A tunnel foundation pit bottom plate anti-floating fixed structure and construction technology

Abstract

The present application is a tunnel foundation pit bottom plate anti-floating fixed structure and construction process related to the field of tunnel construction, which includes a plurality of supporting piles fixed in the foundation pit around the inner wall of the foundation pit along the depth direction of the connection pit, the supporting piles are arranged in a ring-shaped area, each of the supporting piles is fixed with a receiving bolt facing the side of the pit, all the receiving bolts on the same side are welded with a connecting steel bar, and the plurality of connecting steel bars are arranged in a ring shape, a plurality of staggered supporting steel bars are arranged in the foundation pit, and the two ends of the supporting steel bars are respectively welded to the adjacent connecting steel bars, and finally concrete is poured on the supporting steel bars to form a bottom plate and each supporting pile is fixed to the bottom plate. The present application not only reduces the damage to the supporting piles, but also improves the overall construction efficiency.

Description

Technical Field

[0001] The present application relates to the field of tunnel construction, and in particular to an anti-floating fixed structure of a basic bottom plate of a tunnel and a construction process. Background Art

[0002] During foundation pit construction, in order to prevent sudden surges at the bottom of the foundation pit, the bottom of the foundation pit needs to be reinforced or blocked and anti-floating measures need to be taken. In current projects, most foundation pit support piles are used as anti-floating engineering piles, but there are some difficulties:

[0003] 1. In addition to meeting the requirements of foundation pit support (anti-overturning, anti-uplift, overall stability, and anti-bending and anti-shearing bearing capacity), the supporting piles should also solve the problem of how to meet the requirements of anti-floating bearing capacity, including the depth of insertion into the bottom of the pit and the reinforcement. 2. How to connect the supporting piles and the bottom plate of the underground structure as a whole, so that under the action of groundwater buoyancy, the supporting piles and the underground structure and its pile foundation work together without causing mutual displacement and deformation. 3. When the seismic requirements of the underground structure are high, what kind of structural structure is used to separate the bottom plate of the underground structure from the supporting piles, so as to allow deformation and displacement in the horizontal direction under the action of seismic force, and enable the supporting piles to still play an anti-floating bearing role.

[0004] Since the foundation pit support piles are constructed first, when constructing the foundation pit bottom plate structure, the support piles and the bottom plate of the underground structure should be connected as a whole before participating in the anti-floating work. The common construction method now is: Figure 1 and Figure 2 As shown, the staff first needs to remove the concrete on the side of the base of each supporting pile 1 facing the pit, so that a pit 12 is formed at the bottom of the supporting pile 1 and the steel bars in the supporting pile 1 are exposed. Then the staff begins to lay the supporting steel bars 4 of the bottom plate, and welds the two ends of the supporting steel bars 4 to the steel bars in the pit 12 relative to the supporting pile 1, thereby forming a supporting net with staggered supporting steel bars 4 at the bottom of the supporting pile 1, and connecting the supporting steel bars 4 to the steel bars in the supporting pile 1 as a whole. Finally, through the pouring of concrete, the bottom plate and the supporting pile 1 are formed as a whole.

[0005] However, this construction method has a drawback: chiseling away the concrete at the base of each supporting pile will reduce the support and bearing capacity of the base of the supporting pile. Summary of the invention

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a tunnel foundation pit bottom slab anti-floating fixed structure and construction process, which has the advantages of not only reducing damage to supporting piles but also improving construction efficiency.

[0007] The present application provides a tunnel foundation pit bottom plate anti-floating fixed structure adopts the following technical solution:

[0008] A tunnel foundation pit bottom plate anti-floating fixed structure comprises a plurality of supporting piles fixed in the foundation pit around the inner wall of the foundation pit along the depth direction of the connection pit, the supporting piles are arranged to form a ring-shaped area, each of the supporting piles is fixed with a receiving bolt facing the side of the connection pit, a connecting steel bar is welded to all the receiving bolts on the same side, and the plurality of connecting steel bars are arranged to form a ring, a plurality of supporting steel bars arranged in an alternating manner are arranged in the foundation pit, the two ends of the supporting steel bars are respectively welded to the adjacent connecting steel bars, and finally concrete is poured on the supporting steel bars to form a bottom plate and each supporting pile is fixed to the bottom plate.

