A test device and method for treating flocculent slurry by vacuum preloading combined with electro-osmosis

Abstract

The application discloses a kind of vacuum preloading combined electroosmosis method processing flocculus mud test device and method, a kind of vacuum preloading combined electroosmosis method processing flocculus mud test device, including mud model system, vacuum preloading system, electroosmosis system and data acquisition system, the vacuum preloading system includes the improved drainage body in mud model system, suction filter container and vacuum pump, the improved drainage body is connected as electrode by wire with electroosmosis system, the improved drainage body includes framework, filter screen, blocking body and broken stone located at the both ends of framework, the filter screen of the improved drainage body is detachable steel wire filter screen, aperture can be freely selected, by changing the aperture of different steel wire filter screen, the influence of different aperture filter membrane on mud dewatering performance can be explored;Improved drainage body uses spring as built-in framework, not easy to bend and not hinder water seepage;Improved drainage body can conduct electricity, for the research of different arrangement mode of electrode on mud dewatering performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of engineering waste slurry resource disposal technology, and particularly relates to a test device and method for treating flocculation slurry by vacuum preloading combined with electro-osmosis method. BACKGROUND

[0002] When passing through valleys and rivers along railways and highways, bridges must be built to open roads, and pile foundation engineering is inevitably involved in bridge building. At present, slurry bored pile technology has been quite mature and is widely used in various pile foundation engineering. However, a large amount of waste slurry generated during construction is difficult to solve due to its special physicochemical properties. The amount of general waste slurry is 3-5 times the volume of the borehole, and improper disposal will cause great pollution to the environment. When construction projects are built in places with high environmental protection requirements, waste slurry cannot be dumped at will, otherwise huge fines or project suspension will be faced. Therefore, reasonable disposal of slurry is imperative, and an efficient and simple slurry dewatering and volume reduction method is urgently needed.

[0003] At present, the methods for engineering waste slurry can be roughly divided into four types: one is natural sedimentation, which has the characteristics of occupying a large amount of land resources, large scale of sedimentation tank, long sedimentation period and limited sedimentation amount of soil particles; two is chemical solidification method, which adds chemical agents to the slurry, and the agents react with the slurry to quickly solidify the slurry. However, there are defects such as high cost of large-scale use of chemical agents and difficulty in reusing the soil after solidification; three is regeneration treatment method, which detects the properties of waste slurry, and then uses filtration, sedimentation and other methods to separate, purify, regenerate and supplement the slurry. Through regeneration treatment, the slurry consumption can be saved by 10%-25%, but the regeneration treatment has problems such as complex process and unstable properties of regenerated slurry. Four is chemical flocculation and mechanical dewatering treatment method, which adds flocculants to the slurry, and the flocculants have adsorption bridge and net capture effect to accelerate the sedimentation of soil particles in the slurry. The flocculated slurry is further treated by mechanical pressure filtration and centrifugation to further reduce the water content of the slurry. However, this method has the problem of high energy consumption, which greatly limits its popularization and application.

[0004] Electroosmosis method has a long history in soft foundation treatment. The Russian scholar first discovered that the clay with extremely small particle size has negative charge. Under the action of electric field, the soil particles slowly move to the anode and squeeze water molecules to move in the opposite direction, which is electrophoresis. The clay has a double electron layer structure, which adsorbs a large number of polar water molecules. Under the action of electric field, the double electric layer on the surface of the clay slips, which weakens the adsorption of the double electric layer, and the soil particles and water molecules can be separated, which is electroosmosis. Electroosmosis method has been applied in the dehydration treatment of soft foundation with high clay content. It has good effect on soft foundation reinforcement when combined with vacuum preloading method, especially when the water content is low in the later stage. However, the abandoned engineering slurry is a stable colloid formed by micron-sized soil particles adsorbing a large number of water molecules, so natural sedimentation is difficult to separate. Therefore, vacuum preloading electroosmosis method can be considered to be applied in the dehydration of abandoned engineering slurry.

[0005] The initial abandoned engineering slurry has high water content and contains a lot of free water. The water content is generally more than 200%. Direct use of electroosmosis has high energy consumption and economic efficiency needs to be discussed. Generally, anionic polyacrylamide flocculant can be added to the slurry with high initial water content. The micron-sized soil particles in the slurry are flocculated into clusters under the action of adsorption bridge, sweeping net and trapping net. The upper layer of dehydrated clear liquid can be directly pumped out, and the remaining flocculent slurry can be further treated. However, the ordinary plastic drainage belt is used in the previous vacuum preloading dehydration method. The ordinary plastic drainage belt has the following defects: 1. The equivalent pore size of the filter membrane is small, which is easy to block; 2. The soil body shrinks after dehydration, and the drainage belt is easy to bend.

