阅读说明：本技术 一种富水深基坑围护桩缺口开挖支护施工工艺 (Excavation supporting construction process for water-rich deep foundation pit fender pile gap ) 是由 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 于 2020-05-15 设计创作，主要内容包括：本发明属于围护桩缺口支护技术领域,具体为一种富水深基坑围护桩缺口开挖支护施工工艺,解决了背景技术中的技术问题,其利用槽钢加竹胶板作为挡土板分层支挡土体,竹胶板侧还设有草帘,将槽钢锚固于两侧相邻的围护桩之间,之后挂网喷锚,随开挖深度分层加固直至基底。该施工工艺解决了城市主干道上由于地下管线众多无法迁改,或迁改费用较高、迁改时间较长而导致围护桩结构不能闭合的技术难题,减少了城市地下管线对城市地铁施工的影响,节约迁改时间及费用,缩短了施工工期,为后续施工提供了有利条件,围护桩缺口处施工可以与深基坑周边挂网喷锚平行作业,能保证安全有序的施工,提高了施工功效,操作简单,施工安全。(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.)

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.

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.