CN214883616U - Connecting piece for lengthening steel casing of rotary excavating cast-in-place pile - Google Patents

Abstract

The utility model provides a connecting piece that is used for digging bored concrete pile steel soon and protects a section of thick bamboo and connect length belongs to engineering machine tool technical field. This a connecting piece for digging bored concrete pile steel soon and protecting a section of thick bamboo and prolong, including the upper portion steel protects a section of thick bamboo, the adapter sleeve, lower part steel protects a section of thick bamboo and high-strength bolt, protect a section of thick bamboo through adapter sleeve and the steel of upper and lower part and connect, the connection technology of steel protecting a section of thick bamboo has greatly been simplified, the operating time has been shortened, it protects a strict collineation to guarantee upper and lower part steel, whole protect a section of thick bamboo stack body straightness that hangs down has effectively been ensured, high strength bolt shear strength is high, the security of protecting a section of thick bamboo extraction process has been ensured, the connection process who protects a section of thick bamboo is short, and the upper portion steel protects a section of thick bamboo and can carry out preliminary fixation fast, the potential safety hazard that the time of lifting by crane caused has been avoided, the turnover number of times of steel protecting a section of thick bamboo has been increased simultaneously, avoid frequent welding, the damage of fusing operation to a section of thick bamboo stack body is protected to steel.

Description

Connecting piece for lengthening steel casing of rotary excavating cast-in-place pile

Technical Field

The utility model relates to an engineering machine tool technical field particularly, relates to a connecting piece that is used for digging bored concrete pile steel soon and protects a section of thick bamboo and connect length.

Background

During the construction process of the rotary excavating cast-in-place pile by utilizing the all-steel casing wall protecting process, overlarge thickness of geological layers above rock strata or other complex geological conditions are often met, so that the length of a single section of steel casing is insufficient, and the single section of steel casing cannot contact the soil-rock boundary. The condition that the ultra-long protective barrel needs to be pressed and pulled cannot be handled due to the limited operation height of the striking and pulling hammer for pressing the steel protective barrel. Therefore, in the traditional process, a section of steel casing is pressed into the soil, and then a second section of steel casing is lifted up to be welded with a first section of steel casing by using a connecting plate for strip welding, and the method has the following defects:

1. the total verticality of the upper and lower protective cylinders is difficult to guarantee;

2. the upper section of the protecting cylinder is hung in the air, so that the welding quality and the interface tightness are difficult to ensure, and the protecting cylinder cannot be pulled out due to falling off easily in the pulling process;

3. safety accidents are easily caused by long duration of hoisting and welding processes;

4. in the process of pulling out, the welding position of the connecting plate needs to be fused, the process is complicated, and the loss of the steel casing is large;

5. the lower section of thick bamboo that protects in the welding process is in the underground, if geology is special can appear the lower section of thick bamboo that protects because self weight moves down, causes danger such as hole collapse, appears serious safety problem.

Therefore, the connection piece for lengthening the steel casing of the rotary excavating cast-in-place pile is improved.

SUMMERY OF THE UTILITY MODEL

In order to make up the defects, the utility model provides a connecting piece for lengthening a steel casing of a rotary excavating cast-in-place pile, when in use, after the lower steel casing is pressed to a proper position, the lower steel casing and a connecting sleeve are connected firstly, the connecting sleeve is sleeved at the top end of the lower steel casing and rotated to a proper position, a lower fixing pin in the connecting sleeve is embedded into a lower fixing groove in the lower steel casing, the connecting sleeve and the lower steel casing are preliminarily fixed, then a high-strength bolt penetrates through a lower preformed hole in the lower steel casing and a sleeve preformed hole in the connecting sleeve, the high-strength bolt is connected with a high-strength nut welded in advance, the connecting sleeve and the lower steel casing are fixed again, the upper steel casing is lifted, an upper fixing groove in the upper steel casing is embedded into the connecting sleeve, the perpendicularity of the upper steel casing and the lower steel casing is ensured, the upper steel casing is rotated, the upper fixing pin is clamped in the upper fixing groove, the upper steel casing is initially fixed, then the high-strength bolt penetrates through an upper preformed hole in the upper steel casing and a sleeve body preformed hole in the connecting sleeve to be connected with a high-strength nut welded in advance, the upper steel casing and the connecting sleeve are fixed again, the length of a single section of the steel casing and the required number of sections required by specific working conditions are combined, the friction force of soil on the side of the casing and the dead weight of the lower steel casing are comprehensively considered, the shearing force borne by the high-strength bolt, the connecting sleeve and the steel casing is calculated, the number of the required connecting sleeves is finally determined, after the fixing is completed, the perpendicularity of the upper and lower two sections of casings is determined, the steel casing can be normally used, the casing is pulled out after the use is completed, the connecting sleeve is detached, and the subsequent use is performed.

