CN104110008B - A kind of method quickly regulated and controled for concrete dam middle and late stage water flowing - Google Patents

Abstract

A kind of method quickly regulated and controled for concrete dam middle and late stage water flowing, it comprises the steps, initially set up concrete dam middle and late stage water flowing fast prediction model, it is then based on concrete pouring bin observed temperature, dynamically update the significant terms of concrete dam middle and late stage water flowing fast prediction model, with the error that the factor of removing uncertainty causes, then dynamic prediction treats the temperature-responsive of following some days under preferred water flowing measure, object function is set up with dynamic prediction temperature-responsive and design temperature monitor control index, introduce optimized algorithm, from water flowing measure feasible zone space, preferably obtain currently most water flowing measure, the real-time monitoring water flowing of following some days cooling, behind some skies, again obtain and build the current observed temperature in storehouse, dynamically renewal-prediction-Optimum Regulation again. the present invention establishes a kind of quick, accurate and that amount of calculation is little temperature dynamic forecast model, and quickly preferred realization theing be established as temperature control measures of temperature dynamic forecast model provides feasibility.

Description

Method for quickly regulating and controlling water supply in middle and later periods of concrete dam

Technical Field

The invention relates to a method for quickly regulating and controlling water passing in the middle and later periods of a concrete dam, and belongs to the field related to dams.

Background

The problem of late cooling in the water pipes of concrete dams is an important and complex problem. Because the water pipe cooling is a double-edged sword, although the water cooling can effectively reduce the maximum temperature of concrete construction and reduce the temperature of the dam body to the target temperature in a short time, a large tensile stress is caused near the water pipe when water starts to flow, and cracks can be caused if the temperature reduction rate is too fast. The problem is not taken into consideration in the past, and the difference T between the initial temperature and the water temperature of the concrete is allowed in the actual construction₀-T_w20-25 ℃. Research indicates that in the second stage cooling, if 1-grade water temperature is adopted, the initial temperature of the concrete is 30 ℃, the cooling water temperature is 9 ℃, namely the difference between the initial temperature of the concrete and the water temperature is 21 ℃, the cooling is started in the concrete age of 90d, the maximum tensile stress at the hole edge is about 5MPa, and the tensile stress depth is 0.33m (the distance between water pipes is 1).5m × 1.5.5 m) to 0.70m (the distance between water pipes is 3.0m × 3.0.0 m), the tensile stress is enough to cause cracks, in addition, the arrangement of the prior concrete water pipe cooling is simple, the control means is single, in order to avoid the overhigh temperature of the concrete dam, a strategy of increasing the water flow is adopted, so that the waste of water resources is inevitable, and in addition, the existing concrete water pipe cooling arrangement is simple, the control means is single, so that the difference between the actual concrete dam temperature control and the design temperature control is large, and the generation of the cracks of the concrete dam is still difficult to avoid.

In order to effectively control the concrete dam cracks, it is necessary to plan later-stage water pipe cooling, that is, considering the height of a cooling area, the distance between water pipes, the cooling stage and water temperature control, performing careful analysis and multi-scheme comparison, and selecting an optimal scheme from the cooling. Strictly speaking, for the water cooling planning problem in the middle and later stages, thermal parameter inversion is carried out by combining with the measured temperature, and then simulation analysis and comparison are carried out on the concrete dam temperature field containing the cooling water pipe problem and the creep stress field of multiple schemes, and the optimal scheme is selected.

The concrete dam temperature control crack prevention is a complex multi-factor problem related to temperature control measures and concrete thermodynamic parameters, and an optimal scheme is determined by adopting an optimization theory. When the optimization theory is adopted to carry out the optimization design of the temperature control measures of the concrete dam engineering with large scale, if the simulation analysis of a more accurate temperature field and creep stress field is carried out, the calculation workload is extremely large due to the optimization of a plurality of factors such as different temperature control measures, concrete thermodynamic parameters and the like. Even when water cooling is carried out in the middle and later periods of the concrete dam, the distance between water pipes, the material of the water pipes (metal water pipes or plastic water pipes), the thermodynamic performance of concrete and the like are completely determined, and for the concrete dam engineering with large scale, if the simulation analysis is still based on a relatively accurate temperature field and creep stress field, the optimization theory is adopted to optimize water measures, and the calculation workload is still large. Obviously, if the timely guidance for water supply regulation and control in the middle and later periods of the concrete dam cannot be conveniently provided, great blindness exists when temperature control personnel on the site of dam construction specifically implement water supply measures.

Although there have been some reports on the automatic control system for water cooling of concrete, for example, pachychia, Taka Caesalpinia, etc., based on the temperature, flow rate signal and opening degree information collected by the measurement and control device, the opening degree control of the electric control valve is performed to adjust the water flow rate and water temperature. Forest and peng, li qing and the like, digital temperature sensors are buried in a new pouring bin, a flow temperature control device is installed on a water inlet pipe and a water outlet pipe, real-time water flow is determined according to the principles of energy conservation and heat transfer, and an intelligent temperature control method and system for cooling mass concrete by water are established by adopting the temperature control principles of highest temperature, temperature change rate and abnormal temperature. In the Shandong nations, Guo in the morning and the like, a set of instrument and equipment for collecting information such as internal temperature, cooling water temperature and cooling water flow of dam concrete in real time and automatically controlling the cooling water flow is researched and developed, and practical research is carried out in Ludi water power stations. However, an optimization algorithm is not introduced into the automatic concrete water cooling control systems, and waste of water resources is still difficult to avoid.

