Reinforcing device for subway tunnel construction and method thereof

Abstract

The application discloses a reinforcing device for existing buildings in subway tunnel construction, which comprises a rigid isolation wall vertically arranged between a subway tunnel and a foundation of an existing building, a flexible isolation component horizontally arranged between the rigid isolation wall and the foundation of the existing building, a deformation coordination device arranged between the foundation of the existing building and the rigid isolation wall and comprising an elastic material layer and a spring device, and a grouting pipe of a grouting reinforcing component distributed in the soil under the rigid isolation wall, the flexible isolation component and the foundation of the existing building. The application also provides a reinforcing method for existing buildings in subway tunnel construction. The components in the device cooperate with each other to form a comprehensive protection system from isolation, buffering, coordination to reinforcement, so that the stability of the existing building in the subway tunnel construction process is improved, and the structural safety hidden danger of the building caused by the construction is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of subway construction. More particularly, the present application relates to a reinforcing device for existing buildings during subway tunnel construction and a method thereof. BACKGROUND

[0002] With the acceleration of urbanization, the demand for urban transportation is increasing, and the subway, as an efficient and convenient public transportation mode, is expanding its construction scale. In the process of subway tunnel construction, it is inevitable to pass through the area of existing buildings, which brings unprecedented challenges to the construction. The existence of existing buildings makes the construction environment extremely complex, and the protection of existing buildings becomes a key link to ensure the safety of construction and the normal use of buildings.

[0003] Existing buildings are diverse in type, including different ages, different structural forms and different purposes. Some old buildings have weak anti-seismic and anti-deformation capabilities due to the aging of structural materials and the long time since their construction. Different structural forms, such as brick-concrete structures, frame structures and shear wall structures, respond differently to the disturbance of subway tunnel construction. Brick-concrete structures have relatively poor integrity, and under the action of soil deformation and construction vibration, the walls are prone to cracks or even collapse. Although frame structures have good spatial flexibility, stress concentration may occur at the column and beam joints due to construction impact, leading to structural damage. At the same time, buildings with different purposes have different sensitivities to deformation. For example, hospitals and schools, which are densely populated and have high requirements for building stability, may cause serious consequences even from a small deformation.

[0004] In summary, the excavation of subway tunnels will affect the soil, causing the stress of surrounding soil to redistribute, transforming the soil from the original rock stress balance state to the stress balance state after stress redistribution, inevitably causing deformation of the ground soil, which is transmitted to the ground surface to cause ground subsidence, and even collapse accidents in severe cases. This has a great impact on the adjacent buildings above, causing uneven settlement of the building foundation, resulting in tilting, cracking or even collapse of the buildings. Therefore, there is an urgent need for a reinforcing device for existing buildings during subway tunnel construction and a method thereof. SUMMARY

[0005] The present application provides a reinforcing device for existing buildings during subway tunnel construction and a method thereof. The components in the device cooperate with each other from isolation, buffering, coordination to reinforcement, forming a comprehensive protection system, which can improve the stability of existing buildings during subway tunnel construction and reduce the structural safety hazards caused by construction.

[0006] To achieve these objects and other advantages and in view of its purposes, in a first aspect, the present application provides a reinforcing device for existing buildings during subway tunnel construction, comprising:

[0007] Rigid isolation wall, which is a continuous concrete wall, is set vertically between the subway tunnel and the foundation of the existing building;

[0008] a flexible isolation component made of geosynthetics and arranged horizontally between the rigid isolation wall and the existing building foundation;

[0009] A deformation coordination device is provided between the foundation of the existing building and the rigid isolation wall. The deformation coordination device includes an elastic material layer and a spring device. The elastic material layer is provided on the side of the existing building foundation close to the flexible isolation assembly. One end of the spring device is fixedly connected to the embedded connection steel plate on the foundation of the existing building, and the other end is fixedly connected to the reserved connection point of the rigid isolation wall.

[0010] The grouting reinforcement component includes a grouting pipe with grouting holes arranged thereon. The grouting pipe is distributed in the rigid isolation wall, the periphery of the flexible isolation component and in the soil below the foundation of the existing building.

[0011] Preferably, the grouting pipe is obliquely inserted into the periphery of the rigid isolation wall and the flexible isolation assembly, with an inclination angle of 15°-20°, and is fixedly connected to the rigid isolation wall by an anchor; the lower end of the grouting pipe is located 3-5 meters below the bottom surface of the existing building foundation, and the grouting holes of the grouting pipe are spirally distributed with a spacing of 20-30cm and a pore diameter of 8-12mm; wherein, the grouting pipe adopts a high-strength PVC pipe with a diameter of 50-70mm, and the inner wall is provided with a nano-coating to reduce the slurry flow resistance; the outside of the grouting pipe is wrapped with a geotextile filter layer to prevent soil particles from clogging the grouting holes.

