CN111648373A

CN111648373A - Excavation supporting construction process for water-rich deep foundation pit fender pile gap

Info

Publication number: CN111648373A
Application number: CN202010410587.9A
Authority: CN
Inventors: 任鹏鹏; 刘大鹏; 刘柏忠; 张亦程; 温志洋; 詹友君; 雷丹阳; 王赛; 李建民
Original assignee: China Railway Sixth Group Co Ltd; Taiyuan Railway Construction Co Ltd of China Railway Sixth Group Co Ltd
Current assignee: China Railway Sixth Group Co Ltd; Taiyuan Railway Construction Co Ltd of China Railway Sixth Group Co Ltd
Priority date: 2020-05-15
Filing date: 2020-05-15
Publication date: 2020-09-11
Anticipated expiration: 2040-05-15
Also published as: CN111648373B

Abstract

The invention belongs to the technical field of fender pile gap support, in particular to a construction process for excavating and supporting a fender pile gap of a water-rich deep foundation pit, which solves the technical problems in the background technology. The construction process solves the technical problem that the fender post structure cannot be closed due to the fact that underground pipelines are numerous and cannot be moved and changed, or the moving and changing cost is high and the moving and changing time is long on the urban main road, reduces the influence of the urban underground pipelines on urban subway construction, saves the moving and changing time and cost, shortens the construction period, provides favorable conditions for subsequent construction, can be operated in parallel with the hanging net and the spray anchor at the periphery of a deep foundation pit in the construction of the gap of the fender post, can ensure safe and orderly construction, improves the construction efficiency, and is simple to operate and safe to construct.

Description

Excavation supporting construction process for water-rich deep foundation pit fender pile gap

Technical Field

The invention belongs to the technical field of fender pile gap support, and particularly relates to a construction process for excavating and supporting a fender pile gap of a water-rich deep foundation pit.

Background

With the development of traffic networks, urban rail transit is an important component of urban public transport, and urban rail transit engineering is increasing day by day. The method is characterized in that a deep foundation pit of about 20 meters needs to be excavated in subway construction, and fender piles need to be cast on the side wall of the deep foundation pit. In urban subway construction, the conditions that urban underground pipelines are numerous and cannot be moved and changed or the moving and changing cost is high, the moving and changing time is long and the construction period is possibly influenced are frequently met, so that the foundation pit fender post structure cannot be closed, and the technical problem that the deep foundation pit is difficult to excavate is caused.

Disclosure of Invention

The invention aims to solve the technical problems in the background art and provides a construction process for excavating and supporting a water-rich deep foundation pit fender pile gap.

The technical means for solving the technical problems of the invention is as follows: a construction process for excavating and supporting a water-rich deep foundation pit fender pile gap comprises the following steps:

the method comprises the following steps: before constructing the fender pile, carrying out exploration and excavation on the underground pipeline, determining the accurate position of the underground pipeline, then carrying out fender pile construction, and finally forming a fender pile gap at the corresponding position of the underground pipeline;

step two: mechanically excavating a foundation pit in a layered mode, controlling the layered thickness to be 0.5-1m, and excavating a certain thickness from the position of the gap of the fender post to the outer side;

step three: constructing a high-pressure jet grouting pile which is horizontally arranged on the side wall at the position of the gap of the fender pile; the construction process of the high-pressure jet grouting pile is executed according to the standard; the grouting reinforcement measure is adopted to solidify and compact the soil body outside the gap position of the fender post, and the high-pressure jet grouting post has integrity and water sealing effect, so that the pressure on the fender structure is reduced;

step four: continuing to manually dig the fender pile gap outwards on the basis of mechanical excavation, and finally, enabling the thickness of a soil body dug outwards to meet the requirement for placing a straw mat and a bamboo rubber plate, cleaning the soil body between two opposite fender piles at the fender pile gap and exposing the concrete side walls of the fender piles at two sides;

step five: drilling holes in the opposite positions of the upper part and the lower part of the fender post on the two sides, implanting anchoring steel bars, and extending the anchoring steel bars out of the pile surface of the fender post by a certain length;

step six: welding a lower layer channel steel crossing the gap of the fender pile between the anchoring steel bars at the lower parts of the fender piles at two sides, wherein the notch of the lower layer channel steel is upward;

