CN108867690B - Reverse construction method for pile plate retaining wall of large foundation pit - Google Patents
Reverse construction method for pile plate retaining wall of large foundation pit Download PDFInfo
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- CN108867690B CN108867690B CN201811162974.4A CN201811162974A CN108867690B CN 108867690 B CN108867690 B CN 108867690B CN 201811162974 A CN201811162974 A CN 201811162974A CN 108867690 B CN108867690 B CN 108867690B
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D29/00—Independent underground or underwater structures; Retaining walls
- E02D29/02—Retaining or protecting walls
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D29/00—Independent underground or underwater structures; Retaining walls
- E02D29/02—Retaining or protecting walls
- E02D29/0258—Retaining or protecting walls characterised by constructional features
- E02D29/0275—Retaining or protecting walls characterised by constructional features cast in situ
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Abstract
The invention discloses a reverse construction method for a pile plate retaining wall of a large foundation pit, which comprises the following steps: s1, paying off and positioning on the ground to determine the position of the cast-in-place pile; s2, drilling a hole at the position of the cast-in-place pile line by adopting a rotary drilling mode; s3, hanging the bound reinforcement cages into the bored pile holes in the S2 one by one, and pouring concrete; s4, after the pile body strength of the cast-in-place pile reaches 75%, removing the template and excavating the side slope in steps according to design requirements; s5, after the side slope is excavated, drilling an anchor hole on the cast-in-place pile, and grouting and sealing the anchor hole after an anchor rod is installed in the anchor hole; s6, erecting a scaffold and connecting bars, and then binding reinforcing steel bars between adjacent cast-in-place piles; s7, spraying mortar on the steel bars and the cast-in-place piles bound in the step S6 to form retaining plates between the adjacent cast-in-place piles; and S8, excavating the next-stage foundation pit, and then repeating the processes in S5-S7 until the foundation pit is excavated to the set depth. The reverse construction method for the pile-plate retaining wall of the large foundation pit, which is disclosed by the invention, has the advantages of short construction period, high safety coefficient and small investment of the template.
Description
Technical Field
The invention relates to a construction process of a pile plate retaining plate, in particular to a reverse construction method of a pile plate retaining wall of a large foundation pit.
Background
In the civil engineering process, usually, a foundation pit needs to be excavated in a construction site, and a pile plate type retaining wall (for short, a pile plate retaining plate) is arranged at a side slope of the excavation of the foundation pit to maintain and reinforce the side slope of the foundation pit. Generally, a pile-plate type retaining wall is a reinforced concrete structure, and is composed of two parts, i.e., piles and retaining plates between the piles. The pile is partially anchored into the ground, its cross section is rectangular or circular, and its part is extended out of ground surface, and the soil-retaining plate can be made into precast slab, arch slab or cast-in-situ slab. During construction, the construction position of the retaining wall is determined according to geological exploration conditions, and the pile plate retaining wall is formed through the working procedures of positioning and paying off, drilling, hoisting of a reinforcement cage, concrete pouring, binding of retaining wall reinforcements, template manufacturing, retaining wall pouring and the like. In the process, the pile plate retaining plate is arranged after the foundation pit is excavated, so that collapse and other dangers are easily formed in the process of excavating the foundation pit. Meanwhile, when pouring the cast-in-place pile and the retaining wall, the cast-in-place pile needs to customize a steel template, the template is high in manufacturing cost and not easy to hoist, the retaining plate needs to be provided with a large number of templates for grouting forming, time and labor are wasted, and the requirement of the templates is large. Based on the reasons, the applicant considers that the collapse risk is reduced by adopting multilayer excavation and pouring the retaining plates layer by layer, the building difficulty and the quantity of scaffolds are reduced, meanwhile, the template of the cast-in-place pile is improved, the existing steel template is replaced by the multilayer wood template, the retaining plates are formed by adopting a cement spraying mode, the manufacturing cost and the building quantity of the template are reduced, and the construction period is shortened.
Disclosure of Invention
Aiming at the defects of the prior art, the technical problems to be solved by the invention are as follows: how to provide a reverse construction method for a pile plate retaining wall of a large foundation pit, which has short construction period, high safety factor and small investment of a template.
