Super-thick concrete wall construction method

Abstract

The invention provides an ultra-thick concrete wall body construction method, and belongs to the technical field of building construction.The ultra-thick concrete wall body construction method comprises the following steps that a fabricated wall body model sample matched with the environment of a construction unit is set up by simulating a wall body, carrying out finite element analysis on the model sample to accurately simulate the thermal stress distribution of the wall body by utilizing the finite element analysis; according to a temperature field result obtained through thermal analysis, structural mechanical analysis is conducted, and thermal stress generated by the wall due to temperature changes is calculated; dividing different areas by taking the thermal stress value distribution key point as a boundary, and adjusting the aggregate proportion by combining the areas; construction structure optimization is conducted on the basis of an assembly type wall body structure, and assembly filling is conducted on an ultra-thick concrete wall body; by means of the light partition plate of the composite fiber net structure, concrete aggregate of different partitions is evenly distributed, blending of cement paste is blocked, it is guaranteed that the partition performance is independent and stable, and efficient construction and performance improvement of the super-thick concrete wall are guaranteed through the multi-dimensional synergistic effect.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and in particular relates to a method for constructing an ultra-thick concrete wall. Background Art

[0002] With the rapid development of modern industry, the cold chain logistics industry has flourished, and the demand for the construction of large cold storage is growing. The ultra-thick concrete wall in the cold storage is the main enclosure structure. Its quality and performance are directly related to the refrigeration efficiency, cargo storage quality and operating costs of the cold storage. In the construction of ultra-thick concrete walls, especially in structures such as cold storage with a large temperature difference between the inside and outside, traditional construction methods are difficult to effectively cope with thermal stress. Due to the thermal conductivity of concrete, the temperature difference between the inside and outside of the wall will produce significant thermal stress inside.

[0003] Existing ultra-thick concrete wall construction technology often lacks accurate analysis and effective prevention and control measures for this thermal stress. It mostly adopts a unified concrete mix ratio for single walls and conventional thermal insulation methods. Due to the significant differences in the thermal stress borne by different parts of the wall, such as the thermal stress in areas close to cold sources or heat sources is larger, while the thermal stress in areas far away from these areas is relatively small, it is impossible to perform targeted treatment based on the thermal stress characteristics of different parts of the wall, resulting in a high risk of wall cracking, which seriously affects the durability and thermal insulation performance of the structure. Summary of the invention

[0004] In view of this, the present invention provides an ultra-thick concrete wall construction method, which can carry out targeted treatment according to the thermal stress characteristics of different parts of the wall to avoid the risk of cracking of the wall.

[0005] The present invention is achieved in that:

[0006] The present invention provides a super-thick concrete wall construction method, which comprises the following steps:

[0007] S10: Simulate the wall to set up a prefabricated wall model sample that matches the construction unit's environment, and perform finite element analysis on the model sample;

[0008] S20: Perform structural mechanics analysis based on the temperature field results obtained from thermal analysis to calculate the thermal stress of the wall caused by temperature changes;

[0009] S30: Divide different areas according to the key points of thermal stress value distribution, and adjust the aggregate ratio according to the area;

[0010] S40: Optimize the construction structure based on the prefabricated wall structure and assemble fillers for ultra-thick concrete walls.

[0011] On the basis of the above technical solution, the ultra-thick concrete wall construction method of the present invention can also be improved as follows:

[0012] The specific steps of setting up a prefabricated wall model sample that matches the construction unit environment and performing finite element analysis on the model sample are as follows:

[0013] Step 1: First, a sample model is established according to the size of the construction unit to facilitate steady-state thermal analysis of the inside and outside of the wall, and to obtain the temperature field distribution of the wall under the action of the temperature difference between the inside and outside. The sample model includes an environmental structure and a three-dimensional geometric model of an assembled wall structure. The assembled wall structure includes an ultra-thick wall frame. A plurality of groups of inner frame structures are sequentially arranged on the ultra-thick wall frame from top to bottom. The inner frame structure includes a steel bar structure, and baffles are respectively arranged on both sides. Concrete and aggregate fillers of the same proportion are injected into each layer of the inner frame structure from top to bottom. The concrete and aggregate fillers are divided into a plurality of units, and the unit type is selected to be a solid unit that is convenient for simulating solid heat transfer and structural mechanics behavior;

[0014] Step 2: Assign corresponding thermophysical and mechanical parameters of concrete and aggregate in the prefabricated wall sample model through the database of finite element analysis software;

[0015] Step 3: Apply ambient temperature loads corresponding to the construction unit environment to the inner and outer sides of the assembled wall sample model;

[0016] Step 4: Calculate the temperature value of each node inside the prefabricated wall sample model through finite element software, generate a temperature cloud map, intuitively display the temperature changes of the wall from the inside to the outside and from top to bottom, and output the thermal analysis results.

[0017] Furthermore, the specific steps of performing structural mechanics analysis based on the temperature field results obtained by thermal analysis and calculating the thermal stress of the wall caused by temperature changes include:

[0018] Step 1: Calculate the thermal strain of each unit according to the thermal expansion coefficient and the temperature difference, and then calculate the thermal stress in combination with the elastic modulus of the current unit to obtain the thermal stress distribution cloud map;

[0019] Step 2: Analyze the changing pattern of thermal stress from inside to outside and from top to bottom, and then determine the location where the maximum thermal stress occurs, which is the key point of wall cracking.

