Combined reinforcing structure for tunnel crossing pile-slab retaining wall

Abstract

The invention relates to the field of tunnel excavation, and discloses a combined reinforcing structure of a tunnel crossing pile plate retaining wall, which comprises a tunnel and an existing pile, the built-in section of the existing pile is provided with a breaking area, and the tunnel passes through the breaking area; the tunnel comprises a first expanding excavation area, the first expanding excavation area conducts expanding excavation in the circumferential direction, a cover arch is arranged in the first expanding excavation area, a plurality of anchor rods are arranged on the side, close to the existing piles, of the cover arch in the circumferential direction, extension lines penetrate through the ends of the anchor rods of the existing piles to be inserted into the existing piles to form a supporting area, and the supporting area is located above the breaking area. The structural integrity of the pile body is maintained, and the novel reinforcing technology system can adapt to narrow operation space.

Description

Technical Field

[0001] The present invention relates to the field of tunnel excavation, and particularly to a combined reinforcement structure for a tunnel passing through a pile - plate retaining wall. Background Art

[0002] Under the background of underground space development, tunnel crossing projects face technical challenges of complex structural conflicts. In a typical working condition where the urban underground traffic network intersects with the existing support system, when the axis of the newly built tunnel forms a three - dimensional spatial interference with the embedded section of the anti - slide pile of the pile - plate retaining wall (for example, a support system including embedded - section piles on the side of an existing building, and the support system includes rows of existing piles), traditional engineering treatment methods face severe structural safety tests. In the conventional disposal plan where the embedded section of the existing pile is directly demolished, the mechanical equilibrium state of the pile - soil system will change irreversibly: the loss of the supporting effect in the passive area of the pile will lead to the degradation of the anti - slide support function, and may further induce major engineering disasters such as slope sliding.

[0003] In the prestressed anchor cable reinforcement system adopted in current engineering practice, its technical principle is to compensate for structural stability by strengthening the pile - top constraint. However, in specific engineering scenarios, such as when there are high - density buildings or important underground facilities distributed in front of the anti - slide pile, this technical solution exposes significant application limitations: ① The surface operation area is restricted by factors such as the foundation of existing buildings and the distribution of underground pipe networks, and cannot meet the spatial requirements for anchor cable construction; ② The protection requirements of important infrastructure conflict with the vibration impact of the anchoring process. These spatial constraint conditions make the conventional reinforcement plan lose its feasibility in a three - dimensionally restricted environment, objectively requiring the development of a new reinforcement method for underground restricted spaces.

[0004] Currently, in the field of engineering technology, there is no systematic solution for the reinforcement of anti - slide piles under the restriction of underground space. This technical vacuum seriously restricts the safe implementation of tunnel crossing projects under complex geological conditions. Therefore, a new reinforcement technology system that can not only maintain the structural integrity of the pile body but also adapt to narrow working spaces is needed to break through the application bottleneck of existing engineering technologies. Summary of the Invention

[0005] The present invention aims to provide a combined reinforcement structure for a tunnel passing through a pile - plate retaining wall, which is a new reinforcement technology system that can not only maintain the structural integrity of the pile body but also adapt to narrow working spaces.

[0006] To achieve the above object, the present invention adopts the following technical solution: A combined reinforcement structure for a tunnel passing through a pile-slab retaining wall, comprising a tunnel and existing piles. A breaking area is provided on the embedded section of the existing piles, and the tunnel passes through the breaking area; the tunnel includes a first excavation area, which is excavated circumferentially. An arch ring is provided in the first excavation area. A number of anchor rods are circumferentially provided on the side of the arch ring close to the existing piles. The end of the anchor rod whose extension line passes through the existing pile is inserted into the existing pile to form a support area, and the support area is located above the breaking area.

[0007] The beneficial effects of this solution are as follows:

[0008] 1. Limited by the surrounding space and to reduce the construction influence range, and to eliminate the process of excavating the soil in front of the piles, the inventor considered various solutions:

[0009] If ground construction is completely adopted, first excavate several anti-slide piles on the ground, and then construct a capping beam on the tops of the several anti-slide piles to form a portal support structure. Finally, construct anchor rods on the capping beam above the tunnel. By setting the anchor rods obliquely downward, the capping beam and the existing piles are connected. However, the distance between the anti-slide piles and the existing piles should not exceed five times the pile diameter of the anti-slide piles, otherwise the distance is too large to form a cooperative force; but for existing buildings with deep foundations, the anchor rods need to have a large inclination angle to connect with the embedded section of the existing piles, and the anchor rods with a large inclination angle cannot provide enough horizontal force for the existing piles, thus unable to ensure the reliability after the existing piles are broken.

