CN116046635A - Large-particle-size high-porosity rock constant head permeation experiment device and method - Google Patents
Large-particle-size high-porosity rock constant head permeation experiment device and method Download PDFInfo
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- 239000011435 rock Substances 0.000 title claims abstract description 293
- 238000002474 experimental method Methods 0.000 title claims abstract description 91
- 238000000034 method Methods 0.000 title claims abstract description 47
- 230000003204 osmotic effect Effects 0.000 claims abstract description 303
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 154
- 230000008595 infiltration Effects 0.000 claims abstract description 17
- 238000001764 infiltration Methods 0.000 claims abstract description 17
- 230000008569 process Effects 0.000 claims abstract description 16
- 230000035515 penetration Effects 0.000 claims description 48
- 238000007789 sealing Methods 0.000 claims description 20
- 239000002245 particle Substances 0.000 claims description 19
- 229910001220 stainless steel Inorganic materials 0.000 claims description 19
- 239000010935 stainless steel Substances 0.000 claims description 19
- 238000012360 testing method Methods 0.000 claims description 19
- 239000003822 epoxy resin Substances 0.000 claims description 17
- 229920000647 polyepoxide Polymers 0.000 claims description 17
- 239000003292 glue Substances 0.000 claims description 16
- 230000035699 permeability Effects 0.000 claims description 16
- 239000012466 permeate Substances 0.000 claims description 14
- 239000004568 cement Substances 0.000 claims description 7
- 238000005520 cutting process Methods 0.000 claims description 7
- 238000003860 storage Methods 0.000 claims description 7
- 230000001133 acceleration Effects 0.000 claims description 6
- 239000011521 glass Substances 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 6
- 230000000149 penetrating effect Effects 0.000 claims description 6
- 238000007711 solidification Methods 0.000 claims description 5
- 230000008023 solidification Effects 0.000 claims description 5
- 230000008859 change Effects 0.000 claims description 4
- 229920006395 saturated elastomer Polymers 0.000 claims description 4
- 238000002791 soaking Methods 0.000 claims description 4
- 230000005484 gravity Effects 0.000 claims description 3
- 230000000087 stabilizing effect Effects 0.000 claims description 3
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- 239000010438 granite Substances 0.000 description 2
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
The invention discloses a large-particle-size high-porosity rock constant head permeation experiment device and method. The experimental device comprises a rock infiltration bin, an osmotic pressure supply unit, an osmotic pressure control unit and a data acquisition unit. The rock infiltration bin is used for accommodating experimental large-particle-size high-porosity rock; the osmotic pressure supply unit is used for inputting high-flow osmotic water with stable osmotic pressure into the rock osmotic bin; the osmotic pressure control unit is used for driving a servo motor in the osmotic pressure supply unit, so that the servo motor drives a plunger type pressure pump through a roller screw pair to convey osmotic water into the rock osmotic bin; the data acquisition unit is used for acquiring osmotic pressure and osmotic water output flow in the osmotic experiment process, transmitting the osmotic pressure and the osmotic water output flow to the osmotic pressure control unit, and controlling the osmotic pressure supply unit. The invention can meet the requirements of rock permeation experiments containing large-particle-size gravels and high-porosity rocks, and provides a set of effective experimental equipment and experimental method for permeation experiments of rock types with larger permeation coefficients.
Description
Technical Field
The invention relates to a permeation experiment device and method, in particular to a device and an experiment method for carrying out constant head permeation experiments on rocks containing large-particle-size gravels and high in porosity. The invention belongs to the technical field of experimental instruments and experimental methods in the field of geotechnical engineering and hydraulic engineering.
Background
With the increasing of the construction force of the water conservancy and hydropower engineering in the Xinjiang area in recent years, the water conservancy and hydropower engineering projects in the area are gradually increased, and the engineering characteristics of the conglomerates in the Western area are more and more concerned. The current research literature on western conglomerates is very few, and the research mainly focuses on geologic causes, and the research on western conglomerate engineering characteristics is almost blank. For hydraulic and hydroelectric engineering, the permeability characteristics of engineering rock mass are often of great value for safety assessment of engineering.
However, in spite of the current research situation, the existing rock penetration experiment device and method are only limited to the rock with high compactness, low porosity and small permeability coefficient, whereas western conglomerate has different specificity from the common rock, and often has the characteristics of large-grain gravel, low rock density and high porosity, so the existing rock penetration experiment device and method are not suitable for researching the penetration characteristics of the rock with high porosity such as western conglomerate.
The main reasons why the existing rock penetration experimental device is not suitable for the research of high-porosity rock (such as western conglomerate) are as follows:
1. the flow of a water pump in the existing permeation experiment device can not meet the experiment requirement of high-porosity rock. The water flow output and the pressure output of the water pump are a pair of contradictory parameters, and in general, the water flow output is small, and the output pressure is large; the output quantity of water flow is large, and the output pressure is small. For highly dense, low porosity rock (e.g. granite permeability of the order of 10 -9 -10 -7 cm/s), the existing permeation experimental device can meet the experimental requirements of the permeation experimental device because the permeation flow output determined by the physical properties is small. However, for high porosity rock (e.g. western conglomerates, the permeability coefficient can be of the order of 10 -5 ～10 -4 cm/s), and the requirement for stable osmotic pressure in the experiment of measuring the osmotic coefficient by the constant head method is stable, so the conventional osmotic experiment device cannot meet the requirement for stable large flow and osmotic pressure of the high-porosity rock osmotic experiment, namely, the requirement for large flow output is met, and the stable osmotic pressure is maintained when the large flow output is provided.
2. The osmotic pressure control precision of the existing osmotic experimental device can not meet the experimental requirements of high-porosity rock. The control precision of the osmotic pressure of the existing rock osmotic experimental device is at least 0.1MPa, and the osmotic pressure experimental device has the advantages of low porosity and low osmotic coefficient (the osmotic coefficient is at least 10) -9 -10 -7 cm/s), the pressure control precision of 0.1MPa is enough to meet the experimental requirements; however, for high porosity, high permeability coefficient (permeability coefficient of the order of 10 -5 ～10 -4 cm/s), the cutoff error brought by the pressure control precision of 0.1MPa can cause huge error to the experimental result, so the existing permeation experimental device can not meet the requirements of the permeation experimental pressure control precision of the rock with high porosity and high permeation coefficient, namely, the permeation pressure control precision is required to be at least 0.001MPa.
3. Existing permeation experimental deviceThe sleeve specifications in the inner can not meet the experimental requirements of rock samples containing large particle size gravel. The prior penetration experiment device is mostly based on the standard rock sample size
The designed sample sleeve usually has the diameter of the gravel contained in the rock containing the large-particle-size gravel reaching 1-100 mm, so that the conventional penetration experiment device cannot meet the size requirement of penetration experiment samples of the rock containing the large-particle-size gravel (such as western conglomerate), namely, the sleeve of the experiment device is required to meet the capability of carrying out penetration experiments on rock samples with different specifications (the samples are cylindrical, and the diameters are changed within 250mm and the thicknesses are changed within 200 mm).
Disclosure of Invention
In view of the above, the present invention aims to provide a permeation experiment device and method for constant head permeation experiment suitable for large-grain-size and high-porosity rock.