The utility model discloses a realize like this:

the connecting piece for lengthening the steel casing of the rotary excavating cast-in-place pile comprises an upper steel casing, a connecting sleeve, a lower steel casing and a high-strength bolt.

The bottom end of the upper steel casing is provided with a connecting sleeve, and the lower end of the connecting sleeve is provided with a lower steel casing;

the connecting sleeve is composed of an inner sleeve, an outer sleeve and a transverse plate, the central shaft of the inner sleeve and the central shaft of the outer sleeve are positioned on the same straight line, the center of the inner sleeve and the center of the outer sleeve are fixedly connected through the transverse plate, the top ends of the inner wall of the inner sleeve and the outer wall of the outer sleeve are both provided with top wedge-shaped tip ends, the bottom ends of the outer sleeve and the inner wall of the inner sleeve are both provided with bottom wedge-shaped tip ends, the upper side and the lower side of the two sides of the transverse plate are respectively provided with an upper fixing pin and a lower fixing pin, the number of the upper fixing pin and the lower fixing pin are two, the two ends of the two upper fixing pins respectively extend to the outer part of the outer sleeve and the inner part of the inner sleeve, the two ends of the two lower fixing pins respectively extend to the outer part of the outer sleeve and the inner part of the inner sleeve, and the central shafts of the upper fixing pin and the lower fixing pin are both perpendicular to the central shaft of the inner sleeve, the sleeve body preformed holes are formed in the surfaces of the outer sleeve and the inner sleeve and correspond to the sleeve body preformed holes formed in the surface of the inner sleeve one to one, and high-strength nuts are arranged at the sleeve body preformed holes in the inner wall of the inner sleeve.

The utility model discloses an in the embodiment, the upper portion fixed slot has been seted up on the bottom both sides face of an upper portion steel casing, the shape of upper portion fixed slot is seven fonts, just the quantity of upper portion fixed slot is two, and with the center pin that an upper portion steel casing is symmetrical distribution for the center of symmetry in the bottom both sides surface of an upper portion steel casing, the upper portion steel casing has seted up the upper portion preformed hole on being close to the bottom on the surface, just the quantity of upper portion preformed hole is four.

The utility model discloses an in the embodiment, the lower part fixed slot has been seted up on the top both sides face of lower part steel casing, the shape of lower part fixed slot is seven fonts, just the quantity of lower part fixed slot is two, and with the center pin that the lower part steel protected a section of thick bamboo is symmetric distribution in for the center of symmetry the top both sides surface of a lower part steel casing, the lower part steel protects a section of thick bamboo and has seted up the lower part preformed hole on being close to the top on the surface, just the quantity of lower part preformed hole is four.

In an embodiment of the present invention, an opening diameter of the upper fixing groove is larger than two diameters of the upper fixing pin.

In an embodiment of the present invention, an opening diameter of the lower fixing groove is larger than two diameters of the lower fixing pin.

In an embodiment of the present invention, the high-strength nut is fixedly welded to the inner wall of the inner sleeve at the reserved hole of the sleeve body.

The utility model discloses an in the embodiment, upper portion preformed hole can with the diaphragm top cover body preformed hole one-to-one, upper portion preformed hole with the inside of the cover body preformed hole is equipped with high strength bolt, high strength bolt's one end with high strength nut passes through threaded connection, high strength bolt's the other end with be equipped with the high strength gasket between the overcoat.

The utility model discloses an in the embodiment, lower part preformed hole, can with the diaphragm below the cover body preformed hole one-to-one, the lower part preformed hole with the inside of the cover body preformed hole is equipped with high strength bolt, high strength bolt's one end with high strength nut passes through threaded connection, high strength bolt's the other end with be equipped with the high strength gasket between the overcoat.

