CN115595993A - Replacement pile structure of tunnel-passing slope slide-resistant pile and construction method - Google Patents

Abstract

The invention discloses a replacement pile structure of a tunnel-through slope slide-resistant pile, which is arranged below an existing building and comprises a counterfort retaining wall and a rotary-excavating filling pile, wherein the counterfort retaining wall comprises a beam, a heel plate, a wall panel and a counterfort, the beam is arranged between the heel plate and the wall panel, one side of the beam is fixedly connected with the heel plate, the top of the beam is fixedly connected with the bottom of a front panel, the counterfort is fixedly arranged at the top of the heel plate, the counterfort is fixedly connected with the wall panel, the top of the rotary-excavating filling pile penetrates through the bottom of the heel plate, and the top of the rotary-excavating filling pile is fixedly connected with the heel plate. The replacement pile structure provided by the invention can furthest reduce the influence of the original slide-resistant pile on the original structure in the tunnel construction process, and ensure the safety and stability of the original structure and the tunnel in the tunnel construction process.

Description

A replacement pile structure and construction method for tunnel crossing slope anti-slide piles

technical field

The invention belongs to the technical field of tunnel construction, and in particular relates to a displacement pile structure and a construction method for tunnel crossing slope anti-slide piles.

Background technique

With the rapid development of cities, in order to meet people's daily travel needs, more and more highways, railways, subways, etc. have begun to be built in cities. These tunnels often need to pass through existing buildings or structures, so it involves the demolition and protection of the original pile foundation. Pile foundations play a vital role in the safety and stability of buildings. How to ensure the normal use of the original structures without destroying the safety of the original buildings or structures or even during tunnel construction has become a major problem. If the protection is not obtained, the tunnel construction process may threaten the normal use of the original building, or even endanger the safety of the original building, causing heavy economic losses and casualties. Therefore, it is of great significance for the design and construction of this type of tunnel to invent a replacement pile structure and construction method for tunnel crossing slope anti-slide piles.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a replacement pile structure and construction method for tunnel crossing slope anti-slide piles.

The first object of the present invention is to provide a replacement pile structure for tunnel crossing slope anti-slide piles, including buttress-type retaining walls and rotary-dug cast-in-place piles;

The buttress retaining wall comprises a beam, a heel plate, a wall panel and a buttress, the beam is arranged between the heel plate and the wall panel, one side of the beam is fixedly connected to the heel plate, and the top of the beam is connected to the front panel The bottom is fixedly connected, the buttress is fixedly arranged on the top of the heel plate, the buttress is fixedly connected with the wall panel, the top of the rotary-dug cast-in-place pile runs through the bottom of the heel-plate, and the top of the rotary-dug cast-in-situ pile is fixedly connected with the heel plate.

Preferably, the bottom of the heel plate is fixedly provided with a cushion, and the top of the rotary-dug cast-in-place pile penetrates the cushion and is in close contact with the cushion.

Preferably, the length of the rotary-dug cast-in-place pile extending into the heel plate is 20cm.

Second object of the present invention is to provide a kind of construction method of the above-mentioned tunnel passing through the replacement pile structure of the slope anti-slide pile, comprising the following steps:

S1. Construction preparation

Arrange and construct the construction site and construction access road respectively, review the earthwork filling range and rotary excavation pile positions according to the construction design drawing, and carry out measurement and stakeout;

S2. Earthwork filling

After the measurement and stakeout is completed in step S1, the temporary working platform is filled and rolled;

S3. Construction of rotary excavation cast-in-place piles

After the rolling is completed in step S2, the rotary excavation pile construction is carried out;

S4. Pile foundation detection

After the construction of the rotary-dug cast-in-place pile in step S3 is completed, the pile foundation of the rotary-dig cast-in-situ pile is detected by ultrasonic and low-strain methods after the detection conditions are met;

S5. Construction of buttress retaining wall

After the pile foundation of the rotary excavation cast-in-situ pile in step S4 is qualified, foundation excavation, foundation treatment, foundation parts, wall panels, buttresses and backfill construction of the wall are sequentially carried out during construction of the buttress-type retaining wall;

S6. Tunnel excavation and original pile foundation removal

After the construction of the buttress-type retaining wall in step S5 is completed, and the stress and strain tend to be stable, start tunnel excavation and remove the original anti-slide piles.

