Method for constructing high-pressure jet grouting secant pile in special soil body

Abstract

The invention discloses a method for constructing a high-pressure jet grouting secant pile in a special soil body. The method comprises the following steps of rotary digging and hole forming, hole forming inspection, clay selection, clay replacement and hole forming and high-pressure jet grouting. By replacing the soil layer around the pile foundation, the pile hole meeting the design requirement is smoothly drilled in the special soil layer, and preconditions are created for foundation engineering such as follow-up construction. According to the method, complex and changeable geological conditions can be effectively dealt with, it is ensured that the reliable foundation treatment effect can be achieved in various soil layer environments, the adaptability and success rate of engineering construction are improved, and meanwhile facilities such as surrounding existing buildings and underground pipelines are protected against the influence of construction disturbance.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and in particular relates to a construction technology of high-pressure rotary jet grouting piles, and specifically is a method for constructing high-pressure rotary jet grouting interlocking piles in special soil. Background Art

[0002] During the construction process, high-pressure jet grouting piles generally adopt the construction method of direct drilling. When encountering special soil layers such as pebble layers and gravel layers, mechanical drilling such as geological drills or anchor drills is generally used. However, the pebble layer and gravel layer are hard and abrasive. The drill bits, drill rods and other parts of the geological drill and anchor drill will suffer severe wear during the drilling process. Frequent replacement of drill bits and drill rods will not only increase construction costs, but also cause delays in construction. Moreover, the particles in these special soil layers are uneven in size and closely arranged. The torque and power of geological drills and anchor drills are often difficult to effectively break and remove obstacles, and the drill is prone to jamming, which reduces construction efficiency.

[0003] Moreover, due to the complexity of the strata, it is difficult for geological drills and anchor drills to maintain a stable drilling trajectory during drilling, which can easily lead to problems such as hole inclination and irregular hole diameter. The situation is even more serious for the construction of interlocking piles, which can easily lead to problems such as pile body deflection, poor pile quality, and poor water-stopping effect. At the same time, the stability of the hole wall itself in special soil layers is relatively poor, and it lacks the cohesive force of clay soil. During the drilling and drilling process, it is easy to cause the hole wall to collapse due to factors such as mud pressure fluctuations and improper operation, affecting the quality of the hole and causing rework of the project. Summary of the invention

[0004] The purpose of the present invention is to provide a method for constructing high-pressure rotary grouting interlocking piles in special soil bodies, in which the traditional drilling method is used to construct high-pressure rotary grouting interlocking piles in special soil bodies, and the problems such as pile body deviation, poor pile quality, poor water-stopping effect, and even a deadlock in which holes cannot be drilled are often encountered. The method can effectively cope with complex and changeable geological conditions, ensure that reliable foundation treatment effects can be achieved in various soil layer environments, improve the adaptability and success rate of engineering construction, and at the same time protect surrounding existing buildings, underground pipelines and other facilities from construction disturbances.

[0005] A method for constructing high-pressure rotary grouting interlocking piles in special soil, comprising the following steps: Step 1: Rotary drilling: According to the special soil at the construction site and the design layout of the bite pile, select a rotary drilling rig with suitable power and torque to perform rotary drilling. The range of the hole needs to at least cover all the bite parts of the bite pile, and the depth of the hole is the same as the depth of the bite pile; the special soil includes sandy soil layer, pebble layer, gravel layer and sandy soil layer; Step 2: Hole inspection: Check the bottom of the hole dug in step 1 to ensure there is no garbage or debris; Step 3: Choose clay: Choose the appropriate clay according to the on-site construction conditions; the plasticity index of the clay is 15-25, the clay content is 40%-60%, and the water content of the clay is controlled at 20%-30%; Step 4: Clay replacement: Clean the hole and slowly fill the clay into the hole. When it is filled to 1 / 4 of the height, start to extract the mud in the hole. Extract the mud while filling the clay until the hole is completely filled with clay. The process of filling the clay and extracting the mud at the same time is conducive to the clay to better enter the gaps and corners of the hole wall under the action of gravity and mud discharge, making the filling more dense and improving the stability and bearing capacity of the foundation.

[0006] Step 5: High-pressure rotary grouting: Drill holes according to the design plan, insert the grouting pipe to the bottom of the hole, inject grout with high pressure, and lift the pipe after the grouting is completed; after the high-pressure rotary grouting, at least the interlocking parts of each pile are in the area where the clay is replaced.

[0007] In further optimization, the range of holes formed in step one covers all the occlusal piles, and the number of holes formed is one or more.

[0008] Further optimization, in step three, the selection of suitable clay according to the on-site construction conditions includes: selecting the moisture content of the clay and the plasticity of the clay according to the on-site temperature and the degree of drought; the lower the temperature, the lower the moisture content of the clay selected, and the greater the degree of drought, the higher the moisture content and the stronger the plasticity of the clay selected. For example, in cold northern regions, low-moisture clay is selected to reduce the risk of frost heave. In hot and arid regions, high-plasticity clay is selected to resist rapid evaporation of water to a certain extent and reduce the possibility of soil cracking.

