CN110792085A

CN110792085A - Pipe-jacking working pit supporting method

Info

Publication number: CN110792085A
Application number: CN201910941470.0A
Authority: CN
Inventors: 余波
Original assignee: Chengdu Municipal Engineering And Research Design Institute
Current assignee: Chengdu Municipal Engineering And Research Design Institute
Priority date: 2019-09-30
Filing date: 2019-09-30
Publication date: 2020-02-14

Abstract

The invention relates to a pipe-jacking working pit supporting method, which comprises the following steps: firstly, construction preparation, namely, carrying out site leveling according to a designed elevation, carrying out lofting of a cast-in-place pile and constructing around a working pit to form an annular row pile; constructing a high-pressure injection water-stopping pile between two adjacent cast-in-place piles according to the geological and underground water distribution conditions, so that the high-pressure injection water-stopping pile is meshed with the cast-in-place piles to form a closed water-stopping curtain; step three, excavating earthwork in the working pit layer by layer, performing ring beam construction after the excavation reaches the design elevation of each layer, excavating the next layer of earthwork after the ring beam construction of each layer reaches the design strength, and excavating to the bottom of the working pit; and fourthly, grouting and reinforcing the ground of the top pipe entrance to form an entrance lining wall, reserving the position of the top pipe entrance, constructing a cushion layer and a rear seat wall, installing a top pipe device, and completing construction of the working pit. The invention has the advantages of reliable structure and convenient pipe jacking construction.

Description

Pipe-jacking working pit supporting method

Technical Field

The invention relates to the technical field of foundation pit supporting, in particular to a pipe-jacking working pit supporting method.

Background

At present, in municipal engineering, the construction of rainwater pipelines or sewage pipelines is generally carried out by adopting a pipe jacking method. The jacking and burying of the pipeline need the shaft to provide a working space, namely a working pit, and under the condition of site space limitation, the working pit needs to take supporting measures to ensure the earth excavation of the shaft and the safety of later-stage pipeline construction.

In the prior art, the support form of the working pit at the present stage is mainly determined by a pipe jacking process and site geological conditions. For the adoption of the excavation type pipe jacking process, equipment in a pit is simple, the requirement on the clearance size of the jacking pit is not strict, and the requirement only needs to be met for pipeline hoisting and arrangement and jacking of a jack, so that the clearance size is small, and a rectangular jacking pit is mostly adopted. For the mechanical pipe jacking process, because the front end of the pipe jacking adopts automatic tunneling equipment, the hoisting of the equipment and the embedding of an auxiliary pipeline need larger working space in the initial installation stage, which has higher requirements on a supporting structure.

Particularly, in the working pits in urban environment, the number of surrounding structures is large, the underground condition is complex, and for the ultra-deep working pits, a cast-in-place pile and inner support structure system is adopted, although the support is reliable, the operation space is narrow due to the influence of the inner support system, and the requirement of the hoisting space for mechanical pipe jacking equipment and pipeline installation is not facilitated.

Disclosure of Invention

The invention aims to provide a pipe-jacking working pit supporting method which has the advantages of reliable structure and convenience in pipe-jacking construction.

The above object of the present invention is achieved by the following technical solutions:

a pipe-jacking working pit supporting method comprises the following steps:

firstly, construction preparation, namely, carrying out site leveling according to a designed elevation, carrying out lofting of a cast-in-place pile and constructing around a working pit to form an annular row pile;

constructing a high-pressure injection water-stopping pile between two adjacent cast-in-place piles according to the geological and underground water distribution conditions, so that the high-pressure injection water-stopping pile is meshed with the cast-in-place piles to form a closed water-stopping curtain;

step three, excavating earthwork in the working pit layer by layer, performing ring beam construction after the excavation reaches the design elevation of each layer, excavating the next layer of earthwork after the ring beam construction of each layer reaches the design strength, and excavating to the bottom of the working pit;

and fourthly, grouting and reinforcing the ground of the top pipe entrance to form an entrance lining wall, reserving the position of the top pipe entrance, constructing a cushion layer and a rear seat wall, installing a top pipe device, and completing construction of the working pit.