[0009] By adopting the above technical solution, when fixing the bottom plate, the staff only needs to connect the receiving bolts to the side of each supporting pile facing the pit surface, and then put the connecting steel bars on the receiving bolts on the same side. The receiving bolts provide a support carrier for the connecting steel bars, which is not only convenient for positioning the connecting steel bars, but also improves the efficiency of welding the connecting steel bars and the receiving bolts. Finally, the supporting steel bars are staggered and laid in the area surrounded by several connecting steel bars, so as to realize the installation and fixation of the bottom plate steel mesh. Compared with the prior art, this solution does not need to damage the concrete of the supporting piles. It only needs to replace the complicated operation of welding with the internal steel bars of the supporting piles with the carriers of the receiving bolts, which greatly reduces the construction time and protects the original structure of the supporting piles, so that the strength of the supporting piles will not be affected during earthquakes. Moreover, when the seismic requirements are high, in order to meet the requirements of horizontal deformation and displacement under the action of earthquake force, the connection structure between the support piles and the base plate must be separated. Since each support pile is fixed to the connecting steel bar of the base plate by only one receiving bolt, it is easier for the staff to cut off the receiving bolt than the existing technology, so that the connection structure between the base plate and the support piles is separated, which helps to meet the seismic requirements.

[0010] Preferably, the receiving bolt is an expansion bolt.

[0011] By adopting the above technical solution, according to the construction requirements of the connection between the existing rigid material and concrete, the staff can use the pre-made embedded parts or post-placed chemical anchor bolts or expansion bolts. Since the casting method of the support pile cannot adopt the pre-made embedded parts connection method; the post-placed chemical anchor bolt connection has high strength, but the operation is more cumbersome and the construction period is longer; therefore, the expansion bolt connection method is adopted, which is mature, does not require extra time, has high economic benefits and is easy to operate.

[0012] Preferably, a plurality of supporting steel bars are fixed on the connecting steel bars of adjacent supporting piles.

[0013] By adopting the above technical solution, the staff can adjust the number of supporting steel bars according to the needs to meet the different strength requirements of the base plate. This is different from the existing technology of welding the internal steel bars of the supporting piles so that the strength of the base plate directly corresponds to the number of internal steel bars of the supporting piles, which has great limitations.

[0014] Preferably, a limiting component is also installed at the end of each of the connecting bolts to limit the separation of the connecting steel bar and the connecting bolt.

[0015] By adopting the above technical solution, the limiting component is set at the end of the connecting bolt, so that when the connecting steel bar is initially welded to each connecting bolt, the separation of the connecting steel bar and the connecting bolt is limited, thereby improving the stability of the connection between the connecting steel bar and each connecting bolt, thereby facilitating the workers to weld and fix the connecting steel bar, thereby improving construction efficiency.

[0016] Preferably, the limiting assembly includes a sleeve sleeved on the end of the receiving bolt, and a limiting plate fixed to one end of the sleeve, and the size of the limiting plate is larger than the cross-sectional size of the sleeve.

[0017] By adopting the above technical solution, after the worker fixes the receiving bolt, he sets the sleeve on the end of the receiving bolt. Through the friction between the sleeve and the receiving bolt, the limit plate is blocked at the end of the receiving bolt. If the connecting bolt swings, the limit plate limits the swing range of the connecting bolt, which is not easy to cause the connection steel bar and the receiving bolt to separate. In addition, the limit assembly has a simple structure, which improves the installation efficiency of the limit assembly.

[0018] Preferably, the sleeve is provided with an internal thread which cooperates with the thread of the receiving bolt.

