CN113774906A

CN113774906A - A kind of construction technology of expanding and introducing hole pouring filling mortar and implanting composite cross-section hollow pile

Info

Publication number: CN113774906A
Application number: CN202110864532.XA
Authority: CN
Inventors: 赵宇; 席进; 朱玉; 张�浩; 刘维正; 邵虎; 江磊; 张孝虹; 王伟; 姚孝虎
Original assignee: Central South University; Anhui Transport Consulting and Design Institute Co Ltd; Highway Traffic Energy Saving and Environmental Protection Technology and Equipment Transportation Industry R&D Center
Current assignee: Central South University; Anhui Transport Consulting and Design Institute Co Ltd; Highway Traffic Energy Saving and Environmental Protection Technology and Equipment Transportation Industry R&D Center
Priority date: 2021-07-29
Filing date: 2021-07-29
Publication date: 2021-12-10

Abstract

The invention provides a construction process for filling the expansion hole with filling mortar and implanting it into a hollow pile with a composite section. A hollow pile with a composite cross-section of the inner ring of the pipe pile and the filled outer ring is formed. The invention solves the problems of small prefabricated piles, insufficient stability, limited setting depth and end bearing conditions, and insufficient bearing capacity, etc., and can be applied to heavier loads, The bridge pier and pile foundation with complex nature has a wide application prospect.

Description

Construction process for implanting composite-section hollow pile by filling mortar into expanded lead hole

Technical Field

The invention belongs to the construction field of pile foundation engineering and foundation treatment, and particularly relates to a hollow pile with a composite section of an inner ring and an outer ring of a tubular pile, which is formed by filling mortar into a drilling machine expanding guide hole and filling a prefabricated tubular pile guide hole annular gap with slurry (mortar) discharged. The engineering application field is very wide.

Background

The precast tubular pile and the pile splicing technology thereof conform to the characteristics of modern intensive assembly construction, but the precast tubular pile is difficult to penetrate through weathered rocks and other hard rock-soil layers, and the pile sinking arrangement has serious soil discharge effect and other environmental adverse factors, thereby seriously restricting the engineering application.

In recent years, in high-grade highway construction, including a new round of highway widening and reconstruction project, the land for public roads is limited, the soil source of the roadbed is deficient, and the pile plate roadbed structure becomes a new roadbed form. The pile slab roadbed structure adopts a prefabricated pipe pile foundation, a pipe pile component assembled upright post and a prefabricated panel assembled driving pavement, and the construction intensification degree (speed, quality and the like) is obviously improved. However, when the precast tubular pile is encountered in hard rock-soil layers such as strongly weathered rocks, moderately weathered rocks and hard pebble gravelly soil, the pile sinking of the precast tubular pile is difficult. The high-power large-scale pile sinking equipment not only puts higher requirements on construction sites, but also aggravates the environmental influences such as the soil discharge effect, the noise and the like, and is sometimes even difficult to implement. At present, a small hole drilling and pre-leading technology is mostly adopted as a method for energy dissipation of precast pile sinking. On one hand, the power of pile sinking equipment can be reduced; on the other hand, the method is beneficial to accurate positioning of the plane of the foundation pile. However, when the energy dissipation method is applied to a hard rock soil layer such as a moderately weathered rock, the expected effect is difficult to achieve by the small lead hole energy dissipation method.

In view of the existing problems, the invention provides a construction process for implanting the composite section hollow pile of the precast tubular pile by expanding the guide hole, pouring and filling mortar and an application form thereof, and relevant documents, reports and regulations are not found. The cross section size effect of the prefabricated tubular pile composite cross section hollow pile matched with the expanding guide holes, the full cross section (medium weathered rock) rock embedding or (hard rock surface) supporting of the pile end and the like are achieved, the bearing capacity and stability of the foundation pile are remarkably improved, and the construction mode of the assembled upright post of the pile slab roadbed structure is kept. The expanding and guiding hole is matched with the large-diameter precast tubular pile to form a large-diameter hollow pile with a composite section, and the large-diameter hollow pile can also be used for a bridge abutment pile foundation.