step seven: installing a straw curtain and a bamboo plywood in the lower layer channel steel, wherein the straw curtain is close to the outer side of the foundation pit, the bamboo plywood is close to the inner side of the foundation pit, the total thickness of the straw curtain and the bamboo plywood is just clamped between two groove walls of the lower layer channel steel, the length of the bamboo plywood and the length of the straw curtain are equal to the width of a gap of the fender post, and the height of the bamboo plywood and the height of the straw curtain are equal to the downward excavation thickness of the foundation pit;

step eight: embedding drainage tubes at two ends of the lower layer channel steel, wherein the water inlet of each drainage tube is positioned at the position of the straw mat and is wrapped by water-permeable geotextile; the outlet of the drainage pipe extends into the foundation pit;

step nine: welding upper-layer channel steel crossing gaps of the fender piles between anchoring steel bars at the upper parts of the fender piles at two sides, enabling the notches of the upper-layer channel steel to face downwards, and wrapping the upper ends of the grass curtain and the bamboo plywood by utilizing the upper-layer channel steel;

step ten: welding a reinforcing mesh, wherein the reinforcing mesh is fixed with the upper-layer channel steel and the lower-layer channel steel close to one side of the foundation pit;

step eleven: spraying concrete on the reinforcing mesh sheets according to design requirements, reserving a certain height at the lower part of each layer of reinforcing mesh sheets for temporary spraying, and overlapping the concrete with the concrete of the lower layer of reinforcing mesh sheets, wherein the thickness of the concrete sprayed at the gap of the fender post ensures that the concrete surface is flush with the concrete surface at other positions on the side wall of the foundation pit;

step twelve: and repeating the second step and the eleventh step, continuously excavating the lower-layer foundation pit, crossing the underground pipeline when the underground pipeline is excavated, and then continuously performing the steps until the whole foundation pit is completely excavated.

The invention has the beneficial effects that: the construction method disclosed by the invention is used for carrying out excavation and support construction on the gap of the fender post of the water-rich deep foundation pit, solves the technical problem that the fender post structure cannot be closed due to the fact that underground pipelines on an urban main road cannot be moved and changed or the moving and changing cost is high and the moving and changing time is long, reduces the influence of the urban underground pipelines on urban subway construction, saves the moving and changing time and cost, shortens the construction period, provides favorable conditions for subsequent construction, can be operated in parallel with the net hanging and anchor spraying at the periphery of the deep foundation pit in the construction at the gap of the fender post, can ensure safe and orderly construction, is not limited by the conditions of mechanical maintenance, field entering and exiting and the like, improves the construction efficiency, is simple to operate and safe to construct, uses existing small equipment in the field, saves the use cost of large machinery, and obtains good social and economic benefits.

Drawings

FIG. 1 is a flow chart of the construction process of the present invention.

Fig. 2 is a schematic plan structure view of the deep foundation pit fender pile gap reinforcing structure.

Fig. 3 is a schematic elevation structure view of the deep foundation pit fender pile gap reinforcing structure.

In the figure: 1-fender posts; 2-underground pipelines; 3-enclosing a pile gap; 4, foundation pit; 5-high pressure jet grouting pile; 6-straw mat; 7-bamboo plywood; 8-anchoring the steel bars; 9-lower channel steel; 10-a drainage tube; 11-upper channel steel; 12-concrete.

Detailed Description

With reference to fig. 1, 2 and 3, the construction process of excavation and support of the water-rich deep foundation pit fender pile gap according to the invention is explained in detail.

Example (b):

a construction process for excavating and supporting a water-rich deep foundation pit fender pile gap comprises the following steps as shown in figure 1:

the method comprises the following steps: before constructing the fender pile 1, exploring and digging the underground pipeline 2, determining the accurate position of the underground pipeline 2, hanging and pasting a striking mark, then constructing the fender pile 1, and finally forming a fender pile gap 3 at the corresponding position of the underground pipeline 2, as shown in figures 2 and 3;

step two: mechanically excavating a foundation pit 4 in a layered mode, controlling the layered thickness to be 0.5-1m, and excavating a certain thickness from the position of the fender post gap 3 to the outer side in an expanding mode; during specific operation, according to the principle of excavation and supporting, the layering thickness is controlled to be 1m, and the thickness of 0.2m is mechanically expanded and excavated towards the outer side at the position of the gap 3 of the fender post;

