CN114482021B - Method for solidifying preset reverse friction combined pile foundation soil and formed cast-in-place pile - Google Patents

Abstract

The invention relates to a method for preset reverse friction combined with pile bottom soil consolidation and the formed cast-in-place pile. A cast-in-place pile hole is drilled in the foundation, a high-strength air trap is placed at the bottom of the pile hole, and the cast-in-place pile is formed on the surface of the pile hole. Install a double-layer air pipe, and extend the double-layer air pipe out of the cast-in-place pile along the pile hole; inject pile material into the pile hole to form a pile; after the pile body of the cast-in-place pile solidifies for a few days, the double-layer air pipe is inserted into the cast-in-place pile through the double-layer air pipe. Inject air into the internal structure, and evacuate the external structure of the air column; after the cast-in-place pile has been consolidated for a period of time, stop injecting air into the internal structure of the air column, stop vacuuming the external structure of the air column, and pour soft soil at the bottom of the pile. Consolidation occurs; the fluid gel material is injected into the internal structure of the air box through the inner tube of the air conduit until the entire internal structure of the air box is filled; the present invention can effectively improve the side friction resistance of the pile and the pile end bearing capacity, so as to To achieve the purpose of improving the pile foundation bearing capacity.

Description

Method of presetting reverse friction resistance combined with pile subsoil consolidation and forming cast-in-place pile

Technical field

The invention relates to a method for presetting reverse friction combined with pile bottom soil consolidation and the formed cast-in-place pile. It belongs to the technology of increasing soft soil foundation and can be used in fields such as water conservancy projects and civil construction projects.

Background technique

Pile foundation is currently an important way to increase soft soil foundation. The bearing capacity of a pile mainly comes from the reaction force of the soil around the pile on the pile foundation when the pile foundation bears load, and the reaction force of the soil around the pile on the pile foundation comes from the frictional resistance on the pile side and the end bearing force of the pile bottom. Under normal circumstances, when a pile foundation is bearing a load, the pile body has a tendency to sink, and is displaced downward relative to the surrounding soil, and the pile body itself undergoes compressive strain, so the soil around the pile will produce upward lateral frictional resistance to the pile body. . The extent of the lateral friction resistance at a certain depth of the pile foundation is closely related to the strain of the pile foundation itself at that depth. The greater the strain, the greater the relative displacement between the pile body and the soil around the pile at that depth, and the lateral friction resistance of the soil around the pile. The more fully it is used, the greater the bearing capacity of the pile. However, for ordinary piles, the strain of the pile gradually becomes smaller along the depth, resulting in the lateral friction resistance often becoming smaller and smaller along the depth, and cannot be fully exerted.

At the same time, the soil at the bottom of the pile will produce an upward supporting force for the pile, that is, the end-bearing force; the end-bearing force of the pile end is often related to the softness of the soil at the pile end. The lower the moisture content of the soil at the pile end, the harder it will be. The greater the end bearing capacity. In actual situations, in soft soil areas, the end bearing capacity of the pile end is also small due to the smaller strength of the soil. In addition, for bored piles, a certain amount of sediment often remains at the bottom of the hole during the drilling process. As a result, after the pile is completed, the soil at the end of the pile is extremely weak, affecting the end-bearing capacity. The sum of the upward lateral frictional resistance and end-bearing force produced by the soil around the pile and the soil at the pile end is the bearing capacity of the pile.

Obviously, increasing the pile's side friction resistance and pile end bearing capacity are important ways to improve the pile's bearing capacity.

Contents of the invention

The invention provides a method for presetting reverse friction resistance combined with pile bottom soil consolidation and the formed cast-in-place pile, which can effectively improve the side friction resistance of the pile and the pile end bearing capacity, so as to achieve the purpose of improving the bearing capacity of the pile foundation.

