CN108982317B - Method for determining large-scale permeability coefficient of high fill soil body - Google Patents
Method for determining large-scale permeability coefficient of high fill soil body Download PDFInfo
- Publication number
- CN108982317B CN108982317B CN201810613729.4A CN201810613729A CN108982317B CN 108982317 B CN108982317 B CN 108982317B CN 201810613729 A CN201810613729 A CN 201810613729A CN 108982317 B CN108982317 B CN 108982317B
- Authority
- CN
- China
- Prior art keywords
- scale
- permeability coefficient
- simulation
- ring
- soil body
- 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.)
- Expired - Fee Related
Links
- 230000035699 permeability Effects 0.000 title claims abstract description 197
- 239000002689 soil Substances 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 33
- 238000004088 simulation Methods 0.000 claims abstract description 78
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 66
- 238000012360 testing method Methods 0.000 claims abstract description 58
- 238000009826 distribution Methods 0.000 claims abstract description 40
- 230000008859 change Effects 0.000 claims abstract description 16
- 230000000694 effects Effects 0.000 claims abstract description 14
- 238000004364 calculation method Methods 0.000 claims description 26
- 238000005070 sampling Methods 0.000 claims description 17
- 230000035945 sensitivity Effects 0.000 claims description 13
- 238000007619 statistical method Methods 0.000 abstract description 8
- 238000013508 migration Methods 0.000 abstract description 3
- 230000005012 migration Effects 0.000 abstract description 3
- 238000011160 research Methods 0.000 abstract description 3
- 238000011065 in-situ storage Methods 0.000 abstract 1
- 230000035515 penetration Effects 0.000 description 10
- 238000002474 experimental method Methods 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 230000001186 cumulative effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 125000002619 bicyclic group Chemical group 0.000 description 1
- 238000010835 comparative analysis Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000005429 filling process Methods 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000012821 model calculation Methods 0.000 description 1
- 230000003204 osmotic effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000010206 sensitivity analysis Methods 0.000 description 1
- 238000012163 sequencing technique Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Images
Classifications
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Dispersion Chemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
- Management, Administration, Business Operations System, And Electronic Commerce (AREA)
Abstract
The invention discloses a method for determining a large-scale permeability coefficient of a high fill soil body, which comprises the following steps: acquiring the change rule, anisotropy and heterogeneity of the permeability coefficient of the landfill soil body in space on the cutting ring scale; carrying out field double-ring water seepage tests at different positions of a high-fill soil body to obtain the permeability coefficient value on the cutting ring scale; combining a scale effect principle to carry out simulation on a field double-ring water seepage test; and (3) amplifying the simulation of the field double-ring water seepage test to a large scale for simulation, and combining the original distribution of the permeability coefficient of the landfill soil body on the cutting ring scale to obtain the distribution of the large-scale permeability coefficient. The invention relates to a large-scale permeability coefficient required by the research and prediction of future underground water migration rules of a non-homogeneous high-fill soil body, namely, the large-scale permeability coefficient of the high-fill soil body which is difficult to perform in a large-scale in-situ test and high in heterogeneity is analyzed and researched by a large number of methods and means such as tests, statistical analysis, condition simulation, scale effect and the like.
Description
Technical Field
The invention relates to the technical field of soil permeability coefficients, in particular to a method for determining a large-scale permeability coefficient of a high fill soil body.
Background
Loess is widely distributed in China, and due to the characteristic of easy erosion of loess, hilly gullies become the main landform type of loess, and a large amount of large-scale gullies exist even in loess tablelands, and the size of the gullies is continuously enlarged. In recent years, with the development of economy and society, land resources have become increasingly tense. In order to meet the demand, large-scale trench filling and land leveling projects are started to appear in loess areas, and a large amount of high fill loess filling bodies are produced. The change of the landform shape in the major geotechnical engineering will inevitably affect the movement law of underground water, and the numerical simulation is an effective way for predicting the movement law of underground water under the future condition. In numerical simulation, the accuracy of the permeability coefficient is a key factor affecting the calculation result.
