A composite pile type that uses active isolation to reduce side friction.

Abstract

This utility model discloses a composite pile type that reduces side friction by employing active isolation, belonging to the field of pile foundation construction technology. It includes a solidified soil pile, a precast pile, an active isolation layer, and a pile cap. The active isolation layer is located at the interface between the solidified soil pile and the in-situ soil, and is coaxially arranged with the solidified soil pile and the precast pile. The pile cap is located at the upper end of the solidified soil pile and makes frictional contact with it. The pile cap consists of a circular annular plate and two sleeves of different sizes. The circular annular plate is welded to both the inner and outer sleeves. The inner diameter of the circular annular plate is the same as that of both the inner and outer sleeves, and the diameter of the outer sleeve is 1.0-1.05 times that of the outer sleeve. By setting an active isolation layer between the solidified soil pile and the undisturbed soil in the composite pile, the problem of settlement during and after construction in soft soil or filled soil areas is eliminated.

Description

Technical Field

[0001] This utility model belongs to the field of pile foundation construction technology, specifically relating to a composite pile type that uses active isolation to reduce side friction. Background Technology

[0002] Pile foundations are widely used in modern civil engineering due to their high vertical stiffness and bearing capacity, low settlement, and ability to withstand certain horizontal loads. However, when constructing pile foundations in soft soil or special soil strata (such as deep fill strata), the downward displacement of the surrounding soil often exceeds the downward displacement of the pile itself due to factors such as soil consolidation under its own weight, subsidence, lowering of the groundwater level, or surface overloading. This results in downward friction on the pile, creating a downward tension load on the pile sides—the so-called negative friction. The presence of negative friction increases the load on the pile, reduces the bearing capacity of the compression pile, and may lead to excessive settlement, causing building tilting and cracking, directly affecting the functionality and safety of the engineering structure. Therefore, reducing negative friction on the pile has become a key concern in the engineering field.

[0003] Currently, commonly used methods for eliminating negative skin friction are mainly divided into two categories: one is to control the source of negative skin friction, that is, to eliminate the harmfulness of the soil itself that is prone to generating negative friction through foundation treatment methods (dynamic compaction, preloading consolidation, etc.). This method has a long construction cycle and is generally not effective for deep soil layers. The other is to isolate the pile body from the surrounding soil. This type of method is more commonly used, including coating the pile surface with an asphalt film, installing unloading sleeves, installing protective sleeves, and driving isolation piles. This type of method has a more complex processing technology, which increases the manufacturing cost of the pile. While reducing negative friction, it also reduces positive friction.

[0004] In summary, the technology for eliminating negative skin friction in deep soft soil layers and backfilled areas still requires further research. Although many scholars have conducted extensive research and achieved some results, the methods for eliminating negative skin friction are still incomplete. Based on this, this invention proposes a composite pile type that uses active isolation to reduce side skin friction. Summary of the Invention

[0005] To address the aforementioned technical problems in existing technologies, this utility model proposes a composite pile type that employs active isolation to reduce side friction, overcoming the shortcomings of existing technologies. By setting an active isolation layer between the solidified soil pile and the undisturbed soil in the composite pile, the impact of settlement during and after construction on the pile foundation in soft soil or filled soil areas is eliminated.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A composite pile type that reduces side friction by using active isolation is characterized by comprising a solidified soil pile, a precast pile, an active isolation layer, and a pile cap. The active isolation layer is located at the interface between the solidified soil pile and the in-situ soil and is arranged coaxially with the solidified soil pile and the precast pile. The pile cap is located at the upper end of the solidified soil pile and is in frictional contact with the solidified soil pile. The pile cap is composed of a circular annular plate and two sleeves of different sizes. The circular annular plate is welded to both the inner and outer sleeves. The inner diameter of the circular annular plate is the same as that of the inner and outer sleeves. The diameter of the outer sleeve is 1.0-1.05 times that of the outer sleeve.

[0008] Preferably, the pile cap is made of steel, and the surface of the pile cap is coated with an anti-corrosion layer. The outer diameter of the annular plate is 1.2-1.5 times that of the large sleeve.

[0009] Preferably, the flexible isolation material is characterized by high viscosity, high structural strength, strong stability in underground environments, gel-like structure, ability to support its own weight and suspended particles, resistance to sedimentation or segregation, strong adsorption of water molecules, and resistance to dehydration even under pressure, such as bentonite materials.

[0010] The beneficial technical effects of this utility model are as follows:

[0011] By setting an active isolation layer between the solidified soil pile and the original soil in the composite pile, the problem of settlement during and after construction in soft soil areas or filled soil areas can be eliminated. Attached Figure Description

[0012] Figure 1 This is a schematic cross-sectional view of the overall structure in the construction method of reducing the side friction of composite piles based on active isolation according to this utility model.

[0013] Figure 2 The image shows a three-view drawing of the pile cap in a construction method for reducing the side friction of composite piles based on active isolation, according to this utility model.

[0014] Among them, 1-solidified soil pile, 2-precast pile, 3-active isolation layer, 4-pile cap. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Example 1:

[0016] like Figure 1-2As shown, a composite pile type that uses active isolation to reduce side friction is characterized by comprising a solidified soil pile 1, a precast pile 2, an active isolation layer 3, and a pile cap 4. The active isolation layer 3 is located at the interface between the solidified soil pile 1 and the in-situ soil, and is arranged coaxially with the solidified soil pile 1 and the precast pile 2. The pile cap 4 is located at the upper end of the solidified soil pile 1 and is in frictional contact with the solidified soil pile 1. The pile cap 4 is composed of a circular ring plate and two sleeves of different sizes. The circular ring plate and the large and small sleeves are connected by welding. The inner diameter of the circular ring plate is the same as that of the inner sleeve and the small sleeve. The diameter of the large sleeve is 1.0-1.05 times the diameter of the outer sleeve.

[0017] Preferably, the pile cap 4 is made of steel, and the surface of the pile cap 4 is coated with an anti-corrosion layer. The outer diameter of the annular plate is 1.2-1.5 times that of the large sleeve.

[0018] Preferably, the flexible isolation material is characterized by high viscosity, high structural strength, strong stability in underground environments, gel-like structure, ability to support its own weight and suspended particles, resistance to sedimentation or segregation, strong adsorption of water molecules, and resistance to dehydration even under pressure, such as bentonite materials. Example 2:

[0019] like Figure 1-2 As shown, a composite pile type that uses active isolation to reduce side friction is characterized by comprising a solidified soil pile 1, a precast pile 2, an active isolation layer 3, and a pile cap 4. The active isolation layer 3 is located at the interface between the solidified soil pile 1 and the in-situ soil, and is arranged coaxially with the solidified soil pile 1 and the precast pile 2. The pile cap 4 is located at the upper end of the solidified soil pile 1 and is in frictional contact with the solidified soil pile 1. The pile cap 4 is composed of a circular ring plate and two sleeves of different sizes. The circular ring plate and the large and small sleeves are connected by welding. The inner diameter of the circular ring plate is the same as that of the inner sleeve and the small sleeve. The diameter of the large sleeve is 1.0-1.05 times the diameter of the outer sleeve.

[0020] Preferably, the pile cap 4 is made of steel, and the surface of the pile cap 4 is coated with an anti-corrosion layer. The outer diameter of the annular plate is 1.2-1.5 times that of the large sleeve.

[0021] Preferably, the flexible isolation material is characterized by high viscosity, high structural strength, strong stability in underground environments, gel-like structure, ability to support its own weight and suspended particles, resistance to sedimentation or segregation, strong adsorption of water molecules, and resistance to dehydration even under pressure, such as bentonite materials.

[0022] The specific implementation of this structure is as follows:

[0023] Step 1: Constructing and solidifying soil piles 1

[0024] According to the design requirements, a mixing drill is used to form solidified soil mixing piles at the designed pile locations; the solidified soil pile 1 can be formed using mixing equipment, rotary drilling equipment, long spiral equipment, etc.

[0025] Step 2: Implanting precast piles 2

[0026] According to the design requirements, precast piles 2 are concentrically inserted into solidified soil pile 1 to the set depth;

[0027] Step 3: Forming holes in the active isolation layer 3

[0028] Using a double-casing drilling rig, along the interface between the solidified soil pile 1 and the original soil, the concentric double-casing structure is squeezed into the boundary between the solidified soil pile 1 and the original soil. The double-casing structure can be regarded as a whole structure. It is directly lowered to the designated depth by the double-casing drilling rig. During the lowering process, the lower ends of the inner and outer casings are kept closed, that is, there is nothing in the cavity between the inner and outer casings, until the inner and outer casings are lowered to the designated depth.

[0029] Step 4: Pull out the double-sleeve structure

[0030] After the solidified soil pile 1 has initially set and has a certain self-stabilizing ability, the double-sleeve structure is pulled out after initial setting. Since the inner wall of the inner sleeve and the outer wall of the outer sleeve are provided with drag-reducing layers, the pull-out is relatively easy. During the vibration pull-out process, the solidified soil pile body will not collapse. Flexible isolation material is poured into the space between the inner sleeve and the outer sleeve of the double-sleeve structure while the double-sleeve structure is vibrated and lifted. At the same time, the lower end between the inner and outer sleeves is in an open state, and the flexible isolation material is lowered from between the inner and outer sleeves. As the double-sleeve structure is pulled out, the flexible isolation material fills the cavity after the pull-out until the flexible isolation material is poured to the set height as required by the design.

[0031] Step 5: Install pile cap 4

[0032] The double-casing drilling rig and the double casing are moved as a whole and left to stand for a set time, which is the time it takes for the solidified soil pile 1 to reach final set, ranging from 6 to 10 hours. The pile cap 4 is concentrically placed into the annular active isolation layer 3 as a pile head protection device. After the cement-soil strength reaches the design strength, the pile foundation construction is completed. In order to protect the stability of the composite pile and the active isolation layer 3, after the solidified soil pile 1 has initially set, the small casing of the pile cap 4 is directly fitted onto the already formed solidified soil pile 1, and the large casing is inserted into the outside of the active isolation layer 3. In this way, the inner side of the small casing in the pile cap 4 is bonded to the solidified soil pile 1, and the outer side of the large casing is in frictional contact with the soil.

[0033] In the description of the embodiments of this utility model, it should be understood that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In the description of this utility model, it should be noted that unless otherwise explicitly specified and limited, the terms "set" and "connected" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication of two elements. Those skilled in the art can understand the specific meaning of the above terms in this utility model through specific circumstances.

[0034] Of course, the above description is not intended to limit the present utility model, and the present utility model is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present utility model are also within the protection scope of the present utility model.

Claims

1. A composite pile type for reducing side friction in the form of active isolation, characterized by: It includes solidified soil piles, precast piles, an active isolation layer, and pile caps. The active isolation layer is set at the interface between the solidified soil piles and the in-situ soil, and is arranged coaxially with the solidified soil piles and precast piles. The pile cap is set at the upper end of the solidified soil piles and is in frictional contact with the solidified soil piles. The pile cap consists of a circular ring plate and two sleeves of different sizes. The circular ring plate and the large and small sleeves are connected by welding. The inner diameter of the circular ring plate is the same as that of the inner sleeve and the small sleeve. The diameter of the large sleeve is 1.0-1.05 times the diameter of the outer sleeve.

2. The composite pile type according to claim 1, which uses active isolation to reduce side friction, is characterized in that: The pile cap is made of steel and coated with an anti-corrosion layer. The outer diameter of the circular plate is 1.2-1.5 times that of the large sleeve.

3. The composite pile type according to claim 1, which uses active isolation to reduce side friction, is characterized in that: Flexible isolation materials are characterized by high viscosity, high structural strength, strong stability in underground environments, gel-like structure, ability to support their own weight and suspended particles, resistance to sedimentation or segregation, and ability to firmly adsorb water molecules, making them resistant to dehydration even under pressure, such as bentonite materials.

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