CN113533123A - Triaxial soil sample seepage erosion and shear test device and test method thereof - Google Patents
Triaxial soil sample seepage erosion and shear test device and test method thereof Download PDFInfo
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- 238000012360 testing method Methods 0.000 title claims abstract description 70
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- 230000007246 mechanism Effects 0.000 claims abstract description 105
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 72
- 239000002245 particle Substances 0.000 claims abstract description 49
- 238000005303 weighing Methods 0.000 claims abstract description 14
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- 238000006073 displacement reaction Methods 0.000 claims description 16
- 239000012530 fluid Substances 0.000 claims description 15
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- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
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Abstract
The invention relates to the technical field of soil sample seepage erosion detection, and discloses a triaxial soil sample seepage erosion and shear test device and a test method thereof, wherein the triaxial soil sample seepage erosion and shear test device comprises: a fixing mechanism; the confining pressure mechanism is used for applying pressure to the soil sample in the horizontal direction; the vertical loading mechanism and the back pressure mechanism jointly apply uniform and constant pressure to the interior of the soil sample; the seepage mechanism is used for applying water pressure to the soil sample to perform a seepage erosion experiment on the soil sample; and the particle collecting mechanism is used for collecting and weighing the falling particles in the soil sample. The device can realize the preparation of soil samples with different consolidation confining pressures and initial stress ratios, can realize the automatic collection of seepage erosion samples and particles of the soil samples under the condition of complex initial stress, can develop the triaxial shear mechanical property test of the seepage erosion soil samples, and is beneficial to researching the seepage process, the erosion process and the mechanical behavior evolution process of the soil body inside the foundation facilities such as dams, side slopes and the like under the complex load environment.
Description
Technical Field
The invention relates to the technical field of soil sample seepage erosion detection, in particular to a detection device and a test method for soil sample seepage erosion under a triaxial loading condition and a shear test method for seepage erosion soil samples.
Background
The foundation soil is easy to be subjected to seepage erosion under the action of strong seepage induced by rainstorm and the like, and comprises piping and flowing soil. The concrete expression is that fine particles in the soil body pass through skeleton pores formed by coarse particles under the action of seepage force, and particle loss is generated. In order to describe the macroscopic mechanical behavior of the foundation soil body, the indoor test usually takes a triaxial test device as a main part, tests the stress-strain response of the soil body under different stress histories and state conditions, and further describes the mechanical response of the soil body under different service environments.
The existing triaxial test equipment can realize triaxial shear test under the conditions of monotonous drainage, no drainage and cyclic loading of soil under different initial stress states (stress isotropy or anisotropy). The existing one-dimensional seepage test equipment can realize one-dimensional seepage test under the complete lateral limit condition, further test the permeability coefficient and the critical hydraulic gradient of a soil body under the simple stress condition, and realize the phenomena of piping, soil flowing and the like.
The existing triaxial test equipment can not consider the seepage effect inside the soil sample and the hydraulic gradient effect of the upstream and downstream, and can not simulate the seepage erosion effects such as migration and loss of particles inside the soil sample under the influence of seepage, including piping and soil flowing phenomena.
The existing one-dimensional seepage test equipment cannot consider the complex stress history and stress state of a real soil body, can only be used for describing the in-soil seepage under the action of one-dimensional seepage, cannot describe the internal seepage of the soil body under the complex load environment of basic facilities such as dams, side slopes and the like, and cannot realize the automatic collection of particles.
Disclosure of Invention
The purpose of the invention is: the triaxial soil sample seepage erosion and shear test device can realize preparation of soil samples with different consolidation confining pressures and initial stress ratios, can realize automatic collection of seepage erosion samples and particles of the soil samples under the condition of complex initial stress, and is favorable for researching the internal seepage effect of soil bodies of basic facilities such as dams, side slopes and the like under the complex load environment.