The utility model has the advantages that: the utility model greatly simplifies the connecting process of the steel casing, shortens the operation time, ensures the axes of the upper and lower steel casings to be strictly collinear, and effectively ensures the verticality of the whole casing body; the high-strength bolt is high in shear strength, the safety of the protective cylinder extracting process is guaranteed, the connecting process of the protective cylinder is short, the upper steel protective cylinder can be rapidly and preliminarily fixed, the potential safety hazard caused by overlong lifting time is avoided, the turnover times of the steel protective cylinder are increased simultaneously, and the damage to the steel protective cylinder body caused by frequent welding and fusing operations is avoided.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a schematic perspective view of a connecting piece for lengthening a steel casing of a rotary excavating cast-in-place pile according to an embodiment of the present invention;

fig. 2 is a schematic view of a front cross-sectional structure of a connecting sleeve provided by an embodiment of the present invention;

fig. 3 is a schematic cross-sectional structure view of a connecting sleeve according to an embodiment of the present invention;

fig. 4 is a schematic perspective view of an upper steel casing and a lower steel casing according to an embodiment of the present invention.

In the figure: 1. an upper steel casing; 1001. an upper fixing groove; 1002. an upper preformed hole; 2. connecting sleeves; 2001. an inner sleeve; 2002. a jacket; 2003. a transverse plate; 2004. an upper fixing pin; 2005. a lower fixing pin; 2006. a high-strength nut; 2007. a preformed hole is reserved in the sleeve body; 3. a lower steel casing; 3001. a lower fixing groove; 3002. a lower preformed hole; 4. high-strength bolt.

Detailed Description

To make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the drawings of the embodiments of the present invention are combined to clearly and completely describe the technical solutions of the embodiments of the present invention, and obviously, the described embodiments are some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Examples

Referring to fig. 1-4, the present invention provides a technical solution: the connecting piece for lengthening the steel casing of the rotary excavating cast-in-place pile comprises an upper steel casing 1, a connecting sleeve 2, a lower steel casing 3 and a high-strength bolt 4.

Referring to fig. 1-4, in use, after the lower steel casing 3 is pressed down to a proper position, the lower steel casing 3 and the connecting sleeve 2 are connected, the connecting sleeve 2 is sleeved on the top end of the lower steel casing 3, and rotated to a proper position, the lower fixing pin 2005 in the connecting sleeve 2 is embedded into the lower fixing groove 3001 in the lower steel casing 3, so that the connecting sleeve 2 and the lower steel casing 3 are primarily fixed, then the high-strength bolt 4 penetrates through the lower preformed hole 3002 in the lower steel casing 3 and the preformed hole 2007 in the connecting sleeve 2, so that the high-strength bolt 4 is connected with the high-strength nut 2006 welded in advance, the connecting sleeve 2 and the lower steel casing 3 are fixed again, the upper steel casing 1 is lifted, the upper fixing groove 1001 in the upper steel casing 1 is embedded into the connecting sleeve 2, the perpendicularity between the upper steel casing 1 and the lower steel casing 3 is ensured, the upper steel casing 1 is rotated, so that the upper fixing pin 2004 is engaged with the upper fixing groove 1001, the method comprises the steps of initially fixing an upper steel casing 1, enabling the upper steel casing 1 to penetrate through an upper reserved hole 1002 in the upper steel casing 1 and a sleeve body reserved hole 2007 in a connecting sleeve 2 through a high-strength bolt 4 to be connected with a high-strength nut 2006 welded in advance, enabling the upper steel casing 1 and the connecting sleeve 2 to be fixed again, combining the length of a single section of the steel casing and the required number of sections of the steel casing required by specific working conditions, comprehensively considering the friction force of soil on the side of the casing and the dead weight of a lower steel casing 3, calculating the shearing force borne by the high-strength bolt 4, the connecting sleeve 2 and the steel casing, finally determining the number of the required connecting sleeve 2, after fixing is completed, determining the verticality of the upper casing and the lower casing, normally using the upper casing and the lower casing, pulling out the casing after using is completed, dismantling the connecting sleeve 2, and waiting for subsequent use.