A large number of studies have shown that the permeability coefficient varies with the study scale, i.e. has a certain scale effect. Schulze-Makuch et al demonstrate the rule that the permeability coefficient increases with the increase of the observation scale and tends to be stable through the data of 39 geological medium permeability coefficients and the test scale, and the permeability coefficient is equal to the permeability coefficient before the permeability coefficient tends to be stableThe observation scale is linear in logarithmic coordinate values. The existing determination methods of the permeability coefficient mainly comprise a permeameter method, a double-ring water seepage method, a water pumping test method, a water injection test method and the like. However, due to condition limitation, the pumping test and the water injection test are difficult to perform, and the numerical simulation of the area is based on a large-scale subdivision grid, and the indoor infiltration test is performed on a small scale and has the volume of only 120cm3The calculation result is difficult to represent the permeability coefficient on a large scale. In addition, loess in the landfill area has strong heterogeneity, and the distribution of the permeability coefficient of the large-area landfill area cannot be comprehensively reflected by a few field water seepage tests. How to determine the large-scale permeability coefficient of the high fill soil becomes a key problem for researching the groundwater simulation.
In summary, the permeability coefficient determining method in the prior art has the problem that the permeability coefficient of the high fill soil body with a large scale cannot be determined.
Disclosure of Invention
The embodiment of the invention provides a method for determining a large-scale permeability coefficient of a high fill soil body, which is used for solving the problem that the large-scale permeability coefficient of the high fill soil body cannot be determined in the prior art.
The embodiment of the invention provides a method for determining a large-scale permeability coefficient of a high fill soil body, which comprises the following steps: sampling at different horizontal plane positions and vertical positions of a high fill soil body, and determining the vertical and transverse permeability coefficients of the soil sample by using a permeameter method to obtain the spatial change rule, anisotropy and heterogeneity of the permeability coefficient of the fill soil body on the cutting-ring scale;
carrying out field double-ring water seepage tests at different positions of a high-fill soil body to obtain the permeability coefficient value on the cutting ring scale;
according to the value of the permeability coefficient on the cutting ring scale and in combination with the scale effect principle, carrying out simulation on a field double-ring water seepage test;
the simulation of the field double-ring water seepage test is amplified to a large scale for simulation, and the distribution of the large-scale permeability coefficient is obtained by combining the change rule, anisotropy and heterogeneity of the permeability coefficient of the landfill soil body on the cutting ring scale in space.
The embodiment of the invention provides a method for determining a large-scale permeability coefficient of a high fill soil body, which further comprises the following steps:
establishing a double-ring water seepage test simulation model, adopting a square grid for space subdivision, setting the top layer of the simulation model as a constant head, setting the head value as 0m, setting the range of an inner ring and an outer ring of the bottom layer of the simulation model as the constant head, and setting the head value equal to the distance from the top layer to the bottom layer of the simulation model;
selecting a certain permeability coefficient representative value according to a scale effect principle, calculating permeability coefficient values obtained by different random distributions under different subdivision scales according to an isotropic medium, comparing the permeability coefficient values with an actual permeability coefficient value of a field double-ring water seepage test, and selecting a proper subdivision size;
and analyzing the sensitivity of the large-scale equivalent permeability coefficient calculation result to different permeability coefficient representative value numbers and anisotropies on the basis of the determined subdivision size.
Further, the simulation of the field double-ring water seepage test is amplified to a large scale for simulation, and the distribution of the large-scale permeability coefficient is obtained by combining the change rule, anisotropy and heterogeneity of the permeability coefficient of the landfill soil body in the space on the cutting ring scale; the method comprises the following steps:
on the basis of the determined subdivision size, selecting a certain representative value number, gradually amplifying the simulation range according to an isotropic medium, calculating permeability coefficients under different random distributions under each simulation range, and determining the simulation range value when the permeability coefficient value tends to be stable along with the increase of the simulation range as the simulation range of the large-scale permeability coefficient;
analyzing the sensitivity of the large-scale equivalent permeability coefficient calculation result to the number of the permeability coefficient representative values, and determining the number of the appropriate representative values;
analyzing the sensitivity of the large-scale equivalent permeability coefficient calculation result to anisotropy, and determining the large-scale permeability coefficient value of the tested ring cutter scale permeability coefficient large sample;
and determining the distribution of the large-scale permeability coefficient according to the relation between the sample and the population.
