CN109916688B - Lever type sample making machine for triaxial compression test of disturbing soil and sample making method thereof - Google Patents
Lever type sample making machine for triaxial compression test of disturbing soil and sample making method thereof Download PDFInfo
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- CN109916688B CN109916688B CN201910318625.5A CN201910318625A CN109916688B CN 109916688 B CN109916688 B CN 109916688B CN 201910318625 A CN201910318625 A CN 201910318625A CN 109916688 B CN109916688 B CN 109916688B
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- 239000002689 soil Substances 0.000 title claims abstract description 106
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000012669 compression test Methods 0.000 title claims abstract description 14
- 238000002360 preparation method Methods 0.000 claims abstract description 77
- 238000000465 moulding Methods 0.000 claims abstract description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 24
- 229910000831 Steel Inorganic materials 0.000 claims description 9
- 239000010959 steel Substances 0.000 claims description 9
- 230000000670 limiting effect Effects 0.000 claims description 8
- 238000011068 loading method Methods 0.000 claims description 8
- 230000001681 protective effect Effects 0.000 claims description 7
- 238000005070 sampling Methods 0.000 claims description 6
- 238000009434 installation Methods 0.000 claims description 5
- 238000003756 stirring Methods 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 3
- 230000002441 reversible effect Effects 0.000 claims description 3
- 238000005464 sample preparation method Methods 0.000 claims description 3
- 238000002791 soaking Methods 0.000 claims description 3
- 238000005507 spraying Methods 0.000 claims description 3
- 238000003892 spreading Methods 0.000 claims description 3
- 230000007480 spreading Effects 0.000 claims description 3
- 238000005303 weighing Methods 0.000 claims description 3
- 238000007873 sieving Methods 0.000 claims description 2
- 230000033001 locomotion Effects 0.000 abstract description 7
- 238000003825 pressing Methods 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 238000005056 compaction Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000001629 suppression Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 210000003298 dental enamel Anatomy 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Abstract
The invention discloses a lever type sample making machine for a triaxial compression test of disturbing soil and a sample making method thereof. The lifting plate is connected with a push rod of the lever assembly, and the stressing arm of the lever assembly rotates to realize lifting of the punch, so that the punch compacts each layer of soil sample in the sample preparation die to a set thickness, and the stressing arm is only required to be pressed downwards manually during operation. The device can press a plurality of samples at one time, the stamping depth of the punch is controlled to limit the different heights of the stressing arms through the locating frame, and the limit of the different heights of the locating frame can be calculated and determined by combining the size of the stressing arms and the movement track during sample preparation. The lifting plate moves with the upright rod guide. The method has the advantages of being capable of accurately controlling the thickness and the flatness of layered pressed samples, high in sample preparation efficiency and simple in molding and demolding operation.
Description
Technical Field
The invention relates to sample preparation equipment for triaxial compression tests, in particular to a lever type sample preparation machine for disturbing the triaxial compression tests and a sample preparation method thereof.
Background
The triaxial compression test is a test method for measuring the shear strength of soil, and usually 3-4 soil samples are used, and axial pressure is applied under different confining pressures respectively, so that shearing is performed until the soil is destroyed. The triaxial compression test has the outstanding advantages of being capable of strictly controlling drainage conditions and measuring pore water pressure change in a sample, and the stress state in the sample is clear.
According to the standard requirements, during triaxial compression test, a compaction method is generally adopted for preparing a disturbing soil sample, and the sample preparation steps and requirements are as follows:
the soil sample meeting the requirements of dry density and water content is compacted in a compaction cylinder by a plurality of layers (3-5 layers of silt and 5-8 layers of cohesive soil), the quality of each layer of soil sample is equal, and the contact surface of each layer should be shaved. Compacting the last layer, leveling two ends of the sample in the compacting cylinder, taking out the sample, weighing the sample, and ensuring that the density difference of the same group of samples is not more than 0.02g/cm 3 。
When the compaction method is used for preparing samples, the following defects and shortcomings exist:
1. only one sample can be manufactured at a time, the sample manufacturing steps are complicated, the sample manufacturing efficiency is low, and the physical consumption of sample manufacturing staff is high;
2. each layer of soil sample is likely to be stressed unevenly, so that the height, flatness and density of the sample are not easy to control accurately, and the standard requirements are difficult to meet;
3. during sample preparation, harsh hammering sounds are generated, and generated vibration is large, so that serious noise pollution is caused.
4. The shaving equipment is a single shaving needle, the shaving Mao Haoshi is longer, and the efficiency is low.
In view of the shortcomings of the compaction method, some researchers have improved triaxial compression test sample preparation methods and devices that disturb the earth, examples of which are as follows:
CN 107607385A discloses a vacuum test device for triaxial remolded soil sample preparation, which adopts vacuum suction to solidify soft clay to achieve the purpose of preparing uniform soil samples, but the process is complex, the equipment is complex, and the thickness of layered pressed samples cannot be accurately controlled.
CN 202814770U discloses a remolded soil sample preparation device for triaxial shear test, which adopts a sedimentation method to consolidate a soil sample, and can obtain a remolded sample with uniform water content, but the process of static loading the consolidated soil sample is slow, and the sample preparation efficiency is low.
CN 204008243U discloses a remolded soil triaxial compression test sample preparation device, which extrudes a sample through a pressing plate, and can discharge gas in the sample preparation chamber at the same time, and after the extrusion process is completed, the transverse plate is removed, and the upper pressing plate is taken out to obtain a sample. However, after the sample is pressed, the sample preparation device needs to be dismantled to take out the sample, the process is complicated and the efficiency is low.
Disclosure of Invention
The invention aims to provide a lever type sample making machine and a sample making method thereof, which can accurately control the thickness of layered pressed samples, have high sample making efficiency and are simple in mould making and demoulding operation.
The invention provides a lever type sample making machine for a sample for a disturbing soil triaxial compression test, which comprises a bottom plate, a linear guide rail, a mould supporting plate, a sample making mould, a vertical rod, a lifting plate, a punch, a positioning frame and a lever assembly, wherein the bottom plate is provided with a plurality of guide rails; the guide rail of the linear guide rail is fixed on the bottom plate, the die supporting plate is fixed on the slide block of the linear guide rail, the sample preparation die is fixed on the die supporting plate, the vertical rods are symmetrically arranged on the two sides of the bottom plate corresponding to the linear guide rail, the punch is connected to the lower side of the lifting plate, the lifting plate is slidably sleeved on the vertical rods, the number and the positions of the punch and the sample preparation die are corresponding, and the positioning frame is vertically connected between the vertical rods on the same side of the bottom plate; the lever assembly comprises a support, a force adding arm and a push rod, wherein the support is horizontally arranged above the lifting plate and corresponds to the opposite side of the positioning frame, the support is supported on the bottom plate through a vertical support piece, the lower end of the force adding arm is hinged to the support, the rotation angle of the force adding arm is limited by the positioning frame, the upper end of the push rod is slidably connected to the force adding arm, and the lower end of the push rod is connected to the lifting plate; the upper end of the force adding arm extends out of the positioning frame.
In one embodiment of the above technical solution, the linear guide rail is an SBR linear guide rail, two sliding blocks are configured on the guide rail, and a vertical magnetic limit rod is connected to the outer side of the shoe of the guide rail corresponding to one of the sliding blocks.
In one embodiment of the above technical solution, the bottom plate and the mold support plate are rectangular steel plates, the planar dimension of the mold support plate is smaller than that of the bottom plate, the mold support plate is fixed on the slide block, and the mold support plate and the bottom plate share a central plane in the width direction.
In one embodiment of the above technical solution, the sample preparation mold includes a cylindrical barrel, a hoop and a protective barrel, wherein the outer walls of two ends of the cylindrical barrel are provided with inward taper, the cylindrical barrel is formed by splicing multi-petal arc-shaped steel plates, the hoop is sleeved outside the cylindrical barrel to shape the cylindrical barrel, and the protective sleeve is sleeved at the upper end of the cylindrical barrel; the upper side of the mould supporting plate is provided with a circular ring, and the lower end of the cylinder is inserted into the circular ring.
In one embodiment of the above technical solution, the lifting plate is a rectangular plate, the punch comprises a pull rod and a pressure plate at the lower end of the pull rod, the upper end of the pull rod is welded at the lower side of the lifting plate, linear bearings are fixed at four corners of the lifting plate, two ends of each linear bearing extend out of the lifting plate, and the lifting plate is sleeved on the upright rod through the linear bearings.
In one embodiment of the above technical solution, the positioning frame is a vertical rectangular frame, a pair of positioning holes along the horizontal direction are formed at the top of the positioning frame in the height direction, clamping pins are matched in the positioning holes, a plurality of positioning holes along the horizontal direction are uniformly distributed at the upper part of the positioning frame, and positioning pins are matched in the positioning holes.
In one embodiment of the above technical solution, the support includes a T-shaped plate and a vertical ear plate connected to a web plate thereof, the top of the vertical ear plate has a hinge hole, and the web plate has a circular hole corresponding to the outer side of the vertical ear plate; the vertical support piece is a support plate, the upper end of the vertical support piece is connected to the middle position of the outer edge of the T-shaped plate wing plate, and the lower end of the vertical support piece is connected to the upper side of the bottom plate; the lower end of the stress application arm is hinged to the top of the vertical lug plate through a pin shaft, and the upper end of the push rod is slidably connected to the stress application arm.
In one embodiment of the above technical solution, the push rod is a cylindrical rod, the upper end of the push rod is spherical, and two planes symmetrical to the axial center plane of the push rod are machined on the outer wall of the upper section; the middle part of afterburning arm has push rod mounting groove, the bottom has vertical otic placode mounting groove, and the both ends of push rod mounting groove are spherical, and the interlude shape matches with the combined shape of push rod end and upper portion section, and the shape of vertical otic placode mounting groove matches with the rotation orbit of rectangle articulated section, and the push rod inserts the installation back from the upper end of push rod mounting groove, its lower extreme pass behind the round hole in the T template web outside connect in the upside of lifter plate.
In one embodiment of the foregoing technical disclosure, the stress application arm includes a hinge section and a stress application section, the push rod mounting groove is located in the middle of the hinge section, and the stress application section is screwed on the upper end of the hinge section.
The invention also provides a method for preparing the disturbed soil sample, which comprises three steps of preparing the soil sample, molding and demolding, wherein the molding and demolding adopts the sample preparation machine, and the method comprises the following steps:
1. soil sample preparation
(1) After the agglomerate and block-shaped disturbance soil sample is air-dried, the agglomerate and block-shaped disturbance soil sample is rolled and dispersed on a rubber plate on the premise of not damaging the natural structure of soil particles;
(2) Sieving the ground soil sample according to the required soil sample amount, fully and uniformly stirring the soil sample below the sieve, and taking out the soil sample for test by a four-division diagonal sampling method to obtain a disturbance scattered soil sample for preparing a sample;
(3) Preparing a sample with a certain water content, taking 1-2 kg of sieved air-dried soil, spreading the sample in a non-water-absorbing tray, spraying the required water adding amount by a sprayer, fully and uniformly stirring, and then placing the sample into a moisture-retaining device for soaking for a day and night, wherein the required water adding amount is calculated according to the following formula:
wherein: m is m w The amount of water (g) required for the test sample,
w 1 the required moisture content (%) of the sample,
m 0 the mass (g) of the air-dried soil,
w 0 -moisture content (%) of air-dried soil;
(4) Measuring the water content of the infiltrated sample, wherein the difference value between the qualified soil sample and the required water content is not more than +/-1%; (5) Weighing a plurality of parts of qualified soil samples by equal mass for preparing samples, wherein the mass of each part is the mass of each layer of soil sample during sample preparation, and the mass of each layer of soil sample is calculated according to the following formula:
wherein: m is m e The mass (g) of each layer of soil sample,
ρ d dry Density of samples (g/cm) 3 )，
V-sample volume (cm) 3 )，
n-the number of layers of the layered sample preparation;
2. sample preparation
(1) The boosting arm of the lever assembly is positioned at the maximum upward angle through the highest limit position of the positioning frame, so that the lifting plate is positioned at the highest position;
(2) Drawing out the sliding block, the mould supporting plate and the sample preparation mould along the guide rail, loading a first layer of soil sample into a cylindrical barrel of the sample preparation mould, and then integrally loading the first layer of soil sample back onto the guide rail until the sample preparation mould corresponds to the position of the punch;
(3) After the limit of the force adding arm is released, applying downward force to the upper end section of the force adding arm, enabling the force adding arm to rotate downwards around the hinged position of the lower end of the force adding arm, enabling the push rod to move downwards together with the lifting plate and the punch head on the push rod until the upper end section of the force adding arm moves to the lowest limit position of the positioning frame, and compacting the first layer of soil sample to the set thickness;
(5) Applying a reverse force to the force applying arm until the force applying arm returns to the state of the step (1);
(6) Digging the surface of the compacted soil sample in the sample preparation mould;
(7) Compacting each subsequent layer of soil sample by referring to the steps, but sleeving a protective cylinder on the top of the cylindrical cylinder when loading the last layer of soil sample into a sample preparation mould, wherein the surface after compaction is not subjected to shaving treatment;
3. demolding
(1) Drawing out the slide block, the mould supporting plate and the sample preparation mould along the guide rail, and taking the sample preparation mould off the mould supporting plate;
(2) And (5) detaching the sample preparation die.
The sample preparation die is fixed on the die supporting plate, and the die supporting plate is fixed on the sliding block of the linear guide rail, so that the sliding block, the die supporting plate and the sample preparation die can be quickly and integrally taken down and put back from the guide rail for a plurality of times, and each layered soil sample is conveniently and separately put into the sample preparation die. The lifter plate is connected with the push rod of lever assembly, realizes the lift of lifter plate and the drift of connection through the push rod when lever assembly adds the arm of force rotatory to make the drift compact each layer soil sample in the system appearance mould to setting for thickness, during the system appearance operation, only need the manual work with the afterburning arm push down can, easy operation. Because a plurality of sample preparation moulds can be fixed on the mould backup pad simultaneously, the suppression of a plurality of samples is realized simultaneously to the lift of accessible lifter plate, improves the suppression efficiency. The depth of each pressing of the punch can be controlled by limiting the different heights of the stressing arms through the locating frame, and the limiting of the different heights of the locating frame can be accurately calculated and determined by combining the size of the stressing arms and the movement track during sample preparation, so that the thickness of layered pressed samples can be accurately controlled. The lifting plate is guided by the vertical rod during lifting movement, so that the flatness of the pressed sample can be ensured. And when demoulding is carried out after the moulding is finished, the sliding block, the mould supporting plate and the sample preparation mould are integrally detached from the guide rail, and then the sample preparation mould is detached. Therefore, the invention has the advantages of accurate control of the layering pressed sample thickness, high sample preparation efficiency and simple molding and demolding operation.
Drawings
Fig. 1 is a schematic structural view of an embodiment of the present invention.
Fig. 2 is a schematic structural view of the lifter plate assembly of fig. 1.
Fig. 3 is a schematic view of the lever assembly support of fig. 1.
Fig. 4 is a schematic view of the lever assembly of fig. 1 with a biasing arm and push rod assembled.
Fig. 5 is a schematic diagram of the sample preparation mold of fig. 1 (the casing is not shown).
FIG. 6 is a schematic view of a shaver used in sample preparation.
FIG. 7 is a schematic diagram of a funnel structure used when adding a soil sample to a sample mold.
Detailed Description
As shown in fig. 1, the lever-type sampler for triaxial compression test of disturbing soil disclosed in this embodiment includes a base plate 1, a vertical rod 2, a linear guide rail 3, a die fixing plate 4, a positioning frame 5, a lever assembly 6, a lifting plate assembly 7, and a sample preparation die 8.
The bottom plate 1 is a rectangular plate, and the linear guide rail 3 has two groups, and is symmetrically fixed on two sides of the central surface of the bottom plate 1 in the width direction. In this embodiment, an SBR linear guide rail is adopted, two sliding blocks are disposed on the guide rail, and a magnetic limiting rod 31 along the vertical direction is fixed on the bottom support of the guide rail corresponding to the outer end of one of the sliding blocks. In fig. 1, the magnetic limiting rod is positioned at the outer end of the rear-end sliding block.
Four corners of the bottom plate are fixed on the flat ground through foundation bolts.
The die fixing plate 4 is a rectangular plate, the plane size of the die fixing plate is smaller than that of the bottom plate 1, and the die fixing plate is fixed on the sliding block through a fastening bolt and then shares a central plane in the width direction with the bottom plate 1. The upper side of mould backup pad is provided with 4 rings.
The four upright posts 2 are symmetrically fixed on two sides of the linear guide rail 3 on the bottom plate 1, the right upright post is used for installing a support of the lever assembly 6, and the upper end of the right upright post is provided with a thread section.
The locating rack 5 is a vertical rectangular rack, and a pair of locating holes along the horizontal direction are arranged at the top of the height direction, and clamping bolts are matched in the locating holes. The upper part of the locating rack is uniformly distributed with a plurality of pairs of locating holes along the horizontal direction, and locating bolts are matched in the locating holes. The lower end of the locating frame 5 is connected with the middle position between the same side vertical rods 2 on the bottom plate.
As can be seen in connection with fig. 1 and 2, the lifter plate assembly 7 includes a lifter plate 71 and a punch 72 connected to the lower side thereof, the lifter plate is a rectangular plate, the punch includes a pull rod and a platen at the lower end thereof, and the upper end of the pull rod is welded to the lower side of the lifter plate. The number and arrangement positions of the punches correspond to the rings on the die supporting plate. Linear bearings (not shown in the figure) are arranged at four corners of the lifting plate, two ends of each linear bearing extend out of the lifting plate and are sleeved on four upright rods 2 through the linear bearings, and the upright rods can guide up-and-down movement of the lifting plate and guarantee stable movement of the lifting plate. The arrangement of the linear bearing further improves the guiding function, so that the flatness of the pressed sample is better ensured.
When the installation position of the magnetic limiting rod on the guide rail collet is pushed in place by the sliding block, the position of the sample preparation die corresponds to the position of the punch.
As shown in fig. 1, the lever assembly 6 includes a support, a support plate, a force applying arm, and a push rod.
And calculating the position distribution of each positioning hole on the positioning frame by combining the geometric dimension of the force adding arm and the motion track of the force adding arm during sample preparation.
As shown in fig. 3, the support comprises a T-shaped plate 61 and a vertical lug plate 62, the vertical lug plate is connected to a web plate of the T-shaped plate, the top of the vertical lug plate is provided with a hinge hole, the upper end of a support plate 63 is connected to the middle position of the outer edge of a wing plate of the T-shaped plate, and two ends of the T-shaped plate are provided with round holes corresponding to the upright rods 2. As shown in fig. 1, when the support is installed, two ends of the T-shaped plate 61 pass through the right upright rod 2, the lower end of the supporting plate 63 is fixed on the upper side of the bottom plate 1 to vertically position the support, and the right upright rod passes through the T-shaped plate and then is connected with the horizontal limit of the lock nut T-shaped plate.
As shown in fig. 4, the push rod 64 is a cylindrical rod, the upper end of which is spherical, and the outer wall of the upper section is machined with two planes symmetrical about the axial center plane of the push rod.
As can be seen in fig. 1 and 4, the force arm includes a rectangular hinge section 65 and a cylindrical section 66 connected to the upper end thereof, the lower end of the rectangular hinge section 65 is hinged to the top of the vertical ear plate 62 by a pin, and the upper end of the push rod 64 is slidably connected to the rectangular hinge section 65.
The middle part of the rectangular articulated section is provided with a push rod mounting groove, the top is provided with a cylindrical section mounting hole, and the bottom is provided with a vertical lug plate mounting groove. The cylindrical section mounting hole is a threaded hole, and the lower end of the cylindrical section is in threaded connection with the mounting hole. The shape of the lug plate mounting groove is matched with the rotation track of the hinge section, and the top of the vertical lug plate is inserted into the lug plate mounting groove and then hinged through a pin shaft. The two ends of the push rod installation groove are spherical, the shape of the middle section is matched with the combined shape of the push rod end head and the upper section, so that the middle section has a guiding function, when the push rod 64 is inserted and installed from the upper end of the push rod installation groove, the lower end of the push rod 64 passes through a round hole in the outer side of the T-shaped plate web and then is connected to the upper side of the lifting plate 71, and power transmission is realized through the push rod. When the force adding arm rotates, the upper end of the push rod slides in the push rod mounting groove, and the lower end enables the lifting plate to realize lifting movement.
The rectangle articulated segment of this embodiment adopts the structure that two strip shaped plates were assembled, sets up half of each mounting hole respectively in the length direction one side of two strip shaped blocks, and two strip shaped blocks are connected the back with support, cylinder section and push rod and are fastened two strip shaped plates into whole through the fastener.
As shown in fig. 1, in the initial state after the lever assembly 6 is installed, the cylindrical section of the stressing arm is supported by the clamping bolt at the top of the positioning frame 5, the lifting plate 71 is pulled to be at the highest position by the push rod 64, and the punch 72 connected with the lifting plate is located above the sample preparation die 8.
As can be seen from fig. 1 and 5, the sample preparation mold 8 includes a cylindrical barrel 81, a hoop 82 and a protective barrel (not shown in the drawings), wherein the outer walls of the two ends of the cylindrical barrel are provided with inward taper, the cylindrical barrel is formed by splicing multi-petal arc-shaped steel plates, the hoop is sleeved outside the cylindrical barrel to shape the cylindrical barrel, and the jacket is sleeved at the upper end of the cylindrical barrel. The upper side of the mold supporting plate 4 is provided with a circular ring into which the lower end of the cylinder is inserted. The protective cylinder is only used when the uppermost layer of soil sample is filled into the cylindrical cylinder, so that the soil sample is prevented from being scattered.
After the sample preparation machine is assembled, the samples can be prepared, and as shown in fig. 1, four samples can be prepared at a time in the embodiment. The soil sample is prepared before the sample preparation of the sample preparation machine, and the soil sample preparation is specifically as follows:
(1) After the lump or block-shaped disturbance soil sample is air-dried, the soil sample is rolled and scattered on a rubber plate by using wood (the natural structure of soil particles cannot be damaged).
(2) According to the required soil sample amount of the test, the ground soil sample is sieved by a 2mm sieve, and after the sieved soil sample is fully and uniformly mixed, the soil sample for the test is taken out by a four-division diagonal sampling method, so that the disturbance scattered soil sample for preparing the test sample is prepared.
