CN114526376B - Construction method for stacked wire jacking pipe - Google Patents
Construction method for stacked wire jacking pipe Download PDFInfo
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- CN114526376B CN114526376B CN202210030258.0A CN202210030258A CN114526376B CN 114526376 B CN114526376 B CN 114526376B CN 202210030258 A CN202210030258 A CN 202210030258A CN 114526376 B CN114526376 B CN 114526376B
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L1/00—Laying or reclaiming pipes; Repairing or joining pipes on or under water
- F16L1/024—Laying or reclaiming pipes on land, e.g. above the ground
- F16L1/028—Laying or reclaiming pipes on land, e.g. above the ground in the ground
- F16L1/038—Laying or reclaiming pipes on land, e.g. above the ground in the ground the pipes being made in situ
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L1/00—Laying or reclaiming pipes; Repairing or joining pipes on or under water
- F16L1/024—Laying or reclaiming pipes on land, e.g. above the ground
- F16L1/06—Accessories therefor, e.g. anchors
-
- Y—GENERAL 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Ceramic Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Excavating Of Shafts Or Tunnels (AREA)
Abstract
The invention discloses a construction method for a stacked line jacking pipe, which is characterized in that bentonite thixotropic slurry is injected between the outer wall of a pipe joint and a soil body in a jacking process of the jacking pipe, so that a lubricating effect can be achieved, dry friction between the jacking pipe joint and the soil body is changed into wet friction, a complete antifriction slurry film is formed on a machine body shell and a pipe joint shell of jacking equipment, jacking friction resistance is effectively reduced, in addition, the bentonite thixotropic slurry can fill a gap between a pipeline and the soil body during construction, and meanwhile, under grouting pressure, soil deformation is reduced, and the bentonite thixotropic slurry can become a gel layer to support a stratum when static, so that a tunnel becomes stable. And after the jacking pipe is finished, cement slurry is injected between the outer wall of the pipe joint and the soil body to replace the bentonite thixotropic slurry, the soil body outside the pipe joint is reinforced, core soil is effectively solidified, the solidification strength of the core soil is convenient to control, the core soil is effectively prevented from sinking, and the posture of the push bench in upper-layer jacking pipe construction in the stacked wire jacking pipe construction is convenient to control.
Description
Technical Field
The invention relates to the technical field of pipe jacking construction, in particular to a stacked wire pipe jacking construction method.
Background
Under the condition of ultra-small clear distance (for example, 0.7 m), the core soil (for example, the old city miscellaneous fill in the range of 0.7 m) of the vault of the lower jacking pipe is disturbed in the tunneling process, the core soil of the vault is required to be reinforced after the jacking pipe is discharged from the tunnel, then the upper jacking pipe tunneling construction is organized, and the posture of the upper jacking pipe is extremely difficult to control due to the fact that the core soil is large in solidification discreteness (or hard/soft). For example, when the consolidation strength of core soil is less than 0.2MPa, the existing lower pipe-jacking segment is easily damaged by the pipe-jacking machine; and when the consolidation strength of core soil exceeds 2MPa, the ground collapse caused by over-digging after the pipe push bench is lifted easily occurs. Therefore, how to consolidate core soil and control the posture of the pipe pushing machine in the construction process of the overlapped wire pipe pushing is a core problem of safe construction, and no effective solution is provided at present.
Disclosure of Invention
The invention provides a construction method of a stacked wire jacking pipe, which aims to solve the technical problem that core soil cannot be effectively solidified when lower-layer jacking pipe construction is carried out in the existing stacked wire jacking pipe construction.
According to one aspect of the invention, there is provided a construction method of a stacked wire jacking pipe, comprising the following steps:
after finishing three-way and one-level construction on the construction site, carrying out construction operation of the originating well;
A pipe jacking device is installed in the starting well;
performing hole concrete chiseling operation;
hanging the pipe piece into an originating well, butting the pipe piece with a counter-force support system in the pipe jacking equipment and the originating well, performing pipe jacking construction operation, and injecting bentonite thixotropic slurry between the outer wall of the pipe joint and a soil body in the pipe jacking process; in the jacking process of the pipe jacking, a laser beam is shot out of an originating well according to a designed jacking axis by utilizing a laser theodolite and is shot on a light target in the center of the pipe jacking machine, the deviation of the axis can be observed from a monitor in the jacking process, and when the deviation of the jacking axis and a preset axis is detected, the deviation of the jacking axis is rectified through a plurality of groups of hydraulic cylinders on the pipe jacking equipment;
and after the jacking of all pipe joints is finished, removing the abandoned shell of the pipe jacking equipment, casting a concrete structure in the abandoned shell of the pipe jacking equipment, and injecting cement slurry between the outer wall of the pipe joint and the soil body to replace the bentonite thixotropic slurry.
Furthermore, each pipe joint needs to be stuck with a water stop ring and a wood gasket before being installed, the joint part of the pipe joint and the pipe joint is embedded, and the pipe joint and the machine body of the pipe jacking equipment are ensured to be in a concentric and coaxial state.
Further, the bentonite thixotropic slurry comprises the components of bentonite, water, sodium carbonate and CMC, wherein each cubic meter of bentonite thixotropic slurry comprises 200Kg of bentonite, 850Kg of water, 6Kg of sodium carbonate and 2.5Kg of CMC.
Further, the cement slurry comprises the components of cement, fly ash, an expanding agent and water, wherein each cubic meter of cement slurry comprises 300Kg of cement, 420Kg of fly ash, 64Kg of expanding agent and 660L of water.
Further, in the jacking process of the jacking pipe, reinforcing piles are arranged in a preset range of the end head to improve the strength of a soil body in front, when the machine head of the jacking pipe equipment enters a hole, the machine head and a pipe joint at the back are connected through a pull rod to form a whole, two chain blocks are tensioned at intervals of one meter on a guide rail, the machine head smoothly advances along the direction of the guide rail, grouting is carried out on a hole, after grouting is finished, an experiment is carried out on a brick joint of the hole, whether water is gushed out or not is detected, if water gushes out, the grouting drainage number is increased, and the tunneling machine head is ensured to smoothly enter the hole until the water gush does not occur.
Further, before the jacking pipe is started and jacked, a curtain cloth rubber plate sealing moving coil is required to be installed on the hole ring of the starting well.
Further, the grouting pressure of the bentonite thixotropic slurry is the soil pressure value measured at the center cutter head of the large cutter head of the pipe jacking equipment.
Further, a set of stop frame is respectively arranged on two sides of the front base, the bottom of the stop frame is welded and fixed on the base, a pin hole is formed in the stop frame, and when a wooden cushion block is required to be additionally arranged or a pipe joint is required to be assembled, a pin is inserted into the small hole in the stop frame and the hoisting hole of the pipe joint to prevent the pipe joint from retreating.
