Construction method of grouting composite anchor rod system for anti-floating reinforcement of existing underground structure

Abstract

The application discloses a construction method of an anti-floating reinforcing grouting composite anchor rod system for an underground structure, and the composite anchor rod system comprises a plugging and leaking stopping sleeve arranged in a bottom plate, an anchor rod stem pipe arranged in the plugging and leaking stopping sleeve and extending into a soil body, cement slurry and a main stress bar arranged in the anchor rod stem pipe, and an anchor head locking assembly arranged at the top of the anchor rod stem pipe and fixing the main stress bar; the plugging and leaking stopping sleeve and a construction bottom concrete layer are jointly arranged, the anchor rod stem pipe at the bottom plate is positioned and protected, and the joint overall waterproofing can be performed; the main stress bar is arranged, a more reliable stress main body in the anchor rod stem pipe is formed, the anchor head locking assembly is arranged, the anchor head locking assembly is connected with the bottom plate, and the overall stress is facilitated; the static pressure equipment and the segmented construction are used, the construction in a small underground space is facilitated, the disturbance is small, and the segmented construction facilitates the guarantee of the grouting quality.

Description

Technical Field

[0001] This invention relates to the field of anti-buoyancy reinforcement technology for existing buildings, and particularly to a construction method for an anti-buoyancy reinforcement grouting composite anchor system for existing underground structures. Background Technology

[0002] With the acceleration of urban renewal, the underground spaces of many existing buildings need to be renovated and utilized. At the same time, due to the implementation of ecological water replenishment and groundwater extraction restrictions, the groundwater level in many existing building sites has risen significantly. The original underground structures were not adequately designed for buoyancy resistance during construction or the buoyancy resistance design water level was too low, resulting in huge risks of structural floating, foundation cracking, and even overall instability under the buoyancy of rising groundwater.

[0003] Traditional anti-buoyancy reinforcement methods, such as increasing weight (covering with soil or counterweight) and lowering the groundwater level, suffer from problems such as large construction volume, environmental impact, short-lasting effects, or policy restrictions. Another commonly used method is to install anti-buoyancy anchors, but conventional anti-buoyancy anchor construction methods face the following technical or environmental challenges when applied to the reinforcement of existing underground structures: Limited construction space: The work surface is usually located in an existing indoor space with limited space, making it difficult to deploy large equipment. When the groundwater level is higher than the foundation slab, long-term and large-area dewatering is required to ensure construction. However, dewatering affects the surrounding environment and can easily cause secondary disasters such as ground subsidence, deformation of underground pipelines, and building tilting. Furthermore, the dewatering cycle is long, difficult, and expensive.

[0004] Furthermore, the drilling or hammering techniques used in conventional anchor bolt construction can generate vibrations and pressures during construction, potentially causing secondary damage to the existing structure and resulting in low anchoring reliability. Therefore, there is an urgent need for a targeted, efficient, environmentally friendly, pollution-free, and reliable method for reinforcing existing underground structures against buoyancy. Summary of the Invention

[0005] This invention provides a construction method for an existing underground structure anti-buoyancy reinforcement grouting composite anchor system, which solves the technical problems of limited space, difficulty in construction in groundwater environment, and low connection reliability of existing anti-buoyancy anchors.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The existing underground structure anti-buoyancy reinforcement grouting composite anchor system includes a sealing and leak-stopping sleeve installed in the bottom slab, an anchor rod core tube installed in the sealing and leak-stopping sleeve and extending into the soil, cement grout and main reinforcing bars installed in the anchor rod core tube, and an anchor head locking assembly installed at the top of the anchor rod core tube and fixing the main reinforcing bars.

[0008] The specific steps for constructing an anti-buoyancy reinforcement grouting composite anchor system for existing underground structures are as follows:

[0009] Step 1: Remove obstacles from the existing building on the base slab; determine the drilling location according to the design drawings; when there is groundwater or confined water under the base slab and the groundwater head line is higher than the top elevation of the base slab, the drilling on the base slab will not be completed temporarily, and a 5cm~10cm bottom sealing concrete layer will be left to ensure that groundwater cannot seep in.

