Disclosure of Invention
In view of the above, the present invention provides a bidirectional stirring method for manufacturing a bottom-expanded powder injection pile by using alkali residues, and the method of the present invention improves the strength, integrity and overall bearing capacity of the powder injection pile.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a bidirectional stirring method for manufacturing a club-footed powder-spraying pile by using alkaline residues, wherein the club-footed powder-spraying pile comprises a conventional pile body and an enlarged pile body; the method comprises the following steps:
(1) placing a pile machine on the leveled field;
(2) performing first drilling, first ash spraying and first stirring, wherein the material of the first ash spraying comprises caustic sludge; then carrying out first lifting, second ash spraying and second stirring, wherein the material of the second ash spraying comprises cement;
(3) performing second drilling, third ash spraying and third stirring, wherein the material of the third ash spraying comprises caustic sludge; and then carrying out second lifting, fourth ash spraying and fourth stirring to obtain the club-footed powder spraying pile, wherein the material of the fourth ash spraying comprises cement.
Preferably, the speed of the first drilling is 0.8-1.0 m/min; the ash spraying amount of the first ash spraying is 100-120 kg/m, and the ash spraying amount of the expanded pile body is 10-20 kg/m larger than that of a conventional pile body.
Preferably, the first lifting speed is 0.8 m/min; the ash spraying amount of the second ash spraying is 25-35 kg/m, and the ash spraying amount of the expanded pile body is 5kg/m larger than that of the conventional pile body; the rotating speed of the second stirring is 20-40 r/min.
Preferably, the speed of the second drilling is 0.8-1.0 m/min; the ash spraying amount of the third ash spraying is 30-60 kg/m, and the ash spraying amount of the expanded pile body is 10-20 kg/m larger than that of the conventional pile body.
Preferably, the speed of the second lifting is 0.5-0.8 m/min; the ash spraying amount of the fourth ash spraying is 15-25 kg/m, and the ash spraying amount of the expanded pile body is 5kg/m larger than that of the conventional pile body; the rotating speed of the fourth stirring is 20-40 r/min.
Preferably, the drill for the bidirectional stirring method includes an inner drill and an outer drill; in the first and second drilling processes, the inner drill bit rotates in reverse phase, and the outer drill bit rotates in forward direction; during the first and second lifts, the inner bit rotates in a forward direction and the outer bit rotates in a reverse direction.
Preferably, the length of the enlarged pile body of the pedestal powder spray pile accounts for 1/6-1/5 of the total length of the pedestal powder spray pile.
Preferably, the diameter of a conventional pile body of the pedestal powder spraying pile is 400-600 mm; the diameter of the enlarged pile body of the pedestal powder spraying pile is 800-1000 mm.
Preferably, the strength grade of the cement is 42.5 MPa.
Preferably, the soil quality of the field is soft soil with high water content.
The invention provides a bidirectional stirring method for manufacturing a club-footed powder-spraying pile by using alkaline residues, wherein the club-footed powder-spraying pile comprises a conventional pile body and an enlarged pile body; the method comprises the following steps: (1) placing a pile machine on the leveled field; (2) performing first drilling, first ash spraying and first stirring, wherein the material of the first ash spraying comprises caustic sludge; then carrying out first lifting, second ash spraying and second stirring, wherein the material of the second ash spraying comprises cement; (3) performing second drilling, third ash spraying and third stirring, wherein the material of the third ash spraying comprises caustic sludge; and then carrying out second lifting, fourth ash spraying and fourth stirring to obtain the club-footed powder spraying pile, wherein the material of the fourth ash spraying comprises cement.
The invention utilizes the alkaline residue mixed with cement as a curing material, utilizes the high water absorbability of the alkaline residue to reduce the water content of soft soil in the range of the powder-sprayed pile body, and improves the strength of the powder-sprayed pile by matching with a small amount of cement powder. A bidirectional stirring method is adopted, four-spraying and four-stirring (four-spraying and four-stirring) is performed, the pile body is uniformly stirred, and the integrity of the pile body is improved; and the bottom of the powder spraying pile is expanded, so that the end resistance of the powder spraying pile is improved, and the integral bearing capacity of the powder spraying pile is improved. The data of the examples show that: the powder-sprayed pile obtained by the invention has good uniformity, the characteristic value of the average bearing capacity of a single pile is 176.5kN, and the average value of unconfined compressive strength reaches 1.14 MPa.
