Reinforcement device for foundation

Abstract

The present invention discloses a reinforcement device for foundation, characterized in that it comprises at least one first reinforcement section and at least one second reinforcement section, wherein the first reinforcement section comprises a first pipe made of metal and a screw blade arranged on the outer peripheral wall of the first pipe, and the second reinforcement section comprises a second pipe made of metal, wherein the first pipe and the second pipe have the same pipe diameter, and adjacent first pipes and second pipes and adjacent second pipes are threadedly connected. By adopting the form of metal threaded piles and threaded connection between each component, it has the functions of reinforcement and anti-sinking of soft soil foundation with insufficient bearing capacity and anti-floating of structures (buildings) at high water level, and can be screwed and sunk into the soil layer in a narrow space for construction. The component is light and the pile connection is convenient. It is a "metal threaded pile" with both pressure-bearing and anti-pulling properties, with high construction efficiency, and is suitable for construction in subway tunnels.

Description

Technical Field

[0001] The invention relates to civil engineering, in particular to a reinforcement device for foundation used as a pile foundation. Background Art

[0002] The subway tunnel constructed by shield-driven pipe hanging in deep soft soil is suspended on the silty clay foundation. According to the "Metro Design Code" GB50157-2003, the bearing capacity of the foundation soil of the subway foundation must be ≥1.2MPa. Ten years later, the code was revised to GB50157-2013, and the bearing capacity of the foundation soil is ≥1.5MPa, which is 20% higher. The bearing capacity of the foundation of silt or silty soft soil in Ningbo, Wenzhou, Fuzhou, etc. is 0.45MPa~0.55MPa, and the bearing capacity of the foundation of silt soft soil in Shanghai and Tianjin is 0.6MPa~0.7MPa, which is much lower than the bearing capacity of the subway foundation soil required by the code. Direct application without foundation treatment has low bearing capacity of the foundation soil, and the soil is highly compressible soil with large settlement deformation. To ensure the safe operation of the subway, we must first ensure the flatness of the running train line, increase the deformation measurement of the roadbed, and adjust the flatness of the running line in time. The bearing capacity of the subway subgrade is limited by the compressibility of the soil and the flatness of the running track. In order to ensure the safety of subway operation, it is necessary to study and prepare effective measures to reinforce the subway tunnel subgrade soil as soon as possible.

[0003] According to the "Metro Design Specifications", the only measure for the roadbed in operation is grouting reinforcement. Whether the injected slurry can enter the voids of the foundation soil is the basis for determining the reinforcement effect. The silty soft soil in Shanghai, Tianjin, etc. is sandwiched with countless thin layers of fine sand, which are in a state of thousands of layers. The injected slurry can enter the voids of the fine sand and has a certain reinforcement effect. However, the deep silt or silty soft soil in Ningbo, Wenzhou, and Fuzhou is extremely fine soil particles (finer than cement particles), and the surface is bare with electrostatic water film. The injected slurry cannot enter the voids of the soil at all. Under the grouting pressure, a channel is torn open to accumulate cement slurry, disturbing the foundation soil and causing new settlement. The more the injection amount, the greater the accumulation amount, the more serious the disturbance, and the greater the settlement amount.

[0004] The reinforcement method for the subway tunnel subgrade in operation can be carried out with the help of the foundation reinforcement and underpinning of "existing buildings" that can be constructed in a small space. The commonly used technology is "static anchor piles". Based on the structural deadweight of the building as the reaction force, prefabricated reinforced concrete small square piles are statically pressed into the soil layer with hydraulic jacks, and the piles are used to underpin (support) part of the deadweight of the structure, so that the deadweight pressure acting on the foundation soil is reduced, and the allowable bearing capacity and settlement deformation requirements of the foundation soil are met.