In order to solve the technical problems, the invention adopts the following technical scheme:
a reverse construction method for a pile-plate retaining wall of a large foundation pit is characterized by comprising the following steps: s1, drawing a design drawing of the pile plate retaining plate according to the geological survey report, and setting out and positioning on the ground according to the design position of the cast-in-place pile in the design drawing; s2, drilling a hole at the paying-off position of the cast-in-place pile in a rotary drilling mode, wherein the drilling depth is required to be 19-33m greater than the set depth of the foundation pit; s3, hanging the bound reinforcement cages into the drilled pile holes in the S2 one by one, installing templates on the reinforcement cages, and pouring concrete; s4, after the pile body strength of the cast-in-place pile reaches 75%, removing the template and excavating the side slope in steps according to design requirements; s5, after the side slope is excavated, drilling an anchor hole on the cast-in-place pile, installing an anchor rod in the anchor hole, grouting and sealing the anchor hole, and anchoring the cast-in-place pile on the side slope; s6, erecting a scaffold beside the side slope excavated in the S4, stripping soil and rocks between piles, arranging ribs beside the cast-in-place piles, and binding reinforcing steel bars between adjacent cast-in-place piles; s7, spraying mortar on the steel bars and the cast-in-place piles bound in the step S6 to form retaining plates between the adjacent cast-in-place piles; and S8, excavating the next-stage foundation pit, and then repeating the processes in S5-S7 until the foundation pit is excavated to the set depth. Therefore, when the foundation pit is excavated by adopting the construction method, the foundation pit is gradually excavated from top to bottom, before excavation, the edge of the foundation pit is stabilized by adopting the cast-in-place pile, meanwhile, the process of stepwise excavation and stepwise manufacturing of the retaining plate is adopted, and the anchor rod is arranged on the cast-in-place pile to anchor the cast-in-place pile, so that the position of the side slope is protected and fixed in the excavation process, the dangers of collapse and the like can not occur, and the safety coefficient of excavation of the foundation pit is improved. In addition, each step of soil retaining plate is formed by spraying mortar, so that the problems of high reinforcing difficulty, high cost, long period and the like of a single-sided template are solved, the investment of template and scaffold reinforcing is reduced, the cost is saved, and the construction period is shortened.
Furthermore, after the reinforcement cage of each cast-in-place pile is bound, before the formwork is installed, a steel pipe needs to be welded and fixed in the reinforcement cage and at the set position of the anchor hole, a wood plate is fixedly installed on the reinforcement cage and outside the steel pipe, the wood plate is tangent to the reinforcement cage, and the opening of the steel pipe is completely sealed; before drilling an anchor hole on a cast-in-place pile, finding out an embedded wood board by using a knocking and visual inspection method, chiseling off concrete above the wood board along the boundary of the wood board, and completely exposing the wood board, wherein the exposed position of the wood board is the set position of the anchor hole. Therefore, when the anchor hole is drilled, the wood plate is pre-embedded, so that the drilling position of the anchor hole can be accurately found, and meanwhile, the steel pipe is pre-arranged at the pre-embedded wood plate and the anchor hole correspondingly, so that the longitudinal stress steel bar and the stirrup of the pile body cannot be cut off in the drilling process. Meanwhile, the wood board can be cut into the waste templates, the construction cost cannot be increased, and the lower pipe and the pipe drawing of the grouting pipe are not affected by the aid of the device.
Furthermore, in S3, the two layers of templates on each reinforcement cage are respectively an inner-layer thin wood template and an outer-layer wood template, the thickness of the outer-layer wood template is 12-18mm, a plurality of vertical grooves are formed in the back of the outer-layer wood template at intervals along the height direction of the outer-layer wood template, and the outer-layer wood template can be pulled by external force to be bent into an arc shape or a circular shape. Like this, adopt two-layer plank sheathing to be used for the pile head shaping, not only can increase the thickness of template, make its intensity increase, simultaneously, adopt behind the two-layer plank sheathing, outer plank sheathing can not directly be connected with the concrete to, after the form removal, can not glue the concrete on the outer plank sheathing, can have enough to meet the need the use many times. Resource waste can not be caused, and the loss of wood is reduced, so that the construction is more environment-friendly. The outer-layer wood template made of wood has lower manufacturing cost compared with a steel template. Simultaneously, owing to seted up a plurality of vertical recesses on the plank sheathing to make the thickness of groove department plank sheathing reduce, can be crooked under the effect of external force, and then, make the plank sheathing can be crooked under the effect of external force, and be arc or circular, of course, the size of the strength that adopts when pulling according to the operator, can buckle into required radian with it, make the radian of template unanimous with the radian of pile head, the commonality can be higher. In addition, after the external force is released, the template can return to the initial state and is in a flat plate shape, and the turnover and the transportation are more convenient.
