CN213741036U - Prestressed pile with multiple main ribs - Google Patents

Abstract

A multi-main-rib prestressed pile is characterized in that a composite prestressed pile or a pressure-bearing pile with a steel reinforcement cage as a framework grouting or concrete pouring as a pile body is arranged in a drill hole; the main reinforcements of the reinforcement cage framework and the pile body of the prestressed pile are pre-tensioned or post-tensioned prestressed reinforcements. The front end of the main reinforcing steel bar is provided with a device for connecting or grafting and riveting with the diameter-variable reinforcing steel bar cage, the fixed diameter reinforcing steel bar cage, the bearing plate, the expanding head of the bag or the sleeving bag or the anchor head of other supporting bodies to form a prestressed pile framework system with an expanding head or a non-expanding head.

Description

Prestressed pile with multiple main ribs

Technical Field

The utility model relates to an anti-floating or bearing pile (including prestressed pile), especially prestressed pile of many owner muscle.

Background

The foundation of soft soil layer includes but not limited to the foundation treatment in the soil layer of silt, mucky soil, flow plastic, soft plastic or plastic cohesive soil, plain filling soil, silt, sandy soil, gravel soil and the like, and particularly the hole forming of anchor rods or pile foundations in the soft soil layer is a big problem in basic construction.

The mixing pile is also an existing pile and has a ready-made construction method; the deep mixing pile is usually called mixing pile, also called deep cement mixing pile, and is suitable for treating soil layers of normally consolidated silt, mucky soil, plain filling soil, silt, cohesive soil, loose sandy soil without flowing underground water and the like. The reinforcement depth is generally greater than 5.0 m; the construction method can be classified into two types, namely, a slurry stirring method (wet method, i.e., the present fine and deep cement slurry stirring method) and a powder stirring method (dry method), depending on the state of the reinforcing material used. According to the site engineering geological condition, the upper structure load requirement and the stress state of the cement-soil pile, a cement-soil reinforcement body formed by the deep mixing pile can be used as a retaining wall and an anti-seepage curtain for foundation pit engineering; a vertically loaded composite foundation; bulk cement stabilized soil, and the like.

The deep mixing pile is used to stir the stratum by mechanical rotation, and at the same time, cement slurry is poured or cement dry powder is sprayed, and the cement slurry and soil are fully mixed to form the pile body. The shape of the deep stirring strengthening body can be divided into column, wall, grid, block and the like. Wherein, the columnar reinforcement body is mostly used for the composite foundation for soft soil reinforcement; the wall-shaped and grid-shaped reinforcing body is mainly used as a retaining wall and an impervious curtain for the excavation of the deep foundation pit; the massive reinforcing body is mainly used for a structure foundation with a large unit area load of an upper structure and strict uneven settlement control. However, no matter which form of the reinforcing body, the construction of the deep mixing pile has the characteristics of high pile forming speed, high efficiency, low cost, no vibration, no noise, no pollution and the like.

The two piles belong to a method and a process for treating a foundation, and the method also comprises a powder spray method: a cement-soil mixing method using dry cement as a curing agent. Dry method for short. Deep stirring method: a cement-soil stirring method using cement slurry as a curing agent. Referred to as wet process for short. Cement soil 25785stirring: the cement is used as main agent of solidifying agent, and the solidifying agent and foundation soil are forcedly stirred by means of special deep-layer stirring machine so as to make the soft soil be hardened into pile body with integrity, water stability and certain strength. The prior art may not be generally applied to pressure-bearing piles and tensile prestressed piles and preparation thereof.

The soft soil layer foundation and the two piles can adopt the prestressed pile with multiple main ribs for pile foundations and anchor rods, in particular to the prestressed pile with the multiple main ribs with large diameter.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a multi-main-rib prestressed pile, wherein a steel reinforcement cage is arranged in a drill hole and is a composite prestressed pile or a bearing pile with a framework grouting or cast concrete as a pile body; the main reinforcements of the reinforcement cage framework and the pile body of the prestressed pile are pre-tensioned or post-tensioned prestressed reinforcements. In particular to a soft soil layer foundation, a prestressed pile for reinforcing the foundation by a rotary spraying powder spraying or stirring pile, and a prestressed pile with a plurality of major diameter main bars.

The technical scheme of the utility model is that the prestressed pile with a plurality of main bars is characterized in that a steel reinforcement cage is arranged in a drill hole and is a composite prestressed pile or a bearing pile with a framework grouting or cast concrete as a pile body; the main reinforcements of the reinforcement cage framework and the pile body of the prestressed pile are pre-tensioned or post-tensioned prestressed reinforcements.

The front end of the main reinforcing steel bar is provided with a device for connecting or grafting and riveting with the diameter-variable reinforcing steel bar cage, the fixed diameter reinforcing steel bar cage, the bearing plate, the expanding head of the bag or the sleeving bag or the anchor head of other supporting bodies to form a prestressed pile framework system with an expanding head or a non-expanding head.

The reinforcement cage framework can be formed by adding a bearing plate on the bottom of the reinforcement cage framework together with a common prestressed pile, the reinforcement cage framework and the main reinforcement of the pile body of the prestressed pile are bonded, are non-bonded and are prestressed, and the reinforcement cage framework can also be provided with bonded or partially bonded reinforcement according to the engineering design requirement.

The pile is provided with more than 1 and less than 150 unbonded (or bonded) prestressed reinforcements serving as a framework of the pile, the pile is of a cast-in-place pile structure, the bottom of each reinforcement is provided with a backing plate or a bottom anchor, each backing plate is a large-diameter steel plate, holes are uniformly formed in each steel plate, and each hole is internally provided with one prestressed reinforcement; the backing plate or the bottom-added anchor is used for a bottom fixing device of the unbonded prestressed steel bar when prestress is applied.

The foundation anchor is arranged below the steel reinforcement framework and is an expanded footing steel reinforcement cage, the expanded footing steel reinforcement cage is released in the pore-forming depth of the foundation anchor cage, then concrete is poured, and the foundation anchor is solidified into a fixed force foundation anchor, so that the bottom plate, namely the bottom of the pile, is fixed.

Further, the construction method comprises the steps of carrying out rotary spraying powder spraying pile or stirring pile foundation, arranging construction holes or direct drilling at the pile core of the rotary spraying powder spraying pile or stirring pile or the lap joint of the pile, and arranging a composite prestressed pile or a pressure-bearing pile with a steel reinforcement cage as a framework grouting or concrete pouring as a pile body in the holes; the main reinforcements of the reinforcement cage framework and the pile body of the prestressed pile are pre-tensioned or post-tensioned prestressed reinforcements.

The reinforcement cage framework can be a common prestressed pile and a bearing plate arranged at the bottom of the reinforcement cage framework, the main reinforcements of the reinforcement cage framework and the pile body of the prestressed pile are bonded, or the reinforcement cage framework and the pile body of the prestressed pile can be non-bonded and can be prestressed (particularly the latter), or the reinforcement cage framework can be provided with bonded reinforcements or locally bonded reinforcements according to the engineering design requirements.

The unbonded prestressed reinforcement is post-tensioned prestressed reinforcement and has the following structure: the steel bar finishing mill comprises a finish-rolled steel bar, wherein an anti-corrosion grease layer is arranged on the surface of the finish-rolled steel bar, and a plastic film sleeve is arranged outside the anti-corrosion grease layer. The post-tensioned pre-stressed anti-floating tensile pre-stressed pile steel bar comprises a main steel bar (comprising a main steel bar or a main steel bar connecting structure which connects the main steel bar through a connecting nut) as a basic force-bearing structure, wherein the main steel bar is a finish-rolled non-bonded steel bar, an anti-corrosive grease layer is arranged on the surface of the main steel bar, and a plastic film sleeve is arranged outside the anti-corrosive grease layer; coating the anticorrosive grease layer by a anticorrosive grease layer coating device, coating a polyethylene or polypropylene plastic film on the anticorrosive grease layer without bonding ribs by a plastic extruder, and forming a plastic sleeve (pipe) by a cooling cylinder mold; the plastic sleeve is wrapped by concrete or cement mortar, cement paste or other curable materials and is solidified; applying prestress on the main reinforcement steel bars (applying prestress after fixing is finished) to form a prestressed pile rod piece; and locking the main reinforcing steel bars by nuts, and applying prestress to the tensioned reinforcing steel bars to form the prestressed pile bar.

The diameter of the pile body is smaller than or larger than the diameter of the bottom anchor, because the enlarged head steel reinforcement cage is cast with concrete after being released in the self pore-forming depth and is solidified into the constant force bottom anchor, if the pile body adopts 100 or more prestressed steel bars with the diameter reaching about 40 millimeters, the pile body can be enclosed into the prestressed pile with the diameter of more than one meter and five. In particular, more than 30 unbonded (or bonded) prestressed reinforcements are used as the framework of the pile, the pile is of a cast-in-place pile structure, the pile can be distributed in a strip shape or in a broken line or an arc line according to the requirements of the building, and can be used as a prestressed continuous wall or a shear wall, and the pile foundation of special buildings such as subways, bridges and the like.

The main reinforcing steel bar structure is formed by connecting the segmented main reinforcing steel bars through connecting nuts. The combined assembly type prestressed pile component forms an engineering part with compression resistance and tensile resistance (mainly tensile resistance and better effect) in practical application. The extension connection type prestressed pile is a prestressed pile which can be connected into an extension rod piece and finally becomes an assembly.

When the prestressed pile is prepared, the diameter of the end part of a main reinforcing steel bar is provided with a steel bar cage capable of expanding a head framework or expanding the diameter, wherein the expanded head framework comprises the steel bar, the steel bar cage or the diameter-variable steel bar cage capable of expanding the diameter; pouring concrete or cement mortar, cement paste or one of other curable materials on the main reinforcement steel bars and the expansion head framework, and solidifying the concrete or the cement mortar, the cement paste or the other curable materials into the prestressed pile and the expansion head; the prestressed pile is formed by applying one of concrete or cement mortar, cement paste or other curable materials under the condition of applying prestress, and solidifying and curing.

The utility model discloses when plastic film cover reinforcing bar, especially the anti tensile reinforcing bar prestressed pile that floats of post-tensioned prestressing force were used, the real reinforcing bar that forms a free section of prestressing force's main muscle reinforcing bar, nevertheless no longer extension has the effect that the prestressing force was applyed.

The prepared anti-floating tensile steel bar prestressed pile can be used for prefabricating a prestressed pile assembly of prestress by a post-tensioning method and an application technology, and a steel bar cage or a steel bar cage with an enlarged diameter (variable diameter) is arranged at the end part of a main steel bar; wrapping one of concrete or cement mortar, cement paste or other curable materials, and solidifying; according to the design requirement of prestress application, the main reinforcement is a steel reinforcement, and a steel reinforcement material is configured, wherein the reinforcement material comprises a steel reinforcement cage, a stirrup, a steel sleeve, a steel wire mesh cage, a pressure bearing plate and a pressure bearing flange nut; the main reinforcing steel bars and the reinforcing steel bar material are solidified together to form the prestressed pile assembly. The main steel bar of the prestressed pile of the prestressed anti-floating tensile steel bar is applied later, and the anti-floating tensile prestress of the steel bar can be fully embodied.

The unbonded post-tensioned prestressed steel bar is used as a framework of the anti-floating tensile steel bar prestressed pile, and at least an anticorrosive grease layer coated on the outer layer of the steel bar is anticorrosive grease or anticorrosive asphalt or a polymer material. The front end of the main reinforcing steel bar of the prestressed pile assembly is provided with a device which is connected or grafted with a variable-diameter reinforcing steel bar cage, a fixed-diameter reinforcing steel bar cage, a bag or other anchor heads to form a prefabricated prestressed pile system.

The number of the main reinforcing steel bars of the prestressed pile assembly is one or more than one, the specification, the performance, the strength and the diameter of the reinforcing steel bars can be specifically determined according to the design requirements, and the prestressed pile with the large diameter can be poured; the length, the shape and the area of the cross section of the prestressed pile component are set according to specific engineering technical requirements; when the length of the rod piece required by engineering is overlong, two or more than two steel bar rod pieces can be connected by adopting a nut connector or other modes so as to achieve the required length; the steel bar nut connector can also be embedded in the prestressed pile in advance.

The application of the prestressed pile for reinforcing the foundation by the rotary spraying powder spraying or stirring pile can be used for preparing the anti-floating tensile prestressed steel bar prestressed pile assembly with prestress by a post-tensioning method and an application technology, and a steel bar cage or a steel bar cage with enlarged diameter (variable diameter) is arranged at the end part of a main steel bar; wrapping one of concrete or cement mortar, cement paste or other curable materials, and solidifying; according to the design requirement of prestress application, the main reinforcement is a steel reinforcement, and a steel reinforcement material is configured, wherein the reinforcement material comprises a steel reinforcement cage, a stirrup, a steel sleeve, a steel wire mesh cage, a pressure bearing plate and a pressure bearing flange nut; the main reinforcing steel bars and the reinforcing steel bar material are solidified together to form the prestressed pile assembly. Main steel bars of the prestressed pile of the prestressed anti-floating tensile steel bars are applied later; the number of the main reinforcing steel bars of the prestressed pile assembly is one or more than one, the specification, the performance, the strength and the diameter of the reinforcing steel bars can be specifically determined according to the design requirements, and the prestressed pile with the large diameter can be poured; the length, the shape and the area of the cross section of the prestressed pile component are set according to specific engineering technical requirements; when the length of the rod piece required by engineering is overlong, two or more than two steel bars are connected by adopting a nut connector or other modes to achieve the required length; the reinforced nut connector is embedded in the prestressed pile in advance.