Disclosure of Invention

In order to overcome the defects of the prior art, the method for quickly regulating and controlling the water passing in the middle and later periods of the concrete dam is provided, an optimization algorithm is introduced, the current optimal water passing measure is preferably obtained from the feasible domain space of the water passing measure, and the field water passing cooling is guided in real time.

The technical scheme adopted by the invention is as follows:

a method for rapidly regulating and controlling water supply in the middle and later periods of a concrete dam is characterized by comprising the following steps: firstly, establishing a rapid water-passing prediction model in the middle and later stages of a concrete dam, dynamically updating important items of the rapid water-passing prediction model in the middle and later stages of the concrete dam based on the actual measured temperature of a concrete pouring bin to eliminate errors caused by uncertainty factors, then dynamically predicting the temperature response of a plurality of days in the future under the water-passing measure to be optimized, establishing a target function by using the dynamically predicted temperature response and a designed temperature monitoring index, introducing an optimization algorithm, preferably obtaining the current optimal water-passing measure from the feasible domain space of the water-passing measure, regulating and controlling the water-passing cooling of 7-10 days in real time, obtaining the current actual measured temperature of the pouring bin again after 7-10 days, and dynamically updating, predicting, optimizing and regulating and controlling again;

the method specifically comprises the following steps: 1) model for rapidly predicting concrete dam temperature during middle and later period water cooling

In order to quickly and accurately predict the temperature of the concrete block in the middle and later period of water cooling, a priori model with small calculation workload must be adopted, most of the hydration heat of the cement is released and heat preservation benzene plates are generally stuck on the upstream and downstream surfaces when the middle and later period of water cooling of the concrete block is carried out, at the moment, the horizontal distance and the vertical distance of water pipes, the material of the water pipes and the thermodynamic property of the concrete are also known, namely, the middle and later period cooling of the dam concrete is considered to be only a complicated multi-factor problem related to the water temperature, the water flow and the water time;

embedding a cooling water pipe in the concrete pouring bin for water cooling, setting the equivalent cooling diameter as D, the length as L, no heat source and the initial temperature of concrete as T₀Inlet water temperature of T_wThe average temperature of the concrete can be expressed as

T＝T_w+(T₀-T_w)φ(1)

Function phi has the following two calculation formulas

(1) Function phi calculation formula 1

φ＝exp(-p₁τ^s)(2)

Wherein p is₁＝k₁(a/D²)^s，k₁＝2.08-1.174ξ+0.256ξ²，s＝0.971+0.1485ξ-0.0445ξ²，ξ＝λL/(c_wρ_wq_w) In the formula: a is concrete temperature conductivity coefficient, D is equivalent cooling diameter of water pipe of pouring bin, lambda is concrete heat conductivity coefficient, L is cooling water pipe length, c_wSpecific heat of cooling water, p_wFor cooling waterDegree, q_wThe flow rate is the water flow rate;

(2) function phi calculation formula 2

φ＝exp(-p₂τ)(3)

Wherein p is₂＝k₂a/D²，k₂＝2.09-1.35ξ+0.320ξ²Wherein a, D and ξ have the same meanings as above,

when b/c is not equal to 100, the temperature coefficient a in the calculation formula of the function phi is an equivalent temperature coefficient a', for the metal water pipe, the

a′＝1.947(α₁b)²a(4)

Wherein, ${\mathrm{\α}}_{1}b=0.926\exp [-0.0314{(\frac{b}{c}-20)}^{0.48}],20\≤\frac{b}{c}\≤130,$ in the formula: b is the equivalent cooling radius, c is the outer radius of the metal water pipe,

for plastic water pipes, there are

$a^{\′}=\frac{\ln 100}{\ln (b/c)+(\mathrm{\λ}/{\mathrm{\λ}}_1)\ln (c/r_0)}a---\left(5\right)$

In the formula: lambda [ alpha ]₁Is the heat conductivity coefficient of the plastic water pipe, c is the outer radius of the plastic water pipe, r₀Is the inner radius of the plastic water pipe, the other symbols have the same meanings as the former symbols,

when the cooling time is longer, the calculation formula 1 of the function phi is adopted, when the cooling time is not more than 15 days, the calculation formula 2 of the function phi is adopted,

when the water flow is not changed and the cooling is carried out by adopting multi-gear water temperature, the average temperature of the concrete is calculated by adopting the following formula

T＝T_wi+(T_i-T_wi)φ_i(6)

In the formula: t is_wiFor the ith water-blocking temperature, T_iThe concrete temperature phi when the water temperature of the i-1 st water retaining pipe is finished and the water temperature of the i-1 st water retaining pipe is started_iFor the water cooling function when the water temperature of the ith baffle is filled with water, the time tau in the function needs to start from 0,

when the water temperature is constant and the cooling is performed by adopting multi-step flow, the calculation formula of the average temperature of the concrete is similar to the formula (6), and similarly, the time tau in the water cooling function needs to be started from 0;

2) dynamic prediction model for casting bin temperature during middle and later period cooling of concrete dam

The heat source-free water pipe cooling calculation formula implies the appearance of a concrete prism with the equivalent cooling diameter DThe faces are adiabatic boundaries and the hydration heat of the concrete prism is assumed to be fully completed, in a pyrogen-free state. The concrete pouring blocks in the middle and later cooling stages are not in a heat source-free state; in addition, the concrete pouring blocks in the middle and later cooling stages are not in an adiabatic state, and the external environment temperature still has certain influence on the temperature inside the concrete blocks, namely the concrete pouring bin temperature prediction in the middle and later cooling stages is carried out by directly adopting the heat-source-free water pipe cooling calculation formula (6), the effect is not ideal, and the T in the heat-source-free water pipe cooling calculation formula is dynamically updated_iTherefore, the problem that the temperature prediction effect of the non-heat source water pipe cooling calculation formula is not ideal is solved, and the temperature information of the concrete pouring bin in the future 7-10 days can be accurately predicted;

3) concrete analysis step of concrete dam middle and later stage water cooling rapid regulation and control method

(1) Obtaining a current temperature state and a current water-passing feasible region, and firstly obtaining the temperature Ti of each concrete pouring bin of a typical dam section at the beginning of medium-stage cooling or the beginning of secondary cooling; then determining the water passing temperature T according to engineering experience_wFlow rate of water T_QAnd water passing time T_tWaiting for the initial value of the water-passing measure;

(2) dynamically predicting the temperature response of a plurality of days in the future, adopting a heat source-free water pipe cooling calculation formula to calculate the concrete cooling curve and obtaining the final cooling temperature T of each concrete pouring bin under the value combination of water-passing measures_iendAnd maximum daily cooling rate

(3) The calculated final temperature and the maximum daily cooling rate under the intercooling or the secondary cooling are compared with the design target temperature T of the intercooling or the secondary cooling_i ^objAnd a suitable cooling rateThe sum of squares of the residuals is used as an objective function, and the water passing measure optimization model is established by

$\min f(T_i,T_w,T_Q,T_t)={({T_i}^{\mathrm{obj}}-T_{\mathrm{iend}})}^2+{({{\stackrel{\·}{T}}_i}^{\mathrm{opt}}-{\stackrel{\·}{T}}_{i\max })}^2---\left(7\right)$

$s.t.\left\{\begin{array}{c}\underset{\‾}{T_w}\≤T_w\≤\stackrel{\‾}{T_w}\\ \underset{\‾}{T_Q}\≤T_Q\≤\stackrel{\‾}{T_Q}\\ \underset{\‾}{T_t}\≤T_t\≤\stackrel{\‾}{T_t}\end{array}\right.$

In the formula:T _w 、respectively is the water temperature T_wThe upper and lower limit values of (c),T _Q 、respectively the flow rate of water_QThe upper and lower limit values of (c),T _t 、respectively the water passage time T_tUpper and lower limit values of (d);

(4) optimally obtaining a water passing scheme for optimizing the concrete of each bin by adopting an optimization algorithm with constraints;

(5) and analyzing each pouring bin of the typical dam section in the middle and later stages through water cooling one by one, slightly adjusting the optimized water-through measures according to the actual conditions and the experience of the engineering, and guiding the middle and later stages through water cooling.

When the concrete cooling curve is calculated by adopting the heat source-free water pipe cooling calculation formula, the temperature T of the concrete pouring bin at the beginning of the middle-stage cooling or the beginning of the second-stage cooling needs to be known_iThe temperature can be obtained as follows: the method comprises the following steps that firstly, a thermometer is buried in a concrete pouring bin, and the measured temperature is used as the temperature of the concrete pouring bin at the beginning of middle-stage cooling or the beginning of secondary cooling; in the second mode, before the middle-stage cooling or the second-stage cooling, the temperature is measured through water-tight temperature, and the temperature is used as the temperature of the concrete pouring bin at the beginning of the middle-stage cooling or the beginning of the second-stage cooling; in order to ensure the accuracy of obtaining the temperature of the concrete pouring bin, the weighted average calculation can be carried out on the temperature obtained in the first mode and the temperature obtained in the second mode.

At the moment, the main step of water cooling fast regulation and control in the middle and later stages based on the optimization algorithm is similar to the step of cooling by adopting one water temperature and flow rate in the middle and second-stage cooling periods, but the optimization of the water flowing scheme of the concrete pouring bin temperature when the water temperature or the flow rate is regulated each time is needed, and the calculation workload of the pouring bin temperature dynamic prediction model based on the heat-source-free water pipe cooling calculation formula is small, so that the feasibility of optimizing the water flowing scheme when the water temperature or the flow rate is regulated each time can be ensured.

When the water cooling function phi is calculated, the concrete thermal conductivity coefficient, the thermal conductivity coefficient and the plastic water pipe thermal conductivity coefficient are involved, and the parameters are obtained by adopting design values and factory quality inspection values or performing parameter inversion based on actual temperature.

The invention has the following technical effects:

(1) aiming at the problem that water flowing in the middle and later periods of a concrete dam is a complex multi-factor problem related to water flowing temperature, water flowing quantity, water flowing time and the like, the actually measured temperature is organically fused into a non-heat-source water pipe cooling calculation formula, important items in the non-heat-source water pipe cooling calculation formula are dynamically updated based on the actually measured temperature, temperature prediction errors caused by uncertainty of boundary conditions, material parameters, a calculation model and the like are eliminated, and therefore the rapid and accurate temperature dynamic prediction model with small calculation workload is established. The establishment of the temperature dynamic prediction model provides feasibility for the quick and optimal realization of the temperature control measures.

