Arc-shaped section lining plate concrete internal and external temperature difference control heat preservation design method

Abstract

The application provides a design method for controlling temperature difference between inside and outside of arc section lining plate concrete, comprising: step 1, analyzing the crack prevention data of the arc section lining plate concrete in the cavern to obtain calculation parameter information; step 2, calculating the allowable temperature difference between inside and outside of the arc section lining plate concrete according to the obtained calculation parameter information, that is, 【△T nw 】=0.74α×C-20.25H / (2πR)+0.15H×C+0.04E-0.23C-0.81T a +27.57, wherein, α is the fly ash mixing amount, R is the arc section inside radius, C is the 90d design age strength grade of the lining plate concrete, H is the concrete plate thickness, E is the surrounding rock deformation modulus, and T a is the cavern inside air temperature value during the concrete pouring period; step 3, calculating the temperature difference between inside and outside of the arc section lining plate concrete, that is, △T nw ; and step 4, designing the heat preservation measures according to △T nw and 【△T nw 】.

Description

Technical Field

[0001] This invention belongs to the field of concrete temperature crack control technology, specifically involving a thermal insulation design method for controlling the internal and external temperature difference of arc-shaped cross-section lining concrete. Background Technology

[0002] Arc-shaped cross-section lining is a structure widely used in underground cavern engineering projects such as hydraulic tunnels. Figure 1 The internal and external temperature difference refers to the difference between the highest internal temperature and the surface temperature of concrete, and it plays a crucial role in the formation of temperature cracks, especially early surface cracks. Under the same conditions, concrete structures of different forms and sizes exhibit significant differences in internal and external surface temperature differences and their permissible variations. There are no regulations regarding the control of internal and external temperature differences in the lining concrete of hydraulic tunnels and other related structures. For tunnel lining concrete, since the air temperature varies less than in the natural environment, surface covering or wrapping insulation is not used; instead, the tunnel opening is sealed for insulation as needed. However, there has been no specific research on the control or design calculation of the internal and external temperature difference of tunnel lining concrete. Because the internal and external temperature difference is a significant factor in the formation of temperature cracks, and the lining slab is thin, the resulting surface geometric temperature gradient is particularly large, which is a major cause of early surface cracks. Water cooling aims to reduce both the highest internal temperature and the internal and external temperature difference. However, there are no standards for the permissible internal and external temperature difference control of underground tunnel lining concrete.

[0003] Therefore, it is urgent to study the internal and external temperature difference of the concrete lining slab of the arc-shaped section of underground cavern, and to propose a simple, accurate, and rapid method for calculating the allowable internal and external temperature difference and its allowable value, for use in the thermal insulation design of closed cavern openings. Summary of the Invention

[0004] The purpose of this invention is to provide a design method for controlling the internal and external temperature difference of the concrete in an arc-shaped cross-section lining slab, so as to optimize the control of temperature cracks in the lining slab concrete and quickly apply it to the design of internal and external temperature difference control and sealing of openings.

[0005] To achieve the above objectives, the present invention employs the following solution:

[0006] like Figure 2 As shown, the present invention provides a method for thermal insulation design of concrete with arc-shaped cross-section lining slab for controlling the temperature difference between the inside and outside, characterized by comprising the following steps:

[0007] Step 1. Analyze the temperature control and crack prevention data of the concrete in the arc-shaped cross-section lining slab inside the tunnel to obtain calculation parameter information;

[0008] Step 2. Calculate the allowable internal and external temperature difference [△T] of the concrete in the arc-shaped cross-section lining slab based on the obtained calculation parameter information. nw (°C):

[0009]

△T nw

[0010] In the formula: α is the fly ash content, for example, if the content is 20%, then α = 0.2; R is the inner radius of the arc-shaped cross-section (m); C is the 90-day design strength grade of the lining concrete (MPa), such as C 90 40, then C = 40. If the lining concrete is designed with a strength grade of 28 days, it needs to be converted to a strength grade of 90 days according to the specifications; H is the thickness of the concrete slab (m); E is the deformation modulus of the surrounding rock (GPa); T a The temperature inside the underground cavern during the concrete pouring period is T. If the cavern opening is sealed for insulation during construction, causing the air temperature inside the underground cavern to rise, then T... a The increased air temperature inside the cave should be adopted;

[0011] Step 3. Calculate the temperature difference ΔT between the inside and outside of the concrete of the arc-shaped cross-section lining slab based on the obtained calculation parameter information. nw (°C);

[0012] Step 4. Based on △T nw and [△T] nw Design insulation measures.

