CN114525806A - Iron tower single-pile combined foundation and construction method thereof - Google Patents

Abstract

The invention relates to the field of iron tower construction, and discloses an iron tower foundation and a construction method thereof. The single-pile combined foundation of the iron tower includes a foundation pile and a plurality of tower foot connecting beams, the foundation pile is located in the middle of the plurality of tower foot connecting beams, one end of each tower foot connecting beam is connected with the foundation pile, and the other end is connected to the foundation pile. The outer divergent extension forms an extension part, and the extension part is provided with a tower foot connection structure for connecting the iron tower legs. The single-pile combined foundation of the tower only excavates and pours one foundation in the center of the tower. This foundation greatly reduces the land occupation and excavation of the foundation, reduces the restrictions on the tower foundation due to site conditions, and reduces the impact and damage of the tower foundation on the surrounding area, which can effectively Solve the problems of many urban underground pipelines, difficulties in four independent infrastructure construction in mountainous areas, restrictions on the ground breaking area of protected areas, and frost heave has a great impact on the foundation pull.

Description

Iron tower monopile combined foundation and its construction method

technical field

The invention relates to the field of iron tower foundation, in particular to an iron tower foundation and a construction method thereof.

Background technique

The most common type of iron tower for transmission lines is a four-legged iron tower. The existing four-legged iron tower foundation routinely adopts the method of one foundation for each tower leg to transfer the load on the iron tower to the foundation, such as the utility model patent with the announcement number CN203411988U , but with the construction of the line, there are the following difficulties in the construction of the four-legged tower with an independent foundation:

1. The four-legged iron towers built along the city and the surrounding roads of the city cannot build four foundations because of the municipal water and electricity pipelines buried under the roadside;

2. The route passes through ecological environmental protection areas, water sources, aquaculture bases, etc., which have restrictions on the area and scope of ground breaking, and the four-leg foundation cannot meet the requirements;

3. The site of the hydropower transmission line in the mountainous area is narrow, and four independent foundations cannot be built on the isolated hill or cliff;

4. In the plateau or Gobi site with fragile ecological environment, the construction of four independent foundations will seriously damage the environment of the tower base and cannot meet the requirements of environmental protection and water protection;

5. The geological conditions are hard and the foundation excavation is difficult. The use of small-section independent foundations is limited in mechanical excavation space, and the use of large-section independent foundations results in increased investment;

6. The geological conditions are poor, the tower site with large terrain slope adopts four independent foundations, the risk of excavation is high, and the environmental damage is large;

7. In areas with large frost heave grades and depths, the frost heave force in the four-leg independent foundation has a greater impact on the uplift of the foundation, resulting in a substantial increase in the amount of work; the above problems are currently difficult to solve with the commonly used foundation types.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide an iron tower single-pile combined foundation and a construction method thereof, which can reduce the limitation of site conditions on the iron tower foundation, and at the same time reduce the influence of the iron tower foundation on the surrounding.

The single-pile combined foundation for an iron tower disclosed by the invention comprises a foundation pile and a plurality of tower foot connecting beams, the foundation pile is located in the middle of the plurality of tower foot connecting beams, and one end of each tower foot connecting beam is connected with the foundation pile , the other end diverges and extends outward to form an extension part, and the extension part is provided with a tower foot connection structure for connecting the iron tower legs.

Preferably, the bottom of the foundation pile is provided with a foundation enlargement head.

Preferably, the tower foot connecting beams are arranged horizontally.

Preferably, the tower foot connecting beam is inclined upward from the foundation pile to the extension part.

Preferably, each of the tower foot connecting beams is connected to the same level of the foundation piles.

Preferably, each of the tower foot connecting beams is connected to the foundation piles at different levels.

Preferably, the connection structure of the tower foot is an anchor bolt, and the bottom of the anchor bolt is connected with an anchor plate, and the anchor plate is located under the reinforcing bars of the connecting beam of the tower foot.

Preferably, the tower foot connecting beam is made of concrete or profiled steel.

The construction method of the single-pile combined foundation of the iron tower comprises the following steps:

Design the monopile joint foundation of the tower;

Excavate the foundation pit according to the design of the foundation pile, and excavate the groove for connecting the beam at the foot of the tower;

Bind steel bars, set up connecting beams at the tower foot, and then open and fix the pre-buried anchor bolts as the tower foot connection structure according to the tower root, erect the formwork, and pour concrete to form the iron tower single pile joint foundation.