[0020] Furthermore, the specific steps of dividing different regions based on the key points of thermal stress value distribution and adjusting the aggregate ratio in combination with the regions include:

[0021] Step 1: According to the distribution of thermal stress values, key points are divided into high stress area, medium stress area and low stress area. The high stress area is the location where the wall is prone to cracking.

[0022] Step 2: Adjust the concrete and aggregate ratios for different partitions to reduce the temperature gradient and achieve stability of the wall structure by reducing the heat conduction efficiency.

[0023] Step 3: Re-enter the thermophysical and mechanical parameters of the adjusted concrete and aggregate ratio into the finite element model, and conduct thermal stress simulation analysis again to ensure that the thermal stress at the key points after adjustment is reduced, so that the wall constructed according to the ratio in the later stage is more stable;

[0024] Step 4: In order to further reduce the heat accumulation inside the wall, consider setting up an energy extraction structure in the wall based on the connection structure between adjacent inner frame structures.

[0025] Furthermore, the specific steps of optimizing the construction structure based on the assembled wall structure and then starting the construction of the ultra-thick concrete wall include:

[0026] Step 1: Construct multiple casting modules by compiling reinforcement cages;

[0027] Step 2: respectively fix and connect the longitudinal connection units at the top and bottom ends of the adjacent steel cages;

[0028] Step 3: Coordinate and connect the energy export structure with the longitudinal connection unit;

[0029] Step 4: Seal and protect the connection between the energy output structure and the longitudinal connection unit;

[0030] Step 5: Assemble and fill multiple groups of casting modules.

[0031] Furthermore, the specific steps of constructing multiple casting modules by compiling a steel cage include:

[0032] A square steel frame is made as the skeleton according to the length-width ratio of a single casting module. The horizontal and vertical steel beams of the frame are made of high-strength angle steel to improve support and stability. Steel mesh is welded on the inner surface of the steel frame according to the stress limit partition. The aperture of the steel mesh is 50mm×50mm. A composite fiber layer is fixed on the surface of the steel mesh. The composite fiber layer is a thin plate with a thickness of less than 6mm made by mixing glass fiber and metal fiber and then pressing. Support steel bars are tied and welded horizontally and longitudinally on the inner side of the steel cross frame to form a steel cage.

[0033] Furthermore, the specific steps of respectively fixing and connecting the longitudinal connection units at the top and bottom ends of the corresponding adjacent steel cages include:

[0034] Anchor bolts are welded at the top and bottom of the steel cage. The surface of the anchor bolts is threaded. The anchor bolts pass through the through holes on the longitudinal connection units and are locked and fixed with nuts. A groove is provided on the upper surface of the longitudinal connection unit on the top side, and a protrusion matching the groove is provided on the lower surface of the longitudinal connection unit on the bottom side, so as to facilitate the installation of two sets of adjacent steel cages in the longitudinal direction. The reinforcing steel bars are passed through the gaps between the horizontal steel bars inside the longitudinal connection units and are welded and fixed to the supporting steel bars in the steel cage.

[0035] Furthermore, the specific steps of coordinating and connecting the energy output structure with the longitudinal connection unit include:

[0036] The heat pipe uses a copper tube with a diameter of 25mm and is filled with a low-boiling-point working fluid, such as acetone. The heat pipe is inserted into the reserved through hole of the horizontal steel frame of the longitudinal connection unit. Thermal conductive silicone is used to fill the space between the heat pipe and the through hole to ensure good thermal conductivity. The length of the evaporation section of the heat pipe is determined according to the thermal stress distribution of the wall.

[0037] Furthermore, the specific steps of sealing and protecting the connection between the energy output structure and the longitudinal connection unit include:

[0038] At the connection between the heat pipe and the longitudinal connection unit, high temperature resistant sealant is used for sealing to prevent leakage of the working fluid. A protective sleeve is arranged around the heat pipe. The sleeve is made of hard plastic with a wall thickness of 5mm.

[0039] Furthermore, the specific steps of assembling and filling the multiple groups of casting modules include:

[0040] Step 1: First, accurately locate and lay out the lines according to the designed position of the wall, determine the installation positions between adjacent casting modules, and mark the corresponding contour lines and center lines on the foundation surface;

[0041] Step 2: Place the first casting module on the foundation, adjust its position and levelness, and control the error within 5mm. Place the casting modules in the same horizontal row one by one, and install casting baffles on both sides of the corresponding casting modules.

[0042] Step 3: Place the iron core of the magnetic field generator at the bottom of the casting module corresponding to the composite fiber layer, then wind the electromagnetic coil around the iron core and connect the thyristor rectifier and AC power supply.

[0043] Step 4: Inject concrete of corresponding proportion into the corresponding filling area through the upper longitudinal connection unit according to the thermal stress partition. During the concrete pouring process, vibrate with a vibrator. The insertion depth of the vibrator is 300mm. The vibration time is based on the fact that no bubbles or slurry appear on the concrete surface.

