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GRADUATION THESIS ROAD AND HIGHWAY SECTION CONTENTS … Page GRADUATION THESIS ROAD AND HIGHWAY SECTION CHAPTER INTRODUCTION 1.1 BACKGROUND OF THE PROJECT Project name: Highway investment project Location: Alignment A-B is located in Khu 6A, Dak Nong province Project manager: Ministry of Transport Consultant organization: The University of Transports and Communications Designer: 1.2 OUT LINE OF THE PROJECT 1.2.1 Objectives of the Project The main objectives of the Project implementation can be summarized as follows: The new road is strategically located at Dak Nong province to contribute to the economic and social development of the Central Highland region in Vietnam Concerns and improvement for the traffic safety, job opportunity and living level of the local residents in the project area is an important factor in the sense to share the profits of project 1.2.2 The base to carry out the project Base on Dak Nong Highway investment and construction policy Base on traffic volume investigation and forecast data Table 1-1: Forecast traffic volume No … Vehicle Heavy Truck Heavy Truck Heavy Truck Medium Truck Light Truck Small Bus Big Bus Car Summary Fleet Composition % 2 17 64 98 Page Traffic components (veh/day) 13 13 57 107 13 403 630 GRADUATION THESIS ROAD AND HIGHWAY SECTION 1.3 DOCUMENTS USED FOR DESIGNING No Name of Standards Standard Ref No Survey T32 Land survey in construction – general specification TCXDVN3092004 G09 Geotechnical Boring Investigation Standard 22TCN259-2000 G13 Geological survey for waterway work standard 22TCN260-2000 Road Design R16 Specifications for road design TCVN4054-2005 R28 Rural road design standard (used for frontage road and 22TCN210-92 collector road) Pavement P18 Vietnam Pavement standard of flexible structures 22TCN211-06 Water Treatment W11 Flood flow calculation 22TCN220-95 Safety T Roadway traffic signal regulations QC41-2012 1.4 STUDY SCOPE The study scope has limited in direction route, it bases on the long-term transport programming of the area in the future CHAPTER PROJECT AREA IN DAK NONG PROVINCE 2.1 INTRODUCTION AND GEOGRAPHICAL CONDITIONS Dak Nong Province is located in the at the southern gateway of Tay Nguyen, Dak Nong has National Highway 14 linking Ho Chi Minh City and the Eastern provinces with the Central Highlands, 230 km north of Ho Chi Minh City and away from the city Dak Nong has a network of rivers, streams, lakes, dams distributed fairly evenly This is a good condition to exploit water resources for agricultural production, … Page GRADUATION THESIS ROAD AND HIGHWAY SECTION industry, construction of hydropower projects and to serve people's needs Flood regime: Bear the strong influence of Krong No River 2.2 TOPOGRAPHICAL CHARACTERISTIC The topography is quite favorable, coMPared to other midland districts and mountainous areas of the province The district has few mountains with elevations ranging from 500 m to 700 m The alignment is mainly along the contour line, cut through many stream so the different kinds of embankment can be used such as full fill, full excavate, half cut half fill, L shaped cut… Base on the results of topographical surveys, test drilling, field testing and laboratory tests on the collected samples, the stratification of the area was divided into layer as following: - Organic soil was found on the ground surface The thickness of this layer ranges from 0.2m to 0.4m Basaltic soil: this layer distributes along alignment The thickness of this layer ranges from 2m to 4m Weathered rock: the color of this layer is yellowish brown, reddish brown The thickness ranges from m to 5m Bed rock: the most popular bed rock in this area is basalt rock The region where the project is carried out has stable geologic condition Dynamic geological phenomena barely occur or in such small scale that they have no influence on the alignment 2.3 CLIMATIC CONDITIONS This section is prepared to: - To find possible material sources; To determine