An anti-floating structure and construction method using a base reinforcement body to implant prefabricated anchor rods

Abstract

The present invention provides an anti-floating structure and construction method using a base reinforcement body to implant prefabricated anchor rods, comprising a reinforcement body and a prefabricated anchor rod, wherein the reinforcement body is a cement mixing pile or a rotary jet pile; the prefabricated anchor rod comprises an anchor rod body and anchoring steel bars arranged inside the anchor rod body; the upper end portion of the anchoring steel bar extends out of the anchor rod body for connection with a foundation bottom plate; a stiffening piece is arranged on the outside of the anchor rod body for strengthening the connection strength with the reinforcement body, the foundation bottom plate and the reinforcement body are connected together by using the prefabricated anchor rod, the high strength of the base is fully utilized to improve and reinforce the soil body, and the base reinforcement body is effectively utilized to increase the anti-floating ability of the underground structure, and the structure is particularly suitable for anti-floating construction of underground structures with high water levels and bases covered with thick and soft strata.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and in particular relates to an anti-floating structure and a construction method using a base reinforcement body to implant prefabricated anchor rods. Background Art

[0002] Guided by the national policy of developing urbanization and urban underground space, the underground space of my country's large and medium-sized cities, especially those in the eastern coastal cities, has developed by leaps and bounds. Some engineering sites have high groundwater levels and deep soft soil layers at the bottom of the pit. The excavation deformation of deep foundation pits and the floating damage of underground structures continue to occur, and may even cause irreversible and irreparable damage. At present, the bottom soil reinforcement is generally used in engineering to control the deformation of the foundation pit, and the anti-pull piles are used to control the floating of the structure. The traditional construction method does not use the reinforced soil at the bottom of the pit to participate in the control of the anti-floating control of the structure, resulting in waste of resources, increased engineering costs and poor results. Summary of the invention

[0003] The present invention aims to improve the problems existing in the above-mentioned prior art, that is, an embodiment of the present invention provides a

[0004] In order to solve the above technical problems, an embodiment of the present invention provides an anti-floating structure using a base reinforcement body to implant prefabricated anchor rods, including a reinforcement body and a prefabricated anchor rod, wherein the reinforcement body is a soil structure for strengthening the bearing capacity and strength of the foundation, wherein:

[0005] The prefabricated anchor rod includes an anchor rod body and anchoring steel bars arranged inside the anchor rod body, wherein the anchor rod body is located inside the reinforcement body; the upper end portion of the anchoring steel bars extends out of the anchor rod body for connection with the foundation bottom plate; a stiffener is arranged on the outside of the anchor rod body for strengthening the connection strength with the reinforcement body.

[0006] Preferably, the reinforcement body is a cement mixing pile or a rotary jet grouting pile.

[0007] Preferably, the stiffener is a threaded groove arranged on the outside of the anchor body or at least one force-bearing plate arranged on the outside of the anchor body, and the cross-sectional size of the force-bearing plate is larger than the cross-sectional size of the anchor body.

[0008] Preferably, a guide body is provided at the upper end of the prefabricated anchor rod for wrapping and positioning the upper end of the anchor steel bar extending out of the anchor rod body, the prefabricated anchor rod body is concrete with a strength not less than C30, and the guide body is concrete or cement mortar with a strength less than C30.

[0009] Preferably, a water stop ring is provided on the portion of the upper end of the anchor steel bar extending out of the anchor rod body.

[0010] The present invention also discloses a construction method of an anti-floating structure using a base reinforcement body implanted into a prefabricated anchor rod, comprising the steps of:

[0011] Use jet grouting piles or cement mixing piles to reinforce the soft soil at the base;

[0012] Implanting a prefabricated anchor rod in the jet grouting pile or cement mixing pile;

[0013] After the foundation pit is dewatered, earthwork is excavated to the designed elevation;

[0014] During the construction of the foundation slab, the upper end of the anchoring steel bar extends out of the anchor rod body and extends into the interior of the foundation slab.