[0005] For subway tunnels in operation, reinforcement treatment can only be applied during a very short period of non-operation in the middle of the night, such as using "static pressure anchor piles" of small square reinforced concrete piles. However, small square reinforced concrete piles are heavy, inconvenient to carry, have low pile connection efficiency, and slow pile sinking speed. In particular, the operation of the subway causes vibration and liquefaction of the soil around the tunnel wall, which creates buoyancy on the tunnel body. This must be balanced by pull-out piles, but "static pressure anchor piles" of small square reinforced concrete piles cannot be pull-out piles. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a reinforcement device for foundation with improved pressure bearing and pull-out resistance properties in view of the problems existing in the above-mentioned prior art.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a reinforcement device for a foundation, characterized in that it includes at least one first reinforcement section and at least one second reinforcement section, the first reinforcement section includes a first pipe fitting made of metal and screw blades arranged on the outer peripheral wall of the first pipe fitting, the second reinforcement section includes a second pipe fitting made of metal, the first pipe fitting and the second pipe fitting have the same pipe diameter, and adjacent first pipe fittings and second pipe fittings and adjacent two second pipe fittings are threadedly connected.

[0008] Preferably, the first pipe member and the second pipe member are respectively made of steel.

[0009] Preferably, the screw blades are welded to the outer peripheral wall of the first pipe.

[0010] To facilitate the formation of a threaded connection, each first pipe fitting has an axially opposite first end and a second end, the outer periphery of the second end of the first pipe fitting is sleeved with a first sleeve having an internal thread, and the outer periphery of the first end of the first pipe fitting is formed with an external thread that matches the first sleeve; each second pipe fitting has an axially opposite first end and a second end, the outer periphery of the second end of the second pipe fitting is sleeved with a second sleeve having an internal thread, and the outer periphery of the first end of the second pipe fitting is formed with an external thread that matches the second sleeve, thereby enabling threaded connections between adjacent first pipe fittings and second pipe fittings, and between two adjacent second pipe fittings.

[0011] To facilitate the matching between the pipe fittings, a first notch recessed toward the second end is formed in the middle of the first end of the first pipe fitting, and a first protrusion protruding away from the first end is formed at the second end of the first pipe fitting; a second notch recessed toward the second end is formed in the middle of the first end of the second pipe fitting, and a second protrusion protruding away from the first end is formed at the second end of the second pipe fitting, and the first notch and the second notch can both match with the first protrusion or the second protrusion.

[0012] According to one aspect of the present invention, each notch is plug-fitted into the protrusion.

[0013] According to another aspect of the present invention, in order to strengthen the connection between the pipes and increase the pull-out resistance, each notch and protrusion are threadedly matched.

[0014] To facilitate screwing of the pipe, a first pair of through holes is formed at a position of the first pipe close to the first end, and a second pair of through holes is formed at a position of the second pipe close to the first end.

[0015] Compared with the prior art, the advantages of the present invention are: by adopting the form of metal threaded piles and the threaded connection between the components, it has the functions of reinforcing and stopping the sinking of soft soil foundations with insufficient bearing capacity and preventing the floating of structures (buildings) at high water levels. It can be screwed and sunk into the soil layer for construction in a narrow space. The components are light and the piles are easy to connect. It is a "metal threaded pile" with both pressure-bearing and pull-out resistance properties, has high construction efficiency, and is suitable for construction in subway tunnels. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a reinforcement device according to an embodiment of the present invention;

[0017] Figure 2 It is a structural schematic diagram of a first reinforcement section of a reinforcement device according to an embodiment of the present invention;

[0018] Figure 3 It is a structural schematic diagram of a second reinforcement section of a reinforcement device according to an embodiment of the present invention;

[0019] Figure 4 It is a schematic diagram of the installation of the reinforcement device according to an embodiment of the present invention;

[0020] Figure 5 This is a schematic diagram of a reinforcement device according to an embodiment of the present invention applied to a subway tunnel. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below with reference to the accompanying drawings.

[0022] See also Figure 1 to Figure 3 A reinforcement device 100 for foundation includes a first reinforcement section 1 and a second reinforcement section 2 connected to each other. The reinforcement device has the dual functions of compression resistance and pull-out resistance, and is applied to the subway tunnel foundation of existing buildings (structures), so as to achieve the requirements of foundation bearing pressure and building (structure) anti-floating, and can meet the requirements of foundation strength and deformation.

[0023] The first reinforcement section 1 includes a first pipe fitting 11 and a screw blade 12. The first pipe fitting 11 can be made of metal, such as steel. The screw blade 12 is welded to the outer peripheral wall of the first pipe fitting 11, so that the two constitute the first reinforcement section 1 in the form of a threaded steel pipe. The second reinforcement section 2 includes a second pipe fitting 21, which can be made of metal, such as steel. The pipe diameters of each first pipe fitting 11 and each second pipe fitting 21 are the same, and the pipe diameters of the first pipe fitting 11 and the second pipe fitting 21 are also the same. The combination of the first reinforcement section 1 and the second reinforcement section 2 is selected according to the different stratum distribution. The first reinforcement section 1 is selected for hard soil strata, and the second reinforcement section 2 is selected for soft soil strata (the effect of the screw blade in the soft soil layer is not as good as in the hard soil layer, and the first reinforcement section 1 with the screw blade can also be set in the soft soil layer); the combination of the first reinforcement section 1 and the second reinforcement section 2 is selected according to the geological conditions. As shown in Table 1 below:

[0024] Table 1 Combination of reinforcement devices

[0025] Soil layer Hard soil Soft soil Hard soil Soft soil Soft soil Combination A First reinforcement section 1 Second reinforcement section 2 Second reinforcement section 2 Second reinforcement section 2 Combination B First reinforcement section 1 Second reinforcement section 2 First reinforcement section 1 Second reinforcement section 2 Second reinforcement section 2

[0026] like Figure 1 As shown, the first reinforcement section 1 is arranged at the bottom so that ≥ 4 screw blades are screwed into the hard soil layer; when the thickness of the thin hard soil layer in the middle stratum is greater than 2 screw blades 12, the first reinforcement section 1 may not be arranged in this layer, see combination A.

[0027] The reinforcement device 100 also includes a pile shoe 3. In this embodiment, the bottom of the reinforcement device adopts a first reinforcement section 1, at least two second reinforcement sections 2 are connected above the first reinforcement section 1, and the bottom of the first reinforcement section 1 is connected to the pile shoe 3.

[0028] Each first pipe fitting 11 has a first end and a second end axially opposite to each other. A first notch 111 recessed toward the second end is formed in the middle of the first end of the first pipe fitting 11. A first pair of through holes 112 is formed near the first end of the first pipe fitting 11. A first protrusion 113 protruding away from the first end is formed at the second end of the first pipe fitting 11. A first sleeve 114 with an internal thread is sleeved on the outer periphery of the second end of the first pipe fitting 11. An external thread matching the first sleeve 114 is formed on the outer periphery of the first end of the first pipe fitting 11.

[0029] Correspondingly, each second pipe fitting 21 has a first end and a second end axially opposite to each other, the first end of the second pipe fitting 21 is formed with a second notch 211 recessed toward the second end, the second pipe fitting 21 is provided with a second pair of through holes 212 near the first end, the second end of the second pipe fitting 21 is formed with a second protrusion 213 protruding in a direction away from the first end, the second end of the second pipe fitting 21 is sleeved with a second sleeve 214 with an internal thread on its outer periphery, and the first end of the second pipe fitting 21 is formed with an external thread matching the second sleeve 214 on its outer periphery.

[0030] The notch of each pipe fitting can be matched with the protrusion of another pipe fitting, and the sleeve of each pipe fitting can be matched with the outer periphery of the notch of another pipe fitting. The notch and the protrusion can be plug-in matched or threaded matched, that is, the inner periphery of the notch has an internal thread, and the outer periphery of the protrusion has an external thread. Since the connection method of the first reinforcement section 1 and the second reinforcement section 2 is both threaded connection, and the outer periphery of the first reinforcement section 1 is provided with screw blades 12, the firmness of the connection and the friction with the soil layer can be greatly increased, thereby making the reinforcement device have good pull-out resistance.

[0031] See also Figure 4 During installation, insert the protrusion of one pipe into the notch of another pipe, then screw the sleeve part corresponding to the protrusion onto the outer periphery of the pipe end with the notch to close the interface, and so on, to complete the connection of the reinforcement device into a whole pile. The diameter of each pair of through holes is 50mm. When manual screwing is used, a Φ30mm steel pipe can be used to penetrate, and the force arm of screwing can be adjusted to screw the reinforcement device 100 into the soil layer.

[0032] See also Figure 2 and Figure 3 , the length of the first pipe 11 is L1, the pipe diameter is d, the outer diameter of the screw blade 12 after welding is D, the pitch of the screw blade 12 is S, the length of the second pipe 21 is L2, h is the height of the screw blade 12, L1 and L2 can be equal or unequal, the lengths of the first pipes 11 can be equal or unequal, the lengths of the second pipes 21 can be equal or unequal, and the sizes of the first reinforcement section 1 and the second reinforcement section 2 can be selected as the following standard parts (where L is the length of the first pipe or the second pipe):

[0033] Table 2 Pipe fittings size table for reinforcement device

[0034] model L(mm) S(mm) D(mm) d(mm) h(mm) Ⅰ 2700 350 300 180 60 Ⅱ 3000 400 350 200 70

[0035] The bearing capacity of the reinforcement device 100 is calculated as follows:

[0036] Ra=(∑f ai ×A i ×n+d×3.14×∑q s h i )β-------(1)

[0037] Among them, f ai is the characteristic bearing capacity of the i-th soil layer (KPa); A i is the net horizontal projection area of ​​the spiral blade on the i-th soil layer (m 2 ), which is related to the outer diameter D; q s h iis the total lateral friction of the reinforcement device on the i-th soil layer (KPa) (where qs is the lateral friction of the soil around the reinforcement device, qs i is the lateral friction of the soil around the reinforcement device in the i-th layer of soil, h i is the thickness of the i-th layer of soil); n is the number of screw blades entering the hard soil layer and the soft soil layer; β---correction factor of the bearing capacity value (β = measured value of the static load test pile / estimated value).

[0038] The following example is used for illustration. According to Table 2, the model of the size table of the main pipe of the reinforcement device is Type I. According to the geological soil layer in Table 1, since the reinforcement device passes through the soil layer except the end bearing layer which is hard soil, the rest are soft soil, so a combination A of 2 first reinforcement sections 1 + 2 second reinforcement sections 2 is selected. The calculation of the bearing capacity value of the reinforcement device selected above is shown in the following example:

[0039] According to the geological survey report, the bearing capacity characteristic value of the foundation soil: hard soil f a =200Kp a Soft soil a =50Kp a ; Side friction of soft soil qs = 5.5Kp a , the screw blades 12 of the first reinforcement section 1 are screwed into the hard soil layer with 5 blades and the soft soil layer with 9 blades. The limit value R of the static load test pile uk =220KN, A i =(0.3 2 ×3.14 / 4-0.18 2 ×3.14 / 4)=0.045m 2 .

[0040] Estimation formula for the bearing capacity of the reinforcement device (1)

[0041] Ra=(∑f ai ×A i ×n+d×3.14×∑q s h i )β

[0042] Ra=(0.045×5×200±0.045×9×50±0.18×3.14×5.5×2.7×2)β

[0043] =82KN×(110 / 82)

[0044] =110KN

[0045] The model of the corresponding reinforcement section can be selected according to the actual foundation bearing capacity and its requirements.

[0046] Since the subway tunnel is constructed by shield-driven pipe segment hanging, the pipe segments are connected by bolts to form a flexible tunnel body. Combined with the subway tunnel 200 that has been constructed in deep soft soil areas by shield-driven pipe segment hanging, a reinforced concrete semi-cylinder 300 with a thickness of ≥200mm is constructed by embedding reinforcement to make the flexible tunnel body a semi-circular rigid tunnel body. The reinforcement device 100 supports the semi-circular rigid tunnel body. When the tunnel has not yet been constructed, it is advisable to reserve pile holes for the reinforcement device 100 on the pipe segments. For subway tunnels that have been constructed and put into operation, pile holes must be drilled on the tunnel wall, and then a reinforced concrete semi-cylinder 300 with a thickness of ≥200mm is constructed. When used, the first pipe 11 and the second pipe 21 are filled with C30 fine stone concrete to make the reinforcement device a whole pile. The top of the pile is conventionally embedded in the existing building (structure) to complete the support and sinking prevention of the subway tunnel. See. Figure 5 The subway tunnel uses two reinforcement devices to support the weight of the tunnel. Because the reinforcement devices are piles with dual functions of compression and tension resistance, the connection between the piles and the existing buildings (structures) must also have structural strengths equivalent to compression and tension resistance.

[0047] The reinforcement device of the present invention has the functions of reinforcing and stopping the sinking of soft soil foundations with insufficient bearing capacity and preventing the floating of structures (buildings) at high water levels. It can be screwed and sunk into the soil layer for construction in a narrow space. The component is light and the pile connection is convenient. It is a "metal threaded pile" with both pressure-bearing and pull-out resistance properties, has high construction efficiency, and is suitable for construction in subway tunnels.

Claims

1. A reinforcement device for foundation, characterized in that: The invention comprises at least one first reinforcement section (1) and at least one second reinforcement section (2), wherein the first reinforcement section (1) comprises a first pipe member (11) made of metal and a screw blade (12) arranged on the outer peripheral wall of the first pipe member (11), and the second reinforcement section (2) comprises a second pipe member (21) made of metal, and the first pipe member (11) and the second pipe member (21) have the same pipe diameter; Each first pipe member (11) has a first end and a second end opposite to each other in the axial direction, a first sleeve (114) having an internal thread is sleeved on the outer periphery of the second end of the first pipe member (11), and an external thread matching the first sleeve (114) is formed on the outer periphery of the first end of the first pipe member (11); each second pipe member (21) has a first end and a second end opposite to each other in the axial direction, a second sleeve (214) having an internal thread is sleeved on the outer periphery of the second end of the second pipe member (21), and an external thread matching the second sleeve (214) is formed on the outer periphery of the first end of the second pipe member (21), thereby enabling adjacent first pipe members (11) and second pipe members (21), and adjacent two second pipe members (21) to be threadedly connected; A first notch (111) is formed in the middle of the first end of the first tube (11) and is recessed toward the second end, and a first protrusion (113) is formed at the second end of the first tube (11) and is protruding in a direction away from the first end; a second notch (211) is formed in the middle of the first end of the second tube (21) and is recessed toward the second end, and a second protrusion (213) is formed at the second end of the second tube (21) and is protruding in a direction away from the first end, and the first notch (111) and the second notch (211) can both cooperate with the first protrusion (113) or the second protrusion (213); The first pipe member (11) is provided with a first pair of through holes (112) at a position close to the first end, and the second pipe member (21) is provided with a second pair of through holes (212) at a position close to the first end.

2. The reinforcement device for foundation according to claim 1, characterized in that: The first pipe member (11) and the second pipe member (21) are respectively made of steel.

3. The reinforcement device for foundation according to claim 2, characterized in that: The screw blade (12) is welded to the outer peripheral wall of the first pipe (11).

4. The reinforcement device for foundation according to any one of claims 1 to 3, characterized in that: Each notch is plug-fitted with the protrusion.

5. The reinforcement device for foundation according to any one of claims 1 to 3, characterized in that: Each notch and protrusion are threadedly matched.

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