Preferably, when designing the combined foundation of the iron tower, load the load on the tower foot connection structure of the tower foot connecting beam, and determine the most unfavorable uplift force, the most unfavorable down pressure and the most unfavorable horizontal force calculated according to the working conditions of the iron tower. The magnitude and direction of the loading load.

Preferably, when designing the single-pile combined foundation of the iron tower, the basic force is calculated according to the annual average temperature condition, and the deflection of the tower foot connecting beam is calculated based on the basic force, and the pre-lift value of the designed tower foot connecting beam is greater than the calculated tower foot connecting beam. deflection.

The beneficial effects of the present invention are as follows: the combined foundation of the iron tower single pile of the present application only excavates and pours a foundation in the center of the iron tower, which greatly reduces the land occupation and excavation of the foundation, reduces the limitation of site conditions on the iron tower foundation, and reduces the iron tower foundation at the same time. The impact and damage on the surrounding area can effectively solve the problems mentioned in the background art, such as many urban underground pipelines, difficulty in constructing four independent infrastructures in mountainous areas, restrictions on ground breaking area in protected areas, and large impact of frost heave on foundation pull.

Description of drawings

1 is a schematic diagram of an embodiment of the present application;

Figure 2 is a diagram of another embodiment of the application;

FIG. 3 is a schematic diagram of a calculation example of the present application.

Reference numerals: foundation expansion head 1, foundation pile 2, tower foot connecting beam 3, tower foot connecting structure 4.

Detailed ways

The present invention is further described below.

The iron tower single-pile combined foundation disclosed in the present invention includes a foundation pile 2 and a plurality of tower foot connecting beams 3, the foundation pile 2 is located in the middle of the plurality of tower foot connecting beams 3, and each tower foot connecting beam 3 has one end at one end. It is connected with the foundation pile 2, and the other end diverges and extends outward to form an extension portion, and the extension portion is provided with a tower foot connection structure 4 for connecting the iron tower legs.

Among them, the tower foot connection structure 4 on the tower foot connection beam 3 is used to connect the tower foot of the tower. The tower foot connection structure 4 is usually an anchor bolt, and other existing connection methods can also be used. The number of tower foot connection beams 3 It can be determined according to the number of tower feet. At present, most iron towers have four tower feet, that is, the number of tower foot connecting beams 3 is usually four, and the number of foundation piles 2 of the entire foundation is only one, which is located at the connection of each tower foot. At the middle position of the beam 3, the acting force of each tower foot is transmitted to the foundation pile 2 through the tower foot connecting beam 3, and the foundation pile 2 is stably borne. Since only one foundation pile 2 is set, the limitation of site conditions on the iron tower foundation is reduced, and the influence and damage of the iron tower foundation on the surrounding area are also reduced.

The construction method of the single-pile combined foundation of the iron tower includes the following steps:

Design the monopile joint foundation of the tower;

Excavate the foundation pit according to the design of the foundation pile 2, and excavate the groove of the tower foot connecting beam 3;

Bind the steel bars, set the tower foot connecting beam 3, and fix the pre-buried anchor bolts according to the tower root as the tower foot connection structure 4, erect the formwork, and pour concrete to form the iron tower single pile joint foundation.