step three: constructing a high-pressure jet grouting pile 5 which is horizontally arranged on the side wall at the position of the gap 3 of the fender pile; the high-pressure grouting adopts a high-pressure jet grouting pile 5 process, pile positions are arranged according to the pile diameter of the high-pressure jet grouting pile 5 of 0.5-0.6m, the pile spacing of the same layer of high-pressure jet grouting piles 5 is 0.4-0.5m, the layer spacing of upper and lower layers of high-pressure jet grouting piles 5 is 0.4-0.5m, the high-pressure jet grouting piles 5 are horizontally arranged and vertical to the side wall of the foundation pit 4, and the pile length is 3-5 m; arranging drilling positions, moving the pile machine to a specified position to align the pile positions, centering, leveling and correcting the drill rod angle after the pile machine reaches a calibration hole position, and ensuring that the levelness error is within 1.0%; according to the water-cement ratio of 1: 0.5, stirring cement paste, fully and uniformly stirring the cement paste, and pouring the cement paste into a collecting hopper before grouting; starting the stirrer after the cooling water circulation of the deep stirrer is normal, loosening a steel wire rope of the crane to enable the stirrer to cut soil along the guide frame, stir and sink, wherein the sinking speed is controlled by a current monitoring meter of the motor, and the water is not required to be flushed during premixing; after the stirrer sinks to the designed depth, starting an mortar pump, keeping the outlet pressure of the mortar pump at 0.4-0.6 Mpa, continuously spraying cement slurry, controlling the rotary spraying speed of the stirrer to be about 0.5m/min, stopping lifting when the lifting reaches the designed elevation, and stirring for several seconds to ensure that the pile head is uniform and compact; in order to fully stir the cement paste sprayed into the soil and the soil, repeatedly stirring and sinking until the required depth is reached, then stirring and lifting, and re-spraying along the pile body within the range of 1.0m above and below the upper part; after construction is finished, injecting a proper amount of clear water into the collecting hopper, starting a mortar pump, cleaning residual cement paste in the pipeline, and simultaneously removing the soil adhered to the drill bit; the grouting reinforcement measure is adopted to solidify and compact the soil body outside the position of the gap 3 of the fender pile, and the high-pressure jet grouting pile 5 has integrity and water sealing effect, so that the pressure on the fender structure is reduced, and the concrete structure is shown in figures 2 and 3;

step four: on the basis of mechanical excavation, manual outward expanding excavation is continuously carried out on the position of a fender post gap 3 for about 0.1m, the side wall of a foundation pit 4 is cleaned and leveled manually, the thickness of a soil body finally outward expanding excavation is about 0.3m, the requirement that a straw curtain 6 and a bamboo rubber plate 7 can be placed is met, the soil body between two opposite fender posts 1 at the position of the fender post gap 3 is cleaned, and the concrete side walls of the fender posts 1 at two sides are exposed, and the concrete side walls are shown in fig. 2 and 3 specifically;

step five: drilling holes in the relative positions of the upper part and the lower part of the fender post 1 at two sides, implanting anchoring steel bars 8, drilling holes at the side of the post by adopting an electric hammer, wherein the diameter of the drilled hole is 25-37mm, the drilling depth is 230-350mm, and removing impurities in the holes immediately after drilling, so as to ensure that the holes are clean, dry and free of impurities; adopting bar planting equipment with stable performance such as a glue gun and the like to plant bars, wherein the diameter of the anchoring steel bar 8 is 20-28mm, and the anchoring steel bar 8 extends out of the pile surface of the fender post 1 by the length of 200-280mm, which is shown in fig. 2 specifically;

step six: lower-layer channel steel 9 crossing the fender pile gap 3 is welded between anchoring steel bars 8 at the lower parts of fender piles 1 at two sides, notches of the lower-layer channel steel 9 face upwards, the supporting and blocking effects of the fender piles 1 at the two sides are fully utilized, the lower-layer channel steel 9 is C14-C20 channel steel, in the concrete operation, the lower-layer channel steel is C20 channel steel, the anchoring steel bars 8 are fully welded with the side edge of the lower-layer channel steel 9, and a welding seam is full and is shown in figure 3;