Further, in the jacking process of the jacking pipe, when a bad soil layer is encountered, mineral modifier is injected into the soil bin of the jacking pipe equipment through a grouting hole formed in the jacking pipe equipment, so that the plasticity, the fluidity and the water stopping performance of soil in the soil bin are improved.
Further, after jacking of all pipe joints is finished, post-pouring Liang Duiguan joints are applied to the top plate and the bottom plate of the starting hole to limit the pipe joints, displacement of the pipe joints is prevented, plugging steel rings are pre-buried in post-pouring beams, cement slurry is injected to fill gaps between the pipe joints and the enclosure structure and between the post-pouring beams and the post-pouring structure, and water-swelling rubber strips are arranged at construction joints of the post-pouring beams and the enclosure structure, between the post-pouring beams and the pre-buried plugging steel rings, and between the pre-buried plugging steel rings and the enclosure structure.
The invention has the following effects:
according to the construction method for the stacked wire jacking pipe, bentonite thixotropic slurry is injected between the outer wall of the pipe joint and the soil body in a pressing mode in the jacking process of the jacking pipe, the bentonite thixotropic slurry can play a role in lubrication, dry friction between the jacking pipe joint and the soil body is changed into wet friction, a complete antifriction slurry film is formed on the shell of the jacking equipment and the shell of the pipe joint, jacking friction is effectively reduced, normal construction is ensured, the bentonite thixotropic slurry also has filling and supporting functions, the bentonite thixotropic slurry can fill gaps generated between a pipeline and the soil body in construction, meanwhile, under grouting pressure, soil deformation is reduced, and the bentonite thixotropic slurry can become a gel layer to support a stratum when the jacking equipment is static, so that a tunnel becomes stable. Meanwhile, after the jacking of all pipe joints is finished, the concrete structure is poured in the abandoned shell after the abandoned shell of the pipe jacking equipment is dismantled at the receiving end, the shell of the pipe jacking equipment is used as a part of the channel lining to be left in the channel, only the internal equipment and parts of the pipe jacking equipment are dismantled, and the structural stability of the receiving end is ensured. And after the jacking pipe is finished, cement slurry is injected between the outer wall of the pipe joint and the soil body to replace the bentonite thixotropic slurry, the soil body outside the pipe joint is reinforced, core soil is effectively solidified, the solidification strength of the core soil is convenient to control, the core soil is effectively prevented from sinking, and the posture of the push bench in upper-layer jacking pipe construction in the stacked wire jacking pipe construction is convenient to control.
In addition to the objects, features and advantages described above, the present invention has other objects, features and advantages. The present invention will be described in further detail with reference to the drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:
fig. 1 is a schematic flow chart of a construction method of a stacked wire jacking pipe according to a preferred embodiment of the present invention.
Fig. 2 is a schematic structural view of a reaction bracket system according to a preferred embodiment of the present invention.
Fig. 3 is a schematic plan view of a reaction force bracket according to a preferred embodiment of the present invention.
Fig. 4 is a schematic front view of a reaction force bracket according to a preferred embodiment of the present invention.
Detailed Description
Embodiments of the invention are described in detail below with reference to the attached drawing figures, but the invention can be practiced in a number of different ways, as defined and covered below.
As shown in fig. 1, a preferred embodiment of the present invention provides a construction method of a stacked wire pipe, and in particular relates to a lower layer pipe construction in a stacked wire pipe construction, including the following contents:
step S1: after finishing three-way and one-level construction on the construction site, carrying out construction operation of the originating well;
Step S2: a pipe jacking device is installed in the starting well;
step S3: performing hole concrete chiseling operation;
step S4: hanging the pipe piece into an originating well, butting the pipe piece with a counter-force support system in the pipe jacking equipment and the originating well, performing pipe jacking construction operation, and injecting bentonite thixotropic slurry between the outer wall of the pipe joint and a soil body in the pipe jacking process;
step S5: and after the jacking of all pipe joints is finished, removing the abandoned shell of the pipe jacking equipment, casting a concrete structure in the abandoned shell of the pipe jacking equipment, and injecting cement slurry between the outer wall of the pipe joint and the soil body to replace the bentonite thixotropic slurry.
It can be understood that in the construction method of the stacked line jacking pipe of the embodiment, bentonite thixotropic slurry is injected between the outer wall of the pipe joint and the soil body in a pressing manner in the jacking process of the jacking pipe, the bentonite thixotropic slurry can play a role in lubrication, dry friction between the jacking pipe joint and the soil body is changed into wet friction, a complete antifriction slurry film is formed on the shell of the jacking equipment and the shell of the pipe joint, jacking friction is effectively reduced, normal construction is ensured, and the bentonite thixotropic slurry also has filling and supporting functions, so that the bentonite thixotropic slurry can fill gaps generated between a pipeline and the soil body during construction, meanwhile, under grouting pressure, soil deformation is reduced, and the bentonite thixotropic slurry can become a gel layer to support a stratum when static, so that a tunnel becomes stable. Meanwhile, after the jacking of all pipe joints is finished, the concrete structure is poured in the abandoned shell after the abandoned shell of the pipe jacking equipment is dismantled at the receiving end, the shell of the pipe jacking equipment is used as a part of the channel lining to be left in the channel, only the internal equipment and parts of the pipe jacking equipment are dismantled, and the structural stability of the receiving end is ensured. And after the jacking pipe is finished, cement slurry is injected between the outer wall of the pipe joint and the soil body to replace the bentonite thixotropic slurry, the soil body outside the pipe joint is reinforced, core soil is effectively solidified, the solidification strength of the core soil is convenient to control, the core soil is effectively prevented from sinking, and the posture of the push bench in upper-layer jacking pipe construction in the stacked wire jacking pipe construction is convenient to control.
It can be understood that in the step S1, after the construction site completes three-way and one-level, that is, after the electric connection, the water connection, the road connection and the land are leveled, the construction operation of the originating well is performed, and specific construction contents include the construction of the maintenance structures in the two working wells, the establishment of the reaction support system in the originating well, and the like. When the pipe jacking construction is carried out, the counterforce support system in the originating well normally directly supports the hydraulic jack on the rear wall of the originating well, but when the soil layer material in the originating well is softer, especially when the water content is higher, the rear wall of the originating well cannot provide enough counterforce for the hydraulic jack, and the pipe jacking construction difficulty is higher. Therefore, as preferable, as shown in fig. 2, the reaction support system includes a reaction wall, a back rest, a bottom plate (not shown) and a reaction support, the bottom plate is laid on the ground of the originating well, the reaction wall, the back rest and the reaction support are sequentially arranged along the pipe jacking direction, the reaction wall is rigidly connected with two side walls of the originating well, the back rest is rigidly connected with the reaction wall, the reaction support is fixedly installed on the bottom plate, a plurality of jacking devices are installed on the reaction support, one end of each jacking device is used for pushing a pipe piece to tunnel, and the other end of each jacking device is propped against the back rest. The reaction support is positioned in front of the pipe jacking tunneling direction, the back rest is positioned between the reaction wall and the reaction support, and the jacking device is a hydraulic jack. In addition, fig. 2 is a schematic structural view of a reaction force support system in lower-layer pipe jacking construction in the stacked-wire pipe jacking construction, and for simplicity of explanation, components such as a reaction force support, a jacking device, a jacking iron, a pipe piece, and a guide rail in the reaction force support system in upper-layer pipe jacking construction are omitted.
