CN115184242A - Device and method for measuring reverse filtration particle size required by seepage protection of cohesive soil - Google Patents
Device and method for measuring reverse filtration particle size required by seepage protection of cohesive soil Download PDFInfo
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- CN115184242A CN115184242A CN202211024720.2A CN202211024720A CN115184242A CN 115184242 A CN115184242 A CN 115184242A CN 202211024720 A CN202211024720 A CN 202211024720A CN 115184242 A CN115184242 A CN 115184242A
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- 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
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- 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
- G01N15/0806—Details, e.g. sample holders, mounting samples for testing
Abstract
The invention discloses a device and a method for measuring reverse filtration particle size required by cohesive soil seepage protection, wherein the measuring device comprises a reverse filtration particle size verifier, the reverse filtration particle size verifier comprises a straight container for containing a cohesive soil sample required by a test, the front end and the rear end of the straight container are provided with openings, the front end of the straight container is provided with a high-pressure cap, the middle part of the high-pressure cap is provided with a through hole, the through hole is provided with a conduit, and the conduit is connected with a high-pressure water source; a sand cushion layer is arranged at the front end of the straight-tube container; the rear end of the straight cylinder container is provided with a second porous steel plate and a reverse filtering container; a soil seepage water collector is arranged below the water outlet. The measurement method includes steps S1 to S9. The invention provides a testing method for obtaining the particle size required by the seepage protection of the cohesive soil material with a certain safety reserve level through multiple tests of reverse filtering materials with different hydraulic power drops and different particle sizes, and has important practical value and theoretical significance for fundamentally improving the guarantee level of the seepage prevention safety of an earth-rock dam.
Description
Technical Field
The invention relates to the field of geotechnical engineering tests, in particular to a device and a method for measuring the reverse filter particle size required by seepage protection of cohesive soil.
Background
Osmotic damage is the most common type of damage to earth and rockfill dams, except for overtopping. Due to the reasons of uneven material characteristic distribution, defects in the position of a dam body part and the like, an earth core wall of a core-wall rock-fill dam, an earth impervious body of a homogeneous dam or a partition dam, a cohesive soil layer in a covering layer and the like can be in a high hydraulic pressure drop condition for a long time. If the reverse filtration particle size is not reasonable or the particle size of the soil layer downstream of the seepage diameter in the covering layer is too large, the clay in the soil body cannot be protected, and the clay may run off under the seepage action and cause seepage deformation, thereby endangering the safety of the earth-rock dam.
The reverse filtration is a main technical means for protecting a soil impervious body and avoiding osmotic damage, is originally developed in 20-40 years of the 20 th century, forms two types of reverse filtration rules aiming at non-cohesive soil and cohesive soil through years of development, and is generally represented by the particle diameter ratio of a reverse filtration material to a protected material. The Sherard criterion is used as a generation aiming at the reverse filtering criterion of the cohesive soilTable, states that when the protected soil is mainly fine silt and clay (the content of particles with the particle size of less than 0.075mm is more than 85%), the filter material D 10 Should be smaller than protected soil d 85 9 times of D, when D is calculated 10 When the diameter is less than 0.2mm, D is required 10 Is 0.2mm. That is, when the soil to be protected is cohesive soil having a small particle diameter, i.e., d 85 <At 0.02mm (i.e. 1/9 of 0.2 mm), the reverse filtration criterion is in a qualitative state and no longer has a quantitative choice, and D is taken 10 Is 0.2mm. The engineering designed according to the anti-filtration criterion has low anti-seepage safety level and small reserve of the soil anti-seepage body, possibly generates clay particle seepage accidents in the anti-seepage body and threatens the engineering safety, and the typical case is engineering such as Canada wave Taiji mountain and the like.
What is hard to quantify corresponds to the above-mentioned back-filtration criteria is the lack of an apparatus and method for accurately and conveniently determining the back-filtration particle size required for the percolation protection of cohesive soil materials. Classic osmotic characteristic test device, to the category that the mainly used differentiateed the infiltration destruction when cohesive soil develoies the experiment, than descending slightly big can lead to the whole of soil sample to lift or part, can not survey the protective capacities to cohesive soil under the high hydraulic power of corresponding on-the-spot extreme condition than the descending effect, be difficult to survey the required anti-filtration particle diameter of cohesive soil material seepage protection.
The actual agglomeration state under the viscous soil working condition is different from the viscosity grain grade distribution curve measured after dispersion, the reverse filtration protection capability is not completely based on the geometric characteristics of the viscosity grains, the accurate required reverse filtration grain diameter cannot be obtained through simple qualitative or quantitative judgment, and the measurement needs to be carried out through a clear and reliable test means. In addition, the migration modes of the sticky particle aggregates under different mineral types and pore water conditions under different hydraulic specific drop actions are different, and the anti-filtration protection capacity has different safety reserve levels under different specific drop actions. Therefore, a device and a method for specially determining the reverse filter particle size required by the seepage protection of the cohesive soil are needed.
Disclosure of Invention
In response to the above-described deficiencies of the prior art, the present invention provides a device and technique for measuring the protective capacity of a uniform reverse filter material against cementitious soil at high hydraulic force drops.
In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:
the device comprises a reverse filtration particle size verifier, wherein the reverse filtration particle size verifier comprises a straight container for containing a cohesive soil sample required by a test, the front end of the straight container is provided with an opening, the front end of the straight container is provided with a high-pressure cap, the middle part of the high-pressure cap is provided with a through hole, the through hole is provided with a conduit, and the conduit is connected with a high-pressure water source; a sand cushion layer is arranged at the front end of the straight-tube container, a second porous steel plate is arranged at the rear end of the straight-tube container, and a cohesive soil sample is arranged between the sand cushion layer and the second porous steel plate; the back end of the straight cylinder container is provided with a reverse filtering container;
the reverse filtering container comprises a circular steel cylinder connected with the rear end of the straight cylinder container, a reverse filtering material layer with uniform gradation is filled in the circular steel cylinder, the rear end of the circular steel cylinder is connected with a variable cross-section pipe, the side surface of the variable cross-section pipe is communicated with the circular steel cylinder, the variable cross-section pipe is vertical to the circular steel cylinder, the end part of the variable cross-section pipe extends downwards at an angle of 45 degrees, and the circular steel cylinder and the straight cylinder container are obliquely arranged on the first support at an angle of 45 degrees upwards;
the end part of the variable cross-section pipe is provided with a water outlet, the water outlet is a vertical cross-section opening formed at the end part of the variable cross-section pipe, and a soil seepage water collector for measuring the amount of flowing silt and water is arranged below the water outlet.
Furthermore, a first porous steel plate is arranged at the joint of the circular steel cylinder and the variable cross-section pipe.
Furthermore, a metal filter screen is arranged on one side, close to the circular steel cylinder, of the first porous steel plate.
Furthermore, one side of the second porous steel plate, which is close to the straight-tube container, is provided with an annular convex rib, and the cross section of the convex rib is in an isosceles triangle shape.
Furthermore, the high-pressure cap is in threaded connection with the outer wall of the straight-tube container, a hexagonal prism is arranged on the high-pressure cap, and a hexagonal outline is arranged at the front end of the straight-tube container; the outer wall of the straight cylinder container is in threaded connection with the inner part of the round steel cylinder.
Further, a sealing ring is arranged between the through hole and the guide pipe.
Furthermore, the soil seepage water collector comprises a balance, a glass cylinder is placed above the balance, a suspended filter screen bucket is arranged in the glass cylinder, the upper end of the filter screen bucket is connected with a tension sensor through a lifting rope, the tension sensor is hung on the second support through the lifting rope, a plurality of through holes are formed in the lower end of the filter screen bucket, and filter paper is placed at the bottom of the filter screen bucket.
