Stirring shaft for cement mixing pile construction and use method thereof

Abstract

The invention discloses a stirring shaft for cement mixing pile construction and a using method thereof.The stirring shaft comprises a hollow drill rod, the lower end of the hollow drill rod is closed to form a conical drill bit, a plurality of plane vibrators and stirring blades are arranged on the outer side wall of the hollow drill rod, and the plane vibrators are distributed in the axial direction of the hollow drill rod at intervals; the stirring blades are arranged below the plane vibrator; a slurry feeding pipeline is arranged in the hollow drill rod, extends to the position below the stirring blades and extends out in the circumferential direction of the hollow drill rod, and a slurry feeding opening is formed. According to the method, a plane vibration method is adopted, vibration compaction is conducted on solidified soil within the range of a pile body in the drill lifting process of mixing pile construction, redundant holes in the pile body are eliminated, the strength of the pile body of the mixing pile can be further improved on the basis of chemical solidification, and the foundation treatment capacity of the mixing pile is improved.

Description

Technical Field

[0001] The invention relates to the technical field of cement soil mixing piles, and in particular to a mixing shaft for cement soil mixing pile construction and a use method thereof. Background Art

[0002] Cement-soil mixing pile technology is a soft soil in-situ reinforcement technology widely used at home and abroad. During construction, a curing agent is sprayed into the soil while the curing agent and the soil are evenly mixed. A series of physical and chemical reactions between the curing agent and the soil are used to bond the soil particles together, thereby forming a vertical pile in the soil. The vertical pile and the surrounding soil form a cement-soil mixing pile composite foundation, thereby achieving the purpose of reinforcing the soft soil foundation.

[0003] During the construction of cement-soil mixing piles, the mixing blades cut the soil and forcefully mix the soil and curing agent, creating a large number of pores in the pile body. Some of the pores will be filled with the cementing products of the curing agent hydration reaction, but the remaining pores cannot be eliminated by self-weight consolidation inside the solidified pile body and will remain inside the pile body for a long time. The pores that cannot be filled with cementing products will affect the uniformity and density of the mixing pile body, becoming the weak points of strength inside the mixing pile body, which is not conducive to the development of pile body strength. Therefore, the increase in the internal porosity of the pile body caused by the reshaping of the in-situ soil during the construction of the mixing pile is an important factor limiting the reinforcement effect of the mixing pile. Eliminating the excess pores inside the pile body can further improve the strength of the mixing pile body on the basis of chemical curing and improve the foundation treatment capacity of the mixing pile. At present, there is no relevant technical method to effectively eliminate the excess pores in the mixing pile body. Summary of the invention

[0004] The purpose of the present invention is to provide a mixing shaft for cement soil mixing pile construction and a use method thereof, which can simultaneously vibrate and compact the single pile body during the mixing pile construction process, reduce the pores remaining inside the pile body, and thus improve the solidification effect of the mixing pile on the soil.

[0005] The technical solution adopted by the present invention is:

[0006] A mixing shaft for cement-soil mixing pile construction, comprising a hollow drill rod, the lower end of which is sealed to form a conical drill bit, a plane vibrator and a mixing blade are arranged on the outer wall of the hollow drill rod, a plurality of the plane vibrators are evenly spaced along the axial direction of the hollow drill rod, and the mixing blade is arranged below the plane vibrator;

[0007] The mixing blades rotate upward and open when the hollow drill rod is drilling, mixing the curing agent slurry and the soil, and rotate downward and close when the hollow drill rod is lifted upward, fitting against the outer wall of the hollow drill rod;

[0008] A slurry delivery pipeline is arranged inside the hollow drill rod. The slurry delivery pipeline extends to the bottom of the stirring blade and extends out along the circumference of the hollow drill rod to form a slurry delivery port.

[0009] The present invention arranges a vibrator on the outside of the drill rod, and through vibration, reduces the porosity of the mixing pile body, improves the density and uniformity of the pile body, thereby further improving the strength of the mixing pile body on the basis of chemical solidification, and improving the construction quality of the mixing pile. The surface vibration method is adopted, and after the single mixing pile is sprayed and stirred, the pile body is vibrated and compacted during the process of lifting the drill, eliminating the redundant pores generated by the cutting of the mixing blade, and further enhancing the reinforcement effect of the mixing pile.

[0010] Furthermore, a plurality of circular windows are provided at equal intervals along the axial direction of the hollow drill rod, and a planar vibrator is installed in the hollow drill rod, with a vibration plate thereof extending out of the circular windows.

[0011] By adopting the above technical solution and utilizing the space inside the hollow drill rod to install the vibrator, the vibrator motor can be protected and the wiring of the motor is convenient.

[0012] Furthermore, the outer diameter of the vibration plate is equal to the aperture of the circular window, and the vibration plate and the circular window are sealed and connected via a polymer shock-absorbing material.

[0013] By adopting the above technical solution, the plane vibration plate and the drill rod are flexibly connected through a polymer shock-absorbing sealing ring, which not only maintains the sealing of the drill rod and prevents soil from entering the drill rod, but also does not hinder the plane vibrator installed in the circular window from vibrating and compacting the soil. In addition, it can also reduce the vibration impact of the vibration plate on the hollow drill rod.

[0014] Furthermore, the stirring blades are arranged in pairs, and a plurality of pairs are symmetrically distributed at intervals along the axial direction of the hollow drill rod to improve the stirring effect.

[0015] Furthermore, the root of each stirring blade is hinged to the outer wall of the hollow drill rod through a hinge. The structure is simple and reliable, and the stirring blade can be automatically opened or retracted under the resistance of the soil body driven by the drill rod.

[0016] Furthermore, the stirring blade is in a straight line shape, opening and contracting along the axial direction of the hollow drill rod, and the retraction angle is 0 to 90 degrees. When the retraction angle is 0 degrees, the stirring blade fits the outer wall of the hollow drill rod, reducing the resistance of the drill rod to lift upward; when the retraction angle is 90 degrees, the stirring blade is 90 degrees with the axis of the hollow drill rod, improving the stirring effect.

[0017] Furthermore, a grouting port is provided at the lower end of the hollow drill rod, the grouting port is located between the conical drill bit and the mixing blade, and the lower end of the slurry delivery pipeline passes through the grouting port and is fully welded to the grouting port to prevent soil from entering the drill rod through the grouting port and fix the slurry delivery pipeline.

[0018] The method for using any one of the above-mentioned mixing shafts for cement soil mixing pile construction comprises the following steps:

[0019] (1) Install the hollow drill rod on the drilling rig, connect the vibration motor of the plane vibrator to the power supply, and extend the upper end of the slurry delivery pipeline to rotate and connect to the slurry delivery pipeline;

[0020] (2) The hollow drill rod is drilled downward, and at the same time, the curing agent station delivers curing agent slurry to the slurry delivery pipeline through the slurry delivery pipeline. The stirring blade is opened under the action of soil resistance to stir and mix the curing agent slurry and the soil;

[0021] (2) After the hollow drill rod is drilled to the specified depth, all the plane vibrators are started, the hollow drill rod is lifted upward, and the stirring blades are retracted accordingly.

[0022] (3) When each plane vibrator is lifted out of the ground, the plane vibrator is immediately turned off until the hollow drill rod is completely lifted out of the ground, completing the mixing reinforcement and vibration compaction of the mixing pile.

[0023] Beneficial effects of the present invention:

[0024] 1. Effectively reduce the porosity of the mixing pile body, improve the strength and uniformity of the single pile, and improve the construction quality of the mixing pile;

[0025] 2. Vibration compaction and mixing reinforcement are carried out simultaneously, which does not increase the difficulty and workload of mixing pile construction operations, nor does it increase the technical level requirements for construction personnel.

[0026] 3. The present invention solves the problem of increased porosity caused by the remodeling of the in-situ soil during the construction of mixing piles, and further improves the strength of the mixing pile body on the basis of chemical solidification. It is particularly suitable for the reinforcement treatment of mixing piles in sandy soils, is simple and efficient to operate, and has significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic cross-sectional view of the stirring shaft structure of the present invention.

[0028] Figure 2 for Figure 1 Side view of.

[0029] Figure 3 This is a diagram of the changing state of the mixing blades when drilling.

[0030] Among them, 1. slurry delivery pipeline; 2. flat vibrator; 3. polymer shock-absorbing sealing ring; 4. stirring blade; 5. hinge; 6. spraying port; 7. circular window. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention more clear, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and a preferred implementation manner.

[0032] Example 1

[0033] See also Figure 1-Figure 3 The present embodiment provides a mixing shaft for cement-soil mixing pile construction, including a hollow drill rod, the lower end of the hollow drill rod is closed to form a conical drill bit, the outer wall of the hollow drill rod is provided with a plane vibrator 2 and a mixing blade 4 in sequence from top to bottom, and a slurry delivery pipe 1 is provided inside the hollow drill rod, the slurry delivery pipe 1 extends to the bottom of the mixing blade 4 and extends out along the circumference of the hollow drill rod to form a slurry delivery port.

[0034] In specific implementation, the strength and rigidity of the hollow drill rod need to meet the requirements for soil mixing, and its inner diameter is generally 15 to 20 cm. In this embodiment, a plurality of circular windows 7 are provided at equal intervals along the axial direction on the outer wall of the hollow drill rod, and the circumferential side walls of the circular windows 7 protrude axially to form a boss protruding about 0.5 cm from the outer surface of the hollow drill rod, which is convenient for installing the plane vibrator 2, and the center distance between two adjacent circular windows 7 is about 0.5 to 1 m, and the diameter of the circular window 7 is equal to the outer diameter of the hollow drill rod.

[0035] The plane vibrator 2 is a prior art, and all the existing plane vibrators in the art are applicable to the present invention. In this embodiment, a plane vibrator 2 with a circular vibration plate is selected to fit the circular window 7 on the hollow drill rod. In other embodiments, the window may also be rectangular, and fits a vibrator with a rectangular vibration plate.

[0036] The vibration motor of the plane vibrator 2 is fixedly installed in the hollow drill rod, and the vibration plate of the plane vibrator extends out from the circular window 7. The vibration plate and the circular window are sealed and connected by a polymer shock-absorbing seal 3 made of a polymer shock-absorbing material. The polymer sealing material has enough elastic space to ensure that the vibration plate can vibrate.

[0037] In this embodiment, a total of 4 pairs of straight-line stirring blades 4 are provided, and the 4 pairs of stirring blades 4 are symmetrically distributed along the axial direction of the hollow drill rod, and the center distance between two adjacent layers of stirring blades is about 30 cm. The stirring blades 4 are connected to the hollow drill rod by a hinge 5, and the stirring blades 4 can be opened and retracted along the axial direction of the hollow drill rod, and the retraction angle is 0 to 90 degrees. In other embodiments, the form, number and spacing of the stirring blades 4 can be selected according to the construction conditions. For example, the stirring blades 4 can also be in the form of an auger.

[0038] In this embodiment, the slurry delivery pipe 1 is built into a hollow drill rod, and its outer diameter is 2 to 3 cm. A circular hole is opened 20 cm above the conical drill bit of the hollow drill rod as a grouting port 6. The diameter of the grouting port is equal to the outer diameter of the slurry delivery pipe. The lower end of the slurry delivery pipe 1 passes through the grouting port 6 and is fully welded to the grouting port 6.

[0039] Example 2

[0040] This embodiment provides a method for using a mixing shaft for cement-soil mixing pile construction as described in Embodiment 1, comprising the following steps:

[0041] (1) Install the hollow drill rod on the drilling rig, connect the vibration motor of the plane vibrator to the power supply, and extend the upper end of the slurry delivery pipeline to rotate and connect to the slurry delivery pipeline;

[0042] (2) The hollow drill rod is drilled downward, and at the same time, the curing agent station delivers curing agent slurry to the slurry delivery pipeline through the slurry delivery pipeline. The stirring blade is opened under the action of soil resistance to stir and mix the curing agent slurry and the soil;

[0043] (2) After the hollow drill rod is drilled to the specified depth, all the plane vibrators are started, the hollow drill rod is lifted upward, and the stirring blades are retracted accordingly.

[0044] (3) When each plane vibrator is lifted out of the ground, the plane vibrator is immediately turned off until the hollow drill rod is completely lifted out of the ground, completing the mixing reinforcement and vibration compaction of the mixing pile.

[0045] Application Example 3

[0046] In order to verify the effect of the present invention on improving the strength of the cement-soil mixing pile body, an SCJB-C model single-shaft mixing pile machine was used, and the mixing shaft provided by the machine and the mixing shaft described in Example 1 of the present invention (replacing the original mixing shaft) were used to carry out cement-soil mixing pile construction tests. The test site was selected from a foundation treatment project in Nanjing Jiangbei New District. The foundation to be treated was distributed with thick soft soil layers and sand layers. When the present invention was applied, construction was carried out according to the method described in Example 2.

[0047] 28 days after the construction was completed, the test piles were taken to test their porosity, uniformity and strength. The results are shown in Table 1.

[0048] The porosity test method refers to the "Standard for Geotechnical Test Methods" (GB / T 50123-2019)

[0049] The uniformity and strength testing methods refer to the "Highway Engineering Cement Mixing Piles Quality Testing Regulations" (DB32 / T2283-2012)

[0050] Table 1

[0051] Porosity strength Uniformity Test pile of the present invention 10％ 1.5MPa Uniform Comparative test pile 20％ 0.9MPa Uneven

[0052] It can be seen from Table 1 that the cement-soil mixing piles constructed using the present invention are significantly better in uniformity and pile body strength than conventional mixing piles, and the porosity is greatly reduced.

[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications are also within the protection scope of the present invention.

Claims

1. A mixing shaft for cement soil mixing pile construction, comprising a hollow drill rod, characterized in that: The lower end of the hollow drill rod is sealed to form a conical drill bit, and the outer wall of the hollow drill rod is provided with a plane vibrator (2) and a stirring blade (4), a plurality of the plane vibrators (2) are evenly spaced along the axial direction of the hollow drill rod, and the stirring blade (4) is arranged below the plane vibrator (2); The stirring blade (4) rotates upward and opens when the hollow drill rod is drilled down to stir and mix the curing agent slurry and the soil, and rotates downward and closes to fit the outer wall of the hollow drill rod when the hollow drill rod is lifted upward; A slurry delivery pipe (1) is provided inside the hollow drill rod. The slurry delivery pipe (1) extends to the bottom of the stirring blade (4) and extends out along the circumference of the hollow drill rod to form a slurry delivery port.

2. A mixing shaft for cement soil mixing pile construction according to claim 1, characterized in that: A plurality of circular windows are provided at equal intervals along the axial direction of the hollow drill rod. A plane vibrator is installed in the hollow drill rod, and a vibration plate thereof extends out of the circular windows.

3. A mixing shaft for cement soil mixing pile construction according to claim 2, characterized in that: The outer diameter of the vibration plate is equal to the aperture of the circular window, and the vibration plate and the circular window are sealed and connected through a polymer shock-absorbing material.

4. A mixing shaft for cement soil mixing pile construction according to claim 1, characterized in that: The stirring blades (4) are arranged in pairs, and a plurality of pairs are symmetrically distributed at intervals along the axial direction of the hollow drill rod.

5. A mixing shaft for cement soil mixing pile construction according to claim 4, characterized in that: The root of each stirring blade (4) is hinged to the outer side wall of the hollow drill rod through a hinge.

6. A mixing shaft for cement soil mixing pile construction according to claim 5, characterized in that: The stirring blade (4) is in a straight line shape and is opened and retracted along the axial direction of the hollow drill rod, with a retraction angle of 0 to 90 degrees.

7. A mixing shaft for cement soil mixing pile construction according to claim 1, characterized in that: A grouting port is provided at the lower end of the hollow drill rod, and the grouting port is located between the conical drill bit and the stirring blade (4). The lower end of the slurry delivery pipeline (1) passes through the grouting port and is fully welded to the grouting port.

8. The method for using a mixing shaft for cement soil mixing pile construction according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) The hollow drill rod is mounted on the drilling rig, the vibration motor of the plane vibrator (2) is connected to a power source, and the upper end of the slurry delivery pipe (1) is extended and rotated to connect to the slurry delivery pipeline; (2) The hollow drill rod is drilled downward, and at the same time, the curing agent station delivers curing agent slurry to the slurry delivery pipeline through the slurry delivery pipeline. The stirring blade is opened under the action of soil resistance to stir and mix the curing agent slurry and the soil; (2) After the hollow drill rod is drilled to the specified depth, all planar vibrators are started, the hollow drill rod is lifted upward, and the mixing blades are retracted accordingly; (3) When each plane vibrator is lifted out of the ground, the plane vibrator is immediately turned off until the hollow drill rod is completely lifted out of the ground, completing the mixing reinforcement and vibration compaction of the mixing pile.

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