[0013] Preferably, the thermal insulation design method for controlling the internal and external temperature difference of the arc-shaped cross-section lining concrete provided by the present invention may also have the following characteristics: In step 1, analyzing the temperature control and crack prevention data of the arc-shaped cross-section lining concrete in the tunnel includes: collecting and analyzing the engineering overview of the arc-shaped cross-section lining concrete structure in the tunnel, hydrological and meteorological conditions, and concrete temperature control design technical requirements. The obtained calculation parameter information includes: fly ash content, inner radius of the arc-shaped cross-section, 90-day design age strength grade of the lining concrete, concrete slab thickness, deformation modulus of the surrounding rock, air temperature value in the tunnel during concrete pouring, water flow temperature effect value, and convection coefficient of the concrete surface.

[0014] Preferably, in the thermal insulation design method for controlling the internal and external temperature difference of the concrete in the arc-shaped cross-section lining slab provided by the present invention, in step 3, the internal and external temperature difference ΔT of the concrete in the arc-shaped cross-section lining slab is calculated using the following formula. nw (°C):

[0015] △T nw =0.0883C + 0.59T0 + 0.12T g -0.83T a -0.03S b +0.04H×C+0.132H×T0-0.10H×Tg -0.01T0×T g -0.00C×H×T0+21.06 (Formula 2) Where: T0 is the pouring temperature (°C); T g T represents the water flow temperature effect value (°C). g =35-T w T w The water temperature (T is taken as the water temperature when water cooling is not performed) w =35℃); S b Convection coefficient of concrete surface, unit: kJ / (m²) 2 ·h·℃); the rest are the same as before.

[0016] Preferably, the thermal insulation design method for controlling the internal and external temperature difference of the arc-shaped cross-section lining slab concrete provided by the present invention may also have the following characteristics: the convection coefficient S of the concrete surface when different moisturizing curing methods are adopted. b Take different values: For manually controlled watering maintenance, S b =100kJ / (m 2 (·h·℃); Automatic and intelligent control, 90% moisturizing and maintenance, S b =150kJ / (m 2 (·h·℃); Automatic and intelligent control, 95% moisturizing and maintenance, S b =200kJ / (m 2 ·h·℃).

[0017] Preferably, the thermal insulation design method for controlling the internal and external temperature difference of the arc-shaped cross-section lining slab concrete provided by the present invention includes the following sub-steps in step 4:

[0018] Step 4.1 Compare and analyze the internal and external temperature difference ΔT nw Does it exceed the allowable value? [△T] nw 】;

[0019] Step 4.2 If △T nw ≤

【△T nw If △T nw >

【△T nw If the opening is sealed, it will be kept warm.

[0020] Preferably, the thermal insulation design method for controlling the internal and external temperature difference of the arc-shaped cross-section lining slab concrete provided by the present invention may also have the following characteristics: In step 4.2, if [△T] nw 】<△T nw ≤

【△T nw If the temperature is +2.0℃, a simple curtain should be used to seal the opening for insulation, allowing for ventilation or gaps; if [△T] nw +2.0℃ < △Tnw ≤

【△T nw If the temperature exceeds +5.0℃, stricter insulation measures will be taken to seal the opening; △T nw >

【△T nw If the temperature is above 5.0℃, strict measures should be taken to seal the opening and insulate it, and no ventilation gaps are allowed.

[0021] Preferably, the thermal insulation design method for controlling the internal and external temperature difference of the arc-shaped cross-section lining slab concrete provided by the present invention may also have the following characteristics: such as Figure 3 As shown, the simple curtain-style insulation measure for sealing openings refers to a method of sealing openings by hanging thin geotextiles, plastic films, etc., to cover the opening. However, the strips / blocks are not tightly bonded, resulting in ventilation holes or gaps. For example... Figure 4 As shown, a more stringent insulation measure for sealed openings refers to strictly sealing each opening in upper and lower sections according to the structure of the inlet trash rack, with an insulation level between simple and strict insulation measures; for example... Figure 5 As shown, strict sealing of the opening and insulation measures refer to the method of sealing the opening by using thick insulation blankets, cotton felts, etc. to strictly fix the entire opening and seal it. The sealed structure forms a whole and there are no gaps for ventilation.