[0006] Therefore, it is a problem worth studying to provide a test device and method for vacuum preloading combined with electroosmosis method for treating flocculent slurry by using reusable improved drainage body to realize multiple dehydration of flocculent slurry. SUMMARY

[0007] In order to solve the above problems in the prior art, the purpose of the present application is to provide a test device and method for vacuum preloading combined with electroosmosis method for treating flocculent slurry by using reusable improved drainage body to realize multiple dehydration of flocculent slurry.

[0008] The purpose of the present application is achieved as follows:

[0009] A kind of vacuum preloading combined with electro-osmosis method treats flocculation slurry experimental device, including the slurry model system for containing slurry, with the slurry model system connection vacuum preloading system, with the slurry model system connection and for slurry electro-osmosis system, for measuring the data acquisition system of slurry performance in slurry model system, the vacuum preloading system includes located in slurry model system improved drainage body, with the top of improved drainage body by plastic steel wire hose connection suction filter container, with suction filter container by plastic steel wire hose connection vacuum pump, the improved drainage body is connected as electrode by wire with electro-osmosis system, the improved drainage body includes the skeleton with elasticity, filter screen wrapped on the skeleton and can be dismantled, blocking body located at the both ends of skeleton and blocking the containing cavity formed by filter screen and skeleton, gravel located inside containing cavity.

[0010] The frame adopts spring, the filter screen adopts steel wire filter screen, the blocking body adopts rubber plug, and a drain pipe is arranged in the containing cavity, and the top of the drain pipe is connected with the plastic steel wire hose through a cross joint.

[0011] A plurality of annular clamps are arranged on the skeleton, and the plurality of annular clamps are wrapped on the outer surface of the filter screen and uniformly distributed along the length direction of the skeleton.

[0012] A valve is arranged on the plastic steel wire hose for controlling the amount of water entering the suction filter container and the amount of gas extracted by the vacuum pump.

[0013] The slurry model system includes a base on the ground, a visual slurry tank on the base, and an inner support for fixing the improved drainage body in the visual slurry tank.

[0014] The electro-osmosis system includes a direct current power supply connected with the improved drainage body through a wire.

[0015] The data acquisition system includes a water level gauge in the suction filter container, a scale in the visual slurry tank, an air void pressure gauge in the visual slurry tank connected with a data acquisition device through a wire, and a pressure gauge on the top of the suction filter container for detecting the pressure in the suction filter container.

[0016] A vacuum preloading combined with electro-osmosis method for treating flocculation slurry test method includes the following steps:

[0017] Step one: the flocculation slurry to be dewatered is loaded into the visual slurry tank, the improved drainage body and the pore water pressure gauge are arranged, the top surface of the flocculation slurry is sealed by a sealing film, and the surrounding is treated by a pressure ditch;

[0018] Step two: start the vacuum preloading system, temporarily close the valve connected with the slurry tank on the suction filter container, open the valve when the vacuum negative pressure of the suction filter container reaches-85KPa, and turn to step three when the dewatering rate is lower than 1000ml / h.

[0019] Step 3: Connect the electrodes of the DC power supply to the wires on the improved drainage body according to the design plan, and use the electrodes to convert into cathodes and anodes to perform vacuum preloading combined with electroosmosis deep dehydration on the mud. Stop the test when the mud surface settlement and dehydration amount are basically stable.

[0020] Step 4: After stopping the test, recycle the equipment; organize the pore water pressure data, dehydration data, and mud surface settlement data during the test; take soil at different spatial locations and test the moisture content.

