Construction method of lime-soil compaction pile under complex foundation condition

Abstract

The invention discloses a construction method of a lime-soil compaction pile under complex foundation conditions, which relates to the technical field of engineering construction and comprises the following steps of: carrying out geological exploration on a construction area, and determining a soil layer structure, a soil layer thickness, a soil property and an underground water level; drilling is conducted in a jumping mode, jumping drilling is conducted from the center to the two sides at intervals, and during single-row drilling, jumping drilling is conducted every two holes; selecting a drilling method according to the exploration result; a depth sensor is installed to be matched with a control system to monitor the hole depth and the drilling footage depth of a drilling tool in real time; covering the formed hole with a cover plate; and after drilling is completed, the pile body is detected through sound wave testing and drilling quality detection.

Description

Technical Field

[0001] The invention relates to the technical field of engineering construction, in particular to the field of underground pipeline construction, and specifically to a construction method of lime-soil compaction piles under complex foundation conditions. Background Art

[0002] At present, lime soil compaction piles are a common solution for foundation treatment. They are suitable for treating collapsible loess, plain fill, and miscellaneous fill above the groundwater level. The depth of the treated foundation is 5 to 15 meters. In traditional hole-making methods, impact drills and rotary drills are each suitable for different types of soil layers. However, in complex geological conditions, soil layers may appear alternately, or the soil layers have great hardness differences, or the water content of the foundation soil is between 20% and 24%, and the saturation is between 50% and 65%. Figure 3 As shown, necking will occur during the drilling process, and a single drilling method often cannot meet construction requirements, resulting in low construction efficiency, unstable hole wall and even equipment drill jamming and other problems. Summary of the invention

[0003] In order to solve a series of problems in the existing drilling technology of lime-soil compaction piles under complex foundation conditions, such as difficulty in drilling, low efficiency, unstable hole wall, etc., pile foundation construction is very likely to encounter such problems under complex geological conditions. The present invention provides a construction method of lime-soil compaction piles under complex foundation conditions.

[0004] The present invention is implemented by the following technologies: The present invention provides a construction method of lime-soil compaction piles under complex foundation conditions, which specifically comprises the following steps: a. Geological survey Conduct geological surveys in the construction area to determine the soil structure, soil thickness, soil properties, and groundwater level. The survey results provide a basis for the formulation of subsequent construction plans and the selection of drilling tools during the construction process.

[0005] b, continuous hole control The drilling is carried out in a skipping manner, from the center to both sides. When drilling in a single row, skip one hole every two holes to relieve the lateral pressure of the soil layer.

[0006] The single-row punching method specifically includes the following steps: Select a row in the area to be punched as the row to be punched, determine the punching positions and number them in sequence as the first hole, the second hole, ..., the nth hole, and divide the punching positions into three groups; The first hole is punched using the method of steps c and d. After the punching is completed, the second and third holes are skipped and the fourth hole is punched; the fifth and sixth holes are skipped and the seventh hole is punched; and so on, the first group of holes is completed; Return to the second hole position to punch holes; after the punching is completed, skip the third hole position, punch holes at the fifth hole position, skip the sixth hole position, punch holes at the eighth hole position, and so on, to complete the second group of holes; Return to the third hole position to punch holes; after the punching is completed, punch holes at the sixth hole position, and punch holes at the ninth hole position, and so on, to complete the third group of holes.

[0007] c, single hole control Select drilling method based on survey results; Among them, an impact drill is used to break and crush the hard soil layer; the hard soil layer includes hard clay and gravel layers, and the impact drill is used to break the hole wall. The impact drill destroys the hard structure of the soil layer through repeated impact, reduces the cutting resistance of the rotary drill, fully exposes the loose soil layer below, and improves the cutting efficiency of the subsequent rotary drill.

[0008] A rotary drill is used to cut loose soil layers; the loose soil layers include soft soil layers and silt layers. The rotary drill is used to drill holes, making full use of the high cutting efficiency of the rotary drill, so that the loose soil layers can be smoothly passed without getting stuck.

[0009] Use rotary drills and impact drills alternately to drill holes in soil layers prone to neck shrinkage; first use a rotary drill to drill holes in soil layers prone to neck shrinkage, and then continue to use an impact drill to tamp and expand the hole, effectively solving the neck shrinkage problem.

[0010] By installing depth sensors and cooperating with the control system, the hole depth and drilling depth of the drilling tool can be monitored in real time to ensure that the hole depth meets the design requirements.

[0011] d, cover hole After drilling is completed, cover the hole with a cover plate.

[0012] e. Inspection After the drilling is completed, the pile body is tested by ultrasonic testing and drilling quality inspection to ensure that the hole wall quality meets the requirements. Especially in the composite drilling method, it is particularly important to test the overall stability and bearing capacity of the pile body.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The invention designs a construction method of lime-soil compaction piles under complex foundation conditions. By combining the advantages of impact drilling and rotary drilling, and the advantages of two hole-making technologies, the invention is suitable for geological environments where hard soil layers and soft soil layers alternate, change, and shrink. The method can achieve efficient, accurate, and safe drilling under different soil conditions, thereby ensuring the quality of pile foundation construction.

[0014] The main advantages include: 1. Improve hole-forming efficiency The rotary drill has fast cutting ability and a high cutting speed in soft soil and loose soil layers, and can quickly break through relatively soft soil layers. When encountering harder soil layers, make full use of the crushing effect of the impact drill to break the harder soil layers through impact and vibration, especially in hard soil layers such as hard clay and gravel layers. The impact drill can more easily break the soil and provide a smoother channel for the rotary drill to cut. When the two are used in combination, the impact drill can break through the resistance of the hard soil layer, and the rotary drill can improve the hole-forming efficiency of the soft soil layer. The composite method can give full play to the different characteristics of the rotary drill and the impact drill, and use them alternately in different soil layers, significantly improve the hole-forming efficiency, and reduce construction delays caused by differences in soil hardness.

[0015] 2. Better adaptability to complex geological conditions The rotary drill performs well in soft soil and silt, while the impact drill has more advantages in hard soil (such as hard clay, gravel, and rock). The composite method can flexibly adjust the construction process according to the changes in the soil layer to ensure that it can pass through various geological conditions smoothly. Especially when encountering uneven geological conditions, the rotary drill may encounter greater soil resistance, while the impact drill can effectively break through the hard soil layer and provide support for the continued work of the rotary drill. Through the combination of the rotary drill and the impact drill, the smooth progress of the construction can be ensured under complex geological conditions (such as uneven soil distribution, alternating rock and soil layers, etc.), reducing technical difficulties and progress delays in construction.

[0016] 3. Improve the aperture quality and hole wall stability The rotary drill can control the hole diameter more accurately and is suitable for projects that require a finer hole diameter, especially in the construction of large-diameter holes, where the rotary drill can better maintain the stability of the hole wall; the vibration effect of the impact drill can enhance the stability of the hole wall when encountering loose soil layers or soft foundations, preventing the hole wall from collapsing or soil loss; the composite method can flexibly utilize the advantages of the impact drill and the rotary drill at different stages of hole formation to ensure the stability and quality of the hole diameter, while reducing the risk of hole wall collapse in soft or loose soil layers.

[0017] 4. Reduce clogging and sticking problems The impact drill has a crushing effect in hard soil layers, which can effectively avoid drill sticking or blockage problems when dealing with hard soil layers. Through the impact effect, the soil is broken into smaller particles, reducing the resistance of the rotary drill bit; the rotary drill can cut efficiently in loose or soft soil layers and is not prone to drill sticking; the composite method can ensure that the hole-making process is smoother and more stable.

[0018] 5. Save construction time and cost Composite construction reduces the subsequent reinforcement work. Since the impact drill helps the rotary drill to quickly pass through the hard soil layer, it avoids downtime and equipment adjustment time caused by changes in soil hardness, and the entire hole-making process is more efficient. It can improve construction efficiency and save time, while reducing the frequency of equipment replacement and operator coordination time, reducing overall construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the single-row punching sequence in the present invention.

[0020] Figure 2 This is a schematic diagram of the drilling process for the easily shrinkable soil layer in step c of the present invention.

[0021] Figure 3 It is a structural schematic diagram of the necking phenomenon that occurs when a hole is expanded by impact drilling in the prior art.

[0022] In the figure: 1 - general soil layer, 2 - soil layer prone to necking, 3 - necking, 4 - impact drill, 5 - rotary drill. DETAILED DESCRIPTION

[0023] The specific embodiments of the present invention are described in detail below.

[0024] A construction method for lime-soil compaction piles under complex foundation conditions, specifically comprising the following steps: a. Geological survey Conduct geological surveys in the construction area to determine the soil structure, soil thickness, soil properties, and groundwater level. The survey results provide a basis for the formulation of subsequent construction plans and the selection of drilling tools during the construction process.

[0025] b, continuous hole control The drilling is carried out in a skipping manner, from the center to both sides. When drilling in a single row, skip one hole every two holes to relieve the lateral pressure of the soil layer.

[0026] The single-row punching method specifically includes the following steps: like Figure 1 As shown, a row is selected in the area to be punched as the row to be punched, the punching positions are determined and numbered in sequence as the first hole, the second hole, ..., the nth hole, and the punching positions are divided into three groups; The first hole is punched using the method of steps c and d. After the punching is completed, the second and third holes are skipped and the fourth hole is punched; the fifth and sixth holes are skipped and the seventh hole is punched; and so on, the first group of holes is completed; Return to the second hole position to punch holes; after the punching is completed, skip the third hole position, punch holes at the fifth hole position, skip the sixth hole position, punch holes at the eighth hole position, and so on, to complete the second group of holes; Return to the third hole position to punch holes; after the punching is completed, punch holes at the sixth hole position, and punch holes at the ninth hole position, and so on, to complete the third group of holes.

[0027] c, single hole control Select drilling method based on survey results; Among them, an impact drill is used to break and crush the hard soil layer; the hard soil layer includes hard clay and gravel layers, and the impact drill is used to break the hole wall. The impact drill destroys the hard structure of the soil layer through repeated impact, reduces the cutting resistance of the rotary drill, fully exposes the loose soil layer below, and improves the cutting efficiency of the subsequent rotary drill.

[0028] A rotary drill is used to cut loose soil layers; the loose soil layers include soft soil layers and silt layers. The rotary drill is used to drill holes, making full use of the high cutting efficiency of the rotary drill, so that the loose soil layers can be smoothly passed without getting stuck.

[0029] like Figure 2 As shown: a rotary drill and an impact drill are used alternately to drill holes in the soil layer 2 that is prone to necking; a rotary drill 5 is first used to guide the hole in the soil layer that is prone to necking, and then an impact drill 4 is used to tamp and expand the hole, effectively solving the necking problem.

[0030] By installing depth sensors and cooperating with the control system, the hole depth and drilling depth of the drilling tool can be monitored in real time to ensure that the hole depth meets the design requirements.

[0031] d, cover hole After drilling is completed, cover the hole with a cover plate.

[0032] e. Inspection After the drilling is completed, the pile body is tested by ultrasonic testing and drilling quality inspection to ensure that the hole wall quality meets the requirements. Especially in the composite drilling method, it is particularly important to test the overall stability and bearing capacity of the pile body.

[0033] The scope of protection claimed by the present invention is not limited to the above specific embodiments. For those skilled in the art, the present invention may have various deformations and changes. Any modifications, improvements and equivalent substitutions made within the concept and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A construction method for lime-soil compaction piles under complex foundation conditions, characterized by: The following steps are involved: a. Geological survey Conduct geological surveys in the construction area to determine soil structure, soil thickness, soil properties, and groundwater level; b, continuous hole control Drill holes in a skipping manner, from the center to both sides at intervals. When drilling in a single row, skip one hole every two holes. c, single hole control The drilling method is selected according to the survey results, among which, the impact drill is used to break and crush the hard soil layer; the rotary drill is used to cut the loose soil layer; the rotary drill and the impact drill are used alternately to drill the easily necked soil layer; By installing depth sensors and cooperating with the control system, the hole depth and drilling depth of the drilling tool can be monitored in real time; d, cover hole After drilling is completed, cover the hole with a cover plate; e. Inspection After the drilling is completed, the pile body is tested using ultrasonic testing and drilling quality testing to ensure that the hole wall quality meets the requirements.

2. The construction method of lime-soil compaction piles under complex foundation conditions according to claim 1 is characterized by: In step b, the single-row punching specifically includes the following steps: Select a row in the area to be punched as the row to be punched, determine the punching positions and number them in sequence as the first hole, the second hole, ..., the nth hole, and divide the punching positions into three groups; The first hole is punched in the manner of steps c and d. After the punching is completed, the second and third holes are skipped and the fourth hole is punched; the fifth and sixth holes are skipped and the seventh hole is punched; and so on, the first group of holes is completed; Return to the second hole position to punch holes; after the punching is completed, skip the third hole position, punch holes at the fifth hole position, skip the sixth hole position, punch holes at the eighth hole position, and so on, to complete the second group of holes; Return to the third hole position to punch holes; after the punching is completed, punch holes at the sixth hole position, and punch holes at the ninth hole position, and so on, to complete the third group of holes.

3. The construction method of lime-soil compaction piles under complex foundation conditions according to claim 1, characterized in that: In step c, the hard soil layer includes hard clay and gravel layer, and the hole wall is broken using an impact drill.

4. The construction method of lime-soil compaction piles under complex foundation conditions according to claim 1, characterized in that: In step c, the loose soil layer includes a soft soil layer and a silt layer, and a rotary drill is used to drill holes.

5. The construction method of lime-soil compaction piles under complex foundation conditions according to claim 1, characterized in that: In step c, in the soil layer prone to necking, a rotary drill is first used to drill a hole in the soil layer prone to necking, and then an impact drill is used to tamp and expand the hole.

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