By implementing the technical scheme, the high-pressure jet water stop pile is meshed with the cast-in-place pile to form a closed water stop curtain, the cross section of the water stop curtain is circular, the structural reliability is high, the adaptability to site geology is better, the water stop curtain is suitable for supporting an ultra-deep working pit, and the influence on structures around the working pit is controllable due to small displacement of a supporting structure; meanwhile, the large-span ring beam is adopted for supporting, the clearance size of the working pit is large, the size can be flexibly adjusted during design according to the hoisting requirement of mechanical pipe jacking equipment and the size of a pipe joint of a pipeline to be buried, and pipe jacking construction is facilitated; in addition, the supporting structure fully utilizes the characteristic that the circular ring beam has high bearing capacity under pressure, and can achieve better supporting effect with less supporting members under the ground of the same type of fields, thereby being beneficial to reducing the construction investment.

The method is further set in the step one, the reinforcement cage placed in the pile hole of the cast-in-place pile comprises a reinforcement and a glass fiber reinforcement convenient for construction of the entrance hole of the jacking pipe, and the glass fiber reinforcement is placed in the pile hole of the cast-in-place pile and placed to the jacking pipe construction position of the working pit.

By implementing the technical scheme, the cast-in-place pile in the opening range needs to be broken in the construction process of the top pipe opening, the traditional method firstly breaks concrete and then cuts and removes the steel bars in the cast-in-place pile, not only is the construction efficiency low, but also the broken steel bars are mostly irregular steel bars, thereby increasing the construction difficulty of manually cutting the steel bars and increasing the potential safety hazard of construction operation, all longitudinal bars, stirrups and reinforcing bars in the cast-in-place pile in the opening range of the top pipe construction are replaced by glass fiber bars, and compared with the common steel bars, the glass fiber has the characteristics of light weight, high tensile strength, high static shearing force, strong corrosion resistance, low elastic modulus and the like, thereby not only ensuring the structural strength of the supporting structure of the working pit, but also being convenient for removing the glass fiber bars in the later-stage top pipe position during the opening construction, and improving the working efficiency, the construction period is saved.

The invention is further arranged in that the glass fiber reinforcement and the steel bar are connected through a U-shaped bolt.

According to the technical scheme, the longitudinal tensile glass fiber reinforcement and the steel bar are fixed in a lap joint mode through the U-shaped bolts, and the glass fiber reinforcement and the steel bar are convenient to connect and fix in the process of manufacturing the steel bar cage.

The method is further characterized in that in the third step, before the earthwork excavation is carried out on the working pit, an annular crown beam is poured on the top of the waterproof curtain, and after the crown beam reaches the design strength, the earthwork excavation in the working pit is carried out.

According to the technical scheme, the top of the waterproof curtain is supported with the formwork and poured to form the crown beam, the waterproof curtain formed by the cast-in-place pile and the high-pressure jet waterproof pile forms an integrally stressed supporting system through the crown beam, and the supporting system can support the working pit under the condition that the surrounding environment of the working pit is complex.

The invention is further set in the fourth step, firstly, a drilling machine is used for forming holes, then sleeve valve pipes are buried and grouted, then pipes are pulled out, and the opening of the cement mortar is backfilled to form the lining wall of the cave opening.

According to the technical scheme, the holes are formed through the geological drilling machine, the PVC sleeve valve pipes can be inserted after the drilled holes reach the designed depth, full-hole one-time grouting is conducted through the PVC sleeve valve pipes, and finally cement mortar is adopted for sealing and backfilling so as to enhance the stability of the soil body during jacking.

The invention is further provided that a circle of first annular drainage ditch is arranged outside the working pit.

