It is necessary that infrastructure systems in urban areas remain functional, especially
during various disasters. Drinking water should be provided without any disruption and waste
water disposed without any adverse environmental and health effects. However in Turkey,
infrastructure facilities and pipelines suffer heavy damages at every earthquake. Therefore, the
damages that may occur during an earthquake should be taken into consideration when
infrastructure pipelines are designed. These damages have been observed especially in recent
earthquakes, such as 1992 Erzincan (Mw= 7.9), 1995 Dinar (Mw= 6.0), 1999 Kocaeli (Mw= 7.8),
and 2011 Van (Mw= 7.2).
In addition to soil properties, material properties of pipeline, soil-pipeline interactions,
connection points and details of pipes play an important role when post-earthquake damages are
analyzed.
In this study, the displacements of infrastructure pipelines in areas of high earthquake risk
are estimated through a numerical model to assess likely damages. Furthermore, the relationship
between damage patterns and displacements of infrastructure systems after an earthquake is
examined based on varying soil types and conditions

Ali, Coşar

Koçak, Ali

Murat Ergenekon, Selçuk

Özçoban, Mehmet Şükrü

Epoka University

22nd International Balkans Conference on Challenges of Civil Engineering, BCCCE, 23-25 May 2013, Epoka University, Tirana, Albania.Determination of Pipeline Damages during Earthquakes ConsideringDifferent Soil FormationsAli Koçak1, Mehmet Şükrü Özçoban1, Ali Coşar1, Murat Ergenekon Selçuk1,1Department of Civil Engineering, Yildiz Technical University, TurkeyABSTRACTIt is necessary that infrastructure systems in urban areas remain functional, especiallyduring various disasters. Drinking water should be provided without any disruption and wastewater disposed without any adverse environmental and health effects. However in Turkey,infrastructure facilities and pipelines suffer heavy damages at every earthquake. Therefore, thedamages that may occur during an earthquake should be taken into consideration wheninfrastructure pipelines are designed. These damages have been observed especially in recentearthquakes, such as 1992 Erzincan (Mw= 7.9), 1995 Dinar (Mw= 6.0), 1999 Kocaeli (Mw= 7.8),and 2011 Van (Mw= 7.2).In addition to soil properties, material properties of pipeline, soil-pipeline interactions,connection points and details of pipes play an important role when post-earthquake damages areanalyzed.In this study, the displacements of infrastructure pipelines in areas of high earthquake riskare estimated through a numerical model to assess likely damages. Furthermore, the relationshipbetween damage patterns and displacements of infrastructure systems after an earthquake isexamined based on varying soil types and conditions.Keywords: Pipelines, Infrastructure Damages, Earthquake, Soil22nd International Balkans Conference on Challenges of Civil Engineering, BCCCE, 23-25 May 2013, Epoka University, Tirana, Albania.INTRODUCTIONLiquids and gases such as drinking water, wastewater and natural gas have to betransported through pipelines, which are commonly buried below grade during construction. It isnecessary that these buried pipelines stay operational in the event of disasters, such asearthquakes and floods. However, ability of pipes to remain operational depends on pipe type,soil properties, pipe diameter and filling material, and bearing conditions.Pipelines move with soil and become deformed as a result of movements arising fromearthquakes. It is necessary that such deformations stay within certain limits depending on pipematerial, in order to ensure that pipes are not cracked. Thus, earthquake behavior should beexamined depending on type of soil and pipe type. The variation and extent of deformations needto be calculated and verified that the limit deformation that a pipe can withstand is not exceeded.Pipelines are usually integrated and combined systems with long distances. The wholesystem becomes non-functional if any deformation that exceeds limits occurs at any point on thepipelines. Therefore, no cracks/damages should occur not even on a single point along entirepipelines.Important information has been obtained about the type, magnitude, location andproperties of damages on buried pipelines from past earthquakes, and work has been carried outon measures to prevent such damages. Pipe material has as much effect on earthquake-relateddamages of buried pipes as soil conditions and placement conditions.External loads applied on buried pipelines are caused by backfilling of the trenches, self-weight of pipes and its components, and traffic loads. Type of soil and filling, ditch depth,deformation of the pipe and construction method of the pipe are also very important. Thereforeamount of deformation depends on filling height, filling material, placement conditions, pipediameter, pipe type, pipe material and especially, external loads [1, 2, 3, and 4].Performance of the structure and the soil should be taken into consideration together(soil-structure interaction) in the design of buried structures. Soil on buried pipe exerts pressureon pipe. Pressure accumulates on pipes if they cannot sufficiently deform. However, soil weighton the pipe decreases due to soil resistance if the pipe is compressible. In this case soil archesover the pipe and the pressure on the pipe is decreases as a result of this arching effect. Thearching effect depends on soil resistance and pipe-soil interaction [5]. Vertical soil pressure on arigid pipe is greater than soil weight on the pipe. As a result, negative arching occurs, sidefillings settle and an additional pressure is exerted on the pipe. In this case stresses increasearound the pipe and decrease on the side fillings.On the other hand, vertical soil pressure on a flexible pipe is less than soil weight actingon the pipe. Positive arching occurs in this case and part of the pressure on the pipe is transferredto the side fillings. As a result, load on a rigid pipe is greater than load on a flexible one under22nd International Balkans Conference on Challenges of Civil Engineering, BCCCE, 23-25 May 2013, Epoka University, Tirana, Albania.the same conditions [1, 3]. Damages resulting from earthquakes on buried pipelines and places ofsuch damages have been classified according to soil conditions and type of damage, based onfield studies and various other works [6, 7, 8, and 9]. Methods similar to seismic behavior ofsuperstructures are used in works to estimate earthquake behavior of underground structures.However, behavior of buried pipes differs from that of superstructures [6, 7, and 11].Factors such as soil movement, liquefaction and landslide cause significant damagedepending on wave propagation resulting from earthquake. It increases with the ability to resistfault movements and friction forces acting on the pipeline. Flexible pipes show more resistanceduring fault movements. Displacements resulting from fault movements constitute the mainreason for damage of buried pipelines [11]. Eguchi (1982) has evaluated pipeline damagescaused by the 1971 San Fernando earthquake (Mw= 6.6) in North San Fernando Valley.The 1985 Michoacan-Mexico (Mw= 6.5) earthquake is a good example of high rates ofpipeline repair due to temporary displacement. This earthquake resulted in high damages inwater distribution pipelines. Ayala and O’Rourke (1989) have reported these damages andobserved that no liquefaction occurred and damages were essentially a result of earthquakewaves [12].Toprak (1998), O’Rourke et al. (1998) and O’Rourke and Toprak (1997) have presentedin their papers a database for the damages inflicted on the pipes in Los Angeles and forcharacterizing and examining these damages. Repair was necessary at 74 points in the watertransmission pipes (pipe diameter ≥ 600 mm) of the Los Angeles Department of Water andPower (LADWP) and Metropolitan Water District of Southern California (MWD) and at 1013points in the distribution pipelines (pipe diameter < 600 mm) of LADWP [13].The Hanski region of Japan, together with Kobe and Osaka were subject to intenseeffects of the 1995 Kobe earthquake. Very high damages have been observed especially in zoneswith permanent soil deformations. Old pipes and joints had much more damage compared to newand flexible pipes. Kobayashi et al. (2001) and Masuda et al. (2002) have carried out aresearch project from 1996 to 2000 in order to build "Proposed Applications for Gas TransferPipeline Design in Zones Subject to Liquefaction" by examining displacements resulting fromliquefaction, soil and pipe interaction, evaluation of deformations in pipelines and pipedeformations that satisfy conditions of no gas leakage [17, 18]. Japanese Water WorksAssociation (JWWA) established a technical committee after the Kobe earthquake. Thiscommittee made amendments in the regulations for earthquake resistant structures, based onresults of examinations of damages in pipelines [23].22nd International Balkans Conference on Challenges of Civil Engineering, BCCCE, 23-25 May 2013, Epoka University, Tirana, Albania.NUMERICAL INVESTIGATIONSNumerical investigation of dynamic behavior of pipes are investigated by two-dimensional Plaxis 2012 finite element software. Numerical analysis are carried out on acombination of two different soil types and three different pipe materials. Soil is defined as loosesand and dense sand (typical back-fill material) while pipe materials are taken as PVC, concreteand steel. It is assumed that pipe is constructed on a 30 cm height of bedding material in 1mwidth of trench and bottom of the pipe is placed at 3 m below the surface (Figure 1). Backfillmaterial is taken as same as the bedding material. All of the computations are executed for pipewith a diameter of 300 mm. numerical modelling of soil is achieved by using Hardening SmallStrain Model. Dimension of the numerical model is taken as 20mx15m. The material propertiesused in analyses are given in Table1.Figure 1. Mesh created for the numerical modelTable 1. Material properties used in numerical analysesSOIL E (kPa) c (kPa) (⁰) (kN/m3)Loose Sand 10000 1 30 1722nd International Balkans Conference on Challenges of Civil Engineering, BCCCE, 23-25 May 2013, Epoka University, Tirana, Albania.Dense Sand 60000 1 38 21Bedding 30000 1 37 20PIPEMATERIALEA (kN/m)EI(kNm2/m)PVC 4.5E4 9.38Concrete 1E6 208Steel 1E7 208040 seconds of the N-S component of 2010 Van Earthquake strong ground motion record,which has a peak ground acceleration of 0.19g is used in dynamic analyses (Figure 2).Figure 2. Acceleration time history of 2010 Van Earthquake N-S componentThe effect of soil type and material type on the displacement-time history is depicted inFigure 3. Results of the numerical analysis of pipe placed on dense soil show that totaldisplacement of pipe is about 0.115 m, while it is about 0.12m on loose soil. The totaldisplacement does not vary by a large amount. However, displacement rate is faster in loose soilsthan dense soils.