CN119164836B - A method for predicting capillary water flux by capillary water rise height - Google Patents

A method for predicting capillary water flux by capillary water rise height

Info

Publication number
CN119164836B
CN119164836B CN202411338548.7A CN202411338548A CN119164836B CN 119164836 B CN119164836 B CN 119164836B CN 202411338548 A CN202411338548 A CN 202411338548A CN 119164836 B CN119164836 B CN 119164836B
Authority
CN
China
Prior art keywords
capillary water
soil
flux
model
water
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202411338548.7A
Other languages
Chinese (zh)
Other versions
CN119164836A (en
Inventor
张冠儒
陈可欣
唐浩
陈传亚
黄艺
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Chengdu Univeristy of Technology
Original Assignee
Chengdu Univeristy of Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Chengdu Univeristy of Technology filed Critical Chengdu Univeristy of Technology
Priority to CN202411338548.7A priority Critical patent/CN119164836B/en
Publication of CN119164836A publication Critical patent/CN119164836A/en
Application granted granted Critical
Publication of CN119164836B publication Critical patent/CN119164836B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N13/00—Investigating surface or boundary effects, e.g. wetting power; Investigating diffusion effects; Analysing materials by determining surface, boundary, or diffusion effects
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
    • G01N15/082—Investigating permeability by forcing a fluid through a sample
    • G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/24—Earth materials

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Immunology (AREA)
  • General Physics & Mathematics (AREA)
  • Pathology (AREA)
  • General Health & Medical Sciences (AREA)
  • Biochemistry (AREA)
  • Analytical Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Medicinal Chemistry (AREA)
  • Food Science & Technology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Remote Sensing (AREA)
  • Geology (AREA)
  • Fluid Mechanics (AREA)
  • Dispersion Chemistry (AREA)
  • Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)

Abstract

The invention belongs to the field of capillary water rising flux test, and discloses a novel method for predicting capillary water rising flux based on capillary water rising height, and estimating capillary water rising flux by acquiring a soil air outlet value h a, a soil saturation permeability coefficient K s, a correction coefficient lambda of the model capillary water rising height and a fitting parameter beta', and combining the deduced mechanism model. The invention divides the capillary water rising into two stages, derives and establishes a new mechanism model of the capillary water rising flux along with the height change based on Darcy's law under the unsaturated condition, the model covers the whole rising process of the water level, compared with an empirical model, the model has wider application range, and the model fitting value has better matching degree with an observed value.