(2) Aiming at the problems that the existing concrete water pipe cooling arrangement is simple, the control means is single, the difference between the actual concrete dam temperature control and the designed temperature control is large, an optimization algorithm is not introduced into the existing concrete water cooling automatic control system, and the waste of water resources is still difficult to avoid. Therefore, waste of water resources is avoided, and water cooling in the middle and later periods of the concrete dam is effectively guided in real time.

Drawings

FIG. 1 is a block diagram of dynamic prediction of single-point temperature of a concrete pouring bin during middle and later cooling periods;

FIG. 2 is a block diagram of optimal regulation and control of water cooling in the middle and later stages of a typical dam section, wherein NI is the number of pouring bins in the middle and later stages of water supply;

FIG. 3 is a graph of typical dam section vertical temperatures during mid-late cooling.

Detailed Description

Embodiments of the present invention will be further described with reference to the accompanying drawings.

The invention is mainly suitable for the rapid regulation and control of water supply measures in the middle and later periods of the concrete dam. Firstly, establishing a rapid water passing prediction model in the middle and later periods of the concrete dam, dynamically updating important items of the rapid water passing prediction model in the middle and later periods of the concrete dam based on the measured temperature of the concrete pouring bin to eliminate errors caused by uncertain factors, then dynamically predicting the temperature response of a plurality of days in the future under the water passing measures to be optimized, establishing a target function by dynamically predicting the temperature response and designing temperature monitoring indexes, introducing an optimization algorithm, optimally obtaining the current optimal water passing measures from the feasible region space of the water passing measures, and regulating and controlling the water passing cooling of the plurality of days in the future in real time. And after a plurality of days, obtaining the current measured temperature of the pouring bin again, and dynamically updating, predicting, optimally regulating and controlling again.

The detailed technical scheme of the invention is as follows:

1) model for rapidly predicting concrete dam temperature during middle and later period water cooling

In order to quickly and accurately predict the temperature of the concrete block in the middle and later period of water cooling, a priori model with small calculation workload must be adopted. Because most of cement hydration heat is released when water cooling is carried out in the middle and later periods of the concrete block, and the heat preservation benzene plates are generally stuck on the upstream and downstream surfaces, at the moment, the horizontal spacing and the vertical spacing of the water pipes, the material of the water pipes (metal water pipes or plastic water pipes), the thermodynamic property of the concrete and the like are also known, namely, the middle and later period cooling of the dam concrete is only a complicated multi-factor problem related to the water temperature, the water flow, the water time and the like. Therefore, the invention adopts a heat source-free water pipe cooling calculation formula to quickly predict the temperature of the concrete dam during the middle and later period of water cooling.

The calculation formula of the heat source-free water pipe cooling calculation formula is given in detail below. Embedding a cooling water pipe in the concrete pouring bin for water cooling, setting the equivalent cooling diameter as D, the length as L, no heat source and the initial temperature of concrete as T₀Inlet water temperature of T_wThe average temperature of the concrete can be expressed as

T＝T_w+(T₀-T_w)φ(1)

Function phi has the following two calculation formulas

(1) Function phi calculation formula 1

φ＝exp(-p₁τ^s)(2)

Wherein p is₁＝k₁(a/D²)^s，k₁＝2.08-1.174ξ+0.256ξ²，s＝0.971+0.1485ξ-0.0445ξ²，ξ＝λL/(c_wρ_wq_w)。

In the formula: a is concrete temperature conductivity coefficient, D is equivalent cooling diameter of water pipe of pouring bin, lambda is concrete heat conductivity coefficient, L is cooling water pipe length, c_wSpecific heat of cooling water, p_wFor the density of the cooling water, q_wThe flow rate is water flow.

(2) Function phi calculation formula 2

φ＝exp(-p₂τ)(3)

Wherein p is₂＝k₂a/D²，k₂＝2.09-1.35ξ+0.320ξ²

In the formula: a. d and xi have the same meanings as before.

When b/c is not equal to 100, the temperature coefficient a in the calculation formula of the function phi is an equivalent temperature coefficient a', for the metal water pipe, the

a′＝1.947(α₁b)²a(4)

Wherein, ${\mathrm{\α}}_{1}b=0.926\exp [-0.0314{(\frac{b}{c}-20)}^{0.48}],20\≤\frac{b}{c}\≤130$

in the formula: b is the equivalent cooling radius, c is the outer radius of the metal water pipe,

for plastic water pipes, there are

$a^{\′}=\frac{\ln 100}{\ln (b/c)+(\mathrm{\λ}/{\mathrm{\λ}}_1)\ln (c/r_0)}a---\left(5\right)$

In the formula: lambda [ alpha ]₁Is the heat conductivity coefficient of the plastic water pipe, c is the outer radius of the plastic water pipe, r₀Is a plastic water pipeThe remaining symbols have the same meanings as above.

When the cooling time is longer than 15 days, the calculation formula 1 of the function phi is preferably adopted, but in the actual concrete engineering, the calculation formula 2 of the function phi is more used.

When the water flow is not changed and the cooling is carried out by adopting multi-gear water temperature, the average temperature of the concrete is calculated by adopting the following formula

T＝T_wi+(T_i-T_wi)φ_i(6)

In the formula: t is_wiFor the ith water-blocking temperature, T_iThe concrete temperature phi when the water temperature of the i-1 st water retaining pipe is finished and the water temperature of the i-1 st water retaining pipe is started_iFor the water cooling function when the ith water stop temperature is filled with water, the time tau in the function needs to start from 0.

