CN107340333B - Three-dimensional high-power ultrasonic control consolidation test system and method for bubble-containing sludge - Google Patents
Three-dimensional high-power ultrasonic control consolidation test system and method for bubble-containing sludge Download PDFInfo
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Abstract
The invention discloses a three-dimensional high-power ultrasonic control consolidation test system and method for bubble-containing sludge, and relates to an environmental geotechnical engineering test technology. The system comprises a three-dimensional ultrasonic testing unit (10), a testing unit (20) for soil samples containing air bubbles, a pressure chamber unit (30) and a measuring unit (40); the three-dimensional ultrasonic testing unit (10), the testing unit (20) for the soil sample containing air bubbles and the measuring unit (40) are respectively connected with the pressure chamber unit (30). The three-dimensional ultrasonic testing unit (10) is composed of a vertical one-dimensional ultrasonic unit (11) and a radial two-dimensional ultrasonic unit (12). The invention can meet the requirements of applying three-dimensional high-power ultrasonic excitation to the sludge, adjusting the size and concentration of bubbles, and carrying out accurate measurement tests on consolidation deformation, pore pressure, ultrasonic energy attenuation and the like.
Description
Technical Field
The invention relates to an environmental geotechnical engineering test technology, in particular to a three-dimensional high-power ultrasonic control consolidation test system and a method thereof for gas-containing sludge consolidation characteristics under the conditions of different gas bubble sizes and concentrations, different three-dimensional high-power ultrasonic waves and different consolidation pressures.
Background
In order to improve water quality, a port and a wharf are built, a channel and a port pool are widened, large-scale dredging operation is required, and a large amount of sludge is inevitably generated. At present, the treatment of dredging sludge in China is mainly directly abandoned in land dumping and filling areas or low-lying areas, some of the dredging sludge even occupy fishponds and plowed fields, and the ocean dredging also faces the environmental problem caused by deep sea dumping, so most of the dredging sludge is converted into land area dumping. However, the dredged sludge has high water content and low strength, and is difficult to directly develop and utilize. Secondly, the dredged sludge has high clay content and poor water permeability, and can be consolidated in several years or even longer under the action of self weight. Therefore, the water content of the dredged sludge needs to be rapidly reduced, a large amount of water contained in the dredged sludge needs to be rapidly discharged, and the problems that the dredged sludge treatment takes long land occupation time and wastes precious land resources are solved.
In recent years, ultrasonic technology is more and more widely applied to the excitation of sludge dewatering effect by virtue of the advantages of environmental protection, simple and convenient operation, strong practicability and the like. Under the action of high-power ultrasonic waves, micro bubble nuclei in fluid in sludge pores are activated, ultrasonic vibration continuously and rapidly alternates to collapse the cavitation bubble nuclei, local high temperature and high pressure are generated in a very short time, and strong shock waves and jet flows are accompanied, so that migration motion of water and fine particles in the sludge is caused. However, most of the existing indoor sludge consolidation tests are carried out under the condition without ultrasonic waves, and the influence of ultrasonic wave excitation is ignored. Secondly, organic matters in the sludge are extremely easy to spontaneously carry out anaerobic biological reaction during stacking, so that pores in the sludge are saturated by liquid and one or more gases, the gases exist in the pores in the form of small bubbles or large bubbles containing particles, the existence of the bubbles changes the properties of pore fluid and generates coupling action with a framework, and the ultrasonic velocity and energy attenuation are greatly influenced. Although the research on the consolidation characteristics of the saturated sludge has been carried out with certain results due to the development of the sludge consolidation technology, the sludge characteristics obtained by neglecting the influence of the sludge bubbles will be inaccurate and cannot meet the requirements of the actual engineering. Therefore, the research on the consolidation characteristics of the bubble-containing sludge under the excitation of high-power ultrasonic waves has very important application value in the aspects such as solid waste landfill, sewage treatment, river dredging, soft foundation treatment and the like.
In order to research the consolidation characteristics of the sludge containing bubbles under the excitation of high-power ultrasonic waves, conventional indoor consolidation test equipment cannot meet the requirements, and the development of a novel high-power three-dimensional ultrasonic consolidation test system is particularly urgent and important.
The conventional consolidation test equipment is an effective tool for measuring the consolidation deformation of the soil body under the conditions of one-dimensional pressure and three-dimensional pressure, but the conventional consolidation test equipment cannot apply ultrasonic excitation and adjust the size and concentration of bubbles, and cannot meet the test requirement of considering the consolidation characteristics of the bubble-containing sludge under the ultrasonic excitation.
Disclosure of Invention
The invention aims to overcome the defect that the conventional consolidation test equipment cannot consider high-power ultrasonic excitation and bubbles, and provides a high-sensitivity three-dimensional high-power ultrasonic control consolidation test system and method for silt containing bubbles.
The purpose of the invention is realized as follows:
1. three-dimensional high-power ultrasonic control bubble-containing sludge consolidation test system (system for short)
The system comprises a three-dimensional ultrasonic testing unit, a test sheet of a soil sample containing air bubbles, a pressure chamber unit and a measuring unit;
the position and connection relation is as follows:
the three-dimensional ultrasonic testing unit, the testing unit for the soil sample containing the air bubbles and the measuring unit are respectively connected with the pressure chamber unit.
2. Three-dimensional high-power ultrasonic control consolidation test method (method for short) for silt containing bubbles
The method comprises the following steps:
(1) before the formal test, the high-air-intake-value argil plate is saturated by adopting an air-exhaust saturation method until no air bubbles exist;
(2) naturally drying the sludge sample under a cool and shady condition, and adding the airless water into the sludge air-dried sample;
(3) putting the sludge sample after the water-free filling into a two-dimensional ultrasonic transducer for filling soil samples in layers, tamping each layer for the same times to ensure the integral uniformity of the soil sample, wherein the water surface is 1-2cm higher than the top surface of the soil sample during each filling, and ensuring that the filled soil sample is a saturated soil sample; meanwhile, the temperature control device is adjusted and filled at 50 ℃, and the soil sample does not contain gas components;
(4) preparing gas-dissolving water with a certain mass through a liquid gas-dissolving device, and injecting the gas-dissolving water from a permeable stone at the top of the soil sample through high pressure, so that the existing airless water in the soil sample is discharged through a high-air-intake-value clay plate at the bottom of the soil sample; when gas-dissolved water is injected into the soil sample, the vertical pressure on the soil sample is kept equal to the pressure in the liquid gas-dissolved device;
(5) after the inner pores of the soil sample are completely filled with the dissolved air water, gradually and slowly reducing the vertical pressure of the soil sample until the pressure required by the test is reached; when the pressure of each stage is stable, the volume of the bubbles in the soil sample under the condition of each stage of pressure can be obtained by increasing the micro vertical pressure in a short time and recording the total variable quantity of the volume of the soil sample when the volume of the soil sample is not changed any more; gradually recording the volume of the bubbles under each stage of pressure condition, and performing inversion calculation through a classical diffusion theory to obtain the size and concentration of the bubbles;
(6) in a formal test, different ultrasonic excitations are applied to a soil sample under certain vertical pressure, and the ultrasonic consolidation effect of the sludge containing bubbles is researched; in the test process, the volume of the effluent liquid at the bottom of the soil sample is measured by a liquid volume measuring device, and the ultrasonic consolidation drainage effect is evaluated by combining the soil sample deformation measuring result of a pressure volume controller; meanwhile, data of the micro pore water pressure gauge and the micro pressure sensor which are uniformly distributed in the soil sample are analyzed, and the evolution rule of pore pressure and ultrasonic vibration along with time is researched; secondly, taking effluent at regular intervals to perform granularity and turbidity tests, and analyzing the evolution rule of granularity and turbidity along with time in the effluent; in addition, after the indoor test is finished each time, the shear strength of the sludge at different positions in the soil sample is tested.
Compared with the prior art, the invention has the following advantages and positive effects:
(1) longitudinal ultrasonic excitation is applied by adopting a vibration mode conversion type high-power ultrasonic transducer, two-dimensional ultrasonic excitation is applied by adopting a hollow cylindrical piezoelectric ceramic transducer, and a sludge consolidation characteristic test in different ultrasonic excitation modes can be developed;
(2) a liquid gas dissolving device, an annular heating ring and a high-gas-inlet-value argil plate are arranged in the system, a sludge soil sample containing certain bubble characteristics is prepared by using a shaft translation technology, and a sludge consolidation characteristic test under the conditions of different bubble sizes and concentrations can be developed;
(3) the pressure volume controller is connected with a small hole at the top of the stainless steel pressure chamber, so that the ultrasonic excitation can be applied, the vertical consolidation pressure can be applied to the soil sample, the deformation of the soil sample can be measured, and the consolidation characteristic tests of the sludge under different vertical pressures can be met;
(4) in order to improve the precision, the volume of the effluent is measured by a liquid volume measuring device, and the ultrasonic consolidation drainage effect is accurately evaluated by combining the soil sample deformation measuring result of a pressure volume controller;
(5) the micro pore water pressure gauge and the micro pressure sensor are uniformly distributed at different positions and different depths of the soil sample, so that the pore water pressure and the vibration attenuation evolution rule in the soil sample under the action of ultrasonic waves can be measured simultaneously;
(6) the control operation on ultrasonic excitation and bubbles is simple and convenient, the automatic measurement and acquisition on ultrasonic attenuation and pore water pressure are realized, and the measured data is accurate.
In a word, the invention can meet the requirements of applying three-dimensional high-power ultrasonic excitation to the sludge, adjusting the size and concentration of bubbles, and carrying out accurate control and measurement tests on consolidation deformation, pore pressure, ultrasonic energy attenuation and the like.
Drawings
FIG. 1 is a block diagram of the architecture of the present system;
fig. 2 is a schematic diagram of the present system.
In the figure:
10-a three-dimensional ultrasonic testing unit,
11-a vertical one-dimensional ultrasonic unit,
111-a one-dimensional ultrasonic generator,
112-one-dimensional ultrasonic transducer;
113-one-dimensional ultrasonic signal transmission cable;
12-a radial two-dimensional ultrasound unit,
121-a two-dimensional ultrasonic generator,
122-a two-dimensional ultrasonic transducer,
123-two-dimensional ultrasonic signal transmission cable;
20-a test unit of soil sample containing air bubbles,
21-the sample of the soil,
22-a liquid-gas-dissolving device,
23-a water-permeable stone,
24-a pottery clay plate with high air intake value,
25-an annular heating ring, wherein the annular heating ring is arranged on the upper surface of the base plate,
26-a temperature control device for controlling the temperature of the molten metal,
27-a wire;
30-a pressure chamber unit, the pressure chamber unit,
31-a stainless steel pressure chamber,
32-a stainless steel top cover, wherein,
33-a stainless steel bottom plate, wherein,
34-nano-base heat-insulating soft felt,
35-a pressure volume controller, which is connected with the pressure volume controller,
36-a movable bolt is arranged on the upper portion of the frame,
37-a bolt of a water filling port,
38-a drain pipe;
40-a measuring unit for measuring the position of the object,
41-a liquid volume measuring device for measuring the volume of liquid,
42-a micro-pore water pressure gauge,
43-a miniature pressure sensor, which is,
44-a data acquisition instrument, and a data acquisition instrument,
45-signal transmission line;
a is a valve.
Detailed Description
The following detailed description is made with reference to the accompanying drawings and examples:
1. system for controlling a power supply
1. General of
Referring to fig. 1 and 2, the system comprises a three-dimensional ultrasonic testing unit 10, a soil sample testing unit 20 containing air bubbles, a pressure chamber unit 30 and a measuring unit 40;
the position and connection relation is as follows:
the three-dimensional ultrasonic testing unit 10, the air-containing soil sample testing unit 20 and the measuring unit 40 are respectively connected with the pressure chamber unit 30.
2. Functional unit
1) Three-dimensional ultrasonic testing unit 10
The three-dimensional ultrasonic testing unit 10 consists of a vertical one-dimensional ultrasonic unit 11 and a radial two-dimensional ultrasonic unit 12;
(1) The vertical one-dimensional ultrasonic unit 11 is formed by connecting a one-dimensional ultrasonic generator 111 and a one-dimensional ultrasonic transducer 112 back and forth through a one-dimensional ultrasonic signal transmission cable 113.
The side of the one-dimensional ultrasonic transducer 112 is sealed with the two-dimensional ultrasonic transducer 122 by a rubber ring, and the one-dimensional ultrasonic transducer 112 can freely move up and down in the two-dimensional ultrasonic transducer 122.
The one-dimensional ultrasonic generator 111 converts the voltage into a high-frequency alternating current signal matched with the one-dimensional ultrasonic transducer 112; the one-dimensional ultrasonic transducer 112 converts the received high-frequency electric signal into ultrasonic waves; the ultrasonic load emitted from the one-dimensional ultrasonic transducer 112 is applied from the top of the soil sample 21 downward through the permeable stone 23.
The one-dimensional ultrasonic transducer 112 adopts a vibration mode conversion type high-power ultrasonic transducer, a longitudinal sandwich type piezoelectric ceramic transducer in the transducer generates longitudinal vibration, and then a metal cylindrical radiator connected with the transducer is driven to generate vibration; the size of the one-dimensional ultrasonic transducer 112 is 80cm in outer diameter and 2cm in thickness.
(2) The radial two-dimensional ultrasonic unit 12 is formed by connecting a two-dimensional ultrasonic generator 121 and a two-dimensional ultrasonic transducer 122 back and forth through a two-dimensional ultrasonic signal transmission cable 123;
the two-dimensional ultrasonic transducer 122 is a hollow cylindrical piezoelectric ceramic transducer, which is formed by radially compounding a piezoelectric ceramic element and a metal element, the ultrasonic load radiates to the inside of the soil sample 21, and the inner cylindrical surface serves as a radiation surface and can be regarded as an acoustic wave focuser.
The design principle of the two-dimensional ultrasonic transducer 122 is as follows: firstly, the inner and outer metal circular tubes of the transducer must be made of different metal materials, the metal cylinder on the inner side of the transducer is generally light metal, and the metal cylinder on the outer side should be made of heavy metal; secondly, the metal round tube-shaped electrode material is beryllium bronze material, and the number of the piezoelectric ceramic round tubes is even, so that the problems of grounding and insulation of the piezoelectric ceramic round tubes can be well solved.
The dimensions of the two-dimensional ultrasonic transducer 122 are: the inside diameter was 80cm, the height was 123cm, and the wall thickness was 1.5cm, and the inside of the transducer was filled with a soil sample.
In addition, the one-dimensional ultrasonic generator 111 and the two-dimensional ultrasonic generator 121 both adopt the same type of self-excited ultrasonic generator, and the type of self-excited ultrasonic generator has the output power of 0-20kW and the output frequency of 10-35kHz.
2) Test unit 20 for soil sample containing air bubbles
The bubble-containing soil sample test unit 20 consists of a soil sample 21, a liquid air dissolving device 22, a permeable stone 23, a high air intake value argil plate 24, an annular heating ring 25, a temperature control device 26 and a lead 27;
the position and connection relation is as follows:
in the pressure chamber unit 30, from bottom to top, a stainless steel bottom plate 33, a high-air-intake-value pottery clay plate 24, a soil sample 21, a permeable stone 23 and a one-dimensional ultrasonic transducer 112 are sequentially connected;
the liquid air dissolving device 22 is connected with the valve A through a pipeline, penetrates through a central small hole of the one-dimensional ultrasonic transducer 112 and is communicated with the permeable stone 23 above the soil sample 21;
an annular heating ring 25 is arranged between the stainless steel pressure chamber 31 and the two-dimensional ultrasonic transducer 122, and the annular heating ring 25 is connected with the temperature control device 26 through a lead 27.
The soil sample 21 is cylindrical and has the following dimensions: the diameter is 80cm, and the height is 120cm; the soil sample 21 in the size range can better research the law of consolidation deformation of the ultrasonic-excited sludge;
the annular heating ring 25 adopts a resistance type heating ring with the maximum power of 3000W;
the temperature control device 26 is a conventional device for adjusting the temperature inside the stainless steel pressure chamber 31 during the manufacturing process of the soil sample 21.
The working mechanism of the soil sample test unit 20 containing the air bubbles is as follows:
the liquid air dissolving device 22 repeatedly injects high-pressure air into water with certain mass, increases the confining pressure of the water to improve the solubility of the air in the water, and then injects the water-dissolved air into the soil sample 21 through the permeable stone 23; meanwhile, when the high air intake value argil plate 24 at the bottom of the soil sample 21 is saturated, the surface of the high air intake value argil plate 24 is formed with a shrinkage film due to the micro pores on the surface, and the shrinkage film connects a plurality of small pores on the surface of the high air intake value argil plate 24 to generate surface tension, so that air is prevented from passing through the high air intake value argil plate 24, but moisture can be discharged; the air inlet value of the high air inlet value argil plate 24 is 1500kPa, so that a soil sample containing certain bubble characteristics is prepared by utilizing an axis translation technology; when higher air pressure needs to be borne, special fiber membranes with air inlet values as high as 10MPa can be adopted.
3) Pressure chamber unit 30
The pressure chamber unit 30 comprises a stainless steel pressure chamber 31, a stainless steel top cover 32, a stainless steel bottom plate 33, a nano-base heat insulation soft felt 34, a pressure volume controller 35, a movable bolt 36, a water injection bolt 37 and a drain pipe 38;
the position and connection relation is as follows:
the stainless steel top cover 32, the stainless steel pressure chamber 31 and the stainless steel bottom plate 33 are connected up and down through movable bolts 36 to form an axisymmetric container, two layers of nano-base heat insulation soft felts 34 are adhered to the outer wall of the container, a water filling port bolt 37 is arranged on the stainless steel top cover 32, and a drain pipe 38 is arranged on the stainless steel bottom plate 33.
The inner diameter of the container is 83.5cm, the inner height is 160cm, and the wall thickness is 2cm;
the top of the stainless steel top cover 32 is provided with a small hole which is communicated with a pressure volume controller 35 and used for applying vertical consolidation pressure to the soil sample 21 and measuring the deformation of the soil sample, and the pressure volume controller 35 is a GDS triaxial soil test instrument pressure volume controller.
The nano-based heat insulation soft felt 34 is one of the most efficient soft heat insulation products on the market at present.
4) Measuring unit 40
The measuring unit 40 is composed of a liquid volume measuring device 41, a micro pore water pressure gauge 42, a micro pressure sensor 43 and a data acquisition instrument 44;
the liquid volume measuring device 41 is communicated with the pressure chamber unit 30 through the drain pipe 38 to measure the liquid volume change;
the micro pore water pressure gauge 42 and the micro pressure sensor 43 which are respectively connected with the data acquisition instrument 44 through the signal transmission line 45 are respectively arranged in the soil sample 21 to measure the pore water pressure and the ultrasonic vibration.
3. Principle of operation
1) Filling the soil sample 21 in the two-dimensional ultrasonic transducer 122 in a layered manner, wherein the water level is 1-2cm higher than the top surface of the soil sample 21 when filling each time, so that the filled soil sample 21 is a saturated soil sample; meanwhile, the soil sample 21 is filled at a higher temperature (50 ℃), so that air entering the soil sample 21 during filling can be reduced; the soil sample 21 thus prepared was a fully saturated soil sample, and the soil sample 21 contained no gas component; after the soil sample 21 is filled, the stainless steel top cover 32 and related pipelines are installed, and the pressure volume adjusting controller 35 applies vertical pressure to the soil sample 21.
2) Preparing gas-dissolved water with certain mass by a liquid gas-dissolving device 22, and injecting the gas-dissolved water into the soil sample 21 from a permeable stone 23 at the top of the soil sample 21 through high pressure, so that the existing airless water in the soil sample 21 is discharged through a high-air-intake-value clay plate 24 at the bottom of the soil sample 21; the volume of the injected dissolved air water is more than 10 times of the pore volume in the soil sample 21, and the residual airless water in the soil sample 21 can be discharged; when the gas-dissolved water is injected into the soil sample 21, the vertical pressure applied to the soil sample 21 is kept equal to the pressure in the liquid gas-dissolving device 22, so that the test error caused by the release of the gas in the gas-dissolved water can be avoided.
3) When the inner pores of the soil sample 21 are completely filled with the dissolved air water, gradually and slowly reducing the vertical pressure of the soil sample 21 until the pressure required by the test is reached; when the vertical pressure is reduced step by step, the gas dissolved in the water in the soil sample 21 is changed into a super-saturated state, and then bubbles begin to form in the soil sample 21; when the pressure of each stage is stable, the volume of the bubbles in the soil sample 21 under the condition of each stage of pressure can be obtained by increasing the micro vertical pressure in a short time and recording the total change of the volume of the soil sample 21 when the volume of the soil sample 21 is not changed any more; gradually recording the volume of the bubbles under each stage of pressure condition, and performing inversion calculation through a classical diffusion theory to obtain the size and concentration of the bubbles; in determining the volume of air bubbles in a soil sample, the application time of the vertical pressure must be very short to avoid re-dissolution of the air bubbles into the water during application.
4) Applying vertical one-dimensional ultrasonic excitation to the soil sample 21 by using a one-dimensional ultrasonic transducer 112; applying radial two-dimensional ultrasonic excitation to the soil sample 21 by the two-dimensional ultrasonic transducer 122; under the action of high-power ultrasonic waves, micro bubble nuclei in fluid in sludge pores are activated, ultrasonic vibration continuously and rapidly alternates to collapse the cavitation bubble nuclei, local high temperature and high pressure are generated in a very short time, and strong shock waves and jet flow are accompanied, so that migration motion of water and fine particles in sludge is caused; meanwhile, the pressure volume controller 35 is used for applying vertical consolidation pressure to the soil sample 21 and measuring the deformation of the soil sample, and the system can test consolidation deformation, pore pressure, ultrasonic energy attenuation and the like.
2. Method for producing a composite material
(1) Whether the high air intake value argil plate 24 and the pipeline thereof are saturated or not is related to the success or failure of the test, for this reason, before the formal test, the high air intake value argil plate 24 is saturated by adopting an air exhaust saturation method, and the saturation of the pipeline of the test system is realized by injecting airless water into the pipeline in advance by using a peristaltic pump for flushing until no air bubbles exist;
(2) naturally drying the sludge under the shady and cool condition, and adding certain mass of airless water into a sludge air-dried sample according to test requirements;
(3) filling the soil sample 21 in the two-dimensional ultrasonic transducer 122 layer by layer with the sludge sample after water addition, tamping each layer for the same times to ensure the integral uniformity of the soil sample 21, wherein the water level is 1-2cm higher than the top surface of the soil sample 21 during each filling, and ensuring that the filled 21 is a saturated soil sample; meanwhile, the temperature control device 26 is adjusted to fill the soil sample 21 at a higher temperature, so that air entering the soil sample 21 during filling can be reduced; however, the influence on the components of the sludge can be caused by overhigh temperature, and the filling is preliminarily planned to be carried out under the condition of 50 ℃; therefore, the saturated soil sample 21 with a certain density can be prepared through the steps, and the soil sample 21 does not contain gas components;
(4) preparing gas-dissolving water with a certain mass by a liquid gas-dissolving device 22, and injecting the gas-dissolving water from a permeable stone 23 at the top of the soil sample 21 through high pressure, so that the existing airless water in the soil sample 21 is discharged through a high-air-intake-value clay plate 24 at the bottom of the soil sample 21; looking up related data, the volume of the injected dissolved gas water can be more than 10 times of the pore volume in the soil sample 21, and the residual water without gas in the soil sample can be discharged, so that the process needs a long time; meanwhile, vertical pressure is applied to the soil sample 21 by adjusting the pressure volume controller 35;
when the gas-dissolved water is injected into the soil sample, the vertical pressure on the soil sample 21 is kept equal to the pressure in the liquid gas-dissolving device 22, so that the test error caused by the release of the gas in the gas-dissolved water can be avoided;
(5) when the inner pores of the soil sample 21 are completely filled with the dissolved air water, gradually and slowly reducing the vertical pressure of the soil sample 21 until the pressure required by the test is reached; when the vertical pressure is reduced step by step, the gas dissolved in the water in the soil sample 21 is changed into a super-saturated state, and at the moment, bubbles begin to form in the soil sample; when the pressure of each stage is stable, the volume of the bubbles in the soil sample under the condition of each stage of pressure can be obtained by increasing the micro vertical pressure in a short time and recording the total change of the volume of the soil sample 21 when the volume of the soil sample 21 is not changed any more; gradually recording the volume of the bubbles under each stage of pressure condition, and performing inversion calculation through a classical diffusion theory to obtain the size and concentration of the bubbles;
in determining the volume of air bubbles in a soil sample, the application time of the vertical pressure must be very short to avoid re-dissolution of the air bubbles into the water during application.
(6) In a formal test, different ultrasonic excitations are applied to a soil sample under certain vertical pressure, and the ultrasonic consolidation effect of the sludge containing bubbles is researched; in the test process, the volume of the effluent liquid at the bottom of the soil sample 21 is measured by the liquid volume measuring device 41, and the ultrasonic consolidation drainage effect is evaluated by combining the soil sample deformation measuring result of the pressure volume controller 35; meanwhile, the data of the miniature pore water pressure gauges 42 and the miniature pressure sensors 43 which are uniformly distributed in the soil sample are analyzed, and the evolution rule of pore pressure and ultrasonic vibration along with time is researched; secondly, taking effluent at regular intervals to perform granularity and turbidity tests, and analyzing the evolution rule of granularity and turbidity along with time in the effluent; in addition, after the indoor test is finished each time, the shear strength of the sludge at different positions in the soil sample is tested.
Claims (1)
1. A test method of a three-dimensional high-power ultrasonic control gas bubble-containing sludge consolidation test system,
the test system comprises a three-dimensional ultrasonic test unit (10), a soil sample test unit (20) containing air bubbles, a pressure chamber unit (30) and a measuring unit (40);
the position and connection relation is as follows:
the three-dimensional ultrasonic testing unit (10), the testing unit (20) for the soil sample containing air bubbles and the measuring unit (40) are respectively connected with the pressure chamber unit (30);
the three-dimensional ultrasonic testing unit (10) consists of a vertical one-dimensional ultrasonic unit (11) and a radial two-dimensional ultrasonic unit (12);
the vertical one-dimensional ultrasonic unit (11) is formed by connecting a one-dimensional ultrasonic generator (111) and a one-dimensional ultrasonic transducer (112) back and forth through a one-dimensional ultrasonic signal transmission cable (113);
the radial two-dimensional ultrasonic unit (12) is formed by connecting a two-dimensional ultrasonic generator (121) and a two-dimensional ultrasonic transducer (122) back and forth through a two-dimensional ultrasonic signal transmission cable (123);
the testing unit (20) for the soil sample containing the air bubbles consists of a soil sample (21), a liquid air dissolving device (22), a permeable stone (23), a high air intake value pottery clay plate (24), an annular heating ring (25), a temperature control device (26) and a lead (27);
in the pressure chamber unit (30), from bottom to top, a stainless steel bottom plate (33), a high-air-intake-value argil plate (24), a soil sample (21), a permeable stone (23) and a one-dimensional ultrasonic transducer (112) are sequentially connected;
the liquid air dissolving device (22) is connected with the valve (A) through a pipeline, penetrates through a small central hole of the one-dimensional ultrasonic transducer (112) and is communicated with the permeable stone (23) above the soil sample (21);
an annular heating ring (25) is arranged between the stainless steel pressure chamber (31) and the two-dimensional ultrasonic transducer (122), and the annular heating ring (25) is connected with a temperature control device (26) through a lead (27);
the pressure chamber unit (30) comprises a stainless steel pressure chamber (31), a stainless steel top cover (32), a stainless steel bottom plate (33), a nano-base heat insulation soft felt (34), a pressure volume controller (35), a movable bolt (36), a water injection bolt (37) and a drain pipe (38);
the position and connection relation is as follows:
the stainless steel top cover (32), the stainless steel pressure chamber (31) and the stainless steel bottom plate (33) are connected up and down through movable bolts (36) to form an axisymmetric container, two layers of nano-base heat insulation soft felts (34) are adhered to the outer wall of the container, a water injection port bolt (37) is arranged on the stainless steel top cover (32), and a drain pipe (38) is arranged on the stainless steel bottom plate (33);
the inner diameter of the container is 83.5cm, the inner height is 160cm, and the wall thickness is 2cm;
a small hole is formed at the top of the stainless steel top cover (32) and communicated with a pressure volume controller (35);
the measuring unit (40) consists of a liquid volume measuring device (41), a micro pore water pressure meter (42), a micro pressure sensor (43) and a data acquisition instrument (44);
the liquid volume measuring device (41) is communicated with the pressure chamber unit (30) through a drain pipe (38) and measures the liquid volume change of the liquid volume measuring device;
a micro pore water pressure gauge (42) and a micro pressure sensor (43) which are respectively connected with the data acquisition instrument (44) through a signal transmission line (45) are respectively arranged in different positions of the soil sample (21) to measure the pore water pressure and the ultrasonic vibration;
the method is characterized by comprising the following steps:
(1) before formal test, the high air intake value argil plate (24) is saturated by adopting an air extraction saturation method until no air bubbles exist;
(2) naturally drying the sludge sample in the shade, and adding the airless water into the sludge air-dried sample;
(3) putting the sludge sample added with the airless water into a two-dimensional ultrasonic transducer (122) for filling the soil sample (21) layer by layer, tamping each layer for the same times to ensure the integral uniformity of the soil sample (21), wherein the water level is 1-2cm higher than the top surface of the soil sample (21) during each filling, and ensuring that the filled soil sample (21) is a saturated soil sample; meanwhile, the temperature control device (26) is adjusted and is filled at 50 ℃, and the soil sample (21) does not contain gas components;
(4) preparing gas-dissolving water with certain mass by a liquid gas-dissolving device (22), and injecting the gas-dissolving water from a permeable stone (23) at the top of the soil sample (21) through high pressure, so that the existing airless water in the soil sample (21) is discharged through a high-air-intake-value clay plate (24) at the bottom of the soil sample (21); when gas-dissolved water is injected into the soil sample (21), the vertical pressure on the soil sample (21) is kept equal to the pressure in the liquid gas-dissolved device (22);
(5) when the inner pores of the soil sample (21) are completely filled with the dissolved air water, gradually and slowly reducing the vertical pressure of the soil sample (21) until the pressure required by the test is reached; when the pressure of each stage is stable, the volume of the bubbles in the soil sample under the condition of each stage of pressure can be obtained by increasing the micro vertical pressure in a short time and recording the total change of the volume of the soil sample (21) when the volume of the soil sample (21) is not changed any more; gradually recording the volume of the bubbles under each stage of pressure condition, and performing inversion calculation through a classical diffusion theory to obtain the size and concentration of the bubbles;
(6) in a formal test, different ultrasonic excitations are applied to the soil sample (21) under certain vertical pressure to research the ultrasonic consolidation effect of the sludge containing bubbles; in the test process, the volume of the effluent liquid at the bottom of the soil sample (21) is measured by a liquid volume measuring device (41), and the ultrasonic consolidation drainage effect is evaluated by combining the soil sample deformation measuring result of a pressure volume controller (35); meanwhile, data of the micro pore water pressure gauge (42) and the micro pressure sensor (43) which are uniformly distributed in the soil sample are analyzed, and the evolution rule of pore pressure and ultrasonic vibration along with time is researched; secondly, taking effluent at regular intervals to perform granularity and turbidity tests, and analyzing the evolution rule of granularity and turbidity along with time in the effluent; in addition, after the indoor test is finished each time, the shear strength of the sludge at different positions in the soil sample is tested.
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| CN110031400B (en) * | 2019-05-05 | 2024-01-02 | 中交疏浚技术装备国家工程研究中心有限公司 | Multifunctional device for measuring adhesion force between dredging cutter tooth and clay and optimizing cutter tooth |
| CN111024923A (en) * | 2019-12-03 | 2020-04-17 | 中国电建集团华东勘测设计研究院有限公司 | Gas evolution in soil and gas-containing soil mechanics measuring device |
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