CN110610020B - Snowquilt-soil-unconsolidated rock stratum continuous body hydrothermal coupling calculation method - Google Patents
Snowquilt-soil-unconsolidated rock stratum continuous body hydrothermal coupling calculation method Download PDFInfo
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Abstract
The invention provides a hydrothermal coupling calculation method for a snowquilt-soil-unconsolidated rock stratum continuum, which relates to the technical field of hydrological models. The method considers the influence of the snow cover and the loose rock stratum on the model hydrothermal calculation, can be applied to the sub-watersheds with larger snow cover thickness and thinner soil layers, improves the application range of the model, not only enables the physical structure of the model to be closer to the reality, but also improves the calculation accuracy of the model.
Description
Technical Field
The invention relates to the technical field of hydrological models, in particular to a snowquilt-soil-unconsolidated rock stratum continuous body hydrothermal coupling calculation method.
Background
The water circulation in the cold area is mainly influenced by glaciers, snow and frozen soil, the response of the cold area to climate change and human activities in the glaciers, the snow and the frozen soil is different from that in the non-cold area, and the special melting rule of the glaciers and the snow and the soil water redistribution caused by the freezing and thawing process of the soil influence the water circulation processes of infiltration, evaporation, precipitation, runoff, interflow and the like in the cold area to different degrees. Understanding the water circulation process in the cold area has important significance for researching the evolution law of frozen soil and water resources.
From the distribution and formation conditions of perennial frozen soils, the global cold region can be divided into two major categories: firstly, high latitude cold regions at high and medium latitudes; the other is the high altitude cold region at the middle and low latitudes. The Chinese cold region is mainly characterized in that the region is above the North Return line and covers permafrost and seasonal frozen soil, and the coverage area of the permafrost is large. World third; meanwhile, the cold region is mostly a high-altitude cold region, and the permafrost area at high altitude reaches 1.73 multiplied by 106km2Located at the first position of the world.
In the early stage of research on frozen soil hydrology in cold regions, scholars carry out a large number of outdoor and indoor experiments to research a hydrothermal transfer mechanism in the soil freezing and thawing process, and due to the complexity of frozen soil moisture and heat movement, the method combining experimental observation and numerical simulation is gradually an important means for researching frozen soil hydrology in cold regions, and the method is difficult to solve or reflect practical problems by adopting a single experimental method.
In the past decades, a plurality of models simulating frozen soil moisture migration and heat conduction are developed, in the original hydrothermal coupling calculation process of each aquifer, the calculation layer vertical direction of the hydrothermal coupling is mostly considered to be a soil layer, and the influence of accumulated snow which is seasonally changed above the soil and loose rock layers of mixed soil below the soil is ignored. For some non-glacier areas in plateau cold areas, the ground surface is covered with a snowy layer with huge seasonal changes, and part of the areas are affected by the terrain, the surface soil is very thin and thin, and a water-containing loose rock stratum with large thickness exists below the soil layer. Therefore, the influence of accumulated snow and loose rock strata on the water-heat condition of the flow field is considered, the accuracy of the model is very important to be improved, and meanwhile the applicability of the model can be improved.
Disclosure of Invention
The invention aims to provide a snowquilt-soil-unconsolidated rock stratum continuous body hydrothermal coupling calculation method, so as to solve the problems in the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a snowquilt-soil-unconsolidated rock stratum continuous body hydrothermal coupling calculation method comprises the following steps:
s1, judging whether the thickness of the accumulated snow forms a snow layer;
s2, setting hydrothermal parameters of the accumulated snow, the soil and the unconsolidated rock stratum according to the actual measurement results of the accumulated snow, the soil and the unconsolidated rock stratum in the research area;
s3, establishing a model structure: when a snowflake layer exists, the layer 1 calculated by the model is the snowflake, the layer 2-m +1 is divided into a soil layer, and the layer m + 2-m +1+ n is divided into a loose rock layer; otherwise, dividing the 1 st to m th layers calculated by the model into soil layers, and dividing the m +2 th to m + n th layers into loose rock layers;
and S4, calculating the water heat flux between each calculation layer by adopting an iterative calculation method.
Preferably, step S1 specifically includes:
s11, setting a snow cover layer threshold according to the environment to be measured;
s12, judging whether the thickness of the snow is higher than a set threshold value, and if so, forming a snow layer by the snow layer; if the value is lower than the threshold value, the snow layer is not formed by the snow layer.
