METHOD FOR DETERMINING HYDRAULIC PARAMETERS AND WATER INFLOW IN EROSION STAGE OF GRAVEL SOIL

Abstract

The invention discloses method for determining hydraulic parameters and water inflow in the erosion stage of gravel soil, comprising: calculate the soil particle content P and the soil porosity n of each grade of particle size a, and draw the PSD curve of each grade of particle size and the soil particle content P of each grade of particle size and the PSD curve cluster of each grade of particle size and the soil particle content P of each grade of particle size in each erosion stage; calculate the equivalent diameter D.sub.h of the soil particle, and calculate the minimum equivalent pore diameter d.sub.0 of the soil particle; calculate the critical hydraulic gradient i.sub.cr of particle erosion at each stage; calculate the permeability coefficient k.sub.h; calculate the seepage flow velocity ν and the total seepage flow Q.

Claims

1. A method for determining hydraulic parameters and water inflow in the erosion stage of gravel soil, comprising the following steps: calculate the soil particle content P and the soil porosity n of each grade of particle size according to the principle of graded erosion, and draw the PSD curve of each grade of particle size and the soil particle content P of each grade of particle size and the PSD curve cluster of each grade of particle size and the soil particle content P of each grade of particle size in each erosion stage; calculate the equivalent diameter D.sub.h of the soil particle according to the average particle diameter D.sub.j in a certain two particle size range in the PSD curve, and calculate the minimum equivalent pore diameter d.sub.0 of the soil particle according to the equivalent diameter D.sub.h; calculate the critical hydraulic gradient i.sub.cr of particle erosion at each stage according to the soil particle content P of each grade of particle size; calculate the permeability coefficient k.sub.h according to the soil porosity n and the geometric parameter values of the soil particle in the PSD curve cluster; calculate the seepage flow velocity ν and the total seepage flow Q according to the permeability coefficient k.sub.h.

2. The method for determining hydraulic parameters and water inflow in the erosion stage of gravel soil according to claim 1, wherein the method for calculating the soil particle content P and the soil porosity n of each grade of particle size is: calculate the soil particle content P.sub.j.sup.(i) of the j-th grade of particle size in the (1+1) state and the soil porosity n.sup.(i+1) updated to the (1+1) state according to the following formula (1): $\begin{array}{cc}{P}_j^{\left(i+1\right)}=\{\begin{array}{cc}\frac{P_j^{\left(i\right)}-S}{100-S}\times 100\%& \left(S\le P_j^{\left(i\right)}<P_x\right)\\ 0& \left(P_j^{\left(i\right)}<S<P_x\right)\end{array}& \left(1a\right)\\ n^{\left(i+1\right)}=n^{\left(i\right)}+\left(1-n^{\left(i\right)}\right)S& \left(1b\right)\end{array}$ in the formula, P.sub.j.sup.(i) is the soil particle content of the j-th grade of particle size in the state (i); n.sup.i is the soil porosity in the state (i); S is the degree of osmotic erosion, that is, the percentage of the mass of the soil particle smaller than a certain size that are washed away and eroded to the mass of the original soil particle; P.sub.x is the content of fine particles, that is, the percentage of soil particles loss in the total soil mass.

3. The method for determining hydraulic parameters and water inflow in the erosion stage of gravel soil according to claim 1, wherein the method for calculating the minimum equivalent pore diameter d.sub.0 of the soil particle according to the equivalent diameter D.sub.h is: calculate the equivalent diameter D.sub.h of the soil particle according to the following formula (2): $\begin{array}{cc}{D}_h=\frac{1}{\Sigma \frac{\Delta S_j}{D_j}}& \left(2\right)\end{array}$ calculate the minimum equivalent pore diameter d.sub.0 according to the following formula (3): $\begin{array}{cc}{d}_0=2.67\frac{n}{1-n}\frac{D_h}{\alpha }& \left(3\right)\end{array}$ in the formula, D.sub.j is the average particle size of the soil particle with a size grade between j.sub.1 and j.sub.2; ΔS.sub.j is the ratio of the weight of the j-th grade of particle size to the total weight of the sample; n is the porosity; α is the shape factor of the particle.

4. The method for determining hydraulic parameters and water inflow in the erosion stage of gravel soil according to claim 1, wherein the method for calculating the critical hydraulic gradient i.sub.cr of particle erosion at each stage is: calculate the critical hydraulic gradient (i.sub.cr) j of the j-th grade of particle erosion according to the following formula (4): $\begin{array}{cc}{\left(i_{\alpha }\right)}_j=\frac{0.85d_j}{P_j{d}_{85}}\left(1-n\right)\left(s-1\right)& \left(4\right)\end{array}$ in the formula, (i.sub.cr) j is the critical hydraulic gradient of the j-th grade of particle erosion; s is the relative density, that is, the density of the overall soil density relative to the density of the water body; d.sub.85 is the particle size of the particle whose loss of soil particles accounts for 85% of the total soil mass; d.sub.j is the j-th grade of particle size that is eroded from the soil; p.sub.j is the particle content of the j-th grade of particle size.

5. The method for determining hydraulic parameters and water inflow in the erosion stage of gravel soil according to claim 1, wherein the method for calculating the permeability coefficient k.sub.h is: calculate the permeability coefficient k.sub.h according to the following formula (5): $\begin{array}{cc}{k}_k=3.5\times {10}^{-4}\frac{e^3}{1+e}\frac{{\gamma }_w}{{\mu }_w}{d}_{10}^{2.32}{C}_{\alpha }^{0.6}& \left(5\right)\end{array}$ in the formula, e is the void ratio, calculated from the soil porosity e=n/(1−n); μ.sub.w is the dynamic viscosity coefficient of water; γ.sub.w is the weight of water; d.sub.10 is the particle size of the particle whose loss of soil particles accounts for 10% of the total soil mass; C.sub.u is the coefficient of nonuniformity.

6. The method for determining hydraulic parameters and water inflow in the erosion stage of gravel soil according to claim 1, wherein the method for calculating the seepage flow velocity ν and the total seepage flow Q is: calculate the seepage velocity ν of the soil particle according to the following formula (6):
v=K.sub.h.Math.i.sub.cr  (6) calculate the total seepage flow Q of the soil particle according to the following formula (7):
Q=n.Math.ν.Math.A  (7) in the formula, ν is the seepage velocity; i.sub.cr is the critical hydraulic gradient; Q is the total seepage flow; A is the area; n is the soil porosity.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to explain the embodiments of the invention or the technical solutions in the prior art more clearly, the drawings that need to be used in the description of the embodiments or the prior art will be briefly introduced hereinafter. Obviously, the drawings in the following description are only some embodiments of the invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] FIG. 1 is a flow chart of the method according to the invention;

[0033] FIG. 2 is a PSD curve of the particle size distribution of the soil particle of three different soil types according to the invention;

[0034] FIG. 3 is a PSD curve of each grade of particle size and the soil particle content P of each grade of particle size according to the invention;

[0035] FIG. 4 is a PSD curve cluster of the gravel soil S2 according to the invention at each erosion stage;

[0036] FIG. 5 is a PSD curve cluster of the gravel soil S3 according to the invention at each erosion stage;

[0037] FIG. 6 is a block diagram of calculation of critical hydraulic gradient in the process of particle graded erosion according to the invention;

[0038] FIG. 7 is a diagram showing the relationship between the critical hydraulic gradient and each grade of particle size of gravel soil according to the invention;

[0039] FIG. 8 is a diagram showing the relationship between the critical hydraulic gradient of gravel soil and the percentage of particles according to the invention;

[0040] FIG. 9 is a diagram showing the relationship between geometric parameters and permeability coefficient of the gravel soil S2 under different erosion degrees according to the invention;

[0041] FIG. 10 is a diagram showing the relationship between geometric parameters and permeability coefficient of the gravel soil S3 under different erosion degrees according to the invention;

[0042] FIG. 11 is a diagram showing the change of the seepage flow velocity ν and the water inflow Q in the low value area of the critical hydraulic gradient i.sub.cr at different stages according to the invention;

[0043] FIG. 12 is a diagram showing the change of the seepage flow velocity ν and the water inflow Q in the high value area of the critical hydraulic gradient i.sub.cr at different stages according to the invention;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] The technical solutions in the embodiments of the invention will be described clearly and completely hereinafter with reference to the drawings 1 to 11 in the embodiments of the invention. Obviously, the described embodiments are only a part of the embodiments of the invention, rather than all the embodiments. Based on the embodiments of the invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall all fall within the protection scope of the invention.

