CN113338262A - Three-dimensional electroosmosis consolidation soft soil water collecting and draining device and construction method thereof - Google Patents
Three-dimensional electroosmosis consolidation soft soil water collecting and draining device and construction method thereof Download PDFInfo
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- CN113338262A CN113338262A CN202110549412.0A CN202110549412A CN113338262A CN 113338262 A CN113338262 A CN 113338262A CN 202110549412 A CN202110549412 A CN 202110549412A CN 113338262 A CN113338262 A CN 113338262A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/11—Improving or preserving soil or rock, e.g. preserving permafrost soil by thermal, electrical or electro-chemical means
Abstract
The invention discloses a three-dimensional electroosmosis consolidation soft soil water collecting and draining device and a construction method thereof, wherein the three-dimensional electroosmosis consolidation soft soil water collecting and draining device comprises a water collecting well, a cathode tube, anode section steel and a non-conductive sealing element, the cathode tube is concentrically arranged in the water collecting well and is connected with a power supply cathode, the anode section steel is vertically and uniformly distributed around the water collecting well and is connected with a power supply anode in parallel, the sealing element is positioned at the bottom of the water collecting well and is used for fixing the cathode tube, a water pumping device is externally connected to the top of the cathode tube, perforated tube sections are uniformly distributed at through holes at the bottom of the cathode tube, the lower part of each perforated tube section penetrates through the water collecting well and the sealing element and extends into soil to be solidified, and the upper part of each perforated tube section is left in the water collecting well; after the power is switched on, the anode section steel forms an electroosmosis anode, the perforated pipe section in contact with the soil body forms an electroosmosis cathode, and the formed current direction is that the periphery is inclined downwards. The invention realizes the three-dimensional electroosmosis effect of electroosmosis, and ensures three-dimensional seepage flow through the three-dimensional circuit, thereby achieving the three-dimensional electroosmosis drainage effect and improving the electroosmosis efficiency.
Description
Technical Field
The invention relates to a drainage device, in particular to a three-dimensional electroosmosis consolidation soft soil water collecting and drainage device and a construction method thereof.
Background
Due to the shortage of urban construction land, people pay attention to sea filling and land reclamation, mudflat development, building groups on soft soil foundations and the like, but the soft clay cannot meet the construction requirements of buildings due to the defects of high water content, low permeability, low strength and the like, and needs to be subjected to rapid drainage consolidation treatment.
The drainage consolidation method is a common method for treating soft soil foundation at present, and mainly comprises preloading, vacuum preloading, electroosmosis drainage consolidation and the like. The preloading is to apply preloading load to the foundation before building a building, so that partial foundation settlement is completed in advance by soil body, the soil particles are gathered by the preloading load, the pore pressure is reduced, the effective stress of the soil body is increased, the bearing capacity of the soil body is improved, and the settlement generated by factor consolidation is reduced. The vacuum preloading is to lay a sand cushion layer on a pretreated clay layer and seal the sand cushion layer by using a plastic film, then vacuumize the sealing film by using a vacuum pump, discharge water and gas in soil out of the soil body through the pressure difference generated inside and outside the film, reduce the underground water level and achieve the purpose of quickly solidifying the soft soil foundation; due to the hydraulic conductivity coefficient of the soil body, the problems of slow drainage consolidation, damaged vacuum degree transmission in the later period, clogging of the plastic drainage plate and the like in the soft clay foundation treatment cause the preloading and the vacuum preloading to be incapable of achieving the expected effect.
The electroosmosis drainage consolidation method is characterized by that in the soil body an electrode is inserted, and after the direct current is applied, the pore water in the soil body can be moved from anode to cathode under the action of electric field so as to attain the goal of soil body drainage consolidation. In 1939, Casagrand applied the electroosmosis method to geotechnical engineering for the first time, Esrig proposed the one-dimensional consolidation theory of electroosmosis in 1968, and Sujin in 2004 provided the solution of the two-dimensional electroosmosis consolidation theory under different boundary conditions by using a blocking treatment method on the basis of the Esrig one-dimensional electroosmosis consolidation theory. The electroosmosis drainage consolidation method is mainly used for treating a soft soil foundation with high water content and low permeability, has the advantages of high consolidation speed, high safety, small pollution and the like compared with the traditional foundation treatment method, but only mainly uses indoor experimental research at present due to the problems of high energy consumption, serious electrode corrosion, lack of a reasonable field design method and the like, cannot be applied to actual engineering and limits the development of electroosmosis consolidation.
Therefore, it is desired to solve the above problems.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a three-dimensional electroosmosis consolidation soft soil collection and drainage device which achieves a three-dimensional electroosmosis drainage effect and effectively improves electroosmosis efficiency.
The second purpose of the invention is to provide a construction method of the three-dimensional electroosmosis consolidation soft soil water collecting and draining device.
The technical scheme is as follows: in order to achieve the purpose, the invention discloses a three-dimensional electroosmosis consolidation soft soil collection and drainage device which comprises a vertically arranged water collecting well, a cathode tube, anode section steel and a non-conductive sealing element, wherein the cathode tube is concentrically arranged in the water collecting well and is connected with a power supply cathode, the anode section steel is vertically and uniformly distributed around the water collecting well and is connected with a power supply anode in parallel, the sealing element is positioned at the bottom of the water collecting well and is used for fixing the cathode tube, a water pumping device is externally connected to the top of the cathode tube, the bottom of the cathode tube is provided with perforated tube sections uniformly distributed in through holes, the lower parts of the perforated tube sections penetrate through the water collecting well and the sealing element and extend into soil to be solidified, and the upper parts of the perforated tube sections are left in the water collecting well; after the power is switched on, the anode section steel forms an electroosmosis anode, the perforated pipe section in contact with the soil body forms an electroosmosis cathode, and the formed current direction is that the periphery is inclined downwards.
The water collecting well is formed by splicing a plurality of water collecting well sections, the cathode tube is formed by splicing a plurality of cathode tube sections, and the splicing position of the water collecting well and the splicing position of the cathode tube are positioned on the same horizontal plane.
Preferably, two adjacent water collecting well sections are connected through a nut part and a bolt part, wherein the nut part and the bolt part are respectively of an integrally formed structure with the water collecting well sections, and the bolt part is provided with a cross opening.
Furthermore, the concatenation department on sump pit upper portion is equipped with the support ring, should support the ring including linking to each other the cover with the sump pit and establish the support outer loop on nut portion, establish the support inner ring outside the cathode tube and be used for the support outer loop of joint support and support inner ring and the support arm that the equipartition set up, this support arm and cross opening looks adaptation.
Furthermore, the splicing part at the lower part of the water collecting well is provided with a conductive ring, the conductive ring comprises a conductive outer ring which is connected with the water collecting well and is sleeved on the nut part, a conductive inner ring which is sleeved outside the cathode tube and is contacted with the cathode tube and is connected with the cathode tube to form a passage, and conductive support arms which are used for connecting the conductive outer ring and the conductive inner ring and are uniformly distributed, and the conductive support arms are matched with the cross-shaped opening.
Preferably, the distance between the conductive ring at the uppermost end and the surface of the soil body to be solidified is 3-5 m.
Furthermore, a plurality of openings for water to permeate are uniformly distributed on the outer wall of the water collecting well.
Further, the outer wall of the water collecting well is sequentially wrapped with geotechnical filter cloth and a steel wire cage.
Preferably, the power supply is a direct current power supply, and the potential gradient between the positive electrode and the negative electrode of the power supply is 1-2V/cm.
The invention relates to a construction method of a three-dimensional electroosmosis consolidation soft soil water collecting and draining device, which comprises the following steps:
(1) prefabricating a water collecting well section and a cathode pipe section, and transporting to a construction site;
(2) determining the position of a water collecting well, excavating in advance, assembling the water collecting well in sections, and assembling a sealing element; and sequentially wrapping geotechnical filter cloth and a steel wire cage outside the water collecting well wall, and then putting the water collecting well into a pre-dug well.
(3) Assembling the cathode tubes in sections, inserting the assembled cathode tubes from the central point of the water collecting well, wherein the length of the cathode tubes inserted into the soil body and contacted with the soil body is at least 40 cm;
(4) the position of the anode in the three-dimensional space is determined according to the power supply voltage of the horizontal potential gradient of 1-2V/cm and the practical use through the position of the cathode tube, and the specific algorithm is as follows: the distance between the anode section steel and the cathode tube is equal to the actual power supply voltage divided by the horizontal potential gradient; anode section steel is uniformly distributed according to the distance from the anode section steel to the cathode tubes, each side of the section steel is enclosed into a polygon, and the cathode tubes are positioned at the center of the polygon; the positive electrode of the power supply is connected with the top of the cathode tube through a lead, and the negative electrode of the power supply is connected with the top of the anode section steel in parallel;
(5) connecting the cathode tube with an external timing drainage device;
(6) and electrifying to start electroosmosis, wherein the water discharge of the single timing water pumping device is matched with the electroosmosis water discharge.
Has the advantages that: compared with the prior art, the invention has the following remarkable advantages:
(1) the invention adopts a three-dimensional parallel circuit, the anode adopts at least 3 strip-shaped anode section steels and is connected with the positive pole of a power supply through parallel connection; the top end of the cathode tube is connected with the negative electrode of the power supply through a lead, and the perforated tube section at the bottom of the cathode tube and the conductive ring are used as the cathode of the electroosmosis power supply; because the length of the anode section steel is longer, and the cathodes are arranged at the bottom of the water collecting well and the conductive circular rings distributed at the lower part of the water collecting well, the formed current direction is inclined downwards, the three-dimensional electroosmosis effect of electroosmosis is realized, and the three-dimensional seepage is ensured through a three-dimensional circuit, so that the three-dimensional electroosmosis drainage effect is achieved, and the electroosmosis efficiency is improved;
(2) the water collecting well can collect water flowing to the cathode in the electroosmosis process, so that the water displacement of the single timing water pumping device is matched with the water displacement of electroosmosis; the method can prevent a large amount of energy loss caused by the water accumulation phenomenon caused by the electro-osmosis efficiency which is far higher than the drainage efficiency, and can prevent a large amount of energy consumption caused by the ineffective operation of the water pumping device caused by the drainage efficiency which is far higher than the electro-osmosis efficiency; in addition, after the water is drained at regular time, due to the formation of the difference between the internal water head and the external water head of the water collecting well, the hydraulic seepage gradient can be increased, the water seepage efficiency is further increased, and the total drainage efficiency is improved;
(3) the invention breaks through the uniform and two-dimensional electro-osmosis idea, utilizes the anode ring type arrangement and the water storage design of the water collecting well, forms a water head difference inside and outside the water collecting well after completing water pumping, combines hydraulic osmosis and electric seepage, achieves the effect of the two cooperating with three-dimensional seepage, and greatly improves the drainage consolidation efficiency;
(4) according to the invention, the geotechnical filter cloth and the steel wire cage are arranged on the outer side of the well wall to ensure high-efficiency migration of water, avoid unnecessary energy consumption, and have a wide engineering application prospect by utilizing the low cost of the geotechnical filter cloth and the steel wire cage.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic view of the sump according to the present invention;
FIG. 3 is a partial schematic view of a cathode ray tube according to the present invention;
FIG. 4 is a schematic view of the cathode tube assembly according to the present invention;
FIG. 5 is a schematic illustration of the assembly of a sump well with support rings according to the present invention;
FIG. 6 is a schematic view of a support ring according to the present invention;
FIG. 7 is a schematic view of the assembly of the support ring of the present invention;
FIG. 8 is a top plan view of a water collection well block joint according to the present invention;
FIG. 9 is a top view of a water collection interval with support rings of the present invention;
FIG. 10 is a schematic view of a conductive ring according to the present invention;
FIG. 11 is a schematic view of the assembly of the conductive ring of the present invention;
FIG. 12 is a top view of a water collection interval splice with conductive rings of the present invention;
FIG. 13 is a schematic structural view of the anode-type steel of the present invention;
FIG. 14 is a schematic diagram showing the current values during electroosmosis of lake bed sludge in group S1 according to the present invention;
FIG. 15 is a schematic view showing the amount of water discharged during electroosmosis of lake bed mud in Taihu lake of group S1 according to the present invention;
FIG. 16 is a schematic representation of the total energy consumption during electroosmosis of the lake Tai sediment of group S1 according to the present invention;
FIG. 17 is a graph showing current values during electroosmosis of soft clay in group C1 in accordance with the present invention;
FIG. 18 is a schematic representation of the amount of water displaced during electroosmosis of soft clay in group C1 in accordance with the present invention;
FIG. 19 is a schematic representation of the total energy consumption during electroosmosis of soft clay in group C1 in accordance with the present invention;
FIG. 20 is a graph showing current values during electroosmosis of soft clay in group C2 in accordance with the present invention;
FIG. 21 is a schematic representation of the amount of water displaced during electroosmosis of soft clay in group C2 in accordance with the present invention;
FIG. 22 is a schematic representation of the total energy consumption during electroosmosis of soft clay in group C2 in accordance with the present invention;
FIG. 23 is a schematic diagram showing the variation of the energy consumption of the pumping point in the case of the S1 group and the C1 group in the present invention.
Detailed Description
The technical scheme of the invention is further explained by combining the attached drawings.
As shown in figure 1, the three-dimensional electroosmosis consolidation soft soil collection and drainage device comprises a water collecting well 1, a cathode tube 2, anode section steel 3, a sealing element 4, a supporting ring 6, a conductive ring 7, geotechnical filter cloth 8, a steel wire cage 9, a power supply and a drainage device.
As shown in fig. 2, the water collecting well 1 is vertically arranged in the soil body, the water collecting well 1 is formed by splicing a plurality of water collecting well sections 101, the outer diameter of the well wall of the water collecting well 1 can be 15cm, the wall thickness of the water collecting well 1 can be 2cm, and the material can be long glass fiber reinforced polypropylene; the outer wall equipartition of sump pit 1 has the trompil of a plurality of water supply infiltration, and the outer wall of sump pit 1 wraps up geotechnological filter cloth 8 and steel wire cage 9 in proper order, sets up geotechnological filter cloth and steel wire cage outside the wall of a well and guarantees the high-efficient migration of water, avoids the production of unnecessary energy consumption. The splicing part of two adjacent water collecting well sections 101 is respectively provided with a nut part 102 and a bolt part 103, the two adjacent water collecting well sections 101 are connected through the nut part 102 and the bolt part 103, wherein the nut part 101 and one water collecting well section are of an integrally formed structure, the bolt part 103 and the other water collecting well section are of an integrally formed structure, and a cross-shaped opening 104 is formed in the bolt part 103.
As shown in fig. 3 and 4, the cathode tube 2 is inserted into the water collection well 1 along the central axis of the water collection well 1, and the cathode tube 2 is disposed concentrically with the water collection well 1. The top of the cathode tube 2 is provided with a power line interface 203, the power line interface 203 is connected with the negative pole of a power supply, the top of the cathode tube 2 is also provided with a water pumping port 204, the water pumping port 204 is connected with a drainage device, the drainage device is a jet pump 10, and the jet pump can be set to pump water at regular time. The cathode tube 2 is formed by splicing a plurality of cathode tube sections 202, the length of each section of cathode tube is 1-1.1 m, the outer diameter of the cathode tube is 6cm, the tube thickness is 0.8-1 cm, the cathode tube can be a cathode titanium tube, the cathode tube is a hollow metal electrode, and the functions of serving as a circuit cathode, transversely absorbing water and longitudinally draining water are considered simultaneously. And the splicing position of the water collecting well 1 and the splicing position of the cathode tube 2 are positioned on the same horizontal plane, the splicing positions of two adjacent sections of cathode tube sections 202 are respectively provided with a nut 205 and a bolt 206, the two adjacent sections of cathode tube sections 202 are connected through the nut 205 and the bolt 206, wherein the nut 205 and one section of cathode tube section are of an integrally formed structure, and the bolt 206 and the other section of cathode tube section are of an integrally formed structure. The bottom of the cathode tube 2 is provided with perforated tube sections 201 uniformly distributed in the through hole, the lower parts of the perforated tube sections 201 penetrate through the water collecting well 1 and the sealing element 4 and extend into the soil body 5 to be solidified, the upper parts of the perforated tube sections 201 are remained in the water collecting well 1, and the perforated tube sections 201 contacted with the soil body guide water into the cathode tube 2 and flow upwards until the water flows into the water collecting well 1; the total number of the cathode tubes 1 is determined according to the soil body, the perforated tube section 201 is of a net-shaped hollow structure, wherein the perforated tube section 201 in contact with the soil body is at least 40cm, the perforated tube section 201 remained in the water collecting well is at least 2cm, when the length of the perforated tube section 201 is 50cm, the perforated tube section 201 in contact with the soil body is 45cm, and the perforated tube section 201 remained in the water collecting well is 5 cm. The length of each other cathode tube section 202 is 1 m-1.1 m, and each two cathode tube sections are bolted by using threads.
As shown in fig. 13, a plurality of anode section steels 3 are vertically and evenly distributed in the soil around the water collecting well 1, the anode section steels 3 are connected with the positive electrode of the power supply in parallel, that is, the anode section steels 3 are provided with threading holes 301, and the threading holes 301 are connected with the positive electrode of the power supply through power lines. The number of the anode section steels 3 can be 3, when 3 anode section steels are adopted, the cross sections of the anode section steels are V-shaped, the angle of the V-shaped structure is 60 degrees, three V-shaped anode section steels surround an equilateral triangle, and the water collecting well 1 is positioned at the center of the equilateral triangle; the number of the anode section steels can be 4, when 4 anode section steels are adopted, the cross sections of the anode section steels are L-shaped, namely the anode section steels are of angle steel structures, the angles of the L-shaped structures are 90 degrees, four L-shaped anode section steels surround a quadrangle, and the water collecting well 1 is positioned at the center of the quadrangle; according to the invention, the number of the anode section steels can be 5, when 5 anode section steels are adopted, the cross section of the anode section steel is of a V-shaped structure, the angle of the V-shaped structure is 108 degrees, 5V-shaped anode section steels surround a pentagon, and the water collecting well 1 is positioned at the center of the pentagon; the number of the anode section steel can be 6, when 6 anode section steels are adopted, the cross section of the anode section steel is of a V-shaped structure, the angle of the V-shaped structure is 120 degrees, 6V-shaped anode section steels surround a hexagon, and the water collecting well 1 is positioned at the center of the hexagon; by analogy, the number of the anode section steel is at least 3.
The power supply is a direct current power supply 11, and the potential gradient between the anode and the cathode of the power supply is 1-2V/cm. Sealing member 4 is located the bottom of sump pit 1, and sealing member 4 is used for fixed cathode tube 2, and sealing member 4 is the working of plastics, and itself is the non-conducting, and four 5 ~ 8cm high plastic sheets can be chooseed for use to the working of plastics. In the invention, after being electrified, the anode section steel 3 forms an electroosmosis anode, the perforated pipe section 201 in contact with the soil body forms an electroosmosis cathode, and the formed current direction is inclined downwards; the invention adopts a three-dimensional parallel circuit, the anode adopts at least 3 strip-shaped anode section steels and is connected with the anode of a power supply in parallel; the top end of the cathode tube is connected with the negative electrode of the power supply through a lead, and the perforated tube section at the bottom of the cathode tube and the conductive ring are used as the cathode of the electroosmosis power supply; because the length of the anode section steel is longer, and the cathodes are arranged at the bottom of the water collecting well and the conductive circular rings distributed at the lower part, the formed current direction is inclined downwards, the three-dimensional electroosmosis effect of electroosmosis is realized, the three-dimensional seepage is ensured through a three-dimensional circuit, the three-dimensional electroosmosis drainage effect is realized, and the electroosmosis efficiency is improved.
As shown in fig. 5, 6, 7, 8 and 9, a support ring 6 is disposed at a joint of an upper portion of the water collecting well 1, the support ring 6 includes a support outer ring 601, a support inner ring 602 and support arms 603, the support outer ring 601 is connected to the water collecting well 1, the support outer ring 601 is sleeved on the nut portion 102, the support inner ring 602 is sleeved outside the cathode tube 2, the support arms 603 are used for connecting the support outer ring 601 and the support inner ring 602, the support arms 603 are uniformly disposed between the support outer ring 601 and the support inner ring 602, the support arms 603 are adapted to the cross opening 104, and all three of the support outer ring 601, the support inner ring 602 and the support arms 603 are made of non-conductive material.
As shown in fig. 10, 11 and 12, a conductive ring 7 is arranged at the splicing position of the lower part of the water collecting well 1, and the distance from the conductive ring 7 at the uppermost end to the surface of the soil body to be solidified is 3-5 m. The conductive ring 7 comprises a conductive outer ring 701, a conductive inner ring 702 and a conductive support arm 703, wherein the conductive outer ring 701 is connected with the water collecting well 1, the conductive outer ring 701 is sleeved on the nut part 102, the conductive inner ring 702 is sleeved outside the cathode tube 2, the conductive inner ring 702 is in contact with the cathode tube 2 and connected into a passage, the conductive support arm 703 is used for connecting the conductive outer ring 701 and the conductive inner ring 702, the conductive support arm 703 is uniformly distributed between the conductive outer ring 701 and the conductive inner ring 702, the conductive support arm 703 is matched with the cross-shaped opening 104, and the conductive outer ring 701, the conductive inner ring 702 and the conductive support arm 703 are all made of conductive materials, wherein the conductive outer ring 701 and the conductive support ring 601 have the same structure and are only made of different materials; the conductive inner ring 702 and the support inner ring 602 have the same structure, and are different only in material; the conductive support arm 703 and the support arm 603 have the same structure, but the difference is only in the material difference, and the conductive material can be titanium alloy.
The water collecting well can collect water flowing to the cathode in the electroosmosis process, so that the water displacement of the single timing water pumping device is matched with the water displacement of electroosmosis; the method can prevent a large amount of energy loss caused by the water accumulation phenomenon caused by the electro-osmosis efficiency which is far higher than the drainage efficiency, and can prevent a large amount of energy consumption caused by the ineffective operation of the water pumping device caused by the drainage efficiency which is far higher than the electro-osmosis efficiency; in addition, after the water is drained at regular time, the hydraulic seepage gradient can be increased due to the formation of the difference of the water heads inside and outside the water collecting well, the water seepage efficiency is further increased, and the total drainage efficiency is improved.
The invention discloses a construction method of a three-dimensional electroosmosis consolidation soft soil water collecting and draining device, which is characterized by comprising the following steps of:
(1) prefabricating a water collecting well section and a cathode pipe section, and transporting to a construction site;
(2) determining the position of a water collecting well, excavating in advance, assembling the water collecting well in sections, and assembling a sealing element; and sequentially wrapping geotechnical filter cloth and a steel wire cage outside the water collecting well wall, and then putting the water collecting well into a pre-dug well.
(3) Assembling the cathode tubes in sections, inserting the assembled cathode tubes from the central point of the water collecting well, wherein the length of the cathode tubes inserted into the soil body and contacted with the soil body is at least 40 cm;
(4) the position of the anode in the three-dimensional space is determined according to the power supply voltage of the horizontal potential gradient of 1-2V/cm and the practical use through the position of the cathode tube, and the specific algorithm is as follows: the distance between the anode section steel and the cathode tube is equal to the actual power supply voltage divided by the horizontal potential gradient; anode section steel is uniformly distributed according to the distance from the anode section steel to the cathode tubes, each side of the section steel is enclosed into a polygon, and the cathode tubes are positioned at the center of the polygon; the positive electrode of the power supply is connected with the top of the cathode tube through a lead, and the negative electrode of the power supply is connected with the top of the anode section steel in parallel;
(5) connecting the cathode tube with an external timing drainage device;
(6) and electrifying to start electroosmosis, wherein the water discharge of the single-time timing water pumping device is matched with the electroosmosis water discharge, for example, the electroosmosis time is set to be about 4 hours to reach an energy consumption inflection point, and the starting time of the water pumping device at each time is about 2 minutes to finish water pumping.
The invention adopts a three-dimensional electroosmosis consolidation soft soil water collecting and draining device to perform a three-dimensional penetration consolidation test on the lake bed mud with high water content and soft clay, the test size is 50cm x 25cm, the traditional one-dimensional electroosmosis draining test is used as a control test, and the control group is a small-size test, and the size is 20cm x 10 cm. The test conditions are shown in table 1.
TABLE 1 test conditions
And S1 group adopts the three-dimensional electroosmosis consolidation soft soil collection and drainage device to perform experimental research on the lake Tai sediment with high organic matters.
The applied voltage of the test of group S1 was 30V, and the initial water content was 55%. During the experiment, the accumulated water in the water collecting well is extracted once every 8 hours so as to achieve the effect of draining water.
The current values during the electroosmosis of the lake Tai sediment are shown in FIG. 14, and the maximum current value is 1947mA and the minimum current value is 840 mA. As shown in fig. 14, at the beginning of the electroosmosis test, the current value gradually decreases because the electroosmosis test just starts to drain water, water is not accumulated in the water collecting well, and the resistance of the soil body gradually increases, so that the current value decreases; the current value then increases gradually, since the water fraction expelled by electroosmosis starts to accumulate in the water collection well, and the resistance value in the electric field decreases gradually due to the accumulation of water, resulting in a gradually increasing current value, which also increases the efficiency of electroosmosis gradually. After every 8 hours of water withdrawal, the current value decreased sharply and increased gradually as the water accumulated again, and the process was repeated throughout the electroosmosis process. As shown in fig. 14, the value of the lowest current value after each water pumping is gradually reduced along with the increase of the water drainage times, because the total resistance value of the soil body is gradually increased due to the drainage of the water in the soil body, so that the current value is gradually reduced.
The water discharge in the electroosmosis process of the lake Tai sediment is shown in FIG. 15, the final water discharge in the electroosmosis test for 80h is 6483mL, and the water discharge efficiency is 16.20%. As shown in fig. 15, the water discharge in the electroosmosis process gradually decreases in the rate of increase with time. Because of the electroosmosis in-process, its soil body total resistance increases gradually, and along with the progress of electroosmosis process, the ion in the soil body is discharged gradually, and electroosmosis efficiency reduces gradually, and this phenomenon accords with the basic rule of electroosmosis test.
The total energy consumption in the electroosmotic process can be calculated by the following formula:
E＝∫UIdt
wherein E is total energy consumption in the electroosmosis process, W.h; u is the applied voltage in the electroosmosis process, V; i is the total current in the electroosmotic system, a; t is electroosmosis time, h.
The total energy consumption in the electroosmosis process of the lake Tai sediment is shown in FIG. 16, and the total energy consumption in the electroosmosis process shows a continuously rising trend. Meanwhile, the increase rate of the energy consumption is gradually increased between the pumping intervals of 8 h; after the pumping is completed, the increase rate is suddenly reduced and then gradually increased, which is directly related to the change trend of the current. The phenomenon that the energy consumption is increased and the efficiency is suddenly reduced after water pumping is proved again, and the application of the water collecting well in the device and the test method for regularly pumping water are beneficial to reducing the total energy consumption in the electroosmosis process, can play the fundamental roles of reducing the energy consumption and reducing the emission. The total energy consumption in the S1 group is 2604 W.h, the volume of the soil sample in the device is 6.25 x 10-2 cubic meters, the water drainage energy consumption per unit volume is 41.646 kW.h/m 3, and the water drainage energy consumption per unit volume is 6.423 W.h/(m 3 mL).
In group C1, the three-dimensional electroosmosis consolidation soft soil collection and drainage device of the present invention was used to perform experimental studies on soft clay that can be used as a soft soil foundation.
In group C1, the applied voltage was 30V, and the initial water content was 55%.
The current values during electroosmosis of the soft clay are shown in FIG. 17, with the maximum value of 1557mA and the minimum value of 513 mA. As shown in fig. 17, the change rule of the current value in the electroosmosis process of the soft clay is basically consistent with that of the lake Tai sediment, and the current value is basically similar, which shows that the design device has almost the same function for different soil bodies.
As shown in FIG. 18, the total amount of water discharged during electroosmosis of the soft clay was 6433mL, and the water discharge efficiency was 19.49%. The change rule of the water discharge of the embodiment is basically consistent with the change rule of the lake Tai sediment group. During the electroosmosis test of the soft clay, the initial drainage rate is greater than that of the lake Tai sediment, which is caused by the larger current value during the electroosmosis process of the soft clay; but the drainage rate gradually decreased in the later period of the test of the soft clay, resulting in the final drainage of almost the same amount as that of the lake Taihu sediment.
The total energy consumption in the soft clay electroosmosis process is shown in fig. 19, and the energy consumption change rule of the embodiment is basically consistent with the energy consumption change rule of the lake Tai sediment group. The total electroosmotic energy consumption of group C1 was 2488 W.h. The volume of the soil sample in the device is 6.25 x 10-2 cubic meters, the water discharge energy consumption per unit volume is 39.808 kW.h/m 3, and the water discharge energy consumption per unit volume is 6.188 W.h/(m 3. mL). The numerical value of the device is nearly the same as the energy consumption value of the lake Tai sediment group, which shows that the electroosmosis effect of the device on different soil bodies is nearly the same.
Group C2 used a conventional one-dimensional electroosmotic drainage test as a control.
In group C2, the applied voltage was 30V, and the initial water content was 55%.
The current value in the soft clay electroosmosis process is shown in fig. 20, and the current value in the traditional one-dimensional electroosmosis test always shows a gradually decreasing trend, because the total resistance value gradually increases along with the progress of the electroosmosis process in the electroosmosis process, the corresponding current value is reduced along with the gradual increase, the maximum value of the current is 254mA, and the minimum value is 39 mA.
Under the condition that the applied voltage and the initial water content are the same, the current value of the lake Tai sediment is higher than that of the soft clay; when the device is used, the test scale is larger, the water content is higher, the device is a parallel circuit, the test current value is always larger than that of the traditional one-dimensional electroosmosis test, and the electroosmosis efficiency is always higher than that of one-dimensional seepage.
The water displacement during the conventional one-dimensional electroosmosis test is shown in fig. 21, the final displacement of C2 is 314mL,
the total energy consumption in the conventional one-dimensional electroosmosis process is shown in fig. 22, and the total energy consumption in the electroosmosis process shows a trend of continuously increasing, but when the device of the present invention is used, the increase rate of the energy consumption between the pumping intervals of 8h gradually increases, and after the pumping is completed, the increase rate thereof is suddenly reduced and then gradually increased, which is directly related to the change trend of the current, so that a fluctuation situation of increasing and decreasing the energy consumption occurs, as shown in fig. 23. The phenomenon that the energy consumption is increased and the efficiency is suddenly reduced after water pumping is proved again, and the application of the multifunctional water collecting well in the device and the design of timed water pumping are beneficial to reducing the total energy consumption in the electroosmosis process and can play the fundamental roles of reducing the energy consumption, saving energy and reducing emission.
Table 2 shows the total energy consumption, the volume of the soil sample, the energy consumption per unit volume of water discharged and the energy consumption per unit volume of water discharged for each set of tests. By adopting the design device, the final unit energy consumption of the lake Tai sediment and the soft clay is approximately the same, and the comparison with C2 shows that the unit volume water drainage energy consumption and the unit volume water drainage energy consumption of S1 and C1 are far lower than those of C2, and the unit volume water drainage energy consumption of C2 are respectively 1.5 times and 30 times of those of S1 and C1. Therefore, the electroosmosis efficiency of the three-dimensional consolidation device designed by the work is far higher than that of a traditional one-dimensional electroosmosis test, and the three-dimensional consolidation device has very obvious energy-saving and emission-reducing effects on different soil bodies.
TABLE 2 Experimental energy consumption for each group
The test result shows that the unit volume unit drainage energy consumption of the system is about 1/30 of a one-dimensional electroosmosis system, and the system has a remarkable energy-saving effect in the drainage consolidation of the soft foundation.
Claims (10)
1. The utility model provides a three-dimensional electroosmosis concreties soft soil collection drainage device which characterized in that: the device comprises a water collecting well (1) which is vertically arranged, cathode tubes (2) which are concentrically arranged in the water collecting well and are connected with a power supply cathode, anode section steel (3) which is vertically and uniformly distributed around the water collecting well and is connected with a power supply anode in parallel, and a sealing element (4) which is positioned at the bottom of the water collecting well, is used for fixing the cathode tubes and is not conductive, wherein a water pumping device is externally connected to the top of each cathode tube (2), perforated tube sections (201) which are uniformly distributed in through holes are arranged at the bottom of each cathode tube (2), the lower parts of the perforated tube sections (201) penetrate through the water collecting well (1) and the sealing element (4) and extend into a soil body (5) to be solidified, and the upper parts of the perforated tube sections (201) are left in the water collecting well (1); after the power is switched on, the anode section steel (3) forms an electroosmosis anode, the perforated pipe section (201) contacted with the soil body forms an electroosmosis cathode, and the formed current direction is that the periphery is inclined downwards.
2. The three-dimensional electro-osmotic consolidated soft soil collection and drainage device of claim 1, wherein: the collector well (1) is formed by splicing a plurality of collector well sections (101), the cathode tube (2) is formed by splicing a plurality of cathode tube sections (202), and the splicing position of the collector well (1) and the splicing position of the cathode tube (2) are positioned on the same horizontal plane.
3. The three-dimensional electro-osmotic consolidated soft soil collection and drainage device of claim 2, wherein: two adjacent water collecting well sections (101) are connected through a nut part (102) and a bolt part (103), wherein the nut part (101) and the bolt part (103) are respectively of an integrally formed structure with the water collecting well sections (101), and the bolt part (103) is provided with a cross opening (104).
4. The three-dimensional electro-osmotic consolidated soft soil collection and drainage device of claim 3, wherein: the splicing department on sump pit (1) upper portion is equipped with supports ring (6), should support ring (6) including link to each other with the sump pit and establish support outer ring (601) in nut portion, establish support inner ring (602) of establishing outside the cathode tube and be used for connecting support outer ring and support inner ring and support arm (603) that the equipartition set up, this support arm (603) and cross opening (104) looks adaptation.
5. The three-dimensional electro-osmotic consolidated soft soil collection and drainage device of claim 3, wherein: the conductive ring (7) is arranged at the splicing position of the lower part of the water collecting well (1), the conductive ring (7) comprises a conductive outer ring (701) which is connected with the water collecting well and sleeved on the nut part, a conductive inner ring (702) which is sleeved outside the cathode tube and is contacted with the cathode tube and connected into a passage, and conductive support arms (703) which are used for connecting the conductive outer ring and the conductive inner ring and are uniformly distributed, and the conductive support arms (703) are matched with the cross-shaped opening (104).
6. The three-dimensional electro-osmotic consolidated soft soil collection and drainage device of claim 5, wherein: the distance between the conductive ring (7) at the uppermost end and the surface of the soil body to be solidified is 3-5 m.
7. The three-dimensional electro-osmotic consolidated soft soil collection and drainage device of claim 1, wherein: the outer wall of the water collecting well (1) is uniformly provided with a plurality of open pores for water to permeate.
8. The three-dimensional electro-osmotic consolidated soft soil collection and drainage device of claim 7, wherein: the outer wall of the water collecting well (1) is sequentially wrapped with geotechnical filter cloth (8) and a steel wire cage (9).
9. The three-dimensional electro-osmotic consolidated soft soil collection and drainage device of claim 1, wherein: the power supply is a direct current power supply (10), and the potential gradient between the positive electrode and the negative electrode of the power supply is 1-2V/cm.
10. A method of constructing a three-dimensional electro-osmotic consolidated soft soil catchment and drainage device according to any of claims 1 to 9, comprising the steps of:
(1) prefabricating a water collecting well section and a cathode pipe section, and transporting to a construction site;
(2) determining the position of a water collecting well, excavating in advance, assembling the water collecting well in sections, and assembling a sealing element; and sequentially wrapping geotechnical filter cloth and a steel wire cage outside the water collecting well wall, and then putting the water collecting well into a pre-dug well.
(3) Assembling the cathode tubes in sections, inserting the assembled cathode tubes from the central point of the water collecting well, wherein the length of the cathode tubes inserted into the soil body and contacted with the soil body is at least 40 cm;
(4) the position of the anode in the three-dimensional space is determined according to the power supply voltage of the horizontal potential gradient of 1-2V/cm and the practical use through the position of the cathode tube, and the specific algorithm is as follows: the distance between the anode section steel and the cathode tube is equal to the actual power supply voltage divided by the horizontal potential gradient; anode section steel is uniformly distributed according to the distance from the anode section steel to the cathode tubes, each side of the section steel is enclosed into a polygon, and the cathode tubes are positioned at the center of the polygon; the positive electrode of the power supply is connected with the top of the cathode tube through a lead, and the negative electrode of the power supply is connected with the top of the anode section steel in parallel;
(5) connecting the cathode tube with an external timing drainage device;
(6) and electrifying to start electroosmosis, wherein the water discharge of the single timing water pumping device is matched with the electroosmosis water discharge.
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| ZA2021/09955A ZA202109955B (en) | 2021-05-20 | 2021-12-03 | Three-dimensional electroosmosis consolidated soft soil collection and drainage device and construction method therefor |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104831704A (en) * | 2015-05-19 | 2015-08-12 | 河海大学 | Electric osmosis and cathode vacuumizing combined soft soil reinforcement device and method |
| CN105714762A (en) * | 2016-02-01 | 2016-06-29 | 浙江大学 | Change-filling and tamping improved soft clay electroosmosis strengthening method |
| CN106988330A (en) * | 2017-05-06 | 2017-07-28 | 韩少鹏 | Soft soil foundation is layered dewatering construction structure and construction method |
| CN111827248A (en) * | 2020-03-26 | 2020-10-27 | 同济大学 | System and method for air bag expansion pressurization and vacuum-electroosmosis composite dewatering and dewatering in hole |
| CN111851463A (en) * | 2020-07-29 | 2020-10-30 | 金陵科技学院 | Foundation reinforcing method for soft soil field |
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2021
- 2021-05-20 CN CN202110549412.0A patent/CN113338262B/en active Active
- 2021-12-03 ZA ZA2021/09955A patent/ZA202109955B/en unknown
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104831704A (en) * | 2015-05-19 | 2015-08-12 | 河海大学 | Electric osmosis and cathode vacuumizing combined soft soil reinforcement device and method |
| CN105714762A (en) * | 2016-02-01 | 2016-06-29 | 浙江大学 | Change-filling and tamping improved soft clay electroosmosis strengthening method |
| CN106988330A (en) * | 2017-05-06 | 2017-07-28 | 韩少鹏 | Soft soil foundation is layered dewatering construction structure and construction method |
| CN111827248A (en) * | 2020-03-26 | 2020-10-27 | 同济大学 | System and method for air bag expansion pressurization and vacuum-electroosmosis composite dewatering and dewatering in hole |
| CN111851463A (en) * | 2020-07-29 | 2020-10-30 | 金陵科技学院 | Foundation reinforcing method for soft soil field |
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