In order to achieve the above object, the present invention provides a triaxial soil sample seepage erosion and shear test apparatus, comprising:
a fixing mechanism for fixing the soil sample;
the confining pressure mechanism acts on the periphery of the soil sample and is used for applying constant pressure to the soil sample in the horizontal direction;
the vertical loading mechanism is arranged above the soil sample and applies downward pressure to the soil sample;
a back pressure mechanism provided below the soil sample, the back pressure mechanism applying an upward pressure to the soil sample;
the seepage mechanism is connected with the soil sample to apply water pressure to the soil sample so as to carry out seepage erosion experiment on the soil sample;
and the particle collecting mechanism is arranged below the fixing mechanism and is used for collecting and weighing the particles falling from the soil sample.
Compared with the prior art, the triaxial soil sample seepage erosion and shear test device provided by the embodiment of the invention has the beneficial effects that: the fixing mechanism is used for fixing a soil sample, the confining pressure mechanism and the vertical loading mechanism are used for applying stress to the periphery, the upper end face and the lower end face of the soil sample, the soil sample can meet the requirements of different initial stresses, the seepage mechanism applies water pressure to the soil sample after the soil sample meets the conditions of external stress, the counter pressure mechanism applies corresponding pressure to the bottom of the soil sample, the upper portion and the lower portion of the soil sample reach preset pressure difference, particles in the soil sample are subjected to seepage erosion under constant pressure, the particle collecting mechanism below the soil sample collects particles of the seepage erosion soil sample, the particles are weighed, and the proportion of seepage erosion of the soil sample is obtained through calculation. The device can realize the preparation of soil samples with different consolidation confining pressures and initial stress ratios, can realize the automatic collection of seepage erosion samples and particles of the soil samples under the condition of complex initial stress, and is favorable for researching the internal seepage effect of soil bodies of basic facilities such as dams, side slopes and the like under the complex load environment.
The triaxial soil sample seepage erosion and shear test device provided by the embodiment of the invention further comprises a first pressure bin, the fixing mechanism is arranged in the first pressure bin, the fixing mechanism comprises a lower fixing part connected with the bottom wall of the first pressure bin and an upper fixing part abutted against the top surface of the soil sample, and the soil sample is arranged between the upper fixing part and the lower fixing part.
According to the triaxial soil sample seepage erosion and shear test device provided by the embodiment of the invention, the confining pressure mechanism comprises confining pressure fluid positioned in the first pressure bin and a confining pressure valve arranged on the first pressure bin, the confining pressure fluid covers the peripheral surface of the soil sample, and the confining pressure valve is used for pressurizing the confining pressure fluid.
According to the triaxial soil sample seepage erosion and shear test device provided by the embodiment of the invention, the bottom of the first pressure bin is provided with the outlet, the outer side of the outlet is provided with the drainage funnel, the drainage funnel is connected with the second pressure bin, the particle collecting mechanism is arranged in the second pressure bin, and the counter-pressure mechanism is arranged on the second pressure bin to control the pressure in the second pressure bin.
According to the triaxial soil sample seepage erosion and shear test device provided by the embodiment of the invention, the particle collecting mechanism comprises a collecting seat and a weighing device, the weighing device is fixed on the second pressure bin, and the collecting seat is connected with the weighing device.
According to the triaxial soil sample seepage erosion and shear test device provided by the embodiment of the invention, the outer side of the collecting seat is provided with the water collecting tank for maintaining the water level in the collecting seat stable, and the bottom of the second pressure bin is also provided with the drain valve for draining fluid overflowing from the water collecting tank out of the second pressure bin.
According to the triaxial soil sample seepage erosion and shear test device provided by the embodiment of the invention, the vertical loading mechanism comprises a pressure loading device and a displacement sensor, the pressure loading device is abutted to the position right above the soil sample, and the displacement sensor is used for measuring the vertical loading distance of the pressure loading device.
