Combined construction method for reinforcing pile plate retaining wall

Abstract

The invention relates to rock-soil deep curing treatment, and discloses a combined construction method for reinforcing a pile-slab retaining wall, which comprises the following steps: step 1, excavating a tunnel to a first expanding excavation area, constructing a cover arch on one side, close to an existing pile, in the first expanding excavation area, punching in the circumferential direction of the cover arch, placing an anchor rod, and carrying out pile-slab retaining wall reinforcement; therefore, it is guaranteed that the extension line penetrates through the anchor rod end of the existing pile to be inserted into the existing pile to form a supporting area, and grouting is conducted to seal the drilled hole; and secondly, a breaking area is arranged on the built-in section of the existing pile, when excavation is conducted to the position of the existing pile, the breaking area of the existing pile is broken, and the tunnel penetrates through the breaking area. On the premise that the structural integrity of a pile body is ensured, the limitation of underground space is broken through, and directional compensation of the mechanical property of a pile-soil system is achieved.

Description

Technical Field

[0001] The invention relates to deep-layer solidification treatment of rock and soil, and in particular to a combined construction method for reinforcing a pile-sheet retaining wall. Background Art

[0002] With the advancement of three-dimensional development of urban underground space, the spatial conflict between tunnel engineering and existing support structures has become increasingly prominent. In the typical working condition where the existing slope support system and the newly built tunnel form a three-dimensional intersection, when the tunnel axis and the embedded section of the pile-sheet retaining wall have a spatial conflict, the traditional disposal scheme has major technical defects. The embedded section removal method can achieve tunnel penetration but seriously damages the mechanical balance of the pile-soil system: ① The removal of the embedded section leads to the loss of supporting force in the passive zone of the pile body, causing the failure of the pile-sheet retaining wall; ② The reduction of the effective embedded depth of the pile foundation induces the risk of slope slip. This irreversible structural damage has become an important threat to the safety of urban underground engineering.

[0003] In response to the above problems, the engineering community has tried to use a prestressed anchor cable reinforcement system for stability compensation. This technology improves anti-overturning capacity by adding a pile top anchor cable structure, but it has significant limitations in high-density built-up areas: anchor cable construction requires a surface working space with a diameter of more than 3m, and the existing building foundations and underground pipe networks hinder anchor cable construction.

[0004] Based on the above technical status, it is necessary to develop a reinforcement method for the existing embedded section of the anti-slide pile. On the premise of breaking the original embedded section of the existing anti-slide pile, it breaks through the constraints of the underground space and realizes the directional compensation of the mechanical properties of the pile-soil system. This is the core technical problem to be solved by the present invention. Summary of the invention

[0005] The present invention aims to provide a combined construction method for reinforcing pile-sheet retaining walls, which breaks through the constraints of underground space and realizes directional compensation of the mechanical properties of the pile-soil system on the premise of removing the original embedded sections of the existing anti-slide piles.

[0006] To achieve the above object, the present invention adopts the following technical solution: a combined construction method for reinforcing pile-sheet retaining wall, comprising the following steps:

[0007] Step 1: excavate the tunnel to the first expansion area, construct a sleeve arch in the first expansion area close to the existing pile, drill holes circumferentially in the sleeve arch and insert anchor rods, so as to ensure that the extension line passes through the anchor rod end of the existing pile and is inserted into the existing pile to form a support area, and grouting is performed to close the drilled hole;

[0008] Step 2: A breaking area is provided on the embedded section of the existing pile. When excavation reaches the position of the existing pile, the breaking area of ​​the existing pile is broken, and the tunnel passes through the breaking area.

[0009] The beneficial effects of this program are:

[0010] 1. Limited by the surrounding space and aiming to reduce the scope of construction impact, in order to eliminate the process of excavating the soil in front of the piles, the inventor considered various solutions:

[0011] If completely using ground construction, first excavate several anti-slide piles on the ground, then construct a capping beam on the tops of several anti-slide piles to form a portal support structure, and finally construct anchor rods on the capping beam above the tunnel. By setting the anchor rods inclined downward, the capping beam and the existing piles are connected. However, the spacing between the anti-slide piles and the existing piles should not exceed five times the diameter of the anti-slide pile, otherwise, if the spacing is too large, it is difficult to form a coordinated 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 demolished.

[0012] In this solution, neither ground construction nor excavation of the soil in front of the piles is adopted. Instead, during the tunnel excavation process, a sleeve arch and horizontal anchor rods are constructed to connect with the existing piles, thereby ensuring the reliability of the existing piles, reducing the disturbance to the surrounding soil, and forming a new reinforcement technology system that not only maintains the integrity of the pile structure but also adapts to the narrow working space.

[0013] 2. By connecting the existing piles with anchor rods, 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.

[0014] Furthermore, in step one, before excavating the tunnel, construct a ground reinforcement structure, including the following steps:

[0015] 1.1 Construct anti-slide piles on both sides of the tunnel;

[0016] 1.2 Construct the capping beam of the newly added anti-slide piles.

[0017] Furthermore, in step 1.1, the anti-slide piles are arranged in rows and parallel to the existing piles in rows.

[0018] Furthermore, in step 1.1, the horizontal distance between the anti-slide piles and the existing piles is 1 to 5 times the diameter or cross-sectional height of the anti-slide pile.

[0019] Furthermore, in step 1.2, a tie beam is provided between the newly added capping beam and the capping beam on the top of the existing piles.

[0020] Furthermore, in step 1.1, if the tunnel width is less than 5 meters, one anti-slide pile is provided on each side of the tunnel; if the tunnel width is greater than 5 meters, two anti-slide piles are provided on each side of the tunnel.

[0021] Furthermore, in Step 1, the anchor rods are horizontally arranged; in Step 2, before excavating to the position of the existing piles, the tunnel is excavated to the second excavation area. After the second excavation area is excavated upward, it is excavated to the anti-sliding piles on both sides of the top, and a connecting cross beam is poured in the second excavation area. The two ends of the connecting cross beam are respectively connected to the two anti-sliding piles.

[0022] Furthermore, the connecting cross beam is of reinforced concrete structure, and the steel bars at the ends of the connecting cross beam are implanted into the anti-sliding piles.

[0023] Furthermore, the anchor rods at the vault pass through the connecting cross beam.

[0024] Furthermore, in Step 1, the anchor rods are inclined upwardly arranged. The anchor rods are hollow grouting anchor rods, and the grouting holes of the hollow grouting anchor rods are arranged at the upper ends of the hollow grouting anchor rods. Before grouting to seal the boreholes, grout is injected into the hollow grouting anchor rods, and the mortar solidifies after flowing out of the upper ends of the hollow grouting anchor rods;

[0025] After Step 2 is completed, the lower ends of the hollow grouting anchor rods are poured into the later support of the tunnel.

[0026] This solution also has the following effects:

[0027] 1. For the ground structure, the distance between the anti-sliding piles and the existing piles needs to be as close as possible. The horizontal distance D between the anti-sliding piles and the existing piles should be 1 to 5 times the pile diameter or cross-sectional height of the anti-sliding piles to form a collaborative force system, connecting the embedded section of the existing piles and the newly added anti-sliding piles into a whole to jointly resist the earth pressure behind the piles or the lateral pressure of the rock;

[0028] For the underground structure, the anchor rods are driven into the tunnel from the socket arch in the first excavation area, passing through the connecting cross beam and the support arch in sequence. The connecting cross beam connects the anti-sliding piles at both ends, and the support arch connects the existing piles above, so that the existing piles, anti-sliding 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 rods, thus compensating for the adverse effects on stability after the removal of the existing piles in the removal area. Specifically: Generally, the excavation of the tunnel has a large disturbance to the surrounding rock mass, and there are usually 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 rods and the tunnel excavation contour is uneven, and the surrounding rock below the anchor rods is difficult to effectively support the anchor rods. Instead of directly removing the surrounding rock below the anchor rods and re-pouring the support arch, connecting the anchor rods with the primary support and the secondary lining constructed later in the tunnel, the concentrated load transmitted from the edge of the existing pile removal area is transmitted along the longitudinal direction of the tunnel to the primary support and the secondary lining of the tunnel through the anchor rods, thereby dispersing the stress and improving the stability of the overall structure.

[0029] 2. Generally, after the anchorage section of the existing pile is excavated for the construction of the tunnel, the existing pile will overturn and cause the overall structure to deform and fail. In this solution, however, the passive earth pressure is maintained for the existing pile through the anchor rod, and the capping beam distributes the tension received by the tie rod to the surrounding anti-slide piles, thereby increasing the stability and anti-overturning ability of the overall structure.

[0030] 3. The deformation and cracking of the tie beam can be used as a warning for the existing pile to start overturning, so that the personnel on the ground can immediately discover the overturning of the existing pile and take remedial measures in time.

[0031] 4. In the prior art, when constructing the anchor rod on the pile-plank retaining wall, the anchor rod is usually constructed obliquely downward on the side of the pile-plank retaining wall close to the foundation pit to provide tension for the pile-plank retaining wall; however, since the pile-plank retaining wall in this solution is an existing structure and the existing building in the corresponding foundation pit has been built, there is not enough space to construct the anchor rod. Therefore, on the contrary, the anchor rod is constructed obliquely upward from the lower tunnel. The upper end of the anchor rod is inserted into the pile-plank 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, thereby providing a reaction force for the anchor rod.

[0032] That is, the earth pressure acts on the existing pile, and through this newly added anchor rod, the force is transmitted to the rock in the enlarged area. The anchor rod is anchored on the tunnel rock wall, changing the conventional method of driving the anchor rod from the pile-plank retaining wall and driving the anchor rod reversely from the tunnel, which can solve the problem of inability to drive the cable anchor for reinforcement. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is the flow chart of Embodiment 1;

[0034] Figure 2 is the schematic plan view of the initial state of Embodiment 1;

[0035] Figure 3 is the schematic plan view of Construction Step 1.1 of Embodiment 1;

[0036] Figure 4 is the schematic plan view of Construction Step 1.2 of Embodiment 1;

[0037] Figure 5 is the schematic plan view of Construction Step 1.3 of Embodiment 1;

[0038] Figure 6 is the schematic plan view of Construction Step Two of Embodiment 1;

[0039] Figure 7 is the schematic sectional view of the initial state of Embodiment 1;

[0040] Figure 8 is the schematic sectional view of Construction Step 1.1 of Embodiment 1;

[0041] Figure 9 Schematic cross-section view of Construction Step 1.2 of Example 1;

[0042] Figure 10 Schematic cross-section view of Construction Step 1.3 of Example 1;

[0043] Figure 11 Schematic cross-section view of Step 2 of Example 1;

[0044] Figure 12 Schematic cross-section view of Step 2 of Example 2;

[0045] Figure 13 Schematic cross-section view of Step 2 of Example 3. Specific Embodiments

[0046] The following is a further detailed description through specific embodiments:

[0047] The reference numerals in the accompanying drawings of the specification include: existing building 1, existing piles 2, embedded section L1, free section L2, breaking area 21, supporting area 22, existing capping beam 23, anti-slide piles 31, cover beams 32, anchor bolts 33, tie beams 35, tunnel 4, first excavation area 41, second excavation area 42, connecting cross beam 43, supporting arch 44, support structure 45, third excavation area 46, socket arch 47.

[0048] Example 1

[0049] Example 1 is basically as Figures 1 - 11 shown: A combined construction method for strengthening a pile-plank retaining wall, applicable to: an existing building 1 and a newly built tunnel 4. As Figure 6 shown, there is a row of existing piles 2 on the left side of the existing building 1. As Figure 10 shown, the existing piles 2 include a free section L2 and an embedded section L1. There is a breaking area 21 on the embedded section L1 of the existing piles 2. As Figure 11 shown, according to the design requirements, the newly built tunnel 4 needs to pass through the breaking area 21 of the embedded section L1 of the existing piles 2;

[0050] A combined construction method for strengthening a pile-plank retaining wall includes the following steps:

[0051] Step 1.1: As Figure 3 and Figure 8 shown, construct the anti-slide piles 31 on both sides of the 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 provided on each side of the tunnel 4. If the width of the tunnel 4 is greater than 5 meters, two anti-slide piles 31 are provided on each side of the tunnel 4. In this Example 1, two anti-slide piles 31 are provided on each side of the tunnel 4;

[0052] Step 1.2: As shown in Figure 4 and Figure 9 , construct the capping beam of the newly added anti-slide pile 31. The capping beam is poured and connected to the tops of the four anti-slide piles 31. The capping beam spans over the tunnel 4, and there is also an existing capping beam 23 on the top of the existing pile 2. For the convenience of display, Figures 2 - 6 the existing capping beam 23 is omitted in . Four tie beams 35 are constructed between the existing capping beam 23 and the capping beam to pour the existing pile 2 and the anti-slide pile 31 together. The tie beams 35 correspond one by one to the anti-slide piles 31 and the existing piles 2 on both sides of the tunnel 4;

[0053] Step 1.3: As shown in Figure 5 and Figure 10 , excavate the tunnel 4 to the first excavation area 41. The first excavation area 41 is excavated circumferentially. A ring arch 47 is constructed on the side close to the existing pile 2 within the first excavation area 41. A number of holes are drilled horizontally circumferentially on the ring arch 47 and anchor rods 33 are respectively placed therein, so as to ensure that the end portions of the anchor rods 33 whose extension lines pass through the existing pile 2 are inserted into the existing pile 2 to form a support area 22, and the drilled holes are sealed by grouting; As shown in Figure 10 , the support area 22 is located above the breaking area 21. Figure 11 and Figure 10 The scope of the first excavation area 41 in is only for illustration. During the actual construction process, an operation space for drilling and installing the anchor rods 33 should also be reserved;

[0054] Step Two: As shown in Figure 6 and Figure 11 , during the construction of the tunnel 4 excavation, when excavating to the position of the existing pile 2, break the breaking area 21 of the existing pile 2, and construct the support structure 45 of the tunnel 4 such as the primary support and the secondary lining of the tunnel 4 according to the design and specifications.