Specifically, referring to fig. 1-4, a connecting sleeve 2 is arranged at the bottom end of an upper steel casing 1, and a lower steel casing 3 is arranged at the lower end of the connecting sleeve 2;

the connecting sleeve 2 is composed of an inner sleeve 2001, an outer sleeve 2002 and a transverse plate 2003, the central axis of the inner sleeve 2001 and the central axis of the outer sleeve 2002 are positioned on the same straight line, the center of the inner sleeve 2001 and the center of the outer sleeve 2002 are fixedly connected through the transverse plate 2003, the top end of the inner wall of the inner sleeve 2001 and the top end of the outer wall of the outer sleeve 2002 are respectively provided with a top end wedge-shaped tip, the bottom end of the outer wall of the outer sleeve 2002 and the bottom end of the inner wall of the inner sleeve 2001 are respectively provided with a bottom end wedge-shaped tip, an upper fixing pin 2004 and a lower fixing pin 2005 are respectively arranged above and below two sides of the transverse plate 2003, the number of the upper fixing pin 2004 and the lower fixing pin 2005 is two, two ends of the two upper fixing pins 2004 respectively extend to the outside of the outer sleeve 2002 and the inside of the inner sleeve 2001, the central axis of the upper fixing pin 2004 and the central axis of the lower fixing pin 2005 are respectively perpendicular to the central axis of the inner sleeve 2001, the surfaces of the outer sleeve 2002 and the inner sleeve 2001 are both provided with sleeve body preformed holes 2007, the sleeve body preformed holes 2007 formed in the surface of the outer sleeve 2002 and the sleeve body preformed holes 2007 formed in the surface of the inner sleeve 2001 are in one-to-one correspondence, and the inner wall of the inner sleeve 2001 is provided with a high-strength nut 2006 at the sleeve body preformed holes 2007.

Preferably, referring to fig. 1 to 4, two side surfaces of the bottom end of the upper steel casing 1 are provided with upper fixing grooves 1001, the upper fixing grooves 1001 are in a seven-letter shape, the number of the upper fixing grooves 1001 is two, and the two fixing grooves are symmetrically distributed on the two side surfaces of the bottom end of the upper steel casing 1 by taking the central axis of the upper steel casing 1 as a symmetric center, the upper steel casing 1 is provided with upper preformed holes 1002 on the surface close to the bottom end, the number of the upper preformed holes 1002 is four, the upper fixing grooves 1001 in the upper steel casing 1 are embedded into the connecting sleeve 2, so that the verticality between the upper steel casing 1 and the lower steel casing 3 is ensured, and the upper steel casing 1 is rotated to engage the upper fixing pins 2004 in the upper fixing grooves 1001, so that the upper steel casing 1 is primarily fixed.

Preferably, referring to fig. 1 to 4, two side surfaces of the top end of the lower steel casing 3 are provided with lower fixing grooves 3001, the lower fixing grooves 3001 are in a seven-shaped shape, the number of the lower fixing grooves 3001 is two, and the two fixing grooves are symmetrically distributed on two side surfaces of the top end of the lower steel casing 3 by taking the central axis of the lower steel casing 3 as a symmetry center, the lower steel casing 3 is provided with lower preformed holes 3002 on a surface close to the top end, the number of the lower preformed holes 3002 is four, the connecting sleeve 2 is sleeved into the top end of the lower steel casing 3, and the lower preformed holes 3002 are rotated to a proper position, so that the lower fixing pins 2005 in the connecting sleeve 2 are embedded into the lower fixing grooves 3001 in the lower steel casing 3, and the connecting sleeve 2 and the lower steel casing 3 are primarily fixed.

Preferably, referring to fig. 1 to 4, the opening diameter of the upper fixing groove 1001 is greater than the diameters of the two upper fixing pins 2004, so that the upper fixing pins 2004 can be inserted into the upper fixing groove 1001, the connecting sleeve 2 and the upper steel casing 1 can be initially fixed, the perpendicularity between the upper steel casing and the connecting sleeve 2 is ensured, and the hoisting time of the upper steel casing 1 is reduced.

Preferably, referring to fig. 1 to 4, the aperture of the lower fixing groove 3001 is larger than the diameters of the two lower fixing pins 2005, so that the lower fixing pins 2005 can be conveniently inserted into the lower fixing groove, the connecting sleeve 2 and the lower steel casing 3 can be initially fixed, the perpendicularity between the lower steel casing 3 and the connecting sleeve 2 can be ensured, and the labor intensity of operators can be reduced.