[0015] Preferably, the prefabricated anchor rod is made of reinforced concrete, the strength of the reinforced concrete is not less than C30, and a prefabricated guide body is provided at the upper end of the prefabricated anchor rod for wrapping and positioning the upper end of the anchor steel bar extending out of the anchor rod body, and the guide body is prefabricated with concrete or cement mortar with a strength lower than C30.

[0016] Preferably, a stiffener is prefabricated on the outer side of the prefabricated anchor rod body to enhance the connection strength with the reinforcement body.

[0017] Preferably, the guide body is removed before the foundation slab is constructed, and the angle and position of the upper end of the anchoring steel bar are adjusted.

[0018] Preferably, before the construction of the foundation slab, the construction of a cushion layer and a waterproof layer is also included, and during the construction process, waterproofing and anti-corrosion construction is performed on the portion of the anchor rod body extending out of the upper end of the anchor steel bar.

[0019] Beneficial effects of the present invention:

[0020] ① For base construction with high water level and deep and soft strata, prefabricated anchor rods are implanted in the base reinforcement of deep foundation pit, making full use of the high strength of the base to improve and reinforce the soil and increase the anti-floating ability of the underground structure;

[0021] ② By setting a force plate or a force block on the rod body of the prefabricated anchor rod, the contact area and friction resistance between the anchor rod and the reinforcement body are increased, thereby further improving the anti-floating ability of the anchor rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of an anti-floating structure using a base reinforcement body implanted with a prefabricated anchor rod according to an embodiment of the present invention;

[0023] Figure 2 It is a structural schematic diagram of another construction stage of an anti-floating structure using a base reinforcement body to implant prefabricated anchor rods according to an embodiment of the present invention;

[0024] In the figure:

[0025] 1. Implantation equipment 2. Clamp 3. Pile delivery device

[0026] 4. Guide body 5. Prefabricated anchor rod 6. Reinforcement body

[0027] 7. Earthwork above the pit bottom 8. Anchor steel bars 9. Water stop ring

[0028] 10. Base slab 11. Waterproof layer 12. Cushion layer DETAILED DESCRIPTION

[0029] The technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] In the description of the embodiments of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present invention.

[0031] For example, Figure 1 , Figure 2 As shown, an embodiment of the present invention provides an anti-floating structure using a base reinforcement body to implant a prefabricated anchor rod, comprising a reinforcement body and a prefabricated anchor rod, wherein:

[0032] The reinforcement body 6 is a cement mixing pile or a jet grouting pile. In some places near rivers or seas where the groundwater level is high and there is a highly compressed soft soil at the bottom of a deep foundation pit, it is very unfavorable for the deep horizontal displacement of the retaining structure of the foundation pit and the vertical displacement of the base. Usually, cement soil constructed by high-pressure jet grouting piles or three-axis mixing piles is used to reinforce the soft soil at the bottom of the pit. Generally speaking, the reinforcement depth is not less than 4m, and the pile position of the prefabricated anchor rod 5 can be deepened separately.

[0033] The prefabricated anchor rod 5 includes an anchor rod body and an anchoring steel bar 8 arranged inside the anchor rod body; the upper end of the anchoring steel bar 8 extends out of the anchor rod body for connection with the foundation bottom plate 10; a stiffener is arranged on the outside of the anchor rod body to strengthen the connection strength with the reinforcement body 6. The processing and manufacturing of the prefabricated anchor rod 5 is completed in the prefabrication yard. Preferably, the anchoring steel bar 8 is tied with steel bars with a diameter of not less than φ16. After the formwork is set up, concrete with a strength of not less than C30 is used for pouring. After pouring, maintenance is carried out. In a preferred solution, a guide body 4 is arranged at the upper end of the prefabricated anchor rod 5 for wrapping and positioning the upper end of the anchoring steel bar 8 extending out of the anchor rod body. The guide body 4 is poured with concrete or cement mortar with a strength lower than C30. The strength of the prefabricated anchor rod 5 can be discharged only after it reaches 75% of the design strength. Generally speaking, the diameter range of the prefabricated anchor rod 5 is φ200-φ400. The prefabricated anchor rod 5 of appropriate size is selected according to the actual needs of the site.

[0034] In a preferred embodiment, the stiffener is a thread groove disposed on the outside of the anchor body. Specifically, the inner wall of the template of the prefabricated anchor 5 is provided with a thread protrusion or a thread groove, and the outer surface of the prefabricated anchor 5 can have a corresponding thread, thereby increasing the contact area with the reinforcement body 6 and enhancing the pull-out resistance of the prefabricated anchor 5.

[0035] In a preferred embodiment, the stiffener is at least one force-bearing plate arranged outside the anchor body, and the cross-sectional size of the force-bearing plate is larger than the cross-sectional size of the anchor body. Specifically, the force-bearing plate is a protrusion arranged outside the anchor body, and its shape can be annular or a plurality of protrusions are arranged around the outside of the anchor body, and its function is to increase the contact area with the reinforcement body 6 and enhance the pull-out resistance of the prefabricated anchor 5.

[0036] Preferably, a water stop ring 9 is arranged on the part of the anchor rod body extending from the upper end of the anchor steel bar 8. Specifically, the water stop ring is a water stop rubber ring that expands when exposed to water.

[0037] The present invention also discloses a construction method of an anti-floating structure using a base reinforcement body implanted into a prefabricated anchor rod, comprising the steps of:

[0038] Use jet grouting piles or cement mixing piles to reinforce the soft soil at the base;

[0039] Prefabricated anchor rods 5 are implanted in rotary jet piles or cement mixing piles; specifically, the prefabricated anchor rods 5 are first watered or coated with an interface agent before implantation, so that the anchor rods and the reinforcement body 6 are better combined to increase the friction resistance. When the requirements of the anchor rod implantation working surface are met (before the cement soil of the rotary jet pile or cement mixing pile is initially set), the anchor rods are implanted immediately. The prefabricated anchor rods 5 are first inserted into the pile hole, and the guide body 4 at the top of the prefabricated anchor rods 5 is temporarily fixed. The guide body 4 is inserted into the round tube pile driver 3, and the temporary fixing device is removed. The pile driver 3 sinks the prefabricated anchor rod 5 to the designed depth. Preferably, an implantation device 1 is added to the upper part of the pile driver 3 to assist in vibration to make it sink when the resistance is large. The implantation device 1 is a vibration device used to assist the pile driver 3 in pile sinking operations. The implantation device 1 and the pile driver 3 are both prior art, and no specific structural description is given here.

[0040] After the foundation pit is dewatered, earth excavation is carried out to the designed elevation; specifically, after the foundation pit meets the excavation conditions, excavation of earth 7 above the pit bottom is carried out in accordance with the requirements of the foundation pit excavation plan.

[0041] The foundation slab is constructed, and the upper end of the anchoring steel bar 8 extends out of the anchor rod body and extends into the foundation slab 10. Specifically, the mortar or concrete of the guide body 4 is chiseled, the design top elevation of the prefabricated anchor rod 5 is measured and the circumferential marking is done, the circumferential cutting is done, the mortar or concrete is removed, the position and angle of the anchoring steel bar 8 are adjusted according to the design requirements, and the prefabricated anchor rod 5 is subjected to relevant tests, inspections and acceptance. Then the foundation slab 10 is constructed. Before the reinforcement of the foundation slab 10 is tied, the water stop ring 9 is inserted into the anchoring steel bar 8, and then the reinforcement tying, formwork installation and concrete pouring operations of the foundation slab 10 are carried out.

[0042] Preferably, the prefabricated anchor rod 5 is made of reinforced concrete, and the strength of the reinforced concrete is not less than C30. The prefabricated guide body 4 at the upper end of the prefabricated anchor rod 5 is used to wrap and position the upper end of the anchor steel bar 8 extending out of the anchor rod body. The guide body 4 is prefabricated with concrete or cement mortar with a strength lower than C30.

[0043] Preferably, a stiffener is prefabricated on the outer side of the prefabricated anchor rod 5 body to enhance the connection strength with the reinforcement body 6 .

[0044] Preferably, before the construction of the foundation slab 10, the cushion layer 12 and the waterproof layer 11 are also constructed. During the construction process, the portion of the anchor rod body extending out of the upper end of the anchor steel bar 8 is waterproofed and anti-corroded.

[0045] Through the above technical scheme, the foundation slab 10 is connected to the reinforcement body 6 by using prefabricated anchor rods 5, the high strength of the base is fully utilized to improve the reinforced soil 6, and the base reinforcement body 6 is effectively utilized to increase the anti-floating ability of the underground structure. It is particularly suitable for anti-floating construction of underground structures with high water levels and bases covered with thick and soft strata.

[0046] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of application of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A construction method for an anti-floating structure using a base reinforcement body implanted with a prefabricated anchor rod, characterized in that: The anti-floating structure includes a reinforcement body and prefabricated anchor rods. The reinforcement body is a soil structure that strengthens the bearing capacity and strength of the foundation. The prefabricated anchor rod comprises an anchor rod body and an anchoring steel bar arranged inside the anchor rod body, wherein the anchor rod body is located inside the reinforcement body; the upper end portion of the anchoring steel bar extends out of the anchor rod body for connection with the foundation bottom plate; a stiffener is arranged outside the anchor rod body for strengthening the connection strength with the reinforcement body; a guide body is arranged at the upper end of the prefabricated anchor rod for wrapping and positioning the upper end of the anchoring steel bar extending out of the anchor rod body, the prefabricated anchor rod body is concrete with a strength not less than C30, and the guide body is concrete or cement mortar with a strength less than C30; The construction method includes the following steps: A prefabricated anchor rod is implanted in the reinforcement body, and the prefabricated anchor rod is made of reinforced concrete. The guide body is arranged at the upper end of the prefabricated anchor rod to wrap and position the upper end of the anchor steel bar extending out of the anchor rod body, and the guide body is prefabricated with concrete or cement mortar with a strength lower than C30; After the foundation pit is dewatered, earthwork is excavated to the designed elevation; During the construction of the foundation slab, the upper end of the anchoring steel bar extends out of the anchor rod body and extends into the foundation slab. Before the construction of the foundation slab, the guide body is removed and the angle and position of the upper end of the anchoring steel bar are adjusted.

2. The construction method of the anti-floating structure using a base reinforcement body implanted with a prefabricated anchor rod according to claim 1, characterized in that: The reinforcement body is a cement mixing pile or a rotary jet grouting pile.

3. The construction method of the anti-floating structure using a base reinforcement body implanted with a prefabricated anchor rod according to claim 1, characterized in that: The stiffener is a threaded groove arranged on the outside of the anchor body or at least one force-bearing plate arranged on the outside of the anchor body, and the cross-sectional size of the force-bearing plate is larger than the cross-sectional size of the anchor body.

4. The construction method of the anti-floating structure using a base reinforcement body implanted with a prefabricated anchor rod according to claim 1, characterized in that: A water stop ring is arranged on the portion of the anchor steel bar upper end extending out of the anchor rod body.

5. The construction method of the anti-floating structure using a base reinforcement body implanted with a prefabricated anchor rod according to claim 1, characterized in that: Before the construction of the foundation slab, the cushion layer and the waterproof layer are also constructed. During the construction process, waterproofing and anti-corrosion construction is performed on the part of the anchor rod body extending from the upper end of the anchor steel bar.

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