CA1234698A - Cast-in-place concrete pile construction - Google Patents
Cast-in-place concrete pile constructionInfo
- Publication number
- CA1234698A CA1234698A CA000471534A CA471534A CA1234698A CA 1234698 A CA1234698 A CA 1234698A CA 000471534 A CA000471534 A CA 000471534A CA 471534 A CA471534 A CA 471534A CA 1234698 A CA1234698 A CA 1234698A
- Authority
- CA
- Canada
- Prior art keywords
- shell
- hollow
- concrete
- soil
- tube
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Piles And Underground Anchors (AREA)
Abstract
ABSTRACT OF THE INVENTION
"IMPROVEMENTS RELATING TO CAST-IN-PLACE CONCRETE
PILE CONSTRUCTION "
A method of constructing a cast-in-place concrete pile wherein the improvements comprises excavating the soil at the lower end of the shell to an extent larger than the shell in its cross-section for forming an enlarged base and forcing a second charge of concrete through a pressurizing tube the open end of which is extended to the lower end of the excavated portion for penetrating the second charge of concrete into the region surrounding the base and the shell after a first charge of concrete fills and sets in the excavated portion and the shell, thereby improving the end bearing power and the skin friction of the pile.
"IMPROVEMENTS RELATING TO CAST-IN-PLACE CONCRETE
PILE CONSTRUCTION "
A method of constructing a cast-in-place concrete pile wherein the improvements comprises excavating the soil at the lower end of the shell to an extent larger than the shell in its cross-section for forming an enlarged base and forcing a second charge of concrete through a pressurizing tube the open end of which is extended to the lower end of the excavated portion for penetrating the second charge of concrete into the region surrounding the base and the shell after a first charge of concrete fills and sets in the excavated portion and the shell, thereby improving the end bearing power and the skin friction of the pile.
Description
~34698 This invention relates to pile constructions, particularly to a method of constructing a cast-in-place concrete pile with improved end bearing power and s~in friction.
Cast-in-place concrete pile are generally divided in two groups: cased piles in which a thin metal casing is driven into the ground to serve as a form, and uncased piles where the concrete is placed directly against the soil. There are several methods of constructing uncased piles and cased piles. In one method of casting a cased pile, a core is driven with the casing. After the core is withdrawn, the casing is filled with concrete. The casing may be a thin metal shell. In some methods the shell may be closed at the lower end with a flat or cone-shaped boot.
Uncased piles may be formed by a temporary casing which is pulled out after concrete is placed. They may be also established by drilling holes in the ground and and casting concrete in the holes.
It is known that cast-in-place concrete piles may be formed with enlarged bases to reduce the intensity of the load transferred to the bearing strata. Many methods are available for such pile constructions. In one method a shell which is initially partly filled with concrete is driven by an internal core, the shell is raised and the core is forced downward to force the concrete out for forming an enlarged base. Therea~ter, the casing is filled with concrete and then pulled out. However, the methods utili~ed heretofore are found defficient as it is difficult to achieve a desired extent of enlargement in base formation. In addition, the conventional cased piles usually develop reduced skin friction as there are gaps around the formed piles which are resulted while driving the shells.
An object of the invention is to provide a method of constructing a cast-in-place concrete pile with improved end bearing power and skin friction.
Another object of the invention is to provide a method which improves the constructions of a cast-in-place concrete pile to a form with a iarger base formation and an effective surface area in tight abutment with the surrounding soil.
The foregoing and other objects can be achieved in accordance with the invention through the provision of a method of constructing a cast-in-place concrete pile which comprises: (a) driving a shell which is closed temporarily at its lower end with a boots to a certain depth in the ground; (b) forcing the boot of the shell by hammering a core -to separate it from the lower end of the shell and to extend it to a further depth, thereby causing a hollow between the end of the shell and the --`. i23~69l3 boot; (c) removing the core from the shell; (d) enlarging the width of the hollow by soil excavation; and (e) placing concrete into the enlarged hollow and the shell.
