CN111024467B - Remolded soil batch sample preparation device and sample preparation method - Google Patents
Remolded soil batch sample preparation device and sample preparation method Download PDFInfo
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- CN111024467B CN111024467B CN201911325700.7A CN201911325700A CN111024467B CN 111024467 B CN111024467 B CN 111024467B CN 201911325700 A CN201911325700 A CN 201911325700A CN 111024467 B CN111024467 B CN 111024467B
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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
- 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
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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
- G01N1/36—Embedding or analogous mounting of samples
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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
- G01N1/36—Embedding or analogous mounting of samples
- G01N2001/366—Moulds; Demoulding
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Abstract
The invention discloses a remolded soil batch sample preparation device and a sample preparation method, wherein the remolded soil batch sample preparation device comprises a counterforce frame module, a sample preparation module and a compaction module; the reaction frame module comprises a reaction cover plate, a movable bearing plate, a bottom plate and a vertical strut; the sample preparation module comprises a plurality of sets of sample preparation barrel assemblies arranged between the movable bearing plate and the counter-force cover plate; each sample making cylinder assembly comprises an odd number of sleeves which are coaxially arranged and are mutually clamped; the compaction module comprises a jacking device and a compaction piston; each compaction piston comprises a large pressure head, a small pressure head and a connecting rod which are coaxially arranged. The outer wall surface of the small pressure head can be in sliding fit with the inner wall surface of the sleeve; the area of the large pressure head is larger than the inner diameter of the sleeve; a plurality of exhaust holes are uniformly distributed on the end surface of the small pressure head. In addition, two ends are adopted to perform layered compaction sample preparation, and a group of multiple parallel samples are compacted simultaneously; and demolding is carried out sequentially by adopting a static pressure demolding method. The invention can improve the uniformity of the texture of the sample and enhance the reliability and rationality of the test result.
Description
Technical Field
The invention relates to the technical field of geotechnical tests, in particular to a remolded soil batch sample preparation device and a sample preparation method.
Background
In hydraulic and geotechnical engineering practice, the relevant engineering problems mainly involve three aspects: namely strength problems, deformation problems and seepage problems. Correspondingly, the strength, deformation and seepage parameters of the soil also become the most basic and important technical indexes in engineering construction and design. The determination of the strength, deformation and seepage parameters of the soil mainly depends on soil engineering test technology, and the common soil engineering test technology mainly comprises indoor test and field in-situ test. Theoretically, the field in-situ test can truly reflect the structural property of field undisturbed soil and the influence of environmental factors, but the indoor test is still the preferred scheme of broad scholars and engineers based on the aspects of test conditions, test instruments, budget expenditure and the like.
In the case of indoor tests, sample preparation is a major factor affecting the reliability of test results. The common sample preparation scheme comprises an original soil sample preparation and a remolded soil sample preparation, but the original soil is influenced by stress history, sampling positions and other environmental factors, the discreteness of the sample is high, and the reliability of a test result is also reduced, so that the remolded soil sample preparation is widely applied to indoor test research.
At present, the common remolded soil sample preparation methods are mainly divided into two main types: one is consolidation method, the other is compaction method, which mainly comprises a layering compaction method and a two-end compaction method. However, these sample preparation methods all have the following disadvantages and need to be improved:
1. for the consolidation method, the method is commonly used for preparing samples with high water content, the sample preparation process is more complicated, the consolidation time is longer, and the requirement on sample preparation equipment is higher.
2. For the conventional layered compaction method, the phenomenon of over-smashing of the sample often occurs, and the sample must be prepared again at the moment, so that the efficiency is seriously reduced. For an improved layered compaction method, although the precise compaction of each layer of sample can be guaranteed, under the repeated action of compaction load, the structure and uniformity of the sample can be influenced to a certain extent, and the phenomenon that the lower layer of soil sample is more compact than the upper layer of soil sample often occurs.
3. For the two-end compaction method, on one hand, the compacted sample is generally loose in the middle and compact at two ends under the influence of the height-diameter ratio of the sample, and on the other hand, the rapid compaction process may cause the gas in the sample to be difficult to discharge, so that gas gaps are formed in the sample, and the quality of the sample is seriously reduced.
In addition, the current methods of sample release mainly include two types: one method is a direct manual knocking demoulding method based on a three-petal mould sample, the method can cause defects at two ends of the sample, and the sample needs to be prepared again when the defects are serious; the other type adopts an electric demoulding tester to demould, but the device has higher manufacturing cost, heavier weight and single function.
The existing research results show that: the results obtained from tests using samples prepared by different sampling methods have significant variability, which is mainly due to the uniformity of the texture of the samples.
