CN114397155A - Preparation method of unsaturated triaxial sample without cohesive soil - Google Patents
Preparation method of unsaturated triaxial sample without cohesive soil Download PDFInfo
- Publication number
- CN114397155A CN114397155A CN202111547037.2A CN202111547037A CN114397155A CN 114397155 A CN114397155 A CN 114397155A CN 202111547037 A CN202111547037 A CN 202111547037A CN 114397155 A CN114397155 A CN 114397155A
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- sample
- bearing cylinder
- film
- rubber
- membrane
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- 239000002689 soil Substances 0.000 title claims abstract description 38
- 238000002360 preparation method Methods 0.000 title claims abstract description 10
- 229920001971 elastomer Polymers 0.000 claims abstract description 74
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 38
- 239000011521 glass Substances 0.000 claims abstract description 29
- 238000000034 method Methods 0.000 claims abstract description 17
- 238000010521 absorption reaction Methods 0.000 claims abstract description 14
- 238000005056 compaction Methods 0.000 claims abstract description 13
- 239000012528 membrane Substances 0.000 claims description 53
- 229920006395 saturated elastomer Polymers 0.000 claims description 7
- 230000000977 initiatory effect Effects 0.000 claims description 3
- 239000004033 plastic Substances 0.000 claims description 3
- 238000009434 installation Methods 0.000 claims description 2
- 238000005464 sample preparation method Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000011900 installation process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- -1 permeable plates Substances 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
Images
Classifications
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- 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
-
- 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
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
-
- 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
- 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
- G01N2001/366—Moulds; Demoulding
-
- 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
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/026—Specifications of the specimen
- G01N2203/0298—Manufacturing or preparing specimens
Abstract
The invention discloses a preparation method of an unsaturated triaxial sample of non-cohesive soil, which comprises the steps of firstly, preparing a sample in a film bearing cylinder by a stratified compaction method, then integrally moving the film bearing cylinder and a soil sample in the film bearing cylinder to a triaxial apparatus base, turning over a rubber film with the lower part of the film bearing cylinder turned outwards to the triaxial apparatus base, placing an organic glass circular plate on the top of the sample, turning over the rubber film with the upper part of the film bearing cylinder turned downwards to surround the organic glass circular plate, arranging an air outlet joint on the organic glass circular plate, connecting the air outlet joint with a water absorption ball, and then absorbing air in the sample in the rubber film by using the water absorption ball, so that the sample can keep standing under the action of self weight under the action of atmospheric pressure outside the rubber film; then lifting the film bearing cylinder upwards to separate the film bearing cylinder from the rubber film; and then, the samples are installed to carry out a normal sample flow, so that damage to the triaxial apparatus is avoided, a plurality of samples can be prepared for standby, and the test efficiency is high.
Description
Technical Field
The invention belongs to the technical field of static and dynamic triaxial tests in geotechnical tests, and is used for unsaturated triaxial samples with small water content of cohesionless soil and can also be used for preparing dry triaxial samples.
Background
The triaxial test is difficult to avoid the test of running into non-cohesive soil such as sandy soil, and the preparation of the unsaturated sandy soil sample with small water content and dryness mainly comprises the steps of firstly sequentially placing a water-impermeable plate, a rubber film and a split round mold on a base of a pressure chamber, filling the unsaturated sandy soil into the split round mold in layers to ensure the uniformity, and compacting according to the preset density. By the sample preparation method, sand grains are easy to fall into a confining pressure cavity of the triaxial apparatus if the sample preparation method is carelessly operated. In addition, unsaturated sandy soil with a small water content has a small cohesive force although it contains a certain amount of water, and dry sandy soil has no cohesive force at all, and thus, when it is compacted to a certain degree of compaction, a large compacting work is required. Because the precise axial loading devices of the triaxial apparatus are all arranged below the base, the triaxial apparatus is directly compacted or the compaction means is easy to damage the apparatus. The fundamental reason for preparing the sandy soil sample by adopting the method is that the water content is small or the dry sandy soil has cohesive force unlike cohesive soil, and is difficult to keep forming under the self gravity, but the process is easy to damage the instrument.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a preparation method of an unsaturated triaxial sample without cohesive soil, which is used for preparing the unsaturated triaxial sample with small water content of the cohesive soil and can also be used for preparing a dry triaxial sample.
A preparation method of a non-saturated triaxial sample without cohesive soil comprises the following steps:
In the above technical scheme, the film bearing cylinder is a cylinder with an upper opening and a lower opening, and the cylinder wall of the film bearing cylinder is provided with an air nozzle.