[0010] In this solution, neither ground construction nor excavation of the soil in front of the piles is adopted. Instead, during the tunnel excavation process, an arch ring and horizontal anchor rods are constructed to connect with the existing piles, thus ensuring the reliability of the existing piles, while reducing the disturbance to the surrounding soil, maintaining the integrity of the pile structure and adapting to the narrow working space of the new reinforcement technology system.

[0011] 2. By connecting the anchor rods with the existing piles, the main stress position of the existing piles is transferred from the embedded section to the support of the tunnel, and the stress on the tunnel is dispersed longitudinally along the tunnel through the anchor rods.

[0012] Furthermore, anti-slide piles are respectively provided on both sides of the tunnel. The anti-slide piles are arranged in rows and are parallel to the rows of existing piles. A capping beam is provided on the top of the anti-slide piles, and the capping beam is connected to the tops of the anti-slide piles on both sides of the tunnel at the same time.

[0013] Furthermore, the horizontal distance between the anti-slide piles and the existing piles is 1 to 5 times the pile diameter or cross-sectional height of the anti-slide piles.

[0014] Furthermore, a tie beam is provided between the newly added capping beam and the capping beam on the top of the existing piles.

[0015] Furthermore, if the width of the tunnel is less than 5 meters, one anti-slide pile is respectively provided on both sides of the tunnel; if the width of the tunnel is greater than 5 meters, two anti-slide piles are respectively provided on both sides of the tunnel.

[0016] Furthermore, the anchor bolts are horizontally arranged. The tunnel further includes a second excavation area. After the second excavation area is excavated upward, it is excavated toward both sides of the top to the anti-slide piles on both sides of the tunnel. A connecting cross beam is provided in the second excavation area, and both ends of the connecting cross beam are respectively connected to two anti-slide piles.

[0017] Furthermore, the tunnel further includes a third excavation area. The third excavation area is excavated upward to the anchor bolts. Both the support area and the demolition area are within the range of the third excavation area or pass through the support arch. A support arch is provided in the support area, and the end of the anchor bolt is arranged in the support arch. The support arch is connected to the existing piles in the support area.

[0018] Furthermore, the connecting cross beam is of reinforced concrete structure, and the steel bars at both ends of the connecting cross beam are implanted into the anti-slide piles.

[0019] Furthermore, the anchor bolts at the vault pass through the connecting cross beam.

[0020] Furthermore, the anchor bolts are arranged obliquely upward. The anchor bolts are hollow grouting anchor bolts. The grouting holes of the hollow grouting anchor bolts are arranged at the upper end of the hollow grouting anchor bolts, and the lower end of the hollow grouting anchor bolts is used for connection with the later support of the tunnel.

[0021] The present solution also has the following effects:

[0022] 1. For the ground structure, the distance between the anti-slide piles and the existing piles needs to be as close as possible. The horizontal distance D between the anti-slide piles and the existing piles should be 1 to 5 times the pile diameter or cross-sectional height of the anti-slide piles, so as to form a cooperative stress system, connect the embedded section of the existing piles and the newly added anti-slide piles into a whole, and jointly resist the soil pressure behind the piles or the lateral pressure of the rock.

[0023] For the underground structure, the anchor bolts are driven into the tunnel from the collar beam in the first excavation area, passing through the connecting cross beam and the support arch in sequence. The connecting cross beam connects the anti-slide piles at both ends, and the support arch connects the existing piles above. Thus, the existing piles, anti-slide piles and the support structure of the tunnel (the primary support and the secondary lining of the tunnel) are connected into a whole through the anchor bolts, thereby compensating for the adverse impact on stability after the demolition area of the existing piles is demolished. Specifically: Generally, the excavation of the tunnel has a greater disturbance to the surrounding rock mass, and usually there will be problems such as over-excavation and roof collapse of the vault. When the tunnel is excavated to the third excavation area, the distance between the anchor bolts and the tunnel excavation contour is uneven, and the surrounding rock below the anchor bolts is difficult to effectively support the anchor bolts. It is better to directly demolish the surrounding rock below the anchor bolts and re-pour the support arch, connect the anchor bolts with the primary support and the secondary lining constructed later in the tunnel. The concentrated load transmitted from the edge of the demolition area of the existing piles is transmitted along the longitudinal direction of the tunnel to the primary support and the secondary lining of the tunnel through the anchor bolts, thereby dispersing the stress and improving the stability of the overall structure.