Therefore, the device and the method for integrating sample preparation and demoulding, which have the advantages of high sample preparation precision, good sample preparation uniformity and complete functions, have obvious use value and practical significance.
Disclosure of Invention
The invention aims to solve the technical problem of the prior art and provides a remolded soil batch sample preparation device and a remolded soil batch sample preparation method, which can improve the uniformity of the texture of a sample and enhance the reliability and rationality of a test result.
In order to solve the technical problems, the invention adopts the technical scheme that:
a remolded soil batch sample preparation device comprises a counter-force frame module, a sample preparation module and a compaction module.
The reaction frame module comprises a reaction cover plate, a movable bearing plate, a bottom plate and a vertical strut. The upright support is used for connecting the counter-force cover plate and the bottom plate, and the movable bearing plate is positioned between the counter-force cover plate and the bottom plate and can be lifted and lowered.
The sample preparation module comprises a plurality of sets of sample preparation barrel assemblies arranged between the movable bearing plate and the counterforce cover plate. Each system appearance section of thick bamboo subassembly all includes the sleeve of odd number coaxial setting and mutual block. The sleeve in the central layer is called the central sleeve, and the remaining even number of sleeves are called the ring-stacked sleeves. Wherein, the top surface and the bottom surface of central sleeve all are provided with the block groove.
The height and the inner diameter of each sleeve are equal, and the cavity of each sleeve can be filled with remolded soil.
The compaction module comprises a jacking device and a compaction piston. The jacking device is arranged on the bottom plate and used for controlling the height of the movable bearing plate to rise and fall. And the compaction pistons are respectively arranged at the top and the bottom of each sample cylinder assembly.
Each compaction piston comprises a large pressure head, a small pressure head and a connecting rod which are coaxially arranged. The connecting rod is used for connecting big pressure head and little pressure head. The area of the small pressure head is smaller than the inner diameter of the sleeve, and the outer wall surface of the small pressure head can be in sliding fit with the inner wall surface of the sleeve. The area of the large pressure head is larger than the inner diameter of the sleeve. The end face of the small pressure head, which is far away from the connecting rod, can be in contact with remolded soil filled in the cavity of the sleeve. A plurality of exhaust holes are uniformly distributed on the end surface of the small pressure head.
Still include the drawing of patterns module, drawing of patterns module includes the drawing of patterns piston. And a demoulding piston placing hole is formed in the movable bearing plate which is positioned right above the jacking device and used for placing a demoulding piston. And a sample demoulding hole is formed in the counter-force cover plate which is positioned right above the demoulding piston placing hole. The compaction module also comprises a compaction gasket, the compaction gasket is detachably arranged at the top of the jacking device, and the outer diameter of the compaction gasket is larger than the inner diameter of the demoulding piston arranging hole. When the compaction gasket is detached from the top of the jacking device, the top of the jacking device can be detachably connected with the top of the demoulding piston.
The sum of the heights of the small pressure head and the connecting rod is equal to the height of the sleeve.
The jacking device is a hydraulic jack.
The upper surface of each ring-overlapping sleeve positioned above the central sleeve is provided with a clamping groove, and the lower surface of each ring-overlapping sleeve is provided with a connecting flange which can be matched with the clamping groove. The lower surface of each ring-overlapping sleeve below the central sleeve is provided with a clamping groove, and the upper surface of each ring-overlapping sleeve is provided with a connecting flange which can be matched with the clamping groove.
Each exhaust hole is a conical hole which vertically penetrates through, and the contraction end of the conical hole is positioned on the small pressure head on one side which is contacted with remolded soil.
A remolded soil batch sample preparation method comprises the following steps.
Step 1, preparing remolded soil: and breaking the air-dried clay, sieving the crushed clay by using a 2mm analysis sieve, and uniformly spraying distilled water on the sieved clay to form the clay with set water content. And filling the soil material with the set water content into a sealing bag to be sealed for more than 24 hours to form remolded soil.
Step 2, installing a remolded soil batch sample preparation device, comprising the following steps of:
step 21, assembling a reaction frame module: the counter-force cover plate, the movable bearing plate and the bottom plate are sequentially connected from top to bottom through the vertical support columns, and the movable bearing plate slides up and down along the vertical support columns.
Step 23, preparing a sample preparation module: assuming that N parallel remolded soil samples are required to be prepared in each batch, and the total height of each prepared remolded soil sample is the sum of the heights of 2N-1 sleeves, N sets of sample cylinder assemblies are required to be prepared, wherein each set of sample cylinder assembly comprises 2N +1 sleeves. Namely, N central sleeves and 2N × N ring-overlapped sleeves are prepared.