Preferably, the hydrothermal parameters in step S2 include: saturated water conductivity coefficient, saturated water content, field water holding rate, moisture absorption coefficient, maximum molecular water holding rate, capillary wetting peak suction pressure, snowfall density, volumetric heat capacity, heat conductivity coefficient and heat capacity.
Preferably, the formula for calculating the snowfall density is as follows:
ρnewthe density of the snow is (kg/m)3)，TaAir temperature (. degree. C.);
the calculation formula of the heat conductivity coefficient is as follows:
Dnis the thermal conductivity (W/(m ℃)) of accumulated snow, rhonIs the density (kg/m) of accumulated snow3)；
The volume heat capacity calculation formula is as follows:
Cn＝2.09*103*pn
ρnis the density (kg/m) of accumulated snow3)，CnIs the volumetric heat capacity J/(m) of accumulated snow3·℃)。
Preferably, the heat capacity of the soil and the unconsolidated formation is calculated according to the formula:
Cv＝(1-θs)×Cs+θl×Cl+θi×Ci
the calculation formula of the thermal conductivity coefficient of the soil and the unconsolidated rock stratum is as follows:
λst＝0.300×ωsand+0.265×ωsilt+0.250×ωclay
θsthe saturated volume water content of the soil (loose rock stratum); thetalThe water content is the volume water content of liquid water; cs、Cl、CiVolumetric heat capacities of soil (unconsolidated rock formation) solid phase, water and ice respectively; lambda [ alpha ]stIs dry soil (unconsolidated rock formation)) Thermal conductivity (W/(m. degree. C)) of (C) (. omega.))sandComponent content of sand grains in soil, omegaclayIs the component content of the particles in the soil, omegasiltIs the content of clay particles in the soil.
Preferably, the 2 nd and 3 rd layers of the continuum in step S3 are each set to 10 cm; each layer of the 4 th to m + n th layers is set to be 20cm, and the thickness of the m + n th layer of the loose rock layer is subtracted from the total thickness of the soil and the loose rock layer.
Preferably, step S4 specifically includes:
s41, calculating the heat flux of the atmosphere and the snow layer;
s42, calculating heat flux between the soil layer and the snow cover layer;
s43, calculating heat flux between soil and loose rock stratum and between loose rock stratums;
and S44, adding the snow cover and the unconsolidated rock stratum into the iterative calculation to obtain the temperature and the heat flux of each layer.
Preferably, the heat flux of the atmosphere and the snow layer is calculated by a forced-recovery method in step S41;
the calculation formula of the heat flux of the accumulated snow and the soil layer in the step S42 is as follows:
c is the heat flux (W/m) between the soil and the accumulated snow2)，ZSThickness (m) of accumulated snow, ZCIs the first layer soil thickness (m), lambdaSIs the thermal conductivity (W/(m.k)) of the snow-deposited layerCThe thermal conductivity (W/(m.k)) of the soil layer, RCThermal contact resistance of soil layer and snow layer ((m)2·k)/W)，TCThe temperature (DEG C) of the first layer of soil layer, TSTemperature of the snow layer (. degree. C.);
in step S43, the calculation formula of the heat flux between the soil and the loose rock stratum and between the loose rock stratums is:
in the formula Hi,i+1And representing the heat flux between adjacent calculation layers, wherein the initial temperature of each layer of soil is input data of the model, and the soil temperature and the water content are solved by numerical iteration.
Preferably, the model adopts explicit difference to carry out numerical iterative computation, and nested iteration is adopted in consideration of the limitation of the computation time of the multilayer snowquilt-soil-unconsolidated rock formation continuum.
Preferably, the calculation flow of the hydrothermal flux of the soil layer or the unconsolidated rock layer is as follows:
1) calculating temperature and moisture phase changes of the heat conduction, the snow cover, the soil and the loose rock stratum according to initial conditions, and then carrying out iterative calculation to converge by taking the snow cover, the soil and the loose rock stratum as judgment conditions;
2) calculating the water transport amount of each layer according to water balance after the heat calculation is closed and converged, and correcting the water content of the soil and the loose rock stratum;
3) judging whether convergence is achieved by using the liquid water content, if not, returning to the step 1) to carry out heat calculation until the heat and water quantity iterative calculation is closed and converged, finishing the multilayer hydrothermal coupling calculation, and finally completing the numerical solution of the temperature and the water content of the snow layer, the soil layer and the loose rock layer.
The invention has the beneficial effects that:
the invention discloses a snowquilt-soil-unconsolidated formation continuum hydrothermal coupling calculation method which is characterized in that on the basis of an original soil layer, the influence of snow on hydrothermal calculation of an aquifer is considered at the top of the soil layer, a unconsolidated formation which does not belong to soil but can store underground water is added at the lower layer of the soil layer, and a heat flux calculation model of the snowquilt-soil-unconsolidated formation continuum is formed. Compared with the prior art, the model can be applied to sub-basins with larger thickness of the snow cover and thinner soil layers, and the application range of the model is widened.
Drawings
FIG. 1 is a flow chart of the steps of a snowquilt-soil-unconsolidated formation continuum hydrothermal coupling calculation simulation method;
FIG. 2 is a computed structural hierarchy of a snowmobile-soil-unconsolidated formation continuum hydro-thermal coupling model;
FIG. 3 is a schematic flow chart of a calculation of the water heat flux for a soil layer and a unconsolidated formation.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
Example 1
A snowquilt-soil-unconsolidated rock stratum continuous body hydrothermal coupling calculation method comprises the following steps:
s1, judging whether the thickness of the accumulated snow forms a snow layer;
s11, setting a snow cover layer threshold according to the environment to be measured;
s12, judging whether the thickness of the snow is higher than a set threshold value, and if so, forming a snow layer by the snow layer; if the value is lower than the threshold value, the snow layer is not formed by the snow layer.
S2, setting hydrothermal parameters of the accumulated snow, the soil and the unconsolidated rock stratum according to the actual measurement results of the accumulated snow, the soil and the unconsolidated rock stratum in the research area, and the method comprises the following steps: saturated water conductivity coefficient, saturated water content, field water holding rate, moisture absorption coefficient, maximum molecular water holding rate, capillary wetting peak suction pressure, snowfall density, volumetric heat capacity, heat conductivity coefficient and heat capacity.
The calculation formula of the snowfall density is as follows:
ρnewthe density of the new snowfall (kg/m)3)，TaAir temperature (. degree. C.);
the calculation formula of the heat conductivity coefficient is as follows:
Dnis the thermal conductivity (W/(m ℃)) of accumulated snow, rhonIs the density (kg/m) of accumulated snow3)；
The volume heat capacity calculation formula is as follows:
Cn＝2.09*103*pn
ρnis the density (kg/m) of accumulated snow3)，CnIs the volumetric heat capacity J/(m) of accumulated snow3·℃)。
The calculation formula of the heat capacity of the soil and the unconsolidated rock stratum is as follows:
Cv＝(1-θs)×Cs+θl×Cl+θi×Ci
the calculation formula of the thermal conductivity coefficient of the soil and the unconsolidated rock stratum is as follows:
λst＝0.300×ωsand+0.265×ωsilt+0.250×ωclay
θsthe saturated volume water content of the soil (loose rock stratum); thetalThe water content is the volume water content of liquid water; cs、Cl、CiVolumetric heat capacities of soil (unconsolidated rock formation) solid phase, water and ice respectively; lambda [ alpha ]stThermal conductivity (W/(m.degree.C)) of dry soil (unconsolidated rock formation); omegasandComponent content of sand grains in soil, omegaclayIs the component content of the particles in the soil, omegasiltIs the content of clay particles in the soil.
S3, establishing a model structure: when a snowflake layer exists, the layer 1 calculated by the model is the snowflake, the layer 2-m + 1 is divided into a soil layer, and the layer m + 2-m + 1+ n is divided into a loose rock layer; otherwise, dividing the 1 st to m th layers calculated by the model into soil layers, and dividing the m +2 th to m + n th layers into loose rock layers;
each layer of the 2 nd layer and the 3 rd layer of the continuum is set to be 10 cm; each layer of the 4 th to m + n th layers is set to be 20cm, and the thickness of the m + n th layer of the loose rock layer is subtracted from the total thickness of the soil and the loose rock layer.
And S4, calculating the water heat flux between each calculation layer by adopting an iterative calculation method.
S41, calculating the heat flux of the atmosphere and the snow layer by adopting a forced-recovery method;
s42, calculating the heat flux between the soil and the snow cover layer by adopting the following formula;
c is the heat flux (W/m) between the soil and the accumulated snow2)，ZSThickness (m) of accumulated snow, ZCIs the first layer soil thickness (m), lambdaSIs the thermal conductivity (W/(m.k)) of the snow-deposited layerCThe thermal conductivity (W/(m.k)) of the soil layer, RCThermal contact resistance of soil layer and snow layer ((m)2·k)/W)，TCThe temperature (DEG C) of the first layer of soil layer, TSTemperature of the snow layer (. degree. C.);
s43, calculating the heat flux between the soil and the loose rock stratum and between the soil and the loose rock stratum, wherein the calculation formula is as follows;
in the formula Hi,i+1And representing the heat flux between adjacent calculation layers, wherein the initial temperature of each layer of soil is input data of the coupling model, and the soil temperature and the water content are solved by numerical iteration.
And S44, adding the snow cover and the unconsolidated rock stratum into the iterative calculation to obtain the temperature and the water heat flux of each layer.
In this embodiment, the snowquilt-soil-unconsolidated formation continuum model performs numerical iterative computation by using explicit differences, considering the limitation of the computation duration of the multilayer snowquilt-soil-unconsolidated formation continuum, and using nested iteration, the computation flow of the hydrothermal flux of the soil layer or unconsolidated formation is shown in fig. 3, and the specific steps are as follows:
1) calculating temperature and moisture phase changes of the heat conduction, the snow cover, the soil and the loose rock stratum according to initial conditions, and then carrying out iterative calculation to converge by taking the snow cover, the soil and the loose rock stratum as judgment conditions;
2) calculating the water transport amount of each layer according to water balance after the heat calculation is closed and converged, and correcting the water content of the soil and the loose rock stratum;
3) judging whether convergence is achieved by using the liquid water content, if not, returning to the step 1) to carry out heat calculation until the heat and water quantity iterative calculation is closed and converged, finishing the multilayer hydrothermal coupling calculation, and finally completing the numerical solution of the temperature and the water content of the snow layer, the soil and the loose rock layer.
Example 2
The Neyan river basin belongs to a first-level branch of the Yaluzangbujiang, originates from a Lau lake in the autonomous region of Tibet, flows from the source, flows from the west to the east, turns to the northeast direction through Song to Jiaxing, winds a larger arc through Jinda and Taizhao, returns to the east direction in the Golugbujiang, flows through the neighborhood of eight towns, sharply turns to the south flow, and merges into the Yaluzangbujiang in the neighborhood of Luding. The moderate latitude zone of the river basin of the Neyan river belongs to a semi-humid and semi-arid area. The ocean river has a dry flow length of 309km, a river source altitude of about 5000m and a river mouth altitude of about 2920 m. The fall is 2080m, and the average slope drop of the drainage basin is 0.73%.
S1, judging whether the thickness of the accumulated snow can form a snow layer;
according to the actual investigation condition of the Neiyaku river basin, the temperature difference of the Neiyaku river basin in winter and summer is large, a snowy layer with seasonal changes generally exists in a non-glacier area, and the influence of snow on the thickness of frozen soil is very obvious. Therefore, in an area with a large snow thickness, it is necessary to consider the influence of the varying snow layer on the water heat of the frozen soil according to actual conditions. In the model, the snow thickness is used as the average snow thickness of the calculation unit, a threshold value is set according to the actual situation, and the influence of the snow layer is considered when the average snow thickness is larger than the threshold value.
S2, setting hydrothermal parameters of the accumulated snow, the soil and the unconsolidated rock stratum according to the actual measurement results of the accumulated snow, the soil and the unconsolidated rock stratum in the research area;
the soil and unconsolidated formation moisture characteristic parameters determined according to the specific conditions of the Neyan river basin are shown in the following table 1:
TABLE 1 soil and unconsolidated formation moisture characterization parameters
| Parameter(s) | Sand soil | Loam soil | Clay loam | Clay clay | Unconsolidated rock formation |
| Coefficient of saturated water conductivity | 2.50E-03 | 7.00E-04 | 2.00E-04 | 3.00E-05 | 0.5 |
| Saturated water content | 0.4 | 0.466 | 0.475 | 0.479 | 0.29 |
| Water retention rate in field | 0.174 | 0.278 | 0.365 | 0.387 | 0.134 |
| Coefficient of moisture absorption | 0.077 | 0.12 | 0.17 | 0.25 | 0.064 |
| Maximum molecular water holding capacity | 0.035 | 0.062 | 0.136 | 0.09 | 0.027 |
| Capillary wet peak suction pressure | 61 | 89 | 125 | 175 | 48 |
| Coefficient of thermal conductivity (in dry state) | 0.282 | 0.265 | 0.26 | 0.25 | 1.3 |
| Thermal capacity (solid phase) | 2.10E+06 | 2.10E+06 | 2.10E+06 | 2.10E+06 | 1.2E+06 |
Snowfall density:
coefficient of thermal conductivity:
volumetric heat capacity: cn＝2.09*103*pn
In the formula, ρnewThe density of the snow is (kg/m)3)，TaAir temperature (DEG C), DnIs the thermal conductivity (W/(m ℃)) of accumulated snow, rhonIs the density (kg/m) of accumulated snow3)，CnIs the volumetric heat capacity J/(m) of accumulated snow3·℃)。
Thermal capacity of soil and unconsolidated formations:
Cv＝(1-θs)×Cs+θl×Cl+θi×Ci
thermal conductivity of soil and unconsolidated formations:
λst＝0.300×ωsand+0.265×ωsilt+0.250×ωclay
in the formula: thetasThe saturated volume water content of the soil or the loose rock stratum; thetalIs prepared from liquidThe volume water content of the state water; cs、Cl、CiVolumetric heat capacity of soil or unconsolidated formation solid phase, water, ice, respectively: lambda [ alpha ]stThermal conductivity (W/(m. DEG C)) of dry soil or unconsolidated rock formation; omegasandComponent content of sand grains in soil, omegaclayIs the component content of the particles in the soil, omegasiltIs the content of clay particles in the soil.
The heat flux calculation mode of the accumulated snow and the soil layer is as follows:
wherein C is the heat flux (W/m) between the soil and the accumulated snow2)，ZSThickness (m) of accumulated snow, ZCIs the first layer soil thickness (m), lambdaSIs the thermal conductivity (W/(m.k)) of the ice and snow layerCThe thermal conductivity (W/(m.k)) of the soil layer, RCThermal contact resistance of soil layer and snow layer ((m)2·k)/W)，TCThe temperature (DEG C) of the first layer of soil layer, TSThe temperature (. degree. C.) of the snow layer.
S3, model structure: when a snowflake layer exists, the layer 1 calculated by the model is the snowflake, the layer 2-m + 1 is divided into a soil layer, and the layer m + 2-m + 1+ n is divided into a loose rock layer; otherwise, dividing the 1 st to m th layers calculated by the model into soil layers, and dividing the m +2 th to m + n th layers into loose rock layers;
the distributed hydrological model WEP-L soil-containing moisture migration calculation module can simulate water circulation processes such as evaporation and transpiration, infiltration, runoff in soil, underground water movement, production and confluence, snow melting by snow, artificial collateral water circulation and the like, can also simulate energy exchange between the ground surface and the atmosphere, but is lack of simulation of heat conduction between soil layers at different depths, and cannot reflect heat change inside a soil system.
Meanwhile, the original WEP-L model only considers the result of an actual soil layer, the simulation result only represents the average temperature or the water content of the soil layer, the heat transfer and temperature distribution conditions of the frozen soil layer in the loose rock layer mixed by soil and rocks are not considered, and the temperature gradient distribution and heat transfer conditions of the whole movable frozen soil layer cannot be well simulated.
For the application of a soil-unconsolidated rock stratum continuum hydrothermal coupling calculation simulation structure in a model, the research maintains the foundation of the original WEP-L model movable soil layer when a frozen soil-water module is constructed, and a snow cover-soil-unconsolidated rock stratum continuum is constructed under the soil layer according to the actual condition by considering the snow cover unconsolidated rock stratum. The snow accumulation layer with variable thickness is added on the surface of the soil layer of the model, and the surface soil is considered to be sensitive to atmospheric change, each layer of the 2 nd layer and the 3 rd layer of the continuum is determined to be 10cm, each layer of the 4 th-m + n th layer is determined to be 20cm, the loose rock layer of the m +1+ n th layer is the thickness of the soil and the loose rock layer minus the thickness of the m + n layer before the thickness of the soil and the loose rock layer, but the setting of the soil layer is only in an initial state, and the number of the soil layers can be modified according to the thickness of the soil layer actually measured or consulted.
And S4, calculating the water heat flux between each calculation layer by adopting an iterative calculation method.
In the step, the heat flux of the atmosphere and the snow layer is calculated according to a forced-recovery method, and a formula is adopted
Calculating the heat flux between the soil and the snow cover by adopting a formula
the model adopts explicit difference to carry out numerical iterative computation, and nested iteration is adopted in consideration of the limitation of the computation time of the multilayer snow cover-soil-unconsolidated rock stratum continuum. The specific calculation structure diagram is shown in fig. 2, and fig. 3 is a schematic flow chart of the calculation of the water heat flux of the soil layer (unconsolidated formation). The time step length of the model simulation is 1d, and the space step length of the iterative computation is different soil layers in the computing unit. Calculating the temperature and moisture phase change of the heat conduction, the snow cover, the soil and the loose rock stratum according to initial conditions by the model in each time step, then carrying out iterative calculation to convergence by taking the snow cover, the soil and the loose rock stratum as judgment conditions (step 1), calculating the water migration quantity of each layer according to water balance after heat calculation and closed convergence, correcting the water content of the soil and the loose rock stratum (step 2), judging whether the convergence is carried out or not by using the liquid water content, returning to the step 1 to carry out heat calculation if the convergence is not carried out, ending the multilayer hydrothermal coupling calculation until the closed convergence is carried out after the heat and water iterative calculation, and completing the numerical solution of the temperature and the water content of the snow cover, the soil and the loose rock stratum.
By adopting the technical scheme disclosed by the invention, the following beneficial effects are obtained:
the invention discloses a snowquilt-soil-unconsolidated rock stratum continuous body hydrothermal coupling calculation method, which considers the influence of snowquilt and unconsolidated rock stratum on model hydrothermal calculation, not only makes the physical structure of the model closer to the reality, but also improves the calculation precision of the model. Compared with the prior art, the model can be applied to sub-basins with larger thickness of the snow cover and thinner soil layers, and the application range of the model is widened.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements should also be considered within the scope of the present invention.
Claims (6)
1. A snowquilt-soil-unconsolidated rock stratum continuum hydrothermal coupling calculation method is characterized by comprising the following steps:
s1, judging whether the thickness of the accumulated snow forms a snow layer;
s2, setting hydrothermal parameters of the accumulated snow, the soil and the unconsolidated rock stratum according to the actual measurement results of the accumulated snow, the soil and the unconsolidated rock stratum in the research area;
s3, establishing a model structure: when a snowflake layer exists, the layer 1 calculated by the model is the snowflake, the layer 2-m +1 is divided into a soil layer, and the layer m + 2-m +1+ n is divided into a loose rock layer; otherwise, dividing the 1 st to m th layers calculated by the model into soil layers, and dividing the m +2 th to m + n th layers into loose rock layers;
s4, calculating the water heat flux among the calculation layers by adopting an iterative calculation method;
step S4 specifically includes:
s41, calculating the heat flux of the atmosphere and the snow layer;
s42, calculating heat flux between the soil layer and the snow cover layer;
s43, calculating heat flux between soil and loose rock stratum and between loose rock stratums;
s44, adding the snow cover and the loose rock stratum into iterative calculation to obtain the temperature and the heat flux of each layer;
in step S41, calculating the heat flux of the atmosphere and the snow layer by using a forced-recovery method;
the calculation formula of the heat flux of the accumulated snow and the soil layer in the step S42 is as follows:
c is the sensible heat flux between the soil and the snow, ZSThickness of accumulated snow, ZCIs the first layer of soil thickness, lambdaSIs the thermal conductivity of the ice-snow layer, lambdaCIs the thermal conductivity of the soil layer, RCThermal contact resistance of soil layer and snow layer, TCIs the first layer soil layer temperature, TSIs the temperature of the snow layer;
in the step S43, the heat flux formula between the soil and the loose rock stratum and the heat flux calculation formula between the loose rock stratums are both:
in the formula Hi,i+1、Hj,j+1Hj-1,jRespectively representing the heat flux, λ, between adjacent calculated layerss，i、λs，i+1Thermal conductivity coefficients of the ith layer and the (i + 1) th layer of the continuum are respectively; t iss，i、Ts，i+1、Ts，jThe temperature of the ith layer, the (i + 1) th layer and the jth layer of the continuum respectively; z is a radical ofi、zi+1、zjThe thickness of the ith layer, the (i + 1) th layer and the jth layer of the continuum are respectively; cs，iThe mass heat capacity of the j-th layer of the continuum; p is developeds，iThe density of the j-th layer of the continuum; the initial temperature of each layer of soil is input data of the model, and the soil temperature and the water content are solved by numerical iteration;
the model adopts explicit difference to carry out numerical iterative computation, and nested iteration is adopted in consideration of the limitation of the computation time of the multilayer snow cover-soil-unconsolidated rock stratum continuum;
the flow of calculating the hydrothermal flux of the snowquilt-soil-unconsolidated rock stratum continuous body is as follows:
1) calculating temperature and moisture phase changes of the heat conduction, the snow cover, the soil and the loose rock stratum according to initial conditions, and then carrying out iterative calculation to converge by taking the snow cover, the soil and the loose rock stratum as judgment conditions;
2) calculating the water transport amount of each layer according to water balance after the heat calculation is closed and converged, and correcting the water content of the soil and the loose rock stratum;
3) judging whether convergence is achieved by using the liquid water content, if not, returning to the step 1) to carry out heat calculation until the heat and water quantity iterative calculation is closed and converged, finishing the multilayer hydrothermal coupling calculation, and finally completing the numerical solution of the temperature and the water content of the snow layer, the soil and the loose rock layer.
2. The snowquilt-soil-unconsolidated formation continuous body hydrothermal coupling calculation method according to claim 1, wherein the step S1 specifically includes:
s11, setting a snow cover layer threshold according to the environment to be measured;
s12, judging whether the thickness of the snow is higher than a set threshold value, and if so, forming a snow layer by the snow layer; if the value is lower than the threshold value, the snow layer is not formed by the snow layer.
3. The snowmobile-soil-unconsolidated formation continuum hydrothermal coupling calculation method of claim 1, wherein the hydrothermal parameters in step S2 include: saturated water conductivity coefficient, saturated water content, field water holding rate, moisture absorption coefficient, maximum molecular water holding rate, capillary wetting peak suction pressure, snowfall density, volumetric heat capacity, heat conductivity coefficient and heat capacity.
4. The snowquilt-soil-unconsolidated formation continuous body hydrothermal coupling calculation method according to claim 3, wherein the calculation formula of the snowfall density is as follows:
ρnewto density of new snow, TaIs the air temperature;
the calculation formula of the heat conductivity coefficient is as follows:
Dnis the thermal conductivity of accumulated snow, rhonIs the density of accumulated snow;
the volume heat capacity calculation formula is as follows:
Cn＝2.09*103*pn
ρndensity of accumulated snow, CnIs the volumetric heat capacity of snow.
5. The duvet-soil-unconsolidated formation continuum hydrothermal coupling calculation method of claim 3,
the calculation formula of the heat capacity of the soil and the unconsolidated rock stratum is as follows:
Cv＝(1-θs)×Cs+θ1×C1+θi×Ci
the calculation formula of the thermal conductivity coefficient of the soil and the unconsolidated rock stratum is as follows:
λst＝wrock*λ0+ωsand*0.300+ωsilt*0.265+ωclat*0.250
θsthe saturated volume water content of the soil or the loose rock stratum; thetalThe water content is the volume water content of liquid water; thetaiIs the volumetric ice content of the soil or unconsolidated rock formation; cs、Cl、CiVolumetric heat capacities of soil or loose rock stratum solid phase, water and ice respectively; w is arock、wsand、wsilt、wclayThe contents of rock, sand, powder and clay in soil or loose rock stratum; λ is the thermal conductivity of the soil or unconsolidated rock formation; lambda [ alpha ]stThe thermal conductivity of dry soil or unconsolidated formations.
6. The snowmobile-soil-unconsolidated formation continuum hydrothermal coupling calculation method according to claim 1, wherein each of the 2 nd and 3 rd layers of the continuum in step S3 is set to be 10 cm; each layer of the 4 th to m + n th layers is set to be 20cm, and the thickness of the m + n th layer of the loose rock layer is subtracted from the total thickness of the soil and the loose rock layer.
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