(3) Preparing a sample with a certain water content, and taking 1-2 kg of air-dried soil passing through a 2mm sieve. Spreading the sample in enamel plate, spraying water with sprayer, stirring, and soaking in moisture keeping device for one day and night. The required water addition amount is calculated according to the following formula:
wherein: m is m w -the amount of water (g) required for the test sample;
w 1 -the required moisture (%) of the sample;
m 0 -quality of air-dried soil (g);
w 0 -moisture content (%) of air-dried soil.
(4) The water content of the sample after infiltration is measured, the difference between the water content and the required water content is not more than +/-1%, and if the water content is more than +/-1%, the water adding amount in the sample is properly reduced or increased.
(5) Since layered sample preparation is required and the thickness and the mass of each layer are required to be the same, a plurality of parts of soil samples are weighed for sample preparation, and the mass of each part is the mass of each layer of soil sample during sample preparation. The mass of each layer of soil sample is calculated according to the following formula:
wherein: m is m e -the mass (g) of each layer of soil sample;
ρ d dry Density of samples (g/cm) 3 )；
V-sample volume (cm) 3 )；
n-the number of layers for layered sample preparation.
The following is a specific procedure for sample preparation by the present sample making machine:
1. sample preparation
(1) The cylindrical section of the lever assembly force adding arm is supported on a clamping bolt at the top of the positioning frame, so that the lifting plate is positioned at the highest position, and the punch connected with the lifting plate is positioned at the highest position;
(2) Inserting a positioning bolt into a positioning hole at the lowest part of a positioning hole group at the upper part of the positioning frame;
(3) The slide block, the mould supporting plate and the sample preparation mould are integrally pulled out along the guide rail, a first layer of soil sample is filled into the cylindrical barrel of the sample preparation mould through the funnel 9 shown in fig. 6, then the first layer of soil sample is filled back onto the guide rail, and the mould supporting plate is pushed to the magnetic limiting rod, so that the magnetic limiting rod attracts the mould supporting plate, the positioning of the mould supporting plate in the pressing process is ensured, and accidental displacement is avoided.
As shown in fig. 6, the mouth of the funnel 9 is in a straight cylindrical shape and is matched with the mould cylinder in size so as to prevent soil samples from being scattered during soil loading.
(4) Pulling out a clamping bolt at the top of the positioning frame, applying force to the cylindrical section of the force adding arm, enabling the force adding arm to rotate downwards around the hinged part of the lower end of the force adding arm, enabling the lower end of the push rod to push the lifting plate and the punch on the lifting plate to move downwards together until the cylindrical section is blocked by the positioning bolt, and compacting the first layer of soil sample to a set thickness;
(5) Applying a reverse force to the cylindrical section to enable the stressing arm to reversely rotate until the cylindrical section returns to the highest position, and reinserting a clamping bolt at the top of the positioning frame to support the cylindrical section, so that the punch returns;
(6) The compacted soil sample surface in the sample mold is shaved by the shaving Mao Gangzhen of the shaver 10 shown in fig. 7; as shown in fig. 7, the shaver 10 is composed of a long handle, a steel needle fixing thin rod and three shavers Mao Gangzhen, wherein the lower end of the long handle is fixedly connected to the middle position of the steel needle fixing thin rod, and the upper ends of the three shaving steel needles are equidistantly inserted into the steel needle fixing thin rod.
(7) Pulling out the locating pin in the step (2) and inserting the locating pin into the last locating hole, repeating the steps (3) to (6), and repeating the steps, compacting each subsequent layer of soil sample, wherein a pile casing is sleeved on the top of the cylindrical barrel when the last layer of soil sample is filled into the sample preparation mould, and the surface of the compacted soil sample is not subjected to shaving treatment;
the first batch of samples are molded, and the stress application arm returns to the initial state to wait for the samples to be demolded and then to carry out the next batch of sample preparation operation;
2. demolding
And (3) drawing out the sliding block, the mould supporting plate and the sample preparation mould along the guide rail, taking down the sample preparation mould from the circular ring on the mould supporting plate, taking down the hoop of the outer wall of the cylinder barrel, stripping each petal arc plate of the cylinder barrel from the outer wall of the cylindrical soil sample, and completing demoulding.
The lever assembly is used as an actuating mechanism for pressing and preparing samples, the molding of a plurality of samples can be completed in one batch only by manually applying force to the lever assembly, and the linear guide rail is used as a mold supporting plate and a mounting rail of a sample preparation mold fixed on the mold supporting plate, so that the layered soil loading and sample pressing processes are more convenient and faster. The accurate control of drift suppression degree of depth is realized to the control of afterburning arm rotation angle through the locating rack, makes the stable promotion lifter plate of push rod through the rotation of afterburning arm to make each drift homoenergetic steadily suppress the soil sample in each system appearance mould, guarantee the same height, roughness and the dry density of shaping sample, thereby can guarantee that the sample obtains accurate test data through triaxial compression test, better satisfy teaching experiment and scientific research to the requirement of experimental effect.
Claims (4)
1. A sample preparation method of a sample for a disturbing soil triaxial compression test comprises three steps of soil sample preparation, molding and demolding, and is characterized in that:
the molding and demolding adopts a lever type sampling machine, and the lever type sampling machine comprises a bottom plate, a linear guide rail, a mold supporting plate, a sampling mold, a vertical rod, a lifting plate, a punch, a positioning frame and a lever assembly;
the guide rail of the linear guide rail is fixed on the bottom plate, and the die supporting plate is fixed on the slide block of the linear guide rail;
the sample preparation die comprises a cylindrical barrel, a hoop and a protective barrel, wherein the outer walls of the two ends of the cylindrical barrel are provided with inward taper, the cylindrical barrel is formed by splicing multi-petal arc-shaped steel plates, the hoop is sleeved outside the cylindrical barrel to shape the cylindrical barrel, and the protective barrel is sleeved at the upper end of the cylindrical barrel; the upper side of the die supporting plate is provided with a circular ring, and the lower end of the cylinder is inserted into the circular ring;
the vertical rods are symmetrically arranged on two sides of the bottom plate corresponding to the linear guide rail, the punch is connected to the lower side of the lifting plate, the lifting plate is slidably sleeved on the vertical rods, the number and the positions of the punch and the sample preparation die are corresponding, the positioning frame is vertically connected between the same side vertical rods on the bottom plate and is a vertical rectangular frame, the top of the height direction of the positioning frame is provided with a pair of positioning holes arranged along the horizontal direction, clamping bolts are matched in the positioning holes, and a plurality of pairs of positioning holes arranged along the horizontal direction are uniformly distributed on the upper part of the positioning frame and are matched with the positioning bolts;
the lever assembly comprises a support, a force adding arm and a push rod, wherein the support is horizontally arranged above the lifting plate and corresponds to the opposite side of the positioning frame, the support is supported on the bottom plate through a vertical support piece, the lower end of the force adding arm is hinged to the support, the rotation angle of the force adding arm is limited by the positioning frame, the upper end of the push rod is slidably connected to the force adding arm, and the lower end of the push rod is connected to the lifting plate; the upper end of the force adding arm extends out of the positioning frame;
the support comprises a T-shaped plate and a vertical lug plate connected to a web plate of the T-shaped plate, a hinge hole is formed in the top of the vertical lug plate, and a round hole is formed in the web plate corresponding to the outer side of the vertical lug plate; the vertical support piece is a support plate, the upper end of the vertical support piece is connected to the middle position of the outer edge of the T-shaped plate wing plate, and the lower end of the vertical support piece is connected to the upper side of the bottom plate; the lower end of the stress application arm is hinged to the top of the vertical lug plate through a pin shaft;
the push rod is a cylindrical rod, the upper end of the push rod is spherical, and two planes which are symmetrical relative to the axial center plane of the push rod are processed on the outer wall of the upper section of the push rod; the stress application arm comprises a rectangular hinging section and a cylindrical section, and the cylindrical section is in threaded connection with the upper end of the rectangular hinging section;
the middle part of the stress application arm is provided with a push rod mounting groove, and the bottom of the stress application arm is provided with a vertical lug plate mounting groove; the push rod mounting groove is positioned in the middle of the rectangular hinged section, the two ends of the push rod mounting groove are spherical, and the shape of the middle section is matched with the combined shape of the upper end and the upper section of the push rod; the shape of the vertical lug plate mounting groove is matched with the rotating track of the rectangular hinging section;
after the push rod is inserted and installed from the upper end of the push rod installation groove, the lower end of the push rod passes through a round hole on the outer side of the T-shaped plate web plate and is connected to the upper side of the lifting plate;
the sample preparation steps are as follows:
soil sample preparation
(1) After the agglomerate and block-shaped disturbance soil sample is air-dried, the agglomerate and block-shaped disturbance soil sample is rolled and scattered on a rubber plate on the premise of not damaging the natural structure of soil particles;
(2) Sieving the ground soil sample according to the required soil sample amount, fully and uniformly stirring the soil sample below the sieve, and taking out the soil sample for the test by a four-division diagonal sampling method to serve as a disturbance scattered soil sample for sample preparation;
(3) Preparing a sample with a certain water content, taking 1-2 kg of sieved air-dried soil, spreading the sample in a non-water-absorbing tray, spraying the required water adding amount by a sprayer, fully and uniformly stirring, and then placing the sample into a moisture-retaining device for soaking for a day and night, wherein the required water adding amount is calculated according to the following formula:
（1）
wherein:m w the amount of water (g) required for the test sample,
w 1 the required moisture content (%) of the sample,
m 0 the mass (g) of the air-dried soil,
w 0 -moisture content (%) of air-dried soil;
(4) Measuring the water content of the infiltrated sample, wherein the difference value between the qualified soil sample and the required water content is not more than +/-1%;
(5) Weighing a plurality of parts of qualified soil samples by equal mass for preparing samples, wherein the mass of each part is the mass of each layer of soil sample during sample preparation, and the mass of each layer of soil sample is calculated according to the following formula:
（2）
wherein:m e the mass (g) of each layer of soil sample,
dry Density of samples (g/cm) 3 )，
VSample volume (cm) 3 )，
n-number of layers of layered sample preparation;
w 0 -moisture content (%) of air-dried soil;
2. moulding die
(1) The cylindrical section of the lever assembly force adding arm is supported on a clamping bolt at the top of the positioning frame, so that the lifting plate is positioned at the highest position, and the punch connected with the lifting plate is positioned at the highest position;
(2) Inserting a positioning bolt into a positioning hole at the lowest part of a positioning hole group at the upper part of the positioning frame;
(3) Drawing out the sliding block, the mould supporting plate and the sample preparation mould along the guide rail, loading a first layer of soil sample into a cylindrical barrel of the sample preparation mould, and then integrally loading the first layer of soil sample back onto the guide rail until the sample preparation mould corresponds to the position of the punch;
(4) Pulling out a clamping bolt at the top of the positioning frame, applying downward force to the upper end section of the force adding arm, enabling the force adding arm to rotate downwards around the hinged position of the lower end of the force adding arm, enabling the push rod to move downwards together with the lifting plate and the punch thereon until the upper end section of the force adding arm moves to the lowest limit position of the positioning frame, and compacting the first layer of soil sample to the set thickness;
(5) Applying a reverse force to the cylindrical section to enable the stressing arm to reversely rotate until the cylindrical section returns to the highest position, and reinserting a clamping bolt at the top of the positioning frame to support the cylindrical section, so that the punch returns;
(6) Digging the surface of the compacted soil sample in the sample preparation mould;
(7) Pulling out the locating pin in the step (2) and inserting the locating pin into the last locating hole, repeating the steps (3) to (6), and repeating the steps, compacting each subsequent layer of soil sample, wherein a pile casing is sleeved on the top of the cylindrical barrel when the last layer of soil sample is filled into the sample preparation mould, and the surface of the compacted soil sample is not subjected to shaving treatment;
3. demolding
(1) Drawing out the slide block, the mould supporting plate and the sample preparation mould along the guide rail, and taking the sample preparation mould off the mould supporting plate;
(2) And (5) detaching the sample preparation die.
2. The method of claim 1, wherein: the linear guide rail is an SBR linear guide rail, two sliding blocks are arranged on the guide rail, and a vertical magnetic limiting rod is connected to the outer side of the bottom support of the guide rail, corresponding to one of the sliding blocks.
3. The method of claim 2, wherein: the bottom plate and the die supporting plate are rectangular steel plates, the plane size of the die supporting plate is smaller than that of the bottom plate, the die supporting plate is fixed on the sliding block, and the die supporting plate and the bottom plate are arranged on the central plane in the common width direction.
4. The method of claim 1, wherein: the lifting plate is a rectangular plate, the punch comprises a pull rod and a pressure plate at the lower end of the pull rod, the upper end of the pull rod is welded at the lower side of the lifting plate, linear bearings are fixed at four corners of the lifting plate, two ends of each linear bearing extend out of the lifting plate, and the lifting plate is sleeved on the vertical rod through the linear bearings.
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| CN110208065B (en) * | 2019-06-28 | 2021-07-16 | 长沙理工大学 | Rock-like sample integrated preparation device and method for controlling compaction degree in batches |
| CN112067381B (en) * | 2020-08-07 | 2022-09-09 | 浙江海洋大学 | Sample preparation device and method for roadbed level filler soil |
| CN111999141B (en) * | 2020-08-19 | 2022-05-13 | 安徽伟基基础工程有限公司 | Foundation consolidates geotechnique with pressing appearance device |
| CN112729985B (en) * | 2020-12-24 | 2022-05-27 | 上海交通大学 | Device for preparing soil sample through layering compaction |
| CN114414320B (en) * | 2021-12-01 | 2023-11-24 | 上海工程技术大学 | Static pressure rapid sample preparation device for triaxial test, sample preparation method and demolding method |
| CN115420576B (en) * | 2022-11-04 | 2023-03-24 | 成都理工大学 | Discrete dynamic triaxial test sample preparation device |
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