CN111474047B - Test method for verifying hydrodynamic pressure in bank slope soil body - Google Patents
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- 239000002689 soil Substances 0.000 title claims abstract description 141
- 238000010998 test method Methods 0.000 title claims abstract description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 199
- 238000012360 testing method Methods 0.000 claims abstract description 51
- 230000035699 permeability Effects 0.000 claims abstract description 40
- 230000035515 penetration Effects 0.000 claims abstract description 6
- 230000008595 infiltration Effects 0.000 claims description 19
- 238000001764 infiltration Methods 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 12
- 239000011148 porous material Substances 0.000 claims description 9
- 229920001971 elastomer Polymers 0.000 claims description 7
- 239000003292 glue Substances 0.000 claims description 6
- 229920006395 saturated elastomer Polymers 0.000 claims description 6
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- 239000004576 sand Substances 0.000 claims description 4
- 239000004746 geotextile Substances 0.000 claims description 3
- 230000005251 gamma ray Effects 0.000 claims description 2
- 238000011946 reduction process Methods 0.000 claims description 2
- 239000008400 supply water Substances 0.000 claims description 2
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- 239000002245 particle Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 230000003204 osmotic effect Effects 0.000 description 1
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- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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Abstract
A test method for verifying the existence of hydrodynamic pressure in a bank slope soil body can be improved based on most simple penetration devices, and is efficient, economic and strong in operability; after a testing device is improved, a plurality of groups of soil samples with different permeability coefficients are prepared for carrying out a permeability test, the water head and the stress in the soil body in the test are acquired in a targeted mode according to the concept of the hydrodynamic pressure, so that the accuracy of the test is ensured, finally, the existence of the hydrodynamic pressure is verified by analyzing the change rule of the water head and the stress in the soil body acquired from the soil samples in the test under different permeability coefficients, and a scientific basis is provided for accurately grasping the concept of the hydrodynamic pressure in the field of analysis and evaluation of the bank slope stability of the reservoir.
Description
Technical Field
The invention relates to a reservoir bank slope stability analysis test, in particular to a test method for verifying hydrodynamic pressure in bank slope soil.
Background
The concept and the calculation method of the hydrodynamic pressure are important for calculating the stability of the reservoir bank hydrodynamic pressure type slope. However, some scholars at present confuse the concept of hydrodynamic pressure and permeability in slope stability research, and research the hydrodynamic pressure aiming at the state at a certain moment has insufficient scientific basis.
In fact, the hydrodynamic pressure is a physical force generated by the formation of unbalanced water pressure difference in the soil body due to the fact that the dissipation of pore water of the soil body lags behind the dissipation of reservoir water in the rapid decrease process of the reservoir water level. When the reservoir water level is lowered synchronously with the underground water level in the slope, the soil body is subjected to stable seepage force. When the reservoir water level is rapidly reduced and the reduction speed of the reservoir water level is obviously higher than the reduction speed of the underground water level in the soil body of the side slope, the water level in the slope body is higher than the reservoir water level, and the soil body is also subjected to hydrodynamic pressure generated by the difference of the internal and external water pressure of the slope body on the basis of stable permeability.
Disclosure of Invention
The invention aims to solve the technical problem of providing a test method for proving the existence of the hydrodynamic pressure, which can verify the existence of the hydrodynamic pressure and provide a scientific basis for accurately grasping the concept of the hydrodynamic pressure in the field of analysis and evaluation of the stability of the reservoir bank slope.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a test method for verifying the existence of hydrodynamic pressure in a bank slope soil body comprises the following steps:
the method comprises the following steps: the conventional infiltration device is improved, and a plurality of groups of pressure measuring pipes capable of measuring the water head in the soil body are added on the main body of the infiltration instrument;
step two: preparing a plurality of groups of test soil samples according to the permeability coefficient, and paving a plurality of groups of strain gauges in the soil samples in the permeameter main body when each group of soil samples are loaded;
step three: after each group of soil samples are loaded, performing a penetration test and simulating a reservoir water level descending process to obtain the change conditions of the water level inside the soil body and the total stress;
step four: and analyzing the soil body internal water heads and the total pressure change rule of the soil samples with different permeability coefficients at the same initial water head and the same moment to prove the existence of the hydrodynamic pressure.