[0024] 2. Generally, after the anchoring section of the existing piles is removed for tunnel construction, the existing piles will overturn and cause the overall structure to deform and fail. In this scheme, the passive earth pressure is maintained for the existing piles by anchor rods, and the cap beam distributes the tension of the pull rod to the surrounding anti-slip piles, thereby increasing the stability and anti-overturning ability of the overall structure.

[0025] 3. The deformation and cracking of the tie beam can serve as an early warning that the existing piles are beginning to overturn, so that personnel on the ground can immediately detect the overturning of the existing piles and take timely remedial measures.

[0026] 4. In the prior art, when constructing anchor rods on the pile-sheet retaining wall, the anchor rods are usually constructed on the side of the pile-sheet retaining wall close to the foundation pit and inclined downward to provide tension for the pile-sheet retaining wall; however, since the pile-sheet retaining wall in this solution is an existing structure and the existing buildings in the corresponding foundation pit have been built, there is not enough space to construct anchor rods. Therefore, the opposite is done and the anchor rods are constructed obliquely upward from the tunnel below. The upper end of the anchor rod is inserted into the pile-sheet retaining wall and the connection strength is enhanced by grouting; the lower end of the anchor rod is connected to the later support of the tunnel to provide a reaction force for the anchor rod.

[0027] That is, the soil pressure acts on the existing piles, and the force is transmitted to the rock in the expanded area through the newly added anchor rod. The anchor rod is anchored on the rock wall of the tunnel. The conventional practice of driving anchor rods from the pile-sheet retaining wall is changed. The anchor rod is driven in reverse from the tunnel, which can solve the problem of not being able to drive anchor cables for reinforcement.

[0028] 5. When driving anchor rods on the sleeve arch, the anchor rods may be deviated. If the anchor rods leak out when excavating to the broken area, a support arch can be used to remedy the situation and strengthen the supporting effect of the anchor rods. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the final plan view of Example 1;

[0030] Figure 2 is a final cross-sectional schematic diagram of Example 1;

[0031] Figure 3 It is a schematic plan view of the initial state of Example 1;

[0032] Figure 4 It is a plan view of construction step 1 of Example 1;

[0033] Figure 5 It is a plan view of the second construction step of Example 1;

[0034] Figure 6 It is a plan view of construction step 3 of Example 1;

[0035] Figure 7 is a schematic cross-sectional view of the initial state of Example 1;

[0036] Figure 8 Schematic cross-section diagram of Step 1 of the construction in Example 1;

[0037] Figure 9 Schematic cross-section diagram of Step 2 of the construction in Example 1;

[0038] Figure 10 Schematic cross-section diagram of Step 3 of the construction in Example 1;

[0039] Figure 11 Schematic final cross-section diagram of Example 2;

[0040] Figure 12 Schematic final cross-section diagram of Example 3. Specific implementation manners

[0041] The following is a further detailed description through specific implementation manners:

[0042] The reference signs in the attached drawings of the specification include: existing building 1, existing pile 2, embedded section L1, free section L2, demolition area 21, support area 22, existing capping beam 23, anti-slide pile 31, cap beam 32, anchor bolt 33, tie beam 35, tunnel 4, first excavation area 41, second excavation area 42, connecting cross beam 43, support arch 44, support structure 45, third excavation area 46, socket arch 47.

[0043] Example 1

[0044] Example 1 is basically as Figures 1 - 10 shown: A combined reinforcement structure for a tunnel to pass through a pile-slab retaining wall, and the applicable objects are: existing building 1 and newly built tunnel 4. As Figure 1 shown, there is a row of existing piles 2 on the left side of the existing building 1. As Figure 10 shown, the existing pile 2 includes a free section L2 and an embedded section L1. As Figure 2 shown, according to the design requirements, the newly built tunnel 4 needs to pass through the embedded section L1 of the existing pile 2;