step seven: firstly installing a straw curtain 6 in the lower layer channel steel 9, and then installing a bamboo plywood 7, wherein the bamboo plywood 7 is a soil retaining plate, and the loose paving thickness of the straw curtain 6 is 200-250 mm; the thickness of the bamboo plywood 7 is 10-22mm, taking a 1.2m wide gap as an example, 3 high-pressure jet grouting piles 5 are horizontally arranged, the pile spacing of the same layer of high-pressure jet grouting piles 5 is 0.5m, the distance between the centers of the two high-pressure jet grouting piles 5 on the left side and the right side is 0.1m from the edge of a drilled pile, the width of the bamboo plywood 7 is 980mm, the grass curtain 6 is close to the outer side of the foundation pit 4, the bamboo plywood 7 is close to the inner side of the foundation pit 4, the total thickness of the grass curtain 6 and the bamboo plywood 7 can be just clamped between two groove walls of the lower layer of channel steel 9, the lengths of the bamboo plywood 7 and the grass curtain 6 are equal to the width of the gap 3 of the enclosure pile, and the heights of the bamboo plywood 7 and the grass curtain 6 are the downward excavation thickness of the layer;

step eight: the drainage tubes 10 are embedded at two ends of the lower layer channel steel 9, the drainage tubes 10 are rubber tubes with the diameter of 10-15mm, the water inlets of the drainage tubes 10 are positioned at the straw mats 6, the water inlets of the drainage tubes 10 are wrapped by permeable geotextile, and the water outlets are wrapped by plastic cloth, so that the blockage of sprayed soil is prevented; the outlet of the draft tube 10 extends into the foundation pit 4, as shown in fig. 2 and 3;

step nine: welding an upper-layer channel steel 11 crossing a fender pile notch 3 between anchoring steel bars 8 at the upper parts of fender piles 1 at two sides, wherein the upper-layer channel steel 11 is C14-C20 channel steel, in the concrete operation, the upper-layer channel steel is C20 channel steel, a notch of the upper-layer channel steel 11 faces downwards, the anchoring steel bars 8 are in full-welding connection with the side edge of the upper-layer channel steel 11, a welding line is full, and the upper ends of a straw mat 6 and a bamboo plywood 7 are wrapped by the upper-layer channel steel 11, which is shown in figure 3 specifically;

step ten: welding a reinforcing mesh 12, hanging the reinforcing mesh 12 with the diameter of 6mm and the grid structure of 100 × 100mm to 150 × 150mm according to the design requirement, fixing the reinforcing mesh 12 with an upper layer channel steel 11 and a lower layer channel steel 9 which are close to one side of the foundation pit 4, and vertically welding a plurality of reinforcing steel bar sections with the length of 100mm on one side of the reinforcing mesh 12 facing the foundation pit 4, wherein the reinforcing steel bar sections are used for controlling the thickness of sprayed concrete and are specifically shown in fig. 2 and 3;

step eleven: before spraying concrete on the reinforcing mesh 12, arranging a plurality of C20 concrete cushion blocks between the bamboo plywood 7 and the reinforcing mesh 12, spraying concrete on the reinforcing mesh 12 according to design requirements, constructing by adopting a wet spraying process, wherein the spraying thickness is not more than 50mm each time, spraying two layers in total, keeping a certain time interval for two concrete spraying operations, not bearing external force during the curing period, and not less than 7d for the curing time; in order to facilitate construction lap joint, 30cm of height is reserved at the lower part of each layer of reinforcing mesh 12 and is not sprayed temporarily, the height is used for lap joint with concrete of the lower layer of reinforcing mesh 12, an inclined plane-shaped concrete section of 45 degrees is formed at the tail end of spraying, the thickness of the concrete sprayed at the gap 3 of the fender post ensures that the concrete surface is flush with concrete surfaces at other positions on the side wall of the foundation pit 4, after the spraying is finished, manual surface collection and smearing are carried out, and the flatness is based on the standard that a waterproof board laid subsequently is not influenced;

step twelve: and (3) removing the plastic cloth at the water outlet of the drainage pipe 10 after the concrete is sprayed, ensuring that the drainage pipe 10 normally discharges water, repeating the steps from two to eleven, continuously excavating the lower-layer foundation pit 4, crossing the underground pipeline 2 when encountering the underground pipeline 2, and then continuously performing the steps until the whole foundation pit 4 is completely excavated.