[0021] Positive and beneficial effects: The filter of the improved drainage body of the present invention is a detachable steel wire filter, and the aperture can be freely selected. By changing the different apertures of the steel wire filter, the influence of filter membranes with different apertures on the mud dewatering performance can be explored; the improved drainage body uses a spring as a built-in skeleton, which is not easy to bend and does not hinder the seepage of water; the improved drainage body is conductive and can be used to study the influence of different electrode arrangements on the mud dewatering performance. The improved drainage body takes into account the triple functions of electroosmosis electrode, anti-clogging and anti-bending. By monitoring the changes in the dehydration amount of the mud, the suitable time node for the electroosmosis method to participate in mud dehydration can be explored; by adjusting the voltage and current of the DC power supply, the influence of the step-by-step changes in voltage and current on the mud dewatering performance can be explored; by changing the electrode position, the influence of different arrangements of electroosmosis electrodes on the mud dewatering performance can be explored. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the present invention;

[0023] Figure 2 This is a schematic structural diagram of the improved drainage body of the present invention;

[0024] Figure 3 Schematic diagram of the structure of the inner support of the present invention;

[0025] Figure 4 Schematic diagram of electrode arrangement of the present invention;

[0026] The figure shows: vacuum pump 1, plastic steel wire hose 2, filtration container 3, valve 4, pressure gauge 5, water level gauge 6, visual mud pool 7, ruler 8, inner support 9, sealing membrane 10, improved drainage body 11, wire 12, rubber plug 13, ring clamp 14, gravel 15, wire filter 16, spring 17, "cross" connector 18, inner bracket 19, DC power supply 20, data acquisition equipment 21, pore water pressure gauge 22, and base 23. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and examples.

[0028] Example 1

[0029] As Figure 1 shown, a kind of vacuum pre-pressing combined with electroosmosis method processing flocculation mud experimental device, including the mud model system for containing mud, with the mud model system connection vacuum pre-pressing system, with the mud model system connection and for mud electroosmosis system, for measuring the data acquisition system of mud performance in mud model system, the vacuum pre-pressing system includes the improved drainage body 11 in mud model system, with the top of improved drainage body 11 by plastic steel wire hose 2 connection suction filter container 3, with suction filter container 3 by plastic steel wire hose 2 connection vacuum pump 1, the improved drainage body 11 is connected as electrode by wire with electroosmosis system, the plastic steel wire hose 2 is equipped with valve 4 for controlling the amount of water into suction filter container 3 and the amount of gas extracted by vacuum pump 1, the suction filter container 3 is welded by steel material, and the top is sealed by sealing ring, flange plate;The top cover of suction filter container 3 is equipped with five valves and a pressure gauge, left side is equipped with water level gauge, and lower side is equipped with drain valve.Water level gauge precision is 1cm.Suction filter container size can be designed according to the amount of dehydration.Improved drainage body can conduct electricity, and can be used for the research of different electrode arrangement modes on mud dehydration performance, and improved drainage body gives consideration to electroosmosis electrode, anti-clogging and anti-bending triple effect, by monitoring the change of mud dehydration amount, the suitable time node of electroosmosis method participating in mud dehydration can be explored;By adjusting the voltage and current of direct current power supply, the influence of step-by-step change of voltage and current on mud dehydration performance can be explored;By changing electrode position, the influence of different electrode arrangement modes of electroosmosis method on mud dehydration performance can be explored.

[0030] As Figure 2 shown, the improved drainage body includes elastic framework, detachable filter screen wrapped on the framework, blocking body located at both ends of the framework and blocking the containing cavity formed by the filter screen and the framework, and gravel 15 located inside the containing cavity.The framework adopts spring 17, the filter screen adopts steel wire filter screen 16, the blocking body adopts rubber plug 13, and a drain pipe is arranged in the containing cavity, and the top of the drain pipe is connected with plastic steel wire hose 2 through "cross" joint 18.The framework is provided with a plurality of annular clamps 14, the plurality of annular clamps 14 are wrapped on the outer surface of the filter screen and are uniformly distributed along the length direction of the framework, the annular clamps 14 are used for reinforcing the framework and the filter screen, the distance between adjacent two annular clamps 14 is 20cm, the overlapping part of the spring 17 and the steel wire filter screen 16 is adhered by non-hydrolyzed two-component industrial strong glue, the filter screen of the improved drainage body 11 is detachable steel wire filter screen 16, the pore size can be freely selected, by changing the different pore sizes of the steel wire filter screen 16, the influence of filter membrane with different pore sizes on mud dehydration performance can be explored;The improved drainage body 11 uses spring 17 as built-in framework, which is not easy to bend and does not hinder the seepage of water.

