Learning from Failures from a Geotechnical Prospective

1

You can tell whether a man is clever by his answers. You can tell whether a man is wise by his questions. Naguib Mahfouz

2

International Conference on Forensic Civil Engineering, Nagpur, India, 21-23 January 2016

Presentation Overview  Engineering Judgment  Peer Review  Monitoring and Risk Management

1. Introduction 2. Modern Challenges and New Frontiers 3. The Public Perceptions of Engineering Failures 4. Successes Emerging out of Failures 5. Definition of Failure 6. Costs of Failures 7. The Causes of Failures 8. Approaches to Overcome Oversights  Proper Site Characterization  Quantifying Uncertainties in the Design  Validated Modeling

9. Lessons Learnt from Some Previous Failures  Failure of St. Francis Dam, California, USA, 1928  Liquefaction Failures in Niigata Earthquake, Japan, 1964  Rissa Landslide, Norway, 1976.  The Teton Dam Failure, 1976.  Failure of the Nicoll Highway, Singapore, 2001.  The landslide in Bingham Canyon copper mine, Utah, USA, 2013

10.Conclusions

Learning from Failures: A Geotechnical Perspective

Agaiby, S.W. & Ahmed, S.M.

3


1. Introduction

“Failure is success if we learn from it.” M. Forbes

Bearing Capacity Failure of the Transcona GrainElevator, Winnipeg, Canada, 1913 Learning from Failures: A Geotechnical Perspective

Transcona Grain-Elevator, Today


4


 Engineering aims at precluding possible failures of the engineered item under the expected loadings.  Nevertheless, the history of engineering has numerous failures.  The number of failures did not decline in the last decades despite the recent technological advances (e.g., the period of 2004–2011, more than 32,000 landslide-related fatalities have been documented, not including those landslides caused by earthquakes, Petley, 2012).

14.3

1

The Leaning Pisa Tower (completed in 1377)

Collapse of the Tacoma Narrows Bridge, 1940


Failure of the Flooded Control System in New Orleans, Louisiana, 2005 Agaiby, S.W. & Ahmed, S.M.

5


Why failures still occur?  Soils and rocks are complex engineering materials with properties and parameters that are commonly not linear, unique or constant.

 Engineers as humans, are incomplete. They may recklessly, unknowingly or accidentally overlook some aspects in design or construction.  Nature does not necessity ignore what may have overlooked by the engineers if such aspects are critical.

 The possibility of failures increase in projects with complex ground conditions and when newly developed technologies are applied

Shoring failure in Infinity Tower, Dubai, UAE, 2007 Learning from Failures: A Geotechnical Perspective

A Building failure, Shanghai, China, 2009 Agaiby, S.W. & Ahmed, S.M.

6


 recent environmental changes such as the Global Warming, which increase the rate of catastrophic events such as hurricanes.  A recent example of the failures initiated by the Climate Changes due to the Global Warming is the failure of the flood defense system for the greater New Orleans area in August 2005.

Satellite image for Hurricane Katrina (29 August, 2005)

 Approximately 75% of New Orleans became under water after the breaches. Hurricane Katrina was initially held to be the main reason for the failures of levees and floodwalls protecting New Orleans.  Later, it was found that major breaches were caused by failure of the soils underlying the levees or failure of the levee embankments due to design and construction shortcomings that were revealed by studying the occurred failures (Kanning, et al., 2007; Sills, et al., 2008; and others Learning from Failures: A Geotechnical Perspective

A satellite image for New Orleans on 31 August 2005 Agaiby, S.W. & Ahmed, S.M.

7


How to benefit from a failure?  Forensic engineering experts investigate the occurred failures. They develop possible scenarios and test them with thorough analyses.  Forensic investigations and analyses are like puzzle-solving. They require problems to be worked in reverse.  Experts come up with hypotheses of how the failure occurred.

Settlement trough based on a three-dimensional analysis of Nicoll Highway Failure in 2004 (Lee et al., 2010)



8


2- Modern Challenges and New Frontiers “Real knowledge is to know the extent of one's ignorance” Confucius The Tallest building: The Kingdom Tower, Jeddah, KSA (+1000m height; under construction)


The longest tunnel: Gotthard Base Tunnel, Switzerland (57 km length, under construction)


9


 According to UN (2015), the world population reached 7.3 billion in mid 2015. This implies that the world population has increased by about five folds since the end of World War II.  The projected world population is expected to range, with 95% confidence intervals, between 8.4 and 8.6 billion in 2030 and between 9.5 and 13.3 billion in 2100. 

The huge increase in the numbers of human inhabitants necessitates, among other evolving essentials, unprecedented acceleration of construction.

