Summer Practice Report concerning the practice done in Eser Project and Engineering Office in Ankara

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1 Summer Practice Report concerning the practice done in Eser Project and Engineering Office in Ankara Name : Kadir Can Surname : Erkmen Student Number : Date of Completion of Report : Dates of the Summer Practice :

2 TABLE OF CONTENTS Preface p.3 Introduction p.5 Main Text p.6 Conclusion p.3 Appendix : Section Numbers p.33 Notation p.37 References p.38 Appendix : Daily Reports p.39

3 PREFACE Name of the company: Eser Project and Engineering Co. Inc. Address: Eser Green Building Turan Güneş Bulvarı Cezayir Cad Sk. No: 14 ANKARA Phone number: Fax number: Photo 1: Photo of Eser Project and Engineering Co. Inc. Activity areas: The company works in a broad area of different job range including dams, irrigation systems, residential buildings, industrial plants, water and waste water systems, hydro power plants, tunnels, highways, ports, bridges and other infrastructure systems. Brief History: Eser, since its foundation in 1986, has been active in the general contracting activities with a main focus on the infrastructure constructions. Promoted by a professional team highly experienced in international construction, Eser aims to undertake technical construction projects internationally and to be a competitive player in the geographical regions where it carries out its activities. (quoted from Eser s website) Board of Directors - İlhan Adiloğlu President and CEO M.Sc. Civil Eng. - Can Adiloğlu Vice President M.Sc. Civil Eng. 3

4 - Cem Adiloğlu Board Member B.Sc. Comp. Eng.,MBA - Mehmet Dönmez Board Member, General Manager M.Sc. Civil Eng. - Ertuğrul Tonguç Board Member, B.Sc. Geo. Eng. - İhsan Kaş Board Member, PhD. Civil Eng. - Mustafa Kemal Tufan Board Member, B.Sc. Civil Eng. Board of Directors Financial Adviser Legal Adviser General Manager Audit Manager Quality Manager Deputy General Manager Deputy General Manager Deputy General Manager (Finance) Hepp Design Mngr. Planning Mngr. HR Manager Dam Design Manager Geology Project Mgr Surveyin g Manager Tenderin g Mngr. Procure ment Mngr. Finance Mngr. Figure 1: Organizational scheme of the company There are a number of engineers employed in the company thus, presenting the names of all does not look likely however, for the sake of discussion, some are given in the following sentence. Ferit Güvenir Yalçın and Hüsamettin Burak Kaya works in the transportation department meanwhile, Cemre Çağlar works in the geology department and the department that I worked throughout my summer practice session is the dam planning department in 4

5 which three civil engineers employed whose names are Mesut Yapmış, Tevfik Erdoğan and Özlem Arslanhan. Introduction The aim of Adıyaman-Gömükan Dam Project, in the scope of GAP, is to store the flows of Çat and Han streams in Adıyaman-Gömükan Dam which is located in the western side of Adıyaman province and to provide irrigation for a net area of 6535 ha and a gross area of 761 ha in total. Adıyaman-Gömükan Dam Project is within the borders of Adıyaman province and the dam was planned to be erected on Han river. The catchment area of project zone is 17 km northern west of Adıyaman and goes through the Çamyurdu village. The distance from city center to the location of dam is 5 km. Final project report encompasses the parts some of which can be named as the description of project, engineering geology report, calculations, fixture project reports, site evaluation reports, bill of quantities, technical specifications and so forth. Apart from the afore-mentioned statements, Adıyaman has a slope of less than %10 but the slope of some places are %10-5 and may even go up to more than %5. Areas that have slope values exceeding %5 carry the risk of falling rocks and landslides at a notable level. When the Turkey s seismic map is taken into account, that zone falls into 1 st critical seismic zone and the most destructive earthquake was recorded as 7, in Richter s scale, among all times. Adıyaman has a terrestrial climate which means summers are hot and arid whereas winters are cold and rainy. The city s rainfall regime occurs heavily between autumn and spring and annual average rainfall amount is 5.6 kg/m. The work of Adıyaman-Gömükan Dam Project started on 4 September 01 based on the given authorization by signing an agreement between Eser Project and Engineering Co. Inc. and The General Directorate of State Hydraulic Works on 17 September 01. Some features of the project are as follows; main purpose of the project is irrigation and the drainage area is 46 km together with a m of minimum elevation and normal water level as m. Lake volumes are 6.00 hm 3 at the minimum level, hm 3 at normal water level and finally, hm 3 corresponds to active lake volume. Further, dam body is made up of sand gravel fill as its front face covered with concrete. The quantity of non porous fill is m 3 whereas semi porous fill is stated as m 3. Beside those, rock fill quantity is m 3 all of which makes a total of m 3. Additionally, the spillway described in the project is an uncontrolled one on right coast. Q input is m 3 /s and Q output is m 3 /s possessing a stilling basin of USBR type 3. When it comes to the sediment situation of dam, 5