[0045] A combined reinforcement structure for a tunnel to pass through a pile-slab retaining wall includes an existing pile 2. As Figure 10 shown, a demolition area 21 is provided on the embedded section L1 of the existing pile 2. As Figure 2 shown, the tunnel 4 passes through the demolition area 21. As Figure 1As shown in the figure, anti-slide piles 31 are respectively arranged on both sides of the newly-built tunnel 4. The anti-slide piles 31 are arranged in rows and are parallel to the row of existing piles 2. The horizontal distance between the anti-slide piles 31 and the existing piles 2 is 1 to 5 times the pile diameter or cross-sectional height of the anti-slide piles 31. If the width of the tunnel 4 is less than 5 meters, one anti-slide pile 31 is respectively arranged on both sides of the tunnel 4. If the width of the tunnel 4 is greater than 5 meters, two anti-slide piles 31 are respectively arranged on both sides of the tunnel 4. In this embodiment 1, two anti-slide piles 31 are respectively arranged on both sides of the tunnel 4.

[0046] A capping beam is arranged above the tunnel 4. The capping beam is cast and connected to the tops of the four anti-slide piles 31. An existing capping beam 23 is also arranged on the top of the existing pile 2. For the convenience of display, Figures 3 - 1 the existing capping beam 23 is omitted in the figure. There are four tie beams 35 between the existing capping beam 23 and the capping beam. The tie beams 35 correspond one by one to the anti-slide piles 31 on both sides of the tunnel 4 and the existing piles 2.

[0047] As Figure 2 shown in the figure, the tunnel 4 includes a first excavation area 41. The first excavation area 41 is excavated circumferentially. An arch ring 47 is arranged in the first excavation area 41. A number of anchor rods 33 are horizontally arranged circumferentially on the side of the arch ring 47 close to the existing pile 2. The end of the anchor rod 33 whose extension line passes through the existing pile 2 is inserted into the existing pile 2 to form a support area 22. As Figure 10 shown in the figure, the support area 22 is located above the demolition area 21. Figure 2 And Figure 10 the range of the first excavation area 41 in the figure is only for illustration. During the actual construction process, the operation space for drilling and installing the anchor rods 33 should also be reserved.

[0048] A construction method for a combined reinforcement structure of a tunnel passing through a pile-slab retaining wall is as follows:

[0049] The initial state is as Figure 3 and Figure 7 shown in the figure;

[0050] Step 1: As Figure 4 and Figure 8 shown in the figure, construct the anti-slide piles 31 on both sides of the tunnel 4.

[0051] Step 2: As Figure 5 and Figure 9 shown in the figure, construct the capping beam of the newly added anti-slide piles 31, and at the same time construct the connecting beam 35 to pour the existing piles 2 and the anti-slide piles 31 together.

[0052] Step 3: As Figure 6 and Figure 10As shown, the tunnel 4 is excavated to the first enlarged excavation area 41. A sleeve arch 47 is constructed on one side of the existing pile 2 in the first enlarged excavation area 41. Horizontal holes are drilled circumferentially on the sleeve arch 47 and anchor rods 33 are inserted. Thus, the end of the anchor rod 33 whose extension line passes through the existing pile 2 is inserted into the existing pile 2 to form a support area 22, and the drill holes are sealed by grouting.

[0053] Step 4: As Figure 1 and Figure 2 shown, during the construction of the excavation of the tunnel 4, when the excavation reaches the position of the existing pile 2, the demolition area 21 of the existing pile 2 is demolished, and the primary support and the secondary lining of the tunnel 4 and other supporting structures 45 of the tunnel 4 are constructed according to the design and specifications.

[0054] Example 2

[0055] On the basis of Example 1, Example 2: As Figure 11 shown, the tunnel 4 further includes a second enlarged excavation area 42 and a third enlarged excavation area 46. The first enlarged excavation area 41, the second enlarged excavation area 42 and the third enlarged excavation area 46 are arranged in sequence from left to right. After the second enlarged excavation area 42 is enlarged upwards, it is enlarged to both sides of the top to the anti-slide piles 31 on both sides of the tunnel 4.

[0056] A connecting cross beam 43 is provided in the second enlarged excavation area 42. The anchor rod 33 passes through the connecting cross beam 43. The connecting cross beam 43 is a reinforced concrete structure. The steel bars at both ends of the connecting cross beam 43 are respectively implanted into the anti-slide piles 31, so as to ensure that both ends of the connecting cross beam 43 are connected to the two anti-slide piles 31 respectively.

