CN210530860U

CN210530860U - Deep-buried blocking barrier for controlling deformation of tunnel outside foundation pit

Info

Publication number: CN210530860U
Application number: CN201920566032.6U
Authority: CN
Inventors: 杜一鸣; 郑刚; 刁钰; 张立明
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2019-04-23
Filing date: 2019-04-23
Publication date: 2020-05-15
Anticipated expiration: 2029-04-23

Abstract

The utility model discloses a deep-buried blocking barrier for controlling the deformation of a tunnel outside a foundation pit, wherein a main body of the blocking barrier is a bored pile, a pile top is positioned in a deep soil body, a pile long reinforcement cage with effective length is arranged in a drilled hole, concrete is poured to the designed elevation of the pile top, and fine sand is backfilled in the drilled hole above a pile body; the distance D between the deep-buried blocking barrier and the existing tunnel outside the pit is 0.2-0.4D, and D is the net distance between the tunnel and the foundation pit enclosure structure; the buried depth L of the bottom of the deep-buried blocking barrier is 2.0-2.4H, and H is the excavation depth of the foundation pit; the buried depth H of the top of the deep buried blocking barrier is 0.6-1.6H and H is less than 1.2S, and S is the buried depth of the center of the tunnel. The utility model discloses a change the effective stake of traditional separation campshed long, set up protective screen top position among the deep soil body, can effectively increase and block that the protective screen reduces "traction action" when "blocking the effect" of the soil body of initiative district, the deformation of the soil body of active control initiative district, and then the increase blocks the deformation control effect of protective screen to the outer existing tunnel of hole.

Description

Deep-buried blocking barrier for controlling deformation of tunnel outside foundation pit

Technical Field

The utility model belongs to the technical field of foundation and foundation engineering construction, concretely relates to set up the controlling means who is used for controlling the tunnel and arouses the deformation because of the foundation ditch excavation between foundation ditch and neighbouring existing tunnel.

Background

With the construction and operation of a large number of urban subways, when a foundation pit is constructed adjacent to an operated subway tunnel, the deformation influence control of the foundation pit on the existing tunnel becomes an unavoidable difficult problem. The unloading effect of foundation pit excavation can produce strong influence to the surrounding environment, and the existing tunnel of pit outside can produce the deformation removal to the pit in along with the outer initiative district soil body of pit under the unloading effect of the soil body in the pit, if the design of foundation pit engineering and construction are improper, will cause adjacent tunnel to produce serious deformation, threatens structure safety.

Urban subway tunnels tend to be highly sensitive to deformation, which makes mm-scale deformation control necessary. The traditional method depends on passive methods of increasing the thickness, depth, support quantity and the like of the diaphragm wall, and the methods are usually high in cost and limited in deformation control effect. Blocking barriers mainly based on row piles are often arranged between a foundation pit and an adjacent building, and become a measure for effectively controlling the deformation of the adjacent structure outside the pit. In recent years, such blocking barriers have also been used to be placed between the foundation pit enclosure and the existing tunnel in an attempt to reduce the deformation and internal forces caused by the foundation pit to the existing tunnel. However, the applicant researches show that although the blocking barrier can significantly reduce the settlement of the ground outside the pit and the settlement of the foundation shallow-buried building caused by excavation, the blocking barrier may cause additional settlement and horizontal displacement of the soil body of the deep layer outside the pit and the existing tunnel with larger buried depth, and rather play a bad role.

SUMMERY OF THE UTILITY MODEL

In order to solve the problem that exists among the prior art, the utility model provides a control outer tunnel of foundation ditch buries deeply and blocks the protective screen, solves among the prior art problem that traditional separation campshed can not the effective control hole outer existing tunnel warp.

The utility model discloses take following technical scheme to realize:

a deep-buried blocking barrier for controlling the deformation of a tunnel outside a foundation pit is characterized in that a main body of the blocking barrier is a bored pile, a pile top is positioned in a deep soil body, a long reinforcement cage with an effective length is arranged in a drilled hole, concrete is poured to a designed elevation of the pile top, and fine sand is backfilled in the drilled hole above a pile body; the distance D between the deep-buried blocking barrier and the existing tunnel outside the pit is 0.2-0.4D, and D is the net distance between the tunnel and the foundation pit enclosure structure; the depth L of the bottom of the deep-buried blocking barrier is 2.0-2.4H, and H is the excavation depth of the foundation pit; the buried depth H of the top of the deep buried blocking barrier is 0.6-1.6H and H is less than 1.2S, and S is the buried depth of the center of the tunnel.

And backfilling the fine sand part layer by layer, wherein the indexing thickness is 1.5-2 m, and the backfilling and compacting coefficient of each layer is not less than 0.90.

The blocking barrier is horizontally arranged and not smaller than five groups of row piles, and the total length of the blocking barrier is determined according to the length of the protected tunnel interval and the size of the foundation pit.

And the horizontal spacing of the row piles takes 2-3 m.

Compared with the prior art, the beneficial effects of the utility model reside in that:

1. through changing the effective pile length of traditional separation campshed, set up barrier top position among the deep soil body, can effectively increase and block that the barrier reduces "traction effect" when "blocking the effect" of active area soil body, the deformation of active area soil body of effective control, and then the increase blocks the deformation control effect of barrier to the existing tunnel outside the hole.

2. The traditional barrier system design is usually based on engineering experience, and fine design cannot be carried out according to the optimization principle of the control effect. Based on research results of the applicant, the invention can provide optimized design parameters of the isolation row piles according to engineering characteristics such as excavation depth H of the foundation pit, clear distance D between the tunnel and the enclosure structure, buried depth S of the center of the tunnel and the like, and maximize the deformation control effect of the isolation row piles.

3. The deep-buried blocking barrier is used for arranging the top of the row piles in the deep soil body and taking the cast-in-situ bored piles as a main body. In the construction process, the pile body is poured in the drilled hole to the set elevation, and then the effective pile length is formed. And then, fine sand is adopted to backfill the drill hole from the part above the pile top to the ground surface to be compact. This kind of design reduces the effective length of blocking the protective screen by a wide margin, compares in traditional separation campshed, can effectively reduce engineering cost.

Drawings

FIG. 1 is a cross-sectional view of a deep buried blocking barrier;

FIG. 2 is a plan view of a deep buried blocking barrier;

reference numbers and corresponding part names in the drawings:

1-blocking a barrier, 2-backfilling fine sand on the upper part of a pile body, 3-existing tunnels outside pits, 4-foundation pit enclosing structures, 5-soil bodies in active areas outside pits, and 6-digging soil bodies in pits.

Detailed Description

The deep-buried blocking barrier for controlling the deformation of the tunnel outside the foundation pit and the construction method thereof will be further described with reference to the accompanying drawings and specific embodiments. The following examples are given for the purpose of illustration only and are not intended to be limiting.

Research shows that the traditional blocking row piles have a blocking effect on the shallow soil body of the active area and can effectively control the horizontal displacement of the shallow soil body of the active area; meanwhile, the device has a traction effect on deep soil in the active area, and can increase the horizontal displacement of the deep soil, so that the deformation control is unfavorable. The utility model provides a bury deeply and block protective screen reduces "traction effect" when can maximize "blocking effect", effectively improves its deformation control effect, shortens simultaneously and blocks the effective length of protective screen, reduces engineering cost.

The invention relates to a deep-buried blocking barrier for controlling the deformation of a tunnel outside a foundation pit. Compare in traditional separation campshed, the utility model discloses the top position sets up in the outer deep soil body of hole, can effectively reduce engineering cost when effectively increasing its deformation control effect. The main design parameters of the deep-buried blocking barrier are top buried depth H, bottom position depth L and clear distance D from the existing tunnel outside the pit, and based on research results developed by an applicant, the design parameters of the deep-buried blocking barrier are determined according to foundation pit excavation depth H, clear distance D between the tunnel and a foundation pit support structure and tunnel center buried depth S. Based on the existing research results, the design parameters of the blocking barrier are determined in turn. Firstly, determining a blocking barrier position parameter D according to the clear distance D between the tunnel and the foundation pit support structure, wherein when D is 0.2-0.4D, the isolation effect of the deep-buried blocking barrier is obvious; secondly, determining the depth L of the bottom position, and when the depth L is 2.0-2.4H, the deformation control effect of the deep-buried blocking barrier is optimal; and finally, determining the top embedding depth H, and maximizing the deformation control effect of the deep embedding blocking barrier when H is 0.6-1.6H and H is less than 1.2S. Meanwhile, the horizontal distance of the row piles in the barrier is 2-3 m, the deformation control effect and the engineering economy can be considered, and meanwhile, the blocking barrier construction disturbance is reduced.

The utility model discloses select the drilling bored concrete pile as blocking the protective screen main part, be convenient for bury the construction deeply. As shown in fig. 1, the pile top is located in the deep soil. In the implementation, an effective length pile long reinforcement cage is put into a drill hole, and then concrete is poured to the designed elevation of the pile top, so that the construction of the pile body is completed. And in the drill holes above the pile body, fine sand is adopted for backfill and compaction in a layered mode, the layered thickness is 1.5-2 m, and the compaction coefficient of each layer is not smaller than 0.90. The construction cost of the sandy soil engineering of the backfilling part is low, and compared with the traditional blocking pile arrangement, the construction cost can be greatly reduced.

Examples

As shown in fig. 1 and 2, the utility model relates to a control outer tunnel of foundation ditch and bury deeply and block protective screen. Firstly, before digging a soil body 6 in a pit, a foundation pit enclosure structure 4 is constructed. And after the construction of the foundation pit support structure 4 is finished, constructing a blocking barrier 1 between the foundation pit support structure 4 and the existing tunnel 3 outside the pit. The construction design parameters of the blocking barrier 1 are determined based on the combination of research results and field conditions, the net distance D between the blocking barrier and the existing tunnel outside the pit is 0.2-0.4D, the bottom position depth L is 2.0-2.4H, the top embedding depth H is 0.6-1.6H, and H is less than 1.2S (wherein D is the net distance between the tunnel and a foundation pit support structure, H is the excavation depth of the foundation pit, and S is the center embedding depth of the existing tunnel). And (3) taking the cast-in-situ bored pile as the blocking barrier main body, drilling the pile-forming equipment to enter the field, and constructing the blocking barrier 1. And vertically drilling holes on the earth surface of the active area outside the pit, and simultaneously preventing the soil body 5 of the active area outside the pit from collapsing by adopting a mud retaining wall technology. And (4) hoisting the steel reinforcement cage downwards, wherein the top position of the steel reinforcement cage is 5-10 cm higher than the elevation position of the pile top, and then pouring concrete in layers to the elevation position of the pile top. And backfilling the drilled hole above the pile top to the ground surface by adopting dense fine sand 2, and then performing layered compaction treatment, wherein the layered thickness is 1.5-2 m, and the compaction coefficient of each layer is not less than 0.90. Then, the blocking barriers 1 are constructed in sequence in the horizontal direction in a hole jumping manner, see fig. 2. And after the structural strength of the row piles reaches a design value, completing construction of the deep-buried blocking barrier system, and performing foundation pit excavation and excavation of earthwork 6 in the pit.

It should be emphasized that the embodiments described herein are illustrative and not restrictive, and thus the present invention is not limited to the embodiments described in the detailed description, but also falls within the scope of the present invention, in any other embodiments derived by those skilled in the art according to the technical solutions of the present invention.

Claims

1. A deep-buried blocking barrier for controlling the deformation of a tunnel outside a foundation pit is characterized in that a main body of the blocking barrier is a reinforced concrete bored pile combined sand pile, the pile top of the reinforced concrete pile is positioned in a deep soil body, an effective-length pile long reinforcement cage is arranged in a drilled hole, concrete is poured until the designed elevation of the pile top is reached, and fine sand is backfilled in the part of the drilled hole above a pile body to form a sand pile; the distance D between the deep-buried blocking barrier and the existing tunnel outside the pit is 0.2-0.4D, and D is the net distance between the tunnel and the foundation pit enclosure structure; the depth L of the bottom of the deep-buried blocking barrier is 2.0-2.4H, and H is the excavation depth of the foundation pit; the buried depth H of the top of the deep buried blocking barrier is 0.6-1.6H and H is less than 1.2S, and S is the buried depth of the center of the tunnel.

2. The deep-buried blocking barrier for controlling the deformation of the tunnel outside the foundation pit according to claim 1, wherein the blocking barrier is formed by not less than five groups of piles which are horizontally arranged, and the total length of the blocking barrier is determined according to the length of the protected tunnel section and the size of the foundation pit.

3. The deep-buried blocking barrier for controlling the deformation of the tunnel outside the foundation pit according to claim 1, wherein fine sand is used for backfill and compaction in a layered mode, the thickness of backfill in a layered mode is 1.5-2 m, and the backfill and compaction coefficient is not less than 0.90.

4. The deep-buried blocking barrier for controlling the deformation of a tunnel outside a foundation pit according to claim 2, wherein the horizontal distance between row piles in the blocking barrier is 2-3 m.