[0022] In addition, step 2 above calculates the allowable internal and external temperature difference [△T] of the concrete in the arc-shaped cross-section lining slab. nw The reliability of Formula 1 was verified as follows: Taking the circular cross-section side arch of a large domestic hydraulic tunnel as an example, the three-dimensional finite element method was used to simulate the temperature and temperature stress of 125 schemes with different thicknesses and inner radii of lining plates, different strength grades, different tunnel air temperatures, different fly ash content of lining concrete, and different temperature control measures. The internal and external temperature differences of 86 schemes with a crack resistance safety factor greater than 1.0 were listed in Table 1, and then these data were statistically analyzed. Since the crack resistance safety factor K corresponding to the internal and external temperature differences of these 86 schemes is greater than 1.0, as long as the internal and external temperature difference of the arc-shaped cross-section lining plate concrete does not exceed the calculated value of Formula 1, surface temperature cracks will not occur. This confirms that the calculation result of Formula 1 can be used as the allowable internal and external temperature difference [△T]. nw 】

[0023] Table 1. Simulation results of temperature difference between the inside and outside of the concrete in the arc-shaped cross-section lining slab (K>1.0)

[0024]

[0025]

[0026]

[0027]

[0028] Step 3: Calculate the temperature difference ΔT between the inside and outside of the concrete in the arc-shaped cross-section lining slab. nw Formula 2's reliability was verified as follows: Taking the circular cross-section side arch of a large domestic hydraulic tunnel as an example, the three-dimensional finite element method was used to simulate the temperature and temperature stress of 125 schemes under different thicknesses and inner radii of the arc-shaped cross-section lining plate, different strength grades, different tunnel air temperatures, different fly ash content lining concrete pouring conditions, and different temperature control measures. The internal and external temperature differences of each scheme are listed in Table 2. Then, statistical analysis of these data confirmed that the calculation results are basically consistent with the measured conditions. In addition, the statistical analysis results show that the internal and external temperature difference ΔT of the arc-shaped cross-section lining plate concrete is basically consistent with the measured conditions. nw It is unrelated to the amount of fly ash added.

[0029] Table 2 Simulation results of temperature difference between the inside and outside of the concrete in the arc-shaped cross-section lining slab.

[0030]

[0031]

[0032]

[0033]

[0034] The role and effect of invention

[0035] This invention relates to a method for controlling the internal and external temperature difference in concrete for curved cross-section lining slabs, and for the first time proposes an allowable internal and external temperature difference [△T] applicable to concrete for curved cross-section lining slabs. nw [and the actual internal and external temperature difference ΔT] nw A high-precision scientific calculation method was used to calculate the allowable internal and external temperature difference [△T] based on factors such as the inner radius of the arc-shaped cross-section, fly ash content, lining structure thickness and strength, surrounding rock deformation modulus, casting parameters, moisture retention and curing methods, and humidity. nw [and the actual internal and external temperature difference ΔT] nw Based on the numerical comparison results of the two, we can quickly design the insulation measures for the closed openings that need to be taken in the low-temperature season, so as to provide targeted insulation measures for the concrete of the arc-shaped cross-section lining slab, effectively control the temperature difference between the inside and outside, and avoid the generation of surface cracks. Attached Figure Description

[0036] Figure 1 The present invention relates to the cross-section of the arc-shaped lining plate of a hydraulic tunnel (unit: m);

[0037] Figure 2 The flowchart is a design method for controlling the internal and external temperature difference of concrete in arc-shaped cross-section lining slabs, which is involved in this invention.

[0038] Figure 3 This is a schematic diagram of the simple enclosed opening insulation and draft prevention insulation structure involved in this invention;

[0039] Figure 4 The present invention relates to the construction drawing of the insulation structure for the strictly sealed entrance of the Baihetan Hydropower Diversion Tunnel, which is used for insulation and prevention of drafts.

[0040] Figure 5 This is a schematic diagram of the strictly sealed opening insulation structure involved in this invention;

[0041] Figure 6 This invention relates to a cross-sectional view of a 0.8m thick arc-shaped lining plate on the upper horizontal section of a power generation water diversion tunnel.

[0042] Figure 7 This invention relates to a cross-sectional view of a 1.0m thick arc-shaped lining plate on the upper horizontal section of the Baihetan Power Generation Water Diversion Tunnel. Detailed Implementation

[0043] The following, in conjunction with the accompanying drawings, uses the arc-shaped lining concrete of different parts of the Baihetan Hydropower Station's power generation and water diversion tunnel as an example to illustrate the specific implementation scheme of the thermal insulation design method for controlling the internal and external temperature difference of the arc-shaped lining concrete involved in this invention.

[0044] <Temperature Control Data for Lining Concrete of Baihetan Hydropower Station Diversion Tunnel Project>

[0045] The Baihetan Hydropower Station, with an installed capacity of 16,000 MW, is the world's second largest hydropower station (after the Three Gorges Dam). The station has an average annual power generation of 62.443 billion kWh. The reservoir has a total capacity of 20.627 billion m³. The main engineering works consist of the dam, flood discharge and energy dissipation structures, and the water diversion and power generation system. The underground powerhouse system adopts a headwaters development scheme, with units symmetrically arranged on the left and right banks, each housing eight turbine generator units. The water diversion tunnel uses a single-unit, single-pipe water supply system, while the tailrace system uses a shared tailrace tunnel for two units, with four tailrace tunnels on each of the left and right banks.

[0046] The water diversion tunnel consists of a transition section, an upper horizontal section, a narrowing section, an upper bend section, a shaft section, a lower bend section, and a lower horizontal section. The transition section, upper horizontal section, and narrowing section are lined with reinforced concrete of type C. 90 25; The upper bend section, vertical shaft section, lower bend section, and lower horizontal section are lined with steel plates. The transition section adopts a flat slope layout, with the axis perpendicular to the water intake tower, gradually changing from a rectangular cross-section to a circular cross-section; the upper horizontal section adopts a circular cross-section, with two different lining thicknesses of 0.8m and 1.0m. Figure 6 , Figure 7 ).

[0047] The power generation water diversion tunnel uses low-heat cement concrete, and the maximum allowable temperature is shown in Table 3. The standard for pouring temperature control is 18℃ from April to September and 15℃ from October to March of the following year.

[0048] Table 3. Maximum Allowable Temperature for Concrete Lining of Power Generation Water Diversion Tunnel (Low-Heat Cement)

[0049]

[0050] To control the pouring temperature and maximum temperature of concrete, comprehensive measures are taken from aspects such as controlling the heat of hydration of concrete, the temperature upon entering the formwork, water cooling, surface protection, and overall management.

[0051] (1) Controlling the heat of hydration includes: optimizing the concrete mix proportion and reducing the amount of cement; selecting low-heat silicate cement and adding high-quality fly ash and high-efficiency water-reducing agent; pouring low-slump concrete, with the slump of the bottom slab and side wall concrete controlled at 5-8cm, and the slump of the top arch pumped concrete controlled at 11-16cm; using ready-mixed concrete and controlling the outlet temperature at 14℃.

[0052] (2) Control the temperature of concrete entering the placement chamber and the pouring temperature. During the transportation of concrete mix, shading and heat insulation measures such as sunshade cloth should be taken to avoid prolonged exposure to sunlight or rain. When the outside temperature is higher than 23℃, necessary water spraying should be carried out intermittently on the outside of the truck bed before loading to lower the temperature inside the truck bed. After the concrete enters the placement chamber, it should be leveled and vibrated promptly to accelerate the covering speed and shorten the exposure time; when the temperature is high, the surface of the placement chamber should be sprayed to lower the ambient temperature inside the concrete placement chamber.

[0053] (3) Water cooling. Cooling water pipes are buried parallel to the water flow direction in the middle of the lining thickness, with a lining thickness not exceeding 1.5m and a single row arrangement at 1.0m intervals. High-density polyethylene PVC pipes are used, with an outer diameter of Φ32mm and a wall thickness of 2mm. The water cooling flow rate is controlled between 1.5 and 2.0m. 3 The water flow direction changes every 24 hours. The inlet water temperature is controlled at 12-18℃ (cooled water), with a maximum temperature difference of less than 25℃ between the water and the concrete interior, and a daily temperature drop of less than 1.0℃. Water cooling begins when the concrete is poured, lasting 15-20 days, and the internal concrete temperature does not exceed 25℃ at the end of the cooling period. Concrete surface protection is implemented. Within a 50m section at the tunnel entrance, a 3cm thick polyethylene insulation blanket is immediately covered for 30 days after formwork removal. From October to March of the following year, the tunnel entrances and exits (including construction adits and ventilation tunnels) are sealed and insulated to reduce airflow within the tunnel.

[0054] <Example 1> Insulation Design Method for Controlling Inner and Outer Temperature Difference of Concrete with 0.8m Thick Arc-shaped Cross-section Lining Slab for Power Generation Water Diversion Tunnel in Winter

[0055] The power generation water diversion tunnel has a circular cross-section and a lining thickness of 0.8m. Circumferential construction joints are set every 8m to 12m (generally every 12m) along the tunnel's axis. The surrounding rock is Class II, and the lining slab is C. 90 25 Low-heat concrete, mixed with 25% fly ash, such as Figure 6 As shown. The concrete was poured in two stages: first the side arch, then the rear arch. Basic temperature control data is the same as above. Curing was carried out for 90 days using a smart system with ambient temperature tap water to maintain 95% humidity.

[0056] Based on the above temperature control data, the construction unit proposes the following temperature control measures for the lining concrete pouring: pouring at T0 = 18℃ in winter, without water cooling, and the formwork removal time t... m =3d. The temperature inside the tunnel is relatively high. The power generation tunnel is longer and has worse ventilation conditions than the diversion tunnel and the flood discharge tunnel. Referring to the temperature monitoring data of the diversion tunnel, the average annual temperature is 16-26℃ under the condition of no sealed tunnel entrance insulation.

[0057] like Figure 2 As shown in this embodiment, the thermal insulation design method for controlling the internal and external temperature difference of the arc-shaped cross-section lining slab concrete includes the following:

[0058] Step 1. Analyze the temperature control and crack prevention data of the arc-shaped cross-section lining concrete inside the tunnel. Since the Baihetan Hydropower Station is a mega-project, and the power generation tunnel and other structures are classified as Class I structures, temperature control and crack prevention of the lining concrete are crucial. Based on design requirements, effective temperature control measures need to be implemented. Taking the pouring in January as an example, the internal air temperature is calculated using a cosine function, taking the smaller value T. a =16℃.

[0059] Step 2. Calculate the allowable internal and external temperature difference of the concrete in the arc-shaped cross-section lining slab [△T] nw [H = 0.8m, R = 7.0m, E = 20GPa, C = 25MPa, T] a Substituting 16℃ and α=0.25 into (Formula 1) yields [△T] nw = 16.92℃.

[0060] Step 3. Calculate the temperature difference ΔT between the inside and outside of the concrete in the arc-shaped cross-section lining slab. nw The concrete of the arc-shaped cross-section lining slab has a diameter of H = 0.8m, a pressure of C = 25MPa, and a tensile strength of T. a =16℃, α=0.25, T0=18℃, intelligent control 95% moisturizing and nourishing S b =200kJ / (m2·h·℃), without water cooling T g Substituting 0 into (Formula 2) yields △T. nw =17.3℃.

[0061] Step 4. Design insulation measures for the sealed opening. This includes:

[0062] Step 4.1 Compare and analyze the internal and external temperature difference ΔT nw Does it exceed the allowable value? [△T] nw 】:△T nw =17.3℃>

【△T nw = 16.92℃.

[0063] Step 4.2 Because △T nw =17.3℃>

△T nw The temperature is 16.92℃, which is only 0.38℃ higher than the target temperature. [△T] nw

【△T nw +2.0℃, therefore adopt Figure 3 A simple curtain can be used to seal the opening and keep it warm.

[0064] <Example 2> Summer Construction Method for Controlling Insulation of Internal and External Temperature Difference in 1.0m Thick Arc-Shaped Cross-Section Lining Slab for Power Generation Water Diversion Tunnel

[0065] The power generation water diversion tunnel has a circular cross-section and a lining thickness of 1.0m. Circumferential construction joints are set every 8m to 12m (generally every 12m) along the tunnel's axis. The surrounding rock is Class III, and the lining slab is C. 90 25 Low-heat concrete, mixed with 25% fly ash, such as Figure 7 As shown. The concrete was poured in two stages: first the side arch, then the rear arch. Basic temperature control data is the same as above. Curing was carried out for 90 days using tap water at room temperature.

[0066] Based on the above temperature control data, the construction unit proposes the following temperature control measures for the lining concrete pouring: In summer, pour at T0 = 20℃, without water cooling, and the formwork removal time t... m =3d. The temperature inside the tunnel is relatively high. The power generation tunnel is longer and has worse ventilation conditions than the diversion tunnel and the flood discharge tunnel. Referring to the temperature monitoring data of the diversion tunnel, the average annual temperature is 16-26℃ under the condition of no sealed tunnel entrance insulation.

[0067] like Figure 2 As shown in this embodiment, the thermal insulation design method for controlling the internal and external temperature difference of the arc-shaped cross-section lining slab concrete includes the following:

[0068] Step 1. Analyze the temperature control and crack prevention data of the arc-shaped cross-section lining concrete inside the tunnel. Since the Baihetan Hydropower Station is a mega-project, and the power generation tunnel and other structures are classified as Class I structures, temperature control and crack prevention of the lining concrete are crucial. Based on design requirements, effective temperature control measures need to be implemented. Taking the pouring in July as an example, the summer temperature inside the tunnel is calculated using a cosine function, taking the maximum value Ta = 26℃.

[0069] Step 2. Calculate the allowable internal and external temperature difference of the concrete in the arc-shaped cross-section lining slab [△T] nwSubstituting H = 1.0m, R = 7.0m, E = 15GPa, C = 25MPa, Ta = 26℃, and α = 0.25 into formula (1), we can calculate [△T]. nw = 8.02℃.

[0070] Step 3. Calculate the temperature difference ΔT between the inside and outside of the concrete in the arc-shaped cross-section lining slab. nw The concrete of the arc-shaped cross-section lining slab has a strength of H = 1.0m, C = 25MPa, and T. a =26℃, α=0.25, T0=20℃, intelligent control 95% moisturizing and nourishing S b =200kJ / (m2·h·℃), without water cooling T g Substituting 0 into (Formula 2) yields △T. nw =11.13℃.

[0071] Step 4. Design insulation measures for the sealed opening. This includes:

[0072] Step 4.1 Compare and analyze the internal and external temperature difference ΔT nw Does it exceed the allowable value? [△T] nw 】:△T nw =11.13℃>

【△T nw = 8.02℃.

[0073] Step 4.2 Due to △T nw =11.13℃>

△T nw

[0074] Based on the above calculations and analysis, for concrete pouring in winter, △T nw >【△T nw At 0.38℃, simple measures such as hanging curtains to seal the opening for insulation are needed; △T is required when pouring lining concrete in summer. nw -【△T nw The temperature is 3.11℃, which is higher than 2.0℃ but lower than 5.0℃, therefore, it is advisable to take [measures]. Figure 4 Stricter insulation measures should be implemented for sealed openings. Considering the requirements for pouring lining concrete in winter and summer, year-round insulation is recommended. Figure 4 Stricter insulation measures were implemented for the sealed openings.

[0075] In the actual project, the concrete lining of the Baihetan Hydropower Station's water diversion tunnel (i.e., the entrance, with a circular cross-section) was poured at 20℃ in summer and 16℃ in winter, and measures were taken to ensure its integrity. Figure 4Strict insulation measures were implemented at the tunnel entrances (each entrance was strictly sealed in upper and lower sections based on the imported trash rack structure). During construction, some entrances had gaps due to insufficient protection for personnel and equipment access. However, the strict sealing of the entrances was effective, resulting in no temperature cracks in the lining concrete (for details on temperature and temperature crack control, see "Theory and Application of Temperature Crack Control in Hydraulic Tunnel Lining Concrete" by Duan Yahui, Fan Qixiang, et al., China Water Resources and Hydropower Press, November 2021). This demonstrates that the above calculation and analysis results are consistent with the actual engineering situation.

[0076] The above embodiments are merely illustrative examples of the technical solution of the present invention. The method for controlling the internal and external temperature difference of concrete in arc-shaped cross-section lining slabs, as described in the present invention, is not limited to the content described in the above embodiments, but is defined by the scope of the claims. Any modifications, additions, or equivalent substitutions made by those skilled in the art based on these embodiments are within the scope of protection claimed by the claims of the present invention.

Claims

1. A method for controlling the temperature difference between the inside and outside of concrete in an arc-shaped cross-section lining plate, characterized in that, The method comprises the following steps: Step 1. Analyzing the data of temperature control and crack prevention of the concrete of the arc-shaped section lining plate in the chamber to obtain calculation parameter information; Step 2. Calculate the allowable internal and external temperature difference of the arc-shaped section lining plate concrete 【△T nw 】 according to the obtained calculation parameter information [△T nw ] = 0.74a x C - 20.25H / (2πR) + 0.15H x C + 0.04E - 0.23C - 0.81T a + 27.57 (Equation 1) In the formula, a is the fly ash content; R is the inner radius of the arc section; C is the 90d design age strength grade of the lining plate concrete; H is the thickness of the concrete plate; E is the deformation modulus of the surrounding rock; T a is the air temperature value in the chamber during the concrete pouring period; Step 3. Calculate the temperature difference between the inside and outside of the arc-shaped section lining plate concrete according to the obtained calculation parameter information nw ; Step 4. Insulation measures are designed according to ΔΤ nw and 【ΔΤ nw 】 In step 3, the temperature difference ΔT between the inner and outer concrete of the arc-shaped section lining plate is calculated by the following formula nw : ΔT nw = 0.0883C + 0.59T0+ 0.12T g - 0.83T a - 0.03S b + 0.04HxC + 0.132HXT0- 0.10HXT g - 0.01T0XT g - 0.00C x H x T0+ 21.06 (Formula 2) where: T0 is the pouring temperature; T g is the water temperature effect value; S b is the concrete surface convection coefficient.

2. The temperature difference control and heat preservation design method for the arc-shaped section lining plate concrete according to claim 1, characterized in that: wherein, The calculation parameter information obtained in step 1 includes: fly ash mixing amount, inner radius of the arc-shaped section, 90d design age strength grade of the lining plate concrete, thickness of the concrete plate, deformation modulus of the surrounding rock, air temperature value in the chamber during concrete pouring period, water passing temperature effect value, and concrete surface convection coefficient.

3. The temperature difference control and heat preservation design method for the arc-shaped section lining plate concrete according to claim 1, characterized in that: wherein the taking Convection coefficient S of concrete surface under different moisturizing curing methods b Take different values: For manually controlled watering maintenance, S b =100kJ / (m 2 (·h·℃); Automatic and intelligent control provides 90% moisturizing and maintenance, S b =150kJ / (m 2 (·h·℃); Automatic and intelligent control, 95% moisturizing and maintenance, S b =200kJ / (m 2 ·h·℃).

4. The temperature difference control and heat preservation design method for the arc-shaped section lining plate concrete according to claim 1, characterized in that: wherein Step 4 includes the following sub-steps: Step 4.1 Compare inner and outer temperature difference ΔT nw Whether the allowable value 【ΔT nw 】 is exceeded; Step 4.2 If ΔT nw ≤ 【△T nw 】, no need to take the heat preservation measures to close the hole; if ΔT nw > 【△T nw 】, close the hole heat preservation.

5. The method of claim 4, wherein the temperature control design method of the arc-shaped lining plate concrete is controlled by the internal and external temperature difference. Characterized in that: Wherein, In step 4.2, if 【△T nw 】<△T nw ≤【△T nw 】+2.0℃, then take simple curtain closing opening insulation measures, allowing the existence of air leakage or gap; if 【△T nw 】+2.0℃<△T nw ≤【△T nw 】+5.0℃, then take more stringent closing opening insulation measures; △T nw >【△T nw 】+5.0℃, then take strict closed hole insulation measures, not allowed to exist through the gap.

6. The temperature difference control and heat preservation design method for the arc-shaped section lining plate concrete according to claim 5, characterized in that: wherein The simple curtain sealing and heat preservation measure for the hole is a sealing and hole closing method in which a small thickness of geotextile and plastic film is suspended to cover the hole, and the combination between each strip / block is not tight, and there are air leakage holes or gaps; The relatively strict sealing and heat preservation measure for the hole is a sealing and hole closing method in which the inlet is strictly sealed according to the structure of the trash rack, and each hole is divided into upper and lower sections, and the heat preservation degree is between the simple and strict heat preservation measures; The strict sealing and heat preservation measure for the hole is a sealing and hole closing method in which thick and solid heat preservation blankets and cotton felt are strictly fixed to seal the hole as a whole, and the sealing structure forms a whole without air leakage gaps.

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