Long-short combined close double-row pile enclosure structure and construction method

Abstract

The application provides a long-short combined close double-row pile retaining structure, which comprises existing retaining piles and retaining piles of a to-be-built structure; a part of the retaining piles of the to-be-built structure invades between two adjacent existing retaining piles and is combined with the two adjacent existing retaining piles; the top end of the retaining piles of the to-be-built structure shares a joint crown beam with the top end of the existing retaining piles; the interval between every two adjacent pile bodies of the retaining piles of the to-be-built structure is consistent with the interval between every two adjacent pile bodies of the existing retaining piles; a waist beam is arranged on the retaining piles of the to-be-built structure, and the waist beam is arranged at a position in a height range of 2-3 m above the bottom of the existing short retaining piles. The application is based on the bending stiffness of the pile body, considers the beneficial effect of the existing retaining piles on the retaining piles of the to-be-built structure, adopts the long-short combined close double-row pile retaining structure, can fully exert the supporting and retaining capacity of the existing short pile retaining structure, effectively reduces the land occupation area of the to-be-built retaining structure, and ensures the use width of the main body structure of the to-be-built station.

Description

Technical Field

[0001] This invention belongs to the field of construction technology of retaining structure for urban rail transit station foundation pits, and in particular relates to a retaining structure and construction method of a double-row pile retaining structure with a combination of long and short piles. Background Technology

[0002] With rapid economic growth and urbanization, urban population density is constantly rising, making traditional surface transportation increasingly congested and unable to meet people's daily travel needs. Therefore, developing underground rail transit, represented by subways, is of great significance for alleviating traffic congestion and improving the city's overall carrying capacity. At the same time, rapid urban development directly or indirectly compresses urban space, making urban buildings increasingly dense and leaving insufficient space for subway stations. The increasing number of subway line plans and constructions means that many urban areas that previously did not need subway lines now require them. To expand the service coverage of subways, it is inevitable to build subway stations in areas with insufficient space. How to construct subway stations under limited urban space conditions while ensuring no loss of internal space and operational functions is a major challenge in the field of urban transportation engineering. To address this, a new and old combined long and short pile retaining structure with closely spaced double-row retaining structures is proposed, along with a supporting structural calculation model. This approach fully utilizes the supporting capacity of existing short pile retaining structures while effectively reducing the footprint of the proposed retaining structure, thus ensuring the station's internal space and normal functionality. Summary of the Invention

[0003] In view of this, the present invention aims to overcome the defects in the prior art and proposes a double-row pile retaining structure with a combination of long and short piles and a construction method therefor.

[0004] To achieve the above objectives, the technical solution created by this invention is implemented as follows:

[0005] A double-row pile retaining structure combining long and short sections includes existing retaining piles and a proposed structural retaining pile, wherein the length of the proposed structural retaining pile is greater than that of the existing retaining piles.

[0006] The proposed structural retaining piles intrude into the portion between two adjacent existing retaining piles and are in contact with the two adjacent existing retaining piles. The top of the proposed structural retaining piles and the top of the existing retaining piles share a common cap beam. Furthermore, the spacing between any two adjacent piles of the proposed structural retaining piles is the same as the spacing between any two adjacent piles of the existing retaining piles.

[0007] A waist beam is provided on the retaining piles of the proposed structure. The waist beam is located within a height range of 2-3m above the bottom of the existing short retaining piles. The relative positional relationship between the existing retaining piles and the retaining piles of the proposed structure is: min(d1 / 2,d2 / 2). <E<(d1+d2) / 2,

[0008] Wherein, d1 is the diameter of the existing retaining pile, d2 is the diameter of the retaining pile of the proposed structure, and E is the distance between the existing retaining pile and the retaining pile of the proposed structure.

[0009] Furthermore, existing retaining piles are reinforced with grout.

[0010] Furthermore, when reinforcing existing retaining piles, grouting holes are installed at the waist beam position.

[0011] Furthermore, the grouting holes are arranged at an angle downwards, that is, at an angle to the outside of the existing retaining piles.