Preferably, in step S3, the construction of the rotary-dug cast-in-place pile specifically includes the following steps:

S31. Site treatment: After the rolling is completed in step S2, the ground is leveled and compacted, and the ground elevation must be higher than the designed pile top by more than 60 cm;

S32. Pile position stakeout: Stake out the central position of the pile position, lead four points with the same distance to four different directions as protective piles, connect the two opposite protective piles with thin ropes, and cross the two thin ropes. The point is the pile point;

S33. Buried casing: according to the layout of the pile position numbers, the construction sequence adopts the construction of separated holes, and the piles to be constructed are drilled by rotary drilling, and the casing is placed in the dug hole, and the ground line is buried 4700mm below the ground line. 300mm above the ground, and then backfill the bottom and outer sides of the casing with clay soil and compact it layer by layer;

S34, cleaning the hole for the first time: the original mud inside the casing is removed by the mud changing method;

S35. After the first hole cleaning is completed, the steel cage skeleton and the conduit are installed in sequence. After the installation is completed, the second hole cleaning is carried out. After the pile holes are cleaned, the thickness of the sediment at the bottom of the hole must not exceed 50mm;

S36. Concrete pouring: concrete is poured into the casing, and after the pouring is completed, a rotary-dug cast-in-place pile is obtained.

Preferably, in step S4, the detection condition is that the strength of the pile foundation concrete is greater than 70% of the design strength and not lower than 15Mpa.

Preferably, in step S5, the construction of the buttress type retaining wall specifically includes the following steps:

S51. Foundation excavation: After the pile foundation of the rotary excavation pile in step S4 is qualified, the excavation is carried out according to the depth of the excavated foundation pit according to the slope ratio of 1:0.75 and the structural size of the heel plate and beam by 1m to the design elevation. Excavation. Before excavation, clearly mark the pile position foundation pit on the top of the pouring pile filling surface. After digging to 20cm above the bottom of the floor, manually clean up the muck at the bottom of the heel plate and the beam to the design elevation;

S52. Base treatment: manually clean the muck on the head of the rotary-dug cast-in-place pile. After the cleaning is completed, the pile foundation of the rotary-dug cast-in-place pile is cleared with a pick and an artificial steel drill;

S53. Construction of foundation parts: after removing the pile head, the exposed steel bars extend into the cushion layer and the heel plate, connect the rotary-dug cast-in-situ pile with the buttress-type retaining wall, and then bind and pour the beam, heel plate and concrete synchronously;

S54. Construction of wall panels and buttresses: synchronous binding and pouring of wall panels, retaining reinforcement bars, and concrete;

S55. Backfill construction at the back of the wall: After the retaining wall is demolished, the concrete strength meets the design requirements, and then backfill the back of the wall. The backfill position is between the back of the wall panel and the side slope.

Preferably, in step S53 and step S54, the templates used for the beams, heel plates, wall panels and retaining walls are composite steel molds.

Compared with the prior art, the present invention has the beneficial effects of:

(1) The replacement pile structure and construction method of the tunnel passing through the slope anti-slide piles provided by the present invention can minimize the impact of breaking the original anti-slide piles on the original structure during the tunnel construction process, and ensure the integrity of the original structure and the tunnel itself during the tunnel construction process. safe and stable;

(2) The replacement pile structure provided by the present invention can further improve the stability of the original slope structure and increase the safety redundancy of the original slope through the joint design of buttress type retaining wall and rotary excavation cast-in-situ pile;

(3) The replacement pile structure provided by the present invention is simple in structure, reasonable in design, and convenient in construction, and can effectively solve the problem of force transformation of anti-slide piles that need to be broken during tunnel construction.

