A connection structure between raft and anti-pull anchor

Abstract

The present invention relates to a connection structure between a raft and an anti-pullout anchor rod, which is connected to the raft and the anti-pullout anchor rod through a stiffness coordination device, the stiffness coordination device comprises an upper connector, a lower connector, an elastic member and a limit assembly, the upper connector is located at the upper end of the lower connector, and the upper connector can move up and down relative to the lower connector, and the limit assembly limits the movement range of the upper connector; one end of the elastic member abuts the upper connector, and the other end of the elastic member abuts the lower connector; the upper connector is connected to the raft, and the lower connector is connected to the top of the anti-pullout anchor rod. The present invention can economically achieve the deformation coordination problem of the raft foundation and the anti-pullout anchor rod group, the vertical pressure can be evenly transmitted to the foundation soil layer, the anti-pullout anchor rod will not be damaged, and the anti-pullout anchor rod can also play its anti-floating role.

Description

Technical Field

[0001] The invention relates to the technical field of building foundation, and in particular to a connection structure of a raft plate and an anti-pulling anchor rod. Background Art

[0002] Raft foundation is a commonly used foundation form. When a building has a basement, the raft also serves as the basement floor. For vertical pressure, the raft and the foundation soil deformation are coordinated, and the requirements can be met through calculation and specification guidance.

[0003] However, basements generally have anti-floating requirements. In addition to solving the vertical pressure, anti-floating requirements must also be met. The usual practice is to cover the raft with anti-pullout anchors, such as Figure 1 As shown. By setting up the pull-out anchor rod, the vertical pressure and anti-floating problems are solved on the surface. In fact, because of the arrangement of the pull-out anchor rod, the base load will be borne more by the pull-out anchor rod, and the pull-out anchor rod is easy to be damaged. The principle is that the raft foundation is a natural foundation. The deadweight of the raft and the upper load transmitted are borne by the bearing soil layer, which is a surface load and is evenly distributed in the bearing soil layer. After the pull-out anchor rod is arranged, the stiffness of the pull-out anchor rod is greater than the foundation soil. It can be roughly understood as a pile raft foundation. The deadweight of the raft and the upper load transmitted are borne by the pull-out anchor rod, which is a point support load. The pull-out anchor rod bears a large vertical pressure. Unlike piles, the pull-out anchor rod has a small cross-section, generally about 150mm, and 1-2 steel bars are used as the anchor body. The advantage is that the process is simple and economical, but it cannot bear too much load and is easy to be damaged.

[0004] Therefore, it is necessary to adjust the vertical stiffness of the pull-out anchor rod and ensure its pull-out resistance to give full play to the economic rationality of the "raft natural foundation + pull-out anchor rod" foundation, rather than actually adjusting it to a pile raft foundation with higher economic cost. Summary of the invention

[0005] The purpose of the present invention is to provide a connection structure between a raft and an anti-pullout anchor rod, which can economically achieve the deformation coordination problem of the raft foundation and the anti-pullout anchor rod group, and the vertical pressure can be evenly transmitted to the foundation soil layer without damaging the anti-pullout anchor rod, and the anti-pullout anchor rod can also play its anti-floating role.

[0006] To achieve the above-mentioned purpose, the present invention discloses a connection structure between a raft and an anti-pull-out anchor, which connects the raft and the anti-pull-out anchor through a stiffness coordination device, the stiffness coordination device comprises an upper connector, a lower connector, an elastic member and a limit assembly, the upper connector is located at the upper end of the lower connector, and the upper connector can move up and down relative to the lower connector, and the limit assembly limits the movement range of the upper connector; one end of the elastic member abuts the upper connector, and the other end of the elastic member abuts the lower connector; the upper connector is connected to the raft, and the lower connector is connected to the top of the anti-pull-out anchor.