[0045] The invention provides a method for determining hydraulic parameters and water inflow in the erosion stage of gravel soil.

[0046] Before implementing the method, it is necessary to draw the PSD curve of the particle size distribution of the three different soil types as shown in FIG. 2 based on the survey data of the main construction site containing gravel soil, and obtain the geometric parameters of various gravel soils from the PSD curve. Geometric parameters include d.sub.10, d.sub.30, d.sub.60, d.sub.70, d.sub.85, d.sub.q, wherein oho is the particle size of the particle whose loss of soil particles accounts for 10% of the total soil mass; d.sub.30, d.sub.60, d.sub.70, d.sub.85 have the same meaning with d.sub.10, and d.sub.q is the dividing diameter of the coarse and fine particles of the two types of gravel soil. Geometric parameters are substituted into

[00006]$C_{\alpha }=\frac{d_{30}}{d_{60}}$

to calculate the uneven coefficient C.sub.u of gravel soil, substituted into

[00007]$C_{\alpha }=\frac{d_n^2}{d_{30}\times d_{60}}$

to calculate the curvature coefficient C.sub.c, and substituted into d.sub.q=√{square root over (d.sub.10d.sub.10)} to calculate d.sub.q, so as to determine the boundary diameter of coarse and fine particles d.sub.q, and obtain the corresponding fine particle content P.sub.x in FIG. 2.

TABLE-US-00001 TABLE 1 Geometric Parameters of Three Different Soil Types Based On the PSD Curve Coefficient of Curvature Soil Nonuniformity Coefficient Various Geometric Parameters (mm) Type Names (C.sub.u) (C.sub.c) d.sub.q d.sub.10 d.sub.30 d.sub.60 d.sub.70 d.sub.15 d.sub.85 Sand Fine Sand S1 3.77 0.77 0.16 0.065 0.11 0.245 0.41 0.08 0.82 Gravel Soil S2 80.9 7.86 2.3 0.23 5.8 18.6 23.0 0.58 28.9 (Pebble*) Gravel Gravel Soil S3 Soil (Containing 1141.3 0.047 0.57 0.015 0.11 17.1 21.6 0.022 28.3 Silty Clay Pebbles*)

[0047] Calculate the soil particle content P and the soil porosity n of each grade of particle size according to the principle of graded erosion, as shown in FIG. 4 and FIG. 5, and draw the PSD curve of each grade of particle size according to the soil particle content P in each grade and the PSD curve cluster of the two gravel soils moving to the right under the graded erosion condition; each curve corresponds to the fine particles being eroded away step by step, and the composition of the soil particles gradually becomes simplified and single, and finally close to the new soil gradation of pebbles; from the comparison of the gradation curves of the two gravel soils (FIG. 3) and the moving PSD curve clusters (FIGS. 4 and 5), it can be seen that the initial state of the gravel soil S2 (the PSD curve with 0% erosion degree) is equivalent to the fifth grade erosion state of S3 (the PSD curve with 25% erosion degree). Therefore, it can be seen that the two gravel soils have similar sources of sedimentary materials, and the component structure of the former is the phased product of the latter after long-term hydraulic erosion.

[0048] calculate the soil particle content P and the soil porosity n of each grade of particle size according to the following formula (1):

[00008]$\begin{array}{cc}{P}_j^{\left(i+1\right)}=\{\begin{array}{cc}\frac{P_j^{\left(i\right)}-S}{100-S}\times 100\%& \left(S\le P_j^{\left(i\right)}<P_x\right)\\ 0& \left(P_j^{\left(i\right)}<S<P_x\right)\end{array}& \left(1a\right)\\ n^{\left(i+1\right)}=n^{\left(i\right)}+\left(1-n^{\left(i\right)}\right)S& \left(1b\right)\end{array}$

[0049] As shown in FIG. 3, draw the PSD curve of each grade of particle size according to the soil particle content P in each grade; obtain the average particle diameter D.sub.j between the size grade from j.sub.1 to j.sub.2 from the figure, determine the equivalent diameter D.sub.h of the soil particle according to the average particle diameter D.sub.1, and calculate the minimum equivalent pore diameter d.sub.0 according to the equivalent diameter D.sub.h.

[0050] calculate the equivalent diameter D.sub.h of the soil particle according to the following formula (2):

[00009]$\begin{array}{cc}{D}_h=\frac{1}{\Sigma \frac{\Delta S_j}{D_j}}& \left(2\right)\end{array}$

[0051] calculate the minimum equivalent pore diameter d.sub.0 according to the following formula (3):

[00010]$\begin{array}{cc}{d}_0=2.67\frac{n}{1-n}\frac{D_h}{\alpha }& \left(3\right)\end{array}$

[0052] calculate the critical hydraulic gradient i.sub.cr of particle erosion at each stage according to the soil particle content P;

[0053] calculate the critical hydraulic gradient i.sub.cr of particle erosion at each stage according to the following formula (4):

[00011]$\begin{array}{cc}{\left(i_{\alpha }\right)}_j=\frac{0.85d_j}{P_j{d}_{85}}\left(1-n\right)\left(s-1\right)& \left(4\right)\end{array}$

[0054] As shown in FIG. 6, through alternate loop iterations between P.sub.j.sup.(i) and p.sub.j.sup.(i+1), it is determined whether the continuous erosion condition is met after each iteration at the same time, so as to achieve a series of updated PSD curve clusters and the critical hydraulic gradient i.sub.cr of particle erosion at each stage.

[0055] Draw a diagram showing the relationship between the critical hydraulic gradient and each grade of particle size of gravel soil as shown in FIG. 7 according to the critical hydraulic gradient i.sub.cr of particle erosion at each stage; in FIG. 7, the critical hydraulic gradient i.sub.cr of the gravel soil S2 is greater than the critical hydraulic gradient i.sub.cr of S3; this is due to its small particle size range and large particle size, and the movement of soil particles requires greater permeability; in addition, under 25% erosion degree, the PSD curve of the gravel soil S3 is taken as the critical hydraulic gradient i.sub.cr calculated by the new soil type as the change of the particle size, which is very similar to the initial critical hydraulic gradient i.sub.cr change of the gravel soil S2, and the Pearson correlation coefficient reaches 90.4%. It can be further confirmed that the two gravel soil sedimentary materials have the same homology, and the former is the phased product of the latter after long-term hydraulic erosion.

[0056] Draw a diagram showing the relationship between the critical hydraulic gradient of gravel soil and the percentage of particles as shown in FIG. 8 according to the critical hydraulic gradient i.sub.cr of particle erosion at each stage; in the figure, the gravel soil S2 uses sand as the main component of erodible fine particles; while S3 uses powder and a small amount of clay as the main component of erodible fine particles, and the amount of sand that can be eroded is relatively small.

[0057] Calculate the permeability coefficient k.sub.h according to the geometric parameter values of each soil type and the minimum equivalent pore diameter do.

[0058] The minimum equivalent pore diameter d.sub.0 is calculated by formula (2) and formula (3) and the geometric parameters are obtained directly from the PSD curve, and then substituted into formula (5) to obtain the permeability coefficient k.sub.h of gravel soil:

[00012]$\begin{array}{cc}{k}_k=3.5\times {10}^{-4}\frac{e^3}{1+e}\frac{{\gamma }_w}{{\mu }_w}{d}_{10}^{2.32}{C}_{\alpha }^{0.6}& \left(5\right)\end{array}$

[0059] FIG. 9 is a diagram showing the relationship between geometric parameters and permeability coefficient of the gravel soil S2 under different erosion degrees; the data is read from the moving PSD curve or the geometric parameters calculated by the formula. For example, the particle size d.sub.10 and d.sub.15 can be read directly, and the pore diameter d.sub.0 needs to be calculated by formula (3). It can be seen from FIG. 9 that taking into account the influence of the porosity n value (0.20-0.47), the filling area represents the range of geometric parameters and permeability coefficient under the influence of the porosity n value. As the erosion degree S increases, when S=20%, the geometric parameters or permeability coefficients will tend to be consistent.

[0060] FIG. 10 is a diagram showing the relationship between geometric parameters and permeability coefficient of the gravel soil S3 under different erosion degrees; regardless of whether the effective particle size d.sub.10 or d.sub.15 is used, the value of the permeability coefficient is in the case of the erosion degree S<15%, and the calculation result is consistent with the result of the classical hydraulic formula. Taking into account the influence of the coefficient of nonuniformity C.sub.u in the formula (5), the permeability varies widely in the order of magnitude, and the influence of fine particles is highlighted. For example, the permeability coefficient of the gravel soil S3 ranges from 10.sup.−6 to 10 cm/s, which can cover the range of permeability coefficient from silt to gravel.

[0061] Calculate seepage flow velocity ν and total seepage flow Q according to Darcy law and the calculation formula of soil seepage flow rate;

[0062] calculate the seepage velocity ν of the soil particle according to the following formula (6):

v=K.sub.h.Math.i.sub.cr  (6)

[0063] calculate the total seepage flow Q of the soil particle according to the following formula (7):

Q=n.Math.ν.Math.A  (7)

[0064] According to FIG. 11 and FIG. 12, as shown in Table 2, the hydraulic erosion properties of gravel soil at each erosion stage are obtained.

[0065] In the percolation stage (S<5%), the critical hydraulic gradient is i.sub.cr<0.01, the permeation velocity ν is less than 5.0×10.sup.−4 cm/s, and the erodible particles are fine powder particles with a diameter of less than 0.01 mm;

[0066] In the fine-grained erosion stage (5% S30%), the critical hydraulic gradient i.sub.cr is 0.01-0.13, and the seepage velocity ν=5.0×10.sup.−4−4.0×10.sup.−1 cm/s; the erodible particles range from powder particles to fine sand particles with a diameter of 0.01-0.1 mm;

[0067] In the coarse-grained erosion stage (30% SS40%), the critical hydraulic gradient i.sub.cr is 0.13-0.50, and the seepage velocity ν=0.4-2.8 cm/s; the erodible particles are fine to medium coarse sand particles with a diameter of 0.1-0.57 mm;

[0068] In the water inrush or water logging stage (S is not taken into account), the critical hydraulic gradient i.sub.cr is 0.50-0.89, and the seepage velocity is ν>2.8 cm/s.

TABLE-US-00002 TABLE 2 Parameters and Value Ranges of Gravel Soil Erosion at Each Stage Water Inrush or Water Range of Logging Parameter Stage Values for S Is Not Each Stage Percolation Fine-Grained Coarse-Grained Taken of Stage Erosion Stage Erosion Stage Into Erosion S < 5% 5% ≤ S < 30% 30% ≤ S ≤ 40% Account Critical <0.01 0.01-0.13 0.13-0.50 >0.50 Hydraulic Gradient i.sub.cr Permeability 0.05 0.05-2.97 2.97-5.6  >5.6 Coefficient k.sub.h (cm/s) Seepage <5.0 × 10.sup.−4 5.0 × 10.sup.−4 − 0.4 0.4-2.8 >2.8 Flow Velocity v (cm/s) Flow Rate <8.6 × 10.sup.−3 8.6 × 10.sup.−3 − 6.9  6.9-48.4 >48.4 Per Unit Area Q*(m.sup.3/h) Note: 1: the porosity n is 0.47, that is, the gravel soil is in a loose state; A is 1.0 m.sup.2. 2: With reference to the size of water inrush flow in domestic mines, when the flow is less than 50.0 m.sup.3/h, it is a small-scale water inrush point.

[0069] In summary, the method of the invention calculates the dynamic geometric parameters and the changed critical hydraulic gradient and permeability coefficient through the moving PSD curve under the condition of gravel soil graded erosion, and then calculates the seepage velocity and the water inflow by the Darcy formula, so as to obtain the rock and soil hydraulic characteristic parameters and the water inrush, which makes it possible to calculate the total seepage flow in the event of seepage erosion, and inversely deduce the degree of gravel soil erosion and dangerous conditions, so that corresponding measures can be taken to control and protect them, so as to avoid accidents. It is worthy of promotion.

[0070] Although the preferred embodiments of the invention have been described, however, those skilled in the art can make additional alterations and modifications to these embodiments once they learn the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all alterations and modifications falling within the scope of the invention.

[0071] Obviously, those skilled in the art can make various alterations and modifications to the invention without departing from the spirit and scope of the invention. In this way, if these alterations and modifications of the invention fall within the scope of the claims of the invention and the equivalent technologies thereof, the invention is also intended to include these alterations and modifications.