6 in the words of project report, no stations with the ability of sediment measurement exists. In the planning report prepared by The General Directorate of State Hydraulic Works 0. Zone Management, total dead volume is accepted as 6 hm 3 which may come in 50 years from dam location. In terms of geotechnical qualities, first point that needs to be pointed out is that on the dam axis, on both coasts old ofiyolit sediments exist. Those units are weathered and their strength is medium to poor and can be easily crumbled. The scope of geotechnical report covers some quality measurements and the following statements are dedicated to those information. On the route of derivation tunnel, RMR, Q and Terzaghi rock mass classifications were done, pile and support systems were pointed out. RMR classification resulted as RMR = 30 and respectively, the rock stratum were labeled as weak rock. On the other hand, Q classification resulted as Q = 0.03 and respectively, the rock stratum were regarded as extremely weak rock. Lastly, according to Terzaghi classification system, the rock mass are on the fifth group and in this group, rock s physical property defined as cracked. Week 1 Throughout the history of mankind, the need for clean water has forced people to store water and with the aim of this, they built small structures to meet their daily water intake which is particularly valid for the ones living in areas where water resources are limited. It is known that dams were built and were in service in Egypt, Iran, India, Far East and Anatolia 5000 years ago which means dams are closely related with the ups and downs that ancient civilizations came across with. Dams are engineering structures that store water and are higher than 15 m built on valley faces and generally increases the number of benefits of water intake beside some special purposes. Pioneering dams were built for retrieving tap water mostly. The construction of dams takes a long time (3-10 years) and if destroyed, severe amount of financial and health losses occur. If the structure s height is smaller or equal to 15 m and the structure is a basic water storage compared to a dam, that is called a pond. Any kind of engineering structure except for a dam does not experience such static and dynamic forces as high as a dam does. Another significant feature of dam engineering is it chiefly relies upon experience and a fair amount of detail need to be grasped to be fully prepared. I collected some information about the benefits of dams from the engineers and draftsmen working in our company and what I learned is that numerous benefits can be enumerated however, there are some factors all of 6

7 which need attention when design stage is reached. Dams provide irrigation for agricultural fields, produce hydroelectrical power, supply the necessary water for drinking and industry constantly, protect the existing fields against floods, provide water transportation, fishery, location for water sports and a number of other positive contributions. Design considerations include protection of natural balance, historical artifacts and prevention of landslides, increase in the groundwater level and so forth. Plants that constitute a dam can be sorted as body and its plants, spillways, derivation plants, sluiceways and energy transmission plants in energy producing dams. It makes sense to put forward some remarks about physical factors that affect the selection of the type of dam. Before deciding a final type that is most suitable and economical as a solution, a couple of alternatives need to be inspected and pre-project studies should be done. Topographic information and analyses are the ones taken into account at the beginning. To give an example, on a valley where solid and high rocks dominate, the best option to take is a concrete dam however, if there are enough and satisfying materials available, a rock fill dam could be on the cards. Further, geology is another factor and has the potential to make an impact on other interrelated phenomena. To put it another way, rock foundations, gravel foundations, silty or clayey ones, non uniform foundations and a few others all alter the material selection and other critical decisions. Another factor that deserves attention is the height of dam. While selecting the type of any dam, those that are not too high provide less limiting criteria and that is why homogenous dams are preferable due to their ease of erection. Moreover, the amount and quality of the materials planned to be used play a major role especially in terms of economic considerations. For instance, for places where soil products are abundant but porous materials are not as much as that, homogenous dams should be selected. Spillways are also a key aspect during the process of selecting which dam is more suitable. When selecting a spillway the magnitude of plausible floods ought to be taken into account. Thus, the dams that are intended to be built on rivers that have high flood potential mostly affected by spillway characteristics. Additionally, the cost of a large spillway is a noteworthy part among the total project cost. Apart from what has been discussed so far, most of the dams that have been built up to now and planned to be built in the near future in Turkey are located in active earthquake zones. For this reason, the possible horizontal forces that may apply to a dam body when an earthquake strikes off can be taken as static equivalent horizontal forces however, the effect of layers all of which emerge foundation level on horizontal forces applying to fill must be bore in mind. Last but not least, benefit cost ratio 7

8 governs the commencement of the project namely and in other words, it may prevent a project from being a real physical one. My supervisor thouched on the possible reasons for a dam to fail. He said that a dam holding a large amount of water poses a threat to its adjacent territories and even though dam failures do not happen quite often, failures might occur due to the following reasons; - Earthquakes - Landslides that may cause wave movements and allow water to exceed the dam s upper body - Overlooked leaks that emerges on the dam s body due to the settlements on the soil where the dam situates - Water that comes from heavy rainfalls can surpass the crest elevation of a dam Margin of Safety Calculation One of the remedies thought for providing the safety of a dam is leaving a margin of safety between reservoir maximum level and dam crest. Otherwise, the waves emerged on a reservoir might exceed the crest. Following this, if extreme amount of water exceeds quite often, the material on the face of crests and downstreams may fade away due to erosion. In addition to what has been told so far, the waves above a crest pose a massive threat to the people and vehicles on crest. Normal Margin of Safety Explanation The factors that are taken into account during the design phase is successively as follows: 1) 1000 years repeated wind speed (U) ) Design Wave Height (H d ) 3) Swaggering of water wave through the base face of reservoir area (H w ) 4) Ascending of wave through upstream slope (R u ) Normal margin of safety is the addition of water swaggering height and the height of ascending waves. H normal = H w + R u 8

9 Minimum Margin of Safety It is the vertical distance allocated between the dam and maximum water level which was calculated as a result of flood routing. It is generally calculated with 10 years repeated wind speed. To decide the margin of safety: 1) Critical wind speed ) Wind setup 3) Critical wave height 4) Wave runup is calculated Total margin of safety is obtained by the addition of flood tide, wave runup and the relatively small amount decided by engineering judgement. HP = SK + DT + KM where, HP = Margin of Safety SK = Flood Tide DT = Wave runup KM = Arbitrary value selected by an engineer In the project that the company involved in, Adıyaman Gömükan Dam, thalweg elevation is m. According to what my supervisor said, wind values and the data of wind exposed lake lengths are given by meteorological engineers. However, for the sake of discussion, it shall be useful to shortly define what they are. Wind exposed lake length is basically the water setup distance as wind does not face with any kind of obstacle and wind values include the wind speed values as meters per second. During the calculation process of flood tide due to the wind setup, maximum fetch values are used rather than effective fetch values. Flood tide values are calculated using the following formula; S = 1.6V Fd D d (1) S = Flood tide ( above the static water level) V = Maximum wind speed through the fetch direction (m/s) F d = Direct fetch length (m) 9

10 D d = Average water depth through the fetch direction (m) Week While calculating the margin of safety, this equation was used. Another hydraulics part is wave height calculations that are roughly divided into two phenomena: significant wave height and design wave height. When it comes to significant wave height, first thing to say is that waves emerge on the water surface with the help of winds. In a certain distance of fetch and a certain amount of speed for at least an hour long, one third of the average of the waves created by project wind describe what significant wave height is. Significant wave height is determined with the aid of charts developed by researchers who previously worked on that subject depending on whether the condition is shallow or deep water. If the deepness is larger than 0.4L, it can be called as a deep water nevertheless, if it is smaller than 0.4L, shallow water case applies where L is the wave length in deep water. Wavelength value is obtained from wave period as follows L=1.56 T. Design wave length is calculated utilizing H d = 1.5 H s which corresponds to %5 in Longuet - Higgins wave continuity curve. If the number of waves that are higher than design waves is lower than 150 in a 50 years time, the calculation above is accepted as true. On the other hand, if vice versa is the case, the height that corresponds to 150 in wave continuity curve is selected as design wave height. During the calculation stage of margin of safety, wave runup on the dam s spring face is used rather than wave height and this runup depends on the material of spring face, slope, wave length and incidence angle. The formula used for this purpose is; = () where, R u = Wave runup (m) C u = Runup coefficient H d = Design wave height (m) Adıyaman Gömükan dam body has a slope of 1.6/1 (horizontal/vertical) and works as a concrete face rock fill dam. Wave runup ratios were found by utilizing the chart s smooth slope cluster created by Saville et al. 10

11 Figure : Wave runup ratios As a result of all those calculations and methods in the above-mentioned statements, normal margin of safety and minimum margin of safety are determined as.68 m and 1.46 m respectively. As well as the afore-mentioned statements, I also learned the geologic formations that the design engineers should pay consideration when dam bodies are being placed and some of those are stated below; - A groundwater way which is difficult to be ruled out should be found through the dam axis upstream to somewhere related to downstream. - Formations that are hard to rehabilitate or may lead to high costs should be avoided for a dam s foundation 11

12 - Both in the vicinity of fills and the foundations of concrete dams, there should not be active faults - The place where the dam is planned to be built on must not encompass landslide prone areas Before a project starts, dams possessing different dam body types are considered as alternatives and their costs, advantages, disadvantages are listed in order to find the most appropriate dam type for a specific project. Starting with, concrete-face rock-fill dams, its advantages are; - The second smallest body volume - Agricultural fields do not necessarily have to be expropriated - High strength due to all fill materials being dry and disadvantages are; - Spillway excavations on left coast increase the cost - Since right and left incline slopes are too steep, front faces plate widths should be selected among the narrow ones. - Water intake cost Other two types of dams, roller compacted concrete dam and clay core rockfill dam, have advantages and disadvantages as well and described below; Clay core rockfill dam Advantages Disadvantages Wide base area Rocks are far so increased excavation costs Clayey material zone is close Expropriation costs are high Very coherent body type Roller compacted concrete dam Advantages Disadvantages The smallest body volume Dam body exposed to high tensions Shorter construction period Prone to tension and deflections Lower excavation and construction costs Need for flying ash Less tunnel opening difficulty Table 1: Advantages and disadvantages of two dam types 1

13 Spillway Calculations When it comes to typical spillway project phases, primarily spillway width and depth are determined so as to exceed maximum design discharge and afterwards, if exists, the effects of approach channel and inlet are taken into account. To prevent the damage of water to downstream taken from spillway entrance, its energy should be lowered and because of that chutes and stilling basins are constructed. It was decided that, after all economic, geologic and topographic evaluations about Adıyaman Gömükan dam project, the spillway should be placed on the right coast of the territory. Spillway type is an uncontrolled frontal overflow concrete dam with a rectangular cross section. For the width of the spillway, it was determined that the starting width is B = 15 m and after a following contraction B = 10 m, it ends up with B = 10 m as well. At the end of discharge channel, so as to decrease the energy of flow, a stilling basin having a length of m was designed. My supervisor told that the design stage was carried out based on the specifications published by The General Directorate of State Hydraulic Works on 7 January 006. As a result of spillway calculations, Q = m 3 /s which in other words the plausible maximum flood discharge value used by while doing flood routing and offset output discharge is m 3 /s. The threshold elevation of spillway structure is m and approach elevation was determined as After the calculations that has been done, the maximum water level selected as m. Project characteristics are given below: Spillway location and type: On the right coast, uncontrolled frontal Approach channel base elevation: m Spillway crest elevation: m Maximum water level: m Water load: 1.50 m Discharge channel type: Reinforced concrete with a rectangular cross section Discharge channel width: B = 15 m ( km km ) Transition ( km ) B = 10 m ( km km ) 13

14 Discharge channel base slope: j:038 ( ), j:0.08 ( ) Stilling basin length: m Hydraulics calculation of spillway width Collection of water in a bowl depends on the difference between input and output flows. This relationship can be shown as: = (3) Δt = time interval ΔS = Storage during the certain time interval Qi = Incoming flow during Δt Qo = Outgoing flow during Δt The change in incoming flows against time shown with the flood hydrograph, the change in outgoing flow is reflected on spillway discharge curve and the storage is depicted on reservoir elevation curve. 14

15 Dolusavak Deşarj Eğrisi (L = 15m) Su Kotu (m) M.S.S. =, Q-ötelenmiş = 57, Debi (m3/sn) Figure 3: Spillway discharge - level curve (B= 15 m) 15

16 Zaman dt Qgiriş Ort. Qi Toplam Tahmini Giren Su RSS Çıkan Q Çıkan Qort Çıkan V Biriken V V rez. Hesaplanan RSS (saat) (saniye)(m 3 /sn) (hm 3 ) (m) (m 3 /s) (m 3 /s) (10 6 m 3 ) (10 6 m 3 ) (10 6 m 3 ) (m) Table : Flood routing calculations for Qmmf=153,6 m 3 /s (L=15m) 16

17 ADIYAMAN GÖMÜKAN BARAJI Dolusavak Taşkın Ötelemesi Hidrografı Debi - Q (m 3 /sn) Zaman - t (saat) Figure 3: Adıyaman Gömükan Dam spillway inflow-outflow hydrographs Determination of spillway profile A spillway can be roughly split into four parts; the approach channel, crest profile, discharge channel and stilling basin Crest profile: Normally the crest is shaped to conform to the lower surface of the nappe from a fully aerated sharp-crested weir as shown in Figure 1. The pressures on the crest will then be atmospheric. The shape of such a profile depends upon the head, the inclination of the upstream face of the overflow section, and the height of that section above the floor of the entrance channel. ( Khatsuria,004) I have been informed that the major source used for 17

18 spillway design in the office is Design of Small Dams, U.S. Bureau of Reclamation. The equation used for determining the spillway profile is y/h 0 = -K (x/h 0 ) n and the K and n values are constant with solely depending on approach velocity and slope while H 0 is the load on crest. Valveless spillway has the below main characteristics: Spillway crest elevation: m Approach channel elevation: m Spillway crest length: 15 m In the progress of flood routing calculations, the 1000 years flood discharge value corresponding to Q 1000 = m 3 /s was used. Design discharge was found to be m 3 /s at H = m water level in reservoir. Spillway design discharge: Q = m 3 /s Water load at crest: H = H = 1.50 m Approach channel width: m Approach channel velocity: Vy = Q B y design dy dy: water depth in the approach channel y V z dy g dy = m ( by iteration) Vy = 5.83 m/s h a = Vy /g = m Ho 1.50 h a K = ( from graph) n = ( from graph)

19 Figure 4: Variations of K and n coefficients with respect to value Water depth at the entrance of discharge channel Q = m 3 /s P = 0.9 m, Base slope of discharge channel: 0.01 Base angle of discharge channel: Starting elevation of discharge channel = Maximum water level.56 * H e = *1.50 = m dn 9.81 dn cos( ) dn = m ( by iteration) Determination of the intersection point of discharge channel spillway profile Required Circle Diameter = 5 * dn = 5 * =.48 m Chosen Diameter = 6.00 m 19

20 Base slope of discharge channel = 0.01 Base angle of discharge channel = The tangents of curves on the points of crest profile and spillway discharge channel must be the same. In other words, first derivative of the curve and base slope of discharge curve have to be equivalent. x is chosen to be m dy/dx = * ( x ) = x dy/dx = * = = tanβ β is found to be from this equation. a = R*sinβ=6.0*sin4.154 = 4.07 m b = R*cosβ=6.0*cos4.154 = 4.45 m b = R*cosγ=6.0*cos =6.00 D s elevation = b = =85.00 m A s elevation = D s elevation b = = m B s elevation = Max. Water level.56*he= *1.50= m Total crest length x c + x + x 1 = = m With the aim of both creating an economically feasible project and avoiding extra excavation, contraction was done through the discharge channel. V ave = 1.51 d ave = m F = 6.1 Maximum value of the contraction angle α is 3.07 α chosen = atan(15-10/ / 60)=.38 < 3.07 ok While calculating margin of safety, km, base elevation, velocity, water depth and cosα values were taken from related tables. 0

21 3 Margin of safety = V d was determined with this formula. Stilling basin design The discharge value of m 3 /s was taken while the dimensioning and calculation of the stilling basin. What calculations yielded is that at the entrance of the stilling basin, the flow depth is d 1 = m and the flow velocity is m/s. d 1 = m V 1 = m/s V Fr 1 = g d d Flow depth after the jump d Fr d =4.150 m Since Fr 1 > 4.5 and V 1 = m 3 /s < 18 m 3 /s, stilling basin type was selected. For Fr 1 = 8.50, L =.75 and L =.75 * = m, as a result, stilling basin length was decided to be m finally. Lateral wall heights in stilling basins are calculated by adding margin of safety value to the flow depth after hydraulic jump. On the other hand, margin of safety value is found with the equation below; m.o.s = 0.1(V 1 +d ) V 1 =15.97 m/s d 1 = m d =4.150 m m.o.s =.01 m Top of the wall s elevation is found by; Stilling basin base elevation *d + m.o.s = Top of the wall s elevation * = m h wall = 6.50 m My supervisor informed me about the criteria that they take into account while doing sluiceway calculations. Some of them are below; Evacuation conditions should be appropriate for project needs Economic benefit that obtained with the aid of sluiceway used during project flood routing In compliance with discharge criteria Economic benefit that obtained with the aid of sluiceway for the derivation of stream flows during the construction stage 1

22 First water holding criterion should be completed before the first water holding process Week 3 This week I learned how to calculate the hydraulics of diversion tunnels. To begin with, an optimization study is done for the purpose of determining the diameter of a diversion tunnel. Afterwards, during the derivation structure pre-report phase, different route alternatives are inspected. Tunnel entrance elevation, tunnel exit elevation and tunnel length are written first together with tunnel s diameter which is found at the end of optimization studies. An example which I tried to do by consulting the chief enginner are presented below; Tunnel entrance elevation = m Tunnel exit elevation = m A = 9.6 m Tunnel length = 485 m A = 9.57 m 4 Tunnel diameter = 3.5 m Slope of the tunnel = Q 5 = 4.10 m 3 /s Manning coefficient = Q 50 = m 3 /s 1-Tunnel s Free Working Case n /D 1/3 = where n is the manning coefficient. This coefficient is selected by the engineer and s/he decides the value based on his judgement and experience. n changes with respect to a few other factors such as surface smoothness, vegetation, channel irregularity, abrasion, obstacles, discharge and so forth. S 0 / ( n /D 1/3 ) = and for this value, d/d value corresponds to 0.66 which means that unpressured flow case would be observed until %66 of load factor reached in the diversion tunnel. -Tunnel s Pressured Working Case Q design = 10 m 3 /s a) Entrance loss

23 he = ke * hv ke = 0. D = 3.50 m he = Q hv = A g b) Friction loss S f D = 3.50 m S f = hf = S f * L hf = Q c) Exit loss hv = Total Loss = 0.07 K = Sh Q Q d K = * Q F = Q A 9.81 D 1/ F = * Q After all those calculations, flow consumption chart is prepared encompassing the parameters such as h v, h e, reservoir water elevation and so forth. Following this, input and output hydrographs are drawn which can be basically defined as a hydrograph intends to show how the water flow in a drainage basin (particularly river runoff) responds to a period of rain. What my supervisor told me about how a hydrograph is drawn is that there are two types of hydrographs that can be enumerated as line graphs and bar graphs. Line graphs are the ones that they mostly prefer and drawn with two vertical axes. The point where river reaches its highest level is called peak discharge and another useful info is that where gradients are steep, water runs off faster. In addition to what has been told so far, derivation discharge curve is also prepared drawn by placing discharge values on the horizontal axis and water level values on the vertical axis. Finally, flood routing is done for the purpose of finding the maximum value of reservoir water elevation among all values. This, in practice, is materialized by entering discharge values, time intervals, volumes in a spreadsheet application and the rest is calculated by the programme itself. 3