It can be understood that the counterforce support system of the invention sequentially sets the counterforce wall, the back rest and the counterforce support along the pipe jacking direction in the starting well, the counterforce wall is rigidly connected with the two side walls of the starting well, the back rest is rigidly connected with the counterforce wall, the counterforce support is fixedly arranged on the bottom plate laid on the ground of the starting well, one ends of a plurality of jacking devices arranged on the counterforce support are connected with the top iron to push the pipe piece to tunnel, and the other ends of the plurality of jacking devices are abutted against the back rest.
Optionally, the back adopts steel back box, and the straightness that hangs down of steel back box self, with the straightness that hangs down of axis is crucial to jacking work, for guaranteeing the even transmission of power, when steel back box was installed according to actual jacking axis lofting, was installed as steel form and counter-force wall's concrete form together with steel back box, pour concrete counter-force wall to guarantee that steel back box and concrete counter-force wall and originating well wall fully contact, like this, the counter-force that produces in the push pipe jacking can more evenly distributed on the inside lining wall. Wherein, the installation elevation deviation of the steel backrest box is not more than 5mm, and the horizontal deviation is not more than 7mm.
Optionally, the reaction support system further comprises a reaction support, wherein the reaction support is arranged at the rear of the reaction wall and is respectively and rigidly connected with the reaction wall and the side wall of the originating well. Through setting up the counter-force support at the rear of counter-force wall, can effectively strengthen the joint strength between counter-force wall and the well lateral wall that originates, improve the counter-force effect. More preferably, the reaction force struts are provided in a plurality, and the plurality of reaction force struts are provided at uniform intervals along the height direction of the reaction force wall. The section of the counter-force support is rectangular, triangular or trapezoidal.
It will be appreciated that, as shown in fig. 3 and 4, the reaction support includes a plurality of columns arranged in an array, the bottom end of each column is fixedly connected with the bottom plate, each column is connected with the columns adjacent to each other transversely and adjacent to each other longitudinally through a section steel, preferably a shear connection structure is adopted, and the section steel preferably adopts a [ 12-type channel steel. Optionally, triangular steel plates are welded between the four corners of the bottom of the upright post and the bottom plate so as to enhance the connection stability between the upright post and the bottom plate, and the length of the right-angle side of each triangular steel plate is 10cm/20cm. Optionally, the tops of the columns of each row are welded with I-steel, so that a plurality of rows of I-steel are formed, and the tops of the plurality of rows of I-steel are provided with an operation platform. Wherein, square timber is arranged on the tops of the plurality of rows of I-steel and a bottom die is paved to form an operation platform; or, the tops of the rows of I-steel are paved with direct steel plates to form an operation platform. Wherein, the I-steel is preferably 22a I-steel.
Alternatively, the reaction force bracket comprises 8 rows of 7 columns each, 56 columns in total, and the distance between the columns adjacent in the transverse direction and adjacent in the longitudinal direction is 1.5m according to the actual construction size of the originating well. Wherein, the stand adopts the steel pipe stand of phi 609 mm. In other embodiments of the invention, the array arrangement of the reaction brackets may be adaptively adjusted according to the construction size of the originating well.
It will be understood that in the step S2, the pipe jacking device preferably adopts a multi-cutter soil pressure balance pipe jacking machine, and the basic principle is that a motor drives and rotates a cutter disc through a speed reducer arranged on a compartment plate, the cutter disc cuts a tunnel face and carries out soil improvement on the cut soil in a soil bin to form a plastic body mud mass, and the soil pressure and the groundwater pressure are balanced through controlling the soil discharge amount through a spiral soil discharger. The lower part of the push bench is provided with a feeding port of the screw conveyor, and the cut soil body is discharged through the screw conveyor. Because the front shell is separated into a front soil pressure bin and a rear power bin by the compartment plate, groundwater cannot penetrate in, so that the multi-cutter-disc soil pressure balanced pipe jacking machine can carry out pipe jacking construction below a high groundwater level to effectively control ground subsidence. The specification of the multi-cutter-disc soil pressure balance pipe jacking machine can adopt 9.1mX5.5m and 6.9mX4.9m, seven cutter discs are arranged on the machine head of the 9.1mX5.5m pipe jacking machine, wherein the diameter of the large cutter disc is 4200mm, 8 motors with 30 kilowatt are adopted, and the motor rotating speed is 1470r/m; 2. the diameter of each medium cutter disc is 2980mm, 4 motors with 30 kilowatts are adopted, and the rotating speed of the motors is 1470r/m;2 medium cutterheads with the diameter of 2520mm adopt 3 motors with the diameter of 30 kilowatts and the motor rotation speed of 1470r/m; the diameters of the two small cutterheads are 1450mm, 1 motor with 37 kilowatts is adopted, and the motor rotating speed is 1470r/m. Total area of full section 49.968m 2 Total cutting area 41.082m 2 The cutting rate of the whole cutter head is 82.2 percent, and the total stirring area is 37.208m 2 The stirring ratio was 74.4%. And 6.9mX4.9mpipe push bench head totally arranges 6 cutterheads, 1 diameter 2980mm cutterhead, 2 diameter 2800mm cutterhead, 3 diameter 2400mm cutterhead, the front and back staggering arrangement of cutterheads, the front of the diameter 2400mm cutterhead, the rear of the diameter 2800mm and 2980mm cutterhead. The 6 cutterheads are all driven by 3 motors with the speed of 1470r/min, the speed of 0-1.5 r/min and the maximum torque of the cutterhead being 570 KN. All-aroundCross-sectional area 34.808m 2 Total cutting area 31.849m 2 The cutting rate of the whole cutter head is 91.5 percent, and the total stirring area is 29.065m 2 The stirring ratio was 83.5%.