Detailed Description
The invention provides a bidirectional stirring method for manufacturing a club-footed powder-spraying pile by using alkaline residues, wherein the club-footed powder-spraying pile comprises a conventional pile body and an enlarged pile body; the method comprises the following steps:
(1) placing a pile machine on the leveled field;
(2) performing first drilling, first ash spraying and first stirring, wherein the material of the first ash spraying comprises caustic sludge; then carrying out first lifting, second ash spraying and second stirring, wherein the material of the second ash spraying comprises cement;
(3) performing second drilling, third ash spraying and third stirring, wherein the material of the third ash spraying comprises caustic sludge; and then carrying out second lifting, fourth ash spraying and fourth stirring to obtain the club-footed powder spraying pile, wherein the material of the fourth ash spraying comprises cement.
In the invention, the pedestal powder spraying pile comprises a conventional pile body and an enlarged pile body; in the invention, the conventional pile body and the enlarged pile body in the pedestal powder-jet pile are obtained by adjusting the drill bit of the pile machine to have different diameters in the construction process. In the present invention, the length of the under-reamed powder injection pile is preferably less than 20 m. In the invention, the length of the enlarged pile body of the pedestal powder spray pile preferably accounts for 1/6-1/5 of the total length of the pedestal powder spray pile; the diameter of a conventional pile body of the pedestal powder spraying pile is preferably 400-600 mm, and is further preferably 500 mm; the diameter of the enlarged pile body of the pedestal powder spraying pile is preferably 800-1000 mm, and is further preferably 900 mm.
The pile driver is placed on a leveled field.
The method has no special limitation on the leveling mode of the field, and only needs to level the field and vertically and stably place the pile machine on the field; in a specific embodiment of the invention, the shaft of the pile machine is vertical to the field, and the inclination of the drill rod of the drilling machine is less than 1.0%. The invention has no special requirements on the natural elevation of the field, and the natural elevation of the field can only reach the height of the design requirement; if necessary, infrastructure such as water supply, drainage, power supply, roads, temporary buildings and the like which can meet the construction requirements are also required to be established on the site.
After the pile machine is placed, the method carries out first drilling, first ash spraying and first stirring, wherein the material of the first ash spraying comprises alkaline residues; and then carrying out first lifting, second ash spraying and second stirring, wherein the material of the second ash spraying comprises cement.
In the invention, the caustic sludge is preferably sieved by a square hole sieve of 2.5 mm. In the invention, the main component of the alkaline residue is CaCO3、Ca(OH)2、Mg(OH)2、CaCl2NaCl and the like, and has high water absorption and certain gelling property; the water absorption and the gelling property of the alkaline residue are utilized, and the alkaline residue can be combined with cement to form a composite gelling material for improving soft soil and improving the bearing capacity of a foundation, so that the alkaline residue has a resource utilization value; the method is mainly suitable for reinforcing deeper and thicker silt, mucky soil, silt and soft soil foundation with high water content, and has more obvious effect on ultra-soft soil. In the present invention, the strength grade of the cement is preferably 42.5 MPa; the invention further improves the pile body strength of the powder-jet pile by utilizing hydration and mutual excitation of cement. The source of the cement and the caustic sludge in the present invention is not particularly limited, and commercially available products known to those skilled in the art may be used.
In the invention, the ash spraying amount of the first ash spraying is preferably 100-120 kg/m, and the ash spraying amount of the expanded pile body is preferably 10-20 kg/m larger than that of a conventional pile body; in the embodiment of the invention, in the first ash spraying process, the ash spraying amount of the conventional pile body is 100kg/m, and the ash spraying amount of the enlarged pile body is 120 kg/m. In the invention, the speed of the first drilling is preferably 0.8-1.0 m/min.
In the invention, the pile machine is preferably a bidirectional mixing pile machine, and the specific operations of performing first drilling, first ash spraying and first mixing by using the bidirectional mixing pile machine are preferably as follows: according to the diameter adjustment of conventional pile body, the working radius of the inner drill bit stirring blade of the bidirectional stirring pile machine, the control blade connecting rod is in a contraction rotation state, first drilling is carried out, first ash spraying and first stirring are carried out, the conventional pile body is constructed, after the drilling is carried out to the designed elevation of the top surface of the enlarged pile body, the working radius of the inner drill bit stirring blade is adjusted according to the diameter of the enlarged pile body, the control blade connecting rod is in a stretching state, the first drilling is carried out continuously, the first ash spraying and the first stirring are carried out, and the construction is enlarged. In the invention, the first drilling process completes the construction of the pedestal powder-jet pile, namely the pedestal powder-jet pile can be obtained by adjusting the diameter of the drill bit of the pile machine in the first drilling process. In the present invention, the first drilling, the first dust spraying and the first stirring are also referred to as one-spraying-stirring. In the invention, the first drilling, the first dust spraying and the first stirring are carried out simultaneously, namely, the first dust spraying and the first stirring are carried out simultaneously during the first drilling of the drill bit.
In the invention, during the first downward drilling process, the inner drill bit of the bidirectional mixing pile machine preferably rotates in the reverse direction, and the outer drill bit preferably rotates in the forward direction.
In the present invention, the first dust spraying is performed only with caustic sludge in order to absorb the high water content in the soft soil.
In the invention, the ash spraying amount of the second ash spraying is preferably 25-35 kg/m, and the ash spraying amount of the expanded pile body is preferably increased by 5kg/m compared with the ash spraying amount of a conventional pile body; in the embodiment of the invention, the ash spraying amount of the conventional pile body is 30kg/m, and the ash spraying amount of the pedestal pile body is 35 kg/m. In the present invention, the first lifting speed is preferably 0.8 m/min; the rotation speed of the second stirring is preferably 20-40 r/min, and more preferably 30 r/min.
In the invention, the specific operations of first lifting, second ash spraying and second stirring by using the bidirectional stirring pile machine are preferably as follows: keeping the extension state of the inner drill stirring blade of the bidirectional stirring powder spraying pile, carrying out first lifting, second ash spraying and second stirring at a low speed, constructing to enlarge the pile body, lifting to the designed elevation of the top surface of the enlarged pile body, adjusting the working radius of the inner drill stirring blade according to the diameter of the conventional pile body, controlling the blade connecting rod to be in a contraction rotation state, and continuing to carry out first lifting, second ash spraying and second stirring at a low speed. In the present invention, the first lifting, the second ash spraying and the second stirring are also referred to as a second spraying and second stirring. In the invention, the first lifting, the second ash spraying and the second stirring are carried out simultaneously, namely, the second ash spraying and the second stirring are carried out simultaneously during the first lifting of the drill bit.
In the invention, during the first lifting process, the inner drill bit of the bidirectional mixing pile machine preferably rotates in the forward direction, and the outer drill bit preferably rotates in the reverse direction.
In the invention, only the cement is sprayed in the first lifting process, so as to further improve the strength of the alkali residue powder spraying pile.
After the first lifting, the second ash spraying and the second stirring are finished, second drilling, third ash spraying and third stirring are carried out, wherein the material of the third ash spraying comprises alkaline residues; and then carrying out second lifting, fourth ash spraying and fourth stirring to obtain the club-footed powder spraying pile, wherein the material of the fourth ash spraying comprises cement.
In the invention, the ash spraying amount of the third ash spraying is preferably 30-60 kg/m; the ash spraying amount of the enlarged pile body is preferably 10-20 kg/m larger than that of the conventional pile body; in the embodiment of the invention, in the third ash spraying process, the ash spraying amount of the conventional pile body is 30kg/m, and the ash spraying amount of the enlarged pile body is 40 kg/m. In the present invention, the second drilling speed is preferably 0.8 to 1.0m/min, and more preferably 0.9 m/min. In the invention, in the second drilling process, the inner drill bit of the bidirectional mixing pile machine preferably rotates in the reverse direction, and the outer drill bit preferably rotates in the forward direction.
In the invention, the process of performing the second drilling down by using the bidirectional mixing pile machine is the same as the process of performing the first drilling down, and the detailed description is omitted, and the difference is only that the ash spraying amount is adjusted. In the present invention, the second drilling, the third dust spraying and the third stirring are also referred to as three-spraying three-stirring. In the invention, the second drilling, the third dust spraying and the third stirring are carried out simultaneously, namely, the third dust spraying and the third stirring are carried out simultaneously during the second drilling of the drill bit.
In the invention, only the alkali slag is sprayed in the second drilling process, so that the cement hydration is excited by utilizing the gelation property and the alkaline environment, and the strength of the powder-sprayed pile body is improved.
In the invention, the fourth ash spraying amount is preferably 15-25 kg/m, and the ash spraying amount of the expanded pile body is preferably increased by 5kg/m compared with the ash spraying amount of a conventional pile body; in the specific embodiment of the invention, the ash spraying amount of the conventional pile body is 20kg/m, and the ash spraying amount of the pedestal pile body is 25 kg/m. In the invention, the second lifting speed is preferably 0.5-0.8 m/min, and more preferably 0.6-0.7 m/min; the rotation speed of the fourth stirring is preferably 20-40 r/min, and more preferably 30 r/min. In the invention, during the second lifting process, the inner drill bit of the bidirectional mixing pile machine preferably rotates in the forward direction, and the outer drill bit preferably rotates in the reverse direction.
In the invention, the specific operations of performing the second lifting, the fourth ash spraying and the fourth stirring by using the bidirectional stirring pile machine are preferably as follows: keeping the extension state of the inner drill bit stirring blade of the bidirectional stirring powder spraying pile, slowly carrying out second lifting, fourth dust spraying and fourth stirring, constructing an enlarged pile body, adjusting the working radius of the inner drill bit stirring blade according to the diameter of the conventional pile body after lifting to the designed elevation of the top surface of the enlarged pile body, controlling the blade connecting rod to be in a contraction rotation state, and continuously carrying out second lifting, fourth dust spraying and fourth stirring at a low speed; when the drill bit is lifted to 0.5m below the elevation of the powder spraying pile top, the speed regulating motor is closed, the ash supply is stopped, and the residual ash in the pipe is fully utilized for spraying and stirring; lifting the drill bit to 0.2m above the ground, and closing the stirring machine to complete the preparation of the club-footed powder-spraying pile; and moving the machine to prepare the next powder spraying pile. In the present invention, the second lifting, the fourth ash spraying and the fourth stirring are also referred to as four-spraying four-stirring. In the invention, the second lifting, the fourth ash spraying and the fourth stirring are carried out simultaneously, namely, the fourth ash spraying and the fourth stirring are carried out simultaneously during the second lifting of the drill bit.
In the invention, when a plurality of under-reamed powder spraying piles are required to be prepared to solidify soft soil, the diameter, the pile length and the spacing of the under-reamed powder spraying piles are required to be selected according to field construction conditions and stable checking calculation results in practical application, and the requirement of post-construction settlement is required to be met. In a specific embodiment of the invention, the net spacing between the pedestal powder spraying piles is preferably not more than 4.0 times the diameter of the pedestal pile body of the powder spraying pile.
Fig. 1 is a schematic structural diagram of a drill bit for a bidirectional mixing pile machine, wherein 1 is an outer drill rod double-layer impeller, 2 is an inner drill rod double-layer blade, 3 is a telescopic adjusting rod, and 4 is an ash spraying opening. The two layers of impellers of the outer drill rod and the drill bit of the drill bit for the bidirectional stirring pile machine are respectively in an integral state, play a role in pressing dust while drilling and stirring, prevent powder from overflowing during dust spraying, and play a role in uniformly distributing the powder in a pile body; the drill bit of the inner drill rod has two layers of four blades, each layer of blade is separated from each other, 4 blades are positioned on the helicoid, the two layers of blades are staggered, the tail ends of the blades are raised in a radian mode, the edges of the blades are provided with teeth, and the soil cutting and stirring effects are strong; the ash spraying port is located between two layers of blades of the inner drill bit, and ash is sprayed by the central pipe, so that the defect that the blades are easy to block holes is overcome.
Fig. 2 is a flow chart of the bidirectional stirring method for manufacturing the pedestal powder-jet pile of the invention, and the specific flow is as follows: leveling a field, then placing a bidirectional mixing pile machine in place, and performing first drilling (constructing a conventional pile body and then constructing and enlarging the pile body); performing first lifting (firstly constructing and enlarging the pile body, and then constructing a conventional pile body); performing second drilling (constructing the conventional pile body first and then constructing and expanding the pile body); and (5) performing second lifting (firstly constructing and enlarging the pile body, and then constructing the conventional pile body), and shifting the pile machine after pile forming.
The following will explain the two-way stirring method for manufacturing a bottom-enlarged powder injection pile by using caustic sludge according to the present invention in detail with reference to examples, but they should not be construed as limiting the scope of the present invention.
Example 1
(1) Leveling a field, positioning a bidirectional mixing pile machine in place, ensuring that a shaft of the pile machine is kept vertical, and ensuring that the inclination of a drill rod of a drilling machine is less than 1.0%;
(2) adjusting the working radius of the stirring blade of the inner drill bit according to the diameter of the conventional pile body, controlling the blade connecting rod to be in a contraction rotation state, performing first drilling (the drilling speed is 0.8m/min), first ash spraying (the quantity of sprayed alkali slag is 100kg/m) and first stirring, constructing the conventional pile body, wherein the diameter of the pile body is 500mm, and drilling until the designed elevation of the top surface of the pile body is enlarged; adjusting the working radius of the stirring blade of the inner drill bit according to the diameter of the enlarged pile body, controlling the blade connecting rod to be in an extension state, continuously performing first downward drilling, first ash spraying (the amount of sprayed alkali slag is 120kg/m) and first stirring, constructing and enlarging the pile body, and setting the diameter of the pile body to be 800 mm; 1/5 expanding the pile body to occupy the whole powder spraying pile length, in the process, the inner drill bit rotates reversely, and the outer drill bit rotates forwardly;
(3) keeping the extension state of the inner drill bit stirring blade, slowly carrying out first lifting (the lifting speed is 0.8m/min), second ash spraying (the cement spraying amount is 35kg/m) and second stirring (30r/min), constructing an enlarged pile body, adjusting the working radius of the inner drill bit stirring blade according to the diameter of a conventional pile body after the top surface of the enlarged pile body is designed to be an elevation, controlling a blade connecting rod to be in a contraction rotation state, and continuously carrying out first lifting, second ash spraying (the cement spraying amount is 30kg/m) and second stirring at a low speed to construct the conventional pile body; in the process, the inner drill bit rotates in the forward direction, and the outer drill bit rotates in the reverse direction;
(4) adjusting the working radius of a drill bit stirring blade of the internal bidirectional stirring pile machine according to the diameter of a conventional pile body, controlling a blade connecting rod to be in a contraction rotation state, performing second drilling (the speed is 0.8m/min), third ash spraying (the alkali slag spraying amount is 30kg/m) and third stirring, constructing the conventional pile body, adjusting the working radius of the internal drill bit stirring blade according to the diameter of the enlarged pile body after drilling to the designed elevation of the top surface of the enlarged pile body, controlling the blade connecting rod to be in an extension state, and continuing to perform second drilling, third ash spraying (the alkali slag spraying amount is 40kg/m) and third stirring to construct the enlarged pile body; in the process, the inner drill bit rotates reversely, and the outer drill bit rotates forwardly;
(5) keeping the extension state of the inner drill bit stirring blade of the bidirectional stirring powder spraying pile, slowly carrying out second lifting (0.6m/min), fourth cement spraying (the cement spraying amount is 25kg/m) and fourth stirring (20r/min), constructing a bottom expanded pile body, lifting to the designed elevation of the top surface of the expanded pile body, adjusting the working radius of the inner drill bit stirring blade according to the diameter of the conventional pile body, controlling the blade connecting rod to be in a contraction rotation state, continuously carrying out second lifting, fourth cement spraying (the cement spraying amount is 20kg/m) and fourth stirring at a low speed, and constructing the conventional pile body; in the process, the inner drill bit rotates in the forward direction, and the outer drill bit rotates in the reverse direction; when the drill bit is lifted to 0.5m below the elevation of the powder spraying pile top, the speed regulating motor is closed, the ash supply is stopped, and the residual ash in the pipe is fully utilized for spraying and stirring; lifting the drill bit to 0.2m above the ground, and closing the stirring machine to complete the preparation of the club-footed powder-spraying pile; and moving the machine to prepare the next powder spraying pile.
3d after pile forming, adopting light dynamic sounding (N)10) The uniformity of the upper pile body is checked, and the uniformity is good.
And 7 days after pile forming, adopting a shallow excavation pile head for inspection, wherein the excavation depth exceeds 0.5m below a dust stop surface, inspecting the stirring uniformity, and measuring the diameter of a pile body to meet the requirements.
After the pile is formed for 28d, a pile loading method is adopted in the single pile static load test, the average bearing capacity characteristic value of the single pile is tested to be 176.5kN, and the design requirement is met.
After the pile is formed for 28d, a double-pipe single-action sampling drill is used for taking a core sample, an unconfined compressive strength test of the alkali residue cement soil is carried out, and the average value of the sample reaches 1.14 MPa.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.