CN115455532A - Arc-section lining plate concrete internal and external temperature difference control heat preservation design method - Google Patents
Arc-section lining plate concrete internal and external temperature difference control heat preservation design method Download PDFInfo
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- 238000004321 preservation Methods 0.000 title claims abstract description 55
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 27
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- 229910000831 Steel Inorganic materials 0.000 description 1
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Abstract
The invention provides a concrete internal and external temperature difference control heat preservation design method for an arc-shaped section lining plate, which comprises the following steps: step 1, analyzing temperature control and crack prevention data of concrete of the arc-shaped section lining plate in the cavern to obtain calculation parameter information; step 2, calculating the allowable internal and external temperature difference (delta T) of the concrete of the lining plate of the arc section according to the obtained calculation parameter information nw 】＝0.74α×C‑20.25H/(2πR)+0.15H×C+0.04E‑0.23C‑0.81T a +27.57, wherein: alpha is the blending amount of the fly ash; r is the inner radius of the arc-shaped section; c, designing age strength grade for lining plate concrete 90 d; h is the thickness of the concrete slab; e is the deformation modulus of the surrounding rock; t is a The value is the air temperature value in the cavern in the concrete pouring period; step 3, calculating the inside and outside temperature difference Delta T of the concrete of the lining plate with the arc section nw (ii) a Step 4. According to Delta T nw And [ Delta T ] nw Design heat preservation measures.
Description
Technical Field
The invention belongs to the technical field of concrete temperature crack control, and particularly relates to a design method for controlling heat preservation by controlling internal and external temperature difference of arc-shaped section lining plate concrete.
Background
The arc-shaped section lining is a structure (figure 1) widely adopted by underground cavern engineering such as hydraulic tunnels and the like, and the internal and external temperature difference refers to the difference between the highest temperature inside concrete and the surface temperature of the concrete, and is an important role in generating concrete temperature cracks, particularly early surface cracks. In concrete structures of different forms and sizes, the internal surface temperature difference and the allowable internal surface temperature difference are obviously different under the same conditions. The regulation of the temperature difference control inside and outside the lining concrete is not provided in the relevant regulations of hydraulic tunnels and the like. For the lining concrete in the tunnel, because the temperature is less than the amplitude of the natural environment, surface covering or wrapping heat preservation can not be adopted, but closed tunnel opening heat preservation is adopted according to the requirement, but no special research related to the control of the temperature difference between the inside and the outside of the lining concrete in the tunnel or design calculation is available so far. Because the inside and outside temperature difference is an important factor for generating temperature cracks, the thickness of the lining plate is small, the geometrical temperature gradient generated by the inside and outside temperature difference on the surface is particularly large, and the inside and outside temperature difference is also reduced when water is introduced for cooling. But do not have the allowable internal and external temperature difference control standards for lining concrete inside underground caverns.
Therefore, the research on the internal and external temperature difference of the arc-shaped section lining plate concrete of the underground cavern is urgently needed, and a simple, high-precision and quick method for calculating the allowable internal and external temperature difference and the allowable value thereof is provided for the heat preservation design of the closed cavern.
Disclosure of Invention
The invention aims to provide a method for controlling heat preservation by controlling the temperature difference between the inside and the outside of lining plate concrete with an arc-shaped section, which is beneficial to more optimally controlling the temperature cracks of the lining plate concrete and quickly applying to the control of the temperature difference between the inside and the outside and the heat preservation design of a closed opening.