Step 3, preparing a center layer remolded soil sample, comprising the following steps:
Step 4, preparing a three-layer remolded soil sample, comprising the following steps:
And 42, repeating the steps 32 to 33 to finish the preparation of the three-layer remolded soil sample.
And 5, repeating the step 4 until the preparation of the 2 n-1-layer remolded soil sample is completed.
Comprising a step 6 of demoulding, wherein the process comprises the following steps:
step 61, remoulding the soil sample before demoulding: and (4) lowering the height of the jacking device, taking out the overlapped 2n +1 layers of sleeves, and removing the topmost and bottommost sleeves to form 2n-1 layers of sleeves.
Step 62, preparing a demolding module: and detaching the compaction gasket at the top of the jacking device, replacing and installing the demoulding piston, wherein the demoulding piston can extend out of and lift up and down from a demoulding piston installation hole arranged on the movable bearing plate.
Step 63, remolded soil sample transfer: one of the 2n-1 layered sleeves formed in step 61 is moved onto the stripper piston in step 62.
Step 64, synchronously lifting the 2n-1 layers of sleeves: the height of the jacking device rises to drive the demoulding piston, the 2n-1 layer of sleeves and the remolded soil sample in the 2n-1 layer of sleeves to rise synchronously.
Step 65, demolding: and when the top surface of the sleeve of the 2n-1 layer in the step 64 is contacted with the bottom surface of the counter force cover plate, stopping lifting the sleeve of the 2n-1 layer. And the height of the jacking device continues to rise, the top surface of the demoulding piston is in pressed contact with the bottom surface of the remolded soil sample in the 2n-1 layer of sleeve, and the outer wall surface of the demoulding piston is in sliding fit with the inner wall surface of the 2n-1 layer of sleeve, so that the remolded soil sample in the 2n-1 layer of sleeve slides out of the sample demoulding hole of the 2n-1 layer of sleeve and the counter-force cover plate until demoulding is successful.
And step 66, descending the height of the jacking device, and removing the 2n-1 layers of sleeves after demolding. And repeating the steps 63 to 65 to complete the demolding of the rest remolded soil samples.
And filter paper is paved on the surface of the small pressure head of the compaction piston, which faces the remolded soil.
The invention has the following beneficial effects:
1. the sample preparation method adopted by the invention is a two-end layered compaction method, the sample forming quality is good, the dry density and the water content of the prepared sample are relatively uniform, the discreteness of the initial state of the sample is reduced, and the reliability of the test result is enhanced.
2. According to the sample preparation cylinder, the assembled ring-stacked sleeves with the same specification are adopted, the compaction piston is used in the compaction process, and the compaction piston are matched for use, so that the compaction height of each layer of sample can be accurately controlled, and the uniformity of the sample is improved.
3. According to the sample preparation device and the sample preparation method provided by the invention, a group of (four) samples can be prepared simultaneously, the stress states of the samples are consistent, the difference among different samples is reduced, the test error caused by sample preparation is reduced, and the contrast of test results is improved.
4. The lower pressure head of the compaction piston is provided with the conical vent hole, and the size of the hole on one surface contacting with the sample is smaller, so that the soil particle loss in the compaction process can be prevented; the hole specification of the back is bigger, and the inside gas of the soil material is conveniently discharged in the compaction process.
5. The sample preparation device provided by the invention can respectively finish the compaction and the demoulding of the sample, has the advantages of simple sample preparation process, convenient operation and low device cost, and can ensure the sample preparation quality while meeting the sample preparation requirements of a common simple laboratory.
Drawings
Fig. 1 is a schematic structural diagram of a remolded soil batch sample preparation device according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of a movable bearing plate structure provided in an embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a collar sleeve provided according to an embodiment of the present invention.
FIG. 4 is a schematic illustration of a compaction piston configuration provided in accordance with an embodiment of the present invention.
FIG. 5 is a schematic view of a compacted shim construction provided in accordance with an embodiment of the invention.
Fig. 6 is a schematic diagram of a structure of a knockout piston provided in accordance with an embodiment of the present invention.
The figure shows that:
11. a ring-overlapping sleeve; 111. a connecting flange; 12. a central sleeve;
21. a counter-force cover plate; 22. a movable bearing plate; 221. compacting the piston accommodating groove; 222. sliding and perforating;
23. a base plate; 24. a vertical strut; 25. a limiting ring; 26. a bolt;
31. compacting the piston; 311. a small pressure head; 312. a large pressure head; 313. a connecting rod; 314. an exhaust hole;
32. a hydraulic jack; 33. compacting the gasket; 331. compacting a gasket connecting groove;
41. a stripper piston; 441. a demoulding piston connecting groove; 42. a demold piston seating hole; 43. and (4) stripping the sample from the die hole.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific preferred embodiments.