the suitability for quality requirements; To determine the possibility of supply for required magnitude in the project; To provide necessary information to estimate the project cost The Project goes through the area where constructional material sources are popular and advantageous The exploitation, supply and transportation conditions are very convenient - … Soil: sandy clay volume is quite large Sandy clay has high strength Employment, transportation is convenient So, it is used for embankment very well Page GRADUATION THESIS - - ROAD AND HIGHWAY SECTION Stone: The quality of stone is quite good and satisfies Resistance strength is rather high There are some quarries with large volume Sand: the quantities are large The exploitation, supply and transportation are quite convenient Water: is sufficient for construction Figure 2.1: Diagram of Temperature – Humidity … Page GRADUATION THESIS ROAD AND HIGHWAY SECTION Figure 2.2: Diagram of Rain fall – Evaporation … Page GRADUATION THESIS ROAD AND HIGHWAY SECTION Figure 2.3: The wind flower schema 2.4 HYDROLOGY Hydrology of the region is not complex The alignment cuts through a stream The flow volume of this stream is not so high Standing water phenomenon does not occur It locates Kien Duc buk district Topography of the section is generally downy, mainly forest Therefore hydrological regime depends on local rainfall and the irrigation works In research region have only stream system, ditch system … Page GRADUATION THESIS ROAD AND HIGHWAY SECTION 2.5 DETERMINATION OF ENVIRONMENT The following aspects stated in the General Requirements, Section 01700 Environmental Control and Protection should be complied for borrow pits - Air quality and dust - Water quality - Waste and soil contamination - Aesthetic problem - Other environmental aspects 2.6 TRAFFIC CONDITIONS OF THE REGION Dak Lak province has nearly 5000 km roads In which, national road is 398 km (7.96%), province road is 460 km (9.2%), district road and commune road is 4000km (82%) … Page GRADUATION THESIS ROAD AND HIGHWAY SECTION CHAPTER TECHNOLOGY FACTORS 3.1 DETERMINE ROAD LEVEL 3.1.1 DESIGN TRAFFIC VOLUME According to the highway specification TCVN 4054-2005 then: Design traffic volume is number of the passenger cars converted from all the vehicles which is forecasted to pass a cross section of the road during the time unit in the computing year ( the 15th year in this project) 3.1.2 ROAD LEVEL Design traffic volume is number of the passenger cars converted from all the vehicles which is forecasted to pass a cross section of the road during the time unit in the computing year Formula: ∑( a N ) i Nde = i Where: Nde: Design traffic volume (Veh/day) Ni: Volume of vehicle type i in future year Ni = Nip x(1+q)t Nip: Volume of vehicle type at the present q: Traffic growth = 7% t: Calculated time = 15 (years) ai: Equivalence factor from vehicle type i to passenger car No Vehicle Heavy Truck Heavy Truck Heavy Truck Medium Truck Light Truck Small Bus Big Bus Car Summary … Fleet Composition % 2 17 64 98 Traffic component s (veh/day) 13 13 57 107 13 403 630 Page PCU equivalent factors 3 2.5 2.5 2.5 2.5 design traffic volume (Nqd) 38 38 16 142 16 268 38 403 958 GRADUATION THESIS ROAD AND HIGHWAY SECTION The equivalent PC volume in the designed year (the 15th year) is : N15 = N1 (1 + q)15 - = 958 x (1 + 0.07)14 = 2469 (vehicle/day) So the design traffic volume N de = 2469 (vehicle/day) < 3000.According to TCVN 4054-2005, the road level: - Base on the importance of the road is connecting economic and politic centers of the province - Base on the future development plan of the province related to transport and communication’s developments So, the road level chosen is: IV, design Speed is chosen 60 km/h 3.2 CAPACITY OF THE ROAD The capacity of the road, (N) is maximum number of vehicle that can be able to pass continuously through any cross section during time unit N = vehicle per day (VPD) or vehicle per hour (VPH) 3.2.1 IDEAL CAPACITY OF THE ROAD The ideal capacity of the road, Nlt is the capacity which is determined in ideal condition (including the road condition and vehicle condition) + Assumption: vehicle continuously move on the road, the same kind of vehicle and speed, the distance between two adjacent vehicle is constant and equal to L o, which is required so sufficient that if any vehicle suddenly stop then the driver of the followed on keep in time to perceive and put on the brake to stop safety L o is called kinetic size of vehicle + Schema, refer to figure 3-1 + Calculation Formula: NLT = … 1000V Lo ( Veh/h) Page 10 GRADUATION THESIS ROAD AND HIGHWAY SECTION CHAPTER PAVEMENT DESIGN 7.1 PAVEMENT STRUCTURE AND REQUIREMENT Pavement is the structure that is constructed on the roadbed by multi-layer structure, directly subjected to vehicle load and natural factors such as rain, wind and temperature Pavement structure has to satisfy as following requirements: - The pavement has enough strength in the design period without occurring exceeded vertical deformation, sliding deformation, compressible and tensile deformation etc In addition to, pavement’s strength has little change with climate and is stable - The surface has to satisfy plan to reduce rolling impediment coefficient, shock, fuel consumption and traffic cost - The pavement structure has enough roughness to provide safety and smoothly condition for vehicles From above requirements, we choose flexible pavement structure to design for the pavement structure 7.2 FLEXIBLE PAVEMENT STRUCTURE It defines a flexible pavement as a multi-layer structure consisting of surface course, base course and sub-base course, as depicted in below figure: B 1:m 1:m Hn Hd D Figure 7-1: Pavement structure Lc The surface layer consist of a wearing course (termed as abrasion-resistant course), a binder course (termed as load bearing lower course) The wearing course serves to provide waterproofing function, resist wear and abrasion, and offer a skid resistant and smooth riding surface It is usually constructed of fine-grade asphalt … Page 49 GRADUATION THESIS ROAD AND HIGHWAY SECTION mixture from 1.0 to 3.0 cm thick The binder course functions as a structural layer to resist surface deformation, bending and shearing actions caused by traffic loading The base and sub-base courses are designed to distribute through their thickness the stresses caused by traffic loads They may be constructed of several layers of gradually reduced strength downward 7.3 FLEXIBLE PAVEMENT STRUCTURE DESIGN 7.3.1 PAVEMENT STRUCTURE DESIGN Flexible pavement structure design based on the following factors: For the wearing course: + Technical classification of the highway + The design traffic volume in the future year + The design speed For the base and sub-base courses: + Based on geotechnical and hydrological conditions + Availability of local materials In addition to, we have to consider constructional condition, performance of pavements in the area, initial cost, and the overall annual maintenance and service-life cost The selection of materials for the various pavement layers and their respective thickness are selected to withstand the effects of loading of the design traffic The pavement is deemed to be sufficiently strong if the following three conditions are met: 1- The settlement of the pavement structure does not exceed the allowable value – The design approach is based on the reasoning that this settlement requirement can be met by controlling the elastic surface deformation of the structure under the design traffic volume Based on this consideration, the design procedure specifies a required elastic modulus for the entire pavement structure The pavement layer materials and thickness must be selected to provide an equivalent elastic modulus of the whole pavement ≥ structure equal to or higher than the required elastic modulus ( E ch Eyc) 2- No damage to the continuity of pavement layers constructed of cemented or bound materials (termed as integrity layer) – The continuity of each “integrity” layer is preserved if crack formation in the layer is prevented In the pavement design, this is checked by ensuring that the flexural stress in the bottom face of each “integrity” layer … Page 50 GRADUATION THESIS ROAD AND HIGHWAY SECTION under the action of the design load does not exceed the allowable tensile stress of the layer material ( σ u < Ru ) 3- No plastic deformation occurring in any of the pavement layers, including the embankment – To guard against such failure, the shear stress in each layer is checked to ensure that the allowable limit is not exceeded (τ < [τ]) This check is carried out in pavement design by performing load bearing capacity and shear failure analysis of the pavement against the critical design wheel load, known as the standard calculation load 7.3.2 CALCULATION PARAMETERS AND SECTION FLEXIBLE PAVEMENT STRUCTURE 7.3.2.1 Determination of standard axle load According to TCVN 4054-05, the standard design axle load for the flexible pavements of this highway is the axle load (single axle) of 10t In which, the contact pressure (p) is 0.6(MPa) and the diameter of tire imprint (D) is 33(cm) 7.3.2.2 Determination of Design traffic volume The design traffic volume is predicted for a design period that is 15 years The predicted traffic volume at the end of the design period is converted to the predicted daily traffic volume in the lane that carries the heaviest total daily traffic loading in the road section of interest The traffic volume and component in opposing at the beginning of the design period as following in Table 6.1: Ntk = N= No Vehicle Heavy Truck Heavy Truck Heavy Truck Medium Truck Light Truck Small Bus Big Bus Car Summary N i × [ + q] Fleet Composition % 2 17 64 98 ( t −1) Traffic components (veh/day) 13 13 57 107 13 403 630 Table 6-1: Current traffic volume … Page 51 The future traffic volume(Ntk) 32 32 16 146 16 276 32 1040 1590 GRADUATION THESIS ROAD AND HIGHWAY SECTION Conversion of traffic axle load into standard axle load of 100 kN The predicted total two-directional daily traffic volume into equivalent number of the standard axle loads can be calculated by the formula: k  P  N = ∑ c1 c2 ni  i   100  I =1 4.4 Where: C1 = 1+1.2(m-1) C2 = 6.4 for front and rear axles that have one wheel C2 = 1.0 for front and rear axles that have two wheels The calculation is carried out as Table 6.2 Loại xe Fon t Car Rea r Fon t Small Bus Rea r Fon t Big Bus Rea r Fon t Medium Truck Rea r Fon t Light Truck Rea r Fon t Heavy Truck Rea r Heavy Truck Fon t … Pi (kN) C1 C2 ni 20 6.4 1040 21 6.4 1040 27.4 6.4 276 46.5 1 276 51 6.4 32 10 94.2 1 32 24 24.6 6.4 146 71 1 146 32 18 6.4 16 52 1 16 50 6.4 16 110 1 16 24 48 6.4 32 Page 52 C1.C2.ni (Pi/100)4.4 GRADUATION THESIS Rea r Fon t Heavy Truck Rea r ROAD AND HIGHWAY SECTION 97 2.2 32 61 24.4 0 32 76.3 0.38 32 Total Axles converted to standard axle 196 Table 6-2: Axles converted to standard axle From the result, it can be seen that: Ntk = 196 (standard axles/day/) 7.3.2.3 Determination of the standard design lane axle loads Ntt = Ntk.fL Because the designed highway has two lanes and without median, the lane distribution factor can be selected: fL= 0,55 So: Ntt = 196 x 0.55 = 107 (axle/lane/day) 7.3.2.4 Determination of the number of accumulative standard axle loads in the design period We have the predicted standard axle loads at the end of the design period (15 years): Ntt = 107 (axle/lane/day) Because of the daily standard design lane axle loads N tt = 107 (axles/lane/day), using Table 3-4 in the standard (interpolation between N tt= 200 and Ntt= 100), the required elastic modulus is found as Eyc = 148.01 MPa ( larger than the minimum required elastic modulus for road class III as given in Table 3.5: Eyc >140 MPa) The number of accumulative standard axle loads in the design period is calculated by the formula : Ne = Where: [(1 + q ) t − 1] 365.N t q q = 0.06 – the annual growth rate over the design period ⇒ [(1 + 0.07) t − 1] Ne = 365 x 0.07 510= 1.8x106 ( axles) 7.3.2.5 Selection pavement structure We plan structure of the pavement and characteristics of each pavement layer as follow Table 6.3: … Page 53 GRADUATION THESIS Layer (from bottom to top) Thicknes s (cm) Subgrade - - ROAD AND HIGHWAY SECTION Graded Crushed Stone Type II E (MPa) Deformation Rku (MPa ) Slidin g 42 32 250 250 250 - Graded Crushed Stone Type I 16 300 300 300 -Coarse AC concrete 350 250 1600 2.0 -Fine AC 420 300 1800 2.8 C (MPa ) (độ) 0,032 24 Table 6-3 : Structure of the pavement design and characteristics of each pavement layer 7.3.3 CALCULATING AND CHECKING STRENGTH OF THE TRUCTURE BY ELASTIC SURFACE DEFORMATION OF SETTLEMENT 7.3.3.1 Conversion from two layers to an equivalent one-layer Each two-layer from down to up may be converted to an equivalent one-layer by the following formula: 1 + k t /  Etb ' = E1    1+ k  Where: k= and t = The calculated results are show in Table 6.4 as follow: … Page 54 GRADUATION THESIS ROAD AND HIGHWAY SECTION Pavement structure Ei (MPa) t = E2/E1 hi (cm) k = h2/h1 Htb (cm) Graded crushed stone Type II 250 Graded crushed stone Type I 300 1.200 16 AC – Coarse mix 420 1.583 AC – Fine mix 420 1.474 32 Etb' (MPa) 32 250.0 0.469 48 265.3 0.170 55 284.9 0.109 60 296.7 Table 6.4: The result of conversion each two-layer from down to up 7.3.3.2 Determination of the correctly average elastic modulus β The corrective factor is =f(=61/33) with = 60/33 = 1.82 From Table 3.6 (22 TCN 211-06), it can be seen the corrective factor as: β = 1.20 So that the multi-layer pavement structures are taken into the two-layer structure which the upper layer’s thickness is 60cm and average elastic modulus can be calculated as follow: Etbdc = β Etb’ =296.7 x 1.82 = 539.94(MPa) 7.3.3.2 Determination of the general elastic modulus of pavement Using the Figure 3.1 (in 22 TCN 211-06) with: Etbdc = 60/33 = 1.82; = 42 356.03 = 0,12 From these two ratios and the monogram 3.1, we obtain: = 0,604 ⇒ Ech = 0.604 x 356.03 = 215.04 MPa 7.3.3.3 Checking against requirement for elastic deformation It has to be satisfied as: Ech≥ … K dv cd E yc Page 55 GRADUATION THESIS ROAD AND HIGHWAY SECTION From Table 3-2 with the road class III, two lanes and the design reliability is selected as R = 0.9, it obtains K cddv =1.1 ⇒ K cddv Eyc=1,1 x 148.02=162.82 MPa The result of checking as follow: K dv cd E yc Ech= 215.04 MPa > = 162.82 MPa ⇒ OK The pavement structure has satisfied the requirement of strength following the standard of allowable elastic deformation 7.3.4 BEARING CAPACITY DESIGN AGAINST SLIDING OF PAVEMENT STRUCTURE 7.3.4.1 Determine average elastic modulus of the pavement structure Conversion from two layers to an equivalent one-layer are carried out as follow: Pavement structure Ei (MPa) t = E2/E1 hi (cm) k = h2/h1 Htb (cm) Etb' (MPa) 32 250.0 Graded crushed stone Type II 250 Graded crushed stone Type I 300 1.200 16 0.469 48 265.3 AC – Coarse mix 300 1.131 0.170 55 270.2 AC – Fine mix 300 1.110 0.109 60 273.0 32 Table 6.5: The result of conversion each two-layer from down to up The corrective factor is β =f (= 60 33 ) = 1.82 with = 60 33 = 1.82 Calculation is as the same the section 3.7.3.2, we obtain: ⇒ Eave = 1.2 x 273.0= 327.62 MPa 7.3.4.2 Determination of the maximum shear stress created by standard vehicle load Tax We have: = … 60 33 = 1.82; = = 327.62 42 Page 56 = 7.8 GRADUATION THESIS ROAD AND HIGHWAY SECTION From the graph Figure 3-3 in the standard with internally frictional angle ϕ =24o, Tax p it can be seen = 0.0122 ⇒ Tax= 0.0122 x 0,6 = 0,007344 MPa 7.3.4.3 Determination of the shear stress at the same point cause by seftweight of the overlying pavement materials Tav From the graph Figure 3-4, it can be seen Tav : Tav= -0.00217 MPa 7.3.4.4 Determination of the coefficient Ctt Following (3-8) in the standard: Ctt= C.k1.k2.k3 Where: From Table 6-3: C = 0.032 MPa From the section 3.5.4 in the standard, k = 0.6; k2 = 0.8 because the number of the daily standard design lane axle loads (N tt = 525 (axles/lane/day)) is smaller than 1000 