CN116542052A - Method for calculating stability of tailings dam by using mould bag method - Google Patents
Method for calculating stability of tailings dam by using mould bag method Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 79
- 239000004576 sand Substances 0.000 claims abstract description 42
- 238000004364 calculation method Methods 0.000 claims abstract description 40
- 238000004458 analytical method Methods 0.000 claims abstract description 23
- 230000003993 interaction Effects 0.000 claims abstract description 11
- 239000011229 interlayer Substances 0.000 claims abstract description 11
- 125000006850 spacer group Chemical group 0.000 claims abstract description 9
- 239000002689 soil Substances 0.000 claims description 56
- 238000009826 distribution Methods 0.000 claims description 12
- 230000005484 gravity Effects 0.000 claims description 9
- 230000003068 static effect Effects 0.000 claims description 9
- 239000010410 layer Substances 0.000 claims description 6
- 238000010008 shearing Methods 0.000 claims description 6
- 241000212384 Bifora Species 0.000 claims description 3
- 238000009827 uniform distribution Methods 0.000 claims description 3
- 239000000853 adhesive Substances 0.000 claims description 2
- 230000001070 adhesive effect Effects 0.000 claims description 2
- 238000010276 construction Methods 0.000 abstract description 10
- 238000013461 design Methods 0.000 abstract description 6
- 231100000817 safety factor Toxicity 0.000 description 11
- PCTMTFRHKVHKIS-BMFZQQSSSA-N (1s,3r,4e,6e,8e,10e,12e,14e,16e,18s,19r,20r,21s,25r,27r,30r,31r,33s,35r,37s,38r)-3-[(2r,3s,4s,5s,6r)-4-amino-3,5-dihydroxy-6-methyloxan-2-yl]oxy-19,25,27,30,31,33,35,37-octahydroxy-18,20,21-trimethyl-23-oxo-22,39-dioxabicyclo[33.3.1]nonatriaconta-4,6,8,10 Chemical compound C1C=C2C[C@@H](OS(O)(=O)=O)CC[C@]2(C)[C@@H]2[C@@H]1[C@@H]1CC[C@H]([C@H](C)CCCC(C)C)[C@@]1(C)CC2.O[C@H]1[C@@H](N)[C@H](O)[C@@H](C)O[C@H]1O[C@H]1/C=C/C=C/C=C/C=C/C=C/C=C/C=C/[C@H](C)[C@@H](O)[C@@H](C)[C@H](C)OC(=O)C[C@H](O)C[C@H](O)CC[C@@H](O)[C@H](O)C[C@H](O)C[C@](O)(C[C@H](O)[C@H]2C(O)=O)O[C@H]2C1 PCTMTFRHKVHKIS-BMFZQQSSSA-N 0.000 description 8
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- 238000005516 engineering process Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
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- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
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- 238000004422 calculation algorithm Methods 0.000 description 1
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Classifications
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/02—Reliability analysis or reliability optimisation; Failure analysis, e.g. worst case scenario performance, failure mode and effects analysis [FMEA]
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A10/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE at coastal zones; at river basins
- Y02A10/40—Controlling or monitoring, e.g. of flood or hurricane; Forecasting, e.g. risk assessment or mapping
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- Pit Excavations, Shoring, Fill Or Stabilisation Of Slopes (AREA)
Abstract
The invention provides a method for calculating the stability of a tailings dam by a mould bag method, which comprises the following steps: s1, calculating based on a die pocket interlayer sliding failure mode: taking a spacer between the bottom end face of the sliding part of the tailing dam and the top end face of the tailing dam as a rigid pressure slope body, independently carrying out stress analysis on the spacer, solving the interaction force between the spacer and the tailing sand, calculating the stable safety coefficient of the spacer sliding along with the tailing sand, and superposing the stable safety coefficient to obtain a sliding damage calculation formula; s2, calculating based on a deep sliding damage mode of crossing the die pocket: the isolator only transmits vertical force to the tailing sand part, and a calculation formula of deep sliding is obtained; s3, simulating, comparing, calculating and analyzing. The calculation method is scientific and reasonable, the stability of the tailings dam by the mould bag method is accurately calculated, theoretical basis is provided for design and construction of the tailings dam by the mould bag method, and safety is improved.
Description
Technical Field
The invention belongs to the technical field of design and construction of tailing dams, and particularly relates to a method for calculating stability of a tailing dam by a mould bag method.
Background
The mineral resources of China are rich, tailings are solid wastes generated in the mineral industry, the annual discharge amount is huge, and the tailings are piled up in a form of a tailings pond. Tailings ponds are a special industrial building that can safely and stably run, playing a very important role in the production of concentrating mills. The tailing pond consists of a dam body built by tailing sand, the tailing sand and water in the dam body, and forms a manually-built tailing lake which is in a unsteady dangerous state at any time. Once the tailing dam body is broken, tailing sand can flow out in the form of debris flow, which causes serious threat to downstream environment and life and property of surrounding residents, and immeasurable loss to mine enterprises. Cases of serious damage to the results caused by destabilization and failure of tailing pond engineering at home and abroad are frequent. Therefore, how to ensure the safety and stability of the tailing dam is a serious concern.
In recent years, the level of beneficiation technology and recovery rate are continuously improved, the grain size of tailings is finer and finer, and the number of fine tailings ponds is also continuously increased. The fine tailings are characterized by poor water permeability after warehouse entry, difficult dissipation of excess pore water pressure, long consolidation time, low mechanical strength and the like. Because the upstream method has simple dam building process and convenient management, the method is widely used in China for decades. If the traditional upstream method is adopted for the fine tailings, the problems of difficult damming, slow slope of a deposited beach, unsmooth drainage of a dam body, poor stability and the like can be encountered, so that the research on the fine tailings damming technology is urgent.
The mould bag is a large-area continuous bag-shaped material made of high-strength geotextile, and is filled with tailing sand by pumping and solidifying the tailing sand therein to form the bag filling body. The mould bags in the tailing dam by the mould bag method have the characteristics common to geotechnical bags, such as high compressive strength; the mould bag filler can directly use soil, sand, stone or construction waste and the like near the site, so that resources are saved; the die bag has the advantages of low price, good reinforcing effect, high cost performance and the like; the method has the unique advantages of water permeable and slurry impermeable, high drainage consolidation speed, contribution to rapid dam building, high strength of the tailings dam body by a mould bag method, mature production process, simple operation, capacity of building the dam while producing, no influence on production and the like. The tailings dam by the mould bag method solves the problem that the tailings dam by the upstream method is difficult to fill by utilizing the advantages of the mould bag.
The successful application of the mould bag method fine tailings dam-accumulating technology solves the problem that fine tailings dams are difficult to accumulate, and is a great progress in the design and construction of tailings dams. However, the novel construction method is still in a starting stage, and how to calculate the stability after the mould bags are added is a problem which must be solved when the tailing dam is designed, and how to provide an accurate stability calculation method plays a vital role in the design of the tailing dam by the mould bags.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the method for calculating the stability of the tailings dam by the mould bag method, which is scientific and reasonable, strictly and reasonably deduced in theory and accords with the actual practice, thereby providing an important theoretical basis for the design and construction of the tailings dam by the mould bag method.
In order to solve the technical problems, the invention adopts the following technical scheme: the method for calculating the stability of the tailings dam by the mould bag method is characterized by comprising the following operation steps of:
s1, obtaining a die bag interlayer sliding-out calculation formula based on a die bag interlayer sliding failure mode;
s2, obtaining a deep sliding calculation formula based on a deep sliding damage mode;
s3, comparing, calculating and analyzing;
the step S1 comprises the following steps:
s101, taking a part from the bottom end surface of a sliding part of the tailing dam to the top end surface of the tailing dam as an isolator, regarding the isolator as a rigid pressure slope body, and carrying out stress analysis on the isolator alone;
s102, working out interaction force between the isolator and the tailing sand through static balance conditions and limit balance conditions;
s103, uniformly distributing interaction force between the isolator and the tailing sand on the tailing sand, calculating the stability of the isolator by using a rigid body limit balance method without a mould bag, and calculating a stable safety coefficient of the isolator sliding synchronously along with the tailing sand;
s104, superposing a moment balance equation of the sliding part of the isolator and the tailing sand to obtain a calculation formula of the sliding damage between the layers of the die bags.
The step S2 comprises the following steps:
s201, carrying out stress analysis and simplifying treatment on the isolator;
s202, a moment balance equation of vertical force is listed;
and S203, uniformly distributing force through a moment balance equation, and finally obtaining a calculation formula of deep sliding.
Preferably, the specific operation steps of S1 are as follows:
s101, carrying out stress analysis on the isolator, and listing a balance equation by static balance conditions
Wherein N is 1 For supporting the spacer upwards with horizontal sliding surface, N 2 For supporting the tailing sand obliquely facing the separator vertically upwards, T 1 T is the friction force between horizontal sliding surfaces 2 G is the gravity of the separator, l is the width of the separator, θ is the included angle between the separator and the horizontal plane, namely the slope of the dam slope, and h is the height of the separator;
s102, the bottom end surface of the isolator is a sliding surface, and the sliding surface is in a limit balance state, thus obtaining
Wherein,,other parameters are defined as the internal friction angle between the die bags.
Solving to obtain T 1 、N 1 、T 2 And N 2 ;
S103、T 1 `、N 1 `、T 2 ' and N 2 Respectively the counter force of the separator acting on the tailing sand according to the relation between the acting force and the counter forceT is provided with 1 =T’ 1 ,T 2 =T’ 2 ,N 1 =N 1 ’,N 2 =N 2 ' assuming that the tailing dam body is divided into m soil strips, for the horizontal slip plane part, the vertical distribution force and the horizontal distribution force acting on the ith soil strip are respectively p 1i And q 1i To represent; for the slope part, the vertical distribution force and the horizontal distribution force acting on the ith soil strip are respectively p 2i And q 2i To express, then
When i is more than or equal to 1 and less than or equal to m
When m < i
Carrying out stress analysis on the ith soil strip, wherein the ith soil strip is in a static equilibrium state in the vertical direction by the strip block i, and the ith soil strip meets the safety factor of F s Is limited in balance condition of (1)
Wherein G is i '=G i +p 2i b i +q 2i b i tg theta, where T i C is the friction force on the sliding surface of the ith soil strip i For the cohesion of the tailings, l i For the length of the sliding surface of the ith soil strip, N i For the vertical upward supporting force applied to the ith earth bar i G is the internal friction angle of the tailing sand i B is the gravity of the ith soil strip i For the i-th horizontal width of the soil strip, X i Is the shearing force applied to the left side of the ith soil strip, X i+1 Is the shearing force alpha applied to the right side of the ith soil strip i Is the included angle between the sliding surface and the horizontal plane, whichHis parameters are defined as before.
3. The method for calculating the stability of the tailings dam by the die bagging method according to claim 2, wherein the specific operation steps of S104 are as follows:
moment is taken from the circle center of the arc sliding surface, and the moment balance equation of the tailing sand sliding part is that
Wherein R is the radius of the arc sliding surface, h i Other parameters are defined as before for the vertical distance from the top surface of the ith soil strip to the far point.
Based on the distance of the center of the circle of the arc sliding surface taken by the isolator, there are
Wherein d 1 Is N 1 Arm of force d to centre of a circle 2 Force arm from G to circle center, d 3 Is T 2 And N 2 The arm of force from the vertical component to the center of the circle, and other parameters are the same as before.
In (4) and (5)And->Is the interaction force which can be counteracted by adding to obtain
Order the
Substituting the formula (2) and the formula (3) into the formula (6) to obtain X i+1 -X i =0, finally when the interlayer slips outThe safety coefficient calculation formula of (2) is
Wherein,,
4. the method for calculating the stability of the tailings dam by the die bagging method according to claim 1, wherein the specific operation steps of S2 are as follows:
the vertical pressure transmitted downwards by the isolator accords with the following partial conservation relation, and the vertical downward force F of the horizontal part of the tailing sand y1 And vertical downforce F of inclined portion of tailings sand y2 Is collinear with the gravitational force G of the separator
Wherein θ is the included angle between the isolator and the horizontal plane, namely the slope of the dam slope;
order the
p i The uniform distribution force on the corresponding bar blocks is realized;
f when deep sliding is obtained s The calculation formula is that
Wherein,,c i is the adhesion of the ith soil stripForce; b i The width of the ith soil strip; g i Is the gravity of the ith soil strip; phi (phi) i The internal friction angle of the ith soil strip; alpha i Is the included angle between the sliding surface of the ith soil strip and the horizontal plane.
Preferably, the specific operation steps of S3 are as follows: and (3) programming a corresponding calculation program by using MATLAB, calculating a plurality of groups of models, calculating the stability of the non-mould bag tailing dam by using a Bishop strip division method, and comparing and analyzing a plurality of data to verify the scientificity of a calculation mode.
Compared with the prior art, the invention has the following advantages:
the method is scientific and reasonable in operation and accurate in calculation, and provides a theoretical basis for the design and construction of the tailings dam by the mould bag method.
The invention is described in further detail below with reference to the drawings and examples.
Drawings
Fig. 1 is a schematic cross-sectional view of a tailings dam in a bag-in-mould process of the present invention.
FIG. 2 is a schematic illustration of the inter-layer slip in accordance with the present invention.
FIG. 3 is a schematic diagram illustrating the analysis of the slip force between layers according to the present invention.
FIG. 4 is a force analysis chart of an ith soil strip in the present invention.
Fig. 5 is a diagram of moment analysis of the separator of the present invention.
Fig. 6 is a schematic representation of deep slip in the present invention.
FIG. 7 is a graph of deep slip force analysis in the present invention.
Fig. 8 is a schematic diagram of a comparative model left in this example.
Fig. 9 is a schematic diagram of the calculation result of the scheme a in the present embodiment.
Fig. 10 is a graph showing the variation of the safety factor with dam height in the embodiment a.
Fig. 11 is a schematic diagram of the calculation result of the embodiment b.
Fig. 12 is a graph showing the safety factor of the embodiment b according to the slope ratio of the dam.
Fig. 13 is a schematic diagram of the calculation result of the embodiment c.
Fig. 14 is a graph showing the safety factor of the embodiment c according to the width of the dam.
Detailed Description
The embodiment comprises the following operation steps:
s1, obtaining a die bag interlayer sliding-out calculation formula based on a die bag interlayer sliding failure mode;
s2, obtaining a deep sliding calculation formula based on a deep sliding damage mode;
s3, comparing, calculating and analyzing;
the step S1 comprises the following steps:
s101, as shown in figures 1 and 2, taking a part ABCD from the bottom end face of a sliding part of a tailing dam to the top end face of the tailing dam as an isolator, regarding the isolator as a rigid pressure slope, and carrying out stress analysis on the isolator alone;
s102, working out interaction force between the isolator and the tailing sand through static balance conditions and limit balance conditions;
s103, uniformly distributing interaction force between the isolator and the tailing sand on the tailing sand, calculating the stability of the isolator by using a rigid body limit balance method without a mould bag, and calculating a stable safety coefficient of the isolator sliding synchronously along with the tailing sand;
s104, superposing a moment balance equation of the sliding part of the isolator and the tailing sand to obtain a calculation formula of the sliding damage between the layers of the die bags.
The step S2 comprises the following steps:
s201, carrying out stress analysis and simplifying treatment on the isolator;
s202, a moment balance equation of vertical force is listed;
and S203, uniformly distributing force through a moment balance equation, and finally obtaining a calculation formula of deep sliding.
In this embodiment, the specific operation steps of S1 are as follows:
s101, as shown in FIG. 3b, performing stress analysis on the isolator ABCD, and using a static equilibrium condition column equilibrium equation
Wherein N is 1 For supporting the spacer upwards with horizontal sliding surface, N 2 For supporting the tailing sand obliquely facing the separator vertically upwards, T 1 T is the friction force between horizontal sliding surfaces 2 G is the gravity of the separator, l is the width of the separator, θ is the included angle between the separator and the horizontal plane, namely the slope of the dam slope, and h is the height of the separator;
s102, the bottom end surface of the isolator is a sliding surface, and the sliding surface is in a limit balance state, thus obtaining
Wherein,,other parameters are defined as the internal friction angle between the die bags.
Solving to obtain T 1 、N 1 、T 2 And N 2 ;
S103、T 1 `、N 1 `、T 2 ' and N 2 The reaction forces of the spacers acting on the tailings sand are respectively T according to the relation between the acting force and the reaction force 1 =T’ 1 ,T 2 =T’ 2 ,N 1 =N 1 ’,N 2 =N 2 ' assuming that the tailing dam body is divided into m soil strips, for the horizontal slip plane part, the vertical distribution force and the horizontal distribution force acting on the ith soil strip are respectively p 1i And q 1i To represent; for the slope part, the vertical distribution force and the horizontal distribution force acting on the ith soil strip are respectively p 2i And q 2i To express, then
When i is more than or equal to 1 and less than or equal to m
When m < i
Carrying out stress analysis on the ith soil strip, wherein the ith soil strip is in a static equilibrium state in the vertical direction by the strip block i, and the ith soil strip meets the safety factor of F s Is limited in balance condition of (1)
Wherein G is i '=G i +p 2i b i +q 2i b i tg theta, where T i C is the friction force on the sliding surface of the ith soil strip i For the cohesion of the tailings, l i For the length of the sliding surface of the ith soil strip, N i For the vertical upward supporting force applied to the ith earth bar i G is the internal friction angle of the tailing sand i B is the gravity of the ith soil strip i For the i-th horizontal width of the soil strip, X i Is the shearing force applied to the left side of the ith soil strip, X i+1 Is the shearing force alpha applied to the right side of the ith soil strip i Other parameters are defined as before for the included angle between the sliding surface and the horizontal plane.
In this embodiment, the specific operation steps of S104 are as follows:
the whole slip body consists of the ABCD shown in fig. 3a and the B 'DC' shown in fig. 3B, i.e. the parts ABCD and B 'DC' slide out along the slip plane when the sliding occurs. When the moment balance equation of the whole sliding body is listed, the two parts are considered separately, and then are overlapped together, so that the moment balance equation of the whole sliding body can be listed.
Moment is taken from the circle center of the arc sliding surface, and the moment balance equation of the tailing sand sliding part is that
Wherein R is the radius of the arc sliding surface, h i Other parameters are defined as before for the vertical distance from the top surface of the ith soil strip to the far point.
Since the safety factor is defined by means of a moment. So the moment balance of the ABCD part of the isolator needs to be considered, as shown in FIG. 5, AB is a slip plane, and the safety factor is F s Is a limiting equilibrium condition of (2). The moment of the circle center O of the arc sliding surface is based on the moment of the circle center O of the arc sliding surface by the isolator, and the moment of the circle center O of the arc sliding surface is provided with
Wherein d 1 Is N 1 Arm of force d to centre of a circle 2 Force arm from G to circle center, d 3 Is T 2 And N 2 The arm of force from the vertical component to the center of the circle, and other parameters are the same as before.
In (4) and (5)And->Is the interaction force which can be counteracted by adding to obtain
Order the
Substituting the formula (2) and the formula (3) into the formula (6) to obtain X i+1 -X i =0, and finally obtaining the calculation formula of interlayer sliding out as follows
Wherein,,
in this embodiment, the specific operation steps of S2 are as follows:
when the gradient of the tailing dam is smaller and the cohesive force of the tailings is larger, the tailing dam of the die bag upstream method is easier to slide deeply past the die bag dam as shown in fig. 6 and 7. When deep sliding as shown in fig. 6 occurs, the analysis method is the same as the previous one, and ABCD is still considered as a pressed slope. From previous analysis, it can be deduced that the interaction forces between the isolator ABCD and the tailings sand are all internal forces, and that the overall moment balance equations are offset. The ABCD is subjected to stress analysis, so that four unknown forces exist, three balance equations can be listed under the condition of no redundant conditions, the problem of one hyperstatic problem cannot be solved, and two solutions are not needed. It is believed that the vertical pressure transmitted downward by the vertical force isolator imparted by the isolator to only the tailings sand portion conforms to the following, more conservative relationship, and that the vertical downward force F of the tailings sand horizontal portion y1 And vertical downforce F of inclined portion of tailings ore y2 Is collinear with the gravitational force G of the separator
Wherein θ is the included angle between the isolator and the horizontal plane, namely the slope of the dam slope;
order the
p i The uniform distribution force on the corresponding bar blocks is realized;
f when deep sliding is obtained s The calculation formula is that
Wherein,,c i the adhesive force of the ith soil strip; b i The width of the ith soil strip; g i Is the gravity of the ith soil strip; phi (phi) i The internal friction angle of the ith soil strip; alpha i Is the included angle between the sliding surface of the ith soil strip and the horizontal plane.
In this embodiment, the specific operation steps of S3 are as follows: and (3) programming a corresponding calculation program by using MATLAB, wherein the program adopts a step-by-step grid algorithm to search the most dangerous slip plane. To compare the stability of the tailings dam by the mould bag method with that of the tailings dam without the mould bag method, 3 groups of 6 models were calculated as shown in fig. 8. The scheme a is used for comparing and analyzing the stability of the tailings dam by the mould bag method and the tailings dam without the mould bag along with the change of the dam height under the condition that the slope ratio of the dam slope is unchanged; the scheme b compares and analyzes the stability of the tailings dam by the mould bag method and the tailings dam without the mould bag along with the change of the gradient under the condition of unchanged dam height; scheme c compares and analyzes the stability between the tailings dams of the die bag method of two different dam modes, wherein one dam mode is to start the construction from the top of the initial dam, and the other dam mode is to start the construction from the bottom of the inner side of the initial dam.
The detailed calculation parameters are shown in Table 1
TABLE 1
In the concrete calculation, a simplified Bishop strip separation method is adopted for the tailings dam without the mould bags; the tailings dam adopting the mould bag method adopts a calculation method derived in the text. The searching of the most dangerous slip surface of the tailings dam by the mould bag method is realized by the following steps:
calculating the minimum safety coefficient sliding out along the layers of the mould bag dams and the contact layers of the mould bag dams and the tailings according to the formula (7), and finding out the minimum safety coefficient and the corresponding sliding surface thereof;
calculating the minimum safety coefficient of the slip plane crossing the mould bag dam and the corresponding most dangerous slip plane by the method (11);
comparing the two safety factors, wherein the minimum safety factor is defined as the minimum safety factor of the tailings dam by the mould bag method, and the corresponding slip plane is the most dangerous slip plane. The calculation results only give the most dangerous slip plane and the minimum safety factor obtained according to the method.
The calculation result of the scheme a is shown in fig. 9, the change curve of the minimum safety coefficient of the tailings dam without the mould bags and the tailings dam without the mould bags along with the dam height is shown in fig. 10, and the tailings dam without the mould bags are continuously reduced along with the increase of the dam height. When the dam height is 62m, the safety coefficient of the tailings dam by the mould bag method is 1.296, and the safety coefficient of the tailings dam without the mould bag is 1.088; when the dam height reaches 90m, the safety coefficient of the tailings dam by the mould bag method is 1.057, and the tailings dam without the mould bag is unstable and damaged. Comparing the safety coefficients of the two tailings dams, the safety coefficient of the tailings dam by the mould bag method is always higher than that of the tailings dam without the mould bag in the process of increasing the whole dam height, but the increasing amplitude is smaller and smaller, and aiming at the calculation model, when the dam height is 62m, the tailings dam by the mould bag method is improved by 19 percent compared with the tailings dam without the mould bag; when the dam height is 90m, the dam height is improved by less than 6 percent. This shows that the mould bags have a significant stability improving effect only on the dam with a smaller height for the tailings dam of the upstream method, but the mould bags have a smaller stability improving effect when the dam height reaches a certain height. From the position of the most dangerous slip plane in fig. 9, the most dangerous slip plane of the tailings dam by the bag-in-mould method moves towards the interior of the dam body than the most dangerous slip plane of the tailings dam without the bag-in-mould method, which illustrates one of the reasons why the bag-in-mould method improves the stability of the dam body: the existence of the die bag pressure slope body promotes the potential sliding surface to move towards the inside of the dam body.
Because the initial dam is considered firm and stable, the height that actually affects the stability of the tailings dam is the total height of the dam minus the initial dam height.
The calculation result of the scheme b is shown in fig. 11, the change curves of the safety coefficients of the tailings dam without the mould bags and the tailings dam without the mould bags along with the gradient of the dam slope are shown in fig. 12, and when the dam is higher at a certain time, the safety coefficients of the tailings dam without the mould bags and the tailings dam without the mould bags are continuously improved along with the continuous decrease of the gradient of the dam slope. Comparing the safety coefficients of the two tailings dams, the safety coefficient of the tailings dam by the mould bag method is always higher than that of the tailings dam without the mould bag in the process of reducing the gradient of the whole dam slope, but the increasing amplitude is smaller and smaller as can be seen by the difference value between the two tailings dams. For the above calculation model, the slope ratio is 1:2, when the dam height is 78m, the tailings dam by the mould bag method is improved by about 14% compared with the tailings dam without the mould bag; the slope ratio is 1:4, when the dam height is 78m, the improvement is less than 3%. This means that when the slope of the dam slope is relatively small, the effect of the molding bag in improving the stability of the dam is not well exerted. The reason for this analysis is that when the slope ratio of the dam slope is small, the tailing dam is more likely to undergo deep sliding (a part of the sliding surface is concave downward), and when the bottom width of the die bag dam is not sufficiently large, the influence of the presence or absence of the die bag on the sliding surface is small. In the previous analysis, one of the reasons for the improved stability of the dam by the bag-in-mould method is that the presence of the bag-in-mould ramp moves the potential slip towards the interior of the dam. Therefore, when the die bags do not sufficiently affect the original slip plane, the stability of the die bags is not improved well.
When the dam height is smaller and the dam slope is larger, the existence of the mold bags has a relatively large effect on improving the stability of the dam body. However, there is a contradiction that when the gradient is relatively large, the stability of the mould bag is not very good although the effect of improving the stability of the mould bag is large, so that the mould bag tailing dam does not suggest to select too large gradient.
The calculation result of the scheme c is shown in fig. 13, and the purpose of the scheme c is to study the influence of the width of the molded bag dam on the overall stability of the molded bag tailings dam, and to study the stability of the improved molded bag tailings dam. The change curves of the safety coefficient with the dam width of the mould bag dam in two different dam piling modes are shown in fig. 14, and the dam piling mode 1 refers to the construction of the mould bag dam from the top of the initial dam; the fill method 2 refers to the filling of the mold bag dam from the bottom of the initial dam.
As the width of the mould bag dam becomes larger, the safety coefficient of the mould bag tailings dam is also improved, and the mould bag tailings dam are approximately in a linear relationship within the range shown in the figure. Comparing the safety coefficients of the two dam-stacking modes, the safety coefficient corresponding to the dam-stacking mode 2 is larger than that corresponding to the dam-stacking mode 1, and the wider the mould bag dam is, the larger the dam-stacking mode 2 plays a role in improving the stability of the dam body. This means that for the computational models and parameters herein, the stability of the tailings dams in the bag-in-mould process will be greatly improved if the slip resistance provided between the bags can be fully exploited. The dam height is 78m, and the dam slope ratio is: 1:2.5, the width of the bottom of the mould bag dam is 40m, the corresponding safety coefficient of the dam piling mode 2 is 1.324, the safety coefficient is improved by more than 18 percent compared with the dam piling mode 1, and the safety coefficient is improved by more than 29 percent compared with a mould bag-free tailing dam with the same dam height and slope ratio
In conclusion, the division of the strip blocks is consistent with the laying method of the die bag body, the theoretical derivation process is tight, and the calculation process is more accordant with the application state of the die bag body. Compared with the traditional calculation method, the method is basically consistent with the traditional calculation result when the die bag is relatively smaller in the overall dam height effect, and the applicability of the method in the stability analysis of the die bag method is verified.
The above description is only of the preferred embodiments of the present invention, and is not intended to limit the present invention. Any simple modification, variation and equivalent variation of the above embodiments according to the technical substance of the invention still fall within the scope of the technical solution of the invention.
Claims (5)
1. The method for calculating the stability of the tailings dam by the mould bag method is characterized by comprising the following operation steps of:
s1, obtaining a die bag interlayer sliding-out calculation formula based on a die bag interlayer sliding failure mode;
s2, obtaining a deep sliding calculation formula based on a deep sliding damage mode;
s3, comparing, calculating and analyzing;
the step S1 comprises the following steps:
s101, taking a part from the bottom end surface of a sliding part of the tailing dam to the top end surface of the tailing dam as an isolator, regarding the isolator as a rigid pressure slope body, and carrying out stress analysis on the isolator alone;
s102, working out interaction force between the isolator and the tailing sand through static balance conditions and limit balance conditions;
s103, uniformly distributing interaction force between the isolator and the tailing sand on the tailing sand, calculating the stability of the isolator by using a rigid body limit balance method without a mould bag, and calculating a stable safety coefficient of the isolator sliding synchronously along with the tailing sand;
s104, superposing a moment balance equation of the sliding part of the isolator and the tailing sand to obtain a calculation formula of the sliding damage between the layers of the die bags;
the step S2 comprises the following steps:
s201, carrying out stress analysis and simplifying treatment on the isolator;
s202, a moment balance equation of vertical force is listed;
and S203, uniformly distributing force through a moment balance equation, and finally obtaining a calculation formula of deep sliding.
2. The method for calculating the stability of the tailings dam by the die bagging method according to claim 1, wherein the specific operation steps of S1 are as follows:
s101, carrying out stress analysis on the isolator, and listing a balance equation by static balance conditions
Wherein N is 1 For supporting the spacer upwards with horizontal sliding surface, N 2 For supporting the tailing sand obliquely facing the separator vertically upwards, T 1 T is the friction force between horizontal sliding surfaces 2 G is the gravity of the separator, l is the width of the separator, θ is the included angle between the separator and the horizontal plane, namely the slope of the dam slope, and h is the height of the separator;
s102, the bottom end surface of the isolator is a sliding surface, and the sliding surface is in a limit balance state, thus obtaining
Wherein,,is the internal friction angle between the mould bag bodies;
solving to obtain T 1 、N 1 、T 2 And N 2 ;
S103、T 1 `、N 1 `、T 2 ' and N 2 The reaction forces of the spacers acting on the tailings sand are respectively T according to the relation between the acting force and the reaction force 1 =T 1 ',T 2 =T 2 ',N 1 =N 1 ',N 2 =N 2 ' assuming that the tailing dam body is divided into m soil strips, for the horizontal slip plane part, the vertical distribution force and the horizontal distribution force acting on the ith soil strip are respectively p 1i And q 1i To represent; for the slope part, the vertical distribution force and the horizontal distribution force acting on the ith soil strip are respectively p 2i And q 2i To express, then
When i is more than or equal to 1 and less than or equal to m
When m < i
Carrying out stress analysis on the ith soil strip, wherein the ith soil strip is in a static equilibrium state in the vertical direction by the strip block i, and the ith soil strip meets the safety factor of F s Is limited in balance condition of (1)
Wherein G is i '=G i +p 2i b i +q 2i b i tgθ,T i C is the friction force on the sliding surface of the ith soil strip i For the cohesion of the tailings, l i For the length of the sliding surface of the ith soil strip, N i For the vertical upward supporting force applied to the ith earth bar i G is the internal friction angle of the tailing sand i B is the gravity of the ith soil strip i For the i-th horizontal width of the soil strip, X i Is the shearing force applied to the left side of the ith soil strip, X i+1 Is the shearing force alpha applied to the right side of the ith soil strip i Other parameters are defined as before for the included angle between the sliding surface and the horizontal plane.
3. The method for calculating the stability of the tailings dam by the die bagging method according to claim 2, wherein the specific operation steps of S104 are as follows:
moment is taken from the circle center of the arc sliding surface, and the moment balance equation of the tailing sand sliding part is that
Wherein R is the radius of the arc sliding surface, h i Defining the same parameters as before for the vertical distance from the top surface of the ith soil strip to the far point;
based on the distance of the center of the circle of the arc sliding surface taken by the isolator, there are
Wherein d 1 Is N 1 Arm of force d to centre of a circle 2 Force arm from G to circle center, d 3 Is T 2 And N 2 The arm of force from the vertical component to the center of the circle, and other parameters are the same as before;
in (4) and (5)And->Is the interaction force which can be counteracted by adding to obtain
Order the
Substituting the formula (2) and the formula (3) into the formula (6) to obtain X i+1 -X i =0, and finally obtaining the calculation formula of the safety coefficient when the interlayer slides out
Wherein,,
4. the method for calculating the stability of the tailings dam by the die bagging method according to claim 1, wherein the specific operation steps of S2 are as follows:
the vertical pressure transmitted downwards by the isolator accords with the following partial conservation relation, and the vertical downward force F of the horizontal part of the tailing sand y1 And vertical downforce F of inclined portion of tailings sand y2 Is collinear with the gravitational force G of the separator
Wherein θ is the included angle between the isolator and the horizontal plane, namely the slope of the dam slope;
order the
p i The uniform distribution force on the corresponding bar blocks is realized;
f when deep sliding is obtained s The calculation formula is that
Wherein,,c i the adhesive force of the ith soil strip; b i The width of the ith soil strip; g i Is the gravity of the ith soil strip; phi (phi) i The internal friction angle of the ith soil strip; alpha i Is the included angle between the sliding surface of the ith soil strip and the horizontal plane.
5. The method for calculating the stability of the tailings dam by the die bagging method according to claim 1, wherein the specific operation steps of S3 are as follows: and (3) programming a corresponding calculation program by using MATLAB, calculating a plurality of groups of models, calculating the stability of the non-mould bag tailing dam by using a Bishop strip division method, and comparing and analyzing a plurality of data to verify the scientificity of a calculation mode.
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CN117745466B (en) * | 2024-02-21 | 2024-04-26 | 中国有色金属工业昆明勘察设计研究院有限公司 | Tailing pond counting intelligent operation and maintenance system |
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