The technical solutions adopted by the present invention to solve the technical problems are:

A method of presetting reverse friction resistance combined with pile bottom soil consolidation, specifically including the following steps:

Step S1: Drill cast-in-place pile holes in the foundation and perform hole forming operations;

Step S2: Place a high-strength air pot at the bottom of the pile hole, install a double-layer air conduit on the surface of the air pot, and extend the double-layer air conduit pipe out of the cast-in-place pile along the pile hole. The air pot has a double-layer structure. The internal structure of the air duct is connected to the inner tube of the double-layer air conduit, and the external structure of the air conduit is connected to the outer tube of the double-layer air conduit;

Step S3: Inject pile material into the pile hole to form a pile;

Step S4: After the cast-in-place pile body solidifies for several days, inject air into the internal structure of the air bowl through the double-layer air conduit, and evacuate the external structure of the air bowl;

Step S5: After the soft soil or sediment at the bottom of the cast-in-place pile has consolidated for a period of time, stop injecting air into the internal structure of the air bowl and stop vacuuming the external structure of the air bowl. The consolidation of the soft soil or sediment at the bottom of the cast-in-place pile ends;

Step S6: At this time, the internal structure of the air basket expands, and the fluid gel material is injected into the internal structure of the air basket through the inner tube of the air guide tube until the entire internal structure of the air basket is filled;

As a further preference of the present invention, the air basket includes an internal structure and an external structure, the outer structure is a water-permeable layer, the internal structure is the air basket body, and the water-permeable layer is wrapped around the outside of the air basket body;

As a further preference of the present invention, the pile material is concrete or solidified soil;

As a further preference of the present invention, in step S4, the solidification time of the cast-in-place pile body is 28 days;

As a further preference of the present invention, the inner tube of the double-layer air conduit is connected to the air pressure pump, and the outer tube of the double-layer air conduit is connected to the vacuum pump;

As a further preference of the present invention, in step S5, the time for the bottom soft soil or sediment to consolidate is 10-20 days;

The cast-in-place pile formed based on the method of preset reverse friction combined with soil consolidation at the bottom of the pile, includes a cast-in-place pile body, an air trap is provided at the bottom of the pile body of the cast-in-place pile body, and the inside of the air trap is filled with fluid gel material;

The remaining part of the cast-in-place pile body is filled with concrete or solidified soil.

Through the above technical solutions, compared with the existing technology, the present invention has the following beneficial effects:

1. The present invention provides an air trap at the bottom of the cast-in-place pile. After the air trap is inflated, it can generate a lifting force on the bottom of the cast-in-place pile. The soil around the pile forms upward lateral friction resistance on the pile, so that the lateral friction resistance at the bottom of the pile body is improved. ;

2. The air trap arranged at the bottom of the cast-in-place pile in the present invention has a two-layer structure. When the outer layer is evacuated, a negative pressure is formed in the soil at the bottom of the cast-in-place pile. The inner layer is inflated to form a squeezing force on the bottom of the pile. Under the positive and negative pressure, Under the joint action, the soft soil or sediment at the bottom of the pile is consolidated, which increases the strength of the soil at the bottom of the pile, thus increasing the end bearing capacity of the pile;

3. In the present invention, after the soft soil at the bottom of the pile is consolidated, the internal structure of the air box expands, and the injected high-strength gel material forms an enlarged pile bottom at the pile end, further improving the bearing capacity of the cast-in-place pile.

Description of the drawings

The present invention will be further described below in conjunction with the accompanying drawings and examples.

Figure 1 is a schematic structural diagram of a preferred embodiment provided by the present invention in which a high-strength gas trap is inserted after hole formation;

Figure 2 is a schematic diagram of the pile after the pile material is poured into the pile according to the preferred embodiment of the present invention;

Figure 3 is a schematic diagram of pressurizing and vacuuming through a double-layer air guide tube according to the preferred embodiment of the present invention;

Figure 4 is a schematic structural diagram of the preferred embodiment provided by the present invention after filling with high-strength filling materials;

Figure 5 is a schematic cross-sectional view of the double-layer air guide tube provided by the present invention.

In the picture: 1 is the cast-in-place pile, 2 is the pile hole, 3 is the double-layer air guide tube, 4 is the side friction resistance, 5 is the high-strength air trap, 6 is the fluid gel material, 7 is the lifting force, and 8 is the outer tube. , 9 is the inner tube.

Detailed ways

The present invention will now be described in further detail with reference to the accompanying drawings. In the description of this application, it should be understood that the orientation or positional relationship indicated by the terms "left side", "right side", "upper part", "lower part", etc. are based on the orientation or positional relationship shown in the drawings, and are only In order to facilitate the description of the present invention and simplify the description, it is not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and "first", "second", etc. do not refer to components. importance and therefore should not be construed as limitations of the invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of the present invention.

Pile foundation is an important way to increase the soft soil foundation, and it is crucial to improve its bearing capacity. Research shows that the factors affecting the bearing capacity of pile foundations mainly include two points. The first is the side friction resistance of the pile, which affects the degree of side friction resistance. The main factor is the strain of the pile foundation itself. The more fully the lateral friction resistance is exerted, the greater the bearing capacity of the pile. The second factor is the end bearing capacity of the pile. The main factor affecting its performance is the softness of the soil at the pile end. , so the greater the strength of the soil at the pile end, the greater the end bearing capacity.

In order to achieve the above-mentioned purpose of increasing the bearing capacity of the pile foundation, this application provides a method of presetting the reverse friction resistance and consolidating the pile subsoil, which can effectively improve the bearing capacity of the cast-in-place pile 1, specifically including the following steps:

Step S1: Drive the cast-in-place pile 1 into the foundation, perform a hole-forming operation on the cast-in-place pile (sinking cast-in-place pile or drilled cast-in-place pile), and form a pile hole 2 in the cast-in-place pile.

Step S2: As shown in Figure 1, place a high-strength air trap 5 at the bottom of the pile hole, install a double-layer air conduit 3 on the surface of the air cone, and extend the double-layer air conduit pipe out of the cast-in-place pile along the pile hole. The steamer is also a double-layer structure. For the convenience of explanation, the steamer is divided into two parts: the internal structure and the external structure. The outer structure is the water-permeable layer, and the inner structure is the air steamer body. The water-permeable layer is wrapped around the outside of the air steamer body. The air casing body is connected to the inner tube 9 of the double-layer air duct, and the water-permeable layer of the air casing is connected to the outer tube 8 of the double-layer air duct (as shown in Figure 5, the inner tube is used for high-pressure gas injection, and the outer tube is used for vacuum extraction); The permeable layer is made of high-strength permeable materials. When the permeable layer is vacuumed, drainage and air conduction channels can be formed.

Step S3: Inject pile material into the pile hole, and the pile material is concrete or solidified soil, as shown in Figure 2, to form a pile.

Step S4: After the cast-in-place pile body solidifies for several days (the hydration reaction time of the cement here is constrained to 28 days), the inner tube of the double-layer air conduit is connected to the air pressure pump, and the outer tube of the double-layer air conduit is connected to the vacuum pump, as shown in Figure 3 Indicates that air is injected into the internal structure of the air trap through the double-layer air duct, and the external structure of the air trap is evacuated; the air trap body will expand after being inflated, causing the pile body to have an upward lifting tendency, and the pile will move upward relative to the soil. The soil around the pile produces a downward lateral frictional resistance 4 on the pile. As the air body expands, the lifting force 7 is less than the lateral frictional resistance of the pile. In other words, the lateral frictional resistance of the pile in this application is much greater than that of the traditional pile;

At the same time, during the vacuuming process of the permeable layer, the vacuum negative pressure is transmitted from the outer tube to the bottom of the pile, forming a negative pressure in the soil at the bottom of the pile. In addition, the expansion of the air box itself will also form a squeezing force on the soil at the bottom of the pile. Under the combined action of negative pressure, the soil at the pile end is consolidated, resulting in an increase in the strength of the soil at the pile bottom, thereby increasing the pile end bearing capacity. The water generated during the consolidation is discharged from the pile body through the outer tube and passes through the negative pressure. Vacuum can once again effectively strengthen the soil at the pile end.

Step S5: After the soft soil or sediment at the bottom of the cast-in-place pile has consolidated for a period of time, here, depending on the properties of the soil, the time for the soft soil or sediment at the bottom to consolidate is 10-20 days, stop injecting gas into the internal structure of the air bowl. And stop vacuuming the external structure of the gas cylinder, that is, stop negative pressure consolidation and inflation, and the consolidation of soft soil or sediment at the bottom of the poured pile column is completed.

Step S6: At this time, the internal structure of the air trap expands. As shown in Figure 4, the fluid gel material 6 is injected into the internal structure of the air trap through the inner tube of the air guide tube until the entire internal structure of the air trap is filled. After the condensed material is filled , will solidify rapidly in a short period of time to form a high-strength solid. However, due to the consolidation of the soil at the bottom of the pile, the air mass will expand and the volume will be larger than the diameter of the pile. Therefore, the rapid solidification of the condensed material will form an enlarged pile bottom at the pile end. This It also effectively improves the bearing capacity of the pile; this approach can also achieve an effect. When the original pile body is drilled, a certain amount of residue will remain at the bottom of the hole, and the fluid gel material can avoid pile ends caused by the residue. Soil weakness problem.