In the embodiment of the invention, the method for determining the large-scale permeability coefficient of the high fill soil body has the following beneficial effects compared with the prior art:
the invention relates to a high fill soil body with strong heterogeneity, which needs to research and predict the large-scale permeability coefficient needed by the future underground water migration rule, and analyzes and researches the large-scale permeability coefficient of the high fill soil body with high heterogeneity, which is an important parameter for predicting and analyzing the underground water migration rule, through a large number of methods and means such as test, statistical analysis, condition simulation, scale effect and the like, and the large-scale permeability coefficient is difficult to be performed in the high fill soil body, so the invention provides a method for determining the large-scale permeability coefficient of the high fill soil body based on an indoor permeability test and a field double-ring permeability test, because the high fill soil body has the characteristic of strong heterogeneity, the permeability coefficient of the ring cutter scale is obtained through a large number of sampling analysis, and the statistical analysis is performed on the permeability coefficient of the ring cutter size, and (3) combining a scale effect principle, carrying out simulation on the field double-ring water seepage test, expanding the simulation range to a large-scale range on the basis of gradually analyzing various factors influencing the simulation result, and determining the distribution of the large-scale permeability coefficient according to the relation between the sample and the total.
Drawings
Fig. 1 is a flowchart of a method for determining a large-scale permeability coefficient of a high fill soil according to an embodiment of the present invention;
FIG. 2 is a diagram of a sampling site provided by an embodiment of the present invention;
FIG. 3 is a comparison graph of permeability coefficients of the landfill soil in different directions at the same position according to an embodiment of the present invention;
FIG. 4 is a comparison graph of permeability coefficients of the same position of the landfill soil in the same direction according to the embodiment of the invention;
FIG. 5 is a box plot of vertical permeability coefficients for different sampling times provided by an embodiment of the invention;
FIG. 6 is a box plot of permeability coefficients for different sampling times levels provided by an embodiment of the invention;
FIG. 7 is a box plot of vertical permeability coefficients for different sample heights provided by an embodiment of the invention;
FIG. 8 is a box plot of permeability coefficients for different sample height levels provided by an embodiment of the invention;
FIG. 9 is a vertical permeability coefficient histogram provided by an embodiment of the present invention;
FIG. 10 is a histogram of horizontal permeability coefficients provided by an embodiment of the invention;
FIG. 11 is a graph of cumulative frequency of permeability coefficients provided by an embodiment of the invention;
FIG. 12 is a graph showing random distribution of permeability coefficients in a simulated range of a double loop test provided by an embodiment of the present invention;
FIG. 13 is a cross-sectional view of a distribution of constant head boundaries of a dual-loop test model according to an embodiment of the present invention;
FIG. 14 is a graph comparing the results of model calculations and field dual-ring water penetration tests provided in the examples of the present invention;
FIG. 15 is a comparison of the results of the double loop water penetration tests for different combinations of anisotropy provided by the examples of the present invention;
FIG. 16 is a comparison graph of the results of the double-ring water penetration tests with different numbers of representative values provided in the embodiments of the present invention;
FIG. 17 is a comparison graph of large-scale permeability coefficient calculation results for different simulation ranges provided by embodiments of the present invention;
FIG. 18 is a box plot of large-scale permeability coefficient calculation results for different numbers of representative values provided by an embodiment of the present invention;
FIG. 19 is a comparison graph of large-scale permeability coefficient calculations for different combinations of anisotropy provided by an embodiment of the present invention;
fig. 20 is a distribution diagram of the large-scale permeability coefficient calculation result provided by the embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, a method for determining a large-scale permeability coefficient of a high fill soil body according to an embodiment of the present invention includes:
It should be noted that, in order to analyze the change rule, anisotropy and heterogeneity of the osmotic coefficient space on the cutting ring scale, a large number of samples are taken from the high fill soil, the number of samples taken at the same position is 2-3, and the sampling positions are evenly distributed in the whole space.
And 2, carrying out a field double-ring water seepage test at different positions of the high-fill soil body to obtain the permeability coefficient value on the cutting ring scale.
It should be noted that, because the workload of the field double-ring penetration test is relatively large, a few representative points can be selected in the space for testing.
And 3, carrying out simulation on the field double-ring water seepage test according to the permeability coefficient value on the cutting ring scale and by combining the scale effect principle.
The simulation space is divided into cubic grids, the permeability coefficient of the cubic grids is selected according to the permeability coefficient of the cutting ring scale, and the distribution of the permeability coefficients in different grids is determined according to a large number of statistical results of the cutting ring scale permeability coefficients. Setting the top layer of the model as a constant head according to the principle of a field water seepage test, wherein the head value is 0 m; the inner ring and the outer ring of the bottom layer of the model are also provided with constant water heads, and the water head value is equal to the distance from the top layer of the model to the bottom layer so as to ensure that the average water flow gradient from the bottom layer to the top layer is 1. The size of the cube and the magnitude of the permeability coefficient it represents have a significant impact on the simulation results. And (3) verifying by combining the scale effect of the permeability coefficient and using the result of a field double-ring permeability test to determine the proper subdivision size of the cube.
And 4, amplifying the simulation of the field double-ring water seepage test to a large scale for simulation, and combining the change rule, anisotropy and heterogeneity of the permeability coefficient of the landfill soil body on the cutting ring scale in space to obtain the distribution of the large-scale permeability coefficient.
It should be noted that the simulation of the field double-ring water seepage test is amplified to a large-scale simulation, the top layer and the bottom layer are respectively set as fixed water head boundaries, and the water head difference is equal to the length of a vertical path through which water flows from the bottom layer to the top layer.
Further, the method for determining the large-scale permeability coefficient of the high fill soil provided by the embodiment of the invention further comprises the following steps:
(1) a double-ring water seepage test simulation model is established, a square grid is adopted in space subdivision, the top layer of the simulation model is set to be a constant head, the head value is 0m, the range of an inner ring and an outer ring of the bottom layer of the simulation model is also set to be the constant head, and the head value is equal to the distance from the top layer to the bottom layer of the simulation model.
(2) And (3) selecting a certain permeability coefficient representative value according to a scale effect principle, calculating permeability coefficient values obtained by different random distributions under different subdivision scales according to an isotropic medium, comparing the permeability coefficient values with an actual permeability coefficient value of a field double-ring water seepage test, and selecting a proper subdivision size.
(3) And analyzing the sensitivity of the large-scale equivalent permeability coefficient calculation result to different permeability coefficient representative value numbers and anisotropies on the basis of the determined subdivision size.
It should be noted that, on the basis of the indoor penetration test, a certain penetration coefficient value distribution scheme is selected for the subdivision grid, the condition simulation method is used for carrying out simulation on the double-ring penetration test in combination with the scale effect, the field double-ring penetration test result is used for verification, the subdivision size of the model is determined, and the sensitivity of different schemes of the penetration coefficient value selected by the subdivision grid is analyzed.
On the basis of the method, the simulation of the field double-ring water seepage test is amplified to a large scale for simulation, and the distribution of the large-scale permeability coefficient is obtained by combining the change rule, anisotropy and heterogeneity of the permeability coefficient of the landfill soil body in the space on the cutting ring scale; the method specifically comprises the following steps:
(1) on the basis of the determined subdivision size, selecting a certain representative value number, gradually amplifying the simulation range according to isotropic media, calculating permeability coefficients under different random distributions under each simulation range, and determining the simulation range value when the permeability coefficient value tends to be stable along with the increase of the simulation range as the simulation range of the large-scale permeability coefficient.
(2) And analyzing the sensitivity of the large-scale equivalent permeability coefficient calculation result to the number of the permeability coefficient representative values, and determining the number of the appropriate representative values.
(3) And analyzing the sensitivity of the large-scale equivalent permeability coefficient calculation result to anisotropy, and determining the large-scale permeability coefficient value of the tested ring cutter scale permeability coefficient under a large sample.
(4) And determining the distribution of the large-scale permeability coefficient according to the relation between the sample and the population.
On the basis of the determined subdivision size, selecting a certain permeability coefficient value distribution scheme for the subdivision grids, gradually enlarging the simulation range, carrying out simulation on the water seepage of the large-scale landfill until the equivalent permeability coefficient in the simulation range tends to be stable, and determining the simulation range corresponding to the large-scale permeability coefficient; and analyzing the sensitivity of different schemes of the permeability coefficient values selected by the subdivision grids on the basis of the determined subdivision scale, and finally determining the distribution of the large-scale permeability coefficients by combining the change rule, anisotropy and heterogeneity of the cutting ring scale permeability coefficients in space.
Example (b):
taking a valley of the loess area as an example, the top loess is cut and filled into the ditch to become a flat ground. The filling process is carried out layer by layer, the filling height of each layer is about 1m, and the maximum filling height is about 90m, so that the high filling soil body is generated. The method comprises the following specific steps:
(1) along with the sampling of the high fill soil body in the construction process, the fill soil body is sampled, and the distribution of sampling points is shown in figure 2. 2-3 soil samples are sampled at each sampling point, and the soil samples are brought back indoors and subjected to variable head permeation experiments by a T-55 type permeameter to obtain 133 groups of permeation coefficient values, wherein a vertical permeation coefficient group is 66, and a horizontal permeation coefficient group is 67.
(2) And (4) carrying out statistical analysis on the permeability coefficient of the landfill soil cutting ring scale.
In order to analyze the anisotropy and the heterogeneity of the landfill soil, the vertical permeability coefficient and the horizontal permeability coefficient measured by two samples at the same sampling position and the permeability coefficients in two same directions are compared, and the results are shown in fig. 3 and fig. 4 respectively, so that the landfill soil is very large in heterogeneity and very strong in randomness, and the permeability coefficients obtained through a variable water head experiment at individual points are difficult to calculate out the permeability coefficients in a large scale.
In order to further analyze the change rule of the permeability coefficient along with the construction progress and the landfill height, box line graphs of vertical permeability coefficients and horizontal permeability coefficients in different sampling times and different sampling height ranges are respectively drawn, and the box line graphs are shown in the figures 5-8. The vertical permeability coefficient and the horizontal permeability coefficient have no obvious change rule along with the change of the sampling times and the landfill height, so that the vertical permeability coefficient and the horizontal permeability coefficient can be uniformly analyzed as a whole.
Statistical analysis was performed on the vertical and horizontal permeability coefficients of all the landfill samples, respectively, as shown in table 1 and fig. 9-10. As can be seen from the tables and figures, the vertical and horizontal permeability coefficients are distributed substantially uniformly. For further analysis, the cumulative frequency of permeability coefficients is plotted on a logarithmic axis, see FIG. 11. It can be seen from the figure that the frequency distributions of the vertical permeability coefficient and the horizontal permeability coefficient substantially coincide.
TABLE 1 statistical table of permeability coefficients (unit: m/d)
| Statistical terms | Vertical permeability coefficient | Horizontal permeability coefficient |
| Average | 0.0317 | 0.0322 |
| Standard error of | 0.0042 | 0.0045 |
| Median number | 0.02 | 0.0243 |
| Standard deviation of | 0.0338 | 0.0368 |
| Variance (variance) | 0.0011 | 0.0014 |
| Kurtosis | 0.70 | 3.73 |
| Deflection degree | 1.25 | 1.84 |
| Region(s) | 0.129 | 0.1716 |
| Minimum value | 0.00031 | 0.0003 |
| Maximum value | 0.1293 | 0.1719 |
| Number of observations | 66 | 67 |
| Confidence (95.0%) | 0.0083 | 0.009 |
(3) A field double-ring water seepage test is also carried out in the landfill area. The height of the water seepage ring is 25cm, the diameter of the outer ring is 50cm, and the diameter of the inner ring is 25 cm. The obtained permeability coefficient results measured by the field 5 groups of landfill area water seepage tests are respectively 0.030, 0.041, 0.048 and 0.051 m/d.
(4) Simulation of field double-ring water seepage test
Selecting a middle point in each 10% frequency range as a representative value, and performing simulation on a field double-ring water seepage test by using a Visual Modflow method by using a condition simulation method. In order not to influence the boundary, the plane range is selected to be 3-4.5 m, the vertical range is selected to be 0.4-0.45 m, and the models are all split into cubes. Each cube has a permeability coefficient value of one. The permeability coefficients are distributed in each cube by independent equal probability random distribution, and the permeability coefficients of one cube can be different in different implementations (random distribution).
Because the distance between two soil samples at the same sampling position is within 15cm, the test results of the permeability coefficients still have great difference, and therefore the side lengths of the squares of the model subdivision are selected to be 7.5, 7.0, 6.5 and 6.0cm for simulation calculation respectively. Meanwhile, the value of the permeability coefficient is calculated according to the corresponding size and the scale effect principle, and the calculation result is shown in table 2.
TABLE 2 values of different measured dimensional permeability coefficients (unit: m/d)
Permeability coefficients of corresponding sizes are assigned to each cube in the model respectively in a manner of isotropic equal probability random independent distribution, as shown in fig. 12. Setting the top layer of the model as a constant head, wherein the head value is 0 m; the inner ring and the outer ring of the bottom layer of the model are also provided with constant water heads, and the water head value is equal to the distance from the top layer of the model to the bottom layer, as shown in figure 13. The initial head of the model was set to 0 m.
The water quantity entering the model from the bottom layer inner ring constant head boundary in unit time can be obtained through simulation calculation. The same as the calculation principle of the field permeability coefficient, the ratio of the water amount to the inner ring area is the equivalent permeability coefficient of the simulated soil layer in the inner ring range, and the calculation result is shown in fig. 14. Compared with a field double-ring water seepage test, the simulation result is closest to the field water seepage test result when the side length of the subdivision of the cube is 7.0 cm.
(5) Simulated sensitivity analysis of bicyclic water penetration test
In order to analyze the sensitivity of the permeability coefficient to anisotropy, on the basis of the model of the subdivision size of 7.0cm, the 10 representative values are also selected, the vertical permeability coefficient is kept unchanged, and different combinations are obtained by randomly sequencing the horizontal permeability coefficient. Comparative analysis the calculated permeability coefficient values for different vertical and horizontal permeability coefficient combinations under the same random distribution are shown in fig. 15. And obtaining the water seepage test by simulating a field double-ring water seepage test, and calculating the water seepage test according to an isotropic medium.
In order to analyze the sensitivity of the permeability coefficient to the number of representative values, 5, 10, and 20 representative values were selected by the same method based on the above-described model of the 7.0cm division size, and the calculation results of the permeability coefficient were compared and analyzed based on the same random distribution, as shown in fig. 16. When the simulated double-ring water seepage test is obtained, the number of the selected representative values has little influence on the result.
(6) Calculation of large scale permeability coefficient
By simulating a field double-ring water seepage test, the practical situation of the field can be reflected most when the size of a cube grid is cut into 7 cm. Firstly, selecting the 10 representative values, and simulating cubes with the simulation ranges of 0.7 m, 2.1m and 3.5m respectively, namely, a plane is divided into 100 meshes, 900 meshes and 2500 meshes respectively, a vertical direction is divided into 10 layers, 30 layers and 50 layers respectively, the top layer and the bottom layer are set as constant water head boundaries respectively, and the water head difference is equal to the length of a vertical path through which water flows from the bottom layer to the top layer. For each of the subdivided small cubes, according to isotropic media, equal probability independent random assignment is performed on each cube by using 10 selected representative values, and statistical analysis is performed on permeability coefficients calculated under different probability distributions, as shown in fig. 17. It was found that the simulation results at the simulation ranges of 2.1m and 3.5m can substantially represent the permeability coefficient of a large scale. The subsequent studies were all conducted within a 3.5m simulation range.
In order to analyze the influence of the number of representative values on the simulation result, 5, 10 and 20 representative values are selected respectively by the same method, the simulation is carried out by using a model with the simulation range of 3.5m and the subdivision size of 7cm, and the result is compared and analyzed, which is shown in fig. 18. The calculation results of the permeability coefficients under different quantity representative values have certain difference, but the difference is not large, and the relative difference is about 9%. Since the larger the number of representative values, the closer the actual situation, the larger the calculation amount, the more the calculation amount should be considered, and therefore, the subsequent analysis selects 20 representative values.
In order to analyze the influence of anisotropy on the large-scale permeability coefficient, on the basis of the model, the 20 representative values are selected for the vertical permeability coefficient and the horizontal permeability coefficient, the vertical permeability coefficient is kept unchanged, the horizontal permeability coefficients are randomly arranged to obtain different combinations, the distribution conditions of the permeability coefficients under different combinations are analyzed, and the results are shown in fig. 19. The results of the equivalent permeability coefficients obtained under different combinations of the vertical permeability coefficient and the horizontal permeability coefficient have certain difference, but the difference is not large, and the relative difference is about 10%. The average of the equivalent permeability coefficients obtained for the various combinations and distributions was 0.0221 m/d.
The calculation of the large-scale permeability coefficient is carried out on a certain soil sample analysis nodeOn the basis of the results, the average values in different ranges are selected as representative values for statistical analysis. However, the relationship between a certain number of samples and a large-scale stratum belongs to a sample and a population, and the mean value of the samples is not completely equivalent to the mean value of the population. According to the central limit theorem, when the sample volume is sufficiently large (typically required to be greater than or equal to 30), the mean value
The sampling distribution of (a) is approximately subject to a normal distribution, and the confidence interval of the overall mean can be approximated by:
in the formula
Is the mean of the samples, α is the critical probability or confidence level at which the confidence is (1- α), Zα/2Is a critical value below the significant level alpha. And (4) according to the results of the statistical analysis of the vertical permeability coefficient and the horizontal permeability coefficient, looking up a standard normal distribution table to obtain intervals of the overall mean values under different confidence degrees. The average value of the permeability coefficient results obtained by the large-sample indoor variable water head permeability experiment and the field large-scale permeability coefficient are approximately regarded as a direct proportion relation, so that the distribution of the large-scale permeability coefficient under different accumulative frequencies can be calculated, and the result is shown in a figure 20.
The above disclosure is only a few specific embodiments of the present invention, and those skilled in the art can make various modifications and variations of the present invention without departing from the spirit and scope of the present invention, and it is intended that the present invention encompass these modifications and variations as well as others within the scope of the appended claims and their equivalents.
Claims (1)
1. A method for determining the large-scale permeability coefficient of a high fill soil body is characterized by comprising the following steps:
sampling at different horizontal plane positions and vertical positions of a high fill soil body, and determining the vertical and transverse permeability coefficients of the soil sample by using a permeameter method to obtain the spatial change rule, anisotropy and heterogeneity of the permeability coefficient of the fill soil body on the cutting-ring scale;
carrying out field double-ring water seepage tests at different positions of a high-fill soil body to obtain the permeability coefficient value on the cutting ring scale;
according to the value of the permeability coefficient on the cutting ring scale and in combination with the scale effect principle, carrying out simulation on a field double-ring water seepage test;
the simulation of the field double-ring water seepage test is amplified to a large scale for simulation, and the distribution of the large-scale permeability coefficient is obtained by combining the change rule, anisotropy and heterogeneity of the permeability coefficient of the landfill soil body on the cutting ring scale in space;
further comprising:
establishing a double-ring water seepage test simulation model, adopting a square grid for space subdivision, setting the top layer of the simulation model as a constant head, setting the head value as 0m, setting the range of an inner ring and an outer ring of the bottom layer of the simulation model as the constant head, and setting the head value equal to the distance from the top layer to the bottom layer of the simulation model;
selecting a certain permeability coefficient representative value according to a scale effect principle, calculating permeability coefficient values obtained by different random distributions under different subdivision scales according to an isotropic medium, comparing the permeability coefficient values with an actual permeability coefficient value of a field double-ring water seepage test, and selecting a proper subdivision size;
on the basis of the determined subdivision size, analyzing the sensitivity of the large-scale equivalent permeability coefficient calculation result to different permeability coefficient representative value numbers and anisotropies;
the simulation of the field double-ring water seepage test is amplified to a large scale for simulation, and the distribution of the large-scale permeability coefficient is obtained by combining the change rule, anisotropy and heterogeneity of the permeability coefficient of the landfill soil body in the ring cutter scale in space; the method comprises the following steps:
on the basis of the determined subdivision size, selecting a certain representative value number, gradually amplifying the simulation range according to an isotropic medium, calculating permeability coefficients under different random distributions under each simulation range, and determining the simulation range value when the permeability coefficient value tends to be stable along with the increase of the simulation range as the simulation range of the large-scale permeability coefficient;
analyzing the sensitivity of the large-scale equivalent permeability coefficient calculation result to the number of the permeability coefficient representative values, and determining the number of the appropriate representative values;
analyzing the sensitivity of the large-scale equivalent permeability coefficient calculation result to anisotropy, and determining the large-scale permeability coefficient value of the tested ring cutter scale permeability coefficient large sample;
and determining the distribution of the large-scale permeability coefficient according to the relation between the sample and the population.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810613729.4A CN108982317B (en) | 2018-06-14 | 2018-06-14 | Method for determining large-scale permeability coefficient of high fill soil body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810613729.4A CN108982317B (en) | 2018-06-14 | 2018-06-14 | Method for determining large-scale permeability coefficient of high fill soil body |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108982317A CN108982317A (en) | 2018-12-11 |
| CN108982317B true CN108982317B (en) | 2021-01-29 |
Family
ID=64540459
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810613729.4A Expired - Fee Related CN108982317B (en) | 2018-06-14 | 2018-06-14 | Method for determining large-scale permeability coefficient of high fill soil body |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108982317B (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105631078B (en) * | 2014-11-07 | 2019-01-18 | 中国石油化工股份有限公司 | The method for numerical simulation of Natural fractures system self-adapting medium |
| CN106202746B (en) * | 2016-07-14 | 2019-04-16 | 南京大学 | Simulate the Yeh- multi-level finite element modeling method of Water in Porous Medium stream Darcy velocity |
| CN106884442B (en) * | 2017-04-25 | 2019-07-23 | 西安理工大学 | A kind of implementation method of cheuch shape high fill foundation multi- scenarios method monitoring system |
-
2018
- 2018-06-14 CN CN201810613729.4A patent/CN108982317B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN108982317A (en) | 2018-12-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110276160B (en) | Three-dimensional space distribution simulation method for organic carbon in soil in plain area | |
| Rezaei et al. | The relevance of in-situ and laboratory characterization of sandy soil hydraulic properties for soil water simulations | |
| Zhang et al. | Rainfall-runoff modelling in a catchment with a complex groundwater flow system: application of the Representative Elementary Watershed (REW) approach | |
| CN108876918B (en) | High fill loess body settlement deformation prediction method | |
| Bhandari et al. | 2D unsteady flow routing and flood inundation mapping for lower region of Brazos River watershed | |
| CN107966732A (en) | The seismic properties change rate acquiring method being oriented to based on space structure | |
| CN110244363B (en) | Method for predicting fracture-cavity reservoir resource amount | |
| CN108303512B (en) | Method for in-situ testing soil-water characteristic curve | |
| CN108427741B (en) | DEM relative error evaluation method based on large number of high-precision control points | |
| CN110501757A (en) | The three-dimensional point-by-point well depth designing method of point-line-surface | |
| CN113780741A (en) | Landslide risk evaluation method and system based on slope characteristics and storage medium | |
| CN108982317B (en) | Method for determining large-scale permeability coefficient of high fill soil body | |
| CN113484210A (en) | On-site scale test determination method for dispersity of strongly weathered layer | |
| CN113158315A (en) | Rock-soil body parameter three-dimensional non-stationary condition random field modeling method based on static cone penetration data | |
| Rifai et al. | Continuous monitoring of fluvial dike breaching by a laser profilometry technique | |
| CN114236624B (en) | Method and system for estimating fracturing modification space volume based on electromagnetic method | |
| Apaydin et al. | Determination of the drainage basin characteristics using vector GIS | |
| Tombul | Mapping field surface soil moisture for hydrological modeling | |
| US20210349238A1 (en) | Systems and methods for generating vertical and lateral heterogeneity indices of reservoirs | |
| Matano et al. | Thickness of pyroclastic cover beds: the case study of Mount Albino (Campania region, southern Italy) | |
| Yu et al. | Detection and volume estimation of mining subsidence based on multi-temporal LiDAR data | |
| Schwindt | Permafrost in ventilated talus slopes below the timberline-A multi-methodological study on the ground thermal regime and its impact on the temporal variability and spatial heterogeneity of permafrost at three sites in the Swiss Alps | |
| JP4488821B2 (en) | Permeability test evaluation system and permeation test evaluation method | |
| Iwanek | Numerical Investigations of moisture distribution in a selected anisotropic soil medium | |
| dos Santos et al. | Spatial uncertainty analysis of the saturated soil hydraulic conductivity in a subtropical watershed |
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 | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20210129 |