CN107227745A - A kind of group's anchor cable mat foundation of power transmission tower - Google Patents

Abstract

The invention discloses a group anchor cable slab foundation for a power transmission tower, which comprises a foundation upper slab, a sphere at the lower part of the foundation located in the ground below the foundation upper slab, an upper bearing steel backing plate arranged on the foundation upper slab, and several prestressed anchors The prestressed anchor cable includes a steel strand, an upper connecting plate, a lower connecting plate and a pretension spring. The steel strand passes through the upper plate of the foundation and the upper end is fixed to the upper bearing steel backing plate. The steel strand The lower end of the line is connected to the upper connecting plate, the pretension spring is arranged between the upper connecting plate and the lower connecting plate, and a retractable and expandable telescopic anchor assembly is arranged between the upper connecting plate and the lower connecting plate. The lower sphere of the foundation is formed by pouring concrete and integrated with the expanded telescopic anchor assembly. The invention can make the upper part of the power transmission tower have a better ability to resist dynamic loads.

Description

Group anchor cable slab foundation for transmission tower

technical field

The invention belongs to the power transmission technology, and in particular relates to the foundation of a power transmission tower.

Background technique

At present, in areas with thick overburden, traditional transmission line foundations are mainly used, such as "big excavation", "excavation and bottom expansion", "cast-in-situ piles" and other foundations, but these traditional foundations have defects, and large excavation The excavation area of the foundation is large and occupies a lot of land; the construction of the excavated foundation is relatively difficult; the cost of the cast-in-situ pile foundation is relatively high.

The underground part of the traditional foundation occupies a large space. When there are high constraints on the occupied space of the underground part of the foundation, due to the limitation of the calculation model of the conventional slab foundation, the area of the large underground slab is often large, and it is easy to fail to meet the application conditions; Although the cast-in-situ pile foundation covers a much smaller area, for areas with high environmental requirements or inconvenient transportation, when using cast-in-place pile foundations, due to the limitation of construction technology, there are certain requirements for the site and transportation conditions, often due to inability to quickly Environmental pollution caused by a good solution.

The traditional foundation mainly relies on the whole foundation to resist the uplift force, downward pressure and horizontal force, but when resisting a certain control load, the local part of the traditional foundation is often not stressed or the force is small, resulting in waste of materials, increasing the cost of the foundation, and making Traditional foundations are more expensive.

Contents of the invention

The technical problem to be solved by the present invention is to provide a group anchor cable slab foundation for a power transmission tower, which is convenient for construction and enables the power transmission tower to have better resistance to dynamic loads.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions: a group anchor cable slab foundation for transmission towers, including the foundation upper slab, the foundation lower sphere located in the ground below the foundation upper slab, and the upper bearing set on the foundation upper slab A steel backing plate, and several prestressed anchor cables, the prestressed anchor cables include steel strands, upper connecting plates, lower connecting plates and pretension springs, the steel strands pass through the upper plate of the foundation and the upper end and the upper bearing The steel backing plate is fixed, the lower end of the steel strand is connected to the upper connecting plate, the pretension spring is arranged between the upper connecting plate and the lower connecting plate, and a retractable spring is arranged between the upper connecting plate and the lower connecting plate. and the expanded telescopic anchor assembly, the telescopic anchor assembly expands outward circumferentially under the action of a pre-tension spring in a natural state, and the sphere at the lower part of the foundation is formed by pouring concrete and integrated with the expanded telescopic anchor assembly.

Further, the telescopic anchor assembly includes an upper link and a lower link, one end of the upper link and the lower link are hinged together, the other end of the upper link is hinged with the upper connecting plate, and the lower link The other end of the rod is hinged with the lower connecting plate.

Further, the telescopic anchor assemblies are provided in four groups and are evenly distributed along the circumferential direction of the upper connecting plate and the lower connecting plate.

Further, a first through hole is provided on the upper bearing steel backing plate, a fixing plate is arranged above the upper bearing steel backing plate, and the steel strand passes through the first through hole and is fixed to the fixing plate .