[0010] Step 2: Place a sealing and leak-proof sleeve in the opening of the base plate. The outer diameter of the sealing and leak-proof sleeve is the same as the opening diameter of the base plate, and the inner diameter corresponds to the outer diameter of the anchor rod core tube. Apply waterproof material between the outer wall of the sealing and leak-proof sleeve and the base plate to seal it.

[0011] Step 3: Install the static pressure equipment on the base plate, and press the anchor rod core tube into the stratum in sections through the sealing and leak-proof sleeve. Each section is connected with a sealing measure. The depth of pressing into the soil should meet the anchor design requirements. The bottom end of the first anchor rod section is a pointed tip. As the static pressure equipment is pressed in, the bottom sealing concrete layer is broken.

[0012] Step 4: Grouting is performed using a segmented grouting device. After grouting is completed on the outside of the anchor rod core tube, cement grout is added inside the anchor rod core tube. Before the grout inside the tube initially sets, the main reinforcing bar is inserted.

[0013] Step 5: After the strength of the grouting body in the anchor rod skeleton meets the requirements, the main reinforcing bar is tensioned and locked to the top surface of the bottom plate through the anchor head locking component, thereby completing the construction of the existing underground structure anti-buoyancy reinforcement grouting composite anchor system.

[0014] Furthermore, the base slab is a basement base slab, and the soil beneath the base slab contains groundwater; during the construction of the existing underground structure anti-buoyancy reinforcement grouting composite anchor system, the groundwater level rises and is higher than the top surface of the basement base slab, causing the existing building to float or the base slab to crack; wherein, the boreholes on the base slab have a diameter of 100mm~350mm.

[0015] Furthermore, the anchor rod core tube includes an anchor rod, an anchor hole disposed on the outer wall of the anchor rod, and an anchor head disposed at the bottom end of the anchor rod; the anchor head is a closed conical tip, and its hardness corresponds to the concrete layer and the soil to be broken and pressed in.

[0016] Furthermore, the anchor rod is tubular and the anchor rods are assembled and connected; during construction, each segment of the anchor rod is provided with corresponding anchor holes, and a one-way grouting valve is installed in the anchor holes; the splices are connected by threads or sleeves, and the joints are sealed with sealing rings or sealant.

[0017] Furthermore, the water-cement ratio of the cement grout is 0.4~0.7, and the cement grout is applied by pressure injection to keep the grout inside the anchor rod full and spread outwards.

[0018] Furthermore, the sealing and leak-stopping sleeve is an extruded and deformed sleeve, which is made of rubber or plastic tubing.

[0019] Furthermore, the anchor head locking assembly includes an anchor plate, an anchor pad plate disposed below the anchor plate, and an anchor head disposed on top of the anchor plate; the anchor plate is a circular plate with perforations for connecting the main load-bearing reinforcement; the anchor pad plate is a circular plate with a diameter larger than the outer diameter of the anchor rod core tube; and the anchor head is a compression anchor or a wedge anchor.

[0020] Furthermore, the static pressure equipment is a gantry-type static pressure equipment or a clamping static pressure equipment, and its height is lower than the height of the basement; its bottom is fixedly connected to the base plate by anchor bolts.

[0021] Furthermore, in step five, the main reinforcing bars are steel strands, ordinary steel bars, precision rolled threaded steel bars, or fiber-reinforced composite materials; the main reinforcing bars are set according to the working conditions of applying tension prestress or not applying prestress.

[0022] Furthermore, in step five, when a new thick base plate is added above the base plate, the anchor head locking assembly is installed inside the newly poured base plate.

[0023] The beneficial effects of this invention are reflected in:

[0024] 1) This invention, through the combined installation of a sealing and leak-proof sleeve and a bottom sealing concrete layer during construction, ensures that when the groundwater level is high, through drilling is not performed during the initial drilling. The sealing and leak-proof sleeve and the anchor rod core tube are then connected by a sleeve, which can both position and protect the anchor rod core tube at the bottom plate and achieve overall waterproofing. The one-way valve setting in the anchor hole also facilitates grouting and ensures waterproofing.

[0025] 2) The present invention, through the setting of the main load-bearing rib, facilitates the formation of a more reliable load-bearing body within the anchor rod skeleton tube, and through the setting of the anchor head locking component, it connects to the bottom plate, which facilitates the overall load-bearing.

[0026] 3) This invention, through static pressure equipment and segmented construction, not only facilitates construction in low underground spaces with minimal disturbance, but also helps ensure grouting quality through segmented construction.

[0027] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention; the main objects and other advantages of the invention may be realized and obtained by means of the embodiments particularly pointed out in the description. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the construction of an anti-buoyancy reinforcement grouting composite anchor system for existing underground structures;

[0029] Figure 2 This is a schematic diagram of the anchor rod core tube, anchor head locking assembly and its connection structure;

[0030] Figure 3 This is a schematic diagram of the cross-section of the anchor rod skeleton and the main load-bearing reinforcement;

[0031] Figure 4 This is a schematic diagram of drilling construction for existing underground structures;

[0032] Figure 5 This is a schematic diagram of the installation and construction of sealing and leak-proof sleeves for existing underground structures;

[0033] Figure 6 This is a schematic diagram of the construction of static pressure equipment in an existing underground structure;

[0034] Figure 7 This is a schematic diagram of the grouting construction of an existing underground structure;

[0035] Figure 8 This is a schematic diagram of the construction of the main load-bearing reinforcement of the existing underground structure;

[0036] Figure 9 This is a schematic diagram of the construction of the anchor locking components for existing underground structures.

[0037] Attached reference numerals: 1-Beam-column structure, 2-Base slab, 3-Soil, 4-Anchor rod core tube, 41-Main anchor rod, 42-Anchor hole, 43-Anchor head, 5-Cement grout, 6-Main reinforcing bar, 7-Sealing and leak-proof sleeve, 8-Anchor head locking assembly, 81-Anchor plate, 82-Anchor pad, 83-Anchor head, 9-Groundwater head line, 10-Drill hole, 11-Static pressure equipment, 12-Grouting pipe. Detailed Implementation

[0038] Taking the anti-buoyancy reinforcement of an existing building with a basement in an urban renewal project as an example, such as... Figures 1 to 9 As shown, the construction method of the existing underground structure anti-buoyancy reinforcement grouting composite anchor system includes a sealing and leak-proof sleeve 7 installed in the base plate 2, an anchor rod core tube 4 installed in the sealing and leak-proof sleeve 7 and extending into the soil 3, cement grout 5 and main reinforcing bars 6 installed in the anchor rod core tube 4, and an anchor head locking assembly 8 installed at the top of the anchor rod core tube 4 and fixing the main reinforcing bars 6.

[0039] The anchor rod tube 4 includes an anchor rod 41, an anchor hole 42 on the outer wall of the anchor rod 41, and an anchor head 43 at the bottom end of the anchor rod 41. The anchor head 43 is a closed conical tip and has relatively high hardness, so as to facilitate breaking the concrete layer and pressing it into the soil 3.

[0040] In this embodiment, the anchor rod 41 is tubular and the anchor rods 41 are assembled and connected. During construction, each section of the anchor rod 41 is provided with corresponding anchor bolt holes 42, and a one-way grouting valve is installed in the anchor bolt holes 42. The splices are connected by threads or sleeves, and the joints are sealed by sealing rings or sealant.

[0041] In this embodiment, the anchor head locking assembly 8 includes an anchor plate 81, an anchor pad 82 disposed below the anchor plate 81, and an anchor head 83 disposed on top of the anchor plate 81. The anchor plate 81 is a circular plate with perforations for connecting the main reinforcing bars 6. The anchor pad 82 is a circular plate with a diameter larger than the outer diameter of the anchor rod core tube 4. The anchor head 83 is a compression anchor or a wedge anchor. The static pressure device 11 is a gantry-type or clamping static pressure device 11, and its height is lower than the height of the basement. Its bottom is fixedly connected to the base plate 2 by anchor bolts.

[0042] Combination Figures 1 to 9 As shown, the construction method for the grouting composite anchor system for anti-buoyancy reinforcement of existing underground structures is further explained. The specific steps are as follows:

[0043] Step 1: Remove obstacles from the existing building on the base slab 2; determine the location of borehole 10 according to the design drawings; when there is unconfined or pressurized water under the base slab 2 and the groundwater head line 9 is higher than the top elevation of the base slab 2, the borehole 10 on the base slab 2 will not be drilled through temporarily, and a 5cm~10cm bottom sealing concrete layer will be left to ensure that groundwater cannot seep in.

[0044] In this embodiment, the existing building is a concrete building, which forms an integral frame through the beam and column structure 1; the base slab 2 is the basement base slab 2, and the soil 3 below the base slab 2 contains groundwater; during the construction of the existing underground structure anti-buoyancy reinforcement grouting composite anchor system, the groundwater rises and the water level is higher than the top surface of the base slab, causing the existing building to float or the base slab 2 to crack; wherein, the drill holes 10 on the base slab 2 have a diameter of 100mm~350mm.

[0045] Step 2: Place the sealing and leak-proof sleeve 7 into the opening in the base plate 2. The outer diameter of the sealing and leak-proof sleeve 7 is the same as the opening diameter in the base plate 2, and the inner diameter corresponds to the outer diameter of the anchor rod core tube 4. Apply waterproof material between the outer wall of the sealing and leak-proof sleeve 7 and the base plate 2 for sealing. The sealing and leak-proof sleeve 7 is a deformed extrusion sleeve, made of rubber or plastic tubing.

[0046] Step 3: Install the static pressure device 11 on the base plate 2, and press the anchor rod core tube 4 into the stratum in sections through the sealing and leak-proof sleeve 7. Each section is connected with a sealing measure. The depth of pressing into the soil should meet the anchor rod design requirements. The bottom end of the first section of the anchor rod is a pointed tip. As the static pressure device 11 is pressed in, the bottom sealing concrete layer is broken.

[0047] Step 4: Grouting is performed through grouting pipe 12 using a segmented grouting device. After grouting is completed on the outside of the anchor rod core tube 4, cement grout 5 is added inside the anchor rod core tube 4. Before the grout inside the tube initially sets, the main reinforcing bar 6 is inserted. The water-cement ratio of the cement grout 5 is 0.4~0.7. Pressure grouting is used during cement grouting to keep the grout inside the anchor rod 41 full and spread it to the surrounding area.

[0048] Step 5: After the grouting body of the anchor rod bone tube 4 meets the strength requirements, the main reinforcing bar 6 is tensioned and locked to the top surface of the bottom plate 2 by the anchor head locking component 8, thereby completing the construction of the existing underground structure anti-buoyancy reinforcement grouting composite anchor system.

[0049] In step five, the main reinforcing bars 6 are made of steel strands, ordinary steel bars, precision-rolled threaded steel bars, or fiber-reinforced composite materials; the main reinforcing bars 6 are set up according to the working conditions of applying tension prestress or not applying prestress. When a new thick base plate 2 is added above the base plate 2, the anchor head locking assembly 8 is set inside the newly poured base plate 2.

[0050] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A construction method for an existing underground structure anti-buoyancy reinforcement grouting composite anchor system, characterized in that, The existing underground structure anti-buoyancy reinforcement grouting composite anchor system includes a sealing and leak-stopping sleeve installed in the bottom slab, an anchor rod core tube installed in the sealing and leak-stopping sleeve and extending into the soil, cement grout and main reinforcing bars installed in the anchor rod core tube, and an anchor head locking assembly installed at the top of the anchor rod core tube and fixing the main reinforcing bars. The specific steps for constructing an anti-buoyancy reinforcement grouting composite anchor system for existing underground structures are as follows: Step 1: Remove obstacles from the existing building on the base slab; determine the drilling location according to the design drawings; when there is groundwater or confined water under the base slab and the groundwater head line is higher than the top elevation of the base slab, the drilling on the base slab will not be completed temporarily, and a 5cm~10cm bottom sealing concrete layer will be left to ensure that groundwater cannot seep in. The basement slab contains groundwater in the soil beneath it. During the construction of the existing underground structure anti-buoyancy reinforcement grouting composite anchor system, the groundwater level rises and exceeds the top surface of the base slab, causing the existing building to float or the base slab to crack. Step 2: Place a sealing and leak-proof sleeve in the opening of the base slab. The outer diameter of the sealing and leak-proof sleeve is the same as the opening diameter of the base slab, and the inner diameter corresponds to the outer diameter of the anchor rod core tube. Apply waterproof material between the outer wall of the sealing and leak-proof sleeve and the base slab to seal it. The sealing and leak-stopping sleeve is a deformed extrusion sleeve, which is made of rubber or plastic tubing. Step 3: Install the static pressure equipment on the base plate, and press the anchor rod core tube into the stratum in sections through the sealing and leak-proof sleeve. Each section is connected with a sealing measure. The depth of pressing into the soil should meet the anchor design requirements. The bottom end of the first anchor rod section is a pointed tip. As the static pressure equipment is pressed in, the bottom sealing concrete layer is broken. Step 4: Grouting is performed using a segmented grouting device. After grouting is completed on the outside of the anchor rod core tube, cement grout is added inside the anchor rod core tube. Before the grout inside the tube initially sets, the main reinforcing bar is inserted. Step 5: After the strength of the grouting body in the anchor rod skeleton meets the requirements, the main reinforcing bar is tensioned and locked to the top surface of the bottom plate through the anchor head locking component, thereby completing the construction of the existing underground structure anti-buoyancy reinforcement grouting composite anchor system.

2. The construction method of the existing underground structure anti-buoyancy reinforcement grouting composite anchor system as described in claim 1, characterized in that, The holes on the base plate have a diameter of 100mm to 350mm.

3. The construction method of the grouting composite anchor system for anti-buoyancy reinforcement of existing underground structures as described in claim 1, characterized in that, The anchor rod core tube includes an anchor rod, an anchor hole on the outer wall of the anchor rod, and an anchor head at the bottom end of the anchor rod; the anchor head is a closed conical tip, and its hardness corresponds to the concrete layer and the soil to be broken.

4. The construction method of the existing underground structure anti-buoyancy reinforcement grouting composite anchor system as described in claim 3, characterized in that, The anchor rod is tubular and assembled. During construction, each segment of the anchor rod is provided with corresponding anchor holes, and a one-way grouting valve is installed in the anchor holes. The joints are connected by threads or sleeves, and the joints are sealed with sealing rings or sealant.

5. The construction method of the existing underground structure anti-buoyancy reinforcement grouting composite anchor system as described in claim 4, characterized in that, The water-cement ratio of the cement grout is 0.4~0.

7. The cement grout is applied by pressure injection to keep the grout inside the anchor rod full and spread it to the surrounding area.

6. The construction method of the existing underground structure anti-buoyancy reinforcement grouting composite anchor system as described in claim 1, characterized in that, The anchor head locking assembly includes an anchor plate, an anchor pad plate disposed below the anchor plate, and an anchor head disposed on top of the anchor plate; the anchor plate is a circular plate with perforations for connecting the main load-bearing reinforcement; the anchor pad plate is a circular plate with a diameter larger than the outer diameter of the anchor rod core tube; the anchor head is a compression anchor or a wedge anchor.

7. The construction method of the existing underground structure anti-buoyancy reinforcement grouting composite anchor system as described in claim 1, characterized in that, The static pressure equipment is either a gantry-type static pressure equipment or a clamping static pressure equipment, and its height is lower than the height of the basement; its bottom is fixedly connected to the base plate by anchor bolts.

8. The construction method of the grouting composite anchor system for anti-buoyancy reinforcement of existing underground structures as described in claim 1, characterized in that, In step five, the main reinforcing bars are steel strands, ordinary steel bars, precision rolled threaded steel bars, or fiber-reinforced composite materials; the main reinforcing bars are set according to the working conditions of applying tension prestress or not applying prestress.

9. The construction method of the grouting composite anchor system for anti-buoyancy reinforcement of existing underground structures as described in claim 1, characterized in that, In step five, when a new thick base plate is added above the base plate, the anchor head locking assembly is set inside the newly poured base plate.

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