Furthermore, the left end face and the right end face of the outer-layer wood formwork are inclined planes, and the outer-layer wood formwork is bent into a round shape under the action of external force, and then the left end face and the right end face are tightly attached. Like this, vertical recess sets up evenly, and the interval is suitable to make the operator use less power just can pull the template, and the template department thickness that every vertical recess corresponds is unanimous, and the external force that receives is also unanimous, the bending more easily.
Further, in S5, an anchor rod is placed in each anchor hole, the anchor rod is composed of a plurality of anchor cables, spot welding is carried out between every two adjacent anchor cables at intervals of 1500mm, at least two steel bar supports are fixed at one end, close to the cast-in-place pile, of each anchor rod, and each steel bar support is in a shape like a Chinese character 'ji'. Like this, behind the fixed steel bar support on the stock, just can ensure that the stock is in the central point of anchor eye all the time and puts to the skew can not appear, it is more stable, and firm effect is better. After the anchor rod is composed of a plurality of anchor cables, the anchor rod is higher in strength and stronger in tensile resistance.
Further, grouting the anchor hole twice, wherein the grouting is mainly performed on the anchoring section for the first time, when the strength of the grouting body of the anchoring section reaches 100% of the design strength and the compressive strength of the anchor pier concrete reaches 30MPa, the anchor rod needs to be tensioned, and then the grouting is performed on the free section of the anchor rod; before secondary grouting of an anchor hole, an anchor backing plate is sleeved at the position of an anchor head, wherein the anchor backing plate consists of an outer backing plate, an inner backing plate and a triangular backing plate fixedly installed between the outer backing plate and the inner backing plate, one side of the outer backing plate is fixedly connected with one side of the inner backing plate, the opposite side of the fixed side of the outer backing plate is obliquely arranged outwards and is perpendicular to an anchor rod, and through holes for the anchor rod to penetrate through are formed in the outer backing plate and the inner backing plate; outside the anchor backing plate, a reinforcing steel bar net cover is fixed at the anchor head. Like this, the outer backing plate in the anchor backing plate is the slope form, and its structure is more firm, simultaneously, compares traditional flat steel sheet, and the reducible backing plate of above-mentioned anchor backing plate is beaten the picking of pile body concrete for the concrete protection layer of bored concrete pile does not receive destruction, has guaranteed the effective service life of structure. And the mode of twice slip casting to the anchor eye can ensure that the mortar in the anchor eye is closely knit, and is more stable with the anchor of bored concrete pile.
Further, before spraying mortar, a drain pipe and an expansion joint need to be arranged on the reinforcing steel bar bound by the S6, specifically, the drain pipe is made of a phi 100PVC pipe, each drain pipe is arranged in a plum blossom shape and is outwards inclined by 5%, and the distance between two adjacent drain pipes is 3000 mm; the expansion joint sets up along retaining soil board direction of height, and the interval between the adjacent expansion joint is not more than 20m, and each expansion joint seam is wide to be 30mm at least, inlays the polystyrene cystosepiment in the seam. Like this, after setting up the outlet conduit, can prevent that domatic infiltration from influencing shotcrete quality and dado are stable. And the expansion joint that sets up on retaining the native board can provide flexible space when retaining the native board and meet extreme weather, prevents to keep off native board fracture.
