CN104318015A - Method for predicting seepage field of nodal region of earth and rockfill dam and determining infiltration side of earth and rockfill dam - Google Patents

Abstract

The invention discloses a method for predicting the seepage field of a nodal region of an earth and rockfill dam and determining the infiltration side of the earth and rockfill dam. The method includes establishing a nodal-region three-dimensional geological detailed model of an unfavorable geologic body and fractures; setting up three-dimensional seepage and computing a grid model on the basis of the three-dimensional geological detailed model; simulating numerical values of the seepage field of the earth and rockfill dam on the basis of the three-dimensional geological detailed model, dispersing by the finite volume method according to the determined continuity equation, the water and steam two-phase N-S equation, the water and steam two-phase mixing speed equation and mixing density equation, the set boundary conditions and the seepage parameters of the actual project, solving with the SIMPLE algorithm, realizing numerical simulation of the seepage field of the earth and rockfill dam on the basis of the three-dimensional geological detailed model and thereby predicting the seepage field of the nodal region of the earth and rockfill dam. Geological information can be accurately reflected, and the seepage field of the nodal region of the earth and rockfill dam can be accurately simulated. Meanwhile, the seepage field is utilized to determine the infiltration side of the earth and rockfill dam by the VOF (volume of fluid) method.

Description

Prediction earth and rockfill dam nodal region seepage field and determine the method for earth and rockfill dam dam body saturated surface

Technical field

The invention belongs to seepage field numerical simulation field in hydroelectric project, relate to the earth-rock dam seepage Numerical Simulation method based on three-dimensional detailed geological model.Specifically, relate to the construction method of the detailed geological model comprising unfavorable geologic body and crack and the earth-rock dam seepage Numerical Simulation method based on detailed geological model, and earth and rockfill dam saturated surface method for solving.

Background technology

In hydraulic engineering, the destruction of water on job facilities affects the topmost aspect of engineering safety.Wherein the effect of underground water to hydraulic engineering is not easily observed, and is just difficult to retrieve once discovery, often can bring great safety problem and economic loss to engineering ^[1].Therefore hydraulic engineering is very crucial to the prevention of underground water seepage erosion.

Earth and rockfill dam is as most widely used general in dam, world work building, and a kind of form with fastest developing speed, structure is simple, draws materials conveniently.The version that earth and rockfill dam is built a dam and material behavior, make earth and rockfill dam become in various forms of shelves water buildings, the one the closest with seepage flow relation.Seepage problems is directly connected to the stable of earth-rock works and safety, and many earth-rock works bursting or destroy, are all caused by seepage flow both at home and abroad, so it is necessary for managing sunykatuib analysis exactly to earth-rock dam seepage occasion.The present invention is the accurate problem to earth-rock dam seepage field stimulation analysis aspect under mainly solving complex geological condition.

Many employing Darcy's law analysis and solution seepage fields in Simulation of Seepage Field research both at home and abroad, or utilize the principle of temperature field and seepage field equivalence to carry out seepage calculation, application restrictive condition is many, and cannot determine the position of saturated surface effectively accurately.Earth-rock dam seepage belongs to the free seepage having saturated surface, how simple and direct, determine that the position of saturated surface is key and the difficult point of free seepage field analysis exactly.The method extensively adopted at present is finite element fixed mesh method, comprises Bathe and Khoshgoftaar ^[2]the unit seepage matrix adjustment method proposed, Desai ^[3]the residual flow method proposed, Zhang Youtian etc. ^[4,5]the modified initial flow method proposed and Jiang etc. ^[6]the variational inequality method etc. adopted, though these class methods are better to the adaptability of complex region, because saturated surface position is undetermined, need iteration to determine, finite element fixed mesh method have impact on the computational accuracy of seepage field.Meanwhile, its amount of calculation is large, easily produces iterative computation not Convergent Phenomenon.Jie etc. ^[7]propose to use mesh free Natural Element Method to solve the seepage field of band saturated surface, although this method calculates easy, precision is higher, and solution efficiency is lower and easily produce integral error.Yang Haiying ^[8], Zhong little Yan ^[9], Song Yongzhan ^[10], Zhang Yu ^[11]respectively the seepage field of the gate dam dam foundation, radial, Gravity Dam Foundation, dyke etc. is analyzed Deng once using finite volume method and fluid volume function (volume of fluid, VOF) method.But mostly carried out simplifying largely to geologic condition and dam body details in dam infiltration research at present, especially, in the dam foundation, fail to consider different rock-layers geological information, unfavorable geologic body information under complex geological condition comprehensively and ooze the impact of the various factors such as control means on seepage field; In addition, use finite volume method and VOF method to the rarely seen report of research of earth and rockfill dam 3 D complex free seepage problem.

Secondly, the simulation of osculum is the technical barrier in Simulation of Seepage Field always, and the normal method adopted has Wang Lei etc. at present ^[12]the drainage substructure proposed, Zhan etc. ^[13]propose approximate analytic solution in conjunction with finite element algorithm, Wang Enzhi ^[14]" with pipe belt hole ", " the to stitch Dai Jinglie " method proposed, Hu Jing ^[15]the air element etc. proposed.But these methods all put forward based on equivalence principle mostly, there is certain deficiency in theoretical and application aspect.