In order to achieve the purpose, the invention adopts the following scheme:
as shown in figure 2, the invention provides a design method for controlling heat preservation by temperature difference between the inside and the outside of concrete of a lining plate with an arc section, which is characterized by comprising the following steps:
step 1, analyzing temperature control anti-cracking data of concrete of an arc section lining plate in a grotto to obtain calculation parameter information;
step 2, calculating the allowable internal and external temperature difference [ Delta T ] of the concrete of the arc section lining plate according to the obtained calculation parameter information nw 】(℃)：
【△T nw 】＝0.74α×C-20.25H/(2πR)+0.15H×C+0.04E-0.23C-0.81T a +27.57 (equation 1)
In the formula: alpha is the blending amount of the fly ash, for example, alpha =0.2 when the blending amount is 20%; r is the inner radius (m) of the arc-shaped section; c is the design age strength rating (MPa) of lining concrete 90d, e.g. C 90 If the lining concrete is the strength grade designed by the age of 28 days, the lining concrete needs to be converted into the strength grade designed by the age of 90 days according to the specification; h is the thickness (m) of the concrete plate; e is the deformation modulus (GPa) of the surrounding rock; t is a unit of a The temperature value (DEG C) of the air in the cavern in the concrete pouring period, and the T value when the temperature of the air in the underground cavern is increased by adopting the closed cavern for heat preservation in the construction period a The increased air temperature in the cavern should be adopted;
step 3, calculating the inside and outside temperature difference Delta T of the concrete of the arc section lining plate according to the obtained calculation parameter information nw (℃)；
Step 4. According to Delta T nw And [ Delta T ] nw Design heat preservation measures.
Preferably, the design method for controlling heat preservation by temperature difference between the inside and the outside of the concrete of the lining plate with the arc-shaped section, provided by the invention, can also have the following characteristics: in step 1, the analysis arc section liner plate concrete control by temperature change crack control data in the cavern includes: collecting and analyzing the structural engineering general of the arc section lining plate in the cavern, the hydrological weather and the concrete temperature control design technical requirements, wherein the acquired calculation parameter information comprises: the mixing amount of the fly ash, the inner radius of the arc-shaped section, the strength grade of the lining plate concrete at the design age of 90d, the thickness of the concrete plate, the deformation modulus of surrounding rock, the air temperature value in a cavern during the concrete pouring period, the water passing temperature effect value and the concrete surface convection coefficient.
Preferably, in the method for controlling and insulating the temperature difference between the inside and the outside of the concrete of the arc-shaped section lining plate, provided by the invention, in step 3, the temperature difference delta T between the inside and the outside of the concrete of the arc-shaped section lining plate is calculated by adopting the following formula nw (℃)：
△T nw ＝0.0883C+0.59T 0 +0.12T g -0.83T a -0.03S b +0.04H×C+0.132H×T 0 -0.10H×T g -0.01T 0 ×T g -0.00C×H×T 0 +21.06 (formula 2) wherein: t is a unit of 0 Casting temperature (deg.C); t is a unit of g The water temperature effect value (DEG C) and T g ＝35-T w ，T w Temperature of water passage (taking T when water passage cooling is not performed) w ＝35℃)；S b Is the concrete surface convection coefficient, unit: kJ/(m) 2 H. DEG C)); the rest are as defined above.
Preferably, the method for controlling and insulating the temperature difference between the inside and the outside of the concrete of the arc-shaped section lining plate, provided by the invention, can also have the following characteristics: convection coefficient S of concrete surface in different moisturizing and curing modes b Taking different values: for manually controlled watering maintenance, S b ＝100kJ/(m 2 H. Degree.C.); automatically and intelligently controlled 90% moisture preservation and maintenance, S b ＝150kJ/(m 2 H. DEG C)); automatic control, intelligent control 95% moisture maintenance, S b ＝200kJ/(m 2 ·h·℃)。
Preferably, the method for controlling heat preservation by temperature difference between the inside and the outside of the concrete of the lining plate with the arc-shaped section, provided by the invention, comprises the following substeps in step 4:
step 4.1 comparative analysis of internal and external temperature difference Delta T nw Whether or not the allowable value [ Delta T ] is exceeded nw 】；
Step 4.2 if Δ T nw ≤【△T nw A heat preservation measure for closing the hole is not needed; if Δ T nw ＞【△T nw Closing the hole and preserving heat.
Preferably, the arc section lining plate provided by the invention is concreteThe design method for controlling heat preservation by the temperature difference between the inside and the outside of the soil can also have the following characteristics: in step 4.2, if [ Delta T ] nw 】＜△T nw ≤【△T nw At +2.0 ℃, a simple curtain-hanging heat preservation measure for closing the opening is adopted, and ventilation holes or gaps are allowed to exist; if [ Delta T nw 】+2.0℃＜△T nw ≤【△T nw If +5.0 ℃, a strict hole opening sealing heat preservation measure is adopted; delta T nw ＞【△T nw And +5.0 ℃, a strict hole opening sealing heat preservation measure is adopted, and a ventilation gap is not allowed to exist.
Preferably, the design method for controlling heat preservation by temperature difference between the inside and the outside of the concrete of the lining plate with the arc-shaped section, provided by the invention, can also have the following characteristics: as shown in fig. 3, the simple curtain-type hole-closing thermal insulation measure is a hole-closing manner in which a hole is covered with thin geotextile, plastic film and the like with small thickness in a hanging manner, and the combination of the strips/blocks is not tight, so that a ventilation hole or a gap exists; as shown in fig. 4, the strict sealing of the hole heat preservation measure means that each hole is divided into an upper section and a lower section according to the structure of the inlet trash rack, and the heat preservation degree is between the simple and strict heat preservation measure; as shown in fig. 5, the strict sealing hole insulation measure means that a thick insulation quilt, a cotton felt and the like are adopted to strictly fix the whole sealing hole, and the sealing structure forms a whole without a ventilation gap.
In addition, the step 2 calculates the allowable internal and external temperature difference (Delta T) of the concrete of the arc section lining plate nw [ equation 1 ] the reliability is confirmed by: taking a circular section side crown arch of a domestic large hydraulic tunnel as an example, a three-dimensional finite element method is adopted to carry out temperature and temperature stress simulation calculation of 125 schemes of different thicknesses and inner radii of a lining plate, different strength grades and different tunnel indoor air temperature conditions for pouring lining concrete with different fly ash contents, and different temperature control measures, and the internal and external temperature differences of 86 schemes with the crack resistance safety factor of more than 1.0 are listed in a table 1, and then the data are obtained by statistical analysis. As the crack resistance safety coefficients K corresponding to the internal and external temperature difference conditions of the 86 schemes are all larger than 1.0, the concrete of the lining plate with the arc-shaped section only needs to be internally and externally mixed with the concreteIf the temperature difference does not exceed the calculated value (formula 1), surface temperature cracks are not generated. It is confirmed that the calculation result of (formula 1) can be regarded as the allowable internal and external temperature difference [ Delta T ] nw 】。
TABLE 1 simulation calculation result of concrete internal and external temperature difference of arc section lining plate (K > 1.0)
Step 3, calculating the inside and outside temperature difference Delta T of the concrete of the lining plate with the arc section nw The reliability of (equation 2) is confirmed by the following method: taking a circular section side crown arch of a domestic large hydraulic tunnel as an example, a three-dimensional finite element method is adopted to carry out temperature and temperature stress simulation calculation of 125 schemes of different thicknesses and inner radii of an arc section lining plate, different strength grades and different tunnel indoor air temperature conditions for pouring lining concrete with different fly ash mixing amounts under different temperature control measure conditions, the internal and external temperature differences of each scheme are collated and listed in a table 2, then statistical analysis is carried out on the data, and the calculation result is confirmed to be basically consistent with the actual measurement condition. In addition, the statistical analysis result shows that the temperature difference delta T between the inside and the outside of the concrete of the arc-shaped section lining plate nw Independent of the amount of the fly ash.
