CN111502328B - An anchoring structure for brick-clad city wall ruins based on EBTP anchor rods - Google Patents
An anchoring structure for brick-clad city wall ruins based on EBTP anchor rods Download PDFInfo
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- CN111502328B CN111502328B CN202010479174.6A CN202010479174A CN111502328B CN 111502328 B CN111502328 B CN 111502328B CN 202010479174 A CN202010479174 A CN 202010479174A CN 111502328 B CN111502328 B CN 111502328B
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- 229920000647 polyepoxide Polymers 0.000 claims description 11
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Classifications
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G23/00—Working measures on existing buildings
- E04G23/02—Repairing, e.g. filling cracks; Restoring; Altering; Enlarging
- E04G23/0218—Increasing or restoring the load-bearing capacity of building construction elements
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/24—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing alkyl, ammonium or metal silicates; containing silica sols
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G23/00—Working measures on existing buildings
- E04G23/02—Repairing, e.g. filling cracks; Restoring; Altering; Enlarging
- E04G23/0218—Increasing or restoring the load-bearing capacity of building construction elements
- E04G23/0222—Replacing or adding wall ties
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00637—Uses not provided for elsewhere in C04B2111/00 as glue or binder for uniting building or structural materials
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Architecture (AREA)
- Structural Engineering (AREA)
- Ceramic Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Organic Chemistry (AREA)
- Electrochemistry (AREA)
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- Civil Engineering (AREA)
- Piles And Underground Anchors (AREA)
Abstract
本发明公开了一种基于EBTP锚杆的包砖城墙遗址锚固结构，包括EBTP锚杆和包砖墙体；钢筋贯穿于楠竹管材中，钢筋长度大于楠竹管材长度，钢筋贯穿于楠竹管材段伸入至城墙的夯土内锚固段，钢筋延伸出楠竹管材段伸入至包砖内锚固段，钢筋贯穿出包砖墙体外端面通过螺栓和锚板固定；扩体锚节设在楠竹管材内的钢筋中段，且位于包砖墙体承压段和受拉段之间。通过多种传力模式的转化实现临界锚固长度的成倍增加和极限抗拔承载力的大幅提升，该结构能够满足包砖城墙、夯土城墙等大型夯土遗址结构的锚固需求。
The invention discloses a brick-clad city wall ruins anchoring structure based on EBTP anchor rods, comprising EBTP anchor rods and brick-clad walls; steel bars are inserted into bamboo pipes, the length of the steel bars is greater than the length of the bamboo pipes, the steel bars are inserted into the bamboo pipe sections and extended into the anchoring sections in the rammed earth of the city wall, the steel bars extend out of the bamboo pipe sections and extend into the anchoring sections in the brick-clad walls, the steel bars are inserted out of the outer end face of the brick-clad walls and fixed by bolts and anchor plates; the expanded anchor section is arranged in the middle section of the steel bars in the bamboo pipes, and is located between the pressure section and the tension section of the brick-clad walls. The critical anchoring length is multiplied and the ultimate pull-out bearing capacity is greatly improved through the transformation of multiple force transmission modes, and the structure can meet the anchoring requirements of large rammed earth ruins structures such as brick-clad city walls and rammed earth city walls.
Description
Technical Field
The invention belongs to the technical field of rammed earth building site reinforcement and protection, and particularly relates to a wall site anchoring structure of a brick-covered urban wall based on EBTP anchor rods, which is used for enhancing the stability and shock resistance of a large rammed earth site structure of the brick-covered urban wall and the like.
Background
The brick-covered urban wall is taken as a typical historical building remains with huge scale, huge stock and wide distribution in China, and is aggregated with the superelevation of ancient people's building concepts and exquisite building skills, is the shadow map of the bright historical civilization and cultural root veins in China, and has extremely high scientific significance and social value. The brick-covered urban wall mainly comprises internal rammed earth and external brick-covered bricks, and is high in size in ancient times due to the fact that the brick-covered urban wall is mainly used for military defense functions, the ductility of the internal rammed earth and the external brick-covered materials is poor, the strength difference of the two materials is large, the masonry time is different, the deformation of the internal rammed earth and the masonry time is difficult to coordinate, and the internal rammed earth and the external brick-covered materials are not subjected to earthquake-resistant structural design during construction, so that the structure is extremely easy to slip, collapse and other damage under the action of external forces such as earthquakes, and the historic cultural information carried by the historic cultural relics are permanently lost. Aiming at the problem, cultural relics protection workers mainly adopt an anchoring technology to invisibly enhance the stability according to the reinforcing principle of safety first, minimum intervention and no change of original appearance, namely, the anchor rod is drilled and implanted on the surface of the site, and anchoring slurry is injected into the hole to bond the anchor rod with the site body, thereby playing the roles of pulling up dangerous bodies and stabilizing bodies and avoiding the unstable damage of the site.