[0012] Preferably, the elastic material layer is a neoprene rubber sheet with a Shore hardness of 60-70HA, a tensile strength of not less than 18MPa, and an elongation at break of not less than 350%. It is bonded to the side surface of the existing building foundation using high-strength structural adhesive with a bonding strength of not less than 1.5Mpa; it is laid upward from the bottom of the existing building foundation to a height of 1 / 2-2 / 3 of the height of the existing building foundation, and the edges of the neoprene rubber sheet are sealed with sealant to prevent moisture and debris from intruding; when setting the spring device, the stress conditions of various parts of the foundation during construction are simulated by finite element software to determine the positions with high stress and the positions with low stress. At the positions with high stress, the spring devices are set at a spacing of 0.5-1m, and the spring stiffness of each spring device is 200-300kN / m; at the positions with low stress, the spring devices are set at a spacing of 1-1.5m, and the spring stiffness of each spring device is 100-200kN / m.

[0013] Preferably, the spring device comprises a shell and a spring located in the shell, the shell is a telescopic bellows, both ends are provided with openings to make both ends of the spring pass out of the shell, a connecting block is arranged at the outer end of the spring, the connecting block is not fixedly connected with the shell, wherein the spring is made of alloy steel material, the surface is treated with zinc-nickel alloy coating to improve the corrosion resistance and fatigue life of the spring; the wall thickness of the shell is 8-10mm at the position with large stress; the wall thickness of the shell is 6-8mm at the position with small stress.

[0014] Preferably, the rigid isolation wall is a double-layer structure, that is, an outer layer of reinforced concrete structure and an inner layer of reinforced concrete structure, and the outer layer of reinforced concrete structure and the inner layer of reinforced concrete structure are filled with foamed concrete, the thickness of the inner layer of reinforced concrete structure is smaller than that of the outer layer of reinforced concrete structure, and the side surface of the inner layer of reinforced concrete structure connected with the foamed concrete is a rough surface.

[0015] Preferably, the flexible isolation assembly is a multi-layer composite structure, a plurality of groups of flexible isolation assemblies are arranged at equal intervals from top to bottom, the flexible isolation assembly comprises an upper layer isolation assembly, an intermediate layer isolation assembly and a lower layer isolation assembly, wherein the upper layer isolation assembly is a composite geomembrane, which comprises upper and lower layers of non-woven geotextile and an intermediate layer of polyethylene geomembrane, the intermediate layer isolation assembly is a polystyrene foam board, and the lower layer isolation assembly is two layers of high-elastic non-woven geotextile.

[0016] Preferably, a wireless strain sensor is embedded in the laid flexible isolation assembly to monitor the settlement deformation of the soil near the foundation of the existing building.

[0017] Preferably, the grouting pressure of the grouting pipe is 0.3-0.5MPa, the grouting speed is 5-10L / min, and the horizontal spacing of the grouting pipe is 1m.

[0018] Preferably, the rigid isolation wall adopts a prefabricated concrete wall panel, the flexible isolation assembly adopts a prefabricated flexible isolation assembly, and the elastic material layer and the spring device are prefabricated deformation coordination devices.

[0019] In the second aspect, the application provides a method for reinforcing an existing building in subway tunnel construction, which is applied to the reinforcing device for reinforcing an existing building in subway tunnel construction and comprises:

[0020] S1, construction preparation: investigating the existing building, the subway tunnel construction area and the surrounding geological conditions to determine the construction range, the depth of the foundation of the existing building and the nature of the soil;

[0021] S2, between the subway tunnel and the existing building foundation, a prefabricated concrete wall is used to build a vertical rigid isolation wall, which is a double-layer structure, and the foam concrete is filled between the outer reinforced concrete structure and the inner reinforced concrete structure;

[0022] S3, between the rigid isolation wall and the existing building foundation, a flexible isolation component made of geosynthetic material is laid horizontally, which is a multi-layer composite structure, and multiple groups are arranged at equal intervals from top to bottom; wherein a wireless strain sensor is embedded in the laid flexible isolation component for monitoring the soil settlement deformation near the existing building foundation;

[0023] S4, on the side surface of the existing building foundation near the flexible isolation component, a high-elasticity rubber plate is bonded as an elastic material layer, which is laid from the bottom of the existing building foundation upwards, and the laying height is 1 / 2 to 2 / 3 of the height of the existing building foundation; a connecting steel plate is pre-buried on the existing building foundation, and a reserved connecting point is provided on the rigid isolation wall, one end of the spring device is fixedly connected with the pre-buried connecting steel plate, and the other end is fixedly connected with the reserved connecting point;

[0024] S5, drill holes around the rigid isolation wall and the flexible isolation component, and tilt the grouting pipe into the drill holes around the rigid isolation wall and the flexible isolation component, and make the lower end of the grouting pipe below the existing building foundation, the inclination angle of the grouting pipe is controlled at 15°-20°, the grouting pressure is kept at 0.3-0.5MPa, the grouting speed is 5-10L / min, and the horizontal spacing of the grouting pipe is 1 meter.