The specific installation process of the rectangular pipe pushing bench comprises the following steps: and installing an originating guide rail on the poured originating well structure bottom plate, wherein the base is required to meet the requirements of an axis and an elevation after being installed, and is firmly fixed. Then, lifting the lower split and the upper split of the front shell of the rectangular pipe jacking machine, lifting the lower split of the front shell according to a lifting point, lifting the front shell to the front end of a foundation pit guide rail base, aligning the center line, lifting the upper split of the front shell according to the lifting point, putting the front shell above the lower split, aligning the center line, adjusting the connection position of the lower split and the upper split, and connecting and fixing the lower split and the upper split through bolts. Then, the rectangular pipe jacking power system sub-components are hoisted underground, are connected with the connecting positions of the front shell power system and are screwed and fixed by bolts. The front and rear shells are connected through a correction oil cylinder after being jacked to the tail end connecting position of the front shell by a small jack, so that two sealing rubber rings are arranged between the front and rear shells for preventing slurry leakage. And then slowly hanging the single screw conveyor into the cavities of the front and rear shells after the single screw conveyor is in the well, hanging the hanging point at the middle lower end of the screw conveyor upside down by using a chain block, manually assisting to slowly convey the screw conveyor into the reserved hole of the mud cabin, and connecting the screw conveyor with the partition board by bolts, and connecting the screw conveyor with the front upper shell by using flat steel after fastening the bolts, thereby playing a supporting role. And then, the cutterhead of the push bench is lifted down to the well for installation in sequence. In addition, the whole push bench is required to be installed and debugged well before leaving the factory, in order to be convenient for transportation, the push bench is split into a plurality of parts to be transported to a construction site, and in order to check whether the machine is abnormal or not in the transportation and hoisting processes, the push bench is required to be debugged again after being lifted into a working well for installation.
Before the pipe jacking machine starts, the reinforcing steel bars on the back soil surface of the bored and poured guard pile in the range of the reserved tunnel portal are required to be broken, the residual reinforcing steel bars are cut off when the pipe jacking machine starts formally until the reinforcing steel bars on the back soil surface are exposed, concrete slag and sundries generated by the tunnel portal are broken in a working well are cleaned, and no residual reinforcing steel bars in the range of the tunnel portal are checked and confirmed. It can be understood that the chiseling operation process of the tunnel portal concrete is specifically as follows:
1) Determining a chiseling range, measuring and paying off, determining the chiseling range of an initial door, wherein the outer contour dimensions of the top pipe are 9100 multiplied by 5500mm and 6900 multiplied by 4900mm, and a building gap of about 15cm is reserved for a water stop ring of the tunnel door, so that the construction of the water stop ring of the tunnel door and the inlet of the top pipe are convenient, and the chiseling area dimensions are 9400 multiplied by 5800mm and 7200 multiplied by 5200mm.
2) The scaffold is erected, a steel pipe scaffold is erected in the hole ring, a 5cm thick wood plate is paved to serve as a pavement plate, so that an operation position of an operator is provided, the scaffold can be a floor type scaffold when a preliminary hole door is chiseled off, so that the chiseling off construction is facilitated, the scaffold is stable and reliable, and when the concrete blocks are finally cut off, the scaffold is an inverted scaffold, and the working height of the operator is ensured to be above the concrete of the cut-off blocks.
3) And observing the soil body reinforcement condition, drilling an observation hole at the center of the tunnel portal by adopting a water drill so as to observe the soil body reinforcement condition outside the tunnel, and then determining whether to supplement and reinforce the soil body according to the exploratory hole and the water seepage condition.
4) And (3) chiseling the guard piles of the tunnel portal, finding out piles encountered when the pipe jacking machine at the reserved tunnel portal is jacked in according to the condition of a construction site, marking the piles numbered 1-7, cleaning the drilled piles from top to bottom at intervals from outside to inside, firstly chiseling the piles numbered 1 and 7, each time chiseling the pile diameter 1/2, about 600mm thick, and carrying out drilling sampling by using a water saw before each chiseling, wherein when weak or water gushing, collapse and other bad geology exist after the piles are found, the piles are timely connected with the design, and the tunnel portal cannot be chiseled before the geology is not reinforced. And (3) chiseling the pile edges of the parts No. 3 and No. 5 to remove bored pile concrete, and cutting out externally leaked pile foundation reinforcements after the deformation condition of the foundation pit enclosure is observed after the pile body of the part No. 1 and No. 7 is chiseled out by 1/2. And repeating the steps by the rest parts, wherein the next layer can be chiseled after each layer is chiseled and cleaned. After all the marked piles are chiseled for 1/2, observing deformation conditions of foundation pit supports, removing the concrete in the residual bored piles from outside to inside at intervals after no abnormality is found, drilling the inner bored piles from top to bottom by using water before chiseling, and repeating the sequence of outer chiseling piles from outside to inside. And finally, trimming and reinforcing the chiseling range.
5) And removing the concrete blocks, wherein the interface concrete blocks need to be cleaned along with the increase of the chiseling quantity in the chiseling process of the tunnel portal, the chiseling smoothness is ensured, the jacking pipe can be pushed in for the second time smoothly, and the chiseled concrete blocks are removed to one side and hung to the ground.
6) And an inspection interface for carrying out omnibearing inspection on the steel ring and the face area after the chiseling is finished, and checking whether factors which invade the working face of the pipe jacking machine to influence the starting exist or not and eliminating the factors.
Optionally, the following contents are further included before the jacking pipe is started to jack:
and installing a curtain cloth rubber plate sealing hole ring on the hole ring of the starting well.
It can be understood that a 15cm building gap exists between the hole ring and the pipe joint, and serious quality safety accidents of external soil and bentonite thixotropic slurry rushing into an originating well are extremely easy to occur in the jacking pipe originating and normal jacking processes, in order to prevent the occurrence of the serious quality safety accidents, a 1-channel curtain cloth rubber plate sealing hole ring is arranged on the hole ring before construction, a 12mm thick steel pressing plate is adopted as a backing for the rubber plate, and bolt holes of the pressing plate are in a waist hole form, so that the jacking process can be regulated at any time along with the position change of the pipe joint, and the sealing performance of the curtain cloth rubber plate is ensured.
It can be understood that in the step S4, the first segment is lifted into the originating well, and the primary jacking construction can be started after the first segment is docked with the rectangular push bench and the top iron. After the jacking of the first pipe segment is completed, the second pipe segment is lifted into the pipe segment for normal jacking construction, and the pipe jacking equipment continuously advances along with continuous access of the pipe segment and moves from the originating well to the receiving end until all the pipe segments are jacked. And in the jacking process of the jacking pipe, bentonite thixotropic slurry is continuously injected between the outer wall of the pipe joint and the soil body, so that on one hand, the effects of lubrication and antifriction can be achieved, and on the other hand, the effects of filling and supporting core soil can be achieved temporarily.
Optionally, before the jack-in is advanced to the beginning, need first install the waterstop in entrance to a cave, its effect is that the positive soil and water of preventing when push bench advances the hole gushes into the working well in, and its another effect is that the drag reduction mud that prevents to push in during the construction runs off from here, guarantees to form complete effective mud cover. In addition, if the starting well is a poor soil layer such as powdery clay, the whole soil body must be improved or reinforced within a certain range from the working well edge in the jacking direction of the jacking pipe, and the soil body in front of the tunnel gate is reinforced by adopting the high-pressure jet grouting piles, so that the water stop of the tunnel gate is achieved, the soil body in front of the tunnel gate is improved in strength, and collapse of the heading machine is prevented when the heading machine is started. In addition, when the notch of the pipe pushing machine enters the area where reinforced soil starts, water injection slows down the jacking speed (the jacking speed is controlled to be 0.5-1 cm/min), the cutting face is lubricated, the front soil pressure of the machine head is reduced, the soil discharge amount is closely paid attention to and adjusted, the soil discharge amount of each section of pipe is ensured to be slightly larger than the theoretical soil discharge amount, and meanwhile a specially assigned person is responsible for observing the deformation condition of the enclosure structure in the range of the tunnel portal so as to ensure the integrity of the pipe pushing machine equipment and the structural stability of the tunnel portal.
Optionally, after the push bench is jacked into the water stop, the push bench continues jacking under measurement and monitoring until the main jacking stroke is enough, and a limiting block is welded at the tail part of the push bench to prevent the push bench from retracting under the action of a soil body on the front surface when the main jacking jack is retracted. And after the main jack is retracted, the hoisting pipe joint is spliced, the limiting block is cut off after the jack is in place, and jacking is continued. After the initiation, the push bench and the transition pipe joint are connected together by the steel plate to form a whole, the stability is increased after the push bench and the transition pipe joint are connected together, the loading of the head due to the overweight front end of the head after the initiation of the push bench is prevented, the push bench is very beneficial to the jacking construction at one stage after the initiation, and meanwhile, the push bench is convenient to control in the subsequent jacking construction.
It can be understood that after the supporting piles in the hole ring are completely broken, the machine head should be immediately jacked, and the jacking speed should be reduced because the front surface is a plain concrete wall with a full section and the cement soil is reinforced by high-pressure rotary spraying to protect the cutter head. In addition, the screw machine may be difficult to unearth, and a proper amount of clean water may be added to soften or lubricate the cement soil if necessary. After the pipe jacking machine enters undisturbed soil, in order to prevent the machine head from 'knocking', the jacking speed is properly improved, so that the front soil pressure is slightly larger than a theoretical calculated value, and disturbance to the front soil body and ground subsidence are reduced.
In addition, because a 15cm gap exists between the pre-buried steel ring of the starting portal and the shell, and no waterproof structure of the portal such as a cord fabric rubber plate of the starting well exists, water and soil loss is easy to cause when the pipe jacking machine head starts, and the upper soil body is easy to subside and the underground pipeline is damaged when the pipe jacking machine head is serious, corresponding measures are necessary to ensure the starting safety of the pipe jacking machine head. Optionally, after the jacking pipe reaches 6m from the starting hole, grouting of the first pipe section (namely grouting bentonite thixotropic slurry) is started, and the grouting position is gradually moved backwards in the process of jacking in the future, so that a complete soil plug of about 6m is formed before the jacking pipe is started, and the sudden rising of friction resistance around the pipe section caused by the great loss of antifriction slurry in the starting process is avoided. When the notch of the push bench enters the hole reinforcing area, the jacking speed is properly slowed down, the soil discharge amount is adjusted, and the soil pressure on the front side of the machine head is gradually reduced, so that the integrity of the push bench equipment and the structural stability of the hole are ensured.
It can be understood that the soil pressure balance type push bench is adopted, soil pressure in a pressure bin is utilized to balance soil on an excavation surface, the aim of supporting the soil on the excavation surface right in front of the push bench is achieved, and ground subsidence is controlled. Therefore, the setting of the balance soil pressure is the key of jacking construction, and in the invention, the soil pressure is calculated by adopting a Rankine pressure theory, and a specific calculation formula is as follows:
P＝k 0 rz+P 1
wherein P represents the lateral soil pressure of the pipe joint, k 0 Represents the lateral coefficient of soil body, z represents the covering depth, P 1 Representing overload coefficient, selecting 20KN/m 2 R represents the soil filling weight.
In addition, along with the continuous jacking, the soil pressure value should be correspondingly adjusted according to other actual jacking parameters and ground subsidence monitoring data.
In addition, in the initial stage of jacking, the jacking speed is not too high, and is generally controlled to be about 5-10 mm/min, and the normal construction stage can be controlled to be about 10-20 mm/min. In the pipe jacking operation process, the mud output in the pipe is consistent with the jacking mud output, the mud output is larger than the jacking mud output, the ground can be settled, the mud output is smaller than the jacking mud output, and the ground can be raisedThe soil around the pipeline is disturbed, only the mud output is controlled to be consistent with the jacking mud output, the soil around the pipeline is not influenced, so that the ground is not influenced, and the key that the mud output is consistent with the mud output is to strictly control the scale mastered by cutting the soil, so that excessive mud output is prevented. Therefore, the soil output is strictly controlled in the jacking process to prevent over-digging or under-digging, and is controlled to 98% -100% of the theoretical soil output under normal conditions, and the theoretical soil output of a 9.1mX5.5 m pipe section is 75m 3 The soil is lifted into a soil collecting pit on the ground by adopting a bucket, and the lubrication slurry is added, so that the actual soil output of a pipe saving is 83-90m 3 Left and right. And the theoretical soil yield of 6.9mX4.9mone pipe section is 51m 3 The soil is lifted to a soil collecting pit on the ground by a bucket, and the lubrication slurry is added, so that the actual soil yield of a pipe saving is 55-60m 3 Left and right.
Optionally, each pipe joint needs to be stuck with a water stop ring and a wood gasket before being installed, and the joint part of the pipe joint and the pipe joint is embedded, so that the pipe joint and the body of the pipe jacking equipment are ensured to be in a concentric and coaxial state. After the pipe joints are connected, the pipe joints should be on the same axis, have no included angle or deflection, and have uniform stress surfaces.
It can be understood that the rectangular pipe jacking machine adopted by the invention has large broken surface size, large self weight of the machine head and 194.23t weight, so that the phenomenon that the machine head enters a hole to plant the head is very easy to occur when the pipe jacking machine enters an undisturbed soil layer and meets the region with poor soil quality. Therefore, in order to prevent the occurrence of the phenomenon, in the jacking process of the jacking pipe, reinforcing piles are arranged in a preset end head range (generally 1-1.5 times of the length of the jacking pipe machine) so as to improve the strength of soil in front, when the machine head of the jacking pipe equipment enters a hole, the machine head and a rear pipe joint are connected by a pull rod so as to form a whole, two chain blocks are tensioned at intervals of one meter on a guide rail, the machine head is enabled to smoothly advance along the guide rail direction, grouting is carried out on a hole, after grouting is finished, an experiment is carried out on a brick joint of the hole, whether water is in a surge state or not is detected, if the water surge occurs, the grouting drainage number is increased until the water surge does not occur, and the tunneling machine head is ensured to smoothly enter the hole.
It can be understood that in the jacking process of the jacking pipe, the jacking axis and the design axis are often deviated, so that deviation correction measures are adopted to reduce the deviation value between the jacking axis and the design axis, and the deviation value tends to be consistent as much as possible. Optionally, in the jacking process of the jacking pipe, a laser beam is shot out from the starting well by utilizing a laser theodolite according to a designed jacking axis, and is shot on a light target in the center of the jacking pipe machine, the deviation of the axis can be observed from a monitor in the jacking process, and when the deviation of the jacking axis and a preset axis is detected, the deviation of the jacking axis is rectified through a plurality of groups of hydraulic cylinders on the jacking pipe machine. The deviation rectifying action is carried out by generating a folding angle through a deviation rectifying hinge on the push bench, the push bench is of a two-section one-hinge structure, and the length-diameter ratio (namely the deviation rectifying sensitivity) of the push bench is L/D=1.08. The correction system consists of 4 50t double-acting cylinders and control valves, wherein 4 groups of cylinders are obliquely and orthogonally arranged at 45 degrees, and each correction cylinder connects the front shell and the rear shell of the pipe-jacking tunneling machine together through a universal hinge, so that the pipe-jacking tunneling machine can randomly perform correction actions within a certain range. The 4 groups of correction oil cylinders are controlled by 4 three-position four-way electromagnetic reversing valves, the front cavity and the rear cavity of each oil cylinder are respectively provided with a balance valve, and when the correction oil pump is closed, the balance valves can close the oil paths of the front cavity and the rear cavity of the oil cylinder, so that the inside of the oil cylinder is always kept at high pressure, and the reliability of correction action is ensured. Therefore, when the jacking axis deviates, the deviation value is gradually reduced and returned to the position of the designed axis by adjusting the expansion and contraction amounts of the plurality of deviation correcting cylinders. The principle of 'duty measurement, duty correction and slow correction' should be implemented in the construction process, and the correction can not be violently performed so as to avoid adverse effects on concrete pipe joints and jacking construction. Wherein, the deviation control requirement of push pipe axis does: elevation +30mm, -50mm; level of: +50mm.
It can be understood that, because the section of the rectangular pipe-jacking tunneling machine is larger, the front end resistance is large, and in practical construction, even if the pipe joint is jacked for a longer distance, the main jacking cylinder is retracted once every time the pipe joint is assembled or a cushion block is added, the machine head and the pipe joint still retract by 20-30 cm together. When the push bench and the pipe joint are retreated, the soil pressure balance between the machine head and the soil in front is destroyed, the soil surface is not stably supported, the soil in front of the machine head is easy to collapse, and the settlement of the road surface and the pipeline is difficult to control without taking certain measures. Therefore, as an optimization, the invention installs a set of stop frame on both sides of the front base (the end of the base near the starting well), the bottom of the stop frame is welded and fixed on the base, the stop frame is provided with a pin hole, when needing to install a wooden cushion block or assemble a pipe joint, a pin is used to insert the pin hole on the stop frame and the hoisting hole of the pipe joint, so as to prevent the pipe joint from backing. The retaining frame is welded together by adopting two channel steels 28#a and is welded together with the base at the same time, and the two channel steels and the base form a triangular structure.
It is understood that bentonite is a clay mineral with potassium, calcium, sodium montmorillonite as the main component (content is generally greater than 65%), has expansibility and thixotropic properties, and the thixotropic properties of bentonite slurry help the jacking pipe joint to become a friction reducer when moving between strata, reduce friction resistance with viscous liquid, and become gel when stationary to support the strata. Wherein, the bentonite thixotropic slurry comprises bentonite, water, sodium carbonate and CMC (powder chemical paste). The thixotropic bentonite slurry is stirred strictly according to the operation regulations, and the slurry is required to have certain viscosity and good fluidity without water loss, precipitation and solidification during construction. Through long-term theoretical analysis and field test, a plurality of evaluation indexes of thixotropic slurry are formulated, including specific gravity, viscosity, PH value and water loss rate, the performance of the thixotropic slurry is comprehensively evaluated based on the indexes, and the optimal proportion is obtained. Wherein, the optimal proportion is: the thixotropic slurry comprises 200Kg bentonite, 850Kg water, 6Kg sodium carbonate and 2.5Kg CMC, and the specific gravity of the thixotropic slurry is 1.1-1.15 g/cm 3 Viscosity of 1-2 s0, pH value of 7, water loss rate of less than 25cm 3 The thixotropic slurry prepared by the method has good fluidity, no water loss, no sediment, no consolidation and certain viscosity, and can play a good role in antifriction and temporary support.
In addition, the grouting pressure and stability of thixotropic slurry can have an influence on the movement of soil, in the normal jacking process, if the grouting pressure is too large, the soil around a pipe joint can be extruded, so that the soil is laterally displaced and raised on the ground, and if the grouting pressure is too small, the slurry cannot smoothly fill the gap between a pipeline and the surrounding soil, a slurry sleeve cannot be formed, and the expected grouting effect cannot be achieved. Meanwhile, the unstable grouting pressure can generate disturbance to the soil body and damage the structure of the soil body, so that sedimentation, especially later consolidation sedimentation, is caused. Therefore, reasonable grouting pressure can enable slurry to be smoothly injected into the outer wall of the pipe section and can not seriously disturb stratum, and preferably, the grouting pressure in actual construction is the soil pressure value (the sum of underground water pressure and dead weight soil pressure) measured at the center cutter head of the large cutter head of the rectangular pipe jacking machine. Furthermore, in order to fill the gap formed during jacking with lubricating slurry in time to form a slurry sleeve, the purposes of reducing friction resistance and ground subsidence are achieved, the principles of pressing along with the jacking, hole-by-hole grouting, full-line slurry supplementing and uniform slurry quantity must be maintained during grouting, and the grouting pressure is controlled to be about 0.3MPa as much as possible. In order to achieve the ideal antifriction grouting effect, 10 grouting holes are uniformly arranged on each pipe joint, grouting holes are timely and effectively tracked during jacking, and the number of grouting supplementing times and grouting amount are determined according to the specific conditions during construction.
Optionally, in the jacking process of the jacking pipe, when a bad soil layer is encountered, mineral modifier is injected into the soil bin of the jacking pipe equipment through a grouting hole arranged on the jacking pipe equipment, so that the plasticity, the fluidity and the water stopping performance of soil in the soil bin are improved. When the soil with good water stopping performance is filled in the shell of the screw conveyor, the underground water cannot be sprayed, and construction safety is guaranteed. In addition, a plurality of stirring rods are welded behind the cutter bar of the pipe pushing machine, and after the mineral modifier is added, the mineral modifier and excavated soil and sand are stirred uniformly through the continuous stirring of the stirring rods, so that the improved soil body has good plasticity, fluidity and water stopping property.
Currently, the modifier materials commonly used are mainly divided into four categories: mineral materials, super absorbent resin materials, fibers, polysaccharides and negative ion materials, surface active materials and silica sol. The invention preferably employs a mineral modifier comprising a bentonite slurry, a foaming agent and a muck, wherein the bentonite slurry is prepared from bentonite and water. During construction, bentonite slurry with the bentonite to water ratio of 1:8 is adopted, the proportion of the dregs to the bentonite slurry and the proportion of the foaming agent of 1:0.08:0.003 are adopted, and the prepared mineral modifier has larger consistence, the C-type viscosimeter value of the mineral modifier is 8000-10000, and the specific gravity of the mineral modifier is 1.30-1.50. Moreover, when the soil with good plasticity and fluidity is filled in the soil bin, the soil pressure in the soil bin is uniform, so that the detected soil pressure is accurate, and the soil pressure in the soil bin can better balance the static soil pressure and the groundwater pressure of the soil layer where the heading machine is positioned, so that the real soil pressure balance can be realized.
It can be understood that in the step S5, the disassembling block of the push bench is basically the same as the installation of the push bench, and the order of disassembling and lifting the push bench after the push bench reaches the receiving end is sequentially a cutter head, an upper front housing split, a lower front housing split, a middle rear housing, a screw conveyor and a power system before being lifted in the housing, and finally lifted out, wherein each lifted-out component comprises an upper front housing split, a lower front housing split, a power system, a middle rear housing, a screw conveyor and the like. And each piece of the pipe jacking machine is immediately loaded after being disassembled, a large hydraulic platform trailer is adopted for transferring, a transportation line is inspected in the field before transportation, in the transportation process, each part is ensured to be fixed and reliable, sufficient protective measures are taken, damage and accidents in the transportation process of the pipe jacking machine are prevented, and the pipe jacking machine is lifted out from an originating well after being conveyed to the originating well along a guide rail from a receiving end. The cast-in-situ concrete is cast by adopting a ground pump, the pump truck is placed in an originating well and is connected to a casting working face through a pump pipe, a lining top plate adopts a steel template, 6 casting holes are reserved on the template, and the casting holes are uniformly distributed. The pouring holes are prefabricated by the steel templates, the concrete guide pipes and the flow stopping butterfly valves, and can be sequentially started when pouring concrete, and the poured concrete is prevented from pouring Kong Daoliu by controlling the opening and closing of the flow stopping butterfly valves.
Optionally, before the pipe pushing bench is disassembled, the soil body of the shell discarding area is reinforced at first so as to achieve the effects of improving the strength of the soil body and sealing water. Specifically, the horizontal sleeve valve pipe is adopted to carry out grouting reinforcement on the soil body of the abandoned shell section according to design requirements, and simultaneously, in order to ensure the reinforcement effect, after the push bench is jacked in place, grouting holes are reserved in the shell to carry out grouting plugging on the gap outside the shell.
In addition, in order to prevent the pavement from sinking and damaging the underground pipeline, corresponding measures must be taken during the receiving construction, so that the pipe jacking machine head smoothly reaches the receiving end. Specifically, when the jacking pipe reaches 6m from the receiving end, the grouting of the first pipe section is started to stop, the grouting position is gradually moved backwards in the jacking process, a complete soil plug of about 6m is formed before the jacking pipe is received, the phenomenon that friction resistance around the pipe section suddenly rises due to a large amount of loss of antifriction slurry in the receiving process is avoided, in addition, when the notch of the push bench enters the reinforcing area of the hole of the receiving end, the jacking speed is properly slowed down, the soil discharge amount is adjusted, the soil pressure in the front face of the machine head is gradually reduced, and the integrity of the push bench equipment and the structural stability of the hole are ensured.
In addition, after jacking of the jacking pipe is finished, gaps among pipe joints are required to be filled with the bi-component polysulfide sealant. Before caulking, impurities and greasy dirt in the gaps must be cleaned up, the prepared polysulfide paste is leveled, cleaned and dried, the two sides of the gaps are firstly scraped and coated once, the sealing paste is scraped and filled in the gaps to the required height for the second time, and the gaps are compacted and leveled, so that the influence of air bubbles on the strength and the water tightness is prevented. The surface drying time of the sealing paste is 24 hours, 80% strength is achieved after 7 days, and the sealing paste needs to be carefully protected before being fully cured to prevent water immersion.
It can be understood that after jacking construction of the jacking pipe is completed, bentonite thixotropic slurry is filled between the pipe joint and the soil body, and the thixotropic slurry can play a role in temporarily supporting core soil, but cannot be effectively supported for a long time, and the core soil cannot be solidified. Therefore, in order to reduce soil settlement and strengthen the overall waterproof performance of the pipe jacking channel, after the pipe jacking machine is pushed in place, arc-shaped steel plates are used for welding and plugging, gaps between the holes at two ends of the channel and the pipe joint/shell are plugged, cement slurry is injected between the outer wall of the pipe joint and the soil body to replace bentonite thixotropic slurry, and core soil is solidified. After the cement paste is coagulated (generally more than 24 hours), the grouting pipeline can be dismantled, and a blank cap is replaced to seal the grouting hole. The concrete grouting process is as follows: after the original grouting pump is cleaned, the grouting barrel is connected, the grouting pump is started, the grouting hydraulic grouting is sequentially and odd-numbered section grouting is sequentially carried out from the bottom of a pipe section according to the sequence of the pipe sections, then the even-numbered section grouting is carried out from the tail of a pipe jacking channel to the front, after the bottom grouting is completed, the middle part of the pipe section is sequentially pressed according to the sequence, finally the top of the pipe section is circulated until the completion, all valves are closed again, the pressure is maintained for ten minutes, and the grouting pressure is 0.2Mpa during the pressure maintaining. It can be understood that by adopting the multipoint circulation directional grouting scheme with balanced pressure, the grouting process takes the quantity control as the main part and the pressure control as the auxiliary part, and the final hole grouting effect is used for evaluating and controlling grouting end conditions, so that the core soil consolidation effect is ensured to meet the strength requirement.