[0044] Step 5: Connect the heat pipes in the same horizontal row of longitudinal connection units in series, extend the condensing section to the outside of the wall, and connect the heat sink, which is made of aluminum;

[0045] Step 6: After completing the assembly and pouring of the bottom layer of casting modules, place the upper layer casting modules in the groove position corresponding to the upper longitudinal connecting unit, and assemble and pour the second horizontal row of casting modules according to the above steps. After gradually completing the construction of the entire wall, remove the casting baffles on both sides and smooth the wall surface to make it flat and smooth.

[0046] Compared with the prior art, the beneficial effects of the ultra-thick concrete wall construction method provided by the present invention are as follows: the thermal stress of the wall is accurately simulated through finite element analysis, and different areas such as high stress area, medium stress area and low stress area are clearly divided to realize accurate thermal stress simulation and zoning; aggregates with different thermal expansion coefficients and thermal conductivity are selected for combination according to the thermal stress characteristics of different areas, and aggregates with smaller thermal expansion coefficients are used in areas with large thermal stress changes, thereby reducing the volume change caused by temperature changes, avoiding the risk of wall cracking, and significantly improving the durability of the wall; by locating the evaporation section of the heat pipe in the inner area where the wall temperature is higher, the evaporation heat absorption principle of the working fluid is utilized to quickly absorb the heat inside the wall and transfer it to the condensation section, which is located on the outside of the wall and connected to the heat sink to dissipate the heat into the environment; in the high temperature environment in summer, the maximum temperature inside the wall can be reduced by 10°C-15°C after the heat pipe is set, which effectively solves the problem of heat accumulation inside the wall, makes the temperature distribution inside the wall more uniform, reduces the increase in thermal stress caused by high temperature, and extends the service life of the wall.

[0047] Before pouring concrete, a specific magnetic field is applied to the partition through an external magnetic field generating device. Since the partition fiber contains magnetic conductive materials, when concrete with different proportions of additives or aggregates is injected into different partitions, the charged particles or magnetic particles in the aggregates and additives will be acted upon by force, thus avoiding local agglomeration. According to sampling tests, the uniformity of concrete aggregate distribution in the partition using composite fiber laminates is 25%-35% higher than that of traditional methods, making the performance of concrete in each partition more consistent and effectively improving the overall quality stability of the wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0049] Figure 1 is a flow chart of a method for constructing an ultra-thick concrete wall;

[0050] Figure 2 This is a schematic diagram of an ultra-thick wall frame;

[0051] Figure 3 This is the overall schematic diagram of the super thick concrete wall;

[0052] Figure 4 Assemble the top schematic diagram for the casting module;

[0053] Figure 5 It is a schematic diagram of the connection between the heat pipe and the heat sink outside the wall;

[0054] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0055] 10. Extra-thick wall frame; 101. Inner frame structure; 102. Baffle; 11. Energy export structure; 12. Casting module; 121. Longitudinal connection unit; 122. Casting baffle. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0057] like Figure 1 FIG. 1 is a flow chart of a method for constructing an ultra-thick concrete wall provided by the present invention, comprising the following steps:

[0058] S10: Simulate the wall to set up a prefabricated wall model sample that matches the construction unit's environment, and perform finite element analysis on the model sample;

[0059] S20: Perform structural mechanics analysis based on the temperature field results obtained from thermal analysis to calculate the thermal stress of the wall caused by temperature changes;

[0060] S30: Divide different areas according to the key points of thermal stress value distribution, and adjust the aggregate ratio according to the area;

[0061] S40: Optimize the construction structure based on the prefabricated wall structure and assemble fillers for ultra-thick concrete walls.

[0062] like Figure 2-5 As shown, in the above technical solution, the specific steps of simulating the wall to set up a prefabricated wall model sample that matches the construction unit environment and performing finite element analysis on the model sample are:

[0063] Step 1: First, a sample model is established according to the size of the construction unit to facilitate steady-state thermal analysis of the inside and outside of the wall, and to obtain the temperature field distribution of the wall under the action of the temperature difference between the inside and outside. The sample model includes an environmental structure and a three-dimensional geometric model of an assembled wall structure. The assembled wall structure includes an ultra-thick wall frame 10. Multiple groups of inner frame structures 101 are arranged on the ultra-thick wall frame 10 from top to bottom. The inner frame structure 101 includes a steel bar structure, and baffles 102 are respectively arranged on both sides. Concrete and aggregate fillers of the same proportion are injected into each layer of the inner frame structure 101 from top to bottom. The concrete and aggregate fillers are divided into a number of units, and the unit type is selected as a solid unit that is convenient for simulating solid heat transfer and structural mechanics behavior;

[0064] Step 2: Assign corresponding thermophysical and mechanical parameters of concrete and aggregate in the prefabricated wall sample model through the database of finite element analysis software;

[0065] Step 3: Apply ambient temperature loads corresponding to the construction unit environment to the inner and outer sides of the assembled wall sample model;

[0066] Step 4: Calculate the temperature value of each node inside the prefabricated wall sample model through finite element software, generate a temperature cloud map, intuitively display the temperature changes of the wall from the inside to the outside and from top to bottom, and output the thermal analysis results.

[0067] Furthermore, in the above technical solution, the specific steps of performing structural mechanics analysis based on the temperature field results obtained by thermal analysis and calculating the thermal stress of the wall caused by temperature changes include:

[0068] Step 1: Calculate the thermal strain of each unit according to the thermal expansion coefficient and the temperature difference, and then calculate the thermal stress in combination with the elastic modulus of the current unit to obtain the thermal stress distribution cloud map;

[0069] Step 2: Analyze the changing pattern of thermal stress from inside to outside and from top to bottom, and then determine the location where the maximum thermal stress occurs, which is the key point of wall cracking.

[0070] Furthermore, in the above technical solution, different regions are divided according to the key points of the thermal stress value distribution as boundaries, and the specific steps of adjusting the aggregate ratio in combination with the regions include:

[0071] Step 1: According to the distribution of thermal stress values, key points are divided into high stress area, medium stress area and low stress area. The high stress area is the location where the wall is prone to cracking.

[0072] Step 2: Adjust the concrete and aggregate ratios for different partitions to reduce the temperature gradient and achieve stability of the wall structure by reducing the heat conduction efficiency.

[0073] Step 3: Re-enter the thermophysical and mechanical parameters of the adjusted concrete and aggregate ratio into the finite element model, and conduct thermal stress simulation analysis again to ensure that the thermal stress at the key points after adjustment is reduced, so that the wall constructed according to the ratio in the later stage is more stable;

[0074] Step 4: In order to further reduce the heat accumulation inside the wall, consider setting an energy extraction structure 11 in the wall based on the connection structure between adjacent inner frame structures 101.

[0075] Furthermore, in the above technical solution, the specific steps of optimizing the construction structure based on the prefabricated wall structure and then starting the construction of the ultra-thick concrete wall include:

[0076] The first step: constructing a plurality of casting modules 12 by compiling a steel cage;

[0077] Step 2: The top and bottom ends of the corresponding adjacent steel cages are fixedly connected to the longitudinal connection units 121;

[0078] Step 3: Coordinate and connect the energy output structure 11 and the longitudinal connection unit 121;

[0079] Step 4: sealing and protecting the connection between the energy output structure 11 and the longitudinal connection unit 121;

[0080] Step 5: Assemble and fill multiple groups of casting modules 12.

[0081] Furthermore, in the above technical solution, the specific steps of constructing a plurality of casting modules 12 by compiling a steel cage include:

[0082] A square steel frame is made according to the length-width ratio of a single casting module 12 as a skeleton. The horizontal and vertical steel beams of the frame are made of high-strength angle steel to improve support and stability. A steel mesh is welded on the inner surface of the steel frame according to stress limit zones. The aperture of the steel mesh is 50mm×50mm. A composite fiber layer is fixed on the surface of the steel mesh. The composite fiber layer is a thin plate with a thickness of less than 6mm made by weaving a mixture of glass fiber and metal fiber and then pressing. Support steel bars are tied and welded horizontally and longitudinally on the inner side of the steel cross frame to form a steel cage.

[0083] Furthermore, in the above technical solution, the specific steps of respectively fixing and connecting the longitudinal connection units 121 at the top and bottom ends of the adjacent steel cages include:

[0084] Anchor bolts are welded at the top and bottom ends of the steel cage. The surface of the anchor bolts is threaded. The anchor bolts pass through the through holes on the longitudinal connection unit 121 and are locked and fixed with nuts. A groove is provided on the upper surface of the longitudinal connection unit 121 on the top side, and a protrusion matching the groove is provided on the lower surface of the longitudinal connection unit 121 on the bottom side, so as to facilitate the installation of two sets of adjacent steel cages in the longitudinal direction. The reinforcing steel bars are passed through the gaps between the horizontal steel bars inside the longitudinal connection unit 121 and are welded and fixed to the supporting steel bars in the steel cage.

[0085] Furthermore, in the above technical solution, the specific steps of coordinating and connecting the energy output structure 11 and the longitudinal connection unit 121 include:

[0086] The heat pipe is a copper tube with a diameter of 25 mm, and is filled with a low-boiling-point working fluid, such as acetone. The heat pipe is inserted into the reserved through hole of the horizontal steel frame of the longitudinal connection unit 121, and the space between the heat pipe and the through hole is filled with thermal conductive silicone to ensure good thermal conductivity. The length of the evaporation section of the heat pipe is determined according to the thermal stress distribution of the wall.

[0087] Furthermore, in the above technical solution, the specific steps of sealing and protecting the connection between the energy output structure 11 and the longitudinal connection unit 121 include:

[0088] At the connection between the heat pipe and the longitudinal connection unit 121, high temperature resistant sealant is used for sealing to prevent leakage of the working fluid. A protective sleeve is arranged around the heat pipe. The sleeve is made of hard plastic with a wall thickness of 5 mm.

[0089] Furthermore, in the above technical solution, the specific steps of assembling and filling multiple groups of casting modules 12 include:

[0090] Step 1: First, accurately locate and lay out the wall according to the designed position, determine the installation position between adjacent casting modules 12, and mark the corresponding contour line and center line on the foundation surface;

[0091] Step 2: Place the first pouring module 12 on the foundation, adjust its position and levelness, and control the error within 5 mm. Place the pouring modules 12 in the same horizontal row in sequence, and install pouring baffles 122 on both sides of the corresponding pouring modules 12.

[0092] Step 3: Place the iron core of the magnetic field generating device at the bottom of the casting module 12 corresponding to the position of the composite fiber layer, then wind the electromagnetic coil around the iron core, and connect the thyristor rectifier and AC power supply.

[0093] Step 4: Concrete of corresponding proportions is injected into the corresponding filler areas through the upper longitudinal connection unit 121 according to the thermal stress zones. During the concrete pouring process, a vibrator is used for vibrating. The vibrator is inserted to a depth of 300 mm. The vibrating time is based on the fact that no bubbles or slurry appear on the concrete surface.

[0094] Step 5: connect the heat pipes in the same horizontal row of longitudinal connection units 121 in series, extend the condensing section to the outside of the wall, and connect the heat sink, which is made of aluminum;

[0095] Step 6: After completing the assembly and pouring construction of the bottom layer of pouring modules 12, place the upper pouring modules 12 at the groove position corresponding to the upper longitudinal connecting unit 121, and assemble and pour the second horizontal row of pouring modules 12 according to the above steps. After gradually completing the construction of the entire wall, remove the pouring baffles 122 on both sides, smooth the wall surface, and make the wall surface flat and smooth.

[0096] Specifically, the principle of the present invention is: using finite element analysis to accurately simulate the thermal stress distribution of the wall, optimizing the material ratio according to the characteristics of different stress areas, such as using materials with good thermal insulation and low thermal expansion coefficient in high stress areas to reduce thermal stress; using ionic or magnetic principles through a composite fiber mesh structure lightweight partition to evenly distribute concrete aggregates in different partitions under the action of an electric field or a magnetic field and block the fusion of cement slurry, thereby ensuring that the performance of the partitions is independent and stable; using an energy-extracting structural heat pipe based on the principles of heat conduction and phase change, absorbing heat through evaporation of the working fluid and releasing heat through condensation, effectively regulating the internal temperature of the wall and reducing heat accumulation and thermal stress; the casting modules and longitudinal connection units in the prefabricated construction, with the help of reasonable structural design and connection methods, enhance the integrity of the wall and the convenience of construction, and ensure the efficient construction and performance improvement of ultra-thick concrete walls from a multi-dimensional synergistic effect.

[0097] Embodiment 1:

[0098] Taking a large cold storage with dimensions of 60m long, 30m wide, 6m high and 1.2m wall thickness as an example, the designed temperature inside the storage is -25℃, the local average annual ambient temperature is 16℃, and the maximum ambient temperature in summer can reach 33℃.

[0099] Simulate the wall to set up a prefabricated wall model sample that matches the construction unit's environment, and perform finite element analysis on the model sample:

[0100] ANSYS software was used to create a three-dimensional geometric model of the wall, and the wall was divided into hexahedral units with a side length of 0.5 m.

[0101] A temperature load of -25℃ is applied to the inner side of the wall. Considering the low air velocity in the cold storage, the convection heat transfer coefficient is set to 3.8W / (m2 ·K). The ambient temperature load is applied to the outside of the wall. In summer, it is calculated as 33℃, and the convection heat transfer coefficient is 7.5W / (m 2 ·K); in winter, the temperature is 16℃, and the convection heat transfer coefficient is 5.5W / (m 2 K). The bottom of the wall constrains vertical displacement, and the surrounding sides constrain horizontal displacement.

[0102] According to the temperature field results obtained by thermal analysis, structural mechanics analysis is performed to calculate the thermal stress of the wall caused by temperature changes:

[0103] In heat conduction calculations, according to Fourier's law

[0104] Where q is the heat flux, λ is the thermal conductivity, is the temperature gradient;

[0105] By setting the thermal conductivity of the material and the boundary temperature conditions, the software can calculate the temperature distribution inside the wall. When calculating thermal stress, based on the thermal expansion theory ε=αΔT (ε is thermal strain, α is the thermal expansion coefficient, ΔT is temperature change), combined with the elastic modulus E of the material, the thermal stress is calculated according to Hooke's law σ=Eε (σ is thermal stress).

[0106] Calculation principle: In heat conduction calculation, according to Fourier's law (where q is the heat flux, λ is the thermal conductivity, is the temperature gradient). By setting the thermal conductivity of the material and the boundary temperature conditions, the software can calculate the temperature distribution inside the wall.

[0107] When calculating thermal stress, based on the thermal expansion theory ε=αΔT (ε is thermal strain, α is the thermal expansion coefficient, and ΔT is temperature change), combined with the elastic modulus E of the material, the thermal stress is calculated according to Hooke's law σ=Eε (σ is thermal stress).

[0108] Among them, the material parameters are determined as:

[0109] The cement used is ordinary Portland cement (PO 42.5), with a density of 3.0g / cm 3 , thermal conductivity 1.7W / (m·K), specific heat capacity 0.9kJ / (kg·K).

[0110] Aggregates include crushed stone (particle size 5-20mm), river sand and added magnetic iron ore powder (particle size 0.1-1mm); crushed stone density 2.65g / cm 3 , thermal conductivity 3.2W / (m·K), specific heat capacity 0.8kJ / (kg·K); river sand density 2.6g / cm 3, thermal conductivity 2.8W / (m·K), specific heat capacity 0.9kJ / (kg·K); density of magnetic iron ore powder 5.0g / cm 3 , thermal conductivity 7.0W / (m·K), specific heat capacity 0.6kJ / (kg·K).

[0111] The thermal physical and mechanical properties of concrete with different mix ratios were tested. It was preliminarily determined that when the basic mix ratio was cement: fly ash: crushed stone: river sand: magnetic iron ore powder = 1:0.25:4:3:0.5 (mass ratio), the thermal expansion coefficient of concrete was 1.08×10 -5 / K, the elastic modulus is 33GPa, and this ratio is used as a preliminary reference ratio.

[0112] The insulation material is a 120 mm thick polyurethane foam board with a thermal conductivity of 0.023 W / (m·K).

[0113] Steady-state thermal analysis is performed to obtain the wall temperature field, and then structural mechanics analysis is performed to calculate thermal stress.

[0114] Different areas are divided according to the key points of thermal stress distribution, and the aggregate ratio is adjusted according to the area:

[0115] The simulation results show that the thermal stress at the bottom of the inner side and the top of the outer side of the wall is relatively large, with a maximum value of about 8MPa, which is a high stress area; the thermal stress in the middle of the wall is 3.5-6MPa, which is a medium stress area; the thermal stress in the rest of the wall is less than 3.5MPa, which is a low stress area.

[0116] The following is a table of 5 aggregate parameters for high stress areas:

[0117]

[0118] The following is a table of parameters for three types of aggregates in the medium stress zone:

[0119]

[0120] Low stress area: The low stress area maintains the original base ratio: cement: fly ash: crushed stone: river sand: magnetic iron ore powder = 1:0.25:4:3:0.5 (mass ratio), and its thermal expansion coefficient is 1.08×10 -5 / K, elastic modulus is 33GPa, and thermal conductivity is 1.7W / (m·K).

[0121] Based on the prefabricated wall structure, the construction structure is optimized and the filler is assembled for the ultra-thick concrete wall:

[0122] Step 1: A square steel frame is made as a skeleton according to the aspect ratio of a single casting module 12. The horizontal and vertical steel beams of the frame are made of high-strength angle steel to improve support and stability. A steel mesh is welded on the inner surface of the steel frame according to the position of the stress boundary partition. The aperture of the steel mesh is 50 mm × 50 mm. A composite fiber layer is fixed on the surface of the steel mesh. The composite fiber layer is a thin plate with a thickness of less than 6 mm made by mixing glass fiber and metal fiber and then pressing. Support steel bars are tied and welded horizontally and vertically on the inner side of the steel cross frame to form a steel cage.

[0123] The casting module adopts a steel frame with a frame angle of 55mm×55mm×5.5mm. The mesh aperture is 45mm×45mm.

[0124] The composite fiber mesh structure lightweight partition inside the module is made of a blend of carbon fiber and glass fiber (carbon fiber accounts for 52%), and metal fiber (stainless steel fiber) accounts for 16% of the total fiber mass. The partition thickness is 5.5mm and the mesh size is 20mm×20mm.

[0125] The diameter of the filler port in the high stress area is 190mm, that in the medium stress area is 210mm, and that in the low stress area is 230mm.

[0126] Step 2: Anchor bolts are welded at the top and bottom of the steel cage. The surface of the anchor bolts is threaded. The anchor bolts pass through the through holes on the longitudinal connection unit 121 and are locked and fixed with nuts. A groove is provided on the upper surface of the longitudinal connection unit 121 on the top side, and a protrusion matching the groove is provided on the lower surface of the longitudinal connection unit 121 on the bottom side, so as to facilitate the installation of two sets of steel cages adjacent to each other in the longitudinal direction. The reinforcing steel bars are passed through the gaps between the horizontal steel bars inside the longitudinal connection unit 121 and are welded and fixed to the supporting steel bars in the steel cage.

[0127] Step 3: Seal and protect the connection between the energy export structure 11 and the longitudinal connection unit 121, wherein the heat pipe is a copper tube with a diameter of 25 mm and filled with acetone; insert the heat pipe into the reserved through hole of the horizontal steel frame of the longitudinal connection unit 121, and fill the space between the heat pipe and the through hole with thermal conductive silicone to ensure good thermal conductivity. At the connection between the heat pipe and the longitudinal connection unit 121, high-temperature resistant sealant is used for sealing to prevent leakage of the working fluid. A protective sleeve is set around the heat pipe, and the sleeve is made of hard plastic with a wall thickness of 5 mm.

[0128] Step 4: assembling and filling multiple groups of casting modules 12;

[0129] After the foundation is leveled, position the casting module and the longitudinal connection unit. Install the first casting module first and adjust the horizontal error within 3.5mm;

[0130] Place the first pouring module 12 on the foundation, adjust its position and levelness, and control the error within 5 mm. Place the pouring modules 12 in the same horizontal row in sequence, and install pouring baffles 122 on both sides of the corresponding pouring modules 12.

[0131] Place the iron core of the magnetic field generating device at the bottom of the casting module 12 corresponding to the position of the composite fiber layer, then wind the electromagnetic coil around the iron core, and connect the thyristor rectifier and the AC power supply;

[0132] The magnetic field generating device uses an electromagnetic coil wrapped around the casting module. The electromagnetic coil is wound with a copper wire with 800 turns and a wire diameter of 2 mm. It is connected to the AC power supply through a thyristor rectifier, and the current can be adjusted to control the magnetic field strength.

[0133] Before pouring concrete, the electromagnetic coil is energized. According to the needs of different partitions, the current is adjusted to generate a magnetic field of appropriate strength in the area where the composite fiber layer is located. For high stress areas, the magnetic field strength is controlled at 0.6-0.8T; the magnetic field strength in medium stress areas is 0.4-0.6T; and the magnetic field strength in low stress areas is 0.2-0.4T.

[0134] Concrete and aggregate are injected into the corresponding partitions according to the steel wire mesh. During the concrete pouring process, due to the effect of the magnetic field, the magnetic iron ore powder is evenly dispersed in each partition under the action of the magnetic field force. The vibration time of the vibrating rod is 22-32 seconds, and the insertion depth is 280-380mm;

[0135] Connect the heat pipes in the same horizontal row of longitudinal connection units 121 in series, and extend the condensing section to the outside of the wall to connect the heat sink, which is made of aluminum;

[0136] After completing the assembly and pouring construction of the bottom layer of pouring modules 12, place the upper pouring modules 12 in the groove position corresponding to the upper longitudinal connecting unit 121, and assemble and pour the second horizontal row of pouring modules 12 according to the above steps. After gradually completing the construction of the entire wall, remove the pouring baffles 122 on both sides, smooth the wall surface, and make the wall surface flat and smooth.

Claims

1. A method for constructing an ultra-thick concrete wall, characterized in that: The following steps are involved: S10: Simulate the wall to set up a prefabricated wall model sample that matches the construction unit's environment, and perform finite element analysis on the model sample; S20: Perform structural mechanics analysis based on the temperature field results obtained from thermal analysis to calculate the thermal stress of the wall caused by temperature changes; S30: Divide different areas according to the key points of thermal stress value distribution, and adjust the aggregate ratio according to the area; S40: Optimize the construction structure based on the prefabricated wall structure and assemble fillers for ultra-thick concrete walls.

2. The method for constructing an ultra-thick concrete wall according to claim 1, characterized in that: The specific steps of setting up a prefabricated wall model sample matching the construction unit environment and performing finite element analysis on the model sample are as follows: The first step: firstly, a sample model is established according to the size of the construction unit, so as to facilitate steady-state thermal analysis of the inside and outside of the wall, and obtain the temperature field distribution of the wall under the action of the temperature difference between the inside and the outside. The sample model includes an environmental structure and a three-dimensional geometric model of an assembled wall structure. The assembled wall structure includes an ultra-thick wall frame (10). A plurality of groups of inner frame structures (101) are sequentially arranged on the ultra-thick wall frame (10) from top to bottom. The inner frame structure (101) includes a steel bar structure, and baffles (102) are respectively arranged on both sides. Concrete and aggregate fillers of the same proportion are injected into each layer of the inner frame structure (101) from top to bottom, wherein the concrete and aggregate fillers are divided into a plurality of units, and the unit type is selected as a solid unit that is convenient for simulating solid heat transfer and structural mechanics behavior; Step 2: Assign corresponding thermophysical and mechanical parameters of concrete and aggregate in the prefabricated wall sample model through the database of finite element analysis software; Step 3: Apply ambient temperature loads corresponding to the construction unit environment to the inner and outer sides of the assembled wall sample model; Step 4: Calculate the temperature value of each node inside the prefabricated wall sample model through finite element software, generate a temperature cloud map, intuitively display the temperature changes of the wall from the inside to the outside and from top to bottom, and output the thermal analysis results.

3. The method for constructing an ultra-thick concrete wall according to claim 2, characterized in that: The specific steps of performing structural mechanics analysis based on the temperature field results obtained by thermal analysis and calculating the thermal stress generated by the wall due to temperature changes include: Step 1: Calculate the thermal strain of each unit according to the thermal expansion coefficient and the temperature difference, and then calculate the thermal stress in combination with the elastic modulus of the current unit to obtain the thermal stress distribution cloud map; Step 2: Analyze the changing pattern of thermal stress from inside to outside and from top to bottom, and then determine the location where the maximum thermal stress occurs, which is the key point of wall cracking.

4. The method for constructing an ultra-thick concrete wall according to claim 3, characterized in that: The specific steps of dividing different areas according to the key points of thermal stress value distribution as boundaries and adjusting the aggregate ratio in combination with the areas include: Step 1: According to the distribution of thermal stress values, key points are divided into high stress area, medium stress area and low stress area. The high stress area is the location where the wall is prone to cracking. Step 2: Adjust the concrete and aggregate ratios for different partitions to reduce the temperature gradient and achieve stability of the wall structure by reducing the heat conduction efficiency. Step 3: Re-enter the thermophysical and mechanical parameters of the adjusted concrete and aggregate ratio into the finite element model, and conduct thermal stress simulation analysis again to ensure that the thermal stress at the key points after adjustment is reduced, so that the wall constructed according to the ratio in the later stage is more stable; Step 4: In order to further reduce the heat accumulation inside the wall, consider setting an energy extraction structure (11) in the wall based on the connection structure between adjacent inner frame structures (101).

5. The method for constructing an ultra-thick concrete wall according to claim 4, characterized in that: The specific steps of optimizing the construction structure based on the assembled wall structure and then starting the construction of the ultra-thick concrete wall include: The first step is to construct a plurality of casting modules (12) by compiling a reinforcement cage; Step 2: respectively fixing and connecting longitudinal connection units (121) at the top and bottom ends of the corresponding adjacent steel cages; Step 3: Coordinate and connect the energy output structure (11) and the longitudinal connection unit (121); Step 4: sealing and protecting the connection between the energy output structure (11) and the longitudinal connection unit (121); Step 5: assembling and filling multiple groups of casting modules (12).

6. The method for constructing an ultra-thick concrete wall according to claim 5, characterized in that: The specific steps of constructing a plurality of casting modules (12) by compiling a steel cage include: A square steel frame is manufactured as a skeleton according to the length-width ratio of a single casting module (12). The horizontal and vertical steel beams of the frame are made of high-strength angle steel to improve support and stability. A steel mesh is welded on the inner surface of the steel frame according to stress limit zones. The aperture of the steel mesh is 50 mm×50 mm. A composite fiber layer is fixed on the surface of the steel mesh. The composite fiber layer is a thin plate with a thickness of less than 6 mm made by mixing and weaving glass fibers and metal fibers and then pressing them. Support steel bars are tied and welded horizontally and vertically on the inner side of the steel cross frame to form a steel cage.

7. The method for constructing an ultra-thick concrete wall according to claim 6, characterized in that: The specific steps of respectively fixing and connecting the top ends and bottom ends of the corresponding adjacent steel cages with the longitudinal connection units (121) include: Anchor bolts are welded at the top and bottom of the steel cage, and the surfaces of the anchor bolts are threaded. The anchor bolts pass through the through holes on the longitudinal connection unit (121), and the longitudinal connection unit (121) is fixedly installed by locking with nuts, wherein the upper surface of the longitudinal connection unit (121) on the top side is provided with a groove, and the lower surface of the longitudinal connection unit (121) on the bottom side is provided with a protrusion adapted to the groove, so as to facilitate the installation of two sets of longitudinally adjacent steel cages; the reinforcing steel bars are passed through the gaps between the internal horizontal steel bars of the longitudinal connection unit (121), and are fixedly welded to the supporting steel bars in the steel cage.

8. The method for constructing an ultra-thick concrete wall according to claim 7, characterized in that: The specific steps of coordinating and connecting the energy output structure (11) and the longitudinal connection unit (121) include: The heat pipe is a copper tube with a diameter of 25 mm, and is filled with a low boiling point working fluid such as acetone. The heat pipe is inserted into the reserved through hole of the horizontal steel frame of the longitudinal connection unit (121), and the space between the heat pipe and the through hole is filled with thermal conductive silicone to ensure good thermal conductivity. The length of the evaporation section of the heat pipe is determined according to the thermal stress distribution of the wall.

9. The method for constructing an ultra-thick concrete wall according to claim 8, characterized in that: The specific steps of sealing and protecting the connection between the energy output structure (11) and the longitudinal connection unit (121) include: A high temperature resistant sealant is used to seal the connection between the heat pipe and the longitudinal connection unit (121) to prevent leakage of the working fluid. A protective sleeve is provided around the heat pipe. The sleeve is made of hard plastic and has a wall thickness of 5 mm.

10. The method for constructing an ultra-thick concrete wall according to claim 9, characterized in that: The specific steps of assembling and filling the multiple groups of casting modules (12) include: Step 1: First, accurately position and lay out the wall according to the designed position, determine the installation position between adjacent casting modules (12), and mark the corresponding contour line and center line on the foundation surface; Step 2: Place the first pouring module (12) on the foundation, adjust its position and levelness, control the error within 5 mm, complete the placement of the pouring modules (12) in the same horizontal row in sequence, and install pouring baffles (122) on both sides of the corresponding pouring modules (12); Step 3: Place the iron core of the magnetic field generating device at the bottom of the casting module (12) at a position corresponding to the composite fiber layer, then wind the electromagnetic coil around the iron core, and connect the silicon controlled rectifier and AC power supply. Step 4: Concrete of corresponding proportions is injected into the corresponding filler areas through the upper longitudinal connection unit (121) according to the thermal stress zones. During the concrete pouring process, a vibrator is used for vibrating. The vibrator is inserted to a depth of 300 mm. The vibrating time is based on the fact that no bubbles or slurry appear on the concrete surface. Step 5: connect the heat pipes in the same horizontal row of longitudinal connection units (121) in series, extend the condensing section to the outside of the wall, and connect the heat sink, which is made of aluminum; Step 6: After completing the assembly and pouring construction of the bottom layer of pouring modules (12), place the upper layer of pouring modules (12) at the groove position corresponding to the upper longitudinal connection unit (121), and assemble and pour the second horizontal row of pouring modules (12) according to the above steps. After gradually completing the construction of the entire wall, remove the pouring baffles (122) on both sides, and smooth the wall surface to make the wall surface flat and smooth.

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