 This can only be achieved through the utilization of undeveloped areas that were previously considered as problematic (e.g., areas with soft clays, high seismicity, arid problematic soils, etc.). Learning from Failures: A Geotechnical Perspective


10


 Developed and rich countries built, and continue to build, higher and heavier buildings than ever before. These nations dig deeper and wider excavations/tunnels than ever before in order to serve the planned mega constructions.  The emerging huge constructions push the boundaries of our engineering practices beyond their present limits. Consequently, the number and frequency of failures are expected to increase in the forthcoming decades despite the accelerated technological advances. Utilization of the underground space (Source the International Tunneling Association, ITA)

High-rise building timeline (Source: Council on Tall Buildings and Urban Habitat, CTBUH)



11


3- The Public Perceptions of Engineering Failures The First Known Law: The Code of Hammurabi (1754 BC)  If a builder builds a house for someone, and does not construct it properly, and the house which he built falls in and kills its owner, then that builder shall be put to death.  If it kills the son of the owner, the son of that builder shall be put to death. Learning from Failures: A Geotechnical Perspective


12


 The public opinion certainly consider engineers’ success as unquestionable and engineers’ failures are intolerable.  Brandl (2004) noted that the recent medical statistics disclosed that in Great Britain, Italy and Germany about 100,000 people annually lose their life because of medical mistakes. Additionally, about 300,000 patients annually suffer permanently from severe treatment mistakes.  Brandl (2004) also noted that despite the magnitude of these huge numbers, the public opinion would not fiercely react against them in the same way in case some engineers unintentionally cause only 10 people to lose their life in a building failure.

Engineers can not hide their mistakes

 It is interesting to note that the engineering perceptions of failures in the pioneering works of Prof. Petroski has inspired the research related to biomedical failures (Schrenker, 2007). This shows that the engineering concerns about failures indeed has deeply affected other science branches. Learning from Failures: A Geotechnical Perspective


13


4- Successes Emerging out of Failures “It is an apparent paradox of science and engineering that more is learned from failures than from successes.” H. Petroski

Sneferu Bent Pyramid (Height: 104 m)

Khufu Great Pyramid (Height: 146.5 m)



14


The Egyptian Pyramids: Success is born from the womb of failure Zoser Stepped Pyramid

 Zoser Stepped Pyramid was built about 2686 - 2613 B.C. and is known to be the first pyramid in history.

 The architect Imhotep was later deified and became the patron god of architects and doctors.  It was a revolutionary design. Previously, pharaohs were buried in mastabas. Imhotep created a pyramid by stacking six mastabas on top of each other. This design would later evolve into the smooth-sided pyramids.  Stepped Pyramid was initially constructed as a square mastaba with a core of locally quarried stone. It was amended by three more square layers that were to form Pyramid 1.

 It was extended again and two more layers were added to the top resulting in Pyramid 2, a six-tiered step pyramid, which was then cased in dressed limestone.  This Pyramid is 62m tall, with a base of 109m × 125m and was clad with polished white limestone. The burial chambers are underground, hidden in a maze of tunnels, to discourage grave robbers. Learning from Failures: A Geotechnical Perspective


15

   

International Conference on Forensic Civil Engineering, Nagpur, India, 21-23 January 2016 Sneferu Pyramids Sneferu, who was the founder of the 4th Dynasty during the Old Kingdom, reigned Egypt from 2613 BC to 2589 BC. He built at least three famous pyramids that survive to date (The Meidum Pyramid, the Bent Pyramid and the Red Pyramid). Sneferu introduced major innovations in the design and construction of pyramids in Ancient Egypt. Khufu, Sneferu’s son, reigned Egypt after his father and built the Great Giza Pyramid The Meidum Pyramid

The Bent Pyramid

The Red Pyramid

 Height = 93m

 Height = 105m

 Height = 104m

 Base length = 114m



 Inclination =

 Inclination = 54o (lower part)

 Inclination = 43o

74o

 Partially collapsed during construction.

= 43o (upper part)  The lower part suffered from cracks during construction.



16


The Great Pyramid of Giza The Great Giza Pyramid built about 5000 years ago by Khufu (son of Sneferu). It is the last surviving of the “Seven Wonders of the Ancient World” and it was the tallest man-made structure till the Construction of Lincoln Cathedral in 1300 A.D. (i.e., over 3,800 years). The Great Giza Pyramid is still a wonder to date for the following reasons:  Its side length and height are 230.4m and 146.5m, respectively. The ratio of the perimeter to height equates to 2π to an accuracy of better than 0.05%. Its mass is estimated at 5.9 million tons.  Its mass and volume are 5.9 million tons and 2.5 million cubic meters, respectively.  It has 2.3 million Limestone blocks. The stone blocks were very large in the lower layers (1.0m x 2.5m base dimensions and 1.0-1.5m high, 6.5 -10 tons). Higher layers are of smaller blocks to easily transport them (1.0m x 1.0m x 0.5m, approx. 1.3 tons).  8,000 tons of granite, were imported from Aswan located at more than 800 km away. The largest granite stones in the pyramid, found above the "King's" chamber, weigh 25 to 80 tons each.  Blocks of the Great Pyramid were fit together with extremely high precision. The mean opening of the joints is only 0.5 millimeters wide (1/50th of an inch).  There are three known chambers inside the Great Pyramid. Learning from Failures: A Geotechnical Perspective


17


 Stone quarrying, transportation of the blocks, and lifting them in position by ramps. Different configurations have been  The Great Pyramid was built on Middle to Late Eocene massive limestone and dolomite.

 Geotechnical failures would have been inevitable if built in the Nile valley.  A recent study (Raynaud et al., 2008) indicates that rock outcrops were put to good engineering use by builders in the Great Pyramid. The study showed existence of a hill of large volume at the location of pyramid.

the the the the

 Rock keys was used to stabilize the edge slope against slippage (very efficient especially under the earthquake loading).



18


The settlement contours of Oroville Dam vs. the location of the King’s burial room in the Great Pyramid



19

150 m

Base Area


35344 m2

13625m2

53084 m2

48400 m2

12996 m2 146.5m

Height 50m

Inclination

100m

51.8 deg.

93m

105m 43 deg. Upper Part

104m 43 deg.

62m 74 deg. Stepped Pyramid

Meidum Pyramid

54 deg. Lower Part Bent Pyramid


Red Pyramid

The Great Pyramid


20


Pyramids Outside Egypt Paris - France

Nevada - USA

California - USA

Russia



21


The Unfinished Obelisk in Aswan  The Unfinished Obelisk in Aswan is an example of the quarrying technique used by Pharaohs in the hard rock of granite in Aswan.  This obelisk, if completed, would have been the largest known ancient obelisk (42 m long) and would have weighed nearly 1,200 tons.  It is believed that Queen Hatshepsut had ordered its construction.  The length of the trenches around the unfinished granite obelisk measured a total of 91 meters.  A cracks appeared in the granite that was developed by releasing the stress and, hence, it was abandoned. Learning from Failures: A Geotechnical Perspective


22


El-Kafara Dam  Built around 2650 BC next to the First Pyramid of Sakkara for flood control. The dam was about 110m long and 14m in height with a base width of 98m and crest width of 56m. The core was 32m wide and consisted of 60,000 tons of earth (the impermeable core) and rock-fill shoulders. It is the oldest dam of such size in the world.  Downstream slope protection for the dam consisted of limestone ashlars (each was roughly 30 cm high, 45 cm wide, 80 cm long and 23 kg weight).  The dam was under construction for 10 to 12 years before being destroyed by a flood probably because of the absence of a diversion that would have directed water to a wadi around the construction site.  the Ancient Egyptians learnt from the failure of their first flood control dam, El-Kafara Dam that their knowledge at that time would not allow them to control the mighty force of water. They abandoned the idea of building a similar flood-control dam and it was not till another eight centuries that the attempt was retried Learning from Failures: A Geotechnical Perspective


23


5- Definition of Failure “If you cannot explain it simply, you do not understand it well enough.” A. Einstein Just because it works, it doesn’t mean it is not a failure

Leaning Tower of Pisa: When our failures become monuments



24


 A failures in engineering may be defined as having an engineering product with inferior features are considered as un acceptable.

 Failures are nowadays are synonymous with limit states in modern codes. • Failures leading to life-endangering or gross economic loss are called the ultimate limit states. • Failures leading to inconvenience of the end users due to inacceptable deformations are termed serviceability limit states.  Additionally, design codes specify a minimum design lifetime to structures; hence, if a structure does not perform satisfactorily in the working environment during its anticipated exposure conditions during that lifetime, the limit state of the durability limit state is reached. Learning from Failures: A Geotechnical Perspective

Failure of two buildings by 1999 Izmit Earthquake, Turkey Agaiby, S.W. & Ahmed, S.M.

25


 Although limits states are commonly applied in everyday design, yet, the boundaries between the ultimate limit state failures and the serviceability limit state failures are not so rigid.

 Duncan (2000) discussed the case of sliding of a retaining wall, which is considered an ultimate limit state, and the effect of wall movement on this mode of failure.

Sliding

 If the wall slides for a small distance away from the backfill side, then the earth pressure on the active side would decrease and the passive soil earth pressure on the other side would increase; accordingly, the wall may become stable again.

 The progress of the net resisting load with the increasing deformations may be considered unsatisfactory by some engineers, from a serviceability point of view, despite the fact that sliding is an ultimate limit state. Learning from Failures: A Geotechnical Perspective


26


 the definition of “failure” in the loaddeformation and/or stress-strain relationships is not well-agreed on among geotechnical engineers.  Fellenius (1980), Kulhawy & Hirany (1997) & NeSmith & Siegel (2009) demonstrated using the observed load-deformations relationship for deep foundations that the common methodologies for inferring failure loads as ultimate limits are highly variable and give a wide range of results.  They concluded that the concept of failure is still not fully understood even at the very basic level of the interpretation of loading tests. Learning from Failures: A Geotechnical Perspective

NeSmith & Siegel (2009) Ultimate Load = 250 to 500 ton


27


(After Hirany & Kulhawy, 1989)



28


 Failure may also be identified from a contractual point of view.  It is well-acknowledged that the largest source of claims and disputes in the civil engineering field is in the ground.  In projects such as tunnels or dams, the predicted costs and time schedules are often exceeded due to the revealed differing ground conditions/unforeseen.  Consequently, project managers and contract administrators may consider the resulting overruns as failures from their perspective especially if they substantially exceed the planned budget and/or schedule. Learning from Failures: A Geotechnical Perspective

Project Constraints Quality/Scope


29


The Leaning Tower of Pisa  The height of the tower is 56.7 m and its foundation outer diameter is 19.6m. Its weight is about 14,200 tons.  It was built in the span of about 200 years. The evident tilt of the tower was first noticed during the initial phase of construction which began in 1173 AD. Engineers tried to compensate for the tilt by making the columns and arches of the third story slightly taller on the sinking side.  The tilt increased in the decades before the structure was completed, and gradually increased until the structure was stabilized in 1990-2001.  Prior to restoration works, the tower leaned at 5.5o with the vertical but the tower now leans at about 3.99o. Learning from Failures: A Geotechnical Perspective


30


 The tower had been built atop very soft soils yet uniform settlement could have occured.

 Burland, et al. (1998, 1999, 2009 & 2013) attributed the primary cause of the tilt to the fluctuating water table which would perch higher on the tower’s north side, causing the tower’s characteristic slant to the south. Learning from Failures: A Geotechnical Perspective


31


Other Famous Leaning Historical Towers (Typical Allowable Tilt by Codes = 1/300 or 0.19o) Big Ben Tower, London, UK Height = 96 m, Tilt = 0.26o

Leaning Tower of Nevyansk, Russia Height = 57.5m, Tilt = 3o

Tiger Hill Pagoda, Suzhou City, China Height = 48m, Tilt = 3.6o


Tower of Suurhusen, Germany Height = 27.4 m, Tilt = 5.2o


32


How did our engineering blunders inspire Modern Architecture?

Capital Gate is a skyscraper in Abu Dhabi. It is 160 m with 18° inclination.

The Gate of Europe towers (Spanish: Puerta de Europa) are twin office buildings in Madrid, Spain with a height of 114 m and 15 deg. Inclinations.



33


The Montreal Tower is the world's tallest inclined tower. It has a height of 165m and inclination of 45o.



34


How did our engineering blunders inspire caricaturists?

However, we can save 700 liras and two months by not doing a geotechnical investigation



35


How did our engineering blunders inspire people?

People interact with the Leaning Pisa Tower in different ways. Some like pushing it but luckily others try to hold it. Learning from Failures: A Geotechnical Perspective


36


6- Costs of Failures

“Failure is the tuition you pay for success.” W. Brunell

A photo before the failure of the central span of the Sunshine Skyway, Florida, USA


The new central span of the Sunshine Skyway Bridge. Its piers are now protected by dolphins.


37


 Failures always impose implications that may be defined in terms of added costs to the project budget. The costs related to failures can be divided into: 1. Costs due to failure occurrence, including the costs of financial losses, losses due to delays, damages to the owner properties, liquidated damages, thirdparty damages and fatalities; 2. Costs of prevention of failures, including the cost of proper investigation, competent materials, acceptable engineering, strict quality control, suitable installation/construction and any other factors that could be considered as preventive measures of failures.  The total costs are the sum of these costs, they may be expressed using the following formulation: Total failure costs = costs due to failure occurrence + costs of failure prevention



38


 Failure occurrence costs presumably are directly proportional to the probability of failure whilst costs for the prevention of failures are inversely proportional to the probability of failure

 aiming at no failures seems to be not in the best economic interest of contractors and owners. Allowing for a certain probability of failures may reduce the total costs; this is luxury that cannot be afforded for some projects or where lives are in danger. The engineering of certain projects may be categorized into the following three categories: 1. Pragmatic engineering: This type of engineering seeks the lowest failure costs. 2. Principled engineering - lower failure probability than pragmatic engineering: Some owners and design engineers (and contractors but to a lesser degree) would prefer to have lower probabilities of failure for ethical reasons. 3.

Unprincipled engineering - higher failure probability than pragmatic engineering: The involved stakeholders in a certain projects (most probably contractors) may deliberately or unintentionally take a “risky” approach of reducing the costs.` Learning from Failures: A Geotechnical Perspective


39


7 – The Causes of Failures Nine out of ten recent failures occurred not because of inadequacies in the state of the art, but because of oversights that could and should have been avoided.” R. Peck

A sinkhole, Guatemala City, 2010. The hole swallowed a three-story building. Learning from Failures: A Geotechnical Perspective


40

International Conference on Forensic Civil Engineering, Nagpur, India, 21-23 January 2016   

As, there are always uncertainties underneath the Earth surface, variability and unforeseen conditions are often the first accuser when a ground failure occur. some failures seem to be inevitable because of the complex nature of ground and groundwater as well as the limitation of our understanding of the geomaterials. Szechy (1961) state the following causes for failures: 1. Absence of Preliminary Investigation 2. Unsatisfactory Preliminary Investigation 3. Unsuitable Superstructures 4. Unsuitable Foundations 5. Foundations of Different Types Under the Same Building 6. Excessively Rigid Foundations 7. Incomplete Assessment of Effects of Loads 8. Unsuitable Methods of Dewatering 9. Faulty Excavation 10. Faulty Construction 11. Defective Workmanship and Materials 12. Inappropriate consideration of the groundwater 13. Application of additional loads 14. Landslides 15. Damage due to floods 16. Changes of water-content of soil 17. Effects of frost, changes of temperature, drought, and vegetation 41 Learning from Failures: A Geotechnical Perspective Agaiby, S.W. & Ahmed, S.M.


 Most of the failure causes are related to the Human factor.  The ignorance-failure cycle seems to be inevitable especially if new techniques as there is no way to obtain complete and reliable knowledge in the face of errors, uncertainties, limited data and human imperfections

Dunning– Kruger effect

A Main Cause of Failure

 Shaffner (2011) noted that clear potential foundation problems posing significant risk may be kept unnoticed for long by many engineers.  He considered that overlooking a possible failure pattern is similar to a cognitive bias called Dunning– Kruger effect (Kruger & Dunning, 1999) which illustrate how relatively unexperienced individuals suffer from mistakenly assessing their ability to be much higher than is accurate. Learning from Failures: A Geotechnical Perspective


42


8 – Approaches to Overcome Oversights “Don't be afraid. fear won't prevent death, but it prevents you from living your life.” Naguib Mahfouz

A landslide, Nachterstedt, Germany, 2009 Learning from Failures: A Geotechnical Perspective


43


Proper Site Characterization “The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge.” S. Hawking

 Geotechnical investigation is one of the most crucial geotechnical elements. ICE (1991) showed that 3550% of the projects with cost and/or time overruns suffered from ground problems due to the unforeseen ground conditions.  Cost and time overruns are serious concerns that may arise due to improper site investigations (Littlejohn et al., 1994).  Investigation programs may comprise boring, sampling and insitu testing, laboratory testing and geophysical surveys.  The interpretations and analyses of the data should consider geology, site history and environment.  The recommendations on the favorable/unfavorable locations, economic and safe design, and prediction of potential risks are inferred. Learning from Failures: A Geotechnical Perspective

(after Nazir, 2014)


44


 A proper site investigation work is carried out by the combined effort of a specialized geotechnical engineer and a competent ground investigation contractor. Geotechnical engineers should attempt to answer the following questions while envisaging the ground investigations (Nazir, 2014): 1. What is known about the site? 2. What is not known about the site? 3. What needs to be known?  Based on the answers to the above questions, the following 1. What type of investigations are needed?

2. Why are they needed? 3. Where should the actual field work be performed?

(after Nazir, 2014)

4. How will the work is be done?

 Accordingly, the site investigation program is envisaged including the stages of investigation, the type of field work, the number and location of boreholes, type and number of sampling, type and number of testing, etc. Learning from Failures: A Geotechnical Perspective


45


Quantifying Uncertainties in the Design “Natural soil is never uniform. Its properties change from point to point while our knowledge of its properties are limited to those few spots at which the samples have been collected.” K. Terzaghi

 Uncertainty in geotechnical parameters necessitate the adoption of reasonably conservative values of geomaterials stiffness and strength.  Reliability and probabilistic approaches constitute a key basis of limit states geotechnical design codes (e.g., Eurocode, AASHTO and others).  The use of these statistical concepts is integral to the appropriate selection of characteristic value for geotechnical properties and design parameters. Characteristic parameters are the worst credible design values that are selected on the basis of a reasonable engineering assessment and design.  Additionally, geotechnical engineers should consider the site’s geological setting, stress history, geomorphology, hydrology and other controlling geotechnical/geological features such as existence of buried channels, pre-sheared zones or slip surfaces, permeable bands within clays, etc. These aspects may significantly influence the geotechnical behavior of the ground; yet, they cannot be simply represented by the codes common approaches such as the partial factors analysis (Simpson, 2011). Learning from Failures: A Geotechnical Perspective


46


Validated Modeling “All models are wrong. Some models are useful.”

G. Box

 Peck (1981) highlighted that the geotechnical problems are fundamentally nonquantitative and hence solutions are principally non-numerical.  Yet, the recent unprecedented advances in software and hardware technologies allow geotechnical engineer to perform complex nonlinear three-dimensional analyses without much difficulties.

 These powerful tools may potentially lead to failures especially if the engineers who perform the modeling do not have the required engineering experience. The currently available powerful geotechnical software is only as good as their user.

A PLAXIS numerical model for a tunnel

 The ideal approach to validate the computed results from advanced modeling is to perform calculations and/or assessment that do not involve the use of the numerical software. In some cases, closed form and hand solutions are available but in many cases, engineers can only resort to laboratory models or field observations and/or measurements for calibration. They may also validate the computer analyses by using two different software for the same model (Ong, et al., 2006; Ong, 2008). Learning from Failures: A Geotechnical Perspective


47


Engineering Judgment “Theory and calculation are not substitute for judgment, but are the basis for sounder judgment” R. Peck

 Engineering judgment has always played a predominant role in geotechnical engineering prior to the invention of modern computer-aided design.

 At that time, design was performed mainly based on the experience gained from previous similar works.  Yet, at the current time where computer-based design and analysis is very common, engineering judgment is still indispensable to the successful engineering as geotechnical problems cannot yet be solved by the advanced numerical analysis without having reasonable input parameters is reasonable.  The output of analyses from computers needs also to be judged wither to be accepted, or rejected on the basis of its reasonableness (Peck, 1981 & 2006). Learning from Failures: A Geotechnical Perspective


48


Peer Review

“The man with insight enough to admit his limitations comes nearest to perfection.” J.W. von Goethe

 Geotechnical projects need the close cooperation of experts of various disciplines (e.g. geology, geotechnical engineers and geophysicists) in addition to the opinions and feedbacks of the structural and hydraulics engineers.  It is expected that highly qualified experts usually arrive at rather similar opinions although the opposite is not infrequent.  Diversity of opinion of experts have always been a spark for further development and innovations (Sowers, 1993; Bea, 2006).



49


Monitoring and Risk Management

“Residual risks are unavoidable, because ground is the greatest uncertainty in civil engineering.” H. Brandl

 Monitoring of structures during the construction stage is considered one of the most important tools for the mitigation of uncertainties in geotechnical engineering. It provide a quantitative tool for the geotechnical engineers to learn from the ongoing and completed projects and to ascertain the design assumptions (Dunnicliff, 1993).  Peck (1969) presented the Observational Method, which calls for a continuous re-assessment of the design parameters by utilizing the results of the monitoring programs. The possibility to modify the design and strengthen the structure during construction is a fundamental benefit of the Observational Method.  The Observational Method establishes the general framework for the risk management procedure that should be considered to avert possible failures (Powderham, 2002).  The concept of geo-risks has been widely adopted (Lacasse & Nadim, 1998; Chapman et al., 2007). Brinded (2000) defined the risk management as the processes of risk understanding (Risk Analysis) and compared it to the societal tolerated risks of a similar nature (Risk Evaluation), allowing a decision regarding the requirements to control of the risk.  Deltares (formerly known as GeoDelft) developed the GeoQ-method for risk management for controlling ground-related risks (Van Staveren, 2006). Learning from Failures: A Geotechnical Perspective


50


9 – Lessons Learnt from Some Previous Failures “All men make mistakes, but only wise men learn from their mistakes.” W. Churchill

1

2

3

4

Piping failure of the Teton dam in 1976. The four photographs are taken at 30 minute intervals Learning from Failures: A Geotechnical Perspective


51


Failure of St. Francis Dam, California, USA, 1928  St. Francis Dam was a 57m high, 213 m long, curved concrete gravity dam built for the City of Los Angeles in 1924-1926. It stored 47 million m3 of water.

 Just before midnight of March 12, 1928, the dam collapsed and the resulting flood took the lives of 431 people.  The collapse of the St. Francis Dam is considered to be one of the worst American civil engineering disasters of the 20th century.  This failure is also considered the second greatest catastrophe in California's history after the 1906 San Francisco earthquake and fire. This disaster marked the end of its designer's career (Grunsky & Grunsky, 1928; Outland 1963; and others). Learning from Failures: A Geotechnical Perspective


52


 There are many anticipated causes of failure that are believed to include the following (Rogers, 2002 & 2007): 1. The east abutment was founded on mica schist interspersed with talc with a greasy texture. This location had old landslides prior to the dam construction. 2. The western abutment of the dam was rested on a fault comprising red conglomerates which swelled upon wetting. A piping instability appeared to occur upon the water impoundment of the reservoir behind the dam. 3. The dam height was increased by 6m during construction without any increase in base width 4. The dam, after the increase of its height, became unstable in overturning.  This failure lead to many dam safety and maintenance legislations and guidelines in California and other states. This failure also lead to the introduction of the professional engineering registration. Learning from Failures: A Geotechnical Perspective


53


Liquefaction Failures in Niigata Earthquake, Japan, 1964  The Niigata earthquake occurred on June 16, 1964 with a magnitude of 7.5 and an epicenter located about 50 kilometers to the north of the Niigata city.  A great part of the city of Niigata is built on the recent deltaic deposits from the Shinano and Agano rivers (mainly loose sands)  The earthquake shaking caused substantial liquefaction.  Subsidence of up to 140 cm was observed over the large areas that suffered from liquefaction.

A liquefaction failure of apartment buildings that were built on reclaimed land by the Shinona River.

 The occurred failures demonstrated the importance of considering the liquefaction in design of structures in the seismic active zone. Nowadays, liquefactions analyses and checks are commonly applied in everyday design to avert the possible failures that were observed in earthquakes (Ohsaki, 1966; Seed & Idriss, 1967 & 1971). Learning from Failures: A Geotechnical Perspective


54


 The Showa Bridge in Niigata collapsed in the Niigata 1964 earthquake.  The bridge had a length of 307m with spans of 28m. Each span was supported on nine 600mm diameter steel piles of wall thickness of 9 to 16mm.  Some of the bridge girders rested on movable joints to allow for the thermal expansion.  After the earthquake, lateral spreading was observed in the loose sands at the riverbanks and it is suspected that it caused the failure of the bridge (Fukuoka, 1966; Kramer, 1996; and others).

Collapse of the Showa Bridge after Niigata Earthquake, 1964



55


Rissa Landslide, Norway, 1976  Quick clay is a highly sensitive marine clay that exists in Canada, Norway, Russia, Sweden, Finland, the United States and other locations around the world.  When it is undergoes strain, its behavior changes from that of a soil to that of a fluid.

 Quick clay is believed to be the cause of many retrogressive landslides that often initiate at riverbanks and the edges of lakes and progress away from its starting point at slow walking speed to kilometers inland consuming everything in its path.  Rissa landslide took place on April 29, 1978 in Norway. The slide debris was about 6 million m3. There were 40 people within the slide area (about 330,000 m2)  The slide is documented by a film that was taken by two amateur photographers.  This failure substantially added to the knowledge of the engineering community about the quick clay behavior and associated landslides (Gregersen, 1981; Ter-Stepanian, 2000; Torrance, 2012). Learning from Failures: A Geotechnical Perspective


56


Failure of Teton Dam, USA, 1976  The Teton Dam, a 93-m high zoned earthfill dam across the Teton River. It was designed by the U.S. Bureau of Reclamation. The reservoir behind the dam was 27.2 km long with a total capacity of 355 million m3.

The Initial sign of the failure at the right abutment

 It was designed as a multi-purpose facility that would provide irrigation water, flood protection, electrical power, and water-based recreation.  The rock at the dam site consists of hard, welded, rhyolitic ash-flow tuff dated at 1.9 million years which sits on top of sedimentary rock. Along the axis of the dam, the tuff ranges in thickness from about 15m in the left side of the channel section to more than 150m feet under the right abutment.

 The tuff in the right abutment is foliated and strongly jointed. Boreholes showed that it was highly fissured, a condition unlikely to be helped by the Bureau’s favored method of grouting. Learning from Failures: A Geotechnical Perspective


58


 The dam failed just as it was being completed and filled for the first time at 11:57 AM on June 5, 1976. The Failure was initiated by a large leak near the right (northwest) abutment of the dam, about 39.6m below the crest.  When the water level of the reservoir rose to the bottom of the deepest joints, water simply flowed through the open vertical joints, which eroded the crack into a large tunnel (piping failure).

The piping failure of the Teton Dam

 After the dam failure, some of the joints were observed to be tight, others open as much as 5 inches. Some joints are lined with calcite, others are filled with silt and rubble.  The collapse of the dam resulted in the deaths of 11 people and 13,000 cattle. The dam cost about $100 million to build, and the federal government paid over $300 million in claims related to its failure. Total damage estimates have ranged up to $2 billion. The dam has not been rebuilt. Learning from Failures: A Geotechnical Perspective Agaiby, S.W. & Ahmed, S.M.

59


Failure of the Nicoll Highway, Singapore, 2001  On 20 April 2004, during the construction of the Circle MRT Line - Stage 1- Contract 824, a 100-m length, 30-m depth section of the cut-and-cover tunnel suddenly failed near Nicoll highway causing the loss of four lives and the collapse of a substantial part of the main highway running over the tunnel.  The excavation support system included ten levels of preloaded cross-lot struts with two rafts of jet grouted piles (JGP) which was a novel excavation support system (COI, 2005).  Relatively large wall deflections occurred during the excavation; yet, the measured strut loads were smaller than the design calculated values. Accordingly, the project engineers were apparently unaware of the potential for a catastrophic failure.



60

International Conference on Forensic Civil Engineering, Nagpur, India, 21-23 January 2016  Possible reasons for the collapse including (Magnus et al., 2005; Whittle & Davies, 2006; Corral & Whittle, 2010; Ishihara, 2011): 1. Overestimating the undrained shear strength of the lower marine clay, which appears to be still underconsolidated. 2. The design was based on the effective stress strength parameters (c’, φ’) for the undrained condition and MohrCoulomb constitutive model, which seems to have overestimated the undrained shear strength profile for the underconsolidated clays. 3. Underestimated the deformations for the mobilization of the passive shear resistance in the JGP. 4. Underestimating of the earth-pressure on the diaphragm wall. 5. Detailing errors for the structural bracing system and its connection. 6. The diaphragm wall was designed to extend 3m below the soft clay into much stronger alluvium. However, at the location of the failure, it seems that the surface of the clay had been eroded by a buried channel. 

This failure resulted in additional research regarding constitutive modeling of soft clays and the applicability of the Observational Method in deep excavations that may undergo sudden failures due to the failure of the structural strut elements. Learning from Failures: A Geotechnical Perspective


61

International Conference on Forensic Civil Engineering, Nagpur, India, 21-23 January 2016 The landslide in Bingham Canyon copper mine, Utah, USA, 2013

 Kennecott’s Bingham Canyon mine is one of the largest man-made excavation in the world.  It has been in operation since 1906 and produces 25% of the copper used in the United States. It produced more copper than any mine in history.  The rocks at Bingham Canyon are sandstones, quartzites and limestones.  A landslide occurred on 10 April 2013. It produced rock fall debris of volume 65-70 million m3 with speeds reaching 160 km/hr. It is the largest non-volcanic landslide in North American history

≈ 1000m deep

 16 seismic events were detected in the mine area after the landslide over 400 km from the mine. The magnitude of the largest seismic event is 2 to 3.  The cost of the failure is about one billion dollars. Reinstatement works continued to 2015.  Due to the implemented dense instrumentation that detected the early signs of the failure, no life lost in this huge failure. Learning from Failures: A Geotechnical Perspective


62


2.5 km

Failure zone Oct. 2011

June 2013

Satellite Photos from Google Earth



63


Dave Petley* suggested that:

 A fill material might have been dumped on the slope.  There is a comparatively planar surface at the base of the slide. This would suggest a pre-existing weak zone (maybe a fault)

Fill

Fault

* http://blogs.agu.org/landslideblog/2013/04/30/analysing-the-bingham-canyon-mine-landslide-part-1-the-landslide-source-area/



64

International Conference on Forensic Civil Engineering, Nagpur, India, 21-23 January 2016 Chrys Steiakakis* suggested that the failure have occurred due to the scale effect. The rock may have behaved like cohesionless soil owing to the large excavation height.

Rock slope

Hoek et al.(2000)Soil-like slopes

Rock behave like soil Steep slope

Sjoberg (1996)

* http://blog.geotechpedia.com/index.php/2013/04/slope-failures-landslides-and-mines/



65


10 – Conclusions

“It is unwise to be too sure of one's own wisdom. It is healthy to be reminded that the strongest might weaken and the wisest might err.” Mahatma Gandhi

A landslide failure, Wangong, China, 2010



66


 Failures are not all evil. They can be more useful to engineers than successes if they are well-studied to answer the following important questions:  How to improve our performance?  What are the patterns of erroneous thinking and generalizations that we should avoid?  The most fruitful source of lessons in engineering judgment exists in studying case histories of failures and learning from the mistakes of others.  Geotechnical failures are mostly related to human errors Learning from Failures: A Geotechnical Perspective


67


 Most failures can be avoided if extra care and input from engineers having the relevant experience in geotechnical engineering were consulted.  The first and most indispensable tool to avoid failures is the proper engineering judgment that separates the significant from the insignificant details.  Failure numbers could be reduced by implementing proper and adequate geotechnical site investigations, and adopting more flexible/conceptual designs together with the application of the Observational Method (as opposed to rigid, fully-engineered design) and by applying strict site supervision and quality control. Learning from Failures: A Geotechnical Perspective


68

69