Flocculation-vacuum-electroosmosis-dynamic compaction combined soft soil foundation treatment method

Abstract

The invention discloses a flocculation-vacuum-electroosmosis-dynamic compaction combined soft soil foundation treatment method which comprises the following steps: S1, adding a PAM (Polyacrylamide) flocculant into mud in a mud pit, and carrying out mud flocculation treatment; s2, inserting a drainage device into the flocculated slurry, wherein the drainage device is connected with a vacuum pump through a main drainage pipe; s3, electro-osmosis components are inserted into the slurry, the electro-osmosis components are composed of anode electro-osmosis components and cathode electro-osmosis components, the anode electro-osmosis components and the cathode electro-osmosis components are inserted into the slurry pool in a crossed and spaced mode, and the anode electro-osmosis components and the cathode electro-osmosis components are connected with corresponding external direct-current power sources through wires; s4, geotextile is laid on the upper surface of the slurry, a vacuum pump is turned on for vacuum preloading drainage, and an external direct-current power source is turned on for vacuum-electroosmosis combined drainage in the later period of vacuum preloading; and S5, dynamic compaction treatment is conducted, point compaction is conducted through a compaction machine, then full compaction is conducted, and the soft soil foundation is completed. According to the method, the soft soil foundation treatment efficiency is improved, and the good consolidation effect on the soil body is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of soft soil foundation reinforcement, in particular to a method for treating a soft soil foundation by combining flocculation, vacuum, electroosmosis and strong compaction. Background Art

[0002] At present, in order to ease the land shortage contradiction, coastal cities need to form a large amount of land through sea reclamation. The fill used for sea reclamation is generally made of dredged silt from harbors and waterways, which is hydraulically filled to form land sites. The moisture content is as high as 80% or more, and the newly filled sites can even reach about 200%. In addition, due to hydraulic sorting, the upper soil layer of the soft soil foundation has extremely fine particles, mainly clay and colloid particles, and the connection between particles is very weak. A strong soil skeleton structure has not yet been formed, and the soil particles have strong fluidity with water. Soft clay has many unfavorable engineering properties such as high water content, high compressibility, high thixotropy, and low shear strength. High compressibility will cause considerable settlement and settlement difference in the foundation; low permeability makes the settlement last for a long time, which may affect the normal use of buildings; low strength makes the bearing capacity and stability of the foundation often fail to meet engineering requirements. Therefore, how to effectively, quickly and economically reinforce such ultra-soft foundations has become a technical problem that must be solved.

[0003] Among them, the vacuum-electroosmosis combined method has become one of the more effective and promising methods for soft soil foundation treatment. Although the vacuum-electroosmosis combined method has obvious advantages in treating soft soil foundations, it also has problems: 1) The vacuum degree is seriously lost as the depth of the soft soil increases, and the drainage effect on the deep soil is poor; 2) The strength of the soft soil foundation after drainage and consolidation does not meet the requirements of the engineering project for the foundation, and the bearing capacity is weak. Summary of the invention

[0004] In view of the shortcomings of the background technology, the technical problem to be solved by the present invention is to provide a method for treating soft soil foundation by combining flocculation-vacuum-electroosmosis-dynamic compaction. The method combines the flocculation-vacuum-electroosmosis-dynamic compaction procedures to increase the treatment efficiency of soft soil foundation and has a good consolidation effect on the soil.

[0005] The present invention is completed by adopting the following technical scheme: a method for treating soft soil foundation by combining flocculation-vacuum-electroosmosis-strong compaction, comprising the following steps:

[0006] S1. Flocculation treatment: adding PAM flocculant to the mud in the mud pool for mud flocculation treatment;

[0007] S2. Lay a vacuum preloading drainage system, insert a drainage device into the flocculated mud, and connect the drainage device to the vacuum pump through the drainage main pipe;

[0008] S3. Laying an electroosmotic system, inserting an electroosmotic component into the mud, the electroosmotic component is composed of an anode electroosmotic component and a cathode electroosmotic component, the anode electroosmotic component and the cathode electroosmotic component are inserted into the mud pool at intervals, and the anode electroosmotic component and the cathode electroosmotic component are connected to the corresponding external DC power supply through wires;

[0009] S4. Lay geotextile on the upper surface of the mud, turn on the vacuum pump for vacuum preloading and drainage, and turn on the external DC power supply for vacuum-electroosmosis combined drainage in the later stage of vacuum preloading;

[0010] S5. Strong compaction treatment: the compaction machine first uses point compaction and then full compaction to complete the soft soil foundation.

[0011] Furthermore, the drainage device in S2 includes a plurality of drainage boards, and the plurality of drainage boards are uniformly inserted into the mud. The top and bottom of the drainage boards are connected to sealing joints, and the sealing joints are respectively connected to an external vacuum pump through drainage pipes.

[0012] Furthermore, the cathode electroosmosis component is arranged near the drainage device.

[0013] Furthermore, the cathode electroosmosis component is arranged on the outer end surface of the drainage device.

[0014] Furthermore, the electro-osmotic component is a steel bar, the cathode electro-osmotic component is a cathode steel bar, and the anode electro-osmotic component is an anode steel bar.

[0015] Furthermore, in S2, the drainage device is a plurality of permeable piles, which are inserted into the flocculated mud at intervals, and the pile bodies of the permeable piles are evenly provided with a plurality of permeable openings. A drainage pipe system is arranged in the permeable piles, and the top of the drainage pipe system is exposed to the top of the mud, and the top of the drainage pipe system is connected to the main drainage pipe.

[0016] Furthermore, the cathode electroosmosis component includes a plurality of cathode electroosmosis sheets, which are evenly fixed on the surface of the permeable pile and connected to an external DC power supply through a cathode wire. The anode electroosmosis component is a plurality of anode steel bars, which are inserted between adjacent cathode electroosmosis components.

[0017] Furthermore, the drainage pipe system includes a drainage main pipe and a plurality of flexible drainage branch pipes. The top of the drainage main pipe is conductively connected to the drainage main pipe. A plurality of flexible drainage branch pipes are evenly arranged on the drainage main pipe. The flexible drainage branch pipes are conductively connected to the drainage main pipe. A plug ring is provided at the outer end of the flexible drainage branch pipe. The plug ring is sleeved at the water permeable port. The bottom of the drainage main pipe is provided with a bottom pile plug. Before the permeable pile is inserted into the mud, the drainage main pipe is inserted from the middle of the permeable pile until the bottom pile plug is embedded in the lower opening of the permeable pile, and then the outer ports of the flexible drainage branch pipes are plugged into the water permeable port in sequence.

[0018] Furthermore, in S4, the vacuum pump is turned on, and vacuum preloading drainage is performed through the flexible drainage branch pipe, the drainage main pipe and the drainage main pipe. In the later stage of vacuum preloading, the external DC power supply is turned on for vacuum-electroosmosis combined drainage. After the drainage is completed, the drainage main pipe is removed, and the drainage pipe system is removed from the permeable pile. Then, cement mortar is poured into the hollow part of the permeable pile. The cement mortar seeps out from the bottom and side permeable ports of the permeable pile. When the cement mortar forms an expanded and solidified end at the bottom of the permeable pile, cement mud seeps out from the permeable port and solidifies with the mud around the pile.

[0019] Effects of the present invention:

[0020] 1. Through flocculation, vacuum preloading, and electroosmosis combined drainage, the drainage effect is obvious and the drainage efficiency is enhanced. Finally, low-energy strong tamping is performed by a tamping machine to further reinforce the soft soil foundation and increase the reinforcement depth of the soft soil foundation.

[0021] 2. The drainage device uses permeable piles, which can be used as a drainage system during the drainage stage. After the drainage is completed, the permeable piles do not need to be pulled out, which improves the efficiency of the construction. After removing the internal drainage pipe of the permeable pile, cement mortar is poured into the cavity of the permeable pile. The cement mortar forms an expanded and solidified end at the bottom of the permeable pile. At the same time, the cement mud seeps out from the permeable port and solidifies with the mud around the pile, providing bearing capacity for the treated soft soil foundation and improving the stability and firmness of the foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention has the following accompanying drawings:

[0023] Figure 1 It is a structural schematic diagram of the first embodiment of a method for treating soft soil foundation by combining flocculation-vacuum-electroosmosis-strong compaction during construction;

[0024] Figure 2 It is a structural schematic diagram of a second embodiment of a method for treating a soft soil foundation by combining flocculation-vacuum-electroosmosis-strong compaction during construction;

[0025] Figure 3 for Figure 2 A schematic diagram of the structure of the second embodiment after construction;

[0026] Figure 4 for Figure 2 Schematic diagram of the cross-sectional structure inside the medium permeable pile;

[0027] Figure 5 for Figure 4 Schematic diagram of the structure at A in the middle. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Reference Figure 1 As shown, the first embodiment of the present invention provides a method for treating soft soil foundation by combining flocculation-vacuum-electroosmosis-dynamic compaction, comprising the following steps:

[0030] S1. Flocculation treatment: Pour the mud into the mud pool, add PAM flocculant to the mud 1 in the mud pool, and mix the PAM flocculant with the mud.

[0031] S2. Lay a vacuum preloading drainage system. A drainage device is inserted into the flocculated mud, and the top of the drainage device is connected to the vacuum pump 3 through the drainage main pipe 2. Specifically, the drainage device includes a plurality of drainage boards 4, and the plurality of drainage boards 4 are uniformly inserted into the mud 1. The top and bottom of the drainage board are connected to the sealing joint 5, and the sealing joint is respectively connected to the external vacuum pump through the drainage main pipe 2.

[0032] S3. Lay the electroosmosis system, insert the electroosmosis component into the mud, the electroosmosis component is composed of an anode electroosmosis component and a cathode electroosmosis component, the anode electroosmosis component and the cathode electroosmosis component are inserted into the mud pool at intervals, and the anode electroosmosis component and the cathode electroosmosis component are respectively connected to the corresponding external DC power supply through wires. Among them, the cathode electroosmosis component is arranged near the drainage device or the cathode electroosmosis component is arranged on the outer end face of the drainage device. Specifically, the electroosmosis component is a steel bar, the cathode electroosmosis component is a cathode steel bar 6, the anode electroosmosis component is an anode steel bar 7, the cathode steel bar 7 is connected to the cathode terminal, the anode steel bar 6 is connected to the anode terminal through a metal gasket, and the cathode terminal and the anode terminal are respectively connected to two external DC power supplies 9 through wires 8.

[0033] S4. A geotextile 10 is laid on the upper surface of the mud, and the vacuum pump 3 is turned on for vacuum preloading and drainage. In the later stage of vacuum preloading, an external DC power supply 9 is turned on for vacuum-electroosmosis combined drainage.

[0034] S5. After drainage is completed, strong compaction treatment is performed. A small compactor is used for low-energy compaction, and the compactor is preferably 2000 Nm. The compactor first uses point compaction and then full compaction to complete the soft soil foundation.

[0035] The above method for treating soft soil foundation uses flocculation, vacuum preloading, and electroosmosis to combine drainage, which has obvious drainage effect and enhances drainage efficiency. Finally, low-energy strong tamping is performed by a tamping machine, so that the soft soil foundation is further reinforced and the reinforcement depth of the soft soil foundation is increased.

[0036] Reference Figure 2-Figure 5 As shown, the second embodiment of the present invention provides a method for treating soft soil foundation by combining flocculation-vacuum-electroosmosis-dynamic compaction, and the steps are as follows:

[0037] S1. Flocculation treatment. Add PAM flocculant to the mud in the mud pool to perform mud flocculation treatment;

[0038] S2. Lay a vacuum preloading drainage system, insert a drainage device into the flocculated mud, and connect the drainage device to the vacuum pump through the drainage main pipe. The drainage device is a plurality of permeable piles 11, which are inserted into the flocculated mud at intervals, and the pile body of the permeable pile is evenly provided with a plurality of permeable openings 12. The hollow inner cavity of the permeable pile is provided with a drainage pipe system 13, and the top of the drainage pipe system is exposed to the top of the mud, and the top of the drainage pipe system is connected to the drainage main pipe 2.

[0039] S3. Lay the electroosmosis system, insert the electroosmosis components into the mud, the electroosmosis components are composed of an anode electroosmosis component and a cathode electroosmosis component, the anode electroosmosis component and the cathode electroosmosis component are placed in the mud pool in an intersecting manner. The anode electroosmosis component and the cathode electroosmosis component are respectively connected to the corresponding external DC power supply through wires. Specifically, the cathode electroosmosis component includes a plurality of cathode electroosmosis sheets 14, the cathode electroosmosis sheets 14 are evenly fixed on the surface of the permeable pile, the cathode electroosmosis sheets 14 are connected to the cathode terminal through wires, the cathode terminal is connected to the external DC power supply through wires, the anode electroosmosis component is a plurality of anode steel bars 7, the anode steel bars are inserted between adjacent cathode electroosmosis components, the anode steel bars 7 are connected to the anode terminal through metal gaskets, and the anode terminal is connected to the external DC power supply through wires.

[0040] S4. Laying geotextile. Lay geotextile 10 on the upper surface of the mud, turn on the vacuum pump for vacuum preloading and drainage, and turn on the external DC power supply for vacuum-electroosmosis combined drainage in the later stage of vacuum preloading. Specifically, turn on the vacuum pump, and perform vacuum preloading and drainage through the drainage pipe system 13 and the drainage main pipe 2, and turn on the external DC power supply for vacuum-electroosmosis combined drainage in the later stage of vacuum preloading.

[0041] S5. Strong compaction treatment: the compaction machine first uses point compaction and then full compaction to complete the drainage of the soft soil foundation.

[0042] S6. Grouting of permeable piles. After the drainage is completed, remove the main drainage pipe 2, and remove the drainage pipe system 13 from the permeable piles. Then pour cement mortar into the hollow of the permeable pile, fill the hollow of the permeable pile with cement mortar, and seep out from the bottom and side permeable ports of the permeable pile. The seeped cement mortar forms an expanded and solidified end 15 at the bottom of the permeable pile, and at the same time, cement mud seeps out from the permeable port and mixes with the mud around the pile to solidify. The permeable pile does not need to be pulled out of the mud, which improves the efficiency of construction. It is connected to the treated foundation through cement mortar, provides bearing capacity for the treated soft soil foundation, and improves the stability and firmness of the foundation.

[0043] The drainage system 13 of the permeable piles in the above-mentioned method of combined flocculation-vacuum-electroosmosis-strong compaction for treating soft soil foundation is composed of a drainage main pipe 131 and a plurality of flexible drainage branches 132. The drainage system improves the drainage efficiency of the permeable piles. The top of the drainage main pipe 131 is connected to the drainage main pipe 2, and a plurality of flexible drainage branches 132 are evenly arranged on the drainage main pipe 131, and the flexible drainage branches 132 are connected to the drainage main pipe 131. The opening at the outer end of the flexible drainage branch pipe is covered with a filter membrane 137, and a plug ring 133 is provided on the outer periphery of the outer end of the flexible drainage branch pipe. The flexible drainage branch pipe is sleeved at the water permeable port 13 through the plug ring 133, and the plug ring seals the water permeable port and the drainage branch pipe to ensure that the drainage enters the drainage main pipe 131 through the flexible drainage branch pipe 132 and is discharged. The bottom of the drainage main pipe is provided with a bottom pile plug 134, the inner wall of the lower opening of the drainage pile is provided with an annular convex edge 135, and a circle of sealing pad layer 136 is arranged on the inner wall of the permeable pile near the annular convex edge. When the bottom pile plug 134 is inserted into the lower opening of the drainage pile, the bottom of the bottom pile plug abuts against the annular convex edge, and the side wall of the pile plug is tightly connected with the sealing pad layer, so that the bottom pile plug prevents mud from flowing into the permeable pile body from the bottom during drainage.

[0044] Specific work flow: 1) Before the permeable pile is inserted into the mud, the drainage main pipe is inserted from the middle of the permeable pile until the bottom pile plug is embedded in the opening below the permeable pile and abuts against the annular convex edge 135 at the bottom of the permeable pile. Then the outer port of the flexible drainage branch pipe is inserted into the permeable port in sequence. The permeable pile body is fixed with multiple cathode electroosmotic sheets and connected to the cathode terminal through a wire. 2) Multiple permeable piles are inserted into the mud at intervals, and the top of the drainage main pipe is connected to the drainage main pipe 2 through a joint. 3) Anode steel bars are inserted between adjacent permeable piles, and the anode steel bars 7 are connected to the anode terminal through a metal gasket, and the anode terminal is connected to an external DC power supply through a wire. 4) The cathode connecting wire column is connected to an external DC power supply through a wire. 5) According to the above S4, pre-pressure drainage is first performed, and then vacuum-electroosmosis combined drainage is performed. 6) Low-energy tamping is performed. 7) After drainage is completed, the drainage main pipe and the wire are removed, the drainage main pipe is pulled out, and the bottom pile plug and the plug rings on both sides of the drainage main pipe are separated from the inner wall of the permeable pile. 8) Pour concrete slurry or cement mortar into the hollow space of the permeable pile.

[0045] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for treating soft soil foundation by combining flocculation-vacuum-electroosmosis-strong compaction, characterized in that: Includes the following step, S1. Flocculation treatment: adding PAM flocculant to the mud in the mud pool for mud flocculation treatment; S2. Lay a vacuum preloading drainage system, insert a drainage device into the flocculated mud, and connect the drainage device to the vacuum pump through the drainage main pipe; S3. Laying an electroosmotic system, inserting an electroosmotic component into the mud, the electroosmotic component is composed of an anode electroosmotic component and a cathode electroosmotic component, the anode electroosmotic component and the cathode electroosmotic component are inserted into the mud pool at intervals, and the anode electroosmotic component and the cathode electroosmotic component are connected to the corresponding external DC power supply through wires; S4. Lay geotextile on the upper surface of the mud, turn on the vacuum pump for vacuum preloading and drainage, and turn on the external DC power supply for vacuum-electroosmosis combined drainage in the later stage of vacuum preloading; S5. Strong compaction treatment: the compaction machine first uses point compaction and then full compaction to complete the soft soil foundation.

2. The method for treating soft soil foundation by combining flocculation, vacuum, electroosmosis and dynamic compaction according to claim 1, characterized in that: S2 The middle drainage device includes a plurality of drainage boards, which are uniformly inserted into the mud. The top and bottom of the drainage boards are connected with sealing joints, and the sealing joints are respectively connected with an external vacuum pump through drainage pipes.

3. The method for treating soft soil foundation by combining flocculation, vacuum, electroosmosis and dynamic compaction according to claim 2, characterized in that: The cathode electroosmosis component is arranged near the drainage device.

4. The method for treating soft soil foundation by combining flocculation, vacuum, electroosmosis and dynamic compaction according to claim 2, characterized in that: The cathode electroosmosis component is arranged on the outer end surface of the drainage device.

5. A method for treating soft soil foundation by combining flocculation-vacuum-electroosmosis-strong compaction according to claim 1, 2, 3 or 4, characterized in that: The electro-osmotic component is a steel bar, the cathode electro-osmotic component is a cathode steel bar, and the anode electro-osmotic component is an anode steel bar.

6. The method for treating soft soil foundation by combining flocculation-vacuum-electroosmosis-strong compaction according to claim 1 is characterized in that: in S2, the drainage device is a plurality of permeable piles, the plurality of permeable piles are inserted into the flocculated mud at intervals, the pile bodies of the permeable piles are evenly provided with a plurality of permeable openings, a drainage pipe system is arranged in the permeable piles, the top of the drainage pipe system is exposed to the top of the mud, and the top of the drainage pipe system is connected to the main drainage pipe.

7. The method for treating soft soil foundation by combining flocculation-vacuum-electroosmosis-strong compaction according to claim 6, characterized in that: The cathode electroosmosis component includes a plurality of cathode electroosmosis sheets, which are evenly fixed on the surface of the permeable pile and connected to an external DC power supply through a cathode wire. The anode electroosmosis component is a plurality of anode steel bars, which are inserted between adjacent cathode electroosmosis components.

8. The method for treating soft soil foundation by combining flocculation-vacuum-electroosmosis-strong compaction according to claim 6 or 7, characterized in that: The drainage pipe system includes a drainage main pipe and a plurality of flexible drainage branch pipes. The top of the drainage main pipe is conductively connected to the drainage main pipe. A plurality of flexible drainage branch pipes are evenly arranged on the drainage main pipe. The flexible drainage branch pipes are conductively connected to the drainage main pipe. A plug ring is provided at the outer end of the flexible drainage branch pipe. The plug ring is sleeved at the water permeable port. The bottom of the drainage main pipe is provided with a bottom pile plug. Before the permeable pile is inserted into the mud, the drainage main pipe is inserted from the middle of the permeable pile until the bottom pile plug is embedded in the lower opening of the permeable pile, and then the outer ports of the flexible drainage branch pipes are plugged into the water permeable port in sequence.

9. A method for treating soft soil foundation by combining flocculation-vacuum-electroosmosis-strong compaction according to claim 6 or 7, characterized in that: in S4, the vacuum pump is turned on, and vacuum preloading drainage is carried out through the flexible drainage branch pipe, the drainage main pipe and the drainage main pipe. In the later stage of vacuum preloading, the external DC power supply is turned on for vacuum-electroosmosis combined drainage. After the drainage is completed, the drainage main pipe is removed, and the drainage pipe system is removed from the permeable pile, and then cement mortar is poured into the hollow part of the permeable pile. The cement mortar seeps out from the bottom and side permeable ports of the permeable pile, and an expanded and solidified end of the cement mortar is formed at the bottom of the permeable pile. At the same time, cement mud seeps out from the permeable port and solidifies with the mud around the pile.

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