[0057] The third enlarged excavation area 46 is enlarged upwards to the anchor rod 33. Both the support area 22 and the demolition area 21 are within the range of the third enlarged excavation area 46. A support arch 44 is provided in the support area 22. The right end of the anchor rod 33 passes through the support arch 44, and the support arch 44 is connected to the existing pile 2 in the support area 22.

[0058] Example 3

[0059] The difference between Example 3 and Example 1 is that: As Figure 12 shown, the anchor rod 33 is arranged obliquely upwards. The anchor rod 33 is a hollow grouting anchor rod. The grouting holes of the hollow grouting anchor rod are arranged at the upper end of the hollow grouting anchor rod, that is, in the support area 22 formed by inserting the hollow grouting anchor rod into the existing pile 2. The lower end of the hollow grouting anchor rod is used to connect with the later support of the tunnel 4.

[0060] The above are only embodiments of the present invention, and common general technical solutions and / or characteristics in the solutions are not described in detail herein. It should be noted that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicability of the patent. The protection scope claimed in this application shall be subject to the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. A combined reinforcement structure for a tunnel passing through a pile-sheet retaining wall, characterized in that: The invention comprises a tunnel and existing piles, wherein a breaking area is arranged on the embedded section of the existing piles, and the tunnel passes through the breaking area; the tunnel comprises a first expansion area, which is circumferentially excavated, and a sleeve arch is arranged in the first expansion area, and a plurality of anchor rods are circumferentially arranged on a side of the sleeve arch close to the existing piles, and an extension line passes through the anchor rod end of the existing pile and is inserted into the existing pile to form a supporting area, and the supporting area is located above the breaking area.

2. A combined reinforcement structure for a tunnel crossing pile-sheet retaining wall according to claim 1, characterized in that: Anti-slip piles are provided on both sides of the tunnel. The anti-slip piles are arranged in rows and parallel to the existing rows of piles. Crown beams are provided on the tops of the anti-slip piles, and the crown beams are connected to the tops of the anti-slip piles on both sides of the tunnel at the same time.

3. The combined reinforcement structure of a tunnel through pile-sheet retaining wall according to claim 1, characterized in that: The horizontal distance between the anti-slide pile and the existing pile is 1 to 5 times the diameter or cross-sectional height of the anti-slide pile.

4. The combined reinforcement structure of a tunnel through pile-sheet retaining wall according to claim 1, characterized in that: A tie beam is provided between the newly added crown beam and the existing pile top crown beam.

5. The combined reinforcement structure of a tunnel through pile-sheet retaining wall according to claim 1, characterized in that: If the tunnel width is less than 5 meters, one anti-slip pile is installed on each side of the tunnel; if the tunnel width is greater than 5 meters, two anti-slip piles are installed on each side of the tunnel.

6. The combined reinforcement structure of a tunnel through pile-sheet retaining wall according to claim 1, characterized in that: The anchor rods are arranged horizontally, and the tunnel also includes a second expansion area. After the second expansion area is expanded upward, it is expanded toward the top and both sides to the anti-slip piles on both sides of the tunnel. A connecting beam is provided in the second expansion area, and both ends of the connecting beam are respectively connected to two anti-slip piles.

7. A combined reinforcement structure for a tunnel passing through a pile-sheet retaining wall according to claim 6, characterized in that: The tunnel also includes a third expansion area, which is expanded upward to the anchor rod. The support area and the breaking area are both within the third expansion area or pass through the support arch. A support arch is provided in the support area, and the anchor rod end is arranged in the support arch. The support arch is connected to the existing piles in the support area.

8. The combined reinforcement structure of a tunnel through pile-sheet retaining wall according to claim 6, characterized in that: The connecting beam is a reinforced concrete structure, and the steel bars at the ends of the connecting beam are embedded in the anti-sliding piles.

9. The combined reinforcement structure of a tunnel through pile-sheet retaining wall according to claim 6, characterized in that: The anchor rods of the vault pass through the connecting beams.

10. The combined reinforcement structure of a tunnel through pile-sheet retaining wall according to claim 1, characterized in that: The anchor rod is arranged obliquely upwards, and is a hollow grouting anchor rod. The grouting hole of the hollow grouting anchor rod is arranged at the upper end of the hollow grouting anchor rod, and the lower end of the hollow grouting anchor rod is used for connection with the later support of the tunnel.

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