The method comprises the steps of improving the soft soil layer foundation including but not limited to sludge, mucky soil, flow plastic, soft plastic or plastic cohesive soil, plain filling, silt, sandy soil, biological soil, gravelly soil and other soil layers by the aid of a rotary spraying powder spraying pile, a powder spraying or stirring pile, and forming construction holes or direct drilling holes in the pile core of the rotary spraying powder spraying pile or the stirring pile or at the lap joint of the pile, wherein a main reinforcing steel bar rib is arranged in each construction hole, cement (sand) slurry is injected by taking a reinforcing steel bar cage as a framework, or concrete is poured into a composite prestressed pile or a pressure-bearing pile which is taken as a pile body; the main reinforcements of the reinforcement cage framework and the pile body of the prestressed pile are pre-tensioned or post-tensioned prestressed reinforcements.

Has the advantages that: the rotary spraying powder spraying pile (strengthening body) and the stirring pile in the prior art can be used for strengthening the foundation of the existing building and the newly-built building, in a word, the improvement on the soil body which can not be formed with holes is key + a plurality of different traditional prestressed piles; the method can be further applied to soil improvement and various cast-in-place piles with difficult hole forming and poor foundation firmness. And the soil layer of the engineering such as medium and high-rise buildings, deep foundation pits, subways and the like is reinforced or waterproof. The existing rotary spraying powder spraying pile is used as an anti-seepage curtain wall independently in a fixed spraying or swinging spraying mode in foundation pit support engineering or used as an anti-seepage retaining wall in cooperation with an anti-lodging pile array (as oriented swinging and spraying among piles). But because of the prestressed pile and the pile foundation that current spout powder jet pile (reinforcement body) and mixing pile far away be not enough to become the atress in intensity, and the utility model provides a this problem, through mixing pile, spout powder jet pile operation soon, realize the processing to silt and soft soil such as silt soil, plain fill, silt, cohesive soil and the loose sand soil of no flow groundwater, make its induration become the pile body soil layer that has wholeness, water stability and certain intensity. The composite prestressed pile (or pressure-bearing pile) with enlarged footing, which is formed by combining the preparation of prestressed pile with enlarged footing of variable-diameter steel reinforcement cage with the construction of mixing pile or high-pressure jet grouting pile, can be used as anti-floating tensile prestressed pile or pressure-bearing pile foundation even if the existing anti-floating row pile is matched (is used for directional swing-spraying among piles) to be used as an anti-seepage retaining wall. The construction cost is low, and the effect is good. Especially, the main reinforcements of the reinforcement cage framework and the pile body of the prestressed pile are pre-tensioned or post-tensioned prestressed reinforcements, and the application is very significant.

Drawings

Fig. 1 is a schematic view of the cast-in-place pile of the present invention; the method comprises the following steps of a filling pile self a, a variable-diameter reinforcement cage b added in the filling pile and a filling pile variable-diameter reinforcement cage composite pile c.

FIG. 2 is a schematic diagram of the engineering process of the utility model when the mixing pile is used; description of the steps: the steps in FIG. 2: positioning a, stirring and sinking b, spraying and stirring to rise c, spraying and stirring to finish d, initially setting and pulling out a steel pipe e by a grouting body, reaming f by spraying mechanical or high-pressure rotary spraying powder on the lower part, sinking a reducing steel reinforcement cage and a prestressed pile g, opening an expanding mechanism h of the reducing steel reinforcement cage, expanding the reducing steel reinforcement cage to a design size i, and applying prestress j by a post-tensioning method after grouting or pouring concrete.

FIG. 3 is a schematic structural view of a pile of the present invention, which is made of a plurality of unbonded prestressed reinforcements 3-1-1 and has a non-enlarged head with an equal diameter; forming a hole 10-1, concrete 3-2, welding, a nut 3-3-1, a nut 3-3-2 and reinforcement cage stirrups 3-5 and 3-6; and 3-4 welding and bottom plates or steel backing plates or bearing plates for anchoring the nuts 3-3-2 and locking prestress.

FIG. 4 is a schematic structural view of an enlarged head equal diameter post-tensioned prestressed pile made of a plurality of unbonded prestressed reinforcements of the present invention;

FIG. 5 is a schematic structural view of a non-expanded head equal diameter post-tensioned prestressed pile made of single unbonded prestressed reinforcement according to the present invention;

FIG. 6 is a schematic structural view of the single unbonded prestressed reinforcement connection enlarged head equal-diameter post-tensioned prestressed pile of the present invention;

FIG. 7 is a schematic structural view of the expanded head or the equal-diameter post-tensioned prestressed pile made of a plurality of unbonded prestressed reinforcements of the present invention connected to an upper supporting rod; forming a hole 10-1, an enlarged head hole 10, concrete 3-2, a single main reinforcement 3-1, a connecting nut 3-3 or a main reinforcement fixing nut, flange sleeves 3-3-1 and 3-3-2, and reinforcement cage stirrups 3-5 and 3-6; the bottom plate or steel backing plate or bearing plate 3-4 is used for connecting and fixing the flange sleeve 3-3-2 of the upper pile rod column 3-10. 3-10 parts of upper pile rod column; 3-9 of grid ribs; a plurality of unbonded prestressed reinforcements 3-1-1; 3-5-1 parts of a lubricating oil layer of the steel bar and 3-6-1 parts of a (plastic) jacket of the lubricating oil layer;

FIG. 8 is a schematic structural view of an enlarged footing connecting pile made of single unbonded prestressed reinforcement according to the present invention; the expanded head reinforcement cage 10, the expanded head concrete 12 and the guide sleeves 14 and 16-1 are fixed nuts at the lowest end (of the expanded head reinforcement cage);

fig. 9 is a schematic structural view of a bag enlarged footing post-tensioned prestressed pile made of single unbonded prestressed reinforcement of the present invention; 12-1 and 17 sacks of sack concrete;

FIG. 10 is a schematic structural view of a post-tensioned prestressed pile with a single unbonded prestressed reinforcement prepared into a plain concrete expanded footing according to the present invention;

fig. 11 is a schematic structural view of the umbrella frame concrete expanding head post-tensioned prestressed pile prepared by single unbonded prestressed reinforcement of the present invention.

Detailed Description

Example 1: a variable-diameter steel bar cage expanded footing prestressed pile or pressure-bearing pile combined with a mixing pile or a rotary spraying powder spraying pile is characterized in that a construction hole or a direct drilling hole is arranged at the lap joint of a pile core or a pile of the rotary spraying powder spraying pile or the mixing pile constructed by a single pipe, a double pipe method and a triple pipe method, and the pile is formed by reaming construction, lowering of a variable-diameter steel bar cage and a pull rod assembly, grouting or pouring of concrete and composite prestressed pile (or pressure-bearing pile).

Example 1-1: a variable diameter steel reinforcement cage enlarged footing pre-stressed pile anti-floating or pressure-bearing pile, including spraying powder and spraying the pile or mixing the pile as the foundation soon; the construction holes or direct drilling holes are arranged at the pile cores of the rotary spraying powder spraying piles or the mixing piles or the lap joints of the piles, and composite prestressed piles or pressure-bearing piles which take variable-diameter reinforcement cages as frameworks and take grouting or cast-in-place concrete as pile bodies are arranged in the holes.

Examples 1 to 2: comprises a rotary powder spraying pile or a stirring pile as a foundation; the construction holes or direct drilling holes are arranged at the pile cores of the rotary spraying powder spraying piles or the mixing piles or the lap joints of the piles, and composite prestressed piles or pressure-bearing piles which take variable-diameter reinforcement cages as frameworks and take grouting or cast-in-place concrete as pile bodies are arranged in the holes.

Examples 1 to 3: the construction holes or direct drilling holes are arranged at the lap joints of the pile cores or piles of the rotary spraying powder spraying piles or stirring piles constructed by a single-pipe method, a double-pipe method and a triple-pipe method, and the diameter-variable reinforcement cage is added into the holes to enlarge heads and pour grout or pour concrete to form the composite prestressed piles or piles.

Examples 1 to 4: particularly, the diameter of the core of the rotary spraying powder spraying pile or the stirring pile, which is taken as the foundation, is at least 2 times larger than the diameter of the core of the prestressed pile embedded in the pile. The depth of the pile core is also larger than the embedded depth of the prestressed pile.

Examples 1 to 5: the pile is provided with more than 1 and less than 150 unbonded or bonded prestressed reinforcements as a framework of the pile, the pile is of a cast-in-place pile structure, the bottom of each reinforcement is provided with a backing plate or a bottom anchor, each backing plate is a large-diameter steel plate, holes are uniformly formed in the steel plates, and each hole is internally provided with one prestressed reinforcement; the backing plate or the bottom-added anchor is used for a bottom fixing device of the unbonded prestressed steel bar when prestress is applied.

The bottom anchor is an enlarged footing steel reinforcement cage, and the enlarged footing steel reinforcement cage pours the concrete after releasing in the pore-forming degree of depth of oneself, solidifies into the dead weight bottom anchor to fix the bottom plate promptly at the bottom of the pile.

The description of the drawings fully embodies the embodiments and essential parts are disclosed in the applicant's prior applications.

The unbonded prestressed reinforcement is post-tensioned prestressed reinforcement and has the following structure: the steel bar finishing mill comprises a finish-rolled steel bar, wherein an anti-corrosion grease layer is arranged on the surface of the finish-rolled steel bar, and a plastic film sleeve is arranged outside the anti-corrosion grease layer.

The diameter of the pile body is lower than or higher than that of the pile body of the enlarged head pile bottom, because the enlarged head steel reinforcement cage is released in the self pore-forming depth and then poured with concrete, the pile body is solidified into a fixed-force bottom anchor, and if the pile body adopts 100 or more prestressed steel bars with the diameter reaching about 40 millimeters, the pile body can be enclosed into a prestressed pile with the diameter of more than one meter and five meters.

The post-tensioned pre-stressed anti-floating tensile pre-stressed pile steel bar comprises a main steel bar (comprising a main steel bar or a main steel bar connecting structure which connects the main steel bar through a connecting nut) as a basic force-bearing structure, wherein the main steel bar is a finish-rolled non-bonded steel bar, an anti-corrosive grease layer is arranged on the surface of the main steel bar, and a plastic film sleeve is arranged outside the anti-corrosive grease layer; coating the anticorrosive grease layer by a anticorrosive grease layer coating device, coating a polyethylene or polypropylene plastic film on the anticorrosive grease layer without bonding ribs by a plastic extruder, and forming a plastic sleeve (pipe) by a cooling cylinder mold; the plastic sleeve is wrapped by concrete or cement mortar, cement paste or other curable materials and is solidified; applying prestress on the main reinforcement steel bars (applying prestress after fixing is finished) to form a prestressed pile rod piece; and locking the main reinforcing steel bars by nuts, and applying prestress to the tensioned reinforcing steel bars to form the prestressed pile bar.

The main reinforcing steel bar structure is formed by connecting the segmented main reinforcing steel bars through connecting nuts.

When the prestressed pile is prepared, the end part of the main reinforcement steel bar is provided with an expansion head framework, and the expansion head framework comprises a steel bar, a steel reinforcement cage or a variable-diameter steel reinforcement cage capable of expanding the diameter; pouring concrete or cement mortar, cement paste or one of other curable materials on the main reinforcement steel bars and the expansion head framework, and solidifying the concrete or the cement mortar, the cement paste or the other curable materials into the prestressed pile and the expansion head; the prestressed pile is formed by applying one of concrete or cement mortar, cement paste or other curable materials under the condition of applying prestress, and solidifying and curing.

Especially, the end part of the main reinforcing steel bar is provided with a reinforcing cage or a (diameter-variable) reinforcing cage capable of expanding the diameter; and applying one of concrete or cement mortar, cement paste or other curable materials to the main reinforcing steel bars and the reinforcing cage, and solidifying the concrete or cement mortar, the cement paste or other curable materials to form the prestressed pile. According to the design requirement of prestress application, the main reinforcement is a steel reinforcement, and a steel reinforcement material is configured, wherein the reinforcement material comprises a steel reinforcement cage, a stirrup, a steel sleeve, a steel wire mesh cage, a pressure bearing plate and a pressure bearing flange nut; the main reinforcing steel bars and the reinforcing steel bar material are solidified together to form the prestressed pile bar. The main steel bar of the prestressed pile of the prestressed anti-floating tensile steel bar is applied later, and the anti-floating tensile prestress of the steel bar can be fully embodied.

The unbonded pre-tensioned or post-tensioned prestressed anti-floating tensile steel bar prestressed pile is formed, and the anticorrosive grease layer is anticorrosive grease or anticorrosive asphalt or a polymer material.

The front end of the main reinforcement steel bar of the prestressed pile rod piece is provided with a device which is connected or connected with a variable-diameter reinforcement cage, a fixed-diameter reinforcement cage, a bag or other anchor heads to form a prefabricated prestressed pile system.

The combined assembly type prestressed pile component forms an engineering part with compression resistance and tensile resistance (mainly tensile resistance and better effect) in practical application. The extension connection type prestressed pile is a prestressed pile which can be connected into an extension rod piece and finally becomes an assembly.

The main muscle reinforcing bar (including the main muscle reinforcing bar or with the main muscle reinforcing bar through coupling nut's main muscle reinforcing bar connection structure) is regarded as the structure of basic load for the main atress spare of prestressed pile, and the main muscle reinforcing bar can adopt ordinary reinforcing bar, include finish rolling reinforcing bar or add anticorrosive processing in surface again, and unbonded prestressed pile reinforcing bar can also have following structure: the surface of the main reinforcement steel bar is provided with an anti-corrosive grease layer, and a plastic film sleeve is arranged outside the anti-corrosive grease layer; coating the anticorrosive grease layer by a anticorrosive grease layer coating device, coating a polyethylene or polypropylene plastic film on the anticorrosive grease layer without bonding ribs by a plastic extruder, and forming a plastic sleeve (pipe) by a cooling cylinder mold; the plastic sleeve is wrapped by concrete or cement mortar, cement paste or other curable materials and is solidified; applying prestress on the main reinforcement steel bars after prestress (applying prestress after fixing is finished) to form a prestressed pile assembly; and locking the main reinforcing steel bars by using nuts, and applying prestress to the tensioned reinforcing steel bars to form the prestressed pile assembly.

The utility model discloses when plastic film cover reinforcing bar, especially the anti tensile reinforcing bar prestressed pile that floats of post-tensioned prestressing force were used, the real reinforcing bar that forms a free section of prestressing force's main muscle reinforcing bar, nevertheless no longer extension has the effect that the prestressing force was applyed.

The front end of the main reinforcing steel bar of the prestressed pile assembly is provided with a device which is connected or grafted with a variable-diameter reinforcing steel bar cage, a fixed-diameter reinforcing steel bar cage, a bag or other anchor heads to form a prefabricated prestressed pile system.

The number of the reinforcing steel bars in the prestressed pile assembly is not limited, when the length of the rod piece required by the engineering is overlong, two or more than two reinforcing steel bar rod pieces can be connected by adopting a nut connector mode or other modes so as to achieve the required length; the steel bar nut connector can also be embedded in the prestressed pile in advance.

Each unbonded prestressed reinforcement is fixed on the upper portion of the pile body by adopting a bottom plate and a nut, then the concrete pile body is poured, after the concrete is solidified, prestress is applied to each unbonded prestressed reinforcement of the bottom plate by adopting a post-tensioning prestress applying device of an anchor rod CN2020103929335 provided by the application, and the concrete comprises various mortar or gravel concrete.

The prepared anti-floating tensile steel bar prestressed pile can be used for prefabricating a prestressed pile assembly of prestress by a post-tensioning method and an application technology, and a steel bar cage or a steel bar cage with an enlarged diameter (variable diameter) is arranged at the end part of a main steel bar; wrapping one of concrete or cement mortar, cement paste or other curable materials, and solidifying; according to the design requirement of prestress application, the main reinforcement is a steel reinforcement, and a steel reinforcement material is configured, wherein the reinforcement material comprises a steel reinforcement cage, a stirrup, a steel sleeve, a steel wire mesh cage, a pressure bearing plate and a pressure bearing flange nut; the main reinforcing steel bars and the reinforcing steel bar material are solidified together to form the prestressed pile assembly. The main steel bar of the prestressed pile of the prestressed anti-floating tensile steel bar is applied later, and the anti-floating tensile prestress of the steel bar can be fully embodied.

The construction hole or the direct drilling → the reaming construction → the lowering of the diameter-variable steel bar cage and the pull rod assembly → the grouting or the concrete pouring → the formation of the composite prestressed pile (or the bearing pile).

A variable-diameter steel reinforcement cage enlarged footing prestressed pile combined with a mixing pile or a jet grouting powder pile and a construction method thereof are disclosed, the pile position is determined → the pile machine is in place → the mixing pile or the high-pressure jet grouting powder pile is constructed, a prestressed pile (or a bearing pile) construction hole is reserved or a direct drilling is carried out → the lower part of the hole is enlarged → the variable-diameter steel reinforcement cage and a pull rod assembly are put down, the variable-diameter steel reinforcement cage at the enlarged hole is released into a large-diameter steel reinforcement cage → the large-diameter steel reinforcement cage and the whole construction hole are grouted or concrete is poured → a composite prestressed pile (or a bearing pile) formed by combining the variable-diameter steel reinforcement cage pile with the mixing pile or the high-pressure jet grouting powder pile is formed.

The construction holes or direct drilling holes are arranged at the pile cores or the lap joints of the rotary spraying powder spraying piles or the stirring piles which comprise single-pipe construction, double-pipe construction and triple-pipe construction.

The interval (lap joint) of the double-pipe high-pressure rotary powder spraying pile is as follows: the variable-diameter reinforcement cage enlarged footing composite prestressed pile (or pressure-bearing pile) can be constructed at the interval of the double-pipe high-pressure rotary spraying powder spraying pile, or at the interval of two adjacent double-pipe high-pressure rotary spraying powder spraying piles within about initial setting time of the pile cores of the single-pipe, double-pipe and triple-pipe construction rotary spraying powder spraying pile or stirring pile.

Or the construction hole of the prestressed pile (or the bearing pile) is reserved after the construction of the mixing pile or the high-pressure jet grouting powder spraying pile is finished, the bottom end of the prestressed pile (or the bearing pile) is reamed after the pile body has certain strength, a diameter-variable steel reinforcement cage and a pull rod assembly are put down, and the pile forming and the shifting of the grouting or pouring concrete composite prestressed pile (or the bearing pile) are carried out.

The construction technical measures, quality assurance measures and construction steps of the variable-diameter reinforcement cage enlarged footing composite prestressed pile (or pressure-bearing pile) combined with the mixing pile or the jet grouting pile are as follows:

first, engineering measurement

Firstly, pile control and water level measurement are carried out: the surveyor uses theodolite and level gauge to measure and place according to the control point that the construction unit provided by, ensures the position accuracy of foundation ditch excavation to measure present natural ground elevation, and make obvious mark, guarantee that the degree of depth of penetrating into soil, pile length and pile bolck elevation of stirring the stake deeply meet the design requirement, control point and level point need make the map.

Measuring pile position: the measuring staff is used for measuring and placing on the working surface according to the drawing by using instruments and steel rulers, and the bamboo chips or the wood piles are nailed into the soil to be used as marks, so that the overlapping length of the adjacent piles is ensured to meet the design requirement.

Do good, clearance working face barrier

Before the operation, the working face barriers are cleaned to remove broken bricks and stones so as to avoid influencing the construction of the deep stirring pile.

Thirdly, when the mixing pile or the high-pressure rotary spraying powder spraying pile is constructed, the corresponding pile machine is in place, deeply mixed or in rotary spraying powder spraying consolidation sand layer:

(3-1) deep mixing pile consolidation sand layer

Welding of a drill rod and a stirring pipe in construction of a stirring pile or a high-pressure rotary jet powder spraying pile must be firm, concentricity is guaranteed, bending is avoided, the length of the stirring pipe and the length of a blade are monitored and measured after welding, and a check sheet is filled after measured data meet the technical requirements of design of the depth of penetration, the pile length and the like.

The pile driver must be horizontally and stably installed. The bottom of the machine must be leveled and tamped by using sleepers which are 50cm multiplied by 50cm square timbers. The frame and the stirring pipe must be vertical, the stirring head is aligned to the pile core, the pile position deviation is less than or equal to 50mm, and the verticality is controlled within 1%. The stirring pipe is marked with red paint to ensure that the depth of the soil penetration meets the design requirements, and the accuracy of the pile position and the verticality of the pile meet the standard requirements.

The slurry conveying pipe must adopt a high-pressure rubber pipe, so that the slurry conveying pipe cannot be damaged, and a joint is tightly tied by a No. 8 iron wire so that leakage cannot occur.

Preparing cement paste: the cement mixing ratio is 10 percent, and the water cement ratio is 0.50. The consolidated sand layer may be formulated according to design requirements.

The cement is 42.5-grade ordinary silica, and quality guarantee books of the batch must be provided when the cement is provided. The cement must be sampled and inspected when entering the field, and can be put into use after the stability and the strength are qualified, and the cement should be kept properly after entering the field and cannot be affected with damp, deteriorated and agglomerated.

Secondly, strictly controlling the cement dosage according to the 10 percent doping ratio of the consolidated sand layer, and preparing cement slurry according to the water cement ratio of 0.50. The dosage of single-pile cement must be strictly controlled, and the dosage of the single-pile cement must not be reduced, so as to ensure the requirements of compressive strength and seepage-proofing property of the cement soil, and after being filtered by a screen mesh, the cement soil is placed into a slurry storage barrel to be continuously stirred, so that the cement slurry cannot be precipitated and separated.

Stirring and guniting

Firstly, before construction, the construction parameters of the mortar pump, such as pumping pressure, mortar conveying amount, time for mortar to reach a mortar spraying opening through a mortar conveying pipe, lifting speed and the like are calibrated, and a pile forming test is carried out.

Secondly, the sinking speed of the mixing pile during mixing is 0.8m/min, the mixed soil layer is fully cut up, and after the mixing pile sinks to the designed depth, the mixing pile is reversely mixed and simultaneously sprayed with slurry to lift, the lifting speed is 0.5m/min, so that the cement slurry and the soil body are fully mixed and mixed uniformly, and the strength of the pile body is ensured. The control method of re-stirring sinking and guniting stirring lifting is the same as that of primary stirring. The high-pressure rotary spraying powder spraying pile spraying pressure is as follows: 20 MPa; the lifting speed is 0.2 m/min. The high-pressure rotary powder spraying and grouting is carried out from bottom to top, and when the grouting pipe cannot be lifted at one time and needs to be unloaded for several times, the overlapping length of the spraying after the pipe unloading is not less than 10 cm. During the construction process of the rotary spraying powder-sprayed pile, the cement mixing amount and the pressure of cement slurry flow are reasonably determined according to the construction site. After the guniting is confirmed, stirring and lifting can be carried out, and the guniting can not be interrupted in the midway.

After the pile is deeply stirred for 3-5 days, when the strength reaches 30-50%, the anchor testing construction of the large-head prestressed pile of the variable-diameter reinforcement cage can be carried out on the original pile position.

(3-2) carrying out rotary powder spraying to consolidate the sand layer: the rotary powder spraying adopts drilling, a grouting pipe provided with a special alloy nozzle is put to a preset position, cement slurry is horizontally sprayed into a soil body at a high speed through a special spray head at the end of a drill rod by using a high-pressure pump, a soil layer is cut by means of the impact force of liquid, simultaneously, one surface of the drill rod rotates at a certain speed (20r/min), and the other surface of the drill rod slowly lifts at a low speed (15-30 cm/min) to fully stir, mix and solidify the soil body and cement slurry, and the slurry of a high-pressure jet device is fully mixed with the ejected slurry after the soil body is stripped to form the columnar (rotary powder spraying) circular section pile. The swing spraying and the top spraying are also in the spraying form of high-pressure grouting, but the construction mode of the same rotary spraying powder spraying is the same, so that the swing spraying and the top spraying are not separately arranged in the pile foundation. The rotary spraying powder spraying pile forms a cylindrical consolidation body (namely, the rotary spraying powder spraying pile) with certain strength (0.5-8.0 MPa), so that the foundation is reinforced. The rotary spraying powder spraying pile is characterized in that: the shear strength of the foundation can be improved; the large-diameter consolidation body which is 8-10 times larger than the hole can be formed by spraying the small-diameter drilling rotary spraying powder, and the large-diameter consolidation body can be used for foundation consolidation of the existing building without disturbing the nearby soil body; the construction noise is low, and the vibration is small; the high-pressure rotary powder spraying pile sprays cement slurry into a soil layer by a high-pressure rotating nozzle to be mixed with soil mass, so as to form a continuously lapped cement reinforcing body. The construction occupies less land, the vibration is small, and the noise is lower. Single tube: the pile diameter is the minimum by only spraying cement slurry, the pile diameter is generally 0.7-1.0m, the pile diameter is generally used in loose and slightly dense sand layers, the cement consumption is generally 50-80kg/m, the normal construction speed is generally 20cm/min, and when the strength reaches 30-50%, the pre-stressed pile anchor test construction of the large-end pre-stressed pile of the variable-diameter reinforcement cage can be carried out on the original pile position.

And (3) reserving a prestressed pile (or bearing pile) construction hole after the construction of the mixing pile or the high-pressure jet grouting powder spraying pile is finished, expanding the bottom end of the prestressed pile (or bearing pile) after the pile body has certain strength, lowering a variable-diameter steel reinforcement cage and a pull rod assembly, and grouting or pouring concrete into the composite prestressed pile (or bearing pile) to form a pile and shift.

The pre-stressed pile (or pressure-bearing pile) rod piece can be locked by post-tensioning pre-stress tension according to the design requirement.

Each unbonded prestressed reinforcement is fixed on the upper portion of the pile body by adopting a bottom plate and a nut, then the concrete pile body is poured, after the concrete is solidified, prestress is applied to each unbonded prestressed reinforcement of the bottom plate by adopting a post-tensioning prestress applying device of an anchor rod CN2020103929335 provided by the application, and the concrete comprises various mortar or gravel concrete.

The variable-diameter reinforcement cage big-end prestressed pile anchor test construction method comprises the following steps: drilling holes

And determining the position of the specific prestressed pile according to the reference line, marking by using a bar inserting method, and informing supervision and owner field personnel to recheck and check.

Drilling by a prestressed pile drilling machine:

(1) the diameter of the prestressed pile rod body is 200mm, the hole site deviation is less than or equal to 100mm, the hole inclination is less than or equal to 1.0%, and the hole diameter is more than or equal to 200 mm.

(2) The lifting speed of the rotary spraying powder spraying is 10-20 cm/min, and the rotating speed is 10-20 r/min.

(3) The cement slurry is pure cement slurry with a water-cement ratio of 0.5, the rotary spraying powder spraying pressure is 25-30 MPa, and the slurry amount is 75L/min.

(4) After the injection is interrupted, the lapping length is more than or equal to 0.5m when the grouting is resumed.

The design length of the prestressed pile is as follows: 12m, 8m of the common section of the prestressed pile, 4m of the expanded head section, 0.5m of the depth of the drilled hole of the prestressed pile exceeding the design length of the prestressed pile and 1% of the verticality deviation of the anchor hole. The mechanical boring depth is confirmed in situ. And when the reaming depth reaches the design depth, moving to the next drilling hole.

The constructors of all the machines must carefully fill in the original record table during drilling, and record the footage condition of each hole, stratum change and other special conditions during construction.

High-pressure rotary powder spraying and reaming: the high pressure jet reaming can be performed by water or cement slurry. When the cement slurry (or water cutting) reaming process is adopted, reaming is carried out at least twice up and down and back; when the hole expanding process is adopted, if the hole is easy to collapse, the cement grout is adopted for expanding the hole for one time finally.

(1) The diameter of the diameter expansion section is 750mm, the diameter expansion is carried out by adopting plain water hole expansion, the hole expansion injection pressure is 25-30 MPa, the spray pipe rotates at a constant speed during injection, and the hole expansion is carried out for 2 times at the constant speed.

(2) And when the drilling depth meets the design requirement, increasing the injection pressure to 25-30 MPa, and performing high-pressure injection hole expansion at the lifting speed of 20cm/min and the rotating speed of 20 r/min.

(3) The length of the drill rod outside the measuring hole is used for calculating the reaming length, after the reaming length reaches the design requirement, the reaming section is subjected to re-spraying in order to ensure that the diameter of the reaming section meets the design requirement, and cement slurry is used for spraying the slurry.

(4) After the rotary powder spraying and reaming are finished, the drill rod is lifted out of the hole, and a large amount of clear water is used for cleaning the drilling machine, the high-pressure slurry pump and the pipeline immediately.

(5) Note that:

firstly, during jet reaming, construction parameters such as slurry state, jet flow, pressure, drill rod rotating speed, lifting speed and the like are monitored in real time, and design requirements are met.

Secondly, in the high-pressure injection reaming process, the injection is not interrupted; once the jet interruption occurs, when the jet is jetted again, the lap joint length is not less than 500mm, and the interval time is not more than 30 min. The rate of penetration is reduced after the high jet section enters the formation. The injection pressure is raised.

Thirdly, the high-pressure injection water is filtered by a filter screen, the slurry and the cement paste are stirred for the second time and are filtered in the slurry transfer process so as to prevent the pipe blockage accident and influence the normal construction progress.

And fourthly, after the elevation control construction site is excavated, the elevation of each working surface is measured by a level gauge, the length of a hollow hole of each prestressed pile hole site is calculated, and the anchor conveying device is marked.

Controlling the aperture of the expanded body and the aperture of the free section in advance, wherein the injection pressure of the free section is not less than 10MPa, and the feeding or lifting speed of a nozzle is used for carrying out low-pressure injection pore-forming at the lifting speed of 20cm/min and the rotating speed of 20 r/min; spraying pressure at the reaming section is 25-30 MPa, and high-pressure spraying reaming is carried out at the feeding or lifting speed of the nozzle at the lifting speed of 20cm/min and the rotating speed of 20 r/min; ensure that the pore diameter of the hole formed in the non-expansion body section is not less than 200mm and the diameter of the expansion body section is not less than 700 mm.

And sixthly, removing residues in the hole after finishing the hole, and simultaneously measuring the hole depth and the inclination of the anchor hole by a field engineer and a quality inspector to perform next procedure construction after meeting the design requirements.

Manufacturing and installing a prestressed pile: (1) manufacturing a prestressed pile: and the prestressed pile is manufactured and stored in the on-site steel bar processing shed. The prestressed pile rod body reinforcing steel bar adopts PSB1080 grade reinforcing steel bar with the diameter of 40mm, the reinforcing steel bar brush is anticorrosive before manufacturing, the corrosion prevention adopts II grade corrosion prevention, and the rod body brush is subjected to epoxy resin corrosion prevention treatment. And (4) blanking the prestressed pile according to the design requirement or the length required by the depth of the rock-entering hole. The prestressed pile reinforcing steel bars are connected by adopting a high-strength connector.

The quality requirement of the rod body is as follows:

firstly, the prestressed pile rod body is made of high-strength steel bars coated with anticorrosive coatings, the adhesive force between the coating and a steel bar base layer is not lower than 5MPa, the adhesive force between the coating and a cement base layer is not lower than 1.5MPa, and the coating thickness is more than 280 microns.

The prestressed pile rod body unbonded reinforcing steel bar is a PSB 1080-level reinforcing steel bar with the diameter of 40mm, a connecting nut is connected to the rated length, the prestressed pile rod body unbonded reinforcing steel bar is coated with butter and is wrapped by a thin film, and one end of the prestressed pile rod body unbonded reinforcing steel bar is installed on an anchor backing plate or a bearing plate or is fixed with an expansion head reinforcing steel bar cage bottom plate by the nut.

Carrying reinforcing steel bars of the anti-floating prestressed pile: the operation is stable, and the deformation of the anchor hole reinforcing steel bars is prevented. When the centering bracket is placed, the centering bracket is stably and vertically arranged in the hole, and the centering bracket is firmly arranged to prevent the centering bracket from inclining in the hole.

Mounting a prestressed pile: before the rod body is placed into the drill hole, the quality of the rod body is checked, and the rod body is ensured to be assembled to meet the design requirement. When the rod body is installed, the rod body is prevented from being twisted, pressed and bent. After the materials and the manufacturing process are inspected to be qualified, a drilling machine is used for lifting or manually lifting the rod body along the hole wall to send the rod body into the hole for anchoring, the grouting pipe and the prestressed pile are simultaneously placed into the hole, and the distance from the end of the grouting pipe to the bottom of the hole is preferably 200 mm. The diameter-variable switch pin of the variable-diameter steel reinforcement cage is assembled by disassembling and binding a steel wire rope, and is inserted into the hole along with the prestressed pile; the length of the prestressed pile inserted into the hole is not less than 95% of the design specification, and after the prestressed pile is installed, the prestressed pile cannot be knocked randomly and cannot be lifted randomly.

Opening a reinforcement cage: after the diameter-variable steel reinforcement cage prestressed pile is installed at a designed elevation, the verticality (the hole slope is less than or equal to 1.0%) is controlled, then a mechanical winch or a manual work is used for pulling out the diameter-variable switch pin, the pause is forbidden in the middle, and the steel reinforcement cage is ensured to be opened at one time. Then, grouting is prepared.

Grouting: (1) the slurry is cement slurry with a water-cement ratio of 0.5. The number of the test blocks for testing the grouting slurry strength is determined according to no less than one group of 50 prestressed piles. And each group of test blocks is not less than 3. The detection of the strength of the cement paste refers to the standard of basic performance test methods of building mortar (JGJ/T70-2009).

(2) The grouting pipe and the twisted steel are bound together, and the grouting pipe can bear the pressure of 5.0MPa, so that the grout can be smoothly pressure-poured to the anchoring section of the expanded head at the bottom of the drill hole. And (3) timely filling cement slurry after the variable-diameter reinforcement cage is installed and opened, adopting a high-pressure grouting process for grouting the expanded body anchoring section of the reinforcement cage, filling clean cement slurry, uniformly stirring and sieving the cement slurry, and using the cement slurry after stirring, wherein the cement slurry is used up before initial setting. And determining grouting pressure according to field test conditions, wherein the grouting density of the slurry is ensured. The distance from the end of the grouting pipe to the bottom of the hole is preferably 200mm, and the grouting pipe is slowly pulled out at a constant speed along with the injection of the slurry, so that the slurry in the hole is fully injected. After grouting, stopping grouting when grout overflows from the orifice or the grout discharged from the exhaust pipe is consistent with the injected grout in color and concentration. The slurry should be stirred uniformly and used with stirring, and the slurry should be used up before initial setting. And (5) well performing grouting recording work. Due to the shrinkage of the slurry, after the slurry of the prestressed pile shrinks, the cement slurry with the same label is supplemented to the top of the hole.

After the test prestressed pile reaches the age of 28d or the strength of the slurry material reaches 80% of the designed strength, a basic test is carried out to detect the pulling resistance. The detection result of the diameter of the expanded head is specifically detected according to the regulation of relevant provisions in JGJ/T282-2012, technical Specification for high-pressure jet expanded head prestressed piles.

Claims (9)

1. A multi-main-rib prestressed pile is characterized in that a composite prestressed pile or a pressure-bearing pile with a steel reinforcement cage as a framework grouting pile body or a cast-in-place concrete as a pile body is arranged in a drill hole; the main reinforcements of the reinforcement cage framework and the pile body of the prestressed pile are pre-tensioned or post-tensioned prestressed reinforcements.

2. The pre-stressed pile with multiple main bars as claimed in claim 1, wherein the front end of the main bar of the pile body is provided with a device for connecting, grafting or riveting with the enlarged head of the variable diameter reinforcement cage, the fixed diameter reinforcement cage, the bearing plate, the bag or the sheathing bag, or the anchor head of other supporting bodies, so as to form a pre-stressed pile frame system with enlarged head or non-enlarged head.

3. The pre-stressed pile as claimed in claim 1, wherein the reinforcement cage frame is formed by combining a common pre-stressed pile and a bearing plate at the bottom of the reinforcement cage frame, and the main reinforcements of the reinforcement cage frame and the pre-stressed pile body are bonded or non-bonded prestressed reinforcements, or bonded or partially bonded reinforcements according to engineering design requirements.

4. The prestressed pile as claimed in claim 1, wherein more than 1 and less than 150 unbonded or bonded prestressed reinforcements are provided as a skeleton of the pile, the pile is of a cast-in-place pile structure, the bottom of the reinforcement is provided with a backing plate or a bottom anchor, the backing plate is a large-diameter steel plate, holes are uniformly formed in the steel plate, and each hole is provided with one prestressed reinforcement; the backing plate or the bottom-added anchor is used for a bottom fixing device of the unbonded prestressed steel bar when prestress is applied.

5. The prestressed pile as claimed in claim 4, wherein 3 or more unbonded prestressed reinforcements are used as a framework of the pile, a bottom anchor is arranged under the reinforcement framework, the bottom anchor is an enlarged head reinforcement cage, and the enlarged head reinforcement cage is released within the self hole-forming depth and then poured with concrete to be solidified into a fixed-force bottom anchor, so that the bottom plate, i.e. the pile bottom, is fixed.

6. The prestressed pile according to claim 4, wherein said unbonded prestressed reinforcement is a post-tensioned prestressed reinforcement, and is constructed as follows: the steel bar finishing mill comprises a finish-rolled steel bar, wherein an anti-corrosion grease layer is arranged on the surface of the finish-rolled steel bar, and a plastic film sleeve is arranged outside the anti-corrosion grease layer.

7. The prestressed pile as claimed in one of claims 1-4, wherein the enlarged footing of the cage skeleton is used as a bottom anchor, the pile body is connected and fixed, i.e. connected with the bottom anchor, and the diameter of the pile body is smaller or larger than that of the bottom anchor, because the cage of the enlarged footing is released in the self hole-forming depth and then poured with concrete and solidified into the fixed-force bottom anchor; the pile body adopts 100 or more prestressed reinforcements with the diameter reaching about 40mm, so that the prestressed pile with the diameter of more than one meter and five can be formed by encircling.

8. The pre-stressed pile as claimed in any one of claims 1 to 4, wherein the main reinforcing bars are a main reinforcing bar structure in which the main reinforcing bars are connected by connecting nuts.

9. The pre-stressed pile of any one of claims 1 to 4, wherein a rotary spraying powder-spraying pile, a powder spraying or stirring pile is arranged on a modified soft soil layer foundation comprising silt, mucky soil, flow plastic, soft plastic or plastic cohesive soil, plain filling soil, silt, sandy soil, biological soil and gravelly soil, a construction hole or a direct drilling hole is arranged at the pile core of the rotary spraying powder-spraying pile or the stirring pile or the lap joint of the pile, a main reinforcing steel bar rib is arranged in the construction hole, cement mortar is injected into the pile by using a reinforcing steel bar cage as a framework, or concrete is poured into a composite pre-stressed pile or a bearing pile of a pile body; the main reinforcements of the reinforcement cage framework and the pile body of the prestressed pile are pre-tensioned or post-tensioned prestressed reinforcements.

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