CN106525682B - A kind of method and experimental provision of in-site detecting deposit vertical hydraulic conductivity - Google Patents
A kind of method and experimental provision of in-site detecting deposit vertical hydraulic conductivity Download PDFInfo
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- CN106525682B CN106525682B CN201610944477.4A CN201610944477A CN106525682B CN 106525682 B CN106525682 B CN 106525682B CN 201610944477 A CN201610944477 A CN 201610944477A CN 106525682 B CN106525682 B CN 106525682B
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- 238000000034 method Methods 0.000 title claims abstract description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 174
- 238000003860 storage Methods 0.000 claims abstract description 85
- 238000007789 sealing Methods 0.000 claims abstract description 19
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 10
- 239000010959 steel Substances 0.000 claims abstract description 10
- 238000012360 testing method Methods 0.000 claims abstract description 9
- 239000013049 sediment Substances 0.000 claims description 111
- 238000002474 experimental method Methods 0.000 claims description 56
- 230000035699 permeability Effects 0.000 claims description 49
- 238000011065 in-situ storage Methods 0.000 claims description 26
- 230000002093 peripheral effect Effects 0.000 claims description 18
- 239000011148 porous material Substances 0.000 claims description 9
- 230000008569 process Effects 0.000 claims description 7
- 230000008859 change Effects 0.000 claims description 5
- 230000003139 buffering effect Effects 0.000 claims description 4
- 239000011521 glass Substances 0.000 claims description 4
- 238000005070 sampling Methods 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims description 2
- 238000012613 in situ experiment Methods 0.000 abstract description 7
- 238000005259 measurement Methods 0.000 abstract description 4
- 238000009434 installation Methods 0.000 abstract description 3
- 238000001764 infiltration Methods 0.000 abstract 1
- 230000008595 infiltration Effects 0.000 abstract 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000013535 sea water Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 3
- 238000012625 in-situ measurement Methods 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 239000002689 soil Substances 0.000 description 3
- 239000004927 clay Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000000691 measurement method Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000003921 particle size analysis Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000009715 pressure infiltration Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/082—Investigating permeability by forcing a fluid through a sample
- G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change
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Abstract
The present invention relates to a kind of experimental provisions of in-site detecting deposit vertical hydraulic conductivity, including：Water storage vertical tube, connecting flange, gasket, steel gauze and deposit vessel；Wherein, water storage vertical tube is located at earth's surface above section, water storage when for testing；Connecting flange, including water storage vertical tube flange and deposit vessel flange, for connecting the water storage vertical tube and the deposit vessel；Gasket is located between two connecting flanges, and the junction for sealing the water storage vertical tube and the deposit vessel prevents leak；Deposit vessel, positioned at earth's surface hereinafter, crossing water for permeating and experimental section being discharged.Meanwhile the present invention also provides the methods for carrying out in-site detecting deposit vertical hydraulic conductivity using this experimental provision.Using in the present invention experimental provision carry out infiltration coefficient measurement, it is applied widely, device installation be simple and convenient to operate, can directly carry out at the scene it is in situ experiment, can quickly, accurately measure deposit vertical hydraulic conductivity.
Description
Technical Field
The invention relates to the technical field of measuring permeability parameters of sediments, in particular to a method and an experimental device for in-situ determination of vertical permeability coefficients of sediments, which are suitable for the technical field of measurement of soil, seawater and the like.
Background
The permeability coefficient is one of the basic characteristic parameters of soil and seawater, and at present, the existing permeability experiment mainly comprises two forms of indoor experiment and field in-situ experiment (also called as field experiment), the indoor experiment mainly comprises a constant water head/variable water head experiment and a particle size analysis method, and the field in-situ experiment mainly comprises a water pumping experiment, a single-ring pressure infiltration instrument, a seepage instrument, a double-ring method and the like. Obviously, laboratory experiments inevitably disturb the deposit, and the measured permeability coefficient is that of the deposit after compaction or shaking. The field in-situ experiment method also has a plurality of defects: the well drilling consumes time and labor, pumps water and consumes power, the cost is high, the operation is inconvenient, the reading error is large, and the like.
