CN111894026A - Tunnel type pile foundation bearing platform combined anchorage structure and installation method thereof - Google Patents

Abstract

The invention provides a tunnel-type pile foundation bearing platform combined anchorage structure. The anchorage structure is arranged in an oblique slope body, and the slope body is provided with a tunnel along the transverse direction. The anchorage structure includes a tunnel-type bearing platform and a pile foundation. The cap is embedded in the tunnel along the horizontal direction, and the pile hole is excavated vertically downward from the lower end of the tunnel. The pile foundation is arranged in the pile hole, and the pile foundation is connected with the tunnel-type cap. There are several anchor cables buried in the slope section and the vertical section; the advantages of the invention are: excavating the tunnel on the steep slope body provides the anchorage construction space, effectively reducing the earth and stone opening of the pile foundation bearing platform in the grading excavation construction. The amount of excavation can save the construction cost; the pile foundation is used to penetrate into the better geological layer to provide horizontal resistance, and the structure is safe and reliable; it is suitable for harsh conditions with steep terrain and poor geological conditions, with simple construction technology, safe and reliable structure, and relatively economical cost.

Description

A tunnel-type pile foundation cap composite anchor structure and its installation method

technical field

The invention relates to the field of foundation engineering, in particular to a tunnel-type pile foundation bearing platform combined anchor structure and an installation method thereof.

Background technique

In foundation engineering, the anchor structure that mainly bears horizontal force is an important foundation type. Its common structural forms include gravity anchors, pile foundation anchors, rock anchors, etc. Gravity anchors are generally used in areas with relatively flat terrain and good surface geology. When the surface geology is poor, a pile foundation can be added to provide horizontal resistance, which derives the form of pile foundation caps. For excavating slopes in large areas, if the geological conditions are good, rock anchors can be used to drive the anchor cables into hard rock layers to provide horizontal resistance. However, under the harsh conditions of mountainous areas with steep terrain and bad geology, the conventional anchorage structures all show the shortcomings of poor applicability. In response to such problems, the construction of anchorages in such poor areas is generally avoided in the design and site selection. However, when it is unavoidable due to engineering needs, it is still necessary to explore and study them.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a tunnel-type pile foundation bearing platform combined anchor structure and its installation method.

In order to achieve the above object, the technical scheme of the present invention is:

A tunnel-type pile foundation bearing platform combined anchoring structure is characterized in that the anchoring structure is arranged in an oblique slope body, the slope body is provided with a tunnel along the lateral direction, and the anchoring structure comprises a tunnel-type bearing The tunnel-type cap is embedded in the tunnel along the horizontal direction, the lower end of the tunnel is lower than the slope body at the entrance of the tunnel, and a step is formed between the lower end of the tunnel and the slope body. The lower end of the tunnel is excavated vertically downward to form a number of cylindrical pile holes, and a pile foundation is arranged in each of the pile holes, and the upper end of the pile foundation is connected with the lower end of the tunnel-type cap.

The upper end of the tunnel-type bearing platform is arc-shaped, the upper end of the tunnel-type bearing platform is gradually raised from both sides to the center, and the upper end of the tunnel-type bearing platform is inclined downward from front to back. The front end of the bearing platform includes an inclined plane section and a vertical section connected up and down in sequence, the inclined plane section is inclined forward from top to bottom, and several anchor cables are embedded in the inclined plane section.

A method for installing a tunnel-type pile foundation bearing platform combined anchor structure, characterized in that it comprises the following steps:

Step 1) According to the design drawings, stake out the location of the tunnel and excavate the tunnel;

Step 2) Arch frame, anchor rod and spray protection are applied as required in the excavation process, so that the vault, side wall and inverted arch structure meet the construction safety requirements, and the position of the pile opening of the pile foundation is reserved during the construction of the inverted arch spray protection;

Step 3) Complete the tunnel excavation and support, build the lock, and manually excavate the pile hole and pile foundation;

Step 4) After the pile foundation is completed, install the reinforcement cage, pour concrete, and leave the pile head reinforcement of the pile foundation as required to connect and anchor with the tunnel cap;

Step 5) Chisel off the pile head, trim the overhanging steel bars of the pile head, and install the steel bar binding of the tunnel-type cap;

Step 6) Install the anchor cables according to the quantity and position required by the design. After installing the tunnel port formwork, pour concrete on the tunnel cap, so that the pile foundation and the anchor cables are connected through the tunnel cap to form a whole.

The advantages of the invention are: excavating a tunnel on a steep slope body provides an anchorage construction space, effectively reducing the amount of earth and stone excavation for the pile foundation cap of the grading excavation construction, and saving the construction cost; it is better to use the pile foundation to penetrate deeply. It is suitable for the harsh conditions of steep terrain and bad geology, with simple construction technology, safe and reliable structure, and relatively economical cost.

Description of drawings

Fig. 1 is the side structure schematic diagram of the present invention;

FIG. 2 is a schematic view of the front structure of the tunnel-type cap in the present invention.

Reference number:

1 Pile foundation 2 Tunnel cap 21 Inclined section 22 Vertical section

3 Anchor cables 4 Slopes 5 Tunnels.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The present invention discloses a tunnel-type pile foundation bearing platform combined anchorage structure. As shown in FIG. 1 , the anchorage structure is arranged in an inclined slope body 4, and the slope body 4 is provided with a tunnel 5 along the transverse direction. The anchoring structure includes a tunnel-type cap 2 and several pile foundations 1. The tunnel-type cap 2 is embedded in the tunnel 5 along the horizontal direction, and the lower end of the tunnel 5 is lower than the slope 4 at the entrance of the tunnel 5. A step is formed between the lower end of the tunnel 5 and the slope body 4, and a plurality of cylindrical pile holes are excavated vertically downward from the lower end of the tunnel 5, and a pile foundation 1 is arranged in each of the pile holes. The upper end of the pile foundation 1 is connected to the lower end of the tunnel-type cap 2, and the pile foundation 1 penetrates vertically downward into the lower good geological layer to resist the horizontal force borne by the anchorage structure.

As shown in FIG. 1 and FIG. 2 , the upper end of the tunnel-type cap 2 is arc-shaped, the upper end of the tunnel-type cap 2 is gradually raised from both sides to the center, and the upper end of the tunnel-type cap 2 is formed by It is inclined downward from front to back. The front end of the tunnel-type platform 2 includes a sloped section 21 and a vertical section 22 connected up and down in sequence. The sloped section 21 is inclined forward from top to bottom. The sloped section 21 Several anchor cables 3 are embedded.

The invention also discloses an installation method of the tunnel-type pile foundation cap combined anchorage structure, comprising the following steps:

Step 1) According to the design drawings, stake out the position of the tunnel 5 and excavate the tunnel 5;

Step 2) Arch frame, anchor rod and spray protection are applied in the excavation process as required, so that the vault, side wall and inverted arch structure meet the construction safety requirements, and the position of the pile mouth of pile foundation 1 is reserved during the construction of inverted arch spray protection;

Step 3) Complete the excavation and support of the tunnel 5, build the lock, and manually excavate the pile hole and the pile foundation 1;

Step 4) After the pile foundation 1 is completed, install the reinforcement cage, pour concrete, and reserve the pile head reinforcement of the pile foundation 1 as required, and the pile head reinforcement is connected to the tunnel cap 2 for anchorage;

Step 5) Chisel off the pile head, trim the overhanging steel bars of the pile head, and install the steel bar binding of the tunnel-type cap 2;

Step 6) Install the anchor cables 3 according to the quantity and position required by the design. After installing the tunnel 5 port formwork, pour concrete on the tunnel cap 2, so that the pile foundation 1 and the anchor cables 3 are connected through the tunnel cap 2 to form a whole.

During the specific implementation, the terrain conditions of a large-span arch bridge in a mountainous area are harsh, spanning a river and the slopes on both sides are steep, both ends of the bridge are directly connected to the tunnel, and there is basically no good construction site near the bridge site. Due to the steep hillside and the overhead crossing of several civil cables nearby, the relocation and demolition are difficult and the cost is huge, so the temporary construction anchors can only be arranged on both sides of the tunnel entrance.

Considering the serious weathering of the mountain surface, poor geological conditions within 50m of the surface layer, there are karst caves, and cracks are relatively developed, which is not suitable for the application of the rock anchor structure, so the tunnel-type pile foundation bearing platform combination anchor anchor structure involved in the present invention is used for construction.

According to the external load that the anchorage needs to bear, the slope of the slope body 4, the geological conditions, etc., the anchorage structure includes four pile foundations 1 with a diameter of φ2m, and the four pile foundations 1 are connected by a tunnel-type cap 2 into a whole. The plane size of the tunnel-type cap 2 is 8×8m, and an array of anchor cables 3 are arranged on the exposed inclined plane section 21 of the tunnel-type cap 2 according to the stress conditions.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (2)

1. A tunnel type pile foundation and bearing platform combined anchorage structure is characterized in that the anchorage structure is arranged in an oblique slope body, a tunnel is transversely arranged on the slope body, the anchorage structure comprises a tunnel type bearing platform and a plurality of pile foundations, the tunnel type bearing platform is embedded into the tunnel along the horizontal direction, the lower end of the tunnel is lower than a slope body at the entrance of the tunnel, a step is formed between the lower end of the tunnel and the slope body, a plurality of cylindrical pile holes are formed by vertically and downwardly excavating the lower end of the tunnel, a pile foundation is arranged in each pile hole, the upper end of the pile foundation is connected with the lower end of the tunnel type bearing platform,

the upper end of tunnel formula cushion cap is the arc, the upper end of tunnel formula cushion cap risees by both sides to central authorities gradually, the upper end of tunnel formula cushion cap sets up by preceding to the back down dip, the front end of tunnel formula cushion cap includes inclined plane section and the vertical section that connects gradually from top to bottom, the inclined plane section from top to bottom slopes forward and sets up, a plurality of anchor ropes have been buried underground to the inclined plane section.

2. A method for installing a tunnel type pile foundation and bearing platform combined anchorage structure is characterized by comprising the following steps:

step 1) according to a design drawing, lofting the position of a tunnel, and excavating the tunnel;

step 2) constructing an arch frame, an anchor rod and spray protection according to requirements in the excavation process, so that the arch crown, the side wall and the inverted arch structure meet the construction safety requirements, and the pile mouth position of a pile foundation is reserved during inverted arch construction spray protection;

step 3), completing tunnel excavation support, building a locking opening, and manually excavating pile holes and pile foundations;

step 4), after the pile foundation is finished, installing a reinforcement cage, pouring concrete, reserving pile head reinforcements of the pile foundation according to requirements, and connecting and anchoring the pile head reinforcements with the tunnel type bearing platform;

step 5), chiseling off the pile head, finishing the extending reinforcing steel bars of the pile head, and binding and installing the reinforcing steel bars of the tunnel type bearing platform;

and 6) installing the anchor cables according to the quantity and the positions required by the design, pouring concrete on the tunnel type bearing platform after installing the tunnel port template, and connecting the pile foundation and the anchor cables through the tunnel type bearing platform to form a whole.

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