According to the triaxial soil sample seepage erosion and shear test device provided by the embodiment of the invention, the seepage mechanism comprises a water pressure bin and a pneumatic tube for controlling the pressure in the water pressure bin, the bottom of the water pressure bin is connected with a water inlet pipe, and the other end of the water inlet pipe is connected with the upper end surface of the soil sample.
The invention also provides a test method of the triaxial soil sample seepage erosion and shear test device, and the triaxial soil sample seepage erosion and shear test device adopted in the embodiment comprises the following steps:
fixing the soil sample to the fixing mechanism;
applying confining pressure to the periphery of the soil sample through the confining pressure mechanism, and applying constant pressure to the soil sample through the back pressure mechanism to keep the pressure in the soil sample constant;
applying axial stress to the soil sample through the vertical loading mechanism to complete the preparation of the soil sample to be detected;
applying water pressure to the soil sample through the seepage mechanism to enable the soil sample to be subjected to seepage erosion of water flow;
and collecting particles falling from the soil sample through the particle collecting mechanism, and detecting the particles to obtain a seepage erosion result.
Compared with the prior art, the triaxial soil sample seepage erosion test method provided by the embodiment of the invention has the beneficial effects that: the experimental method can realize the automatic collection of seepage erosion samples and particles under the condition of the soil sample with complex initial stress, and is beneficial to researching the seepage effect of the soil body of the foundation facilities such as dams, side slopes and the like under the complex load environment.
The triaxial soil sample seepage erosion and shear test device provided by the embodiment of the invention further comprises the following steps: after the water pressure is applied to the soil sample, so that the soil sample is subjected to seepage erosion of water flow, the ambient pressure of the first pressure bin is kept constant, the vertical loading mechanism continues to apply pressure to the soil sample in the axial direction, and the displacement sensor monitors the axial deformation of the soil sample until the soil sample is subjected to shear failure.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
FIG. 1 is a schematic structural diagram of a triaxial soil sample seepage erosion and shear test apparatus according to an embodiment of the present invention;
FIG. 2 is a flow chart of a testing method of the triaxial soil sample seepage erosion and shear testing apparatus according to an embodiment of the present invention.
In the figure, 1, a first pressure bin; 11. a confining pressure fluid; 12. an outlet; 13. a drainage funnel; 14. a hopper valve; 2. soil sampling; 21. a lower fixing portion; 22. an upper fixing portion; 3. a vertical loading mechanism; 31. a displacement sensor; 32. pressing a plate; 33. a cylinder; 34. a pressure lever 34; 4. a back pressure mechanism; 41. a second pressure bin; 42. a back pressure valve; 43. a drain valve; 5. a seepage mechanism; 51. a hydraulic pressure bin; 52. a pneumatic tube; 53. a water inlet pipe; 6. a particle collection mechanism; 61. a collecting seat; 62. a weighing device; 621. a support bar; 622. a bearing frame; 623. a weight measuring instrument; 63. a water collection tank.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
As shown in fig. 1, a triaxial soil sample seepage erosion and shear test apparatus according to a preferred embodiment of the present invention includes a first pressure chamber 1, an experimental station of a soil sample 2 is located in the first pressure chamber 1, a fixing mechanism is disposed in the first pressure chamber 1, the fixing mechanism is used for fixing the soil sample 2, the fixing mechanism includes a lower fixing portion 21 connected to a bottom wall of the first pressure chamber 1 and an upper fixing portion 22 abutted to a top surface of the soil sample 2, and the soil sample 2 is mounted on the fixing mechanism between the upper fixing portion 22 and the lower fixing portion 21;
as shown in fig. 1, in some embodiments of the present invention, the upper fixing portion 22 and the lower fixing portion 21 are both filter screens, and the area of the filter screens is slightly larger than the horizontal cross-sectional area of the soil sample 2, so as to wrap the soil sample 2 in the fixing mechanism. Specifically, the sieve of the lower fixing portion 21 is provided to pass only fine particles of the soil sample 2 for separating eroded particles of the soil sample 2 from the soil sample 2 during seepage; the upper part of the filter screen of the upper fixing part 22 is also provided with a water filtering stone to prevent external impurities from permeating into the soil sample 2.