[0019] By adopting the above technical solution, the sleeve is threadedly connected to the receiving bolt, which improves the stability of the connection between the sleeve and the receiving bolt and is also easy to operate.

[0020] In view of the shortcomings of the prior art, the second purpose of the present invention is to provide a construction process for a tunnel foundation pit floor, which can reduce damage to support piles while improving the overall construction efficiency.

[0021] To achieve the above object, the present invention provides the following technical solution: comprising the following steps:

[0022] S1: Material preparation: prepare the receiving bolts, connecting steel bars and supporting steel bars according to the design requirements; determine the specific length of the connecting steel bars and supporting steel bars according to the internal space of the foundation pit, and cut them in advance;

[0023] S2: Fixing the receiving bolts: determine the fixing position of the receiving bolts on the supporting piles, and open holes for fixing the receiving bolts on one side of the pit facing surface of the supporting piles, and then fix the receiving bolts in the holes;

[0024] S3: The connecting steel bars are positioned and fixed. A connecting steel bar is placed on all the receiving bolts on the same side. Then, the connecting steel bars and the overlapping positions of each receiving bolt are welded and fixed to each other, and the two ends of all the connecting steel bars are connected to each other to form a ring area.

[0025] S4: The support steel bars are positioned and fixed. Two groups of support steel bars are arranged. Each group of support steel bars is arranged side by side. The two ends of the support steel bars are respectively placed on the connecting steel bars on the corresponding side. The connecting points of the support steel bars and the connecting steel bars are welded to each other. The two groups of support steel bars are arranged in a staggered manner, and the staggered positions of the two groups of steel bars are tied.

[0026] S5: The bottom plate is cast and formed, and concrete is pumped into the bottom of the foundation pit to make the concrete evenly distributed, and the supporting steel bars are filled in the concrete.

[0027] By adopting the above technical solution, a construction process for tunnel foundation pit is provided. This solution does not need to damage the concrete of the support piles. It only needs to replace the complicated operation of welding with the internal steel bars of the support piles by the carrier of the receiving bolts, which greatly reduces the construction time and protects the original structure of the support piles, so that the strength of the support piles will not be affected during earthquakes. Moreover, when the seismic requirements are high, in order to meet the horizontal deformation and displacement under the action of earthquake forces, the support piles and the bottom plate connection structure must be separated. Since each support pile is fixed to the connecting steel bar of the bottom plate by only one receiving bolt, it is easier for the staff to cut off the receiving bolts than the existing technical staff, so that the connection structure between the bottom plate and the support piles is separated, which helps to meet the seismic requirements.

[0028] Preferably, a step is added before S3: a step is added before S3: a limit assembly is installed at the end of each receiving bolt.

[0029] By adopting the above technical solution, since the layout distance of the connecting steel bars is relatively long, it is easy for the connecting steel bars and the receiving steel bars to separate from each other when the staff performs preliminary positioning of the connecting steel bars. Therefore, the limiting assembly is installed at the end of the receiving bolt, so that the limiting plate limits the sliding of the connecting steel bars on the receiving bolt, thereby improving the operating efficiency of the staff.

[0030] Preferably, a step is added after S3, in which a positioning tube is provided directly above each receiving bolt, the positioning tube and the connecting steel bar are welded to each other, and the axial direction of the positioning tube is directed toward the receiving bolt.

[0031] By adopting the above technical solution and setting the positioning tube, an operating hole is formed in the positioning tube after concrete is poured, thereby reducing the distance between the bottom of the operating hole and the receiving bolt, making it easier for workers to cut the receiving bolt with tools and improving the efficiency of cutting the receiving bolt.

[0032] Preferably, a step is added before S5 to seal the inside of the positioning tube.

[0033] By adopting the above technical solution, the positioning tube is sealed, so that after the concrete is poured, the concrete is not easy to enter the positioning tube. After the concrete is solidified, the sealant in the positioning tube is taken out, so that an operating hole is formed in the positioning tube, thereby reducing the distance between the bottom wall of the positioning tube and the receiving bolt, making it easier for the staff to cut the receiving bolt with tools, thereby improving the cutting efficiency.

[0034] In summary, the present application includes at least one of the following beneficial technical effects:

[0035] 1. Reduced damage to the supporting piles. The present application replaces the existing construction step of removing concrete from the supporting piles by setting the receiving bolts, which greatly reduces the strength damage to the supporting piles;

[0036] 2. The construction period is shortened. Since there is no need to remove the wall of the supporting piles, the amount of wall removal construction is greatly reduced, and the construction efficiency is improved;

[0037] 3. The overall strength of the base plate is increased. By connecting the steel bars, the staff can adjust the number of supporting steel bars according to needs, so as to achieve the purpose of controlling the strength of the base plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the overall structure of the bottom anti-floating fixed structure in the background technology;

[0039] Figure 2 It is a schematic diagram of the connection structure between the supporting steel bars and the supporting piles in the bottom plate in the background technology;

[0040] Figure 3 It is a schematic diagram of the bottom plate anti-floating fixing structure in Embodiment 1;

[0041] Figure 4 It is a schematic diagram of the connection structure between the support piles and the internal support steel bars of the bottom plate in Example 1;

[0042] Figure 5 It is a construction process for the tunnel foundation pit bottom plate in embodiment 1;

[0043] Figure 6 It is a schematic diagram of the connection structure between the receiving bolt and the supporting pile in Example 2;

[0044] Figure 7 It is a partial structural schematic diagram showing the fixed position of the positioning tube in Example 2;

[0045] Figure 8 It is a construction process for the tunnel foundation pit bottom plate in Example 2.

[0046] Explanation of the reference numerals: 1. Support pile; 11. Connecting piece; 12. Pit; 2. Socket bolt; 3. Connecting steel bar; 4. Supporting steel bar; 5. Limiting assembly; 51. Sleeve; 52. Limiting plate; 6. Positioning tube; 61. Connecting rod; 62. Operating hole. DETAILED DESCRIPTION

[0047] The present application is further described in detail below in conjunction with all the drawings.

[0048] Embodiment 1: This embodiment of the present application discloses a bottom plate anti-floating fixed structure of a tunnel foundation pit, such as Figure 3 As shown, it is arranged in a foundation pit. This embodiment takes a rectangular foundation pit as an example. A plurality of root support piles 1 are erected in the foundation pit along the height direction of the foundation pit. The bottom of the support piles 1 is fixed to the bottom of the foundation pit, and the support piles 1 are evenly distributed along the inner wall of the foundation pit and enclose a rectangular annular area. The number of support piles 1 in each row is the same and corresponds one to one.

[0049] like Figure 3 and Figure 4 As shown, each supporting pile is provided with a fixing hole on the peripheral surface at the base, and the fixing hole is facing the side of the pit surface. A receiving bolt 2 is fixed in each fixing hole. The receiving bolt is an expansion bolt. The receiving bolts 2 in the same row are parallel to each other, and the axes of the receiving bolts 2 in the same row are located in the same horizontal plane. The receiving bolts 2 in the same row are also provided with a connecting steel bar 3, and the connection between the connecting steel bar 3 and each receiving bolt 2 is welded to each other.

