OUTLINE:
- Geotechnics history and application
- Ways that geotechnics have been helpful eversince the start of its discovery
- Its important contributions to society
- Current trends and its impact to the future
- Future possibilities
- Conclusion
REPORT
I. Geotechnical Engineering Definition and Application
Geotechnical engineering uses principles of soil and rock mechanics to investigate subsurface conditions
and materials; determine the relevant physical, mechanical and chemical properties of these materials;
evaluate stability of natural slopes and man-made soil deposits; assess risks posed by site conditions.
Geotechnical engineering is a branch of civil engineering concerned with the engineering behavior of
earth materials. It is important in civil engineering, but also has the applications in military, mining,
petroleum and other engineering disciplines that are concerned with construction occurring on the surface
or within the ground. Geotechnical engineering designs earthworks and structure foundations; monitor
site conditions, earthwork and foundation construction.
II. How Geotechnical Engineering emerged all throughout history – Brief explanation
Did you know the first ever geotechnical engineering activity traced in history was way back 2000 BCE
(4,000 years ago), were humans have used soil as a material for flood control, irrigation purposes, burial
sites, building foundations, and construction material for buildings? Specifically, it was from the dykes,
dams, and canals in some parts of ancient Egypt, Greece , and other parts of the world. Although a
thousand of years has passed already, our current generation still practices geotechnical engineering
where we study soil and rock behavior and utilize it to address concerns in society especially in our
structures.
Through researching and reading articles on the internet about its history, that there are major differences
in the practice in between generations. In earlier times, the practice was applied by trial and error,
observational experience, and empirical experimentation which means there wasn’t much thought put
through in soil structures as well as its design and no scientific basis were applied to back what they were
doing. Geotechnical Engineering in the primitive era was an art rather than science.
By the 18th century as civilization advanced further, numerous engineering problems related to building
foundations began to emerge. Several foundation-related problems, such as the Leaning Tower of Pisa in
Italy, a famous tourist destination spot until now prompted scientists to begin taking a more scientific-
based approach in geotechnical engineering. It presented a very unique challenge to scientists at that time,
trying to investigate why the structure is leaning at an angle. The 800 year old mystery of the tower of
Pisa was solved by John Burland, an English geotechnical engineer who discovered that the primary
cause of the tilt was a fluctuating water table which would perch higher on the tower’s north side, causing
the tower’s characteristic slant to the south. Significant soil theories were created and then more
principles of soil mechanics came into existence until now.
III. Current Emerging Trends and Innovation
a. Laboratory Testing and Analysis
- Prediction of Soil Behavior – A Reappraisal
This study emphasizes the fact that there is a certain pattern of variation of soil
properties between liquid and plastic limit. Undrained shear strength at plastic limit (170kN/m2 ) is
around hundred times the undrained shear at liquid limit. At plastic limit a soil is subjected to a
consolidation pressure of around 630kN/m2 which is again around hundred times that at the liquid limit.
It has been verified that coefficient of permeability is of the same range/order ( average value 2.15 × 10-
7 cm/sec ) at liquid limit and it has been found that coefficient of permeability is also of the same range
or order at plastic limit of the soil ( average value 7.25 × 10-9 cm/sec ). These findings has resulted in the
formulation of expressions for predicting undrained shear strength, consolidation pressure and
permeability of a remolded soil at any water content based solely on its liquid limit and plastic limit.
- Risk Analysis of Bearing Capacity of Shallow Foundation
Plate load test, which is revered as most reliable in-situ testing technique to obtain loadsettlement
response, may give rise to unrealistic results if not properly conducted. This paper focuses on the
analysis of laboratory plate load test results, to understand the effect of maintained and non-maintained
load during each loading stage. Following are the salient conclusions drawn from the study.
1. From both stress maintained and stress not-maintained laboratory plate load tests on remoulded
marine clay, it is observed that the load-settlement response for both the cases are different.
2. Load tests with conventional hydraulic pumping units, which cannot hold the pressure constant
during loading stages, lead to flatter load-settlement response.
3. Had there been a servo-controller based hydraulic pumping unit or a similar mechanism to maintain
the pressure on the plate during each loading cycle, the observed settlements under each loading stage
would have been still higher, than that were observed in the present study.
4. The resistance factor for bearing pressure varies from 0.63 to 0.67, with an average value of 0.65, for
settlements in the range of 4 to 12 mm. These resistance factors, when multiplied with the loads of non-
maintained load test for any given settlement, can partially compensate the gross overestimation of
loads obtained from nonmaintained load tests.
- Coal Ashes in Geotechnical Engineering Practice: Beneficial Aspects
The common understanding among the people is that the coal ashes, which are by-products of thermal
power generation industry, are waste materials which are harmful to the environment and to the people
of the region as well. However, the study of the physical, chemical and engineering properties of coal
ashes shows that the coal ashes are potential resourceful materials from the geotechnical engineering
applications view point. The present paper has discussed many properties of coal ashes which can be
used with the advantage in various geotechnical engineering applications. They are – low specific
gravity, lower compressibility, higher rate of consolidation, higher frictional strength, higher CBR,
negligible swell – shrink potential, water insensitiveness of compaction characteristics and pozzolanic
reactivity. The beneficial properties of coal ashes discussed in this paper encourage their use as
• fill materials for low-lying areas
• construction fill materials on weak compressible soils
• The ever increasing scarcity for good materials in various geotechnical engineering projects can also be
overcome by the use of large scale use of coal ashes as
• back fill materials in retaining structures
• good foundation base materials
• sub-base materials for pavements
• construction of earth embankments and dams
• mechanical admixtures in stabilising expansive and cohesive fine-grained soils.
b. Ground Improvement Methods
- Ground Response Support Measures for Railway Tunnel in the Himalayas
The Pir Panjal tunnel in the Himalayas traverses through much diversified geology experiencing high
ground stresses. Time dependent behaviour of tunnels in squeezing rock is investigated using Closed
form and FLAC methods. Stresses and displacements are obtained before and after the installation of
support measures. Nominal shortcrete and rock bolting proves ineffective to control squeezing in shales,
hence advance face stabilization approaches have been suggested in this work.
- Recent Experiences on Ground Stabilization Techniques
All the methods described in this paper are actual case studies which have been implemented at various
sites by author. The gabion walls in ash dykes provide a passive support to ash dyke and thus allow
further raising of dykes. The case study discussed here is for a thermal power project where millions of
tonnes of flyash is produced every year and govt. has made very strict laws against purchase of new
grounds for storage of flyash. The gabion walls discussed in paper are also provided due to availability of
very limited space at site. Both the methods proved to be much more economical than purchase of new
grounds.
- Soft Ground Improvement with PVDS
Analysis of consolidation of soft ground treated by PVDs is presented. A simple non-linear theory of
radial consolidation developed for thick deposit of clay treated with PVDs considering linear void ratio-
log effective stress relationship predicts that while the degree of settlement is independent of the final
to initial stress ratio, the degree of dissipation of pore pressure is very much dependent on the stress
ratio. The residual excess pore pressures are under-estimated in the conventional linear theory. The
proposed nonlinear theory substantiates the actual in-situ slower rate of degree of dissipation of excess
pore pressures compared to that of the degree of settlement. The non-linear consolidation effect is
pronounced at shallow depths compared to the effect at greater depths. The excess pore pressures due
to radial drainage vary not only with time and radial distance but also with depth in contrast to depth-
independent pore pressures from the conventional theory for radial flow. The significance of the
proposed theory is that it can explain failure of high embankments constructed rapidly on thick deposits
of fine grained soils.
c. Underground Structures
- Performance based Earthquake Resistant Design of Geothermal Structures – A New Trend
The design of any geotechnical structure such as foundation, embankment, retaining wall, slope etc.
under earthquake loading has sufficient scope to improvise. The present day design guidelines
emphasize on force based design which includes evaluating the factors of safety against sliding,
overturning and bearing pressure. However, displacement or performance based analysis is being
considered to be superior specially for geotechnical structures. Pushover analysis applied to structural
frames can provide a basis for assessing the capacity of geotechnical structures under a design
earthquake demand. Considering this aspect, it is important to note that the evaluation of precise
permanent displacement of geotechnical structure is extremely essential. In this regard, the
methodology presented in the paper to estimate the coupled permanent sliding and tilting displacement
is useful. It is even more important to validate and show that analytical models are comparable to
reality. With such papers, it is hoped that performance based design in geotechnical earthquake
engineering takes a big leap in immediate future.
- A Decision Support System for Risk Assessment of Remediation Option Selection for Contaminated
Soils and Ground Water
Contaminated soils and groundwater are receiving increasing attention due to the greater
understanding of their toxicological importance in ecosystem and for human health. Risk assessment
based technologies are proving to be useful for selection of remediation tec hnologies for contaminated
sites. With a risk based cleanup regimen, sites are remediated to the extent that will render them safe
for future land use. With large number of contaminated sites in India, a decision support system would
be very helpful in quick, feasible and cost effective remediation process selection. The present study is
an endeavour in this direction. The developed DSS has been applied for the contaminated site of UCIL
Bhopal and results are reported.
d. Offshore Geotechnical Structures
- The Assessment of Offshore Wind Innovation System in Poland Using Technological Innovation
System Approach, which has been widely used to describe the Offshore Innovation System among
Europian Countries
e. Geosynthetics
- Geosynthetics are synthetic products used to stabilize terrain. They are generally polymeric products
used to solve civil engineering problems. This includes eight main product categories: geotextiles,
geogrids, geonets, geomembranes, geosynthetic clay liners, geofoam, geocells and geocomposites. The
polymeric nature of the products makes them suitable for use in the ground where high levels of
durability are required. These products have a wide range of applications and are currently used in many
civil, geotechnical, transportation, geoenvironmental, hydraulic, and private development applications
including roads, airfields, railroads, embankments, retaining structures, reservoirs, canals, dams, erosion
control, sediment control, landfill liners, landfill covers, mining, aquaculture and agriculture.
f. Remote Sensing Technology
- Geotechnical Engineers have never had array of technological options available for monitoring
embankments, dams, and slopes. Remote Sensing will help engineers in monitoring 24/7 without having
to be physically onsite. Through this, data can be quickly processed and transmitted electronically. Alert
thresholds can be established so stakeholders are automatically notified when collected data exceeds a
threshold. The high spatial resolution allows capturing the spatial variability of the measurement of
interest. The most impactful recent advancements in this technology is that unmanned platforms or
devices can be quickly deployed at a site with a wide range of technologies, advancement includes
different imagery, e.g. thermal, optical, and reflective, and LiDAR. Cloud storage where vast amounts of
data can be stored and accessed quickly by people anywhere in the world. It changed the industry by
increasing the use of satellites, number and types of sensors and greatly improved spatial and temporal
resolution of sensing.
