001-Research Brief-C for Submission Final 030313 Uploaded

8/9/2019 001-Research Brief-C for Submission Final 030313 Uploaded

1/10

I PROJECT TITLE

Accurate Prediction of Safe Life of Buried Pipelines

II AIMS AND BACKGROUND

This research will derive a new theory for the accurate prediction of the safe life of buried infrastructure, using metalwater pipes as an example. It will integrate material deterioration, soil mechanics, fracture mechanics and time-dependent reliability theory into a methodology to analyse the behaviour and failure mechanisms of buried metal

pipes subjected to simultaneous internal deterioration and external loads, including environmental loads. Theproposed research will advance the knowledge in deterioration science and failure theory and provide a sustainablesolution to the intelligent management of the vast asset of buried pipelines in the world. It will bring abouteconomical, environmental and social benefits both nationally and internationally.

The problem

The life expectancy of buried metal pipelines, such as cast iron pipes, can exceed 100 years [1] but the average age offailed pipes is much shorter than the estimated life expectancy. For example, the average age of failed water pipes isonly 47 years in the US and Canada [2]. It is noted that buried metal pipes are more prone to failure, defined ascollapse or burst, than ever before. Long service, coupled with aging, deterioration and damage of buried pipes,

exacerbates the situation. For example, it is reported in the UK and Canada that the failure rate of buried pipes is 39breaks per 100 km per annum [3, 4]. The Australian National Water Commission [5] also reported that water mainssuffer from 20 breaks per 100 km per annum on average and the cost on replacement of failed pipes has increased by10% annually since 2006.

Examples of the most recent pipe bursts that can be classified as catastrophic to the public are: (i) the sudden burst ofa 200 mm ductile iron water main in the CBD of Adelaide, resulting in chaos and heavy traffic disruption during peakhours on 23 July 2012, and substantial financial consequences (reported in the newspaper Adelaide Now); (ii) thesudden collapse of a 760 mm cast iron main in Cleveland, US in March 2008, which had been operating withoutproblems since its installation in 1880 and after cement lining in 1996 [6]; and (iii) the sudden bursting of a 686 mmsteel water main on 3 December, 2012 in Landsborough Road, Leicester, UK, which damaged about 50 properties,

closed roads for a day and resulted in the loss of water supply of 5,000 houses for several hours (reported on BBCNews).

It is apparent that pipe failures are a global problem with severe consequences and disruptions. These failures canoccur without any warning. The fact that they are buried underground makes the problem worse. The reoccurrence ofpipe failures with this nature has exposed the inadequacy and/or inaccuracy of current theories used for the predictionof the failures of buried pipes.

One lesson from these sudden failures of buried pipes is that the first principles of pipe behaviour in its lifespan andthe mechanisms of pipe failure under multiple influencing factors need to be understood at a fundamental level, andthat the time-variant uncertain nature of both the pipe behaviour and influencing factors needs to be accounted formore accurately. It also highlights the urgent need to develop a new theory, based on a new approach with a clearunderstanding of pipe behaviour, interaction with soil, all possible failure modes and advanced predictive methods.Without such a new approach, it is impossible to effectively prevent future unexpected failures. This is a seriousscientific challenge that demands considerable intellectual capability. The purpose of the proposed research is todevelop a new theory with such a new approach.

Various attempts have been made to develop a theory for service life prediction of buried pipes [!"#$], as have beencritically reviewed by the CIs. For example, Rajani and Makar [8] developed an empirical model that relates tensilestrength of cast iron pipes with defect size and geometry through a stress intensity factor. Sadiq et al. [9] used MonteCarlo simulation for risk assessment of cast iron water mains. Rajani and Abdel-Akher [10] used mechanistic models

and finite element method to estimate the safety factor of old cast iron pipes. Chiodo and Ruggieri[11]

developed aprocedure to determine the fracture toughness of pipes with circumferential surface cracks. Moore et al.[12]

nvestigated the soil–pipe interaction of buried cement pipes.

In Australia, numerous research projects related to buried pipes have also been carried out. For example, Moglia etal.[13] used an empirical model to predict the failure rates of cast iron pipes. Deghan et al.[14] developed a new


2/10

nonparametric technique for failure prediction of different classes of pipes. Gould et al. [15] undertook an exploratorystatistical analysis to investigate the effect of climate on the failure rate of water pipes. Melchers [16] proposed a bi-modal model to simulate the multi-phase corrosion of grey cast iron with underlying uniform corrosion and thesubsequent pitting corrosion in marine and atmospheric environments.

Preliminary studies have also been undertaken by the Lead CI Li. Mohebbi and Li (CI) [17] investigated the corrosionof cast iron pipes and found that pipe corrosion is dominated by pitting corrosion which can change the mode of pipefailure due to stress concentration. Li (CI) and Yang [3] then developed a method to determine the stress intensityfactor K for pipes with surface cracks and subjected to service loads. In applying fracture mechanics to reliability

analysis of buried pipes[18]

, Mohebbi and Li (CI) also found that soil movement can significantly affect the stressfield in the pipe. This issue will be addressed in this research.

A comprehensive survey of the published research (see VI References), including that from websites of fundingbodies, e.g., ARC, NSF (US), EPSRC (UK), NRC (Canada), suggests that for most metal pipes, e.g., cast iron pipes,research has focused more on single failure mode, e.g., by strength, than on multiple modes of failure, e.g., bystrength or fracture. However, observations of pipe failures, either from the field or from laboratories, show thatmany metal pipes, especially cast iron pipes, can fail by different modes, e.g., by fracture [10, 19], which is of brittlenature, i.e., sudden failures as cited above.

The survey also suggests that, in investigating pipe behaviour and failures, most current research has not considered

either or both of: (i) the microbial corrosion of the pipe which causes local damage and stress concentration and mayaffect the properties of pipe materials, such as fracture toughness; and (ii) the re-distribution of stress field due to soilmovement which affects the failure mode of buried pipes. In terms of approach, most current research has not usedeither or both of: (iii) prototype tests on pipes buried in soil to verify theoretical models; and (iv) the advanced time-dependent reliability method to account for the time-variant uncertain nature of both the contributing factors (causes),and the behaviour and failure mode (effects) of the pipe. These are the sources of inadequacy and inaccuracy ofcurrent theories used for predicting pipe failures and pose serious scientific challenges for the proposed research inderiving a new theory.

The solution

The proposed research will meet these scientific challenges with original and innovative solutions that address theproblems that hinder the accurate prediction of the safe life of buried pipelines. The specific objectives of theproposed research are as follows:

1)

the development of a rational stochastic model for metal corrosion that incorporates microbial corrosion in soilenvironments;

2) the investigation of the effects of soil movement caused by climate change and other environmental loads on thestress field in buried pipes;

3) the exploration of the effects of corrosion and other chemical agents on metal properties, in particular its fracturetoughness; and

4) the derivation of a new time-dependent reliability solution to account for the time-variant uncertain nature of boththe contributing factors and the behaviour and failure mode of the pipe.

III RESEARCH PROJECT

The Significance

Most stakeholders of pipe infrastructure, in particular, the industry and public, have recognised the severeconsequences of pipe failures and there is on-going application-focused research funded by industry, e.g., WaterService Association of Australia and Water Research Foundation (US). However, due to the lack of innovation in thetheory used for predicting the failure of buried pipes, reoccurrence of these disasters has not been prevented. This

nnovation is scientifically challenging and intellectually demanding. As such it requires a new approach and aconcerted effort from the research community to examine the fundamental science that underpins any applications.

The scientific significance of the proposed research is in advancing the knowledge of deterioration science ofmaterials (metal) and the failure theory of infrastructure (buried pipeline), incorporating metal corrosion, soilmechanics, fracture mechanics, and time-dependent reliability methods as demonstrated below.


3/10

Stress is a fundamental measure of the behaviour of built infrastructure. For the example of fracture mechanics, astress intensity factor K is used as the measure of pipe behaviour [20]:

( )( ) 2 , K t r f t ! " # = $

(1)

where r and ! are geometric parameters and t is time. In determining K , the scientific challenge is accurate modelling

of local pitting corrosion since it causes damage (cracking) and hence affects the correction function f (! , t ). Althoughcorrosion of metal has been widely researched, little has been done in the proposed complex yet real environment ofsoil. Furthermore, one of the important mechanisms of corrosion that is most relevant to buried pipes, microbial

corrosion, has not been considered due to the complexity of the underground environment. Another challenge is theeffect of soil movement, in particular climate change-induced fluctuation of saturation of soil since it causes stress re-

distribution and cyclic changes with time, and hence affects the stress field " . The widely projected climate change

s also expected to create extreme storm events and changes to the underground water table by altering rainfallpatterns and sea level [21], which will lead to soil movement and resultant changes to the stress-fields exerted onburied pipes.

The very nature of the randomness and time variance of all related factors should be taken into account in accuratelypredicting failures of buried pipes. As such it is more appropriate to use a time-dependent reliability method. Withthis method, the probability of pipe failure by fracture (for example) as a function of time can be expressed as

follows:( ) [ ( ) ] f c p t P K t K = !

(2)

where K c is the fracture toughness. The scientific challenge here is to derive a solution to Eq.(2) so that the time-dependent reliability method can be used. However, this is extremely intellectually demanding since Eq.(2)represents a typical outcrossing problem in reliability theory. Since Rice developed a general formula for outcrossingproblems in the 1940s [22] (known as the Rice formula) very few solutions have been derived. No analytical solution

to Eq.(2) exists when its terms and variables (e.g., K, " ) are non-stationary and non-Gaussian stochastic processes ascould be the case for buried pipes.

Also in Eq.(2), the fracture toughness K c is widely treated as constant but it has been suggested[23] that corrosion and

other chemical agents in soil can affect the fracture toughness of metal, which would make K c time-dependent andaffect the failure mode of the pipe. Scientific evidence for, and subsequent modelling of, the effect of corrosion andother chemical agents on fracture toughness K c is another innovative feature of the proposed research which willadvance the knowledge in deterioration science and failure theory.

The Innovation and Originality

With the above identified knowledge gaps, the proposed research will focus on the following innovations:

1)

a new model of metal corrosion that is developed from an understanding of the chemical physics in soilenvironments;

2)

stochastic modelling of the effects of soil movement on pipe behaviour and failure that incorporates climatechange and other environmental loads;

3) production of scientific evidence for, and stochastic modelling of, the effects of corrosion and other chemicalagents on material properties, in particular fracture toughness.

4) prototype tests on pipes buried in soil and subjected to corrosion and external loads; and5)

a new analytical solution to Eq.(2) for non-stationary non-Gaussian stochastic processes.

The research program designed to achieve these innovations is detailed in “Methodology”.

It is acknowledged that considerable research has been undertaken related to buried metal pipes as reviewed above

(see VI References) but this research is very different from others (whilst fully recognising their values) in thefollowing perspectives:

1) in its aim, i.e., to derive a new theory for the accurate prediction of the safe service life of buried pipes;2) in its approach, i.e., to examine the fundamentals of material and structural behaviour and failure mechanisms and

consider the time-variant uncertain nature of all factors involved;


4/10

3)

in its creativity, i.e., theoretical analysis coupled with a comprehensive and well planned laboratory study tounderstand pipe behaviour and failure mechanisms; and

4)

in its methodology, i.e., the integration of materials deterioration, soil mechanics, fracture mechanics andreliability theory.

With these features, the originality of the proposed research is very clear.

Advancing Knowledge

With these innovations and originality, the outcomes of the proposed research will advance knowledge in thefollowing scientific fields:

1)

Corrosion Science that will be enriched by a better understanding of the microbial corrosion of buried metals;2) Soil Mechanics that will be supplemented with the effect of soil movement on buried infrastructure;3) Fracture Mechanics that will be extended to the effect of corrosion and soil movement on stress intensity factor

and fracture toughness;4) Experimental methods that will include prototype tests of pipes buried in soil with corrosion and external loads;

and5) Reliability theory that will be enhanced with more analytical solutions to time-dependent problems.

The Methodology

To achieve the proposed aims and objectives the following work packages (WP) have been designed and integratedwith a feasible action plan, cost-effective budget and clear timeline for delivery. A combination of analytical,numerical and experimental methods will be employed to execute the designed WPs.

WP1 – Test on corrosion

Whilst there have been many studies on corrosion of metals, one important factor often missed is microbial inducedcorrosion. Furthermore, the relationship between the corrosion depth/rate and pipe failure by fracture or strength hasnot been well understood. Previous work [17] undertaken by CI Li and his colleagues has shown that localised orpitting corrosion is the dominant mechanism in corrosion of cast iron pipes. It has also been observed that the

microstructure of cast iron has a significant influence on corrosion depth. It is hypothesised that this may be thereason for the recent unexpected failures observed in water pipes. Experiments proposed here will address these gapsn knowledge.

Based on the CIs’ (Li and Setunge) previous research in corrosion and their comprehensive review of researchiterature, an experiment has been designed to examine the effect of the key contributing factors on corrosion and the

resultant corrosion depth: (i) pH; (ii) temperature; (iii) microstructure of the metal; (iv) presence of bacteria; (v)chemical composition of the exposed soils; and (vi) loads applied on the buried pipes. Only external corrosion will benvestigated in this research.

Three types of metal will be selected: (i) cast iron; (ii) ductile iron; and (iii) steel, since they have diversifiedmechanical and microstructure properties with different proportions of graphite, pearlite, ferrite and cementite.Specimens used in the tests will be a section of real pipe of 150 mm in diameter (e.g., DN150) with a length of 500mm and supported on stainless steel wedges. Corrosion will be induced in an environmental chamber simulating thereal service environment encountered underground, covering: (i) three chemical compositions of soil: sodic, sulphaterich, and saline soils; (ii) different types of microbial, e.g., sulphate reducing bacteria, iron-oxidizing bacteria, andcontents, e.g., 104-105 cells per gram, using the approach adopted by Hasan and Setunge (CI) [24]; and (iii) tensilestress on the pipe surface equal to the typical stresses induced by soil movement to be estimated in WP3.

Corrosion will be accelerated by increasing the concentration of the corrosive agents in the surrounding environmentat three levels: e.g., if the actual environment is pH of 6, the tests will be conducted at pH of 5, 4 and 3 so that the

corrosion at pH of 6 can be extrapolated. Similarly three levels of temperature will be used. The activity of anaerobicbacteria in changing the pH and temperature of the environment will also be accelerated, as observed in Hasan andSetunge (CI) [24]. Based on this experience it is estimated that significant pitting corrosion can occur in 2 years.

The number of tests will be determined by a factorial method adopted in Dignan and Li (CI) [25]. The key dataproduced is the corrosion depth, which will be measured using electrochemical measurement of polarisation


5/10

resistance of the pipe length, a pitting gauge and mass loss. The tests will run until the failure of the pipes, estimatedto occur in 2 years, so that the failure mode can be observed.

Identifying and examining the main contributing factors to corrosion depth and the cause/effect relation for pipefailure is the innovative outcome of this WP.

WP2 – Development of corrosion model

The corrosion progression will be analysed and characterised, and models for corrosion depth will be developed as afunction of contributing factors and time, based on laboratory experiments. It is rational to model the corrosion effect

as a stochastic process, due to a large degree of uncertainty of both the corrosion process and its contributing factors,and to be consistent with the advanced time-dependent reliability methods (see WP6), as follows:

( , ) ( , ) ( )m c

c t c t ! = "E E E (3)

where c(E, t ) is the corrosion depth on the pipe wall; the vector E is the contributing factor as identified in WP1 and

t is time. In Eq.(3), cm(E, t ) is the mean value function of corrosion depth and # c(E) is the variation functionaccounting for all random characteristics of the corrosion process and its contributing factors. Mathematicalregression will be readily employed to derive the mean function cm(E, t ) with the data produced in WP1. The

variation function # c(E) will be derived from the classic theory of statistics and Monte Carlo simulation techniques.

Experience in related corrosion research [3, 17, 18, 24, 26] has shown that models based purely on collected data, without

significant theoretical inputs and understanding of the underlying corrosion science and mechanics, are unlikely to beof much use in prediction. The model to be developed in this research will be based on corrosion science andchemical physics observed from experiments in real world service conditions to be simulated and controlled in theaboratory.

Developing a stochastic model for metal corrosion in soil environments, considering the time-variant uncertain natureof all factors involved, is the innovative outcome of this WP.

WP3 – Study on effects of soil movement on stress field in pipes

In addition to service loads, environmental loads can also lead to soil movement which significantly affects pipe

behaviour and can result in its failure. For example, long droughts result in a decrease of soil saturation and anncrease of soil suction and cause contractive deformation of soils. On the other hand, rainfall causes an increase ofsoil saturation and a decrease of soil suction, which may lead to either swelling or wetting collapse of soils. Widelyexpected climate change will alter the existing rainfall/evaporation pattern, temperature cycle, and the currentunderground water level, and change environmental loads further in the long term. Buried pipes will deform as aconsequence of soil movement, leading to a re-distribution of the stress field in the pipes, as shown in Fig.1.

Several climate parameters influencing water tableand soil moisture were established in a recent projectcompleted by CI Setunge [26]. These climateparameters will be integrated into a recently

developed hydro-mechanical interactive constitutivemodel [27] for soils by CI Zhou to predict soilmovement in different climate scenarios. Thepredicted soil movement will then be inputted asknown displacement boundary conditions into acommercial finite element program, e.g., ABAQUS,to simulate the stress field in the pipe under bothenvironmental and service loads. The resultant stresswill be modelled as a stochastic process in the sameform as Eq.(3) because soil parameters and loads aretreated as time variant random variables.

Simulating the stress field in buried pipes undervarious service and environmental loads anddeveloping a stochastic model of the stress is the innovative outcome of this WP.

Evaporation Rainfall

Ground

Surface

Ground

Surface

Scenario 1: Initial state (after installation)

Soil shrinkageSoil expansion

Scenario 2: Real world service state (under environmental loads)

pipepipe

pipepipe

!"#$% "#$% &%'()*+,#(- &.% ,( /(#0 *(1%*%-,

Datum Datum

Datum Datum


6/10

WP4 – Examination of corrosion effect on fracture toughness

Corrosion and other chemical agents can lead to a reduction in the fracture toughness of metals. For example,corrosion reactions can generate hydrogen leading to embrittlement of metals. This has not been explored by otherresearchers. It is hypothesised that this may be another reason for recent unexpected sudden, i.e., brittle, failuresobserved in water pipes. Experiments proposed here will address these gaps in knowledge.

The same specimens as those of WP1 will be used in the experiment. After different degrees of corrosion, asmeasured by corrosion depth, tests will be conducted on their fracture toughness according to ASTM-E1820-01. Amicroscopic investigation to determine changes in the microstruture of the metals during the corrosion process and at

different degrees of corrosion will also be conducted. The investigation will provide an understanding of howcorrosion changes the properties of the material. The experience and skills of CIs Li and Setunge in corrosion relatedtests will ensure the success of the tests.

Once the change of fracture toughness of the selected metals as a function of corrosion depth is established, astochastic model in the same form as Eq. (3) will be developed. The model for fracture toughness as a function ofcorrosion depth will be the first to be developed in this research field.

The outcome of this WP will be of far-reaching significance to material and structural deterioration, opening newareas of research on how corrosion affects material properties and furthering the knowledge of deterioration science.

WP5 – Test on prototype buried pipe If theoretical models are to be of use, they must be calibrated against data obtained under real service conditions.Experiments have been designed to verify the results predicted by the models to be developed in this research. Aprototype pipe 4 meter long of the same materials as those in WP1 and with diameters of 100 mm, 150 mm and 250mm (since about 80 - 85% pipe population are small pipes, i.e.,


7/10

WP6 – Derivation of solution to probability of failure

The safe service life of buried pipes will be predicted based on risk assessment of pipe collapse (i.e., probability offailure assuming the same consequences). The probability of pipe collapse will be determined using advanced time-dependent reliability theory [28], as expressed in Eq. (2) and outlined in Fig. 3, in which R is the structural capacity(e.g., strength or fracture toughness), S is the load effect (e.g., stress or stress intensity factor), f R (r|t=ta) is probabilitydensity function for R at time ta, f S(s|t=ta) is probability density function for S at time ta, and tL is the life time. Eq. (2)represents a typical outcrossing problem (the stochasticprocess crosses out of a defined safe domain) to which theRice Formula is the general solution. The Rice Formula

consists of two parts: (i) the probability of failure at timezero, which can be solved using existing methods [28], e.g.,first order reliability (FOR) method, and (ii) the outcrossingrate as a function of time, to which there is no existinganalytical solution when the stochastic processes are non-stationary and non-Gaussian. In this research theoutcrossing rate will be derived based on the concept of firstpassage probability and stochastic process theory.

The probability of pipe collapse can be predicted usingEq.(2) for the selected group of pipes under a variety of

environmental, service and ground conditions during theirwhole service life. The safe service life for the selectedpipes can be determined for an acceptable risk due to thenature of the time-variance of this method.

The derivation of a solution to the outcrossing rate under the combined action of corrosion, soil movement anddamage events is another innovative outcome of the proposed research, contributing to time-dependent reliabilitytheory, which is also applicable to many other engineering problems.

WP7 – Integration of developed models and solutionAll models and solutions developed and/or derived will be integrated into a theory with detailed descriptions and

derivations. An algorithm will be developed and coded into a user-friendly computer programme as a tool tomplement all computations of risk of pipe collapse under a variety of environmental, service and ground conditions.

With this tool, a quantitative risk classification can be produced for a given pipeline system. This research capabilitywill cement CIs’ leading position in the world in this research field.

Plan for the Proposed Research

The actions and timeline for the proposed research are planned as follows.

TasksMonths

6 12 18 24 30 36WP1-Test on corrosion

WP2- Development of corrosion model

WP3-Study on effects of soil movement on stress field in pipes

WP4- Examination of corrosion effect on fracture toughness

WP5-Test on prototype buried pipe

WP6- Derivation of solution to probability of failure

WP7- Integration of developed models and solution

Funds are requested from the ARC primarily for employment of a full time Research Assistant and a half timeTechnician mainly for laboratory work whilst CIs focus on theoretical development of the proposed research.

National Research Priorities and Priority Goals

The outcomes will advance the knowledge in the complex deterioration of buried pipelines and their failuremechanisms, with clear understanding of corrosion of pipes, fracture of corroded pipes, soil pipe interactionncorporating climate change and time-variant uncertainty of all factors using the theory of reliability. Based on this

R ,S

f R(r | t = ta)

f S(s | t = ta)

ta tb

f R(r | t = tb)

f S(r | t = tb)

tL t

S (t)

0 Typical load effect

Trace S (t)

Time-dependent reliability problem

!"#$ & "#$%&' ()#' *&+ +,)- .+#',/$,&0


8/10

knowledge accurate prediction of pipe failures and its safe life can be achieved. This advanced knowledge willsubsequently bring about technological innovations, e.g., reliability-based intelligent management of buried pipelines,nnovative remedial measures of deteriorated pipelines, guidelines on design of new pipelines and development of

new pipe materials. These innovative technologies will sharpen the competitive edge of Australian industrynternationally. Therefore the proposed research aligns very well with the national research priority of “Frontier

Technologies for Building and Transforming Australian Industries” specifically under the goal of “Frontiertechnologies”.

Economic, Environmental and Social Benefits

In addition to scientific innovation and advancing knowledge, the outcomes of the proposed research will enhance thesustainability of buried infrastructure by pro-active and intelligent management based on frontier technologies. Thiswill create far-reaching benefits to the Australian and international community. The economic, environmental andsocial benefits will be derived from:

1) improved serviceability of pipeline systems based on better understanding of the pipe behaviour;2) better planning for pipeline systems based on accurate prediction of safe service life;3)

updated guidelines for intelligent management of pipe assets based on developed models and methods;4) preventing environmental pollution and flooding based on accurate prediction of pipe failures;5) preventing disruption of the daily life of the public based on accurate prediction of failures and mitigation

measures;6) potential savings based on preventing premature and avoidable failures of pipes (see “Value for Money”); and7)

creating a culture of pro-active and intelligent management of pipe infrastructure through research andinnovation.

Value for Money

The proposed research will produce good value for money. Whilst the savings from prevention of unexpectedcollapses of buried infrastructure are difficult to evaluate (but are at least hundreds of millions of dollars), savingsfrom capital expenditure on buried pipes can be estimated. For example, the annual cost for the replacement of failedpipes is estimated at $115 million, increasing by 10% annually [2]. This cost is ultimately borne by the public, i.e.,

taxpayers. If these failures could be predicted more accurately, using the developed models and methodology, so that5% of the pipes could serve for one more year (which is a conservative estimate), the potential annual savings are$5.75 million. Funds requested for the proposed research to create this benefit are only $314K, i.e. about 5% of oneyear’s savings. This is a significant cost/benefit ratio.

IV RESEARCH ENVIRONMENT

Research Strategy and Directions at RMIT

As a well-established university of technology and design, RMIT focuses on solving critical global problems withsmart technological solutions. This project directly aligns with RMIT’s strategic plan where smart technologysolutions, sustainability and climate change and the future of cities are key interdisciplinary research topics endorsedand supported by the university. RMIT has identified sustainable systems as one of key research areas. The outcomesof the proposed research will be a fundamental understanding of the failure of buried metal pipelines leading to thedevelopment of tools and technologies for reducing the economic, environmental and social impacts caused byunexpected failure of buried infrastructure, and enhancing the sustainability of buried infrastructure systems. Thestrong support of the proposed research by RMIT is demonstrated by the cash contribution of $156,139 to support aPhD studentship directly working on the proposed research and other costs on experiments and disseminations.

Adequacy of the Research Environment in the School

The research will be conducted in the School of Civil, Environmental and Chemical Engineering at RMIT. CI Li isthe Head of School and CI Setunge is the Head of the Civil Engineering Discipline. The Civil Engineeringaboratories are well equipped for the proposed experimental program, together with the environmental and chemicalaboratories within the School. Each year the university spends about $700,000 on capital equipment for the School.

This has allowed the School to develop cutting edge facilities in material durability testing, including a largeenvironmental chamber, two smaller chambers, fully equipped corrosion tanks with salt spray, electrodes, loop


9/10

pumps, fully automated 500kN capacity creep rigs, 3000 kN servo controlled compression testing and 1000 kNtensile testing capability and repeat load automated triaxial testing rig. The School also has developed a pipe testingchamber, where flow rate can be changed to induce differential stresses. The School has direct access to SEM, XRDand EDAX equipment for corrosion and microstructural analysis through the School of Applied Science of RMIT.

With the support of University, the School has recently recruited two senior academic staff (one professor and oneassociate professor) in Civil Engineering to increase its research activities and profile. In 2012, the School invested in20 postgraduate research scholarships and the equivalent of four Research Fellowships to enhance its researchoutputs. Of 18 academics in the Discipline of Civil Engineering, there is a Fellow of ATSE, 2 professors, 4 associate

professors and 2 DECRA recipients (one is CI Zhou). The Discipline typically attracts around $1million in researchfunds per year.

Capability of the Research Team

CIs Li, Setunge and Zhou are members of the infrastructure research group, which is a strategically supported area ofrecognized research strength within the School. CI Li’s research expertise includes time-dependent reliability theoryand corrosion and its effect on structural deterioration. From 2003 to 2011, Li worked in the UK where he wasawarded four EPSRC (ARC equivalent) grants, among other national and industry grants. In one of EPSRC projects(GR/R28348), he led a multidisciplinary research team to develop a quantitative maintenance strategy for coastalstructures, which involved 5 academic investigators, 1 research fellow, 3 research students and 4 industrial

collaborators. The final assessment for the completed project is (EPSRC letter of 25/11/2005): (i) Research Quality –Internationally leading; (ii) Research Planning and Practice – Internationally leading; and (iii) Communications ofResearch Outputs – Outstanding. In the recent UK’s Research Assessment Exercise in 2008 (RAE2008), CI Li’sresearch outputs in materials and structural deterioration and service life prediction were rated 4-star, i.e., the worldeading (the highest rating).

CI Setunge has established expertise in infrastructure management covering bridges, buildings, seaports and sewerswith four current research grants including an ARC Linkage grant and an NCCARF grant in this area. She hasdeveloped accelerated testing of materials in the RMIT Civil Engineering laboratory where she has simulatedmicrobial corrosion of concrete septic tanks, corrosion of steel reinforcement and time effects on concrete. CISetunge has developed two integrated systems for deterioration prediction and cost optimisation of council buildings

and predicting effects of climate change on seaport structures.

CI Zhou was awarded a PhD degree in 2011. He successfully won a competitive ARC Discovery Early CareerResearcher Award (DECRA) in 2012 (one of three in RMIT). CI Zhou has made a significant contribution to theresearch field by developing constitutive models for various geotechnical engineering materials (e.g., unsaturatedsoils) and corresponding finite element algorithms to solve engineering problems.

The details of the CIs’ research record are in Section F.

Communication and Engagement

The outputs of this research will be communicated through publications in peer-reviewed international journals andnternational conferences and their proceedings. The target for journal publications is 6 papers per year. Targetournals include Corrosion Science, Geotechnique, ASCE Journal of Materials in Civil Engineering and ASCE

Journal of Engineering Mechanics. Target conferences include the: 19 th International Corrosion Congress in 2014;20th European Conference on Fracture in 2015; 12 th International Conference on Applications of Statistics andProbability in Civil Engineering in 2015; 24thInternational Congress of Theoretical and Applied Mechanics in 2016;ASCE Pipelines Conference in 2016; and 37th International Conference on Soil Mechanics and GeotechnicalEngineering in 2016. The outputs will also be communicated through a series of workshops and events with the targetaudience being pipeline sector. Publicity materials, e.g. brochures, posters, articles, etc. will be produced anddisseminated either by print or on the Internet.

V ROLE OF PERSONNEL

The research team has complementary expertise that is ideally suited to the accomplishment of the proposed aims andobjectives. CI Li will devote 20% of his time to the project and be responsible for the delivery of the proposedresearch as planned, providing overall leadership and guidance for the project based on his expertise and experience.


10/10

He will specifically work on model development as detailed in WPs 2 to 4 and on the derivation of analyticalsolutions as detailed in WP 6. CI Setunge will contribute 20% of her time on the design and development of thecorrosion experiments (WP1), fracture toughness tests (WP4) and prototype tests (WP5). She will also be responsiblefor the development of the corrosion model (WP2) and the integrated tool (WP7) combining the outcomes of WPs 2to 6. CI Zhou will contribute 20% of his time to developing stochastic hydro-mechanical constitutive model for soilsand implementing this model into FEM codes to predict soil movement and qualify the stress field of the pipes(WP3). He will also participate in determining soil parameters for prototype testing of buried pipes (WP5).

The Research Assistant will be full-time employed specifically for laboratory work (WPs 1, 4 and 5) where he/she

will be engaged in corrosion monitoring, downloading data from the data logger and verifying accuracy under theguidance of the CIs, fracture testing and prototype testing of the pipe as described under “Methodology”. TheTechnician is employed full time for the first year and 0.5 part time for the second year, specifically for developingtesting rigs, fabrication of corrosion tanks, fracture test specimens and the setting up of monitoring equipment. AResearch Student, fully funded by RMIT University, will primarily focus on research into pipe corrosion andpredictive modelling of the corrosion process under different influencing parameters. He/she will conduct thecomprehensive experimental study to understand the corrosion process and influencing parameters.

VI REFERENCES

1] Belmonte, H.M.S., Mulheron, M., Smith, P.A., Ham, A., Wescombe, K., and Whiter, J. (2008) Weibull-based methodology for condition assessment

of cast iron water mains and its application. Fatigue and Fracture of Engineering Materials and Structures. vol. 31.no.5. 370-385.2] Folkman, S. (2012) Water Main Break Rates in the USA and Canada: A Comprehensive Study . Report (April, 2012). the Utah State University,Buried Structures Laboratory.

3] Li, C.Q. and Yang, S.T. (2012) Stress intensity factors for high aspect ratio semi-elliptical internal surface cracks in pipes. International Journal ofPressure Vessels and Piping. vol. 96-97. 13-23.

4] Makar, J.M. (2000) A preliminary analysis of failures in grey cast iron water pipes. Engineering Failure Analysis. vol. 7.no.1. 43-53.5] National Water Comission Australia (2010) National Performance Report 2009-10 - Urban Water Utilities.

http://archive.nwc.gov.au/library/topic/npr/npr-2009-10-urban.6] Rajani, B., Lewandowski, J., and Margevicius, A. (2012) Failure analysis of cast iron trunk main in Cleveland, Ohio. Journal of Failure Analysis and

Prevention. vol. 12.no.3. 217-236.7] Ayatollahi, M.R. and Khoramishad, H. (2010) Stress intensity factors for an axially oriented internal crack embedded in a buried pipe. International

Journal of Pressure Vessels and Piping. vol. 87.no.4. 165-169.8] Rajani, B. and Makar, J. (2000) A methodology to estimate remaining service life of grey cast iron water mains. Canadian Journal of Civil

Engineering. vol. 27.no.6. 1259-1272.

9] Sadiq, R., Rajani, B., and Kleiner, Y. (2004) Probabilistic risk analysis of corrosion associated failures in cast iron water mains. ReliabilityEngineering and System Safety. vol. 86.no.1. 1-10.

[10] Rajani, B. and Abdel-Akher, A. (2012) Re-assessment of resistance of cast iron pipes subjected to vertical loads and internal pressure. EngineeringStructures. vol. 45. 192-212.

11] Chiodo, M.S.G. and Ruggieri, C. (2010) J and CTOD estimation procedure for circumferential surface cracks in pipes under bending. EngineeringFracture Mechanics. vol. 77.no.3. 415-436.

[12] Moore, I.D., Lapos, B., and Mills, C. (2004) Biaxial Testing to Investigate Soil–Pipe Interaction of Buried Fiber-Reinforced Cement Pipe.Transportation Research Record: Journal of the Transportation Research Board. vol. 1868. 169–176.

13] Moglia, M., Davis, P., and Burn, S. (2008) Strong exploration of a cast iron pipe failure model. Reliability Engineering and System Safety. vol.93.no.6. 885-896.

14] Dehghan, A., McManus, K., and Gad, E. (2008) Probabilistic Failure Prediction for Deteriorating Pipelines: Nonparametric Approach. Journal ofPerformance of Constructed Facilities. vol. 22.no.1. 45-53.

15] Gould, S.J.F., Boulaire, F.A., Burn, S., Zhao, X.L., and Kodikara, J.K. (2011) Seasonal factors influencing the failure of buried water reticulation

pipes. Water Science and Technology. vol. 63.no.11. 2692-2699.16] Melchers, R.E. (2013) Long-term corrosion of cast irons and steel in marine and atmospheric environments. Corrosion Science. vol. 68. 186-194.17] Mohebbi, H. and Li, C.Q. (2011) Experimental Investigation on Corrosion of Cast Iron Pipes. International Journal of Corrosion. vol. 2011. 17 pages.18] Mohebbi, H. and Li, C.Q. (2011) Application of Fracture Mechanics in Reliability Analysis of Corrosion Affected Cast Iron Water Mains. Proc. 12th

Int. Conf. on Durability of Building Materials and Components. 12-15 April. Porto. (on CD).19] Marshall, P. (2001) The Residual Structural Properties of Cast Iron Pipes - Structural and Design Criteria for Linings for Water Mains. UK Water

Industry Research.20] Hertzberg, R.W. (1996) Deformation and Fracture Mechanics of Engineering Materials. Chichester, Wiley.21] CSIRO and the Bureau of Meteorology (2007) Climate change in Australia: technical report 2007 .22] Rice, S.O. (1945) Mathematical analysis of random noise. Bell System Technical Journal. vol. 24. 46-156.23] Mahmoodian, M. and Li, C.Q. (2011) Structural System Reliability Analysis of Cast Iron Water Mains. Proceeding 2nd Iranian Conference on

Reliability Engineering. 24-26, October 2011. Tehran, Iran.24] Hasan, M.S., Setunge, S., Molyneaux, T.C.K., and Law, D.W. (2008) Determination of life expectancy of concrete septic tanks under biogenic

sulphuric acid corrosion. Futures in Mechanics of Structures and Materials - Proceedings of the 20th Australasian Conference on the Mechanics of

Structures and Materials, ACMSM20. Toowoomba, Queensland, Australia. 519-526.25] Dignan, M. and Li, C.Q. (2003) Experimental Investigation into the Effect of Fly Ash on the Fresh Properties of Self-Compacting Concrete. Proc. 2nd

International Conference on Structural and Construction Engineering, . 23 – 26th, September. Rome.26] Kong, D., Setunge, S., Molyneaux, T., Zhang, G., and Law, D. (2012) Australian seaport infrastructure resilience to climate change. Advanced

Materials Research. vol. 238. 350-357.27] Zhou, A.N., Sheng, D., Scott, S.W., and Gens, A. (2012) Interpretation of unsaturated soil behaviour in the stress-saturation space, I: Volume

change and water retention behaviours. . Computers and Geotechnics. vol. 43. 178-187.28] Melchers R E (1999) Structural Reliability Analysis and Prediction John Wiley & Sons

001-Research Brief-C for Submission Final 030313 Uploaded

Documents

Transcript of 001-Research Brief-C for Submission Final 030313 Uploaded