CN103604717A - Volume displacement method and apparatus for measuring soil mass water content - Google Patents

Abstract

The invention provides a volume displacement method for measuring soil mass water content, which comprises the following steps: filling a constant-volume container with a known volume with a soil sample to be measured with an arbitrarily volume, weighing the mass of the soil sample to be measured; filling water into the constant-volume container with the soil sample to be measured, weighing the total mass of the soil sample and water in the constant-volume container filled with water; and calculating the soil mass water content according to a formula. The invention also provides an apparatus used in the method, and the device comprises a constant-volume container, a weighing device, and a water-injecting device, wherein the constant-volume container is used for accommodating soil sample to be measured, the water-injecting device is used for injecting water into the constant-volume container, and the weighing device is used for weighing mass. The method of the invention is suitable for water content measurement of soil with any quality, is simple and convenient in operation process, and overcomes the problems of other methods for measuring water content, such as time wasting and unsuitability for field work for drying methods, energy consumption and relatively low measurement precision for burning methods.

Description

Measure the volume displaced method and apparatus of soil quality water percentage

Technical field

The present invention relates to pedology field, be specifically related to a kind of volume displaced method and apparatus of measuring soil quality water percentage.

Background technology

Soil quality water percentage is the physical quantity that characterizes the dry wet degree of certain depth soil layer, it is an important parameter in agricultural production, determining soil moisture is the element task of carrying out soil moisture analysis, its direct measurement is the basis of correlative study and application, very important in the research and practices such as soil mechanics, arable farming, field irrigation, ecologic environment, so it is very important to obtain exactly the information of soil quality water percentage.Particularly, along with water resources crisis becomes increasingly conspicuous, to water-saving agriculture, research is all paid close attention both at home and abroad, and soil quality water percentage has also just become the project of often measuring in water-saving agriculture research.In the engineerings such as production and construction, agricultural, water conservancy, need easy, Fast Measurement soil quality water percentage.

At present, the method for directly measuring soil quality water percentage mainly contains dries Weight or combustion method, and as the unique method of direct measurement soil water content, wherein drying Weight is standard method.These two kinds of bases that method is other all indirect measurement methods have the incomparable advantage of other indirect measurement method in measuring accuracy.The oven drying method of traditional measurement water percentage is more time-consuming and be not suitable for field work; Combustion method consumes the energy, and measuring accuracy is relatively low.Other indirect measurement methods (as TDR, FDR, gamma ray, capacitive transducer, Neutron etc.), must adopt one of above-mentioned two kinds of direct measuring method to calibrate and demarcate, exist simultaneously expensive, not easy to operate, may be to many-sided defects such as harm are larger.Therefore, direct measuring method is extremely important simply and easily.

Summary of the invention

In order to overcome the problems such as complicated operation of the method existence of measuring for a long time soil quality water percentage, the present invention aims to provide a kind of volume displaced method and apparatus of measuring soil quality water percentage.

Volume displaced side's ratio juris that the present invention measures soil quality water percentage is as follows:

Soil is the three-phase mixture by soil particle, water and gas composition.The quality of air is negligible in calculating, so the quality of soil sample to be measured of getting is mainly determined containing quality by soil particle quality and soil sample to be measured.

Because soil sample fills to such an extent that closely still fill to obtain the loose situation that all only affects aeration porosity in soil, can not affect soil bulk density, soil particle volume, soil sample to be measured containing quality, the moisture volume of soil sample to be measured, while therefore sampling, can appoint and get soil sample to be measured.

Arbitrary volume soil sample to be measured is packed in constant volume container, claim to such an extent that fill with water in the backward container of quality of soil sample m to be measured, claiming quality to obtain after topped up with water the gross mass of soil sample and water in constant volume container is m ', now, in container, the quality of material comprises the quality sum that soil particle quality, soil sample to be measured contain quality and keep the skin wet, and relationship between quality expression formula is:

m'=m _s+m _w+m _r （1）

Wherein, m _rfor supplementary biodiversity in constant volume container, the g of unit.