Preferably, referring to fig. 1-4, the high-strength nut 2006 is fixedly welded to a preformed hole 2007 formed in the inner wall of the inner sleeve 2001.

Preferably, referring to fig. 1 to 4, the upper preformed hole 1002 may correspond to the sleeve preformed hole 2007 above the transverse plate 2003, a high-strength bolt 4 is disposed inside the upper preformed hole 1002 and the sleeve preformed hole 2007, one end of the high-strength bolt 4 is connected to the high-strength nut 2006 through a thread, and a high-strength gasket is disposed between the other end of the high-strength bolt 4 and the outer sleeve 2002.

Preferably, referring to fig. 1-4, the lower preformed hole 3002 corresponds to the sleeve preformed hole 2007 below the transverse plate 2003, the high-strength bolt 4 is arranged inside the lower preformed hole 3002 and the sleeve preformed hole 2007, one end of the high-strength bolt 4 is connected with the high-strength nut 2006 through a thread, the high-strength gasket is arranged between the other end of the high-strength bolt 4 and the outer sleeve 2002, the high-strength bolt 4 is high in shear strength and high in strength, the safety of the steel casing in the process of pulling out is guaranteed, and the cost increase caused by the fact that the steel casing is broken in the process of pulling out is avoided.

Specifically, the working principle of the connecting piece for lengthening the steel casing of the rotary excavating cast-in-place pile is as follows: when in use, after the lower steel casing 3 is pressed down to a proper position, the lower steel casing 3 and the connecting sleeve 2 are connected, the connecting sleeve 2 is sleeved at the top end of the lower steel casing 3 and rotated to a proper position, the lower fixing pin 2005 in the connecting sleeve 2 is embedded into the lower fixing groove 3001 in the lower steel casing 3, the connecting sleeve 2 and the lower steel casing 3 are preliminarily fixed, the high-strength bolt 4 penetrates through the lower preformed hole 3002 in the lower steel casing 3 and the sleeve preformed hole 2007 in the connecting sleeve 2, the high-strength bolt 4 is connected with the high-strength nut 2006 welded in advance, the connecting sleeve 2 and the lower steel casing 3 are fixed again, the upper steel casing 1 is lifted, the upper fixing groove 1001 in the upper steel casing 1 is embedded into the connecting sleeve 2, the verticality between the upper steel casing 1 and the lower steel casing 3 is ensured, the upper steel casing 1 is rotated, the upper fixing pin 2004 is clamped in the upper fixing groove 1001, the method comprises the steps of initially fixing an upper steel casing 1, enabling the upper steel casing 1 to penetrate through an upper reserved hole 1002 in the upper steel casing 1 and a sleeve body reserved hole 2007 in a connecting sleeve 2 through a high-strength bolt 4 to be connected with a high-strength nut 2006 welded in advance, enabling the upper steel casing 1 and the connecting sleeve 2 to be fixed again, combining the length of a single section of the steel casing and the required number of sections of the steel casing required by specific working conditions, comprehensively considering the friction force of soil on the side of the casing and the dead weight of a lower steel casing 3, calculating the shearing force borne by the high-strength bolt 4, the connecting sleeve 2 and the steel casing, finally determining the number of the required connecting sleeve 2, after fixing is completed, determining the verticality of the upper casing and the lower casing, normally using the upper casing and the lower casing, pulling out the casing after using is completed, dismantling the connecting sleeve 2, and waiting for subsequent use.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. The connecting piece for lengthening the steel casing of the rotary excavating cast-in-place pile is characterized by comprising an upper steel casing (1), a connecting sleeve (2), a lower steel casing (3) and a high-strength bolt (4);

a connecting sleeve (2) is arranged at the bottom end of the upper steel casing (1), and a lower steel casing (3) is arranged at the lower end of the connecting sleeve (2);