Disclosure of Invention

The invention provides a composite section hollow pile for expanding a lead hole, filling and implanting filling mortar and a construction process thereof. The method comprises the following steps: drilling machine expands the guide hole, pours flowing solidified mortar, seals the tubular pile, injects mortar, and discharges the mortar to fill the annular gap between the tubular pile and the guide hole, so as to form the hollow pile with the composite cross section of the inner ring and the outer ring of the tubular pile.

The specific construction process comprises the following steps: measuring and paying off, and determining a pile position; expanding a lead hole of the rotary drilling rig; checking the quality of the formed hole; installing a positioning device; pouring mortar into the lead hole; filling mortar is implanted into the tubular pile; accurate positioning; and (5) naturally maintaining and recovering equipment.

In order to achieve the purpose, the invention adopts the following technical scheme:

a composite-section hollow pile with expanded leading hole filled with filling mortar is composed of a strong weathered and medium weathered hard rock-soil layer, a hollow pile filled with filling mortar, and a composite-section hollow pile with inner and outer tubular piles.

The further technology of the invention is as follows:

preferably, when the load of the pile top is small and the property is single, a hollow pile PHC-A or AB 500-600 low-strength small-diameter hollow pile is selected, the matched expanding hole DB is 700 mm-800 mm and is used as a pile foundation of a pile slab roadbed structure, and the section of the PHC pile is stably controlled by the upright post of the assembled tubular pile component.

Preferably, when the load of the pile top is heavier and the pile body is subjected to bending tension, the PHC B or C800-plus-1000 high-strength bending-tension large-diameter hollow pile is selected and matched with the large-diameter expanded lead hole hollow pile with the expanded lead hole DB larger than 1000mm to serve as the foundation of the bridge abutment pile.

Preferably, the pile top of the composite hollow pile is embedded into the bearing platform by 30-50 cm, the outer ring of the filling mortar is poured by a prefabricated mold, an annular notch with the depth of 3-5 cm is formed, and the notches are distributed at intervals along the pile body of the composite hollow pile.

Preferably, the outer core (mortar) ring sleeve is additionally provided with a circular stirrup restraint.

Preferably, filling mortar is implanted into the hollow pile in a suspending manner to form a pile body variable-section pile, a single-section tubular pile is implanted to form an upper composite-section hollow tubular pile, and a lower plain mortar pile variable-section pile is formed.

The large-diameter composite section hollow pile is formed by the cooperation of the expanded guide holes and the large-diameter hollow pile, the problems that the section of the precast pile is small and the stability is insufficient, the setting depth and the bearing capacity of the end bearing condition are limited are solved, the method can be applied to the bridge abutment pile foundation with heavy load and complex properties, and the application prospect is very wide.

Drawings

FIG. 1 is a schematic diagram of a composite cross-section hollow pile with an inner ring of a precast tubular pile and an outer ring of filled mortar and a construction process thereof.

Fig. 2 is a top view of the composite section hollow pile of the present invention.

FIG. 3 shows the application characteristics of the composite section hollow pile engineering of the present invention.

Fig. 4 is a close-up view of an engineering application E of the present invention.

Fig. 5 is an enlarged view of a portion of the present invention at engineering application F.

1, prefabricating a hollow pipe pile; 2, filling a mortar ring sleeve; 3, pipe pile joints; 4, sealing the pile shoe; 5, bearing platform; 6, anchoring the steel bars; 7, connecting reinforcing steel bars on the pile top; 8-inner core stirrup and 9-outer core stirrup.

Detailed Description

The present invention will be further illustrated with reference to the accompanying drawings and specific embodiments, which are to be understood as merely illustrative of the invention and not as limiting the scope of the invention. It should be noted that the terms "front," "back," "left," "right," "upper" and "lower" used in the following description refer to directions in the drawings, and the terms "inner" and "outer" refer to directions toward and away from, respectively, the geometric center of a particular component.

The invention provides a composite section hollow pile implanted with expanded lead holes and filled mortar and a construction process thereof, which meet the intensive construction development trend of the modern civil engineering industry. The main technical scheme is as follows:

as shown in the attached drawing 1, mortar is poured into the expanding and guiding holes, the mortar poured into the hole for embedding the sealed precast tubular pile fills annular gaps between the expanding and guiding holes and the tubular pile, the pile body mortar material strength is fully exerted, the filling mortar quality is improved, and the soil contact surface of the expanding and guiding hole pile is obviously hardened.

As shown in the accompanying drawings 2 and 3(A), when the pile top load is small and the property is single, a prefabricated pipe pile PHC-A or AB 500-plus 600 low-strength small-diameter prefabricated pipe pile is preferably selected, the cooperative expansion hole DB is 700 mm-800 mm and can be used as a pile foundation of a pile slab roadbed structure, and the section of the PHC pile can be stably controlled by an upright post of an assembled pipe pile component;

on the contrary, as shown in the accompanying drawings 2 and 3(B), when the pile top load is heavy and the pile body is pulled in a bending-resistant manner, the PHC B or C800-.

As shown in the accompanying drawings 2 and 3(C), the precast tubular pile can also be implanted with filling mortar in a suspending manner to form a pile body variable-section pile, and is suitable for implanting a large-diameter tubular pile when a deep-long expanded lead hole is formed, and implanting a single-section tubular pile to form a variable-section pile with an upper composite-section hollow tubular pile (bearing compression and bending resistance) and a lower plain mortar pile (bearing compression).

The invention is further explained by combining the abstract attached drawing and the attached drawing, and the concrete implementation scheme of the typical engineering application example of the invention is as follows:

embodiment example I-roadbed pile plate structure

The highway is located in the hilly valley area in the middle of Anhui, has thinner natural sediments along the highway, and mainly comprises argillaceous sandstone and tuff, and the downward lying (fully) strongly weathered rock and moderately weathered rock. Because the roadbed filled soil source is deficient, the roadbed is difficult to land acquisition, and the construction period of the project is short, the roadbed pile plate structure is adopted after the demonstration, and the accumulated mileage reaches 60 km.

Because the length of the pile in the surface deposited soil and the (total) strongly weathered layer is relatively short, the pile-column system based on the pile-plate structure is stable, the precast pile needs to enter the moderately weathered rock and even pass through the medium weathered layer, and the precast pile is difficult to directly set. According to the invention, the roadbed pile plate structure pile foundation is drilled and expanded with a rotary drill (DB is 700mm) to the depth of the medium weathering rock embedded rock or the surface of the weak weathering hard rock, a precast tubular pile (DP is 500mm) is implanted after filling of the filling mortar, and the annular gap is filled with the excitation discharge (mortar) slurry to form the composite section hollow pile.

Composite section hollow pile: the pre-hole solves the problem of difficult construction and workability of pile sinking of moderately weathered rocks; the size of the positive section of the hollow pile with the expanded guide hole, the filling and grouting composite section is increased, and the problem of stability of a pile system is solved. In addition, the volume of the annular clearance between the tubular pile and the expanded lead hole is combined with the filling coefficient, and the volume of the poured mortar is controlled, so that the poured mortar is called as filling mortar; the annular gap size is matched with the nominal upper limit particle size of the filled mortar aggregate, the fluidity working performance of the mortar aggregate can be controlled, and the pile sinking difficulty of mortar discharge (mortar) is reduced.

Assembling the column components: according to the attached figures 2 and 3(A) of the specification, after the pipe pile is implanted, when the filling mortar is hardened to reach the required age, the upright post of the pipe pile is assembled, and the upper driving pavement is installed. The hardening age of the filling mortar is close to the resting period after the arrangement of the slurry-discharging precast pile, and the basic characteristics of intensive and rapid construction of the pile slab roadbed are not influenced.

Quality control level: according to the attached figures 2 and 3(A) of the specification, the full-length implantation shock excitation setting effect of the sealing tubular pile is similar to that of vibration, and the quality of filling mortar in an annular gap is obviously improved compared with that of a common cast-in-place pile; the precast tubular pile and the pile splicing technology thereof are intensive and have obvious advantages of high quality.