The process of water filling is by the gas displacement in soil sample and constant volume container out.The quality of supplementary moisture is known, and original gas-filled space (original soil sample and constant volume container) is the volume of the water displacement being injected into.According to volume relationship, can calculate the moisture volume of soil sample to be measured and soil particle volume sum, poor for the volume of constant volume container and the volume keeping the skin wet.As following relationship:

v _s+v _w=v'-m _r/ρ _w （2）

In soil sample, the quality of soil particle and water equals respectively their volumes separately and the product of density.

So obtain:

$v_s=\frac{m-{\mathrm{\ρ}}_w{v}_0}{{\mathrm{\ρ}}_s-{\mathrm{\ρ}}_w}---\left(3\right)$

$v_w=\frac{{\mathrm{\ρ}}_s{v}_0-m}{{\mathrm{\ρ}}_s-{\mathrm{\ρ}}_w}---\left(4\right)$

In formula,

$v_0=v^{\′}-\frac{m_r}{{\mathrm{\ρ}}_w}---\left(5\right)$

For soil particle volume and the moisture volume sum of soil sample to be measured, the cm of unit ³.

According to soil bulk density and water-mass density, can obtain the quality of soil particle and initial aqueous:

m _s=v _sρ _s （6）

m _w=v _wρ _w （7）

According to definition, soil moisture content is calculated by following formula:

$\mathrm{\θ}=\frac{m_w}{m_s}\×100\%---\left(\text{8}\right)$

Then according to formula (6), (7), (8), obtain the water percentage of any soil.

$\mathrm{\θ}=\frac{v_w{\mathrm{\ρ}}_w}{v_s{\mathrm{\ρ}}_s}\×100\%---\left(9\right)$

A kind of volume displaced method of measuring soil quality water percentage provided by the invention, concrete steps are as follows:

Pack soil sample to be measured into constant volume container that volume is known, claim quality of soil sample to be measured; To being equipped with in the constant volume container of soil sample to be measured, fill with water, weigh after topped up with water the gross mass of soil sample and water in constant volume container; According to following formula, calculate soil moisture content:

Formula 1:m _r=m'-m

Formula 2:v ₀=v'-m _r/ ρ _w

Formula 3: $v_s=\frac{m-{\mathrm{\ρ}}_w{v}_0}{{\mathrm{\ρ}}_s-{\mathrm{\ρ}}_w}$

Formula 4: $v_w=\frac{{\mathrm{\ρ}}_s{v}_0-m}{{\mathrm{\ρ}}_s-{\mathrm{\ρ}}_w}$

Formula 5: $\mathrm{\θ}=\frac{v_{\text{w}}{\mathrm{\ρ}}_w}{v_s{\mathrm{\ρ}}_s}\×100\%$

In formula, m _rfor the quality of injected water, m is quality of soil sample to be measured, and m ' is the gross mass of soil sample and water in constant volume container after topped up with water, the g of unit, and v ' is constant volume vessel volume, v ₀for soil particle volume and the moisture volume sum of soil sample to be measured, v _sfor soil particle volume, v _wfor the moisture volume of soil sample to be measured, the cm of unit ³; ρ _wfor water-mass density, ρ _sfor soil bulk density, the g/cm of unit ³; θ is soil quality water percentage, the % of unit;

Described constant volume container is comprised of the liquid level locating cover of a regular shape and on-deformable container and upper end thereof, on liquid level locating cover, is provided with water filling port, in vessel port, is provided with gap; By add a cover the volume that liquid level locating cover controls in container in the upper end of container, be constant, by water filling port, to slow liquid make-up in constant volume container, gap is for discharging the liquid that exceeds constant volume vessel volume.

Wherein, temperature is when 4 ℃ of left and right, and the density of water is 1.000g/cm ³, in the situation that temperature variation is little, can be by water-mass density ρ when calculating _wvalue 1.000g/cm ³; Soil bulk density ρ _ssize is relevant with chemistry and the mineral composition of soil, and the particle density of general soil is many at 2.6～2.8g/cm ³in scope, the soil bulk density value conventionally adopting during calculating is 2.653g/cm ³.