TABLE 2 simulation calculation result of internal and external temperature difference of arc section lining plate concrete
Action and effects of the invention
The invention relates to a design method for controlling heat preservation by controlling internal and external temperature differences of arc-shaped section lining plate concrete, and firstly provides an allowable internal and external temperature difference (delta T) suitable for arc-shaped section lining plate concrete nw Delta T difference between actual internal and external temperature nw The high-precision scientific calculation method obtains the allowable internal and external temperature difference [ Delta T ] by calculation according to the factors such as the inner radius of the arc-shaped section, the mixing amount of the fly ash, the thickness and the strength of the lining structure, the deformation modulus of the surrounding rock, the pouring parameters, the moisture-preserving maintenance mode and the humidity thereof nw Delta T difference between actual internal and external temperature nw Based on the numerical comparison result of the two, the closed hole heat-insulating measure needed to be taken in low-temperature seasons is designed rapidly so as to provide a targeted heat-insulating measure for the concrete of the arc-shaped section lining plate, effectively control the temperature difference between the inside and the outside and avoid the generation of surface cracks.
Drawings
FIG. 1 is a cross section (unit: m) of a circular arc lining plate of a hydraulic tunnel according to the present invention;
FIG. 2 is a flow chart of the concrete internal and external temperature difference control heat preservation design method for the arc-shaped section lining plate according to the invention;
FIG. 3 is a schematic view of the heat-insulating structure for simply sealing the opening to insulate heat and prevent cross-ventilation according to the present invention;
FIG. 4 is a construction drawing of a heat-insulating structure for strictly sealing the entrance of the diversion tunnel for power generation in the white beach and insulating the tunnel entrance and preventing cross-ventilation related to the invention;
FIG. 5 is a schematic view of a strictly closed hole insulation structure according to the present invention;
FIG. 6 is a cross-sectional view of a circular arc-shaped lining plate with the thickness of 0.8m on the upper flat section of the power generation diversion tunnel according to the invention;
FIG. 7 is a sectional view of a circular arc lining plate with the thickness of 1.0m on the upper flat section of the power generation diversion tunnel of the white beach.
Detailed Description
The concrete embodiment of the method for controlling and insulating the temperature difference between the inside and the outside of the arc-shaped section lining plate concrete is explained in detail below by taking the arc-shaped lining plate concrete at different parts of the power generation diversion tunnel project of the white crane beach hydropower station as an example in combination with the attached drawings.
< temperature control data of lining concrete for power generation diversion tunnel engineering of white crane beach hydropower station >
The white crane beach hydropower station has an installed capacity of 16000MW, and is the 2 nd hydropower station (second to the three gorges) all over the world. The installed capacity of the power station is 16000MW, and the average power generation amount for many years is 624.43 hundred million kW.h. The total storage capacity of the power station reservoir is 206.27 hundred million m < 3 >. The hub project consists of main buildings such as a barrage, a flood discharge and energy dissipation building, a water diversion and power generation system and the like. The underground plant system adopts a head development scheme, the head development scheme is respectively and symmetrically arranged on the left bank and the right bank, and 8 hydroelectric generating sets are respectively installed in the plant. The diversion tunnel adopts single-machine single-pipe water supply, and the tailwater system is the mode of a tailwater tunnel of 2 machines sharing, and left and right both banks respectively arrange 4 tailwater tunnels.
The diversion tunnel comprises a gradual change section, an upper flat section, a gradually reducing section, an upper bending section, a vertical shaft section, a lower bending section and a lower flat section, wherein the gradual change section, the upper flat section and the gradually reducing section are lined with reinforced concrete, and the type of the concrete is C 90 25; the upper bending section, the vertical shaft section, the lower bending section and the lower flat section are lined with steel plates. The gradual change section is arranged in a flat slope, the axis of the gradual change section is vertical to the water inlet tower, and the gradual change section is a circular section from a rectangular section; the upper flat section adopts a circular cross section and has two different lining thicknesses of 0.8m and 1.0m (figures 6 and 7).
The power generation diversion tunnel adopts low-heat cement concrete, and the maximum temperature allowed by design is shown in table 3. The casting temperature is controlled to be standard, 18 ℃ in 4-9 months and 15 ℃ in 10-3 months of the next year.
TABLE 3 highest temperature allowed for power generation diversion tunnel lining concrete design (Low Hot Cement)
The pouring temperature and the highest temperature of the concrete are controlled, and comprehensive measures are taken from the aspects of controlling the hydration heat of the concrete, the warehousing temperature, water cooling, surface protection, comprehensive management and the like.
(1) Controlling the heat of hydration, comprising: the mixing proportion of the concrete is optimized, and the using amount of the cement is reduced; selecting low-heat portland cement, and doping high-quality fly ash and a high-efficiency water reducing agent; pouring low-slump concrete, controlling the warehousing slump of the concrete of the bottom plate and the side wall to be 5-8 cm, and controlling the warehousing slump of the concrete pumped by the top arch to be 11-16 cm; commercial concrete is adopted, and the outlet temperature is controlled to be 14 ℃.
(2) And controlling the warehousing temperature and the pouring temperature of the concrete. The concrete mixture is transported, sun-shading and heat-insulating measures such as sun-shading cloth are adopted, long-time insolation or rain prevention is avoided, and when the outside temperature is higher than 23 ℃, necessary water spraying and temperature reduction are carried out on the outer side of the carriage discontinuously before loading, so that the temperature in the carriage is reduced. After the concrete is put into a bin, leveling and vibrating the bin in time, so that the covering speed is increased, and the exposure time is shortened; when the air temperature is higher, the surface of the bin is sprayed to reduce the environmental temperature in the concrete bin.
(3) And (5) introducing water for cooling. The cooling water pipe is embedded in the middle of the thickness in a direction parallel to the water flow direction, the lining thickness is not more than 1.5m, the time interval is 1.0m, the lining is arranged in a single row, a high-density polyethylene PVC pipe is adopted, the outer diameter phi is 32mm, and the wall thickness is 2mm. The flow rate of cooling water is controlled to be 1.5 to 2.0m 3 And/h, the water flow direction changes every 24 h. The water temperature of the water inlet is controlled to be 12-18 ℃ for making cold water, the temperature difference with the highest temperature inside the concrete is less than 25 ℃, and the daily temperature reduction range is less than 1.0 ℃. And (3) starting water cooling after the concrete is fed, wherein the water feeding time is 15-20 d, and the internal temperature of the concrete is not more than 25 ℃ when the water feeding is finished. And (5) protecting the concrete surface. And (4) covering a polyethylene heat preservation quilt with the thickness of 3cm for 30 days immediately after the mould is removed in the range of 50m of the tunnel entrance. Tunnel (including construction support) from 10 months to 3 months in the next yearHoles, ventilation holes, etc.) to reduce the air flow in the holes.
< embodiment I > design method for controlling heat preservation by pouring temperature difference between inside and outside of circular arc section lining plate concrete with thickness of 0.8m of power generation diversion tunnel in winter
The circular cross section of the power generation diversion tunnel is provided with a lining with the thickness of 0.8m, annular construction parting joints are arranged at intervals of 8-12 m (generally at intervals of 12 m) along the axis direction of the power generation tunnel, II-class surrounding rocks are formed, and lining plates are C 90 25% of low-heat concrete doped with 25% of fly ash, as shown in fig. 6. Pouring concrete by stages 2: the top arch is arranged at the first side and the back arch is arranged at the second side. The basic data of temperature control are the same as above. And intelligently controlling 95% humidity by adopting normal-temperature tap water, and maintaining for 90d.
According to the temperature control data, a construction unit plans a lining concrete pouring temperature control measure: winter T 0 Pouring at 18 ℃, not cooling by water, and removing the mould for time t m =3d. The temperature in the tunnel chamber, the length of the power generation tunnel and the ventilation condition are different from those of the diversion tunnel and the flood discharge tunnel, the annual average temperature is 16-26 ℃ under the condition of heat preservation without a closed tunnel opening by referring to the temperature monitoring data in the diversion tunnel chamber.
As shown in fig. 2, the method for controlling and insulating the temperature difference between the inside and the outside of the concrete of the arc-shaped cross-section lining plate provided by this embodiment includes the following steps:
step 1, analyzing concrete temperature control anti-cracking data of the lining plate with the arc-shaped section in the cavern. As the white crane beach hydropower station belongs to giant projects, and the power generation holes and the like are level 1 buildings, the temperature control and crack prevention of the lining concrete are very important. According to the design requirements, effective measures need to be taken for temperature control. Taking the casting in 1 month in winter as an example, the temperature in the cavern is calculated according to a cosine function to obtain a small value T a ＝16℃。
Step 2, calculating the allowable internal and external temperature difference (delta T) of the concrete of the lining plate with the arc section nw [ solution ] A: h =0.8m, R =7.0m, E =20GPa, C =25MPa, T a Substituting =16 deg.C,. Alpha =0.25 into (equation 1) to calculate [. DELTA.T [ ] nw 】＝16.92℃。
Step 3, calculating the inside and outside temperature difference Delta T of the concrete of the lining plate with the arc section nw : lining plate concrete with arc-shaped cross section has H =0.8m, C =25MPa and T a ＝16℃、α＝0.25、T 0 =18 ℃ and intelligently controlled 95% moisture-keeping maintenance S b =200 kJ/(m 2. H. DEG C.), cooling T without water g Substituting =0 into (formula 2) to calculate Δ T nw ＝17.3℃。
And 4, designing a heat preservation measure for the closed hole. The method comprises the following steps:
step 4.1 comparative analysis of internal and external temperature difference Delta T nw Whether or not the allowable value [ Delta T ] is exceeded nw 】：△T nw ＝17.3℃＞【△T nw 】＝16.92℃。
Step 4.2 because of Δ T nw ＝17.3℃＞【△T nw =16.92 ℃, only above 0.38 ℃, [ Δ T ℃ nw 】＜△T nw ＜【△T nw 2.0 ℃, so the simple curtain shown in figure 3 is adopted to seal the opening of the hole for heat preservation.
< example two > design method for controlling heat preservation by pouring concrete internal and external temperature difference of circular cross section lining plate with thickness of 1.0m of power generation diversion tunnel in summer
The circular cross section of the power generation diversion tunnel is provided with a lining with the thickness of 1.0m, annular construction parting joints are arranged at intervals of 8-12 m (generally at intervals of 12 m) along the axis direction of the power generation tunnel, class III surrounding rocks are arranged, and lining plates are C 90 25% low heat concrete, blended with 25% fly ash, as shown in fig. 7. Pouring concrete by stages 2: the top arch is arranged at the first side and the back arch is arranged at the second side. The basic data of temperature control are the same as above. And (5) moisturizing and maintaining for 90 days by adopting normal-temperature tap water.
According to the temperature control data, a construction unit plans a lining concrete pouring temperature control measure: summer T 0 Pouring at 20 ℃, not cooling by water, and removing the mould for time t m =3d. The temperature in the tunnel chamber, the length of the power generation tunnel and the ventilation condition are different from those of the diversion tunnel and the flood discharge tunnel, the annual average temperature is 16-26 ℃ under the condition of heat preservation without a closed tunnel opening by referring to the temperature monitoring data in the diversion tunnel chamber.
As shown in fig. 2, the method for controlling and insulating the temperature difference between the inside and the outside of the concrete of the arc-shaped cross-section lining plate provided by this embodiment includes the following steps:
step 1, analyzing concrete temperature control anti-cracking data of the lining plate with the arc-shaped section in the cavern. As the white crane beach hydropower station belongs to giant projects, and the power generation holes and the like are level 1 buildings, the temperature control and crack prevention of the lining concrete are very important. According to the design requirements, effective measures need to be taken for temperature control. Taking pouring in summer of 7 months as an example, calculating the temperature in the cavity in summer according to a cosine function, and taking a large value Ta =26 ℃.
Step 2, calculating the allowable internal and external temperature difference (delta T) of the concrete of the lining plate with the arc section nw [ solution ] A: substituting H =1.0m, R =7.0m, E =15GPa, C =25MPa, ta =26 ℃, α =0.25 into equation (1) to calculate [ Δ T ] nw 】＝8.02℃。
Step 3, calculating the inside and outside temperature difference Delta T of the concrete of the lining plate with the arc section nw : lining plate concrete with arc-shaped cross section has H =1.0m, C =25MPa and T a ＝26℃、α＝0.25、T 0 Intelligent controlled 95% moisture-keeping curing S at 20 deg.C b =200 kJ/(m 2. H. DEG C.), cooling T without water g Substituting =0 into (formula 2) to calculate Δ T nw ＝11.13℃。
And 4, designing a heat preservation measure for the closed hole. The method comprises the following steps:
step 4.1 comparative analysis of internal and external temperature difference Delta T nw Whether or not the allowable value [ Delta T ] is exceeded nw 】：△T nw ＝11.13℃＞【△T nw 】＝8.02℃。
Step 4.2 due to DeltaT nw ＝11.13℃＞【△T nw 】＝8.02℃，△T nw -【△T nw =3.11 ℃, so a stricter heat preservation measure for the closed hole as shown in fig. 4 is preferably adopted.
By integrating the above calculation and analysis, concrete is poured in winter, and the delta T nw ＞【△T nw 0.38 ℃, simple curtain-hanging hole-closing heat-preserving measures need to be adopted; pouring concrete in summer, delta T nw -【△T nw =3.11 ℃, although it exceeds 2.0 ℃, it does not exceed 5.0 ℃, so it is advisable to adopt the stricter heat preservation of the closed hole in fig. 4. The strict heat preservation measures of the closed hole in the figure 4 are adopted all the year round according to the requirements of pouring lining concrete in winter and summer.
In the actual engineering, the power generation diversion tunnel (i.e. entrance opening, circular section) of the white crane beach is lined with concrete, poured at 20 ℃ in summer and 16 ℃ in winter, and the tunnel opening is strictly closed in the figure 4 for heat preservation (the upper and lower sections of each tunnel opening are strictly closed according to the structure of the entrance trash rack). Some holes in construction have holes because personnel and equipment access guarantee are not enough. But the closed hole is stricter and has better effect, so the lining concrete has no temperature crack effect (temperature and temperature crack control effect, see the section brightness, fan auspicious and the like in the theory and application of the temperature crack control of the lining concrete of hydraulic tunnels, the Chinese water conservancy and hydropower publishing company, 2021, 11 months). The results of the above computational analysis are shown to be consistent with the practical situation of engineering.
The above embodiments are merely illustrative of the technical solutions of the present invention. The method for controlling the heat preservation by the temperature difference between the inside and the outside of the concrete of the lining plate with the arc-shaped section is not limited to the contents described in the above embodiments, but is subject to the scope defined by the claims. Any modification, supplement or equivalent replacement by a person skilled in the art on the basis of this embodiment is within the scope of the invention as claimed in the claims.
Claims (7)
1. The design method for controlling heat preservation by the temperature difference between the inside and the outside of the concrete of the arc-shaped section lining plate is characterized by comprising the following steps of:
step 1, analyzing temperature control and crack prevention data of concrete of the arc-shaped section lining plate in the cavern to obtain calculation parameter information;
step 2, calculating the allowable internal and external temperature difference (delta T) of the concrete of the lining plate of the arc section according to the obtained calculation parameter information nw 】：
【△T nw 】＝0.74α×C-20.25H/(2πR)+0.15H×C+0.04E-0.23C-0.81T a +27.57 (formula 1) wherein: alpha is the blending amount of the fly ash; r is the inner radius of the arc-shaped section; c, designing age strength grade for lining plate concrete 90 d; h is the thickness of the concrete plate; e is the deformation modulus of the surrounding rock; t is a unit of a The value is the air temperature value in the cavern in the concrete pouring period;
step 3, calculating the temperature difference delta T between the interior and the exterior of the concrete of the arc-shaped section lining plate according to the obtained calculation parameter information nw ；
Step 4. According to Delta T nw And [ Delta T ] nw Design heat preservation measures.
2. The design method for controlling heat preservation by temperature difference between the inside and the outside of the concrete of the arc-shaped section lining plate according to claim 1, characterized by comprising the following steps:
wherein, the calculation parameter information obtained in step 1 includes: the mixing amount of the fly ash, the inner radius of the arc-shaped section, the strength grade of the lining plate concrete at the design age of 90d, the thickness of the concrete plate, the deformation modulus of surrounding rock, the air temperature value in a cavern during the concrete pouring period, the water passing temperature effect value and the concrete surface convection coefficient.
3. The design method for controlling heat preservation by temperature difference between the inside and the outside of the concrete of the arc-shaped section lining plate according to claim 1, characterized by comprising the following steps:
in step 3, calculating the temperature difference delta T between the inside and the outside of the concrete of the arc-shaped section lining plate by adopting the following formula nw ：
△T nw ＝0.0883C+0.59T 0 +0.12T g -0.83T a -0.03S b +0.04H×C+0.132H×T 0 -0.10H×T g -0.01T 0 ×T g -0.00C×H×T 0 +21.06 (equation 2)
In the formula: t is a unit of 0 The casting temperature is set; t is g The water temperature effect value is obtained; s b Is the concrete surface convection coefficient.
4. The method for controlling and insulating the concrete internal and external temperature difference of the arc-shaped section lining plate according to claim 3, characterized by comprising the following steps:
wherein, the convection coefficient S of the concrete surface is adopted in different moisture-preserving curing modes b Taking different values: for manually controlled watering maintenance, S b ＝100kJ/(m 2 H. Degree.C.); automatically and intelligently controlled 90% moisture preservation and maintenance, S b ＝150kJ/(m 2 H. Degree.C.); automatic control, intelligent control 95% moisture maintenance, S b ＝200kJ/(m 2 ·h·℃)。
5. The method for controlling and insulating the concrete internal and external temperature difference of the arc-shaped section lining plate according to claim 1, which is characterized in that:
wherein, step 4 comprises the following substeps:
step 4.1 comparison of internal and external temperature difference DeltaT nw Whether or not the allowable value [ Delta T ] is exceeded nw 】；
Step 4.2 if Δ T nw ≤【△T nw The heat preservation measure for closing the hole opening is not needed; if Δ T nw ＞【△T nw And C, sealing the hole and preserving heat.
6. The method for controlling and insulating the concrete internal and external temperature difference of the arc-shaped section lining plate according to claim 5, characterized by comprising the following steps:
wherein, in step 4.2, if [ Delta T ] nw 】＜△T nw ≤【△T nw At +2.0 ℃, a simple curtain-hanging heat preservation measure for closing the opening is adopted, and ventilation holes or gaps are allowed to exist; if [ Delta T nw 】+2.0℃＜△T nw ≤【△T nw If +5.0 ℃, a strict hole opening sealing heat preservation measure is adopted; delta T nw ＞【△T nw And +5.0 ℃, a strict hole opening sealing heat preservation measure is adopted, and a ventilation gap is not allowed to exist.
7. The design method for controlling heat preservation by temperature difference between the inside and the outside of the concrete of the arc-shaped section lining plate according to claim 6, characterized by comprising the following steps:
the simple curtain-hanging hole-closing heat-insulating measure is characterized in that geotechnical cloth and plastic films with small thicknesses are adopted to cover the hole in a hanging mode, and the combination of all the strips/blocks is not tight, so that ventilation holes or gaps exist;
the strict sealing of the hole heat preservation measures means that each hole is divided into an upper section and a lower section according to the structure of an inlet trash rack and is strictly sealed, and the heat preservation degree is between simple and strict heat preservation measures;
the strict hole sealing heat preservation measure is that a thick heat preservation quilt and a cotton felt are adopted to strictly fix a sealing hole mode of the integral sealing hole, a sealing structure forms an integral body, and no ventilation gap exists.
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