through two shield tunnels (1), and the two sleeve valve pipe grouting structures are symmetrically distributed and are grouting reinforcement structures for integrally reinforcing a stratum (5) to be reinforced; each sleeve valve pipe grouting structure comprises a plurality of sleeve valve pipes (4) driven into a stratum (5) to be reinforced from the same shield tunnel (1), and the sleeve valve pipes (4) in each sleeve valve pipe grouting structure are radially distributed; the stratum (5) to be reinforced is a stratum within the range of L meters outside the excavation contour line of the constructed connecting channel (2), wherein the value range of L is 2.5-3.5;
Each sleeve valve tube (4) in one sleeve valve tube grouting structure is intersected with at least one sleeve valve tube (4) in the other sleeve valve tube grouting structure;
the stratum to be reinforced (5) is divided into a heavy overlaying and reinforcing area (6), an outer grouting weak area (9) positioned at the outer side of the overlaying and reinforcing area (6) and two end grouting weak areas (7) positioned at the front side and the rear side of the overlaying and reinforcing area (6), wherein the overlaying and reinforcing area (6) is an area where grouting areas of two sleeve valve pipe grouting structures are overlapped;
the two end grouting weak areas (7) are respectively positioned above the front end and the rear end of the overlapped reinforcing area (6), and the advance small guide pipe (8) arranged in the step 201 is positioned in the end grouting weak areas (7); the two end grouting weak areas (7) are all advanced small conduit grouting reinforcing areas reinforced by adopting advanced small conduits (8), and the overlapping reinforcing areas (6) and the two end grouting weak areas (7) form a core reinforcing area;
the stratum where the constructed connecting channel (2) is located in the core reinforcing area.
2. The construction method for excavating the connecting channel between the shield sections of the water-rich sand layer is characterized by comprising the following steps of: the areas where the two shield tunnels (1) are connected with the constructed connecting channel (2) are tunnel connection areas, tunnel sections where the tunnel connection areas in each shield tunnel (1) are located are tunnel sections to be reinforced, and the two groups of segment temporary support structures are respectively arranged in the tunnel sections to be reinforced of the two shield tunnels (1);
Each group of segment temporary support structures comprises 2N segment temporary support structures for temporarily supporting shield segment rings in the tunnel segment to be reinforced one by one, the structures of the 2N segment temporary support structures in each group of segment temporary support structures are the same and are distributed from back to front along the longitudinal extension direction of the distributed shield tunnel (1), each segment temporary support structure is supported in one shield segment ring, and each segment temporary support structure is positioned on one tunnel cross section of the shield tunnel (1); wherein N is a positive integer and N is more than or equal to 2;
each group of duct piece temporary supporting structures is divided into two duct piece temporary supporting groups which are respectively positioned at two sides of the tunnel junction area, and each duct piece temporary supporting group comprises N duct piece temporary supporting structures.
3. The construction method for excavating the connecting channel between the shield sections of the water-rich sand layer according to claim 1 or 2, which is characterized by comprising the following steps: in the fourth step, the tunnel portal (3) is positioned at the rear side of the constructed connecting channel (2), the constructed connecting channel (2) is divided into the tunnel portal section and a front tunnel section positioned at the front side of the tunnel portal section, the tunnel portal section is excavated twice from front to back, and the front tunnel section is excavated and formed from back to front; step five, when the tunnel entrance section is subjected to tunnel entering construction, the tunnel entrance section is excavated for the first time from back to front, and an excavation-shaped tunnel entrance transition section is obtained; the cross section of the tunnel portal transition section is smaller than that of the front tunnel section, and the cross section of the tunnel portal transition section is gradually increased from back to front;
In the process of entering a tunnel from a tunnel entrance section, a plurality of rows of grouting pipes (15) are pre-buried in the arch part of the tunnel entrance transition section from back to front synchronously, a plurality of rows of grouting pipes (15) are distributed from back to front, each row of grouting pipes (15) comprises a plurality of grouting pipes (15) distributed along the arch part excavation outline of the tunnel entrance transition section, and a plurality of grouting pipes (15) in each row of grouting pipes (15) are distributed on the same cross section of a constructed communication channel (2); each grouting pipe (15) gradually inclines upwards from back to front;
and fifthly, in the process of excavating from back to front, the excavation-molded opening transition section is subjected to primary support synchronously from back to front, and a temporary primary support structure of the opening transition section is obtained.
4. The construction method for excavating the connecting channel between the shield sections of the water-rich sand layer according to claim 3, which is characterized by comprising the following steps: in the sixth step, after the front tunnel section is excavated, advanced support is carried out on the arch stratum of the tunnel portal transition section through a plurality of rows of grouting pipes (15); then, breaking the temporary primary support structure in the opening transition section from front to back;
In the process of breaking the temporary primary support structure from front to back, carrying out secondary excavation on the hole section from front to back to obtain the excavation-shaped hole section; and in the process of carrying out secondary excavation on the hole section from front to back, carrying out primary support on the hole section formed by excavation synchronously from back to front.
5. The construction method for excavating the connecting channel between the shield sections of the water-rich sand layer according to claim 1 or 2, which is characterized by comprising the following steps: in the third step, the vertical transportation channel (17) is vertically distributed;
in the third step, when the vertical transportation channel (17) is constructed, drilling is firstly carried out from top to bottom by adopting drilling equipment, and a steel casing (18) is arranged in the formed drilling; the upper end of the steel protection cylinder (18) extends out of the ground and is fixedly supported on the ground, and the bottom end of the steel protection cylinder (18) is positioned below the vault of the front tunnel section.
6. The construction method for excavating the connecting channel between the shield sections of the water-rich sand layer according to claim 1 or 2, which is characterized by comprising the following steps: the advance small guide pipe (8) arranged in the step 201 is a grouting pipe which is driven into a stratum through a pipe piece lifting hole on a shield pipe piece ring in the shield tunnel (1).
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