The rammed earth building site has the dual properties of the building and the cultural relics, the metal anchor rods (such as reinforcing steel bars and the like) commonly used in the traditional rock-soil slope anchoring engineering are not suitable for rammed earth site anchoring, and are particularly characterized in that 1, the metal anchor rods are easy to react with moisture to cause rust damage, so that the durability is poor, the service life of the rammed earth building site is very short compared with that of the cultural relics, 2, the strength difference between the metal anchor rods and rammed earth materials is large, the deformation of the metal anchor rods and the rammed earth materials is difficult to coordinate, the tensile property of the metal anchor rods cannot be fully exerted, 3, the cement mortar matched with the metal anchor rods is easy to chemically react with the rammed earth materials of the cultural relics, the compatibility of the cement mortar and the rammed earth materials of the cultural relics is poor, and 4, the prestress technology is strictly limited to be used for protecting the cultural relics.
In view of this, the literature and insurance workers are based on the investigation of the performance of the wood materials in the rammed earth building, through long-term exploration practice, the consensus that the seismic stability of rammed earth sites is enhanced by a method of combining bamboo and wood materials with a non-prestress anchoring technology is finally achieved, rammed earth site anchor rods which are made of natural materials such as 'nanzhu anchor rods', 'wax wood anchor rods' and the like are researched and developed, however, a great deal of practical experience shows that although the anchor rods made of the natural bamboo and wood materials can effectively solve the compatibility problem and the durability problem of rod bodies and sites, the following defects still exist:
(1) The tensile strength of the common bamboo and wood rod is lower, the shear strength of the anchoring slurry used in cooperation is generally only slightly higher than that of the rammed soil body, and the bonding performance of an anchoring interface is poor, so that higher anchoring force is difficult to provide, and the requirement of anchoring large urban wall sites cannot be met.
(2) The existing site anchoring mode is mainly full-length bonding tension type, the stress distribution of the interface of the anchoring system is extremely uneven, the high stress area is mainly concentrated near the orifice, the bonding strength of the interface at different anchoring depths can not be fully exerted, the effective anchoring length is short, and the anchoring efficiency is low.
(3) The common bamboo-wood anchor rod has a simple structure, and is difficult to select proper anchoring agents according to the performances of different anchoring materials, so that the bonding strength of different anchoring sections is exerted to the maximum extent, and therefore, the anchor rod is not fully applicable to sites containing different materials such as brick-covered urban walls, such as brick-covered bricks, rammed earth and the like.
In summary, the metal anchor rods commonly used for anchoring the traditional rock-soil slope and the bamboo-wood anchor rods commonly used for anchoring the current rammed earth site cannot well meet the anchoring requirements of the brick-covered urban wall site.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide the brick-covered urban wall site anchoring structure of the expanded bamboo reinforcement pulling-pressing composite anchor rod (called EBTP anchor rod for short) suitable for large rammed earth sites such as urban walls and the like (especially for brick-covered urban wall sites), and solve the problems that the existing metal anchor rod is poor in durability and compatibility, the natural bamboo-wood anchor rod is low in pulling-resistant bearing capacity, concentrated in anchoring interface stress, insufficient site anchoring force is easily caused, local premature damage is easily caused and the like. The conversion of multiple force transmission modes realizes the multiple increase of critical anchoring length and the great improvement of ultimate pulling-resistant bearing capacity, and the performance advantages of different materials can be fully exerted through a zonal grouting technology.
The invention is realized by the following technical scheme.