[0050] Several supporting steel bars 4 are arranged between two connecting steel bars 3. The supporting steel bars 4 are perpendicular to the connecting steel bars 3. The two ends of the supporting steel bars 4 are respectively placed on the corresponding connecting steel bars 3 and welded to each other at the contact position of the connecting steel bars 3. Moreover, the supporting steel bars 4 are evenly arranged along the length direction of the two connecting steel bars 3. After adjusting the supporting steel bars 4 in one direction, the staff adjusts the supporting steel bars 4 connecting the other two sides in the same way, so that the supporting steel bars 4 in the two directions are close to each other and arranged at 90 degrees. The staff can adjust the number of supporting steel bars 4 arranged in the connecting steel bars 3 according to the strength requirements of the bottom plate, so that the supporting steel bars 4 can be evenly laid in the area surrounded by the four connecting steel bars 3. Compared with the prior art, the supporting steel bars 4 can only be connected to the internal steel bars of the supporting piles 1, so that the arrangement of the supporting steel bars 4 is lacking between the adjacent supporting piles 1, resulting in uneven arrangement of the bottom plate supporting steel bars 4 and uneven force. Therefore, in this application, by setting the receiving bolts 2 and the connecting steel bars 3, not only the problem of uneven distribution of the supporting steel bars 4 is solved, but also the supporting piles 1 do not need to be broken, which reduces the damage to the supporting piles 1 and improves the construction efficiency. Finally, the staff realizes the formation of the bottom plate by pouring concrete, and finally realizes the mutual fixation of the bottom plate and the supporting piles 1.

[0051] The length of each receiving bolt 2 protruding from the supporting pile 1 is 5 cm, so that when the connecting steel bar 3 is placed on the receiving bolts 2 in the same row, there can be enough space between it and the supporting pile 1, so that when the end of the supporting steel bar 4 is placed on the connecting steel bar 3, there is a margin between the end of the supporting steel bar 4 and the connection point of the connecting steel bar 3, making it difficult for the supporting steel bar 4 to detach from the connecting steel bar 3, and also improving the fault tolerance when the connecting steel bar 3 and the supporting steel bar 4 are fixed.

[0052] Moreover, the bottom plate anti-floating fixed decoupling strand in this embodiment can also meet higher earthquake resistance requirements. When an earthquake occurs, the horizontal force in the foundation pit needs to be overcome, and the support pile 1 needs to produce horizontal displacement deformation. Since the bottom plate is mutually fixed to the surrounding support piles 1, the displacement of the support piles 1 will be limited. Since in the prior art, the support steel bars 4 are welded to the internal steel bars of each support pile 1, it is difficult to separate the connection between the bottom plate and the support pile 1. In this embodiment, each supporting pile has only one receiving bolt 2 that is mutually fixed to the bottom plate. The staff only needs to cut off each receiving bolt 2 to separate the bottom plate from the trunk of each supporting pile, so that in the event of an earthquake, the staff can reduce losses by abandoning the bottom plate.

[0053] A construction process for a tunnel foundation pit bottom plate comprises the following steps: Figure 5 As shown:

[0054] S1: Material preparation. Determine the number of receiving bolts 2 to be prepared based on the number of supporting piles 1 and the design requirements of the base plate. Determine the cutting length of the connecting steel bars 3 and the supporting steel bars 4 based on the spacing between the supporting piles 1 and the layout range of the supporting piles 1 in the same row, so that they can be assembled and welded in time at the bottom of the foundation pit.

[0055] S2: Fixing of the receiving bolt 2. After the supporting pile 1 is cast and formed, determine the fixing position of each receiving bolt 2. Use an electric drill to drill a horizontal hole on the side of each supporting pile 1 located on the facing pit surface, and make the extension line of the hole axis intersect with the axis of the supporting pile 1. At the same time, keep the axes of all the holes in the same plane. Finally, fix the receiving bolt 2 in each hole, and make the receiving bolt 2 protrude from the outer wall of the supporting pile 1 by 5 cm.

[0056] S3: The connecting steel bars 3 are positioned and fixed, and each connecting steel bar 3 is placed on the receiving bolt 2 of the supporting pile 1 on each side, and then the contact points of the connecting steel bars 3 and each receiving bolt 2 are welded. When the four connecting steel bars 3 are welded and fixed to the receiving bolts 2, a rectangular area is formed in the foundation pit.

