DFI Magazine September/October 2020 - 102
QA/QC aspects include field verification
of soil densification and/or load testing of RIs
to confirm design assumptions. Load testing
is often carried out on individual RIs, and
this is particularly suitable when RIs carry
concentrated loads. Load testing of largescale footings with multiple RIs is sometimes
needed to verify soil/RI response to loading.
Settlement monitoring during, and sometimes after, construction is recommended.
Stress Distribution
RIs and the surrounding soil will behave as
a composite system. Thus, a rational
representation of the soil-RI interaction is a
fundamental aspect of RI design. For
instance, when the distribution in load
between the RIs and the soil is evaluated
using a large-scale plate load test, the
distribution varies with footing pressure.
At lower footing pressures (and smaller
displacements), the RIs resist a higher
percentage of the load compared to higher
footing pressures and larger displacements.
In the case of RIs within an embankment,
vertical stresses from the overlying
embankment will cause settlement and
negative skin friction along the length of
the RIs (fig.2). As a result, the RIs will
behave like piles. It may seem intuitive that
the RIs beneath an embankment may be
considered to be in pure shear in a conventional limit equilibrium analysis; however,
consideration should be made for the fact
that the RIs will attract the embankment
stress and transfer that stress deeper into
the soil profile.
In addition, horizontal shear stresses
are present near the edges of embankments (fig. 3). The design of underlying RIs
should thus consider the shear and
bending resulting from the embankment
Figure 1. Large-scale plate test of load distributed between RIs and soil
shear stresses, as well as other potential
loading/stress conditions when more
complex design demands exists.
Liquefaction Mitigation
RIs can provide stiffened soil responses to
seismic loading. This effect is more
pronounced when the RIs are installed
using full soil-displacement methods that
do not remove soil from the ground.
Typically, the displacement of predominantly coarse-grained soils results in
densification of these soils surrounding the
installed RIs, consequently increasing their
resistance to seismic loading. The required
increase in resistance is determined by
analytical methods and is verified by
QA/QC activities that include performing
in situ tests before and after RI installation.
Verification of increase in soil density,
strength and modulus is typically needed
to ensure that design requirements are met.
In situ tests routinely performed include
the standard penetration test (SPT), cone
penetration test (CPT) and dilatometer test
(DMT), as well as shear wave velocity (Vs)
measurements.
Figure 2. Embankment stress distributions along RIs (close-up at right)
102 * DEEP FOUNDATIONS * SEPT/OCT 2020
A detailed case history of drilled
displacement rigid inclusions used for
liquefaction mitigation was presented in
the January/February 2019 edition of Deep
Foundations magazine.
Seismic Loading
RIs have limited lateral capacity and
stiffness because of their relative
slenderness and lack of - or limited -
reinforcement. As a result, they elicit brittle
behavior under lateral loading conditions.
In areas of moderate to high seismicity,
earthquake-induced lateral loading of RIs
is a significant design consideration.
Seismic loading of RIs results from a
combination of inertial loading due to
dynamic response of the superstructure
being supported, and kinematic loading
due to transient or permanent ground
deformation during an event. This loading
and deformation due to a seismic event will
impose bending moments throughout the
entire length of the element, which must be
incorporated into the RI design.
Vertical load (P) and overturning
moments (M) applied to a foundation by
seismic inertial loading must be incorporated into the vertical loading design of
the RIs (fig. 4). Shear loads (V) are resisted
by passive soil resistance against the foundation and through shear transfer to the
load transfer platform and to the soil and
RIs below it.
In addition to the inertial superstructure loading, the kinematic loading
due to transient or permanent soil
deformation is significant and must be
included in the structural evaluation of RI
elements. While the soil-structure
DFI Magazine September/October 2020
Table of Contents for the Digital Edition of DFI Magazine September/October 2020
CONTENTS
CONTENTS 2
DFI Magazine September/October 2020 - Intro
DFI Magazine September/October 2020 - 1
DFI Magazine September/October 2020 - 2
DFI Magazine September/October 2020 - CONTENTS
DFI Magazine September/October 2020 - 4
DFI Magazine September/October 2020 - CONTENTS 2
DFI Magazine September/October 2020 - 6
DFI Magazine September/October 2020 - 7
DFI Magazine September/October 2020 - 8
DFI Magazine September/October 2020 - 9
DFI Magazine September/October 2020 - 10
DFI Magazine September/October 2020 - 11
DFI Magazine September/October 2020 - 12
DFI Magazine September/October 2020 - 13
DFI Magazine September/October 2020 - 14
DFI Magazine September/October 2020 - 15
DFI Magazine September/October 2020 - 16
DFI Magazine September/October 2020 - 17
DFI Magazine September/October 2020 - 18
DFI Magazine September/October 2020 - 19
DFI Magazine September/October 2020 - 20
DFI Magazine September/October 2020 - 21
DFI Magazine September/October 2020 - 22
DFI Magazine September/October 2020 - 23
DFI Magazine September/October 2020 - 24
DFI Magazine September/October 2020 - 25
DFI Magazine September/October 2020 - 26
DFI Magazine September/October 2020 - 27
DFI Magazine September/October 2020 - 28
DFI Magazine September/October 2020 - 29
DFI Magazine September/October 2020 - 30
DFI Magazine September/October 2020 - 31
DFI Magazine September/October 2020 - 32
DFI Magazine September/October 2020 - 33
DFI Magazine September/October 2020 - 34
DFI Magazine September/October 2020 - 35
DFI Magazine September/October 2020 - 36
DFI Magazine September/October 2020 - 37
DFI Magazine September/October 2020 - 38
DFI Magazine September/October 2020 - 39
DFI Magazine September/October 2020 - 40
DFI Magazine September/October 2020 - 41
DFI Magazine September/October 2020 - 42
DFI Magazine September/October 2020 - 43
DFI Magazine September/October 2020 - 44
DFI Magazine September/October 2020 - 45
DFI Magazine September/October 2020 - 46
DFI Magazine September/October 2020 - 47
DFI Magazine September/October 2020 - 48
DFI Magazine September/October 2020 - 49
DFI Magazine September/October 2020 - 50
DFI Magazine September/October 2020 - 51
DFI Magazine September/October 2020 - 52
DFI Magazine September/October 2020 - 53
DFI Magazine September/October 2020 - 54
DFI Magazine September/October 2020 - 55
DFI Magazine September/October 2020 - 56
DFI Magazine September/October 2020 - 57
DFI Magazine September/October 2020 - 58
DFI Magazine September/October 2020 - 59
DFI Magazine September/October 2020 - 60
DFI Magazine September/October 2020 - 61
DFI Magazine September/October 2020 - 62
DFI Magazine September/October 2020 - 63
DFI Magazine September/October 2020 - 64
DFI Magazine September/October 2020 - 65
DFI Magazine September/October 2020 - 66
DFI Magazine September/October 2020 - 67
DFI Magazine September/October 2020 - 68
DFI Magazine September/October 2020 - 69
DFI Magazine September/October 2020 - 70
DFI Magazine September/October 2020 - 71
DFI Magazine September/October 2020 - 72
DFI Magazine September/October 2020 - 73
DFI Magazine September/October 2020 - 74
DFI Magazine September/October 2020 - 75
DFI Magazine September/October 2020 - 76
DFI Magazine September/October 2020 - 77
DFI Magazine September/October 2020 - 78
DFI Magazine September/October 2020 - 79
DFI Magazine September/October 2020 - 80
DFI Magazine September/October 2020 - 81
DFI Magazine September/October 2020 - 82
DFI Magazine September/October 2020 - 83
DFI Magazine September/October 2020 - 84
DFI Magazine September/October 2020 - 85
DFI Magazine September/October 2020 - 86
DFI Magazine September/October 2020 - 87
DFI Magazine September/October 2020 - 88
DFI Magazine September/October 2020 - 89
DFI Magazine September/October 2020 - 90
DFI Magazine September/October 2020 - 91
DFI Magazine September/October 2020 - 92
DFI Magazine September/October 2020 - 93
DFI Magazine September/October 2020 - 94
DFI Magazine September/October 2020 - 95
DFI Magazine September/October 2020 - 96
DFI Magazine September/October 2020 - 97
DFI Magazine September/October 2020 - 98
DFI Magazine September/October 2020 - 99
DFI Magazine September/October 2020 - 100
DFI Magazine September/October 2020 - 101
DFI Magazine September/October 2020 - 102
DFI Magazine September/October 2020 - 103
DFI Magazine September/October 2020 - 104
DFI Magazine September/October 2020 - 105
DFI Magazine September/October 2020 - 106
DFI Magazine September/October 2020 - 107
DFI Magazine September/October 2020 - 108
DFI Magazine September/October 2020 - 109
DFI Magazine September/October 2020 - 110
DFI Magazine September/October 2020 - 111
DFI Magazine September/October 2020 - 112
DFI Magazine September/October 2020 - 113
DFI Magazine September/October 2020 - 114
DFI Magazine September/October 2020 - 115
DFI Magazine September/October 2020 - 116
DFI Magazine September/October 2020 - 117
DFI Magazine September/October 2020 - 118
DFI Magazine September/October 2020 - 119
DFI Magazine September/October 2020 - 120
DFI Magazine September/October 2020 - 121
DFI Magazine September/October 2020 - 122
DFI Magazine September/October 2020 - 123
DFI Magazine September/October 2020 - 124
DFI Magazine September/October 2020 - 125
DFI Magazine September/October 2020 - 126
DFI Magazine September/October 2020 - 127
DFI Magazine September/October 2020 - 128
DFI Magazine September/October 2020 - 129
DFI Magazine September/October 2020 - 130
DFI Magazine September/October 2020 - 131
DFI Magazine September/October 2020 - 132
DFI Magazine September/October 2020 - 133
DFI Magazine September/October 2020 - 134
DFI Magazine September/October 2020 - 135
DFI Magazine September/October 2020 - 136
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