A wall site anchoring structure of a brick-covered urban wall based on EBTP anchor rods comprises EBTP anchor rods and a brick-covered wall body, wherein each EBTP anchor rod comprises reinforcing steel bars, anchor plates, phyllostachys pubescens tubular products and expanded anchor joints, the reinforcing steel bars penetrate through the phyllostachys pubescens tubular products, the length of the reinforcing steel bars is larger than that of the phyllostachys pubescens tubular products, the reinforcing steel bars penetrate through the phyllostachys pubescens tubular products and extend into rammed earth anchoring sections of the urban wall body, the reinforcing steel bars extend out of the phyllostachys pubescens tubular products and extend into the brick-covered anchoring sections, the outer end faces of the reinforcing steel bars penetrating out of the brick-covered wall body are fixed through bolts and the anchor plates, the expanded anchor joints are arranged in reinforcing steel bar middle sections in the phyllostachys pubescens tubular products, and the expanded anchor joints are located between the brick-covered wall body bearing sections and the tension sections.
For the above technical solution, the present invention is further preferred:
further, the inner anchoring section of the brick is formed by bonding reinforcing steel bars of EBTP anchor rods with the brick from an anchor plate to reinforcing steel bar sections extending out of the phyllostachys pubescens pipe by cement mortar from the outer facade orifice of the brick wall to the interface between the brick wall and the rammed earth body.
The cement mortar is prepared by mixing cement and medium sand according to the mass ratio of 15:85 with water, wherein the water-cement ratio is 0.29.
Further, the rammed earth inner anchoring section is formed by bonding the outer surface of the phyllostachys pubescens pipe section which penetrates through the reinforcing steel bars with the rammed earth body by adopting modified slurry from the interface of the brick-covered wall body and the rammed earth body to the bottom end of the anchor hole.
The modified slurry is prepared by mixing scattered soil of a site, cement, fly ash and glutinous rice slurry with 5% silica sol, wherein the mass ratio of the components is 60:20:10:10, and the cement ratio is 0.31.
Furthermore, epoxy resin glue is poured into the tension Duan Nanzhu pipe to glue the inserted steel bars, and epoxy resin glue is not poured into the pressure-bearing Duan Nanzhu pipe.
Further, the expanded anchor joint comprises a bearing plate and a triangular support body, wherein the bearing plate is welded vertically along the radial direction of the steel bar, the triangular support body is fixedly connected with the bearing plate and the steel bar along the axial direction of the steel bar respectively, and a plurality of circular grouting holes are formed in the bearing plate.
Further, a longitudinal sliding groove penetrating through the triangular support body is formed in the middle section of the phyllostachys pubescens pipe.
Furthermore, the EBTP anchor rods are uniformly distributed along the outer vertical surface of the brick-covered wall body or gradually distributed in an encrypted manner from bottom to top along with the height of the wall.
Further, EBTP anchor rods are distributed along the outer vertical surface of the brick-covered wall body in a quincuncial shape, and the adjacent rows and the rows of EBTP anchor rods are staggered by 1/3-1/2 of the distance between the anchor rods.
Further, the EBTP anchor rod penetrates into the brick wall body, forms an included angle of 10-30 degrees with the horizontal plane, and is inserted obliquely downwards.
Further, the expansion anchor joints between the adjacent EBTP anchor rods are arranged at different depths in the rammed earth in a staggered mode, and the axial distance is 1/2-1/5 of the length of the anchor section in the rammed earth.
Due to the adoption of the technical scheme, the invention has the following beneficial effects:
according to the invention, the expanded bamboo rib pulling and pressing composite anchor rod (EBTP anchor rod) with multi-ring-layer and multi-anchoring section structural characteristics is formed by additionally arranging the reinforcing steel bars and the expanded anchor sections on the basis of the traditional phyllostachys pubescens anchor rod, so that the anchor rod not only can ensure higher pulling-resistant bearing capacity of an anchoring system and lower peak stress level of an anchoring interface, but also can solve the problems of low durability of a metal rib body and compatibility of the metal rib body with a soil body.
The main technical problem that this scheme can solve includes:
(1) The rammed earth internal anchoring section is divided into the shallow pressure-bearing section and the deep tension section, so that the critical anchoring length can be increased by times, the shearing resistance of anchoring interfaces at different anchoring depths can be fully exerted, the anti-pulling bearing capacity of the anchor rod is greatly improved, and the problems of low strength and limited anti-pulling bearing capacity of the bamboo-wood anchor rod are solved.
(2) The expanded anchor can effectively improve mechanical engagement force and reduce interface slippage, and meanwhile, the local interface bonding strength of adjacent anchor rods is improved through disturbance compaction of soil mass around the anchor rods, so that the loss of anchoring efficiency caused by group anchoring effect is compensated, and the performance of an anchoring system is further improved.