Description of drawings

Fig. 1 is the plane structure diagram of the replacement pile structure of the tunnel passing through the slope anti-slide pile provided by the embodiment of the present invention;

Fig. 2 is the sectional view of the replacement pile structure that the embodiment of the present invention provides;

Fig. 3 is the three-dimensional rendering of the replacement pile structure provided by the embodiment of the present invention;

Fig. 4 is the construction flowchart of the replacement pile structure of the tunnel passing through the slope anti-slide pile provided by the embodiment of the present invention;

In the figure: 1. Rotary excavation pile; 2. Buttress retaining wall; 3. Original anti-slide pile; 4. Heel plate; 5. Wall panel; 6. Buttress; 7. Cushion; 8. Beam; 9. Tunnel.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

As shown in Figures 1 to 3, the embodiment of the present invention provides a replacement pile structure for tunnel crossing slope anti-slide piles, including a buttress-type retaining wall 2 and a rotary-dug cast-in-place pile 1;

The buttress type retaining wall 2 comprises a beam 8, a heel plate 4, a wall panel 5 and a buttress 6, the beam 8 is arranged between the heel plate 4 and the wall panel 5, and one side of the beam 8 is connected to the heel plate 4 Fixed connection, the top of the beam 8 is fixedly connected with the bottom of the wall panel 5, the buttress 6 is fixedly arranged on the top of the heel panel 4, the buttress 6 is fixedly connected with the wall panel 5, and the top of the rotary drilling pile 1 runs through the bottom of the heel panel 4 bottom, and the top of the rotary drilling cast-in-situ pile 1 is fixedly connected with the heel plate 4.

The bottom of the heel plate 4 is fixedly provided with a cushion layer 7 , and the top of the rotary-dug cast-in-place pile 1 penetrates the cushion layer 7 and is in close contact with the cushion layer 7 .

The length that the rotary-dug cast-in-situ pile 1 extends into the heel plate 4 is 20cm.

The embodiment of the present invention also provides a construction method of the above-mentioned tunnel passing through the replacement pile structure of the slope anti-slide pile, which specifically includes the following steps:

S1. Construction preparation

Arrange and build the construction site and construction access road respectively, and complete the "three connections and one leveling" in the early stage (that is, before the official construction, the construction site should meet the conditions of water, electricity, road access and site leveling), material stacking site, Preparation for installation and commissioning of tools and equipment, review the earthwork filling range and bored pile positions according to the construction design drawing, and carry out measurement and lofting disclosure;

S2. Earthwork filling

After the measurement and stakeout is completed in step S1, fill the temporary working platform and carry out rolling. The rolling follows the principle of "light first, then heavy, first both sides, then the middle, first static pressure, then vibratory pressure". The rolling is divided into initial pressure, Re-pressure and final pressure;

S3. Construction of rotary excavation cast-in-place piles

After the rolling is completed in step S2, the construction of the rotary-dug cast-in-situ pile 1 is carried out, and the construction of the rotary-dug cast-in-situ pile 1 specifically includes the following steps:

S31. Site treatment: After the rolling is completed in step S2, the ground is leveled and compacted. The ground elevation must be higher than the design pile top by more than 60 cm. Before the pile foundation construction, 4 acoustic measuring tubes must be embedded in each pile for ultrasonic detection;

S32. Pile position stakeout: Use a total station to stake out the central position of the pile position, lead four points with the same distance to four different directions as protective piles, and connect the two opposite protective piles with thin ropes. The intersection point of the string is the stake point;

S33. Buried casing: according to the layout of the pile position numbers, the construction sequence adopts the construction of separated holes, and the piles to be constructed are drilled by rotary drilling, and the casing is placed in the dug hole, and the ground line is buried 4700mm below the ground line. 300mm above the ground, when the casing is buried and positioned, the plane position deviation between the center of the casing and the center of the pile is not more than 50mm, and the inclination of the casing in the vertical direction is not more than 1%. The soil is backfilled and compacted in layers. The casing is made of steel plates with an inner diameter of 2700mm, a height of 5000mm, and a wall thickness of 20mm. When the casing is manufactured and processed, its ellipticity is less than d/100; the allowable deviation of the diameter is ±10mm; The allowable deviation of the inclination of the body end face is 3mm, and the bending sagittal height of the longitudinal axis shall not be greater than 0.1% of the length of the casing, and shall not be greater than 30mm; the amount of misalignment of the butt joint of the casing shall not be greater than 0.2 times the thickness of the steel plate, and shall not be greater than 4mm;