Further, the fixed plate is provided with a prestressed clip anchor, and the upper end of the steel strand is fixed with a prestressed clip anchor.

Further, an anchor hole is provided in the ground below the upper plate of the foundation for the passage of the prestressed anchor cable, and the bottom of the anchor hole is provided with an expansion hole for accommodating the lower sphere of the foundation, and the steel strand is covered with a steel sleeve. Filling concrete is poured into the cavity between the steel casing and the wall of the anchor hole, and the filling concrete is integrally cast with the lower sphere of the foundation.

Further, the steel sleeve is detachably connected with a lifting rope, the mouth of the steel sleeve is provided with a lifting ring, and the bottom of the lifting rope is provided with a hook matching with the lifting ring.

Further, the upper slab of the foundation is poured from reinforced concrete.

Further, the upper plate of the foundation is connected with the upper bearing steel backing plate through anchor bolts.

Further, the upper slab of the foundation is poured on the lower bearing steel backing slab.

After the present invention adopts above-mentioned technical scheme, the beneficial effect that brings is:

The upper slab of the foundation can be regarded as a shallow foundation. The upper slab and the lower sphere of the foundation are assembled and connected by prestressed anchor cables. The upper slab of the foundation is connected with the lower sphere of the foundation by applying prestress to the anchor cables. After it is completed, it is integrated with the expanded telescopic anchor component pouring. The main function of the upper plate of the foundation is to resist the vertical downward pressure, horizontal force and bending moment. When the foundation is subjected to the downward pressure, the downward force is completely borne by the upper plate of the foundation to prevent the foundation from lateral slipping and overturning; the lower part of the foundation The main function of the sphere is to resist the uplift force of the upper structure due to factors such as wind loads. When the foundation is subjected to the uplift force, the uplift force is transmitted to the multiple foundation lower spheres through the upper bearing steel backing plate and prestressed anchor cables. , It is completely supported by the linkage of the lower part of the foundation to prevent the foundation from being pulled out. Therefore, it can make the upper transmission tower have a better ability to resist dynamic loads. With the continuous emergence of extreme weather, the status of dynamic loads in the design of future transmission lines will gradually increase.

The upper load-bearing steel backing plate and prestressed anchor cable mainly play the role of transmitting the uplift force, the upper plate of the foundation mainly bears the down pressure and horizontal force, and the sphere at the bottom of the foundation mainly bears the uplift force, so that the foundation load transmission is clear and the foundation force is clear.

The main function of the upper slab on the foundation is to resist the vertical downward pressure, horizontal force and bending moment, which can reduce a certain thickness. The prestressed anchor cable adopts an underground expansion structure, which can reduce the diameter of the anchor hole, so it can save concrete consumption and mountainous areas. The amount of soil excavation reduces the cost of the project, reduces the damage caused by large-scale excavation to the environment, and thus protects the ecological environment; at the same time, the foundation construction has a high degree of mechanization, which makes the construction period short, improves construction efficiency, and reduces construction costs.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and specific embodiment:

Fig. 1 is the schematic diagram of the group anchor cable slab foundation with the prestressed anchor cable in the shrinking state for the transmission tower;

Fig. 2 is the schematic diagram of the group anchor cable slab foundation with the prestressed anchor cable in the expanded state for the transmission tower;

Fig. 3 is the structural schematic diagram of prestressed anchor cable under expansion state;

Fig. 4 is a schematic diagram of the structure of the fixed disk.

detailed description

Referring to Fig. 1 to Fig. 4, an embodiment of a group anchor cable slab foundation for a power transmission tower according to the present invention will be further described.

As shown in Figures 1 to 4, a group anchor cable slab foundation for a transmission tower includes a foundation upper plate 2, a base lower sphere located in the ground below the foundation upper plate, and an upper bearing steel backing plate arranged on the foundation upper plate , and several prestressed anchor cables 1, the prestressed anchor cables include a steel strand 11, an upper connecting plate 12, a lower connecting plate 14 and a pretension spring 13, and the steel strand 11 passes through the upper plate 2 of the foundation and The upper end is fixed with the upper bearing steel backing plate, the lower end of the steel strand is connected with the upper connecting plate 12, and the pretension spring 13 is arranged between the upper connecting plate 12 and the lower connecting plate 14, and the upper connecting plate 12 and the lower connecting plate 14 are connected. A retractable and expandable telescopic anchor assembly 15 is arranged between the lower connecting plates 14 .

Wherein, as shown in FIG. 3 , the telescopic anchor assembly 15 includes an upper link 151 and a lower link 152, one end of the upper link 151 and the lower link 152 are hinged together, and the other end of the upper link 151 One end is hinged to the upper connecting plate 12 , and the other end of the lower connecting rod 152 is hinged to the lower connecting plate 14 . The telescopic anchor assembly 15 is installed in the anchor hole 4 by means of the steel sleeve 3, and the telescopic anchor assembly 15 shrinks toward the center, and then it can be put into the steel sleeve 3. The bottom of the anchor hole is provided with an expansion hole 41 for accommodating the lower sphere of the foundation. The steel casing 3 is detachably connected with a lifting rope 32 for lifting the steel casing 3 upwards. The mouth of the steel casing is provided with a lifting ring 31, and the bottom of the lifting rope is provided with a ring to cooperate with the lifting ring. the hook. Two lifting ropes 32 are arranged and evenly distributed along the mouth of the steel sleeve, so that when the lifting rope 32 lifts the steel sleeve 3, the force on the steel sleeve 3 is more uniform, and the pulling of the steel sleeve 3 is more convenient and labor-saving.

When the telescopic anchor assembly 15 is in a tightened state, the pretension spring 13 is in a stretched state, and the telescopic anchor assembly 15 is stretched simultaneously, so that the telescopic anchor assembly 15 penetrates into the steel casing 3 so as to be placed in the anchor hole 4; When the telescopic anchor assembly 15 is located in the expansion hole 41 together with the bottom of the steel casing 3, it can be expanded, and the upper connecting plate 12 is supported by the rigid support rod, and the lifting ring 31 on the steel casing is used to lift the lifting rope 32, and at the same time Due to the effect of the pretension spring 13, the telescopic anchor assembly 15 is in an expanded state. Concrete is poured into the cavity between the steel casing 3 and the wall of the anchor hole, so that the spheroid at the bottom of the foundation is combined with the expanded telescopic anchor assembly 15 pouring. The prestressed anchor cable 1 adopts an underground expansion structure, which can reduce the diameter of the anchor hole, save the amount of concrete and the amount of soil excavation in mountainous areas, reduce the cost of the project, reduce the damage to the environment caused by large-scale excavation, and thus protect the ecological environment. In this embodiment, the telescopic anchor assemblies 15 are provided in four groups and are evenly distributed along the circumferential direction of the upper connecting plate 12 and the lower connecting plate 14 . The telescopic anchor assembly 15 extends toward the anchor hole 4 from four directions, so that the wrapped prestressed anchor cable after pouring concrete is more evenly stressed in all directions. The prestressed anchor cable adopts a spring-type telescopic expansion structure, which can be freely expanded and contracted, which is convenient for transportation and construction.

The foundation upper plate 2 is formed by pouring reinforced concrete, the foundation upper plate 2 is connected with the upper bearing steel backing plate through anchor bolts, and the foundation upper plate is poured on the lower bearing steel backing plate.

The main function of the upper plate of the foundation is to resist the vertical downward pressure, horizontal force and bending moment. When the foundation is subjected to the downward pressure, the downward force is completely borne by the upper plate of the foundation to prevent the foundation from lateral slipping and overturning; the lower part of the foundation The main function of the sphere is to resist the uplift force of the upper structure due to factors such as wind loads. When the foundation is subjected to the uplift force, the uplift force is transmitted to the multiple foundation lower spheres through the upper bearing steel backing plate and prestressed anchor cables. , It is completely supported by the linkage of the lower part of the foundation to prevent the foundation from being pulled out. Therefore, the upper transmission tower can have a better ability to resist dynamic loads.