In the technical scheme, the height of the membrane bearing cylinder is the sample height plus 2 water permeable plate thicknesses different from that of the conventional membrane bearing cylinder.
In the technical scheme, a through hole is formed in the center of the organic glass circular plate, and a section of hard plastic pipe is embedded in the through hole and is externally connected with a rubber hose to serve as an air outlet joint.
In the above technical solution, step 1 includes the following steps:
a) a rubber membrane is sleeved in the membrane bearing barrel, so that the upper end and the lower end of the rubber membrane are respectively outwards turned out of the upper end and the lower end of the membrane bearing barrel, and the outwards turned parts are fastened by rubber bands; then, sucking air between the membrane cylinder and the rubber membrane by using a water sucking ball through an air nozzle on the outer side of the membrane bearing cylinder to ensure that the rubber membrane is tightly attached to the inner wall of the membrane bearing cylinder;
b) horizontally placing a sample on a table top by using a water permeable plate, then placing a cut circular filter paper sheet, and then sleeving a film bearing cylinder sleeved with a rubber film on the water permeable plate;
c) injecting prepared sandy soil with specific water content into a film bearing cylinder, and preparing a sample by layering compaction or compaction;
d) when the sample reaches a preset height, filter paper and a permeable plate are placed on the top of the sample, and the top surface of the permeable plate is basically flush with the top of the membrane bearing cylinder.
In the above technical solution, in step 3, the drain valve on the base should be closed.
The invention has the following advantages and beneficial effects:
according to the method, the sample is prepared in the film bearing cylinder according to a layered compaction method, then the sample is moved to the triaxial apparatus, the inviscid soil sample stands on the base of the triaxial apparatus like the cohesive soil sample by utilizing negative pressure, and then a normal sample installation process is carried out, so that damage to the triaxial apparatus is avoided, the prepared sample is relatively uniform, the discreteness is small, a plurality of samples can be prepared for standby by separating from the triaxial apparatus, and the test efficiency is high.
Drawings
FIG. 1 is a schematic view when a sample is prepared.
Fig. 2 is a schematic diagram of a sample standing on the base of the triaxial apparatus under negative pressure after the membrane bearing cylinder is removed.
For a person skilled in the art, other relevant figures can be obtained from the above figures without inventive effort.
Detailed Description
In order to make the technical solution of the present invention better understood, the technical solution of the present invention is further described below with reference to specific examples.
In this embodiment, a common sandy soil sample with a diameter of 39.1mm in a laboratory is taken as an example to illustrate the technical scheme of the present invention.
The invention needs the following auxiliary components besides the conventional test auxiliary components such as rubber membranes, permeable plates, water absorption balls and the like:
1) the membrane bearing cylinder has special requirements on the height which is different from the conventional experimental membrane bearing cylinder, and the height is equal to the height of a sample H +2 multiplied by the height of a water permeable plate. The other characteristics are the same as the conventional film bearing cylinder, the film bearing cylinder is in a cylinder shape with an upper opening and a lower opening, an air tap 1.1 is arranged on the cylinder wall, and the inner diameter is 39.1mm plus the thickness of the rubber film.
2) The rubber film rings are 1, the inner diameter of the rubber film rings is slightly smaller than the diameter of the sample, the height of the rubber film rings is about 10mm, and the rubber film rings are malleable.
3) The device comprises 1 organic glass round plate, wherein the diameter of the organic glass round plate is 38mm, the thickness of the organic glass round plate is 10 mm-20 mm, a through hole with the diameter of about 8 mm-10 mm is reserved in the center of the organic glass round plate, and a section of hard plastic pipe is embedded in the through hole and is externally connected with a rubber hose to serve as an air outlet joint.
The following description of the method for preparing a triaxial sample of sandy soil (i.e., non-cohesive soil) having a low water content or dry sandy soil will be made with reference to the accompanying drawings 1 to 2, which include the following steps:
a) sleeving a rubber membrane 2 in the membrane bearing barrel 1, turning the upper and lower ends of the rubber membrane 2 out of the upper and lower ports of the membrane bearing barrel 1 by 3-5 cm respectively, and fastening the turned-out part by a rubber band 3; then connecting an air nozzle 1.1 of the film bearing cylinder 1 with a water absorption ball, and absorbing redundant air between the film bearing cylinder 1 and the rubber film 2 by using the water absorption ball to enable the rubber film 2 to be tightly attached to the inner wall of the film bearing cylinder 1;
b) putting a porous plate 4 for test on a table, putting cut round filter paper sheets, and sleeving the lower port of a film bearing cylinder sleeved with a rubber film on the porous plate 4;
c) injecting prepared sandy soil with specific water content into the film bearing cylinder 1, and preparing a sample by layering compaction or compaction, wherein the quality of each layer of soil is determined according to test requirements;
d) when the sample reaches a predetermined height, filter paper and a water permeable plate 5 are placed on top of the sample, and the top surface of the water permeable plate is substantially flush with the top of the membrane bearing cylinder.
