Structural treatment methods for newly constructed underground units occupied by existing pipe jacking wells

Abstract

This invention provides a structural treatment method for locations where existing pipe jacking wells occupy the space of newly constructed underground buildings. By utilizing, modifying, and reinforcing the retaining piles and main structure of the existing pipe jacking wells that occupy the main structure of the newly constructed underground buildings, the discontinuity of the retaining structure caused by the occupation of the space by the existing pipe jacking wells can be effectively addressed. This avoids large deformation of the excavation and support of the new foundation pit at the location of the existing pipe jacking wells and significant impact on the surrounding environment, greatly shortening the construction period. In terms of technical feasibility, work efficiency, and implementation effect, this method is far superior to traditional methods.

Description

Technical Field

[0001] This invention relates to the field of building foundation pit construction technology, and in particular to a structural treatment method for newly built underground single-unit structures where existing pipe jacking wells occupy the space. Background Art

[0002] Currently, due to the rapid development of underground engineering, during the construction of retaining structures and main structures in complex environments, it is increasingly common to encounter underground obstacles such as existing pipe jacking shafts, preventing the retaining structure from being closed and resulting in the encroachment of the main structure area. Therefore, it is necessary to take measures to deal with these obstacles. Traditional methods include the following two approaches:

[0003] 1) The obstacle removal method is adopted, namely: using equipment such as full-rotation drilling rigs to remove the existing pipe jacking well structure, and backfilling is carried out after the entire process is completed. However, the backfilled soil will be excavated again during the main structure construction stage, resulting in secondary economic waste.

[0004] 2) The method of bypassing obstacles is adopted, namely: the new foundation pit retaining piles are moved and the new retaining piles are wrapped with obstacles to ensure the integrity of the retaining structure. This method increases the amount of engineering work of the retaining structure, which not only prolongs the construction period and expands the impact on the surrounding environment, but also creates secondary obstacles to the construction of the main structure.

[0005] In view of the shortcomings of traditional obstacle handling methods in the prior art, which involve clearing or avoiding obstacles, such as limited construction period, secondary waste of project costs, and large-scale impact on the surrounding environment, those skilled in the art have been looking for solutions. Summary of the Invention

[0006] The purpose of this invention is to provide a structural treatment method for newly constructed underground single-unit structures where existing pipe jacking wells occupy the space, in order to solve the problems of limited construction period, secondary waste of project costs, and large-scale impact on the surrounding environment caused by using traditional obstacle treatment methods in the prior art, which involve clearing or avoiding obstacles.

[0007] To solve the above-mentioned technical problems, the present invention provides a method for structural treatment of newly constructed underground buildings where existing pipe jacking wells occupy the space. The method for structural treatment of newly constructed underground buildings where existing pipe jacking wells occupy the space includes the following steps:

[0008] S1: After the new underground single-unit retaining structure is completed, high-pressure jet grouting piles are constructed at the joint between the existing pipe jacking well and the new underground single-unit retaining structure.

[0009] S2: Reinforce the existing underground pipelines within the influence range of the existing pipe jacking well using high-pressure jet grouting piles;

[0010] S3: Lower the groundwater level to 0.5m below the excavation surface of the new foundation pit;

[0011] S4: Remove the existing retaining piles of the jacking shaft to the first predetermined depth, and construct a reinforced concrete ring beam on the top of the removed surface of the existing retaining piles.

[0012] S5: Excavate the new foundation pit to the design elevation of the pit bottom, and simultaneously carry out the following construction during the excavation process:

[0013] The portion of the existing lining structure and retaining structure of the pipe jacking well that occupies the space of the new underground single-unit main structure is chiseled away, and lime soil is backfilled in layers from the chiseled surface to the bottom of the pit and compacted tightly.

[0014] The backfill soil in the existing pipe jacking shaft is excavated to the bottom elevation of the new foundation pit, forming a 1:1.5 slope. A second predetermined depth is reserved between the top of the slope and the bottom of the reinforced concrete ring beam as a space for inclined support operation, and the construction slope is protected.

[0015] S6: At the connection between the side wall and the bottom slab of the newly built underground single structure in the existing pipe jacking well area, a reinforced concrete corbel is cast to form an integral part of the bottom slab.

[0016] S7: Install inclined bracing between the reinforced concrete ring beam and the reinforced concrete corbel in the existing pipe jacking well area;

[0017] S8: Continue construction of the superstructure located in the newly built underground unit. After the superstructure reaches the design strength and specification requirements, remove the inclined bracing and reinforced concrete corbels, and backfill with soil to the design ground elevation.

[0018] Optionally, in the structural treatment method for the location where the newly constructed underground unit is occupied by the existing pipe jacking well, in S1, the horizontal reinforcement range of the high-pressure jet grouting pile is a range greater than or equal to 1.7m on the outside of the existing pipe jacking well water-stop curtain; the vertical reinforcement range is a range greater than or equal to 4m below the bottom of the newly constructed foundation pit.

[0019] Optionally, in the structural treatment method for the location where the newly built underground unit is occupied by the existing pipe jacking well, in S2, the working depth of the high-pressure jet grouting pile is: 1.2m below the ground to the bottom of the existing pipe jacking well.

[0020] Optionally, in the structural treatment method for the location where the newly built underground unit is occupied by the existing pipe jacking well, in S2, the horizontal protection distance of the existing underground surrounding pipelines is greater than or equal to 500mm, and the vertical protection distance is greater than or equal to 300mm.

[0021] Optionally, in the structural treatment method for the location where the newly built underground unit is occupied by the existing pipe jacking well, in S4, the first predetermined depth range is 1460m~1660m.

[0022] Optionally, in the structural treatment method for the location where a newly constructed underground unit is occupied by an existing pipe jacking well, S4 includes the following sub-steps:

[0023] S41: During the process of removing the existing retaining piles of the jacking shaft to the first predetermined depth, the main reinforcement of the existing retaining piles of the jacking shaft shall be retained.

[0024] S42: Reinforcing bars are tied to the main reinforcement bars at the top of the chiseled surface of the existing pipe jacking well retaining piles, and formwork is erected to form a reinforced concrete ring beam.

[0025] Optionally, in the structural treatment method for the location where the newly built underground unit is occupied by the existing pipe jacking well, in S42: the main reinforcement of the existing pipe jacking well retaining pile is anchored into the reinforced concrete ring beam by 40d; where d is the diameter of the main reinforcement.

[0026] Optionally, in the structural treatment method for the location where a newly constructed underground unit is occupied by an existing pipe jacking well, in step S5, the process of protecting the construction slope includes the following steps:

[0027] Lay an 8@200×200 steel mesh on the slope;

[0028] C20 is sprayed onto the steel mesh to form a 100mm thick concrete surface layer;

[0029] The distance from the toe of the slope to the drainage ditch is greater than or equal to 1m.

[0030] Optionally, in the structural treatment method for the location where the newly built underground unit is occupied by the existing pipe jacking well, in S5, the second predetermined depth range is 850mm~925mm.

[0031] Optionally, in the structural treatment method for the location where the newly built underground unit is occupied by the existing pipe jacking well, in S5, lime soil is backfilled in layers and compacted at an elevation position 1.0m away from the excavation surface to the bottom of the pit.

[0032] Optionally, in the structural treatment method for the location where the newly built underground unit is occupied by the existing pipe jacking well, in S7, the inclined bracing is HW400×400×13×21 steel.

[0033] In the structural treatment method provided by this invention for the location of a newly constructed underground unit occupied by an existing pipe jacking well, the existing pipe jacking well retaining piles and main structure occupying the main structure of the newly constructed underground unit are utilized, modified and reinforced. This method can effectively address the discontinuity of the retaining structure caused by the existing pipe jacking well occupying the new underground unit, thereby avoiding large deformation of the excavation support and the significant impact on the surrounding environment at the location of the existing pipe jacking well. It also greatly shortens the construction period and is significantly superior to traditional methods in terms of technical feasibility, work efficiency and implementation effect. Attached Figure Description

[0034] The above and other objects, features and advantages of this disclosure will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0035] Figure 1 This is a flowchart of a structural treatment method for a newly constructed underground unit where an existing pipe jacking well occupies space, according to an embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram of the structure after the new underground unit has been treated by the structural treatment method of the existing pipe jacking well occupying the space;

[0037] Figure 3 This is another schematic diagram of the structure after the new underground unit has been treated by the structural treatment method of the existing pipe jacking well occupying the space.

[0038] In the picture:

[0039] 1-High-pressure jet grouting pile; 2-Horizontal reinforcement range; 3-Vertical reinforcement range; 4-Existing surrounding pipelines; 5-Horizontal protection distance; 6'-Vertical protection distance; 6-Existing pipe jacking shaft; 7-New underground unit; 8-Existing pipe jacking shaft retaining piles; 9-First predetermined depth; 10-Reinforced concrete ring beam; 11-Inclined bracing; 12-Embedded steel plate; 13-Existing pipe jacking shaft inner lining main structure; 14-Distance from the excavation surface to the bottom of the pit; 15-Existing 16-Backfill soil inside the pipe jacking shaft; 17-Oblique support working space; 18-Concrete surface layer; 19-Reinforcing mesh surface; 20-Distance from slope toe to drainage ditch; 21-Reinforced concrete corbel; 22-Water-stop curtain of existing pipe jacking shaft; 23-Corbel height; 24-Side wall of newly built underground single structure; 25-Base slab; 26-Removed part; 27-Corbel width; 28-Outer side of reinforced concrete corbel; 29-Inner side of reinforced concrete corbel; 20-Horizontal spacing of corbel. DETAILED DESCRIPTION

[0040] The structural treatment method for newly constructed underground single-unit structures occupied by existing pipe jacking wells, as proposed in this invention, will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this invention.

[0041] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.

[0042] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0044] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0045] Please refer to Figures 1 to 3 The structural treatment method for newly constructed underground single-unit structures occupied by existing pipe jacking wells according to the present invention includes the following steps:

[0046] First, perform step S1. After the new underground single-unit retaining structure is completed, construct high-pressure jet grouting piles 1 at the joint between the existing jacking well 6 and the new underground single-unit retaining structure. The horizontal reinforcement range 2 of the high-pressure jet grouting piles 1 is a range greater than or equal to 1.7m outside the existing jacking well water-stop curtain (double-axis mixing pile) 21. The vertical reinforcement range 3 is a range greater than or equal to 4m below the bottom of the new foundation pit.

[0047] Next, please refer to Figure 2 Step S2 is executed, using high-pressure jet grouting piles 1 to reinforce the existing underground peripheral pipelines 4 within the influence range of the existing pipe jacking well 6; wherein, the high-pressure jet grouting piles 1 can be 700@500mm, with a cement content of 20%; the working depth of the high-pressure jet grouting piles 1 is: 1.2m below the ground to the bottom of the existing pipe jacking well 6; the horizontal protection distance 5 of the existing underground peripheral pipelines 4 is greater than or equal to 500mm, and the vertical protection distance 6' is greater than or equal to 300mm.

[0048] Next, step S3 is executed to lower the groundwater level to 0.5m below the excavation surface of the new foundation pit.

[0049] Next, step S4 is performed to modify the existing pipe jacking shaft 6: the existing pipe jacking shaft retaining piles 8 are chiseled to the first predetermined depth 9, and a reinforced concrete ring beam 10 is constructed on the top of the chiseled surface of the existing pipe jacking shaft retaining piles 8; in this embodiment, the first predetermined depth 9 is preferably in the range of 1460m~1660m.

[0050] Specifically, S4 includes the following steps:

[0051] S41: During the process of removing the existing retaining piles 8 of the jacking well to the first predetermined depth 9, the main reinforcement of the existing retaining piles 8 of the jacking well shall be retained.

[0052] S42: Reinforcing bars are tied to the main reinforcement bars at the top of the excavated surface of the existing pipe jacking shaft retaining pile 8, and a reinforced concrete ring beam 10 is formed by erecting formwork and pouring concrete. Specifically, the main reinforcement bars of the existing pipe jacking shaft retaining pile 8 are anchored into the reinforced concrete ring beam 10 by 40d; where d is the diameter of the main reinforcement bar.

[0053] Next, proceed to step S5, excavate the new foundation pit to the designed bottom elevation, and simultaneously carry out the following construction during the excavation process:

[0054] Excavation of the area occupied by the existing jacking shaft structure 6: The portion of the existing jacking shaft's inner lining main structure 13 enclosing structure that is located within the newly constructed underground single-unit main structure will be excavated (corresponding to...). Figure 2 In the middle section 25), lime soil is backfilled in layers between the excavated surface and the bottom of the pit and compacted tightly; in this embodiment, lime soil is backfilled in layers at an elevation of 1.0m between the excavated surface and the bottom of the pit and compacted tightly.

[0055] The backfill soil 15 inside the existing pipe jacking shaft 6 is excavated to the bottom elevation of the new foundation pit, forming a 1:1.5 slope. A second predetermined depth is reserved between the top of the slope and the bottom surface of the reinforced concrete ring beam 10 as a space 16 for inclined support operation. The slope protection is carried out during construction. Specifically, the second predetermined depth ranges from 850mm to 925mm. The process of slope protection includes the following steps:

[0056] Lay an 8@200×200 steel mesh 18 on the slope; spray C20 on the steel mesh 18 to form a 100mm thick concrete surface layer 17; the distance 19 from the toe of the slope to the drainage ditch is greater than or equal to 1m.

[0057] Next, step S6 is executed, where a reinforced concrete corbel 20 is cast at the connection between the newly built underground single structure sidewall 23 and the bottom plate 24 in the existing pipe jacking well area 6.

[0058] Next, step S7 is performed for reinforcement: an inclined brace 11 is installed between the reinforced concrete ring beam 10 and the reinforced concrete corbel 20 in the area of ​​the existing pipe jacking well 6; the inclined brace 11 is preferably HW400×400×13×21 steel.

[0059] Specifically, both ends of the inclined brace 11 are connected to the reinforced concrete ring beam 10 and the reinforced concrete corbel 20 through embedded steel plates 12. The cross-section of the reinforced concrete ring beam 10 is 1200mm×800mm. The length, width and height of the embedded steel plate 12 partially embedded in the reinforced concrete ring beam 10 are 600mm×800mm×25mm. The center of the embedded steel plate 12 and the center of the cross-section of the reinforced concrete ring beam 10 are on the same axis.

[0060] The reinforced concrete corbel 20 is constructed as follows: additional main reinforcement is provided on the upper part of the reinforced concrete corbel 20; the corbel height 22 is 800mm above the top slab surface; the corbel width 26 is equal to the width of the embedded steel plate 12; the outer side 27 of the reinforced concrete corbel uses a 1:0.625 variable cross section for transition; the inner side 28 of the reinforced concrete corbel uses a 1:1 variable cross section for transition; the planar arrangement of the reinforced concrete corbel 20 is as follows: one reinforced concrete corbel 20 is arranged along the center line of the existing jacking shaft 6; the remaining reinforced concrete corbels 20 are symmetrically arranged on both sides of the center line; the horizontal spacing 29 between adjacent corbels is 2.6m; additional main reinforcement is pre-set inside the reinforced concrete corbel 20; its anchorage length into the bottom slab 24 is not less than the seismic anchorage length of the reinforcement; its support stirrups are four-limb stirrups; the stirrup range is 500mm outward from the corbel on each side; and an embedded steel plate 12 is set on the outer slope of the reinforced concrete corbel 20 to ensure that the center of the embedded steel plate 12 and the center of the reinforced concrete corbel 20 are on the same axis.

[0061] Next, proceed to step S8 to continue construction of the superstructure located in the newly built underground unit 7. After the superstructure reaches the design strength and specification requirements, remove the inclined bracing 11 and the reinforced concrete corbel 20, and backfill the soil to the design ground elevation.

[0062] Please refer to Figure 2 and Figure 3 Based on the present invention, the processing method of the present invention is used to treat the structure of the newly built underground unit occupied by the existing pipe jacking well. By utilizing, modifying and reinforcing the retaining piles and main structure of the existing pipe jacking well that occupy the main structure of the newly built underground unit, the discontinuity of the retaining structure caused by the occupation of the new underground unit by the existing pipe jacking well can be effectively dealt with. This avoids large deformation of the excavation support of the new foundation pit at the existing pipe jacking well and large impact on the surrounding environment. Compared with the method of clearing or avoiding, the construction period is greatly shortened. It is much stronger than the traditional method in terms of technical feasibility, work efficiency and implementation effect.

[0063] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0064] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A method for structural treatment of locations where existing pipe jacking wells occupy space in newly constructed underground buildings, characterized in that, The following steps are involved: S1: After the new underground single-unit retaining structure is completed, high-pressure jet grouting piles (1) are constructed at the joint between the existing pipe jacking well (6) and the new underground single-unit retaining structure. S2: Reinforce the existing underground pipelines (4) within the influence range of the existing jacking well (6) using high-pressure jet grouting piles (1); S3: Lower the groundwater level to 0.5m below the excavation surface of the new foundation pit; S4: Remove the existing retaining piles (8) of the jacking shaft to the first predetermined depth (9), and construct a reinforced concrete ring beam (10) on the top of the removed surface of the existing retaining piles (8); S5: Excavate the new foundation pit to the design elevation of the pit bottom, and simultaneously carry out the following construction during the excavation process: The portion of the existing lining structure (13) of the existing pipe jacking well that occupies the space of the new underground single main structure is chiseled away, and lime soil is backfilled in layers between the chiseled surface and the bottom of the pit and compacted tightly. Excavate the backfill soil (15) in the existing pipe jacking well (6) to the bottom elevation of the new foundation pit and form a 1:1.5 slope. Reserve a second predetermined depth between the top of the slope and the bottom surface of the reinforced concrete ring beam (10) as a space for inclined support operation (16) and construction slope protection. S6: At the connection between the side wall (23) of the newly built underground single structure and the bottom plate (24) in the area of ​​the existing pipe jacking well (6), a reinforced concrete corbel (20) is cast to form an integral part of the bottom plate (24); S7: Install inclined bracing (11) between the reinforced concrete ring beam (10) and the reinforced concrete corbel (20) in the area of ​​the existing pipe jacking well (6); S8: Continue construction of the superstructure located in the newly built underground unit (7). After the superstructure reaches the design strength and specification requirements, remove the inclined bracing (11) and reinforced concrete corbel (20), and backfill the soil to the design ground elevation.

2. The structural treatment method for locations where existing pipe jacking wells occupy spaces in newly constructed underground single-unit structures, as described in claim 1, is characterized in that... In S1, the horizontal reinforcement range (2) of the high-pressure jet grouting pile (1) is a range greater than or equal to 1.7m outside the existing jacking well water-stop curtain (21); the vertical reinforcement range (3) is a range greater than or equal to 4m below the bottom of the new foundation pit.

3. The structural treatment method for locations where existing pipe jacking wells occupy newly constructed underground single-unit spaces, as described in claim 1, is characterized in that... In S2, the working depth of the high-pressure jet grouting pile (1) is 1.2m below the ground to the bottom of the existing jacking well (6).

4. The structural treatment method for locations where existing pipe jacking wells occupy spaces in newly constructed underground single-unit structures, as described in claim 1, is characterized in that... In S2, the horizontal protection distance (5) of the existing underground surrounding pipelines (4) is greater than or equal to 500mm, and the vertical protection distance (6') is greater than or equal to 300mm.

5. The structural treatment method for locations where existing pipe jacking wells occupy newly constructed underground single-unit spaces, as described in claim 1, is characterized in that... In S4, the range of the first predetermined depth (9) is 1460m to 1660m.

6. The structural treatment method for locations where existing pipe jacking wells occupy spaces in newly constructed underground single-unit structures, as described in claim 1, is characterized in that... S4 includes the following steps: S41: During the process of chiseling away the existing retaining piles (8) of the jacking well to the first predetermined depth (9), the main reinforcement of the existing retaining piles (8) of the jacking well is retained; S42: The main reinforcement bars on the top of the chiseling surface of the existing pipe jacking well retaining pile (8) are tied with steel bars, and the formwork is erected and the reinforced concrete ring beam (10) is poured.

7. The structural treatment method for locations where existing pipe jacking wells occupy spaces in newly constructed underground single-unit structures, as described in claim 6, is characterized in that... In S42: the main reinforcement of the existing pipe jacking well retaining pile (8) is anchored into the interior of the reinforced concrete ring beam (10) by 40d; where d is the diameter of the main reinforcement.

8. The structural treatment method for locations where existing pipe jacking wells occupy spaces in newly constructed underground single-unit structures, as described in claim 1, is characterized in that... In S5, the process of slope protection during construction includes the following steps: 8@200×200 steel mesh was laid on the slope (18); C20 is sprayed onto the steel mesh surface (18) to form a 100mm thick concrete surface layer (17); The distance from the foot of the slope to the drainage ditch (19) is greater than or equal to 1m.

9. The structural treatment method for locations where existing pipe jacking wells occupy spaces in newly constructed underground single-unit structures, as described in claim 1, is characterized in that... In S5, the second predetermined depth range is 850mm to 925mm.

10. The structural treatment method for locations where existing pipe jacking wells occupy spaces in newly constructed underground single-unit structures, as described in claim 1, is characterized in that... In S5, lime soil is backfilled in layers and compacted at an elevation position where the distance (14) between the excavated surface and the bottom of the pit is 1.0m.

11. The structural treatment method for locations where existing pipe jacking wells occupy newly constructed underground single-unit spaces, as described in claim 1, is characterized in that... In S7, the inclined brace (11) is HW400×400×13×21 steel.

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