TC214 Soft Soils

Foundation Engineering for Difficult Soft Soil Conditions

Short name: Soft Soils (TC214)


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Background and Scopes

Soft soil engineering is often regarded as a classical geotechnical field. There are also some engineers / researchers who ridicule as “do you still study soft soils?” Looking at the current situation of land use in the world, most of good lands have already been developed, and frontiers of land development today are often in coastal areas, offshore land reclamation sites, or undeveloped wetlands, etc. In those areas where soft soil is thickly deposited, construction projects are facing geotechnical challenges. The soft ground is not only a soft clay deposit with high plasticity having a high water content and a high void ratio but also various kinds of soils such as highly sensitive soil, organic soil, peaty soil showing very high compressibility with remaining plant fibers, etc. Liquefiable soil due to earthquake is also a target in soft soil engineering. Peat is a very difficult soil in evaluation of its physical and mechanical properties. For soft soil deposits, installation of vertical drains with preloading is often used to accelerate the consolidation; however, we have to pay attention to continuity of the vertical drains and stability of preload fill. On the other hand, there is an advanced technology which can be applied to soft soil deposit, such as vacuum consolidation in which we don’t need to consider the continuity of PVD and the stability under vacuum loading. Some kinds of problematic soils such as sensitive soil for which it is very difficult to evaluate its intact characteristics, organic soil for which it is very difficult to apply cement stabilization technology, and volcanic ash for which it contains crushable soil particles, will be subject to soft soil engineering. Accordingly, from engineering sense, this TC is named as Foundation Engineering for Difficult Soft Soil Conditions.

As the design method has been changing from specification based design to performance based design on the basis of reliability based design, main subjects of soft soil engineering has also changed from “fail or not-fail problem” to deformation analysis. Advancement in construction technology makes it possible to enlarge structure dimensions, and then some stiff soil layers are recently considered relatively soft, even though those layers had been regarded as stiff. For example, the subsoil layers of the Kansai International Airport in deeper portion are Pleistocene clay layers, which are generally very stiff and often used as a bearing layer; however, those Pleistocene clay layers are regarded as relatively soft in this case because of very large incremental consolidation pressure. Actually, they observed residual settlement more than 3 m, and currently, annual settlement rate is approximately 60 mm/year.

Various types of soil are subjected in soft soil engineering, and variety of challenging geotechnologies in the field of ground investigation, laboratory testing, ground improvement such as acceleration of consolidation and solidification, prediction calculation in performance based design, etc. The followings are proposed subjects in TC214’s future activities.

Soil types:

-Marine clay (non-glacial)
-Marine clay (glacial)
-Lacustrine clay
-Silty clay/clayey silt
-Peat
-Dredged soil (treatment/ reclamation)
-Sandy soil for reclamation (liquefaction)
-Volcanic ash/ pumice sand filling (liquefaction due to looseness)

Projects:

-Man-made island (e.g. Kansai International Airport) [Possible collaboration with TC217: Land reclamation]
-Embankment (road and railway) [Possible collaboration with TC202: Transportation]
-Dyke/Levee [Possible collaboration with TC201: Dykes and Levees]
-Waste soil treatment
-Hydraulic cutoff (barrier) for waste reclamation site [Possible collaboration with TC215: Geo-Environmental]
-Foundations (mainly deep foundations) in soft soils
-Deep excavations in soft soils (e.g. West Link Gothenburg)
-Earth fills (liquefaction of loose pumice sands, e.g. 2018 Hokkaido Earthquake)

Phenomenon/Issues:

-Consolidation settlement (primary and secondary)
    Long-term consolidation (man-made island), Differential settlement (embankment), ground subsidence (dropping of groundwater level)
    With/without ground improvement
    Degradation/ deterioration in strength and stiffness (sensitive clays)
    Strain-rate effects on the stiffness and the strength

-Stability
    Seawall/ Embankment
    Staged construction (with vertical drains)
    Ground improvement (if necessary)

-Interaction between soil and foundation
    Piled foundation under vertical/horizontal soil movement

-Treatment
    Dewatering/ Solidification (cement, lime)

-Behaviour under moderate temperature changes (accelerated creep)

-Installation and soil disturbance effects (smear)

-Microstructural effects (pore-size distribution/ aggregation/ macro- and micro-porosity)

-Liquefaction of loose soil.

Investigation:

[Possible collaboration with TC101: Laboratory testing, and TC102: In-Situ Testing]
-Sampling and laboratory test
    UC, Triaxial CIU, CAU, CK0U (compression and extension)
-Sounding
    CPT, RI-CPT, vane
-Exploration
    PS-logging/ Seismic cone
-Monitoring
    Settlement/ compression of sublayers, excess pore water pressure, density

Prediction:

-Conventional theory
-Numerical analysis [Possible collaboration with TC103: Numerical Methods in Geomechanics]
-Physical modelling [Possible collaboration with TC104: Physical Modelling]
-Field observations
-Empirical method
    Curve fitting

Ground improvement technology:

[Possible collaboration with TC211: Ground improvement]
-For deposits
    Preloading/ surcharge loading
    Replacement
        Sand compaction piles (SCP: high replacement ratio, low replacement ratio)
    Replacement/ Consolidation/ Ddensification
        Vertical drains
    Prefabricated vertical drains (PVD) with preload/vacuum, Sand drains (SD) with preload
    Solidification (chemical treatment)
        Deep mixing method (DMM) with cement/lime
-For slurry
    Solidification
        Cement treated soil (pneumatic mixing method, airfoam treated soil)
    Dewatering (filter press)
    Electro-osmosis

 

Chair:          Prof. Yoichi Watabe (Hokkaido University, Japan)

Vice-Chair:  Prof. Minna Karstunen (Chalmers University of Technology, Sweden)

Secretary:   Prof. Suched Likitlersuang (Chulalongkorn University, Thailand)

 

Main theme:

Prediction methods from laboratory and site investigation to modelling and design in soft soil engineering

Terms of reference

ISSMGE-TC214 on Soft Soil Engineering ”Foundation Engineering for Difficult Soft Soil Conditions” will focus on the following three broad topics under the main theme “Prediction methods from laboratory and site investigation to modelling and design in soft soil engineering”:

  1. Physical and mechanical properties – There are variety of soft soils with different characteristics in the world. Interpretation of fundamental properties of those soils and understanding the difference of each soil are necessary. This issue includes field investigation, laboratory testing, and constitutive modeling (or interpretation of laboratory test results).
  2. Prediction of soil behavior – To meet performance based design, soil deformation has to be analytically (or empirically) predicted. However, because of difficulties in site investigation and laboratory testing due to softness, there are still some issues to be filled in this research field to achieve performance based design.
  3. Ground improvement / soil treatment – Ground improvement is one of the best solutions to use a soft soil deposit as a foundation ground. Also, soil solidification by mixing with a binder (cement, lime, blast furnace slag, etc) is recently preferably used to shorten construction period instead of conventional technology such as vertical drains; however, organic contents often adversely affect solidification.

The main aim of the TC214 is to promote a greater interaction among practitioners (engineers) and academicians engaged in soft soil engineering related so as to achieve greater cooperation and facilitate the exchange of information, experience, knowledge, and new ideas in these two areas. In the next four years (2020-2024), TC214 would endeavor to organize at least two small to medium size workshops during ISSMGE conferences: (i) the 20th ICSMGE at Sydney, Australia, in 2022, and (ii) one of regional conferences under auspices of ISSMGE in 2023. In each workshop, the three themes listed above will be discussed. One principal aim of these workshops is to ensure publication of excellent case histories and associate construction experience, as well as technical proposals to overcome soft ground problems for future projects.

In addition, TC214 will propose to organize an international symposium (new IS-series on Soft Soil Engineering with 150 to 300 participants) on soft soil engineering. The first symposium will be held in 2023. This proposal will be discussed more later, but these future activities depend on the infection status of the new coronavirus COVID-19.

# Type Full Name Country
1 Chair Yoichi Watabe Japan
2 Vice Chair Minna Karstunen Sweden
3 Secretary Suched Likitlersuang Thailand
4 Nominated Member Anh Dzung NGUYEN Vietnam
5 Nominated Member Victor Kaliakin United States
6 Nominated Member Alvaro Perez Peru
7 Nominated Member Josif Josifovski North Macedonia
8 Nominated Member Gerardo Pittaro Singapore
9 Nominated Member Hans Dete Mozambique
10 Nominated Member Mats Karlsson Sweden
11 Nominated Member Roman Marte Austria
12 Nominated Member Domenico Lombardi United Kingdom
13 Nominated Member Juan PAULIN AGUIRRE Mexico
14 Nominated Member Germán López Pineda Spain
15 Nominated Member Umur Salih OKYAY France
16 Nominated Member Hong DOAN France
17 Corresponding Member Hamza MENACEUR France
18 Nominated Member Stefano Muraro Netherlands
19 Nominated Member James Fern Switzerland
20 Nominated Member Fabio M. Soccodato Italy
21 Nominated Member Sung Ryul Kim South Korea
22 Nominated Member Cristina Jommi Italy
23 Corresponding Member Moon Sek Nam South Korea
24 Corresponding Member Haizuo zhou China
25 Nominated Member Shiao Huey Chow Australia
26 Nominated Member Erika Prina Howald Switzerland
27 Nominated Member Ariane Locat Canada
28 Nominated Member Juan Pablo Osorio Ireland
29 Nominated Member Paulo da Venda Oliveira Portugal
30 Nominated Member Henrique Lopes Portugal
31 Corresponding Member guoxiong Mei China
32 Corresponding Member Xilin Lu China
33 Nominated Member Fintan Buggy Ireland
34 Nominated Member Feyza Cinicioglu Turkey
35 Nominated Member Yi Hong China
36 Nominated Member Ken Yeo Hong Kong Special Administrative Region
37 Nominated Member Muhammad Shakeel Hong Kong Special Administrative Region
38 Nominated Member Maria Esther Soares Marques Brazil
39 Nominated Member Roberto Coutinho Brazil

Kick-off meeting (web) held at 5 pm (UTC) on 4 June 2021

Agenda

1. Self-introduction (all members. 2 min each)

TC Membership20210603.xlsx and Biography of TC214 members.docx

Link to access Biography of TC214 members:

https://www.issmge.org/filemanager/technical_committee_pages/55/Biography_of_TC214_members.pdf

2. Terms of reference

Terms of Reference TC214.docx

or visit the following URL

https://www.issmge.org/committees/technical-committees/applications/soft-soils-

and select Terms of Reference

3. Frequency of meeting

Web-meeting (Record video, and open it to public. Care must be taken regarding copyright)

Face-to-face meeting after the Pandemic due to COVID-19

Every 2 months. 5 meetings per year. Avoiding Friday (and avoiding July and August).

Rotate suitable time slot for regions.

4. Future activities (Web-meeting)

4-1. 1st round: Soft soil problems in each topic (3-5 members per meeting. We need to nominate 3 speakers for the first regular meeting)

4-2. 2nd round: Lecture of case history/academic research (2-3 members per regular meeting)

 

The URL to access the video recording of the meeting is as follows.

https://youtu.be/iP148GFB6Ws

The 2nd meeting  (web) held at 8 am (UTC) on 8 Dec 2021

Agenda

1. TC session at the 20th ICSMGE (Sydney, Australia)

We discussed how to organize TC session at the 20th ICSMGE (Sydney, Australia). We would prefer to organize a panel discussion style session (see Technical Committee Selection Process.pdf), and for that, we need to select the best 20 (or 30) papers from 39 papers in the list. Please open TC214 -Accepted ICSMGE Papers.docx and fill up the cells on the evaluation columns with your score (10: Excellent to 1: Poor).

Please send me back the Word document with your score not later than December 28, 2021.

2. Members' soft soil issues

During the meeting, 4 members introduced their soft soil issues as listed below:

(1) Manmade islands on soft marine deposits in Japan by Yoichi Watabe

(2) Some challenges from soft clays in infrastructure in Singapore by Gerardo Agustin Pittaro

(3) Short overview of typical geotechnical problems regarding soft soils in Alpine regions such as Austria by Roman Marte

(4) Back analysis of a road embankment over soft soils - Maputo river floodplain by Hans Dete

The following link can be used to access the video recorded during the meeting.

https://youtu.be/dzgS2o7sq4k

 

The 3rd meeting (web) held at 3 pm (UTC) on 25 March 2022

Agenda

1. TC session at the 20th ICSMGE (Sydney, Australia)

The organizing committee of 20th ICSMGE allocated 1 virtual session and 0.5 in-person session for TC214.

The virtual session will be chaird by Prof. Yoichi Watabe, and the in-person session will be chird by Dr. Shiao Huey Chow.

We decided to propose the presentation order (or video play order) based on the score, which was evaluated in the process of presentation paper nomination in last December.

2. Members' soft soil issues

During the meeting, 2 members introduced their soft soil issues as listed below:

(1)  Rio de Janeiro city soft clay by Esther Marques

(2) Challenges and Improvement Solutions of Soft Bangkok Clay by Suched Likitlersuang

 

The following link can be used to access the video recorded during the meeting.

https://youtu.be/4AnDgJf1D7M

The 4th meeting (web) held at 1 pm (UTC) on 10 June 2022

Agenda

1. TC session at the 20th ICSMGE (Sydney, Australia)

Prof. Yoichi Watabe reported the virtual session of TC214 at 20th ICSMGE.

Day 4: 16:30-17:30 Parallel Sessions

TC214 Virtual Session

(1) Clay fabric under the britest light
      Mr. Georgios Birmpilis
(2) A framework for the time-dependent behaviour of soft strutured clays
      Dr. Miguel Mánica
(3) Numerical prediction of the Ballina test embankment using an advanced constitutive model
      Mr. James Barron
(4) Multi-stepwise CRS consolidation test and its application to predict long-term consolidation based on the isotache concept
      Prof. Yoichi Watabe

2. Members' soft soil issues

During the meeting, one member introduced his soft soil issues as listed below:

(1) Learnings from land reclamation projects at Kansai International Airport and Tokyo Haneda Airport
by Yoichi Watabe

The following link can be used to access the video recorded during the meeting.

https://youtu.be/idUKW5qbIAQ

 

The 5th meeting (web) held at 1 pm (UTC) on 10 November 2022

Agenda

1. Members' soft soil issues

During the meeting, 2 members introduced her/his soft soil issues as listed below:

(1) Physical modelling at the field scale in the Netherlands
by Christina Jommi

(2)Soft soil challenges in Ireland
by Fintan Buggy

 

The following link can be used to access the video recorded during the meeting.

ttps://youtu.be/rrtUPf9w4_A

Contact Technical Committee : Foundation Engineering for Difficult Soft Soil Conditions

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