In the construction process, the selection of the channel steel types of the upper-layer channel steel 11 and the lower-layer channel steel 9 is mainly the selection of the thicknesses of the straw mat 6 and the bamboo plywood 7, and only the width of the channel steel can clamp the straw mat 6 and the bamboo plywood 7. The drilling area, the high-pressure rotary jet grouting pile 5 pulping area and the mixture stirring area are all provided with a spraying system to prevent dust; the high-pressure jet grouting pile 5 is completely used for pulping and dewatering by using a dewatering well, and tap water is strictly forbidden; the soil-retaining bamboo plywood 7 is made of leftover materials and turnover materials with the requirement on load strength; the straw mats 6 for water filtration are all used for using the old straw mats 6 paved at the entrance and exit of the construction site; the soil body and the materials of the exposed foundation pit 4 are covered by a green dense mesh net with the mesh number not less than 2000 before work; the construction site is fixed on the side wall of the foundation pit 4 by using an electric wire, a three-level power distribution two-level protection measure is adopted, and the electric brake box is locked in time; in the construction process, the surrounding structures and the foundation pit 4 are monitored and measured, the displacement and settlement change conditions are grasped in time, and countermeasures are taken.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. The construction process for excavation and support of the water-rich deep foundation pit fender pile gap is characterized by comprising the following steps of:

the method comprises the following steps: before constructing the fender post (1), exploring and digging the underground pipeline (2), determining the accurate position of the underground pipeline (2), then constructing the fender post (1), and finally forming a fender post gap (3) at the corresponding position of the underground pipeline (1);

step two: mechanically excavating a foundation pit (4) in layers, controlling the thickness of each layer to be 0.5-1m, and excavating a certain thickness from the position of the fender post gap (3) to the outer side;

step three: constructing a high-pressure jet grouting pile (5) which is horizontally arranged on the side wall at the position of the gap (3) of the fender pile;

step four: the method comprises the following steps that manual outward expanding excavation is continuously carried out on the position of a fender post gap (3) on the basis of mechanical excavation, the thickness of a soil body finally expanded and excavated outward meets the requirement that a straw curtain (6) and a bamboo rubber plate (7) can be placed, the soil body between two opposite fender posts (1) at the fender post gap (3) is cleaned, and the concrete side walls of the fender posts (1) at two sides are exposed;

step five: drilling holes in the opposite positions of the upper part and the lower part of the fender post (1) at two sides, implanting anchoring reinforcing steel bars (8), and extending the anchoring reinforcing steel bars (8) out of the pile surface of the fender post (1) by a certain length;

step six: lower-layer channel steel (9) crossing the retaining pile gap (3) is welded between anchoring steel bars (8) at the lower parts of the retaining piles (1) at two sides, and the notch of the lower-layer channel steel (9) faces upwards;

step seven: installing a grass curtain (6) and a bamboo plywood (7) in a lower layer channel steel (9), wherein the grass curtain (6) is close to the outer side of a foundation pit (4), the bamboo plywood (7) is close to the inner side of the foundation pit (4), the total thickness of the grass curtain (6) and the bamboo plywood (7) can be just clamped between two groove walls of the lower layer channel steel (9), the lengths of the bamboo plywood (7) and the grass curtain (6) are equal to the width of a fender post notch (3), and the heights of the bamboo plywood (7) and the grass curtain (6) are the downward digging thickness of each layer of the foundation pit (4);

step eight: drainage tubes (10) are embedded at two ends of the lower layer channel steel (9), water inlets of the drainage tubes (10) are positioned at the straw curtains (6), and the water inlets of the drainage tubes (10) are wrapped by water-permeable geotextiles; the outlet of the drainage pipe (10) extends into the foundation pit (4);

step nine: an upper layer channel steel (11) crossing the retaining pile gap (3) is welded between the anchoring steel bars (8) at the upper parts of the retaining piles (1) at two sides, the notch of the upper layer channel steel (11) faces downwards, and the upper ends of the grass curtain (6) and the bamboo plywood (7) are wrapped by the upper layer channel steel (11);