As shown in fig. 1, a triaxial soil sample seepage erosion and shear test apparatus according to a preferred embodiment of the present invention includes a confining pressure mechanism acting on the periphery of a soil sample 2, the confining pressure mechanism being configured to apply pressure to the soil sample 2 in a horizontal direction; the soil sample testing device further comprises a vertical loading mechanism 3 arranged above the soil sample 2 and a back pressure mechanism 4 arranged below the soil sample 2, wherein the vertical loading mechanism 3 applies downward pressure to the soil sample 2, and the back pressure mechanism 4 applies upward pressure to the soil sample 2; the seepage mechanism 5 is connected with the soil sample 2, so that water pressure is applied to the soil sample 2 to perform a seepage erosion experiment on the soil sample 2; still include granule collection mechanism 6, it sets up in the fixed establishment below, and granule collection mechanism 6 is used for collecting and weighs the granule that falls down in the soil sample 2.
As shown in fig. 1, in some embodiments of the present invention, the confining pressure mechanism includes a confining pressure fluid 11 located in the first pressure chamber 1 and a confining pressure valve disposed on the first pressure chamber 1, the confining pressure fluid 11 covers the outer circumferential surface of the soil sample 2, and the confining pressure valve is configured to pressurize the confining pressure fluid 11, and the air pressure in the first pressure chamber 1 can be adjusted according to different experimental requirements to adjust the pressure of the confining pressure fluid 11 acting on the outer circumferential surface of the soil, so as to implement isotropic consolidation of the soil sample 2 under the condition that different pressure requirements are met. It is to be understood that the confining pressure fluid 11 includes water, etc., and the confining pressure valve can be electrically controlled or manually controlled, and is not limited thereto.
As shown in fig. 1, in some embodiments of the invention, the bottom of the first pressure bin 1 is provided with an outlet 12 for particles of the soil sample 2 eroded by seepage to enter the particle collection mechanism 6 through the outlet 12. The size of the outlet 12 is larger than the horizontal cross-sectional area of the soil sample 2 so that all particles of the soil sample 2 eroded by seepage can fall through the opening.
In some embodiments of the invention, as shown in fig. 1, a drainage funnel 13 is provided on the outside of the opening, which gradually shrinks from top to bottom, for collecting the particles together for weighing. The drain funnel 13 is provided with a funnel valve 14 for opening and closing a water flow path of the drain funnel 13. A second pressure bin 41 is connected below the drainage funnel 13, the particle collecting mechanism 6 is arranged in the second pressure bin 41, and the outlet 12 of the drainage funnel 13 extends into the particle collecting mechanism 6. Granule collection mechanism 6 is fixed in the bottom of second pressure storehouse 41, backpressure mechanism 4 sets up the pressure in order to control second pressure storehouse 41 on second pressure storehouse 41, backpressure mechanism 4 adjusts the pressure in second pressure storehouse 41 and keeps the inside stable back pressure of soil sample 2 through drainage funnel 13, and be used for adjusting the stress that soil sample 2 wholly received and the water pressure difference that the inside granule of soil sample 2 received at the seepage flow erosion in-process, guaranteed that the inside pore water pressure of sample is invariable, avoid because of the loss of 2 saturation of soil sample that the pore pressure reduces and leads to. Specifically, the back pressure mechanism 4 includes a back pressure valve 42 provided on the second pressure chamber 41, and the other end of the back pressure valve 42 is connected to an external pressure regulating device; it is understood that the back pressure valve 42 may be provided on a side wall or a top wall of the second pressure bin 41, and is not particularly limited thereto.
As shown in fig. 1, in some embodiments of the present invention, the particle collecting mechanism 6 includes a collecting seat 61 and a weighing device 62, the weighing device 62 is fixed to the second pressure chamber 41, specifically, the weighing device 62 includes a support rod 621 and a bearing frame 622, a weight measuring instrument 623 is disposed at the bottom of the bearing frame 622, and the collecting seat 61 is connected below the weight measuring instrument 623. The collecting seat 61 is provided just below the outlet 12 of the drain funnel 13 for receiving the particles falling from the drain funnel 13. The weight measuring instrument 623 detects the weight of the collecting seat 61 in real time, determines the loss amount of the particles of the soil sample 2 through the weight difference of the collecting seat 61 at the beginning and the end of seepage erosion, and also can estimate the particle loss speed of the soil sample 2 in different time periods through recording the weight of the collecting seat 61 in different time periods, thereby researching the seepage loss rate under different hydraulic gradient conditions.
As shown in fig. 1, in some embodiments of the present invention, a water collecting groove 63 is provided outside the collecting base 61, and the water collecting groove 63 can store water drained by the drain funnel 13 for maintaining a stable water level in the collecting base 61 and preventing the particle collecting mechanism 6 from being directly exposed to air. When the water level is higher than the side wall of the water collecting tank 63, the water level will overflow into the second pressure chamber 41, and the bottom of the second pressure chamber 41 is further provided with a drain valve 43 to drain the fluid overflowing from the water collecting tank 63 out of the second pressure chamber 41, so as to prevent the water level of the second pressure chamber 41 from being higher than the water level in the water collecting tank 63 and affecting the back pressure of the soil sample 2. The stable back pressure is maintained, and the weight measuring device is matched, so that the real-time measurement of the particle loss amount (rate) along with the development of time can be realized, the phenomena of seepage loss rate and the like under different hydraulic gradient conditions are researched, and the accuracy of the experiment is ensured.
As shown in fig. 1, in some embodiments of the present invention, the vertical loading mechanism 3 includes a pressure loading device and a displacement sensor 31, the pressure loading device abuts directly above the soil sample 2, on one hand, the pressure loading device can be used for applying axial stress to the soil sample 2 when preparing the soil sample 2, so as to realize preparation of an initial anisotropic sample, and the sample is matched with the confining pressure mechanism to reach a preset initial stress ratio; on the other hand, in the shear test, the pressure loading device is used for applying axial strain to the prepared seepage erosion soil sample 2 until the soil sample 2 is subjected to shear breaking. The displacement sensor 31 is used for measuring the pressing distance of the pressure loading device, and can be used for monitoring the pressing distance in the process of preparing the soil sample 2 and determining that the applied axial stress reaches a preset value; in the shearing experiment, the axial strain of the soil sample 2 can be estimated through the displacement of the pressure loading device, and the stress-strain response of the soil sample 2 under the drainage shearing condition is analyzed through the axial strain. Specifically, the pressure loading device includes a pressure plate 32 abutting on the upper side of the soil sample 2 and a cylinder 33 driving the pressure rod 34, the pressure plate 32 and the cylinder 33 are connected by the pressure rod 34, and the displacement sensor 31 is connected with the pressure rod 34 to measure the pressing stroke of the pressure loading device.
As shown in fig. 1, in some embodiments of the present invention, the seepage mechanism 5 includes a hydraulic pressure chamber 51 and an air pressure tube 52 for controlling the pressure in the hydraulic pressure chamber 51, one end of the air pressure tube 52 extends into the hydraulic pressure chamber 51, the other end is connected to an air pressure control device such as an air pump, and the air pressure tube 52 increases the air pressure in the hydraulic pressure chamber 51 by air intake, so as to change the pressure applied to the water in the hydraulic pressure chamber 51. The bottom of water pressure storehouse 51 is connected with inlet tube 53, and the up end of soil sample 2 is connected to the other end of inlet tube 53, makes the water pressure in the water pressure storehouse 51 act on soil sample 2 top, adjusts the water pressure in the water pressure storehouse 51 through the intake pipe and can adjust the seepage flow water pressure that the upper surface of soil sample 2 received.
As shown in fig. 2, the method for testing a triaxial soil sample seepage erosion and shear test apparatus according to a preferred embodiment of the present invention, which uses the triaxial soil sample seepage erosion and shear test apparatus according to the above embodiment, includes the following steps:
s01: fixing the soil sample 2 on a fixing mechanism;
s02: applying confining pressure to the periphery of the soil sample 2 through a confining pressure mechanism, and applying upward pressure to the soil sample 2 through a back pressure mechanism 4 to keep the pressure in the soil sample 2 constant;
s03: applying axial stress to the soil sample 2 through the vertical loading mechanism 3 to complete the preparation of the soil sample 2 to be detected;
s04: applying water pressure to the soil sample 2 through the seepage mechanism 5 to enable the soil sample 2 to be subjected to seepage erosion of water flow;
s05: particles falling from the soil sample 2 are collected through the particle collecting mechanism 6, and the particles are detected to obtain a seepage erosion result.
By adopting the steps, the automatic collection of seepage erosion samples and particles of the soil sample 2 under the complex initial stress condition can be realized, and the research on the seepage effect of the soil body inside the foundation facilities such as dams, side slopes and the like under the complex load environment is facilitated.
In some embodiments of the present invention, in S01, after the soil sample 2 is fixed to the fixing mechanism, the first pressure chamber 1 is filled with water and the water is allowed to cover the entire soil sample 2.
In some embodiments of the present invention, in S02, when the confining pressure mechanism applies confining pressure to the periphery of the soil sample 2, the confining pressure valve on the first pressure chamber 1 is activated to pressurize the first pressure chamber 1, so that the water in the first pressure chamber 1 maintains a predetermined confining pressure to the periphery of the soil sample 2.
In some embodiments of the present invention, in S02, the backpressure valve 42 is opened at the same time as the confining pressure is applied, and a backpressure corresponding to the confining pressure is applied to the bottom of the soil sample 2, so as to ensure that the soil sample 2 is internally saturated and the external confining pressure is stable, and the actual confining pressure of the soil sample 2 is the external confining pressure minus the internal backpressure.
In some embodiments of the present invention, in S03, when the vertical loading mechanism 3 applies an axial displacement to the soil sample 2, the air cylinder 33 drives the pressing plate 32 to move downward, the pressing plate 32 applies an axial stress to the soil, and during the pressing of the pressing plate 32, the displacement sensor 31 records the stroke of the pressing rod 34 for monitoring the pressing distance and determining that the applied axial stress reaches a preset value.
In some embodiments of the present invention, when water pressure is applied to the soil sample 2 by the seepage mechanism 5 in S04, water exceeding 2/3 is injected into the hydraulic pressure chamber 51 and beatenThe air pressure pipe 52 is opened, and the pressure of the air inlet pipe is controlled to enable the water pressure in the water pressure chamber 51 to reach u0The water pressure bin 51 is connected with the top of the soil sample 2 through a water inlet pipe 53, so that the water pressure at the top of the soil sample 2 can reach u0(ii) a The pore pressure at the bottom of the soil sample 2 is controlled by the backpressure valve 42, the backpressure valve 42 can be closed in the seepage erosion process, the water level of the water collecting tank 63 is kept constant, and the pore pressure at the bottom of the soil sample 2 can be constant and is u1The difference between the water pressures of the upper and lower boundaries (u ═ u) of the soil sample 20-u1) The process of seepage and particle erosion in soil is realized under the action of the water. Further, the counter-pressure valve 42 can be opened in the process to adjust the pressure inside the soil sample 2 in real time during the seepage process.