Furthermore, before pouring anchor head concrete, an anchor head mould is required to be manufactured according to the radian of a cast-in-place pile, the anchor head mould comprises a bottom mould and side moulds fixed on the bottom mould, one side of the bottom mould is arc-shaped, the radian of the side mould is consistent with that of the cast-in-place pile, the side moulds can be completely attached to the cast-in-place pile, the side moulds are provided with three side moulds, the bottoms of the three side moulds are fixedly connected with three edges outside the arc-shaped edge of the bottom mould, and the side moulds are U-shaped after being surrounded; before sealing the anchor, nailing supporting steel bars and fixing steel bars of a supporting anchor head mould into the upper position and the lower position of the anchor head of the cast-in-place pile, then placing the manufactured anchor head mould on the supporting steel bars, clamping and fixing the anchor head mould by using the fixing steel bars, simultaneously inserting wood wedges between the anchor head mould and the fixing steel bars, finally pouring anchor head concrete into the anchor head mould, finally setting the concrete, and removing the anchor head mould after the anchor head is formed. Therefore, after the anchor head die manufactured by the mode is used for pouring concrete, the anchor head is good in forming quality and attractive in appearance. After the anchor head concrete is poured and formed, the anchor head die can be detached to continue to be used in the next anchor head construction, and workers do not need to support again. All the formed anchor heads have the same size and shape, and the integral uniformity is good; the anchor head quantity of prestressing force pile slab fender board is very big under the general condition, adopts this anchor head mould after, can practice thrift engineering time, simultaneously greatly reduced construction cost.
Further, the concrete spraying operation is performed in a segmented and fragmented manner in sequence, and the spraying sequence is divided into secondary operation construction finished products from bottom to top; and after the sprayed concrete is finally set for 2 hours, spraying water for curing, wherein the curing time is determined according to the temperature and is preferably 3-7 days. Thus, after the segmentation, the fragmentation and the secondary operation are adopted, the operation can be avoidedRebound resilienceThe material covers the non-sprayed surface. And after the water spraying maintenance, the molding quality of the retaining plate is better.
Compared with the prior art, the reverse construction method for the pile-plate retaining wall of the large foundation pit, which is disclosed by the invention, has the following advantages:
1. before excavation, the foundation pit side slope to be excavated is primarily supported by the cast-in-place piles, meanwhile, during excavation, step excavation is adopted, the side slope position is protected and fixed by the step-by-step soil retaining plate manufacturing process, dangers such as collapse cannot occur, and the safety factor of excavation foundation pits is improved.
2. The retaining plates of all steps are formed by spraying mortar, so that the problems of high reinforcing difficulty, high cost, long period and the like of a single-sided template are solved, the investment of template and scaffold reinforcing is reduced, the cost is saved, and the construction period is shortened.
3. The pile head plank sheathing is provided with a plurality of vertical grooves at intervals, so that the pile head plank sheathing can be bent randomly to be arc-shaped or circular, the installation requirement of a template system of pile heads with random radian and random diameters can be met, and the universality is high. Meanwhile, the pile head wood template is made of wood, is low in manufacturing cost and high in strength, is flat after being disassembled and before being installed, and is very convenient to transport.
Drawings
FIG. 1 is a schematic cross-sectional reinforcement structure of a cast-in-place pile and a retaining plate in an embodiment;
FIG. 2 is a schematic view of the installation structure of the anchor rod and the anchor head in the embodiment;
FIG. 3 is a schematic diagram of a formwork mounting structure of an embodiment cast-in-place pile;
FIG. 4 is a schematic structural view of the outer layer wooden formwork after bending in the embodiment;
FIG. 5 is a schematic view of an installation structure of the pre-buried wood board in the embodiment;
FIG. 6 is a schematic structural diagram of an anchor head template in the embodiment.
In the figure: the cast-in-place pile comprises a cast-in-place pile 1, a reinforcement cage 11, anchor holes 12, anchor rods 13, steel pipes 14, wood boards 15, an inner-layer thin wood formwork 16, an outer-layer wood formwork 17, vertical grooves 18, anchor backing plates 2, outer backing plates 21, triangular backing plates 22, inner backing plates 23, a reinforcement mesh enclosure 3, a water drain pipe 4, expansion joints 5, polystyrene foam plates 6 and an anchor head mold 7.
Detailed Description
The invention is further illustrated with reference to the following figures and examples.
Example (b):
as shown in fig. 1 to 6, the reverse construction method of the pile-plate retaining wall of the large foundation pit provided in this embodiment includes the following steps: s1, drawing a design drawing of the pile plate retaining plate according to the geological survey report, and setting out and positioning on the ground according to the design position of the cast-in-place pile 1 in the design drawing; s2, drilling a hole at the paying-off position of the cast-in-place pile 1 in a rotary drilling mode, wherein the drilling depth is required to be 19-33m greater than the set depth of the foundation pit; s3, hanging the bound reinforcement cages 11 into the drilled pile holes in the S2 one by one, installing templates on the reinforcement cages 11, and pouring concrete; s4, after the pile body strength of the cast-in-place pile 1 reaches 75%, removing the template and excavating the side slope in steps according to the design requirements; s5, after the side slope is excavated, drilling an anchor hole 12 on the cast-in-place pile 1, installing an anchor rod 13 in the anchor hole 12, grouting and sealing the anchor hole 12, and anchoring the cast-in-place pile on the side slope; s6, erecting a scaffold beside the side slope excavated in the S4, stripping soil and rocks between the piles, arranging reinforcing bars beside the cast-in-place piles, and binding reinforcing bars between adjacent cast-in-place piles 1; s7, spraying mortar on the steel bars and the cast-in-place piles 1 bound in the step S6 to form retaining plates between the adjacent cast-in-place piles 1; and S8, excavating the next-stage foundation pit, and then repeating the processes in S5-S7 until the foundation pit is excavated to the set depth. It is to be noted that before the pile top is excavated, a temporary pile top drainage ditch needs to be arranged, and after the bottom foundation pit is excavated, a bottom drainage ditch is arranged in the foundation pit; the horizontal pitch error of adjacent anchor holes 12 should not be greater than 20mm, and the vertical pitch error should not be greater than 20 mm.
As shown in fig. 5, after the reinforcement cage 11 of each cast-in-place pile 1 is bound, before the formwork is installed, a steel pipe 14 needs to be welded and fixed at a set position of the anchor hole 12 in the reinforcement cage 11, and a wood plate 15 is fixedly installed on the reinforcement cage 11 and outside the steel pipe 14, the wood plate is tangent to the reinforcement cage 11, the length and width of the wood plate 15 are equal to the set diameter of the anchor hole 12, and the steel pipe opening is completely sealed; before drilling the anchor hole 12 on the cast-in-place pile 1, finding the pre-embedded wood board 15 by knocking and visual inspection, chiseling off concrete above the wood board 15 along the boundary of the wood board 15, and exposing the wood board 15 completely, wherein the exposed position of the wood board 15 is the set position of the anchor hole 12.
In the S3, two layers of templates are arranged on each reinforcement cage 11, namely an inner-layer thin wooden template 16 and an outer-layer wooden template 17, the thickness of the outer-layer wooden template 17 is 12-18mm, a plurality of vertical grooves 18 are arranged at intervals on the back surface of the outer-layer wooden template 17 along the height direction of the outer-layer wooden template, and the outer-layer wooden template 17 can be pulled by external force to bend into an arc shape or a circular shape (as shown in fig. 3 and 4) by taking any one of the vertical grooves 18 as an axis.
As shown in fig. 4, in order to ensure that the joint of the outer layer wooden mold plates 17 is smooth enough, the left end surface and the right end surface of the outer layer wooden mold plate 17 are both inclined surfaces, and the outer layer wooden mold plate 17 is bent into a circular shape under the action of external force, and then the left end surface and the right end surface are tightly attached.
In S5, an anchor rod 13 is placed in each anchor hole 12, the anchor rod 13 is composed of a plurality of anchor cables, spot welding is performed between every two adjacent anchor cables at intervals of 1500mm, at least two steel bar supports are fixed at one end of each anchor rod 13 close to the cast-in-place pile 1, and each steel bar support is in a shape of a Chinese character 'ji'.
Grouting the anchor hole 12 twice, mainly grouting the anchoring section of the anchor rod 13 for the first time, tensioning the anchor rod 13 when the grouting strength of the anchoring section reaches 100% of the design strength and the compressive strength of anchor pier concrete reaches 30MPa, and then grouting the free section of the anchor rod 13; before the anchor hole 12 is grouted for the second time, an anchor backing plate 2 is sleeved at the anchor head position, the anchor backing plate 2 consists of an outer backing plate 21, an inner backing plate 23 and a triangular backing plate 22 fixedly installed between the outer backing plate 21 and the inner backing plate 23, one side of the outer backing plate 21 is fixedly connected with one side of the inner backing plate 23, the opposite side of the fixed side of the outer backing plate 21 is obliquely outwards arranged and perpendicular to the anchor rod 13, and through holes for the anchor rod to pass through are formed in the outer backing plate 21 and the inner backing plate 23; outside the anchor backing plate 2, a reinforcing steel bar net cover 3 is fixed at the anchor head. Before concrete pouring, broken stones, mud and the like around the hole opening and on the building surface need to be removed, then reinforcing steel bars and vertical molds are bound, and meanwhile, longitudinal ribs, positioning pipes and fixed anchor backing plates 2 are installed. The anchor backing plate 2 can be used as an anchor pier end face template and fixed at the end part of the positioning pipe and is vertical to the axis of the positioning pipe.
Before the anchor rod 13 is placed and the anchor hole 12 is grouted, the anchor rod 13 is subjected to anti-corrosion treatment so as to prevent the anchor rod 13 from being corroded after being used for a long time and influence the stability of the cast-in-place pile 1. Specifically, the free section of the anchor rod is anticorrosive by adopting the following mode: after rust and oil removal, each steel strand is firstly coated with lubricating oil or anticorrosive paint on the surface of the anchor rod 13, then is wrapped with asphalt glass fiber cloth, is coated with lubricating oil or anticorrosive paint on the glass fiber cloth, is wrapped with the glass fiber cloth to form two-coating two-cloth, and is finally put into a plastic sleeve, and the plastic sleeve is filled with grease, so that double-layer corrosion prevention is finally formed; the free section is preferably a casing without a joint, and when the joint exists, the lap joint length of the joint is more than 50mm and the joint is sealed by using an adhesive tape; the anchoring section of the anchor rod 13 is preserved in the following way: after rust and oil removal of the steel strand, cement mortar is adopted for corrosion prevention, the anchor rod is required to be positioned in the middle of the anchor hole in construction, and the thickness of the cement mortar protective layer around the rod body is required to be not less than 35 mm.
Before spraying mortar, arranging a drain pipe 4 and an expansion joint 5 on a reinforcing steel bar bound by S6, specifically, the drain pipe 4 is made of a phi 100PVC pipe, each drain pipe 4 is arranged in a plum blossom shape and is outwards inclined by 5%, the distance between every two adjacent drain pipes 4 is 3000mm, and the distance between the lowest drain holes is 300 mm; the expansion joint sets up along retaining soil board direction of height, and the interval between the adjacent expansion joint is not more than 20m, and 5 seam widths at least for 30mm at each expansion joint inlay polystyrene cystosepiment 6 in the seam. In addition, in order to prevent the drain pipes 4 from being clogged, a gravel reverse filtering layer is filled on the side of each drain pipe 4 facing the soil slope, and at the same time, in order to prevent water flowing out of the drain pipe 4 from eroding the retaining plate, a clay water barrier layer with a thickness of at least 300 is tamped in the lower portion of the lowest drain pipe 4. During specific construction, the foundation of the anchor rib is embedded into the complete weathered rock with the depth not less than 600mm, and the buried depth of the soil retaining plate is more than 150 mm. The supporting layer of the base of the retaining base plate requires detailed construction drawings, and the stress of the base is rough. Before the construction of the retaining plate, surface drainage is carried out well to keep the foundation pit dry, after the foundation construction is finished, the foundation is backfilled and compacted in time to avoid water accumulation to soften the foundation, and the gravity type retaining plate wall body and wall back filling are carried out in a crossed mode to avoid the suspended fracture of the wall body. When the slope of the filling zone substrate is steeper than 1/5, the substrate is pressed into a position of 1: 2 (height-width ratio) is dug into steps, and the step width is not less than 1 m; the adverse slope gradient 1: 0.1.
as shown in fig. 6, before pouring anchor head concrete, an anchor head mold 7 needs to be manufactured according to the radian of a cast-in-place pile 1, the anchor head mold 7 comprises a bottom mold 71 and a side mold 72 fixed on the bottom mold, wherein one side of the bottom mold 71 is arc-shaped, the radian of the side is consistent with that of the cast-in-place pile 1, the side mold can be completely attached to the cast-in-place pile 1, the side mold 72 is provided with three pieces, the bottoms of the three pieces of side mold 72 are fixedly connected with three edges outside the arc-shaped edge of the bottom mold 71, and the three pieces of side mold are U-shaped after; before sealing the anchor, need to follow closely into the supporting reinforcement and the fixed reinforcement that support anchor head mould 7 on bored concrete pile 1, anchor head below position, then place the anchor head mould 7 made on the supporting reinforcement, and with the fixed reinforcing bar chucking fixed, insert the wood wedge between anchor head mould 7 and fixed reinforcement simultaneously, at last pour anchor head concrete into anchor head mould 7 again, and at the final setting of concrete, remove anchor head mould 7 after the anchor head shaping.
The concrete spraying operation is performed in a subsection and subsection mode in sequence, and the spraying sequence is from bottom to top so as to avoidRebound resilienceCovering the non-sprayed surface with the material, and performing secondary operation construction to obtain a finished product; and after the sprayed concrete is finally set for 2 hours, spraying water for curing, wherein the curing time is determined according to the temperature and is preferably 3-7 days.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the technical solutions, and although the present invention has been described in detail by referring to the preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention can be made without departing from the spirit and scope of the technical solutions, and all the modifications and equivalent substitutions should be covered by the claims of the present invention.
Claims (7)
1. A reverse construction method for a pile-plate retaining wall of a large foundation pit is characterized by comprising the following steps: s1, drawing a design drawing of the pile plate retaining plate according to the geological survey report, and setting out and positioning on the ground according to the design position of the cast-in-place pile (1) in the design drawing; s2, drilling a hole at the paying-off position of the cast-in-place pile (1) in a rotary drilling mode, wherein the drilling depth is required to be 19-33m greater than the set depth of the foundation pit; s3, hanging the bound reinforcement cages (11) into the drilled pile holes in the S2 one by one, installing templates on the reinforcement cages (11), and pouring concrete; s4, after the pile body strength of the cast-in-place pile (1) reaches 75%, removing the template and excavating the side slope in steps according to the design requirement; s5, after the side slope is excavated, drilling an anchor hole (12) in the cast-in-place pile (1), installing an anchor rod (13) in the anchor hole (12), grouting and sealing the anchor hole (12), and anchoring the cast-in-place pile (1) on the side slope; s6, erecting a scaffold beside the side slope excavated in the S4, stripping soil and rocks between piles, arranging reinforcing bars beside the cast-in-place piles, and binding reinforcing bars between adjacent cast-in-place piles (1); s7, spraying mortar on the steel bars and the cast-in-place piles (1) bound in the step S6 to form retaining plates between the adjacent cast-in-place piles (1); s8, excavating a next-stage foundation pit, and then repeating the processes in S5-S7 until the foundation pit is excavated to a set depth; the formwork on each steel reinforcement cage (11) is provided with two layers, namely an inner thin wood formwork (16) and an outer wood formwork (17), the thickness of the outer wood formwork (17) is 12-18mm, a plurality of vertical grooves (18) arranged along the height direction of the outer wood formwork (17) are arranged on the back of the outer wood formwork at intervals, and the outer wood formwork (17) can be pulled by external force to be bent into an arc shape or a circular shape; the left end face and the right end face of the outer-layer wood formwork (17) are inclined planes, and the outer-layer wood formwork (17) is bent into a round shape under the action of external force, and then the left end face and the right end face are tightly attached.
2. The reverse construction method for the pile-plate retaining wall of the large foundation pit according to claim 1, characterized in that after the reinforcement cage (11) of each cast-in-place pile (1) is bound, a steel pipe (14) is welded and fixed at the set position of the anchor hole (12) in the reinforcement cage (11) before the formwork is installed, a wood plate (15) is fixedly installed on the reinforcement cage (11) and outside the steel pipe (14), the wood plate is tangent to the reinforcement cage (11), and the wood plate (15) completely blocks the steel pipe opening; before drilling the anchor hole (12) on the cast-in-place pile (1), finding the pre-embedded wood board (15) by using a knocking and visual inspection method, chiseling concrete above the wood board (15) along the boundary of the wood board (15), and completely exposing the wood board (15), wherein the exposed position of the wood board (15) is the set position of the anchor hole (12).
3. The reverse construction method for the pile-plate retaining wall of the large foundation pit according to claim 1 or 2, wherein in S5, an anchor rod (13) is placed in each anchor hole (12), the anchor rod (13) is composed of a plurality of anchor cables, the adjacent anchor cables are spot-welded at intervals of 1500mm, at least two steel bar supports are fixed at one end of each anchor rod (13) close to the cast-in-place pile (1), and the steel bar supports are in a zigzag shape.
4. The reverse construction method for the pile-plate retaining wall of the large foundation pit according to claim 3, wherein the grouting of the anchor hole (12) is divided into two times, the first time is mainly to perform grouting on the anchoring section of the anchor rod (13), when the grouting strength of the anchoring section reaches 100% of the design strength and the compressive strength of the anchor pier concrete reaches 30MPa, the anchor rod (13) needs to be tensioned, and then the free section of the anchor rod (13) is grouted; before carrying out secondary grouting on the anchor hole (12), sleeving an anchor backing plate (2) at the anchor head position, wherein the anchor backing plate (2) consists of an outer backing plate (21), an inner backing plate (23) and a triangular backing plate (22) fixedly installed between the outer backing plate (21) and the inner backing plate (23), one side of the outer backing plate (21) is fixedly connected with one side of the inner backing plate (23), the opposite side of the fixed side of the outer backing plate (21) is obliquely arranged outwards and is perpendicular to the anchor rod (13), and through holes for the anchor rod to pass through are formed in the outer backing plate (21) and the inner backing plate (23); outside the anchor backing plate (2), a reinforcing steel bar mesh enclosure (3) is fixed at the anchor head.
5. The reverse construction method for the pile-plate retaining wall of the large foundation pit according to claim 3, wherein before spraying mortar, the drain pipes (4) and the expansion joints (5) are required to be arranged on the reinforcing steel bars bound by the S6, specifically, the drain pipes (4) are made of phi 100PVC pipes, each drain pipe (4) is arranged in a plum blossom shape and is 5% outward, and the distance between two adjacent drain pipes (4) is 3000 mm; the expansion joint sets up along retaining soil board direction of height, and the interval between the adjacent expansion joint is not more than 20m, and each expansion joint (5) seam width is 30mm at least, inlays polystyrene cystosepiment (6) in the seam.
6. The reverse construction method for the pile-plate retaining wall of the large foundation pit according to claim 3, wherein before pouring anchor head concrete, an anchor head mold (7) is manufactured according to the radian of the cast-in-place pile (1), the anchor head mold (7) comprises a bottom mold and side molds fixed on the bottom mold, one side of the bottom mold is arc-shaped, the radian of the side is consistent with that of the cast-in-place pile, the side molds can be completely attached to the cast-in-place pile, the side molds are provided with three blocks, the bottoms of the three side molds are fixedly connected with three edges outside the arc-shaped edge of the bottom mold, and the bottom molds are U-shaped after being enclosed; before sealing the anchor, need to follow closely into the support reinforcement and the fixed reinforcement that support the anchor head mould on bored concrete pile (1), the anchor head mould that then will make is placed on the support reinforcement to with the fixed reinforcing bar chucking fixed, insert the wooden wedge between anchor head mould and fixed reinforcement simultaneously, at last pour anchor head concrete into anchor head mould again, and at the final setting of concrete, remove anchor head mould after the anchor head shaping.
7. The reverse construction method for the pile-plate retaining wall of the large foundation pit according to claim 3, wherein the concrete spraying operation is performed in a segmented and segmented manner in sequence, the spraying sequence is from bottom to top to avoid the non-sprayed surface being covered by the resilient material, and the construction is divided into secondary operation finished products; and after the sprayed concrete is finally set for 2 hours, spraying water for curing, wherein the curing time is determined according to the air temperature and is 3-7 d.
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| CN111593809A (en) * | 2020-04-09 | 2020-08-28 | 中国水利水电第十四工程局有限公司 | Convenient preformed hole forming template |
| CN113653084A (en) * | 2021-08-10 | 2021-11-16 | 北京市市政一建设工程有限责任公司 | Cast-in-situ bored pile water stopping structure and cast-in-situ bored pile construction method |
| CN115404908A (en) * | 2022-10-10 | 2022-11-29 | 中铁二十二局集团第五工程有限公司 | Construction method of retaining wall between side slope upright piles |
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| CN106498950B (en) * | 2016-12-21 | 2018-11-30 | 大连交通大学 | Anchor head is placed in the implementation method of the Pile-Anchor Supporting for Deep Excavation system of pile body |
| CN107761744A (en) * | 2017-11-30 | 2018-03-06 | 华东建筑设计研究院有限公司 | A kind of continuous protective construction of bored concrete pile inter-pile soil |
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