The method for measuring the reverse filtration particle size by using the device for measuring the reverse filtration particle size required by the seepage protection of the cohesive soil material comprises the following steps:
s1: selecting n types of anti-filtering materials with different uniform particle sizes, wherein the particle sizes of the n types of anti-filtering materials are sequentially reduced, and the particle size of the n types of anti-filtering materials is D 10 1 、D 10 2 、…、D 10 n ；
S2: the variable cross-section tube is firstly placed horizontally, and the grain diameter is taken as D 10 1 The reverse filtering material is filled into a round steel cylinder with a first porous steel plate, compacted according to a set density, and a straight cylinder container with a second porous steel plate is screwed into the end part of the round steel cylinder; filling the viscous soil material to be measured into the straight container, and laying a surface sand cushion;
s3: assembling a high-pressure cap and a variable cross-section pipe, placing the assembled reversed filter particle size verifier on a first support, and preparing a soil and water seepage collector; injecting water into the high-pressure cap cover by adopting a high-pressure water source through a guide pipe to apply a certain water head to the front end of the viscous soil;
s4: tension value F detected by tension sensor Tension force And the scale reading real-time monitors the water and soil loss amount, and the tensile force value F is utilized Tension force Calculating the mass m and the volume v of the flowing-out soil on the filter paper;
s5: calculating the infiltration and erosion rate of the cohesive soil material by using the mass m of the outflowing soil; the erosion rate = (mass M of soil outflow/initial mass M of cohesive soil material) × 100%;
s6: calculating the hydraulic power ratio drop i when the corrosion rate reaches 20% j ：i j H is the water head applied to the front end of the cohesive soil material, and H is the height of the clay soil sample; if the corrosion rate is always lower than 20 percent, taking i j ＝10000。
S7: calculated particle diameter of D 10 1 Safety factor S of the reverse filter material 1 ：
Wherein i work The hydraulic power drop of the cohesive soil during normal work and stable seepage;
s8: repeating the steps S2-S7, replacing the reverse filtering material in the round steel cylinder in the step S2, and calculating the residual grain diameter to be D 10 2 ，…，D 10 n Safety factor S corresponding to the reverse filter material 2 ，···，S n ；
S9: the obtained safety factor S 1 ，S 2 ，···、S n Safety factors S respectively corresponding to engineering requirements s 0 Carrying out comparison;
if S i <S s 0 And S i+1 ≥S s 0 Then the particle diameter D is 10 i+1 The corresponding reverse filtering material can meet the seepage protection condition of the cohesive soil material in the project; s. the i Safety factor, S, corresponding to the i-th reverse filter material i+1 The safety factor corresponding to the (i + 1) th anti-filtration material; d 10 i+1 The grain size of the (i + 1) th anti-filtration material;
otherwise, the particle diameter D 10 i+1 The corresponding reverse filter material still does not meet the seepage protection condition of the cohesive soil materials in the project.
Further, the method for calculating the mass m in step S4 is as follows:
wherein G is s The specific gravity of soil particles flowing out of the filter paper is g, and g is gravity acceleration;
the method for calculating the volume v is:
where ρ is w Is the density of water.
The invention has the beneficial effects that: the invention provides a method for determining the reverse filtration particle size required by the seepage protection of cohesive soil materials under a certain safety margin level through multiple tests of reverse filtration materials with different hydraulic pressure drops and different particle sizes, provides a quantitative and simple test method for determining the required reverse filtration particle size for specific protected cohesive soil materials in actual engineering, and sets the reverse filtration particle size according to a certain risk level so that the determined reverse filtration particle size meets the engineering safety requirement. The research can determine the seepage protection capability of the uniform reverse filter material on the cohesive soil material under the condition of high hydraulic pressure drop, and the test method for obtaining the particle size required by the seepage protection of the cohesive soil material under a certain safe reserve level has important practical value and theoretical significance for fundamentally improving the guarantee level of seepage prevention safety of the earth-rock dam.
Drawings
FIG. 1 is a view showing the structure of an apparatus for measuring the reverse filtration particle diameter required for the seepage protection of a viscous soil material.
Fig. 2 is a structural view of a second perforated steel plate.
FIG. 3 is a structural view of the rib.
The device comprises a 1-reverse filtration particle size verifier, a 2-soil seepage water collector, a 3-high-pressure cap, a 4-straight cylinder container, a 5-reverse filtration container, a 6-guide pipe, a 7-sealing ring, an 8-sand cushion layer, a 9-reverse filtration material layer, a 10-cohesive soil material layer, an 11-high-pressure water source, a 12-round steel cylinder, a 13-variable cross-section pipe, a 14-second porous steel plate, a 15-first porous steel plate, a 16-metal filter screen, a 17-water outlet, an 18-glass cylinder, a 19-tension sensor, a 20-filter screen bucket, a 21-balance, 22-filter paper, a 23-first support, a 24-second support and a 25-convex rib.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.
As shown in fig. 1-3, the device for determining the reverse filtration particle size required by the seepage protection of the cohesive soil material comprises a straight container 4 for containing a cohesive soil sample required by a test, wherein the front end of the straight container 4 is open, a high-pressure cap 3 is arranged at the front end of the straight container 4, a through hole is formed in the middle of the high-pressure cap 3, a conduit 6 is arranged on the through hole, and the conduit 6 is connected with a high-pressure water source 11; a sand cushion layer 8 is arranged at the front end of the straight-tube container 4, a second porous steel plate 14 is arranged at the rear end of the straight-tube container 4, and the cohesive soil sample is arranged between the sand cushion layer 8 and the second porous steel plate 14; the rear end of the straight cylinder container 4 is provided with a reverse filtering container 5.
The reverse filtering container 5 comprises a circular steel cylinder 12 connected with the rear end of the straight cylinder container 4, a uniform grading reverse filtering material layer 9 is filled in the circular steel cylinder 12, the rear end of the circular steel cylinder 12 is connected with a variable cross-section pipe 13, the side surface of the variable cross-section pipe 13 is communicated with the circular steel cylinder 12, the variable cross-section pipe 13 is perpendicular to the circular steel cylinder 12, the end part of the variable cross-section pipe 13 extends downwards at an angle of 45 degrees, and the circular steel cylinder 12 and the straight cylinder container 4 are obliquely arranged on the first support 23 at an upward angle of 45 degrees.
The end part of the variable cross-section pipe 13 is provided with a water outlet 17, the water outlet 17 is a vertical cross-section opening formed at the end part of the variable cross-section pipe 13, and a soil seepage water collector 2 for measuring the amount of flowing-out silt and water is arranged below the water outlet 17.
In this embodiment, a first porous steel plate 15 is disposed at a joint between the circular steel cylinder 12 and the variable cross-section pipe 13, a metal filter screen 16 is disposed on one side of the first porous steel plate 15 close to the circular steel cylinder 12, and the metal filter screen 16 can ensure that reverse filtering particles do not flow into the seepage water collector, and only particles in the soil sample flow into the seepage water collector. The diameter of the distribution range of the holes on the second porous steel plate 14 is smaller than that of the straight-tube container, an annular convex rib 25 is arranged on one side, close to the straight-tube container 4, of the second porous steel plate 14, and the cross section of the convex rib 25 is in the shape of an isosceles triangle. The distribution range of the holes is smaller than the diameter of the straight-tube container, and the convex ribs 25 are arranged, so that the influence of the preferential seepage of the side wall can be effectively avoided.
The high-pressure cap 3 is in threaded connection with the outer wall of the straight-tube container 4, a hexagonal prism is arranged on the high-pressure cap 3, and a hexagonal outline is arranged at the lower end of the straight-tube container 4; the outer wall of the straight cylinder container 4 is connected with the inner thread of the round steel cylinder 12. A sealing ring 7 is arranged between the through hole and the conduit 6.
In this embodiment, the earth-water seepage collector 2 comprises a balance 21, a glass cylinder 18 is placed above the balance 21, a suspended filter screen bucket 20 is arranged in the glass cylinder 18, the upper end of the filter screen bucket 20 is connected with a tension sensor 19 through a lifting rope, the tension sensor 19 is suspended on a second support 24 through the lifting rope, a plurality of through holes are formed in the lower end of the filter screen bucket 20, and filter paper 22 is placed at the bottom of the filter screen bucket 20.
The use principle of the testing device provided by the invention is as follows:
firstly, assembling a device, arranging a metal filter screen 16 on the bottom surface of a circular steel cylinder 12, then loading a reverse filter material with uniform gradation (the grain size of the soil material is selected according to the grain size of the soil material tested in a straight cylinder container 4), and compacting according to set density; screwing the straight-tube container 4 on the reverse filtering container 5 with a circular steel tube 12 and a variable cross-section tube 13; compacting cohesive soil materials in the straight container 4, paving a sand cushion layer 8 or a porous rigid permeable plate on the upper surface of the cohesive soil material layer 10, and screwing the high-pressure cap 3 on the upper side of the straight container 4; after the high-pressure cap 3 is connected with the guide pipe 6, the anti-filtration particle size verifier 1 is placed on the first bracket 23; placing the glass cylinder 18 on a balance 21, placing filter paper 22 on the bottom surface of the filter screen bucket 20, connecting the tension sensor 19 to the lower side of a second bracket 24, and hanging the filter screen bucket 20 on the lower side of the tension sensor 19; the earth-water collector 2 is placed below the water outlet 17. Before the test, a small amount of clear water is injected into the soil seepage device to ensure that the water level exceeds the bottom of the filter screen bucket 20.
The method for measuring the reverse filtration particle size by adopting the device for measuring the reverse filtration particle size required by the seepage protection of the cohesive soil material comprises the following steps:
s1: selecting n types of anti-filtering materials with different uniform particle sizes, wherein the particle sizes of the n types of anti-filtering materials are sequentially reduced, and the particle size of the n types of anti-filtering materials is D 10 1 、D 10 2 、…、D 10 n ；
S2: the variable cross-section tube 13 is firstly horizontally placed; taking the particle diameter as D 10 1 The reverse filtering material is filled into a round steel cylinder 12 with a first porous steel plate 15, the material is compacted according to a set density, and a straight cylinder container 4 with a second porous steel plate 14 is screwed into the end part of the round steel cylinder 12; filling the viscous soil material to be measured into the straight container 4, and laying a surface sand cushion 8;
s3: assembling a high-pressure cap 3 and a variable cross-section pipe 13 to prepare a percolating soil water collector 2; injecting water into the high-pressure cap 3 by the high-pressure water source 11 through the conduit 6, applying a certain water head to the front end of the cohesive soil material, adjusting the high-pressure water source 11 to a high water ratio reduced to 1, keeping the high water ratio, and closing the high-pressure water source 11 to stop injecting water after a set time t;
s4: tension value F detected by tension sensor 19 Tension force And the water and soil loss is monitored in real time by the indication of the balance 21, and the tensile value F is utilized Tension force Calculating the mass m and the volume v of the soil flowing out of the filter paper;
the method for calculating the mass m comprises the following steps:
wherein G is s The specific gravity of the soil particles flowing out of the filter paper 22, and g is the gravity acceleration;
the method for calculating the volume v is:
where ρ is w Is the density of water.
S5: calculating the infiltration and erosion rate of the cohesive soil material by using the mass m of the outflowing soil; the erosion rate = (mass M of soil outflow/initial mass M of cohesive soil material) × 100%;
s6: calculating the hydraulic power ratio drop i when the corrosion rate reaches 20% j ：i j H/H, wherein H is the water head applied to the front end of the cohesive soil material, and H is the height of a clay soil sample; if oozingIf the etching rate is always lower than 20 percent, i is taken j ＝10000。
S7: calculated particle diameter of D 10 1 Safety factor S of the reverse filter material 1 ：
Wherein i work The hydraulic power drop of the cohesive soil during normal work and stable seepage; for thin impervious body earth-rock dam i work Normally less than 10, for cohesive soil i of the covering layer work Also much lower than 20;
s8: repeating the steps S2-S7, replacing the anti-filtering material in the circular steel cylinder 12 in the step S2, and calculating the residual grain diameter to be D 10 2 ，…，D 10 n Safety factor S corresponding to the reverse filter material 2 ，···，S n ；
S9: the obtained safety factor S 1 ，S 2 ，···、S n Safety factors S respectively corresponding to engineering requirements s 0 Comparing;
if S i <S s 0 And S i+1 ≥S s 0 Then the particle diameter D is 10 i+1 The corresponding reverse filter material can meet the seepage protection condition of the cohesive soil material in the project; s. the i Safety factor, S, corresponding to the i-th reverse filter material i+1 The safety factor corresponding to the (i + 1) th anti-filtration material; d 10 i+1 The grain size of the (i + 1) th anti-filtration material;
otherwise, the particle diameter D is 10 i+1 The corresponding reverse filter material still does not meet the seepage protection condition of the cohesive soil materials in the project.
The invention provides a method for determining the reverse filtration particle size required by the seepage protection of cohesive soil materials under a certain safety margin level through multiple tests of reverse filtration materials with different hydraulic power drops and different particle sizes, provides a quantitative and simple test method for determining the required reverse filtration particle size aiming at specific protected cohesive soil materials in actual engineering, and sets the reverse filtration particle size according to a certain risk level to ensure that the determined reverse filtration particle size meets the engineering safety requirement. The research can determine the seepage protection capability of the uniform reverse filter material on the cohesive soil material under the condition of high hydraulic ratio reduction, and the test method for obtaining the particle size required by the seepage protection of the cohesive soil material under a certain safety reserve level has important practical value and theoretical significance for fundamentally improving the anti-seepage safety guarantee level of the earth-rock dam.
Claims (9)
1. The device for measuring the reverse filtration particle size required by the seepage protection of the cohesive soil material is characterized by comprising a reverse filtration particle size verifier, wherein the reverse filtration particle size verifier comprises a straight container for containing a cohesive soil sample required by a test, the front end of the straight container is provided with an opening, the front end of the straight container is provided with a high-pressure cap, the middle part of the high-pressure cap is provided with a through hole, the through hole is provided with a guide pipe, and the guide pipe is connected with a high-pressure water source; a sand cushion layer is arranged at the front end of the straight-tube container, a second porous steel plate is arranged at the rear end of the straight-tube container, and the cohesive soil sample is arranged between the sand cushion layer and the second porous steel plate; the rear end of the straight cylinder container is provided with a reverse filtering container;
the reverse filtration container comprises a circular steel cylinder connected with the rear end of a straight cylinder container, a uniform gradation reverse filtration material layer is filled in the circular steel cylinder, the rear end of the circular steel cylinder is connected with a variable cross-section pipe, the side surface of the variable cross-section pipe is communicated with the circular steel cylinder, the variable cross-section pipe is vertical to the circular steel cylinder, the end part of the variable cross-section pipe extends downwards at an angle of 45 degrees, and the circular steel cylinder and the straight cylinder container are obliquely arranged on a first support at an angle of 45 degrees upwards;
the end part of the variable cross-section pipe is provided with a water outlet, the water outlet is a vertical cross-section opening formed at the end part of the variable cross-section pipe, and a soil seepage water collector for measuring the amount of flowing silt and water is arranged below the water outlet.
2. The apparatus for determining the reverse filtering grain size required by the seepage protection of the cohesive soil material as claimed in claim 1, wherein a first porous steel plate is arranged at the joint of the circular steel cylinder and the variable cross-section pipe.
3. The apparatus for determining a reverse filtering grain size required by the seepage protection of the cohesive soil as claimed in claim 2, wherein a metal screen is disposed on one side of the first perforated steel plate close to the circular steel cylinder.
4. The apparatus for determining the reverse filtering grain size required by the seepage protection of the cohesive soil material as claimed in claim 1, wherein the second porous steel plate is provided with an annular rib at one side close to the straight cylindrical container, and the section of the rib is isosceles triangle.
5. The device for measuring the reverse filtration particle size required by the seepage protection of the cohesive soil material as claimed in claim 1, wherein the high-pressure cap cover is in threaded connection with the outer wall of the straight container, a hexagonal prism is arranged on the high-pressure cap cover, and a hexagonal outline is arranged at the front end of the straight container; the outer wall of the straight cylinder container is in threaded connection with the inner part of the round steel cylinder.
6. The apparatus for determining a reverse filter particle size required for the seepage protection of cementitious soil as claimed in claim 1, wherein a sealing ring is provided between the through hole and the duct.
7. The device for measuring the reverse filter particle size required by the seepage protection of the cohesive soil material as claimed in claim 1, wherein the seepage soil water collector comprises a balance, a glass cylinder is placed above the balance, a suspended filter screen bucket is arranged in the glass cylinder, the upper end of the filter screen bucket is connected with the tension sensor through a lifting rope, the tension sensor is suspended on the second support through the lifting rope, a plurality of through holes are formed in the lower end of the filter screen bucket, and filter paper is placed at the bottom of the filter screen bucket.
8. A method for measuring a reverse filtration particle size using the apparatus for measuring a reverse filtration particle size required for the seepage protection of a cementitious soil material according to any one of claims 1 to 7, comprising the steps of:
s1: selecting n types of anti-filtering materials with different uniform particle sizes, wherein the particle sizes of the n types of anti-filtering materials are sequentially reduced, and the particle size of the n types of anti-filtering materials is D 10 1 、D 10 2 、…、D 10 n ；
S2: the variable cross-section tube is firstly placed horizontally, and the grain diameter is taken as D 10 1 The reverse filtering material is filled into a round steel cylinder with a first porous steel plate, compacted according to a set density, and a straight cylinder container with a second porous steel plate is screwed into the end part of the round steel cylinder; filling the viscous soil material to be measured into the straight container, and laying a surface sand cushion layer;
s3: assembling a high-pressure cap and a variable cross-section pipe, placing the assembled reverse filtering particle size verifier on a first support, and preparing a soil and water seepage collector; injecting water into the high-pressure cap cover by adopting a high-pressure water source through a guide pipe to apply a certain water head to the front end of the viscous soil;
s4: tension value F detected by tension sensor Tension force And the scale number is used for monitoring the soil and water loss in real time, and the tension value F is used Tension force Calculating the mass m and the volume v of the flowing-out soil on the filter paper;
s5: calculating the infiltration and erosion rate of the cohesive soil material by using the mass m of the outflowing soil; the erosion rate = (mass M of soil outflow/initial mass M of cohesive soil material) × 100%;
s6: calculating the hydraulic power ratio drop i when the corrosion rate reaches 20% j ：i j H is the water head applied to the front end of the cohesive soil material, and H is the height of the clay soil sample; if the corrosion rate is always lower than 20%, taking i j ＝10000。
S7: calculated particle diameter of D 10 1 Safety factor S of the reverse filter material 1 ：
Wherein i work The hydraulic power ratio drop of the cohesive soil during normal work and stable seepage;
s8: repeating steps S2-S7, replacing the reverse filtering material in the round steel cylinder in the step S2, and calculating the residual grain diameter to be D 10 2 ，…，D 10 n Safety factor S corresponding to the reverse filter material 2 ，···，S n ；
S9: the obtained safety factor S 1 ，S 2 ，···、S n Safety factors S respectively corresponding to engineering requirements s 0 Comparing;
if S i <S s 0 And S i+1 ≥S s 0 Then the particle diameter D 10 i+1 The corresponding reverse filtering material can meet the seepage protection condition of the cohesive soil material in the project; s i Safety factor, S, corresponding to the i-th reverse filter material i+1 The safety factor corresponding to the (i + 1) th anti-filtration material; d 10 i+1 The grain size of the (i + 1) th anti-filtration material;
otherwise, the particle diameter D 10 i+1 The corresponding reverse filter material still does not meet the seepage protection condition of the cohesive soil materials in the project.
9. The method for determining the reverse filtering particle size required by the seepage protection of the cohesive soil material as claimed in claim 8, wherein the method for calculating the mass m in the step S4 comprises the following steps:
wherein G is s The specific gravity of soil particles flowing out of the filter paper is g, and g is the gravity acceleration;
the method for calculating the volume v is as follows:
where ρ is w Is the density of water.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211024720.2A CN115184242B (en) | 2022-08-25 | 2022-08-25 | Device and method for measuring reverse filtration particle size required by cohesive soil material seepage protection |
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| CN202211024720.2A CN115184242B (en) | 2022-08-25 | 2022-08-25 | Device and method for measuring reverse filtration particle size required by cohesive soil material seepage protection |
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| CN115184242A true CN115184242A (en) | 2022-10-14 |
| CN115184242B CN115184242B (en) | 2023-05-05 |
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| CN202211024720.2A Active CN115184242B (en) | 2022-08-25 | 2022-08-25 | Device and method for measuring reverse filtration particle size required by cohesive soil material seepage protection |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117107769A (en) * | 2023-10-23 | 2023-11-24 | 水利部交通运输部国家能源局南京水利科学研究院 | Grading-considered soil dam leakage channel electric repairing device and grading-considered soil dam leakage channel electric repairing method |
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| CN112504941A (en) * | 2020-12-17 | 2021-03-16 | 北京航空航天大学 | Tester for researching radial permeability characteristics of soil body |
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| CN204855317U (en) * | 2015-06-03 | 2015-12-09 | 中国能源建设集团甘肃省电力设计院有限公司 | Device is jointly surveyd with lixiviation hog factor to coarse grain soil sample osmotic coefficient |
| CN206990577U (en) * | 2017-07-07 | 2018-02-09 | 农业部环境保护科研监测所 | Small-sized vegetable plot original position soil evaporation measurement device |
| US10809175B1 (en) * | 2020-06-04 | 2020-10-20 | Prince Mohammad Bin Fahd University | Device and method for soil hydraulic permeability measurement |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117107769A (en) * | 2023-10-23 | 2023-11-24 | 水利部交通运输部国家能源局南京水利科学研究院 | Grading-considered soil dam leakage channel electric repairing device and grading-considered soil dam leakage channel electric repairing method |
| CN117107769B (en) * | 2023-10-23 | 2024-01-23 | 水利部交通运输部国家能源局南京水利科学研究院 | Grading-considered soil dam leakage channel electric repairing device and grading-considered soil dam leakage channel electric repairing method |
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| CN115184242B (en) | 2023-05-05 |
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