[0057] S4: The supporting steel bars 4 are fixed and divided into two groups. Each group of supporting steel bars 4 is arranged side by side, and the two ends of the supporting steel bars 4 are respectively placed on the connecting steel bars 3 on the corresponding side. Then, the connecting points of the supporting steel bars 4 and the connecting steel bars 3 are welded to each other. The two groups of supporting steel bars 4 are staggered and the staggered positions of the two groups of steel bars are tied. The staff can adjust the number of supporting steel bars 4 and the spacing between adjacent supporting steel bars 4 according to the design requirements to meet the requirements for changing the bottom plate strength.

[0058] S5: After the base plate is cast, the concrete truck is moved to the side of the foundation pit and the concrete is pumped into the bottom of the foundation pit. The concrete is then vibrated by an oscillating device to make the concrete evenly distributed and to expel the bubbles in the concrete until the concrete covers the supporting steel bars by 44-8cm. The casting is then completed.

[0059] S6: Base plate maintenance. Maintenance work should be carried out 12-18 hours after the base plate is poured. Watering and film covering maintenance should be carried out on the base plate. The formwork can be slightly loosened 24-48 hours after the concrete is poured, and watering and maintenance should be continued until the formwork is removed, and then moisture retention should be continued until the specified age.

[0060] Embodiment 2: A bottom plate anti-floating fixed structure of a tunnel foundation pit, such as Figure 6 As shown, the difference from Example 1 is that a stopper assembly 5 is provided at the end of each receiving bolt 2, and the stopper assembly 5 includes a sleeve 51, the inner wall diameter of the sleeve 51 is equal to the diameter of the receiving bolt 2, and the inner wall of the sleeve 51 is provided with an internal thread that matches the thread of the receiving bolt 2, and the end face of the sleeve 51 away from the outlet is coaxially fixed with a circular stopper piece 52, and the diameter of the stopper piece 52 is greater than the diameter of the outer peripheral surface of the sleeve 51. After the staff fixes the receiving bolt 2, the sleeve 51 is connected to the receiving bolt 2 by the thread, so as to fix the stopper assembly 5 at the end of each receiving bolt 2, and then the staff places the connecting steel bar 3 on the receiving bolt 2 in the same row. Since the stopper piece 52 is located at the end of the receiving bolt 2, even if the connecting steel bar 3 slides, it is not easy to cause the connecting steel bar 3 and the receiving bolt 2 to separate from each other, thereby improving the stability of the placement of the connecting steel bar 3, and facilitating the staff to weld and fix the connecting steel bar 3 and the receiving bolt 2 to each other later.

[0061] like Figure 7As shown, a rectangular positioning tube 6 is arranged above each receiving bolt 2, the center line of the positioning tube 6 is perpendicular to the plane where the bottom plate is located, and the lower end face of the positioning tube 6 is 2 cm away from the upper edge of the receiving bolt 2, and then the positioning tube 6 is welded to the connecting steel bar 3 through the connecting rod 61. The positioning tube 6 needs to be pre-filled before concrete pouring, and then after concrete pouring, the upper surface of the concrete is flush with the upper edge of the positioning tube 6. After the concrete is set, the filling of the positioning tube 6 is removed to form an operating hole 62 in the positioning tube 6. During an earthquake, the staff can quickly locate the fixed position of the receiving bolt 2 through the operating hole 62, and cut off the connection between the receiving bolt 2 and the supporting pile 1 through a cutting tool, thereby reducing the shaking of the bottom plate on each supporting pile 1 and reducing losses.

[0062] A construction process for a tunnel foundation pit bottom plate comprises the following steps: Figure 8 As shown:

[0063] S1: Material preparation. Determine the number of receiving bolts 2, limit assemblies 5, and positioning tubes 6 to be prepared according to the number of supporting piles 1 and the design requirements of the base plate. Determine the cutting length of the connecting steel bars 3 and the supporting steel bars 4 according to the spacing between the relative supporting piles 1 and the layout range of the supporting piles 1 in the same row, so that they can be assembled and welded in time at the bottom of the foundation pit.

