Construction method for vibro-replacement stone column in riprap layer with underlying silt

Abstract

A construction method for a vibro-replacement stone column in a riprap layer with underlying silt. A feeding system of a construction apparatus is composed of a lifting bucket, an aggregate bin, a double-locked pressure chamber, a vibroflotation guide rod and feeding pipe, and a discharge outlet, wherein a weighing device is provided on the lifting bucket to ensure accurate feeding metering; high-pressure water and air pipes and high-pressure water and air nozzles, which are arranged outside the vibroflotation guide rod and feeding pipe, jet high-pressure water and air during unloading so as to form a cavity inside a silt layer or a riprap body, thereby ensuring smooth discharging; in addition, when stone in the riprap body gets stuck in the discharge outlet, the stone is pushed to move with the assistance of high-pressure water and air. A construction apparatus body is composed of the vibroflotation guide rod and feeding pipe, a vibration damper, a high-power vibroflot and bottom-opening water-air nozzles. A hole is drilled vertically, and a retaining wall system is formed; and a vibroflotation apparatus is lifted to a certain height, discharging is then started, the vibroflotation apparatus is lowered after filling, and this process is repeated until a column is formed. No pilot-hole pre-drilling operation is required, the apparatus and personnel investment is reduced, and the engineering construction cost is reduced.

Description

A construction method for silt vibrating crushed stone piles under a riprap layer Technical Field

[0001] The invention relates to the technical field of composite foundation construction, in particular to a construction method of silt vibro-stone piles lying under a riprap layer. Background Art

[0002] Vibro-compacted stone piles are generally suitable for compacting loose sand, silt, plain fill, and mixed fill foundations. However, for composite foundations with thick, dimensional stone overburden placed atop silty soil, conventional bottom-discharge vibro-compacting equipment and sunken-tube vibro-compacting equipment cannot penetrate the upper stone layer and drill holes in the silt layer due to insufficient excitation force. While high-powered vibrators can penetrate the soil and drill holes, the riprap layer collapses as the vibrators ascend, preventing an effective material delivery channel. This typically necessitates the use of rotary drilling or down-the-hole drilling equipment. A drilling system, such as a rotary drilling or down-the-hole drill, is used to initially drill a hole through the riprap layer to the bottom, where a steel casing is then buried. Bottom-discharge vibro-compacting equipment, sunken-tube vibro-compacting equipment, or head-of-hole vibro-compacting equipment continues drilling within the casing to the designed pile bottom. Filling, vibrating, and lifting are performed until the bottom of the steel casing is reached. The steel casing is removed, and filling, vibrating, and lifting continue until the pile top is reached.

[0003] The disadvantages of prior art 1 are:

[0004] (1) There are both drilling equipment and vibratory equipment working in parallel on site, which poses a high safety risk.

[0005] (2) The cost of drilling holes in the riprap layer is high.

[0006] (3) Removal of the casing may cause the rock pile to collapse, resulting in broken piles.

[0007] (4) The outer material pipe of the bottom discharge vibratory equipment is attached to the vibrator, restricting the vibratory force of the vibrator.

[0008] (5) The vibrator of the immersed tube vibratory equipment is set at the top of the equipment, and the exciting force at the bottom of the equipment that is in direct contact with the riprap is relatively small.

[0009] (6) The hole filling vibratory equipment uses excavators, forklifts and other equipment to fill the hole directly, which has poor measurement accuracy and serious waste on site.

[0010] (7) The skill level of workers directly determines the quality of the final product, and the quality fluctuates greatly.

[0011] Summary of the Invention

[0012] The technical problem to be solved by the present invention is to address the deficiencies of the existing technology and propose a construction method for vibrating gravel piles under a riprap layer, which does not require pre-drilling operations, reduces equipment and personnel investment, and lowers engineering construction costs.

[0013] The technical problem to be solved by the present invention is achieved through the following technical solutions: a method for constructing silt vibro-stone piles under a riprap layer, which is characterized by:

[0014] 1) The feeding system of the silt vibro-stone pile construction equipment under the riprap layer consists of a lifting hopper, a collecting hopper, a double-locked pressure chamber, a vibro-floating guide rod that also serves as a feeding pipe and a discharge port. The lifting hopper is equipped with a weighing device to ensure accurate feeding, and the collecting hopper serves as the feeding inlet. The double-locked pressure chamber ensures that the feeding material can be fed not only by free fall according to gravity but also by high-pressure air pressure to promote feeding. The vibro-floating guide rod that also serves as the feeding pipe provides a feeding channel.

[0015] 2) The high-pressure water and air pipes and high-pressure water and air nozzles installed outside the vibratory guide rod and feed pipe spray high-pressure water and air during material discharge, forming a cavity in the silt layer or riprap body to ensure smooth material discharge; at the same time, when stones in the riprap body are stuck in the discharge port, high-pressure water and air are used to assist in pushing;

[0016] 3) The main body of the silt vibro-stone pile construction equipment under the riprap layer consists of a vibro-rock guide rod and feed pipe, a shock absorber, a high-power vibrator, and a bottom water-air nozzle. After the site is cleaned and leveled and the construction site is determined, the vibro-rock pile construction equipment is turned on to vertically drill a hole. The bottom water-air nozzle is simultaneously turned on to assist in drilling the hole. When the upper high-pressure water-air nozzle is sunk above the silt surface, the high-pressure water-air nozzle is turned on to make slurry. It can be observed on site that the slurry passes through the riprap layer and returns to the ground, forming a stable mud-rock structure around the hole in the riprap layer, forming a wall protection system. After the hole is drilled to a pile bottom elevation of less than 0.3m, the hole is cleaned by repeatedly lifting and sinking the vibro-rock pile construction equipment.

[0017] 4) Raise the vibrating equipment to a certain height, start feeding, lower the vibrating equipment after filling, and continue to lower it to a certain depth to insert the filler when the current begins to increase, and carry out vibrating compaction work until the working current exceeds the compaction current. Stop vibrating after 5-30S; continue to raise the vibrating equipment, filler, and vibrating compaction until the top of the pile.

[0018] The technical problem to be solved by the present invention can be further achieved by the following technical solution: in step 4), the height of the upper vibrating impact device is 1 to 1.5 m.

[0019] The technical problem to be solved by the present invention can be further achieved by the following technical solution: the compaction current in step 4) is 100-400A.

[0020] The technical problem to be solved by the present invention can be further achieved by the following technical solution: in step 1), the upper opening of the discharge port is semicircular and the interior of the lower opening is ridge-shaped to ensure smooth discharge.

[0021] The technical problem to be solved by the present invention can be further achieved by the following technical solutions: in step 3), the water pressure of the bottom water-gas nozzle and the upper high-pressure water-gas nozzle is maintained at 0.1-1.0 MPa; the penetration speed of the vibrator should not be greater than 2 m / min.

[0022] Compared with existing technologies, this invention provides a set of equipment and construction methods that can automatically form a hole, place materials, and perform vibro-compaction construction on a composite foundation of composite dump-filled standard stone materials in silty soil. This eliminates the need for pre-drilling operations, reduces equipment and personnel investment, and lowers construction costs.

[0023] Economical: By adopting integrated hole-making and vibro-impact equipment, the investment in rotary drilling, down-the-hole drilling and other equipment is reduced. The precise metering of the feeding system such as the lifting hopper avoids the waste of filler, thus reducing the project cost.

[0024] Quality control: The integrated process of hole making and vibratory impact ensures the integrity of the pile body, avoiding the formation of hole expansion, necking and broken piles; weighing facilities are installed on the lifting hopper to ensure accurate feeding and metering.

[0025] Construction period control: The use of integrated hole-making and vibratory flushing equipment saves 1 / 3 of the construction time compared to drilling the hole first and then vibrating, effectively shortening the construction period.

[0026] Safety management and control: Integrated construction reduces cross-operation on site and greatly reduces safety management risks on site.

[0027] The double-locked pressure bin ensures that the material can be fed not only by free fall according to gravity but also by high-pressure air pressurization, which improves the continuity of material feeding and ensures the quality integrity of the pile body.

[0028] High-pressure water and air pipes installed outside the vibro-impact guide rod create cavities in the silt layer or riprap, ensuring smooth material discharge. High-pressure water and air can also be used to assist in moving the material if stones in the riprap block the discharge port. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a structural diagram of the construction equipment;

[0030] Figure 2 is a structural diagram of the discharge port;

[0031] FIG3 is a side view of FIG2 . DETAILED DESCRIPTION

[0032] The specific technical solutions of the present invention are further described below. To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer and to facilitate further understanding of the present invention by those skilled in the art, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them, and do not constitute a limitation on the rights thereof. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0033] A vibro-compacted stone pile construction system for silt beneath a riprap layer. The feeding system consists of a lifting hopper 1, a collecting hopper 2, a double-locked pressure chamber 3, a vibro-compacted guide rod / feed pipe 4, and a discharge port 7. The lifting hopper is equipped with a weighing device to ensure accurate feeding, and the collecting hopper serves as the feeding inlet. The double-locked pressure chamber ensures that the material can fall freely by gravity, while also utilizing high-pressure air to facilitate discharge. The vibro-compacted guide rod / feed pipe 4 provides a discharge channel. The discharge port 7 has a semicircular upper opening and a ridged or other internal shape at the lower opening to ensure smooth discharge.

[0034] High-pressure water and air pipes 5 and high-pressure water and air nozzles 6, located outside the vibro-flotation guide rod and feed pipe 4, spray high-pressure water and air during material discharge, forming cavities in the silt layer or riprap, ensuring smooth material discharge. High-pressure water and air can also be used to assist in the discharge of rocks stuck in the riprap.

[0035] The main body of the vibro-stone pile construction equipment for silt piles below the riprap layer consists of a vibro-rock guide rod (also serving as a feed pipe) 4, a shock absorber 8, a high-power vibrator 9, and bottom water-air nozzles 10. After the site is cleaned and leveled and the construction site is determined, the vibro-rock pile construction equipment (high-power vibrators with a power of 180 kW or higher and a no-load current of approximately 100 A) is activated to vertically drill a hole. The bottom water-air nozzles can be activated simultaneously to assist in drilling. Once the upper high-pressure water-air nozzles have sunk above the silt surface, the high-pressure water-air nozzles are activated to generate slurry. On-site observation shows that the slurry flows through the riprap layer and returns to the surface, forming a stable mud-rock structure around the hole within the riprap layer, forming a retaining wall system. The water pressure at the bottom water-air nozzles and upper high-pressure water-air nozzles is maintained between 0.1 and 1.0 MPa. The vibrator penetration rate should not exceed 2 m / min. Once the hole is drilled to below 0.3 m above the pile base elevation, the hole is cleaned by repeatedly raising and lowering the vibro-rock pile construction equipment.

[0036] Raise the vibrating device to a certain height, start feeding, and lower the vibrating device after filling. When the current begins to increase (at this time, the vibrator is close to the top of the filler), continue to lower it to a certain depth to insert the filler and perform vibrating compaction until the working current exceeds the compaction current (compaction current 100-400A). Stop vibrating after 5-30 seconds. Raise the vibrating device 1m and continue filling and vibrating compaction until the top of the pile.

Claims

1. A method for constructing silt vibro-stone piles under a riprap layer, characterized in that: 1) The feeding system of the silt vibro-stone pile construction equipment under the riprap layer consists of a lifting hopper, a collecting hopper, a double-locked pressure bin, a vibro-floating guide rod serving as a feeding pipe and a discharge port. The lifting hopper is equipped with a weighing facility to ensure accurate feeding measurement, and the collecting hopper is the feeding entrance; the double-locked pressure bin ensures that the feeding can be pressurized by high-pressure air to promote feeding in addition to free falling according to gravity; the vibro-floating guide rod serving as a feeding pipe provides a feeding channel; 2) The high-pressure water and air pipes and high-pressure water and air nozzles installed outside the vibro-impact guide rod and feed pipe spray high-pressure water and air during material discharge to form cavities in the silt layer or riprap to ensure smooth material discharge; at the same time, when stones in the riprap block the discharge port, high-pressure water and air are used to assist in pushing; 3) The main body of the construction equipment for silt vibrating crushed stone piles under the riprap layer consists of a vibrating guide rod and a feeding pipe, a shock absorber, a high-power vibrator and a bottom water-gas nozzle. After the site is cleaned and leveled and the construction site is determined, the vibrating equipment is turned on to vertically drill holes, and the bottom water-gas nozzle is opened to assist in drilling holes. When the upper high-pressure water-gas nozzle sinks above the silt surface, the high-pressure water-gas nozzle is opened to make slurry. It can be observed on site that the mud passes through the riprap layer and returns to the ground, forming a mud-block stone stable structure around the inner hole of the riprap layer, forming a wall protection system. After the hole is drilled to a pile bottom elevation of less than 0.3m, the hole is cleaned by repeatedly lifting and sinking the vibrating equipment. 4) Raise the vibrating device to a certain height, start feeding, lower the vibrating device after filling, and continue to lower it to a certain depth to insert the filler when the current begins to increase, and perform vibrating compaction work until the working current exceeds the compaction current. Stop vibrating after 5-30S; continue to raise the vibrating device, filler, and vibrating compaction until the top of the pile.

2. The method for constructing silt vibro-stone piles under a riprap layer according to claim 1, characterized in that: In step 4), the height of the upper vibrating and impacting equipment is 1 to 1.5 m.

3. The method for constructing silt vibro-stone piles under a riprap layer according to claim 1, characterized in that: The compaction current in step 4) is 100-400A.

4. The method for constructing silt vibro-stone piles under a riprap layer according to claim 1, characterized in that: The upper opening of the discharge port in step 1) is semicircular, and the lower opening is ridge-shaped to ensure smooth discharge.

5. The method for constructing silt vibro-stone piles under a riprap layer according to claim 1, characterized in that: Step 3) The water pressure of the bottom water-gas nozzle and the upper high-pressure water-gas nozzle is maintained at 0.1-1.0 MPa; the penetration speed of the vibrator should not be greater than 2 m / min.

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