Construction Method and Device for Execution of a Cast In-Situ Pile with Multiple Diameters Decreasing with Depth

Abstract

This invention is detailing a construction method for a cast in-situ pile having an upper section with a larger diameter and at least one subsequent section with a smaller diameter, and a drilling device equipped with continuous flights which allows the construction of one pile having multiple diameters using the innovative construction method in a single continuous drilling phase while each drilling tool is penetrating through the soil in one pass.

The drilling tool according to the invention has a central hollow space that allows accommodation through it of at least one another smaller diameter drilling tool that can drill continuously and can be coupled by means of a coupling-decoupling device in a specific manner to the other drilling tool in order to act as a fixed assembly, at any given position in relation to the smaller drilling tool length and rotating position.

Claims

1. A construction method for a cast in-situ pile having an upper section and at least one lower section, the upper section having a diameter larger than a diameter of the lower section, the method comprising: inserting of a second drilling tool through a first drilling tool, wherein (1) the first drilling tool has a first diameter and comprises a first hollow stem large enough to accommodate the second drilling tool, a cutting edge level disposed at or near an end of the first hollow stem, (2) the second drilling tool has a second diameter and comprises a second hollow stem, a tip disposed at or near an end of the second hollow stem, and a nozzle disposed at or near the tip, and (3) wherein the first diameter is larger than the second diameter; coupling of the first drilling tool to the second drilling tool, in a predetermined position along a length of the second drilling tool, by use of a coupling-decoupling device to form an assembly; inserting the assembly into ground comprising soil using a piling rig until the cutting edge level of the first drilling tool reaches a predetermined depth for a corresponding length of the pile upper section; decoupling of the first drilling tool from the second drilling tool, by use of the coupling-decoupling device to disconnect the assembly; further inserting the second drilling tool into the ground until the tip reaches a predetermined depth for the corresponding at least one lower section of the pile or until insertion is no longer possible due to soil layer stiffness (refusal criteria); pumping concrete, or grout, or mortar through the hollow stem of the second drilling tool and out the nozzle, while retracting the second drilling tool in such a way that displaced soil is immediately replaced by the concrete or grout or mortar and, until the tip of the second drilling tool reached the cutting edge level of the first drilling tool to form one of the at least one lower sections of the pile; coupling the first drilling tool to the second drilling tool, by use of the coupling-decoupling device to reconnect the assembly; pumping concrete, or grout, or mortar through the hollow stem of the second drilling tool and out the nozzle while retracting the assembly in such a way that displaced soil is immediately replaced by the concrete or grout or mortar and until the tip or nozzle reaches a predetermined design level to form the upper section of the pile; further retracting the assembly until complete extraction from the ground or above a working platform.

2. The construction method according to claim 1 wherein the second drilling tool is a continuous flight auger optionally comprising a starting segment with auger flights and extending fenders or ribs; wherein the inserting step comprises pushing and rotating the continuous flight auger into the ground.

3. A drilling device with continuous flights for execution of a cast in-situ pile into ground, the pile having a first section having a first diameter and at least one other section disposed below the first section and having a reduced diameter that is smaller than the first diameter, the drilling device comprising a first drilling tool, a second drilling tool, and a coupling-decoupling device; wherein the first drilling tool comprises an outer diameter that corresponds to the first diameter, and a central continuous hollow space which allows insertion of at least the second drilling tool; wherein the second drilling tool comprises an outer diameter that corresponds to the at least one other section of the pile having a reduced diameter; and wherein the coupling-decoupling device allows the first drilling tool to be fastened to the second drilling tool.

4. The drilling device with continuous flights according to claim 3 wherein the first drilling tool further comprises a central spacer having a tubular shape disposed within the hollow space to act as a centering device for the second drilling tool within the hollow space and to allow soil excavated by the second drilling tool to be transported upwards.

5. The drilling device with continuous flights according to claim 4, wherein the outer diameter of the second drilling tool may vary within predetermined boundaries and wherein the central spacer is configured to accommodate the varying outer diameter of the second drilling tool.

6. (canceled)

7. The drilling device with continuous flights according to claim 4 wherein the coupling-decoupling device allows the first drilling tool to be fastened to the second drilling tool in any position over the length of the second drilling tool.

8. The drilling device with continuous flights according to claim 4 wherein the drilling device further comprises a gliding system; wherein the first drilling tool comprises a flange fixed onto an upper portion of the first drilling too; wherein the coupling-decoupling device comprises a mandrel having a tubular shape or a clamping profiled shape, an array of metal wedges, a driving system acting on the array of metallic wedges by hydraulic or mechanical or electro-mechanical force that drives one or more blocking pads to fasten onto the second drilling tool; and wherein the one or more blocking pads are configured to slide through the gliding system over the flange.

9. The drilling device with continuous flights according to claim 8 wherein the coupling-decoupling device further comprises mobile flange segments that are fixed to each of the one or more blocking pads; wherein the flange of the first drilling tool and the mobile flange segments comprise oval shaped holes through which fastening screws or other coupling devices may be inserted to allow translation of the one or more blocking pads so that the one or more blocking pads can fasten or unfasten onto the second drilling tool and transmit torque and push or pull force to the first drilling tool.

10. The drilling device with continuous flights according to claim 8 wherein the one or more blocking pads comprise a blocking profile having indents or ribs on a side towards the second drilling tool.

11. The drilling device with continuous flights according to claim 10 wherein the second drilling tool further comprises a profile that corresponds to and is configured to engage with the blocking profiles of the one or more blocking pads.

12. The drilling device with continuous flights according to claim 4 wherein the coupling-decoupling device is configured to lock and transmit when coupled only the torque force during drilling phase into the ground of the first drilling tool without transmitting push or pull force, so that the second drilling tool can rotate together with the first drilling tool without compacting or loosening a surrounding soil beneath the first drilling tool while lifting too much soil through its flights due to smaller penetration rate of the largo first drilling tool; and wherein the coupling-decoupling device is further configured to be operated to fasten the first drilling tool to the second drilling tool (1) at any time and position when rotational assembly of the first and second drilling tools is required and (2) when the drilling device is being retracted from the ground; and wherein the coupling-decoupling device is further configured to operate to unfasten the first drilling tool from the second drilling tool while the second drilling tool is being retracting into the first drilling tool.

13. The drilling device with continuous flights according to claim 4 wherein the coupling-decoupling device comprises a geared transmission that allows the drilling device to rotate the first drilling tool at a different speed rate compared to a rotation of the second drilling tool when the first and second drilling tools are coupled together and wherein the rotation of the first drilling tool can be in a same direction or an opposite direction as the rotation of the second drilling tool.

14. The construction method according to claim 1, wherein the second drilling tool is a drilling rod with a densifying barrel body optionally comprising a starting segment with auger flights and extending fenders or ribs that allow the pile body to have threaded-like shape; and wherein the inserting step comprises pushing and rotating the drilling rod with the densifying barrel body into the soil to displace the soil sideways and densify surrounding area.

15. The construction method according to claim 1, wherein the second drilling tool is a drilling rod with a densifying barrel body optionally comprising a starting segment with auger flights; and wherein the inserting step comprises pushing and rotating the drilling rod with the densifying barrel body into the soil to displace the soil sideways and densify surrounding area.

Description

[0041] The invention is described below, with reference to following figures:

[0042] FIG. 1—Schematic representation of the construction method of cast in-situ piles with diameters decreasing in depth, by a continuous single phase process consisting in a single insertion into the ground of each drilling tool needed to construct the pile;

[0043] FIG. 2—Schematic representation of the concreting process for cast in-situ piles with diameters decreasing in depth;

[0044] FIG. 3—Example of axonometric view of the large diameter drilling tool connected to a smaller diameter continuous flight auger;

[0045] FIG. 4—Example of axonometric view of the large diameter drilling tool connected to a smaller diameter continuous flight auger, with exemplification of a centering spacer between the large diameter tool and the smaller diameter continuous flight auger which can have a diameter smaller than diameter of the hollow stem of the large diameter drilling tool;

[0046] FIG. 5—Example of cross section of the large diameter drilling tool, when the diameter of the continuous flight auger is same with diameter of the hollow stem of the large diameter drilling tool;

[0047] FIG. 6—Example of cross section of the large diameter drilling tool, when the diameter of the continuous flight auger is smaller than diameter of the hollow stem of the large diameter drilling tool;

[0048] FIG. 7—Example of axonometric view of the large diameter drilling tool and of the spacer between the continuous flight auger with smaller diameter and the large diameter drilling tool, with exemplification of blocking pads corresponding to continuous flight auger with a smaller diameter than of the hollow stem of large diameter drilling tool;

[0049] FIG. 8—Example of axonometric view of the continuous flight auger with smaller diameter, with exemplification of blocking pads, of spacer between the continuous flight auger with smaller diameter and the large diameter drilling tool, and of the spacers used for the blocking pads of the coupling-decoupling device;

[0050] FIG. 9—Example of axonometric view of the large diameter drilling tool, with exemplification of shape of the spacer used on the upper segment of the large diameter drilling tool;

[0051] FIG. 10—Example of axonometric view of the tip of the large diameter drilling tool, with exemplification of teeth position on the circular spacer placed between the large diameter drilling tool and smaller diameter drilling tool;

[0052] FIG. 11—Example of front view of the tip of the large diameter drilling tool, with exemplification of teeth position or other means to advance through excavated material.

[0053] FIG. 12—Example of axonometric view of the tip of the large diameter drilling tool, with exemplification of spacer shape on its lower part;

[0054] FIG. 13—Example of axonometric view of the tip of the large diameter drilling tool, with exemplification of teeth position;

[0055] FIG. 14—Example of axonometric view of the coupling-decoupling device, with the jaws acting on the blocking pads by directional movement in vertical plan;

[0056] FIG. 15—Example of shape of the blocking pads, with an example of shape of clamping wedges which are placed parallel to the movement direction of the blocking pads;

[0057] FIG. 16—Example of shape of the blocking pads, with example of multiple clamping wedges having a tangential movement direction to the transversal circular cross section of the smaller diameter drilling tool;

[0058] FIG. 17—Example of shape of the blocking pads, with example of shape of clamping wedges having a tangential movement direction to the transversal circular cross section of the smaller diameter drilling tool;

[0059] FIG. 18—Example of cross section through the coupling-decoupling device fixed onto the larger diameter drilling tool as per FIG. 3;

[0060] FIG. 19—Example of cross section through the blocking pads depicted in FIG. 15;

[0061] FIG. 18—Example of cross section through the coupling-decoupling device fixed onto smaller diameter drilling tool, as per FIG. 10;

[0062] FIG. 21—Example of position and shape of interlocking strips blocking movement between coupling-decoupling device and smaller diameter drilling tool;

[0063] FIG. 22—Example of position and shape of interlocking indents on the blocking pads, blocking movement between coupling-decoupling device and smaller diameter drilling tool;

[0064] FIG. 23—Example of position and shape of interlocking indents on the smaller diameter drilling tool flights;

[0065] Numerical references marked in the above listed figures are corresponding to following technical items: [0066] 1. Large diameter drilling tool; [0067] 2. Large diameter drilled shaft; [0068] 3. Hollow stem inside the large diameter drilling tool; [0069] 4. Continuous flight auger or smaller diameter drilling tool; [0070] 5. Coupling-decoupling device; [0071] 6. Blocking pads used to fix the large diameter drilling tool onto the smaller diameter drilling tool; [0072] 7. Driving mandrel for the blocking pads, having tubular shape or clamping profiled shape; [0073] 8. Piling rig; [0074] 9. Foundation ground; [0075] 10. Pile toe; [0076] 11. Concrete hose connected to concrete pump; [0077] 12. Concrete nozzle for evacuation of concrete through the hollow stem inside the smaller diameter drilling tool; [0078] 13. Pile segment having a smaller diameter; [0079] 14. Pile segment having a larger diameter; [0080] 15. Kelly extension commonly used for construction of piles by CFA method or densification method; [0081] 16. Clamping wedges used in the coupling-decoupling device used to fix connection of the larger diameter drilling tool onto the smaller diameter drilling tool; (assembly of mandrel exterior and blocking pads); [0082] 17. Locking rugged surfaces onto inner side of the blocking pads, such as grooves, indentations, striations or ribs; [0083] 18. Complementary interlocking rugged surfaces onto the smaller diameter drilling tool, to snugly fit the rugged surfaces onto inner side of the blocking pads, such as grooves, indentations, striations or ribs; [0084] 19. Spacers for the blocking pads to compensate the difference in the diameter of the smaller diameter drilling tool and hollow stem space 3 inside the larger diameter drilling tool; [0085] 20. Excavated material from drilled shaft; [0086] 21. Concrete pumped through the nozzle of the continuous flight auger; [0087] 22. Working platform; [0088] 23. Spacer used to compensate and center a smaller diameter drilling tool inside a larger hollow stem of the larger diameter drilling tool; [0089] 24. Drilling teeth or other profiled shapes placed on the bottom of the centaring spacer 23 having the scope of transferring drilled soil to the flights of the augers; [0090] 25. Drilling teeth or other profiled shapes placed on the bottom of the large diameter drilling tool having the scope of transferring drilled soil to the flights of the augers; [0091] 26. Device, driven by mechanical, electro-mechanical, hydraulic or electro-hydraulic means, designed to control movement and clamping force of the blocking pads (16) in such way that mandrel (7) will control coupling or decoupling of the larger diameter drilling tool (1) to the smaller diameter drilling tool (4); [0092] 27. Means of controlling directional sliding of blocking pads towards or outwards the larger diameter drilling tool (1); [0093] 28. Bottom tip of the larger diameter drilling tool; [0094] 29. Bottom tip of the smaller diameter drilling tool; [0095] 30. Fixed flange onto the upper part of the larger diameter drilling tool (1).

[0096] According to this invention, the drilling assembly depicted in FIG. 2 and following FIGS. 3 to 13 is consisting of a large diameter drilling tool (1) with exterior shape similar to a continuous flight auger, having the outer diameter equal to the diameter of the large diameter drilled shaft (2), having a central hollow stem (3) where another smaller diameter drilling tool (4) can translate and rotate independently, having a coupling-decoupling device (5) fixed to it.

[0097] The smaller diameter continuous drilling tool (4) can be a commonly used continuous flight auger (CFA) or a tube having a densification barrel or a tube having a regular flight auger of a certain length or a flight auger of a certain length and special shape of the flights with interlocking strips or grooves.

[0098] The coupling-decoupling device (5) can have various technical principles, in one of the variants being made as an assembly with metallic wedges (16), so that by hydraulic jacks or mechanic or electro-mechanic gears these can be pushed with significant force that will ensure enclenching of the blocking pads (6) onto the smaller diameter tool (4) in such way that the connection is fixed and impede movement between the parts and can transfer the push force and torque transmitted by the drilling rig to the smaller diameter tool which, in its turn through the coupling procedure, will transmit these loads to the large diameter tool (1) so that it can penetrate the foundation ground (9).

[0099] In FIGS. 1 and 2 can be seen an example of this invention construction where the smaller diameter drilling tool (4) is a regular continuous flight auger used in CFA procedure. In one variant of this invention construction, the coupling-decoupling device (5) is consisting of one external mandrel shell (7) which might be of tubular shape or having a clamping like shape, able to interact with one or more blocking pads (6), an array of metallic wedges (16), a coupling system (26) actioned by hydraulic, mechanical or electro-mechanical energy and gliders (26) to ensure directional sliding of the blocking pads (6) against the larger diameter drilling tool (1).

[0100] The blocking pads (6) ensure a snugly fixed coupling between the larger diameter drilling tool (1) with the smaller diameter drilling tool (4). The mandrel (7) will interact with the blocking pads (6) by use of a mechanical, electro-mechanical or hydraulic system which is acting on the metallic wedges (16) so that the mandrel (7) is pushing or retracting the blocking pads (6) so that the coupling or decoupling of the larger diameter drilling tool (1) to the smaller diameter drilling tool (4) is made. During drilling process, the large diameter section (2) of a shaft is made when the larger diameter drilling tool (1) is rotated together with the smaller diameter drilling tool (4), connection of the two being fixed by the blocking pads (6) of the coupling-decoupling device (5) which are pushing towards the smaller diameter drilling tool (4) so that friction force developed in between the contact surfaces overcomes the torque amount which is driving the rotational movement of the latter. The smaller diameter drilling tool is pushed downwards and rotated by the hydraulic head of the drilling rig (8). To enhance the friction forces developed by fastening of the blocking pads (6) onto the smaller diameter drilling tool (4), the inner side of the pads (6), as a construction variant, might be particularly profiled (17), with grooves, indentations, striations or ribs. Similarly the smaller diameter drilling tool (4) can have complementary profiles (18), such as grooves, indentations, striations or ribs, made over the contact area between it and the blocking pads (6). This way the connection between the drilling tools is improved and transmission of push force, retraction force or torque to the larger diameter drilling tool (1) is more reliable.

[0101] In one construction example, the gliding system (27) that allows fastening or unfastening of the blocking pads (6) onto the smaller diameter drilling tool (4) is made by an array of flange segments, each welded to the lower side of one pad, connected to a fixed flange (30) which is locked to the upper part of the larger diameter drilling tool (1). The connection in this example allows gliding of the flange segment over the fixed flange in a radial direction with bolts or screws inserted in oval openings. Locking or unlocking of movement between the parts is achieved by fastening or unfastening the pads (6) onto the smaller diameter drilling tool (4).

[0102] In one construction example, the coupling-decoupling device (5) is locking in a way that allows only the torque to be transmitted to the larger diameter drilling tool during execution of the large diameter segment of the pile shaft, without transmitting push force. In this way the smaller drilling tool (4) can rotate without penetration and excavated soil will not be compressed or transported excessively from the smaller diameter due to different rates of penetration in between the drilling tools. The coupling-decoupling device (5) can be triggered whenever desired to lock rotational movement between larger diameter drilling tool (1) and smaller diameter drilling tool (4), latest stage being when the drilling tip (29) of the smaller diameter drilling tool (4) is retracted to the same level as the cutting edge of the larger diameter drilling tool (1), and lastly the complete drilling assembly is extracted from the borehole.

[0103] In one construction example, the coupling-decoupling device (5) has an embedded geared system that allows the larger diameter drilling tool (1) to be driven at a different rotational speed and rotating in same direction or otherwise compared to the rotational speed and rotation direction of the smaller diameter drilling tool (4). This will allow a faster penetration rate of the assembly made by the locked drilling tools (1) and (4) with a smaller amount of energy, in different kinds of soils.

[0104] After the larger diameter drilling tool (1) has reached its predetermined depth in the foundation ground (9) where the pile shaft (2) is made, the tool (1) is decoupled from tool (4) by unlocking the coupling-decoupling device (5) and the movement of tool (4) remains independent from tool (4) while tool (4) remains fixed into the ground. Subsequently the drilling process continues following the general rules of drilling by continuous flight auger method or densification method, where smaller diameter drilling tool (4) is further penetrating the foundation ground (9), driven by the drilling rig (8) until the pile toe level (10) is reached. Then starts concrete pumping through the hose (11) coming from concrete pump, and through the hollow stem of the continuous flight auger drilling tool (4), while simultaneously retracting the auger (4) so that displaced soil is replaced by fresh concrete poured inside the pile shaft through the nozzle (12) positioned at the tip of the auger (4). Extraction of the smaller diameter drilling tool (4) can be accompanied by a rotational movement of the tool (4). The process continues until the tip of the drilling tool (4) reaches the cutting edge (28) level of the larger diameter drilling tool (1) which was left previously at a chosen depth for the construction of the pile shaft (2). Hence concludes the concreting operation of the smaller diameter section (13) of the pile. Next, unlike any other method known before, by operating the coupling-decoupling device (5) so that movement is blocked between the drilling tools and can allow the complete fixed assembly composed of larger diameter drilling tool (1), smaller diameter drilling tool (4) and coupling-decoupling device (5) to be extracted from the borehole until a predetermined level is reached, while continuing the concreting procedure as described above, completing the upper segment (14) with a larger diameter of the pile body. Next, according to design calculations, the pile with decreasing diameters in depth can be reinforced with a reinforcement cage capable to withstand necessary amount of loads that the pile is intended to transfer from the superstructure to the ground. Reinforcement can be made of various raw materials such as steel or other metals, carbon or glass fibers, or polymers, or any other. Reinforcement can be shaped as arrays or cages of single bars or clusters of bars, cables or thrust, profiled shapes, or dispersed fibers, or any other shape. The reinforcement can be over the entire length of the pile or partial, either to each or any of the pile sections, in any ratio. Reinforcement can be tensioned before or after the pile was finished, or not tensioned.

[0105] The piles made by use of this invention can have empty spaces, connectors to the superstructure elements, precast embedded parts, or embedded parts of any sort, made of any material. To improve settlement behavior of pile and its bearing capacity and inner strength, the piles made using this invention can be grout injected in the base and/or on the shaft. The piles made using this invention can also embed coupling rods to poles or otherwise, as depicted in document RO132489A2, or with a cavitation on the upper side as per patent pending a2017/00041.

[0106] In another example of this invention, the smaller diameter drilling tool (4) is a drilling rod equipped with a densification barrel which can have on its bottom an auger of a certain length. The method described with this invention is applied in the same way for this drilling tool, only that the penetration into the ground of the drilling tool (4) is made following the rules of densification displacement techniques generally available for execution of piles.

[0107] Advantage for this variant is that by densification of the surrounding soil the pile has a bigger load capacity and improved stiffness, supporting higher axial and horizontal loads as well as a higher bending capacity. Limitations of this method are same as for known methods to install cast in-situ piles using densification process, respectively diameters are limited usually to approximately 700 mm, the maximum value being dependent on the soil state of compaction that might require a higher torque and/or pushing force than is possible to attain with existing technology for pile drilling rigs.

[0108] In another example of this invention, the smaller diameter drilling tool (4) is a drilling rod equipped with a densification barrel which can have on its bottom an auger with external fenders or ribs that can imprint notches or grooves into the pile body during concreting phase. The execution method of this invention is applied as described above, except that the penetration into the ground of the drilling tool (4) is made following the rules of densification displacement techniques generally available for execution of screwed piles.

[0109] Advantage for this variant is that by densification of the surrounding soil the pile and the body having a screw-like shape has a bigger load capacity and improved stiffness, supporting higher axial and horizontal loads as well as a higher bending capacity. Limitations of this method are same as for known methods to install cast in-situ piles using densification process, respectively diameters are limited usually to approximately 700 mm, the maximum value being dependent on the soil state of compaction that might require a higher torque and/or pushing force than is possible to attain with existing technology for pile drilling rigs.

[0110] In another example of this invention, the larger diameter drilling tool (1) is accommodating in its hollow center (3) a second large diameter drilling tool (1) that according to this invention is a “auger in auger” drilling assembly, which in its turn can be connected with a smaller diameter drilling tool (4).

[0111] This “auger in auger” assembly allows construction of a pile having three different diameters, decreasing along pile length and depth, the drilling tools being able to be coupled or decoupled independently one to another.

[0112] The construction method according to this invention is applied in a similar way as described above, using firstly the assembly “auger in auger” to drill the biggest and upper diameter of the pile, then continuing only with the middle drilling tool type (1) connected to the tool (4) to make the intermediate diameter shaft and lastly continuing only with the smaller diameter drilling tool (4) to drill the last section of the pile with smallest diameter.