When designing, it is necessary to take into account the iron tower and site conditions. The foundation must not only meet the installation requirements of the iron tower, but also be adapted to the site conditions. The site conditions include the surrounding environment, geological topography and other factors; when excavating foundation pits and trenches, Mechanical or manual excavation can be used. Since the relative area of the required foundation pit and trench is relatively small, the amount of engineering can be reduced to a certain extent. The tower foot connecting beam 3 is made of concrete or profiled steel. If the tower foot connecting beam 3 is made of concrete, the tower foot connecting beam 3 should also be bound with steel bars, and the steel bars of the foundation pile 2 and the tower foot connecting beam 3 can be bound separately, but the preferred way is that the foundation pile 2 steel bar and the tower foot connecting beam 3 steel bars At the same time, it is bound to ensure the effective anchoring connection. If the connecting beam 3 of the tower foot is made of profiled steel, the profiled steel can be connected to the reinforcement of the foundation pile 2 to ensure stability. When the formwork is erected, the formwork needs to be fixed firmly, and measures can be taken to ensure the size of the foundation pile 2 and the connecting beam 3 at the tower foot and the thickness of the steel protective layer. Preferably, after the formwork is fixed, check the elevation of the foundation pile 2, the elevation and direction of the connecting beam 3 at the tower foot, the foundation root opening, the root opening of the anchor bolts and other dimensions, and pour the foundation concrete after the review is correct. For concrete pouring and vibrating around the bolts, it is necessary to ensure that the position of the anchor bolts remains unchanged. After the concrete is poured, the elevation of foundation pile 2, the elevation and direction of tower foot connecting beam 3, the opening of the foundation, and the opening of the anchor bolts should be checked. Concrete curing according to relevant specifications.

The stability of the foundation pile 2 is particularly important. In order to improve the stability of the foundation pile 2, in the preferred embodiment of the present application, a foundation enlargement head 1 is provided at the bottom of the foundation pile 2, and the foundation enlargement head 1 can improve the foundation pile 2. The force performance, whether it is the basic compression, pull-up, and bending performance, can be improved. The foundation enlargement head 1 itself may not be equipped with reinforcement, but it needs to be poured together with the foundation pile 2 through reinforcement and concrete.

The foundation is mainly subjected to compression and bending. There is a pull-up load only when the front and rear sides of the tower are pulled up. 2. The extension part is inclined upward, and at the same time, the tower foot connecting beam 3 can be connected to the same level of the foundation pile 2, or can be connected to the different levels of the foundation pile 2, which can be matched according to the needs, for example, The extension of each tower foot connecting beam 3 can be set to different heights according to the terrain and the requirements of the iron tower. As shown in Figure 1, when the tower foot connecting beam 3 is connected to the same level of the foundation pile 2, the tower foot can be adjusted by adjusting the height of the tower foot connecting beam 3. The length and inclination angle of the connecting beam 3 are used to adjust the height of the extension, and then the height and position of the tower foot connecting structure 4 are adjusted to fit the tower foot. As shown in Figure 2, when the tower foot connecting beam 3 is set horizontally, it can be By adjusting the connection height and length of each tower foot connecting beam 3, the height and position of the tower foot connecting structure 4 are adjusted to fit the tower foot.

When designing the single-pile combined foundation of the iron tower, load the load on the tower foot connection structure 4 of the tower foot connection beam 3, and determine the load according to the most unfavorable uplift force, the most unfavorable down pressure and the most unfavorable horizontal force calculated under each working condition of the iron tower. The magnitude and direction of the load to ensure the stability of the foundation.

As shown in Figure 3, the acting forces of the four tower legs of a 110kV linear tower under the same working condition are as follows:

Leg number Vertical force (kN) X-direction horizontal force (kN) Y-direction horizontal force (kN) A -111.84 4.3 -13.66 B 330.26 -31.09 -31.57 C 61.32 -7.8 -9.71 D -387.56 -35.04 -35.65

The loads in the table above are the maximum uplift and maximum downforce load conditions corresponding to the foundation forces on each tower leg. The negative value of the vertical force indicates the downforce, and the positive value indicates the uplift. Load the four loads ABCD in the above table on the corresponding tower legs in Figure 3, calculate the pile foundation force and the beam force, and then calculate the pile foundation 2 and the tower foot connecting beam 3 specifications according to the pile foundation specification and concrete specification, including Section size and the number of steel bars, etc., the diameter of the pile foundation 2 is 1.2m, 26 steel bars of 22mm are used, the size of the connecting beam 3 of the tower foot is 0.9m high and 0.6m wide at the root, and there are 6 steel bars of 28mm on the upper and lower planes.

In order to ensure that the height of the tower foot will not be affected by the downward deflection of the connecting beam after being stressed, when designing the combined foundation of the single pile of the iron tower, the maximum foundation force is calculated according to the annual average temperature condition, and the connection beam 3 at the tower foot is calculated based on the maximum foundation force. Deflection, take the calculated deflection of the connecting beam 3 at the tower foot as the pre-lift value of the connecting beam 3 at the tower foot. Through the designed pre-lift value of the tower foot connecting beam 3, it can be ensured that the tower foot connecting beam 3 is in an accurate height position after bearing the load, and the height position of the tower foot is accurate.