Therefore, to improve the accuracy of permeability coefficient measurements, there is a continuing need to improve and upgrade existing measurement techniques and methods.
Disclosure of Invention
The invention aims to provide a device for gas-phase coating aiming at the defects of the prior art and simultaneously provides a novel gas-phase coating method, and the device and the method can realize rapid, quantitative and highly safe and controllable gas-phase coating by using a liquid-phase or gas-liquid composite precursor.
In a first aspect, the present invention provides an experimental apparatus for in-situ determination of vertical permeability coefficient of a deposit, including: the device comprises a water storage vertical pipe 1, a connecting flange 4, a sealing gasket 5, a steel gauze 6 and a sediment containing cavity 7; the water storage vertical pipe 1 is positioned above the ground surface and used for storing water during experiments; the connecting flange 4 comprises a water storage vertical pipe flange and a sediment container flange and is used for connecting the water storage vertical pipe 1 and the sediment cavity 7; the sealing gasket 5 is positioned between the two connecting flanges 4 and is used for sealing the joint of the water storage vertical pipe 1 and the sediment cavity 7 to prevent water leakage; the sediment containing cavity 7 is positioned below the ground surface and used for permeating and discharging the experiment section water.
Preferably, the experimental device further comprises a pressure sensor 2, which is located in a sensor chamber communicated with the bottom of the water storage vertical pipe 1 and used for recording the change of the water level in the water storage vertical pipe 1 along with the time in the experimental process.
Preferably, the experimental facility further comprises a valve 3 located at the bottom of the water storage standpipe 1 for controlling the start and end of the experiment.
Preferably, there are two of said gaskets 5.
Further preferably, the experimental device further comprises the steel gauze 6 which is positioned between the two sealing gaskets 5 and is used for buffering water flow.
Preferably, the bottom edge of the deposit volume 7 has a cutting edge opening.
Preferably, the sediment cavity 7 is provided with an upper section and a lower section, and the upper section is used for permeating the experimental water passing part; the lower half section is provided with a pore for draining water.
In a second aspect, the invention also provides a method for in-situ determination of vertical permeability coefficient of a deposit, comprising the following steps:
s101, selecting a measuring point, and vertically inserting/wedging a sediment containing cavity into a sediment of an experimental field until a sediment containing cavity flange is flush with the surface of the sediment;
s102, sequentially superposing a sealing gasket, a steel gauze and a sealing gasket on the sediment containing cavity flange, aligning the water storage vertical pipe, and fastening the whole device by using screws and nuts;
s103, setting preset starting time and data sampling frequency of the pressure sensor, firstly, opening a sensor cavity, putting the pressure sensor into the sensor cavity, then, closing a valve of a water storage vertical pipe, filling water into the water storage vertical pipe, and finally closing the sensor cavity;
s104, adding in-situ water into the water storage vertical pipe to a preset height;
s105, opening a water storage vertical pipe valve according to preset starting time of the pressure sensor, starting a test, and recording time sequence data of water level changes of the water storage vertical pipe and time sequence data of peripheral water level changes by the pressure sensor according to preset data by adopting frequency;
s106, after the experiment is finished, exporting data in the pressure sensor, and calculating the vertical permeability coefficient of the in-situ sediment of the experimental site according to the obtained data;
s107, repeating experiments S101-S106 at the same position, and performing at least nine groups of experiments.
And S108, removing the maximum value and the minimum value, and taking the average value of the experiments to obtain the final vertical permeability coefficient of the sediment.
Preferably, when a constant head experiment is carried out, the vertical permeability coefficient of the in-situ sediment of the experiment site is calculated according to the following formula:
wherein K is the vertical permeability coefficient of the sediment; hPThe water level height of the water storage vertical pipe is set; hTIs the height of the sea tide; l isVThe length of the working section of the sediment cavity is determined; rdFor the diameter ratio of retaining standpipe and deposit appearance chamber, promptly:dUthe inner diameter of the water storage vertical pipe; dLThe sediment chamber inner diameter.
Preferably, when the variable water head experiment is carried out, the vertical permeability coefficient of the in-situ sediment of the experiment site is calculated according to the following formula:
wherein K is the vertical permeability coefficient of the sediment; a and b are constants; hPThe water level height of the vertical water storage pipe at any time is stored; hTSea tide height, HT(t)＝at+b；LVThe length of the working section of the sediment cavity is determined; rdFor the diameter ratio of retaining standpipe and deposit appearance chamber, promptly:dUthe inner diameter of the water storage vertical pipe; dLThe sediment chamber inner diameter.
Compared with the prior art, the invention has the advantages that: (1) the whole device is convenient to disassemble, transport and install. (2) In the in-situ experiment, the sediment is prevented from being disturbed, and the experiment result is accurate. (3) The application range is wide: range of measurable permeability coefficients 10-7-10-2m/s, coarse sand to fine clay are all available. (4) Short experimental time of 1min<t<The reaction can be completed within 1 h. (5) The method is not only suitable for the condition of peripheral constant water head; but also to the case that the peripheral water level changes with time (sea tide) in the coastal zone area. (6) The appropriate standpipe diameter can be preselected based on the magnitude of the sediment permeability coefficient (empirical value). When the head drops too fast, a smaller standpipe diameter should be selected, and vice versa. (7) In the experiment, a pressure sensor is used for recording the water level and time of the vertical pipe, and the data is read more accurately than the data read by naked eyes.
Drawings
Embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:
FIG. 1 is a schematic perspective view of an experimental apparatus for in-situ measurement of vertical permeability coefficient of sediment according to an embodiment of the present invention;
FIG. 2 is a perspective sectional view of an experiment for in situ determination of vertical permeability coefficient of sediment according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a process for in situ determination of vertical permeability coefficient of a sediment according to an embodiment of the present invention.
Detailed Description
The invention is further illustrated by the following figures and specific examples, but it should be understood that these examples are for the purpose of illustration only and are not to be construed as in any way limiting the present invention, i.e., as in no way limiting its scope.
This section generally describes the materials used in the experiments of the present invention, as well as the methods of testing. Although many materials and methods of operation are known in the art for the purpose of carrying out the invention, the invention is nevertheless described herein in as detail as possible. It will be apparent to those skilled in the art that the materials and methods of operation used in the present invention are well within the skill of the art, provided that they are not specifically illustrated.
FIG. 1 is a schematic perspective view of an experimental apparatus for in-situ measurement of vertical permeability coefficient of sediment according to an embodiment of the present invention; fig. 2 is a perspective cross-sectional view of an experiment for in-situ measurement of vertical permeability coefficient of a sediment according to an embodiment of the present invention. As shown in fig. 1 and 2, the experimental apparatus (also called a standpipe experimental apparatus) includes: the water storage vertical pipe (1), the connecting flange (4), the sealing gasket (5), the steel gauze screen (6) and the sediment containing cavity (7); wherein,
the water storage vertical pipe (1) is located above the ground surface and used for storing water during experiments, and the reference surface of the water storage vertical pipe (1) is the junction of the bottom end of the water storage vertical pipe and the connecting flange (4). Preferably, the water storage vertical pipe (1) is made of organic glass materials, the diameter of the water storage vertical pipe ranges from 0.01 m to 0.1 m, the water storage vertical pipe is selected according to the actual situation of an experimental site, and the proper diameter of the vertical pipe can be pre-selected according to the size (empirical value) of the permeability coefficient of the sediment. When the head drops too fast, a smaller standpipe diameter should be selected, and vice versa. The vertical pipe is preferably 1.5 meters, and in order to conveniently check or record the condition of water falling in the pipe, scale values are marked on the outer side of the vertical pipe. In one example, a valve (3) is further arranged at the bottom of the water storage vertical pipe (1) and used for controlling the start and the end of the experiment, and besides, the valve (3) can also avoid that when water is injected into the water storage vertical pipe (1) in the experiment, too high water flow impacts sediment, and the porosity is disturbed to influence the permeability.
In another example, in order to facilitate the accuracy of recording the water level in the water storage vertical pipe (1) and the experimental time in the experimental process, the experimental device further comprises a pressure sensor (2) which is positioned in a sensor cavity communicated with the bottom of the water storage vertical pipe (1) and used for recording the change of the water level in the water storage vertical pipe (1) along with the time in the experimental process. The application sensor software sets the preset starting time and the data acquisition frequency, and if the sensor is not available, the scale value marked on the outer wall of the water storage vertical pipe (1) can be directly read, and the scale value corresponding to the concave liquid level of the water column in the water storage vertical pipe (1) is recorded in a matching manner. It should be noted that, before the experiment, the software of the pressure sensor (2) is required to set the preset starting time and the data sampling frequency of the pressure sensor (2). Then according to the pressure sensor pre-starting moment, opening the standpipe valve, beginning the experiment, the water level in the retaining standpipe (1) descends gradually fast afterwards slowly, constantly supplies deposit pore water. The pressure sensor (2) may record time series data of standpipe level changes at predetermined time intervals. Meanwhile, time series data of changes of peripheral water level (such as sea tide) are recorded, and other pressure sensors can be arranged on the periphery of the vertical pipe for recording in order to ensure the accuracy of data recording.
The connecting flange (4) comprises a water storage vertical pipe flange and a sediment container flange and is used for connecting the water storage vertical pipe (1) and the sediment container (7), the central axes of the two flanges are perpendicular to the central axes of the water storage vertical pipe (1) and the sediment container (7), screw holes are axially arranged in the corresponding positions of the flanges, and the water storage vertical pipe (1) and the sediment container (7) can be fixed by combining screws and nuts.
The sealing gasket (5) is positioned between the flange of the water storage vertical pipe (1) and the flange of the sediment containing cavity (7), is of an annular structure, is also provided with screw holes corresponding to the flanges, and can well seal the joint of the whole vertical pipe device after screwing the screws and nuts, so that the influence of water leakage on the accuracy of experimental data is prevented. In order to ensure the sealing performance, the sealing gasket (5) has a little elastic plasticity, and is preferably made of silica gel or rubber.
In yet another example, there are two gaskets (5). For buffering rivers, play and avoid the rivers too fast, strike deposit disturbance pore structure's effect, experimental apparatus still includes steel gauze (6), is located the centre of two sealed pads (5), except having the effect of buffering rivers, can also avoid the foreign matter of aquatic to block up the deposit top layer.
The sediment containing cavity (7) is located below the earth surface and is divided into an upper section and a lower section, the upper section is a seepage working part and is used for a water passing part in a seepage experiment, the lower section is provided with uniform pores which are used for removing experiment water and increasing the stability of installing a vertical pipe experiment device, and in one example, a cutting edge opening is formed in the bottom edge of the sediment containing cavity (7) for facilitating the installation of the vertical pipe experiment device.
It should be noted that, preferably, the sediment chamber (7) is made of organic glass, and the diameter thereof is preferably 0.1 meter, and is generally selected to be larger than the diameter of the water storage standpipe (1), and considering the convenience of the experiment operation, the diameter ratio of the water storage standpipe (1) to the sediment chamber (7) is preferably 0.1 to 1.0 diameter. The length of the sediment containing cavity (7) is preferably 0.4 m, the sediment containing cavity is divided into an upper section and a lower section, 0.2m of the upper section is a seepage working part, 2 mm-diameter pores are uniformly distributed on 0.2m of the lower section, the total number of the pores is 20 rows and 36 columns, and the whole sediment containing cavity (7) is communicated with surrounding sediments to play a role in draining and stabilizing the experimental device.
It should be noted that, in the actual experiment process, when the sediment of the selected experiment site is soft, the sediment cavity is vertically inserted/wedged into the experiment site (such as beach, river beach, lake center, etc.); when the sediment is dense, the annular groove (for example, the depth of 0.22 m) is dug around the sediment, so that the sediment cavity is gradually inserted downwards until the flange plane of the cavity is flush with the surface of the sediment. In addition, the annular groove can ensure that water in the water storage vertical pipe is directly communicated with seawater, so that the water head at the bottom of the cavity is consistent with the surrounding water level (such as sea tide).
The vertical pipe experimental device provided by the embodiment of the invention is simple to disassemble, move and install; the operation is convenient, the in-situ experiment can be directly carried out on site, and the vertical permeability coefficient of the sediment can be rapidly and accurately measured; not only the clay from coarse sand to powder can be used, but also the permeability coefficient range is determined to be wide: 10-7-10-2m/s; in addition, the experimental device has wide application range: the method is not only suitable for the condition of peripheral constant water head; but also suitable for the condition that the peripheral water level changes along with the time in the coastal zone area.
FIG. 3 is a schematic diagram of a process for in situ determination of vertical permeability coefficient of a sediment according to an embodiment of the present invention. As shown in fig. 3, taking the measurement of the beach sediment vertical permeability coefficient as an example, the method for measuring the sediment vertical permeability coefficient by using the experimental device provided by the present invention comprises the following steps:
s101, selecting a measuring point, and vertically inserting/wedging the sediment containing cavity into the sediment of the experimental field until the flange of the sediment containing cavity is flush with the surface of the sediment.
Specifically, a relatively flat undisturbed experimental site is selected, and a suitable diameter of the water storage standpipe is selected according to empirical estimation of permeability coefficient of beach sediments. If the water level drops too slowly, a smaller diameter standpipe may be used instead. And vice versa. Considering the convenience of experimental operation, the diameter ratio of the water storage vertical pipe to the sediment cavity is preferably between 0.1 and 1.0.
When the sediment is soft, vertically inserting/wedging the sediment containing cavity into an experimental field; when the sediment is dense, the annular groove (for example, the depth of 0.22 m) is dug around the sediment, so that the sediment cavity is gradually inserted downwards until the flange plane of the cavity is flush with the surface of the sediment. In addition, the annular groove can ensure that water in the water storage vertical pipe is directly communicated with seawater, so that the water head at the bottom of the cavity is consistent with the surrounding water level (such as sea tide).
And S102, sequentially stacking a sealing gasket, a steel gauze and a sealing gasket on the sediment cavity flange, aligning the water storage vertical pipe, and fastening the whole device by using screws and nuts.
S103, setting the preset starting time and the data sampling frequency of the pressure sensor, firstly, opening the sensor cavity, putting the pressure sensor into the sensor cavity, then, closing the valve of the water storage vertical pipe, filling water into the water storage vertical pipe, and finally closing the sensor cavity.
And S104, adding in-situ water into the water storage vertical pipe to a preset height.
Specifically, clean in-situ water is poured into the water storage vertical pipe to a certain height, the difference between the clean in-situ water and the peripheral water level is as large as possible, and the initial water head difference is about 1.2 meters; the initial water column height is preferably such that the water level does not fall too quickly after opening the valve, and the total experimental time is preferably kept between 60 and 3600 seconds. The water head reduction during the whole experiment is preferably 0.2 to 1.2 meters.
It should be noted that, during the experiment of the peripheral constant head, in-situ water is poured into the annular groove, so that a certain head is maintained around the sediment containing cavity, the peripheral water level is recorded, and at the moment, formula calculation under the condition of the peripheral constant head is adopted; when the water level of the groove is changed (reduced) rapidly under the influence of sea tide or the in-situ permeability is good, the formula under the condition of a peripheral variable water head is adopted for calculation.
And S105, opening a water storage vertical pipe valve according to the preset starting time of the pressure sensor, starting the test, and recording time sequence data of water storage vertical pipe water level changes and time sequence data of peripheral water level changes by the pressure sensor according to preset data and frequency.
Specifically, according to the pressure sensor pre-starting moment, open the standpipe valve, begin the experiment, the water level in the retaining standpipe descends gradually fast afterwards slowly, constantly supplies deposit pore water. The pressure sensor may record time series data of standpipe level changes at predetermined time intervals. Meanwhile, time series data of changes of peripheral water level (such as sea tide) are recorded, and other pressure sensors can be arranged on the periphery of the vertical pipe for recording in order to ensure the accuracy of data recording.
And S106, after the experiment is finished, exporting the data in the pressure sensor, and calculating the vertical permeability coefficient of the in-situ sediment of the experimental site according to the obtained data.
Specifically, each group of experiments is finished, the top cover of the sensor cavity is opened, the pressure sensor is taken out, experimental data of the water level of the water storage vertical pipe changing along with time are derived, and the work of the sensor is stopped. Substituting the time sequence data of the constant water head of the peripheral water level or the water level change into a formula (4-6), and solving the vertical permeability coefficients of the in-situ sediments of the experimental sites of different groups by using a least square method.
The relevant formula is derived as follows:
reduction of water volume in water storage standpipe:
water volume throughput in the sediment chamber: (time interval is [ t, t + Deltat ])
From the law of conservation of mass: Δ VP＝ΔVLIs provided with
Obtaining a formula of water level of the water storage vertical pipe at any time under the condition of linear change of the peripheral water head:
when the peripheral head is kept constant (a is 0, b is 0), the above formula is simplified to obtain the formula in the case of the peripheral constant head:
for formula (3), the vertical permeability coefficient of the sediment:
physical quantity:
k is the vertical permeability coefficient of the sediment; dUThe inner diameter of the water storage vertical pipe; dLIs the inner diameter of the sediment containing cavity;
HPthe water level height of the water storage vertical pipe is set; initial head height (t ═ 0): hP(0)＝h0；
HTThe sea tide height is obtained, the sea tide is approximately linearly changed due to short experimental observation time, and the calculation precision is enough; namely: hT(t) ═ at + b, where a and b are constants;
LVsetting the value to be 0.2m for the length of the working section of the sediment cavity;
Rdthe diameter ratio of the water storage vertical pipe to the sediment cavity is set; namely:
and (3) when a constant water head experiment is carried out, calculating the vertical permeability coefficient of the in-situ sediment of the experimental site according to the formulas (5) and (6).
And when the variable water head experiment is carried out, calculating the vertical permeability coefficient of the in-situ sediment of the experiment site according to the formulas (4) and (6).
S107, repeating experiments S101-S106 at the same position, and performing at least nine groups of experiments.
In order to reduce the accidental error, the steps S101-S106 are repeated at the same position, and the experiment frequency is preferably not less than 10.
And S108, removing the maximum value and the minimum value, and taking the average value of the experiments to obtain the final vertical permeability coefficient of the sediment.
After the experiment is finished, the water storage vertical pipe and the sediment containing cavity are detached, the sediment containing cavity is slightly pulled out of soil, and the groove is backfilled; cleaning all the components of the device, and drying and collecting the components for later use.
Compared with the prior art, the experimental device disclosed by the invention is used for measuring the permeability coefficient, is wide in application range, simple in installation and convenient to operate, can be used for directly carrying out in-situ experiment on site, and can be used for quickly and accurately measuring the vertical permeability coefficient of the sediment.
Although the present invention has been described to a certain extent, it is apparent that appropriate changes in the respective conditions may be made without departing from the spirit and scope of the present invention. It is to be understood that the invention is not limited to the described embodiments, but is to be accorded the scope consistent with the claims, including equivalents of each element described.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (6)
1. An experimental device for in-situ determination of vertical permeability coefficient of sediment, comprising: the device comprises a water storage vertical pipe (1), a pressure sensor (2), a valve (3), a connecting flange (4), a sealing gasket (5), a steel gauze screen (6) and a sediment accommodating cavity (7); wherein,
the water storage vertical pipe (1) is positioned above the ground surface and used for storing water during experiments; the water storage vertical pipe (1) is made of organic glass; scale values are marked on the outer side of the water storage vertical pipe;
the pressure sensor (2) is positioned in a sensor cavity communicated with the bottom of the water storage vertical pipe (1) and is used for recording the change of the water level in the water storage vertical pipe (1) along with the time in the experimental process;
the valve (3) is positioned at the bottom of the water storage vertical pipe (1) and is used for controlling the start and the end of an experiment; the valve is also used for avoiding that when water is injected into the water storage vertical pipe (1) in an experiment, overhigh water flow impacts sediments and disturbs a pore structure to influence permeability;
the connecting flange (4) comprises a water storage vertical pipe flange and a sediment container flange and is used for connecting the water storage vertical pipe (1) and the sediment cavity (7);
the sealing gasket (5) is positioned between the two connecting flanges (4) and is used for sealing the joint of the water storage vertical pipe (1) and the sediment accommodating cavity (7) to prevent water leakage;
the steel gauze (6) is positioned between the two sealing gaskets (5) and is used for buffering water flow;
the sediment containing cavity (7) is positioned below the ground surface and used for permeating and discharging the experiment section water;
the sediment containing cavity (7) is made of organic glass and is provided with an upper section and a lower section, and the upper section is used for permeating the experimental water passing part; the lower half section is provided with a pore for draining water;
the diameter ratio of the water storage vertical pipe (1) to the sediment cavity (7) is 0.1-1.0; the diameter of the water storage vertical pipe (1) is smaller than that of the sediment accommodating cavity (7).
2. Laboratory device according to claim 1, characterized in that the number of gaskets (5) is two.
3. Experimental device according to claim 1, characterized in that the bottom edge of the sediment volume (7) has a cutting edge opening.
4. A method for in situ determination of vertical permeability coefficient of a sediment, applied to the apparatus of claim 1, comprising:
s101, selecting a measuring point, and vertically inserting/wedging a sediment containing cavity into a sediment of an experimental field until a sediment containing cavity flange is flush with the surface of the sediment;
s102, sequentially superposing a sealing gasket, a steel gauze and a sealing gasket on the sediment containing cavity flange, aligning the water storage vertical pipe, and fastening the whole device by using screws and nuts;
s103, setting preset starting time and data sampling frequency of the pressure sensor, firstly, opening a sensor cavity, putting the pressure sensor into the sensor cavity, then, closing a valve of a water storage vertical pipe, filling water into the water storage vertical pipe, and finally closing the sensor cavity;
s104, adding in-situ water into the water storage vertical pipe to a preset height;
s105, opening a water storage vertical pipe valve according to preset starting time of the pressure sensor, starting a test, and recording time sequence data of water level changes of the water storage vertical pipe and time sequence data of peripheral water level changes by the pressure sensor according to preset data by adopting frequency;
s106, after the experiment is finished, exporting data in the pressure sensor, and calculating the vertical permeability coefficient of the in-situ sediment of the experimental site according to the obtained data;
s107, repeating the experiments S101-S106 at the same position, and then performing at least nine groups of experiments;
and S108, removing the maximum value and the minimum value, and taking the average value of the experiments to obtain the final vertical permeability coefficient of the sediment.
5. The method of claim 4, wherein when conducting a constant head test, the vertical permeability coefficient of the in-situ deposit at the test site is calculated according to the following formula:
wherein K is the vertical permeability coefficient of the sediment; hPTo storeThe water level height of the water vertical pipe; hTIs the height of the sea tide; l isVThe length of the working section of the sediment cavity is determined; rdFor the diameter ratio of retaining standpipe and deposit appearance chamber, promptly:dUthe inner diameter of the water storage vertical pipe; dLThe sediment chamber inner diameter.
6. The method of claim 4, wherein when performing the variable head test, the vertical permeability coefficient of the in-situ sediment at the test site is calculated according to the following formula:
wherein K is the vertical permeability coefficient of the sediment; a and b are constants; hPThe water level height of the vertical water storage pipe at any time is stored; hTSea tide height, HT(t)＝at+b；LVThe length of the working section of the sediment cavity is determined; rdFor the diameter ratio of retaining standpipe and deposit appearance chamber, promptly:dUthe inner diameter of the water storage vertical pipe; dLThe sediment chamber inner diameter.
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