[0007] After the above arrangement, when the raft is subjected to vertical pressure, vertical deformation occurs. The upper connector is also subjected to pressure, the elastic member is compressed, and vertical deformation occurs together with the raft as a whole, that is, deformation stiffness coordination is achieved, and the vertical pressure on the raft can be evenly transmitted to the foundation soil layer, and the load will not be mainly borne by the pull-out anchor rod, that is, the vertical pressure on the pull-out anchor rod is very small, and the pull-out anchor rod will not be damaged due to the existence of the pull-out anchor rod group. When the raft is subjected to buoyancy, the buoyancy first offsets the vertical pressure. As the buoyancy increases, the deformation of the raft caused by the vertical pressure is restored, the upper connector moves up, and the elastic member is reset. If the buoyancy continues to increase, the lower connector will pull the upper connector due to the limit assembly, limiting the deformation of the raft, that is, the pull-out anchor rod plays a role. In addition, the above-mentioned stiffness coordination device has a simple structure and low preparation cost, and can economically achieve the deformation coordination problem of the raft foundation and the pull-out anchor rod group.

[0008] Preferably, the pull-out anchor has at least one anchor bar, and the upper end of at least one anchor bar extends out of the top surface of the pull-out anchor and is connected to the lower connector; the upper connector is connected to the raft through the anchor bar. After such arrangement, the pull-out anchor and the lower connector are stably connected, and the upper connector and the raft are stably connected, thereby ensuring that the stiffness coordination device can play its role.

[0009] Preferably, the upper connector is partially embedded in the raft. This arrangement can ensure a reliable connection between the stiffness coordination device and the raft.

[0010] Preferably, the upper connector is embedded in the raft to a depth of 50±20 mm.

[0011] Preferably, the position limiting assembly includes at least one pin and a long hole corresponding to the pin, the pin is arranged on the upper connecting body, the long hole is arranged on the lower connecting body, and the length direction of the long hole is the vertical direction, and the pin is inserted into the long hole. The position limiting assembly thus arranged has a simple structure and is easy to process and manufacture.

[0012] Preferably, the diameter of the pin is D (mm), the diameter of the long hole is D1 (mm), and the length of the long hole is L (mm), then: ; F=pA=kv; D1=D+2; L=max(v+10,2D1); Where, F is the vertical pressure on the pull-out anchor (kN); f v is the design value of the shear strength of the pin (steel) (kN / mm 2 ); p is the base pressure (kPa); A is the top surface area of ​​the upper connector (m 2); k is the elastic coefficient of the elastic part (kN / mm); v is the settlement of the foundation (mm), and the value of v is calculated based on the settlement deformation of the foundation.

[0013] Preferably, it also includes a graded sand and gravel cushion layer arranged below the stiffness coordination device, the area of ​​the graded sand and gravel cushion layer is not less than the cross-sectional area of ​​the stiffness coordination device, and a fence for limiting the diffusion of the graded sand and gravel cushion layer is arranged on the periphery of the graded sand and gravel cushion layer. The graded sand and gravel cushion layer has the function of filling the concave and leveling, and also has the function of coordinating the deformation of the cushion layer and coordinating the deformation of the upper connector by using the piercing principle.

[0014] Preferably, the thickness of the graded sand and gravel cushion layer is H, then H=max(100, v+50), v is the foundation settlement (mm), and the unit of the thickness H of the graded sand and gravel cushion layer is mm; the thickness of the enclosure is not less than 100 mm.

[0015] Preferably, the inner ring shape of the enclosure is adapted to the outer shape of the upper connector. Such a configuration can well stabilize the posture of the stiffness coordination device and ensure its stable and reliable use.

[0016] Preferably, the upper connector has a first cavity with an opening facing downward, the lower connector has a second cavity with an opening facing upward, and the upper end of the lower connector is inserted into the first cavity; one end of the elastic member abuts against the bottom of the first cavity, and the other end of the elastic member abuts against the bottom of the second cavity. With this arrangement, the first cavity and the second cavity can form a protective installation space for installing the elastic member, and can also guide the upper connector in the direction of movement.

[0017] Preferably, at least one sealing member is further included, and the sealing member seals the gap between the inner wall of the first cavity and the outer wall of the lower connector; the limiting assembly is placed in the first cavity and is located above the sealing member. The sealing member can prevent dirt or sand from entering the installation protection space, and foreign objects will not interfere with the limiting assembly and the elastic member, thereby ensuring the service life of the stiffness coordination device.

[0018] Preferably, the opening of the first cavity is a sharp opening. After such arrangement, when the upper connector receives vertical pressure, the sharp opening can penetrate into the graded sand and gravel cushion layer to avoid affecting the movement of the upper connector.

[0019] The present invention has the following beneficial effects: The present invention connects the raft and the anti-pulling anchor by setting a rigidity coordination device. When the raft is subjected to vertical pressure, vertical deformation occurs. The upper connector is also subjected to pressure, the elastic member is compressed, and vertical deformation occurs together with the raft as a whole, that is, deformation rigidity coordination is achieved, and the vertical pressure on the raft can be evenly transmitted to the foundation soil layer, and the load will not be mainly borne by the anti-pulling anchor. In other words, the vertical pressure on the anti-pulling anchor is very small, and the anti-pulling anchor will not be damaged due to the existence of the anti-pulling anchor group. When the raft is subjected to buoyancy, the buoyancy first offsets the vertical pressure. As the buoyancy increases, the deformation of the raft caused by the vertical pressure is restored, the upper connector moves up, and the elastic member is reset. If the buoyancy continues to increase, the lower connector will pull the upper connector due to the limit assembly, limiting the deformation of the raft, that is, the anti-pulling anchor plays a role. In addition, the rigidity coordination device is simple in structure and low in preparation cost, and can economically achieve the deformation coordination problem of the raft foundation and the anti-pulling anchor group. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the plan layout of the raft and anti-tension anchors.

[0021] Figure 2 It is a schematic diagram of the present invention.

[0022] Figure 3 Schematic diagram of the stiffness coordination device.

[0023] Figure 4 This is a bottom view of the upper connector.

[0024] Figure 5 A cross-sectional view of the upper connector.

[0025] Figure 6 A top view of the lower connector.

[0026] Figure 7 This is a cross-sectional view of the lower connector.

[0027] Figure 8 This is a connection diagram of the limit assembly.

[0028] Main component symbols: Raft 10, anchor bars 11; Pull-out anchor rod 20, anchor rod reinforcement body 21; Stiffness coordination device 30, upper connecting body 31, lower connecting body 32, elastic member 33, first cavity 34, second cavity 35, pin 36, long hole 37, sealing member 38, sharp opening 39; Graded sand and gravel cushion 41, enclosure 42; Foundation soil layer 50. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0030] like Figure 2-8 As shown, the present invention discloses a connection structure between a raft 10 and an anti-pullout anchor rod. Specifically, the raft 10 and the anti-pullout anchor rod 20 are connected through a stiffness coordination device 30. Generally speaking, a plurality of anti-pullout anchor rods 20 (often referred to as an anti-pullout anchor rod group) are arranged on the raft 10, and each anti-pullout anchor rod 20 corresponds to a stiffness coordination device 30.

[0031] The stiffness coordination device 30 includes an upper connector 31, a lower connector 32, an elastic member 33 and a limit assembly. The upper connector 31 is connected to the raft 10. Preferably, the upper connector 31 is connected to the raft 10 through anchor bars 11, and at least two anchor bars 11 can be provided. In addition, it is also required that the top of the upper connector 31 is partially embedded in the raft 10, and the depth of the upper connector 31 embedded in the raft 10 is preferably h=50±20mm. The pull-out anchor 20 has at least one anchor bar 21, and the upper end of at least one anchor bar 21 extends out of the top surface of the pull-out anchor 20 and is connected to the lower connector 32. The upper connector 31 is located directly above the lower connector 32, and has a first cavity 34 opening downward. At this time, the upper connector 31 can be regarded as a single-opening box. The upper end of the lower connector 32 is inserted into the first cavity 34. The cross-sectional shape of the first cavity 34 matches the outer shape of the lower connector 32. The upper connector 31 can move up and down relative to the lower connector 32. The setting of the first cavity 34 can play a role in movement guidance.

[0032] The limit assembly is used to limit the movement range of the upper connector 31. Specifically, the limit assembly includes at least one pin 36 and a long hole 37 corresponding to the pin 36. The pin 36 is arranged on the upper connector 31 and placed in the first cavity 34. The pin 36 is evenly distributed on the inner wall of the first cavity 34. The long hole 37 is arranged on the lower connector 32, and the length direction of the long hole 37 is the vertical direction. The long hole 37 can be an oblong hole. The pin 36 is inserted into the long hole 37, so that the upper connector 31 can be limited in its up and down movement range.

[0033] In this case, the elastic member 33 is a spring, and the lower connecting body 32 has a second cavity 35 with an opening facing upward, one end of the spring abuts against the bottom of the first cavity 34, and the other end of the spring abuts against the bottom of the second cavity 35. The second cavity 35 can provide sufficient installation space for the spring and also protect the spring.

[0034] Because the stiffness coordination device 30 is close to the foundation soil layer 50 and the graded sand and gravel cushion layer 41, in order to prevent soil or sand and gravel from entering the installation space and affecting the normal operation of the stiffness coordination device 30, a seal 38 is provided for sealing the gap between the inner wall of the first cavity 34 and the outer wall of the lower connector 32. At least one seal 38 is provided, and the seal 38 can be a sealing strip. The pin 36 and the long hole 37 are both located above the seal 38.

[0035] In addition, a graded gravel cushion layer 41 is provided under each stiffness coordination device 30, and the area of ​​the graded gravel cushion layer 41 is not less than the cross-sectional area of ​​the stiffness coordination device 30. A baffle 42 is provided on the periphery of the graded gravel cushion layer 41 to limit the diffusion of the graded gravel cushion layer 41. Preferably, the inner ring shape of the baffle 42 is adapted to the outer shape of the upper connector 31, so that the posture of the stiffness coordination device 30 can be well stabilized to ensure its stable and reliable use. The baffle 42 can be made of a brick membrane. In addition, the case also defines the thickness of the graded gravel cushion layer 41 as H (unit: mm), and it is recommended that H=max(100, v+50), where v is the foundation settlement (mm), and the value of v is calculated based on the foundation settlement deformation. That is, when v+50>100, H=v+50; and when v+50≤100, H=100mm. The thickness W of the baffle 42 is recommended to be not less than 100mm. The thickness of the graded gravel cushion layer 41 is H and the thickness of the enclosure 42 is W. The specific thickness can also be considered in combination with the construction interface requirements of the grouting of the anti-pullout anchor rod 20.

[0036] When the raft 10 is subjected to vertical pressure, vertical deformation occurs, the upper connector 31 is also subjected to pressure and moves downward, the elastic member 33 is compressed, and vertical deformation occurs together with the raft 10 as a whole. At this time, there is no rigid connection between the upper connector 31 and the lower connector 32, and the lower connector 32 is subjected to very little vertical pressure, that is, the vertical pressure on the pull-out anchor 20 is very small, so that deformation stiffness coordination is achieved, and the vertical pressure on the raft 10 can also be evenly transmitted to the foundation soil layer 50, and the load will not be mainly borne by the pull-out anchor 20. In this way, the raft 10 will not damage the pull-out anchor 20 due to the existence of the pull-out anchor 20 group. In order to prevent the graded gravel cushion 41 from interfering with the downward movement of the upper connector 31, the cavity opening of the first cavity 34 is designed as a sharp opening 39. In this way, the sharp opening 39 can penetrate into the graded gravel cushion 41. The penetration of the upper connector 31 is an important part of the deformation. The penetration depth is actually the foundation settlement. Generally, the settlement is designed to be 30 mm. The upper connector 31 is inserted a little and a little is left below, so the thickness H of the graded sand and gravel cushion layer 41 is about 100 mm.

[0037] When the raft 10 is acted upon by buoyancy, the buoyancy first offsets the vertical pressure. As the buoyancy increases, the deformation of the raft 10 caused by the vertical pressure is restored, the upper connector 31 moves upward, and the elastic member 33 is restored. If the buoyancy continues to increase, the lower connector 32 will pull the upper connector 31 due to the limiting assembly, limiting the deformation of the raft 10, that is, the anti-pullout anchor 20 takes effect.

[0038] In order to ensure that the stiffness coordination device 30 can play its role, the stiffness of the pin 36, the long hole 37 and the spring are designed as follows. Specifically, the diameter of the pin 36 is defined as D (unit: mm), the diameter of the long hole 37 is defined as D1 (unit: mm), and the length of the long hole 37 is defined as L (unit: mm). Then: ; F=pA=kv; D1=D+2; L=max(v+10, 2D1); that is, when v+10>2D1, L=v+10; and if v+10≤2D1, L=2D1. 2D1 represents twice the aperture D1 of the long hole 37.

[0039] Where, F is the vertical pressure on the pull-out anchor 20 (kN); f v is the design value of shear strength of pin 36 (steel) (kN / mm 2 p is the base pressure (kPa); A is the top surface area of ​​the upper connector 31 (m 2 ); k is the elastic coefficient of the elastic member 33 (kN / mm); v is the settlement of the foundation (mm), and the value of v is calculated based on the settlement deformation of the foundation.

[0040] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A connection structure between a raft and an anti-pulling anchor, characterized in that: The raft and the anti-pullout anchor are connected by a stiffness coordination device, which includes an upper connector, a lower connector, an elastic member and a limit assembly, wherein the upper connector is located at the upper end of the lower connector and can move up and down relative to the lower connector, and the limit assembly limits the movement range of the upper connector; one end of the elastic member abuts against the upper connector, and the other end of the elastic member abuts against the lower connector; the upper connector is connected to the raft, and the lower connector is connected to the top of the anti-pullout anchor; The limiting component includes at least one pin and a long hole corresponding to the pin, the pin is arranged on the upper connecting body, the long hole is arranged on the lower connecting body, and the length direction of the long hole is the vertical direction, and the pin is inserted into the long hole.

2. The connection structure between the raft and the anti-pulling anchor according to claim 1, characterized in that: The pull-out anchor has at least one anchor bar, and the upper end of at least one anchor bar extends out of the top surface of the pull-out anchor and is connected to the lower connector; the upper connector is connected to the raft through the anchor bar.

3. The connection structure between the raft and the anti-pulling anchor according to claim 1, characterized in that: The upper connector is partially embedded in the raft.

4. The connection structure between the raft and the anti-pulling anchor according to claim 3 is characterized in that: The upper connector is embedded in the raft plate to a depth of 50±20 mm.

5. The connection structure between the raft and the anti-pulling anchor according to claim 1, characterized in that: The pin diameter is D, the aperture of the long hole is D1, and the length of the long hole is L. The units of the pin diameter D, the aperture of the long hole D1, and the length of the long hole L are all mm, then: ； F=pA=kv; D1=D+2; L=max(v+10,2D1); Where, F is the vertical pressure on the pull-out anchor, in kN; f V is the design value of the shear strength of the pin, in kN / mm 2 ; p is the base pressure, in kPa; A is the top surface area of ​​the upper connector, in m 2 ; k is the elastic coefficient of the elastic part, the unit is kN / mm; v is the foundation settlement, the unit is mm.

6. The connection structure between the raft and the anti-pulling anchor according to claim 1, characterized in that: It also includes a graded sand and gravel cushion layer arranged below the stiffness coordination device, the area of ​​the graded sand and gravel cushion layer is not less than the cross-sectional area of ​​the stiffness coordination device, and a barrier is arranged on the periphery of the graded sand and gravel cushion layer for limiting the diffusion of the graded sand and gravel cushion layer.

7. The connection structure between the raft and the anti-pulling anchor according to claim 6, characterized in that: The thickness of the graded sand and gravel cushion layer is H, then H=max(100,v+50), v is the foundation settlement, the unit is mm, and the thickness H of the graded sand and gravel cushion layer is mm; the thickness of the enclosure is not less than 100mm.

8. The connection structure between the raft and the anti-pulling anchor according to claim 6, characterized in that: The inner circle shape of the enclosure is adapted to the outer shape of the upper connector.

9. The connection structure between the raft and the anti-pulling anchor according to claim 1 or 6, characterized in that: The upper connecting body has a first cavity opening downward, the lower connecting body has a second cavity opening upward, and the upper end of the lower connecting body is inserted into the first cavity; one end of the elastic member abuts against the bottom of the first cavity, and the other end of the elastic member abuts against the bottom of the second cavity.

10. The connection structure between the raft and the anti-pulling anchor according to claim 9, characterized in that: It also includes at least one sealing member, which seals the gap between the inner wall of the first cavity and the outer wall of the lower connector; the limiting component is placed in the first cavity and located above the sealing member; the cavity opening of the first cavity is a pointed opening.

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