Also taking the 110kV linear tower shown in Figure 3 as an example, the working conditions for calculating the deflection are that the wind speed is 5m/s, the ground wire is not covered with ice, and the annual average temperature is 5℃. The force at the annual average temperature of this tower is:

Leg number Vertical force (kN) X-direction horizontal force (kN) Y-direction horizontal force (kN) A -3.91 0.15 -0.48 B 11.56 -1.09 -1.11 C 2.15 -0.27 -0.34 D -13.56 -1.23 -1.25

Finally, the pre-lift value of the connecting beam 3 at the tower foot is calculated to be 8 mm. In a straight tower, due to the different calculation directions of the wind load, each tower leg will have the same maximum load, so the pre-lift value of the connecting beam 3 at the tower foot is the same. .

The tower foot connection structure 4 is usually an anchor bolt, and the anchor bolt needs a certain anchoring length to ensure the mechanical performance. An anchor plate is connected, and the anchor plate is located below the steel bar of the connecting beam 3 at the tower foot, and the anchor plate bears the pulling force of the anchor bolt.

Claims (10)

1. an iron tower monopile combined foundation, is characterized in that, comprises a foundation pile (2) and a plurality of tower foot connecting beams (3), and the described foundation pile (2) is located in the middle of a plurality of tower foot connecting beams (3), One end of each of the tower foot connecting beams (3) is connected with the foundation pile (2), and the other end diverges and extends outward to form an extension portion, and the extension portion is provided with a tower foot connection structure (4) for connecting the tower legs. 2. The iron tower monopile combined foundation according to claim 1, characterized in that: the bottom of the foundation pile (2) is provided with a foundation enlargement head (1). 3. The iron tower monopile combined foundation according to claim 1, wherein the tower foot connecting beam (3) is arranged horizontally or inclined upward from the foundation pile (2) to the extension portion. 4. The iron tower monopile combined foundation according to any one of claims 1-3, characterized in that: each of the tower foot connecting beams (3) is connected to the same level of the foundation piles (2). 5. The iron tower monopile combined foundation according to any one of claims 1-4, characterized in that: each of the tower foot connecting beams (3) is connected to the foundation piles (2) at different levels. 6 . The combined foundation of iron tower monopiles according to claim 1 , wherein the tower foot connection structure (4) is an anchor bolt, and the bottom of the anchor bolt is connected with an anchor plate, and the anchor plate is located in the tower. 7 . The feet are connected below the reinforcing bars of the beam (3). 7. The iron tower monopile combined foundation according to claim 1, wherein the tower foot connecting beam (3) is made of concrete or profiled steel. 8. the construction method of the iron tower monopile combined foundation as described in any one of claim 1-7, is characterized in that, comprises the steps: Design the monopile joint foundation of the tower; Excavate the foundation pit according to the design of the foundation pile (2), and excavate the groove of the connecting beam (3) at the foot of the tower; Bind the steel bars, set the tower foot connecting beam (3), and after completion, press the iron tower to open and fix the pre-buried anchor bolts as the tower foot connection structure (4), erect the formwork, and pour concrete to form the iron tower single pile joint foundation. 9. The construction method according to claim 8, characterized in that, when designing an iron tower monopile combined foundation, a load is loaded on the tower foot connection structure (4) of the tower foot connection beam (3), according to each working condition of the iron tower The calculated uplift force is the most unfavorable, the downward pressure is the most unfavorable, and the horizontal force is the most unfavorable situation. Determine the magnitude and direction of the loading load, calculate the force of the pile foundation (2) and the connecting beam (3) at the tower foot, and then according to the pile foundation specification and The concrete specification calculates the specification of the pile foundation (2) and the connecting beam (3) at the tower foot. 10. The construction method according to claim 8 or 9, characterized in that, when designing the combined foundation of the iron tower single pile, the foundation force is calculated according to the annual average temperature condition, and the deflection of the connecting beam (3) at the foot of the tower is calculated with the foundation force. , and take the calculated deflection of the connecting beam (3) at the tower foot as the pre-lift value of the connecting beam (3) at the designed tower foot.

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