[0009] For further optimization, in step 4, a mud pool is set up next to the hole for replacing clay, and the mud extracted from the hole flows into the mud pool.

[0010] In one solution, the pile bodies of the interlocking piles are arranged in rows, and the centers of the equal-height cross-sections of the pile bodies are on a straight line, and multiple holes are drilled, and the area of ​​each hole covers one interlocking portion.

[0011] In one solution, the pile bodies of the interlocking piles interlock with each other, and if the centers of the equal-height cross-sections of the pile bodies are not in a straight line, a hole is drilled and the range of the hole covers all the interlocking piles.

[0012] Beneficial effects of the present invention: 1. Enhanced hole wall stability: Special soil layers may have loose particles and poor cohesion, and the hole wall is prone to collapse when drilling directly. After clay replacement, the viscosity of the clay can effectively fill the pores in the soil layer, enhance the integrity and cohesion of the soil, and better maintain the stability of the hole wall during rotary drilling, reduce the risk of hole collapse, and ensure construction safety and hole quality. For example, in sandy soil layers, the probability of hole wall collapse after clay replacement can be reduced by about 60% compared to direct drilling.

[0013] 2. Reduced drilling difficulty: Some special soil layers may contain hard impurities or have a high density. When drilling directly, the drill bit will wear quickly and the drilling efficiency will be low. After the clay is replaced, the soil is relatively uniform and soft. The drill bit of the rotary drilling rig is easier to cut into and break the soil, reducing equipment loss and increasing drilling speed. For example, in a soil layer containing more gravel, the drilling speed can be increased by about 40% after replacing clay.

[0014] 3. Improved pile bearing performance: Clay replacement provides a more stable surrounding soil environment for the pile body, and the friction and adhesion between the pile body and the clay are enhanced, which helps to more effectively transfer the building load to the deep soil and improve the bearing capacity of the pile foundation. In contrast, when drilling directly in special soil layers, the interaction between the pile body and the surrounding loose soil is weak, and the bearing performance is limited. According to actual engineering tests, the bearing capacity of the pile foundation after clay replacement can be increased by 30% - 50%.

[0015] 4. Improved pile quality: After clay replacement, the cement slurry can be sprayed continuously and stably to ensure the integrity of the pile body and improve the reliability and durability of high-pressure jet grouting piles. At the same time, the verticality deviation of the drilling rig can be controlled within 1% to avoid the pile body from tilting and affecting the bearing capacity and stability.

[0016] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a flow chart of the method in Example 1 of the present invention; Figure 2 The configuration of the occlusal piles and the hole-forming and clay-filling area in Example 2 of the present invention; Figure 3 The configuration of the occlusal piles and the hole-forming and clay-filling area in Example 3 of the present invention; Figure numerals: 1. Occlusal pile; 2. Drilling and clay replacement area; 3. Occlusal part. DETAILED DESCRIPTION

[0018] Example 1 A method for constructing high-pressure rotary grouting interlocking piles in special soil, including the following steps after construction preparation, pile positioning and equipment placement: Step 1: Rotary drilling: According to the special soil at the construction site and the design layout of the bite pile, select a rotary drilling rig with suitable power and torque to perform rotary drilling. The range of the hole covers all the bite parts of the bite pile, and the depth of the hole is the same as the depth of the bite pile. The special soil includes sandy soil layer, pebble layer, gravel layer and sandy soil layer; this embodiment is a pebble layer, and XCMG XR418F can be used, torque: rated output torque 430kN・m, power: rated power 399kW.

[0019] like Figure 2 As shown, the pile bodies of the interlocking piles in this embodiment are arranged in rows, the centers of the equal-height cross-sections of the pile bodies are on a straight line, and multiple holes are drilled, and the area of ​​each hole covers an interlocking part, which can save costs and achieve basic effects.

[0020] Step 2: Hole inspection: Check the bottom of the hole excavated in step 1 to ensure there is no garbage or debris.

[0021] Step 3: Select clay: According to the on-site construction conditions, select clay with a plasticity index of 15 - 25, a clay content of 40% - 60%, and a water content of 20% - 30%.

[0022] Step 4: Clay replacement: Clean the hole and slowly fill the clay into the hole. When it is filled to 1 / 4 of the height, start to extract the mud in the hole. Extract the mud while filling the clay until the hole is completely filled with clay.

[0023] Step 5: High-pressure rotary jetting: construct holes according to the design plan, insert the shotcrete pipe to the bottom of the hole, perform high-pressure jet grouting, and lift the pipe after the shotcrete is completed; after the high-pressure rotary jetting, the interlocking parts of the piles are in the area where clay is replaced.

[0024] Example 2 A method for constructing high-pressure rotary grouting interlocking piles in special soil, comprising the following steps after construction preparation, pile positioning and equipment placement: Step 1: Rotary drilling: According to the special soil at the construction site and the design layout of the bite pile, select a rotary drilling rig with suitable power and torque to perform rotary drilling. The range of the hole covers all the bite parts of the bite pile, and the depth of the hole is the same as the depth of the bite pile; the special soil includes sandy soil layer, pebble layer, gravel layer and sandy soil layer; this embodiment is a sandy soil layer, and XCMG XR138F can be used; Torque: rated output torque 138kN・m; Power: rated power 129kW.

[0025] like Figure 3As shown, in this embodiment, the interlocking piles are arranged at the joints of the continuous wall, and the pile bodies are interlocked with each other to form a ring. If the centers of the equal-height cross-sections of the pile bodies are not in a straight line, a hole is drilled and the range of the hole covers all the interlocking piles.

[0026] Step 2: Hole inspection: Check the bottom of the hole excavated in step 1.

[0027] Step 3: Select clay: According to the on-site construction conditions, select clay with a plasticity index of 15 - 25, a clay content of 40% - 60%, and a water content of 20% - 30%.

[0028] Step 4: Clay replacement: clean the hole and slowly fill the hole with clay. When it is filled to 1 / 4 of the height, start to extract the mud in the hole. Fill the clay and extract the mud at the same time until the hole is completely filled with clay. Set up a mud pool next to the hole for clay replacement, and the mud extracted from the hole flows into the mud pool.

[0029] Step 5: High-pressure rotary grouting: According to the design plan, holes are drilled in the area where the clay is to be replaced, the shotcrete pipe is inserted to the bottom of the hole, high-pressure jet grouting is performed, and the pipe is lifted after the shotcrete is completed; after the high-pressure rotary grouting, all the piles are in the area where the clay is to be replaced.

[0030] The above-mentioned embodiments are only partial embodiments of the present invention and cannot cover the whole of the present invention. Based on the above-mentioned embodiments and drawings, technical personnel in this field can obtain more implementation methods without paying creative work. Therefore, these implementation methods obtained without paying creative work should be included in the protection scope of the present invention.

Claims

1. A method for constructing high-pressure rotary grouting interlocking piles in special soil, characterized in that: The following steps are involved: Step 1: Rotary drilling: According to the special soil at the construction site and the design layout of the bite pile, select a rotary drilling rig with suitable power and torque to perform rotary drilling. The range of the hole needs to at least cover all the bite parts of the bite pile, and the depth of the hole is the same as the depth of the bite pile; the special soil includes sandy soil layer, pebble layer, gravel layer and sandy soil layer; Step 2: Hole inspection: Check the bottom of the hole dug in step 1 to ensure there is no garbage or debris; Step 3: Choose clay: Choose the appropriate clay according to the on-site construction conditions; the plasticity index of the clay is 15 - 25, the clay content is 40% - 60%, and the water content of the clay is controlled at 20% - 30%; Step 4: Clay replacement: clean the hole and slowly fill the hole with clay. When it is filled to 1 / 4 of the height, start to extract the mud in the hole. Fill the clay and extract the mud at the same time until the hole is completely filled with clay. Step 5: High-pressure rotary grouting: Drill holes according to the design plan, insert the grouting pipe to the bottom of the hole, inject grout with high pressure, and lift the pipe after the grouting is completed; after the high-pressure rotary grouting, at least the interlocking parts of each pile are in the area where the clay is replaced.

2. The method for constructing high-pressure rotary grouting interlocking piles in special soil according to claim 1, characterized in that: The range of holes formed in step 1 covers all the occlusal piles, and the number of holes formed is one or more.

3. The method for constructing high-pressure rotary grouting interlocking piles in special soil according to claim 1, characterized in that: In step three, the step of selecting suitable clay according to the on-site construction conditions includes: selecting the moisture content and plasticity of the clay according to the on-site temperature and the degree of drought; the lower the temperature, the lower the moisture content of the clay selected, and the greater the degree of drought, the higher the moisture content and the stronger the plasticity of the clay selected.

4. The method for constructing high-pressure rotary grouting interlocking piles in special soil according to claim 1, characterized in that: In step 4, a mud pool is set up next to the hole for replacing clay, and the mud extracted from the hole flows into the mud pool.

5. The method for constructing high-pressure rotary grouting interlocking piles in special soil according to claim 1, characterized in that: The pile bodies of the interlocking piles are arranged in rows, and the centers of the circles of the equal-height cross-sections of the pile bodies are on a straight line, so multiple holes are formed by rotary drilling, and the area of ​​each hole covers an interlocking part.

6. The method for constructing high-pressure rotary grouting interlocking piles in special soil according to claim 1, characterized in that: The pile bodies of the interlocking piles interlock with each other. If the centers of the equal-height cross-sections of the pile bodies are not in a straight line, a hole is drilled and the range of the hole covers all the interlocking piles.

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