When cooling is performed at a plurality of flow rates with the water temperature of the feed water constant, the concrete average temperature calculation formula is similar to the formula (6), and similarly, the time τ in the water cooling function needs to be from 0.

2) Dynamic prediction model for casting bin temperature during middle and later period cooling of concrete dam

As shown in fig. 1, the calculation formula of the non-heat source water pipe cooling implies that the outer surface of the concrete prism with the equivalent cooling diameter D is an adiabatic boundary, and the hydration heat of the concrete prism is completely finished and is in a non-heat source state. Because the concrete pouring blocks in the middle and later cooling stages are not in a heat source-free state, for example, the concrete dam is doped with fly ash at a high level, slow heat release in the later stage exists, and the like; in addition, the concrete pouring blocks in the middle and later cooling stages are not in a heat insulation state, for example, heat insulation polystyrene boards are adhered to the outer surfaces of the concrete pouring blocks, and the temperature of the external environment still has certain influence on the temperature inside the concrete pouring blocks. Namely, the concrete pouring bin temperature prediction during the middle and later period cooling is carried out by directly adopting a heat source-free water pipe cooling calculation formula (6), and the effect is not ideal.

The invention is based on the current measured temperature of the concrete pouring bin, and the heat is not generated in the dynamic updatingT in source water pipe cooling calculation formula_iThe dynamic updating of T can be realized by the slow heat release of the highly doped fly ash and the errors caused by the fact that the upstream and downstream surfaces are not adiabatic boundaries_iThe dynamic real-time correction is carried out, so that the problem that the prediction effect of the heat source-free water pipe cooling calculation formula temperature is not ideal is solved, and the prediction of the concrete pouring bin temperature information in 7-10 days in the future can be accurately carried out.

3) Method for quickly regulating and controlling water cooling in middle and later periods of concrete dam

The invention adopts the established dynamic prediction model of the concrete pouring bin with small calculation workload, is rapid and accurate, dynamically predicts the temperature response of a plurality of days in the future under the water passing measure to be optimized, establishes an objective function by dynamically predicting the temperature response and designing a temperature monitoring index, introduces an optimization algorithm (such as a composite algorithm) with constraint, optimally obtains the current optimal water passing measure from the feasible domain space of the water passing measure, and regulates and controls the water passing cooling of the plurality of days in the future in real time. And after a plurality of days, obtaining the current measured temperature of the pouring bin again, and dynamically updating, predicting, optimally regulating and controlling again. Therefore, a rapid water cooling regulation and control model for the middle and later periods of the concrete dam is established.

Referring to fig. 2, the analysis steps of the method for rapidly regulating and controlling the water cooling in the middle and later stages of the concrete dam are detailed below.

(1) And obtaining the current temperature state and the current water passing feasible region. Firstly, obtaining the temperature Ti of each concrete pouring bin of a typical dam section at the beginning of medium-stage cooling or the beginning of secondary cooling; then determining the water passing temperature T according to engineering experience_wFlow rate of water T_QAnd water passing time T_tAnd waiting for the initial value of the water passing measure.

(2) The temperature response for several days in the future is dynamically predicted. Adopting a heat source-free water pipe cooling calculation formula to calculate the concrete cooling curve to obtain the final cooling temperature T of each concrete pouring bin under the value combination of water-passing measures_iendAnd maximum daily cooling rate

(3) The calculated final temperature and the maximum daily cooling rate under the intercooling or the secondary cooling are compared with the design target temperature T of the intercooling or the secondary cooling_i ^objAnd a suitable cooling rateThe sum of squares of the residuals is used as an objective function, and the water passing measure optimization model is established by

$\min f(T_i,T_w,T_Q,T_t)={({T_i}^{\mathrm{obj}}-T_{\mathrm{iend}})}^2+{({{\stackrel{\·}{T}}_i}^{\mathrm{opt}}-{\stackrel{\·}{T}}_{i\max })}^2---\left(7\right)$

$s.t.\left\{\begin{array}{c}\underset{\‾}{T_w}\≤T_w\≤\stackrel{\‾}{T_w}\\ \underset{\‾}{T_Q}\≤T_Q\≤\stackrel{\‾}{T_Q}\\ \underset{\‾}{T_t}\≤T_t\≤\stackrel{\‾}{T_t}\end{array}\right.$

In the formula:T _w 、respectively is the water temperature T_wThe upper and lower limit values of (c),T _Q 、respectively the flow rate of water_QThe upper and lower limit values of (c),T _t 、respectively the water passage time T_tUpper and lower limit values of (1).

(4) And preferably obtaining a water passing scheme optimized by concrete in each bin by adopting an optimization algorithm (such as a composite algorithm) with constraints.

(5) And analyzing each pouring bin of the typical dam section in the middle and later stages through water cooling one by one. According to the actual engineering situation, engineering experience and the like, the optimized water passing measures are slightly adjusted, and then water passing cooling in the middle and later periods is guided.

