Engineering calculation method for annual dynamic heat and moisture transfer amount of surrounding rock in underground space

Abstract

The invention relates to the technical field of underground space heat and humidity environments, in particular to an engineering calculation method for annual dynamic heat and humidity transfer quantity of underground space surrounding rock, which comprises the following steps of: establishing a surrounding rock heat and humidity coupling transfer mathematical model, solving the internal temperature and relative humidity of the surrounding rock at any moment, and dynamically calculating a surrounding rock heat and humidity coupling transfer process by taking a year as a unit; counting the annual average heat absorption capacity, heat release capacity, heat absorption time and heat release time of the surrounding rock wall surface; determining sensitive factors influencing the heat transfer capacity and the moisture transfer capacity of the surrounding rock; and by taking the sensitive factors of the heat transfer capacity and the moisture transfer capacity of the surrounding rock obtained by sensitivity analysis as independent variables, fitting calculation formulas of the annual average moisture absorption capacity, the moisture liberation capacity, the moisture absorption time and the moisture liberation time of the surrounding rock, and generating an annual dynamic load prediction result of the surrounding rock. The method solves the problem that current underground space surrounding rock heat transfer and heat transfer quantity engineering calculation is too rough, and meanwhile, compared with a traditional dynamic numerical calculation method, the calculation process can be simplified, and the calculation time can be shortened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underground space heat and humidity environment, and particularly relates to an engineering calculation method of annual dynamic heat and humidity transfer of surrounding rock of underground space. BACKGROUND

[0002] At present, urban underground space is in a rapid development stage, and realizing "low carbon" and "green" development has become a key goal of underground space development. The underground space environment has its particularity, such as strong heat storage capacity of surrounding rock, less influence of outdoor meteorological parameters, and generally existing humidity. These characteristics make the control and improvement of the underground space environment more dependent on artificial means.

[0003] In the control of underground space heat and humidity environment, load calculation is the first step and the most important link. However, the existing load calculation method usually calculates the heat and humidity transfer of the surrounding rock of underground space in a steady state. This simplified calculation method leads to a large deviation between the actual state and the heat and humidity transfer load of the surrounding rock, thereby affecting the operation energy efficiency of the air conditioning system. Therefore, it is urgent to study a more reasonable heat and humidity load calculation method according to the heat and humidity characteristics of underground space.

[0004] In addition, the heat and humidity coupling transfer process of the surrounding rock of underground space is very complex, which brings great challenges to the prediction of the heat and humidity load of underground space. The traditional calculation method is often too rough to accurately reflect the dynamic change process of the heat and humidity transfer of the surrounding rock. Therefore, developing an engineering calculation method capable of accurately calculating the annual dynamic heat and humidity transfer of the surrounding rock of underground space has very important significance for the green and sustainable development and utilization of underground space. SUMMARY

[0005] In order to solve the above problems, the present application provides an engineering calculation method of annual dynamic heat and humidity transfer of surrounding rock of underground space, which solves the problem that the current engineering calculation of heat and humidity transfer of surrounding rock of underground space is too rough, and can simplify the calculation process and shorten the calculation time compared with the traditional dynamic numerical calculation method.

[0006] The technical scheme of the present application is as follows: An engineering calculation method of annual dynamic heat and humidity transfer of surrounding rock of underground space, characterized in that it comprises the following steps: establishing a heat and humidity coupling transfer mathematical model of the surrounding rock, solving the temperature and relative humidity inside the surrounding rock at any time, and dynamically calculating the heat and humidity coupling transfer process of the surrounding rock in units of years according to the time range of the heat and humidity load prediction of the surrounding rock; based on the calculation results of the previous step, statistically calculating the annual average heat absorption and heat release of the surrounding rock wall surface, the heat absorption time and the heat release time in units of years; determining the sensitive factors affecting the heat and humidity transfer of the surrounding rock; The sensitive factors of the heat and moisture transfer of the surrounding rock obtained by the sensitivity analysis are used as independent variables to fit the calculation formulas of the annual average moisture absorption and release amounts and the moisture absorption and release times of the surrounding rock, and the annual dynamic load prediction results of the surrounding rock are generated.

[0007] The mathematical model of the heat and moisture coupling transfer of the surrounding rock includes: ; ; In the formula: the slope of the isothermal moisture absorption equilibrium curve of the material; the relative humidity of the material; time variable, s; spatial coordinate in one-dimensional direction, m; temperature, ℃; the specific heat capacity at constant pressure of the surrounding rock in a dry state, J / (kg·K); the dry density of the surrounding rock, kg / m³; the specific heat capacity of liquid water, taken as 4200 J / (kg·K); moisture content, kg / kg; the effective thermal conductivity of the surrounding rock, W / (m·K); the heat transfer coefficient caused by the relative humidity gradient; the mass transfer coefficient caused by the relative humidity gradient, kg / (m·s); the mass transfer coefficient caused by the temperature gradient, m 2 / (s·K).

[0008] The formula of the effective thermal conductivity of the surrounding rock is as follows: ; The formula of the heat transfer coefficient caused by the relative humidity gradient is as follows: ; In the formula: the effective thermal conductivity of the material, W / (m·K); the latent heat of evaporation, a single-valued function of temperature; - water vapor permeability coefficient, kg / (m-s-Pa); - saturated water vapor partial pressure, a single-valued function of temperature, Pa.

[0009] The initial conditions of the mathematical model of heat and moisture coupled transfer of surrounding rock are set as follows: ; wherein, is the initial temperature, is the initial relative humidity.

[0010] The boundary conditions of the mathematical model of heat and moisture coupled transfer of surrounding rock include inner boundary conditions and far boundary conditions; Inner boundary conditions: ; Far boundary conditions: ; In the formula: - surface mass transfer coefficient of convection, s / m; - surface heat transfer coefficient of convection, W / (m 2 ·K); - indoor relative humidity; - indoor saturated water vapor partial pressure, Pa; - wall relative humidity; - wall saturated water vapor partial pressure, Pa; - indoor temperature, K; - wall temperature, K; - far boundary temperature, K; - far boundary relative humidity.

[0011] The solving process of the mathematical model equation of heat and moisture coupled transfer of surrounding rock is as follows: Define known parameters, set space step and time step and carry out grid division; In time advancing calculation, a time step is a time layer, and the calculation of temperature, relative humidity and moisture content of all nodes at a certain calculation time is completed; In the calculation of each time layer, the temperature and humidity of the previous time are set as the budget values of the time, are brought into the coefficient matrix to convert the nonlinear equation set into a linear equation set, and iterative calculation is performed until the temperature and humidity difference between the previous and next iterations reaches the required calculation accuracy, and the calculation value of the current iteration step is taken as the calculation value of the time; By analogy, the simulation calculation of the heat and moisture coupling transmission of the surrounding rock is realized.

[0012] In the step of determining the sensitive factors affecting the heat and moisture transmission of the surrounding rock and the heat and moisture absorption and release time length of the surrounding rock wall surface, an orthogonal test method is used to design the simulation conditions, and the influence factors and significance of the heat and moisture transmission of the surrounding rock wall surface are analyzed.

[0013] The orthogonal test method is used to design the simulation conditions, the annual average heat and moisture absorption and release amount and the heat and moisture absorption and release time length of the surrounding rock wall surface are taken as the observation indexes of the orthogonal test, the importance and significance of each factor are analyzed by comparing the range sizes corresponding to different air influence factor parameters, and the greater the range is, the more significant the influence is, and the more important the factor is.

[0014] The air influence factors are selected as the annual temperature amplitude, the annual average temperature, the annual humidity amplitude and the annual average humidity.

[0015] According to the functional approximation relationship between the four factors of the annual temperature amplitude, the annual average temperature, the annual humidity amplitude and the annual average humidity and the annual average heat and moisture absorption and release amount and the heat and moisture absorption and release time length of the surrounding rock wall surface, the form of the fitting formula is determined. According to the significance analysis, the significant and very significant factors are selected as the independent variables, and the prediction formula of the annual average heat and moisture absorption and release amount and the heat and moisture absorption and release time length of the surrounding rock wall surface is fitted.

[0016] The beneficial effects of the present application are as follows: 1. The engineering calculation method for the annual dynamic heat and moisture transmission amount of the surrounding rock of the underground space improves the calculation accuracy, can more accurately calculate the temperature and relative humidity in the surrounding rock at any time by establishing a surrounding rock heat and moisture coupling transmission mathematical model and using the finite volume method for discrete solution, can more truly reflect the dynamic process of the heat and moisture transmission of the surrounding rock of the underground space compared with the traditional steady-state calculation method, and thus improves the accuracy of load calculation.

[0017] 2. The engineering calculation method for the annual dynamic heat and moisture transmission amount of the surrounding rock of the underground space simplifies the calculation process, although the dynamic numerical calculation method can more accurately simulate the heat and moisture transmission process in theory, but the calculation is complex and time-consuming, the method provided by the present application significantly shortens the calculation time and improves the efficiency of engineering application while maintaining high calculation accuracy.

[0018] 3. The engineering calculation method for annual dynamic heat and moisture transfer of underground space surrounding rock provides a scientific and accurate theoretical basis for the design of underground space air conditioning systems. Through accurate calculation of the dynamic heat and moisture transfer of surrounding rock, the selection of air conditioning systems, capacity determination and operation strategies can be more effectively guided, thereby achieving energy saving, environmental protection and comfort in underground space.

[0019] 4. The engineering calculation method for annual dynamic heat and moisture transfer of underground space surrounding rock provides an accurate heat and moisture load calculation method, which helps to optimize the environmental control strategy of underground space, reduce energy consumption and environmental pollution, and promote the green development of underground space.

[0020] 5. The engineering calculation method for annual dynamic heat and moisture transfer of underground space surrounding rock not only has theoretical innovation, but also has strong engineering practicability. Through sensitivity analysis and fitting of prediction formulas, the heat and moisture load can be quickly estimated according to specific engineering conditions, providing strong support for the design, construction and operation management of underground space engineering. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Figure 1 is a flowchart of the engineering calculation method for annual dynamic heat and moisture transfer of underground space surrounding rock; Figure 2 Figure 2 is a grid division diagram of the solving region in the solving process of the heat balance and moisture balance equation discrete equation set using the TDMA algorithm; Figure 3 Figure 3 is a grid division diagram of the internal node in the solving process of the heat balance and moisture balance equation discrete equation set using the TDMA algorithm; Figure 4 Figure 4 is a grid division diagram of different material interface nodes in the solving process of the heat balance and moisture balance equation discrete equation set using the TDMA algorithm; Figure 5 Figure 5 is a flowchart of the solution of the heat balance and moisture balance equation; Figures 6 to 9 Figure 6 is the influence of different factors on the heat absorption and release amount and time of surrounding rock in the embodiment; Figures 10 to 13 Figure 7 is the influence of different factors on the moisture absorption and release amount and time of surrounding rock in the embodiment. DETAILED DESCRIPTION

[0022] The application will be described in further detail below with specific reference being made to the drawings. Like elements in different embodiments are denoted by like reference numerals. In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the application. However, it will be apparent to one skilled in the art that the application can be practiced without the specific details given herein. In other instances, well-known features are not described in detail to avoid obscuring the application. In this description, all temperatures are in degrees Celsius (°C) unless otherwise indicated. All relative humidity (RH) values are in percent (%) unless otherwise indicated.

[0023] In addition, features, operations, or steps described in the specification can be combined in any suitable manner without departing from the scope of the present application. Similarly, steps in methods described herein can be performed in an order different than described without departing from the scope of the application. Accordingly, the description and drawings are to be regarded as illustrative in nature and not as restrictive.

[0024] As shown in Figure 1 The engineering calculation method of the annual dynamic heat and moisture transfer of the surrounding rock of the underground space includes the following steps: Surrounding rock heat and moisture coupled transfer model and temperature and humidity distribution solving: a surrounding rock heat and moisture coupled transfer mathematical model is established, and the finite volume method is used to discretely solve the temperature and relative humidity inside the surrounding rock at any time; according to the time range predicted by the surrounding rock heat and moisture load, the dynamic calculation of the surrounding rock heat and moisture coupled transfer process is completed in units of years; Surrounding rock wall surface annual average heat and moisture absorption and release performance statistics: according to the results obtained in step one, the average heat and moisture absorption and release amounts and times of the surrounding rock wall surface in each year are calculated in units of years; Surrounding rock wall surface heat and moisture absorption and release sensitivity analysis: the sensitive factors affecting the heat and moisture transfer amounts of the surrounding rock with time are determined through orthogonal analysis in units of years; Surrounding rock wall surface heat and moisture load prediction formula: the sensitive factors affecting the heat and moisture transfer amounts of the surrounding rock obtained through the sensitivity analysis are taken as independent variables, and the average heat and moisture absorption and release amounts and times of the surrounding rock in each year are calculated, so as to obtain the annual dynamic load condition.

[0025] Further, the surrounding rock heat and moisture coupled transfer model is a one-dimensional heat and moisture coupled transfer model of a non-saturated porous medium, which includes a heat balance model and a moisture balance model, and temperature and relative humidity are taken as driving potentials, respectively.

[0026] The surrounding rock heat and moisture coupled transfer model is: ; wherein: — the slope of the material isothermal moisture sorption equilibrium curve; — the relative humidity of the material; — the time variable, s; — the spatial coordinate in one-dimensional direction, m; — the temperature, °C.

[0027] ; wherein: — the specific heat capacity at constant pressure of the surrounding rock in dry state, J / (kg·K); — the dry density of the surrounding rock, kg / m³; — the specific heat capacity of liquid water, taken as 4200 J / (kg·K); — the moisture content, kg / kg; — the effective thermal conductivity of the surrounding rock, W / (m·K); — the effective thermal conductivity of the material, W / (m·K); — the latent heat of evaporation, a single-valued function of temperature; — the water vapor permeability coefficient, kg / (m·s·Pa); — the saturated water vapor partial pressure, Pa, which is a single-valued function of temperature and can be calculated by ; — the heat transfer coefficient caused by the relative humidity gradient; — the mass transfer coefficient caused by the relative humidity gradient, kg / (m·s); — the mass transfer coefficient caused by the temperature gradient, m 2 / (s·K).

[0028] The initial conditions of the above model are set as follows: ; wherein, is the initial temperature, is the initial relative humidity.

[0029] The underground space is mostly located in the isothermal layer, and the temperature of the underground isothermal layer is considered to be approximately equal to the local annual average surface temperature. The special nature of the microclimate of the underground space and the presence of groundwater make the humidity of the surrounding rock higher, so the initial relative humidity of the surrounding rock is 85%.

[0030] The boundary conditions of the above model include: inner boundary conditions and far boundary conditions.

[0031] Inner boundary conditions: the inner surface of the surrounding rock and the air inside the underground space simultaneously conduct heat and moisture transfer in the form of convection, and the boundary condition of the inner surface is a convective boundary condition: ; Far boundary conditions: the far boundary of the model is located deep in the semi-infinite object, where the temperature and humidity of the surrounding rock are almost unaffected by heat and moisture transfer, and always maintain the initial thermal and humid state, so the far boundary is a constant temperature and humidity boundary: ; In the formula: - surface convective mass transfer coefficient, s / m; - surface convective heat transfer coefficient, W / (m 2 ·K); - indoor relative humidity; - indoor saturated water vapor partial pressure, Pa; - wall relative humidity; - wall saturated water vapor partial pressure, Pa; - indoor temperature, K; - wall temperature, K; - far boundary temperature, K; - far boundary relative humidity.

[0032] The solution process of the heat balance and moisture balance equations is as follows: define the known parameters, set the space step and time step, and divide the grid. In the time advancing calculation, a time step is a time layer, and the calculation of the temperature, relative humidity, and moisture content of all nodes at a certain calculation time is completed. When calculating each time layer, set the temperature and humidity at the previous time as the budget value at this time, bring it into the coefficient matrix to convert the nonlinear equation set into a linear equation set, and perform iterative calculation until the temperature and humidity difference between the previous and next iterations reaches the required calculation accuracy. The calculation value of the current iteration step is taken as the calculation value at this time, and the simulation calculation of the heat and moisture coupled transfer of the surrounding rock is realized in this way.

[0033] The solving method of the discrete equation set of heat balance and moisture balance equations is given by using TDMA algorithm: (1) Discretization of control equation: The finite volume method is used to discretize the mathematical model of heat and moisture coupled transfer in surrounding rock. Variable grid size is adopted in meshing. When the node division is uneven, the outer node method has higher accuracy than the inner node method. At the same time, there is a problem of discontinuity of some parameters at the interface of different materials. In order to improve the solving accuracy, nodes need to be set at the interface. Considering the above factors, the outer node method is selected as the regional discretization method, as shown in Fig. 1. Implicit format is used for solving. Figure 2

[0034] Discretization of internal nodes: the division of internal nodes of surrounding rock is shown in Fig. 2. The moisture balance control equation (1) is integrated in time and space: Figure 3 (1) where, is the space, is the volume of the control volume, is the time step; In the non-steady term on the left side of the equation, the partial derivative of relative humidity with respect to time is taken in the difference. The discretization of the diffusion term on the right side of the equation uses central difference: (2) (3) (4) (5) (6) (7) After integration, we get: (8)

[0035] (9)

[0036] (10) After discretization of the moisture balance equation, we can arrange it as: (11) where, ; ; ; ;​​ ; The upper index "0" represents the value at the last time, without the upper index represents the value at this time, the subscript "C" represents the current calculation control body center, "L" represents the left control body center, "R" represents the right control body center, "L" represents the left interface of the control body, "R" represents the right interface of the control body. For the calculation of the coefficient at the control volume interface, the harmonic average method is adopted, that is: P W E w P e P ; ; ; ; Similarly, the heat balance equation is discretized: (12) (13) (14) (15) (16) After the heat balance equation is discretized, it can be arranged as: (17) In the formula: ; ; ; ; ; For the calculation of the coefficient at the control volume interface, the harmonic average method is adopted, that is: ; ; ; ;

[0037] In the formula: - The volume of the control volume; - Spatial step​​​​​​​ —Time step.

[0038] Material interface node discretization: The node division of different material interfaces is as follows Figure 4 As shown, the contact thermal resistance and moisture resistance of the interface are ignored in the calculation. The specific heat capacity and density at the interface can be taken as the arithmetic average of the two materials, while the moisture content, thermal conductivity, and liquid water permeability coefficient can be taken as the average of the two materials. , water vapor permeability coefficient , liquid water diffusion coefficient , slope of moisture absorption curve The parameter value corresponding to the interface can be expressed by the harmonic mean.

[0039] ; ; ; ; ; ; ; Substitute the above parameter calculation formula into the heat and moisture balance equation, and then discretize the interface nodes according to the above discretization method.

[0040] Boundary node discretization: This study uses the exterior node method to discretize the control equations, with the inner surface as the first node and the far boundary as the last node. The volumes of the inner surface unit cell and the far boundary unit cell are both half of the volume of the inner unit cell.

[0041] Converting the inner surface convection mass transfer boundary conditions into the form of inner surface unit body, we can get: (18) Discretizing the above formula, we can get: (19) Arranged into a common format: (20) Where: ; ; ; ; Converting the convective heat transfer boundary conditions on the inner surface into the form of inner surface unit body, we can obtain: (twenty one) Discrete the above formula, we get: (22) Arrange into a general format: (23) In the formula: ; ; ; ; In summary, the discrete control equation and boundary conditions of the heat and moisture transfer in surrounding rock can be expressed in a unified format: (24) (25) (2) Control equation solution: According to the analysis above, the discrete heat and moisture balance equations of surrounding rock give n algebraic equations, respectively, that is Discrete equations of moisture balance: (26) Discrete equations of heat balance: (27) Both can be written in the form of matrix equation: (28) In the formula: ; ; ; ; ; ; Figure 5 The flow chart for solving the heat and moisture balance equations, where is the initial temperature, is the initial relative humidity, and are the pre-computed values at the current time, iter is the current iteration time step, is the time step, Time is the current calculation time, Tmax is the maximum calculation time, is the humidity result matrix, is the temperature result matrix, and is a coefficient matrix, and is a dependent variable matrix, and r1 and r2 are calculation accuracies.

[0042] Further, the orthogonal test method is used to design simulation working conditions, and influence factors and significance of wall surface heat and moisture transfer amount, heat and moisture transfer time of surrounding rock are analyzed. The wall surface heat and moisture transfer amount of surrounding rock refers to the average heat and moisture transfer amount of surrounding rock in a year, and the heat and moisture transfer time refers to the heat absorption time and heat release time of surrounding rock in a year, which is an index for investigation of the orthogonal test. The influence factors include annual temperature amplitude, annual average temperature, annual humidity amplitude and annual average humidity. The importance and significance of each factor are analyzed by comparing the range sizes corresponding to the four influence factors. The greater the range is, the more significant the influence is, and the more important the factor is.

[0043] Further, in combination with relevant design specifications and measured data, the indoor temperature and humidity of underground buildings are maintained at 10-32.5℃ and 30%-85% throughout the year, and the recommended factor level is set as shown in the following table.

[0044]

[0045] According to the requirements of the orthogonal table and the factor level table, the parameter table of each test group is shown in the following table.

[0046]

[0047] The air temperature and humidity of each working condition can be expressed as the following formula, which ensures that the parameters other than the above four factors are unchanged in each working condition.

[0048] ; ; Further, the heat and moisture coupling transfer model is used to simulate the heat and moisture coupling transfer process of surrounding rock in the above working condition distribution, and the temperature and humidity distribution of surrounding rock at any time, and the wall surface heat and moisture transfer are obtained. On this basis, the annual average heat release amount, annual average heat absorption amount, annual average moisture absorption amount, annual average moisture release amount, heat absorption and release time, and moisture absorption and release time are calculated, and the single-factor effect diagram of different factors on the above physical quantities is drawn, and the functional correspondence relationship between the dependent variables and the independent variables is analyzed.

[0049] Further, the significance of the above factors is analyzed. The variance analysis method is used to decompose the total difference of data into two parts caused by error and caused by factor change, construct F statistic, make F test, and judge the significance of the effect of each factor. When F>99.01, the influence is very significant, when F<19, the influence is not significant, when 19<F<99.01, the influence is significant, and the significant factors are screened out.

[0050] The heat and moisture transfer prediction formula of the surrounding rock wall surface: according to the functional approximation relationship between the four factors of the annual temperature amplitude, the annual average temperature, the annual humidity amplitude and the annual average humidity of air and the annual average heat and moisture absorption and release amount and the heat and moisture absorption and release time length of the surrounding rock wall surface, the form of the fitting formula is determined; according to the significance analysis, the significant and very significant factors are selected as independent variables, and the prediction formula of the annual average heat and moisture absorption and release amount and the heat and moisture absorption and release time length of the surrounding rock wall surface is fitted, that is, the engineering calculation formula of the dynamic heat and moisture transfer amount of the underground space surrounding rock. Embodiment

[0051] The envelope structure of the embodiment is composed of 0.35 m concrete lining and 50 m rock-soil, and the thermal and moisture physical parameters of the concrete and rock-soil are obtained by consulting relevant literature (see the table below).

[0052]

[0053] According to the orthogonal analysis experiment table, the annual dynamic simulation of the heat and moisture coupling of the surrounding rock under different working conditions is carried out. The finite volume method is used to discretize the control equation, the variable grid size is used in the depth direction of the surrounding rock, the grid size is 0.005 m within 0-20 m from the wall surface of the surrounding rock, and the grid size is 0.02 m from 20 m to 50.35 m, and the calculation time length is 1 year. The wet balance and heat balance discrete equation set is obtained, and the TDMA algorithm is used to uniformly solve the discrete equation set, and the temperature and humidity distribution of the surrounding rock at any time and the wall surface heat and moisture transfer are obtained. On this basis, the annual average heat release amount, the annual average heat absorption amount, the annual average moisture absorption amount, the annual average moisture release amount, the heat absorption and release time length, and the moisture absorption and release time length are calculated, and the single-factor effect diagram of different factors on the above physical quantities is drawn, and the functional corresponding relationship between the independent variables and the dependent variables is analyzed.

[0054] The single-factor curve diagram of the annual average heat release amount, the annual average heat absorption amount, the annual average moisture absorption amount, the annual average moisture release amount, the heat absorption and release time length, and the moisture absorption and release time length of each factor under different levels is drawn.

[0055] As shown in Figures 6 to 9 , the annual average moisture release amount and the moisture absorption amount of the surrounding rock under different factors and different levels are described, Figure 6 the annual average heat release amount; Figure 7 the annual average heat absorption amount; Figure 8 the annual average heat release time length; Figure 9 the annual average heat absorption time length.

[0056] According to Figure 6 It can be seen that among the four factors, only the annual average temperature is inversely proportional to the annual average heat release amount of the surrounding rock, the annual temperature amplitude, the annual humidity amplitude and the annual average humidity are all proportional to the heat release amount of the surrounding rock, and it can be seen that the four influencing factors and the heat release amount of the surrounding rock all show an approximate linear correlation. According to Figure 7It can be seen that only the annual humidity amplitude is inversely proportional to the annual average heat absorption of the surrounding rock, and the annual temperature amplitude, the annual average temperature and the annual average humidity are all proportional to the heat absorption of the surrounding rock. Similarly, the four influencing factors are also approximately linearly correlated with the heat absorption of the surrounding rock. Figure 8 and Figure 9 The average value of the annual average heat absorption and release time of the surrounding rock under each level of each factor is described. For the heat release time of the surrounding rock, only the annual temperature amplitude is positively correlated therewith, and the annual average temperature, the annual humidity amplitude and the annual average humidity are all inversely correlated therewith. Conversely, the annual temperature amplitude is inversely correlated with the heat absorption time of the surrounding rock, and the annual average temperature, the annual humidity amplitude and the annual average humidity are all positively correlated with the heat absorption time of the surrounding rock. The four influencing factors are approximately linearly correlated with the heat absorption and release time of the surrounding rock.

[0057] Figures 10 to 13 For the influence of different factors on the moisture absorption and release amount and time of the surrounding rock in the examples, Figure 10 is the annual average heat release amount; Figure 11 is the annual average heat absorption amount; Figure 12 is the annual average heat release time; Figure 13 is the annual average heat absorption time.

[0058] According to Figure 10 It can be seen that the four factors are all positively correlated with the annual average heat release amount of the surrounding rock and are approximately linearly correlated, and Figure 11 It can be derived that only the annual temperature amplitude is inversely correlated with the annual average heat absorption amount of the surrounding rock, and the annual average temperature, the annual humidity amplitude and the annual average humidity are all positively correlated with the heat absorption amount of the surrounding rock. Figure 12 and Figure 13 The average value of the annual average heat absorption and release time of the surrounding rock under each level of each factor is described. For the heat release time of the surrounding rock, the annual temperature amplitude and the annual average temperature are positively correlated therewith, and the annual humidity amplitude and the annual average humidity are inversely correlated therewith. Conversely, the annual temperature amplitude and the annual average temperature are inversely correlated with the heat absorption time of the surrounding rock, and the annual humidity amplitude and the annual average humidity are positively correlated with the heat absorption time of the surrounding rock. The four influencing factors are approximately linearly correlated with the heat absorption and release time of the surrounding rock.

[0059] According to the calculation results, the variance analysis table of the average heat release amount, the annual average heat absorption amount, the annual average heat absorption amount, the annual average heat release amount, the heat absorption and release time and the heat absorption and release time is obtained. According to the information in the table, it can be seen that the annual temperature amplitude and the annual average temperature have a very significant influence on the annual average heat absorption amount of the surrounding rock; the annual average temperature has a significant influence on the heat absorption and release time of the surrounding rock; the annual humidity amplitude has a significant influence on the heat release amount of the surrounding rock; and the annual humidity amplitude and the annual average humidity have a significant influence on the heat absorption amount of the surrounding rock and the heat absorption and release time of the surrounding rock.

[0060] According to the analysis of the variance analysis table shown in the following table, the annual temperature amplitude of air, the annual average temperature of air, the annual humidity amplitude of air and the annual average humidity of air are approximately linearly related to the annual average heat and moisture absorption and release amount and the time length of surrounding rock, so linear relationship is taken as the starting point, and it is assumed that the annual temperature amplitude of air, the annual average temperature of air, the annual humidity amplitude of air and the annual average humidity of air are respectively, according to the significance analysis, the significant and very significant factors are selected as independent variables, and the multiple linear regression is used to fit the prediction formula of the annual average heat and moisture absorption and release amount and the time length of surrounding rock.

[0061]

[0062] (1) Heat absorption and release amount and time length: Annual average heat release amount (R2=1): ; Annual average heat absorption amount (R2=0.999): ; Heat release time length (R2=0.985): ; Heat absorption time length (R2=0.985): ; (2) Moisture absorption and release amount and time length: Annual average moisture release amount (R2=0.968): ; Annual average moisture absorption amount (R2=0.95): ; Moisture release time length (R2=0.92): ; Moisture absorption time length (R2=0.92): ; Multiple linear regression basic steps: 1. Determine the model form: the basic form of the multiple linear regression model is: ; Wherein, Y is the dependent variable, X 1 ,X 2 ,...,X n X is the independent variable, β 0 is the intercept, β 1 ,β 2 ,...,β is the regression coefficient, is the error term.

[0063] 2. Least Squares Fitting: The core of the fitting lies in using the least squares method to estimate the regression coefficients. The goal of the least squares method is to minimize the sum of the squares of the residuals between the actual observations and the model predictions: ; Where Yi: Actual observation (true value), represents the true value of the dependent variable in the i-th observation sample. : Predicted value (fitted value), represents the predicted value of the dependent variable for the i-th observation sample calculated using the regression model. It is calculated based on the values of the independent variables and the regression coefficients.

[0064] 3. Matrix Representation: In multiple linear regression, matrix form can be used to simplify calculations.

[0065] Let Y be the vector of dependent variables; X be the design matrix of independent variables (including the constant term); β be the vector of regression coefficients; Then it can be represented as: ; Through the matrix solution of the least squares method, we get: ; Where, : Estimated regression coefficient vector, represents the regression coefficients of each independent variable estimated by the least squares method. It contains the influence degree of all independent variables on the dependent variable. X: Design matrix (or independent variable matrix), which contains the observation values of all independent variables. Each row represents an observation sample, and each column represents an independent variable. Usually, the first column of the design matrix is all 1, representing the intercept term (β0). T : Transpose of the design matrix, which represents the exchange of rows and columns of the matrix X. The transposed matrix displays the observation values of the independent variables in column form. Y: Observation value vector of the dependent variable, containing the actual values of the dependent variable for all observation samples. It is a column vector, usually the same as the number of rows of the design matrix X.

[0066] 4. Model Evaluation: After fitting, the performance of the model needs to be evaluated. The coefficient of determination R2 is usually used to measure the degree of explanation of the model to the variation of the dependent variable. The value of R2 is between 0 and 1, and the higher the value, the better the fitting effect of the model.

[0067] The above application uses specific examples to illustrate the invention, which is only used to help understand the invention and does not limit the invention. For those skilled in the art to which the invention belongs, according to the idea of the invention, some simple deductions, deformations or substitutions can be made.

Claims

1. An engineering calculation method for annual dynamic heat and moisture transfer in underground space surrounding rock, characterized in that, The method comprises the following steps: a mathematical model of heat and moisture coupled transfer of the surrounding rock is established, and the temperature and relative humidity of the surrounding rock at any time are solved, and the heat and moisture coupled transfer process of the surrounding rock is dynamically calculated in years according to the time range of the heat and moisture load prediction of the surrounding rock; the annual average heat absorption and heat release of the surrounding rock wall surface, the heat absorption time and the heat release time are calculated in years based on the calculation results of the previous step; sensitive factors affecting the heat and moisture transfer of the surrounding rock are determined; the sensitive factors of the heat and moisture transfer of the surrounding rock obtained through the sensitivity analysis are taken as independent variables, and a fitting formula of the annual average moisture absorption and moisture release, the moisture absorption time and the moisture release time of the surrounding rock is fitted to generate the annual dynamic load prediction results of the surrounding rock.

2. The method according to claim 1, wherein the method is characterized by, The mathematical model of heat and moisture coupled transfer of the surrounding rock comprises: ； ； In the formula, - the slope of the isothermal moisture sorption equilibrium curve; - relative humidity of the material; - time variable, s; - spatial coordinates in one-dimensional direction, m; - Temperature, °C; - specific heat capacity at constant pressure in dry state of the surrounding rock, J / (kg K); - dry density of the surrounding rock, kg / m3; - specific heat capacity of liquid water, taken as 4200 J / (kg K); - moisture content, kg / kg; — effective thermal conductivity of the surrounding rock, W / (m K); — heat transfer coefficient due to relative humidity gradient; - mass transfer coefficient due to relative humidity gradient, kg / (m-s); - mass transfer coefficient, m, caused by the temperature gradient 2 (s K).

3. The method according to claim 2, wherein the method is characterized by, The formula of the effective thermal conductivity of the surrounding rock is as follows: ； The formula of the heat transfer coefficient caused by the relative humidity gradient is as follows: ； In the formula, - effective thermal conductivity of the material, W / (m K); - latent heat of vaporization, single-valued function of temperature; - water vapour permeability coefficient, kg / (m-s-Pa); - the saturation water vapour partial pressure, the single-valued function of temperature Pa.

4. The method according to claim 3, wherein the method is characterized by, The initial conditions of the mathematical model of heat and moisture coupled transfer of the surrounding rock are set as follows: ； wherein is the initial temperature, is the initial relative humidity.

5. The method according to claim 4, wherein the method is characterized by, The boundary conditions of the mathematical model of heat and moisture coupled transfer of the surrounding rock include internal boundary conditions and remote boundary conditions. Internal boundary conditions: ； Remote boundary conditions: ； In the formula, - surface convective mass transfer coefficient, s / m; - surface convective heat transfer coefficient, W / (m 2 · K); - indoor relative humidity; - indoor saturated water vapour partial pressure, Pa; — wall relative humidity; - wall surface saturated water vapor partial pressure, Pa; - indoor temperature, K; - wall temperature, K; — far boundary temperature, K; — Far boundary relative humidity.

6. The method according to claim 5, wherein the method is characterized by, The solving process of the mathematical model of heat and moisture coupled transfer of the surrounding rock is as follows: Define known parameters, set spatial step and time step, and divide the grid; In the time advancing calculation, one time step is taken as one time layer, and the temperature, relative humidity and moisture content of all nodes at a certain calculation time are calculated; In the calculation of each time layer, the temperature and humidity of the previous time are set as the budget value of the current time, and are brought into the coefficient matrix to convert the nonlinear equation set into a linear equation set, and the iteration calculation is performed until the temperature and humidity difference between the previous and next iteration calculations reaches the required calculation accuracy, and the calculation value of the current iteration step is taken as the calculation value of the current time; In this way, the simulation calculation of the heat and moisture coupled transfer of the surrounding rock is realized.

7. The method according to claim 1, wherein the method is characterized by, In the step of determining the sensitive factors affecting the heat and moisture transfer of the surrounding rock and the heat and moisture absorption and release time of the surrounding rock wall surface, the orthogonal test method is used to design the simulation working conditions, and the influencing factors and significance of the heat and moisture transfer of the surrounding rock wall surface are analyzed.

8. The method according to claim 7, wherein the method is characterized by, The orthogonal test method is used to design the simulation working conditions, the annual average heat and moisture absorption and release of the surrounding rock wall surface and the heat and moisture absorption and release time are taken as the indexes of the orthogonal test, the importance and significance of each factor are analyzed by comparing the range sizes corresponding to different air influencing factor parameters, the larger the range is, the more significant the influence is, and the more important the factor is.

9. The method according to claim 8, wherein the method is characterized by, The air influencing factors are selected as the annual temperature amplitude, the annual average temperature, the annual humidity amplitude and the annual average humidity.

10. The method according to claim 9, wherein the method is characterized by, According to the functional approximation relationship between the four factors of the annual temperature amplitude, the annual average temperature, the annual humidity amplitude and the annual average humidity and the annual average heat and moisture absorption and release of the surrounding rock wall surface and the heat and moisture absorption and release time, the form of the fitting formula is determined; According to the significance analysis, the significant and very significant factors are selected as independent variables, and the prediction formula of the annual average heat and moisture absorption and release and the heat and moisture absorption and release time of the surrounding rock wall surface is fitted.

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