And 2, after the sample preparation in the step 1 is finished, supporting the water permeable plate at the lower part of the membrane bearing cylinder by one hand, and integrally moving the membrane bearing cylinder to the base 6 of the triaxial apparatus.
In this step, a triaxial on-board pressure head may not be used in place of the organic glass circular plate 7 of the present invention, and although the sample may be stood by applying negative pressure to the sample by using the drain line of the triaxial on-board pressure head, the membrane-bearing cartridge cannot be lifted and removed due to the presence of the drain line of the triaxial on-board pressure head and the mounting knob thereof.
And 4, immediately enclosing the sample by using a three-valve or split film after the film bearing barrel 1 is taken down, and tightly hooping a rubber band. Then the water absorption ball is unloaded, so that the interior of the sample is communicated with the atmosphere; at the moment, the sample cannot collapse due to the enclosing effect of the three valves or the split mold; then the rubber film ring 8 on the organic glass circular plate 7 is taken down, and the organic glass circular plate 7 is taken out.
And 5, installing a pressure head of the triaxial sample, and then operating a triaxial instrument control system to apply negative pressure of the sample of about 5 kPa. At this time, the three valves or the split mold around the sample are removed, and the sample is kept standing under the negative pressure. Thereafter, the sample dimensions, triaxial cell enclosure mounting and test initiation can be performed according to conventional triaxial cell operation procedures.
Spatially relative terms, such as "upper," "lower," "left," "right," and the like, may be used in the embodiments for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatial terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "lower" can encompass both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Moreover, relational terms such as "first" and "second," and the like, may be used solely to distinguish one element from another element having the same name, without necessarily requiring or implying any actual such relationship or order between such elements.
The invention has been described in an illustrative manner, and it is to be understood that any simple variations, modifications or other equivalent changes which can be made by one skilled in the art without departing from the spirit of the invention fall within the scope of the invention.
Claims (6)
1. A preparation method of a non-saturated triaxial sample without cohesive soil is characterized by comprising the following steps:
step 1, preparing samples of prepared sandy soil with water content in a film bearing cylinder with a special height according to a layering compaction method;
step 2, after the sample preparation in the step 1 is finished, integrally moving the membrane bearing cylinder and the soil sample in the membrane bearing cylinder to a base of the triaxial apparatus;
step 3, turning over the rubber membrane with the lower part of the membrane bearing cylinder turned outwards to a base of the triaxial apparatus, and hooping the rubber membrane on the base by using a rubber band; placing an organic glass circular plate on the top of the sample, wherein the diameter of the organic glass circular plate is slightly smaller than the inner diameter of the film bearing cylinder, turning up a rubber film turned downwards on the upper part of the film bearing cylinder to surround the organic glass circular plate, and hooping the rubber film on the organic glass circular plate by a rubber film ring, so that the upper part and the lower part of the rubber film wrapping the sample are respectively provided with a rubber band and the rubber film ring for hooping, and the sample forms a closed space isolated from the atmosphere; an air outlet joint is arranged on the organic glass circular plate, the air outlet joint is connected with a water absorption ball, and then the water absorption ball is used for absorbing air in a sample in the rubber film, so that the sample can keep standing under the action of self weight under the action of atmospheric pressure outside the rubber film; then lifting the film bearing cylinder upwards to separate the film bearing cylinder from the rubber film;
step 4, taking down the membrane bearing cylinder, and enclosing a sample by using a three-flap membrane or an opposite-opening membrane; then the water absorption ball is unloaded, so that the interior of the sample is communicated with the atmosphere; taking down the organic glass circular plate;
step 5, installing a pressure head of the triaxial sample, operating a triaxial apparatus to apply negative pressure to the sample, unloading the three valves or split molds around the sample, and keeping the sample standing under the action of the negative pressure; thereafter, the sample dimensions, confining pressure chamber cover installation and test initiation can be performed according to conventional triaxial apparatus procedures.
2. The method of preparing a non-saturated triaxial sample without cohesive soil of claim 1, wherein: the film bearing cylinder is a cylinder with an upper opening and a lower opening, and the cylinder wall of the film bearing cylinder is provided with an air nozzle.
3. The method of preparing a non-saturated triaxial sample without cohesive soil of claim 2, wherein: the height of the film bearing cylinder is the sample height plus the thickness of 2 water permeable plates.
4. The method of preparing a non-saturated triaxial sample without cohesive soil of claim 1, wherein: a through hole is arranged in the center of the organic glass circular plate, and a section of hard plastic pipe is embedded in the through hole and is externally connected with a rubber hose to serve as an air outlet joint.
5. The method of preparing a non-saturated triaxial sample without cohesive soil of claim 1, wherein: the step 1 comprises the following steps:
a) a rubber membrane is sleeved in the membrane bearing barrel, so that the upper end and the lower end of the rubber membrane are respectively outwards turned out of the upper end and the lower end of the membrane bearing barrel, and the outwards turned parts are fastened by rubber bands; then, sucking air between the membrane cylinder and the rubber membrane by using a water sucking ball through an air nozzle on the outer side of the membrane bearing cylinder to ensure that the rubber membrane is tightly attached to the inner wall of the membrane bearing cylinder;
b) horizontally placing a sample on a table top by using a water permeable plate, then placing a cut circular filter paper sheet, and then sleeving a film bearing cylinder sleeved with a rubber film on the water permeable plate;
c) injecting prepared sandy soil with specific water content into a film bearing cylinder, and preparing a sample by layering compaction or compaction;
d) when the sample reaches a preset height, filter paper and a permeable plate are placed on the top of the sample, and the top surface of the permeable plate is basically flush with the top of the membrane bearing cylinder.
6. The method of preparing a non-saturated triaxial sample without cohesive soil of claim 1, wherein: and step 3, closing a drainage valve on the base.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111547037.2A CN114397155B (en) | 2021-12-16 | 2021-12-16 | Preparation method of non-clay unsaturated triaxial sample |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111547037.2A CN114397155B (en) | 2021-12-16 | 2021-12-16 | Preparation method of non-clay unsaturated triaxial sample |
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| CN114397155A true CN114397155A (en) | 2022-04-26 |
| CN114397155B CN114397155B (en) | 2023-10-27 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117347237B (en) * | 2023-08-24 | 2024-05-07 | 南京交通职业技术学院 | Flexible wall structure for preventing dirt mud solidification heavy metal infiltration |
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| CN107179227A (en) * | 2017-06-27 | 2017-09-19 | 同济大学 | A kind of triaxial test sample preparation device |
| CN111103185A (en) * | 2020-01-13 | 2020-05-05 | 石河子大学 | Spinning type coarse-grained soil triaxial experiment sample preparation device and sample preparation method |
| WO2020103356A1 (en) * | 2018-11-21 | 2020-05-28 | 中国科学院武汉岩土力学研究所 | Specimen preparation method for eliminating membrane penetration effect on highly-weathered rock |
| CN212275392U (en) * | 2020-06-22 | 2021-01-01 | 哈尔滨理工大学 | A can inhale formula system appearance device for sandy soil triaxial experiment |
| AU2020103902A4 (en) * | 2020-12-04 | 2021-02-11 | Nanjing Technology University | An aeration sample preparation equipment and its preparation method |
-
2021
- 2021-12-16 CN CN202111547037.2A patent/CN114397155B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107179227A (en) * | 2017-06-27 | 2017-09-19 | 同济大学 | A kind of triaxial test sample preparation device |
| WO2020103356A1 (en) * | 2018-11-21 | 2020-05-28 | 中国科学院武汉岩土力学研究所 | Specimen preparation method for eliminating membrane penetration effect on highly-weathered rock |
| CN111103185A (en) * | 2020-01-13 | 2020-05-05 | 石河子大学 | Spinning type coarse-grained soil triaxial experiment sample preparation device and sample preparation method |
| CN212275392U (en) * | 2020-06-22 | 2021-01-01 | 哈尔滨理工大学 | A can inhale formula system appearance device for sandy soil triaxial experiment |
| AU2020103902A4 (en) * | 2020-12-04 | 2021-02-11 | Nanjing Technology University | An aeration sample preparation equipment and its preparation method |
Non-Patent Citations (2)
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117347237B (en) * | 2023-08-24 | 2024-05-07 | 南京交通职业技术学院 | Flexible wall structure for preventing dirt mud solidification heavy metal infiltration |
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| CN114397155B (en) | 2023-10-27 |
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