[0012] A method for calculating the equivalent model of the above-mentioned double-row pile retaining structure, characterized by comprising the following steps:

[0013] S1. Divide the proposed structural retaining piles into two parts: a section with a length of L1 that is closely attached to the existing retaining piles and a section with a length of L3 that is not closely attached to the existing retaining piles.

[0014] S2. For the closely fitted section of length L1, the beneficial effects of the existing retaining piles are considered, and the new and old piles are simplified to a single-row pile calculation according to the principle of equivalent bending stiffness; for the non-closely fitted section of length L3, the beneficial effects of the existing piles are not considered, and it is calculated as a single-row pile.

[0015] S3. When calculating the equivalent bending stiffness of the piles of the closely spaced retaining structure, the smallest calculation unit with a length equal to the designed pile spacing S is selected based on the pile layout. This smallest analysis unit is 1 / 2 of a proposed retaining pile and the existing retaining piles on both sides of it; that is, the smallest analysis unit includes a proposed pile and an existing pile.

[0016] S4. Based on the principle of structural static calculation, the centroidal axis of the combined support pile is determined, and the distances y1 and y2 between the proposed pile and the existing pile and the centroidal axis of the combined support are determined.

[0017] S5. Solve for the moments of inertia I1 and I2 of the old and new piles about the centroidal axis within the analysis unit. Based on the design materials E1 and E2 of the old and new retaining piles, the material of the closely fitted retaining piles is considered to be the same as that of the proposed retaining piles. Calculate the moment of inertia I of the closely fitted retaining piles according to the following formula.

[0018] E2I=(1*E1*I1+1*E2*I2)

[0019] Deformation, E2 is eliminated on both sides

[0020] I = η * I1 + I2

[0021] In the formula, η = E1 / E2. Considering that the position of the centroid axis of the combined support changes after the equivalent calculation, and the actual centroids of the upper and lower parts are inconsistent after the equivalent calculation, the actual gain effect of the existing pile is limited. Therefore, a gain coefficient γ for the existing pile is proposed.

[0022] The formula for calculating the moment of inertia I of the closely fitted retaining piles becomes:

[0023] I = γ*η*I1 + I2

[0024] γ is the coefficient for the effectiveness of the existing pile retaining structure, which is related to the diameter d2 of the retaining piles of the proposed structure, the distance between the old and new retaining piles E, and the distance between the retaining piles S.

[0025] S6. Based on the above calculation theory, the long and short combined close-fitting double-row retaining structure is equivalent to a single-row pile support structure with a pile spacing of S. Each single pile is divided into an upper structure with a length L1 and a moment of inertia I and a lower structure with a length L3 and a moment of inertia I2.

[0026] A construction method for the aforementioned double-row pile retaining structure includes the following steps:

[0027] Construct retaining piles for the proposed structure that are longer than the existing retaining piles on the side of the proposed structure, and keep the spacing between any two adjacent piles of the proposed structure consistent with the spacing between any two adjacent piles of the existing retaining piles. At the same time, ensure that each retaining pile of the proposed structure intrudes into the portion between the adjacent existing retaining piles on both sides, while being close to the existing retaining piles on both sides.

[0028] The existing partial capping beam at the top of the retaining piles will be removed. After the construction of the retaining piles of the proposed structure is completed, a new joint capping beam at the top of the old and new piles will be constructed.

[0029] A waist beam is constructed on the retaining piles of the proposed structure. The waist beam is located within a height range of 2-3m above the bottom of the existing short retaining piles to enhance the local structural strength of the retaining piles of the proposed structure.

[0030] Grouting holes are laid out diagonally downwards at the waist beam position, and excavation is carried out to the existing retaining piles. Grouting is then performed to reinforce the existing retaining piles.