S34. Cleaning the hole for the first time: Use the slurry changing method to clean the original mud inside the casing until the mud discharged or extracted from the hole has no grainy feel to the touch, and the specific gravity, viscosity, and sand content of the mud are controlled within the required range;

S35. After the first hole cleaning is completed, the steel cage skeleton and the conduit are installed in sequence. After the installation is completed, the second hole cleaning is carried out. After the pile holes are cleaned, the thickness of the sediment at the bottom of the hole must not exceed 50mm;

S36. Concrete pouring: pour concrete into the casing. After the pouring is completed, a rotary-dug cast-in-situ pile 1 is obtained. The concrete is C35 concrete, the steel bars are mainly HRB400 and HPB300, and the thickness of the main reinforcement protective layer is 70mm.

S4. Pile foundation detection

After the construction of the rotary-dig cast-in-place pile 1 in step S3 is completed, after the concrete strength of the pile foundation is greater than 70% of the design strength and not lower than 15MPa, the pile foundation of the rotary-dig cast-in-situ pile is detected by ultrasonic and low-strain methods, specifically according to "Building Integrity testing of pile foundations is carried out in JGJ106-2014 and other relevant regulations and specifications, and 50% of pile foundations use low-strain integrity testing, and 50% of pile foundations use ultrasonic integrity testing. Core drilling samples were taken on 10% of the pile foundations of the total number of piles. The concrete age of the pile foundation for core sampling shall not be less than 28 days;

S5. Construction of buttress retaining wall

After the pile foundation of the rotary excavation cast-in-place pile in step S4 is qualified, foundation excavation, foundation treatment, foundation parts, wall panels 5, buttresses 6 and backfill construction of the wall are sequentially carried out during construction of the buttress-type retaining wall 2 , in the embodiment of the present invention, the construction of the buttress type retaining wall 2 specifically includes the following steps:

S51, foundation excavation: after the pile foundation of the rotary excavation cast-in-place pile 1 in step S4 is qualified, that is, after the concrete strength of all pile foundations reaches more than 75%, according to the excavation depth of the foundation pit according to the slope ratio of 1:0.75 and the heel plate The structural dimensions of 4 and beam 8 are expanded 1m outward to the design elevation for excavation. Before excavation, the pile position foundation pit is clearly marked on the top of the filling surface of the cast-in-situ piles. The muck at the bottom of beam 8 reaches the design elevation;

S52. Base treatment: after the muck on the pile head of the rotary-dug cast-in-place pile 1 is manually cleaned, the pile foundation is cleared and chiseled with a pneumatic pick and an artificial steel drill;

S53. Construction of foundation parts: After the pile head is removed, the exposed steel bars extend into the cushion layer 7 and the heel plate 4, and the rotary excavation pile 1 is connected with the buttress retaining wall 2, and then the beam 8, the heel plate 4 and the buttress retaining wall 2 are connected. Simultaneous binding and pouring of concrete;

S54. Wall panel and buttress construction: wall panel 5 and buttress reinforcement and concrete are bound and poured synchronously, the templates are all combined steel molds, the tie rods are pulled in opposite directions, and the back support is reinforced;

S55. Backfill construction at the back of the wall: after the formwork removal of the retaining wall, the concrete strength meets the design requirements, and then backfill the back of the wall. Foam soil is used for the backfill, and the backfill position is between the back of the wall panel and the side slope;

S6. Tunnel excavation and original pile foundation removal

After the construction of the buttress-type retaining wall 2 in step S5 is completed, and the stress and strain tend to be stable, the excavation of the tunnel 9 is started and the original anti-slide pile 3 is removed. When the original anti-slide pile is removed, the monitoring of the slope and the replacement structure should be strengthened Measurement, monitoring and measurement specifically include:

(1) Observation inside and outside the cave: The observation in the cave includes the observation of the excavation surface and the observation of the section where the initial support is completed. The observation of the excavation surface is carried out once after each excavation. Records and determination cards of surrounding rock grades, observation of the section where the initial support is completed shall be carried out at least once a day, and the observation content includes the status of sprayed concrete, anchor rods, and steel frames. The observation outside the cave includes the observation of the surface conditions at the entrance of the cave, surface subsidence, stability of side slopes and uphill slopes, and surface water seepage.

