Miniature vibration compaction pile construction technology

Abstract

The invention relates to a micro vibration compaction pile construction technology, and belongs to the field of engineering construction. According to the method, hole forming is conducted through vibration construction, then pile forming is conducted through grouting, vibration impact construction, vibration tube sinking method construction or cross wing resonance method construction can be adopted in the vibration construction, a micro vibration impact device is adopted in the vibration impact construction, a vibration hammer and a pile tube are adopted in the vibration tube sinking method construction, and a vibration hammer and a cross steel plate are adopted in the cross wing resonance method construction. The diameter of the micro vibration compaction pile obtained through construction is smaller than or equal to 300 mm, additional stress caused by construction is small, damage force to the periphery is small, and construction noise is low; the excitation frequency is high, and the force transmission direction and directivity are strong; the pile forming speed is high; the device is high in design flexibility, is suitable for various different soil conditions, and is especially suitable for soft soil areas.

Description

Technical Field

[0001] The invention relates to the technical field of engineering construction, in particular to a micro vibration compaction pile construction process. Background Art

[0002] There are many types of micropiles, each with its own unique construction methods and applicable scenarios. The three most common types are: root piles, precast piles, and grouting steel pipe piles.

[0003] Root pile. A small-diameter bored pile, usually 100 to 300 mm in diameter, is made by cleaning the hole, lowering the steel bar, inserting the grouting pipe, injecting cement slurry under pressure, and vibrating and pulling the pipe to form a pile.

[0004] Its advantages:

[0005] 1) Due to its small diameter, it can be constructed in narrow or restricted spaces, with high construction flexibility;

[0006] 2) The construction efficiency of tree root piles is high, which can shorten the construction period. At the same time, under certain circumstances, its cost is lower than that of traditional pile foundations;

[0007] 3) It is suitable for various soil conditions such as clay, sand, gravel, etc., and the overall bearing capacity of pile groups is relatively high;

[0008] 4) Due to the small pile diameter, the impact on surrounding buildings and environment during construction is relatively small.

[0009] Disadvantages: 1) Due to the small pile diameter, the bearing capacity of a single tree root pile is relatively low;

[0010] 2) The construction process has high requirements for drilling, grouting and other technical techniques to ensure the quality and bearing capacity of the pile body. It is suitable for areas with limited space and weak foundations such as foundation reinforcement and slope stability, or occasions with special requirements for environmental beautification such as bridge foundations and urban building-intensive areas.

[0011] Precast micro piles. A type of micro pile prefabricated in a factory from high-strength concrete or reinforced concrete, with a small diameter, usually with a cross-sectional size of no more than 300 mm.

[0012] Advantages: 1) Prefabricated micropiles are prefabricated in the factory and can be quickly installed on site, which can significantly shorten the construction period;

[0013] 2) Factory production can achieve strict quality control, and the pile quality is stable and reliable;

[0014] 3) During the production and construction of prefabricated piles, wet work on site is reduced, resulting in less environmental impact;

[0015] 4) Piles of different specifications and strengths can be customized according to project requirements to ensure the stability of the pile foundation project.

[0016] insufficient:

[0017] 1) The initial factory production cost of prefabricated piles is high, and they need to be transported to the construction site, which easily leads to high transportation costs;

[0018] 2) The transportation and hoisting of prefabricated piles require a certain amount of space and equipment, and the construction takes up a large space;

[0019] 3) The connection with the surrounding soil or foundation may not be as strong as cast-in-place piles, and the accuracy of the installation equipment and the technical requirements of the operators are high. It is suitable for the rapid reinforcement of foundations such as silt, silty soil, clay, silt, sand and artificial fill with limited space on the construction site, or when the original foundation bearing capacity is insufficient and additional support is required.

[0020] Micro grouting steel pipe piles. They are composed of steel pipes with smaller diameters. The pile body is formed by pressure grouting or filling concrete inside the steel pipes. They combine the strength of steel pipe piles with the foundation reinforcement effect of grouting technology.

[0021] advantage:

[0022] 1) Made of high-strength steel, it is suitable for a variety of soil conditions and has a high bearing capacity;

[0023] 2) Grouting can fill the voids in the surrounding soil and improve the overall bearing capacity and stability of the soil;

[0024] 3) Compared with traditional pile foundations, micro-grouting steel pipe piles have a fast construction speed and can effectively shorten the construction period;

[0025] 4) It can be constructed by various construction methods such as pre-drilling, hammering, static pressure, etc., with good construction flexibility.

[0026] insufficient:

[0027] 1) The cost of a single pile is relatively high, especially in projects that require a large number of pile foundations;

[0028] 2) It has high requirements on grouting materials and construction technology, and requires professional construction teams and equipment.

[0029] Micropiles are suitable for foundation projects that require high bearing capacity and stability, especially in densely built-up urban areas with limited space and sensitive to noise and environmental impacts, or in places with complex geological conditions where different soil types such as soft soil, silt, and rock are intertwined and the self-stability of the soil needs to be enhanced.

[0030] However, existing micro piles are usually not made by vibration construction, especially vibro-impact construction. The drilling is usually done by a drilling machine, which is difficult to construct, mainly because the micro pile has a small hole diameter and is prone to hole collapse. Therefore, for the construction of micro piles, the focus is on preventing the pile hole from collapsing. Generally, the method of burying casing is adopted, which not only increases the construction difficulty, but also has limited effect in preventing hole collapse.

[0031] Based on this, the present invention is proposed. Summary of the invention

[0032] In view of the shortcomings of the prior art, the present invention provides a micro vibration compaction pile construction process, and its technical solution is as follows:

[0033] The micro vibration compaction pile construction process includes the following steps:

[0034] Step 1: Select the stake location and set the ground zero point;

[0035] Step 2: Hole making

[0036] Vibratory impact construction is adopted, which first uses a micro vibrator to make holes, clean the holes, and obtain vibratory impact holes with a diameter of 100-300mm;

[0037] or,

[0038] The vibrating pipe sinking method is used for construction. The construction tools are vibrating hammer and pile pipe. The outer diameter of the pile pipe is 100-300mm.

[0039] or,

[0040] The cross-wing resonance method is used for construction. The construction tools are a vibrating hammer and a cross steel plate. The length of the cross steel plate is 100-300mm, and the width of the cross steel plate is 100-300mm. Holes are made by vibrating hammer and cross steel plate.

[0041] Step 3: Grouting

[0042] When vibratory construction is adopted, the grouting medium at this time is a main material without filler or a main material with filler; a grouting pump is used to deliver the grouting medium into the vibratory hole, the water pump is turned off before grouting, and the micro vibrator is used to vibrate and compact the grouting medium; grouting is carried out in a segmented lifting manner, such as first injecting a certain amount of grouting medium into the vibratory hole, then lifting the micro vibrator, then grouting, then lifting the micro vibrator, and then grouting until the set height is reached;

[0043] When the vibration pipe sinking method is used for construction, the grouting medium is sent into the pile pipe by a grouting pump, and the vibrating hammer applies vibration to the pile pipe to compact the grouting medium; the height of the grouting medium in the pile pipe must reach a certain height before the pipe can be pulled out. Before pulling out the pipe, vibrate for about 1 minute, and then pull out the pipe while vibrating. For every 0.5-1m rise, the pile pipe should be reversed by about 40cm, and vibration should be left for 30-60s. This is repeated until the pile pipe is fully pulled out, and the pulling speed is controlled at 1.2-1.5m / min; repeat the above grouting and pulling steps until the pile pipe is pulled out of the ground;

[0044] When the cross-wing resonance method is used for construction, a grouting pump is used to deliver the grouting medium into the center hole of the cross steel plate, and grouting is performed in a segmented upward manner. For example, a certain amount of grouting medium is first injected, and then the cross steel plate is lifted up a certain distance and then grouting is performed again, and then the cross steel plate is lifted up again and grouting is performed again until the set height is reached.

[0045] As a further solution of the present invention, when vibro-impact construction is adopted, the high-pressure water pump is started first, and when water comes out from the bottom of the grouting pipe on both sides of the micro-vibrator, the micro-vibrator is started to make a hole until the hole is made to 0.3 to 0.5 m below the designed depth, thereby completing the hole making.

[0046] As a further solution of the present invention, when adopting the vibration pipe sinking method for construction, the pile head is first installed at the designed pile position, the pile pipe is placed on the pile head, the vibration hammer is in place, the pile pipe is kept vertically downward, and the hammer weight and the pile pipe's own weight are used to slowly press statically for 1-2m, then the vibration hammer is started to vibrate and sink, until the vibration hammer sinks the pile pipe to the designed depth, and the vibration hammer stops vibrating.

[0047] As a further solution of the present invention, during the hole-making construction process using the cross-wing resonance method, the frequency of the vibrating hammer is adjusted, and the cross steel plate vibrates downward to reach the designed depth and then is lifted while vibrating until it reaches the ground.

[0048] As a further solution of the present invention, after hole making and before grouting, steel bars, anti-pulling soft anchors or anti-pulling hard anchors are installed in the vibrating holes, and grouting is performed after the installation is completed.

[0049] As a further solution of the present invention, if a pull-out soft anchor or a pull-out hard anchor is installed in the vibrating hole, the pile finally formed is a pull-out pile.

[0050] As a further solution of the present invention, the pull-out resistant soft anchor is composed of an inverted cone-shaped anchor shoe and an anchor body, and the anchor body is a steel wire rope or an iron chain;

[0051] The pull-out resistant hard anchor is composed of an inverted cone-shaped anchor shoe and an anchor body. The anchor body is an iron rod, and the iron rod is made by connecting a plurality of standard rods.

[0052] As a further solution of the present invention, when a micro vibrator is used to make holes, a two-by-one hole making method is adopted to make holes.

[0053] As a further solution of the present invention, when a micro vibrator is used for hole making, the water pressure is 10-20MPa, the motor speed is 0-12000r / min, the no-load current is 8-30A, and the current is increased by 5-30A during encryption.

[0054] As a further solution of the present invention, the main material without filler is one or more of original soil, cement, and cement slurry; the main material with filler includes reinforcing material, anti-corrosion and rust inhibitor, coagulant, and cement, the reinforcing material is one or more of aggregate and fiber, and the aggregate includes crushed stone and sand.

[0055] Compared with the prior art, the beneficial effects of the present invention are:

[0056] The micro vibration compaction pile obtained by the construction of the present invention has a diameter less than or equal to 300 mm, small additional stress caused by construction, small destructive force on the surrounding area, and low construction noise; high excitation frequency, strong force transmission direction and directivity; fast pile speed; large design flexibility, suitable for various soil conditions, especially suitable for soft soil areas.

[0057] The construction machines and tools can be: vibrator, vibration hammer (pile pipe, cross steel plate), which have strong versatility.

[0058] The pull-out structure is divided into: pull-out anchor cable and pull-out anchor rod;

[0059] Pile main material: divided into main material without filler and main material with filler to meet various process requirements. DETAILED DESCRIPTION

[0060] The present invention is described in detail below in conjunction with specific embodiments. The embodiments described below are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0061] Example 1

[0062] Step 1: Select the stake location and set the ground zero point;

[0063] Step 2: Make a hole.

[0064] In some embodiments, vibro-impacting construction is used, which first uses a micro vibro-impactor to make a hole. Generally, a high-pressure water pump is started first, and when water comes out from the bottom of the grouting pipe on both sides of the micro vibro-impactor, the micro vibro-impactor is started to make a hole until the hole is 0.3 to 0.5 m below the designed depth, and the hole is completed and cleaned to finally obtain a vibro-impacted hole.

[0065] The diameter of the micro vibrator without the water pipe is 50-160mm, and the diameter of the micro vibrator with the water pipe is 100-240mm. The water pressure during hole making is 10-20MPa, the air compressor pressure is 0.2-1.6MPa (used to supply compressed air to the micro vibrator), the motor speed is 0-12000r / min, the no-load current is 8-30A, and the current is increased by 5-30A during encryption. Dry construction is possible, the motor is equipped with a cooling system, and the pile hole diameter is 100-300mm.

[0066] For the existing vibrator, the theoretical pile diameter is 800-1200mm, the no-load current of the vibrator is 45-120A, the density current is increased by 30-100A (relative to the no-load current), the exciting force is 100KN-500KN, the water pressure during hole making is 0-2MPa, the air compressor pressure is 0.2-1.6MPa, and the motor speed is 0-3000r / min.

[0067] Therefore, compared with the existing vibrators, the motor speed of the micro vibrator is doubled, up to 4 times that of the existing vibrator, and the water pressure when making holes is 10 times that of the existing vibrator. Since the micro vibrator has a higher speed, a higher excitation frequency, and a higher water pressure when making holes, the micro vibrator has a higher hole-making rate.

[0068] In other embodiments, a vibration pipe sinking method is used for construction, and the construction tools are a vibration hammer and a pile pipe, and the outer diameter of the pile pipe is 100-300 mm. The specific steps are as follows:

[0069] First install the pile head at the designed pile position, place the pile pipe on the pile head, put the vibratory hammer in place, keep the pile pipe vertically downward, use the weight of the hammer and the pile pipe to slowly press statically for 1-2m, then start the vibratory hammer to vibrate and sink it until the vibratory hammer sinks the pile pipe to the designed depth and the vibratory hammer stops vibrating.

[0070] In other embodiments, the cross-wing resonance method is used for construction, and the construction tools are a vibrating hammer and a cross steel plate. First, a hole is made by using the vibrating hammer and the cross steel plate. During the hole making process, the frequency of the vibrating hammer is adjusted (consistent with the natural frequency of the reinforced soil layer previously measured), and the cross steel plate vibrates downward to reach the designed depth and then is lifted while vibrating until it reaches the ground.

[0071] Step 3: Grouting

[0072] In some embodiments, vibro-impacting construction is adopted, and the grouting medium at this time is a main material without fillers or a main material with fillers; the main material without fillers is one or more of original soil, cement, and cement slurry; the main material with fillers includes reinforcing materials, anticorrosive and rust-inhibiting agents, coagulants, and cement, and the reinforcing materials are one or more of aggregates and fibers, and the aggregates include crushed stone and sand. A grouting pump is used to deliver the grouting medium into the vibro-impacting hole, and the water pump is turned off before grouting. The micro-vibrator is used to vibrate and compact the grouting medium; grouting is performed in a segmented lifting manner, such as first injecting a certain amount of grouting medium into the vibro-impacting hole, then lifting the micro-vibrator, then grouting, then lifting the micro-vibrator, and then grouting until the set height is reached.

[0073] According to the requirements, the concrete strength of plain concrete structures should not be lower than C15 grade, and the reinforced concrete strength should not be lower than C20 grade.

[0074] Note: C15 concrete mix ratio per cubic meter (kg): 256kg cement, 185kg water, 750kg sand, 1172kg crushed stone. Sand is medium sand with a fineness modulus of 2.3-3.0; the particle size of crushed stone is 5-40mm.

[0075] C20 concrete mix ratio per cubic meter dosage (kg): 335kg cement, 185kg water, 640kg sand, 1245kg crushed stone. Sand is medium sand with a fineness modulus of 2.3-3.0; the particle size of crushed stone is 5-40mm.

[0076] C25 concrete mix ratio per cubic meter (kg): 390kg cement, 185kg water, 566kg sand, 1244kg crushed stone. The sand is medium sand with a fineness modulus of 2.3-3.0; the particle size of the crushed stone is 5-40mm.

[0077] In other embodiments, the vibrating pipe sinking method is used for construction, and the construction tools are a vibrating hammer and a pile pipe. The grouting medium at this time is the same as that in the vibratory construction. A grouting pump is used to send the grouting medium into the pile pipe, and the vibrating hammer applies vibration to the pile pipe to squeeze the grouting medium; the height of the grouting medium in the pile pipe needs to reach a certain height (such as greater than 1 / 3 of the pile pipe length) before the pipe can be pulled out. Before pulling out the pipe, vibrate for about 1 minute, and then pull out the pipe while vibrating. For every 0.5-1m increase, the pile pipe should be reversed by about 40cm, and vibration should be left for 30-60s. This is repeated until the pile pipe is fully pulled out, and the pulling speed is controlled to be 1.2-1.5m / min. Repeat the above grouting and pulling out steps until the pile pipe is pulled out of the ground.

[0078] In other embodiments, the cross-wing resonance method is used for construction, and the construction tools are a vibrating hammer and a cross steel plate. The grouting medium at this time is the same as that in the vibration construction. A grouting pump is used to deliver the grouting medium into the center hole of the cross steel plate (when making the hole, the center hole is closed with a hole plug), and the grouting is performed in a segmented upward manner. For example, a certain amount of grouting medium is first injected, and then the cross steel plate is lifted for a certain distance (such as 0.33m) and then grouting is performed, and then the cross steel plate is lifted and grouting is performed again until the set height is reached.

[0079] Example 2

[0080] In Example 1, after hole making and before grouting, steel bars, pull-out soft anchors or pull-out hard anchors can be installed in the vibrating holes according to construction requirements, and grouting can be performed after installation.

[0081] In some embodiments, if an anti-pullout soft anchor or an anti-pullout hard anchor is installed in the vibrating hole, the final pile is an anti-pullout pile.

[0082] The pull-out anchor is divided into pull-out soft anchor and pull-out hard anchor. The pull-out soft anchor, also known as the pull-out anchor cable, is composed of an inverted cone-shaped anchor shoe and an anchor body, which is a wire rope or iron chain. The pull-out hard anchor, also known as the pull-out anchor rod, is composed of an inverted cone-shaped anchor shoe and an anchor body, which is an iron rod, and the iron rod is made of several standard rods.

[0083] Example 3

[0084] If the existing 30kW vibrator is used, the pile spacing is 1.3 meters. For areas with small loads or sandy foundations, holes can be drilled continuously without skipping holes. For micro vibrators, the excitation frequency is higher, and resonance is more likely to occur during construction, resulting in hole collapse. In contrast, at the same pile spacing, if the two-hole-with-one-hole drilling method is not used during the hole-making process, the probability of hole collapse will increase significantly. The two-hole-with-one-hole drilling method means that for every two holes drilled, the third preset hole-making position is skipped, and holes are drilled at the fourth and fifth preset hole-making positions; then, after the first, second, fourth, and fifth micro vibration compaction piles are formed, return to the third preset hole-making position to drill holes and pile. After a large number of tests and statistics, it was found that compared with continuous hole making, the hole collapse rate of the two-hole-one-hole making method decreased by more than 70%; compared with the one-hole-one-hole making method, the hole collapse rate of the two-hole-one-hole making method decreased by more than 35%; compared with the three-hole-one-hole making method, the hole collapse rate of the two-hole-one-hole making method decreased by more than 30%.

[0085] Example 4

[0086] For micropiles, the vibrator vibrates horizontally and the vibratory hammer vibrates vertically. These two vibration modes have a great influence on the performance of micropiles (especially the bending bearing capacity).

[0087] After a lot of tests and statistics:

[0088] When the cross section of the micropile is the same, the bending bearing capacity of the micropile constructed by the cross-wing resonance method is 143% of that of the micropile constructed by the vibroflotation method, while the bending bearing capacity of the micropile constructed by the vibroflotation method is 107% of that of the micropile constructed by the vibroflotation method. However, the average lateral resistance of the micropile constructed by the cross-wing resonance method is higher, which is 57% higher than that of the vibroflotation method.

[0089] In addition, it should be understood that those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. The micro vibration compaction pile construction process is characterized by: The following steps are involved: Step 1: Select the stake location and set the ground zero point; Step 2: Hole making Vibratory impact construction is adopted, which first uses a micro vibrator to make holes, clean the holes, and obtain vibratory impact holes with a diameter of 100-300mm; or, The vibrating pipe sinking method is used for construction. The construction tools are vibrating hammer and pile pipe. The outer diameter of the pile pipe is 100-300mm. or, The cross-wing resonance method is used for construction. The construction tools are a vibrating hammer and a cross steel plate. The length of the cross steel plate is 100-300mm, and the width of the cross steel plate is 100-300mm. Holes are made by vibrating hammer and cross steel plate. Step 3: Grouting When vibratory construction is adopted, the grouting medium at this time is a main material without filler or a main material with filler; a grouting pump is used to deliver the grouting medium into the vibratory hole, the water pump is turned off before grouting, and the micro vibrator is used to vibrate and compact the grouting medium; grouting is carried out in a segmented lifting manner, such as first injecting a certain amount of grouting medium into the vibratory hole, then lifting the micro vibrator, then grouting, then lifting the micro vibrator, and then grouting until the set height is reached; or, When the vibration pipe sinking method is used for construction, the grouting medium is sent into the pile pipe by a grouting pump, and the vibrating hammer applies vibration to the pile pipe to compact the grouting medium; the height of the grouting medium in the pile pipe must reach a certain height before the pipe can be pulled out. Before pulling out the pipe, vibrate for about 1 minute, and then pull out the pipe while vibrating. For every 0.5-1m rise, the pile pipe should be reversed by about 40cm, and vibration should be left for 30-60s. This is repeated until the pile pipe is fully pulled out, and the pulling speed is controlled at 1.2-1.5m / min; repeat the above grouting and pulling steps until the pile pipe is pulled out of the ground; or, When the cross-wing resonance method is used for construction, a grouting pump is used to deliver the grouting medium into the center hole of the cross steel plate, and grouting is performed in a segmented upward manner. For example, a certain amount of grouting medium is first injected, and then the cross steel plate is lifted up a certain distance and then grouting is performed again, and then the cross steel plate is lifted up again and grouting is performed again until the set height is reached.

2. The micro vibration compaction pile construction process according to claim 1 is characterized in that: When vibro-impacting construction is adopted, the high-pressure water pump is started first. When water comes out from the bottom of the grouting pipe on both sides of the micro-vibrator, the micro-vibrator is started to make holes until the hole is made to 0.3 to 0.5 m below the designed depth.

3. The micro vibration compaction pile construction process according to claim 1 is characterized by: When using the vibration pipe sinking method for construction, first install the pile head at the designed pile position, place the pile pipe on the pile head, put the vibrating hammer in place, keep the pile pipe downward vertically, use the weight of the hammer and the pile pipe's own weight to slowly press statically for 1-2m, then start the vibrating hammer to vibrate and sink the pile pipe until the vibrating hammer sinks the pile pipe to the designed depth and the vibrating hammer stops vibrating.

4. The micro vibration compaction pile construction process according to claim 1 is characterized in that: In the process of drilling holes using the cross-wing resonance method, the frequency of the vibrating hammer is adjusted, and the cross steel plate vibrates downward to the designed depth and then is lifted while vibrating until it reaches the ground.

5. The micro vibration compaction pile construction process according to claim 1 is characterized by: After drilling the hole and before grouting, install steel bars, anti-pulling soft anchors or anti-pulling hard anchors into the vibrating hole. After installation, grouting is performed.

6. The micro vibration compaction pile construction process according to claim 1 is characterized by: If a pull-out soft anchor or a pull-out hard anchor is installed in the vibrating hole, the final pile will be a pull-out pile.

7. The micro vibration compaction pile construction process according to claim 6 is characterized by: The anti-pullout soft anchor is composed of an inverted cone-shaped anchor shoe and an anchor body, and the anchor body is a steel wire rope or an iron chain; The pull-out resistant hard anchor is composed of an inverted cone-shaped anchor shoe and an anchor body. The anchor body is an iron rod, and the iron rod is made by connecting a plurality of standard rods.

8. The micro vibration compaction pile construction process according to claim 1 is characterized by: When a micro vibrator is used for hole making, a two-hole-alternate-one hole making method is adopted.

9. The micro vibration compaction pile construction process according to claim 1 is characterized by: When using a micro vibrator to make holes, the water pressure is 10-20MPa, the motor speed is 0-12000r / min, the no-load current is 8-30A, and the current is increased by 5-30A during encryption.

10. The micro vibration compaction pile construction process according to claim 1 is characterized by: The main material without filler is one or more of original soil, cement, and cement slurry; the main material with filler includes reinforcing material, anticorrosion and rust inhibitor, coagulant, and cement, the reinforcing material is one or more of aggregate and fiber, and the aggregate includes crushed stone and sand.