In the first step, the infiltration device comprises an infiltration instrument main body, one side of the infiltration instrument main body is connected with a water supply device, and the other side of the infiltration instrument main body is connected with a water collecting device;
the water supply device comprises a water storage tank and a water supply barrel, wherein the water storage tank is connected with the water supply barrel, and the water supply barrel is connected with the permeameter main body through a rubber pipeline and supplies water to the permeameter main body;
the permeameter main body comprises a sample containing cylinder, an upper cover plate, a permeable plate, a supporting tube and a lower cover plate, wherein a row of pressure measuring tubes are arranged on the sample containing cylinder at intervals;
the water collecting device comprises a water collecting barrel, and the water collecting barrel is connected with the permeameter main body through a rubber pipe.
In the first step, 5 pressure measuring pipes are arranged at intervals of 10cm from the boundary of the upper cover plate at the position of 5cm, and the distance between the pressure measuring pipes and the lower boundary of the sample containing cylinder is 5cm.
Step one, when the pressure measuring pipe is installed, a layer of geotextile is wrapped at a water inlet of the pressure measuring pipe which is in contact with a test soil sample; winding a water stopping adhesive tape on the side wall of the water inlet end of the piezometric tube; after the pressure measuring pipe is installed, AB glue is smeared at the contact part of the pressure measuring pipe and the sample containing barrel, and whether the device leaks water is checked after the glue is dried.
In the second step, when a plurality of groups of test soil samples are prepared, 5 soil samples with different permeability coefficients can be prepared, and are respectively marked as K1, K2 \8230, 8230and K5, wherein 3 groups of parallel samples are arranged under each permeability coefficient to prepare 15 groups of soil samples;
and step two, filling sand gravel at the permeable plate of the water inlet during sample filling, taking a soil sample with certain mass during sample filling, filling the soil sample in layers, wherein the thickness of each layer is 5cm, and burying a plurality of strain gauges at intervals between layers until a sample containing barrel of the permeameter main body is filled with compacted soil.
The test method in the third step comprises the following steps:
1) After the sample loading is finished, the infiltration device is vertically inverted and fixed (namely, the upper cover plate and the water inlet are arranged at the lower part, and the water outlet of the lower cover plate is arranged at the upper part), a water supply barrel supplies water slowly to the apparatus from the water inlet of the upper cover plate to enable the soil sample to be saturated by water inflow from bottom to top, and when water flows exist at the water outlet of the lower cover plate, the sample is kept stand for 24 hours and is fully saturated.
2) Adjusting the height of a water supply barrel of the water supply device to a required water head height, and adjusting the height of the water supply barrel once every a period of time according to the maximum descending rate Vmax of the reservoir water level when the water outlet of a water collecting barrel of the water collecting device is stable;
3) Recording the starting moment of the test as t0 according to the water level descending speed determined in the step 2), recording the time interval once every 6h, descending the height of the water supply barrel by 30cm, standing for 1-2 min, recording the water level of the piezometer tube and the reading of the strain gauge after the seepage in the device is stable, and obtaining t 1 ……t n Experimental data of time of day.
4) And repeating 1) and 3) according to the grouping condition of the soil samples to obtain the water level of the piezometer pipe and the data of the strain gauge of the test soil samples under different permeability coefficients.
The invention discloses a test method for verifying the existence of hydrodynamic pressure in a bank slope soil body, which has the following technical effects:
1) According to the deduced hydrodynamic pressure calculation formula, a feasible test method for verifying the existence of the hydrodynamic pressure is established in a targeted manner, the method can be used for testing on the basis of the devices modified by most simple permeation devices, and the method is efficient, economical and strong in operability.
2) The method comprises the steps of preparing a plurality of groups of soil samples with different permeability coefficients to carry out a permeability test, obtaining the water head and the stress inside the soil body in the test in a targeted mode according to the concept of the hydrodynamic pressure to ensure the accuracy of the test, and finally verifying the existence of the hydrodynamic pressure by analyzing the change rule of the water head and the stress inside the soil body obtained from the soil samples in the test under different permeability coefficients, so that a scientific basis is provided for accurately mastering the concept of the hydrodynamic pressure in the field of analysis and evaluation of the stability of the reservoir bank slope.