In the description of the present invention, it is to be understood that the terms "left side", "right side", "upper part", "lower part", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and that "first", "second", etc., do not represent an important degree of the component parts, and thus are not to be construed as limiting the present invention. The specific dimensions used in the present example are only for illustrating the technical solution and do not limit the scope of protection of the present invention.
As shown in figure 1, the remolded soil batch sample preparation device comprises a reaction frame module, a sample preparation module, a compaction module and a demolding module.
The reaction frame module comprises a reaction cover plate 21, a movable carrier plate 22, a bottom plate 23 and an upright post 24. The vertical support posts are used to connect the reaction cover plate and the base plate and are fastened by bolts 26.
The movable bearing plate is positioned between the counterforce cover plate and the bottom plate, is preferably sleeved on the upright post, and is lifted and lowered along the upright post. A stop ring 25 is preferably arranged on each upright below the sliding sleeve, in order to limit the height of the movable carrier plate.
As shown in fig. 2, N compacting piston placing grooves 221 are uniformly formed on the upper surface of the movable carrier plate 22 along a diagonal direction, where N is a positive integer, preferably equal to 4.
The middle position of the movable bearing plate is preferably provided with a demoulding piston arranging hole 42, and the central longitudinal section of the demoulding piston arranging hole is preferably T-shaped.
Preferably, a sliding sleeve is mounted at the connection between the movable carrier plate 22 and the upright post 24.
The sample preparation module comprises a plurality of sets of sample preparation cylinder assemblies arranged between the movable bearing plate and the counter-force cover plate, and the number of the sample preparation cylinder assemblies determines the number of remolded soil samples prepared in each batch, namely the number of parallel samples, and preferably four sets of the sample preparation cylinder assemblies.
Each system appearance section of thick bamboo subassembly all includes the sleeve of odd number coaxial setting and mutual block. The specific number of the sleeves is determined according to the layering number of the remolded soil samples to be manufactured, and after compaction manufacturing, the height of each layer of remolded soil samples is equal to the height of the sleeves.
The sleeve located in the central layer is referred to as the central sleeve 12 and the remaining even number of sleeves are referred to as the collar sleeves 11. Wherein, the top surface and the bottom surface of central sleeve all are provided with the block groove.
The upper surface of each of the stacked sleeves above the central sleeve is provided with a locking groove, and the lower surface is provided with a connecting flange 111 capable of matching with the locking groove, as shown in fig. 3. The lower surface of each ring-overlapping sleeve below the central sleeve is provided with a clamping groove, and the upper surface of each ring-overlapping sleeve is provided with a connecting flange which can be matched with the clamping groove.
The height and the inner diameter of each sleeve are equal, and the cavity of each sleeve can be filled with remolded soil.
The compaction module comprises a jacking device, a compaction pad 33 and a compaction piston 31.
The jacking means is preferably a hydraulic jack 32 mounted on the base plate for controlling the elevation of the movable carrying floor.
The compacted shim is constructed as shown in fig. 5 as a circular plate with a compacted shim attachment slot 331 in the center. Through compaction gasket spread groove 331, detachable installation is at the top of jacking device, and the external diameter of compaction gasket is greater than the internal diameter in drawing of patterns piston placement hole, preferably more than 1.2 times of drawing of patterns piston placement hole internal diameter.
Compaction pistons are arranged at the top and bottom of each sample cylinder assembly.
As shown in fig. 4, each compaction piston includes a small ram 311, a large ram 312, and a connecting rod 313, which are coaxially arranged. The connecting rod is used for connecting big pressure head and little pressure head.
The area of the large pressure head is larger than the inner diameter of the sleeve, and the compaction stroke is limited.
The area of the small pressure head is smaller than the inner diameter of the sleeve, preferably 1-2mm, and the outer wall surface of the small pressure head can be in sliding fit with the inner wall surface of the sleeve. The end face of the small pressure head, which is far away from the connecting rod, can be in contact with remolded soil filled in the cavity of the sleeve.
The small pressure head is preferably provided with a plurality of vent holes 314 uniformly distributed on the end surface. Each exhaust hole is preferably a conical hole which vertically penetrates, and the contraction end of the conical hole is positioned on the small pressure head on the side which is in contact with the remolded soil.
The small pressure head of the compaction piston is preferably paved with filter paper towards the surface of remolded soil, so that the exhaust hole can be prevented from being blocked.
The sum of the heights of the small pressure head and the connecting rod is equal to the height of the sleeve, so that the stroke of each compaction is kept consistent, and the compaction uniformity is high.
In the invention, when a plurality of ring-overlapping sleeves are adopted for layered sample preparation, the soil material required by each layer of sample is determined in advance through calculation. Since the sum of the length of the connecting rod 313 and the thickness of the small ram 311 is equal to the height of one of the sleeves 11, the diameter of the large ram 312 is slightly larger than the diameter of the sleeve 11. During sample compaction, when the large ram 312 contacts the top of the barrel 11, the compaction piston does not continue to move downward and, therefore, over-pressurization does not occur.
The stripper module includes a stripper piston 41. As shown in fig. 6, the center longitudinal section of the ejector piston 41 is preferably T-shaped, and is placed in the ejector piston seating hole 42. The centre of the bottom of the demoulding piston is provided with a demoulding piston connecting groove 411 which is used for being detachably connected with the top of the jacking device. When the compaction gasket is detached from the top of the jacking device, the top of the jacking device can be detachably connected with the top of the demoulding piston.
In fig. 6, the stripper piston is turned over with the bottom surface facing upward for ease of showing the stripper piston connecting grooves.
And a sample demoulding hole 43 is formed in the counter-force cover plate right above the demoulding piston placing hole, so that the remolded soil sample can conveniently slide out of the top of the counter-force cover plate.
A remolded soil batch sample preparation method comprises the following steps.
Step 1, preparing remolded soil: and breaking the air-dried clay, sieving the crushed clay by using a 2mm analysis sieve, and uniformly spraying distilled water on the sieved clay to form the clay with set water content. And filling the soil material with the set water content into a sealing bag to be sealed for more than 24 hours to form remolded soil.
And 2, installing a remolded soil batch sample preparation device, comprising the following steps.
Step 21, assembling a reaction frame module: the counter-force cover plate, the movable bearing plate and the bottom plate are sequentially connected from top to bottom through the vertical support columns, and the movable bearing plate slides up and down along the vertical support columns.
Alternatively, the upper compaction piston is not installed during this step, and it is within the scope of the present invention to place the upper compaction piston directly on the upper surface of the remolded soil after the remolded soil has been loaded during step 32.
Step 23, preparing a sample preparation module: assuming that N parallel remotened soil samples are to be prepared per batch, preferably N ═ 4, the total height of each remotened soil sample after preparation is the sum of 2N to 1 sleeve heights, i.e. each remotened soil sample after preparation has 2N to 1 layers. Wherein N and N are both positive integers.
Therefore, N sets of sample cylinder assemblies each including 2N +1 cartridges are prepared. Namely, N central sleeves and 2N × N ring-overlapped sleeves are prepared.
In this example, each sample cylinder assembly shown in fig. 1 has 5 sleeves, and each remolded soil sample after preparation has three layers.
And 3, preparing a center layer remolded soil sample, comprising the following steps.
Furthermore, filter paper is preferably laid between the remolded soil in the three-layer sleeve and the small pressure head in the compaction piston.
The sum of the heights of the small pressing heads and the connecting rod is preferably equal to the height of the sleeve, so that when the large pressing head in the upper compacting piston and the lower compacting piston is in close contact with the ring-overlapped sleeve, the stroke of each compacting can be kept consistent, and the compacting uniformity is high.
And 4, preparing a three-layer remolded soil sample, which comprises the following steps.
And 42, repeating the steps 32 to 33 to finish the preparation of the three-layer remolded soil sample.
In order to further improve the uniformity of sample preparation, the maximum load of each layer of sample in the compaction process is controlled respectively, and if the external force used in the compaction process of the sample in the central layer is P, the second layer and the third layer of samples next to the sample in the central layer are compacted by adopting the external force of 0.9P, and similarly, the fourth layer and the fifth layer of samples are compacted by adopting the external force of 0.8P.
And 5, repeating the step 4 until the preparation of the 2 n-1-layer remolded soil sample is completed.
And step 6, demolding, wherein the demolding process comprises the following steps:
step 61, remoulding the soil sample before demoulding: and (4) lowering the height of the jacking device, taking out the overlapped 2n +1 layers of sleeves, and removing the topmost and bottommost sleeves to form 2n-1 layers of sleeves.
Step 62, preparing a demolding module: and detaching the compaction gasket at the top of the jacking device, replacing and installing the demoulding piston, wherein the demoulding piston can extend out of and lift up and down from a demoulding piston installation hole arranged on the movable bearing plate.
Step 63, remolded soil sample transfer: one of the 2n-1 layered sleeves formed in step 61 is moved onto the stripper piston in step 62.
Step 64, synchronously lifting the 2n-1 layers of sleeves: the height of the jacking device rises to drive the demoulding piston, the 2n-1 layer of sleeves and the remolded soil sample in the 2n-1 layer of sleeves to rise synchronously.
Step 65, demolding: and when the top surface of the sleeve of the 2n-1 layer in the step 64 is contacted with the bottom surface of the counter force cover plate, stopping lifting the sleeve of the 2n-1 layer. And the height of the jacking device continues to rise, the top surface of the demolding piston is in pressed contact with the bottom surface of the remolded soil sample in the 2n-1 layer of sleeve, the outer wall surface of the demolding piston is in sliding fit with the inner wall surface of the 2n-1 layer of sleeve, so that the remolded soil sample in the 2n-1 layer of sleeve slides out of the sample demolding hole of the 2n-1 layer of sleeve and the counter-force cover plate until demolding is successful, and then a preservative film is used for wrapping and sealing the demolded remolded soil sample.
And step 66, descending the height of the jacking device, and removing the 2n-1 layers of sleeves after demolding. And repeating the steps 63 to 65 to complete the demolding of the rest remolded soil samples.
Through the setting of exhaust hole, further improve the whole degree of consistency of sample.
An empirical formula of the compaction speed and the size and number of the vent holes in the compaction process is as follows:
α＝(nA′)/A (2)
in the formula: v-compaction speed;
delta H is the height difference between the loose soil material and the compacted soil material in each layer of sleeve;
s-the gas overflow coefficient, which is the ratio of the actual gas volume discharged through the exhaust hole to the theoretical calculated volume, is generally 0.6-0.8
Alpha-equivalent area ratio, n is the number of exhaust holes, A' is the area of a single exhaust hole,
a is the area of a small pressure head in the compaction piston;
p is compaction pressure;
ρ -air density;
q-the total volume of gas in the sample in each layer of the sleeve, typically taken as the internal volume of one layer of the sleeve.
From the above formula, it can be seen that the compaction speed and the size and number of vents are all interdependent. Preferably, for three standard samples (with diameters of 39.1mm, 61.8mm and 101mm respectively) commonly used in laboratories, in order to prevent the loss of the soil from the vent hole during the compaction process, the diameter of the vent hole on the side of the compaction piston contacting the sample is preferably not more than 0.5mm, and in order to prevent part of fine particles from blocking the vent hole, a piece of filter paper is additionally arranged between the vent hole and the sample; secondly, considering the compaction speed and the exhaust speed of the sample, the compaction time of the sample on one layer is recommended to be not more than 1min, and the total area of the number of the exhaust holes formed in the surface of the compaction piston is recommended to be not less than 3% of the total area of the small pressure head in the compaction piston.
In the invention, the main purpose of the vent hole is to smoothly discharge the redundant gas in the soil material in the compaction process, reduce the initial pore damage caused by insufficient discharge of the gas and improve the uniformity of the sample from a microscopic view.
Although the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the details of the embodiments, and various equivalent modifications can be made within the technical spirit of the present invention, and the scope of the present invention is also within the scope of the present invention.
Claims (8)
1. The utility model provides a remolded soil system appearance device in batches which characterized in that: the device comprises a counterforce frame module, a sample preparation module and a compaction module;
the reaction frame module comprises a reaction cover plate, a movable bearing plate, a bottom plate and a vertical strut; the vertical strut is used for connecting the counter-force cover plate and the bottom plate, and the movable bearing plate is positioned between the counter-force cover plate and the bottom plate and can be lifted and lowered;
the sample preparation module comprises a plurality of sets of sample preparation barrel assemblies arranged between the movable bearing plate and the counter-force cover plate; each sample making cylinder assembly comprises an odd number of sleeves which are coaxially arranged and are mutually clamped; the sleeve positioned in the central layer is called a central sleeve, and the rest even number of sleeves are called ring-overlapped sleeves; the top surface and the bottom surface of the central sleeve are provided with clamping grooves;
the height and the inner diameter of each sleeve are equal, and a cavity of each sleeve can be filled with remolded soil;
the compaction module comprises a jacking device and a compaction piston; the jacking device is arranged on the bottom plate and used for controlling the height of the movable bearing plate to rise and fall; the top and the bottom of each sample making cylinder assembly are respectively provided with one compaction piston;
each compaction piston comprises a large pressure head, a small pressure head and a connecting rod which are coaxially arranged; the connecting rod is used for connecting the large pressure head and the small pressure head; the area of the small pressure head is smaller than the inner diameter of the sleeve, and the outer wall surface of the small pressure head can be in sliding fit with the inner wall surface of the sleeve; the area of the large pressure head is larger than the inner diameter of the sleeve; the end face of the small pressure head, which is far away from the connecting rod, can be contacted with remolded soil filled in the cavity of the sleeve; a plurality of exhaust holes are uniformly distributed on the end surface of the small pressure head;
the sum of the heights of the small pressure head and the connecting rod is equal to the height of the sleeve.
2. The remolded soil batch sample preparation device of claim 1, wherein: the demolding device also comprises a demolding module, wherein the demolding module comprises a demolding piston; a demoulding piston placing hole is formed in the movable bearing plate which is positioned right above the jacking device and used for placing a demoulding piston; a sample demoulding hole is arranged on the counter-force cover plate which is positioned right above the demoulding piston placing hole; the compaction module also comprises a compaction gasket, the compaction gasket is detachably arranged at the top of the jacking device, and the outer diameter of the compaction gasket is larger than the inner diameter of the demoulding piston arranging hole; when the compaction gasket is detached from the top of the jacking device, the top of the jacking device can be detachably connected with the top of the demoulding piston.
3. The remolded soil batch sample preparation device of claim 1, wherein: the jacking device is a hydraulic jack.
4. The remolded soil batch sample preparation device of claim 1, wherein: the upper surface of each ring-overlapping sleeve positioned above the central sleeve is provided with a clamping groove, and the lower surface of each ring-overlapping sleeve is provided with a connecting flange which can be matched with the clamping groove; the lower surface of each ring-overlapping sleeve below the central sleeve is provided with a clamping groove, and the upper surface of each ring-overlapping sleeve is provided with a connecting flange which can be matched with the clamping groove.
5. The remolded soil batch sample preparation device of claim 1, wherein: each exhaust hole is a conical hole which vertically penetrates through, and the contraction end of the conical hole is positioned on the small pressure head on one side which is contacted with remolded soil.
6. A remolded soil batch sample preparation method is characterized by comprising the following steps: the method comprises the following steps:
step 1, preparing remolded soil: breaking the air-dried clay, sieving the crushed clay by using a 2mm analysis sieve, and uniformly spraying distilled water on the sieved clay to form the clay with set water content; filling the soil material with the set water content into a sealing bag to be sealed for more than 24 hours to form remolded soil;
step 2, installing a remolded soil batch sample preparation device, comprising the following steps of:
step 21, assembling a reaction frame module: the counter-force cover plate, the movable bearing plate and the bottom plate are sequentially connected from top to bottom through the vertical strut, and the movable bearing plate slides up and down along the vertical strut;
step 22, assembling a compaction module: placing a jacking device on the bottom, and installing a compaction gasket on the top of the jacking device; the upper surface of the movable bearing plate and the lower surface of the counter-force cover plate are both provided with compaction pistons which are equal in number and correspond to the sample preparation sleeve assemblies in position; the compaction piston positioned on the movable bearing plate is called a lower compaction piston, and the compaction piston positioned on the counter force cover plate is called an upper compaction piston; small pressure heads of the compaction piston face the sample preparation sleeve assembly;
step 23, preparing a sample preparation module: assuming that N parallel remolded soil samples need to be prepared in each batch, and the total height of each prepared remolded soil sample is the sum of the heights of 2N-1 sleeves, N sets of sample cylinder assemblies need to be prepared, wherein each set of sample cylinder assembly comprises 2N +1 sleeves; namely, N central sleeves and 2N × N ring-overlapped sleeves are prepared;
step 3, preparing a center layer remolded soil sample, comprising the following steps:
step 31, mounting three layers of sleeves: adjusting the height position of the movable bearing plate, and respectively clamping and connecting an overlapping ring sleeve at the upper end and the lower end of each of the N central sleeves to form N three-layer sleeves; uniformly coating a layer of vaseline on the inner walls of the N three-layer sleeves and sequentially placing the vaseline on the corresponding lower compaction pistons assembled in the step 22;
step 32, remolding soil sample loading: weighing N parts of remolded soil prepared in the step 1, and respectively pouring the weighed remolded soil into the N three-layer sleeves in the step 31;
step 33, compacting: the movable bearing plate is driven by the jacking device to slowly rise, so that small pressure heads in the upper compaction pistons assembled in the step 22 enter the corresponding three layers of sleeves; then, the jacking device ascends at a constant speed until a large pressure head in the upper compaction piston and the lower compaction piston is in close contact with the ring-overlapped sleeve, so that the preparation of the remolded soil sample of the central layer is completed;
step 4, preparing a three-layer remolded soil sample, comprising the following steps:
step 41, installing five layers of sleeves: the height of the jacking device is reduced, the three-layer sleeves are taken out, the two ends of the compacted center-layer remolded soil sample are planed, and then, one ring-overlapped sleeve is respectively added to the two ends of each three-layer sleeve to form N five-layer sleeves; uniformly coating a layer of vaseline on the inner walls of the N five-layer sleeves and sequentially placing the five-layer sleeves on corresponding lower compaction pistons assembled in the step 22;
step 42, repeating the step 32 to the step 33 to finish the preparation of the three-layer remolded soil sample;
and 5, referring to the step 4, finishing the preparation of the 2 n-1-layer remolded soil sample.
7. The remolded soil batch sampling method according to claim 6, characterized in that: comprising a step 6 of demoulding, wherein the process comprises the following steps:
step 61, remoulding the soil sample before demoulding: the height of the jacking device is lowered, 2n +1 layers of sleeves formed by superposition are taken out, the topmost layer sleeves and the bottommost layer sleeves are removed, and 2n-1 layers of sleeves are formed;
step 62, preparing a demolding module: detaching the compaction gasket at the top of the jacking device, replacing and installing a demoulding piston, wherein the demoulding piston can extend out of a demoulding piston installation hole formed in the movable bearing plate and lift;
step 63, remolded soil sample transfer: moving one of the 2n-1 layer sleeves formed in the step 61 to a demoulding piston in the step 62;
step 64, synchronously lifting the 2n-1 layers of sleeves: the height of the jacking device rises to drive the demoulding piston, the 2n-1 layer of sleeves and the remolded soil sample in the 2n-1 layer of sleeves to rise synchronously;
step 65, demolding: when the top surface of the sleeve of the 2n-1 layer in the step 64 is contacted with the bottom surface of the counter-force cover plate, the height of the sleeve of the 2n-1 layer stops lifting; the height of the jacking device continues to rise, the top surface of the demoulding piston is in pressed contact with the bottom surface of the remolded soil sample in the 2n-1 layer of sleeve, and the outer wall surface is in sliding fit with the inner wall surface of the 2n-1 layer of sleeve, so that the remolded soil sample in the 2n-1 layer of sleeve slides out of the sample demoulding hole of the 2n-1 layer of sleeve and the counter-force cover plate until demoulding is successful;
step 66, descending the height of the jacking device, and removing the 2n-1 layers of sleeves after demolding; and repeating the steps 63 to 65 to complete the demolding of the rest remolded soil samples.
8. The remolded soil batch sampling method according to claim 6, characterized in that: and filter paper is paved on the surface of the small pressure head of the compaction piston, which faces the remolded soil.
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| CN112129640A (en) * | 2020-09-24 | 2020-12-25 | 江苏华安科研仪器有限公司 | Novel bearing device of reservoir inversion model |
| CN112485078B (en) * | 2020-10-30 | 2023-04-07 | 同创工程设计有限公司 | Forming method of unconfined compressive strength sample of reclaimed water stabilized macadam |
| CN112649262A (en) * | 2020-12-07 | 2021-04-13 | 江苏科技大学 | Sample preparation and demolding device and sample preparation method for multiple groups of rock and soil samples |
| CN112985934B (en) * | 2021-01-28 | 2024-07-05 | 浙江工业大学 | Soil remolded sample preparation device and sample preparation method thereof |
| CN114277758B (en) * | 2021-11-16 | 2023-08-11 | 西安建筑科技大学 | Sample pressing device for foundation stabilization |
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| CN104006992B (en) * | 2014-05-22 | 2016-06-15 | 西南交通大学 | Symmetrical layering pressure-like device and method for making sample prepared by a kind of triaxial test sample |
| CN104713756B (en) * | 2015-01-30 | 2017-09-12 | 浙江大学 | A kind of Unconfined Compression Strength of Soil tests the producing device of earth pillar model |
| CN104634636B (en) * | 2015-02-16 | 2017-05-03 | 河海大学 | Remolded soil layered sample impacting device and sample preparation method thereof |
| CN205317545U (en) * | 2015-12-16 | 2016-06-15 | 华中农业大学 | Batch production remolded sample's device |
| CN205941118U (en) * | 2016-07-07 | 2017-02-08 | 河海大学 | A kind device is hit in remolded soil layering |
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