METHOD AND LOADING MODULE TO MECHANICALLY INCREASE PILE/DRILLED SHAFT END BEARING STIFFNESS

• US 20190071834A1
• Filed: 02/21/2017
• Published: 03/07/2019
• Est. Priority Date: 02/22/2016
• Status: Active Grant

• Current Assignee: Board of Regents Nevada System of Higher Education (State of Nevada)
• Original Assignee: Reno Nevada, Board of Regents Nevada System of Higher Education (State of Nevada)
• Inventors: ELFASS, Sherif A., NORRIS, Gary M.
• Granted Patent: US 10,407,859 B2
• Time in Patent Office: Days
• CPC Class Codes: E02D 15/04 Placing concrete in mould-pipes, pile tubes, bore-holes or narrow shafts
• CPC Class Codes: E02D 5/38 making by use of mould-pipes or other moulds
• CPC Class Codes: E02D 5/665 for making piles

Abstract

Disclosed herein are a module, system and technique to enhance end bearing stiffness of pile/drilled shafts. In particular, methods, systems and loading modules which account for tip resistance in overall pile/shaft capacity are provided which increase the stiffness of the bearing soil. The techniques utilize a mechanical system to preload the soil under the shaft tip, thus allowing the users to confidently account for the gained resistance at an acceptable level of movement. Each shaft/pile is preloaded during construction to verify its load carrying capability.

Claims

1. A method for increasing pile/drilled shaft end bearing stiffness, comprising:

drilling a hole having a diameter of the pile/drilled shaft to a desired depth;

positioning at least one loading rod tube, at least one cement slurry tube and a loading module in the hole, wherein the loading module comprises a base plate with a lip and at least one seating opening;

positioning at least one loading rod down the loading rod tube so that it is seated within the at least one seating opening of the base plate;

securing a reaction frame to a pile/shaft body;

compressing the at least one loading rod so that it pushes the base plate into a bearing soil and creates a void between the base plate and bottom soil;

filling the void between the base plate and bottom soil with cement slurry;

removing the at least one loading rod; and

filling the loading tube with a cement slurry.

2. The method of claim 1, further comprising positioning one or more anchor rods around the pile/shaft body to allow for securing the reaction frame to the pile/shaft body.

3. The method of claim 1, wherein compressing the at least one loading rod comprises utilizing a hydraulic jack to compress the loading rod.

4. The method of claim 1, wherein the base plate comprises three seating openings.

5. The method of claim 4, wherein three loading rods are used to push the base plate into bearing soil and create a void between the base plate and bottom soil.

6. The method of claim 1, wherein the loading module further comprises a porewater pressure dissipater.

7. The method of claim 6, wherein the porewater pressure dissipater comprises a cylindrical receptacle and uniform or nonuniform aggregate positioned within the receptacle and sealed by the base plate of the loading module.

8. A system for increasing pile/drilled shaft end bearing stiffness, comprising:

a loading module comprising a base plate with a lip and at least one seating opening;

one or more loading tubes for receiving one or more loading rods;

one or more access tubes to deliver a cement slurry; and

one or more anchoring rods.

9. The system of claim 8, further comprising a reaction frame.

10. The system of claim 8, further comprising one or more loading rods.

11. The system of claim 8, further comprising a hydraulic jack.

12. The system of claim 8, wherein the loading module further comprises a porewater pressure dissipater.

13. The system of claim 12, wherein the porewater pressure dissipater comprises a cylindrical receptacle filled with uniform aggregate.

14. The system of claim 12, wherein the porewater pressure dissipater comprises a cylindrical receptacle filled with nonuniform aggregate.