The last main point to explain is that the air pressure formed by injecting air into the air pile body through the air pressure pump needs to be calculated in advance for the side friction resistance of the pile. The specific calculation method for this side friction resistance needs to be calculated and set according to actual needs, which will not be done here. Repeat.

The cast-in-place pile formed according to the above method, as shown in Figure 4, includes a cast-in-place pile body, an air bowl is provided at the bottom of the pile body, and the inside of the air bowl is filled with fluid gel material.

In summary, it can be seen that this application ultimately improves the pile bearing capacity by increasing the side friction resistance of the pile and the pile end bearing capacity.

It will be understood by one of ordinary skill in the art that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms such as those defined in general dictionaries are to be understood to have meanings consistent with their meaning in the context of the prior art, and are not to be taken in an idealized or overly formal sense unless defined as herein. explain.

The meaning of "and/or" mentioned in this application means that each exists alone or both exist at the same time.

The meaning of "connection" in this application may be a direct connection between components or an indirect connection between components through other components.

Taking the above-mentioned ideal embodiments of the present invention as inspiration and through the above description, relevant workers can make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the description, and must be determined based on the scope of the claims.

Claims (6)

1. A method of presetting reverse friction resistance and consolidating pile bottom soil, which is characterized by: specifically including the following steps: Step S1: Drill cast-in-place piles (1) and pile holes (2) in the foundation, and perform hole forming operations. ; Step S2: Place a high-strength air trap (5) at the bottom of the pile hole (2), install a double-layer air conduit (3) on the surface of the air cone, and connect the double-layer air conduit (3) along the pile hole (2) ) stretches out the cast-in-place pile (1), in which the air basket has a double-layer structure. The internal structure of the gas basket is connected with the inner tube (9) of the double-layer air guide tube (3). The external structure of the air basket is connected with the double-layer air guide tube (3). ) is connected to the outer tube (8); Step S3: Inject pile material into the pile hole (2) to form a pile; Step S4: After the cast-in-place pile (1) solidifies for several days, air is injected into the internal structure of the air bowl through the double-layer air conduit (3), and the external structure of the air bowl is evacuated; Step S5: After the soft soil or sediment at the bottom of the cast-in-place pile (1) has solidified for a period of time, stop injecting air into the internal structure of the air bowl and stop vacuuming the external structure of the air bowl. The soft soil at the bottom of the cast-in-place pile (1) or sediment consolidation ends; Step S6: At this time, the internal structure of the air basket expands, and the fluid gel material (6) is injected into the internal structure of the air basket through the inner tube (9) of the air guide tube until the entire internal structure of the air basket is filled; The air steamer includes an internal structure and an outer structure. The outer structure is a water-permeable layer, the inner structure is the air steamer body, and the water-permeable layer is wrapped around the air steamer body. 2. The method of presetting reverse friction resistance combined with pile bottom soil consolidation method according to claim 1, characterized in that: the pile material is concrete or solidified soil. 3. The method of presetting reverse friction resistance combined with pile subsoil consolidation according to claim 1, characterized in that in step S4, the solidification time of the cast-in-place pile (1) body is 28 days. 4. The method of preset reverse friction combined with pile subsoil consolidation according to claim 1, characterized in that: the inner tube (9) of the double-layer air conduit (3) is connected to the air pressure pump, and the double-layer air conduit (3) is connected to the air pressure pump. The outer tube (8) of 3) is connected to the vacuum pump. 5. The method of preset reverse friction combined with pile bottom soil consolidation according to claim 1, characterized in that: in step S5, the time for the soft soil or sediment at the bottom of the cast-in-place pile (1) to consolidate is 10-20 days. . 6. The cast-in-place pile (1) formed based on the method of preset reverse friction combined with pile subsoil consolidation according to any one of claims 1 to 5, characterized in that: it includes a cast-in-place pile (1) body, a cast-in-place pile (1) ) The bottom of the pile body is provided with an air bowl, and the inside of the air bowl is filled with fluid gel material (6); Cast-in-place pile (1) The remaining part of the pile body is filled with concrete or solidified soil.