step ten: welding a steel bar mesh (12), wherein the steel bar mesh (12) is fixed with an upper layer channel steel (11) and a lower layer channel steel (9) which are close to one side of the foundation pit (4);

step eleven: concrete is sprayed on the steel bar net sheets (12) according to design requirements, a certain height is reserved at the lower part of each layer of steel bar net sheets (12) and is not sprayed temporarily, the concrete is lapped with the concrete of the lower layer of steel bar net sheets (12), and the thickness of the concrete sprayed at the gap (3) of the fender post ensures that the concrete surface is flush with the concrete surface at other positions on the side wall of the foundation pit (4);

step twelve: and repeating the second step and the eleventh step, continuously excavating the lower-layer foundation pit (4), crossing the underground pipeline (2) when the underground pipeline (2) is excavated, and then continuously performing the steps until the whole foundation pit (4) is completely excavated.

2. The excavation supporting construction process of the water-rich deep foundation pit fender pile gap according to claim 1, characterized in that in the third step, pile positions are arranged according to the pile forming diameter of the high-pressure jet grouting piles (5) of 0.5-0.6m, the pile length is 3-5m, the pile spacing of the same layer of high-pressure jet grouting piles (5) is 0.4-0.5m, and the layer spacing of the upper and lower layers of high-pressure jet grouting piles (5) is 0.4-0.5 m.

3. The excavation and support construction process for the water-rich deep foundation pit fender pile gap according to the claim 1, characterized in that in the fifth step, an electric hammer is adopted to drill holes on the side walls of the fender piles (1) at the two sides, the diameter of the drilled hole is 25-37mm, the depth of the drilled hole is 230-350mm, and impurities in the holes are removed immediately after the holes are drilled, so that the cleanness, the dryness and the absence of impurities in the holes are ensured; and (3) implanting the anchoring steel bar (8) into the drilled hole by using bar implanting equipment.

4. The excavation and support construction process for the water-rich deep foundation pit fender pile gap according to the claim 3, characterized in that in the fifth step, the diameter of the anchoring steel bar (8) is 20-28mm, and the length extending out of the pile surface of the fender pile (1) is 200-280 mm.

5. The excavation and support construction process of the water-rich deep foundation pit fender pile notch as claimed in claim 1, wherein in the seventh step, a grass curtain (6) is installed in a lower layer channel steel (9), the loose paving thickness of the grass curtain (6) is 200-250mm, and then a bamboo plywood (7) is installed, wherein the thickness of the bamboo plywood (7) is 10-22 mm.

6. The water-rich deep foundation pit fender pile gap excavation supporting construction process according to claim 1, characterized in that in step eight, the drainage tube (10) is a 10-15mm rubber tube, a water outlet of the drainage tube (10) is wrapped by plastic cloth for preventing concrete from blocking the water outlet, and after the concrete spraying in step eleven, the plastic cloth at the water outlet of the drainage tube (10) is removed to ensure that the drainage tube (10) normally discharges water.

7. The excavation and support construction process of the water-rich deep foundation pit fender pile gap according to the claim 1, characterized in that in the step ten, the reinforcing steel bar mesh (8) is welded into a grid structure of 100 x 100mm-150 x 150mm by using reinforcing steel bars with the diameter of 6-8mm, and a plurality of reinforcing steel bar sections with the length of 100mm are vertically welded on one side of the reinforcing steel bar mesh (8) facing the foundation pit (4), and the reinforcing steel bar sections are used for controlling the thickness of sprayed concrete.

8. The excavation and support construction process of the water-rich deep foundation pit fender pile gap according to the claim 7, characterized in that in the eleventh step, before the concrete is sprayed on the steel mesh sheet (12), a plurality of concrete cushion blocks are arranged between the bamboo plywood (7) and the steel mesh sheet (12).

9. The construction process for the gap excavation and support of the water-rich deep foundation pit fender pile according to any one of claims 1 to 8, characterized in that the upper layer channel steel (11) and the lower layer channel steel (9) are both C14-C20 channel steel.

10. The excavation and support construction process of the water-rich deep foundation pit fender pile gap according to claim 9, characterized in that the anchoring steel bars (8) are fully welded to the side edges of the upper layer channel steel (11) or the lower layer channel steel (9) respectively, and the welding seams are full.