In order to achieve the above purpose, the present invention adopts the following technical scheme: a constant head penetration experiment method for large-grain-size high-porosity rock comprises the following steps:
s1, preparing a cylindrical rock sample with large particle size and high porosity;
selecting a high porosity rock as such containing intact large particle size gravel; cutting the selected rock to obtain a cylindrical rock sample required by experiments; checking the integrity of the cylindrical rock sample; measuring a physical parameter of a cylindrical rock sample;
The relationship between the size of the cylindrical rock sample and the maximum gravel size contained therein should satisfy the following requirements:
wherein ,
represents the average diameter of a cylindrical rock sample; />
Representing the average thickness of a cylindrical rock sample; d, d max Representing the maximum gravel diameter contained in the rock sample;
s2, selecting a conical sleeve with corresponding size, placing a cylindrical rock sample, and sealing between the cylindrical rock sample and the inner wall of the sleeve;
s2.1, selecting a conical sleeve matched with the rock sample, and installing a cylindrical rock sample;
the relationship between the selected conical sleeve size and the cylindrical rock sample size is:
wherein ,
representing the inner diameter of the sleeve in mm; />
Mean diameter in mm of a cylindrical rock sample; />
Represents the average thickness in mm of a cylindrical rock sample; l (L) c The sleeve height in mm; />
The symbology is rounded up; />
The symbolic representation is rounded down;
inverting the conical sleeve, namely arranging a small inner diameter opening downwards and a large inner diameter opening upwards, and placing a cylindrical rock sample into the sleeve from one end with a large opening at the bottom of the conical sleeve;
s2.2, edge sealing by glass cement;
at the moment, the conical sleeve is still in an inverted state, and glass cement which is difficult to flow and has high viscosity is used for plugging the lower edge of a gap between the cylindrical rock sample and the inner wall of the conical sleeve;
S2.3, sealing;
at this time, the conical sleeve is still in an inverted state, and epoxy resin glue with smaller viscosity and easy flow is injected from the gap between the outer surface of the cylindrical rock sample and the inner wall of the conical sleeve until the epoxy resin glue fills all the gaps between the rock sample and the inner wall of the conical sleeve;
after the sleeve is inverted and kept stand for 24 hours, waiting for the solidification of the epoxy resin glue, if a gap is still reserved between the rock sample and the inner wall of the conical sleeve at the moment, continuing to add the epoxy resin glue with smaller viscosity and easy flow until the epoxy resin glue fills all gaps between the rock sample and the inner wall of the stainless steel sleeve and is kept stand for solidification;
s3, assembling the rock permeation bin and checking the tightness of the permeation bin body.
S4, connecting the osmotic pressure supply unit, the osmotic pressure control unit and the data acquisition unit, exhausting and starting the experiment.
S5, osmotic pressure loading, namely pressure step-by-step loading is carried out on the rock sample.
S5.1, loading osmotic pressure and applying osmotic water;
the initial osmotic pressure applied by the osmotic pressure control unit is 0.001MPa, and the osmotic pressure is kept for 2.5-3 h; then, loading osmotic pressure step by step, increasing the osmotic pressure by 0.001MPa each time and keeping for 2.5-3 hours until the rock sample starts to permeate for the first time;
In the process of applying osmotic pressure and inputting osmotic water into a rock osmotic bin, observing the osmotic condition of rock, when a rock sample starts to permeate for the first time, namely a water film is formed on the upper surface of the rock sample, recording the osmotic pressure p and the flow Q at the moment, finishing an osmotic experiment at this moment, continuously increasing the osmotic pressure, and repeating the following osmotic experiment steps, wherein the difference is that the osmotic pressure and the flow recorded in each osmotic experiment change;
s5.2 soaking in water for 24 hours, 48 hours and 72 hours, and repeating the permeation experiment;
repeating the saturated sample permeation experiments for three times after the sample is soaked for 24h, 48h and 72h respectively, wherein the osmotic pressure loading step is the same as that of S5.1, and the osmotic pressure and flow data of the experiment are required to be recorded;
s6, collecting experimental data, and calculating the permeability coefficient of the rock with large particle size and high porosity;
in the process of reading the osmotic experiment, experimental data measured by an osmotic pressure sensor, a first electromagnetic flowmeter, a second electromagnetic flowmeter and a water-encountering alarm are read, and the osmotic coefficient k of a rock sample is calculated according to the following calculation formula:
wherein Q is the flow in unit time measured by the sleeve water inlet flowmeter, V is the seepage volume in the time of pressure-stabilizing seepage t, t is the pressure-stabilizing seepage time, 
Is the average thickness of the cylindrical rock sample, A is the surface area of the bottom surface of the cylindrical rock sample, deltaH is the osmotic head difference, deltap is the osmotic pressure difference, p is the osmotic pressure measured by an osmotic pressure sensor, ρ is the density of the osmotic liquid, g is the gravitational acceleration, & lt, & gt>
Average diameter of sample, D 1 、D 2 、D 3 、D 4 Respectively represent the diameters of different positions of the cylindrical sample, L 1 、L 2 、L 3 、L 4 Respectively representing the thicknesses of different positions of the cylindrical sample;
the formula (3) is integrated and deduced to calculate the osmotic coefficient k as follows:
wherein k is the permeability coefficient in cm/s; ρ isDensity of permeated liquid in g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the g is gravity acceleration, unit m/s 2 The method comprises the steps of carrying out a first treatment on the surface of the L is the thickness of the cylindrical rock sample in cm; v is the seepage volume in the time of pressure-stabilizing seepage t, and the unit cm 3 The method comprises the steps of carrying out a first treatment on the surface of the Δp is the osmotic pressure difference in MPa; a is the surface area of the bottom surface of a cylindrical rock sample, and the unit is cm 2 The method comprises the steps of carrying out a first treatment on the surface of the t is the pressure stabilizing seepage time, and the unit is s.
In order to achieve the aim of the invention, the invention adopts the following technical scheme: an experimental device for realizing a constant head permeation experimental method of large-particle-size high-porosity rock comprises a rock permeation bin, a permeation pressure supply unit, a permeation pressure control unit and a data acquisition unit;
the rock penetration bin is used for containing experimental large-particle-size high-porosity cylindrical rock samples;
The osmotic pressure supply unit is used for inputting high-flow osmotic water with stable osmotic pressure into the rock osmotic bin;
the osmotic pressure control unit is used for driving the osmotic pressure supply unit to convey high-flow osmotic water with stable osmotic pressure into the rock osmotic bin;
the data acquisition unit is used for acquiring experimental data in the experimental process and transmitting the experimental data to the osmotic pressure control unit;
the osmotic pressure supply unit is connected with the rock osmotic bin through a high-pressure water pipeline, the osmotic pressure control unit is connected with the osmotic pressure supply unit through a circuit, and the data acquisition unit is connected with the rock osmotic bin, the osmotic pressure supply unit and the osmotic pressure control unit through circuits to form a closed-loop feedback control system.
Preferably, the rock penetration bin is composed of a conical sleeve and a flange plate base; the conical sleeve is connected with the flange plate base through bolts; the flange plate base is detachably fixed on an operation platform; a water inlet penetrating through the operation platform is formed in the center of the flange plate base; a water outlet is formed in the upper part of the side surface of the conical sleeve; an O-shaped sealing ring is arranged between the conical sleeve and the flange plate base.
Preferably, the relationship between the conical sleeve and its internal cylindrical rock sample is:
wherein ,
representing the inner diameter of the sleeve in mm; />
Mean diameter in mm of a cylindrical rock sample; />
Represents the average thickness in mm of a cylindrical rock sample; l (L) c The sleeve height in mm; />
The symbology is rounded up; />
The symbology is rounded down.
Preferably, the conical sleeve and the flange base forming the rock penetration bin are a series of reducing sleeves and bases, and the specification of the conical sleeve needs to meet
wherein />
Indicating the inner diameter of the sleeve>
Indicating the lower inner diameter of the sleeve, L c Indicating the sleeve height.
Preferably, the osmotic pressure supply unit comprises a servo motor, a roller screw pair, a plunger type pressure pump, a water storage tank, a three-way joint, a one-way valve, an exhaust valve and a switch valve; an output shaft of the servo motor is connected with a piston in the plunger type pressure pump through the roller screw pair to push the piston to reciprocate; the water inlet of the plunger type pressure pump is connected with the water storage tank through a proportional valve, and the water outlet of the plunger type pressure pump is connected with the water inlet at the bottom of the rock permeation bin through the three-way joint, the one-way valve and the switching valve which are connected in series and the high-pressure water conveying pipeline; and a pipeline branch is led out from the high-pressure water conveying pipeline, and the exhaust valve is arranged on the pipeline branch.
Preferably, the osmotic pressure range output by the osmotic pressure supply unit is 0.002MPa-0.500MPa, and the output osmotic flow is more than 300ml/min; the control precision of the osmotic pressure control unit is 0.001MPa.
Preferably, the data acquisition unit comprises an osmotic pressure sensor, a first electromagnetic flowmeter, a second electromagnetic flowmeter, a water meeting alarm and a computer; the osmotic pressure sensor is arranged at the water outlet of the plunger type pressure pump and is used for measuring the pressure at the water outlet of the plunger type pressure pump;
the first electromagnetic flowmeter is arranged in the water inlet water delivery pipeline of the rock permeation bin and is used for measuring the permeation flow rate input into the rock permeation bin;
the second electromagnetic flowmeter is arranged in a water outlet pipeline at the water outlet at the upper part of the side surface of the conical sleeve and is used for measuring the seepage flow discharged by the cylindrical rock sample;
a vertical guide rail is fixed beside the conical sleeve, the water-contacting alarm is arranged on the guide rail, and a feeler wire of the water-contacting alarm extends into the conical sleeve and is placed on the upper surface of the rock sample;
the data output ends of the osmotic pressure sensor, the first electromagnetic flowmeter, the second electromagnetic flowmeter and the water meeting alarm are connected with the data input end of the osmotic pressure control unit in a wired or wireless mode, and are connected with the data input end of the computer.
Compared with the existing rock penetration experimental device and method, the invention has the beneficial effects that:
1. the invention effectively solves the problem that the flow of the water pump in the existing permeation experimental device can not meet the demand of the high-porosity rock permeation experiment, and realizes the output of large-flow permeation water on the premise of keeping the permeation pressure stable. The invention adopts the rock osmotic bin, the osmotic pressure supply unit, the osmotic pressure control unit and the data acquisition unit to carry out closed-loop feedback control, the plunger type pressure pump of the osmotic pressure supply unit is controlled by the osmotic pressure control unit to provide stable osmotic pressure for the osmotic experiment device, and meanwhile, the osmotic pressure provided by the osmotic pressure supply unit is monitored by an osmotic pressure sensor in real time and is fed back to the osmotic pressure control unit, so that the osmotic pressure is ensured to be stable. Under the premise that the target osmotic pressure is kept stable, the cross-sectional area of the piston of the plunger type pressure pump is increased, so that the osmotic water flow provided by the osmotic pressure supply unit can be increased, the high-flow output under the stable pressure of the experiment requirement is met, and the high-precision flow sensor is adopted to monitor the osmotic water flow in the experiment process in real time, so that the smooth performance of the high-porosity rock osmotic experiment is ensured.
2. The invention effectively solves the problem that the control precision of the osmotic pressure of the traditional osmotic experimental device can not meet the experimental requirement of the rock with high porosity, and effectively reduces the cut-off error of the experimental device with low precision to the osmotic test of the rock with high porosity. The invention adopts a more sensitive osmotic pressure sensor and an osmotic pressure supply unit with higher controllable precision, wherein the minimum display precision of the osmotic pressure sensor is 0.0001MPa; the osmotic pressure supply unit adopts the rotary motion of the roller screw pair to drive the piston to reciprocate so as to control the osmotic pressure, and the reciprocating motion distance of the piston driven by 1 wire of the roller screw pair is reduced, so that the pressure control precision of the system is improved, and the controllable precision can reach 0.001MP. The osmotic pressure supply unit adopts a plunger type pressure pump capable of being finely adjusted, continuously and finely adjusts osmotic pressure, and is matched with the osmotic pressure control unit, so that the osmotic pressure precision of the osmotic device is greatly improved.
3. The invention effectively solves the problem that the sleeve specification of the traditional penetration experiment device can not meet the experiment requirement of rock samples containing large-particle-size gravels. The invention designs a series of sleeves with different specifications and sizes, and the series of sleeves are suitable for the permeation experiment of cylindrical rock samples with the thickness of 50-200 mm and the diameter of 50-250 mm and containing gravels with large particle sizes in any size. Meanwhile, the invention also provides a matching standard between the sleeve specification and the rock sample containing the gravels with different diameters, and provides an applicable range of the maximum gravels with different specifications and sizes, thereby meeting the experimental requirements of the rock sample containing the gravels with large particle sizes.
4. The invention breaks through the limit that one set of experimental device can only perform experiments on rocks of the same type. The components of the invention can exist independently and are connected with each other through a high-pressure water transmission pipeline and a general data line. For rock samples of different sizes (e.g. conventional rock samples are typically of size
The size of the gravel rock sample with large particle size is related to the maximum gravel diameter, and the experiment can be carried out only by replacing the rock permeation bin with the corresponding size; for rock of different permeability coefficient orders (e.g. granite permeability coefficient orders of 10 -9 -10 -7 Between cm/s, the permeability coefficient of the conglomerate in the Western area is of the order of 10 -5 ～10 -4 cm/s), only the sensor of corresponding magnitude needs to be replaced.
Drawings
FIG. 1 is a schematic diagram of a large-particle-size high-porosity rock constant head permeation experiment device;
FIG. 2 is a schematic diagram of a rock penetration bin perspective structure of the penetration experiment device of the invention;
FIG. 3A is a schematic view of the longitudinal cross-sectional structure of a rock penetration bin of the penetration test apparatus of the present invention;
FIG. 3B is a schematic view of the partial enlarged structure of A in FIG. 3A;
FIG. 4A is a schematic top perspective view of a flange plate base of a rock penetration bin of the penetration test apparatus of the present invention;
FIG. 4B is a schematic top view of the flange plate base of the rock penetration bin of the penetration test apparatus of the present invention;
FIG. 4C is a schematic side sectional view of a flange plate base of a rock penetration bin of the penetration test apparatus of the present invention;
FIG. 4D is a schematic bottom perspective view of the flange plate base of the rock penetration cartridge of the penetration test apparatus of the present invention;
FIG. 4E is a schematic view of the bottom structure of the flange plate base of the rock penetration cartridge of the penetration test apparatus of the present invention;
FIG. 5A is a schematic perspective view of a stainless steel sleeve of a rock penetration bin of the penetration test apparatus of the present invention;
FIG. 5B is a schematic side sectional view of a stainless steel sleeve of a rock penetration bin of the penetration test apparatus of the present invention;
FIG. 5C is a schematic top view of a stainless steel sleeve of a rock penetration bin of the penetration test apparatus of the present invention;
FIG. 5D is a schematic view showing the bottom structure of a stainless steel sleeve of a rock penetration cartridge of the penetration test apparatus of the present invention;
FIG. 6 is a schematic diagram of the osmotic pressure supply unit of the osmotic test device according to the present invention;
FIG. 7 is a flow chart of the permeation experiment performed by using the large-particle-size high-porosity rock constant head permeation experiment device.