-300-200-10001002000 20 40 60 80Acceleration ( gal)time (s)2010 Van EarthquakeAcceleration Time History22nd International Balkans Conference on Challenges of Civil Engineering, BCCCE, 23-25 May 2013, Epoka University, Tirana, Albania.Figure 3. Total displacement of pipes on dense and loose sandsHorizontal displacement of pipe is compared with the base of the model. Relativehorizontal displacement time history for different soil type and materials are given in Figure 4.Relative horizontal displacement of pipe is about 0.05m. The horizontal displacement differencebetween various types of pipe material are not significant. Also effect of soil type on thehorizontal displacement of pipe is not clear.0.000.020.040.060.080.100.120 10 20 30 40total displamcent  (m)time (s)dense sand pvcdense sand concretedense sand steel0.000.020.040.060.080.100.120 10 20 30 40total displamcent  (m)time (s)loose sand pvcloose sand concreteloose sand steel22nd International Balkans Conference on Challenges of Civil Engineering, BCCCE, 23-25 May 2013, Epoka University, Tirana, Albania.Figure 4. Relative displacement time history of pipeThe changes of the cross-sectional forces acting on pipe from the static condition to afterdynamic effects are applied for different soil type and different pipe material in Table 2. It isseen on the table that, soil type effects the cross sectional forces for the three different type ofpipes. Forces are much higher than the pipes seated on dense sand. Moment, shear forces actingon concrete pipes seated on loose soil are increased about 4% while it is about 27% in dense soil.Same behavior is seen also on steel and PVC pipes.Furthermore, the comparison of cross sectional forces shows that PVC pipes are the mostaffected pipes. Moments acting on PVC pipes placed on loose sand is about 76% while it is-0.06-0.04-0.020.000.020.040.060 10 20 30 40Relative Displacement (m)time (s)loose sand / steelloose sand concreteloose sand  pvc-0.06-0.04-0.020.000.020.040.060 10 20 30 40Relative Displacement (m)time (s)loose sand / steeldense sand concretedense sand  pvc22nd International Balkans Conference on Challenges of Civil Engineering, BCCCE, 23-25 May 2013, Epoka University, Tirana, Albania.about 26 % in steel pipes. The tendency of increment on cross sectional forces are same on pipesbuilt on dense sand.Table 2. Changes in cross-sectional forces acting on pipesLOOSE SAND/ CONCRETE DENSE SAND/CONCRETEM(kNm/m)V(kN/m)N(kN/m)M(kNm/m)V(kN/m)N(kN/m)Change %max 42.10% 41.34% 37.09% 26.14% 27.99% -32.39%min 38.53% 40.39% -2.13% 22.31% 24.47% -1.55%LOOSE SAND/STEEL DENSE SAND/STEELM(kNm/m)V(kN/m)N(kN/m)M(kNm/m)V(kN/m)N(kN/m)Change %max 31.89% 31.95% -4.04% 30.62% 35.21% -25.18%min 28.99% 30.61% -0.52% 27.43% 31.94% 0.90%LOOSE SAND/PVC DENSE SAND/PVCM(kNm/m)V(kN/m)N(kN/m)M(kNm/m)V(kN/m)N(kN/m)Change %max 76.40% 71.06% -31.17% 57.72% 56.08% -35.76%min 63.98% 70.63% 5.79% 49.01% 54.38% 1.52%CONCLUSIONS22nd International Balkans Conference on Challenges of Civil Engineering, BCCCE, 23-25 May 2013, Epoka University, Tirana, Albania.The effects of pipe material and soil type cannot be observed easily based on the resultsof numerical analyses. 2D analyses is insufficient to observe displacement behavior of a pipe.Thus, numerical analysis should be carried out on 3D to better understand the displacementbehavior of pipe. Moreover, experimental observation should be collected to support numericalfindings. The computation results of cross sectional forces acting on pipe show that materialproperties of pipe and soil type influence the results. PVC pipes are mostly effected pipe typefrom dynamic forces while steel pipes effected less. Also pipes on loose sand have much morecross sectional forces than pipes built on dense sand medium. To better understanding ofdynamic behavior of pipes, effect of bedding material, diameter of pipe and depth of pipeplacement should also be studied.REFERENCES[1] Mooser,A. P., (1990), “Burried Pipa Design”, Mc. Graw Hill, New York.[2] Linsley R. K. and Franzini J. B., (1955), “Elements of Hydraulic Engineering”, Mc. GrawHill Book Comp., New York.[3] Uslu M., (1979), “Prefabrike Kanalizasyon Kanalları ve Boru Hatları Döşenmesine aitTalimatlar,Alman Normları DIN 4033”, İller Bankası. Ankara.[4] Oglesby C. H. and Hichs R. 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Determination of Pipeline Damages during Earthquakes Considering Different Soil Formations

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Determination of Pipeline Damages during Earthquakes Considering Different Soil Formations

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