Compared with the steps of the test method of the triaxial soil sample seepage erosion and shear test device in the embodiment, the test method of the triaxial soil sample seepage erosion and shear test device in the preferred embodiment of the invention further comprises the following steps: and S06, after the water pressure is applied to the soil sample 2 to enable the soil sample 2 to be subjected to seepage erosion of water flow, continuously applying axial pressure to the soil sample 2 through the vertical loading mechanism, and monitoring the axial deformation of the soil sample 2 through the displacement sensor 31 until the soil sample 2 is subjected to shear failure.
By adopting the steps, the independent triaxial shear test of the triaxial loading system is realized, and the triaxial shear test is used for researching the triaxial drainage mechanical response, the triaxial non-drainage mechanical response and the triaxial mechanical response of the soil sample 2 after seepage erosion under the cyclic loading condition.
In some embodiments of the present invention, before S06, i.e. before the shear test is performed, the funnel valve 14 is closed, and the pressure in the first pressure chamber 1 and the sample is reduced to correspond to the seepage pressure of the hydraulic pressure chamber 51 until the back pressure drop in the sample is zero, and the sample is consolidated again until the confining pressure is stabilized, and then the shear test is performed.
In some embodiments of the present invention, in S06, when the shear test is performed, the gate of the drain valve 43 is opened, and the shear test of triaxial soil sample seepage erosion during the draining process can be performed; after the shear test is finished, test data in the shearing process of the soil sample 2 are analyzed, wherein the test data comprise radial stress (confining pressure), axial stress, axial strain (measured by a displacement sensor 31) and body strain (measured by a drainage volume), and the stress-strain response of the soil sample 2 under the drainage shearing condition is analyzed.
In some embodiments of the present invention, in S06, the drain valve 43 is closed when the shear test is performed, and the shear test of triaxial soil sample seepage erosion in the case of no drainage can be performed. After the shear test is finished, test data in the shearing process of the soil sample 2 are analyzed, wherein the test data comprise radial stress (confining pressure), axial stress and axial strain (measured by a displacement sensor 31), and the stress-strain response of the soil sample 2 under the drainage shearing condition is analyzed.
To sum up, the embodiment of the present invention provides a triaxial soil sample seepage erosion detection apparatus, a test method thereof, and a shear test method thereof, which have the following advantages:
(1) compared with the existing triaxial test equipment, the seepage mechanism 5 and the particle collecting mechanism 6 are introduced, so that a seepage erosion sample of the soil sample 2 under a complex initial stress condition can be realized, and the change of triaxial mechanical properties of the soil sample 2 before and after seepage erosion can be further researched. Meanwhile, the invention has the advantages of the traditional triaxial test equipment and can realize the preparation of loading samples with different consolidation confining pressures and initial stress ratios. It is worth mentioning that the particle collection mechanism 6 of the present invention introduces the back pressure mechanism 4, which can ensure the constant average pore water pressure inside the sample in the seepage erosion process, and avoid the problems of the saturation reduction of the soil sample 2 caused by the reduction of the pore water pressure, etc.
(2) Compared with the existing one-dimensional seepage test equipment, the invention can realize the limited seepage test of the soil sample 2 and simultaneously control the horizontal and vertical stress of the soil sample 2, thereby preparing the soil sample 2 with a complex initial stress state; meanwhile, the invention can realize automatic collection of seepage erosion soil particles and real-time measurement of mass loss in a pressurized environment (applied by a counter-pressure valve 42 of the particle collection mechanism 6), and meets the multifunctional test of the seepage erosion mechanical characteristics of the soil sample 2 under various working conditions.
The above is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.
Claims (10)
1. The utility model provides a triaxial soil sample seepage flow erosion and shear test device which characterized in that includes:
a fixing mechanism for fixing the soil sample;
the confining pressure mechanism acts on the periphery of the soil sample and is used for applying constant pressure to the soil sample in the horizontal direction;
the vertical loading mechanism is arranged above the soil sample and applies downward pressure to the soil sample;
a back pressure mechanism provided below the soil sample, the back pressure mechanism applying an upward pressure to the soil sample;
the seepage mechanism is connected with the soil sample to apply water pressure to the soil sample so as to carry out seepage erosion experiment on the soil sample;
and the particle collecting mechanism is arranged below the fixing mechanism and is used for collecting and weighing the particles falling from the soil sample.
2. The triaxial soil sample seepage erosion and shear test apparatus of claim 1, wherein: the soil sample fixing device comprises a first pressure bin, a fixing mechanism and a soil sample fixing part, wherein the fixing mechanism is arranged in the first pressure bin and comprises a lower fixing part and an upper fixing part, the lower fixing part is connected with the bottom wall of the first pressure bin, the upper fixing part is abutted to the top surface of the soil sample, and the soil sample is arranged between the upper fixing part and the lower fixing part.
3. The triaxial soil sample seepage erosion and shear test apparatus of claim 2, wherein: the confining pressure mechanism comprises confining pressure fluid located in the first pressure bin and a confining pressure valve arranged on the first pressure bin, the confining pressure fluid covers the outer peripheral surface of the soil sample, and the confining pressure valve is used for pressurizing the confining pressure fluid.
4. The triaxial soil sample seepage erosion and shear test apparatus of claim 2, wherein: the bottom in first pressure storehouse is provided with the export, the outside of export is provided with drainage funnel, drainage funnel connects the second pressure storehouse, be provided with in the second pressure storehouse the granule is collected the mechanism, backpressure mechanism set up in order to control the pressure in the second pressure storehouse on the second pressure storehouse.
5. The triaxial soil sample seepage erosion and shear test apparatus of claim 4, wherein: the particle collecting mechanism comprises a collecting seat and a weighing device, the weighing device is fixed on the second pressure bin, and the collecting seat is connected with the weighing device.
6. The triaxial soil sample seepage erosion and shear test apparatus of claim 5, wherein: the collecting seat is characterized in that a water collecting groove is formed in the outer side of the collecting seat and used for maintaining the stability of the water level in the collecting seat, and a drain valve is further arranged at the bottom of the second pressure bin and used for discharging fluid overflowing from the water collecting groove out of the second pressure bin.
7. The triaxial soil sample seepage erosion and shear test apparatus of claim 1, wherein: the vertical loading mechanism comprises a pressure loading device and a displacement sensor, the pressure loading device is abutted to the position right above the soil sample, and the displacement sensor is used for measuring the vertical loading distance of the pressure loading device.
8. The triaxial soil sample seepage erosion and shear test apparatus of claim 1, wherein: the seepage mechanism includes water pressure storehouse and control the atmospheric pressure pipe of the pressure in the water pressure storehouse, the bottom in water pressure storehouse is connected with the inlet tube, the other end of inlet tube is connected the up end of soil sample.
9. A test method of a triaxial soil sample seepage erosion and shear test device, which adopts the triaxial soil sample seepage erosion and shear test device of any one of claims 1 to 8, and is characterized by comprising the following steps:
fixing the soil sample to the fixing mechanism;
applying confining pressure to the periphery of the soil sample through the confining pressure mechanism, and applying constant pressure to the soil sample through the back pressure mechanism to keep the pressure in the soil sample constant;
applying axial stress to the soil sample through the vertical loading mechanism to complete the preparation of the soil sample to be detected;
applying water pressure to the soil sample through the seepage mechanism to enable the soil sample to be subjected to seepage erosion of water flow;
and collecting particles falling from the soil sample through the particle collecting mechanism, and detecting the particles to obtain a seepage erosion result.
10. The method of testing the triaxial soil sample seepage erosion and shear test apparatus of claim 9, further comprising the steps of: after the water pressure is applied to the soil sample, so that the soil sample is subjected to seepage erosion of water flow, the ambient pressure of the first pressure bin is kept constant, the vertical loading mechanism continues to apply pressure to the soil sample in the axial direction, and the displacement sensor monitors the axial deformation of the soil sample until the soil sample is subjected to shear failure.
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