According to the invention, the method may further includes step (d) preparing a rotary shaft with collapsible blades and lowering said shaft until it reaches the hollow. The collapsible blades may be made of steel chains.
According to the invention, the method m~y further comprises the steps: placing a central tube passing through the shell and extending beyond the bottom side of the enlarged hollow prior to step (e) and forcing a further charge of concrete through said tube after step (e) to cause the concrete to penetrate into the soil surrounding the enlarged base formed and the gap around the shell.
In one aspect of the invention, the method comprises:
ta) driving a core with a shell into the ground; (b) removing the core from the shell; (c) placing a central tube passing through the shell and extending it to the end of the shell; (d) placing concrete into the shell through the annular space around the central tube; (e) allowing the concrete to set; and tf) forcing a further charge of concrete through the central tube to cause it to penettate into the soil and the gap surrounding the shell.
The presently preferred exemplary embodiment will be described in detail with reference to the following ~23'~698 drawings, wherein:
Fig. 1 illustrates the shell and core which is placed in the ground;
Fig. 2 illustrates the driving of the boot to separate it from the shell;
Fig. 3 illustrates a rotary shaft with collapsible blades placed in the hollow;
Figs. 4 and 5 illustrates the operation of the shaft for enlargement of the hollow;
Fig. 6 shows a collapsible reinforcement frame placed in the shell and the hollow;
Fig. 7 illustrates that the shell and the hollow is provided with a pressurizing tube;
Fig. 8 is a view after the shell and the hollow are L il led with,concrete;
Fig. 9 is a view after -the soil stabilizing agent is introduced through the pressurizing tube; and Fig. 10 is a view after the pile construction is complete.
"
Referring to Fig. 1, a shell 10 which is in this embodiment pre~rably a precast concrete pile is provided with a cone shaped boot 11 at its lower end. The shell 10 is driven into the ground. When it reaches a certain depth, the cone shaped boot 11 is forced by hammering a core lOa tO
be separated from the lower end oE the shell.
~ 23~6~D~
~lammering is continued until the boot 11 extends into a Eurther depth of about lm to 2 m, thereby resulting a hollow 12 between the lower end of the shell and the boot 11, as shown in Fig. 2.
The hollow 12 is further enlarged by soil excavation. It is requird a rotary shaft with collapsible blades which can be passed through the shell 10 and then stretched out at beyond the end of the shell.
Preferably, steel chains are used as blades in this embodiment. A rotary shaft 13 which is incorporated with steel chains 15 is lowered into the hollow 12 through the shell 10 and then rotated by a driving means, such as motor. The lengths of the chains 15 may be chosen according to how much extent of the base is desired.
The shaft 13 is extended to a depth above the boot as shown in.Fig. 3.
As the shaft 13 is rotated, the steel chains 15 are spinning and beating the soil as shown in Fig. 4. For ef~ective beating of the soil, the shaft may be rotated in clockwise and counter-clockwise directions alternatively. Water is jetted into the hollow 12 and the soil is churned into slurry which is then bailed out by a known manner. Large size stones and the like which can not be suspended in the slurry are beaten down by the chains 15 into the contracted space above the boot 11 as shown in Fig. 5. As the soil is excavated, the hollow 12 is enlarged. The enlarged hollow 12 may have a size or radius substantially similar to the length of a steel ` ~3~6~8 chain 15. The volume of the enlarged hollow 12 can be determined by a supersonic detector.
To keep the rotary shaft 13 in a coaxial relationship with the shell 10, retaining members 17 which can be made of elastic material,such as rubber are provided between the rotary shaft 13 and the shell 10.
For reinforcing purpose, a steel frame 14 which is preferably collapsible is placed in the enlarged hollow 12 and the shell 10 prior to casting concrete, as shown in Fig. 7.