Wherein, described constant volume container is preferably the shapes such as cylindrical, rectangular parallelepiped or polygon prism.

Wherein, the material requirements of described constant volume container has certain repellency and not yielding.Stupalith or general metal material all can as aluminium, stainless steel, alloy etc.

Wherein, described in fill with water, for add water in constant volume container, to liquid level, approach constant volume vessel port, cover liquid level locating cover, till slowly inwardly dripping and have water droplet to occur to gap place by water filling port.

Wherein, computation process can be calculated by artificial calculating, counter, computing machine calculates, and is preferably the data of mensuration are directly imported to computing machine, according to enrolling required formula, automatically calculates soil quality water percentage.

Another object of the present invention is to provide the volume displaced method equipment used of measuring soil quality water percentage, constant volume container, weighing-appliance, water injection equipment, consists of; Wherein constant volume container is used for holding soil sample to be measured, and water injection equipment is for past constant volume container water filling, and weighing-appliance is used for weighing quality.

Wherein, described weighing-appliance is balance, preferred electron balance.

Wherein, the preferred dropper of described water injection equipment, more preferably glue head dropper.

Wherein, described computing equipment preferred computer.

The application of the volume displaced method that the present invention also provides described measurement soil quality water percentage in measuring soil physical properties.

Advantage provided by the invention is:

The volume displaced method of measurement soil quality water percentage of the present invention is applicable to the measurement of water ratio of any quality, arbitrary volume/quality soil, and operating process is simple, convenient.It is more time-consuming and be not suitable for field work that method of the present invention has overcome the oven drying method of traditional measurement water percentage, and combustion method consumes the energy, the relatively low problem of measuring accuracy, has good application prospect.

The stabilization of equipment performance of volume displaced method that the present invention measures soil quality water percentage is good, can measure the gross mass of soil and water after the initial mass of arbitrary volume/quality soil and water filling, by calculating soil quality water percentage, convenient, fast, accurate.

Accompanying drawing explanation

In Fig. 1 embodiment 1, the present invention measures the structural representation of the volume displaced method device therefor of soil quality water percentage.

In Fig. 2 embodiment 1, the present invention measures the constant volume structure of container schematic diagram in the volume displaced method device therefor of soil quality water percentage.

In Fig. 3 embodiment 1, the present invention measures the constant volume container photo in the volume displaced method device therefor of soil quality water percentage.

Fig. 4 is the volume displaced method of the bright measurement soil quality of embodiment 2 this law water percentage and the result comparison diagram of oven drying method.

Wherein, 1 is constant volume container, and 2 is electronic balance, and 3 is glue head dropper, and 4 is water filling port, and 5 is gap, and 6 is liquid level locating cover.

Embodiment

Following examples are used for illustrating the present invention, but are not used for limiting the scope of the invention.

Embodiment 1 the present invention measures the volume displaced method device therefor of soil quality water percentage

The volume displaced method device therefor structural drawing that the present invention measures soil quality water percentage as shown in Figure 1, comprise constant volume container 1, weighing-appliance electronic balance 2(Shanghai Zhuojing Electronic Technology Co., Ltd., model: BSM-5200.2), the conventional simple glass matter glue head dropper in water injection equipment glue head dropper 3(laboratory).

Wherein, as shown in Figure 2, Fig. 3 is shown in by photo in kind to the structural representation of constant volume container 1.Constant volume container 1(comprises constant volume container and the liquid level locating cover two parts that remove liquid level locating cover) be a cylinder shape belt liquid level locating cover container, on its liquid level locating cover 6, be provided with water filling port 4, in vessel port, be provided with gap 5.Constant volume container 3 internal diameter 75mm, external diameter 81mm, high 63mm, wall thickness 3mm, the thick 3mm of liquid level locating cover 6.The dark 3mm of gap 5, width 5mm, for to 45 ° of internal cuttings; Water filling port 4 lower port diameters are 2mm, and upper port slightly larger in diameter is in lower port.Constant volume container 1 material is metal material.

Embodiment 2 measures the volume displaced method of soil quality water percentage and the comparison of oven drying method

Device therefor is referring to embodiment 1.

Test adopts 3 kinds of earth materials, is respectively and picks up from the black earth in Pekinese's silty loam, Jilin and the glutinous laterite in Jiangxi (being called below T1, T2, T3), to check the measurement precision of this device to different soils.T1, T2, T3 are prefabricated into respectively 5 kinds of design water percentage: 10%, 15%, 20%, 25%, 30%.

3 kinds of soil samples (T1, T2 and T3) of different designs water percentage are divided into respectively to 3 one's share of expenses for a joint undertaking samples, the volume displaced method that 3 one's share of expenses for a joint undertaking samples are measured soil quality water percentage for the present invention is measured, under 105 ℃ of conditions, dry with traditional oven drying method and measure afterwards, be every kind of soil repeating for 3 times in different designs water percentage situation and test.

The volume displaced method of measuring soil quality water percentage, concrete steps are as follows:

Pack soil sample to be measured into constant volume container that volume is v', claim quality of soil sample m to be measured; To water filling in the constant volume container of soil sample to be measured is housed, cover liquid level locating cover, then with glue head dropper, by water filling port, continue slowly in constant volume container, dropwise to add water, until gap place stops while having water droplet to occur, now soil particle and water are full of constant volume container, the soil sample state that reaches capacity, the water of injection all cements out the air that was originally present in soil sample.With thieving paper, clean on constant volume chamber wall residual water stain, reading numerical values when electronic scales stable reading is constant, weighing after topped up with water the gross mass of soil sample and water in constant volume container is m '; According to following formula, calculate soil moisture content:

Formula 1:m _r=m'-m

Formula 2:v ₀=v'-m _r/ ρ _w

Formula 3: $v_s=\frac{m-{\mathrm{\&rho;}}_{\mathrm{<figure-callout\; id="0"\; label="w\; v"\; filenames="HDA0000398363900000022.png"\; state="\{\{state\}\}">w</figure-callout>}}{v}_{}{}_0}{{\mathrm{\&rho;}}_s-{\mathrm{\&rho;}}_w}$

Formula 4: $v_w=\frac{{\mathrm{\&rho;}}_s{v}_0-m}{{\mathrm{\&rho;}}_s-{\mathrm{\&rho;}}_w}$

Formula 5: $\mathrm{\&theta;}=\frac{v_{\text{w}}{\mathrm{\&rho;}}_w}{v_s{\mathrm{\&rho;}}_s}\&times;100\%$

In formula, m _rfor the quality of injected water, the g of unit; v ₀for soil particle volume and the moisture volume sum of soil sample to be measured, v _sfor soil particle volume, v _wfor the moisture volume of soil sample to be measured, the cm of unit ³; ρ _wfor water-mass density, ρ _sfor soil bulk density, the g/cm of unit ³; θ is soil quality water percentage, the % of unit.

Tradition oven drying method is measured as and soil sample is placed in to the baking oven of 105 ℃, after oven dry 72h, takes out and weighs, and by traditional oven drying method, calculates soil quality water percentage.Drying plant is drying baker (Chinese-foreign joint Chongqing Si Da experimental apparatus company limited, model: CS101-1E).

The result that the result recording by method of the present invention and traditional geotechnological measuring method (oven dry Weight) are measured contrasts, and the accuracy of the inventive method measurement be described.Under the condition of different designs water percentage, use the inventive method to measure any soil sample of T1, T2 and T3, and the soil quality water percentage obtaining and oven drying method (105 ℃, the 72h) result of the measurement comparison of advancing, maximum absolute error is in 1% left and right, as shown in table 1.

The absolute error (%) of table 1 volume displaced measurement soil quality water percentage and the comparison of oven drying method measurement result

The water percentage according to the following formula two kinds of methods being recorded carries out matching, and the matched curve obtaining as shown in Figure 4.

y=Ax

Wherein, y and x are respectively the soil quality water percentage that instrument and traditional oven drying method record, %; A is regression coefficient, characterizes between the result that two kinds of measuring methods record degree one to one.

As seen from Figure 4, the coefficient of determination that 3 kinds of soil sample matchings obtain is all greater than 0.99, shows to have good one-to-one relationship between result that any soil moisture content of this measurement device and oven drying method measure.Measured data shows, this instrument stable work in work, and measurement result has degree of precision, and this apparatus measures process is simple, time saving and energy saving and save the energy, can be applied to the direct measurement of soil quality water percentage.

Measured data shows, method measurement result of the present invention has degree of precision, can meet the instant requirement of measuring in outdoor field, measuring process is simple, time saving and energy saving, the saving energy, can be applied to the direct measurement of any quality, free position Water Content Tests in Soil Samples.

The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, do not departing under the prerequisite of the technology of the present invention principle; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (8)

1. a volume displaced method of measuring soil quality water percentage, concrete steps are as follows:

Pack soil sample to be measured into constant volume container that volume is known, claim quality of soil sample to be measured; To being equipped with in the constant volume container of soil sample to be measured, fill with water, weigh after topped up with water the gross mass of soil sample and water in constant volume container; According to following formula, calculate soil moisture content:

Formula 1:m _r=m'-m

Formula 2:v ₀=v'-m _r/ ρ _w

Formula 3: $v_s=\frac{m-{\mathrm{\&rho;}}_w{v}_0}{{\mathrm{\&rho;}}_s-{\mathrm{\&rho;}}_w}$

Formula 4: $v_w=\frac{{\mathrm{\&rho;}}_s{v}_0-m}{{\mathrm{\&rho;}}_s-{\mathrm{\&rho;}}_w}$

Formula 5: $\mathrm{\&theta;}=\frac{v_{\text{w}}{\mathrm{\&rho;}}_w}{v_s{\mathrm{\&rho;}}_s}\&times;100\%$

In formula, m _rfor the quality of injected water, m is quality of soil sample to be measured, and m ' is the gross mass of soil sample and water in constant volume container after topped up with water, the g of unit, and v ' is constant volume vessel volume, v ₀for soil particle volume and the moisture volume sum of soil sample to be measured, v _sfor soil particle volume, v _wfor the moisture volume of soil sample to be measured, the cm of unit ³; ρ _wfor water-mass density, ρ _sfor soil bulk density, the g/cm of unit ³; θ is soil quality water percentage, the % of unit;

Described constant volume container is comprised of the liquid level locating cover of a regular shape and on-deformable container and upper end thereof, on liquid level locating cover, is provided with water filling port, in vessel port, is provided with gap; By add a cover the volume that liquid level locating cover controls in container in the upper end of container, be constant, by water filling port, to slow liquid make-up in constant volume container, gap is for discharging the liquid that exceeds constant volume vessel volume.

2. method according to claim 1, is characterized in that, water-mass density ρ _wvalue 1.000g/cm ³, soil bulk density ρ _svalue 2.653g/cm ³.

3. method according to claim 1, is characterized in that, described in fill with water, for add water in constant volume container, to liquid level, approach constant volume vessel port, cover liquid level locating cover, till slowly inwardly dripping and have water droplet to occur to gap place by water filling port.

4. method equipment used described in claim 1-3 any one, is characterized in that, constant volume container, weighing-appliance, water injection equipment, consists of; Wherein constant volume container is used for holding soil sample to be measured, and water injection equipment is for past constant volume container water filling, and weighing-appliance is used for weighing quality.

5. equipment claimed in claim 4, is characterized in that, described weighing-appliance is balance.

6. equipment claimed in claim 5, is characterized in that, described weighing-appliance is electronic balance.

7. equipment claimed in claim 4, is characterized in that, described water injection equipment is dropper.

8. the application of method in measuring soil physical properties described in claim 1-3 any one.

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