Long pile casing follow-up pile foundation construction method

Abstract

The long pile casing follow-up pile foundation construction method comprises the steps that S1, a temporary steel pile casing is buried, then a first section of permanent steel pile casing is buried, and a rotary drilling rig is in place; s2, the rotary drilling rig presses down the steel casing, and the rotary drilling rig takes soil to the bottom of the steel casing; s3, firmly welding the second section of permanent steel casing and the first section of permanent steel casing after soil sampling; and S4, the steel casing continues to be pressed downwards, soil continues to be taken to the bottom of the steel casing, and after the rock stratum is excavated, the rock stratum drilling machine slowly drills and excavates downwards till the designed elevation is excavated. According to the method, the vibration hammer sinking and pulling steel casing and the rotary drilling rig drilling are combined, the hole forming process for miscellaneous fill, marsh sludge and quicksand stratums is effectively achieved, slurry wall protection is not adopted, pollution is reduced, the environment is protected, the labor intensity of workers is reduced, compared with a conventional drilling process, the construction period is shortened, and the construction cost is reduced. The pile foundation quality is greatly improved, the construction cost is reduced, and the economic benefit is improved.

Description

Technical Field

[0001] The invention relates to the technical field of pile foundation construction, and in particular to a long casing follow-up pile foundation construction method. Background Art

[0002] The pebble formation is a typical geological structure with the following characteristics: loose structure, the pebbles are loosely distributed in the formation, uneven in size, and there are large pores between the particles. Strong permeability, due to the large pores between the pebbles, groundwater can easily flow through them, and the permeability coefficient is high. High compressive strength, the pebbles themselves have high hardness and high compressive strength. No cohesion, the pebble formation is mainly composed of smooth round pebble particles, which have no cohesion themselves and poor stability.

[0003] At present, due to the characteristics of the pebble stratum itself, especially for the loose structure in the miscellaneous fill, silt stratum, and quicksand stratum, the conventional pile foundation construction method is difficult to construct the pile foundation under such geological conditions. The slurry leakage and hole collapse phenomena are serious during the drilling process, resulting in backfilling and secondary drilling. The over-squareness of the hole expansion during the casting process of the bored pile foundation is large, which seriously affects the construction progress and cost control. Summary of the invention

[0004] In order to solve the above problems in the prior art, a long casing following pile foundation construction method is provided.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] The present invention proposes a long casing follow-up pile foundation construction method, comprising the following steps:

[0007] S1: Bury temporary steel casing, then bury the first section of permanent steel casing, and put the rotary drilling rig in place;

[0008] S2: The rotary drilling rig presses down the steel casing, and the rotary drilling rig extracts soil to the bottom of the steel casing;

[0009] S3: After soil excavation, the second section of permanent steel casing is firmly welded to the first section of permanent steel casing;

[0010] S4: Continue to press down the steel casing, continue to take soil to the bottom of the steel casing, and after digging to the rock layer, the rock drilling rig slowly drills down until it reaches the designed elevation.

[0011] Preferably, the foundation is treated and the foundation is tested before the pile foundation machinery enters the site. When the actual bearing capacity is lower than the construction requirement, foundation treatment measures are taken to make the foundation meet the requirements for placing the drilling rig machinery;

[0012] Measure and lay out the lines, set up double cross guard piles at the measured and laid out pile positions, and control the pile axis and verticality;

[0013] The drilling rig is in place. Before the drilling rig is in place, stones and hard objects below the pile position are cleared so that the vibrating hammer can clamp the steel casing through the sand layer smoothly, and a steel plate is placed on the foundation where the drilling rig is placed.

[0014] Preferably, a vibrating hammer is used to clamp the steel casing, and the verticality and pile position of the steel casing are checked. The steel casing is driven through the sand layer, and the top surface of the steel casing is higher than the original ground. At the end of the construction, a steel mesh is added to the hole for fixed protection.

[0015] Preferably, when drilling into a hole and about to drill into the bottom of the steel casing, check the geological conditions to ensure that the steel casing seals the sand layer, and adjust the length of the steel casing according to the sealing condition of the sand layer;

[0016] After the steel casing is driven into the soil, the soil inside the steel casing is squeezed and compacted. After the drill bit of the drilling rig drills through the steel casing, the steel casing is flushed with water while drilling to fill the hole with water. The drill bit is rotated back and forth in the steel casing and lifted up and down to clean the steel casing. When the drilling rig drills into the final hole, a reservation is made, and the soil and rock debris on the edge of the steel casing are cleaned before the final hole is drilled.

[0017] Preferably, the steel cage is lowered after being hoisted vertically. The pile position control reinforcement is welded at the top of the steel cage. The steel cage is clamped into the designed pile position through the steel casing. The acoustic detection pipe joints are tightened and tied to make the spacing between the acoustic detection pipes equal and the exposed length greater than the pile top elevation. Pour in clean water and cover.

[0018] Preferably, the conduit is lowered, and each set of conduits is tested for water tightness before use. The conduit is lowered and centered, and the installation length is 30cm-50cm from the bottom of the hole. When the large hopper is filled with concrete, the buried depth of the conduit for the first concrete pouring is more than 1m. After that, the hole is cleaned, and the sediment at the bottom of the hole is cleaned by high-pressure air delivered by an air compressor. When cleaning the hole, the conduit is shaken back and forth to clean the hole, and at the same time it is lifted up and down to clean the hole.

[0019] Preferably, the concrete is poured, and the first pouring of concrete ensures that the buried pipe depth is not less than 1 meter. A cone plug is placed in the funnel. When the funnel is filled with concrete, the plug is immediately pulled out, and concrete is continuously added to the funnel to allow the concrete to be poured continuously. After the first pouring is completed, the concrete is poured continuously from the side of the funnel mouth into the conduit;

[0020] After the first batch of concrete is poured, continue pouring, measure the concrete surface height frequently and pull out the pipe repeatedly. When pulling out the pipe, accurately measure the concrete pouring depth and calculate the buried depth of the conduit, then pull out the pipe. If there is difficulty in lifting the concrete, reduce the buried depth of the conduit. When pulling out the last section of the long conduit, slow down the pulling speed.

[0021] Preferably, the steel casing is removed, and after the concrete is poured, the casing is lifted, and the casing is filled with concrete to discharge the mud and sediment, and the guide tube is not removed, and the steel casing is lifted with a vibrating hammer and then poured with concrete;

[0022] The steel casing is lifted vertically at a uniform speed to allow the concrete in the casing to spread evenly outside the hole. The lifting is completed within the initial setting time of the concrete. After the steel casing is lifted, the steel casing at the adjacent pile position cannot be driven. The steel casing at the pile position is driven in a skipping manner.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention adopts a method of combining the vibratory hammer sinking and drawing steel casing with the rotary drilling rig drilling, which effectively solves the hole-forming process for miscellaneous fill, swamp silt, and quicksand strata. The cooperation of the vibratory hammer and the rotary drilling rig does not use mud wall protection, thereby reducing pollution, cleaning the site, protecting the environment, and reducing the labor intensity of workers. Compared with the conventional drilling process, the construction period is saved, the quality of the pile foundation is greatly improved, the construction cost is reduced, and the economic benefit is improved. At the same time, the field of rotary drilling rig construction of special strata is broadened, and the advantage of the fast construction speed of the vibratory hammer vibration pile sinking is fully utilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0026] Figure 1 It is the overall flow chart of the present invention;

[0027] Figure 2 The construction process of the present invention Figure 1 ;

[0028] Figure 3 The construction process of the present invention Figure 2 ;

[0029] Figure 4 The construction process of the present invention Figure 3 ;

[0030] Figure 5 The construction process of the present invention Figure 4 ;

[0031] Figure 6 The construction process of the present invention Figure 5 ;

[0032] Figure 7 The construction process of the present invention Figure 6 ;

[0033] Figure 8 The construction process of the present invention Figure 7 ;

[0034] Fig. 9 The construction process of the present invention Figure 8 . DETAILED DESCRIPTION

[0035] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0036] like Figure 1-Figure 9 As shown, this embodiment proposes a long casing follow-up pile foundation construction method, comprising the following steps:

[0037] S1: Bury temporary steel casing, then bury the first section of permanent steel casing, and put the rotary drilling rig in place;

[0038] S2: The rotary drilling rig presses down the steel casing, and the rotary drilling rig extracts soil to the bottom of the steel casing;

[0039] S3: After soil excavation, the second section of permanent steel casing is firmly welded to the first section of permanent steel casing;

[0040] S4: Continue to press down the steel casing, continue to take soil to the bottom of the steel casing, and after digging to the rock layer, the rock drilling rig slowly drills down until it reaches the designed elevation.

[0041] Conduct foundation treatment and test the foundation before the pile foundation machinery enters the site. When the actual bearing capacity is lower than the construction requirements, take foundation treatment measures to make the foundation meet the requirements for placing the drilling rig machinery. Conduct K30 test to verify that the foundation bearing capacity is greater than 120Kpa;

[0042] Measure and lay out the lines. Set up double cross guard piles at the pile positions to control the pile axis and verticality. Guard piles should be monitored by a dedicated person and laid out in a position that does not affect the machinery.

[0043] The drilling rig is in place. Before the drilling rig is in place, stones and hard objects below the pile position are cleared so that the vibratory hammer can clamp the steel casing and pass through the sand layer smoothly. Steel plates are placed on the foundation where the drilling rig is placed to ensure the stability of the drilling rig. Check whether there are any objects around the drilling rig that hinder the construction, remove them in time, plan the construction area, and set up warning lines.

[0044] Use a vibratory hammer to clamp the steel casing, control the clamping speed, check the verticality and pile position of the steel casing at any time, and make timely corrections. The steel wire rope of the vibratory hammer is severely worn, so it should be inspected in every shift and replaced in time if there are any defects.

[0045] Determine the driving length of the steel casing according to the geological conditions of the land survey, ensure that the driving length of the steel casing passes through the sand layer, and the top surface of the steel casing is higher than the original ground. At the end of the construction, add a steel mesh to the hole opening for fixed protection.

[0046] During drilling, check whether the geological conditions meet the design requirements. When drilling to the bottom of the steel casing, check the geological conditions to ensure that the steel casing seals the sand layer. Adjust the length of the steel casing according to the sealing condition of the sand layer to avoid hole collapse and reduce concrete waste.

[0047] After the steel casing is driven into the soil, the soil inside the steel casing is squeezed and compacted. After the drill bit of the drilling rig drills through the steel casing, mud is easily left on the casing wall, resulting in insufficient pile diameter. The steel casing is flushed with water while drilling, the hole is filled with water, the drill bit is rotated back and forth in the steel casing, and the drill bit is lifted up and down to clean the steel casing and ensure the pile diameter of the pile foundation.

[0048] When the drilling rig drills into the final hole, reserve the last bucket of footage to reach the designed hole depth in one bucket, try to avoid the accumulation of broken rocks at the bottom of the hole that are difficult to fish out, and clean the soil and rock debris on the edge of the steel casing before drilling the final hole to ensure that the edge of the hole is clean and avoid debris falling into the hole.

[0049] Lower the steel cage after it is lifted vertically. Reduce collision and scraping against the rock wall during the lowering process. Weld the pile position control reinforcement at the top of the steel cage. Put the steel cage into the designed pile position through the steel casing. Tighten the ultrasonic testing pipe joints and tie them up to ensure that the spacing between the ultrasonic testing pipes is equal and smooth. The exposed length is greater than the pile top elevation of 50cm. Pour clean water and cover it. During the production, transportation and installation of the steel cage, measures must be taken to prevent it from deforming and falling into the pile hole. It must be firmly positioned to prevent it from floating up.

[0050] Lower the conduit. Each set of conduits shall be tested for water tightness before use. It can be used only after confirmation of qualification. After a certain number of uses, the conduit needs to be tested for water tightness again. During the test, the pressure shall be no less than 1MPa, and the pressure shall be stable for no less than 10 minutes. Fill the conduit with 70% water and roll it on the ground. There shall be no leakage along the entire length of the conduit.

[0051] The rubber pad of the conduit joint is intact, the joint is tightened, the conduit is placed in the middle, and the installation length is 30cm-50cm from the bottom of the hole. When the large hopper is filled with concrete, the buried depth of the conduit for the first concrete pouring is more than 1m. After that, the hole is cleaned. The sediment at the bottom of the hole is cleaned by high-pressure air from an air compressor. When cleaning the hole, shake the conduit back and forth to clean the hole, and lift it up and down to clean the hole at the same time.

[0052] When pouring concrete, ensure that the buried depth of the pipe is not less than 1 meter for the first pour of concrete. Put a cone plug in the funnel. When the funnel is filled with concrete, pull out the plug immediately and continue to add concrete to the funnel to make the concrete pour continuously. After the first pouring, pour the concrete continuously from the side of the funnel mouth into the conduit. Do not fill it up at once to avoid the formation of air pockets.

[0053] After the first batch of concrete is poured, continue pouring, measure the concrete surface height frequently and pull out the pipe repeatedly. When pulling out the pipe, accurately measure the concrete pouring depth and calculate the buried depth of the conduit before pulling out the pipe. The buried depth of the conduit shall not be greater than 6m and not less than 2m.

[0054] When the pouring is almost finished, the height of the concrete column in the conduit decreases and the overpressure is reduced. If there is difficulty in jacking up the concrete, the buried depth of the conduit can be appropriately reduced to ensure smooth pouring. When pulling out the last section of the long conduit, the pulling speed should be slow to avoid the upper mud in the hole being pressed into the pile.

[0055] After removing the steel casing and pouring concrete, lift the casing immediately and determine the measures for lifting the steel casing. If there are deviations in the geological conditions and loss of sand layer outside the hole, fill the casing with concrete to discharge the mud and sediment. Do not remove the guide tube and use a vibrating hammer to lift the steel casing for 1 meter before pouring concrete to ensure that the concrete can fill the void outside the hole and that the pile head elevation meets the design requirements and the quality of the pile body.

[0056] The steel casing should be lifted vertically at a uniform speed, not too fast, so that the concrete in the casing can be evenly diffused outside the hole. The lifting should be completed within the initial setting time of the concrete to ensure the quality of the pile concrete. After the steel casing is lifted, the steel casings at adjacent piles cannot be driven to avoid the vibration caused by the vibrating hammer clamping the steel casing affecting the quality of the newly poured pile body. The steel casings at piles 10 meters away should be driven by the skipping method.

[0057] By combining the method of vibratory hammer sinking and pulling steel casing with rotary drilling rig drilling, the hole-forming process for miscellaneous fill, swamp silt, and quicksand formations is effectively solved. The coordination of vibratory hammer and rotary drilling rig reduces pollution, cleans the site, protects the environment, and reduces the labor intensity of workers because mud wall protection is not used. Compared with conventional drilling technology, it saves construction time, greatly improves the quality of pile foundation, reduces construction costs, and improves economic benefits. At the same time, it broadens the scope of rotary drilling rig construction of special formations and gives full play to the advantages of vibratory hammer vibration pile sinking construction speed

[0058] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A long casing follow-up pile foundation construction method, characterized in that: The following steps are involved: S1: Bury temporary steel casing, then bury the first section of permanent steel casing, and put the rotary drilling rig in place; S2: The rotary drilling rig presses down the steel casing, and the rotary drilling rig extracts soil to the bottom of the steel casing; S3: After soil excavation, the second section of permanent steel casing is firmly welded to the first section of permanent steel casing; S4: Continue to press down the steel casing, continue to take soil to the bottom of the steel casing, and after digging to the rock layer, the rock drilling rig slowly drills down until it reaches the designed elevation.

2. A long casing follow-up pile foundation construction method according to claim 1, characterized in that: Conduct foundation treatment and inspect the foundation before the pile foundation machinery enters the site. When the actual bearing capacity is lower than the construction requirements, take foundation treatment measures to make the foundation meet the requirements for placing the drilling rig machinery; Measure and lay out the lines, set up double cross guard piles at the measured and laid out pile positions, and control the pile axis and verticality; The drilling rig is in place. Before the drilling rig is in place, stones and hard objects below the pile position are cleared so that the vibrating hammer can clamp the steel casing through the sand layer smoothly, and a steel plate is placed on the foundation where the drilling rig is placed.

3. A long casing follow-up pile foundation construction method according to claim 1, characterized in that: The steel casing is clamped and driven by a vibrating hammer to check its verticality and pile position. The steel casing is driven long enough to pass through the sand layer and its top surface is higher than the original ground. At the end of the construction, a steel mesh is added to the hole opening for protection.

4. A long casing follow-up pile foundation construction method according to claim 1, characterized in that: When drilling into a hole and about to reach the bottom of the steel casing, check the geological conditions to ensure that the steel casing seals the sand layer, and adjust the length of the steel casing according to the sealing condition of the sand layer; After the steel casing is driven into the soil, the soil inside the steel casing is squeezed and compacted. After the drill bit of the drilling rig drills through the steel casing, the steel casing is flushed with water while drilling to fill the hole with water. The drill bit is rotated back and forth in the steel casing and lifted up and down to clean the steel casing. When the drilling rig drills into the final hole, a reservation is made, and the soil and rock debris on the edge of the steel casing are cleaned before the final hole is drilled.

5. A long casing follow-up pile foundation construction method according to claim 1, characterized in that: Lower the steel cage, and then lower it after it is lifted vertically. Weld the pile position control reinforcement at the top of the steel cage, and put the steel cage into the designed pile position through the steel casing. Tighten the ultrasonic detection pipe joints, tie and fix them, so that the spacing between the ultrasonic detection pipes is equal and the exposed length is greater than the pile top elevation. Pour in clean water and cover it.

6. A long casing follow-up pile foundation construction method according to claim 1, characterized in that: The conduit is lowered and a water tightness test is carried out on each set of conduits before use. The conduit is lowered and centered, and the installation length is 30cm-50cm from the bottom of the hole. When the large hopper is filled with concrete, the buried depth of the conduit for the first concrete pouring must be more than 1m. After that, the hole is cleaned, and the sediment at the bottom of the hole is cleaned by high-pressure air delivered by an air compressor. When cleaning the hole, the conduit is shaken back and forth and at the same time lifted up and down to clean the hole.

7. A long casing follow-up pile foundation construction method according to claim 1, characterized in that: Pour concrete. The first pour of concrete should ensure that the buried pipe depth is not less than 1 meter. Put a cone plug in the funnel. When the funnel is filled with concrete, pull out the plug immediately and continue to add concrete to the funnel to ensure continuous pouring of concrete. After the first pouring is completed, pouring continues to slide from the side of the funnel mouth into the conduit; After the first batch of concrete is poured, continue pouring, measure the concrete surface height frequently and pull out the pipe repeatedly. When pulling out the pipe, accurately measure the concrete pouring depth and calculate the buried depth of the conduit, then pull out the pipe. If there is difficulty in lifting the concrete, reduce the buried depth of the conduit. When pulling out the last section of the long conduit, slow down the pulling speed.

8. A long casing follow-up pile foundation construction method according to claim 1, characterized in that: Remove the steel casing, pour concrete, lift the casing, fill the casing with concrete to drain the mud and sediment, do not remove the guide tube, lift the steel casing with a vibrating hammer and then pour concrete; The steel casing is lifted vertically at a uniform speed to allow the concrete in the casing to spread evenly outside the hole. The lifting is completed within the initial setting time of the concrete. After the steel casing is lifted, the steel casing at the adjacent pile position cannot be driven. The steel casing at the pile position is driven in a skipping manner.

Images