[0025] The present application at least comprises the following beneficial effects: a rigid isolation wall is arranged between the subway tunnel and the existing building foundation, the rigid isolation wall serves as a solid barrier and can effectively block the direct disturbance of the subway tunnel construction on the soil. Therefore, during shield tunneling and other operations, the direct impact of vibration, soil displacement and other construction on the existing building foundation can be reduced, and the risk of foundation damage is reduced. The flexible isolation component uses geosynthetic materials, which can further buffer the soil deformation caused by subway tunnel construction. When the soil deforms due to construction, the degree of deformation transmitted to the existing building foundation can be reduced, and problems such as uneven settlement and cracking of the building foundation due to excessive deformation of the soil can be avoided. The elastic material layer and spring device in the deformation coordination device can play an important role. The elastic material layer can absorb part of the deformation energy, and the spring device can coordinate deformation and disperse stress by stretching and contracting according to the relative displacement of the soil and the building foundation. In the area with large stress, the number of spring devices is increased, which can better adapt to the large deformation requirement and prevent the building structure from being damaged due to stress concentration. The grouting reinforcement component sets grouting pipes in the soil around the rigid isolation wall, the flexible isolation component and the existing building foundation, injects slurry to reinforce the soil, improves the bearing capacity and stability of the soil, reduces the building settlement caused by soft soil, and provides a more solid soil support for the existing building. In summary, the components cooperate with each other to form a comprehensive protection system from isolation, buffering, coordination to reinforcement, which comprehensively improves the stability of the existing building during the subway tunnel construction process, ensures the safety of the building, and reduces the structural safety hazards caused by construction.

[0026] Other advantages, objects, and features of the present application will be apparent to those skilled in the art from the following description, and will be appreciated by those skilled in the art. BRIEF DESCRIPTION OF DRAWINGS

[0027] Fig. 1 FIG. 1 is a side view of the reinforcing device for the existing building during the subway tunnel construction according to the present application;

[0028] Fig. 2 FIG. 4 is a side view of the spring device in the reinforcing device for the existing building during the subway tunnel construction according to the present application;

[0029] Fig. 3 FIG. 6 is a side view of the grouting pipe according to the present application. DETAILED DESCRIPTION

[0030] The present application will be further described in detail below with reference to the accompanying drawings, so that those skilled in the art can implement the present application according to the description.

[0031] It should be understood that the terms such as "have", "contain", and "include" used herein do not exclude the presence or addition of one or more other elements.

[0032] It should be noted that the experimental methods in the following embodiments are conventional methods, and the reagents and materials are commercially available unless otherwise specified. In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mount", "connect", "arrange" should be understood broadly, for example, they can be fixedly connected, arranged, or detachably connected, arranged, or integrally connected, arranged. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances. The orientations or positional relationships indicated by the terms "transverse", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0033] As shown in Figs. 1-3 The present application provides a reinforcing device for existing buildings in subway tunnel construction, which comprises: a rigid isolation wall 2, which is a concrete continuous wall, vertically arranged between a subway tunnel 5 and an existing building foundation 1; a flexible isolation component 4 made of geosynthetic material, horizontally arranged between the rigid isolation wall 2 and the existing building foundation 1; a deformation coordination device 3 arranged between the existing building foundation 1 and the rigid isolation wall 2, the deformation coordination device 3 comprising an elastic material layer 310 and a spring device 320, the elastic material layer 310 being arranged on the side of the existing building foundation 1 close to the flexible isolation component 4, one end of the spring device 320 being fixedly connected with a pre-buried connecting steel plate on the existing building foundation 1, and the other end being fixedly connected with a reserved connecting point of the rigid isolation wall 2; a grouting reinforcement component comprising a grouting pipe 6, the grouting pipe being provided with grouting holes, and the grouting pipe 6 being distributed in the rigid isolation wall 2, the flexible isolation component 4, and the soil under the existing building foundation 1.

[0034] The rigid isolation wall 2 is a prefabricated concrete wall plate, the flexible isolation component 4 is a prefabricated flexible isolation component, and the elastic material layer 310 and the spring device 320 are prefabricated deformation coordination devices.

[0035] In the above embodiment, when the tunnel 5 is constructed, the existing building to be reinforced needs to be investigated in advance, and the parameters of the rigid isolation wall 2, the flexible isolation assembly 4, the elastic material layer 310 and the spring device 320 are designed according to the investigation results, and are manufactured in advance by the factory. For example, the height of the rigid isolation wall 2 is set to 8 meters, the width is 2 meters, and the thickness is 0.5 meters. The outer layer of reinforced concrete structure 210 and the inner layer of reinforced concrete structure 230 are integrally cast in the factory, and the middle is filled with foam concrete 220. The side of the inner layer of reinforced concrete structure 230 connected with the foam concrete 220 is set as a rough surface during casting to enhance the adhesion with the foam concrete 220. During installation, a large crane is used to hoist the prefabricated concrete wall panel to the construction site, and the rigid isolation wall 2 is accurately placed between the subway tunnel 5 and the existing building foundation 1 according to the designed position, and the adjacent rigid isolation walls 2 are firmly connected through the reserved connecting steel bars and connecting pieces to form a continuous rigid isolation wall 2. During the installation process, the verticality of the rigid isolation wall 2 is strictly controlled to ensure that the error is within the allowable range. The prefabricated flexible isolation assembly 4 is a multi-layer composite structure. The upper isolation assembly is composed of two layers of non-woven geotextile and a layer of polyethylene geomembrane in the middle, with a size of 5 meters long and 2 meters wide. The middle layer isolation assembly is a polystyrene foam board with the same size as the upper layer. The lower layer isolation assembly is also two layers of high-elastic non-woven geotextile, with the same size of 5 meters long and 2 meters wide. In the factory, the three layers of assembly are combined into a complete prefabricated flexible isolation assembly 4. After the installation of the rigid isolation wall 2 is completed, the ground between the rigid isolation wall 2 and the existing building foundation 1 is cleaned and leveled. Starting from the side close to the existing building foundation 1, the prefabricated flexible isolation assembly 4 is laid in turn, and the units are connected in a lap joint manner with a lap width of 0.2 meters, and special glue is used for bonding to ensure tight connection. According to the design requirements, three groups of flexible isolation assemblies 4 are laid at equal intervals from top to bottom. It should be noted that trenches need to be dug in advance at the construction site to facilitate the installation of the rigid isolation wall 2 and the flexible isolation assembly 4 in the trenches. The elastic material layer 310 is made of neoprene rubber plate, with a size of 1 meter long, 0.5 meter wide and 0.03 meter thick. The springs of the spring device 320 are made of high-strength alloy steel, with a zinc-nickel alloy coating on the surface to improve the corrosion resistance and fatigue life of the springs. The slurry injected into the grouting pipe 6 is a composite grouting material. Cement slurry is added with an appropriate amount of bentonite, fly ash and other materials to form a composite grouting material. Bentontie can improve the suspension and stability of the slurry, reduce the precipitation and water separation of the slurry, and make it better diffuse in the sand layer and other strong permeable strata to improve the reinforcement effect. Fly ash can improve the fluidity of the slurry, reduce the cement dosage, save costs, and also enhance the later strength. For example, the underground construction area is a sand layer geology. P.O42.5 ordinary portland cement is used for cement, and the water-cement ratio is set to 0.5.The bentonite is added in an amount of 8% of the cement, and the fly ash is added in an amount of 20% of the cement. In the field, the construction personnel first mixes water and cement according to the water-cement ratio to prepare cement slurry. Then, the corresponding amount of bentonite and fly ash is weighed and slowly added into the cement slurry, and the stirring is continued for 30 minutes to ensure that the materials are fully mixed and uniform, forming a composite grouting material. The grouting and reinforcing assembly further comprises a grouting pump arranged at the pipe opening of the grouting pipe, and the grouting pump is used to inject grout into the grouting pipe. For the rigid isolation wall 2, the design parameters of the flexible isolation assembly 4, and the elastic material layer 310 and the spring device 320 can be set according to actual conditions.

[0036] In the above embodiment, the rigid isolation wall 2 is arranged between the subway tunnel 5 and the existing building foundation 1, and the rigid isolation wall 2 serves as a solid barrier to effectively block the direct disturbance of the subway tunnel 5 construction to the soil. Therefore, during shield tunneling and other operations, the direct impact of vibrations, soil displacement and other construction-induced effects on the existing building foundation 1 can be reduced, and the risk of foundation damage is reduced. The flexible isolation assembly 4 utilizes the properties of geosynthetic materials to further buffer the soil deformation caused by the construction of the subway tunnel 5. When the soil deforms due to construction, the degree of deformation transmitted to the existing building foundation 1 can be reduced, and problems such as uneven settlement and cracking of the building foundation 1 due to excessive soil deformation can be avoided. The elastic material layer 310 and the spring device 320 in the deformation coordination device 3 can play an important role. The elastic material layer 310 can absorb part of the deformation energy, and the spring device 320 can coordinate the deformation and disperse the stress by stretching and contracting according to the relative displacement of the soil and the building foundation 1. In areas with high stress, the number of spring devices 320 increases, which can better adapt to the requirement of larger deformation and prevent the building structure from being damaged due to stress concentration. The grouting and reinforcing assembly improves the bearing capacity and stability of the soil by arranging the grouting pipe around the rigid isolation wall 2, the flexible isolation assembly 4 and the soil under the existing building foundation 1, and injecting slurry to reinforce the soil, which reduces the settlement of the building caused by soft soil and provides a more solid soil support for the existing building.

[0037] In one specific embodiment, the grouting pipe 6 is inclined to the periphery of the rigid isolation wall 2 and the flexible isolation assembly 4 at an angle of 15°-20°, and is fixedly connected to the rigid isolation wall 2 through an anchor; the lower end of the grouting pipe 6 is located 3-5 meters below the bottom surface of the existing building foundation 1, and the grouting holes of the grouting pipe 6 are distributed in a spiral shape with a spacing of 20-30 cm and a hole diameter of 8-12 mm; wherein the grouting pipe 6 is a high-strength PVC pipe with a diameter of 50-70 mm, and the inner wall is provided with a nano coating to reduce the flow resistance of the slurry; the outer side of the grouting pipe 6 is wrapped with a layer of geotextile filter layer to prevent soil particles from blocking the grouting holes.

[0038] In the above-mentioned embodiments, the arranged grouting pipe 6 can enable the grout to fill into the soil pores around the rigid isolation wall 2, the flexible isolation assembly 4 and under the existing building foundation 1. For example, in some sandy or silty soil areas, the grout can cement the loose soil particles together, increase the density of the soil, and improve the shear strength and bearing capacity of the soil, thereby providing a more stable soil support foundation for the existing building, and reducing the risk of building settlement caused by soft soil. When the grouting pipe is inserted obliquely and deeply under the existing building foundation 1, the reinforced soil forms a stress dispersion area. When the soil stress changes due to the construction of the subway tunnel 5, this area can better disperse the stress and avoid excessive stress on the existing building foundation 1. Working together with the rigid isolation wall 2, the flexible isolation assembly 4 and the deformation coordination device 3, the stability of the existing building is improved. The reinforced soil enhances the lateral support of the rigid isolation wall 2, making it better resist construction disturbance; at the same time, it also provides a more stable foundation for the flexible isolation assembly 4, reducing the damage of soil deformation to the flexible isolation assembly 4, and ensuring the effectiveness of the entire reinforcement system, and fully protecting the safety of the existing building during the construction of the subway tunnel 5. When the grouting pipe 6 is set, a drilling machine is used to drill a hole, and then the grouting pipe 6 is inserted into the hole.

[0039] In this embodiment, the grouting pipe is arranged at an oblique angle (15°-20°) to form a three-dimensional network around the rigid isolation wall and the flexible isolation assembly, covering the key area under the building foundation and breaking through the limitations of traditional two-dimensional plane reinforcement. The lower end of the grouting pipe extends 3-5 meters below the bottom surface of the building foundation, and the soft and weak underlying layer where the building is most prone to settlement is reinforced. The grouting holes are distributed in a spiral shape on the grouting pipe with an increased spacing, which can achieve more uniform diffusion of grout compared to traditional straight-line grouting holes, forming a continuous "grouting curtain" to enhance the integrity of the soil and prevent local stress concentration. The grouting pipe is fixed to the rigid isolation wall by an anchoring device, which synchronously enhances the adhesion between the rigid isolation wall and the soil during the grouting process, forming a "isolation wall-grouting body-soil" composite bearing system, which significantly improves the lateral stiffness and deformation resistance of the rigid isolation wall. High-strength PVC pipe is more corrosion-resistant than traditional steel pipe and is suitable for complex underground environments; nano coating reduces grout loss and improves grouting efficiency. The geotextile filter layer effectively prevents the grouting hole from being blocked, ensures the continuity of grouting, and solves the problem of easy failure of traditional grouting pipes.

[0040] In one specific embodiment, the layer of elastic material 310 is a neoprene plate with a Shore hardness of 60-70 HA, a tensile strength of not less than 18 MPa, and an elongation at break of not less than 350%. The neoprene plate is bonded to the side surface of the existing building foundation using high-strength structural adhesive with a bonding strength of not less than 1.5 MPa. The neoprene plate is laid from the bottom of the existing building foundation upwards to a height of 1 / 2-2 / 3 of the height of the existing building foundation, and the edges of the neoprene plate are sealed using sealant to prevent the ingress of water and debris. When the spring devices 320 are installed, the stress conditions of each part of the building foundation during construction are simulated using finite element software to determine the positions of high stress and low stress. At positions of high stress, the spring devices 320 are installed with a spacing of 0.5-1 m, and each spring device 320 has a spring stiffness of 200-300 kN / m. At positions of low stress, the spring devices 320 are installed with a spacing of 1-1.5 m, and each spring device 320 has a spring stiffness of 100-200 kN / m.

[0041] In the above embodiment, the neoprene plate is a high-elasticity rubber plate with good elasticity and flexibility. When affected by soil deformation, vibration, and other factors caused by the construction of the subway tunnel 5, the neoprene plate can effectively buffer these external forces. Laying the neoprene plate from the bottom of the existing building foundation 1 upwards to a height of 1 / 2-2 / 3 of the height of the foundation can play a buffering role in critical parts. Installing more spring devices at positions of high stress allows the deformation coordination device 3 to better adapt to the deformation requirements of different parts. At the part of the building foundation 1 near the subway tunnel 5, the construction impact is greater, and the installation of more spring devices can provide stronger deformation coordination capabilities. When the soil undergoes large deformation, these spring devices can adjust the relative displacement between the foundation and the soil by their own stretching and contracting deformation, making the deformation of each part of the building foundation 1 more uniform, effectively preventing the building from tilting, cracking, and other situations caused by uneven deformation, and ensuring the structural safety of the building. In addition, this embodiment specifies specific parameters such as the Shore hardness, tensile strength, and elongation at break of the neoprene plate, which makes the performance of the layer of elastic material more stable and reliable in actual construction, and better adapts to the complex stress environment during construction. The neoprene plate with a Shore hardness of 60-70 HA has moderate hardness, which can provide sufficient elastic buffering and ensure a certain supporting strength. By simulating the stress conditions of each part of the building foundation using finite element software, the spacing and spring stiffness of the spring devices 320 are accurately set, which is more scientific and reasonable than the empirical setting of spring devices in existing technologies. Different spring stiffness and spacing are used at different stress positions to more accurately adjust the deformation coordination capability according to the actual stress conditions, improving the efficiency of the entire reinforcement device.

[0042] In one specific embodiment, the spring device 320 includes a shell 322 and a spring 321 located in the shell 322, the shell 322 is a telescopic bellows, both ends are provided with openings to make both ends of the spring 321 pass out of the shell 322, a connecting block 324 is provided at the outer end of the spring 321, the connecting block 324 is not fixedly connected with the shell 322, wherein the spring 321 is made of alloy steel, and the surface is treated with a zinc-nickel alloy coating to improve the corrosion resistance and fatigue life of the spring 321; the wall thickness of the shell 322 is 8-10 mm at the position with large stress; the wall thickness of the shell 322 is 6-8 mm at the position with small stress.

[0043] In the above embodiment, the shell made of a telescopic bellows provides good protection for the internal spring. In the subway tunnel 5 construction environment, there are dust, moisture and various corrosive substances. The bellows can block these substances from corroding the spring, preventing the spring from rusting and corroding, thereby ensuring that the spring is always in good working condition and stably plays its role in coordinating deformation and buffering stress. At the same time, the design of the two open ends does not affect the normal extension and contraction of the spring, and ensures the effective connection between the spring and the existing building foundation 1 and the rigid isolation wall 2, so that the spring can smoothly transmit and buffer stress. The spring is made of alloy steel and treated with a zinc-nickel alloy coating, which significantly improves the corrosion resistance and fatigue life of the spring compared to traditional spring materials and coatings, better adapts to the underground humid and complex environment, and reduces the problem of spring failure caused by corrosion and fatigue. The neoprene plate as the elastic material layer 310 has excellent elasticity, aging resistance and corrosion resistance, and its elasticity can effectively absorb and buffer the vibration and impact force generated during the construction of the subway tunnel 5, further enhancing the buffering performance of the deformation coordination device 3. In cooperation with the spring device 320, when the soil deforms, the neoprene plate first buffers part of the stress through its elastic deformation, and then the spring device 320 adjusts the extension and contraction according to the deformation, and the two work together to more effectively coordinate the deformation between the existing building foundation 1 and the rigid isolation wall 2, prevent the structure from being damaged due to stress concentration, and ensure the safety and stability of the existing building.

[0044] For the spring device 320, the spring 321 in the spring device 320 can be arranged in two sections, a support rod 323 is arranged at the connection, and a connecting block 324 is arranged at the outer end of the two sections of the spring 321, and the connecting block 324 is not fixedly connected with the shell.

[0045] In one embodiment, the rigid isolation wall 2 is a double-layer structure, i.e., an outer reinforced concrete structure 210 and an inner reinforced concrete structure 230, and the inner reinforced concrete structure 230 is filled with foamed concrete 220, the thickness of the inner reinforced concrete structure 230 is less than that of the outer reinforced concrete structure 210, and the side of the inner reinforced concrete structure 230 connected with the foamed concrete 220 is rough.

[0046] In the above embodiment, the outer reinforced concrete structure 210 provides strong compression and shear resistance, can withstand the large soil pressure, vibration load and other external forces generated during the construction of the subway tunnel 5, effectively blocks the direct disturbance of the construction to the soil, and reduces the impact on the existing building foundation 1. The inner reinforced concrete structure 230 is relatively thin, but works cooperatively with the outer structure to enhance the overall stability of the rigid isolation wall 2. At the same time, the rough surface of the inner reinforced concrete structure 230 connected with the foamed concrete 220 increases the friction and adhesion between the two, so that the foamed concrete 220 can better work cooperatively with the inner structure, improve the ability of the rigid isolation wall 2 to resist deformation, and ensure the safety of the existing building. The filled foamed concrete 220 has the characteristics of light weight and heat preservation, reduces the weight of the rigid isolation wall 2 itself, reduces the pressure on the foundation, and to some extent reduces the possibility of settlement of the rigid isolation wall 2 itself.

[0047] In one embodiment, the flexible isolation assembly 4 is a multi-layer composite structure, and a plurality of flexible isolation assemblies 4 are arranged at equal intervals from top to bottom, including upper isolation assemblies, intermediate layer isolation assemblies, and lower isolation assemblies. The upper isolation assembly is a composite geomembrane, which includes two layers of non-woven geotextile and one layer of polyethylene geomembrane, the intermediate layer isolation assembly is a polystyrene foam board, and the lower isolation assembly is two layers of high-elastic non-woven geotextile.

[0048] In the above embodiment, the upper composite geomembrane has two layers of non-woven geotextile above and below, which can play a filtering and protective role for the intermediate polyethylene geomembrane. The polyethylene geomembrane has good anti-seepage and isolation performance, which can effectively block the migration of water and fine particles in the soil, and reduce the influence of the change of water content and particle movement in the soil on the existing building foundation 1. The intermediate layer of polystyrene foam board is light in texture and has elasticity, which can buffer the vibration and soil deformation caused by the construction of the subway tunnel 5, and reduce the impact on the existing building foundation 1. The lower two layers of high-elasticity non-woven geotextile not only can further buffer the deformation, but also has good flexibility, which can adapt to a certain degree of displacement of the soil, and prevent the isolation assembly from failing due to the slight deformation of the soil. A plurality of flexible isolation assemblies 4 are arranged at equal intervals, which further enhances the overall isolation and buffering effect, and reduces the construction influence from multiple aspects.

[0049] In one specific embodiment, a wireless strain sensor is embedded in the laid flexible isolation assembly 4 to monitor the settlement and deformation of the soil near the existing building foundation 1. The wireless strain sensor can monitor the settlement and deformation of the soil near the existing building foundation 1 in real time. Traditional monitoring methods often require manual periodic measurement, which has the problems of long time interval and untimely data acquisition. The strain sensor can capture soil deformation information at any time and feed back data to the monitoring personnel through wireless transmission technology. For example, once the soil appears abnormal settlement, the strain sensor can immediately send a signal, so that the construction personnel can know in the first time and take timely measures.

[0050] In one specific embodiment, the grouting pressure of the grouting pipe is 0.3-0.5 MPa, the grouting speed is 5-10 L / min, and the horizontal spacing of the grouting pipe is 1 meter.

[0051] Another embodiment of the present application provides a reinforcing method for existing buildings during subway tunnel construction, which is applied to the reinforcing device for existing buildings during subway tunnel construction, and comprises:

[0052] S1, construction preparation: investigating the existing building, the subway tunnel 5 construction area and the surrounding geological conditions, determining the construction range and the depth of the existing building foundation 1, and the soil properties;

[0053] S2, between the subway tunnel 5 and the existing building foundation 1, a vertical rigid isolation wall 2 is constructed by using a prefabricated concrete wall plate, the rigid isolation wall 2 has a double-layer structure, and the outer layer of reinforced concrete structure 210 and the inner layer of reinforced concrete structure 230 are filled with foam concrete 220;

[0054] S3, a flexible isolation component 4 made of geosynthetic material is horizontally laid between the rigid isolation wall 2 and the existing building foundation 1, the flexible isolation component 4 is a multi-layer composite structure, and a plurality of groups are arranged at equal intervals from top to bottom; wherein a wireless strain sensor is embedded in the laid flexible isolation component 4 for monitoring the settlement deformation of the soil near the existing building foundation 1;

[0055] S4, a high-elasticity rubber plate is bonded as an elastic material layer 310 on the side surface of the existing building foundation 1 near the flexible isolation component 4, and is laid upwards from the bottom of the existing building foundation 1, and the laying height is 1 / 2 to 2 / 3 of the height of the existing building foundation 1; a connecting steel plate is pre-buried on the existing building foundation 1, and a reserved connecting point is provided on the rigid isolation wall 2, one end of the spring device 320 is fixedly connected with the pre-buried connecting steel plate, and the other end is fixedly connected with the reserved connecting point;

[0056] S5, inclined drilling is performed on the periphery of the rigid isolation wall 2 and the flexible isolation component 4, a grouting pipe is inclined inserted into the drilling on the periphery of the rigid isolation wall 2 and the flexible isolation component 4, so that the lower end of the grouting pipe is located below the existing building foundation 1, the inclination angle of the grouting pipe is controlled to be 15°-20°, the grouting pressure is kept at 0.3-0.5MPa, the grouting speed is 5-10L / min, and the horizontal spacing of the grouting pipes is 1m.

[0057] The construction method provides basis for subsequent construction through pre-investigation, and each step constructs each component of the reinforcement device in turn, from isolation, buffering, coordinated deformation to soil reinforcement, to form a complete protection system. At the same time, the embedded sensor realizes real-time monitoring, and each link closely cooperates to comprehensively ensure the safety and stability of the existing building in the subway tunnel construction.

[0058] The number of devices and the scale of processing described here are used to simplify the description of the application. Applications, modifications and variations of the application will be apparent to those skilled in the art.

[0059] Although the embodiments of the present application have been disclosed as above, it is not limited to the application and implementation listed in the specification, and it can be fully applied to various fields suitable for the present application, and additional modifications can be easily realized by those skilled in the art, therefore the present application is not limited to specific details and the figures shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. A reinforcement device for existing buildings during subway tunnel construction, characterized in that: include: Rigid isolation wall, which is a continuous concrete wall, is set vertically between the subway tunnel and the foundation of the existing building; a flexible isolation component made of geosynthetics and arranged horizontally between the rigid isolation wall and the existing building foundation; A deformation coordination device is provided between the foundation of the existing building and the rigid isolation wall. The deformation coordination device includes an elastic material layer and a spring device. The elastic material layer is provided on the side of the existing building foundation close to the flexible isolation assembly. One end of the spring device is fixedly connected to the embedded connection steel plate on the foundation of the existing building, and the other end is fixedly connected to the reserved connection point of the rigid isolation wall. A grouting reinforcement assembly includes a grouting pipe with grouting holes disposed thereon, the grouting pipe being distributed in the soil around the rigid isolation wall, the flexible isolation assembly, and below the foundation of the existing building; Wherein, the elastic material layer is a neoprene rubber sheet with a Shore hardness of 60-70HA, a tensile strength of not less than 18MPa, and an elongation at break of not less than 350%. It is bonded to the side surface of the existing building foundation using high-strength structural adhesive with a bonding strength of not less than 1.5Mpa; it is laid upward from the bottom of the existing building foundation to a height of 1 / 2-2 / 3 of the height of the existing building foundation, and the edges of the neoprene rubber sheet are sealed with sealant to prevent the intrusion of moisture and debris; when setting the spring device, the stress conditions of various parts of the foundation during construction are simulated by finite element software to determine the positions with high stress and the positions with low stress. At the position with high stress, the setting spacing of the spring devices is 0.5-1m, and the spring stiffness of each spring device is 200-300kN / m; at the position with low stress, the setting spacing of the spring devices is 1-1.5m, and the spring stiffness of each spring device is 100-200kN / m; The spring device includes a housing and a spring located in the housing. The housing is a telescopic bellows with openings at both ends to allow the two ends of the spring to pass through the housing. A connecting block is provided at the outer end of the spring, and the connecting block is not fixedly connected to the housing. The spring is made of alloy steel and the surface is treated with a zinc-nickel alloy coating to improve the corrosion resistance and fatigue life of the spring. The wall thickness of the housing is 8-10 mm at a location with high force; and the wall thickness of the housing is 6-8 mm at a location with low force. The flexible isolation component is a multi-layer composite structure, with multiple groups of flexible isolation components arranged at equal intervals from top to bottom. The flexible isolation component includes an upper isolation component, a middle isolation component and a lower isolation component. The upper isolation component is a composite geomembrane, which includes two layers of non-woven geotextiles and a middle layer of polyethylene geomembrane. The middle isolation component is a polystyrene foam board, and the lower isolation component is two layers of high-elastic non-woven geotextiles.

2. The reinforcement device for existing buildings during subway tunnel construction according to claim 1, characterized in that: The grouting pipe is obliquely inserted into the periphery of the rigid isolation wall and the flexible isolation component, with an inclination angle of 15°-20°, and is fixedly connected to the rigid isolation wall by an anchor; the lower end of the grouting pipe is located 3-5 meters below the bottom surface of the existing building foundation, and the grouting holes of the grouting pipe are spirally distributed with a spacing of 20-30cm and an aperture of 8-12mm; wherein, the grouting pipe adopts a high-strength PVC pipe with a diameter of 50-70mm, and the inner wall is provided with a nano-coating to reduce the slurry flow resistance; the outer side of the grouting pipe is wrapped with a geotextile filter layer to prevent soil particles from clogging the grouting holes.

3. The reinforcement device for existing buildings during subway tunnel construction according to claim 1, characterized in that: The rigid isolation wall is a double-layer structure, namely an outer reinforced concrete structure and an inner reinforced concrete structure. Foam concrete is filled between the outer reinforced concrete structure and the inner reinforced concrete structure. The thickness of the inner reinforced concrete structure is smaller than that of the outer reinforced concrete structure, and the side of the inner reinforced concrete structure connected to the foam concrete is a rough surface.

4. The reinforcement device for existing buildings during subway tunnel construction according to claim 1, characterized in that: Wireless strain sensors are embedded in the laid flexible isolation components to monitor the settlement and deformation of soil near the foundation of existing buildings.

5. The reinforcement device for existing buildings during subway tunnel construction according to claim 2, characterized in that: The grouting pressure of the grouting pipe is 0.3-0.5 MPa, the grouting speed is 5-10 L / min, and the horizontal spacing of the grouting pipe is 1 meter.

6. The reinforcement device for existing buildings during subway tunnel construction according to claim 1, characterized in that: The rigid isolation wall adopts prefabricated concrete wall panels, the flexible isolation components adopt prefabricated flexible isolation components, and the elastic material layer and the spring device are prefabricated deformation coordination devices.

7. A method for reinforcing an existing building during subway tunnel construction, applied to the device for reinforcing an existing building during subway tunnel construction according to any one of claims 1 to 6, characterized in that: include: S1. Construction Preparation: Investigate the existing buildings, subway tunnel construction area and surrounding geological conditions to determine the construction scope, foundation depth of existing buildings, and soil properties; S2. Construct a vertical rigid isolation wall between the subway tunnel and the existing building foundation using precast concrete wall panels. The rigid isolation wall has a double-layer structure, with foam concrete filled between the outer and inner reinforced concrete layers. S3. Horizontally lay flexible isolation assemblies made of geosynthetics between the rigid isolation wall and the existing building foundation. The flexible isolation assemblies are multi-layer composite structures, with multiple groups spaced evenly from top to bottom. Wireless strain sensors are embedded in the laid flexible isolation assemblies to monitor soil settlement and deformation near the existing building foundation. S4. Bond a highly elastic rubber sheet as an elastic material layer to the side surface of the existing building foundation near the flexible isolation assembly, and lay it upward from the bottom of the existing building foundation to a height of 1 / 2 to 2 / 3 of the height of the existing building foundation; pre-embed a connecting steel plate on the existing building foundation, and set a reserved connection point on the rigid isolation wall; fix one end of the spring device to the pre-embedded connecting steel plate, and fix the other end to the reserved connection point; S5. Drill holes around the rigid isolation wall and flexible isolation components, insert the grouting pipe into the drilled holes around the rigid isolation wall and flexible isolation components at an angle, and make the lower end of the grouting pipe be located below the foundation of the existing building. The inclination angle of the grouting pipe should be controlled at 15°-20°, the grouting pressure should be maintained at 0.3-0.5MPa, the grouting speed should be 5-10L / min, and the horizontal spacing of the grouting pipes should be 1 meter.

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