There is further inserted a pressurizing tube 16 which is extended into the hollow 12 through the shell 10 prior to casting concrete. The tube 16 is advantageously extended to a region below the enlarged portions of the hollow 12 which will be filled with concrete as shown in Figs. 8 and 9, so that the open end of the tube will not be embedded in the concrete.
A charge of concrete is poured into the hollw 12 through the annular space around the tube 16. To avoid ~L~clc~ ~6 the ~ at the end of the tube 16, the tube is supplied with a flow of water during operation. After the shell 10 and the enlarged hollow 12 are filled with concrete as shown in Fig. 8, the concret~ is allowed to set for 4-5 hours.
Then a soil stabilizing agent is supplied into the tube 15 and then forced to penetrate into the soil surrounding the enlarged concrete base 18 as shown in ~23469~
Fig. 9. Subsequent supplying of the soil s-tabilizing agent causes the agent to rise through the region surrounding the enlarged base 18 to the region around the shell 10, thereby improving the soil density and stability around the shell 10 and the enlarged base 18.
Thereafter, a further charge of concrete is forced through the tube 16 and penetrated into the soil surrounding the enlarged base 18, thereby increasing the size of the base 18 as well as its-skin friction. As the concrete is supplied through a high pressure, it is then penetrated into the gap around the shell 10 from the base as illustrated in Fig. 10. When the concrete sets, an improved skin friction is developed around the shell 10.
This step is important for improving the skin friction of the pile. The construction of a pile is complete at this stage.
It can be appreciated that the method according to the invention offers an improved pile construction - with an effective enlarged base which increases the end bearing power of the pile and with an effective surface area adhering to the surrounding soil which improves the skin friction.
With the invention thus explained, it is apparent that obvious modifications and variations can be made without departing from the scope of the invention. It is therefore intended that the invention be limited only as indicated in the appended claims.
Cast-in-place concrete pile are generally divided in two groups: cased piles in which a thin metal casing is driven into the ground to serve as a form, and uncased piles where the concrete is placed directly against the soil. There are several methods of constructing uncased piles and cased piles. In one method of casting a cased pile, a core is driven with the casing. After the core is withdrawn, the casing is filled with concrete. The casing may be a thin metal shell. In some methods the shell may be closed at the lower end with a flat or cone-shaped boot.
Uncased piles may be formed by a temporary casing which is pulled out after concrete is placed. They may be also established by drilling holes in the ground and and casting concrete in the holes.
It is known that cast-in-place concrete piles may be formed with enlarged bases to reduce the intensity of the load transferred to the bearing strata. Many methods are available for such pile constructions. In one method a shell which is initially partly filled with concrete is driven by an internal core, the shell is raised and the core is forced downward to force the concrete out for forming an enlarged base. Therea~ter, the casing is filled with concrete and then pulled out. However, the methods utili~ed heretofore are found defficient as it is difficult to achieve a desired extent of enlargement in base formation. In addition, the conventional cased piles usually develop reduced skin friction as there are gaps around the formed piles which are resulted while driving the shells.
An object of the invention is to provide a method of constructing a cast-in-place concrete pile with improved end bearing power and skin friction.
Another object of the invention is to provide a method which improves the constructions of a cast-in-place concrete pile to a form with a iarger base formation and an effective surface area in tight abutment with the surrounding soil.
The foregoing and other objects can be achieved in accordance with the invention through the provision of a method of constructing a cast-in-place concrete pile which comprises: (a) driving a shell which is closed temporarily at its lower end with a boots to a certain depth in the ground; (b) forcing the boot of the shell by hammering a core -to separate it from the lower end of the shell and to extend it to a further depth, thereby causing a hollow between the end of the shell and the --`. i23~69l3 boot; (c) removing the core from the shell; (d) enlarging the width of the hollow by soil excavation; and (e) placing concrete into the enlarged hollow and the shell.
According to the invention, the method may further includes step (d) preparing a rotary shaft with collapsible blades and lowering said shaft until it reaches the hollow. The collapsible blades may be made of steel chains.
According to the invention, the method m~y further comprises the steps: placing a central tube passing through the shell and extending beyond the bottom side of the enlarged hollow prior to step (e) and forcing a further charge of concrete through said tube after step (e) to cause the concrete to penetrate into the soil surrounding the enlarged base formed and the gap around the shell.
In one aspect of the invention, the method comprises:
ta) driving a core with a shell into the ground; (b) removing the core from the shell; (c) placing a central tube passing through the shell and extending it to the end of the shell; (d) placing concrete into the shell through the annular space around the central tube; (e) allowing the concrete to set; and tf) forcing a further charge of concrete through the central tube to cause it to penettate into the soil and the gap surrounding the shell.
The presently preferred exemplary embodiment will be described in detail with reference to the following ~23'~698 drawings, wherein:
Fig. 1 illustrates the shell and core which is placed in the ground;
Fig. 2 illustrates the driving of the boot to separate it from the shell;
Fig. 3 illustrates a rotary shaft with collapsible blades placed in the hollow;
Figs. 4 and 5 illustrates the operation of the shaft for enlargement of the hollow;
Fig. 6 shows a collapsible reinforcement frame placed in the shell and the hollow;
Fig. 7 illustrates that the shell and the hollow is provided with a pressurizing tube;
Fig. 8 is a view after the shell and the hollow are L il led with,concrete;
Fig. 9 is a view after -the soil stabilizing agent is introduced through the pressurizing tube; and Fig. 10 is a view after the pile construction is complete.
"
Referring to Fig. 1, a shell 10 which is in this embodiment pre~rably a precast concrete pile is provided with a cone shaped boot 11 at its lower end. The shell 10 is driven into the ground. When it reaches a certain depth, the cone shaped boot 11 is forced by hammering a core lOa tO
be separated from the lower end oE the shell.
~ 23~6~D~
~lammering is continued until the boot 11 extends into a Eurther depth of about lm to 2 m, thereby resulting a hollow 12 between the lower end of the shell and the boot 11, as shown in Fig. 2.
The hollow 12 is further enlarged by soil excavation. It is requird a rotary shaft with collapsible blades which can be passed through the shell 10 and then stretched out at beyond the end of the shell.
Preferably, steel chains are used as blades in this embodiment. A rotary shaft 13 which is incorporated with steel chains 15 is lowered into the hollow 12 through the shell 10 and then rotated by a driving means, such as motor. The lengths of the chains 15 may be chosen according to how much extent of the base is desired.
The shaft 13 is extended to a depth above the boot as shown in.Fig. 3.
As the shaft 13 is rotated, the steel chains 15 are spinning and beating the soil as shown in Fig. 4. For ef~ective beating of the soil, the shaft may be rotated in clockwise and counter-clockwise directions alternatively. Water is jetted into the hollow 12 and the soil is churned into slurry which is then bailed out by a known manner. Large size stones and the like which can not be suspended in the slurry are beaten down by the chains 15 into the contracted space above the boot 11 as shown in Fig. 5. As the soil is excavated, the hollow 12 is enlarged. The enlarged hollow 12 may have a size or radius substantially similar to the length of a steel ` ~3~6~8 chain 15. The volume of the enlarged hollow 12 can be determined by a supersonic detector.
To keep the rotary shaft 13 in a coaxial relationship with the shell 10, retaining members 17 which can be made of elastic material,such as rubber are provided between the rotary shaft 13 and the shell 10.
For reinforcing purpose, a steel frame 14 which is preferably collapsible is placed in the enlarged hollow 12 and the shell 10 prior to casting concrete, as shown in Fig. 7.
There is further inserted a pressurizing tube 16 which is extended into the hollow 12 through the shell 10 prior to casting concrete. The tube 16 is advantageously extended to a region below the enlarged portions of the hollow 12 which will be filled with concrete as shown in Figs. 8 and 9, so that the open end of the tube will not be embedded in the concrete.