[0064] S2: Fixing of the receiving bolt 2. After the supporting pile 1 is cast and formed, determine the fixing position of each receiving bolt 2. Use an electric drill to drill a horizontal hole on the side of each supporting pile 1 located on the facing pit surface, and make the extension line of the hole axis intersect with the axis of the supporting pile 1. At the same time, keep the axes of all the holes in the same plane. Finally, fix the receiving bolt 2 in each hole, and make the receiving bolt 2 protrude from the outer wall of the supporting pile 1 by 5 cm.

[0065] S3: Install the limiting assembly 5 , and threadably connect the sleeve 51 of the limiting assembly 5 to the receiving bolt 2 , so that the limiting piece 52 is located at the end of the receiving bolt 2 .

[0066] S4: The connecting steel bar 3 is positioned and fixed, and each connecting steel bar 3 is placed on all the receiving bolts 2 of the supporting piles 1 on each side. Under the limitation of the limiting plate 52, the separation of the connecting steel bar 3 and the receiving bolt 2 is limited, and then the contact points of the connecting steel bar 3 and each receiving bolt 2 are welded, so that the connecting steel bar 3 and all the receiving bolts 2 on the same side are fixed to each other. When the four connecting steel bars 3 are welded and fixed to the receiving bolts 2, a rectangular area is formed in the foundation pit.

[0067] S5: The supporting steel bars 4 are fixed and divided into two groups. Each group of supporting steel bars 4 is arranged side by side, and the two ends of the supporting steel bars 4 are respectively placed on the connecting steel bars 3 on the corresponding side. Then, the connecting points of the supporting steel bars 4 and the connecting steel bars 3 are welded to each other. The two groups of supporting steel bars 4 are staggered and the staggered positions of the two groups of steel bars are tied. The staff can intelligently adjust the number of supporting steel bars 4 and the spacing between adjacent supporting steel bars 4 according to the design requirements to meet the needs of changing the bottom plate strength.

[0068] S6: Fix the positioning tube 6. Place the positioning tube 6 just above the receiving bolt 2, keep the lower end face of the positioning tube 6 2 cm away from the upper boundary of the receiving bolt 2, and then weld the positioning tube 6 and the connecting steel bar 3 to each other to achieve the fixation of the positioning tube 6.

[0069] S7: Casting of the bottom plate, first put the filler into the positioning tube 6, then move the concrete truck to the side of the foundation pit, and pump the concrete into the bottom of the foundation pit, then oscillate the concrete through the oscillation device to make the concrete evenly distributed, and discharge the bubbles in the concrete, until the concrete and the upper end of the positioning tube 6 are flush with each other, and the casting is completed. After the concrete is initially formed, the filler is taken out to form an operating hole 62 in the positioning tube 6. In the event of an earthquake, the staff can quickly locate the fixed position of the receiving bolt 2 through the operating hole 62, and cut off the connection between the receiving bolt 2 and the support pile 1 through the cutting tool, thereby reducing the shaking of the bottom plate on each support pile 1 and reducing losses.

[0070] S8: Base plate maintenance. Maintenance work should be carried out 12-18 hours after the base plate is poured. Watering and film covering maintenance should be carried out on the base plate. The formwork can be slightly loosened 24-48 hours after the concrete is poured, and watering and maintenance should be continued until the formwork is removed, and then moisture retention should be continued until the specified age.

[0071] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A construction process for a tunnel foundation pit bottom plate anti-floating fixed structure, the structure comprising a plurality of support piles (1) fixed in the foundation pit around the inner wall of the foundation pit along the height direction of the foundation pit, the support piles (1) being arranged to form a ring-shaped area, characterized in that: Each of the supporting piles (1) is fixed with a receiving bolt (2) facing the side of the pit, and a connecting steel bar (3) is welded to all the receiving bolts (2) on the same side, and a plurality of connecting steel bars (3) are arranged in a ring shape, and a plurality of supporting steel bars (4) arranged in a staggered manner are arranged in the foundation pit, and the two ends of the supporting steel bars (4) are respectively welded to the adjacent connecting steel bars (3), and finally concrete is poured on the supporting steel bars (4) to form a bottom plate and each supporting pile (1) is fixed to the bottom plate; The following steps are involved: S1: Material preparation: prepare the receiving bolts (2), connecting steel bars (3), and supporting steel bars (4) according to the design requirements; determine the specific length and quantity of the connecting steel bars (3) and supporting steel bars (4) according to the internal space of the foundation pit, and cut them in advance; S2: Fixing the receiving bolt (2), determining the fixing height and position of the receiving bolt (2) on the supporting pile (1), and opening a hole for fixing the receiving bolt (2) on one side of the pit facing surface of the supporting pile (1), and then fixing the receiving bolt in the hole; S3: The connecting steel bar (3) is positioned and fixed, and a connecting steel bar (3) is placed on all the receiving bolts (2) on the same side, and then the connecting steel bar (3) and the overlapping position of each receiving bolt (2) are welded and fixed to each other, and the two ends of all the connecting steel bars (3) are connected to each other to form a ring-shaped area; S4: The supporting steel bars (4) are positioned and fixed. Two groups of supporting steel bars (4) are arranged. Each group of supporting steel bars (4) is arranged side by side. The two ends of the supporting steel bars (4) are respectively placed on the connecting steel bars (3) on the corresponding side. The connecting points of the supporting steel bars (4) and the connecting steel bars (3) are then welded to each other. The two groups of supporting steel bars (4) are arranged in a staggered manner. Finally, the staggered positions of the two groups of steel bars are tied together. S5: The bottom plate is cast and formed, concrete is pumped into the bottom of the foundation pit to make the concrete evenly distributed, and the supporting steel bars (4) are filled in the concrete; Add a step before S3 to install the limit assembly (5) at the end of each receiving bolt (2); A step is added after S3, wherein a positioning tube (6) is arranged directly above each receiving bolt (2), the positioning tube (6) and the connecting steel bar (3) are welded to each other, and the axial direction of the positioning tube (6) is directed toward the receiving bolt (2). A step is added before S5 to seal the inside of the positioning tube (6). After the concrete is initially set, the filler is removed to form an operation hole in the positioning tube (6). During an earthquake, the staff can quickly locate the fixed position of the receiving bolt (2) through the operation hole and cut off the connection between the receiving bolt (2) and the supporting pile (1) by using a cutting tool, thereby reducing the shaking of the bottom plate on each supporting pile (1) due to the horizontal unloading force.

2. The construction process of the tunnel foundation pit bottom plate anti-floating fixed structure according to claim 1 is characterized by: The receiving bolt (2) is an expansion bolt.

3. The construction process of the tunnel foundation pit bottom plate anti-floating fixed structure according to claim 1 is characterized by: A plurality of supporting steel bars (4) are fixed on the connecting steel bars (3) of adjacent supporting piles (1).

4. The construction process of the tunnel foundation pit bottom plate anti-floating fixed structure according to claim 2 is characterized by: A limiting component (5) is also installed at the end of each receiving bolt (2) for limiting the separation of the connecting steel bar (3) and the receiving bolt (2).

5. The construction process of the tunnel foundation pit bottom plate anti-floating fixed structure according to claim 4 is characterized by: The limiting assembly (5) comprises a sleeve (51) sleeved on the end of the receiving bolt (2), and a limiting plate (52) fixed on one end of the sleeve (51), wherein the size of the limiting plate (52) is larger than the cross-sectional size of the sleeve (51).

6. The construction process of the tunnel foundation pit bottom plate anti-floating fixed structure according to claim 5 is characterized by: The sleeve (51) is provided with an internal thread which matches the thread of the receiving bolt (2).

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