Assembly type bearing platform anchor cable foundation of power transmission tower and construction method
Technical Field
The invention belongs to the technical field of power transmission and transformation engineering, and particularly relates to an assembly type bearing platform anchor cable foundation suitable for building a large-angle corner power transmission tower in a composite stratum with a thick covering layer and complete underlying bedrock in a mountainous area.
Background
The fabricated foundation is a foundation type with optimal comprehensive benefits in various transmission line tower foundations, research and application demonstration of the transmission line fabricated tower foundation are developed, standard, modularized and industrialized processing production of the tower foundation can be promoted, and the quality of the tower foundation is improved; meanwhile, the fabricated foundation does not need on-site concrete maintenance, the construction period of the transmission line tower foundation can be effectively shortened, and the construction efficiency of the transmission line project is improved; the fabricated foundation can be assembled on site through mechanized transportation, the mechanized construction level of the transmission line tower foundation is improved, and the workload and the construction process of on-site manual operation are effectively reduced.
A large number of composite stratums with thicker covering layers and better underburden engineering properties exist in the southeast coastal mountainous area of China. For such stratum, the existing common transmission line foundation, such as an excavation foundation, has the defects of large excavation amount of earth and stone, serious environmental damage, large buried depth and size of a bearing platform, large consumption of concrete, high transportation requirements of materials such as cement, gravel, steel and the like, and high cost; the common rock anchor rod foundation is suitable for the condition that the underlying bedrock is shallow, the stratum with a thicker covering layer is limited by the length of the common rock anchor rod, larger foundation excavation amount is needed or other deep foundation types are adopted, the construction in mountainous areas is difficult, and the manufacturing cost is higher. Ordinary rock stock basis is mostly traditional full length bonding type stock, and its tensile bearing capacity is not only relevant with stock material intensity, receives the stock to be relevant with rock mass and mortar bonding strength moreover, and single stock can not provide great withdrawal resistance. Due to the asymmetry of the load of the large-angle corner power transmission tower, the iron tower foundation needs to bear large uplift load and horizontal load, and therefore a novel assembly type iron tower foundation capable of aiming at complex working conditions needs to be designed.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide the fabricated bearing platform anchor cable foundation for the power transmission tower, which is suitable for a composite stratum with a thicker covering layer and better underlayer rock engineering properties and can bear complex working conditions under the comprehensive action of uplift load and horizontal load.
In order to solve the technical problems, the invention adopts the following technical scheme: the utility model provides a steel pylons assembled cushion cap anchor rope basis, installs in the binary composite stratum that has upper portion soil covering layer, lower position bedrock, includes:
the prefabricated bearing platform is used for mounting tower feet of the power transmission tower;
the supporting short columns are supported below the prefabricated bearing platform and are fixed with the prefabricated bearing platform;
the prefabricated bearing platform and the supporting short column are buried in the soil covering layer at the upper part;
and the pressure type anchor cable sequentially penetrates through the prefabricated bearing platform and the supporting short column and is anchored into the lower bedrock.
Preferably, the prefabricated cushion cap comprises a plurality of prefabricated cushion cap main beams which are arranged on the upper layer in parallel and a plurality of prefabricated cushion cap secondary beams which are arranged on the lower layer in parallel, the prefabricated cushion cap main beams and the prefabricated cushion cap secondary beams are vertically staggered, the lap joint parts of the prefabricated cushion cap main beams and the prefabricated cushion cap secondary beams are fixed through anchor bolts, and anchor cable hole positions for pressure type anchor cables to penetrate through are arranged on the lap joint parts of the prefabricated cushion cap main beams and the prefabricated cushion cap secondary beams in a penetrating mode.
Preferably, the upper surface of the main beam of the prefabricated bearing platform is provided with foundation bolts used for being connected with foot plates of the iron tower.
Preferably, the supporting short column is a precast concrete short column, and the precast concrete short column is provided with an anchor cable hole site for a pressure type anchor cable to pass through at the middle position in a penetrating manner.
Preferably, the supporting short column is a square short column, and the supporting short column is fixed with the prefabricated bearing platform through an anchor bolt.
Preferably, the pressure type anchor cable is arranged vertically or obliquely.
Preferably, the anchor cable body of the pressure type anchor cable is made of a steel strand.
Preferably, the steel strand is externally sleeved with a protective sleeve.
Preferably, the prefabricated bearing platform is arranged on the concrete cushion layer.
The invention also provides a construction method of the assembly type bearing platform anchor cable foundation of the power transmission tower, which comprises the following steps:
prefabricating a main beam of a bearing platform, a secondary beam of the bearing platform and a supporting short column;
transporting the prefabricated part to a construction site;
excavating a foundation pit on site, leveling and aligning the excavated field, and pouring a concrete cushion;
fourthly, installing a pressure type anchor cable and grouting holes;
hoisting a supporting short column, a prefabricated bearing platform main beam and a prefabricated bearing platform secondary beam in sequence, and connecting the supporting short column, the prefabricated bearing platform main beam and the prefabricated bearing platform secondary beam through anchor bolts;
stretching and fixing the pressure type anchor cable;
and seventhly, mounting an iron tower foot plate, and backfilling earthwork.
According to the technical scheme, the stress of the iron tower foundation under the working conditions of upward pulling, horizontal pressing and downward pressing is borne through the pressure type anchor cables, the supporting short columns and the prefabricated bearing platform respectively.
Compared with the prior art, the invention has the beneficial effects that:
1. the prefabricated bearing platform adopted by the invention comprises a plurality of prefabricated bearing platform main beams and a plurality of prefabricated bearing platform secondary beams which are processed independently, so that the volume and the weight of each prefabricated single body are light, the prefabricated bearing platform is convenient to manufacture, transport and install, on-site concrete maintenance is not needed, the foundation excavation earthwork amount, the concrete consumption and the damage to the environment are reduced, the construction period is shortened, and the prefabricated bearing platform has the advantages of economy and environmental protection.
2. The pressure type anchor cable is adopted to replace the traditional full-length bonding tension type anchor rod, the anchor cable can penetrate through the covering layer, the bottom of the anchor cable is anchored into the bedrock for a certain length, the pulling resistance required by the power transmission tower is transferred to a stable stratum, the force transfer path is more definite and reasonable, the higher foundation bearing capacity of the underlying complete bedrock is fully utilized, and the pulling resistance and the horizontal bearing capacity of the foundation are effectively improved; the anchor cable grouting body is in a pressed state, so that the advantage of strong compression resistance of the grouting body can be fully exerted; the single anchor cable can provide great resistance to plucking bearing capacity, can arrange the quantity and the arrangement mode of required anchor cable in a flexible way according to the load of pulling up to and nimble adjustment anchor cable length, have very high place suitability, be favorable to providing safe and reliable's resistance to plucking bearing capacity.
3. Because the uplift bearing capacity is borne by the pressure type anchor cable, and the prefabricated bearing platform only needs to meet the requirement of the bearing capacity of pressing down, the embedded depth and the section size of the prefabricated bearing platform can be greatly reduced during design.
The following detailed description and the accompanying drawings are included to provide a further understanding of the invention.
Drawings
The invention is further described with reference to the accompanying drawings and the detailed description below:
FIG. 1 is a schematic front view of a fabricated cap anchor cable foundation of the present invention;
FIG. 2 is a view taken in the direction 1-1 of FIG. 1;
FIG. 3 is a schematic sectional view taken along line A-A in FIG. 2;
in the figure: 1-prefabricating a main beam of a bearing platform; 2, prefabricating a bearing platform secondary beam; 3-a square short column; 4-pressure type anchor cable; 5-concrete cushion; 6-tower foot; 7-anchoring bolts.
Detailed Description
The technical solutions of the embodiments of the present invention are explained and illustrated below with reference to the drawings of the embodiments of the present invention, but the following embodiments are only preferred embodiments of the present invention, and not all embodiments. Based on the embodiments in the implementation, other embodiments obtained by those skilled in the art without any creative effort belong to the protection scope of the present invention.
Example one
Referring to fig. 1 to 3, the fabricated bearing platform anchor cable foundation for the power transmission tower is suitable for a composite stratum with a thick covering layer and good underlayer rock property in a mountainous area, and comprises a prefabricated bearing platform with the upper part formed by a prefabricated bearing platform main beam 1 and a prefabricated bearing platform secondary beam 2, a square short column 3 at the lower part and a plurality of pressure type anchor cables 4.
The prefabricated bearing platform is used for installing tower feet 6 of the power transmission tower and is arranged on the concrete cushion 5. The prefabricated cushion cap comprises a plurality of prefabricated cushion cap main beams 1 which are arranged on the upper layer in parallel and a plurality of prefabricated cushion cap secondary beams 2 which are arranged on the lower layer in parallel, the prefabricated cushion cap main beams 1 and the prefabricated cushion cap secondary beams 2 are vertically staggered, the lap joint parts of the prefabricated cushion cap main beams 1 and the prefabricated cushion cap secondary beams 2 are fixed through anchor bolts 7, and anchor cable hole positions for pressure type anchor cables to pass through are arranged on the lap joint parts of the prefabricated cushion cap main beams 1 and the prefabricated cushion cap secondary beams 2 in a penetrating mode. And a plurality of square short columns 3 are supported below the prefabricated bearing platform and are fixed with the prefabricated bearing platform. The prefabricated cushion cap main beam 1, the prefabricated cushion cap secondary beam 2 and the square short column 3 are buried in the covering layer, one end of the pressure type anchor cable 4 penetrates through the covering layer, and penetrates through the prefabricated cushion cap main beam 1, the prefabricated cushion cap secondary beam 2 and the square short column 3 in sequence and is anchored into bedrock.
The square short column is a precast concrete short column, and the precast concrete short column is provided with an anchor cable hole site for a pressure type anchor cable to pass through at the middle position in a penetrating manner. The square short column is fixed with the prefabricated bearing platform through an anchoring bolt.
Preferably, the pressure type anchor cable is arranged vertically or obliquely. The anchor cable body of the pressure type anchor cable is made of steel strands. And a protective sleeve is sleeved outside the steel strand.
This assembled cushion cap anchor rope basis undertakes iron tower basis atress under pull-up, level and the operating mode of pushing down respectively through pressure type anchor rope 4, square short column 3 and prefabricated cushion cap girder 1, prefabricated cushion cap secondary beam 2, adopts pressure type anchor rope 4 to replace traditional full length bonding tension type stock.
The structural design of prefabricated cushion cap of assembled for every free volume of assembled and weight can be the lightweight be convenient for preparation, transportation and installation, and need not on-the-spot concrete maintenance, reduce basic excavation earthwork volume, concrete volume and to the destruction of environment, the reduction of erection time has economic environmental protection's advantage.
The anchor cable can penetrate through the covering layer and the bottom of the anchor cable is anchored into the bedrock for a certain length, the pulling resistance required by the power transmission iron tower is transferred to a stable stratum, the force transfer path is more definite and reasonable, the higher foundation bearing capacity of the underlying complete bedrock is fully utilized, and the pulling resistance and the horizontal bearing capacity of the foundation are effectively improved; the anchor cable grouting body is in a pressed state, so that the advantage of strong compression resistance of the grouting body can be fully exerted; the single anchor cable can provide great resistance to plucking bearing capacity, can arrange the quantity and the arrangement mode of required anchor cable in a flexible way according to the load of pulling up to and nimble adjustment anchor cable length, have very high place suitability, be favorable to providing safe and reliable's resistance to plucking bearing capacity.
Because the uplift bearing capacity is borne by the pressure type anchor cable, and the prefabricated bearing platform only needs to meet the requirement of the bearing capacity of pressing down, the embedded depth and the section size of the prefabricated bearing platform can be greatly reduced during design.
Example two
The construction method of the assembly type bearing platform anchor cable foundation of the power transmission tower in the first embodiment of the invention comprises the following steps:
firstly, prefabricating a main beam 1 of a prefabricated bearing platform, a secondary beam 2 of the prefabricated bearing platform and a square short column 3 according to the basic size;
transporting the prefabricated part to the site;
excavating a foundation pit on site, leveling and aligning the excavated field, and pouring a concrete cushion layer 5;
positioning and drilling, installing a pressure type anchor cable 4, and grouting holes;
hoisting the square short column 3, the prefabricated bearing platform main beam 1 and the prefabricated bearing platform secondary beam 2 in sequence, and connecting the beams through the anchor bolts 6;
sixthly, tensioning and fixing the pressure type anchor cable 4;
installing the upper structure and backfilling soil.
The assembled bearing platform anchor cable foundation provided by the invention is suitable for an upper soil and lower rock composite soil layer with a thicker covering layer, can fully utilize the higher foundation bearing capacity of the underlying complete bedrock, has higher uplift bearing capacity and is suitable for a large-angle corner iron tower with higher uplift load, and the single anchor cable provides larger uplift bearing capacity; meanwhile, the section size and the burial depth of the bearing platform foundation can be greatly reduced, the excavation earth volume of the foundation, the concrete consumption and the damage to the environment are reduced, the construction period is shortened, and the method has the advantages of economy and environmental protection.
While the invention has been described with reference to specific embodiments thereof, it will be understood by those skilled in the art that the invention is not limited thereto, and may be embodied in many different forms without departing from the spirit and scope of the invention as set forth in the following claims. Any modification which does not depart from the functional and structural principles of the present invention is intended to be included within the scope of the claims.