Description

Method for predicting capillary water flux through capillary water elevation
Technical Field
The invention belongs to the field of capillary water rising flux test, and particularly relates to a method for predicting capillary water rising flux based on capillary water rising height.
Background
Soil capillary water refers to liquid water held and moved by capillary force in the pores of the soil capillary, and is one of main sources of water required by plant growth.
Two predictive models are commonly employed in existing methods of predicting capillary water flux. One is a mechanism model, which focuses on the capillary water part rise interval, and predicts poor accuracy when the range is exceeded. The other is an empirical model, which is suitable for specific conditions, and when the actual situation deviates from the condition according to the model, the prediction of the model will have errors.
Disclosure of Invention
Based on the problems existing in the prior art, the invention divides the capillary water rising process into two stages by taking the soil air outlet value as a threshold value, and derives a new mechanism model of capillary water rising flux along with the change of height according to Darcy's law under the unsaturated condition, which is used for predicting capillary water rising flux under different rising heights of capillary water.
The invention is realized in that a method for predicting capillary water flux by capillary water elevation comprises the steps of:
Step one, obtaining a soil air outlet value h a.
And step two, obtaining a soil saturation permeability coefficient K s.
And thirdly, obtaining a correction coefficient lambda and a fitting parameter beta' of the capillary water rising height of the model.
And step four, predicting capillary water rising flux according to the parameters and the deduced mechanism model.
In the first step, soil to be measured is taken for a soil moisture absorption experiment. And before the experiment starts, drying the soil sample to be tested until the water content of the soil is reduced to 0. Then slowly adding a certain volume of water into the soil, measuring the volume water content and the matrix suction force in the soil after the water is fully diffused, and then repeating the processes of adding water and measuring the volume water content and the matrix suction force until the volume water content reaches saturation, reducing the matrix suction force to 0Kpa, and finishing the soil moisture absorption experiment. And (3) converting the suction force of the soil matrix measured by the experiment into the height of a centimeter water column, drawing a moisture absorption curve of a soil moisture characteristic curve by taking the matrix potential as an x axis and the volume moisture content as a y axis.
The Gardner model (Gardner, 1958) was used as a fitted model for the earth-water characteristic curve:
Wherein θ and θ S are average volume water content and saturated volume water content respectively, h is matrix suction force, cm, θ r is residual water content, and c and m are model shape parameters.
And drawing a tangent line at the saturation volume water content and a tangent line of an inflection point by using the soil moisture characteristic curve fitted by the model, and prolonging the two tangent lines, wherein the abscissa of the intersection point of the two tangent lines is expressed as the soil air outlet value height h a, and the unit is cm.
In the second step, the soil is filled into the columnar container, and the soil density in the soil column is reduced to the original soil density by knocking the column wall. The column was immersed in water. And taking out the water after the water saturation time is reached, fixing the soil column by using an iron frame table, placing a beaker below the soil column, adding water above the soil column by using a Marshall bottle, keeping a certain thickness of a water layer, and keeping a constant water level.
Starting timing when the first drop of water appears below the soil column, measuring the water seepage amount at intervals, and recording the water temperature. The cumulative water seepage V measured each time is set as a y axis, the time t spent by the cumulative water seepage is set as an x axis, and a change curve of the soil cumulative water seepage along with time is obtained. The change curve of the soil infiltration amount along with the time gradually shows a linear correlation, which means that the soil infiltration amount is the same in a certain time, and a stable state is achieved.
The permeability coefficient is calculated according to the darcy formula:
Wherein the method comprises the steps of
Wherein V is the water quantity penetrating through the soil column sectional area A (cm 2) within the time t (h), cm 3, I is the hydraulic gradient, K is the permeability coefficient, namely the permeability speed when the hydraulic gradient is 1, cm/h, L is the water penetration distance of two points designated in the soil column, cm, and Deltah is the total water head difference between the two points designated.
Further, in the third step, a new dry soil column is prepared, and a Marshall bottle is utilized to provide stable groundwater level and sufficient water source. When the experiment starts, water is supplied from a Marshall bottle to enable water to flow into the soil column, when the water level in the soil column rises to a stable underground water level, the rising height of capillary water at the moment is recorded to be 0cm, the rising time is 0h, and the rising water volume is 0cm 3. In the first stage of capillary water rising (the rising height of the capillary water is smaller than the soil air outlet value h a), the rising time and the graduation of the water tank are recorded once when the capillary water rises to a certain height until the capillary water rises to 1/3h a, and a plurality of discrete data points are acquired. The capillary water rising flux (q 0) is obtained by utilizing the rising water volume and the rising time estimation, and then the capillary water rising height (z T) is combined with a plurality of discrete values, the soil air outlet value h a and the soil saturation permeability coefficient K s, and the correction coefficient lambda of the capillary water rising height can be obtained by substituting the following formula:
In the formula (3), q 0 is capillary water rising flux, cm/h, K s is saturation permeability coefficient (cm/h), z T is capillary water rising height, cm, lambda is correction coefficient of capillary water rising height, and h a is soil air outlet value.
In the second stage of capillary water rising (the rising height of the capillary water is larger than the soil air outlet value h a), the rising time and the graduation of the water tank are recorded once when the capillary water rises to a certain height until the capillary water rises to 4/3h a, and a plurality of discrete data points are acquired. The capillary water rising flux is estimated by utilizing the rising water volume and the rising time, and then a plurality of discrete values of the capillary water rising height, the soil air outlet value h a and the soil saturation permeability coefficient K s are combined and substituted into the following formula to obtain the model fitting parameter beta':
In the formula (4), beta' is a model fitting parameter.
In the fourth step, the model parameters estimated in the first to third steps and formulas (3) and (4) are used to estimate the capillary water rising flux at other heights in the capillary water rising process.
In summary, the invention has the advantages and positive effects that:
The capillary water rising is divided into two stages, and a new mechanism model of the capillary water rising flux changing along with the height is deduced and established based on Darcy's law under the unsaturated condition. The model covers the whole rising process of the water level, has wider application range compared with an empirical model, and has better matching degree between a model fitting value and an observed value.
Drawings
FIG. 1 is a schematic flow chart of a method for predicting capillary water flux;
FIG. 2 is a graph showing a first stage of capillary water rise flux prediction (capillary water rise height less than h a);
FIG. 3 is a graph of a second stage of capillary water rise flux prediction (capillary water rise height greater than h a).
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present method will be described in further detail with reference to the following examples.
The method for predicting capillary water flux through the capillary water elevation provided by the embodiment of the invention comprises the following steps:
Step one, obtaining a soil air outlet value h a.
And step two, obtaining a soil permeability coefficient K s.
And thirdly, obtaining a correction coefficient lambda and a fitting parameter beta' of the capillary water rising height of the model.
And step four, predicting capillary water rising flux according to the parameters and the deduced mechanism model.
In the first step, 0.075mm quartz sand is taken for soil moisture absorption experiments. Before the experiment starts, the quartz sand sample is dried until the water content of the soil is reduced to 0. Then slowly adding a certain volume of water into the soil, measuring the volume water content and the matrix suction force in the soil after the water is fully diffused, and then repeating the processes of adding water and measuring the volume water content and the matrix suction force until the volume water content reaches saturation, reducing the matrix suction force to 0Kpa, and finishing the soil moisture absorption experiment. And (3) converting the suction force of the soil matrix measured by the experiment into the height of a centimeter water column, drawing a moisture absorption curve of a soil moisture characteristic curve by taking the matrix potential as an x axis and the volume moisture content as a y axis.
The Gardner model (Gardner, 1958) was used as a fitted model for the earth-water characteristic curve:
Wherein θ and θ S are average volume water content and saturated volume water content respectively, h is matrix suction force, cm, θ r is residual water content, and c and m are model shape parameters.
And drawing a tangent line at the saturation volume water content and a tangent line of an inflection point by using the soil moisture characteristic curve fitted by the model, and prolonging the tangent line, wherein the abscissa of the intersection point of the two tangent lines is expressed as the height of the soil air outlet value, h a is 69, and the unit is cm.
In the second step, quartz sand with the thickness of 0.075mm is filled into a columnar container, and the soil density in the soil column is reduced to the original soil density by knocking the columnar wall. The soil column is immersed in water, taken out after the water saturation time is reached, the soil column is fixed by an iron frame table, water is added above the soil column by a Marshall bottle, a beaker is placed below the soil column, the thickness of a water layer is kept to be 5cm, and meanwhile, the constant water level is kept. Starting timing when the first drop of water appears from the lower part of the soil column from the beginning of the water supply of the Marshall bottle, measuring the water seepage amount every 5 minutes, and simultaneously recording the water temperature. The cumulative water seepage V measured each time is set as a y axis, the time t spent by the cumulative water seepage is set as an x axis, and a change curve of the soil cumulative water seepage along with time is obtained.
The permeability coefficient was calculated according to the Darcy formula to give K s of 3.23cm/h.
Wherein the method comprises the steps of
Wherein V is the water quantity penetrating through the soil column sectional area A (cm 2) within the time t (h), cm 3, I is the hydraulic gradient, K is the permeability coefficient, namely the permeability speed when the hydraulic gradient is 1, cm/h, L is the water penetration distance of two points designated in the soil column, cm, and Deltah is the total water head difference between the two points designated.
In the third step, a new dry earth pillar is prepared, a Marshall bottle is used for providing stable groundwater level and sufficient water source, water is supplied to the earth pillar by the Marshall bottle when an experiment starts, when the water level in the earth pillar rises to the stable groundwater level, the rising height of capillary water at the moment is recorded to be 0cm, the rising time is 0h, and the rising water volume is 0cm 3. In the first stage of capillary water rising (capillary water rising height is smaller than soil air outlet value h a), rising time and graduation of the water tank are recorded at a distance of rising by 2cm until capillary water rises to 1/3h a, and a plurality of discrete data points are acquired. And estimating by utilizing the rising water volume and the rising time to obtain capillary water rising flux (q 0), combining a plurality of discrete values of the capillary water rising height (z T), the soil air outlet value h a and the soil saturation permeability coefficient K s, and substituting the discrete values into the following formula to obtain the correction coefficient lambda of the capillary water rising height which is 0.7475.
In the formula, q 0 is capillary water rising flux, cm/h, z T is capillary water rising height, cm, lambda is correction coefficient of capillary water rising height, and beta' is fitting parameter.
In the second stage of capillary water rising (the rising height of the capillary water is larger than the soil air outlet value h a), the rising time and the graduation of the water tank are recorded once every 2cm of capillary water rising until the capillary water rises to 4/3h a, and a plurality of discrete data points are acquired. And estimating by using the rising water volume and the rising time to obtain the capillary water rising flux, and substituting the capillary water rising flux, the soil air outlet value h a and the soil saturation permeability coefficient K s into the following formula to obtain the model fitting parameter beta' of 0.086.
In the fourth step, the model parameters and formulas (7) and (8) estimated in the first to third steps are used to estimate the capillary water rising flux of other heights in the capillary water rising process.
The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and to implement the same, but are not intended to limit the scope of the present invention, and all equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of the present invention.

Claims (3)

1.一种通过毛细水上升高度预测毛细水通量的方法，其特征在于按照下述步骤进行：1. A method for predicting capillary water flux by capillary water rise height, characterized by following the steps: 步骤1：通过土壤吸湿实验，获取土壤出气值ha；Step 1: Obtain the soil outgassing value h a through soil moisture absorption experiment; 步骤2：利用土柱实验，按照达西公式计算获取土壤饱和渗透系数Ks；Step 2: Using the soil column experiment, calculate the soil saturated permeability coefficient Ks according to Darcy's formula; 步骤3：在毛细水上升第一阶段，根据毛细水上升实验数据及公式(1)获取模型毛细水上升高度的修正系数λ；在毛细水上升第二阶段，根据毛细水上升实验数据及公式(2)获取模型拟合参数β'；Step 3: In the first stage of capillary water rise, the correction coefficient λ of the model capillary water rise height is obtained according to the capillary water rise experimental data and formula (1); in the second stage of capillary water rise, the model fitting parameter β' is obtained according to the capillary water rise experimental data and formula (2); 步骤4：将步骤1至3中估算的模型参数ha、Ks、λ、β'代入公式(1)、(2)预测毛细水上升通量；Step 4: Substitute the model parameters h a , K s , λ, and β' estimated in steps 1 to 3 into equations (1) and (2) to predict the capillary water rise flux; 式中，q0代表毛细水上升通量，单位cm/h；ha为土壤出气值；Ks为饱和渗透系数，单位cm/h；zT为毛细水上升高度，单位cm；λ为毛细水上升高度的修正系数；β'为模型拟合参数；Where q0 represents the capillary water rise flux, in cm/h; h a is the soil outgassing value; K s is the saturated permeability coefficient, in cm/h; z T is the capillary water rise height, in cm; λ is the correction coefficient for the capillary water rise height; β' is the model fitting parameter; 其中，步骤1中，取待测土壤进行土壤吸湿实验，利用Gardner模型拟合出的土壤水分特征曲线，绘制出饱和体积含水率处的切线以及拐点的切线并延长，两条切线的交叉点的横坐标表示为土壤出气值高度ha。In step 1, a soil moisture absorption experiment is performed on the soil to be tested. The soil moisture characteristic curve is fitted using the Gardner model. The tangent line at the saturated volumetric moisture content and the tangent line at the inflection point are drawn and extended. The abscissa of the intersection of the two tangent lines represents the soil outgassing value height h a . 2.根据权利要求1所述的一种通过毛细水上升高度预测毛细水通量的方法，其特征在于：步骤3中，利用马氏瓶进行实验，得到毛细水上升通量q0和毛细水上升高度zT的多个离散值，结合土壤出气值ha和土壤饱和渗透系数Ks，一起代入推导的多阶段毛细水通量机制模型，得到毛细水上升高度的修正系数λ以及拟合参数β'。2. The method for predicting capillary water flux by capillary water rise height according to claim 1, characterized in that: in step 3, a multiple discrete values of capillary water rise flux q 0 and capillary water rise height z T are obtained by experiment using a Malvern flask, and the values are combined with the soil outgassing value h a and the soil saturated permeability coefficient K s , and substituted into the derived multi-stage capillary water flux mechanism model to obtain the correction coefficient λ and fitting parameter β' of the capillary water rise height. 3.根据权利要求1所述的一种通过毛细水上升高度预测毛细水通量的方法，其特征在于：步骤4中，利用步骤1至3中估算的模型参数及推导出的多阶段毛细水通量机制模型估算毛细水上升过程中其他高度的毛细水上升通量。3. A method for predicting capillary water flux by capillary water rise height according to claim 1, characterized in that: in step 4, the model parameters estimated in steps 1 to 3 and the derived multi-stage capillary water flux mechanism model are used to estimate the capillary water rise flux at other heights during the capillary water rise process.
CN202411338548.7A 2024-09-25 2024-09-25 A method for predicting capillary water flux by capillary water rise height Active CN119164836B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202411338548.7A CN119164836B (en) 2024-09-25 2024-09-25 A method for predicting capillary water flux by capillary water rise height

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202411338548.7A CN119164836B (en) 2024-09-25 2024-09-25 A method for predicting capillary water flux by capillary water rise height

Publications (2)

Publication Number Publication Date
CN119164836A CN119164836A (en) 2024-12-20
CN119164836B true CN119164836B (en) 2025-09-05

Family

ID=93885343

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202411338548.7A Active CN119164836B (en) 2024-09-25 2024-09-25 A method for predicting capillary water flux by capillary water rise height

Country Status (1)

Country Link
CN (1) CN119164836B (en)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108458961A (en) * 2018-03-28 2018-08-28 江西理工大学 A kind of ion type rareearth leaching solution capillary rise pilot system and experimental method
CN115436235A (en) * 2022-09-07 2022-12-06 成都理工大学 Laboratory permeability coefficient determination method based on capillary water rise

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN204694602U (en) * 2015-06-17 2015-10-07 成都理工大学 A kind of measurement capillary soil water climbing height test unit

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108458961A (en) * 2018-03-28 2018-08-28 江西理工大学 A kind of ion type rareearth leaching solution capillary rise pilot system and experimental method
CN115436235A (en) * 2022-09-07 2022-12-06 成都理工大学 Laboratory permeability coefficient determination method based on capillary water rise

Also Published As

Publication number Publication date
CN119164836A (en) 2024-12-20

Similar Documents

Publication Publication Date Title
CN110927038B (en) Testing device and testing method for soil body soil-water characteristic curve and permeability coefficient test
CN111208042B (en) A device and method for inverting hydraulic parameters of unsaturated garbage soil
CN110261279B (en) A Simultaneous Measurement Method of Unsaturated Soil Permeability Coefficient and Soil-Water Characteristic Curve Based on Axis Translation
CN107066687B (en) A kind of soil rainfall infiltration measurement system and method considering air drag effect
JP3381991B2 (en) Water permeability measuring apparatus and water permeability measuring method using the same
WO2015096672A1 (en) Detection device
CN110516322B (en) A Prediction Method of Nonlinear Permeability Coefficient of Clay Saturation under Different Hydraulic Gradients
CN108487904B (en) Phase permeation curve correction method for eliminating end effect based on plate
CN110672494B (en) Method for rapidly measuring different porosities of porous concrete
CN111650082A (en) A kind of measuring device and measuring method of unsaturated soil soil-water characteristic curve
CN101221117A (en) A system and method for measuring soil infiltration performance
CN113959837A (en) An unsaturated soil consolidation and wetting deformation measurement test device capable of accurately measuring the absorption and drainage of a sample and its use method
CN118169362B (en) Method for acquiring suction distribution of roadbed matrix under dry-wet cycle-stress coupling effect
CN102735819B (en) Infiltrometer
CN110095584B (en) Reservoir oil-water saturation correction method
CN107607456A (en) The assay method of unsaturated soil hydraulic conductivity based on the control of non-linear throughput process
CN119164836B (en) A method for predicting capillary water flux by capillary water rise height
Mohammadzadeh-Habili et al. Development of the Green-Ampt infiltration rate model and relationship of the GA model parameters with soil hydraulic parameters
CN113945497B (en) Evaluation method of reservoir fluid mobility in oil and gas reservoirs
Jia et al. Modified method for the estimation of groundwater evapotranspiration under very shallow water table conditions based on diurnal water table fluctuations
Constantz Comparison of isothermal and isobaric water retention paths in nonswelling porous materials
Su et al. Water retention measurement for soils
Moret-Fernández et al. A novel double disc method to determine soil hydraulic properties from drainage experiments with tension gradients
CN117054315B (en) A frozen soil permeability coefficient measurement system
CN210803217U (en) Constant head permeameter

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant