CN114960617A

CN114960617A - Tunnel foundation pit bottom dislocation hidden pier reinforcement system and reinforcement method thereof

Info

Publication number: CN114960617A
Application number: CN202210558912.5A
Authority: CN
Inventors: 楼佳悦; 章李刚; 陈常科; 周文俊; 郝舰艇; 李毅; 周亚洲; 徐长节; 梁禄钜; 管凌霄
Original assignee: East China Jiaotong University; Zhejiang Huayun Electric Power Engineering Design Consulting Co
Current assignee: East China Jiaotong University; Zhejiang Huayun Electric Power Engineering Design Consulting Co
Priority date: 2022-05-21
Filing date: 2022-05-21
Publication date: 2022-08-30

Abstract

The invention relates to a tunnel foundation pit bottom dislocation hidden pier reinforcement system and a corresponding reinforcement method, wherein the method comprises the following steps: drilling a hole in a soil body below the tunnel to form a grouting reinforcement area, and grouting the reinforcement area to form a hidden pier; the grouting reinforcement areas are distributed in the soil body below the tunnel in a staggered mode on two sides in the width direction of the tunnel, one side of each grouting reinforcement area is tangent to the boundary of one side of the tunnel, and a distance larger than zero is reserved between the other side of each grouting reinforcement area in the width direction of the tunnel and the boundary of the other side of the tunnel; compared with the traditional integral grouting, the reinforcing system and the reinforcing method adopting the technical scheme can reduce the using amount of grouting materials, greatly reduce the construction cost, effectively avoid the settlement of the tunnel bottom while reducing the waste, flexibly change the total area occupation ratio of the grouting reinforcing area according to the mechanical property of the original soil body, reduce the construction area and effectively accelerate the construction progress.

Description

Tunnel foundation pit bottom dislocation hidden pier reinforcement system and reinforcement method thereof

Technical Field

The invention relates to a foundation pit bottom soil body grouting reinforcement technology, and belongs to the technical field of foundation pit engineering.

Background

Along with urbanization development, more and more underground pipe gallery tunnels are used for municipal pipe network construction and transmission and distribution lines cable engineering project, and tunnel laying construction has become one of the inevitable directions of GIL (gas insulated metal enclosed transmission line) electric power pipeline construction technical development, and the excavation foundation ditch is needed in the tunnel of building. After the tunnel is built, the bottom of the foundation pit is easy to subside due to the self-weight effect of the tunnel, and the safety of the engineering is threatened. The reason for the settlement is mainly because the mechanical property of the soil body at the bottom of the tunnel is poor.

The grouting reinforcement technology has a great effect on improving the mechanical property of the soil body, in the prior art, the soil body at the bottom of the tunnel is generally subjected to grouting reinforcement, and the method can improve the mechanical property of the soil body so as to reduce pit bottom settlement. However, the method for grouting and reinforcing all the soil bodies at the bottom of the pit does not consider the reinforcement requirements under different soil body strength conditions, generally has high cost, generates certain waste on materials, and has relatively long construction time. Therefore, the design of the reinforcement technology which can meet the settlement requirement and save materials and working hours is very significant.

Disclosure of Invention

In order to solve the technical problems, the invention provides a system for reinforcing a hidden pier staggered at the bottom of a tunnel foundation pit, which comprises a grouting reinforcement area in a soil body below a tunnel, wherein the grouting reinforcement area is distributed in a staggered manner at two sides along the width direction of the tunnel in the soil body below the tunnel, one side of the grouting reinforcement area is tangent to one side boundary of the tunnel, and a distance greater than zero is reserved between the other side of the grouting reinforcement area along the width direction of the tunnel and the other side boundary of the tunnel.

Further, the interval between two adjacent grouting reinforcement areas along the length direction of the tunnel is d, and the value range of d is as follows: -0.3L < d <0.3L, where L is the width of the tunnel.

Furthermore, the depth of the grouting reinforcement area is 0.2H-0.6H, wherein H is the excavation depth of the foundation pit.

Further, the section of the grouting reinforcement area in the horizontal direction is circular, the diameter of the circle is between 0.3L and 0.6L, and L is the width of the tunnel.

Further, the section of the grouting reinforcement area in the horizontal direction is rectangular, the side length of the rectangle is 0.3L-0.6L, and L is the width of the tunnel.

Based on the reinforcing system, the invention also relates to a method for reinforcing the staggered hidden pier at the bottom of the tunnel foundation pit, which comprises the following steps: drilling a hole in a soil body below the tunnel to form a grouting reinforcement area, and grouting the reinforcement area to form a hidden pier; the grouting reinforcement areas are distributed in the soil body below the tunnel in a staggered mode on two sides in the width direction of the tunnel, one side of each grouting reinforcement area is tangent to one side boundary of the tunnel, and a distance larger than zero is reserved between the other side of each grouting reinforcement area in the width direction of the tunnel and the other side boundary of the tunnel.

Compared with the traditional integral grouting, the reinforcing system and the reinforcing method adopting the technical scheme greatly reduce the using amount of grouting materials, greatly reduce the construction cost, reduce the sedimentation of the tunnel pit bottom while reducing the waste, meet the requirement of the sedimentation of the tunnel pit bottom, flexibly change the total area occupation ratio of a grouting reinforcing area according to the mechanical property of the original soil body and save the materials to the maximum extent. Because the construction area is reduced, the construction is more convenient, the construction progress can be effectively accelerated, and the workload is reduced.

Drawings

The accompanying drawings, in which like references indicate similar elements, illustrate exemplary embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:

fig. 1 is a top view of a foundation pit bottom dislocation pier reinforcement system in embodiment 1 of the invention.

Fig. 2 is a top view of a foundation pit bottom dislocation pier reinforcement system in embodiment 2 of the invention.

Fig. 3 is a front view of the foundation pit bottom dislocation pier reinforcement system in the embodiment 1 and 2 of the invention.

Fig. 4 is a side view of foundation pit bottom dislocation pier reinforcement system in the embodiment 1 and 2 of the invention.

Reference numbers in the figures: 1 is a hidden pier formed by grouting reinforcement; 2 is a tunnel structure; and 3, a foundation pit.

Detailed Description

In the present invention, the term "and/or" is intended to cover all possible combinations and sub-combinations of the listed elements, including any one, any sub-combination, or all of the elements listed individually, without necessarily excluding other elements. Unless otherwise specified, the terms "first", "second", and the like are used to describe various elements and are not intended to limit the positional relationship, timing relationship, or importance relationship of the elements, and such terms are used merely to distinguish one element from another. Unless otherwise indicated, the terms "front, back, upper, lower, left, right" and the like indicate orientations or positional relationships that are generally based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and are not to be construed as limiting the scope of the present invention.

The invention adopts a staggered grouting reinforcement technology, in particular to grouting reinforcement by staggering soil mass at the bottom of a tunnel in different areas, and the grouting reinforcement can be divided into three categories of infiltration grouting, split grouting and compaction grouting according to the interaction mode of flowing grout and the soil mass. The grouting mode can be reasonably selected according to the condition of the soil property of the concrete engineering. And grouting reinforcement time is used for construction when foundation pit excavation is completed, and construction is convenient at the moment.

During construction, grouting and reinforcing soil bodies on two sides of a foundation pit in a staggered mode, wherein the staggered mode can refer to fig. 1, and the section shape of a reinforced area can be selected according to actual construction needs, such as rectangular area reinforcement or circular area reinforcement; the grouting reinforcement areas at the bottom of the foundation pit are distributed on two sides of the soil body below the tunnel in a staggered manner, one side of each grouting reinforcement area is tangent to one side boundary of the tunnel, the other side of each grouting reinforcement area in the width direction of the tunnel is away from the other side boundary of the tunnel by a certain distance, and the tangency is defined as that one side of a rectangle is basically overlapped with one side boundary of the tunnel under the condition of the rectangular reinforcement areas as shown in figure 1; in the case of a circular reinforcing region, as shown in fig. 2, the tangent line defined as a circle coincides with one side boundary of the tunnel.

The specific size of the reinforced area can be selected according to the actual soil strength. Assuming that the width of the GIL tunnel structure is L, the dimension of the reinforcing region in the width direction of the foundation pit is preferably between 0.3L and 0.6L, and the dimension of the reinforcing region in the length direction of the foundation pit is preferably between 0.3L and 0.6L. Specifically, if the cross section of the reinforcing region is rectangular, the dimension is the length and width of the rectangle, and if the cross section of the reinforcing region is circular, the dimension is the diameter of the circle. Similarly, the grouting reinforcement depth (i.e. the depth of the reinforcement area) may also be selected according to the actual soil strength, as shown in fig. 3, in the actual construction, the depth of the grouting reinforcement area is preferably 0.2H-0.6H (where H is the excavation depth of the foundation pit).

As shown in fig. 4, two adjacent reinforcement areas along the length direction of the foundation pit have a gap d in the length direction of the foundation pit, and the value of "d" can be determined by comprehensively referring to the size of the reinforcement area or the mechanical properties and settlement requirements of the original soil body, for example, d may be preferably in the range of-0.3L, and when the value of d is 0, it means that the two adjacent reinforcement areas may contact each other; when d is less than 0, it means that two adjacent reinforced areas may overlap in the length direction of the foundation pit. The spacing d between two adjacent reinforcement areas is preferably equal, meaning that the reinforcement areas are evenly distributed on both sides of the foundation pit. But the size, depth and spacing of the reinforced areas can also be set to be different according to the soil conditions of different areas.

The following describes a specific embodiment of the present invention through examples 1 to 3, and for illustrating the specific embodiment, a certain GIL open cut tunnel foundation pit engineering size is taken as an example: the excavation depth of the engineering foundation pit is 7m, the width of the engineering foundation pit is 8m, the tunnel is a square tunnel, the side length L of the tunnel is 5m, C40 reinforced concrete is adopted for pouring, and the strength of a soil body below the tunnel is 12.6 Mpa. The following embodiments all take reinforcement area values with this engineering size:

example 1

As shown in fig. 1, in order to prevent the tunnel from settling after construction, a rectangular grouting area is used to reinforce the area, where the length × width is 0.4L × 0.4L is 2m × 2m, and the grouting reinforcement depth is 0.3H is 2.1 m. The distance d is 0.5m because the strength of the soil body under the tunnel is enough.

Description of cost saving: if a mode of grouting reinforcement of the whole area below the tunnel is adopted, the reinforcement depth is generally 0.2H to 1.4 m, the reinforcement length of 10m is the volume of 70 cubic meters, and the method of the embodiment 1 of the invention only needs to reinforce 33.6 cubic meters, so that the cost is saved by 52%.

Example 2

As shown in fig. 2, a circular region reinforcement method is adopted, in which the circular region reinforcement area has a diameter D of 0.4L of 2m, the grouting reinforcement depth is 0.4H of 2.8m, and the distance between the reinforcement regions is 0.5 m.

Cost saving description: if a mode of completely grouting and reinforcing the lower area of the tunnel is adopted, the reinforcing depth is generally 0.2H to 1.4 m, the reinforcing length of 10m is the volume of 70 cubic meters, and if the method of embodiment 2 of the invention is adopted, only 35.19 cubic meters are required to be reinforced, so that the cost is saved by 49.7%.

Example 3

The reinforcing method of the rectangular grouting area is adopted, the area size of the rectangular area is that the length is multiplied by the width is 0.6L multiplied by 0.3L is multiplied by 3m multiplied by 1.8m, the elastic modulus of the soil body below the tunnel is assumed to be 7Mpa at the moment, the bearing capacity of the soil body below the tunnel is weak, therefore, the grouting reinforcement depth is increased to be 0.4H which is multiplied by 2.8m, the distance d is multiplied by 0m, and the dislocation reinforcement area is continuous in the length direction.

Cost saving description: if a mode of grouting reinforcement of the whole area below the tunnel is adopted, the reinforcement depth is generally 0.2H to 1.4 m, and the reinforcement length of 9m is 63 cubic meters, that is, the reinforcement is needed, for example, the method of the embodiment 3 of the invention only needs 45.36 cubic meters, and the cost is saved by 28%.

According to the technical scheme for grouting and reinforcing the foundation pit bottom soil body, the following construction method can be preferably adopted: and (4) adopting a sleeve valve pipe grouting construction scheme to perform grouting reinforcement on the soil body at the bottom of the tunnel by staggering the regions. The method comprises the following steps: leveling a field, lofting hole positions, positioning by a drilling machine, drilling holes, installing sleeve valve pipes, sealing the holes and grouting.

Wherein, the grouting reinforcement time is started when the excavation of the foundation pit is completed. The construction site is leveled, namely sundries, garbage and the like in the grouting reinforcement range are cleaned up, irrelevant materials, machines and the like are taken out of the construction site, and leveling and compacting are carried out, so that the condition of stable construction of the geological drilling rig is achieved. And hole position lofting, namely lofting according to a design drawing, wherein the transverse and longitudinal spacing of the grouting holes is 1 m. After the drill is positioned, namely the hole position is determined, the drill enters the field and is in place, the bottom of the drill needs to be flat and stable, the drill hole is positioned according to a drawing in principle, and the deviation of the hole position is not more than 0.05 m. And (3) checking whether the drilling angle of a drill rod of the drilling machine meets the design requirement before drilling, namely before drilling, leveling and correcting the drilling machine when drilling for 2m and after each drill rod is added, wherein the deviation between the inclination of the drilling hole and the design inclination is required to be less than or equal to 1.5%. The sleeve valve pipe is installed, namely, the sleeve valve pipe is drilled to the designed depth and then is immediately assembled to the designed hole depth, a lower blank cap is added to the bottom of a connected grouting pipe, the grouting pipe is put into a hole, water is filled into the grouting pipe so as to prevent the grouting pipe from floating upwards, the grouting pipe is ensured to be put into the hole bottom, the upper surface of the grouting pipe is higher than the bottom of a foundation pit, and a sealing cover is sealed at the top of the grouting pipe so as to prevent sundries from entering the pipe. The hole sealing is that casing materials are adopted to fill below 1m underground, the strength of the casing materials must be moderate, slurry is prevented from flowing up and down in a hole, and the casing materials can be split by grouting pressure. The casing material generally adopts cement: bentonite: water 1: 1.5: 1.9, prepare and form, pipe through circulation mud is connected to extrusion formula slip casting machine on, the shell material is under the effect of pressure, through drilling rod drilling bottom, along with the entering of shell material, mud is come out from the replacement of drill way, and the mud ditch through the drill way mouth of mud circulation pond is arranged to the mud of coming out of replacement. When the discharged slurry is found to contain the jacketing material, the replacement is stopped. And grouting construction is carried out when the casing material has certain strength (the time is not less than three days).

By adopting the reinforcement method of the technical scheme, the shape, the size and the interval of the reinforcement area can be adjusted according to different conditions of the soil body, when the strength of the soil body is higher, the size of the reinforcement area can be reduced, and the interval is increased; and when the soil body intensity is less, can increase the size in reinforcement area, the interval reduces. The mechanical property test and post-construction settlement monitoring of the reinforced soil body show that the reinforcement method adopting the technical scheme saves cost and obtains a better settlement prevention effect.

It is to be understood that the present invention has been described with reference to certain embodiments, and that various changes in the features and embodiments, or equivalent substitutions may be made therein by those skilled in the art without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. The utility model provides a tunnel foundation pit bottom dislocation hidden pier reinforcerment system, reinforcerment system consolidates the region including the slip casting that is arranged in the soil body of tunnel below, its characterized in that: the grouting reinforcement areas are distributed in the soil body below the tunnel in a staggered mode on two sides in the width direction of the tunnel, one side of each grouting reinforcement area is tangent to one side boundary of the tunnel, and a distance larger than zero is reserved between the other side of each grouting reinforcement area in the width direction of the tunnel and the other side boundary of the tunnel.

2. The system for reinforcing the hidden pier staggered at the bottom of the tunnel foundation pit according to claim 1, wherein the interval between two adjacent grouting reinforcement areas along the length direction of the tunnel is d, and the value range of d is as follows: -0.3L < d <0.3L, where L is the width of the tunnel.

3. The system for reinforcing a staggered dark pier at the bottom of a tunnel foundation pit according to claim 1, wherein the depth of the grouting reinforcement area is between 0.2H and 0.6H, wherein H is the excavation depth of the foundation pit.

4. The system for reinforcing a staggered pier at the bottom of a tunnel foundation pit according to any one of claims 1 to 3, wherein the cross section of the grouting reinforcement area in the horizontal direction is circular, the diameter of the circle is between 0.3L and 0.6L, wherein L is the width of the tunnel.

5. The system for reinforcing the staggered hard pier at the bottom of the tunnel foundation pit according to any one of claims 1 to 3, wherein the section of the grouting reinforcement area in the horizontal direction is a rectangle, the side length of the rectangle is between 0.3L and 0.6L, and L is the width of the tunnel.

6. A tunnel foundation pit bottom dislocation hidden pier reinforcing method comprises the following steps: opening holes in a soil body below the tunnel to form a grouting reinforcement area, and grouting the reinforcement area to form a hidden pier; the method is characterized in that: the grouting reinforcement areas are distributed in the soil body below the tunnel in a staggered mode on two sides in the width direction of the tunnel, one side of each grouting reinforcement area is tangent to one side boundary of the tunnel, and a distance larger than zero is reserved between the other side of each grouting reinforcement area in the width direction of the tunnel and the other side boundary of the tunnel.

7. The method for reinforcing the hidden pier staggered at the bottom of the tunnel foundation pit according to claim 6, wherein the interval between two adjacent grouting reinforcement areas along the length direction of the tunnel is d, and the value range of d is as follows: -0.3L < d <0.3L, where L is the width of the tunnel.

8. The system for reinforcing a staggered dark pier at the bottom of a tunnel foundation pit according to claim 6, wherein the depth of the grouting reinforcement area is between 0.2H and 0.6H, wherein H is the excavation depth of the foundation pit.

9. The system for reinforcing a staggered pier of a tunnel foundation pit bottom according to any one of claims 6 to 8, wherein the grouting reinforcement area has a circular cross section in the horizontal direction, the diameter of the circle is between 0.3L and 0.6L, wherein L is the width of the tunnel.

10. The system for reinforcing the staggered hard pier at the bottom of the tunnel foundation pit according to any one of claims 6 to 8, wherein the section of the grouting reinforcement area in the horizontal direction is a rectangle, the side length of the rectangle is between 0.3L and 0.6L, and L is the width of the tunnel.