A charge of concrete is poured into the hollw 12 through the annular space around the tube 16. To avoid ~L~clc~ ~6 the ~ at the end of the tube 16, the tube is supplied with a flow of water during operation. After the shell 10 and the enlarged hollow 12 are filled with concrete as shown in Fig. 8, the concret~ is allowed to set for 4-5 hours.
Then a soil stabilizing agent is supplied into the tube 15 and then forced to penetrate into the soil surrounding the enlarged concrete base 18 as shown in ~23469~
Fig. 9. Subsequent supplying of the soil s-tabilizing agent causes the agent to rise through the region surrounding the enlarged base 18 to the region around the shell 10, thereby improving the soil density and stability around the shell 10 and the enlarged base 18.
Thereafter, a further charge of concrete is forced through the tube 16 and penetrated into the soil surrounding the enlarged base 18, thereby increasing the size of the base 18 as well as its-skin friction. As the concrete is supplied through a high pressure, it is then penetrated into the gap around the shell 10 from the base as illustrated in Fig. 10. When the concrete sets, an improved skin friction is developed around the shell 10.
This step is important for improving the skin friction of the pile. The construction of a pile is complete at this stage.
It can be appreciated that the method according to the invention offers an improved pile construction - with an effective enlarged base which increases the end bearing power of the pile and with an effective surface area adhering to the surrounding soil which improves the skin friction.
With the invention thus explained, it is apparent that obvious modifications and variations can be made without departing from the scope of the invention. It is therefore intended that the invention be limited only as indicated in the appended claims.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of constructing a cast-in-place concrete pile comprising: (a) driving a shell which is closed temporarily at its lower end with a boot to a certain depth in the ground;
(b) forcing the boot of the shell by hammering a core to separate it from the lower end of the shell and to drive it to a further depth, thereby causing a hollow between the end of the shell and the boot; (c) removing the core from the shell; (d) enlarging the width of the hollow by soil excavation; (e) lowering a tube in the shell until the tube extends to the bottom of the enlarged hollow; (f) filling the enlarged hollow and the shell with a cement; and (g) injecting a cement material through said tube to the surrounding of the filled enlarged hollow.
(b) forcing the boot of the shell by hammering a core to separate it from the lower end of the shell and to drive it to a further depth, thereby causing a hollow between the end of the shell and the boot; (c) removing the core from the shell; (d) enlarging the width of the hollow by soil excavation; (e) lowering a tube in the shell until the tube extends to the bottom of the enlarged hollow; (f) filling the enlarged hollow and the shell with a cement; and (g) injecting a cement material through said tube to the surrounding of the filled enlarged hollow.
2. A method as claimed in claim 1, wherein the step (d) includes beating the soil with a rotary shaft having col-lapsible blades.
3. A method as claimed in claim 2, wherein said col-lapsible blades are made of steel chains.
4. A method as claimed in claim 1, further comprising the step (h) placing a reinforcement collapsible steel frame in the shell and the hollow before the step (f).
5. A method as claimed in claim 1, further comprising the step (h) introducing a soil stabilizing agent through the tube after step (g).
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08410308A GB2157750B (en) | 1984-04-19 | 1984-04-19 | Improvements relating to cast-in-situ concrete pile construction |
| GB8410308 | 1984-04-19 | ||
| US60259584A | 1984-04-20 | 1984-04-20 | |
| US602,595 | 1984-04-20 | ||
| JP10345584A JPS60250121A (en) | 1984-05-22 | 1984-05-22 | Base stake inflated in bump state at lower end thereof and its construction |
| JP59-103455 | 1984-05-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1234698A true CA1234698A (en) | 1988-04-05 |
Family
ID=27262337
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000471534A Expired CA1234698A (en) | 1984-04-19 | 1985-01-04 | Cast-in-place concrete pile construction |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1234698A (en) |
-
1985
- 1985-01-04 CA CA000471534A patent/CA1234698A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |