CN116296800A - High-stress and large-diameter dam foundation deep coarse-grained soil penetration test device and method - Google Patents
High-stress and large-diameter dam foundation deep coarse-grained soil penetration test device and method Download PDFInfo
- Publication number
- CN116296800A CN116296800A CN202310153221.1A CN202310153221A CN116296800A CN 116296800 A CN116296800 A CN 116296800A CN 202310153221 A CN202310153221 A CN 202310153221A CN 116296800 A CN116296800 A CN 116296800A
- Authority
- CN
- China
- Prior art keywords
- sample
- pressure
- pressure chamber
- osmotic
- water
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000002689 soil Substances 0.000 title claims abstract description 91
- 238000012360 testing method Methods 0.000 title claims abstract description 59
- 230000035515 penetration Effects 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 35
- 238000013112 stability test Methods 0.000 claims abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 83
- 230000003204 osmotic effect Effects 0.000 claims description 59
- 239000010419 fine particle Substances 0.000 claims description 47
- 238000011068 loading method Methods 0.000 claims description 44
- 239000002245 particle Substances 0.000 claims description 40
- 238000006243 chemical reaction Methods 0.000 claims description 27
- 230000008569 process Effects 0.000 claims description 25
- 239000011521 glass Substances 0.000 claims description 20
- 238000011144 upstream manufacturing Methods 0.000 claims description 20
- 238000011049 filling Methods 0.000 claims description 19
- 238000006073 displacement reaction Methods 0.000 claims description 14
- 229920006395 saturated elastomer Polymers 0.000 claims description 13
- 238000013508 migration Methods 0.000 claims description 10
- 230000005012 migration Effects 0.000 claims description 10
- 239000011362 coarse particle Substances 0.000 claims description 9
- 238000012216 screening Methods 0.000 claims description 6
- 230000008859 change Effects 0.000 claims description 5
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 238000004364 calculation method Methods 0.000 claims description 3
- 230000006835 compression Effects 0.000 claims description 3
- 238000007906 compression Methods 0.000 claims description 3
- 238000005520 cutting process Methods 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 238000005429 filling process Methods 0.000 claims description 3
- 230000035699 permeability Effects 0.000 claims description 3
- 238000007790 scraping Methods 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- 238000009738 saturating Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 4
- 230000003628 erosive effect Effects 0.000 description 7
- 239000011148 porous material Substances 0.000 description 5
- 230000002265 prevention Effects 0.000 description 5
- 238000011161 development Methods 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- 238000005336 cracking Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 239000012633 leachable Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/36—Embedding or analogous mounting of samples
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/02—Investigating particle size or size distribution
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/082—Investigating permeability by forcing a fluid through a sample
- G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
- G01N3/06—Special adaptations of indicating or recording means
- G01N3/068—Special adaptations of indicating or recording means with optical indicating or recording means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
- G01N3/12—Pressure testing
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/003—Generation of the force
- G01N2203/0042—Pneumatic or hydraulic means
- G01N2203/0048—Hydraulic means
Landscapes
- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- General Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Dispersion Chemistry (AREA)
- Fluid Mechanics (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses a high-stress large-diameter dam foundation deep coarse-grained soil penetration test device and method, and relates to the field of geotechnical tests. The invention can simulate the high-stress large-diameter deep coarse-grained soil penetration stability test of the dam foundation and truly reflect the condition of site soil materials.
Description
Technical Field
The invention belongs to the field of geotechnical tests, and particularly relates to a high-stress large-diameter deep coarse-grained soil penetration test device and method for a dam foundation.
Background
The erosion refers to the phenomenon that fine particles in seepage carrying internal unstable soil body migrate and run away in pores formed by coarse particles, and local hollows and local fills are gradually formed in the foundation. The internal unstable soil is a soil body in which the characteristic particle size of coarse and fine materials in the soil does not meet the self-filtering condition, part or all of the fine materials can freely move in pores, the soil body is a typical internal unstable soil, and the soil body is often contained in a deep coverage layer foundation due to the lack of middle grading soil and the relatively smooth coarse-grained soil at the tail part of a grading curve. The development of the undermining to a certain extent can cause uneven settlement of the foundation or damage the seepage prevention system of the dam, thereby threatening the safety of the dam. The Tarbela dam of the Pakistan, the Bennett dam of the Canada, the Sichuan dam of China and other hydropower engineering built on the foundation of the deep coverage layer all cause serious accidents due to corrosion, and the Tarbela dam is forced to empty the reservoir.
The most common seepage control measure in the deep and thick coverage foundation at present is a concrete impervious wall, and after the dam is built in a reservoir and water is stored, the seepage gradient near the end part of the impervious wall is generally larger than that in other areas, so that the seepage is more likely to occur. The migration and loss of a large amount of fine particles near the end part of the impervious wall easily induces the partial uneven settlement of the dam foundation, so that the impervious wall can be cracked and even broken, and the safety of the dam is seriously threatened. Therefore, the method for evaluating the dam safety by using the coarse-grained soil has very important theoretical and practical significance for discussing the penetration stability of coarse-grained soil near the end part of the impervious wall at the deep part of the dam foundation and the stress deformation characteristics possibly induced by the grain migration loss.
To investigate the penetration stability of deep coarse-grained soil near the end of a dam foundation diaphragm wall and the stress deformation characteristics possibly induced by the grain migration loss, corresponding geotechnical test equipment must be developed, which must be capable of more truly simulating the high-stress state of the deep coarse-grained soil on the one hand and reflecting the grain composition characteristics of the deep coarse-grained soil on the other hand as far as possible. At present, the maximum construction depth of the concrete impervious wall reaches 150-180 m, so that soil near the end of the impervious wall is generally in a high-stress state, and the action of a dam and an upper soil layer is considered, and the upper soil pressure of coarse-grained soil near the end of the impervious wall is roughly estimated to be 2.0-3.0 MPa. To properly evaluate the osmotic stability of the soil mass near the end of the diaphragm wall, such a high stress condition must be effectively simulated. In addition, the soil body of the deep and thick coverage layer is mainly a wide-grade soil body, the particle size difference of coarse particles and fine particles is obvious, the coarse particles are generally gravels and gravels, the maximum particle size can reach 60 cm-80 cm, the filling fine particles are gravel sand, fine sand, silt and the like, and the particle size is generally 0.075 mm-2 mm. To more truly simulate the grain size characteristics of deep coarse-grained soil in the field, the sample diameter must be large enough, however, the sample diameter commonly used in the current indoor penetration test is generally 7.6 cm-30 cm. In order to prevent the test result from being influenced by the particle size of the soil, according to the current geotechnical test rules (SL 237-1999), the maximum particle size of the soil needs to be controlled to be 1/5-1/6 of the diameter of a sample, if the diameter of the sample is 30cm, the maximum particle size allowed by an indoor test is only 5 cm-6 cm, so that a large number of particles with the particle size exceeding 6cm in the soil cannot be effectively simulated, serious distortion of the particle grading of the soil in the indoor test is caused, and the condition of the soil on site cannot be accurately reflected.
Therefore, how to provide a device and a method for testing the penetration stability of deep coarse-grained soil of a dam foundation with high stress and large diameter is a problem to be solved by those skilled in the art.
Disclosure of Invention
In view of the above, the invention provides a high-stress large-diameter dam foundation deep coarse-grained soil penetration test device and method, which can be used for simulating whether the loss of fine grains can induce the uneven deformation of a soil skeleton in the development process of deep erosion of a deep-thickness coverage foundation under a high-stress condition, and the test result can quantitatively evaluate the influence of the movement of the grains in the deep-thickness coverage foundation deep coarse-grained soil on the stress deformation and safety of the dam.
In order to achieve the above purpose, the present invention adopts the following technical scheme: the high-stress large-diameter deep coarse-grained soil penetration test device for the dam foundation is used for high-stress large-diameter coarse-grained soil penetration stability test in the deep of the dam foundation and comprises an axial pressurization system, a penetration pressure loading system, a lost fine particle collecting system and a data acquisition system, wherein the penetration pressure loading system is arranged on the axial pressurization system, the lost fine particle collecting system is arranged at the bottom of the penetration pressure loading system, and the data acquisition system is arranged on the penetration pressure loading system and the axial pressurization system.
Further, the axial pressurization system comprises a frame platform, a door-type reaction frame and a hydraulic jack, wherein the door-type reaction frame comprises reaction frame struts and reaction frame beams, the reaction frame struts are arranged on two sides of the frame platform, the reaction frame beams are arranged on the top ends of the reaction frame struts, and the hydraulic jack is arranged on the reaction frame beams.
Further, the roller row sub-component comprises a roller row frame and a roller row, wherein the roller row frame is arranged on the frame platform, and the roller row is arranged in the roller row frame and is in rotary connection with the roller row frame.
Further, the osmotic pressure loading system comprises osmotic pressure loading equipment, a water inlet pipe, a water pressure measuring hole, a pressure chamber top cover, an upstream porous cover plate and a pressure chamber, wherein the osmotic pressure loading equipment is a movable water tank or a pressure pump with precise adjustment and control, the pressure chamber is arranged on a roller sub-component, the water pressure measuring hole is uniformly formed in the pressure chamber, the pressure chamber top cover is arranged above the pressure chamber, the water inlet pipe is arranged on the pressure chamber top cover, the upstream porous cover plate is arranged in the pressure chamber, the osmotic pressure loading equipment is arranged on one side of a rack platform, and the osmotic pressure loading equipment is communicated with the water inlet pipe.
Further, the device also comprises a pressure chamber piston and a pushing frame, wherein the pressure chamber piston is arranged on the pressure chamber top cover, the pushing frame is arranged on the upstream porous cover plate, the pressure chamber piston is in sliding connection with the pressure chamber top cover, and the pressure chamber piston is abutted against the pushing frame.
Further, the pressure chamber comprises a first organic glass cylinder, a second organic glass cylinder, a connecting flange and a pull rod, wherein the connecting flange is arranged at two ends of the first organic glass cylinder and the second organic glass cylinder, the first organic glass cylinder and the second organic glass cylinder are communicated through the connecting flange, and the pull rod is uniformly arranged between the connecting flanges and used for improving the structural strength of the pressure chamber.
Further, the fine particle loss collecting system comprises a downstream porous cover plate, a funnel-shaped water outlet and a water outlet pipe, wherein the funnel-shaped water outlet is arranged at the bottom end of the pressure chamber and is communicated with the pressure chamber, the downstream porous cover plate is arranged between the pressure chamber and the funnel-shaped water outlet, and the water outlet pipe is arranged at the bottom of the funnel-shaped water outlet.
Further, the data acquisition system comprises a load sensor, a displacement sensor, a water pressure sensor and an industrial control integrated machine, wherein the load sensor is arranged on the hydraulic jack, the displacement sensor is arranged on the counter-force frame beam and used for detecting the displacement of the hydraulic jack, the water pressure sensor is arranged at the water pressure measuring hole, the industrial control integrated machine is arranged on one side of the door-type counter-force frame, and the load sensor, the displacement sensor and the water pressure sensor are all in electromechanical connection with the industrial control integrated machine.
A test method of a high-stress large-diameter dam foundation deep coarse-grained soil penetration test device comprises the following steps:
s01, filling and compacting in layers, preparing a sample, screening according to a particle grading curve of a test soil body, preparing the soil body according to filling dry density and filling volume calculation, adding water into the proportioned soil particles, fully stirring, fully wrapping fine particles around coarse particles, avoiding separation of the coarse particles and fine particles, and finally filling and compacting the stirred soil body in layers, wherein in the filling process, the quality of each layer of soil body is controlled to be the same, compacting is ensured to be the same thickness, and the relative density of each layer is ensured to be consistent; cutting and marking the surface of the previous layer of sample before filling the lower layer of sample, scraping the surface of the previous layer of sample so that the layers are tightly combined, and photographing and recording the initial state of the sample after filling is finished;
s02, slowly applying axial pressure, horizontally placing an upstream porous cover plate on the surface of a sample, measuring by a level meter, and re-leveling the surface of the sample if the pressure chamber piston is not in a horizontal state, ensuring that a pressure chamber piston applying the axial pressure vertically acts on the center of the upstream porous cover plate so as to avoid eccentric compression, slowly applying step by step when the axial pressure is applied, simultaneously recording the change of the settlement of the sample, applying the axial pressure of the next stage when the settlement of the sample is no longer changed, recording the settlement of the sample after the axial pressure reaches a preset value, and taking the settlement as the initial settlement generated by loading of the overlying pressure and keeping the axial pressure unchanged all the time in a subsequent test;
s03, slowly and fully saturating a sample, ensuring that the sample is slowly and fully saturated under low osmotic pressure, avoiding osmotic damage of the sample in the saturation process, keeping the seepage direction from bottom to top in the saturation process, keeping enough endurance in the saturation process, continuously exhausting a pressure measuring tube, ensuring that the sample is fully saturated, recording the seepage flow of the sample and the readings of each water pressure measuring sensor after the saturation is finished, photographing, recording the saturated state of the sample, and facilitating later analysis and comparison;
s04, applying osmotic pressure in a grading manner, starting an osmotic test, starting to slowly lift a movable water tank after a sample is saturated, applying osmotic pressure in a grading manner, closely focusing on the movement condition of particles on the wall surface of the sample in the loading process, recording the osmotic flow and the reading of a pressure measuring tube every 10 minutes, when each index is stable, indicating that the sample reaches a stable state, recording the osmotic flow and the reading of the pressure measuring tube, photographing and recording the migration condition of fine particles on the side wall of an instrument and other relatively obvious test phenomena, starting to apply the next-stage osmotic pressure, and continuously increasing the osmotic pressure to the maximum value when the sample has obvious osmotic damage, such as the phenomena of abrupt increase of the osmotic flow, turbidity of water and abrupt decrease of an upstream water head, and continuing for 12 hours, so as to ensure that the migration of the fine particles can be carried out;
s05, particle grading analysis, namely photographing and recording the upper surface condition of the sample after the test is finished, removing the sample in a layered manner, carefully observing and recording the movement condition of particles and the formation condition of a leakage channel in the sample during the removal process, drying and screening each layer of soil sample and the fine particles collected in each loading step, carrying out particle grading analysis, and evaluating the movement condition of the fine particles during the test.
Further, in step S04, in order to facilitate the loss of fine particles, in the process of applying osmotic pressure in a graded manner, the direction of seepage is from top to bottom, and meanwhile, in the process of loading at each stage of osmotic pressure, the loss of fine particles are collected, and the fine particles collected in different loading steps are separately and independently placed.
The beneficial effects of the invention are as follows:
the test device solves the key technical requirements of high stress, large sample diameter and the like required by researching the stress deformation characteristics possibly induced by the penetration stability of deep coarse-grained soil of a dam foundation and the particle migration loss. The device can be used for discussing whether the fine particle loss can induce the uneven deformation of the soil skeleton in the deep erosion occurrence and development process of the deep foundation of the deep coverage layer under the high stress condition through the axial pressurizing system, the osmotic pressure loading system, the lost fine particle collecting system and the data acquisition system, and the test result can quantitatively evaluate the influence of the particle movement in the deep coarse-grained soil of the deep foundation of the deep coverage layer on the stress deformation and safety of the dam.
Drawings
FIG. 1 is a front view of the present invention;
FIG. 2 is a left side view of the present invention;
FIG. 3 is a schematic illustration of the erosion near the end of a particular hydroelectric power station barrier.
In the figure: 1-a rack platform; 2-a reaction frame strut; 3-a reaction frame cross beam; 4-a hydraulic jack; 5-rolling rows; 6-a water inlet pipe; 7-a water pressure measuring hole; 8-a pressure chamber top cover; 9-an upstream side porous cover plate; 10-a pressure chamber; 11-a pressure chamber piston; 12-pushing frame; 13-connecting flanges; 14-a pull rod; 15-a downstream side porous cover plate; 16-a funnel-shaped water outlet; 17-a water outlet pipe; 18-load cell; 19-displacement sensor.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
In the description of the present invention, it should be noted that, directions or positional relationships indicated by terms such as "center", "upper", "lower", "left", "right", "horizontal", "inner", "outer", "one side", etc., are based on directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements to be referred to must have a specific direction, be configured and operated in the specific direction, and thus should not be construed as limiting the present invention; the terms "first," "second," "third," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance, and furthermore, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "coupled," and the like are to be construed broadly, and may be fixedly coupled, detachably coupled, or integrally coupled, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
1-2, the high-stress large-diameter deep coarse-grained soil penetration test device for the deep high-stress large-diameter coarse-grained soil penetration stability test of the dam foundation comprises an axial pressurizing system, a penetration pressure loading system, a loss fine particle collecting system and a data collecting system, wherein the penetration pressure loading system is arranged on the axial pressurizing system, the loss fine particle collecting system is arranged at the bottom of the penetration pressure loading system, and the data collecting system is arranged on the penetration pressure loading system and the axial pressurizing system.
The axial pressurizing system can simulate the upper load borne by a deep coverage foundation and mainly comprises a frame platform 1, a 1000kN gate-type reaction frame and a hydraulic jack 4, wherein the frame platform 1 is 1.3 m long and 0.95 m wide, and is formed by welding 45 steel plates, then eliminating residual stress through high-temperature tempering and processing by a large machine tool; the 1000kN door-type reaction frame comprises reaction frame struts 2 and reaction frame cross beams 3, wherein the reaction frame struts 2 are arranged on two sides of a frame platform 1, the reaction frame cross beams 3 are arranged at the top ends of the reaction frame struts 2, and hydraulic jacks 4 are arranged on the reaction frame cross beams 3.
In order to facilitate the movement of the pressure chamber on the frame platform 1, a roller row sub-component is arranged at the lower part of the pressure chamber, the roller row sub-component comprises a roller row frame and 20 roller rows 5, the roller row frame is arranged on the frame platform 1, and the roller rows 5 are arranged in the roller row frame and are in rotary connection with the roller row frame.
The osmotic pressure loading system is used for simulating the seepage effect born by soil and comprises osmotic pressure loading equipment, a water inlet pipe 6, water pressure measuring holes 7, a pressure chamber top cover 8, an upstream side porous cover plate 9 and a pressure chamber 10, wherein the osmotic pressure loading equipment is mainly a movable water tank or a pressure pump with precise regulation and control, the pressure chamber 10 is arranged on a roller row component, and ten water pressure measuring holes 7 are uniformly arranged in the height range of the pressure chamber 10 in order to monitor the local gradient change of samples at different parts along the path; in order to improve the structural strength of the pressure chamber 10, the pressure chamber 10 is composed of an upper organic glass cylinder and a lower organic glass cylinder, namely a first organic glass cylinder and a second organic glass cylinder, connecting flanges 13 are arranged at two ends of the first organic glass cylinder and the second organic glass cylinder, the first organic glass cylinder and the second organic glass cylinder are communicated through the connecting flanges 13, pull rods 14 are uniformly arranged between the connecting flanges 13, the inner diameter of the pressure chamber 10 is 46cm, and the effective sample height is 55cm. The pressure chamber top cover 8 is arranged above the pressure chamber 10, the water inlet pipe 6 is arranged on the pressure chamber top cover 8, the upstream porous cover plate 9 is arranged in the pressure chamber 10, the osmotic pressure loading device is arranged on one side of the frame platform 1, and the osmotic pressure loading device is communicated with the water inlet pipe 6.
The invention also comprises a pressure chamber piston 11 and a pushing frame 12, wherein the pressure chamber piston 11 is arranged on the pressure chamber top cover 8, the pushing frame 12 is arranged on the upstream porous cover plate 9, the pressure chamber piston 11 is in sliding connection with the pressure chamber top cover 8, and the pressure chamber piston 11 is in contact with the pushing frame 12.
The system for collecting the lost fine particles can collect the fine particles of the sample flowing out in the underetching process in real time and measure seepage flow, and comprises a downstream porous cover plate 15, a funnel-shaped water outlet 16 and a water outlet pipe 17, wherein the funnel-shaped water outlet 16 is arranged at the bottom end of the pressure chamber 10 and is communicated with the pressure chamber 10, the downstream porous cover plate 15 is arranged between the pressure chamber 10 and the funnel-shaped water outlet 16, the water outlet pipe 17 is arranged at the bottom of the funnel-shaped water outlet 16, the aperture of the downstream porous cover plate 15 has larger influence on the loss of the fine particles, and if the aperture is overlarge relative to the particle size of the lost fine particles, a large amount of particles are lost when the sample is filled, initial defects are artificially formed, and the test result is influenced; if the pore size is too small relative to the particle size of the leachable particles, loss of fines may be hindered and the test results may be affected. In this case, since particles of 5mm or less are generally used as fine particles in engineering, the pore diameter of the downstream porous cover plate is assumed to be 5mm.
The data acquisition system can monitor sample settlement, upstream and downstream water head difference, seepage flow, pore water pressure of each measuring point of the sample along the journey and the like in real time and comprises a 50-ton load sensor 18, a 100-mm displacement sensor 19, a water pressure sensor and an industrial control integrated machine, wherein the load sensor 18 is arranged on the hydraulic jack 4, the displacement sensor 19 is arranged on the counter-force frame beam 3 and is used for detecting the displacement of the hydraulic jack 4, the water pressure sensor is arranged at the water pressure measuring hole 7, the pressure measuring pipe is used for directly measuring the change of the water head along the journey under the condition of low water head, and the water pressure sensor is used for measuring under the condition of high water head; the industrial control integrated machine is arranged on one side of the door-type reaction frame, and the load sensor 18, the displacement sensor 19 and the water pressure sensor are all in electromechanical connection with the industrial control integrated machine and are used for measuring and displaying load loading force and displacement deformation, and measuring accuracy is +/-0.2% F.S.
Example 1
The embodiment discloses a test method of a high-stress large-diameter dam foundation deep coarse-grained soil penetration test device, which comprises the following steps:
s01, filling and compacting in layers to prepare a sample. Screening according to a particle size distribution curve of a test soil body, preparing a proper amount of soil body according to filling dry density and filling volume calculation, adding proper amount of water into proportioned soil particles, fully stirring to ensure that fine particles are fully wrapped around coarse particles, avoiding separation of the coarse particles, and finally filling and compacting the stirred soil body into 5 layers with the thickness of 11cm, wherein in the filling process, the quality of each layer of soil body is controlled to be the same, compacting to the same thickness is ensured, and the relative density of each layer is ensured to be consistent; cutting and marking the surface of the previous layer of sample before filling the lower layer of sample, scraping the surface of the previous layer of sample so that the layers are tightly combined, and photographing and recording the initial state of the sample after filling is finished;
s02, slowly applying axial pressure. The method comprises the steps of horizontally placing an upstream porous cover plate on the surface of a sample, measuring by a level meter, and if the sample is not in a horizontal state, re-leveling the surface of the sample, ensuring that a pressure chamber piston applying axial pressure vertically acts on the center of the upstream porous cover plate so as to avoid eccentric compression, slowly applying step by step when the axial pressure is applied, recording the change of the settlement amount of the sample, applying the next-stage axial pressure when the settlement amount of the sample is no longer changed, recording the settlement amount of the sample after the axial pressure reaches a preset value, and taking the settlement amount of the sample as the initial settlement amount generated by loading of the overlying pressure and keeping the axial pressure unchanged all the time in a subsequent test;
s03. slow and fully saturated samples. Ensuring that the sample is slowly and fully saturated under low osmotic pressure, avoiding osmotic damage of the sample in the saturation process, keeping the seepage direction from bottom to top in the saturation process, keeping enough tolerance in the saturation process, continuously exhausting the pressure measuring tube, ensuring that the sample is fully saturated, recording the seepage quantity of the sample and the readings of each water pressure measuring sensor after the saturation is finished, and photographing to record the saturated state of the sample so as to facilitate later analysis and comparison;
s04, applying osmotic pressure in a grading way, and starting an osmotic test. When the sample is saturated, slowly lifting the movable water tank, applying the osmotic pressure in a grading manner, closely focusing on the movement condition of the particles on the wall surface of the sample in the loading process, recording the osmotic flow and the reading of the pressure measuring tube every 10 minutes, when all indexes are stable, indicating that the sample reaches a stable state, recording the osmotic flow and the reading of the pressure measuring tube, photographing and recording the migration condition of the fine particles on the side wall of the instrument and other obvious test phenomena, starting to apply the next stage of osmotic pressure, and continuously increasing the osmotic pressure to the maximum value when obvious osmotic damage occurs to the sample, such as the phenomena of sudden increase of the osmotic flow, turbid water and sudden decrease of the upstream water head, and continuously maintaining for 12 hours, so as to ensure that the migration of the fine particles can occur, wherein in order to facilitate the loss of the fine particles, the seepage direction is from top to bottom in the grading process of applying the osmotic pressure, simultaneously, collecting the lost fine particles in the process of each stage of osmotic pressure loading, and separating and independently placing the fine particles collected in different loading steps;
s05, particle grading analysis. After the test is finished, photographing and recording the upper surface condition of the sample, removing the sample in a layering manner, carefully observing and recording the movement of particles and the formation condition of a leakage channel in the sample in the removing process, drying and screening each layer of soil sample and the fine particles collected in each loading step, carrying out particle grading analysis, and evaluating the movement condition of the fine particles in the test process.
Application example 1
As shown in fig. 3, the device is used for carrying out a penetration stability test of soil body of a deep (1) layer of a dam foundation of a hydropower station in southwest of China, and the test result provides an important theoretical basis for seepage safety evaluation of the soil body of the deep of the dam foundation of the hydropower station.
A certain hydropower station is positioned in a large river basin, the normal water storage level of a reservoir is 1378.00m, and the total storage capacity is 2.195 hundred million m 3 The installed capacity is 920MW, the maximum dam height is 79.5m, the engineering and the like are equal to each other, and the engineering scale is of a large (2) type. The dam site area is deep in covering layer, the maximum thickness is 148.6m, the hierarchical structure is complex, and the dam site area can be divided into four layers of seven sublayers from bottom to top: (1) a layer (2) -1 sublayer, (2) -2 sublayer, (2) -3 sublayer, (3) -1 sublayer, (3) -2 sublayer and (4), wherein (1) layer, (2) -1 sublayer and (4)The layers are strong water permeability, (2) -2 sublayer, (2) -3 sublayer, (3) -1 sublayer, and (3) -2 sublayer are medium water permeability. The dam body adopts clay core wall for seepage prevention, the dam foundation river bed section adopts 110m deep suspension type seepage prevention wall lower joint cover layer and bedrock curtain grouting closed cover layer, and two banks adopt the seepage prevention scheme of the closed type seepage prevention wall.
When the hydropower station stores water for the first time, water burst dangerous situations occur at the positions of the downstream right bank river channel which are about 448m and Gao Chengyao m away from the dam axis, the water burst quantity is about 200L/s, more gray black fine particles are burst, and uneven deformation phenomena such as ground cracking, riverbed collapse and the like occur near the water burst point. After an accident occurs, comprehensively judging that the accident causes the erosion of the soil body of the layer (1) near the end part of the impervious wall caused by the curtain defect of the covering layer according to a great deal of works such as geological exploration, water quality analysis of a seepage water source, detection of a seepage channel, three-dimensional seepage inversion analysis and the like. Then, the continuous massive loss of fine particles in the soil body of the deep (1) layer of the dam foundation will not induce significant deformation of the soil skeleton, as shown in fig. 3, and further induce cracking, breaking, and even sudden dam break of the impervious wall? The accurate assessment of the problem relates to the self-safety of the luzhou-dynasty hydropower station and the safety of other cascade power stations downstream of county and large-river. For this problem, no accurate assessment is given at present, because the current research mainly focuses on what kind of grain-graded soil mass will be eroded, namely the geometrical conditions, critical hydraulic conditions for erosion, etc., but little focuses on that the erosion will not induce deformation of the soil skeleton and thus cause corresponding damage problems. To make an assessment fully accurate, a related series of experimental studies must be conducted.
To accurately evaluate that the loss of fine particles in the deep layer (1) of the luzhou-dyke foundation based on the test can not induce obvious skeleton deformation, the following two technical problems need to be solved: (1) The test soil material needs to reflect the original grain composition characteristics of the site soil body as far as possible. The deep (1) layer of the dam foundation is a floating (block) egg (crushed) gravel layer, the difference of soil mass thickness particles is obvious, the maximum particle size and the minimum particle size respectively reach 20cm and 0.005mm, and the non-uniformity coefficient of the grading envelope line reaches 259.1. According to the geotechnical test procedure (SL 237-1999), when the ratio of the diameter of the sample to the maximum particle size of the soil body is more than 5-6, the uniformity of the sample can be ensured, thereby ensuring the repeatability of the test result. According to the grading characteristics of the layer (1), the maximum grain diameter of the test soil body is preferably 8cm, so that the original grading characteristics can be truly reflected, the diameter of a sample is required to be 40 cm-48 cm approximately, however, the diameter of most seepage test samples is 7.6 cm-30 cm currently, and the current research requirements cannot be met. (2) The test needs to simulate the in-situ high stress state of soil near the end of the impervious wall as far as possible. According to rough estimation of dead weight stress, the embedded depth near the end part of the impervious wall is about 200m, the in-situ vertical effective dead weight stress is about 2.0MPa, however, the axial pressure applied by most seepage tests at present is 25 kPa-900 kPa, and the current research requirements cannot be met.
The high-stress large-diameter deep coarse-grained soil penetration stability test device for the dam foundation has the advantages that the maximum axial stress reaches 3.0MPa, and the requirement on stress state simulation is met; the diameter of the sample reaches 46cm, the maximum particle diameter of the instrument is allowed to reach 7.7 cm-9.2 cm, and the requirement of the original grading simulation of the soil body of the layer (1) is met. Specific test results are not described herein.
The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the technical scope of the present invention, so that any minor modifications, equivalent changes and modifications made to the above embodiments according to the technical principles of the present invention still fall within the scope of the technical solutions of the present invention.
Claims (10)
1. The deep coarse-grained soil penetration test device of the dam foundation with high stress and large diameter is used for a coarse-grained soil penetration stability test of the high stress and large diameter in the deep of the dam foundation, and is characterized in that: the device comprises an axial pressurization system, a osmotic pressure loading system, a lost fine particle collecting system and a data acquisition system, wherein the osmotic pressure loading system is arranged on the axial pressurization system, the lost fine particle collecting system is arranged at the bottom of the osmotic pressure loading system, and the data acquisition system is arranged on the osmotic pressure loading system and the axial pressurization system.
2. The high-stress large-diameter dam foundation deep coarse-grained soil penetration test device according to claim 1, wherein the axial pressurization system comprises a frame platform, a gate-type reaction frame and a hydraulic jack, the gate-type reaction frame comprises reaction frame struts and reaction frame cross beams, the reaction frame struts are arranged on two sides of the frame platform, the reaction frame cross beams are arranged on the top ends of the reaction frame struts, and the hydraulic jack is arranged on the reaction frame cross beams.
3. The high stress, large diameter dam foundation deep coarse soil penetration test apparatus of claim 2, further comprising a roller row sub-assembly comprising a roller row frame disposed on the frame platform and a roller row disposed in the roller row frame and rotatably connected to the roller row frame.
4. The high-stress large-diameter dam foundation deep coarse-grained soil permeability test device according to claim 3, wherein the osmotic pressure loading system comprises osmotic pressure loading equipment, a water inlet pipe, a water pressure measuring hole, a pressure chamber top cover, an upstream side porous cover plate and a pressure chamber, wherein the osmotic pressure loading equipment is a movable water tank or a pressure pump controlled by precise adjustment, the pressure chamber is arranged on a roller sub-component, the water pressure measuring hole is uniformly arranged on the pressure chamber, the pressure chamber top cover is arranged above the pressure chamber, the water inlet pipe is arranged on the pressure chamber top cover, the upstream side porous cover plate is arranged in the pressure chamber, the osmotic pressure loading equipment is arranged on one side of a rack platform, and the osmotic pressure loading equipment is communicated with the water inlet pipe.
5. The high-stress large-diameter dam foundation deep coarse soil penetration test device according to claim 4, further comprising a pressure chamber piston and a pushing frame, wherein the pressure chamber piston is arranged on a pressure chamber top cover, the pushing frame is arranged on an upstream side porous cover plate, the pressure chamber piston is in sliding connection with the pressure chamber top cover, and the pressure chamber piston is in contact with the pushing frame.
6. The high-stress large-diameter dam foundation deep coarse-grained soil penetration test device according to claim 4, wherein the pressure chamber comprises a first organic glass cylinder, a second organic glass cylinder, connecting flanges and a pull rod, the connecting flanges are arranged at two ends of the first organic glass cylinder and the second organic glass cylinder, the first organic glass cylinder and the second organic glass cylinder are communicated through the connecting flanges, and the pull rod is uniformly arranged between the connecting flanges and used for improving the structural strength of the pressure chamber.
7. The high-stress large-diameter dam foundation deep coarse-grained soil penetration test device according to claim 4, wherein the fine-grained soil loss collection system comprises a downstream porous cover plate, a funnel-shaped water outlet and a water outlet pipe, the funnel-shaped water outlet is arranged at the bottom end of the pressure chamber and communicated with the pressure chamber, the downstream porous cover plate is arranged between the pressure chamber and the funnel-shaped water outlet, and the water outlet pipe is arranged at the bottom of the funnel-shaped water outlet.
8. The high-stress large-diameter dam foundation deep coarse-grained soil penetration test device according to claim 4, wherein the data acquisition system comprises a load sensor, a displacement sensor, a water pressure sensor and an industrial control integrated machine, wherein the load sensor is arranged on a hydraulic jack, the displacement sensor is arranged on a counter-force frame beam and used for detecting the displacement of the hydraulic jack, the water pressure sensor is arranged at a water pressure measuring hole, the industrial control integrated machine is arranged on one side of a door-type counter-force frame, and the load sensor, the displacement sensor and the water pressure sensor are all in electromechanical connection with the industrial control integrated machine.
9. The method for testing the penetration of high-stress large-diameter deep coarse-grained soil of a dam foundation according to any one of claims 1 to 8, comprising the following steps:
s01, filling and compacting in layers, preparing a sample, screening according to a particle grading curve of a test soil body, preparing the soil body according to filling dry density and filling volume calculation, adding water into the proportioned soil particles, fully stirring, fully wrapping fine particles around coarse particles, avoiding separation of the coarse particles and fine particles, and finally filling and compacting the stirred soil body in layers, wherein in the filling process, the quality of each layer of soil body is controlled to be the same, compacting is ensured to be the same thickness, and the relative density of each layer is ensured to be consistent; cutting and marking the surface of the previous layer of sample before filling the lower layer of sample, scraping the surface of the previous layer of sample so that the layers are tightly combined, and photographing and recording the initial state of the sample after filling is finished;
s02, slowly applying axial pressure, horizontally placing an upstream porous cover plate on the surface of a sample, measuring by a level meter, and re-leveling the surface of the sample if the pressure chamber piston is not in a horizontal state, ensuring that a pressure chamber piston applying the axial pressure vertically acts on the center of the upstream porous cover plate so as to avoid eccentric compression, slowly applying step by step when the axial pressure is applied, simultaneously recording the change of the settlement of the sample, applying the axial pressure of the next stage when the settlement of the sample is no longer changed, recording the settlement of the sample after the axial pressure reaches a preset value, and taking the settlement as the initial settlement generated by loading of the overlying pressure and keeping the axial pressure unchanged all the time in a subsequent test;
s03, slowly and fully saturating a sample, ensuring that the sample is slowly and fully saturated under low osmotic pressure, avoiding osmotic damage of the sample in the saturation process, keeping the seepage direction from bottom to top in the saturation process, keeping enough endurance in the saturation process, continuously exhausting a pressure measuring tube, ensuring that the sample is fully saturated, recording the seepage flow of the sample and the readings of each water pressure measuring sensor after the saturation is finished, photographing, recording the saturated state of the sample, and facilitating later analysis and comparison;
s04, applying osmotic pressure in a grading manner, starting an osmotic test, starting to slowly lift a movable water tank after a sample is saturated, applying osmotic pressure in a grading manner, closely focusing on the movement condition of particles on the wall surface of the sample in the loading process, recording the osmotic flow and the reading of a pressure measuring tube every 10 minutes, when each index is stable, indicating that the sample reaches a stable state, recording the osmotic flow and the reading of the pressure measuring tube, photographing and recording the migration condition of fine particles on the side wall of an instrument and other relatively obvious test phenomena, starting to apply the next-stage osmotic pressure, and continuously increasing the osmotic pressure to the maximum value when the sample has obvious osmotic damage, such as the phenomena of abrupt increase of the osmotic flow, turbidity of water and abrupt decrease of an upstream water head, and continuing for 12 hours, so as to ensure that the migration of the fine particles can be carried out;
s05, particle grading analysis, namely photographing and recording the upper surface condition of the sample after the test is finished, removing the sample in a layered manner, carefully observing and recording the movement condition of particles and the formation condition of a leakage channel in the sample during the removal process, drying and screening each layer of soil sample and the fine particles collected in each loading step, carrying out particle grading analysis, and evaluating the movement condition of the fine particles during the test.
10. The method according to claim 9, wherein in step S04, in order to facilitate the loss of fine particles, the seepage direction is from top to bottom during the process of applying the seepage pressure in a grading manner, and meanwhile, the fine particles lost during each stage of the osmotic loading process are collected, and the fine particles collected in different loading steps are separately placed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310153221.1A CN116296800A (en) | 2023-02-21 | 2023-02-21 | High-stress and large-diameter dam foundation deep coarse-grained soil penetration test device and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310153221.1A CN116296800A (en) | 2023-02-21 | 2023-02-21 | High-stress and large-diameter dam foundation deep coarse-grained soil penetration test device and method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116296800A true CN116296800A (en) | 2023-06-23 |
Family
ID=86825046
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310153221.1A Pending CN116296800A (en) | 2023-02-21 | 2023-02-21 | High-stress and large-diameter dam foundation deep coarse-grained soil penetration test device and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116296800A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116840053A (en) * | 2023-09-01 | 2023-10-03 | 河海大学 | Device for testing influence of seepage pressure on rock and soil strength |
| CN117470734A (en) * | 2023-10-26 | 2024-01-30 | 中国科学院武汉岩土力学研究所 | Salt cavern helium storage sediment permeability and fine particle migration testing device and testing method |
| CN118583750A (en) * | 2024-08-01 | 2024-09-03 | 德州博俊建筑工程有限公司 | Road pavement asphalt permeability detection device |
-
2023
- 2023-02-21 CN CN202310153221.1A patent/CN116296800A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116840053A (en) * | 2023-09-01 | 2023-10-03 | 河海大学 | Device for testing influence of seepage pressure on rock and soil strength |
| CN116840053B (en) * | 2023-09-01 | 2023-11-03 | 河海大学 | Device for testing influence of seepage pressure on rock and soil strength |
| CN117470734A (en) * | 2023-10-26 | 2024-01-30 | 中国科学院武汉岩土力学研究所 | Salt cavern helium storage sediment permeability and fine particle migration testing device and testing method |
| CN117470734B (en) * | 2023-10-26 | 2024-10-18 | 中国科学院武汉岩土力学研究所 | Salt cavern helium storage sediment permeability and fine particle migration testing device and testing method |
| CN118583750A (en) * | 2024-08-01 | 2024-09-03 | 德州博俊建筑工程有限公司 | Road pavement asphalt permeability detection device |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN116296800A (en) | High-stress and large-diameter dam foundation deep coarse-grained soil penetration test device and method | |
| Xiao et al. | Experimental investigation of the effects of suffusion on physical and geomechanic characteristics of sandy soils | |
| Ke et al. | Triaxial erosion test for evaluation of mechanical consequences of internal erosion | |
| Richards et al. | Experimental investigation of initiation of backward erosion piping in soils | |
| Viswanadham et al. | Centrifuge model tests on clay based engineered barriers subjected to differential settlements | |
| Sato et al. | Laboratory testing for evaluation of the influence of a small degree of internal erosion on deformation and stiffness | |
| Luo et al. | Effect of open-framework gravel on suffusion in sandy gravel alluvium | |
| Damavandi-Monfared et al. | Development of a miniature cone penetrometer for calibration chamber testing | |
| Yoshimine et al. | Liquefaction of clean sand with stratified structure due to segregation of particle size | |
| Wanatowski et al. | Effect of specimen preparation method on the stress-strain behavior of sand in plane-strain compression tests | |
| Wang et al. | A large-scale high-pressure erosion apparatus for studying internal erosion in gravelly soils under horizontal seepage flow | |
| Chang et al. | Laboratory investigation of initiation and development of internal erosion in soils under complex stress states | |
| Kakuturu et al. | Evaluation of the parameters influencing self-healing in earth dams | |
| Israr et al. | Experimental investigation and assessment of internal stability of granular filters under one-dimensional static and cyclic loading | |
| Luo et al. | Influence of constriction-based retention ratio on suffusion in double-layered alluvial foundation with a cutoff wall | |
| Al-Shamrani et al. | Swelling behavior under oedometric and triaxial loading conditions | |
| Ventini et al. | Analysis of transient seepage through a river embankment by means of centrifuge modelling | |
| Hori et al. | Model test and consolidation analysis of failure of a loose sandy embankment dam during seepage | |
| Bhaskar et al. | Effect of lime stabilization on the unsaturated hydraulic conductivity of clayey soil in Texas | |
| CN116380743A (en) | Discrimination method for double-layer foundation contact scouring | |
| CN115032135B (en) | Hydraulic consolidation test device and test method for measuring consolidation parameters of ultra-soft soil | |
| Chen et al. | Experimental investigation of the erosion mechanisms of piping | |
| Jegatheesan et al. | Laboratory model test on contact erosion of dispersive soil beneath pavement layers | |
| McGuire et al. | Bench-scale test apparatus for modeling column-supported embankments | |
| Israr et al. | Assessment of internal stability of filters under static and cyclic loading: an experimental and theoretical treatment |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |