# Method of determination of filtration coefficient of soils created on overburdens

FIELD: agriculture.

SUBSTANCE: description of the soil horizons is provided with identification of degree of their gleization, samples are prepared of natural soils over horizons using the cut cylinder with small volume. Method differs in that using samples density of dry mass of soil is determined, after this work completion, and samples destruction - selection of the mixed soil sample and determination of its grain-size classification, according to ratio of content in fine soil of the particles with size exceeding dust, i.e. over 0.05 mm, to density of the soil at the pre-plotted calibration diagram the average geometric value of the filtration coefficient of p% probability of decreasing over the soil horizons considering degree of their gleization is estimated.

EFFECT: reduced R&D expenses, more rational use of funds for lands reclamation, operation of reclamation systems and use of reclaimed lands.

1 tbl, 1 dwg

The invention relates to the field of agriculture and complex melioration of agricultural landscapes and can be used in the practice of drainage of soils for explanation of methods and the methods of drainage, construction of drainage systems and the use of drained land.

The permeability of soils as a basis for land drainage and subsequent use drained soils. The problem of definition is given great attention in many works. One of the substantive work is the work of F. R. Seidelman and P. Manning (Zaidelman F. R., manning, P. Methods for determination of K_{f}to calculate the drainage in the Nonchernozem zone // Hydraulic engineering and land reclamation. - 1979. - No. 11. - S. 57 62...).

This paper analyzes the possibility of application of various methods for determining the permeability of soil thickness, affect the drainage network. Shows the complexity and high costs of work to determine the filtration coefficient. It is emphasized that the permeability of soil genetic horizons of the soil profile inherent property of anisotropy. Therefore, in this work lead identification methods, both vertically and horizontally.

The disadvantages outlined in this paper include:

1. The work is completely lost, uncut�Timoti determine the geometric average values of the filtration coefficient, which, as you know, is equal to the square root of product of values of the vertical and horizontal coefficients of the filter.

2. In given in the review of methods of determining the filtration coefficient into account the variation in area of genetic horizon, which, as you know, due to soil-forming process and anthropogenic activities.

In reclamation practice for determining the filtration coefficient widespread method of sampling natural addition on soil genetic horizons of the soil profile cutting small cylinders of volume equal to 250 cm^{3}(Cm. S. 59 in the above work; the prototype).

The challenge resolved data of the claimed invention, is to develop a rapid and reliable method for determining the geometric average values of filtration coefficient R per cent probability of understating soils, formed on the surface sediments.

The technical result is to increase the informativeness of the designated filtration rate and a considerable reduction on the definition of geometric mean values of filtration coefficient R per cent probability of understating soils, formed on the surface sediments, improvement of methods and software�mandatory drainage, to increase the efficiency of use of drained land, including through more effective use of soil-conservation measures, and, ultimately, in improving the economic and environmental efficiency of drainage of the considered soil.

Put in the invention the task is resolved in that the method of determining the permeability of soils, formed on the surface sediments, includes the passage of the pit, the description of the genetic horizons of the soil profile by determining the degree gleyed, sampling of soils nature composition of genetic horizons of the soil profile cutting cylinder small volume. On the samples is carried out to determine the density of the addition of dry mass of soil, and after the completion of this work and destruction of samples - a selection of mixed soil sample and determining its particle size distribution. In terms of content in the fine earth particles larger than dust size greater than 0.05 mm and density of adding soil on a previously constructed calibration graph to judge the value of the geometric average values of filtration coefficient R per cent probability of understating on genetic horizons of the soil profile to the extent that they are gleyed.

With the aim of improving the reliability of the created structures, and irrigation in particular, tracticketdelete filtration is considered taking into account the probability of its occurrence (GOST 20522-96. Soils. Methods of statistical processing of test results). While land drainage account for the probability of underestimation of p % of the values of the filtration coefficient, which is associated with less nedouchki lands on the side of the square by taking into account several low against average normative values corresponding to R=50%.

Wide spread use of the values of the filtration coefficient R per cent probability of underestimation, in particular, and p=25%, in the practice of reclamation of soils is hampered by the complexity and high costs in its determination.

Put in the invention the task is resolved by determining the density of the addition of dry mass of soil (FS, g/cm^{3}and its granulometric composition - by establishing in the fine earth content of particles larger than dust (larger than 0.05 mm), i.e. (M>05,%) and the ratio µ=(M>05)/PS on the calibration chart (see drawing) determine the geometric average value of the filtration coefficient R per cent probability of understating equal to 25%. When this calibration graph takes into account the degree of gleyed soil genetic horizons.

