CN109211756A - Deformation soil air-entry value prediction technique based on VG model - Google Patents
Deformation soil air-entry value prediction technique based on VG model Download PDFInfo
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- CN109211756A CN109211756A CN201811288358.3A CN201811288358A CN109211756A CN 109211756 A CN109211756 A CN 109211756A CN 201811288358 A CN201811288358 A CN 201811288358A CN 109211756 A CN109211756 A CN 109211756A
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- 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
- G01N15/088—Investigating volume, surface area, size or distribution of pores; Porosimetry
- G01N15/0893—Investigating volume, surface area, size or distribution of pores; Porosimetry by measuring weight or volume of sorbed fluid, e.g. B.E.T. method
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- 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
- G01N33/246—Earth materials for water content
Abstract
The present invention provides a kind of deformation soil air-entry value prediction technique based on VG model, it being capable of quickly and efficiently prediction of distortion soil air-entry value, the deformation soil air-entry value prediction technique is characterised by comprising following steps: step 1. measures the measurement matric suction ψ under deformation condition based on pressure plate test0With measurement quality moisture content w0Serial measured data；Step 2. will measure matric suction ψ0With measurement quality moisture content w0Serial measured data, which substitutes into VG model, fits soil―structure interaction, and obtains measurement fitting parameter a based on the soil―structure interaction0、m0、n0；And step 3. will measure fitting parameter a0、m0、n0It substitutes into and deforms in native air inlet value prediction model, calculate soil body air-entry value under deformation condition, as predicted value.
Description
Technical field
The invention belongs to soil body pore structure distribution characters and unsaturated soil water retention characteristic technical field, and in particular to a kind of
Deformation soil air-entry value prediction technique based on VG model.
Technical background
Value of air-entry suction ψa(air entry value) refers to suction when initially entering air in saturated soil dehydration
Force value.When the moisture in soil is in a saturated state, if applying small suction to soil, in soil and anhydrous discharge, contain
Water still maintains saturation value.After suction increases to value of air-entry suction, maximum pore cannot resist applied suction in soil,
Then soil starts to drain, and water content starts to reduce.Air-entry value (i.e., value of air-entry suction) is on soil-water feature (dehumidification) curve
A catastrophe point, by by oblique line elongated segment on soil―structure interaction, and trunnion axis corresponding with saturated aqueous rate intersects,
The corresponding matric suction of its intersection point is air-entry value；Before this suction, the variation of moisture content is small；When matric suction reaches
To after air-entry value, moisture content sharp fall with the increase of suction.The precision of air-entry value is to starting point in high saturation area
Dehumidification scan line has large effect, also functions to vital effect simultaneously for capillary accumulation type design of impervious layer.Therefore,
Carrying out prediction to soil body air-entry value under deformation condition is a very important job in soil―structure interaction research.
It the use of the model of more description soil―structure interaction is at present van Genuchten model, the suction of the model
Range is wider, can indicate the soil―structure interaction in full range of negative pressure, good to different types of medium fitting effect, tool
There is wide applicability.
Air-entry value prediction frequently with traditional graphing method or fitting parameter estimate as a result, calculating process is more complex, it is artificial because
Element is more, and the prediction of soil body air-entry value is cumbersome under deformation condition.
Summary of the invention
The present invention be to solve the above-mentioned problems and carry out, and it is an object of the present invention to provide it is a kind of based on the deformation soil of VG model into
Gas value prediction technique, being capable of quickly and efficiently prediction of distortion soil air-entry value.
The present invention to achieve the goals above, uses following scheme:
The present invention provides a kind of deformation soil air-entry value prediction technique based on VG model, which is characterized in that including following step
It is rapid:
Step 1. measures the measurement matric suction ψ under deformation condition based on pressure plate test0With measurement quality moisture content w0's
Serial measured data；
Step 2. will measure matric suction ψ0With measurement quality moisture content w0Serial measured data is substituted into VG model and is fitted
Soil―structure interaction, and measurement fitting parameter a is obtained based on the soil―structure interaction0、m0、n0；
Step 3. will measure fitting parameter a0、m0、n0It substitutes into and deforms in native air inlet value prediction model, calculate deformation condition
Lower soil body air-entry value, as predicted value,
Deform native air inlet value prediction model are as follows:
ψ is matric suction in formula, and a indicates parameter related with air-entry value, and it is after air-entry value and de- that n indicates that matric suction is greater than
The related parameter of water speed rate, m are parameters related with residual amount,GsFor specific density of solid particles, e1
To deform preceding initial void ratio, wsTo be saturated quality moisture content, wrFor residual qualities moisture content.
Deformation soil air-entry value prediction technique provided by the invention based on VG model, can also have the feature that in step
In rapid 1, pressure plate test instrument be volumetric pressure plate instrument, atmospheric pressure be respectively 5kPa, 10kPa, 30kPa, 80kPa,
160kPa, 280kPa, 450kPa, 700kPa, 1250kPa are accurately measured after the pressure balance of every level-one and are calculated each initial
Void ratio quality of soil sample moisture content, upper level can just continue to next stage pressure, finally obtained different aperture ratio after balancing
Under the conditions of the soil body measurement matric suction ψ0With measurement quality moisture content w0。
In addition, in the deformation soil air-entry value prediction technique provided by the invention based on VG model: base will be measured in step 2
Matter suction ψ0With measurement quality moisture content w0It substitutes into VG model, is by w0Substitute into the w, ψ of VG model0The ψ for substituting into VG model, into
And soil―structure interaction is fitted, obtain measurement fitting parameter a0、m0、n0.And fitting parameter generation in step 2, will be measured
Enter also further calculate out the preceding soil body air-entry value ψ of deformation in following equationa0:
The action and effect of invention
Deformation soil air-entry value prediction technique provided by the present invention based on VG model is with VG model for basic formula,
Establish soil body air inlet value prediction model under deformation condition, data fitting carried out using Matlab software, method is simple and precision compared with
Height, VG empirical model show good precision and ease and extensive on the Mathematical Fitting to soil―structure interaction
Using；In addition, the deformation soil air inlet value prediction model established is simple, convenience of calculation need to only measure a kind of soil of initial void ratio
Body soil―structure interaction can predict the soil body air-entry value under other deformation conditions, substantially reduce calculating process difficulty, from
And prediction of distortion soil air-entry value more efficiently, and then more easily study unsaturated soil distribution of pores characteristic.
Detailed description of the invention
Fig. 1 is Hunan red clay soil―structure interaction fitted figure in the embodiment of the present invention；
Fig. 2 is the soil―structure interaction that mass water content indicates under the conditions of different initial void ratios in the embodiment of the present invention
Figure；
Fig. 3 is that native air-entry value measured value and VG model predication value comparison diagram are deformed in the embodiment of the present invention.
Specific embodiment
Specific implementation below in conjunction with attached drawing to the native air-entry value prediction technique of the deformation based on VG model of the present invention
Scheme is described in detail.
<embodiment one>
As shown in Figure 1, the deformation soil air-entry value prediction technique based on VG model provided by the present embodiment includes following step
It is rapid:
Step 1. measures the measurement matric suction ψ under deformation condition based on pressure plate test0With measurement quality moisture content w0's
Serial measured data.
Pressure plate test instrument be volumetric pressure plate instrument, atmospheric pressure be respectively 5kPa, 10kPa, 30kPa, 80kPa,
160kPa, 280kPa, 450kPa, 700kPa, 1250kPa are accurately measured after the pressure balance of every level-one and are calculated different aperture
The quality of soil sample moisture content than under the conditions of, upper level can just continue to next stage pressure after balancing, finally obtained different initial
Test data under void ratio.Wherein, measured data includes measurement matric suction ψ0With measurement quality moisture content w0.The present embodiment
In it is as shown in table 1 below, measured data shares 10 groups.
The soil―structure interaction measured data table that 1 initial void ratio of table is 1.115
Step 2. will measure matric suction ψ0With measurement quality moisture content w0Serial measured data is substituted into VG model and is fitted
As shown in Figure 1 goes out soil―structure interaction, and obtains measurement fitting parameter a based on the soil―structure interaction0、m0、n0.Soil-water
Horizontal axis is measurement matric suction ψ in indicatrix0, the longitudinal axis be measurement quality moisture content w0.Fitting parameter a will be measured0、m0、n0Generation
Enter in following equation, and then calculate soil body air-entry value before deformation:
In this implementation one, fitting parameter a is measured0、m0、n0Respectively 0.5607,0.03144,3.947, deform before the soil body into
Gas value ψa0For 1.15kPa.
Step 3. will measure fitting parameter a0、m0、n0It substitutes into and deforms in native air inlet value prediction model, Hunan red clay is become
Soil body air-entry value is calculated under the conditions of shape, as predicted value.
Deform native air inlet value prediction model are as follows:
ψ is matric suction in formula, and a indicates parameter related with air-entry value, and it is after air-entry value and de- that n indicates that matric suction is greater than
The related parameter of water speed rate, m are parameters related with residual amount,GsFor specific density of solid particles, e1
To deform preceding initial void ratio, wsTo be saturated quality moisture content, wrFor residual qualities moisture content.
The derivation process of the deformation soil air inlet value prediction model are as follows:
1) VG model is
In formula: wrFor residual qualities moisture content, wsTo be saturated quality moisture content, a indicates parameter related with air-entry value, n table
Show that matric suction is greater than parameter related with rate of water loss after air-entry value, m is parameter related with residual amount, and ψ is matrix suction
Power.
As shown in Fig. 2, making horizontal line w=e1/Gs, with e before deformation0When soil―structure interaction intersection point abscissa
Being approximately considered is e1When air-entry value ψa1。
2) VG model and w=e are combined1/Gs, it can obtain:
3) further deformation is available:
In the present embodiment one, calculated predicted value is 3.61kPa, by deformation soil air-entry value measured value 3.21kPa and in advance
Measured value comparison coincide good.
<embodiment two>
In the present embodiment two, specific prediction technique is identical with embodiment one, and so it will not be repeated, only the specific number of explanation
According to: measurement fitting parameter a0、m0、n0Respectively 0.5607,0.03144,3.947, by void ratio after measurement fitting parameter and deformation
The native air inlet value prediction model of deformation is substituted into for 0.97 k value, the deformation soil air-entry value of prediction is 6.79kPa, and measured value is
5.70kPa。
<embodiment three>
In the present embodiment three, specific prediction technique is identical with embodiment one, and so it will not be repeated, only the specific number of explanation
According to: measurement fitting parameter a0、m0、n0Respectively 0.5607,0.03144,3.947, by void ratio after measurement fitting parameter and deformation
The native air inlet value prediction model of deformation is substituted into for 0.90 k value, the deformation soil air-entry value of prediction is 13.29kPa, and measured value is
10.42kPa。
<example IV>
In the present embodiment four, specific prediction technique is identical with embodiment one, and so it will not be repeated, only the specific number of explanation
According to: measurement fitting parameter a0、m0、n0Respectively .5607,0.03144,3.947, by void ratio after measurement fitting parameter and deformation
The native air inlet value prediction model of deformation is substituted into for 0.84 k value, the deformation soil air-entry value of prediction is 27.59kPa, and measured value is
28.79kPa。
As shown in figure 3, by the deformation soil air-entry value predicted value being calculated in above-described embodiment one to three and measured value into
Row comparison, the performance that coincide is good, illustrates that this method accuracy is good.
Above embodiments are only the illustration done to technical solution of the present invention.It is according to the present invention to be based on VG mould
The native air-entry value prediction technique of the deformation of type is not limited to content described in above embodiments, but is limited with claim
Subject to fixed range.Any modify or supplement or wait that those skilled in the art of the invention are done on the basis of the embodiment
Effect replacement, all in claim range claimed of the invention.
Claims (2)
1. a kind of deformation soil air-entry value prediction technique based on VG model, which comprises the following steps:
Step 1. measures the measurement matric suction ψ under deformation condition based on pressure plate test0With measurement quality moisture content w0Series
Measured data；
Step 2. will measure matric suction ψ0With measurement quality moisture content w0Serial measured data substitute into fitting in VG model be unearthed-
Water characteristic curve, and measurement fitting parameter a is obtained based on the soil―structure interaction0、m0,n0；
Step 3. will measure fitting parameter a0、m0、n0It substitutes into and deforms in native air inlet value prediction model, calculate native under deformation condition
Body air-entry value, as predicted value,
The native air inlet value prediction model of the deformation are as follows:
ψ is matric suction in formula, and a indicates parameter related with air-entry value, and n indicates fast with dehydration after matric suction is greater than air-entry value
The related parameter of rate, m are parameters related with residual amount,GsFor specific density of solid particles, e1For deformation
Preceding initial void ratio, wsTo be saturated quality moisture content, wrFor residual qualities moisture content.
2. the deformation soil air-entry value prediction technique according to claim 1 based on VG model, it is characterised in that:
Wherein, in step 1, pressure plate test instrument be volumetric pressure plate instrument, atmospheric pressure be respectively 5kPa, 10kPa,
30kPa, 80kPa, 160kPa, 280kPa, 450kPa, 700kPa, 1250kPa are accurately measured simultaneously after the pressure balance of every level-one
Each initial void ratio quality of soil sample moisture content is calculated, next stage pressure can be just continued to after upper level balance, finally obtain
Different aperture ratio under the conditions of the soil body measurement matric suction ψ0With measurement quality moisture content w0。
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113310871A (en) * | 2021-05-21 | 2021-08-27 | 湖北工业大学 | Simplified and unified method for predicting air intake value based on saturated permeability coefficient |
| CN114117766A (en) * | 2021-11-19 | 2022-03-01 | 江苏科技大学 | Parameter fitting method for VG model |
| CN114117766B (en) * | 2021-11-19 | 2024-04-26 | 江苏科技大学 | Parameter fitting method for VG model |
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| CN114117766A (en) * | 2021-11-19 | 2022-03-01 | 江苏科技大学 | Parameter fitting method for VG model |
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