[0031] As Figure 3As shown, the mud model system includes a base 23 located on the ground, a visual mud pool 7 located on the base 23, and an inner bracket 19 located in the visual mud pool 7 and fixing the improved drainage body 11. The visual mud pool 7 adopts a transparent material to facilitate observation of the mud in the visual mud pool 7. An inner support 9 is provided in the visual mud pool 7, and the inner bracket 19 is placed on the inner support 9. The inner support 9 is two protruding inner supports provided in the middle position of the symmetrical side walls. The design of the inner bracket 19 is based on the overall layout of the improved drainage body 11. The length of the inner bracket 19 is slightly smaller than the inner diameter length of the visual mud pool 7. The inner bracket 19 is used to support the improved drainage body 11. The inner bracket 19 is formed by overlapping pipes with an outer diameter of less than 20 mm to form a "well"-shaped bracket, wherein the pipe material can be PVC material or other non-conductive materials.

[0032] like Figure 4 As shown, the electroosmosis system includes a DC power supply 20, which is connected to the improved drainage body 11 through a wire 12, that is, the wire is connected to the spring 17 and is conductive. At this time, the improved drainage body 11 is equivalent to an electrode, and the DC power supply 20 provides power.

[0033] The data acquisition system includes a water level gauge 6 located in the filtration container 3, a scale 8 located in the visual mud pool 7, a pore water pressure gauge 22 located in the visual mud pool 7 and connected to the data acquisition device 21 through a wire, and a pressure gauge 5 located on the top of the filtration container and used to detect the pressure in the filtration container 3. The water level gauge 6 is used to detect the water level in the filtration container 3, the scale 8 is used to detect the height of the mud in the visual mud pool 7, the pore water pressure gauge 22 is used to detect the pressure of the water in the visual mud pool 7, and the data acquisition device 21 is a display screen, which is convenient for timely observation of the reading of the pore water pressure gauge 22.

[0034] Specific installation process: the visual slurry tank 7 is placed on the base 23, the front is pasted with the scale ruler 8; first, the inner support 19 is placed on the middle inner support 9, the design of the inner support 19 is based on the overall arrangement of the improved drainage body 11, the length of the inner support 19 is slightly smaller than the length of the inner diameter of the visual slurry tank 7; the pre-prepared improved drainage body 11 is placed in the visual slurry tank 7 and is bound and reinforced with the inner support 19 with fine iron wire, the wires 12 of the eight improved drainage bodies 11 on the left and right are connected with the negative pole of the direct current power supply 20, the wires 12 of the four improved drainage bodies 11 in the middle are connected with the positive pole of the direct current power supply 20, and the plastic steel wire hose 2 at the end of the improved drainage body 11 is connected with the valve 4 of the suction filter container 3 through the cross joint 18; the pore water pressure gauge 22 is bound with the inner support 19 with iron wire according to the test scheme, the lower sensing element is suspended in the slurry; the flocculation slurry is slowly poured into the slurry tank to the scale 80 cm, the sealing film 10 is covered on the surface of the slurry through the data line of the improved drainage body 11 and the pore water pressure gauge 22, and the sealing film 10 is repaired with adhesive tape at the damaged place. Finally, the vacuum pump 1 is connected with the suction filter container 3 through the plastic steel wire hose 2; whether the vacuum pump 1, the direct current power supply 20 and the data acquisition equipment 21 can work normally is tested, and the test preparation work is completed.

[0035] The formal test is implemented, first, the four valves 4 connected with the improved drainage body 11 are closed, the vacuum pump 1 is started to perform air suction on the suction filter container 3, when the vacuum pressure reaches 85 KPa, the valve 4 is opened, and the vacuum preloading dewatering test of the slurry is performed. The dewatering volume of the slurry, the slurry surface settlement and the pore water pressure are recorded in time; when the dewatering rate of the slurry is less than 1 L / h, that is, the scale change of the water level gauge 6 is less than 1 cm, the vacuum preloading combined with electro-osmosis is used for dewatering the slurry, the direct current power supply 20 is opened, and the dewatering volume of the slurry, the slurry surface settlement and the pore water pressure data are recorded in time; when the water level gauge is basically stable, the experiment is ended. The sealing film 10 is removed, the improved drainage body 11, the wire 12, the power supply and other equipment are recovered, and the soil sample is taken to determine the moisture content. The test can flexibly change the electrode to study the influence of different cathode and anode arrangement modes on the dewatering performance of the slurry.

[0036] Example 2

[0037] A test method for treating flocculation slurry by vacuum preloading combined with electro-osmosis method, comprising the following steps: step one: the flocculation slurry to be dewatered is loaded into a visual slurry tank 7, the improved drainage body 11 and the pore water pressure gauge 22 are arranged, the top surface of the flocculation slurry is sealed by a sealing film 10, and the surrounding is treated by pressure ditching;

[0038] Step two: start the vacuum preloading system, temporarily close the valve 4 connected with the slurry tank on the suction filter container 3, open the valve 4 when the vacuum negative pressure of the suction filter container 3 reaches-85 KPa. When the dewatering rate is less than 1000 ml / h, that is, the scale change of the water level gauge 6 is less than 1 cm, go to step three.

[0039] Step three: according to the design scheme, the electrode of the direct current power supply 20 is connected to the wire on the improved drainage body 11, and the electrode is converted into a cathode and anode to carry out vacuum preloading combined with electro-osmotic deep dewatering on the mud. When the mud surface settlement and dewatering amount are basically stable, the test is stopped.

[0040] Step four: after stopping the test, the equipment is recovered; the pore water pressure data, dewatering amount data and mud surface settlement data during the test are sorted out; and the soil at different spatial positions is taken to test the moisture content.

Claims

1. A test device for treating flocculent slurry by vacuum preloading combined with electroosmosis, characterized by: The invention comprises a mud model system for holding mud, a vacuum preloading system connected to the mud model system, an electroosmotic system connected to the mud model system and for performing electroosmosis on the mud, and a data acquisition system for measuring the properties of the mud in the mud model system. The vacuum preloading system comprises an improved drainage body located in the mud model system, a filtration container connected to the top of the improved drainage body via a plastic steel wire hose, and a vacuum pump connected to the filtration container via the plastic steel wire hose. The improved drainage body is connected to the electroosmotic system via a wire to serve as an electrode. The improved drainage body comprises an elastic skeleton, a detachable filter screen wrapped around the skeleton, a blocking body located at both ends of the skeleton and blocking a receiving cavity formed by the filter screen and the skeleton, and gravel located within the receiving cavity. The skeleton is spring-loaded, the filter screen is a steel filter screen, and the blocking body is a rubber stopper. A drainage pipe is provided in the receiving cavity, the top of which is connected to the plastic steel wire hose via a "cross" joint. The skeleton is provided with a plurality of annular clamps, which are wrapped around the outer surface of the filter screen and evenly distributed along the length of the skeleton.

2. The experimental device for treating flocculent slurry by vacuum preloading combined with electroosmosis according to claim 1, characterized in that: The plastic steel wire hose is provided with a valve for controlling the amount of water entering the suction filtration container and the amount of gas extracted by the vacuum pump.

3. The experimental device for treating flocculent slurry by vacuum preloading combined with electroosmosis according to claim 1, characterized in that: The mud model system comprises a base located on the ground, a visual mud pool located on the base, and an inner bracket located in the visual mud pool and fixing the improved drainage body.

4. The experimental device for treating flocculent slurry by vacuum preloading combined with electroosmosis according to claim 1, characterized in that: The electroosmosis system includes a DC power supply, which is connected to the improved drainage body through a wire.

5. The experimental device for treating flocculent slurry by vacuum preloading combined with electroosmosis according to claim 1, characterized in that: The data acquisition system includes a water level gauge located outside the filtration container, a scale located in the visual mud pool, a pore water pressure gauge located in the visual mud pool and connected to the data acquisition equipment through a wire, and a pressure gauge located on the top of the filtration container and used to detect the pressure in the filtration container.

6. A method for treating flocculent slurry by vacuum preloading combined with electroosmosis, using the apparatus for treating flocculent slurry by vacuum preloading combined with electroosmosis according to any one of claims 1 to 5, characterized in that: The method includes the following steps: Step 1: Load the floc slurry to be dehydrated into a visual mud pool, arrange the improved drainage body and the pore water pressure gauge, seal the top surface of the floc slurry with a sealing membrane, and make pressure grooves on all sides; Step 2: Start the vacuum preloading system, temporarily close the valve on the filtration container connected to the mud pool, and open the valve when the vacuum negative pressure of the filtration container reaches -85KPa; when the dehydration rate is lower than 1000ml / h, proceed to step 3; Step 3: According to the design plan, connect the electrodes of the DC power supply to the wires on the improved drainage body, and use the electrodes to convert into cathode and anode to perform vacuum preloading and combined electroosmosis deep dehydration on the mud. When the mud surface settlement and dehydration amount are stable, stop the test; Step 4: After stopping the test, recycle the equipment; organize the pore water pressure data, dehydration data and mud surface settlement data during the test; take soil at different spatial positions and test the moisture content.

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