The device comprises a 1-rock infiltration bin, a 11-operation platform, a 111-water delivery hole, a 112-pin hole, a 12-sleeve, a 121-water outlet, a 122-skirt, a 1221-screw-free bolt hole, a 13-flange base, a 131-water inlet, a 132-screw-equipped bolt hole, a 133-locating pin, a 14-bolt and a 15-O-shaped sealing ring; 2-osmotic pressure supply unit, 21-servo motor, 22-roller screw pair, 23-plunger type pressure pump, 231-piston, 232-high pressure water bin, 24-water storage tank, 25-three-way joint, 26-one-way valve, 27-exhaust valve, 28-switch valve and 29-proportional valve; 3-osmotic pressure control unit; the system comprises a data acquisition unit 4, a penetrating pressure sensor 41, a first electromagnetic flowmeter 42, a second electromagnetic flowmeter 43, a water-meeting alarm 44, a guide rail 441, a 442-feeler wire and a computer 45; 5-high pressure water delivery pipeline.
Detailed Description
The structure and features of the present invention will be described in detail below with reference to the accompanying drawings and examples. It should be noted that various modifications can be made to the embodiments disclosed herein, and thus, the embodiments disclosed in the specification should not be taken as limiting the invention, but merely as exemplifications of embodiments, which are intended to make the features of the invention apparent.
As shown in fig. 1-6, the large-particle-size high-porosity rock constant head infiltration experimental device disclosed by the invention comprises a rock infiltration bin 1, an osmotic pressure supply unit 2, an osmotic pressure control unit 3 and a data acquisition unit. The rock infiltration bin 1 is used for accommodating large-particle-size high-porosity rock for experiments; the osmotic pressure supply unit 2 is used for inputting high-flow osmotic water with stable osmotic pressure into the rock osmotic bin 1; the osmotic pressure control unit 3 is used for driving a servo motor 21 in the osmotic pressure supply unit 2, so that the servo motor drives a plunger type pressure pump 23 through a roller screw pair 22, and high-flow osmotic water with stable osmotic pressure is conveyed into the rock osmotic bin 1; the data acquisition unit is used for acquiring experimental data in the experimental process and transmitting the experimental data to the osmotic pressure control unit 3. The osmotic pressure supply unit 2 is connected with the rock osmotic bin 1 through a high-pressure water transmission pipeline 5, and the osmotic pressure control unit 3 is connected with the osmotic pressure supply unit 2 through a circuit; the data acquisition unit is in circuit connection with the rock infiltration bin 1, the osmotic pressure supply unit 2 and the osmotic pressure control unit 3 to form a closed-loop feedback control system.
As shown in fig. 1 to 3B, the rock penetrating cartridge 1 is composed of a sleeve 12 and a flange base 13, and the sleeve 12 is fixed to the operation platform 11 by the detachable flange base 13. A water delivery hole 111 is formed in the center of the operation platform 11; the center of the flange base 13 is provided with a water inlet 131 communicated with the water delivery hole 111, the flange base 13 is fixed on the operating platform 11 through a locating pin 133, and the sleeve 12 is fixed with the flange base 13 through a bolt 14. A water outlet 121 is provided in the upper side of the sleeve 12. An O-ring 15 is provided between the sleeve 12 and the flange base 13.
As shown in fig. 4A to 4E, the flange base 13 is a lower sealing stainless steel flange base, a water inlet 131 is formed at the center of the flange base, a plurality of bolt holes 132 with internal threads for connecting with the sleeve 12 are formed on the outer periphery of the flange base, and a plurality of positioning pins 133 for connecting with the operation platform 11 are arranged on the back surface of the flange base.
As shown in fig. 2, 3A and 3B, the operation platform 11 is provided with pin holes 112 corresponding to the flange bottom seat back positioning pins 133. When the flange is installed, the locating pin 133 on the back of the flange base is inserted into the pin hole 112, and the water inlet 131 is aligned with the water delivery hole 111 in the center of the operating platform 11.
As shown in fig. 5A-5D, the sleeve 12 is a conical stainless steel sleeve, and a ring of skirt 122 extends outwards from the bottom of the sleeve, and the skirt 122 is integrally formed with the sleeve body. A plurality of unthreaded bolt holes 1221 are provided in the skirt 122 at intervals for connection to the flange base 13. When in installation, the bolt holes 1221 on the skirt 122 at the bottom of the sleeve are aligned with the threaded holes 132 on the base 13 of the flange, and the bolts 14 are inserted into the bolt holes to connect and fix the two.
The invention designs the sleeve 12 to be conical, which has the advantages that: 1. the rock sample is convenient to install; 2. when penetrating water with certain pressure is input into the sleeve from the bottom of the sleeve, the conical inner wall of the sleeve can apply downward reaction force to the rock sample to prevent the rock sample from sliding, so that experimental errors are prevented, and experimental results are more accurate.
In order to meet the experimental requirements of rock samples with different sizes, the conical stainless steel sleeve 12 and the flange base 13 forming the penetration experimental device of the invention are a series of variable diameter sleeves and bases which contain six different specifications except for meeting the characteristics of the sleeve 12 and the flange base 13, and the variable diameter sleeves and the bases are respectively 
wherein ,
representing the inner diameter of the sleeve in mm; />
Mean diameter in mm of a cylindrical rock sample; />
Represents the average thickness in mm of a cylindrical rock sample; l (L) c The sleeve height in mm; />
The symbology is rounded up; />
The symbology is rounded down.
As shown in fig. 1 and 6, the osmotic pressure supply unit 2 of the present invention includes a servo motor 21, a roller screw pair 22, a plunger type pressure pump 23, a water storage tank 24, a three-way joint 25, a check valve 26, an exhaust valve 27, and an on-off valve 28.
An output shaft of the servo motor 21 is connected with a piston 231 in a plunger type pressure pump 23 through a roller screw pair 22 to push the plunger type pressure pump to reciprocate. The water inlet of the plunger type pressure pump 23 is connected with the water storage tank 24 through the proportional valve 29, and the water outlet of the plunger type pressure pump 23 is connected with the water inlet 131 of the rock permeation bin flange plate base 13 through the three-way joint 25, the series check valve 26 and the switch valve 28 and the high-pressure water delivery pipeline 5.
A line branch is also led out of the high-pressure water line 5 between the switching valve 28 and the non-return valve 26, on which a venting valve 27 is mounted. Before the permeation experiment device starts to work, the check valve 26 and the exhaust valve 27 are opened, the switch valve 28 is closed, the servo motor 21 is started, the plunger type pressure pump 23 is pushed to work through the roller screw pair 22, air in the high-pressure water conveying pipeline 5 is discharged, the exhaust valve 27 is closed, the switch valve 28 is opened, and permeation water with certain pressure is pumped into the rock permeation bin 1.
In order to enable the permeation testing device to meet the requirement of large-particle-size and high-porosity rock permeation test on large permeation flow, the pressure receiving area of the piston 231 in the plunger type pressure pump 23 is increased. Maximum thrust F of plunger type pressure pump 23 when maximum output power of servo motor 21 is unchanged max Unchanged, F max ＝A Plunger piston *σ max, wherein APlunger piston Is the compression area of the piston, sigma max Is the maximum osmotic pressure that can be achieved by the pressure pump. Aiming at the characteristics of large grain diameter, low osmotic pressure and large osmotic flow of high porosity rock, the invention reduces the maximum osmotic pressure sigma max Piston force bearing area A Plunger piston The amount of permeate water pushed into the rock permeate cartridge stainless steel sleeve 12 can be correspondingly increased, i.e. the piston moves forward the same distance. The servo motor 21 drives the roller screw pair 22 to advance by the same thrust for the same length, so that the requirement of flow increase can be met, and meanwhile, the stability of osmotic pressure is ensured as the output power of the servo motor and the length of the roller screw pair are unchanged. The osmotic pressure supply unit 2 has the output of large-flow osmotic water on the premise of ensuring the stable supply of target osmotic pressure, namely, the flow of the osmotic water pushed into the rock osmotic bin is large.
In the preferred embodiment of the present invention, the compression area of the piston 231 is 380cm 2 . On the basis that the osmotic pressure control unit maintains any osmotic pressure between 0.002MPa and 0.500MPa to be stable, the osmotic pressure supply unitThe permeation flow rate of the element output can reach>High flow rate of 300ml/min is required (the maximum of the existing permeation test device can reach 100 ml/min).
In the preferred embodiment of the invention, the osmotic pressure control unit 3 selects a special servo motor controller customized and developed by Jinan rock company, and comprises a special control chip for controlling a servo motor, wherein the special control chip is provided with a function of directly receiving a pressure value signal of an osmotic pressure sensor and adjusting the servo motor in real time to drive a roller screw pair to rotate, so that the osmotic pressure is continuously and finely adjusted, and closed-loop feedback control of osmotic pressure, osmotic pressure sensor, servo motor, pressure pump and osmotic pressure is realized, and regulated output is realized. The control precision of the osmotic pressure control unit can reach 0.001MPa, the osmotic pressure supply unit adopts a plunger type pressure pump capable of being finely adjusted, the osmotic pressure is continuously and finely adjusted, and the osmotic pressure supply unit is matched with the osmotic pressure control unit, so that the osmotic pressure precision of the osmotic device is greatly improved.
As shown in fig. 1, the data acquisition unit includes an osmotic pressure sensor 41, a first electromagnetic flowmeter 42, a second electromagnetic flowmeter 43, a water-meeting alarm 44, and a computer 45. The osmotic pressure sensor 41 is arranged at the water outlet of the plunger type pressure pump 23 and is used for measuring the pressure at the water outlet of the plunger type pressure pump; a first electromagnetic flowmeter 42 is installed in the water delivery pipeline of the rock penetration cartridge water inlet 131 for measuring the flow rate of penetration water input into the rock penetration cartridge. A second electromagnetic flowmeter 43 is mounted in the water outlet line at the upper water outlet 121 of the sleeve side for measuring the permeate flow rate discharged through the high porosity rock. As shown in FIG. 1, an upstanding rail 441 is secured adjacent the stainless steel sleeve 12, and a water-encountering alarm 44 is mounted on the rail 441 with the feeler wire 442 of the water-encountering alarm 44 extending into the sleeve 12 for placement on the upper surface of the rock specimen. As the level of the permeate water in the casing 12, which is displaced through the high porosity rock, rises, the sounding wire 442 senses the permeate water and immediately alarms.
The data output ends of the osmotic pressure sensor 41, the first electromagnetic flowmeter 42, the second electromagnetic flowmeter 43 and the water meeting alarm 44 are connected with the data input end of the osmotic pressure control unit 3 in a wired or wireless mode, and are connected with the data input end of the computer 45.
The osmotic pressure control unit 3 controls the servo motor 22 according to the data acquired by the sensor, and further controls the reciprocating progress of the piston 231 in the plunger type pressure pump 23.
The computer 45 collects the data output by the sensors and calculates the permeability coefficient of the rock under test.
In order to make the osmotic experimental device of the invention have higher osmotic pressure control precision, the invention selects an osmotic pressure sensor 41 with minimum display precision of 0.0001MPa and an osmotic pressure control unit 3 with the osmotic pressure precision of 0.001 MPa. The osmotic pressure sensor 41 monitors the osmotic pressure value provided by the osmotic pressure supply unit 2 in real time, the monitored pressure signal can be transmitted to the osmotic pressure control unit 3 in real time, the osmotic pressure control unit 3 controls the rotation angle and the speed of the servo motor 21 according to the pressure value of the plunger type pressure pump high-pressure water sump 232 fed back by the osmotic pressure sensor 41, the servo motor 21 drives the roller screw pair 22 to do torsion motion, the torsion motion of the roller screw pair 22 directly drives the piston 231 in the plunger type pressure pump 23 to do reciprocating motion, and the reciprocating motion distance of the piston driven by the roller screw pair 1 wire is reduced, so that the pressure control precision is improved, the osmotic pressure in the osmotic process is regulated, the osmotic pressure supply unit 2 keeps outputting stable osmotic pressure, and the experimental requirements of large-particle-size high-porosity rock low osmotic pressure and large water flow rate permeation are met.
As shown in fig. 7, the method for performing the osmotic pressure experiment on the high-porosity rock by using the large-grain-size high-porosity rock constant head permeation experimental device comprises the following steps:
s1, preparing a cylindrical rock sample with large particle size and high porosity.
S1.1, selecting a complete rock with large particle size and high porosity;
the invention is characterized in that the experimental object is rock with large particle size gravel and high porosity, and according to different degrees of rock cementation, the sample sampling has certain difficulty, and more or less force is applied to the rock in the cutting process, so that the rock is selected as the original shape, the rock with a relatively complete structure is firstly screened through visual inspection or light knocking.
S1.2, cutting the selected rock, and processing the rock into a cylindrical rock sample required by experiments;
and cutting the initially screened rock in an original mode, wherein the mode of less damage to the rock sample is selected in the machining process, so that artificial cracks are prevented from being formed inside due to machining reasons, and water knife cutting or wire cutting is recommended. According to the original specification of the rock, the rock is processed into a cylindrical rock sample required by experiments.
In the preferred embodiment of the present invention, the sleeve 12 of the rock infiltration chamber is conical, so the present invention processes the selected rock as such into a cylindrical rock sample, the size of the rock sample is related to the particle size of the rock containing the maximum gravel, the particle size of the rock sample needs to be obtained by CT scanning or soaking before the infiltration experiment starts, and the relationship between the size of the cylindrical rock sample and the size of the maximum gravel particles contained therein needs to satisfy the following relationship:
wherein ,
represents the average diameter of a cylindrical rock sample; />
Representing the average thickness of a cylindrical rock sample; d, d max Indicating the maximum gravel diameter contained in the rock sample.
S1.3, checking a cylindrical rock sample;
and (3) checking the processed cylindrical rock sample to check whether the sample has pits formed by dropping large gravel caused by processing man, if so, performing the repairing procedure of the step S1.4, otherwise, performing the step S1.5.
S1.4, repairing a cylindrical rock sample;
on the basis of the step S1.3, the pits formed by dropping the large gravel blocks caused by the processing man are repaired by using epoxy resin glue, so that the sample is formed into a standard cylinder shape. Since gravel was considered to be impermeable to water in this experiment, epoxy glue was used instead of the falling bulk gravel.
S1.5, measuring physical parameters of a cylindrical rock sample;
physical parameter measurements were performed on standard cylindrical samples, including but not limited to initial parameters of thickness, diameter, dry mass, saturated mass, bubble mass after saturation, and the like, and recorded.
S2, selecting a sleeve with a corresponding size, placing a cylindrical rock sample, and sealing between the cylindrical rock sample and the inner wall of the sleeve.
S2.1, selecting a sleeve matched with the rock sample, and installing a cylindrical rock sample;
as shown in fig. 5A, the sleeve 12 of the permeation testing device according to the present invention has a conical shape with a large bottom opening and a small top opening, and when the cylindrical rock sample prepared in step S1 is placed, the sleeve 12 is inverted, i.e., the small inner diameter opening is positioned downward, the large inner diameter opening is positioned upward, and the rock sample is placed into the sleeve from the large end of the sleeve bottom opening. When the rock sample is placed in the sleeve, the placing position of the rock sample is not too close to the water inlet 131 and the water outlet 121 of the rock infiltration bin, otherwise, the osmotic pressure is not uniform or a water film cannot be formed to influence the operation of the water-encountering alarm 44.
S2.2, edge sealing by glass cement;
the sleeve 12 is inverted, because the inner diameter of the sleeve 12 is larger than the outer diameter of the rock sample, in order to prevent water from flowing through the gap between the rock sample and the inner wall of the sleeve and affecting the permeation experiment result, the lower edge of the gap between the rock sample and the inner wall of the sleeve is also required to be plugged by using glass cement with high viscosity, which is not easy to flow, so that the sealing effect is not good due to the fact that epoxy resin cement with low viscosity and easy to flow out through the lower edge of the gap between the rock sample and the inner wall of the sleeve in the step S2.3 is prevented.
S2.3, sealing;
inverting the sleeve 12, and injecting epoxy resin glue with low viscosity and easy flow from the gap between the outer surface of the rock sample and the inner wall of the stainless steel sleeve until the epoxy resin glue fills all the gaps between the rock sample and the inner wall of the stainless steel sleeve;
after the sleeve 12 is inverted and kept stand for 24 hours, waiting for the epoxy resin glue to solidify, if a gap is still reserved between the rock sample and the inner wall of the stainless steel conical sleeve at the moment, the epoxy resin glue with smaller viscosity and easy flow is continuously added until the epoxy resin glue fills all gaps between the rock sample and the inner wall of the stainless steel sleeve, and standing for solidification.
S3, assembling the rock permeation bin and checking the tightness of the permeation bin body.
As shown in fig. 2-3B, a stainless steel sleeve 12 with a rock sample is placed above a lower sealing stainless steel flange base 13, and an O-ring 15 is placed between the stainless steel sleeve 12 and the lower sealing stainless steel flange base 13, and the two are fastened together by bolts 14.
As shown in fig. 2, when fastening the bolts 14, it is preferable to fasten the bolts 14 in accordance with the principle of diagonal fastening, that is, to fasten in pairs to ensure the sealing effect of the O-rings 15.
After the rock infiltration storehouse is assembled, when infiltration water is injected into the rock infiltration storehouse from the water inlet 131 of ring flange base 13, the sealed effect of epoxy glue and O type sealing washer is examined, ensures that the infiltration water of injection is not oozed from between rock sample and the sleeve inner wall and O type sealing washer department, only is permeated from the inside of rock sample, guarantees that the infiltration experimental process goes on smoothly.
S4, connecting the osmotic pressure supply unit, the osmotic pressure control unit and the data acquisition unit, exhausting and starting the experiment.
S4.1, connecting a water outlet of the osmotic pressure supply unit with a water inlet of the rock permeation bin through a high-pressure water pipe;
as shown in fig. 1 and 2, one end of the high-pressure water pipe 5 is connected to a water inlet 131 at the lower part of the rock infiltration chamber, and the other end is connected to a three-way high-pressure joint 25 at the water outlet of the plunger type pressure pump 23 of the osmotic pressure supply unit.
To control the on/off of the permeate water and to control the discharge of the high pressure water feed line 5, a check valve 26, an exhaust valve 27 and an on/off valve 28 are connected in series to the high pressure water feed line 5.
S4.2, connecting a control line and a sensor data line;
as shown in fig. 1, an osmotic pressure sensor 41 is installed at the water outlet of the osmotic pressure supply unit plunger type pressure pump 23. The first electromagnetic flowmeter 42 is arranged at the water inlet pipeline of the rock penetration bin, the second electromagnetic flowmeter 43 is arranged at the water outlet pipeline of the rock penetration bin, the water meeting alarm 44 is arranged beside the sleeve of the rock penetration bin, and the feeler wire of the water meeting alarm is horizontally arranged on the upper bottom surface of a rock sample in the sleeve.
The data output end of the sensor is connected with the data input end of the osmotic pressure control unit 3 and the data acquisition unit 4 in a wired or wireless mode.
The control signal output end of the osmotic pressure control unit 3 is connected with the control end of the servo motor 21 of the osmotic pressure supply unit in a wired or wireless mode to control the action of the servo motor 21.
S4.3, checking the tightness of the device, exhausting, and starting an experiment;
as shown in fig. 1, the on-off valve 28 at the water inlet of the rock permeation unit is closed, the exhaust valve 27 is closed, the one-way valve 26 at the water outlet of the plunger type pressure pump 23 is opened, and the osmotic pressure supply unit 2 is started to supply pressurized water to check the tightness of the high pressure water delivery pipeline 5 and the relevant joints. The exhaust valve 27 is opened to exhaust the air in the system. The exhaust valve 27 was closed, the on-off valve 28 was opened, and water injection and pressurization were started to perform experiments.
S5, osmotic pressure loading, namely pressure step-by-step loading is carried out on the rock sample.
S5.1, loading osmotic pressure, and applying osmotic water to complete an osmotic experiment of the rock sample;
aiming at the structural characteristics of large-grain-size high-porosity rock, low density and large pores, the osmotic pressure control unit 3 provided by the invention has the advantages that the initial osmotic pressure applied is 0.001MPa, a control signal is output, the servo motor 21 is started to drive the roller screw pair 22 to push the piston 231 in the plunger type pressure pump 23 to reciprocate, and water in the high-pressure water sump 232 is pushed into the rock osmotic sump 1. Since the flow output and the pressure output of the plunger type pressure pump are a pair of inversely related parameters, under the condition that the output power of the servo motor is unchanged, the output pressure of the plunger type pressure pump (the value of the output pressure is equal to the osmotic pressure measured by the osmotic pressure sensor 41) is small, and the flow output of the plunger type pressure pump is large, the initial osmotic pressure applied by the osmotic pressure control unit is 0.001MPa, the osmotic pressure is kept for a certain time, for example, 2.5-3 hours, and the osmotic condition of a rock sample in the rock osmotic bin 1 is observed.
The osmotic pressure is loaded step by step, the osmotic pressure is increased by 0.001MPa every 2.5 to 3 hours until the water meeting alarm 44 detects that the sample starts to permeate water, and the first osmotic pressure p is recorded;
in the process of applying osmotic pressure and inputting osmotic water into the rock osmotic bin, the osmotic condition of the rock is observed, when a rock sample starts to permeate for the first time, namely, a water film is formed on the upper surface of the rock sample, and when the water meeting alarm 44 is triggered, the computer 45 records the osmotic pressure p at the moment, and the osmotic pressure supply unit 2 still keeps the osmotic pressure p at the moment.
The osmotic pressure p is kept stable, and the data acquisition unit 4 records the osmotic pressure p and the flow Q in the experimental process, so that the one-time osmotic experiment is completed. And then entering a permeation experiment of the next step permeation pressure, wherein the steps of the follow-up permeation experiment are repeated, the difference is that the permeation pressure and the flow rate of each permeation experiment change, and the experiment is ended after experimental data of multiple step permeation pressures are acquired.
S5.2 soaking in water for 24 hours, 48 hours and 72 hours, and repeating the permeation experiment;
repeating the saturated sample permeation experiments for three times after the sample is soaked for 24h, 48h and 72h respectively, wherein the osmotic pressure loading step is the same as that of S5.1, and recording osmotic pressure and flow data;
S6, collecting experimental data, and calculating the permeability coefficient of the rock with large particle size and high porosity.
In the process of reading the osmotic experiment, experimental data measured by an osmotic pressure sensor, a first electromagnetic flowmeter, a second electromagnetic flowmeter and a water-encountering alarm are read, and the osmotic coefficient k of a rock sample is calculated according to the following calculation formula:
where Q is the flow rate measured by the first flow meter 42, V is the permeate volume in the time of stabilized permeate t, L is the average thickness of the sample, A is the surface area of the bottom surface of the cylindrical sample, ΔH is the osmotic head difference, Δp is the osmotic pressure difference, p is the osmotic pressure measured by the osmotic pressure sensor, ρ is the osmotic liquid density, g is the gravitational acceleration,
average diameter of sample, D 1 、D 2 、D 3 、D 4 Respectively represent the diameters of different positions of the cylindrical sample, L 1 、L 2 、L 3 、L 4 Respectively representing the thicknesses of different positions of the cylindrical sample;
the formula (3) is integrated and deduced to calculate the osmotic coefficient k as follows:
wherein k is the permeability coefficient in cm/s; ρ is the density of the permeated liquid in g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the g is gravity acceleration, unit m/s 2 The method comprises the steps of carrying out a first treatment on the surface of the L is the thickness of the sample in cm; v is the seepage volume in the time of pressure-stabilizing seepage t, and the unit cm 3 The method comprises the steps of carrying out a first treatment on the surface of the Δp is the osmotic pressure difference in MPa; a is the penetration area per cm 2 The method comprises the steps of carrying out a first treatment on the surface of the t is the pressure stabilizing seepage time, and the unit is s.
Compared with the existing rock permeation experiment device and method, the device and the method can meet the experiment requirement of large-flow output on the premise of maintaining stable osmotic pressure, acquire accurate water head and flow data change in the experiment process in real time, conveniently perform permeation coefficient experiments on rock samples with different specifications and sizes, reveal the permeation characteristics of the large-grain-size and high-porosity rocks, and provide reliable reference data for construction of related engineering.
Finally, it should be noted that: the embodiments described above are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced with equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. A constant head permeation experiment method for large-particle-size high-porosity rock is characterized by comprising the following steps: it comprises the following steps:
S1, preparing a cylindrical rock sample with large particle size and high porosity;
selecting a high porosity rock as such containing intact large particle size gravel; cutting the selected rock to obtain a cylindrical rock sample required by experiments; checking the integrity of the cylindrical rock sample; measuring a physical parameter of a cylindrical rock sample;
the relationship between the size of the cylindrical rock sample and the maximum gravel size contained therein should satisfy the following requirements:
wherein ,
represents the average diameter of a cylindrical rock sample; />
Representing the average thickness of a cylindrical rock sample; d, d max Representing the maximum gravel diameter contained in the rock sample;
s2, selecting a conical sleeve with corresponding size, placing a cylindrical rock sample, and sealing between the cylindrical rock sample and the inner wall of the sleeve;
s2.1, selecting a conical sleeve matched with the rock sample, and installing a cylindrical rock sample;
the relationship between the selected conical sleeve size and the cylindrical rock sample size is:
wherein ,
representing the inner diameter of the sleeve in mm; />
Mean diameter in mm of a cylindrical rock sample; />
Represents the average thickness in mm of a cylindrical rock sample; l (L) c The sleeve height in mm; / >
The symbology is rounded up; />
The symbolic representation is rounded down;
inverting the conical sleeve, namely arranging a small inner diameter opening downwards and a large inner diameter opening upwards, and placing a cylindrical rock sample into the sleeve from one end with a large opening at the bottom of the conical sleeve;
s2.2, edge sealing by glass cement;
at the moment, the conical sleeve is still in an inverted state, and glass cement which is difficult to flow and has high viscosity is used for plugging the lower edge of a gap between the cylindrical rock sample and the inner wall of the conical sleeve;
s2.3, sealing;
at this time, the conical sleeve is still in an inverted state, and epoxy resin glue with smaller viscosity and easy flow is injected from the gap between the outer surface of the cylindrical rock sample and the inner wall of the conical sleeve until the epoxy resin glue fills all the gaps between the rock sample and the inner wall of the conical sleeve;
after the sleeve is inverted and kept stand for 24 hours, waiting for the solidification of the epoxy resin glue, if a gap is still reserved between the rock sample and the inner wall of the conical sleeve at the moment, continuing to add the epoxy resin glue with smaller viscosity and easy flow until the epoxy resin glue fills all gaps between the rock sample and the inner wall of the stainless steel sleeve and is kept stand for solidification;
s3, assembling the rock permeation bin and checking the tightness of the permeation bin body.
S4, connecting the osmotic pressure supply unit, the osmotic pressure control unit and the data acquisition unit, exhausting and starting the experiment.
S5, osmotic pressure loading, namely pressure step-by-step loading is carried out on the rock sample.
S5.1, loading osmotic pressure and applying osmotic water;
the initial osmotic pressure applied by the osmotic pressure control unit is 0.001MPa, and the osmotic pressure is kept for 2.5-3 h; then, loading osmotic pressure step by step, increasing the osmotic pressure by 0.001MPa each time and keeping for 2.5-3 hours until the rock sample starts to permeate for the first time;
in the process of applying osmotic pressure and inputting osmotic water into a rock osmotic bin, observing the osmotic condition of rock, when a rock sample starts to permeate for the first time, namely a water film is formed on the upper surface of the rock sample, recording the osmotic pressure p and the flow Q at the moment, finishing an osmotic experiment at this moment, continuously increasing the osmotic pressure, and repeating the following osmotic experiment steps, wherein the difference is that the osmotic pressure and the flow recorded in each osmotic experiment change;
s5.2 soaking in water for 24 hours, 48 hours and 72 hours, and repeating the permeation experiment;
repeating the saturated sample permeation experiments for three times after the sample is soaked for 24h, 48h and 72h respectively, wherein the osmotic pressure loading step is the same as that of S5.1, and the osmotic pressure and flow data of the experiment are required to be recorded;
S6, collecting experimental data, and calculating the permeability coefficient of the rock with large particle size and high porosity;
in the process of reading the osmotic experiment, experimental data measured by an osmotic pressure sensor, a first electromagnetic flowmeter, a second electromagnetic flowmeter and a water alarm are read, and the osmotic coefficient k of a rock sample is calculated according to the following calculation formula:
wherein Q is the flow rate in unit time measured by the sleeve water inlet flowmeter, V is the seepage volume in the time of pressure-stabilizing seepage t, t is the pressure-stabilizing seepage time, L is the average thickness of the cylindrical rock sample, A is the surface area of the bottom surface of the cylindrical rock sample, deltaH is the osmotic head difference, deltap is the osmotic pressure difference, p is the osmotic pressure measured by the osmotic pressure sensor, ρ is the osmotic liquid density, g is the gravitational acceleration,
average diameter of sample, D 1 、D 2 、D 3 、D 4 Respectively represent the diameters of different positions of the cylindrical sample, L 1 、L 2 、L 3 、L 4 Respectively representing the thicknesses of different positions of the cylindrical sample;
the formula (3) is integrated and deduced to calculate the osmotic coefficient k as follows:
wherein k is the permeability coefficient in cm/s; ρ is the density of the permeated liquid in g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the g is gravity acceleration, unit m/s 2 ；
Is the thickness of a cylindrical rock sample, and is in cm; v is the seepage volume in the time of pressure-stabilizing seepage t, and the unit cm 3 The method comprises the steps of carrying out a first treatment on the surface of the Δp is the osmotic pressure difference in MPa; a is the surface area of the bottom surface of a cylindrical rock sample, and the unit is cm 2 The method comprises the steps of carrying out a first treatment on the surface of the t is the pressure stabilizing seepage time, and the unit is s.
2. The method for constant head permeation experiments of large-particle-size high-porosity rock according to claim 1, wherein the method comprises the following steps: the conical sleeve is fixed on an operation platform through a detachable flange plate base; an O-shaped sealing ring is arranged between the conical sleeve and the flange plate base;
a water inlet penetrating through the operation platform is formed in the center of the flange plate base; a water outlet is formed in the upper part of the side surface of the conical sleeve;
the conical sleeve and the flange base are a series of variable-diameter sleeves and bases;
the conical sleeve and the flange plate base form the rock penetration bin.
3. The method for constant head permeation experiments of large-particle-size high-porosity rock according to claim 2, wherein the method comprises the following steps: the data acquisition unit comprises a osmotic pressure sensor, a first electromagnetic flowmeter, a second electromagnetic flowmeter and a water alarm;
the osmotic pressure sensor is arranged at the outlet of the osmotic pressure supply unit;
the first electromagnetic flowmeter is arranged in the water inlet water delivery pipeline of the rock permeation bin and is used for measuring the permeation flow rate input into the rock permeation bin;
The second electromagnetic flowmeter is arranged in a water outlet pipeline at the water outlet at the upper part of the conical sleeve and is used for measuring the seepage flow discharged by the cylindrical rock sample;
a vertical guide rail is fixed beside the conical sleeve, the water-contacting alarm is arranged on the guide rail, and a feeler wire of the water-contacting alarm extends into the conical sleeve and is placed on the upper surface of the rock sample;
the data output ends of the osmotic pressure sensor, the first electromagnetic flowmeter, the second electromagnetic flowmeter and the water alarm are connected with the data input end of the osmotic pressure control unit in a wired or wireless mode.
4. An experimental device for realizing the experimental method for constant head permeation of large-particle-size high-porosity rock according to claim 1, which is characterized in that: the device comprises a rock infiltration bin, an osmotic pressure supply unit, an osmotic pressure control unit and a data acquisition unit;
the rock penetration bin is used for containing experimental large-particle-size high-porosity cylindrical rock samples;
the osmotic pressure supply unit is used for inputting high-flow osmotic water with stable osmotic pressure into the rock osmotic bin;
the osmotic pressure control unit is used for driving the osmotic pressure supply unit to convey high-flow osmotic water with stable osmotic pressure into the rock osmotic bin;
The data acquisition unit is used for acquiring experimental data in the experimental process and transmitting the experimental data to the osmotic pressure control unit;
the osmotic pressure supply unit is connected with the rock osmotic bin through a high-pressure water pipeline, the osmotic pressure control unit is connected with the osmotic pressure supply unit through a circuit, and the data acquisition unit is connected with the rock osmotic bin, the osmotic pressure supply unit and the osmotic pressure control unit through circuits to form a closed-loop feedback control system.
5. The large-particle-size high-porosity rock constant head permeation experiment device according to claim 4, wherein: the rock penetration bin consists of a conical sleeve and a flange plate base;
the conical sleeve is connected with the flange plate base through bolts;
the flange plate base is detachably fixed on an operation platform;
a water inlet penetrating through the operation platform is formed in the center of the flange plate base; a water outlet is formed in the upper part of the side surface of the conical sleeve;
an O-shaped sealing ring is arranged between the conical sleeve and the flange plate base.
6. The large-particle-size high-porosity rock constant head permeation experiment device according to claim 5, wherein: the relationship between the conical sleeve and its built-in cylindrical rock sample is:
wherein ,
representing the inner diameter of the sleeve in mm; />
Mean diameter in mm of a cylindrical rock sample; />
Represents the average thickness in mm of a cylindrical rock sample; l (L) c The sleeve height in mm; />
The symbology is rounded up; />
The symbology is rounded down.
7. The large-particle-size high-porosity rock constant head permeation experiment device according to claim 6, wherein: the conical sleeve and the flange base forming the rock penetration bin are a series of variable diameter sleeves and bases, and the specification of the conical sleeve needs to be satisfied
8. The large particle size high porosity rock constant head permeation testing device according to one of claims 5 to 7, wherein: the osmotic pressure supply unit comprises a servo motor, a roller screw pair, a plunger type pressure pump, a water storage tank, a three-way joint, a one-way valve, an exhaust valve and a switching valve;
an output shaft of the servo motor is connected with a piston in the plunger type pressure pump through the roller screw pair to push the piston to reciprocate;
the water inlet of the plunger type pressure pump is connected with the water storage tank through a proportional valve, and the water outlet of the plunger type pressure pump is connected with the water inlet at the bottom of the rock permeation bin through the three-way joint, the one-way valve and the switching valve which are connected in series and the high-pressure water conveying pipeline;
And a pipeline branch is led out from the high-pressure water conveying pipeline, and the exhaust valve is arranged on the pipeline branch.
9. The large-particle-size high-porosity rock constant head permeation experiment device according to claim 8, wherein:
the osmotic pressure range output by the osmotic pressure supply unit is 0.002MPa-0.500MPa, and the output osmotic flow is more than 300ml/min; the control precision of the osmotic pressure control unit is 0.001MPa.
10. The large particle size high porosity rock constant head permeation testing device according to claim 9, wherein: the data acquisition unit comprises a osmotic pressure sensor, a first electromagnetic flowmeter, a second electromagnetic flowmeter, a water alarm and a computer;
the osmotic pressure sensor is arranged at the water outlet of the plunger type pressure pump and is used for measuring the pressure at the water outlet of the plunger type pressure pump;
the first electromagnetic flowmeter is arranged in the water inlet water delivery pipeline of the rock permeation bin and is used for measuring the permeation flow rate input into the rock permeation bin;
the second electromagnetic flowmeter is arranged in a water outlet pipeline at the water outlet at the upper part of the side surface of the conical sleeve and is used for measuring the seepage flow discharged by the cylindrical rock sample;
A vertical guide rail is fixed beside the conical sleeve, the water-contacting alarm is arranged on the guide rail, and a feeler wire of the water-contacting alarm extends into the conical sleeve and is placed on the upper surface of the rock sample;
the data output ends of the osmotic pressure sensor, the first electromagnetic flowmeter, the second electromagnetic flowmeter and the water meeting alarm are connected with the data input end of the osmotic pressure control unit in a wired or wireless mode, and are connected with the data input end of the computer.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310062616.0A CN116046635A (en) | 2023-01-19 | 2023-01-19 | Large-particle-size high-porosity rock constant head permeation experiment device and method |
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| CN117481629A (en) * | 2023-12-29 | 2024-02-02 | 成都水木医疗科技有限公司 | Multifunctional colloid osmotic pressure instrument and measuring method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117481629A (en) * | 2023-12-29 | 2024-02-02 | 成都水木医疗科技有限公司 | Multifunctional colloid osmotic pressure instrument and measuring method and application thereof |
| CN117481629B (en) * | 2023-12-29 | 2024-03-26 | 成都水木医疗科技有限公司 | Multifunctional colloid osmotic pressure instrument and measuring method and application thereof |
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