When the water cooling is rapidly regulated and controlled in the middle and later periods based on the optimization algorithm, the following problems need to be noticed

(1) When the concrete cooling curve is calculated by adopting a heat source-free water pipe cooling calculation formula, the temperature T of the concrete pouring bin at the beginning of the middle-stage cooling or the beginning of the second-stage cooling needs to be known_iThe temperature can be obtained as follows: the method comprises the following steps that firstly, a thermometer is buried in a concrete pouring bin, and the measured temperature is used as the temperature of the concrete pouring bin at the beginning of middle-stage cooling or the beginning of secondary cooling; in the second mode, before the middle-stage cooling or the second-stage cooling, the temperature is measured through water-tight temperature, and the temperature is used as the temperature of the concrete pouring bin at the beginning of the middle-stage cooling or the beginning of the second-stage cooling; in order to ensure the accuracy of obtaining the temperature of the concrete pouring bin, the weighted average calculation can be carried out on the temperature obtained in the first mode and the temperature obtained in the second mode.

(2) When the water cooling function phi is calculated, the concrete thermal conductivity coefficient, the plastic water pipe thermal conductivity coefficient and the like are involved, and the parameters are obtained by adopting design values and factory quality inspection values or performing parameter inversion based on measured temperature.

(3) In the middle-stage cooling or the second-stage cooling, the water temperature or the flow rate needs to be adjusted for cooling for a plurality of times, at this time, the main step of water cooling fast control in the middle and later stages is performed based on an optimization algorithm, which is similar to the step of cooling by adopting one water temperature and flow rate in the middle-stage cooling period and the second-stage cooling period, but the water feeding scheme of the concrete pouring bin temperature when the water temperature or the flow rate is adjusted for each time needs to be optimized. Because the calculation workload of the casting bin temperature dynamic prediction model based on the non-heat-source water pipe cooling calculation formula is small, the feasibility of a preferable water passing scheme can be ensured when the water temperature or the flow is adjusted every time.

Engineering examples

A high arch dam constructed in the southwest is divided into 31 dam sections, the dam crest elevation is 610m, and the maximum dam height is 285.5 m. In order to reduce the temperature of the concrete in the construction period to the arch sealing temperature, the concrete is cooled in three periods of first-stage cooling, middle-stage cooling, second-stage cooling and the like according to the characteristics of temperature control and crack prevention of the concrete of the arch dam, so that the effects of small temperature difference and slow cooling are achieved. Meanwhile, a poured area, a grouting area, a same cooling area, a transition area, a cover weight area and a pouring area are vertically arranged on the dam section to reduce the vertical temperature gradient and control the height of the cooling area. In order to better control the water cooling and obtain the temperature state of the dam concrete, a thermometer is buried in a concrete pouring bin for temperature monitoring. And 12 concrete pouring bins of a typical dam section are selected for optimized regulation and control analysis of water cooling in the middle and later periods, as shown in figure 3. The height of each irrigation area of the high arch dam is 9m, the thickness of a pouring bin is 3m, the first-stage cooling target temperature is 20 ℃, the middle-stage cooling target temperature is 16 ℃, and the second-stage cooling target temperature (arch sealing temperature) is 12 ℃. In the figure, the solid line represents the current temperature state of each pouring bin, the dotted line represents the cooling target temperature of each pouring bin, and analysis is carried out according to the water supply optimization regulation and control principle in the middle and later stages of the concrete.

(1) Determination of preference factors

The water cooling in the middle and later periods of the concrete dam needs to optimize 3 factors of water temperature, water flow and water time. Because in order to save the refrigeration cost, this high arch dam only provides two fender temperature: during the middle-stage cooling, adopting water temperature of 15-16 ℃, wherein the water temperature is close to the target temperature of the middle-stage cooling; and during the second-stage cooling, the water temperature is 8-9 ℃, and the water temperature is lower than the water temperature of the sealing arch. Therefore, in this actual concrete work, the water temperature of the water for the medium-stage cooling was set to 15.2 ℃ and the water temperature of the water for the second-stage cooling was set to 8.5 ℃. Only 2 water flow factors of the water flow rate and the water flow time are preferred.

(2) Value range of water supply measure

According to the engineering experience of the concrete dam and the actual engineering conditions, for middle-stage water cooling, the value range of water flow is selected to be 10-30L/min, and the value range of water time is selected to be 5-45 d; and for the second-stage water cooling, the value range of the water flow is selected to be 5-25L/min, and the value range of the water time is selected to be 5-25 d.

(3) Rapid regulation of water-passing measures

The method is characterized in that the distances among 12 concrete pouring bin water pipes of a typical dam section are 1.5m multiplied by 1.5m, polyethylene plastic water pipes are adopted, and as the concrete dam project is provided with a poured area, a grouting area, a co-cooling area, a transition area, a cover weight area and a pouring area in the vertical direction, the vertical direction temperature gradient of a concrete pouring block can be better prevented from being too large, the height of a cooling area can be better controlled, and meanwhile, the concrete project is subjected to small temperature difference and slow cooling in three periods. According to the actual measurement temperature statistical analysis of the concrete pouring bin after the concrete dam engineering finishes the middle-stage cooling and the second-stage cooling, the maximum daily cooling rate during the middle-stage and the second-stage water cooling meets the design requirement, and therefore, the optimized water flow and the optimized water passing time are determined mainly by the temperature information when the intercooling or the second cooling starts in the pouring bin and the intercooling or the second cooling target temperature in combination with a heat source-free water pipe cooling calculation formula and by adopting an optimization algorithm. The optimization algorithm adopts a composite algorithm with constraint conditions, and the constraint conditions of water flow and water passing time are the value range of water passing measures.

