March/April 2021 - 19

Excavation for station
stairways, ADA elevators

As excavation proceeded, bracing was
installed at the level of the subway roof to
provide lateral support. The bracing struts
were preloaded using flat jacks to minimize
potential lateral displacement of the sheet
pile walls and consequent settlements.
Once excavation was completed to final
subgrade, the entrance structures,
including stairways and shafts for ADA
elevators, were constructed of reinforced
concrete. Portions of the side walls of the
existing subway were removed and
reframed to connect the new entrances to
the station platforms on both sides. The
bracing was removed as construction
proceeded from the bottom up.

Avenue B Electrical Substation

At the top of the existing subway structure, concrete
button piers were installed to close off the excavation on the
street side and to support the deck beams. The layout of the
concrete piers presented significant challenges during design
due to the presence of various utilities running along the roof
that needed to be maintained and protected, such as a 36 in
(914 mm) water main along the tunnel's south side.

The excavation support system used for
construction of the Avenue B electrical
substation concept resembled that for the
new station entrances. Steel sheet piling
was installed around the perimeter of the excavation area
using the press-in method, with approximately 10 ft (3 m) of
embedment below final excavation level. Jet grout closures
were also used at utility locations and where required for
closure against the existing subway tunnel.
The jet grout blanket, installed prior to excavation start, was
typically 6 ft (1.8 m) thick, except at the east end where a 9 ft

Developing electrical substation near Avenue B intersection
DEEP FOUNDATIONS * MAR/APR 2021 * 19



March/April 2021

Table of Contents for the Digital Edition of March/April 2021

TOC
March/April 2021 - Intro
March/April 2021 - 1
March/April 2021 - 2
March/April 2021 - TOC
March/April 2021 - 4
March/April 2021 - 5
March/April 2021 - 6
March/April 2021 - 7
March/April 2021 - 8
March/April 2021 - 9
March/April 2021 - 10
March/April 2021 - 11
March/April 2021 - 12
March/April 2021 - 13
March/April 2021 - 14
March/April 2021 - 15
March/April 2021 - 16
March/April 2021 - 17
March/April 2021 - 18
March/April 2021 - 19
March/April 2021 - 20
March/April 2021 - 21
March/April 2021 - 22
March/April 2021 - 23
March/April 2021 - 24
March/April 2021 - 25
March/April 2021 - 26
March/April 2021 - 27
March/April 2021 - 28
March/April 2021 - 29
March/April 2021 - 30
March/April 2021 - 31
March/April 2021 - 32
March/April 2021 - 33
March/April 2021 - 34
March/April 2021 - 35
March/April 2021 - 36
March/April 2021 - 37
March/April 2021 - 38
March/April 2021 - 39
March/April 2021 - 40
March/April 2021 - 41
March/April 2021 - 42
March/April 2021 - 43
March/April 2021 - 44
March/April 2021 - 45
March/April 2021 - 46
March/April 2021 - 47
March/April 2021 - 48
March/April 2021 - 49
March/April 2021 - 50
March/April 2021 - 51
March/April 2021 - 52
March/April 2021 - 53
March/April 2021 - 54
March/April 2021 - 55
March/April 2021 - 56
March/April 2021 - 57
March/April 2021 - 58
March/April 2021 - 59
March/April 2021 - 60
March/April 2021 - 61
March/April 2021 - 62
March/April 2021 - 63
March/April 2021 - 64
March/April 2021 - 65
March/April 2021 - 66
March/April 2021 - 67
March/April 2021 - 68
March/April 2021 - 69
March/April 2021 - 70
March/April 2021 - 71
March/April 2021 - 72
March/April 2021 - 73
March/April 2021 - 74
March/April 2021 - 75
March/April 2021 - 76
March/April 2021 - 77
March/April 2021 - 78
March/April 2021 - 79
March/April 2021 - 80
March/April 2021 - 81
March/April 2021 - 82
March/April 2021 - 83
March/April 2021 - 84
March/April 2021 - 85
March/April 2021 - 86
March/April 2021 - 87
March/April 2021 - 88
March/April 2021 - 89
March/April 2021 - 90
March/April 2021 - 91
March/April 2021 - 92
March/April 2021 - 93
March/April 2021 - 94
March/April 2021 - 95
March/April 2021 - 96
March/April 2021 - 97
March/April 2021 - 98
March/April 2021 - 99
March/April 2021 - 100
March/April 2021 - 101
March/April 2021 - 102
March/April 2021 - 103
March/April 2021 - 104
March/April 2021 - 105
March/April 2021 - 106
March/April 2021 - 107
March/April 2021 - 108
March/April 2021 - 109
March/April 2021 - 110
March/April 2021 - 111
March/April 2021 - 112
March/April 2021 - 113
March/April 2021 - 114
March/April 2021 - 115
March/April 2021 - 116
March/April 2021 - 117
March/April 2021 - 118
March/April 2021 - 119
March/April 2021 - 120
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/march-april-2024
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/january-february-2024
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/november-december-2023
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/september-october-2023
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/july-august-2023
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/may-june-2023
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/Jan-feb-2021_nxtbook
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/july-august-2021
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/march-april-2023
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/january-february-2023
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/november-december-2022
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/september-october-2022
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/july-august-2022
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/may-june-2022
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/march-april-2022
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/january-february-2022
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/november-december-2021
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/sept-oct-2021
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/july-aug-2021
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/may-june-2021
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/march-april-2021
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/january-february-2021
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/november-december-2020
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/September-October-2020
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/may-june-2020
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/march-april-2020
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/january-february-2020
https://www.nxtbook.com/dfi/DEEP-FOUNDATIONS/july-august-2020
https://www.nxtbookmedia.com