(3) The method adopts a partitioned grouting (in-brick and rammed earth) technology and a multi-ring layer structure (steel bar/phyllostachys) structure, not only can optimize the performance of an internal anchoring section by selecting proper anchoring slurry according to the material characteristics, but also can ensure the deformation coordination and durable compatibility of the anchor rod and the site.
As EBTP anchor rods adopt the structural characteristics, and the working principle of the anchor rods is combined, the invention has the following advantages:
1) The shearing action of the modified slurry of the pressure-bearing section in the rammed earth and the interface of the rammed earth body and the shearing action of the outer surface of the tension Duan Nanzhu and the interface of the modified slurry can jointly resist the axial load of the anchor rod caused by the displacement of the brick-covered wall body, so that the critical anchoring length of the anchoring section in the rammed earth is the sum of the critical anchoring length of the pressure-bearing section and the critical anchoring length of the tension section;
2) The embedding effect of the expanded anchor joint increases mechanical biting force, reduces the slippage of the anchor rod relative to the rammed soil body, and further limits the relative displacement of the brick-covered wall body and the rammed soil body, so that the brick-covered wall body and the rammed soil body are firmly tied;
3) Soil particles caused by displacement of the expanded anchor joint are moved and compacted, so that the peripheral soil pressure born by adjacent anchor rods is increased, the bonding strength of an anchoring interface and the ultimate anti-pulling bearing capacity of the anchor rods are improved, a cooperative reinforcement mechanism is presented between the adjacent anchor rods, and the performance of an anchoring system is further improved;
4) The brick-covered wall body and the rammed earth body are respectively subjected to regional grouting by adopting cement mortar and modified slurry anchoring agent, so that the performance advantages of materials with different strengths can be fully exerted;
5) The stress transfer between the reinforcing steel bars and the rammed soil body is excessive through the phyllostachys pubescens pipe, so that the interior moisture of rammed soil and the reinforcing steel bars are blocked by phyllostachys pubescens to react to cause rust damage, the problem of poor durability of the reinforcing steel bars is solved, the stress of the reinforcing steel bars can be gradually transferred into the rammed soil body through phyllostachys pubescens and anchoring agents, the problem that deformation of each material is difficult to coordinate due to overlarge strength difference is avoided, the stress can be uniformly dissipated in a site soil body, and the safety of the site body is further guaranteed.
In conclusion, compared with natural bamboo-wood anchor rods and metal anchor rods, the EBTP anchor rods have remarkable stress performance advantages in reinforcing and protecting the brick-covered urban wall sites. The structure can meet the anchoring requirement of large rammed earth site structures such as brick-covered urban walls, rammed earth urban walls and the like.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and constitute a part of this specification, are incorporated in and constitute a part of this specification and do not limit the application in any way, and in which:
FIG. 1 is a schematic illustration of the construction of EBTP bolt of the present invention;
FIG. 2 is a cross-sectional view A-A of the present invention at EBTP anchor joints;
FIG. 3 is a cross-sectional view of EBTP bolts installed in a brick-covered urban wall;
fig. 4 is a connection diagram of the expanded anchor section and the reinforcing steel bar;
FIG. 5 is a schematic diagram of a phyllostachys pubescens pipe wall slotting;
FIG. 6 is a schematic diagram of a two-sided support type carrier plate connected to a support body;
FIG. 7 is a schematic diagram of a four-sided support type carrier plate connected to a support body;
FIG. 8 is a plan view of a two-sided support type carrier plate and support body connection;
FIG. 9 is a plan view of a four-sided support carrier plate connected to a support body;
FIG. 10 is a plan view of EBTP bolts in an exterior elevation of a town wall;
FIG. 11 is a schematic representation of the relative positions of anchor joints of each EBTP anchor rod in a town wall.
In the figure, M.EBTP anchor rods, 1 part of reinforcing steel bars, 2 parts of phyllostachys pubescens pipes, 3 parts of bearing plates, 3-1 parts of grouting holes, 3-2 parts of reinforcing steel bar insertion holes, 4 parts of triangular supporting bodies, 4-1 parts of welding seams, 5 parts of epoxy resin glue, 6 parts of modified slurry, 7 parts of cement mortar, 8 parts of urban wall ramming soil, 9 parts of brick-covered walls, 10 parts of cavities, 11 parts of bamboo joints, 12 parts of anchor plates, 13 parts of bolts, 14 parts of brick-covered walls and rammed soil body interfaces, 15 parts of longitudinal sliding grooves, 16 parts of brick-covered inner anchoring sections, 17 parts of rammed soil inner anchoring sections, 18 parts of bearing sections, 19 parts of tension sections and 20 parts of brick-covered urban wall outer vertical surfaces.
Detailed Description
The present invention will now be described in detail with reference to the drawings and the specific embodiments thereof, wherein the exemplary embodiments and descriptions of the present invention are provided for illustration of the invention and are not intended to be limiting.
As shown in fig. 1 and 2, the EBTP anchor rod M mainly comprises a reinforcing steel bar 1, a phyllostachys pubescens pipe 2, epoxy resin glue 5, an anchor plate 12, a bolt 13 and an expanded anchor joint, wherein the expanded anchor joint comprises a bearing plate 3 and a triangular support body 4. Wherein, the bearing plate 3 of the expanded anchor joint is perpendicular to the axial direction of the steel bar 1, and the two bearing plates are welded and fixed by two right-angle edges of the triangular support body 4 connected with the steel bar 1. As shown in fig. 2 and 4, the bearing plate 3 and the triangular support body 4 are mutually and vertically fixed through a welding seam 4-1, wherein one of two right-angle sides of the triangular support body 4 is welded with the surface of the steel bar 1, the other is welded with the surface of the bearing plate 3, and symmetrically distributed grouting holes 3-1 are formed in the bearing plate 3 and are used for inserting grouting pipes to inject modified slurry into gaps between the phyllostachys pubescens and rammed earth at the rear part of the anchor joint. The cross section of fig. 2 is sequentially provided with a reinforcing steel bar 1, epoxy resin glue 5, a phyllostachys pubescens pipe 2 and a bearing plate 3 from the center to the outside.
As shown in fig. 1,2 and 3, in the anchor structure of the brick-covered urban wall site, the reinforcing steel bars 1 are inserted into the phyllostachys pubescens pipe 2 which opens the bamboo joints 11 in a centering manner, wherein the length of the reinforcing steel bars 1 is greater than that of the phyllostachys pubescens pipe 2, and the reinforcing steel bars 1 penetrate through the phyllostachys pubescens pipe 2 section and extend into the brick-covered wall.
According to the force transmission mode and the force bearing characteristic of the anchor rod, the whole length of the anchor rod can be divided into 2 anchor segments, namely 1) the anchor segments in the brick-covered wall body from the opening of the outer vertical surface of the brick-covered wall body to the interface between the brick-covered wall body and the rammed earth body, and 2) the anchor segments in the rammed earth body from the interface between the brick-covered wall body and the rammed earth body to the bottom end of the anchor hole. The rammed earth body internal anchoring section comprises two force transmission modes, namely 1) a pressure-bearing anchoring section from the brick-covered wall body and rammed earth body interface 14 to the expanded body anchoring section, and 2) a tension anchoring section from the expanded body anchoring section to the bottom end of the anchor hole.
The reinforcing steel bar 1 penetrates through the phyllostachys pubescens pipe 2 section and stretches into the rammed earth inner anchoring section 17 of the urban wall, the phyllostachys pubescens pipe section extending out of the reinforcing steel bar 1 stretches into the brick-covered inner anchoring section 16, the brick-covered inner anchoring section 16 is formed by bonding cement mortar 7 from the brick-covered wall outer vertical face orifice to the brick-covered wall body and rammed earth body interface, and the reinforcing steel bar 1 of EBTP anchor rods is bonded with the brick from the anchor plate 12 to the phyllostachys pubescens pipe reinforcing steel bar section extending out of the brick-covered body. The rammed earth inner anchoring section 17 is formed by bonding the outer surface of the phyllostachys pubescens pipe section which penetrates through the reinforcing steel bars with the rammed earth body by adopting the modified slurry 6 from the interface of the brick-covered wall body 9 and the rammed earth body to the bottom end of the anchor hole. The reinforcing steel bar penetrates through the outer end face of the brick-covered wall body 9 and is fixed through bolts 13 and anchor plates 12, the expanded anchor joint is arranged in the reinforcing steel bar middle section in the phyllostachys pubescens pipe 2, and the expanded anchor joint is arranged between the brick-covered wall body pressure-bearing section 18 and the tension section 19. In the brick-covered internal anchoring section 16, the reinforcing steel bars 1 are not wrapped by the phyllostachys pubescens pipe 2, in the rammed earth internal anchoring section 17, the middle of the reinforcing steel bars 1 of the front bearing section 18 and the phyllostachys pubescens pipe 2 is a non-bonded cavity 10, the reinforcing steel bars 1 of the rear tension section 19 and the phyllostachys pubescens pipe 2 are bonded through the whole length of the epoxy resin glue 5, and the junction of the bearing section 18 and the tension section 19 is provided with an expansion anchor joint.
As shown in fig. 3, EBTP the connection relation of the anchor rod M in the brick-covered urban wall is that the steel bar 1 in the anchor section 16 in the brick-covered urban wall is adhered to the brick-covered urban wall 9 through cement mortar 7, the phyllostachys pubescens pipe 2 in the anchor section 17 in the rammed earth is adhered to the rammed earth 8 of the urban wall through modified slurry 6, and when the EBTP the anchor rod M is installed, an anchor plate 12 is installed on the outer surface of the urban wall for sealing, and the steel bar 1 and the anchor plate 12 are fixed by bolts 13.
As shown in fig. 1 and 5, the bamboo joints 11 inside the phyllostachys pubescens pipe 2 are all open except the last section so as to insert reinforcing steel bars in the phyllostachys pubescens and pour epoxy resin glue for bonding, and the upper and lower parts of the surface of the phyllostachys pubescens pipe 2 in the front part of the triangular support body 4 are respectively provided with a longitudinal sliding groove 15 so as to ensure that the position of the phyllostachys pubescens pipe 2 in the bearing section 18 is unchanged when the bearing body moves in tension.
As shown in fig. 6 and 8, the bearing plate 3 of the expanded anchor joint is welded vertically along the radial direction of the steel bar 1, the triangular support 4 is fixedly connected with the bearing plate 3 and the steel bar 1 along the axial direction of the steel bar 1, and a plurality of circular grouting holes 3-1 are arranged on the bearing plate 3. The ratio of the length to the height of the triangular support body 4 is about 1:1, and the height is slightly smaller than the radius of the bearing plate 3, so as to enhance the displacement resistance and the deformation resistance of the bearing plate. In one embodiment, two side supporting type bearing plates 3 are adopted to be vertically welded with a triangular supporting body 4 and are fixed through welding seams 4-1, a steel bar inserting hole 3-2 is formed in the middle of the bearing plate 3, and grouting holes 3-1 are symmetrically formed in the bearing plates 3 on two sides of the triangular supporting body 4 respectively.
In another embodiment, as shown in fig. 7 and 9, a four-side support type bearing plate 3 is welded with a triangular support body 4 vertically, and is fixed by a welding seam 4-1, a steel bar jack 3-2 is arranged in the middle of the bearing plate 3, and grouting holes 3-1 are respectively arranged in four quadrants of the bearing plate 3 separated by the triangular support body 4.
As shown in fig. 10, EBTP anchor rods M are arranged in a quincuncial shape on the outer facade 20 of the brick-covered urban wall, the arrangement positions of EBTP anchor rods are staggered, the longitudinal spacing of each row is 10 times the diameter D of the bearing plate, namely 10D, and the horizontal spacing of adjacent longitudinal columns of anchor rods is 5 times the diameter D of the bearing plate, namely 5D.
As shown in FIG. 11, EBTP anchor rods M need to pass through the brick-covered wall body 9 when being installed in the brick-covered urban wall, and the bearing plate 3 is positioned at a deeper position in the urban wall rammed earth 8, if the length of the anchoring section 17 in the urban wall rammed earth is L 0, the bearing plates 3 of two adjacent EBTP anchor rods M need to be staggered by 1/3L 0 length along the axial direction of the anchor rods, and the EBTP anchor rods M are inserted obliquely downwards at an included angle of 10 degrees with the horizontal plane when being installed in the brick-covered urban wall.
The positions of the expanded anchor joints can be dynamically adjusted according to the installation positions of the expanded anchor joints in the site brick-covered wall body, the expanded anchor joints between adjacent EBTP anchor rods are preferably arranged at different depth positions in the rammed earth body in a staggered manner, and the axial distance is 1/2-1/5 of the length of the anchor sections in the rammed earth.
Furthermore, the diameter of the reinforcing steel bar 1 is slightly smaller than the diameter of the inner wall of the phyllostachys pubescens pipe 2, preferably adopting phi 18-phi 28 screw thread steel, and also being replaced by steel strands.
The phyllostachys pubescens pipe 2 is preferably made of natural phyllostachys pubescens with straight whole body and no obvious damage, all bamboo joints 11 except the last section inside phyllostachys pubescens are opened in a drilling or splitting and hollowing mode, and the bamboo joints are restored to the original circular section shape by pasting and winding carbon fiber cloth or binding steel wires after being opened in a splitting mode.
The epoxy resin adhesive 5 is preferably high-strength weather-resistant adhesive for building, the tensile strength is not lower than 65MPa, and brittle failure cannot occur. The epoxy resin adhesive 5 should have excellent adhesive strength and weather resistance, and its normal service life should not be less than the standard repair period of urban wall sites.
The plane shape of the anchor plate 12 can be round or square, the diameter or side length of the anchor plate is 3-6 times of the diameter of the bearing plate 3, and the anchor plate and the nuts are covered by old after the installation is completed, so that the consistency of the appearance of the anchor plate and the original wall is ensured.
The modified slurry 6 can be prepared by mixing scattered soil of the site, cement, fly ash and glutinous rice slurry with 5% silica sol, wherein the mass ratio of the components is 60:20:10:10, the cement ratio is 0.31, and the strength of the rammed soil body of the site can be adjusted. The strength of the material is slightly higher than the shear strength of rammed earth, so that the strength difference among the anchoring materials is in a smaller range, and the deformation and stress transmission of the anchoring system are more reasonable.
Cement mortar 7 can be mixed by cement and middle sand according to the mass ratio of 15:85 with water, the water-cement ratio is 0.29, and the strength and workability of the mortar can be improved by increasing the cement consumption and adjusting the water-cement ratio, but the strength of the cured mortar is not lower than M7.5 standard. The strength of the composite material is slightly higher than the shear strength of bricks of the brick-covered wall body so as to ensure higher bonding strength and smaller relative slippage of an anchoring interface in the brick-covered wall body.
The reinforcing steel bar 1 should be inserted into the phyllostachys pubescens tubular product 2 until the last bamboo joint 11, the length of the reinforcing steel bar 1 which is not wrapped by the phyllostachys pubescens tubular product 2 is the same as the thickness of the brick-wrapped wall 9, and 5cm to 15cm should be reserved for connecting and fixing the anchor plate 12 and the bolt 13.
The length of the longitudinal sliding groove of the phyllostachys pubescens pipe 2 is 50-100mm, and the width is slightly larger than the thickness of the supporting body.
The connection mode of the bearing plate 3 and the supporting body 4 can be two-side supporting type or four-side supporting type, and the like, the bearing plate 3 and the supporting body 4 are connected according to the mutually perpendicular relation of planes of the bearing plate 3 and the supporting body 4, a grouting hole is respectively arranged between two adjacent supporting bodies 4, the diameter of the grouting hole is larger than that of a grouting pipe, and the grouting hole is smaller than 1/2 of the distance between the outer diameter of the bearing plate 3 and the outer diameter of the phyllostachys pubescens pipe 2.
The EBTP anchor rods M are distributed in a quincuncial shape on the outer facade 20 of the urban wall, the adjacent rows and the rows of anchor rods are staggered by 1/3-1/2 of the distance, the anchor rods can be uniformly distributed along the wall surface or gradually distributed in an encrypted manner along the increase of the height of the wall according to the existing form of the urban wall site, and the anchor rods can be not arranged in the range of 1/4H at the bottom of the wall. The distribution interval of EBTP anchor rods is preferably 8-16 times of the diameter of the expanded anchor joint, so that the disturbance compaction influence range of the expanded anchor joint on soil mass can be ensured to cover adjacent anchor rods, the soil pressure around the adjacent anchor rods and the interfacial bonding strength of a tension section are improved, and the ultimate anti-pulling bearing capacity of the anchor rods is improved.
When EBTP anchor rods M are installed in urban walls, the bearing plates 3 are located in the length of the rear 2/3L 0 of the anchor section 17 in the rammed earth, the bearing plates of adjacent anchor rods are staggered by 1/2-1/5L 0 intervals along the axial direction of the anchor rods, and the projection of the bearing plates 3 at the deeper positions in the normal direction of the anchor rods is located in the tension section 19 of the adjacent anchor rods.
The working principle of the invention is as follows:
When the rammed earth urban wall site is subjected to external load such as horizontal earthquake, the brick-covered wall body and the rammed earth have large material property difference, and no reliable connection measure exists between the brick-covered wall body and the rammed earth, so that the brick-covered wall body generates relative displacement relative to the internal rammed earth. Because the strength of the steel bars, cement mortar, brick materials and the bonding strength of the interfaces of the anchoring section in the brick-covered wall body are high, the relative sliding quantity of the anchoring interface is far smaller than that of the anchoring section in rammed earth, so that the brick-covered wall body can be regarded as a commonly deformed whole. At this time, the anchor rod in the rammed earth body bears the axial load caused by the displacement of the brick-covered wall body, the load is directly transmitted to the expanded anchor joint by the reinforcing steel bars in the bearing section without bonding with the phyllostachys pubescens, the expanded anchor joint is pulled along with the reinforcing steel bars and generates displacement towards the direction of the hole, the modified slurry on one side of the bearing section of the expanded anchor joint bears pressure, the interface between the modified slurry and the rammed earth body bears shear stress and is gradually transmitted from the anchor joint to the hole, the stress mode of the section is similar to that of the traditional pressure anchor rod, the anchor rod at the rear part of the expanded anchor joint also generates displacement trend towards the hole due to the forward movement of the expanded anchor joint, but the strength of the reinforcing steel bars in the tension section is far Gao Yunan of bonding strength between the outer surface of the phyllostachys pubescens and the rammed earth interface, the shear sliding of the section mainly occurs at the outer surface of the phyllostachys pubescens and the rammed earth interface, and the interface shear stress is gradually transmitted from the anchor joint to the bottom end, and the stress mode of the interface is similar to that of the full-length bonding tension type anchor system.
In addition, the shearing and expanding effect caused by the displacement of the expanded anchor joint can cause disturbance to the soil body around the anchor in a certain range, the migration and compaction of soil particles are caused, the soil pressure around the anchor of the adjacent anchor rods is enhanced, the bonding strength of the anchoring interface of the adjacent anchor rods is improved accordingly, the anchor rods can cooperatively resist the relative displacement deformation of the brick-covered wall body, and the anchoring effect is further improved.
The invention is not limited to the above embodiments, and based on the technical solution disclosed in the invention, a person skilled in the art may make some substitutions and modifications to some technical features thereof without creative effort according to the technical content disclosed, and all the substitutions and modifications are within the protection scope of the invention.
Claims (9)
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| CN112761380B (en) * | 2021-01-22 | 2024-12-17 | 陕西建工第十三建设有限公司 | Support-anchor composite reinforcement structure and method for rammed earth wall |
| CN115573591A (en) * | 2022-09-30 | 2023-01-06 | 中建七局建筑装饰工程有限公司 | Ancient city wall soil body repairing construction method |
| CN115749358B (en) * | 2022-12-15 | 2025-04-04 | 江苏东南特种技术工程有限公司 | A reinforcement device for restraining horizontal earth pressure in a city wall and a reinforcement method thereof |
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| CN204023567U (en) * | 2014-08-11 | 2014-12-17 | 华侨大学 | A kind of tension and compression composite anchor-rod |
| CN110424762A (en) * | 2019-07-29 | 2019-11-08 | 西安建筑科技大学 | A cave reinforcement system |
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| CN2793196Y (en) * | 2005-05-13 | 2006-07-05 | 李最雄 | Composite bamboo reinforced rockbolt |
| CA2611531A1 (en) * | 2007-10-26 | 2009-04-26 | Gerard Voon | New building technologies |
| JP3208555U (en) * | 2016-11-07 | 2017-01-26 | 承▲き▼鋼鐵股▲ふん▼有限公司 | Adhesive anchor structure |
| CN108330966B (en) * | 2018-03-26 | 2023-05-30 | 华侨大学 | A centering support for the pressure-bearing anchorage section of the tension-compression composite bolt |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN204023567U (en) * | 2014-08-11 | 2014-12-17 | 华侨大学 | A kind of tension and compression composite anchor-rod |
| CN110424762A (en) * | 2019-07-29 | 2019-11-08 | 西安建筑科技大学 | A cave reinforcement system |
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