[0031] Compared with existing technologies, the present invention has the following advantages:

[0032] This invention, based on the bending stiffness of the piles and considering the beneficial effects of existing retaining piles on the retaining piles of the proposed structure, incorporates a double-row, closely fitted arrangement of new and old piles, effectively creating a single-row pile retaining structure with high upper stiffness and low lower stiffness. Furthermore, this combination of long and short piles in a closely fitted double-row retaining structure not only fully utilizes the supporting capacity of the existing short pile retaining structure but also effectively reduces the footprint of the proposed retaining structure, ensuring the usable width of the proposed station's main structure. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0034] Figure 1 A schematic diagram of the plan view of the combined long and short, closely spaced double-row enclosure structure of this invention;

[0035] Figure 2 A schematic diagram illustrating the relative positions of the old and new enclosure structures for this invention;

[0036] Figure 3 A schematic diagram illustrating the equivalent calculation model of the double-row enclosure structure for this invention;

[0037] Figure 4 A schematic diagram of the smallest computational unit for creating an equivalent computational model for this invention. Detailed Implementation

[0038] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0039] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this 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, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] A type of retaining structure with closely spaced double-row piles of varying lengths, such as Figures 1 to 4As shown, the structure includes existing retaining piles 1 on the existing structural side 6 and proposed structural retaining piles 2 on the proposed structural side 7. The length of the proposed structural retaining piles is greater than that of the existing retaining piles. Preferably, the diameter of the proposed structural retaining piles is greater than that of the existing retaining piles.

[0043] The proposed structural retaining piles encroach on the portion between two adjacent existing retaining piles, and simultaneously adhere to the two adjacent existing retaining piles. The tops of the proposed structural retaining piles and the tops of the existing retaining piles share a common capping beam. When constructing the capping beam 4 of the proposed structural retaining piles, the existing capping beam 3 is first demolished. Then, after the construction of the proposed structural retaining piles is completed, the new and old capping beam 9 is reconstructed. Furthermore, the spacing between any two adjacent piles of the proposed structural retaining piles is consistent with the spacing between any two adjacent piles of the existing retaining piles.

[0044] A waist beam 8 is provided on the retaining piles of the proposed structure. The location of the waist beam is within 2-3m above the bottom of the existing short retaining piles. The relative positional relationship between the existing retaining piles and the retaining piles of the proposed structure is: min(d1 / 2,d2 / 2). <E<(d1+d2) / 2,

[0045] Wherein, d1 is the diameter of the existing retaining pile, d2 is the diameter of the retaining pile of the proposed structure, and E is the distance between the existing retaining pile and the retaining pile of the proposed structure.

[0046] For existing retaining piles, grouting reinforcement is used. When reinforcing the existing retaining piles, grouting holes are arranged at the waist beam position to reduce the risk of damage to the existing retaining structure's kick plate. Preferably, the grouting holes are arranged obliquely downwards, that is, obliquely towards the outside of the existing retaining piles.

[0047] A method for calculating the equivalent model of the double-row pile retaining structure as described in claim 1 includes the following steps:

[0048] S1. Divide the proposed structural retaining piles into two parts: a section with a length of L1 that is closely attached to the existing retaining piles and a section with a length of L3 that is not closely attached to the existing retaining piles.

[0049] S2. For the closely fitted section of length L1, the beneficial effects of the existing retaining piles are considered, and the new and old piles are simplified to a single-row pile calculation according to the principle of equivalent bending stiffness; for the non-closely fitted section of length L3, the beneficial effects of the existing piles are not considered, and it is calculated as a single-row pile.

[0050] S3. When calculating the equivalent bending stiffness of the piles in the closely spaced retaining structure, the smallest calculation unit 5 with a length equal to the designed pile spacing S is selected based on the pile layout. This smallest analysis unit is half the length of one proposed retaining pile and the existing retaining piles on both sides. In other words, the smallest analysis unit for calculating the equivalent bending stiffness of the piles in the closely spaced retaining structure includes one proposed pile and one existing pile.

[0051] S4. Based on the principle of structural static calculation, the centroidal axis 12 of the combined support pile body is determined, and the distances y1 and y2 of the proposed pile body and the existing pile body from the centroidal axis of the combined support body are determined.

[0052] S5. Solve for the moments of inertia I1 and I2 of the existing retaining pile centroidal axis 10 and the proposed retaining pile centroidal axis 11 within the analysis unit. Based on the design materials E1 and E2 of the old and new retaining piles, the material of the closely fitted retaining piles is considered to be the same as that of the proposed retaining piles. Calculate the moment of inertia I of the closely fitted retaining piles according to the following formula.

[0053] E2I=(1*E1*I1+1*E2*I2)

[0054] Deformation, E2 is eliminated on both sides

[0055] I = η * I1 + I2

[0056] In the formula, η = E1 / E2. Considering that the position of the centroid axis of the combined support changes after the equivalent calculation, and the actual centroids of the upper and lower parts are inconsistent after the equivalent calculation, the actual gain effect of the existing pile is limited. Therefore, a gain coefficient γ for the existing pile is proposed.

[0057] The formula for calculating the moment of inertia I of the closely fitted retaining piles becomes:

[0058] I = γ*η*I1 + I2

[0059] γ is the coefficient for the effectiveness of the existing pile retaining structure, which is related to the diameter d2 of the retaining piles of the proposed structure, the distance between the old and new retaining piles E, and the distance between the retaining piles S.

[0060] S6. Based on the above calculation theory, the long and short combined close-fitting double-row retaining structure is equivalent to a single-row pile support structure with a pile spacing of S. Each single pile is divided into an upper structure with a length L1 and a moment of inertia I and a lower structure with a length L3 and a moment of inertia I2.

[0061] A construction method for the aforementioned double-row pile retaining structure includes the following steps:

[0062] Construct retaining piles for the proposed structure that are longer than the existing retaining piles on the side of the proposed structure, and keep the spacing between any two adjacent piles of the proposed structure consistent with the spacing between any two adjacent piles of the existing retaining piles. At the same time, ensure that each retaining pile of the proposed structure intrudes into the portion between the adjacent existing retaining piles on both sides, while being close to the existing retaining piles on both sides.

[0063] The existing partial capping beam at the top of the retaining piles will be removed. After the construction of the retaining piles of the proposed structure is completed, a new joint capping beam at the top of the old and new piles will be constructed.

[0064] A waist beam is constructed on the retaining piles of the proposed structure. The waist beam is located within a height range of 2-3m above the bottom of the existing short retaining piles to enhance the local structural strength of the retaining piles of the proposed structure.

[0065] Grouting holes are laid out diagonally downwards at the waist beam position, and excavation is carried out to the existing retaining piles. Grouting is then performed to reinforce the existing retaining piles.

[0066] This invention, based on the bending stiffness of piles and considering the beneficial effects of existing retaining piles on the retaining piles of the proposed structure, incorporates a double-row, closely fitted structure of new and old piles, equivalent to a single-row pile retaining structure with high upper stiffness and low lower stiffness. Furthermore, this double-row, closely fitted retaining structure, combining long and short piles, fully utilizes the supporting capacity of the existing short pile retaining structure while effectively reducing the footprint of the proposed retaining structure, ensuring the usable width of the proposed station's main structure. While ensuring the safety of the retaining structure, it also reduces the length and diameter of the new retaining piles to a certain extent, saving materials and labor, and shortening the construction period. It has significant potential for widespread application and provides a valuable reference for the design and construction of retaining structures for subway stations in confined spaces adjacent to existing structures.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A double-row pile retaining structure combining long and short sections, characterized in that: This includes existing retaining piles and retaining piles for the proposed structure, with the length of the retaining piles for the proposed structure being greater than that of the existing retaining piles. The proposed structural retaining piles intrude into the portion between two adjacent existing retaining piles and are in contact with the two adjacent existing retaining piles. The top of the proposed structural retaining piles and the top of the existing retaining piles share a common cap beam. Furthermore, the spacing between any two adjacent piles of the proposed structural retaining piles is the same as the spacing between any two adjacent piles of the existing retaining piles. A waist beam is provided on the retaining piles of the proposed structure. The waist beam is located within a height range of 2-3m above the bottom of the existing retaining piles. The relative positional relationship between the existing retaining piles and the retaining piles of the proposed structure is: min(d1 / 2,d2 / 2). <E<( d1+d2) / 2, Where d1 is the diameter of the existing retaining pile, d2 is the diameter of the retaining pile of the proposed structure, and E is the distance between the existing retaining pile and the retaining pile of the proposed structure. Existing retaining piles are reinforced with grouting. When reinforcing existing retaining piles, grouting holes are arranged at the waist beam position; The grouting holes are arranged at an angle downwards.

2. A calculation method for the equivalent model of the double-row pile retaining structure as described in claim 1, characterized in that, Includes the following steps: S1. Divide the proposed structural retaining piles into a closely fitted section of length L1 that is in close contact with the existing retaining piles and a non-closely fitted section of length L3. S2. For the closely spaced section of length L1, considering the beneficial effects of the existing retaining piles, the retaining piles of the proposed structure and the existing retaining piles are simplified to a single row of piles according to the principle of equivalent bending stiffness; for the non-closely spaced section of length L3, the beneficial effects of the existing retaining piles are not considered, and it is calculated as a single row of piles. S3. When calculating the equivalent bending stiffness of the piles of the closely spaced retaining structure, the smallest calculation unit with a length of the designed pile spacing S is selected based on the pile layout method. This smallest calculation unit is 1 / 2 of a proposed retaining pile and the existing retaining piles on both sides of it. S4. Based on the principle of structural static calculation, the centroidal axis of the combined support pile body is determined, and the distances y1 and y2 between the proposed structure retaining pile body and the existing retaining pile body and the centroidal axis of the combined support body are determined. S5. Solve for the moments of inertia I1 and I2 of the proposed structural retaining piles and the existing retaining piles about the centroidal axis within the smallest calculation unit. Based on the design materials E1 and E2 of the proposed structural retaining piles and the existing retaining piles, the material of the closely fitted retaining piles is considered to be the same as that of the proposed structural retaining piles. Calculate the moment of inertia I of the closely fitted retaining piles according to the following formula. E2I=(1 E1 I1+1 E2 I2) Deformation, E2 is eliminated on both sides I=η I1+I2 In the formula, η = E1 / E2. Considering that the position of the centroid axis of the combined support changes after the equivalent calculation, and the actual centroids of the upper and lower parts are inconsistent after the equivalent calculation, the actual gain effect of the existing retaining piles is limited. Therefore, a gain coefficient γ for the existing retaining piles is proposed. The formula for calculating the moment of inertia I of the closely fitted retaining piles becomes: I=γ or I1+I2 γ is the coefficient of effectiveness of the existing pile retaining structure, which is related to the diameter d2 of the retaining piles of the proposed structure, the distance E between the retaining piles of the proposed structure and the existing retaining piles, and the design pile spacing S. S6. Based on the above calculation theory, the long and short combined close-fitting double-row retaining structure is equivalent to a single-row pile support structure with a pile spacing of S. Each single pile is divided into an upper structure with a length L1 and a moment of inertia I and a lower structure with a length L3 and a moment of inertia I2.

3. A construction method for the double-row pile retaining structure as described in claim 1, characterized in that, Includes the following steps: Construct retaining piles for the proposed structure that are longer than the existing retaining piles on the side of the proposed structure, and keep the spacing between any two adjacent piles of the proposed structure consistent with the spacing between any two adjacent piles of the existing retaining piles. At the same time, ensure that each retaining pile of the proposed structure intrudes into the portion between the adjacent existing retaining piles on both sides and is in close contact with the existing retaining piles on both sides. Remove the existing partial capping beam at the top of the retaining piles, and after the construction of the proposed retaining piles is completed, reconstruct the joint capping beam at the top of the proposed retaining piles and the existing retaining piles. A waist beam is constructed on the retaining piles of the proposed structure. The waist beam is located within a height range of 2-3m above the bottom of the existing retaining piles to enhance the local structural strength of the retaining piles of the proposed structure. Grouting holes are laid out diagonally downwards at the waist beam position, and excavation is carried out to the existing retaining piles, and then grouting is performed to reinforce the existing retaining piles.

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