Drawings
The invention is further illustrated with reference to the following figures and examples:
FIG. 1 is a flow chart of the present invention.
FIG. 2 is a schematic view of an osmotic engine according to the present invention.
Fig. 3 is a schematic structural view of the permeameter main body in the present invention.
Fig. 4 is a cross-sectional view of the permeameter body according to the present invention.
In the figure: the device comprises a water supply device 1, a permeameter main body 2, a water collecting device 3, a barrel cover 4, a water supply barrel 5, a rubber pipe 6, a valve 7, a water storage tank 8, an upper cover plate 9, a pressure measuring pipe 10, a support pipe 11, a connecting plate 12, a sample containing barrel 13, a lower cover plate 14, a strain gauge 15, a water collecting barrel 16, a water stopping adhesive tape 17, a water permeable plate 18 and gravel 19.
Detailed Description
As shown in fig. 2-3, a test device for verifying the existence of hydrodynamic pressure in the bank slope soil body is improved on the existing penetration device.
The device comprises a water supply device 1, a permeameter main body 2 and a water collecting device 3.
The water supply device 1 comprises a water storage tank 8 and a water supply barrel 5, wherein the water storage tank 8 is connected with the water supply barrel 5, and the water supply barrel 5 is connected with the permeameter main body 2 through a rubber pipe 6 to supply water for the permeameter main body 2.
The water collecting device 3 comprises a water collecting barrel 16, and the water collecting barrel 16 is connected with the permeameter main body 2 through a rubber pipe 6.
As shown in fig. 4, the main body of the permeameter 2 comprises a sample holding cylinder 13, an upper cover plate 9, a permeable plate 18, a support tube 11 and a lower cover plate 14. Wherein, the sample containing cylinder 13 is 50cm long and 15cm in inner diameter.
In order to obtain the real-time change condition of the water head in the soil body during the test, a row of piezometer tubes 10 are arranged on the sample containing barrel 13 of the permeameter main body 2.
5 pressure measuring pipes 10 are arranged at intervals of 10cm from the boundary of the upper cover plate 9, and 5 pressure measuring pipes are arranged in total, wherein the distance between all the pressure measuring pipes 10 and the lower boundary of the sample containing barrel 13 is 5cm.
When the pressure measuring pipe 10 is installed, the end of the water inlet of the pressure measuring pipe 10, which is in contact with a test soil sample, is wrapped by a layer of geotextile, so that soil particles are prevented from entering the pressure measuring pipe to cause blockage in the test process.
In addition, the side wall of the water inlet of the pressure measuring pipe 10 is wound by a water stop adhesive tape, AB glue is coated at the contact part of the pressure measuring pipe 10 and the sample containing barrel 13 after the pressure measuring pipe 10 is installed, and whether the device leaks water is checked after the glue is dried.
The test method for verifying the existence of hydrodynamic pressure in the bank slope soil body by adopting the device comprises the following steps:
step 1, screening the soil sample taken back on site to obtain particles with different particle sizes, and bagging the obtained soil particles respectively for later use.
And 2, preparing 5 soil samples with different permeability coefficients by the soil particles with different particle sizes obtained in the step 1, wherein the soil samples are respectively marked as K1, K2 \8230, 8230and K5, and 3 groups of parallel samples are arranged under each permeability coefficient to prepare 15 groups of soil samples.
And 3, in order to obtain the stress change condition inside the soil body during the penetration test, laying strain gauges 15 in the penetration device, and burying one strain gauge 15 every 5cm from the 2.5cm position of the boundary of the upper cover plate 9 as shown in fig. 4, wherein the total number of the strain gauges is 10.
And 4, filling sand and gravel 19 at the left and right permeable plates 18 to achieve the effects of water inlet buffering and uniform infiltration, and filling soil samples in the space in the sample containing barrel 13 between the sand and gravel 19. When filling the soil sample, the soil sample with certain mass is taken and layered to be filled, the thickness of each layer is 5cm, the strain gauge 10 is embedded between layers until the compacted soil body fills the sample containing cylinder 13 of the infiltration instrument 2. The strain gauge 10 is connected with a strain gauge, so that the magnitude of the internal stress of the soil body is obtained.
And 5, after sample loading is finished, slowly supplying water to the instrument by using a water supply barrel to enable the soil sample to be saturated by water inflow from bottom to top, and standing the sample for 24 hours to be fully saturated when water flows exist at a water outlet at the top.
And 7, recording the starting moment of the test as t according to the water level descending speed determined in the step 6 0 Recording time interval every 6h, reducing height of water supply barrel 5 by 30cm, standing for 1-2 min, recording water level of piezometer and reading of strain gauge after seepage is stabilized in the device to obtain t 1 ……t n Test data at time.
And 8, repeating the steps 4-7 according to the grouping condition of the soil samples to obtain the data of the water level of the piezometer tube and the strain gauge of the test soil sample under different permeability coefficients. And (4) comparing the water levels of the piezometric tubes of the test soil samples with different permeability coefficients and the internal stress of the soil body at the same time t because the initial water heads of the 5 groups of test soil samples are the same.
The hydrodynamic pressure calculation formula is as follows:
△F＝γ w ·△i·V d
△h＝h 0 -h t
wherein Δ F is the hydrodynamic pressure (unit: N); gamma ray w Is the weight of water (unit: N/m) 3 )；V d Is the volume (unit: m) below the soil body infiltration line 3 ) (ii) a Δ i is the hydraulic gradient (dimension 1); delta d is the horizontal width (unit: m) of the soil body; h is t For synchronous reduction of water level in soil body and reservoir water levelWater level (unit: m); h is 0 The water level (unit: m) is the water level when the water level in the slope body is delayed and the reservoir water level is reduced when the water level is rapidly reduced.
According to the concept of hydrodynamic pressure, the hydrodynamic pressure is a physical force generated by the fact that dissipation of pore water of a soil body lags behind dissipation of reservoir water in the rapid reduction process of the reservoir water level and unbalanced water pressure difference is formed in the soil body. That is, if hydrodynamic pressure exists in the bank slope soil body, the infiltration line in the soil body is higher than that in the normal drainage of the soil body along with the rapid decrease of the reservoir water level, and the permeability coefficient of the bank slope soil body is smaller due to the phenomenon. In order to verify the existence of the hydrodynamic pressure, soil samples with different permeability coefficients in 5 are prepared in step 2: are respectively marked as K 1 ，K 2 ……K 5 Meanwhile, 3 groups of parallel samples are arranged to avoid errors generated in the experimental process. And at the same initial head H through steps 4-7 0 And acquiring the water level h of the piezometer tube and the internal stress P of the soil body of each group of test soil samples at different moments t under the condition of the water level descending speed v.
Taking test soil sample groups K1 and K2 as examples, comparing the change rules of the water level of the piezometric tube and the internal stress of the soil body of test soil samples with different permeability coefficients at the same time t:
the comparison being at the same time t n Soil sample K for lower test 1 And K 2 The water head of the piezometer tube draws an internal water head line L of each group of soil samples according to five pieces of piezometer tube data obtained by each group of soil samples K1 And L K2 If the water level line L inside the soil sample is L, because the permeability coefficient K1 of the tested soil sample is more than K2 K2 Is obviously higher than L K1 It is proved that the dissipation of pore water in the soil body generates a hysteresis phenomenon along with the reduction of the permeability coefficient, and the water level difference between the pore water and the pore water can cause the generation of hydrodynamic pressure. Internal water head connecting line L for taking two groups of soil samples at present K1 And L K2 (i.e. h) mid-point head k1 And h K2 ) The water level difference of two groups of soil samples with different permeability coefficients can be obtained at the moment:
the horizontal length d of the test instrument of the invention is 0.5m, the hydraulic gradient at that moment can be obtained:
the wet weight gamma of the soil sample is determined according to the K2 group test wK2 And the volume V of the soil below the saturation line d The hydrodynamic pressure generated when the permeability coefficient of the soil body is K2 at the moment is obtained compared with the hydrodynamic pressure generated when the permeability coefficient is K1:
secondly, comparing the internal stress P of the two groups of test soil samples K1 And P K2 If P is K2 ＞P K1 It is proved that the internal stress of the soil body increases with the decrease of the permeability coefficient. And meanwhile, the increment of the internal stress of the soil body can be obtained, namely:
if it is
And with
If they are close, the existence of the hydrodynamic pressure can be further confirmed.
And similarly, comparing the water head h of the piezometric tube and the internal stress P of the soil body obtained by the other groups of test soil samples at the same moment, and if the water level h of the piezometric tube is increased along with the reduction of the permeability coefficient and the internal stress P of the soil body is increased, proving that the hydrodynamic pressure exists.
Claims (3)
1. A test method for verifying the existence of hydrodynamic pressure in a bank slope soil body is characterized in that: the method comprises the following steps:
the method comprises the following steps: the conventional infiltration device is improved, and a plurality of groups of pressure measuring pipes capable of measuring the water head in the soil body are added on the main body of the infiltration instrument;
step two: preparing a plurality of groups of test soil samples according to the permeability coefficient, and paving a plurality of groups of strain gauges in the soil samples in the permeameter main body when each group of soil samples are loaded;
step three: after each group of soil samples are loaded, carrying out a penetration test and simulating a reservoir water level descending process to obtain the change conditions of the soil body internal water level and the total stress;
step four: analyzing the soil body internal water heads and the total pressure change rule of soil samples with different permeability coefficients at the same initial water head and the same moment to prove the existence of the dynamic water pressure;
in the first step, the infiltration device comprises an infiltration instrument main body (2), one side of the infiltration instrument main body (2) is connected with the water supply device (1), and the other side of the infiltration instrument main body is connected with the water collection device (3);
the water supply device (1) comprises a water storage tank (8) and a water supply barrel (5), wherein the water storage tank (8) is connected with the water supply barrel (5), and the water supply barrel (5) is connected with the permeameter main body (2) through a rubber pipe (6) to supply water to the permeameter main body (2);
the permeameter main body (2) comprises a sample holding cylinder (13), an upper cover plate (9), a water permeable plate (18), a supporting pipe (11) and a lower cover plate (14), wherein a row of pressure measuring pipes (10) are arranged on the sample holding cylinder (13) at intervals;
the water collecting device (3) comprises a water collecting barrel (16), and the water collecting barrel (16) is connected with the permeameter main body (2) through a rubber pipe (6);
in the first step, 5 pressure measuring pipes (10) are arranged at intervals of 10cm from the boundary of an upper cover plate (9) at the position of 5cm, and the distance between the pressure measuring pipes (10) and the lower boundary of a sample containing cylinder (13) is 5cm;
the test method in the third step comprises the following steps:
1) After sample loading is finished, the infiltration device is vertically inverted and fixed, water is slowly supplied to the apparatus from a water inlet at the upper cover plate by a water supply barrel to enable the soil sample to be saturated by water inflow from bottom to top, and the sample is kept stand for 24 hours and fully saturated when water flows exist at a water outlet at the lower cover plate;
2) Adjusting the water supply barrel (5) of the water supply device (1) to a required water head height, and adjusting the height of the water supply barrel (5) at intervals according to the maximum falling rate Vmax of the reservoir water level when the water outlet of the water collecting barrel (16) of the water collecting device (3) is stable;
3) Recording the starting moment of the test as t0 according to the water level descending speed determined in the step 2), recording the time interval once every 6h, descending the height of the water supply barrel (5) by 30cm, standing for 1-2 min, recording the water level of the piezometer and the reading of the strain gauge after the seepage in the device is stable, and obtaining t 1 ……t n Test data at the time;
4) Repeating 1) to-3) according to the grouping condition of the soil samples to obtain the water level of the piezometer tube and the data of the strain gauge of the test soil sample under different permeability coefficients;
2.5cm from the boundary of the upper cover plate (9), burying strain gauges (15) every 5cm for 10 in total;
the hydrodynamic pressure calculation formula is as follows:
△F＝γ w ·△i·V d
△h＝h 0 -h t
wherein Δ F is the hydrodynamic pressure (unit: N); gamma ray w Is the water gravity, unit: n/m 3 ；V d Volume below the soil saturation line, unit: m is 3 (ii) a Delta i is hydraulic gradient with dimension of 1; and delta d is the width of the soil body in the horizontal direction, and the unit is as follows: m; h is a total of t The unit is the water level when the water level in the soil body and the reservoir water level synchronously descend: m; h is a total of 0 Is the water level when the water level descends rapidly and the water level in the slope body lags behind the water level in the reservoir descends, the unit: m;
according to the concept of hydrodynamic pressure, the hydrodynamic pressure is physical force generated by the fact that dissipation of pore water of a soil body lags behind dissipation of reservoir water in the rapid reduction process of the reservoir water level and unbalanced water pressure difference is formed in the soil body; in the bank slope soil bodyThe dynamic water pressure exists, and along with the rapid reduction of the reservoir water level, the infiltration line in the soil body is higher than that of the soil body during normal drainage, so that the permeability coefficient of the bank slope soil body is smaller; in order to verify the existence of the hydrodynamic pressure, soil samples with different permeability coefficients in 5 are prepared in the second step: are respectively marked as K 1 ，K 2 ……K 5 Meanwhile, 3 groups of parallel samples are arranged to avoid errors generated in the experimental process; and through steps 1) to 4) in the third step, at the same initial head H 0 Acquiring the water level h of the piezometer tube and the internal stress P of the soil body of each group of test soil samples at different moments t under the condition of the water level descending speed v;
taking test soil sample groups K1 and K2 as examples, comparing the change rules of the water level of the piezometric tube and the internal stress of the soil body of test soil samples with different permeability coefficients at the same time t:
comparing at the same time t n Soil sample K for lower test 1 And K 2 The water head of the piezometer tube draws an internal water head line L of each group of soil samples according to five pieces of piezometer tube data obtained by each group of soil samples K1 And L K2 If the water level line L inside the soil sample is L, because the permeability coefficient K1 of the tested soil sample is more than K2 K2 Is obviously higher than L K1 The result shows that the dissipation of pore water in the soil body generates a hysteresis phenomenon along with the reduction of the permeability coefficient, and the water level difference between the pore water and the pore water can cause the generation of hydrodynamic pressure; internal water head connecting line L for taking two groups of soil samples at present K1 And L K2 Mid-point head of (h) k1 And h K2 The water level difference of two groups of soil samples with different permeability coefficients can be obtained at the moment:
the horizontal length d of the test apparatus is 0.5m, the hydraulic gradient at this moment can be obtained:
the wet weight gamma of the soil sample is determined according to the K2 group test wK2 And volume V below the soil saturation line d The hydrodynamic pressure generated when the permeability coefficient of the soil body is K2 at the moment is obtained compared with the hydrodynamic pressure generated when the permeability coefficient is K1:
secondly, the internal physical stress P of the two groups of test soil samples obtained by comparison K1 And P K2 If P is K2 ＞P K1 The internal stress of the soil body is proved to be increased along with the reduction of the permeability coefficient; and meanwhile, the increment of the internal stress of the soil body can be obtained, namely:
if it is
And
if the pressure is close, the existence of the hydrodynamic pressure can be further proved;
and similarly, comparing the water head h of the piezometric tube and the internal stress P of the soil body obtained by the other groups of test soil samples at the same moment, and if the water level h of the piezometric tube is increased along with the reduction of the permeability coefficient and the internal stress P of the soil body is increased, proving that the hydrodynamic pressure exists.
2. The test method for verifying the existence of hydrodynamic pressure in the bank slope soil body according to claim 1, characterized in that: in the first step, when the pressure measuring pipe (10) is installed, a layer of geotextile is wrapped at a water inlet of the pressure measuring pipe (10) which is in contact with a test soil sample; the side wall of the water inlet end of the pressure measuring pipe (10) is wound by a water stopping adhesive tape; after the pressure measuring pipe is installed, AB glue is smeared at the contact part of the pressure measuring pipe and the sample containing barrel (13), and whether the device leaks water is checked after the glue is dried.
3. The test method for verifying the existence of hydrodynamic pressure in the bank slope soil body according to claim 1, characterized in that: in the second step, sand gravel (19) is filled at the permeable plate (18) of the water inlet during sample filling, a soil sample with certain mass is taken and layered for sample filling, the thickness of each layer is 5cm, a plurality of strain gauges (10) are embedded at intervals between layers until a sample containing cylinder (13) of the permeameter main body (2) is filled with compacted soil.
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