To sum up tell, the aspects such as the computing method focusing on seepage flow of research both at home and abroad and concrete engineering application.In earth-rock dam seepage simulation process, in view of complexity and the uncertainty in geologic condition and crack, be difficult to set up geology and model of fissuration accurately, therefore often compare large simplify processes to actual geologic condition, this obviously can reduce the precision of analog result greatly.In addition, in current seepage calculation, the normal method adopted is finite element method, and temperature field is equivalent to seepage field, or adopts Darcy's law to solve seepage field, and application restrictive condition is many, and cannot determine the position of saturated surface effectively accurately.Simulation for the infiltration free face of seepage with free surface adopts finite element fixed mesh method more, though the method is better to the adaptability of complex region, wait to ask owing to infiltrating free surface position, unknown in advance, need iteration to determine, finite element fixed mesh method have impact on the computational accuracy of seepage field.For this reason, the present invention proposes the method set up and comprise the nodal region three-dimensional geological refined model in unfavorable geologic body and crack, and based on the mathematical model that the earth-rock dam seepage of finite volume method and VOF method calculates, achieve the numerical simulation to earth and rockfill dam complex free seepage field.

[list of references]

[1] rich and powerful. based on the complex condition earth-rock dam seepage research [D] of advanced method for numerical simulation. Zhejiang: Zhejiang University, 2010.

[2]Bathe?K?J,Khoshgoftaar?M?R.Finite?element?free?surface?analysis?without?mesh?iteration[J].Int?J?Numer?Anal?Met,1979,3:13-22。

[3]Desai?C?S.Finite?element?residual?schemes?for?unconfined?flow[J].Int?J?Numer?Meth?Eng,1976,10:1415-1418。

[4] Zhang Youtian, Chen Ping, Wang Lei. the modified initial flow method [J] that seepage with free surface is analyzed. Journal of Hydraulic Engineering, 1988, (8): 18-26.

[5] Pan Shu comes, Wang Quanfeng, Yu's red silk. and utilize modified initial flow method to analyze the improvement [J] of seepage with free surface problem. Geotechnical Engineering journal, 2012,34 (2): 202-209.

[6]Jiang?Q?H,Ye?Z?Y,Yao?C,et?al.A?new?variational?inequality?formulation?for?unconfined?seepage?flow?through?fracture?networks[J].Sci?China?Tech?Sci,2012,55:3090-3101。

[7]Jie?Y?X,Liu?L?Z,Xu?W?J,et?al.Application?of?NEM?in?seepage?analysis?with?a?free?surface[J].Mathematics?and?Computers?in?Simulation,2013,89:23-37。

[8] Yang Haiying. adopt finite volume method to carry out the analysis of gate dam seepage flow under foundation and study [D] with seepage control measure. Xi'an: Xi'an University of Technology, 2005.

[9] Zhong little Yan. based on the seepage field numerical simulation [D] of porous media model and VOF method. Xi'an: Xi'an University of Technology, 2010.

[10] Song Yongzhan. based on concrete gravity dam seepage prevention of dam founda drainage measure analysis and research [D] of finite volume method. Lanzhou: Lanzhou University of Science & Technology, 2011.

[11] fine jade is opened. based on the dyke building Numerical Analysis of Seepage Field [D] of Fluent. Taiyuan: Institutes Of Technology Of Taiyuan, 2013.

[12] Wang Lei, Liu Zhong, Zhang Youtian. there is the Seepage [J] of osculum curtain. Journal of Hydraulic Engineering, 1992, (4): 15-20.

[13]Zhan?M?L,Su?B?Y.New?method?of?simulating?concentrated?drain?holes?in?seepage?control?analysis[J].Journal?of?Hydrodynamics.Ser.B,1999,3:27～35。

[14] Wang Enzhi, Wang Hongtao, Wang Huiming. " to stitch Dai Jinglie "---osculum curtain analogy method inquires into [J]. Chinese Journal of Rock Mechanics and Engineering, 2002,21 (1): 98-101.

[15] Hu Jing, Chen Shenghong. the air element [J] of simulation of drain holes in Analysis of The Seepage. rock-soil mechanics, 2003,24 (2): 281-283.

Summary of the invention

For overcoming the deficiencies in the prior art, learn the seepage field situation of earth and rockfill dam nodal region under complex geological condition exactly, the present invention proposes a kind ofly accurately to reflect that geological information can go out the method for numerical simulation of earth and rockfill dam nodal region seepage field by accurate simulation again.

A kind of method based on three-dimensional detailed geological model prediction earth and rockfill dam nodal region seepage field of the present invention, comprises the following steps:

Step one, foundation comprise the nodal region three-dimensional geological refined model in unfavorable geologic body and crack, comprising:

Hydroelectric Engineering Geology data are divided into deterministic data and statistically data; For determinacy geologic data, the NURBS (Non-Uniform Rational B-Splines) of three-dimensional hybrid data structure, tectonic structure curved surface and geologic body is adopted to build rock stratum, nodal region, unfavorable geologic body and ooze the three-dimensional geological model of control structure; For statistically geologic data, Monte Carlo (Monte Carlo) method is adopted to build Three-dimensional Rock Fracture Networks model; For three-dimensional geological model and Three-dimensional Rock Fracture Networks model, based on the spatial relation between Boolean calculation analytical model, boolean's difference operation is carried out to the geologic body of overlap, realize rock stratum, unfavorable geologic body and the coupling of Fracture Networks model on locus, thus obtain three-dimensional detailed geological model;

Step 2, set up three dimensional fluid flow computing grid model based on three-dimensional detailed geological model: by computation fluid dynamics (Computational Fluid Dynamics) software, the geologic data coupling comprising formation information, unfavorable geologic body information and crack information is converted into Fluid Mechanics Computation model data, simultaneously, body fitted grids and local refined net partitioning is adopted three-dimensional detailed geological model to be converted into three dimensional fluid flow computing grid model, in order to realize the accurate expression of actual geological information in computation fluid dynamics software computation model;

Step 3, earth-rock dam seepage Numerical Simulation based on three-dimensional detailed geological model, comprising:

3-1, set up mathematical model in order to earth-rock dam seepage Numerical Simulation, this mathematical model comprises continuity equation, the water-air two phase flow N-S equation of coupling VOF (Volume of Fluid) method, aqueous vapor two-phase mixtures density equation and mixing velocity equation; Mixing velocity equation and hybrid density equation are in order to express mixing velocity and the hybrid density of aqueous vapor two-phase in seepage field, and mixing velocity equation and hybrid density equation are all coupled in water-air two phase flow N-S equation by filtrational resistance source item; Wherein: continuity equation:

$\frac{\∂\mathrm{\ρ}}{\∂t}+\mathrm{div}\left(\mathrm{\ρu}\right)=0---\left(1\right)$

Water-air two phase flow N-S equation:

$\frac{\mathrm{du}}{\mathrm{dt}}=f-\frac{1}{\mathrm{\ρ}}\mathrm{grad}p+{v\▿}^{2}u+S---\left(2\right)$

In formula (1) and formula (2): u is the average velocity of infinitesimal section, the porosity of the relation of u and pore fluid true velocity u' to be u=nu', n be porous medium, unit is m/s; T is the time, and unit is s; F is unit mass force, and unit is N; P is the pressure on fluid micro unit, and unit is Pa; ρ is fluid density, and unit is m ³/ s; V is fluid kinematic coefficient of viscosity, and unit is m ²/ s; S is filtrational resistance source item, equals inertia loss item S _iwith viscosity loss item S _vsum; If S _i=0, viscosity loss item S _vexpression formula be:

$S_v=-\frac{\mathrm{\ρv}}{\mathrm{\α}}u---\left(3\right)$

In formula (3): for viscosity factor, unit is 1/m ², its expression formula is:

$\frac{1}{\mathrm{\α}}=\frac{g}{\mathrm{Kv}}---\left(4\right)$

In formula (4): K is the infiltration coefficient of porous medium, and unit is m/s; After coupling VOF method, aqueous vapor two-phase shares a set of equation, formula (1) is no longer constant to ρ and ν in formula (4), but adopt the variable that the hybrid density equation of aqueous vapor two-phase and mixing velocity equation are determined, the expression formula of aqueous vapor two-phase mixtures density equation and mixing velocity equation is respectively:

Hybrid density equation: ρ=F _wρ _w+ (1-F _w) ρ _a(5)

Mixing velocity strategy: ν=F _wν _w+ (1-F _w) ν _a(6)

In formula (5) and formula (6): ρ _w, ρ _abe respectively the density of water, gas two kinds of fluids, unit is kg/m ³; ν _w, ν _abe respectively the coefficientof kinematic viscosity of water, gas two kinds of fluids, unit is m ²/ s; F _wfor the volume fraction of water, unit is zero dimension;

3-2, determine the boundary condition of three dimensional fluid flow computing grid model, comprise: import boundary condition: the water logging of storehouse, upstream there is not part, be taken as and determine head pressure entrance boundary, according to upper pond level before Practical Project determination dam, thus determine that head pressure is determined in upstream, according to upstream reservoir level, import aqueous vapor two-phase ratio of component is set; Export boundary condition: downstream boundary is taken as exit boundary, will be positioned at the level of tail water and be taken as with lower part and determine head pressure exit boundary, the level of tail water is taken as free water outlet border with upper part, sets out saliva gas two-phase ratio of component according to downstream reservoir level; Solid wall surface boundary condition: by solid law of the wall process, the node of all Gu Bichu all adopts non-slip condition process;

3-3, the continuity equation determined according to step 3-1, the water-air two phase flow N-S equation of coupling VOF method, aqueous vapor two-phase mixtures rate equation and hybrid density equation, the boundary condition that step 3-2 is arranged, and according to the permeability parameters that Practical Project is determined, undertaken discrete by finite volume method, SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm is utilized to solve, realize the earth-rock dam seepage Numerical Simulation based on three-dimensional detailed geological model, thus prediction earth and rockfill dam nodal region seepage field.

What provide in the present invention a kind ofly determines that the method for earth and rockfill dam dam body saturated surface utilizes the above-mentioned seepage field obtained based on the method for three-dimensional detailed geological model prediction earth and rockfill dam nodal region seepage field, and adopts VOF method determination earth and rockfill dam dam body saturated surface, and method is as follows:

VOF method is introduced one fluid model and is processed polyphasic flow problem, for water-air two phase flow flow field, be located at the water in same unit, gas or the mixture of the two and there is identical speed, namely obey the same group of equation of momentum, using the volume function of aqueous vapor two-phase in whole seepage field all as independent variable; In any one unit, the gentle volume fraction sum of water equals 1, if F _wrepresent the volume fraction of water, then the volume fraction of gas is 1-F _w; Work as F _w=1, represent this unit all occupied by aqueous phase; Work as F _w=0, represent this unit all occupied by gas phase; Work as 0<F _w<1, represents that this unit is the interface element of aqueous vapor two-phase; The variablees such as the pressure that aqueous vapor two-phase has, flow velocity all adopt the weighted mean value of volume function to represent;

Volume fraction function:

$\frac{{\&PartialD;F}_w}{\&PartialD;t}+\mathrm{\&rho;v}\&dtri;F_w=0---\left(7\right)$

In formula (7): t is the time, and unit is s; ρ is fluid density, unit m ³/ s; ν is fluid kinematic coefficient of viscosity, and unit is m ²/ s;

Space aqueous vapor two-phase volume fraction separately everywhere can be obtained by solving volume fraction function, in interface zone, adopting the geometrical reconstruction method of piecewise linear interpolation to obtain aqueous vapor interphase; Seepage flow in earth and rockfill dam is the free seepage with saturated surface, and seepage flow saturated surface is the interphase of water-air two phase flow in essence, and VOF method therefore can be adopted to obtain RCCD saturated surface.

Compared with prior art, the invention has the beneficial effects as follows:

(1) NURBS constructing technology is adopted to set up the three-dimensional detailed geological model comprising all kinds of unfavorable geologic body and ooze control structure, and adopt Monte Carlo technique to build three-dimensional fracture network, and realize being coupled of geologic model and Fracture Networks by Boolean calculation analysis, achieve the fine analog to dam foundation complex geological condition.

(2) transformed by being coupled between geological model data with CFD model data, set up CFD model, achieve the accurate expression of true complicated landform in CFD software, compensate for the limitation that in modeling in the past, grid accuracy is inadequate.

(3) based on three-dimensional detailed geological model, adopt Fluid Mechanics Computation method (CFD), set up equivalent continuity porous media model and three-dimensional seepage field numerical simulator, achieve the accurate simulation of the earth and rockfill dam nodal region three-dimensional seepage field under complex geological condition.

(4) adopt the simulation of VOF method to determine dam body seepage field saturated surface, achieve direct modeling seepage flow saturated surface, analog result is more accurate.

Accompanying drawing explanation

Fig. 1 is the earth-rock dam seepage Numerical Simulation method flow diagram that the present invention is based on three-dimensional detailed geological model;

Fig. 2 is the three-dimensional fine modeling general structure of engineering geology in the present invention;

Fig. 3 is SIMPLE algorithm flow chart in the present invention.

Embodiment

Below in conjunction with accompanying drawing, technical solution of the present invention is described in further detail.

The present invention constructs a kind of earth-rock dam seepage Numerical Simulation method of the three-dimensional detailed geological model that can be coupled, it accurately can reflect that geological information can go out earth and rockfill dam nodal region seepage field by accurate simulation again, reach the object of Accurate Prediction earth and rockfill dam nodal region seepage field, for earth-rock dam seepage controls to provide guidance.

Method based on three-dimensional detailed geological model prediction earth and rockfill dam nodal region seepage field of the present invention mainly comprises the nodal region three-dimensional geological refined model modeling method comprising stratum, unfavorable geologic body and crack, based on the earth-rock dam seepage Numerical Simulation method of three-dimensional detailed geological model, and VOF method is used to solve earth and rockfill dam dam body saturated surface method.General technical flow process as shown in Figure 1, mainly comprise following three parts: (1) three-dimensional geological modeling: first, according to key water control project dam district multi-source geologic data and Dam Designs in Last data, set up dam body, stratum, unfavorable geologic body, ooze five large-sized model such as control structure, crack; Then, analyze the spatial relation between geologic model and model of fissuration based on Boolean calculation, boolean's difference operation is carried out to the geologic body of overlap, obtains three-dimensional fine geology unified model; Finally, based on three-dimensional fine geology unified model, body fitted grids and local refined net partitioning is used to set up three dimensional fluid flow computing grid model.(2) three dimensional fluid flow Numerical Simulation: based on three dimensional fluid flow computing grid model, permeability parameters and the boundary condition of model are set according to engineering practice, adopt three dimensional fluid flow computational mathematics model and three VOF mathematical models, calculate earth and rockfill dam nodal region seepage field.Then by obtaining the distribution of the head of nodal region, hydraulic gradient and uplift pressure to the analysis of earth and rockfill dam nodal region seepage field, and leakage.(3) dam body saturated surface solves analysis: the earth and rockfill dam nodal region seepage field obtained according to part (2), adopts VOF method to calculate the volume fraction of aqueous vapor two-phase, obtains the interface of aqueous vapor two-phase, and then obtain the saturated surface of earth and rockfill dam dam body.

Preferred forms of the present invention is as follows:

Step one, foundation comprise the nodal region three-dimensional geological refined model in unfavorable geologic body and crack,

Comprise:

(1) Hydroelectric Engineering Geology data are divided into deterministic data and statistically data; For determinacy geologic data, adopt NURBS (the Non-Uniform Rational B-Splines) constructing technology of three-dimensional hybrid data structure, tectonic structure curved surface and geologic body to build rock stratum, nodal region, unfavorable geologic body and ooze the three-dimensional geological model of control structure; Wherein, unfavorable geologic body comprises one or more in compressive belt, shatter belt, corrosion band and weak intercalated layer.

(2) for statistically geologic data, Monte Carlo (Monte Carlo) method is adopted to build Three-dimensional Rock Fracture Networks model; Three-dimensional fracture network model construction mainly comprises following 7 steps: 1) determine sample area, effectively divides into groups according to the occurrence in crack in actual samples region; 2) quantity and the density of often organizing crack is determined; 3) probability model that the geometric parameters such as crack mark length, spacing, occurrence are obeyed is determined often to organize; 4) utilize Monte Carlo method to generate a series of analog parameter, and the result that checking generates meet the probability model of expection; 5) the three-dimensional fracture network model often organizing crack is generated; 6) cutting model of fissuration, to often organizing, crack mark is long, the parameter of spacing is checked, and ensures that itself and preset value are to consistent; 7) preliminary Three-dimensional network model is generated.

(3) for three-dimensional geological model and Three-dimensional Rock Fracture Networks model, the spatial relation between geologic model and model of fissuration is analyzed based on Boolean calculation, boolean's difference operation is carried out to the geologic body of overlap, realize rock stratum, unfavorable geologic body and the coupling of Fracture Networks model on locus, thus obtain three-dimensional detailed geological model.The three-dimensional fine modeling general structure in engineering geology and crack as shown in Figure 2, according to original survey data, 2D cross-section and engineering design data, adopt MIDAS mixed data structure face and to object technology, carry out Geometric Modeling, modeling process is mainly divided into following three parts: (1) is set up dam body, oozed the model of the man-made objects such as control structure, gallery, then they are combined, obtain engineering construction object model; (2) model of the natural geological objects such as landform, stratum, crack, unfavorable geologic body is set up, then they are combined, obtain three-dimensional geological model, finally use original survey data, 2D cross-section and engineering design data to carry out the Analysing Geology Trend Surface improved again, thus carry out supplementing checking to the three-dimensional geological model set up; (3) analyze the spatial relation between geologic model and engineering construction object model based on Boolean calculation, boolean's difference operation is carried out to lap, thus obtains earth and rockfill dam nodal region three dimensional unification model.

Step 2, set up three dimensional fluid flow computing grid model based on three-dimensional detailed geological model:

Based on the three-dimensional geological model comprising bad ground information set up, by computation fluid dynamics (Computational Fluid Dynamics) software, the geologic data coupling comprising formation information, unfavorable geologic body information and crack information is converted into Fluid Mechanics Computation model data, simultaneously, body fitted grids and local refined net partitioning is adopted three-dimensional detailed geological model to be converted into three dimensional fluid flow computing grid model, in order to realize the accurate expression of actual geological information in computation fluid dynamics software computation model.

Step 3, earth-rock dam seepage Numerical Simulation based on three-dimensional detailed geological model:

Comprise:

3-1, set up mathematical model in order to earth-rock dam seepage Numerical Simulation, this mathematical model comprises continuity equation, the water-air two phase flow N-S equation of coupling VOF (Volume of Fluid) method, aqueous vapor two-phase mixtures density equation and mixing velocity equation; Mixing velocity equation and hybrid density equation are in order to express mixing velocity and the hybrid density of aqueous vapor two-phase in seepage field, and mixing velocity equation and hybrid density equation are all coupled in water-air two phase flow N-S equation by filtrational resistance source item;

Wherein:

Continuity equation:

$\frac{\&PartialD;\mathrm{\&rho;}}{\&PartialD;t}+\mathrm{div}\left(\mathrm{\&rho;u}\right)=0---\left(1\right)$

Water-air two phase flow N-S equation:

$\frac{\mathrm{du}}{\mathrm{dt}}=f-\frac{1}{\mathrm{\&rho;}}\mathrm{grad}p+{v\&dtri;}^{2}u+S---\left(2\right)$

In formula (1) and formula (2): u is the average velocity of infinitesimal section, the porosity of the relation of u and pore fluid true velocity u' to be u=nu', n be porous medium, unit is m/s; T is the time, and unit is s; F is unit mass force, is generally only gravity, and unit is N; P is the pressure on fluid micro unit, and unit is Pa; ρ is fluid density, and unit is m ³/ s; ν is fluid kinematic coefficient of viscosity, and unit is m ²/ s; S is filtrational resistance source item, equals inertia loss item S _iwith viscosity loss item S _vsum; Inertia loss item can be ignored for the laminar condition that flow velocity is lower, namely think S _i=0; The flowing higher for flow velocity can ignore viscosity loss item, namely thinks S _v=0.Because in the Seepage Flow Field of roller compacted concrete Dam studied in the present invention, the seepage velocity of water is lower, belong to laminar condition, therefore can ignore inertia resistance item, if S _i=0, viscosity loss item S _vexpression formula be:

$S_v=-\frac{\mathrm{\&rho;v}}{\mathrm{\&alpha;}}u---\left(3\right)$

In formula (3): for viscosity factor, unit is 1/m ², its expression formula is:

$\frac{1}{\mathrm{\&alpha;}}=\frac{g}{\mathrm{Kv}}---\left(4\right)$

In formula (4): K is the infiltration coefficient of porous medium, and unit is m/s;

After coupling VOF method, aqueous vapor two-phase shares a set of equation, formula (1) is no longer constant to ρ and ν in formula (4), but adopt the variable that the hybrid density equation of aqueous vapor two-phase and mixing velocity equation are determined, the expression formula of aqueous vapor two-phase mixtures density equation and mixing velocity equation is respectively:

Hybrid density equation ρ=F _wρ _w+ (1-F _w) ρ _a(5)

Mixing velocity strategy ν=F _wν _w+ (1-F _w) ν _a(6)

In formula (5) and formula (6): ρ _w, ρ _abe respectively the density of water, gas two kinds of fluids, unit is kg/m ³; ν _w, ν _abe respectively the coefficientof kinematic viscosity of water, gas two kinds of fluids, unit is m ²/ s; F _wfor the volume fraction of water, unit is zero dimension.

3-2, determine to comprise the boundary condition of three dimensional fluid flow computing grid model:

Import boundary condition: the water logging of storehouse, upstream there is not part, is taken as and determines head pressure entrance boundary, according to upper pond level before Practical Project determination dam, thus determines that head pressure is determined in upstream, arranges import aqueous vapor two-phase ratio of component according to upstream reservoir level;

Export boundary condition: downstream boundary is taken as exit boundary, will be positioned at the level of tail water and be taken as with lower part and determine head pressure exit boundary, the level of tail water is taken as free water outlet border with upper part, sets out saliva gas two-phase ratio of component according to downstream reservoir level;

Solid wall surface boundary condition: by solid law of the wall process, the node of all Gu Bichu all adopts non-slip condition process.

3-3, according to the continuity equation that step 3-1 determines, the water-air two phase flow N-S equation of coupling VOF method, aqueous vapor two-phase mixtures rate equation and hybrid density equation, the boundary condition that step 3-2 is arranged, and (comprise dam body according to the permeability parameters that Practical Project is determined, the permeability rate of stratum and unfavorable geologic body and infiltration coefficient), undertaken discrete by finite volume method, SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm is utilized to solve, realize the earth-rock dam seepage Numerical Simulation based on three-dimensional detailed geological model, thus prediction earth and rockfill dam nodal region seepage field.SIMPLE algorithm flow as shown in Figure 3, mainly comprises following 9 steps: setting completed for (1) boundary condition, prepares to calculate; (2) suppose velocity distribution u0, a v0, coefficient and the constant term (3) of momentum discrete equation during for calculating iteration first suppose a pressure field, i.e. setting pressure conjecture value p*; (4) according to present speed field and pressure field, the coefficient in the equations such as momentum discrete equation and constant term is calculated (5) solve momentum discrete equation, obtain speed u*, v*; (6) according to speed u*, v*, solve pressure correction equation, obtain revised pressure p; (7) improve speed according to revised pressure, obtain revising rear speed u, v; (8) utilize revised velocity field to solve every other discretize transport equation, obtain the coefficient in the equations such as momentum discrete equation and constant term (9) judge whether to restrain, if convergence, then calculate end; If do not restrain, then make p*=p, u*=u, V*=v, return in step (4) and recalculate, loop iteration, until convergence.

Utilize the above-mentioned seepage field obtained based on the method for three-dimensional detailed geological model prediction earth and rockfill dam nodal region seepage field in the present invention, and adopt VOF method determination earth and rockfill dam dam body saturated surface,

The VOF method proposed by Hirt and Nichols is a kind of effective ways processing Free Surface.Seepage flow in earth and rockfill dam dam body is the seepage with free surface with saturated surface, and seepage flow saturated surface is the interface of water-air two phase flow in essence, and VOF method therefore can be adopted to obtain saturated surface.The method is as follows:

VOF method is introduced one fluid model and is processed polyphasic flow problem, for water-air two phase flow flow field, be located at the water in same unit, gas or the mixture of the two and there is identical speed, namely obey the same group of equation of momentum, using the volume function of aqueous vapor two-phase in whole seepage field all as independent variable.In any one unit, the gentle volume fraction sum of water equals 1.In a unit, if F _wrepresent the volume fraction of water, then the volume fraction of gas is 1-F _w.F _wthere are 3 kinds of situation: F _w=0,0<F _w<1, F _w=1;

Work as F _w=0, represent this unit all occupied by gas phase;

Work as 0<F _w<1, represents that this unit is the interface element of aqueous vapor two-phase;

Work as F _w=1, represent this unit all occupied by aqueous phase;

The variable that other aqueous vapor is total, the flow velocity had as aqueous vapor two-phase, flow, pressure can adopt the weighted mean value of volume function to represent.

Volume fraction function:

$\frac{{\&PartialD;F}_w}{\&PartialD;t}+\mathrm{\&rho;v}\&dtri;F_w=0---\left(7\right)$

In formula (7): t is the time, and unit is s; ρ is fluid density, unit m ³/ s; ν is fluid kinematic coefficient of viscosity, and unit is m ²/ s.

Space aqueous vapor two-phase volume fraction separately everywhere can be obtained by solving volume fraction function, in interface zone, adopting the geometrical reconstruction method of piecewise linear interpolation to obtain aqueous vapor interphase, i.e. saturated surface.Seepage flow in earth and rockfill dam is the free seepage with saturated surface, and seepage flow saturated surface is the interphase of water-air two phase flow in essence, and VOF method therefore can be adopted to obtain RCCD saturated surface.

Although invention has been described by reference to the accompanying drawings above; but the present invention is not limited to above-mentioned embodiment; above-mentioned embodiment is only schematic; instead of it is restrictive; those of ordinary skill in the art is under enlightenment of the present invention; when not departing from present inventive concept, can also make a lot of distortion, these all belong within protection of the present invention.

Claims (4)

1., based on a method for three-dimensional detailed geological model prediction earth and rockfill dam nodal region seepage field, comprising:

Step one, foundation comprise the nodal region three-dimensional geological refined model in unfavorable geologic body and crack, comprising:

Hydroelectric Engineering Geology data are divided into deterministic data and statistically data; For determinacy geologic data, adopt the NURBS of three-dimensional hybrid data structure, tectonic structure curved surface and geologic body to build rock stratum, nodal region, unfavorable geologic body and ooze the three-dimensional geological model of control structure; For statistically geologic data, Monte Carlo method is adopted to build Three-dimensional Rock Fracture Networks model;

For three-dimensional geological model and Three-dimensional Rock Fracture Networks model, the spatial relation between geologic model and model of fissuration is analyzed based on Boolean calculation, boolean's difference operation is carried out to the geologic body of overlap, realize rock stratum, unfavorable geologic body and the coupling of Fracture Networks model on locus, thus obtain three-dimensional detailed geological model;

Step 2, set up three dimensional fluid flow computing grid model based on three-dimensional detailed geological model:

By computation fluid dynamics software, the geologic data coupling comprising formation information, unfavorable geologic body information and crack information is converted into Fluid Mechanics Computation model data, simultaneously, body fitted grids and local refined net partitioning is adopted three-dimensional detailed geological model to be converted into three dimensional fluid flow computing grid model, in order to realize the accurate expression of actual geological information in computation fluid dynamics software computation model;

Step 3, earth-rock dam seepage Numerical Simulation based on three-dimensional detailed geological model, comprising:

3-1, set up mathematical model in order to earth-rock dam seepage Numerical Simulation, this mathematical model comprises continuity equation, the water-air two phase flow N-S equation of coupling VOF method, aqueous vapor two-phase mixtures density equation and mixing velocity equation; Mixing velocity equation and hybrid density equation are in order to express mixing velocity and the hybrid density of aqueous vapor two-phase in seepage field, and mixing velocity equation and hybrid density equation are all coupled in water-air two phase flow N-S equation by filtrational resistance source item;

Wherein:

Continuity equation:

$\frac{\&PartialD;\mathrm{\&rho;}}{\&PartialD;t}+\mathrm{div}\left(\mathrm{\&rho;u}\right)=0---\left(1\right)$

Water-air two phase flow N-S equation:

$\frac{\mathrm{du}}{\mathrm{dt}}=f-\frac{1}{\mathrm{\&rho;}}\mathrm{grad}p+v{\&dtri;}^{2}u+S---\left(2\right)$

In formula (1) and formula (2):

U is the average velocity of infinitesimal section, the porosity of the relation of u and pore fluid true velocity u' to be u=nu', n be porous medium, and unit is m/s;

T is the time, and unit is s;

F is unit mass force, and unit is N;

P is the pressure on fluid micro unit, and unit is Pa;

ρ is fluid density, and unit is m ³/ s;

ν is fluid kinematic coefficient of viscosity, and unit is m ²/ s;

S is filtrational resistance source item, equals inertia loss item S _iwith viscosity loss item S _vsum; If S _i=0, viscosity loss item S _vexpression formula be:

$S_v=-\frac{\mathrm{\&rho;v}}{\mathrm{\&alpha;}}u---\left(3\right)$

In formula (3): for viscosity factor, unit is 1/m ², its expression formula is:

$\frac{1}{\mathrm{\&alpha;}}=\frac{g}{\mathrm{Kv}}---\left(4\right)$

In formula (4): K is the infiltration coefficient of porous medium, and unit is m/s;

After coupling VOF method, aqueous vapor two-phase shares a set of equation, formula (1) is no longer constant to ρ and ν in formula (4), but adopt the variable that the hybrid density equation of aqueous vapor two-phase and mixing velocity equation are determined, the expression formula of aqueous vapor two-phase mixtures density equation and mixing velocity equation is respectively:

Hybrid density equation ρ=F _wρ _w+ (1-F _w) ρ _a(5)

Mixing velocity strategy ν=F _wν _w+ (1-F _w) ν _a(6)

In formula (5) and formula (6): ρ _w, ρ _abe respectively the density of water, gas two kinds of fluids, unit is kg/m ³; ν _w, ν _abe respectively the coefficientof kinematic viscosity of water, gas two kinds of fluids, unit is m ²/ s; F _wfor the volume fraction of water, unit is zero dimension;

3-2, determine to comprise the boundary condition of three dimensional fluid flow computing grid model:

Import boundary condition: the water logging of storehouse, upstream there is not part, is taken as and determines head pressure entrance boundary, according to upper pond level before Practical Project determination dam, thus determines that head pressure is determined in upstream, arranges import aqueous vapor two-phase ratio of component according to upstream reservoir level;

Export boundary condition: downstream boundary is taken as exit boundary, will be positioned at the level of tail water and be taken as with lower part and determine head pressure exit boundary, the level of tail water is taken as free water outlet border with upper part, sets out saliva gas two-phase ratio of component according to downstream reservoir level;

Solid wall surface boundary condition: by solid law of the wall process, the node of all Gu Bichu all adopts non-slip condition process;

3-3, the continuity equation determined according to step 3-1, the water-air two phase flow N-S equation of coupling VOF method, aqueous vapor two-phase mixtures rate equation and hybrid density equation, the boundary condition that step 3-2 is arranged, and according to the permeability parameters that Practical Project is determined, undertaken discrete by finite volume method, utilize SIMPLE algorithm to solve, realize the earth-rock dam seepage Numerical Simulation based on three-dimensional detailed geological model, thus prediction earth and rockfill dam nodal region seepage field.

2., according to claim 1 based on the method for three-dimensional detailed geological model prediction earth and rockfill dam nodal region seepage field, it is characterized in that, in step one, unfavorable geologic body comprises one or more in compressive belt, shatter belt, corrosion band and weak intercalated layer.

3. according to claim 1 based on the method for three-dimensional detailed geological model prediction earth and rockfill dam nodal region seepage field, it is characterized in that, in step 3, the permeability parameters determined according to Practical Project comprises dam body, the permeability rate of stratum and unfavorable geologic body and infiltration coefficient.

4. determine the method for earth and rockfill dam dam body saturated surface for one kind, it is characterized in that, utilize if claim 1 or 2 or 3 is based on the seepage field of the method acquisition of three-dimensional detailed geological model prediction earth and rockfill dam nodal region seepage field, adopt VOF method determination earth and rockfill dam dam body saturated surface, method is as follows:

VOF method is introduced one fluid model and is processed polyphasic flow problem, for water-air two phase flow flow field, be located at the water in same unit, gas or the mixture of the two and there is identical speed, namely obey the same group of equation of momentum, using the volume function of aqueous vapor two-phase in whole seepage field all as independent variable; In any one unit, the gentle volume fraction sum of water equals 1, if F _wrepresent the volume fraction of water, then the volume fraction of gas is 1-F _w; Work as F _w=1, represent this unit all occupied by aqueous phase; Work as F _w=0, represent this unit all occupied by gas phase; Work as 0<F _w<1, represents that this unit is the interface element of aqueous vapor two-phase; The variablees such as the pressure that aqueous vapor two-phase has, flow velocity all adopt the weighted mean value of volume function to represent;

Volume fraction function:

$\frac{\&PartialD;F_w}{\&PartialD;t}+\mathrm{\&rho;v}\&dtri;F_w=0---\left(7\right)$

In formula (7): t is the time, and unit is s; ρ is fluid density, unit m ³/ s; ν is fluid kinematic coefficient of viscosity, and unit is m ²/ s;

Space aqueous vapor two-phase volume fraction separately everywhere can be obtained by solving volume fraction function, in interface zone, adopting the geometrical reconstruction method of piecewise linear interpolation to obtain aqueous vapor interphase; Seepage flow in earth and rockfill dam is the free seepage with saturated surface, and seepage flow saturated surface is the interphase of water-air two phase flow in essence, and VOF method therefore can be adopted to obtain RCCD saturated surface.