The adoption of the ratio µ=(M>05)/PS due to the fact that with the increase of the ratio grows and the value of the filtration coefficient and Vice versa, and the adoption of the p%probability zanjani� the calculated values of the filtration coefficient is determined by acceptance and some nethouse soils for p percent of the drained area.

The drawing shows the calibration graph of the dependence of geometric mean values of the filtration coefficient (K_{f}(m/day) at p=25% of the value of the ratio µ constructed on the basis of a large body of evidence. This schedule 1 is used for genetic horizons A2, AW and B1 gleyic and genetic horizons A2_{g}and A2B_{g}gley soils and horizons for B2_{g}gleyic and B_{g}gley soils - schedule 2.

The claimed method of determining the geometric average values of filtration coefficient R per cent probability of understating includes the following operations.

1. Points for determination of filtration properties of soils chosen after the completion of the soil survey. Held in conjunction with their each reclamation district - the territory formed by the homogeneous soil Genesis and composition of parent rocks with the same causes waterlogging.

2. Upon arrival to the destination in the selected produce item:

- the excerpt of the pit;

- establishment of the boundaries of the genetic horizons of the soil profile and its description indicating the distribution gleyed;

- selection of samples from the pit soil genetic horizons with the help of cutting cylinders, and selection of water at the facility and their delivery to the laboratory.

3. In lab perform:

- definition of on about�Azzah density of addition of dry mass of soil genetic horizons (PS,
g/cm^{3});

- the destruction of samples in the cylinders, selection of mixed soil samples to determine their size distribution;

- determination of the granulometric composition of soil genetic horizons;

- the establishment of the results of determination of granulometric composition of soil content in the fine earth by genetic horizons of the larger particles of dust larger than 0.05 mm (M>05, %);

- calculation of genetic horizons of the ratio µ=(M>05)/PS;

- setting the obtained value of µ via a calibration geometric average values of the filtration coefficient K_{f}25% probability of understating on genetic horizons with regard to their gleyed.

The results of implementing the claimed method in the Tver region on two soil profiles at the site "Bukharin" for p=25% (examples of calculation) are shown in the table.

These data suggest that the permeability of the soils, formed on the surface sediments decreases with depth. The permeability of soils gley soils, even when one of their class by grading, lower than gleyic. This must be considered when determining the methods and means of drainage of the considered soils and, primarily, the depth regulating CE�and and uniformity of drainage fields for crop cultivation area and use of the soils after drainage, in particular the application of soil-conservation measures.

The claimed method of determining the K_{f}provides increased technical level of land reclamation, reduce the cost of design and survey works, more rational use of funds for land reclamation, operation of irrigation and drainage systems and the use of the reclaimed land, i.e. the achievement of the expected technical result.

The proposed method of determination of K_{f}more informative in comparison with existing, as well as simple and economical in comparison with other applied until recently. In regard to this method, when organizations determine To_{f}preference should be given. The relative time required for application of this method in comparison with other known methods (see, e.g., pp. 61 in the above work) is decreasing in units of up to two orders of magnitude, while providing higher accuracy and reliability of determination of K_{f}excluding completely the probability of occurrence of random errors and the corresponding random data, since it is based sizing chart - put a large amount of factual data.

In conclusion consider a way of creating a calibration graph.

The essential requirement is the goal, anticipating Reza�adds the future operation, above, surveys without conducting field work associated with the establishment of the filtration coefficient.

To create a calibration graph used data from surveys at sites draining soils, formed on the surface sediments obtained in the determination of permeability of soil genetic horizons of the soil profile based on the selection of monoliths by the method of the cutting cylinder in the horizontal and vertical directions.

In a basis of creation of calibration curve laid more than 1000 field definitions the filtration coefficient. The soils formed in the surface sediments was laid at 24 venues-the"key" to them - 24 of the soil profile. Morphological description of soil profiles selected monoliths and samples for moisture determination. As an example, we give the results of determining the geometric average values of the coefficient of filtration 25% probability of understating, the density of the addition of the dry soil and the content of particles larger than dust size greater than 0.05 mm on one of the soil profiles, the genetic horizon A2B1_{g}on the object "Vyakhirev" in the Tver region.

Cutting cylinders with a diameter of 200 mm was selected from the 6 monoliths (n=6) both in vertical and in the horizontal�nom directions and and samples for determination of soil moisture to determine the density of the addition of dry soil in the selected monoliths. After filtration works from destructible monoliths selected random sample to determine the granulometric composition of soils.

