Micropile foundation matrix
The disclosure describes, in part, apparatuses and methods for installing structures (e.g., foundations, footings, anchors, abutments, etc.) at work sites, such as difficult-access work sites. In some instances, a rotating drill assembly is assembled over a target location in order to excavate a radial array of batter-angled shafts associated with the target location in preparation for the installation of a radial array of micropiles. An operator utilizes the rotating drill in combination with a foundation pile schedule/decision matrix to design and install the radial array of batter-angled micropiles. This disclosure also describes techniques for designing, fabricating and installing structural caps to be coupled to the installed radial array batter angled micropiles. These structural caps are lightweight and, thus, more portable to difficult-access sites where they are coupled to the micropiles forming a foundation for structure to be installed at the difficult-access site.
1. A method for installing a pile group at a site, the method comprising:
at a time of installation of a first pile of the pile group at the site,
positioning a drill assembly to the first pile of the pile group at the site;
performing, using the drill assembly, an in-situ penetration test to determine a geotechnical characteristic of a stratum at a point of characterization in the first pile location of the pile group, wherein the point of characterization comprises a distance in the ground below a pile cap excavation at the site;
at least partly subsequent to the performing of the in-situ penetration test, determining a quantity of piles to include in the pile group based on the determined geotechnical characteristic of the stratum at the point of characterization in the first pile location, wherein the determining of the quantity of piles at the time of installation of the first pile of the pile group at the site comprises mapping, via a predefined mapping, the determined geotechnical characteristic of the stratum to one of multiple defined soil conditions, and wherein the determined quantity of piles is based at least in part on the one defined soil condition; and
initiating, using the drill assembly, installation of the determined quantity of piles.
2. The method as recited in claim 1 , wherein the in-situ penetration tests comprise one or more of a Standard Penetration Test (SPT) or a Cone Penetration Test (CPT).
3. The method as recited in claim 1 , wherein the piles comprise micropiles, and wherein the initiating of the installation comprises initiating installation of a radial array of micropiles.
4. The method as recited in claim 1 , wherein the determined quantity of piles is used as a quantity for each additional pile group at the site.
5. The method as recited in claim 1 , further comprising repeating the performing of the in-situ penetration test, the determining of a quantity of piles and the initiating of the installation for each additional pile group at the site.
6. The method as recited in claim 1 , wherein the site comprises one of multiple sites, and wherein the determined quantity of piles is used as a quantity for each additional pile group for at least one other site.
7. The method as recited in claim 1 , wherein the distance in the ground below the pile cap excavation at the site is between one foot and six feet.
8. The method as recited in claim 1 , wherein the multiple defined soil conditions comprise loose, medium dense and rock.
9. The method as recited in claim 1 , further comprising:
performing an in-situ penetration test to determine a geotechnical characteristic at each of one or more intervals past the point of characterization in the first pile location; and
determining a minimum length of casing embedment and a minimum bond length for the determined quantity of piles based on a determined geotechnical characteristic at each of the one or more intervals.
10. The method as recited in claim 9 , wherein the pile group comprises a first of multiple pile groups at the site, and further comprising:
during the installation of a pile at a pile location at the first pile group or another pile group, determining whether a geotechnical characteristic of a stratum at the point of characterization in the pile location differs by more than a predefined threshold amount from the determined geotechnical characteristic of the stratum of the first pile location; and
at least partly in response to determining that the geotechnical characteristic of the stratum at the point of characterization in the pile location does not differ by more than the predefined threshold amount, continuing to install the determined quantity of piles each having the determined minimum casing embedment and minimum bond length at each pile group location of the site; and
at least partly in response to determining that the geotechnical characteristic of the stratum at the point of characterization in the pile location does differ by more than the predefined threshold amount, performing a new in-situ penetration test at the point of characterization in the pile location and a new in-situ penetration test at each of one or more intervals past the point of characterization.
11. The method as recited in claim 9 , wherein each of the intervals past the point of characterization at the first pile location is between two feet and ten feet past the point of characterization.
12. The method as recited in claim 11 , wherein the performing of the in-situ penetration test at the one or more intervals continues until bedrock is encountered or until a total depth of the first pile location is reached.
13. The method as recited in claim 1 , further comprising:
before the performing of the in-situ penetration test at the point of characterization in the first pile location, determining that: (i) a deficiency of geotechnical data available for the site or for the first pile location exists, or (ii) previously-compiled geotechnical data differs from the geotechnical characteristic of the stratum encountered at the point of characterization in the first pile location by more than a predefined threshold amount, and wherein the performing of the in-situ penetration test at the point of characterization is based on the determining that the deficiency exists or that the previously-compiled geotechnical data differs from the geotechnical characteristic of the stratum encountered at the point of characterization in the first pile location by more than the predefined threshold amount.
14. A method for installing a group of structural members at a site, the method comprising:
at a time of installation of a first structural member of the group of structural members at the site,
performing an in-situ penetration test at a point of characterization in a first location for the first structural member of the group of structural members to determine a geotechnical characteristic of a stratum at the point of characterization, wherein the point of characterization comprises a distance in the ground below a pile cap excavation at the site;
at least partly subsequent to the performing of the in-situ penetration test, determining a quantity of structural members to include in the group of structural members based on the determined geotechnical characteristic at the point of characterization, wherein the determining of the quantity of structural members at the time of installation of the first structural member of the group of structural members at the site comprises mapping, via a foundation schedule, the determined geotechnical characteristic at the point of characterization to one of multiple defined soil conditions, and wherein the determined quantity of structural members is based at least in part on the one defined soil condition;
subsequent to the determining of the quantity of structural members, initiating installation of the determined quantity of structural members;
performing an in-situ penetration test at each of one or more intervals past the point of characterization to determine a geotechnical characteristic at each of the one or more intervals; and
determining a length for the determined quantity of structural members based on a determined characteristic at each of the one or more intervals.
15. The method as recited in claim 14 , wherein the in-situ penetration tests comprise one or more of a standard penetration test (SPT) or a cone penetration test (CPT).
16. The method as recited in claim 14 , wherein the structural members comprise rock anchors or piles.
17. The method as recited in claim 14 , wherein the structural members comprise micropiles, and wherein the initiating of the installation comprises initiating installation of a radial array of micropiles.
18. The method as recited in claim 14 , wherein the structural members collectively form at least a portion of a foundation for a tower.
19. The method as recited in claim 14 , wherein the structural members collectively form at least a portion of a first foundation of multiple foundations to receive a first leg of multiple legs of a lattice tower.
20. The method as recited in claim 14 , wherein the determining of the length for the determined quantity of structural members comprises determining a casing embedment length of the structural members based on the determined characteristic at each of the one or more intervals.
21. The method as recited in claim 14 , wherein the determining of the length for the quantity of structural members comprises determining a bond length of the structural members based on the determined characteristic at each of the one or more intervals.
22. The method as recited in claim 14 , wherein the determined quantity of structural members is used as a quantity for each additional group of structural members at the site.
23. The method as recited in claim 14 , further comprising repeating the performing of the in-situ penetration test to determine a geotechnical characteristic, the determining of a quantity of structural members, the initiating of the installation, the performing of the in-situ penetration test at each of one or more intervals past the point of characterization and the determining of a length for the determined quantity of structural members for each additional group of structural members at the site.
24. The method as recited in claim 14 , wherein the site comprises one of multiple sites, and wherein the determined quantity of structural members is used as a quantity for each additional group of structural members for at least one other site.
25. The method as recited in claim 14 , wherein the distance in the ground below the pile cap excavation at the site is between one foot and six feet.
26. The method as recited in claim 14 , wherein the multiple defined soil conditions comprise loose, medium dense and rock.
27. The method as recited in claim 14 , wherein each of the intervals past the point of characterization is between two feet and ten feet past the point of characterization.
28. The method as recited in claim 14 , wherein the performing of the in-situ penetration test at the one or more intervals continues until bedrock is encountered or until a total depth of the group of structural members is reached.
29. The method as recited in claim 14 , further comprising:
before the performing of the in-situ penetration test at the point of characterization, determining that: (i) a deficiency of geotechnical data available for the site or for the group of structural members exists, or (ii) previously-compiled geotechnical data differs from the geotechnical characteristic of the stratum encountered at the point of characterization in the first location for the first structural member by more than a predefined threshold amount, and wherein the performing of the in-situ penetration test at the point of characterization is based on the determining that the deficiency exists or that the previously-compiled geotechnical data differs from the geotechnical characteristic of the stratum encountered at the point of characterization in the first location for the first structural member by more than the predefined threshold amount.