CN106124386A - A kind of undisturbed soil effecive porosity analyzer - Google Patents

Abstract

The invention relates to an instrument for measuring effective porosity of undisturbed soil, which includes a water supply tank, a water head adjustment assembly, a seepage unit, a liquid equalization unit and a detection unit. The water supply unit is connected with the seepage unit through the liquid equalization unit; The effective porosity tester can measure the effective porosity of rock and soil, and the effective porosity of the original soil sample can be obtained by the solute replacement method, and the seepage unit can be used for sampling the original soil sample at the same time; The process is simple, the measurement accuracy of effective porosity is high, and it has good application potential. In hydrogeological research, it can be used as a laboratory teaching instrument to help students understand the difference between effective porosity and total porosity; it can be used for determination in actual production The effective porosity of the sample provides a parameter determination experimental device for further research on solute migration, such as seawater infiltration, leakage recharge, phreatic migration, and groundwater in-situ restoration.

Description

A Measuring Instrument for Effective Porosity of Undisturbed Soil

technical field

The invention relates to a rock and soil parameter measuring instrument, in particular to an undisturbed soil effective porosity measuring instrument, which belongs to the technical field of hydrogeological experiment devices.

Background technique

Groundwater retention, The groundwater retention, release, and transport capabilities are mainly affected by the effective porosity of rock and soil. Therefore, the effective porosity not only directly affects the accuracy of calculation and research results, but also affects other hydrogeological parameters. Make forecast estimates. With the continuous development and utilization of groundwater resources, people began to explore the quantitative relationship between effective porosity and groundwater migration rate.

The effective porosity of rock and soil is the ratio of the pore volume where gravity water flows (excluding the space occupied by disconnected dead pores and immobile bound water) to the rock volume (including pore volume). The effective porosity of rock and soil is represented by _ne , which is an important hydrogeological parameter. At present, the device for measuring effective porosity can only be used on samples such as low-permeability rocks and fermented grains in wine tanks, such as CN103674804A and CN102141502A published by Chinese patents, which measure effective porosity for low-permeability rocks and fermented grains in wine tanks respectively It is suitable for the determination of effective porosity of loose rock and soil.

To sum up, the current effective porosity measuring devices can only measure low-permeability rocks and fluffy materials such as wine tank unstrained spirits, and there is a lack of an effective porosity measuring instrument that can measure loose rock and soil.

Contents of the invention

The purpose of the present invention is to solve the problems in the prior art and provide a measuring instrument capable of measuring the effective porosity of loose rock and soil.

The technical solution adopted to realize the object of the present invention is an instrument for measuring the effective porosity of undisturbed soil, at least including a water supply unit, a seepage unit and a detection unit, the water supply unit is connected with the seepage unit, and the water supply unit includes a water supply tank and a water head adjustment assembly , the water head adjustment assembly is a height adjustment assembly, the water supply tank is fixed on the water head adjustment assembly, the water supply tank is provided with an overflow plate lower than the height of the water supply tank, the water supply tank is divided into a water supply cavity and an overflow cavity by the overflow plate, and the water supply tank A water supply port and a water inlet connected to the water supply chamber and a drain port connected to the overflow chamber are provided on the top, and the water supply tank communicates with the seepage unit through the water supply pipe installed on the water supply port; the water outlet end of the water supply pipe is provided with a liquid equalizing unit, The liquid equalizing unit is located on the seepage unit, and the liquid equalizing unit includes an overflow pipe and a liquid distributor connected to each other, and the water outlet of the water supply pipe is located at the center of the upper part of the liquid distributor, and the liquid distributor is composed of the original column seepage plate, The fixed tube is composed of more than one sieve plate. The original column seepage plate and each sieve plate are sequentially distributed in the fixed tube from bottom to top. The original column seepage plate and sieve plate are both orifice plates. The hole distribution density is not the same, and the overflow pipe is connected between the seepage plate of the original column and the sieve plate at the bottom; the seepage unit includes the original column, the sealing seat, the bottom filter plate and the support assembly, and the liquid divider is located at the top of the original column And communicate with the original column, the original column is fixed in the support assembly, the sealing seat is connected with the lower end of the original column, and the original column is closed, the bottom filter plate is located under the original column and fixed in the sealing seat, the bottom filter plate and the sealing seat constitute the detection chamber , the original column is composed of more than one hollow column, the end of the hollow column is a wedge-shaped convex edge or a wedge-shaped groove matching the wedge-shaped convex edge, the top surface of the hollow column at the top is a plane, and the upper end of the sealing seat is Wedge-shaped groove or wedge-shaped convex edge, the sealing seat and the original column are fastened and connected with the wedge-shaped convex edge through the wedge-shaped groove; the detection unit includes a display, a flow meter and more than one resistivity sensor, and the flow meter is fixed by the sealing seat and connected to the The detection cavity is communicated, the resistivity sensor is located in the detection cavity, and the display is located outside the detection cavity and is electrically connected to the resistivity sensor through wires.

The height adjustment assembly includes a base, a sliding column, a water tank support and a sliding adjuster, the sliding column is fixed on the base, the sliding column is provided with buckles along the axial direction, the sliding adjuster is sleeved on the sliding column and is limited by the buckle position, the water tank support is fixed on the slide regulator.

The buckle is a position-limiting protrusion, and the sliding adjuster is composed of a lifting rocker, a sliding sleeve and a fixed sleeve. The fixing sleeve is threadedly connected to the lower part of the sliding sleeve. One of the ends is a round pipe, which is fitted on the pin shaft and fits with the pin shaft. The other end of the lifting handle protrudes from the sliding sleeve, and the outer surface of the round pipe and the inner surface of the lower part of the sliding sleeve are provided with limiting protrusions. rise.

The middle part of the water supply tank is provided with a partition plate, and the water supply tank is divided into two identical inner cavities by the partition plate, and overflow plates are provided in the two inner cavities, and water supply ports are provided on the water supply ports of the two inner cavities. The other ends of the two water supply pipes are connected to a liquid equalizing unit, one of which is connected to the original column, and the water inlets of the two inner chambers are equipped with water inlets, and the drains are equipped with drains. The drain pipe is connected to the water inlet pipe through the three-way interface, and the water inlet pipe is located on the pipe section between the three-way interface and the water inlet, and a water pump is installed.

The liquid flow divider is composed of a fixed pipe and the first sieve plate, the second sieve plate, the third sieve plate and the original column percolation plate fixed in the fixed pipe from top to bottom, the first sieve plate and the second sieve plate Water-retaining areas are provided in the seepage areas, and the water-retaining areas are located at the center or edge of the sieve plate.

The vertical distance between the third sieve plate and the seepage plate of the original column is 1 cm, and the overflow pipe is connected to 0.5 cm above the seepage plate of the original column.

The support assembly includes a support plate, a support column, a fixing ring and a support fixture, the support column is installed on the support plate, the fixing ring is sleeved on the original column and is located at the joint of the hollow column, and the support fixture is sleeved on the support column, The retaining ring and support anchor are connected by threaded fasteners.

Both the fixing ring and the supporting fixture are composed of two ear-shaped semi-circular rings connected by threaded fasteners, and the threaded fasteners are located at the ears of the ear-shaped semi-circular rings.

The bottom of the sealing seat is provided with a flow measurement tube communicating with the detection cavity, and the flow meter is fixed in the flow measurement tube.

Three resistivity sensors are fixed in the detection chamber, and the three resistivity sensors are evenly distributed along the circumferential direction of the sealing seat.

It can be seen from the above technical solution that the undisturbed soil effective porosity tester provided by the present invention has a main body including a water supply unit, a seepage unit, a liquid equalization unit and a detection unit, wherein 1, the water supply unit is used to provide seepage water, and the water supply unit includes a water supply unit Tank and water head adjustment components, through which the position and head of water in the water supply tank can be adjusted, the water supply tank is provided with an overflow plate, and the water supply tank is divided into a water supply chamber and an overflow chamber by the overflow plate, so as to realize constant water head control; 2. Seepage The unit includes the undisturbed column, sealing seat, bottom filter plate and support assembly. The undisturbed column is the sampling and seepage place of the undisturbed soil sample. The undisturbed column is composed of more than one hollow column. The end of the hollow column is a wedge-shaped convex edge or The wedge-shaped groove matched with the wedge-shaped convex edge. When sampling, insert the wedge-shaped convex edge of the hollow column into the soil, and use a hammer to hammer the wedge-shaped groove end of the hollow column. When the highest point of the soil sample at the sampling point reaches the wedge-shaped groove end , take out the hollow column as a whole, if the undisturbed soil sample length is longer, when the highest point of the soil sample at the sampling point reaches the end of the wedge-shaped groove, insert the wedge-shaped convex edge of the next hollow column into the wedge-shaped groove of the previous hollow column Repeated hammering, all hollow columns are inserted in turn and taken out as a whole. On-site sampling will not destroy the original internal void structure of the undisturbed soil, ensuring the validity of the test results. The original column is also the seepage site of the undisturbed soil sample, and the sealing seat It is connected with the lower end of the original column to close the original column, and the bottom filter plate is fixed in the sealing seat to form a detection chamber. The seepage water of the undisturbed soil sample is filtered by the bottom filter plate and then converges in the detection chamber; 3. The liquid equalizing unit is used to The water body is evenly divided, including interconnected overflow pipes and liquid diverters. The liquid diverter is composed of the original column seepage plate, fixed pipe and more than one sieve plate. The original column seepage plate and each sieve plate are horizontally installed on the fixed pipe from bottom to top Among them, by setting the pore diameter and hole distribution density of the original column seepage plate and the sieve plate to be different, the flow velocity of the water flow between the original column seepage plate and each sieve plate is changed, and the water flow is evenly distributed through the densely distributed holes, ensuring that the water body is surface 4. The detection unit is used to detect the flow rate and ion concentration of seepage water.

In the undisturbed soil effective porosity measuring instrument provided by the present invention, the water head adjustment component adopts the structure of shaking up and buckling limit, and the height adjustment component includes a base, a sliding column, a water tank support and a sliding regulator, and the sliding column is buckled. The sliding adjuster is set on the sliding column and is limited by the buckle. The sliding adjuster is composed of a lifting handle, a sliding sleeve and a fixed sleeve. The lifting handle can swing up and down relative to the sliding sleeve. Since the lifting handle is close to the end surface of the sliding column The buckle is also set, and the process of lifting and shaking the hand is equivalent to the process of buckle engagement. After adjusting to a suitable position, the sliding sleeve is locked by the fixing sleeve. The mechanism is simple in structure, easy to adjust and stable in position.

The water supply tank is arranged as a left-right symmetrical structure, and the interior is divided into two identical inner cavities by a partition plate, one of which is used for seepage water supply, and the other is a spare cavity. Both inner cavities are connected with water supply pipes, and the other of the water supply pipes One end is connected to the liquid equalizing unit. When the seepage liquid needs to be replaced, the original liquid equalizing unit is directly removed, and the other liquid equalizing unit is placed on the top of the original column, and the seepage can continue after being sealed with a sealant; each The inner chamber is divided into a water supply chamber and an overflow chamber by an overflow plate, and the drain pipe is connected to the water inlet pipe through a tee joint, and the water discharged from the drain pipe is pumped into the water supply chamber again through a water pump.

In order to further optimize the liquid diversion effect, the designed liquid diverter is composed of a fixed pipe and the first sieve plate, the second sieve plate, the third sieve plate and the original column seepage plate installed horizontally in the fixed pipe from top to bottom. Both the plate and the second sieve plate are designed to have a water seepage area and a water retaining area. The water retaining area is located at the center or edge of the sieve plate. The position of the water retaining area of the first sieve plate and the second sieve plate is different, which is used to change the water flow. Flow direction, weakening the flow rate of water, when the water body enters, it will be evenly diverted through the seepage area of the first sieve plate, and the water body will be filled between the first sieve plate and the second sieve plate, and the liquid will flow into the second sieve plate and the second sieve plate evenly through the small round hole The gap between the third sieve plates, and then through the third sieve plate to divide the water body evenly again, through the dense small round holes of the original column seepage plate to make the water infiltrate evenly, and pass through the first sieve plate, the second sieve plate, and the third sieve plate 1. The seepage plate of the original column divides the water evenly to ensure that the water infiltrates into the original column in a planar manner. The third sieve plate is separated from the seepage plate of the original column by 1 cm. The overflow pipe is connected to the 0.5 cm above the seepage plate of the original column. A thin water layer of 0.5 cm is maintained on the top of the seepage plate to infiltrate the sample.

In the undisturbed soil effective porosity measuring instrument provided by the present invention, the original column is a detachable structure, so the support assembly of the original column is required to adapt to the detachable structure. The support assembly includes a support plate, a support column, a fixed ring and a support fixer, and The column is installed on the support plate to form an overall support support. The fixing ring is set on the original column, and the support fixer is set on the support column. The fixing ring and the support fixer are connected by threaded fasteners to realize the fixation of the original column. The disassembly and assembly of the fixed ring and the supporting fixture are both designed as a structure composed of two ear-shaped semi-circular rings connected by threaded fasteners. The supporting fixture is located at the joint of the hollow column, and at the same time plays an auxiliary sealing effect.

The measuring instrument of the present invention has simple structure, simple and convenient measuring process, high measuring precision of effective porosity, and good application potential. In hydrogeological research, it can be used as a laboratory teaching instrument to help students understand the difference between effective porosity and total porosity The difference; in actual production, it can be used to measure the effective porosity of the sample, and provide an experimental device for parameter determination for further research on solute migration, such as seawater infiltration, leakage recharge, diving migration, and groundwater in-situ restoration.

Compared with the prior art, the undisturbed soil effective porosity measuring instrument provided by the invention has the following advantages:

(1) It can realize the effective porosity measurement of loose undisturbed rock and soil, which is simple and convenient;

(2) It can quickly replace the displacement liquid, and keep the outlet water head and infiltration water head the same;

(3) By using the sensor, the relationship between concentration and time can be accurately obtained to ensure the accuracy of the experiment.

Description of drawings

Fig. 1 is a structural schematic diagram of an undisturbed soil effective porosity measuring instrument provided by the present invention.

Figure 2 is a schematic diagram of the structure of the slide regulator.

Fig. 3 is a schematic structural diagram of a liquid splitter.

Fig. 4 is a structural schematic diagram of the support assembly.

Among them, 1-base, 2-reinforcing plate, 3-water supply tank, 4-sliding column, 5-clip, 6-inlet pipe, 7-tee interface, 8-drainage pipe, 9-micro water pump, 10-water tank Support, 11-water supply port, 12-sliding regulator, 13-overflow plate, 14-partition plate, 15-water inlet, 16-drainage port, 17-water supply pipe, 18-sealing seat, 19-liquid diverter , 20-overflow pipe, 21-original column, 22-supporting fixture, 23-flow measuring tube, 24-fixing ring, 25-threaded fastener, 26-supporting column, 27-bottom filter plate, 28-resistivity Sensor, 29-support plate, 30-wire, 31-display, 32-glass rotameter, 33-lifting shaker, 34-sliding sleeve, 35-fixing sleeve, 36-pin shaft, 37-fixing pipe, 38- The first sieve plate, 39-the second sieve plate, 40-the original column seepage plate, 41-the third sieve plate, 42-seepage area, 43-water retaining area, 44-ear-shaped semicircle.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments, and the content of the present invention is not limited to the following embodiments.

The undisturbed soil effective porosity measuring instrument provided by the present invention has a structure as shown in Figure 1, including a water supply unit, a seepage unit, a liquid equalization unit and a detection unit, and the water supply unit communicates with the seepage unit through the liquid equalization unit;

The water supply unit includes a water supply tank 3 and a water head adjustment assembly, the water supply tank is fixed on the water head adjustment assembly, the water supply tank is made of 3mm thick plexiglass plates, and the specification is 22cm*20cm*10cm. There is a partition plate 14, and the water supply tank is divided into two identical inner chambers by the partition board, and the overflow board 13 lower than the height of the water supply tank is arranged in the two inner chambers, and the two inner chambers are separated into two chambers by the overflow board. Water supply chamber and overflow chamber, the water supply tank is provided with a water supply port 11 and a water inlet 15 connected with the water supply chamber and a drain port 16 connected with the overflow chamber, and the water supply tank is evenly distributed with the liquid through the water supply pipe 17 installed on the water supply port The units are connected, and the water inlets 15 of the two inner cavities are equipped with water inlet pipes 6, and the water outlets 16 are equipped with drain pipes 8. The drain pipes are connected to the water inlet pipes through the three-way interface 7, and are located between the three-way interface and the water inlet. A micro water pump 9 is installed on the water inlet pipe 6, and the micro water pump 9 pumps the water body into the water supply chamber. When the water level in the water supply chamber is higher than the overflow plate 13, the excess water flows into the overflow chamber, and is connected with the water supply tank through the drain port 16. The drain pipe 8 is discharged, and the drain pipe 8 is connected with the water inlet pipe 6 through the three-way interface 7, so that the discharged water flows into the water inlet pipe 6 for reuse;

The water head adjustment assembly is a height adjustment assembly, and the height adjustment assembly includes a base 1, a reinforcement plate 2, a sliding column 4, a water tank support 10 and a sliding regulator 12, the base 1 is a square iron plate with a side length of 15 cm, and the center of the square There is a round hole with a diameter of 3 cm, and the iron circular sliding column 4 is inserted into the round hole of the base 1. One end of two iron strip-shaped reinforcement plates 2 is hinged on the base, and the other ends are hinged on the bottom of the sliding column 4. The upper edge of the sliding column A buckle 5 is provided in the axial direction, and the buckle is a limit protrusion with an extension length of 0.2 cm. The distance between the buckle 5 is 1 cm. The sliding regulator 12 is set on the sliding column and is limited by the buckle. On the sliding regulator, the material of the water tank support 10 is a plexiglass plate, and the specification is 22cm*20cm*1cm. Referring to FIG. It is made of plastic, the upper part is a cuboid of 8*8*3cm, the middle part of the cuboid has a round hole with a diameter of 3.2cm, so as to be inserted into the sliding column 4, the upper part is bonded to the water tank support 10, and a pin with a diameter of 0.5cm is welded in the cuboid of the sliding sleeve One end of the shaft 36 and the lifting handle 33 is a round tube with a diameter of 0.6 cm, and the round tube is sleeved on the pin shaft, and the outer surface of the round tube is also provided with a spacing of 1 cm and an extension length of 0.2 cm. Limiting protrusions (buckles) The lifting handle 33 is inserted into the cuboid of the sliding sleeve 34, and can rock up and down around the pin shaft 36. The buckle 5 drives the sliding sleeve 34 to lift, and the sliding sleeve 34 then drives the water tank support 10 to lift. The lower part of the sliding sleeve 34 is an upper diameter of 4 cm, Hollow circular table with a lower diameter of 3.5 cm, the hollow circular table is welded on the lower part of the cuboid, the inner wall of the hollow circular table is also provided with buckles 5, the outer wall has threads, and more than two vertical cracks are provided on the side arm of the hollow circular table; the fixed sleeve 35 is the inner diameter 3.6cm, outer diameter 4.0cm, high 1cm circular ring, the inner wall has the thread with the same pitch as the outer wall of the hollow circular platform, when the sliding sleeve 34 drives the water tank support 10 to a certain height, the fixed sleeve 35 is screwed on the sliding sleeve 34 outside the lower hollow round table, the buckle 5 on the inner wall of the hollow round table and the buckle 5 on the outer wall of the sliding column 4 are engaged with each other to achieve a fixing effect;

There are two sets of liquid equalizing units, which are convenient for liquid conversion, and can ensure that the water inlet head from the water supply tank 3 to the liquid diverter 19 remains unchanged when converting the liquid; the liquid equalizing unit is connected to the water outlet of the water supply pipe 17, and the liquid The equalizing unit includes an interconnected overflow pipe 20 and a liquid diverter 19. The water outlet of the water supply pipe 17 is located at the center of the upper part of the liquid diverter. The liquid diverter 19 is cylindrical, and the whole is made of organic glass tubes. The device 19 can be placed on the percolation unit without reinforcement, which is convenient for two liquid flow dividers 19 to be quickly replaced. Referring to Fig. The first sieve plate 38, the second sieve plate 39, the third sieve plate 41 and the original column percolation plate 40 constitute, the first sieve plate 38 and the second sieve plate 39 are circular plexiglass plates with a diameter of 22 cm, passing through a diameter of 22cm, height is that 0.5cm cylindrical plexiglass tube (fixed pipe 37 tops) links to each other, and the diameter of the third sieve plate 41 and the original original column percolation plate 40 is 20cm, is 20cm by diameter, and height is 3cm cylindrical plexiglass tube ( The lower part of the fixed pipe 37) is connected, the small round holes of two adjacent sieve plates are arranged in a staggered manner, the distance between the third sieve plate and the seepage plate of the original column is 1 cm, and the overflow pipe 20 is connected to the place 0.5 cm above the seepage plate of the original column. The water pipe 20 leads out the water body that has not infiltrated in time, and maintains a 0.5cm thin water layer infiltration sample on the top of the original column seepage plate 40, and the first sieve plate 38 center diameter has a 1cm impermeable small circular plate (i.e. the water retaining area 43) 1cm from the small circular plate to the edge of the liquid diverter 19 (the 1cm edge of the first sieve plate 38 is also a water-retaining area) and is filled with a small circular hole with a diameter of 0.4cm. This area is the seepage area 42, and the center of each small circular hole 0.8cm apart, each row of small round holes are arranged in a staggered manner; within 2cm of the edge of the second sieve plate 39 (2cm of the edge of the second sieve plate 39 is also a water retaining area) as a whole, there are small round holes with a diameter of 0.4cm. The centers of the round holes are 0.8cm apart, and the small round holes in each row are arranged in a staggered manner; the third sieve plate 41 has small round holes with a diameter of 0.3cm as a whole, and the centers of each small round hole are 0.6cm apart, and the small round holes in each row are arranged in a staggered manner ; The original column seepage plate 40 has 0.3cm small round holes as a whole, the center of each small round hole is 0.45cm apart, and each column of small round holes is arranged in a staggered manner;

Described percolation unit comprises original shape column 21, seal seat 18, bottom filter plate 27 and support assembly, and liquid divider 19 is positioned at the top of original shape column and is communicated with original shape column, and original shape column is fixed in support assembly, and seal seat 18 is by high 2cm The iron ring is welded with a circular iron plate with a diameter of 20 cm and a thickness of 1 cm. The sealing seat 18 is connected to the lower end of the original column to seal the original column. The circular iron plate at the bottom of the sealing seat is provided with a flow measuring tube communicating with the detection chamber. 23. The flowmeter is fixed in the flow measuring tube. The bottom filter plate 27 is an iron sieve plate with a diameter of 20cm. The sieve hole diameter is 0.4cm. The center of each sieve hole is 0.8cm apart. The bottom filter plate 27 is welded and fixed in the sealing seat To form a detection chamber, the original column is composed of three iron hollow columns with an inner diameter of 20cm, an outer diameter of 22cm, and a height of 30cm. The sharp angle of the convex edge is 45°, the top of the hollow column and the lower hollow column is a wedge-shaped groove matching the wedge-shaped convex edge, the bottom end is a wedge-shaped convex edge, and the upper end of the sealing seat is a wedge-shaped groove. When connecting, the wedge-shaped convex Insert the edge into the wedge-shaped groove and apply sealant on the junction to prevent water leakage;

Described support assembly comprises support plate 29, support column 26, fixed ring 24 and support fixture 22, support plate 29 is the elongated iron plate of 20cm*5cm*1cm, and support column 26 is long 70cm, diameter 3cm round iron column , the lower part of the support column 26 is welded on the support plate 29, and the fixed ring 24 is fixed at the junction of the hollow original column 21, referring to Fig. The ear-shaped semi-circular ring 44 has a radius of 11 cm and a height of 3 cm, which can tightly fix the hollow original column 21. The two sides of the ear-shaped semi-circular ring 44 are provided with screw holes with diameters of 1 cm and 0.5 cm in turn, of which the diameter is 1 cm. One on one side, two on one side of the 0.5cm screw hole, the fixed ring 24 and the original post 21 are fixed by threaded fasteners 25 at the ears on the original post 21 both sides, and the supporting fixture 22 is 1.5cm by two radiuses, It consists of ear-shaped semi-circular rings with a height of 3 cm, and two screw holes with a diameter of 0.5 cm are respectively opened on the ears on both sides. fixed;

The detection unit includes a display 31, a glass rotameter 32 and three resistivity sensors 28, the glass rotameter 32 is fixed in the flow measuring tube 23 and communicates with the detection chamber, the three resistivity sensors 28 are located in the detection chamber and Evenly distributed along the circumferential direction of the sealing seat, the display is located outside the detection chamber and is electrically connected to the resistivity sensor through a wire 30 .

The operating principle of the undisturbed soil effective porosity measuring instrument provided by the invention is as follows:

The resistivity R measured by the resistivity sensor, according to the relationship curve between the resistivity R and the displacement fluid concentration C, the change curve of the displacement fluid concentration C and the time T is obtained, and the effective porosity of sandy soil and clay ( Φ) Calculation formula.

(1) Determination of the effective porosity of undisturbed soil (absorptive):

$\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; V</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0.5</span>}}$

In the formula: Φ—the effective porosity of the sample, %;

V——Darcy flow rate of displacement fluid, cm/min;

L——sample height, which is also the displacement path of displacement fluid, cm;

T _0.5 ——the time when the concentration of the displacement fluid is half of its original concentration when it flows out, min;

According to Darcy's law, there are:

$\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}$

In the formula: Q—displacement fluid flow rate, cm ³ /min;

S - cross-sectional area of the sample, cm ² ;

(2) Determination of the effective porosity of undisturbed soil (absorptive):

From the relationship between the Darcy velocity of the displacement fluid and the pore velocity:

$\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; V</span>}}{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}$

In the formula: U——pore flow velocity, cm/min;

According to the one-dimensional flow-dispersion model, it can be known that:

${\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}{<span\; class="notranslate">\; \&lsqb;</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0.159</span>}}}}{\sqrt{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0.159</span>}}}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0.841</span>}}}}{\sqrt{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0.841</span>}}}}<span\; class="notranslate">\; \&rsqb;</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$

$\mathrm{<span\; class="notranslate">\; \&Phi;</span>}\frac{<span\; class="notranslate">\; \&part;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}{{<span\; class="notranslate">\; \&part;</span>}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}\frac{{<span\; class="notranslate">\; \&part;</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; \&Phi;C</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}{<span\; class="notranslate">\; \&part;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; u</span>}\frac{<span\; class="notranslate">\; \&part;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}{<span\; class="notranslate">\; \&part;</span>\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&Phi;R</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}$

In the formula: D _j —— one-dimensional diffusion coefficient;

C _j - ion concentration at the water outlet, mol/L;

R _j ——Ion reduction concentration, mol/L;

x—displacement distance of displacement fluid, cm;

t—displacement time, min;

t _0.841 , t _0.159 —the corresponding time when the displacement fluid concentration is 0.841C ₀ and 0.159C ₀ .

The working steps of the undisturbed soil effective porosity measuring instrument provided by the invention are as follows:

1. Collect samples

1.1. Vertical sampling

Clean up the upper part of the soil sample site where the effective porosity needs to be measured, then insert the lower tip of the lower hollow column into the soil, and use a striking object to hammer the top of the lower hollow column. When the highest point of the soil sample at the sampling point reaches the top of the lower hollow column, Insert the tip of the lower end of the hollow column into the concave triangle at the top of the lower hollow column, insert the upper hollow column in turn, stop hammering when the original column is completely submerged in the soil sample, dig out the soil sample around the original column, and expose the entire original column, Apply sealant to the junction of the original column, fix the fixing ring on the original column, and take out the original column at one time;

1.2. Horizontal sampling

Make a vertical section of the soil sample with effective porosity to be measured, insert the lower tip of the lower hollow column into the soil sample horizontally, and hammer the top of the lower hollow column with a hammer, when the highest point of the soil sample at the sampling point reaches the top of the lower hollow column Finally, insert the tip of the lower end of the hollow column into the concave triangle at the top of the lower hollow column, and insert the upper hollow column in turn. When the original column is completely submerged in the soil sample, stop hammering, and dig out the soil sample around the original column to reveal the whole Column, apply sealant to the junction of the original column, fix the fixing ring on the original column, and take out the original column at one time;

1.3. Combined device

Install the original column on the base, fix the connection, place a liquid diverter on the upper part of the original column, apply sealant to the joint between the liquid diverter and the original column to prevent water leakage, check the tightness of the device, adjust the height of the water supply device, and make the permeable water penetrate into the original Soil column;

1.4. Measurement specifications

Measure the cross-sectional area S and sample height L of the original column sample; the resistivity R corresponding to 0.2mol/L sodium chloride and 0.1mol/L sodium chloride;

1.5. Test process

Open the water inlet pipe, draw deionized water into the left inner chamber of the water supply tank, and pump NaCl solution with a concentration of 0.2mol/L into the right inner chamber, and connect the liquid splitter connected to the left inner chamber with the original column to make the deionized The water body infiltrates to the original column. When the lower flow rate and resistivity readings are stable, quickly replace the liquid diverter connected to the left inner chamber with the liquid diverter connected to the left inner chamber for infiltration, and start recording the infiltration time T and resistance in real time at the same time. rate R and flow Q; when the resistivity R corresponding to 0.1mol/L sodium chloride is reached, record the flow Q and cumulative time T _0.5 ; when the resistivity R corresponding to 0.2mol/L sodium chloride is reached, stop the measurement, Record the accumulated time T.

Claims (10)

1. An undisturbed soil effective porosity measuring instrument comprises at least a water supply unit, a seepage unit and a detection unit, the water supply unit is connected with the seepage unit, and it is characterized in that: the water supply unit includes a water supply tank and a water head adjustment assembly, and the water head adjustment The component is a height adjustment component. The water supply tank is fixed on the water head adjustment component. The water supply tank is provided with an overflow plate lower than the height of the water supply tank. The water supply tank is divided into a water supply cavity and an overflow cavity by the overflow plate. The water supply port and the water inlet connected with the overflow chamber and the drain port connected with the overflow chamber, the water supply tank is connected with the seepage unit through the water supply pipe installed on the water supply port; On the seepage unit, the liquid equalizing unit includes an interconnected overflow pipe and a liquid divider, the water outlet of the water supply pipe is located at the center of the upper part of the liquid divider, and the liquid divider consists of the original column seepage plate, a fixed pipe and a piece of The above sieve plate is composed of the original column seepage plate and each sieve plate are distributed in the fixed pipe from bottom to top sequentially. The original column seepage plate and sieve plate are all orifice plates, and the pore diameter and hole distribution density of the original column seepage plate and sieve plate are different. Similarly, the overflow pipe is connected between the original column seepage plate and the sieve plate at the bottom; the seepage unit includes the original column, the sealing seat, the bottom filter plate and the support assembly, and the liquid divider is located at the top of the original column and communicated with the original column , the original column is fixed in the support assembly, the sealing seat is connected to the lower end of the original column, and the original column is closed, the bottom filter plate is located under the original column and fixed in the sealing seat, the bottom filter plate and the sealing seat constitute a detection chamber, and the original column It is composed of more than one hollow column. The end of the hollow column is a wedge-shaped convex edge or a wedge-shaped groove matching the wedge-shaped convex edge. The top surface of the hollow column at the top is a plane, and the upper end of the sealing seat is a wedge-shaped groove or wedge-shaped The convex edge, the sealing seat and the original column are fastened and connected with the wedge-shaped convex edge through the wedge-shaped groove; the detection unit includes a display, a flow meter and more than one resistivity sensor, the flow meter is fixed by the sealing seat and communicated with the detection chamber, and the resistance The resistivity sensor is located in the detection cavity, and the display is located outside the detection cavity and is electrically connected to the resistivity sensor through wires. 2. The undisturbed soil effective porosity measuring instrument according to claim 1, characterized in that: the height adjustment assembly comprises a base, a sliding column, a water tank support and a sliding regulator, the sliding column is fixed on the base, and the sliding column is fixed on the base. A buckle is provided along the axial direction, the sliding adjuster is sleeved on the sliding post and limited by the buckle, and the water tank support is fixed on the sliding adjuster. 3. The undisturbed soil effective porosity measuring instrument according to claim 2, characterized in that: the buckle is a position-limiting protrusion, and the sliding regulator is composed of a lifting handle, a sliding sleeve and a fixed sleeve, and the fixed sleeve is connected to the fixed sleeve. The lower part of the sliding sleeve is threaded, the upper part of the sliding sleeve is provided with a pin shaft, one end of the lifting handle is a round tube, the round tube is sleeved on the pin shaft and fits with the pin shaft, the other end of the lifting handle protrudes from the sliding On the outer surface of the sleeve, the outer surface of the round pipe and the inner surface of the lower part of the sliding sleeve are all provided with limiting protrusions. 4. The undisturbed soil effective porosity measuring instrument according to claim 1, characterized in that: the middle part of the water supply tank is provided with a partition plate, and the water supply tank is divided into two identical inner cavities by the partition plate, and the two There are water overflow plates in each inner cavity, water supply pipes are provided on the water supply ports of the two inner cavities, and the other ends of the two water supply pipes are connected with liquid equalizing units, one of which is connected with the original column, and the two The water inlets of the inner cavities are all provided with water inlet pipes, and the water outlets are all provided with drain pipes. The drain pipes are connected to the water inlet pipes through the three-way interface. 5. The undisturbed soil effective porosity measuring instrument according to claim 1, characterized in that: the liquid flow divider is composed of a fixed pipe and a first sieve plate and a second sieve plate fixed in the fixed pipe in order from top to bottom 1, the third sieve plate and the original column seepage plate, the seepage area of the first sieve plate and the second sieve plate are all provided with a water retaining area, and the water retaining area is located at the center or edge of the sieve plate. 6. The undisturbed soil effective porosity measuring instrument according to claim 5, characterized in that: the vertical distance between the third sieve plate and the original column seepage plate is 1 cm, and the overflow pipe is connected to the top of the original column seepage plate by 0.5 cm place. 7. The undisturbed soil effective porosity measuring instrument according to claim 1, characterized in that: the support assembly comprises a support plate, a support column, a fixed ring and a support fixture, the support column is installed on the support plate, and the fixed ring covers On the original column and at the joint of the hollow column, the supporting fixture is sleeved on the supporting column, and the fixing ring and the supporting fixture are connected by threaded fasteners. 8. The undisturbed soil effective porosity measuring instrument according to claim 7, characterized in that: the fixing ring and the supporting fixture are all composed of two ear-shaped semi-circular rings connected by threaded fasteners, and the threaded fasteners Located on the ear of the ear-shaped semicircle. 9. The undisturbed soil effective porosity measuring instrument according to claim 1, characterized in that: the bottom of the sealing seat is provided with a flow measuring tube communicating with the detection cavity, and the flow meter is fixed in the flow measuring tube. 10. The instrument for measuring effective porosity of undisturbed soil according to claim 1, characterized in that 3 resistivity sensors are fixed in the detection chamber, and the 3 resistivity sensors are evenly distributed along the circumferential direction of the sealing seat.