Individual filter coefficient for each i-th monolith (i=1...6) set for phase steady-state filtration. This was measured and the water temperature, and the value of the filter coefficient according to the formula of Hazen were brought to a temperature of 10°C. To conduct seepage studies used soil and groundwater, transported to the laboratory from the sampling monoliths.

The moisture content of the soils was determined thermostat-weight method. The number of replications appointed on the basis of achieving a 10 percent precision at the significance level of 5%. Bulk density of dry soil and its particle size distribution was determined by conventional methods.

Individual values of the filtration coefficient was equal to: in the vertical direction (K_{in})_{i}- 125, 104, 82, 64, 50 and 31 mm/day, and horizontal (K_{g})_{i}- 96, 82, 55, 42, 37 and 22 mm/day.

The result of this work also found that the distribution of permeability in genetically uniform area of soil horizon�and (the variation) is much more different from the normal distribution, than the distribution of the logarithms of the coefficients of the filter. Therefore, in accordance with GOST 20522-96 normative and calculated values of permeability in vertical and horizontal directions were set with the use of the normal distribution of the logarithms of the coefficients of the filter.

The distribution of the log of permeability with greater accuracy is subject to the normal Gaussian law. This was the basis to use for statistical processing of the obtained data t-student distribution.

As an example, consider the calculation of the distribution parameters log vertical filtration coefficient. When applied to the following formula:

the mean value of log (K_{in})_{i}

the magnitude of the error and

log vertical filtration coefficient 25% probability of understating (including the area of spread of individual values (K_{in})_{i}and using the method of confidence interval)

where t_{25}- student test, corresponding to a 25 percent signicance level (one-sided confidence interval, α=0.75 and the number of degrees of freedom (n-1)) laid on the table of percentage points of student's t-test.

The value of K_{in}25% probability of underestimation found in the result of the operation of antilogarithmic To log_{in}.

As a result of the payments received that the genetic horizon A2B1_{g}on the subject of "Vyakhireva" vertical filtration coefficient 25% probability of understating K_{in}=59 mm/day.

Similar calculations were performed for the horizontal permeability. As a result found that a_{g}=42 mm/day.

A higher value of K_{in}against the value K_{g}due to the increased fracturing of the soil horizon A2B1_{g}vertically.

Finished processing data on the genetic horizon of establishing the estimated geometric mean value of the filtration coefficient of 25 per cent probability of understating calculated by the formula^{3}and as a result of determining the granulometric composition of soils: in the fine earth contains larger particles of dust larger than 0.05 mm 12,8%, i.e. (M>05)=12,8%. The value µ=(M>05)/PS=12,8:1,52=8,4.

Similar work was carried out on all genetic horizons of each of the 24 soil profiles posted on the soils formed on the surface sediments. The analysis of the data obtained and processed using known in mathematical statistics methods allowed to install:

1. For genetic horizons A2, AW and B1 gleyic and genetic horizons A2_{g}and A2B_{g}gley soils dependence of the geometric average values of the coefficient of filtration 25% probability of understating in m/day is described by the equation

The dependence has the following boundary conditions: 0,8≤(M>05)≤22 and 1.41≤(PS)≤1,69. The correlation coefficient of estimated and actual data is 0.72, the level of significance of 0.1. The dependence (4) is shown in the calibration chart at number 1.

2. For genetic horizons B2_{g}gleyic and B_{g}gley soils

where K_{f}- also in m/day, agranichnyi conditions dependencies: 0,3≤(M>
05)≤22, 1,47≤(PS)≤1,7. The correlation coefficient of estimated and actual data to 0.94, the level of significance of 0.1. The dependence (5) is shown in the calibration chart at number 2.

It is also necessary to note that the horizontal scale is logarithmic calibration curve, but for the convenience of practical use, the values K_{f}corresponding log K_{f}.

Obtaining calculated data other than a 25 percent probability of understating, p%of the probability can be carried out in a similar manner by the corresponding p values of student's criterion t (see formula 3).

The method for determining the permeability of soils, formed on the surface sediments, including the passage of the pit, the description of the genetic horizons of the soil profile by determining the degree gleyed, sampling of soils nature composition of genetic horizons of the soil profile cutting cylinder of small volume, characterized in that on the samples is carried out to determine the density of the addition of dry mass of soil, and after the completion of this work and destruction of samples - a selection of mixed soil sample and determining its granulometric composition, in terms of content in the fine earth particles larger than dust - dim�more rum 0.05 mm and density of adding soil on a previously constructed calibration graph to judge the value of the geometric average values of filtration coefficient R per cent probability of understating on genetic horizons of the soil profile to the extent that they are gleyed.

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1 tbl, 3 ex

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