The water passing parameters of 12 concrete pouring bins in the middle and later water passing cooling stages are shown in a table 1, and the water passing measures are slightly adjusted according to the actual engineering conditions, the engineering experience and the like, and the time and the flow are adjusted and shown in the table 1. As can be seen from Table 1, the water cooling time of each concrete pouring bin is different, at this time, in order to ensure the uniformity of cooling, the concrete pouring bins are preferably cooled by middle-stage cooling and second-stage cooling at the same time, and when the cooling time of a certain concrete pouring bin reaches the preferable water flowing time, the pouring bin is switched to the temperature control stage.

TABLE 1 preferred water-flow measures for the individual casting bins

Claims (2)

1. A method for rapidly regulating and controlling water supply in the middle and later periods of a concrete dam is characterized by comprising the following steps: firstly, establishing a rapid water-passing prediction model in the middle and later stages of a concrete dam, dynamically updating important items of the rapid water-passing prediction model in the middle and later stages of the concrete dam based on the actual measured temperature of a concrete pouring bin to eliminate errors caused by uncertainty factors, then dynamically predicting the temperature response of a plurality of days in the future under the water-passing measure to be optimized, establishing a target function by dynamically predicting the temperature response and designing a temperature monitoring index, introducing an optimization algorithm, optimally obtaining the current optimal water-passing measure from the feasible domain space of the water-passing measure, regulating and controlling the water-passing cooling of 7-10 days in real time, obtaining the current actual measured temperature of the pouring bin again after 7-10 days, and dynamically updating, predicting, optimizing and regulating and controlling again;

the method specifically comprises the following steps: 1) the concrete dam temperature rapid prediction model during the middle and later period water cooling period is as follows:

in order to quickly and accurately predict the temperature of the concrete dam in the middle and later period of water cooling, a priori model with small calculation workload must be adopted, most of the hydration heat of the cement is released and heat preservation benzene plates are stuck on the upstream and downstream surfaces when the middle and later period of water cooling of the concrete dam is carried out, at the moment, the horizontal distance, the vertical distance, the material of the water pipe and the thermodynamic property of the concrete are also known, namely, the middle and later period cooling of the concrete of the dam is considered to be only a complicated multi-factor problem related to the water temperature, the water flow and the water time;

embedding a cooling water pipe in the concrete pouring bin for water cooling, setting the equivalent cooling diameter of the cooling water pipe in the pouring bin as D, the length as L, no heat source and the initial temperature of concrete as T₀Inlet water temperature of T_wThen the concrete average temperature is expressed as:

T＝T_w+(T₀-T_w)φ(1)

the water cooling function phi has the following two calculation formulas

(1) Water cooling function phi calculation formula 1

φ＝exp(-p₁τ^s)(2)

Wherein p is₁＝k₁(a/D²)^s，k₁＝2.08-1.174ξ+0.256ξ²，s＝0.971+0.1485ξ-0.0445ξ²，ξ＝λL/(c_wρ_wq_w) In the formula: a is the concrete temperature conductivity coefficient, D is the equivalent cooling diameter of a cooling water pipe in the pouring bin, lambda is the concrete heat conductivity coefficient, L is the length of the cooling water pipe, and c_wSpecific heat of cooling water, p_wFor the density of the cooling water, q_wThe flow rate is the water flow rate;

(2) water cooling function phi calculation formula 2

φ＝exp(-p₂τ)(3)

Wherein p is₂＝k₂a/D²，k₂＝2.09-1.35ξ+0.320ξ²Wherein a, D and ξ have the same meanings as above,

when b/c is not equal to 100, the temperature coefficient a in the calculation formula of the water cooling function phi adopts an equivalent temperature coefficient a ', and for the water pipe made of metal, the equivalent temperature coefficient a' is

a′＝1.947(α₁b)²a(4)

Wherein,wherein b/c ≠ 100; in the formula: b is the equivalent cooling radius, c is the outer radius of the metal water pipe,

for water pipe made of plastic, there are

$a^{\′}=\frac{ln100}{ln(b/c)+(\mathrm{\λ}/{\mathrm{\λ}}_1)ln(c/r_0)}a---\left(5\right)$

In the formula: lambda [ alpha ]₁Is the heat conductivity coefficient of the plastic water pipe, c is the outer radius of the plastic water pipe, r₀Is the inner radius of the plastic water pipe, the other symbols have the same meanings as the former symbols,

when the cooling time is longer, the calculation formula 1 of the water cooling function phi is adopted, when the cooling time is not more than 15 days, the calculation formula 2 of the water cooling function phi is adopted,

when the water flow is not changed and the cooling is carried out by adopting multi-gear water temperature, the average temperature of the concrete is calculated by adopting the following formula

T＝T_wi+(T_i-T_wi)φ_i(6)

In the formula: t is_wiFor the ith water-blocking temperature, T_iThe concrete temperature phi when the water temperature of the i-1 st water retaining pipe is finished and the water temperature of the i-1 st water retaining pipe is started_iFor the water cooling function when the water is introduced at the ith water stop temperature, the time tau in the water cooling function needs to start from 0,

when the water temperature is constant and the cooling is performed by adopting multi-step flow, the calculation formula of the average temperature of the concrete is similar to the formula (6), and similarly, the time tau in the water cooling function needs to be started from 0;

2) dynamic prediction model for casting bin temperature during middle and later period cooling of concrete dam

The heat source-free water pipe cooling calculation formula implies that the outer surface of the concrete prism with the cooling water pipe equivalent cooling diameter D in the pouring bin is an adiabatic boundary, and the hydration heat of the concrete prism is completely finished and is in a heat source-free state; the concrete pouring blocks in the middle and later cooling stages are not in a heat source-free state; in addition, the concrete pouring blocks in the middle and later period cooling stages are not in a heat insulation state, the external environment temperature still has certain influence on the temperature inside the concrete blocks, namely, the concrete pouring bin temperature prediction in the middle and later period cooling period is carried out by directly adopting the heat-source-free water pipe cooling calculation formula (6), the effect is not ideal, and the T in the heat-source-free water pipe cooling calculation formula is dynamically updated based on the current measured temperature of the concrete pouring bin_iTherefore, the problem that the temperature prediction effect of the heat source-free water pipe cooling calculation formula is not ideal is solved, and the temperature information of the concrete pouring bin in the future 7-10 days is accurately predicted;

3) concrete analysis step of concrete dam middle and later stage water cooling rapid regulation and control method

(1) The current temperature state and the current water-passing feasible region are obtained, firstly, the middle-period cooling starting time or two is obtainedTemperature T of concrete pouring bins of typical dam section at the beginning of cooling_i(ii) a Then determining the water passing temperature T according to engineering experience_wFlow rate of water T_QAnd water passing time T_tAn initial value of (1);

(2) dynamically predicting the temperature response of a plurality of days in the future, adopting the concrete dam temperature middle and later period water-passing dynamic prediction model based on the heat-source-free water pipe cooling calculation formula in the step 2) to calculate the concrete cooling curve, and obtaining the final cooling temperature T of each concrete pouring bin under the value combination of water-passing measures_iendAnd maximum daily cooling rate

(3) The calculated final cooling temperature and the maximum daily cooling rate under the middle-stage cooling or the secondary cooling are compared with the design target temperature T of the middle-stage cooling or the secondary cooling_i ^objAnd a suitable cooling rateThe sum of squares of the residuals is used as an objective function, and the water passing measure optimization model is established by

$\begin{array}{cc}\min & f(T_i,T_w,T_Q,T_t)={(T_i^{obj}-T_{iend})}^2+{({\stackrel{\·}{T}}_i^{opt}-{\stackrel{\·}{T}}_{imax})}^2\end{array}---\left(7\right)$

$s.t.\left\{\begin{array}{c}\underset{\‾}{T_w}\≤T_w\≤\stackrel{\‾}{T_w}\\ \underset{\‾}{T_Q}\≤T_Q\≤\stackrel{\‾}{T_Q}\\ \underset{\‾}{T_t}\≤T_t\≤\stackrel{\‾}{T_t}\end{array}\right.$

In the formula:T _w 、respectively is the water temperature T_wThe upper and lower limit values of (c),T _Q 、respectively the flow rate of water_QThe upper and lower limit values of (c),T _t 、respectively the water passage time T_tUpper and lower limit values of (d);

(4) optimally obtaining a water passing scheme for optimizing the concrete of each bin by adopting an optimization algorithm with constraints;

(5) analyzing each pouring bin of the typical dam section in the middle and later stages through water cooling one by one, slightly adjusting the optimized water-through measures according to the actual conditions and the experience of the engineering, and then guiding the middle and later stages through water cooling;

because the concrete dam temperature middle and later period water-filling dynamic prediction model based on the heat-source-free water pipe cooling calculation formula in the step 2) needs to know the concrete pouring bin temperature T at the beginning of middle-period cooling or the beginning of secondary cooling when calculating the concrete cooling curve_iThe temperature is obtained in the following way: the method comprises the following steps that firstly, a thermometer is buried in a concrete pouring bin, and the measured temperature is used as the temperature of the concrete pouring bin at the beginning of middle-stage cooling or the beginning of secondary cooling; in the second mode, before the middle-stage cooling or the second-stage cooling, the temperature is measured through water-tight temperature, and the temperature is used as the temperature of the concrete pouring bin at the beginning of the middle-stage cooling or the beginning of the second-stage cooling; or in order to ensure the accuracy of the temperature of the concrete pouring bin, the weighted average calculation is carried out on the temperature obtained in the first mode and the temperature obtained in the second mode;

when the middle-stage cooling or the second-stage cooling is performed, the water temperature or the flow rate needs to be adjusted for multiple times for cooling, at this time, the main step of performing the water cooling fast control in the middle and later stages based on the optimization algorithm is similar to the step of performing cooling by adopting one water temperature and flow rate in the middle and second-stage cooling periods, but the optimization of the water flowing scheme of the concrete pouring bin temperature when the water temperature or the flow rate is adjusted is performed every time, and the feasibility of the preferable water flowing scheme is ensured because the calculation workload of the concrete dam temperature middle and later-stage water flowing dynamic prediction model based on the heat-source-free water pipe cooling calculation formula in the step 2) is small.

2. The method for rapidly regulating and controlling water passing in the middle and later periods of the concrete dam as claimed in claim 1, wherein: when the water cooling function phi is calculated, the concrete thermal conductivity coefficient, the thermal conductivity coefficient and the plastic water pipe thermal conductivity coefficient are involved, and the parameters are obtained by adopting a design value and a manufacturer quality inspection value or performing parameter inversion based on an actual temperature.