A subway anti-floating and anti-seismic structure adopting double-layer gravity cast-in-place piles and a construction method thereof

Abstract

The application discloses a kind of metro anti-floating seismic structure and construction method using double-layer gravity pouring pile.The anti-floating seismic structure includes station structure bottom plate, double-layer gravity pouring pile installed below station structure bottom plate, counterweight block arranged on pile top.Counterweight block is covered with concrete bottom seal.Double-layer gravity pouring pile includes inner pile pipe, outer pile pipe and top sealing plate;Inner pile pipe is sleeved in outer pile pipe;Top sealing plate closes the space between inner pile pipe and outer pile pipe as independent cavity.Independent cavity is filled with high-expansion gas before pouring;Inner layer hot melt liquid is poured in inner pile pipe during pouring, independent cavity is opened and poured with outer layer hot melt liquid.A plurality of holes are arranged on outer pile pipe at intervals;Holes are blocked with deformation sheet;Deformation sheet has plastic deformation capacity, and melting point is lower than pouring temperature of outer layer hot melt liquid.The anti-floating seismic structure and construction method effectively improve the anti-seismic and anti-floating performance of metro station structure by combining mechanical anchoring and gravity counterweight.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underground engineering construction, and particularly relates to a metro anti-floating and anti-seismic structure adopting double-layer gravity cast-in-place piles and a construction method. BACKGROUND

[0002] With the development of cities and population growth, urban traffic continues to expand into underground space. As the backbone of urban underground traffic, the subway is widely used due to its large capacity and fast running speed. The structural safety of the subway station, as the core hub of the subway system, directly affects the stable operation of the entire network.

[0003] In highly active economic regions such as the southeast coast, Beijing-Tianjin-Hebei, Yangtze River Delta, and Pearl River Delta, the subway operating mileage accounts for more than half of the total in China. However, these regions are mostly located in or adjacent to seismic activity belts, and subway stations face the risk of being affected by strong earthquakes. At the same time, many cities in China are often affected by heavy rainfall, causing the groundwater level to rise significantly in a short period of time. As a large-section underground structure, the self-weight of the subway station is relatively light. When the groundwater level rises, a large upward force is easily generated, causing the structure to float and displace, seriously threatening the overall safety and operation order of the subway system. Therefore, for subway stations in regions with complex geological and hydrological conditions, new structural systems with good anti-seismic and anti-floating performance are urgently needed. SUMMARY

[0004] The main technical problem to be solved by the present application is to provide a metro anti-floating and anti-seismic structure to effectively improve the anti-seismic and anti-floating performance of the subway station structure.

[0005] To solve the above technical problems, the present application provides a metro anti-floating and anti-seismic structure adopting double-layer gravity cast-in-place piles, which comprises a station structure bottom plate, double-layer gravity cast-in-place piles, and counterweights. The station structure bottom plate is provided with a plurality of construction holes along the thickness direction. A plurality of pile holes are drilled below the construction holes. The double-layer gravity cast-in-place piles are installed in the pile holes. The counterweights are arranged on the top of the double-layer gravity cast-in-place piles. The double-layer gravity cast-in-place piles comprise an inner pile tube, an outer pile tube, and a top sealing plate. The inner pile tube is sleeved in the outer pile tube to form a double-layer structure. The top sealing plate is arranged between the inner pile tube and the outer pile tube to close the space below the top sealing plate between the inner pile tube and the outer pile tube into an independent cavity.

[0006] The independent cavity is filled with a high-expansion gas before the pouring process of the double-layer gravity cast-in-place piles. In the pouring process, the inner layer of hot melt liquid is poured into the inner pile tube. The top of the independent cavity is opened and filled with the outer layer of hot melt liquid.

[0007]

[0008] ​The outer pile pipe is provided with a plurality of holes at intervals on the pipe wall; the holes below the station structure bottom plate are blocked by deformation sheets; the deformation sheets have plastic deformation capacity; and the melting point of the deformation sheets is lower than the pouring temperature of the outer hot melt liquid.

[0009] In a preferred embodiment, the anti-floating and anti-seismic structure further comprises a concrete bottom seal; and the concrete bottom seal covers the counterweight.

[0010] In a preferred embodiment, the inner pile pipe is sealed at the bottom and the bottom is not lower than the bottom of the outer pile pipe.

[0011] In a preferred embodiment, the top seal plate is arranged at the top of the double-layer gravity poured pile.

[0012] In a preferred embodiment, the deformation sheet is made of an alloy material.

[0013] In a preferred embodiment, the density of the inner hot melt liquid and the outer hot melt liquid is not less than 2.5 tons per cubic meter.

[0014] In a preferred embodiment, the holes are distributed at equal intervals in the height direction of the outer pile pipe.

[0015] The application also provides a construction method of a subway anti-floating and anti-seismic structure, which is used for constructing the double-layer gravity poured pile subway anti-floating and anti-seismic structure described above. The construction method comprises the following steps:

[0016] Step 1: reserving a construction hole at the designed pile position of the station structure bottom plate; and drilling a pile hole below the construction hole;

[0017] Step 2: hoisting the prefabricated double-layer gravity poured pile into the pile hole;

[0018] Step 3: pouring the inner hot melt liquid into the inner pile pipe and allowing it to solidify;

[0019] Step 4: opening the top seal plate and pouring the outer hot melt liquid into the outer pile pipe until the top of the pile;

[0020] Step 5: pouring the counterweight at the top of the double-layer gravity poured pile.

[0021] In a preferred embodiment, the construction method further comprises the following steps:

[0022] Step 6: pouring the concrete bottom seal to cover the counterweight.

[0023] In a preferred embodiment, the step 5 is specifically: continuously pouring the outer hot melt liquid until the outer hot melt liquid fills the outer pile pipe and extends upward, and the counterweight is poured at the top of the station structure bottom plate through the construction hole.

[0024] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0025] The anti-floating and earthquake-resistant structure and construction method provided by the present invention provide an efficient and stable anti-floating solution for subway stations by integrating the dual mechanisms of deep mechanical anchoring and gravity counterweight. Its advantages are specifically manifested as follows: (1) High-expansion gas pushes the deformation plate to form a plastic convex structure; the outer layer of hot melt melts the deformation plate and then overflows and solidifies to form a three-dimensional escape structure rigidly connected to the pile body. The two together form a deep anchoring network, embedded in the stratum to produce strong mechanical bite, significantly improving the lateral friction resistance and pull-out bearing capacity of the pile body, and at the same time improving the integrity of the station structure and the stratum. (2) The high-weight hot melt poured into the inner and outer pile pipes contributes to the main pile mass, and cooperates with the additional vertical load provided by the pile top counterweight block to effectively balance the buoyancy of groundwater and enhance the overall anti-floating stability of the structure. (3) The step-by-step pouring process uses heat to pre-evaporate the moisture around the pile, avoiding the risk of boiling of the outer layer of hot melt when it encounters water, and promoting its full diffusion in the dry soil layer, which is conducive to forming a larger-scale escape structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic cross-sectional view of the subway anti-floating and anti-seismic structure when pile hole drilling is completed in an embodiment of the present invention;

[0027] Figure 2 Schematic cross-section of the subway anti-floating and anti-seismic structure when the double-layer gravity cast-in-place piles are installed in the pile holes according to an embodiment of the present invention;

[0028] Figure 3 This is a cross-sectional schematic diagram of the subway anti-floating and earthquake-resistant structure according to an embodiment of the present invention when construction is completed;

[0029] Figure 4 A partial top view schematic diagram (i.e., an AA perspective schematic diagram) of the subway anti-floating and earthquake-resistant structure according to an embodiment of the present invention after construction is completed;

[0030] Figure 5 Schematic cross-section diagram of a double-layer gravity bored pile at different construction stages according to an embodiment of the present invention, wherein: Figure 5 A is a schematic diagram after installation in the pile hole. Figure 5 B is a schematic diagram after pouring the inner layer of hot melt. Figure 5 C is a schematic diagram after pouring the outer layer of hot melt.

[0031] Markings in the figure are: 1-station structure base plate, 2-construction hole, 3-pile hole, 4-double-layer gravity cast-in-place pile, 41-inner pile tube, 42-outer pile tube, 43-capping plate, 44-high expansion gas, 45-deformation plate, 46-external convex structure, 47-inner layer hot melt liquid, 48-outer layer hot melt liquid, 49-escape structure, 5-counterweight block, 6-concrete bottom seal. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0033] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom end" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "provided with", "sleeved / connected", "connected" and the like should be understood broadly, for example, "connected" can be wall-mounted connection, can be detachable connection, or integral connection, can be mechanical connection, can be electrical connection, can be direct connection, can be indirect connection through an intermediate medium, can be internal communication of two elements, and for a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0035] As shown in Figures 1-5 The embodiment of the present application provides a subway anti-floating and anti-seismic structure adopting double-layer gravity poured piles. The anti-floating and anti-seismic structure comprises a station structure bottom plate 1, double-layer gravity poured piles 4 and counterweights 5. Overall, the station structure bottom plate 1 is provided with a plurality of construction holes 2 penetrating through in the thickness direction to provide a passage for subsequent pile foundation construction. A plurality of pile holes 3 are drilled below the construction holes 2 by pre-hole technology, and the double-layer gravity poured piles 4 are installed in the pile holes 3. The counterweights 5 are arranged on the top of the double-layer gravity poured piles 4. The outer side and top of the counterweights 5 are covered with concrete bottom sealing 6.

[0036] As shown in Figure 5As shown, the double-layer gravity poured pile 4 comprises an inner pile tube 41, an outer pile tube 42 and a top sealing plate 43. The inner pile tube 41 is sleeved in the outer pile tube 42 to form a double-layer space. Preferably, the bottom of the inner pile tube 41 is sealed and is not lower than the bottom of the outer pile tube 42. Further, in this embodiment, the bottom of the inner pile tube 41 is higher than the bottom of the outer pile tube 42. The top sealing plate 43 is arranged between the outer pile tube 42 and the inner pile tube 41 to seal the space between the inner pile tube 41 and the outer pile tube 42 below the top sealing plate 43 into an independent cavity. Preferably, the top sealing plate 43 is arranged at the top of the double-layer gravity poured pile 4. As shown in Figure 5 As shown in A, before the pouring process of the double-layer gravity poured pile 4, the independent cavity is filled with high-expansion gas 44. In the pouring process, the inner layer hot melt liquid 47 is poured into the inner pile tube 41; the independent cavity is opened at the top and is poured with the outer layer hot melt liquid 48. Both of the hot melt liquids are high-density materials and form high-strength pile body after cooling and solidification. Preferably, the density of the inner layer hot melt liquid 47 and the outer layer hot melt liquid is not less than 2.5 tons per cubic meter.

[0037] The inner pile tube 41 and the outer pile tube 42 adopt smooth tube wall. Different from this, the tube wall of the outer pile tube 42 is provided with a plurality of holes. Preferably, the plurality of holes are arranged on the length section of the outer pile tube 42 below the station structure bottom plate 1. The "below" means below the bottom elevation of the station structure bottom plate 1. The holes are distributed equidistantly in the height direction of the outer pile tube 42. The double-layer gravity poured pile 4 further comprises a plurality of deformation pieces 45. The deformation pieces 45 are blocked on the holes and are tightly fixed with the tube wall of the outer pile tube 42. The deformation pieces 45 are arranged only on the outer pile tube 42 below the station structure bottom plate 1. The material of the deformation pieces 45 has good plastic deformation capacity and the melting point is lower than the pouring temperature of the outer layer hot melt liquid 48. Preferably, the deformation pieces 45 adopt alloy material.

[0038] As shown in Figure 5 As shown in B, in the pouring process, when the inner tube hot melt liquid is poured into the inner pile tube 41, the high-expansion gas 44 is heated and expanded to generate outward extrusion force, and at the same time, the deformation pieces 45 are heated to a certain extent through heat transfer to push the deformation pieces 45 to outward plastic deformation in the manner of "blow molding" to form the outward convex structure 46 of the deformation pieces 45 on the surface of the outer pile tube 42. As shown in Figure 5As shown in Fig. C, when the outer layer hot melt liquid 48 is poured into the outer pile tube 42, the outer layer hot melt liquid 48 fills the convex structure 46 and melts the deformation sheet 45 with a lower melting point. After the deformation sheet 45 is melted, the blocked hole is opened, and the high-temperature and high-flowability outer layer hot melt liquid 48 overflows and penetrates into the soil layer around the pile. The overflowing outer layer hot melt liquid 48 cools and solidifies in the soil layer, and finally forms the escape structure 49 in a radial, dendritic or conical column shape.

[0039] As shown in Fig. C, when the outer layer hot melt liquid 48 is poured into the outer pile tube 42, the outer layer hot melt liquid 48 fills the convex structure 46 and melts the deformation sheet 45 with a lower melting point. After the deformation sheet 45 is melted, the blocked hole is opened, and the high-temperature and high-flowability outer layer hot melt liquid 48 overflows and penetrates into the soil layer around the pile. The overflowing outer layer hot melt liquid 48 cools and solidifies in the soil layer, and finally forms the escape structure 49 in a radial, dendritic or conical column shape. Figure 3 、 Figure 4 As shown in Fig. C, when the outer layer hot melt liquid 48 is poured into the outer pile tube 42, the outer layer hot melt liquid 48 fills the convex structure 46 and melts the deformation sheet 45 with a lower melting point. After the deformation sheet 45 is melted, the blocked hole is opened, and the high-temperature and high-flowability outer layer hot melt liquid 48 overflows and penetrates into the soil layer around the pile. The overflowing outer layer hot melt liquid 48 cools and solidifies in the soil layer, and finally forms the escape structure 49 in a radial, dendritic or conical column shape.

[0040] The embodiment also provides a construction method of a subway anti-floating and anti-seismic structure, which adopts the anti-floating and anti-seismic structure described above. The method specifically comprises the following steps:

[0041] Step 1: When the main structure of the subway station is built, a construction hole 2 is reserved at the designed pile position of the station structure bottom plate 1. The construction hole 2 is used to drill down the stratum to form a pile hole 3 which penetrates into the stable bearing stratum, as shown in Fig. A. Figure 1

[0042] Step 2: The prefabricated double-layer gravity cast-in-place pile 4 which has not been poured is hoisted and placed in the pile hole 3, as shown in Fig. B. Before hoisting, the connection reliability of the top sealing plate 43 and the deformation sheet 45 and the filling state of the high-expansion gas 44 should be inspected to meet the requirements. Figure 2

[0043] Step 3: The inner layer hot melt liquid 47 is poured into the inner pile tube 41 and is left to solidify. In this process, the high-temperature inner layer hot melt liquid 47 heats the high-expansion gas 44 in the closed space, and the high-expansion gas 44 “blows” the deformation sheet 45 by thermal expansion and heat transfer to form the convex structure 46.

[0044] Step 4: The outer pile tube 42 is removed to open the independent cavity between the outer pile tube 42 and the inner pile tube 41, and then the outer layer hot melt liquid 48 is poured into the outer pile tube 42 to the top of the pile. In the subsequent solidification process, the high-temperature outer layer hot melt liquid 48 slowly melts the deformation sheet 45 and penetrates and solidifies into the soil layer around the pile to form the escape structure 49.

[0045] ​​Step 5: continuously pouring the outer layer hot melt liquid 48 until the outer layer hot melt liquid 48 fills the outer pile pipe 42 and extends upward to form the counterweight 5 on the top of the station structure floor 1 through the construction hole 2. It can be understood that in another embodiment, the counterweight 5 can also be separately poured after the pouring of the double-layer gravity cast-in-place pile 4 is completed.

[0046] Step 6: after the outer layer hot melt liquid 48 and the counterweight 5 are solidified to a certain strength, the concrete sealing layer 6 is poured on the outer side and top surface of the counterweight 5.

[0047] In summary, the subway anti-floating and anti-seismic structure and the construction method provided by the embodiment of the present application provide a double anti-floating mechanism of deep mechanical anchoring and gravity counterweight, which provides an efficient and stable anti-floating solution for the subway station. The specific technical advantages are as follows: (1) the high-expansion gas 44 expands after being heated to push the deformed sheet 45 to form a plastic convex structure 46, thereby compacting the soil around the pile and improving the vertical limiting between the pile and the soil. The outer layer hot melt liquid 48 overflows and solidifies after melting the deformed sheet 45, forming an escape structure 49 rigidly connected with the double-layer cast-in-place pile. These three-dimensionally distributed anchoring bodies (convex structure 46, escape structure 49) are embedded in the stratum, producing a strong mechanical locking effect, thereby improving the lateral friction resistance and uplift bearing capacity of the double-layer gravity cast-in-place pile 4, providing core anchoring force for resisting upward floating, and also improving the integrity of the station structure and the stratum. (2) The high-density hot melt liquid poured into the inner and outer pile pipes 42 contributes to the main quality of the pile, and cooperates with the additional vertical load provided by the counterweight 5 on the top of the pile, effectively balancing the groundwater buoyancy and improving the anti-floating stability of the main structure of the station. (3) In addition, the step-by-step poured hot melt liquid evaporates the water around the pile using heat, not only preventing the outer layer hot melt liquid 48 from overflowing into the soil and boiling when encountering water, which brings construction risks, but also facilitating the outward diffusion of the outer layer hot melt liquid 48 in the relatively dry soil to form the largest possible escape structure 49.

[0048] The above is only the preferred specific embodiment of the present application, not the limitation of the patent range of the present application, and any technical equivalent transformation using the content of the present application is within the protection scope of the present application.

Claims

1. A subway anti-floating and earthquake-resistant structure using double-layer gravity-cast piles, comprising a station structure base plate, double-layer gravity-cast piles, and counterweights; the station structure base plate is provided with a plurality of construction holes extending through the thickness thereof; a plurality of pile holes are drilled below the construction holes; the double-layer gravity-cast piles are installed in the pile holes; and the counterweights are disposed on top of the double-layer gravity-cast piles; and the structure is characterized in that: The double-layer gravity cast-in-place pile comprises an inner pile tube, an outer pile tube and a capping plate; the inner pile tube is sleeved inside the outer pile tube to form a double-layer structure; the capping plate is arranged between the inner pile tube and the outer pile tube, and is used to enclose the space between the inner pile tube and the outer pile tube below the capping plate into an independent cavity; Before the pouring process of the double-layer gravity cast-in-place pile, the independent cavity is filled with high-expansion gas; during the pouring process, the inner pile tube is poured with inner layer hot melt liquid; the top of the independent cavity is opened and poured with outer layer hot melt liquid; A plurality of holes are arranged at intervals on the wall of the outer pile tube; the holes located below the station structure bottom plate are blocked with a deformation plate; the deformation plate has plastic deformation capability; the melting point of the deformation plate is lower than the pouring temperature of the outer layer hot melt.

2. The subway anti-floating and anti-seismic structure using double-layer gravity cast-in-place piles according to claim 1, characterized in that: It also includes a concrete bottom seal; the concrete bottom seal covers the counterweight block.

3. The subway anti-floating and anti-seismic structure using double-layer gravity cast-in-place piles according to claim 1 is characterized by: The bottom of the inner pile tube is sealed, and the bottom is not lower than the bottom of the outer pile tube.

4. The subway anti-floating and anti-seismic structure using double-layer gravity cast-in-place piles according to claim 1, characterized in that: The capping plate is arranged on the top of the double-layer gravity cast-in-place pile.

5. The subway anti-floating and anti-seismic structure using double-layer gravity cast-in-place piles according to claim 1 is characterized by: The deformation piece is made of alloy material.

6. The subway anti-floating and anti-seismic structure using double-layer gravity cast-in-place piles according to claim 1, characterized in that: The density of the inner layer hot melt and the outer layer hot melt is not less than 2.5 tons / cubic meter.

7. The subway anti-floating and anti-seismic structure using double-layer gravity cast-in-place piles according to claim 1, characterized in that: The holes are distributed at equal intervals in the height direction of the outer pile tube.

8. A construction method for a subway anti-floating and earthquake-resistant structure, for constructing a subway anti-floating and earthquake-resistant structure using double-layer gravity cast-in-place piles as claimed in any one of claims 1 to 7, characterized in that: include: Step 1: Reserve a construction hole at the designed pile position of the station structure base plate; drill and excavate a pile hole below the construction hole; Step 2: Hanging the prefabricated double-layer gravity cast-in-place pile into the pile hole; Step 3: Pour the inner layer of hot melt liquid into the inner pile tube and let it stand to solidify; Step 4: Open the capping plate and pour the outer layer of hot melt liquid into the outer pile tube to the pile top; Step 5: Casting the counterweight block on the top of the double-layer gravity cast-in-place pile.

9. The construction method of a subway anti-floating and earthquake-resistant structure according to claim 8, characterized in that: Also includes: Step 6: Pour concrete bottom seal to cover the counterweight.

10. The construction method of a subway anti-floating and earthquake-resistant structure according to claim 8, characterized in that: The step 5 specifically comprises: continuously pouring the outer layer of hot melt liquid until the outer layer of hot melt liquid fills the outer pile tube and extends upward, and pouring the counterweight block on the top of the station structure bottom plate through the construction hole.

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