[0055] Embodiment 2

[0056] On the basis of Embodiment 1, in Step Two: As shown in Figure 12 , the tunnel 4 further includes a second excavation area 42 and a third excavation area 46. The first excavation area 41, the second excavation area 42 and the third excavation area 46 are arranged in sequence from left to right. After the second excavation area 42 is excavated upward, it is excavated to both sides of the top to the anti-slide piles 31 on both sides of the tunnel 4;

[0057] A connecting cross beam 43 is poured within the second excavation area 42. The anchor rods 33 at the crown of the arch pass through the connecting cross beam 43. The connecting cross beam 43 is made of reinforced concrete. 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 respectively connected to the two anti-slide piles 31.

[0058] The third excavation area 46 is excavated upward to the anchor rod 33. The support area 22 and the demolition area 21 are both within the scope of the third excavation area 46. A support arch 44 made of reinforced concrete structure is poured in the support area 22. The end of the anchor rod 33 is arranged inside the support arch 44 or passes through the support arch 44. The support arch 44 is connected to the existing pile 2 in the support area 22.

[0059] Embodiment 3

[0060] The difference between Embodiment 3 and Embodiment 1 is that: as Figure 13 shown, in Step 1, the anchor rod 33 is arranged obliquely upward. 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. Before grouting to seal the drill hole, grout is injected into the hollow grouting anchor rod. After the mortar flows out of the upper end of the hollow grouting anchor rod, it solidifies, that is, it solidifies in the support area 22 formed by inserting the hollow grouting anchor rod into the existing pile 2.

[0061] After the end of Step 2, the lower end of the hollow grouting anchor rod is poured into the later support of the tunnel 4.

[0062] The above are only the embodiments of the present invention. Specific technical solutions and / or common knowledge such as characteristics well known in the art 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 deformations 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 required by 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 construction method for a reinforced pile-plank retaining wall, characterized in that , including the following steps: Step 1: Excavate the tunnel to the first excavation area. Construct a socket arch on the side close to the existing pile in the first excavation area. Drill holes circumferentially on the socket arch and insert anchor rods, so that 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 grout is used to seal the drill holes. Step 2: There is a breaking area on the embedded section of the existing pile. When excavating to the position of the existing pile, break the breaking area of the existing pile, and the tunnel passes through the breaking area.

2. The combined construction method of a reinforced pile-plank retaining wall according to claim 1, characterized in that: In Step 1, before excavating the tunnel, construct a ground reinforcement structure, including the following steps: 1.1 Construct anti-slide piles on both sides of the tunnel. 1.2 Construct the capping beam of the newly added anti-slide piles.

3. The combined construction method of a reinforced pile-plank retaining wall according to claim 2, characterized in that: In Step 1.1, the anti-slide piles are arranged in rows and parallel to the existing piles in rows.

4. A combined construction method for a reinforced pile - slab retaining wall according to claim 2, characterized in that: In Step 1.1, 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.

5. The combined construction method of a reinforced pile-plank retaining wall according to claim 2, characterized in that: In Step 1.2, there is a tie beam between the newly added capping beam and the existing pile top capping beam.

6. The combined construction method of a reinforced pile-plank retaining wall according to claim 2, characterized in that: In Step 1.1, if the tunnel width is less than 5 meters, one anti-slide pile is provided on each side of the tunnel; if the tunnel width is greater than 5 meters, two anti-slide piles are provided on each side of the tunnel.

7. A combined construction method of a reinforced pile - slab retaining wall according to claim 1, characterized in that: In Step 1, the anchor rods are horizontally arranged. In Step 2, before excavating to the position of the existing pile, excavate the tunnel to the second excavation area. After the second excavation area is excavated upward and then excavated to both sides of the top to the anti-slide piles on both sides of the tunnel, pour a connecting cross beam in the second excavation area, and both ends of the connecting cross beam are connected to the two anti-slide piles respectively.

8. A combined construction method for a reinforced pile-plank retaining wall according to claim 7, characterized in that: The connecting cross beam is a reinforced concrete structure, and the steel bars at the end of the connecting cross beam are implanted into the anti-slide piles.

9. A combined construction method of a reinforced pile-plank retaining wall according to claim 7, characterized in that: The anchor rods at the vault pass through the connecting cross beam.

10. A combined construction method of a reinforced pile-plank retaining wall according to claim 1, characterized in that: In Step 1, the anchor rods are inclined upward. The anchor rods are hollow grouting anchor rods, and the grouting holes of the hollow grouting anchor rods are arranged at the upper end of the hollow grouting anchor rods. Before grouting to seal the drill holes, grout is injected into the hollow grouting anchor rods, and the mortar solidifies after flowing out of the upper end of the hollow grouting anchor rods. After Step 2 is completed, the lower end of the hollow grouting anchor rod is cast into the later support of the tunnel.

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