CN107059882A - Arch anchor net and Anchor-Pile Retaining Structure structure - Google Patents

Abstract

The invention discloses an arch anchor net and pile-anchor combined support structure, which is arranged on the side wall of the foundation pit. The structure includes several support piles fixed on the inner bottom of the foundation pit along the vertical direction, The waist beam between the two supporting piles and the arched baffle connected between the two adjacent supporting piles pass through the arched baffle to the side wall soil of the foundation pit. A plurality of soil nails are extended, and a plurality of prestressed anchor rods are extended into the soil body of the side wall of the foundation pit through the waist beam and the support pile. Beneficial effects of the structure: (a) by adding an arched baffle and supporting piles as a whole, the lateral stiffness is increased, and the deformation and reinforcement of the supporting piles are reduced; (b) the arched baffle is equipped with Soil nails reduce the stress on the supporting piles, thereby reducing the length of the anchor rods; (c) the arched baffle has both soil and water retaining functions, which has changed the shortcomings of the traditional pile-anchor support system.

Description

Combined support structure of arched anchor net and pile-anchor

technical field

The invention relates to a foundation pit support system, in particular to an arched anchor net and pile-anchor joint support structure.

Background technique

The foundation pit refers to the space below the ground excavated for the purpose of building the foundation and basement of buildings (including structures), burying municipal engineering pipelines, and developing underground spaces (such as underground stations, shopping malls, etc.). Foundation pit support refers to engineering measures such as support, reinforcement and protection for the side walls of the foundation pit and the surrounding environment to protect the safety of the underground structure and the surrounding environment of the foundation pit.

The basic types of support structures for foundation pit engineering include: grading excavation and simple support, cantilever support structure, cement-soil pile wall support structure, internal support structure, pile-anchor support structure, soil Nail wall support structures, top-down methods and other support structures. Among these foundation pit support structures, the pile-anchor support structure is a frequently used support structure, and has been continuously and widely used.

The pile-anchor support structure is composed of reinforced concrete pouring piles and horizontal or oblique prestressed anchor rods. The pile-anchor support structure can be divided into single-point pile-anchor support structures according to the excavation depth of the foundation pit and the surrounding environment of the foundation pit. And multi-pivot pile-anchor support structure. The prestressed anchor is composed of a free section and an anchor section, and the prestress applied by the anchor is borne by the anchoring force provided by the anchor section of the anchor.

During the excavation of the foundation pit, due to the pressure of the foundation pit soil, the pile body of the supporting pile is in a state of bending, and the anchor rod is in a state of tension. Because the anchor provides support for the pile body, the internal force distribution of the pile body tends to be even under the action of horizontal earth pressure, and the force on the pile body is more reasonable than that in the cantilever state. The pre-applied anchor bolt prestress enables the pile-anchor support structure to effectively control the horizontal displacement of the pit wall during the excavation of the foundation pit, greatly improves the anti-overturning stability, and significantly shortens the embedded depth of the pile body , Construction difficulty and engineering investment are greatly reduced. Therefore, the pile-anchor support structure, as a commonly used support structure form in engineering practice, is widely used in support engineering.

However, the existing technology has the following two major disadvantages: (1) The lateral stiffness of the pile row is small. Under the action of earth pressure, a large bending moment will usually occur near the mid-span, and relatively large bending deformation will occur, making the cast-in-place pile (2) When the depth of the foundation pit is large or the soil condition is poor, the prestress provided by the anchor is usually high, and a large anchorage length is required at this time, and usually the foundation pit The surrounding environment is relatively poor, the urban geological environment is relatively complex, the groundwater level is high, and the space available outside the pit is small, which has brought great restrictions to the application of the pile-anchor support structure, and also imposed great restrictions on the application of the pile-anchor support structure. The design and construction of the project brought great difficulties.

Contents of the invention

The embodiment of the present invention provides an arched anchor net and pile-anchor combined support structure, which has high strength, and has the functions of retaining soil and water, and is easy to implement.

Arched anchor net and pile-anchor joint support structure is arranged on the side wall of the foundation pit, and the structure includes several support piles fixed on the inner bottom of the foundation pit along the vertical direction, connected to at least two adjacent support piles. The waist beam between the retaining piles and the arched baffles connected between the two adjacent supporting piles pass through the arched baffles and extend into the soil body of the side wall of the foundation pit. Nails, passing through the waist beam and the support piles to extend into the soil body of the side wall of the foundation pit are provided with several prestressed anchor rods.

Preferably, the arched baffle is arc-shaped.

Preferably, the waist beam, the soil nail and the prestressed anchor rod are all steel structures.

Preferably, both the support piles and the arched baffle are of concrete structure.

Preferably, the prestressed anchor rod is arranged inclined downward.

Preferably, the waist beam includes a plurality of upper and lower parallel beams.

Beneficial effects of the support structure of the present invention: (a) by adding an arched baffle and connecting the support piles into a whole, the lateral stiffness is increased, and the deformation and reinforcement amount of the support piles are reduced; (b) the arched Adding soil nails in the baffle reduces the stress on the supporting piles, thereby reducing the length of the anchor rod; (c) the arched baffle has both soil and water retaining functions, which has changed the shortcomings of the traditional pile-anchor support system .

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the structural schematic diagram (soil body transparent schematic) of the arched anchor net and pile-anchor combined support structure provided by the embodiment of the present invention;

Fig. 2 is the top view of the arched anchor net and pile-anchor combined support structure provided by the embodiment of the present invention (transparent soil body schematic);

Fig. 3 is the force diagram 1 of the arched anchor net and pile-anchor combined support structure provided by the embodiment of the present invention;

Fig. 4 is the force diagram 2 of the arched anchor net and pile-anchor combined support structure provided by the embodiment of the present invention.

Explanation of reference signs:

1-support pile, 2-waist beam, 3-arch baffle, 4-soil nail, 5-prestressed anchor rod;

A-the force of the soil on the supporting structure, B-the tension of the prestressed anchor rod; C-the tension of the soil nail.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

As shown in Figure 1 and Figure 2, an arch anchor net and pile-anchor combined support structure is arranged on the side wall of the foundation pit, and the structure includes several support piles 1, The waist beam 2 connected between at least two adjacent support piles 1 and the arched baffle 3 connected between the adjacent two described support piles 1 pass through the The arched baffle 3 extends into the soil body of the side wall of the foundation pit, and several soil nails 4 are arranged, and a plurality of prestressed anchors are arranged extending through the waist beam 2 and the support pile 1 into the soil body of the side wall of the foundation pit. Rod 5, the arched baffle plate 3 is arc-shaped arched, wherein the prestressed anchor rod 5 includes a free section close to the support pile 1 and an anchoring section connected to the free section, the waist beam 2. The soil nails 4 and the prestressed anchor rods 5 are steel structures, the support piles 1 and the arched baffles 3 are all concrete structures, and the prestressed anchors The rod 5 is arranged obliquely downwards, and the waist beam 2 includes a plurality of vertically arranged in parallel.

As shown in Figure 3 and Figure 4, the force A of the soil on the side wall of the foundation pit on the entire support structure is composed of the horizontal component of the tension B of the prestressed anchor rod 5 and the horizontal direction of the tension C of the soil nail 4 The components are used to balance, so as to ensure that the entire structure does not collapse and ensure construction safety.

In this support structure: (1) the support pile 1 acts as a retaining wall and bears the horizontal pressure from the soil on the side wall of the foundation pit; (2) the arched baffle 3 forms a space rigidity, Form a whole to reduce the horizontal deformation of the support system; (3) The prestressed anchor rod 5 is divided into a free section and an anchor section, which plays the role of tensioning and supporting the pile 1, and at the same time reduces the horizontal deformation of the pile; (4) The soil nail 4 Anchored in the soil, it plays the role of pulling the arched baffle 3; (5) the waist beam 2 fixes the prestressed anchor rod 5, and at the same time forms a whole with the support pile 1, and plays the role of a ring beam.

The supporting structure of the present invention is through laboratory experiments and field experiments, and the results show that: (a) arched anchor nets can be set between piles to form a continuous soil retaining structure together with the pile body, and the structural rigidity can be increased by more than 30%, which plays a limiting role. The effect of pile-soil displacement; the soil pressure values behind the pile and the arch slab are not much different, and the distribution forms are basically similar. The pressure plays an adjustment role, so that the deformation and reinforcement of the pile are smaller than those without the arched baffle; (b) soil nails are added in the arched baffle to share 20%-30% of the earth pressure, reducing The pressure acting on the support pile is reduced, thereby reducing the length of the anchor rod; (c) the overall structural system formed by the support pile and the arched baffle has a good function of retaining soil and water, and provides a good foundation for the building. Construction provides good working conditions.

In summary, the support structure of this design can achieve the following technical effects: (a) By adding an arched baffle and connecting the support piles as a whole, the lateral stiffness is increased, and the deformation and reinforcement of the support piles are reduced; (b) Soil nails are added in the arched baffle, which reduces the stress on the supporting piles, thereby reducing the length of the anchor rod; (c) The arched baffle has both soil and water retaining functions, changing the traditional pile anchor deficiencies in the protection system.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies thereof, the present invention also intends to include these modifications and variations.

Claims (6)

1. Arched anchor net and pile-anchor joint support structure, which is arranged on the side wall of the foundation pit, is characterized in that the structure includes several support piles fixed on the inner bottom of the foundation pit along the vertical direction, connected to adjacent at least The waist beam between the two support piles and the arched baffle connected between the adjacent two described support piles pass through the arched baffles into the soil body of the side wall of the foundation pit A plurality of soil nails are extended, and a plurality of prestressed anchor rods are extended into the soil body of the side wall of the foundation pit through the waist beam and the support pile. 2. The arched anchor net and pile-anchor combined support structure according to claim 1, wherein the arched baffle is arc-shaped. 3. The arched anchor net and pile-anchor combined support structure according to claim 1, wherein the waist beam, the soil nail and the prestressed anchor rod are all steel structures. 4. The arch anchor net and pile-anchor combined support structure according to claim 1, characterized in that, both the support piles and the arch baffle are of concrete structure. 5. The combined support structure of arched anchor net and pile-anchor as claimed in claim 1, characterized in that, said prestressed anchor rods are arranged inclined downward. 6. The arched anchor net and pile-anchor joint support structure according to claim 1, characterized in that, the waist beams include a plurality of upper and lower parallel beams.