(2) Peripheral displacement measurement: measure the convergence of the section of the tunnel, including the measurement of the sinking of the vault, the convergence of the headroom level and the swelling of the floor (if necessary).

(3) Surface subsidence measurement: The surface subsidence measurement should start at the sum of the tunnel embedment depth in front of the excavation face and the tunnel excavation height until the lining structure is closed and the subsidence basically stops. A total station is used to monitor the coordinates and elevation of each fixed point, and a ruler is used to measure the change of crack width, which can refer to the BM point of the road survey. And set the inclinometer tube on the interval platform.

(4) Advance geological forecast: Based on the geological survey and analysis method, combined with geophysical means such as TSP and geological radar, supplemented by comprehensive geological forecast means such as advanced drilling. Among them: set a section at an interval of 100-150m for TSP, set a section at an interval of 30m for ground radar, and add more advanced drilling holes as needed.

In summary, the replacement structure of anti-slide piles for tunnel crossing slopes provided by the embodiment of the present invention is an optimization scheme proposed on the basis of traditional buttress-type retaining walls according to actual engineering conditions. The original slope anti-slide piles are replaced by the combined force-bearing structure of the rotary-dug pile hole grouting piles. The layout of the buttress retaining wall and the rotary-dug grouting piles is designed according to the slope conditions, the location of the anti-slide piles and the location of the tunnel. , to protect the safety of the slope and improve the stability of the slope when the original anti-slide piles are excavated in the tunnel.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (8)

1. A replacement pile structure of an anti-slide pile for a tunnel to pass through a side slope is arranged below an existing building and is characterized by comprising a buttress retaining wall (2) and a rotary excavating filling pile (1);

buttress formula retaining wall (2) contain roof beam (8), heel board (4), shingle nail (5) and buttress (6), roof beam (8) set up between heel board (4) and shingle nail (5), one side and heel board (4) fixed connection of roof beam (8), the top of roof beam (8) and the bottom fixed connection of shingle nail (5), buttress (6) fixed set up in the top of heel board (4), buttress (6) and shingle nail (5) fixed connection, the bottom of heel board (4) is run through at the top of bored concrete pile (1) soon, and dig the top of bored concrete pile (1) soon and heel board (4) fixed connection.

2. The replacement pile structure of the tunnel-crossing slope slide-resistant pile according to claim 1, wherein a cushion layer (7) is fixedly arranged at the bottom of the heel plate (4), and the top of the rotary-digging cast-in-place pile (1) penetrates through the cushion layer (7) and is in close contact with the cushion layer (7).

3. The replacement pile structure of the tunnel-crossing slope slide pile according to claim 1, wherein the length of the rotary excavating cast-in-place pile (1) extending into the heel plate (4) is 20cm.

4. The method for constructing a replacement pile structure of a tunnel-crossing slope slide pile according to claim 1, which comprises the following steps:

s1, preparation for construction

Respectively arranging and constructing a construction site and a construction sidewalk, rechecking an earthwork filling range and a pile position of a rotary excavating cast-in-place pile (1) according to a construction design drawing, and measuring, lofting and mating the bottom;

s2, filling earthwork

After the step S1 of measurement lofting is finished, filling a temporary working platform and rolling;

s3, construction of rotary digging cast-in-place pile

After the rolling is finished in the step S2, construction of the rotary excavating cast-in-place pile (1) is carried out;

s4, pile foundation detection

After the construction of the rotary excavating filling pile (1) is completed in the step S3, detecting a pile foundation of the rotary excavating filling pile (1) by adopting an ultrasonic wave and low strain method after detection conditions are met;

s5, counterfort retaining wall construction

After the pile foundation of the rotary excavating filling pile (1) in the step S4 is detected to be qualified, foundation excavation, substrate treatment, foundation pieces, wall panels (5), buttresses (6) and wall back backfill construction are sequentially carried out when the buttress retaining wall (2) is constructed;

s6, tunnel excavation and original pile foundation demolition

And (5) after the construction of the counterfort retaining wall (2) in the step (S5) is completed, and after the stress and strain tend to be stable, starting tunnel excavation and dismantling the original anti-slide pile (3).