Implement above-mentioned technical scheme, through being provided with first annular escape canal, carry out precipitation to near the surface water of work hole, reduce simultaneously around the rainwater enter into the work hole in.

The invention is further provided that a circle of second annular drainage ditch is arranged at the bottom of the working pit, and the second annular drainage ditch is communicated with a water collecting pit at the bottom of the working pit.

Implement above-mentioned technical scheme, through be provided with round second annular escape canal in the work hole, to carrying out precipitation in the work hole, the rivers of second annular escape canal flow into the sump pit, take the sump pit to pump drainage measure and carry out precipitation in to the work hole.

The invention is further arranged in the third step that the vertical distance between the adjacent ring beams in the working pit is 4 m.

By implementing the technical scheme, the vertical distance between two adjacent ring beams in the working pit is 4m, the vertical distance between two adjacent vertical ring beams is large, the earthwork excavation in the working pit is facilitated, the working procedure is staggered and single, and the construction period is saved.

The invention is further provided that in the third step, the ring beam is connected with the waterproof curtain through the dowel bars.

According to the technical scheme, when the ring beam formwork is poured, the ring beam formwork is connected with the waterproof curtain through the inserted bars, the ring beam and the waterproof curtain are convenient to form a whole, and the filled concrete in the ring beam is prevented from falling.

In conclusion, the invention has the following beneficial effects:

the method comprises the following steps that firstly, a sealed waterproof curtain is formed by meshing a high-pressure injection waterproof pile and a cast-in-place pile, the cross section of the waterproof curtain is circular, the structural reliability is high, the adaptability to site geology is good, the waterproof curtain is suitable for supporting an ultra-deep working pit, and the influence on structures around the working pit is controllable due to small displacement of a supporting structure; meanwhile, the large-span ring beam is adopted for supporting, the clearance size of the working pit is large, the size can be flexibly adjusted during design according to the hoisting requirement of mechanical pipe jacking equipment and the size of a pipe joint of a pipeline to be buried, and pipe jacking construction is facilitated; in addition, the supporting structure fully utilizes the characteristic that the circular ring beam has high bearing capacity under pressure, and can achieve better supporting effect with less supporting members under the similar fields, thereby being beneficial to reducing the construction investment;

secondly, in the process of opening construction of pipe-jacking construction, the cast-in-place pile in the opening range needs to be broken, after concrete is firstly broken in the traditional mode, reinforcing steel bars in the cast-in-place pile need to be cut and removed, not only the construction efficiency is low, but also the broken reinforcing steel bars are mostly irregular reinforcing steel bars, the construction difficulty of manually cutting the reinforcing steel bars is increased, and the potential safety hazard of construction operation is also increased, all longitudinal bars, stirrups and reinforcing steel bars in the cast-in-place pile in the pipe-jacking construction opening range are replaced by glass fiber bars, compared with the common reinforcing steel bars, the glass fiber has the characteristics of light weight, high tensile strength, high static shearing force, strong corrosion resistance, low elastic modulus and the like, the structural strength of the supporting structure of the working pit is ensured, the glass fiber bars can be removed when the opening construction is carried out at the later-stage pipe-jacking position, and the working efficiency is improved, the construction period is saved.

Drawings

FIG. 1 is a cross-sectional view of a working pit according to an embodiment of the present invention;

FIG. 2 is a plan view of a working pit according to an embodiment of the present invention;

fig. 3 is a schematic structural view of a reinforcement cage according to an embodiment of the present invention.

Reference numerals: 1. filling piles; 2. a working pit; 3. high-pressure jet water-stopping piles; 4. a ring beam; 5. the jacking pipe enters the hole; 6. lining walls in the hole; 7. a cushion layer; 8. a rear seat wall; 9. a reinforcement cage; 91. reinforcing steel bars; 92. a glass fiber rib; 10. a U-shaped bolt; 11. a crown beam; 12. a first annular drain ditch; 13. a second annular drain ditch; 14. a water collecting pit.

Detailed Description

The technical solutions of the embodiments of the present invention will be described below with reference to the accompanying drawings.

Examples

With reference to fig. 1 and 2, the working pit supporting structure for pipe-jacking construction includes a cast-in-place pile 1, a high-pressure jet water-stop pile 3, a ring beam 4 and a crown beam 11. Bored concrete pile 1 encircles work pit 2 and separates the stake construction, forms annular pile row to the high-pressure injection stagnant water stake 3 of construction between two adjacent bored concrete piles 1, high-pressure injection stagnant water stake 3 and bored concrete pile 1 interlock mutually form confined stagnant water curtain. Meanwhile, the annular crown beam 11 is poured on the top of the waterproof curtain through a supporting die. And excavating earthwork in the pit 2 of the working pit in a layered manner, after the excavation reaches the design elevation of each layer, constructing a ring beam 4 through a formwork, and pouring the ring beam 4 and a waterproof curtain together through a joint bar.

As shown in figure 1, grouting and reinforcing the ground at the position of the top pipe entrance hole 5 in the working pit 2 to form an entrance lining wall 6, and constructing and forming a cushion layer 7 and a rear seat wall 8 which are convenient for construction of jacking equipment in the working pit 2. A circle of first annular drainage ditches 12 surrounding the working pit 2 are dug on the ground outside the working pit 2, a circle of second annular drainage ditches 13 are dug at the bottom of the working pit 2, the second annular drainage ditches 13 are communicated with a water collecting pit 14 in the bottom of the working pit 2, and a constructor can pump underground water collected in the water collecting pit 14 out of the working pit 2 through pumping and draining equipment.

As shown in fig. 3, the reinforcement cage 9 lowered into the pile hole of the cast-in-place pile 1 is made of reinforcement bars 91 and glass fiber reinforcement 92, and the glass fiber reinforcement 92 is lowered into the pile hole of the cast-in-place pile 1 to the pipe-jacking construction position of the working pit 2. In the manufacturing process of the reinforcement cage 9, the original reinforcement 91 is replaced by the glass fiber reinforcement 92 at the part of the cast-in-place pile 1, which needs to be removed from the top pipe entrance 5. When the reinforcement cage 9 is manufactured, the glass fiber reinforcement 92 and the glass fiber reinforcement 92 are longitudinally tensioned, the glass fiber reinforcement 92 and the reinforcement 91 are connected by the U-shaped bolt 10, and the connection of other parts is firmly bound by iron wires or nylon ropes. Inside the muscle cage of glass fiber muscle 92 should adopt the 92 trusses of glass fiber muscle or the removable reinforcing bar 91 trusses in later stage, increase the 92 muscle cage rigidity of glass fiber muscle, avoid the muscle cage of glass fiber muscle 92 to appear too big deformation in hoist and mount and transportation, guarantee reinforcing cage 9 transportation process safety.

The embodiment also discloses a pipe-jacking working pit supporting method, which comprises the following steps:

firstly, construction preparation, namely arranging safety guardrails on the periphery of a foundation pit according to the actual situation of the site, adopting an investigation report suggested value for the stratum parameters of a working pit 2, and adopting a circular working pit 2 with a net diameter of 10m as a top pit according to the plane arrangement and hoisting requirements of a pipe jacking machine; a circle of first annular drainage ditches 12 are dug outside the working pit 2 for precipitation and drainage, water level observation points are arranged, and the underground water level is dynamically observed;

step two, constructing a cast-in-place pile 1, leveling a field according to a designed elevation, measuring a pile position by using a total station, making a mark, and measuring and releasing pile protection points around the center of the pile position to serve as a pile position control point and a check point in drilling construction; embedding a pile casing, positioning the pile casing by adopting a cross method, then drilling a pile hole of the cast-in-place pile 1 by using a drilling machine, protecting the wall by using slurry in the drilling process, and checking the hole depth, the aperture, the hole position and the like after the drilling hole reaches the designed depth; all longitudinal bars, stirrups and reinforcing bars of the cast-in-place pile 1 are made of glass fiber bars 92 within the range of opening of the top pipe entrance 5, when the reinforcement cage 9 is manufactured, the longitudinal tensile glass fiber bars 92 are connected with the glass fiber bars 92, the glass fiber bars 92 are connected with the reinforcement bars 91 by U-shaped bolts 10, the connection of other parts is firmly bound by 10 # iron wires or nylon ropes, and then a glass fiber truss is arranged inside the reinforcement cage 9 as an auxiliary measure for hoisting the glass fiber bars 92; before the steel reinforcement cage 9 is placed in place, the sediment at the bottom of a hole is required to be removed, the sediment at the bottom of a pile is not more than 100mm, the steel reinforcement cage 9 is immediately hung after hole cleaning is finished, glass fiber reinforcements 92 of the steel reinforcement cage 9 are hoisted to the range of the opening of the top pipe entrance 5 along the pile hole, concrete with the strength grade of C40 is poured, and a tandem method underwater pouring process is adopted; the cast-in-place pile 1 is constructed by adopting a pile separation method, and after concrete of adjacent piles reaches 70% of design strength, hole forming construction is carried out; the designed elevation of the steel reinforcement cage 9 exposed out of the bottom of the crown beam 11 is not less than 35d, and the pouring elevation is increased by 500mm compared with the designed elevation; after the construction of the cast-in-place pile 1 is finished, a construction unit entrusts a unit with special detection qualification to carry out pile body integrity detection;

thirdly, constructing the high-pressure jet water-stopping piles 3 between two adjacent cast-in-place piles 1, and adopting a hole-separating and sequencing mode, wherein the interval time of adjacent hole grouting is not shorter than 24 hours, so that the high-pressure jet water-stopping piles 3 are meshed with the cast-in-place piles 1 to form a closed water-stopping curtain; the diameter of a designed consolidation body is 800mm, the water cement ratio of cement paste is 1:1, water glass determined by tests can be doped during construction, and the diameter of the bottom consolidation body is increased by adopting a re-spraying process due to the fact that a waterproof curtain is deeper; when the high-pressure jet water-stopping pile 3 is constructed and set out, the pile position coordinates, various elevation data, the distance between the pile position and the contour line and the like are carefully checked, so that the accuracy is ensured; the pile position deviation is not more than 50 mm; the perpendicularity deviation of the pile body is not more than 1%; deviation of the central line of the pile position: the thickness is not more than 50mm along the vertical axis direction and not more than 150 mm along the axis direction; pile diameter tolerance error: +/-50 mm; pile top elevation error: less than 50 mm; hole depth error: +300 mm; the cleaning of the deficient soil at the hole bottom is more thorough, and the thickness of the deficient soil at the hole bottom is not more than 200 mm because the high-pressure jet water stop pile 3 is a horizontal force resistant pile; when the construction drilling is carried out, geological bedding surface records are required to be made, if the geological condition is found to be greatly different from drilling data, the geological condition is required to be timely connected with a design unit for coordination treatment; after the construction of the high-pressure jet water-stopping pile 3 is completed, a construction unit entrusts a unit with special detection qualification to perform pile body integrity detection on all the high-pressure jet water-stopping piles 3;

pouring a crown beam 11 on the top of the waterproof curtain through a formwork, wherein the plane of the crown beam 11 is a closed circle, the section of the crown beam is a rectangle, and the size of the crown beam is determined by calculation; before the crown beam 11 is poured, residues, floating soil and accumulated water on the top of the waterproof curtain need to be cleaned, and chiseled and cleaned to the designed elevation; pouring the concrete strength grade C40 of the crown beam 11, wherein the thickness of the protective layer of the steel bar 91 of the crown beam 11 is 50 mm; the crown beam 11 is poured once, and when construction joints need to be reserved due to special reasons, the construction joints need to be processed according to the standard requirements; the main rib of the crown beam 11 is welded in a single-side lap joint mode, the lap joint welding length is larger than 10d, and when double-side welding is adopted, the lap joint welding length is larger than 5 d; the allowable deviation of the elevation of the crown beam 11 is 20mm, and the allowable deviation of the diameter of the crown beam in any direction is 50 mm;

fifthly, after the crown beam 11 reaches the design strength, carrying out in-pit earthwork excavation, wherein the earthwork excavation needs to be carried out in a layered balanced and symmetrical manner, and carrying out net spraying on soil between piles; the layered excavation height is 0.5m below the support design elevation of the next ring beam 4, after the design elevation of each layer is reached, the construction of the ring beam 4 is carried out through a formwork, the plane of the ring beam 4 is a closed circle, the cross section is a rectangle, the size of the ring beam is determined through calculation, and the adjacent ring beams 4 are vertically spaced by 4m in the working pit 2; pouring the concrete strength grade C40 of the ring beam 4, and the thickness of the protective layer of the steel bar 91 of the ring beam 4 is 35 mm; the ring beam 4 is poured once, when a construction joint needs to be reserved due to special reasons, the construction joint needs to be processed according to the standard requirement, the construction and the removal of the ring beam 4 are consistent with the design working condition, and the principle of firstly supporting and then digging needs to be followed; the main rib of the ring beam 4 adopts single-side lap welding, and the length of the lap welding is more than 10 d; when double-sided welding is adopted, the lap welding length is more than 5 d; the contact part of the ring beam 4 and the waterproof curtain is cleaned of soil impurities and roughened, the gap between the ring beam 4 and the waterproof curtain is filled with plain concrete, in order to prevent the filled concrete from falling, the ring beam 4 can be connected with the waterproof curtain through an inserted bar during formwork erection, and redundant anti-falling measures are adopted for the ring beam 4; the allowable deviation of the elevation of the ring beam 4 is 20mm, and the allowable deviation of the diameter in any direction is 50 mm; when the earthwork is excavated, the water in the pit should be synchronously lowered, the water level in the pit is ensured to be lower than the excavation elevation of each layer by 0.5m, and the next layer of earthwork is excavated after the ring beam 4 of each layer reaches the design strength;

after the working pit 2 is dug to the bottom, a circle of second annular drainage ditch 13 is dug at the bottom of the working pit 2, the second annular drainage ditch 13 is communicated with a water collecting pit 14 in the bottom of the working pit 2, and water in the water collecting pit 14 is pumped out of the working pit 2 through pumping equipment, so that the designed reduced water level of the working pit 2 is 0.5m below the bottom of the working pit 2;

seventhly, constructing a lining wall 6, a cushion layer 7 and a rear seat wall 8 in the cave in the working pit 2; grouting and reinforcing the ground of the lining wall 6 at the opening of the cave, rechecking the water cement ratio, grouting pressure, grouting amount and effective grouting reinforcing range through a field grouting test before construction, and correcting the design; when grouting and reinforcing the ground of the lining wall 6 in the opening of the hole, adopting a geological drilling machine to form the hole, wherein the diameter of the drilled hole is not more than 100mm, carrying out drilling machine positioning according to the designed plane coordinate position, requiring that a drill bit is aligned to the center of the hole site, and simultaneously, the plane of the drilling machine is stably placed, the allowable deviation of the horizontal drilling position is +/-50 mm, and the allowable deviation of the verticality is +/-1%; when the drill hole reaches the designed depth, the 50 type PVC sleeve valve pipe can be inserted; then, full-hole one-time grouting is carried out through a 50-type PVC sleeve valve pipe, the grouting flow is measured to be (7-10) L/min, the grouting should be continuously carried out, the interruption time interval is not less than the initial setting time of the grout due to reasons, the grouting amount can be finished when the grouting amount reaches the designed grouting amount or the final hole grouting pressure, and the grouting should skip the hole interval and sequentially grouting from the periphery to the middle; finally, sealing, backfilling and sealing holes by using cement mortar;

step eight, reserving the position of a top pipe hole entrance 5 when the hole entrance lining wall 6 is constructed, marking the cast-in-place pile 1 needing to be broken within the range of the top pipe hole entrance 5 after the strength of the hole entrance lining wall 6 meets the design requirement, and then breaking the concrete and the glass fiber ribs 92 of the cast-in-place pile 1 by adopting a breaking hammer or blasting breaking, thereby completing the construction of the top pipe hole entrance 5; and then, the pipe jacking equipment is installed to complete the construction of the working pit 2.

The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the invention are covered by the protection scope of the invention.

Claims

1. A pipe-jacking working pit supporting method is characterized by comprising the following steps:

firstly, construction preparation, namely, carrying out site leveling according to a designed elevation, carrying out lofting of a cast-in-place pile (1) and constructing around a working pit (2) at intervals to form an annular row pile;

constructing a high-pressure injection water-stopping pile (3) between two adjacent cast-in-place piles (1) according to geological and underground water distribution conditions, so that the high-pressure injection water-stopping pile (3) is meshed with the cast-in-place piles (1) to form a closed water-stopping curtain;

step three, excavating earthwork in the working pit (2) layer by layer, constructing a ring beam (4) after the excavation reaches the design elevation of each layer, excavating the next layer of earthwork after the construction of each layer of ring beam (4) reaches the design strength, and excavating to the bottom of the working pit (2);

and fourthly, grouting and reinforcing the ground of the top pipe entrance (5) to form an entrance lining wall (6), reserving the position of the top pipe entrance (5), constructing a cushion layer (7) and a rear seat wall (8), installing a pipe jacking device, and completing construction of the working pit (2).

2. A pipe-jacking working pit supporting method according to claim 1, wherein in the first step, the reinforcement cage (9) which is lowered in the pile hole of the cast-in-place pile (1) comprises a reinforcement (91) and a glass fiber reinforcement (92) which is convenient for construction of the pipe-jacking entrance hole (5), and the glass fiber reinforcement (92) is lowered in the pile hole of the cast-in-place pile (1) to the pipe-jacking construction position of the working pit (2).

3. A pipe jacking working pit supporting method according to claim 2, wherein said glass fiber reinforcement (92) and said steel reinforcement (91) are connected by U-bolt (10).

4. A pipe-jacking working pit supporting method according to claim 1, wherein in the third step, before earth excavation is performed in the working pit (2), an annular crown beam (11) is poured on the top of the waterproof curtain, and after the crown beam (11) reaches the designed strength, earth excavation is performed in the working pit (2).

5. The pipe-jacking working pit supporting method according to claim 1, wherein in the fourth step, a hole is formed by a drilling machine, sleeve valve pipes are buried and grouted, pipes are pulled out, and the lining wall (6) of the hole is formed by backfilling the cement mortar with an opening.

6. A push pipe work pit supporting method according to claim 1, characterized in that a ring of first annular drainage ditches (12) are provided outside the work pit (2).

7. A pipe-jacking work pit supporting method according to claim 1, wherein a circle of second annular drainage ditches (13) are arranged in the bottom of the work pit (2), and the second annular drainage ditches (13) are communicated with a water collecting pit (14) in the bottom of the work pit (2).

8. A pipe-jacking work pit supporting method according to claim 1, wherein in step three, the vertical spacing between adjacent ring beams (4) in the work pit (2) is 4 m.

9. A pipe-jacking working pit supporting method according to claim 1, wherein in step three, the ring beam (4) is connected with a waterproof curtain through a dowel.