The upper load-bearing steel backing plate and prestressed anchor cable mainly play the role of transmitting the uplift force, the upper plate of the foundation mainly bears the down pressure and horizontal force, and the sphere at the bottom of the foundation mainly bears the uplift force, so that the foundation load transmission is clear and the foundation force is clear. And after the steel strand 11 is fixed with the upper load-bearing steel backing plate, the contact area connected between the steel strand and the foundation upper plate can be increased to prevent excessive stress concentration from occurring.

The main function of the slab on the foundation is to resist the vertical downward pressure, horizontal force and bending moment, and can reduce a certain thickness, so it can save the amount of concrete and the excavation volume of soil in mountainous areas, reduce the project cost, and reduce large-scale excavation The damage caused to the environment, thereby protecting the ecological environment; at the same time, the high degree of mechanization of the foundation construction makes the construction period short, improves the construction efficiency, and reduces the construction cost.

Further, a first through hole is provided on the upper bearing steel backing plate, and a fixed disk 5 is arranged above the upper bearing steel backing plate, and the steel strand 11 passes through the first through hole and connects with the fixed disk 5 Fixed, the fixed disc can be fixed as one with the upper bearing steel backing plate and the foundation upper plate by bolts 52. The fixed disc 5 increases the contact area between the steel strand 11 and the upper bearing steel backing plate, preventing excessive stress concentration. The fixed plate 5 is provided with a prestressed clip anchor 51 for fixing the upper end of the steel strand.

Referring to FIG. 4 , the fixed plate is provided with a second through hole 50 , the second through hole is rounded and truncated, and the prestressed clip anchor 51 is a split wedge chuck. The steel strand passes through the first through hole and the second through hole and is fixed by a split wedge clamp. The split-type wedge-shaped chuck is convenient for clamping the steel strand. The wedge-shaped chuck has a self-locking function during the clamping of the steel strand, and is not easy to slip; Fix the wedge-shaped collet in the through hole to prevent the wedge-shaped collet from slipping off. The ends of the steel strands are fixed with prestressed clip anchors, and the upper and lower concrete are connected together through the steel strands by applying prestress to the steel strands.

The present invention also provides a construction method for group anchor cable slab foundations for power transmission towers, the steps are as follows:

(1) Excavate a foundation pit on the selected ground, drill several anchor holes vertically downward at the bottom of the foundation pit, and use reaming equipment to ream the bottom of the anchor holes to the designed size;

(2) The upper connecting plate is connected with the steel strand (wedge chuck can be used to fix it), and the steel sleeve is sleeved on the outside of the telescopic anchor assembly and put into the anchor hole together. At this time, the pretension spring is in a stretched state, and at the same time Stretch the telescopic anchor component so that the telescopic anchor component is in a contracted state;

(3) Use support rods and other instruments to extend into the anchor hole against the top of the upper connecting plate, pull the lifting rope upward, and the lifting rope drives the steel casing to move upward, so that the telescopic anchor assembly extends in the reamed hole at the bottom of the anchor hole. Out of the casing, the pre-tension spring is retracted, so that the telescopic anchor assembly is expanded outward, and then the support rod is taken out;

(4) Inject concrete into the anchor hole, so that the concrete in the anchor hole and the prestressed anchor cable are condensed into one, and a sphere under the foundation is also formed. When constructing multiple prestressed anchor cables, it must be carried out from the inside to the outside (that is, first Pouring the prestressed anchor cables in the middle part, and then pouring the prestressed anchor cables around the middle part);

(5) Concrete is poured in the foundation pit to form the upper slab on the foundation.

Finally, the upper plate of the foundation is connected with the upper load-bearing steel backing plate through anchor bolts, a fixed plate is placed on the upper load-bearing steel backing plate, and the steel strand is locked on the fixed plate by a split wedge-shaped chuck.

Using this basis has the following advantages:

(1) It can give full play to the physical and mechanical properties of different materials, save materials and reduce the cost.

(2) The undisturbed soil can be fully utilized, and the reliability of the foundation's pull-out resistance is high.

(3) With the continuous emergence of extreme climates, the status of dynamic loads in the design of transmission lines will gradually increase in the future. The use of flexible foundations can make the upper towers have better resistance to dynamic loads.

(4) The amount of spoil can be reduced, thereby protecting the ecological environment.

(5) It is easy to disassemble, which reduces the amount of foundation demolition work.

(6) The load transfer of the foundation structure is clear, and the structure calculation and construction are relatively simple.

The above descriptions are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions under the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those skilled in the art, some improvements and modifications without departing from the principles of the present invention should also be regarded as the protection scope of the present invention.

Claims (10)

1. a kind of group's anchor cable mat foundation of power transmission tower, it is characterised in that：Including basic upper plate, positioned at ground below basic upper plate Interior basic infrastructure spheroid, the upper carrying billet being arranged on basic upper plate, and some prestress anchorage cables, the prestressing force Anchor cable includes steel strand wires, upper gusset piece, second line of a couplet fishplate bar and pretension spring, and the steel strand wires are passed through and upper end from basic upper plate Fixed with upper carrying billet, the lower end of the steel strand wires is connected with upper gusset piece, and the pretension spring is arranged on connection It is described provided with collapsible and expansion flexible anchor assemblies between upper gusset piece and the second line of a couplet fishplate bar between plate and second line of a couplet fishplate bar Flexible anchor assemblies are in its natural state by the outside adjacent circumferential expansion of pretension spring effect, and the basic infrastructure spheroid is poured by concrete Build to form and pour with the flexible anchor assemblies after expansion and be combined as a whole.

2. a kind of power transmission tower according to claim 1 group's anchor cable mat foundation, it is characterised in that：The flexible anchor assemblies Including upper connecting rod and lower link, one end of the upper connecting rod and lower link is hinged, the other end of the upper connecting rod with Upper gusset piece is hinged, and the other end and the lower linking plate of the lower link are hinged.

3. a kind of power transmission tower according to claim 2 group's anchor cable mat foundation, it is characterised in that：The flexible anchor assemblies It is provided with four groups and uniform along the circumference of upper gusset piece and second line of a couplet fishplate bar.

4. a kind of power transmission tower according to claim 1 group's anchor cable mat foundation, it is characterised in that：The upper carrying steel pad First through hole is provided with plate, the top of the upper carrying billet is provided with fixed disk, and the steel strand wires are worn from first through hole Cross and fixed with fixed disk.

5. a kind of power transmission tower according to claim 4 group's anchor cable mat foundation, it is characterised in that：Set on the fixed disk There is prestressing force intermediate plate anchorage, the upper end of the steel strand wires is fixed using prestressing force intermediate plate anchorage.

6. a kind of power transmission tower group's anchor cable mat foundation according to claim 1 to 5 any one, it is characterised in that：Institute The anchor hole for being provided with and passing through for prestress anchorage cable in ground below basic upper plate is stated, the bottom of the anchor hole is provided with receiving basic infrastructure It is cased with having poured in the cavity between steel sleeve, steel sleeve and the anchor hole hole wall outside the expanded bore of spheroid, the steel strand wires and fills out Fill concrete and the fill concrete is molded with basic infrastructure spheroid formed by integrally casting.

7. a kind of power transmission tower according to claim 6 group's anchor cable mat foundation, it is characterised in that：The steel sleeve is removable Unload and be connected with rope, the oral area of the steel sleeve is provided with suspension ring, and the bottom of the rope is provided with the hook coordinated with suspension ring.

8. a kind of power transmission tower according to claim 1 group's anchor cable mat foundation, it is characterised in that：The basic upper plate by Armored concrete, which is poured, to be formed.

9. a kind of power transmission tower according to claim 8 group's anchor cable mat foundation, it is characterised in that：The basic upper plate with Upper carrying billet is connected by crab-bolt.

10. a kind of power transmission tower according to claim 8 group's anchor cable mat foundation, it is characterised in that：The basic upper plate It is cast on lower carrying billet.