5. The method for constructing the replacement pile structure of the tunnel-crossing slope slide-resistant pile according to claim 4, wherein in the step S3, the rotary excavating cast-in-place pile construction specifically comprises the following steps:

s31, site processing: after the rolling is finished in the step S2, leveling and compacting the ground, wherein the ground elevation needs to be higher than the designed pile top by more than 60 cm;

s32, pile position lofting: lofting the center position of a pile position, guiding four points with the same distance to four different directions to serve as guard piles, connecting two opposite guard piles by using thin ropes, wherein the intersection point of the two thin ropes is a pile position point;

s33, embedding a protection tube: according to the pile position numbering layout, adopting hole isolation construction according to the construction sequence, carrying out rotary drilling on the pile position to be constructed, placing a pile casing into the excavated hole, burying 4700mm below the ground line, exposing 300mm above the ground, backfilling the bottom and the periphery of the outer side of the pile casing with clay soil, and compacting in layers;

s34, cleaning holes for the first time: removing the original slurry in the protective cylinder by adopting a slurry changing method;

s35, after the hole cleaning is finished for the first time, sequentially installing the reinforcement cage framework and the guide pipe, and after the hole cleaning is finished for the second time, cleaning the hole, wherein the thickness of the sediment at the bottom of the hole is not more than 50mm after the hole is cleaned;

s36, pouring concrete: and (3) pouring concrete into the pile casing, and obtaining the rotary excavating cast-in-place pile (1) after pouring.

6. The method for constructing a replacement pile structure of a tunnel-crossing slope slide-resistant pile according to claim 4, wherein in the step S4, the detection condition is that the strength of the pile foundation concrete is greater than 70% of the design strength and not lower than 15MPa.

7. The method for constructing a replacement pile structure of a tunnel-through slope slide pile according to claim 4, wherein in the step S5, the counterfort retaining wall construction specifically comprises the following steps:

s51, foundation excavation: after the pile foundation of the rotary-excavating cast-in-place pile in the step S4 is detected to be qualified, excavating according to the depth of an excavation foundation pit, the slope ratio of 1.75 and the structural sizes of the heel plate (4) and the beam (8) which are expanded by 1m outwards to a designed elevation, obviously marking a pile position foundation pit on the top of the filling surface of the cast-in-place pile before excavating, and manually cleaning the heel plate (4) and the bottom of the beam (8) to the designed elevation after excavating to 20cm from the bottom of the bottom plate;

s52, substrate treatment: cleaning up the slag soil on the pile head of the rotary-digging cast-in-place pile (1) manually, and after the cleaning up is completed, cleaning up the pile head of the rotary-digging cast-in-place pile (1) by adopting an air pick and a manual steel drill;

s53, constructing a foundation part: after a pile head is chiseled off, exposed reinforcing steel bars extend into the cushion layer (7) and the heel plate (4), the rotary-digging cast-in-place pile (1) is connected with the counterfort retaining wall (2), and then the beam (8) and the heel plate (4) are synchronously bound and poured with concrete;

s54, wall panel and buttress construction: synchronously binding and pouring the wall panel (5), the wall protection reinforcing steel bars and the concrete;

s55, wall back backfilling construction: and backfilling the wall back after the concrete strength of the retaining wall after the form removal reaches the design requirement, wherein the backfilling position is between the back of the wall panel (5) and the side slope.

8. The method for constructing the replacement pile structure of the tunnel-through slope slide-resistant pile according to claim 4, wherein the templates adopted by the beam (8), the heel plate (4), the wall panel (5) and the retaining wall (6) in the steps S53 and S54 are all combined steel molds.

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