the connecting sleeve (2) consists of an inner sleeve (2001), an outer sleeve (2002) and a transverse plate (2003), the central axis of the inner sleeve (2001) and the central axis of the outer sleeve (2002) are positioned on the same straight line, the center of the inner sleeve (2001) and the center of the outer sleeve (2002) are fixedly connected through the transverse plate (2003), the top end of the inner wall of the inner sleeve (2001) and the top end of the outer wall of the outer sleeve (2002) are both provided with top end wedge-shaped tips, the bottom end of the outer wall of the outer sleeve (2002) and the bottom end of the inner wall of the inner sleeve (2001) are both provided with bottom end wedge-shaped tips, an upper fixing pin (2004) and a lower fixing pin (2005) are respectively arranged above and below two sides of the transverse plate (2003), the number of the upper fixing pins (2004) and the lower fixing pins (2005) is two, and two ends of the two upper fixing pins (2004) respectively extend to the outside of the outer sleeve (2002) and the inside of the inner sleeve (2001), the two ends of the two lower fixing pins (2005) extend to the outside of the outer sleeve (2002) and the inside of the inner sleeve (2001) respectively, the central axis of the upper fixing pin (2004) and the central axis of the lower fixing pin (2005) are perpendicular to the central axis of the inner sleeve (2001), sleeve body preformed holes (2007) are formed in the surfaces of the outer sleeve (2002) and the inner sleeve (2001), the sleeve body preformed holes (2007) formed in the surface of the outer sleeve (2002) correspond to the sleeve body preformed holes (2007) formed in the surface of the inner sleeve (2001) one by one, and high-strength nuts (2006) are arranged on the inner wall of the inner sleeve (2001) at the positions of the sleeve body preformed holes (2007).

2. The connecting piece for lengthening the steel casing of the rotary excavating cast-in-place pile according to claim 1, wherein two sides of the bottom end of the upper steel casing (1) are provided with upper fixing grooves (1001), the upper fixing grooves (1001) are in a seven-letter shape, the upper fixing grooves (1001) are two and symmetrically distributed on the surfaces of two sides of the bottom end of the upper steel casing (1) by taking the central axis of the upper steel casing (1) as a symmetric center, the upper steel casing (1) is provided with upper preformed holes (1002) on the surface close to the bottom end, and the upper preformed holes (1002) are four in number.

3. The connecting piece for lengthening the steel casing of the rotary excavating cast-in-place pile according to claim 1, wherein two sides of the top end of the lower steel casing (3) are provided with lower fixing grooves (3001), the lower fixing grooves (3001) are in a seven-letter shape, the number of the lower fixing grooves (3001) is two, the lower fixing grooves are symmetrically distributed on the surfaces of two sides of the top end of the lower steel casing (3) by taking the central axis of the lower steel casing (3) as a symmetric center, the lower steel casing (3) is provided with lower preformed holes (3002) on the surface close to the top end, and the number of the lower preformed holes (3002) is four.

4. The connection piece for the rotary excavating bored concrete pile steel casing lengthening according to claim 2, wherein an opening caliber of the upper fixing groove (1001) is larger than diameters of the two upper fixing pins (2004).

5. The connecting piece for rotary excavating cast-in-place pile steel casing lengthening according to claim 3, characterized in that the opening caliber of the lower fixing groove (3001) is larger than the diameter of the two lower fixing pins (2005).

6. The connecting piece for lengthening the steel casing of the rotary excavating cast-in-place pile according to claim 1, wherein the high-strength nut (2006) is fixedly welded to the preformed hole (2007) of the sleeve body formed in the inner wall of the inner sleeve (2001).

7. The connecting piece for lengthening the steel casing of the rotary excavating cast-in-place pile according to claim 2, wherein the upper preformed hole (1002) can correspond to the sleeve body preformed hole (2007) above the transverse plate (2003) in a one-to-one manner, high-strength bolts (4) are arranged inside the upper preformed hole (1002) and the sleeve body preformed hole (2007), one end of each high-strength bolt (4) is connected with the high-strength nut (2006) through threads, and a high-strength gasket is arranged between the other end of each high-strength bolt (4) and the outer sleeve (2002).

8. The connecting piece for lengthening the steel casing of the rotary excavating cast-in-place pile according to claim 3, wherein the lower preformed hole (3002) can correspond to the sleeve preformed hole (2007) below the transverse plate (2003) in a one-to-one manner, high-strength bolts (4) are arranged inside the lower preformed hole (3002) and the sleeve preformed hole (2007), one end of each high-strength bolt (4) is connected with the high-strength nut (2006) through threads, and a high-strength gasket is arranged between the other end of each high-strength bolt (4) and the outer sleeve (2002).

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