Embodiment example II bridge pier foundation

Based on the engineering geological conditions, the bridge abutment foundation pile also adopts the composite section hollow pile implanted with the expanding guide hole and filled with the mortar.

According to the attached figures 2 and 3(B) of the specification, the pier pile foundation composite section hollow pile and the quality control characteristics thereof are the same as the pile slab roadbed. Because the pier foundation load is heavier, and there is the foundation pile stability problem, the relative oversize of the positive cross-section of compound cross-section hollow tube pile. For example, the precast tubular pile DP is 800mm, and the diameter of the reaming hole may be DB >1000mm to satisfy the load level and load property of the bridge abutment foundation.

Hollow pile and bearing platform connection structure (inner core): according to the specification and the attached figure 4, the pile top of the hollow pile with the composite cross section of the pier pile foundation is embedded into a bearing platform by 30-50 cm, the pile top is provided with a supporting plate and is placed into a steel bar framework, anchoring steel bars 6 and pile top connecting steel bars 7 are uniformly arranged along the circumference of the tubular pile, stirrups 8 are vertically arranged at equal intervals, the anchoring steel bars 6 and the pile top connecting steel bars 7 are firmly welded with the supporting plate, the size of the supporting plate is slightly smaller than the inner diameter of the tubular pile, the anchoring length of the anchoring steel bars 6 is taken according to the current specification, and the inner core of the tubular pile is filled with C50 micro-expansion concrete.

Hollow pile and bearing platform connection structure (outer core): according to the attached drawings of 5(a) and (b) of the specification, the pile top of the hollow pile with the composite section faces downwards 30-50 cm, the outer core mortar ring sleeve is poured by adopting a prefabricated mould, annular notches with the depth of 3-5 cm are formed in the outer core pile body, and the notches are distributed at intervals along the composite hollow pile body, so that the construction pouring integrity can be improved, the connection between the composite pile and the bearing platform is more effective, and the strength is higher compared with the traditional foundation pile embedded pouring bearing platform; meanwhile, the circular stirrups 9 are additionally arranged on the outer core of the large-diameter composite-section hollow pile, so that the bonding strength of the outer core can be improved, the shear resistance of the oblique section of the pile top of the composite-section hollow pile can be improved, and the upper horizontal load can be effectively transmitted to the pile body.

Tubular pile suspension variable cross section hollow pile: due to the fact that the load level is higher and the foundation pile is required to be stable, the diameter DB of the expansion hole is larger, and the underwater mortar pouring quality is easy to control; the depth of the expanded lead hole is deep, the cost of the large-diameter tubular pile is increased, and when the pile splicing process is complex, the suspension variable cross-section hollow pile can be adopted. According to the specification attached figure 3(C), the composite hollow tubular pile with the upper composite section and the composite pile with the lower variable section of the plain mortar pile can be formed by suspension implantation according to the upper limit value of the reference length of the large-diameter tubular pile, the load transfer characteristic that the bending tensile stress of the lower part of the bridge foundation pile is very small is met, in addition, the pile splicing process can be cancelled while the bearing capacity and the stability requirement are met, and the intensification degree is obviously improved.

In the above embodiment, the compound mortar mixing ratio and the physical and mechanical property indexes adopted in the construction process of filling mortar into the expanded pilot holes and implanting the composite cross-section hollow pile are shown in the following table.

The above detailed description of the present invention with reference to the embodiment of the present invention, which is made for the purpose of illustration and not limitation, and the construction process of the present invention, is provided for the purpose of composite cross-section hollow pile by grouting filling mortar, and it should be noted that: it will be apparent to those skilled in the art that several embodiments can be made without departing from the spirit and scope of the invention, and that various changes and modifications can be made without departing from the spirit and scope of the invention.

Claims

1. a construction technique of filling and filling mortar into the enlarging hole and implanting the composite section hollow pile, it is characterized in that: the enlarging hole passes through the hard rock and soil layer of strongly weathered and moderately weathered rock, and the hollow pile is implanted with filling mortar, and the soil is excited and drained. Filling the annular gap to form a hollow pile with a composite section of the inner ring of the pipe pile and the filled outer ring, which specifically includes the following steps:

(1) Measure and lay out the line to determine the pile position. After the site is leveled, install the rotary excavation sleeve integrated drilling rig, expand the diameter of the lead hole to the design hole diameter and the elevation of the pile bottom, and the outside diameter of the lead hole is larger than the outside diameter of the prefabricated pipe pile;

(2) The rotary drilling rig expands and guides the hole, which is characterized in that in the process of forming the hole, the top surface of the steel casing is connected with the rotary drilling rig through a flange, and the spinning of the drilling rig drives the steel casing to rotate downward into the soil; meanwhile, the drilling rig is in the steel casing. The soil borrowing is carried out inside the cylinder, and the extracted soil is transported to the outside of the borehole by the suction pump; the lead hole is enlarged relative to the diameter of the prefabricated pipe pile, and the lead hole enters into the medium weathered rock or passes through to the surface of the underlying hard rock, and the composite cross-section hollow pile has a full section at the end of the pile. Closed, forming rock-socketed piles in moderately weathered rock, or forming support piles on hard rock surfaces.

(3) After the lead hole is completed, the quality inspection of the hole forming is carried out;

(4) The drilling rig is displaced, and the positioning device is lowered into the drilling hole by a crane, and the outer edge of the positioning device is overlapped on the top surface of the steel casing;

(5) Put down a grouting conduit in the borehole, and pour mortar into the borehole to the design elevation through the conduit;

(6) The pipe pile is implanted with filling mortar, and the annular gap is filled by exciting soil dumping to form a composite cross-section hollow pile with an inner ring of the prefabricated pipe pile and an outer ring filled with mortar;

(7) Local accurate adjustment of the pile position through the positioning device;

(8) Carry out natural maintenance, control the maintenance time, recover the positioning device, and then pull out the steel casing.

2. according to the construction technique of a kind of reaming hole filling mortar implantation composite section hollow pile described in claim 1, it is characterized in that: when the pile top load is less and the property is single, select the hollow pile PHC-A or AB 500-600 low-strength, small-diameter hollow piles, with cooperating expansion holes DB=700mm~800mm, are used as pile foundations for pile-slab roadbed structures, and the prefabricated pipe piles are used to stably control the PHC pile section.

3. according to the construction technique of a kind of reaming hole filling mortar implantation composite section hollow pile described in claim 1, it is characterized in that: when the pile top load is heavy and the pile body is resistant to bending and pulling, select PHC B or C 800-1000 high-strength bending-resisting large-diameter hollow piles, cooperating with expanded guide holes DB>1000mm large-diameter expanded guide-hole hollow piles, are used as bridge pier pile foundations.

4. A construction technique for implanting composite cross-section hollow piles with enlarging holes and filling mortar according to claim 1, characterized in that: the pile top of the composite hollow piles is embedded in a cap of 30 to 50 cm, and the filling mortar outer ring is prefabricated The mould is poured to form annular grooves with a depth of 3 to 5 cm. The grooves are distributed along the composite hollow pile body at intervals. The inner core of the pipe pile is placed with inserts and concrete is poured. The bridge pier pile foundation and the cap are connected to the construction integrity and internal force transmission significantly enhanced.

5 . The construction technique for implanting composite cross-section hollow piles with enlarging holes and filling mortar according to claim 4 , wherein the outer core ring sleeves are restrained by adding circular stirrups. 6 .

6. the construction technology of a kind of expansion hole filling mortar implantation composite section hollow pile according to claim 1, it is characterized in that: hollow pile is suspended and implanted filling mortar to form pile body variable section pile, single-section pipe pile It is implanted to form the upper composite section hollow pipe pile and the lower part of the variable section pile of the plain mortar pile.

7. The construction technology of a kind of enlarging hole filling mortar implanting composite cross-section hollow pile according to claim 1, it is characterized in that: the composite mortar performance index used in the pile planting process comprises, the composite mortar material 425 cement , Class II fly ash, sand mix ratio of 1:0.7:7 ~ 1:0.6:3, frustum flow degree ≥ 200mm, bleeding rate 0%, 28d compressive strength ≥ 25MPa.