It can be understood that the consolidation strength of core soil can influence the top pipe posture control in the upper layer top pipe construction in the stacked wire top pipe construction, when the consolidation strength of core soil is not up to 0.2MPa, the existing lower top pipe piece is easily damaged by the top pipe machine planting head, and when the consolidation strength of core soil exceeds 2MPa, the ground collapse caused by the over-digging after the top pipe machine is lifted easily occurs. Therefore, how to select the component proportions of the cement slurry to control the consolidation strength of the core soil within the target range is important. Preferably, cement, fly ash, an expanding agent and water are selected as preferable combined materials for preparing cement paste, and the optimal proportion is as follows: each cubic meter of cement slurry comprises 300Kg of cement, 420Kg of fly ash, 64Kg of expanding agent and 660L of water, and the prepared cement slurry has the following performance indexes: the specific gravity is 1.45, the viscosity is 10-11 cm, the water seepage rate is less than 3%, and the expansion rate is 2-3%.
Optionally, after the jacking of all pipe joints is finished, post-pouring Liang Duiguan joints are applied to the top plate and the bottom plate of the starting hole to limit, so that the pipe joints are prevented from being displaced. However, the post-cast beam is a waterproof weak point, so that waterproof measures are also required, specifically: and embedding a blocking steel ring in the post-cast beam, filling gaps between the pipe joint and the enclosure structure and between the post-cast beam and the post-cast beam by injecting cement, and arranging water-swelling rubber strips at construction joints of the post-cast beam and the enclosure structure, the post-cast beam and the embedded blocking steel ring and the enclosure structure.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (1)
1. The construction method of the stacked wire jacking pipe is characterized by comprising the following steps of:
after finishing three-way and one-level construction on the construction site, carrying out construction operation of the originating well;
a pipe jacking device is installed in the starting well;
performing hole concrete chiseling operation;
hanging the pipe piece into an originating well, butting the pipe piece with a counter-force support system in the pipe jacking equipment and the originating well, performing pipe jacking construction operation, and injecting bentonite thixotropic slurry between the outer wall of the pipe joint and a soil body in the pipe jacking process; in the jacking process of the pipe jacking, a laser beam is shot out of an originating well according to a designed jacking axis by utilizing a laser theodolite and is shot on a light target in the center of the pipe jacking machine, the deviation of the axis can be observed from a monitor in the jacking process, and when the deviation of the jacking axis and a preset axis is detected, the deviation of the jacking axis is rectified through a plurality of groups of hydraulic cylinders on the pipe jacking equipment;
Removing the abandoned shell of the pipe jacking equipment after jacking of all pipe joints is finished, pouring a concrete structure in the abandoned shell of the pipe jacking equipment, and pouring cement slurry between the outer wall of the pipe joints and soil mass to replace bentonite thixotropic slurry;
the construction operation of the originating well comprises construction of maintenance structures in two working wells and establishment of a counter-force support system in the originating well, wherein the counter-force support system comprises a counter-force wall, a back rest, a bottom plate, a counter-force support and a counter-force support, the bottom plate is paved on the ground of the originating well, the counter-force wall, the back rest and the counter-force support are sequentially arranged along the pipe jacking direction, the counter-force wall is rigidly connected with two side walls of the originating well, the back rest is rigidly connected with the counter-force wall, the counter-force support is fixedly arranged on the bottom plate, a plurality of jacking devices are arranged on the counter-force support, one ends of the jacking devices are used for pushing tunneling pipe pieces, the other ends of the jacking devices are abutted against the back rest, and the counter-force supports are uniformly arranged behind the counter-force wall at intervals along the height direction of the counter-force wall and are rigidly connected with the side walls of the originating well respectively;
before the pipe joint is installed, a water stop ring and a wood gasket are required to be adhered to each pipe joint, the joint part of the pipe joint and the pipe joint is embedded, and the pipe joint and a machine body of the pipe jacking equipment are ensured to be in a concentric and coaxial state;
The bentonite thixotropic slurry comprises the components of bentonite, water, sodium carbonate and CMC, wherein each cubic meter of bentonite thixotropic slurry comprises 200Kg of bentonite, 850Kg of water, 6Kg of sodium carbonate and 2.5Kg of CMC;
the cement paste comprises the components of cement, fly ash, an expanding agent and water, wherein each cubic meter of cement paste comprises 300Kg of cement, 420Kg of fly ash, 64Kg of expanding agent and 660L of water;
in the jacking process of the pipe jacking, a reinforcing pile is arranged in a preset range of the end head to improve the strength of a soil body in front, when a machine head of the pipe jacking equipment enters a hole, the machine head and a pipe joint at the back are connected by a pull rod to form a whole, two chain blocks are used for tensioning at intervals of one meter on a guide rail, so that the machine head smoothly advances along the guide rail direction, grouting is carried out on a hole, after grouting is finished, an experiment is carried out on a hole drilled at a brick joint of the hole, whether water is gushed out or not is detected, if the water gush occurs, the grouting drainage number is increased, and the tunneling machine head is ensured to smoothly enter the hole until the water gush does not occur;
before jacking pipe jacking starting jacking, installing a curtain cloth rubber plate sealing moving ring on a hole ring of a starting well;
the grouting pressure of the thixotropic bentonite slurry is the soil pressure value measured at the center cutter head of the large cutter head of the pipe jacking equipment;
A set of stop frames are respectively arranged on two sides of the front base, the bottoms of the stop frames are welded and fixed on the base, pin holes are formed in the stop frames, and when a wood cushion block is required to be additionally arranged or a pipe joint is required to be assembled, a pin is inserted into the small holes in the stop frames and the hoisting holes of the pipe joint to prevent the pipe joint from retreating;
in the jacking process of the jacking pipe, when a bad soil layer is encountered, mineral modifier is injected into a soil bin of the jacking pipe equipment through a grouting hole arranged on the jacking pipe equipment so as to improve the plasticity, the fluidity and the water stopping performance of soil in the soil bin;
after the jacking of all pipe joints is finished, post-pouring Liang Duiguan joints are applied to the top plate and the bottom plate of the starting hole to limit the pipe joints, so that the pipe joints are prevented from being displaced, plugging steel rings are pre-buried in post-pouring beams, cement is injected to fill gaps between the pipe joints and the enclosure structure as well as between the post-pouring beams and the post-pouring structure, and water-swelling rubber strips are arranged at construction joints of the post-pouring beams and the enclosure structure, between the post-pouring beams and the pre-buried plugging steel rings, and between the pre-buried plugging steel rings and the enclosure structure.
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