axles And k3 = 1.5 (because subgrade is clay) … Page 57 GRADUATION THESIS ROAD AND HIGHWAY SECTION ⇒ Ctt = 0,032 x 0.6 x 0,8 x 1,5 = 0,023 MPa 7.3.4.5 Checking against sliding conditions of pavement The pavement structure will provide sufficient strength if the following equation satisfy: Tax + Tav ≤ Ctt K cdtr For the road class III and the design reliability is selected as R = 0.94, it obtains as K cdtr =0.94 And Tax , Tav are computed above Tax + Tav =0.00734 – 0,00217 = 0.005174 MPa k cdtr == 0.024511 MPa ⇒ Tax + Tav = 0,005174 < k cdtr = 0.024511 MPa ⇒ OK The pavement structure have satisfied the requirement of strength following the standard of sliding conditions 7.3.4.6 Checking against sliding conditions of asphalt concrete h1=14 cm; E1 = 1800 MPa; K = 6/8 = 0.75 ; t=300/250 = 1,2 The average elastic modulus (Eave’) of two layer such as Lower and Upper asphalt concrete layer a is Eave’ = 270.69 MPa Thickness of three layers is H’= 32 +16 = 48cm β Consider the corrective factor : With = 48 33 = 1.42 From Table 3-6 in the standard, it obtains ⇒ We have: = 48 33 Etbdc = 1.42; = 1.1650 =1.165 x 265.3= 309.07 MPa Etbdc = = 0.1359 From these two ratios and the monogram 3.1, we obtain: Etbdc ⇒ Ech.m = 309.07 x 0.479 = 148.05 MPa … β Page 58 = 0.479 GRADUATION THESIS ROAD AND HIGHWAY SECTION We have: 14 33 = = 0.42; = = 1.502; From the graph Figure 3-3 in the standard with internally frictional angle ϕ =24o, Tax p it can be seen = 0.2406.⇒ Tax= 0.2406 x 0.6 = 0.144 MPa [T] = 1.6.C1 =1.6.0.3 = 0.48 The structure have satisfied the requirement of strength following the standard of sliding conditions 7.3.5 DESIGN AGAINST TENSILE AND FLEXURAL FAILURE OF BOUND MATERIAL 7.3.5.1 Determination of the maximum bending stress asphalt concrete layers σ ku at the bottom of a The lower asphalt concrete layer h1=12 cm; E1 = 1800 MPa The average elastic modulus (Eave’) of three layer such as Graded crushed stone Type II, Graded crushed stone Type I and Cement treated crushed stone is calculated above ( Table 6-4) as Eave’ = 265.3 MPa Thickness of two layers is H’= 32 +15 = 47 cm β Consider the corrective factor : With = 47 33 = 1.42 From Table 3-6 in the standard, it obtains ⇒ We have: = 47 33 Etbdc = 1.165 =1.165 x 265.3 = 309.07 MPa dc tb E = 1.42 ; = 42 265.3 = 0.1359 From these two ratios and the monogram 3.1, we obtain: Etbdc ⇒ Ech.m = 309.07 x 0.439 = 148.05 MPa … β Page 59 = 0.479 GRADUATION THESIS Determine 3.5 with: σ ku ROAD AND HIGHWAY SECTION at the bottom of the lower asphalt concrete by using the Figure 14 33 = =0.42; = 1800 148.05 = 12.16 σ ku The result obtains: = 1.79 and with p = 0.6 MPa; k b = 0.85 Following the formula (3.11) in the standard, we obtain: σ ku = 1.79 x 0.6 x 0.85 = 0.9129 MPa b The upper asphalt concrete layer h1= cm; E1 = 1600 MPa The average elastic modulus (Eave’) of three layers is calculated as follow Pavement structure Ei (MPa) t = E2/E1 hi (cm) Graded crushed stone Type II 225 Graded crushed stone Type I 275 1.2 16 1600 4.6 AC – Coarse mix k = h2/h1 Htb (cm) 32 30 225,0 0.938 48 243,0 0.163 56 345,9 Table 6.6: The result of conversion each two-layer from down to up β Consider the corrective factor : With = 55 33 = 1.67 From Table 3-6 in the standard, it obtains ⇒ Etbdc β = 1.1962 =1.1962 x 382.7 = 457.79 MPa We have: = 60 33 = 1.82; Etbdc = 42 457.79 = 0.092 From these two ratios and the monogram 3.1, we obtain: Etbdc ⇒ Echm = 457.79 x 0.455 = 208.29 MPa … Page 60 Etb' (MPa) = 0.455 GRADUATION THESIS Determine 3.5 with: σ ku ROAD AND HIGHWAY SECTION at the bottom of the upper asphalt concrete by using the Figure The corrective factor is β =f(= 62 33 ) with = 62 33 = 1.879; Calculation is as the same the section 1.3.3.2, we obtain: ⇒ Etb = 1.194 x 249.1 = 255,03 (MPa) 7.3.5.2 Checking tensile and flexural conditions at the bottom of asphalt concrete layers The pavement structure will provide sufficient flexural strength if the following σku ≤ equation satisfy: Rttku K cdku The allowable flexural strengths at the bottom of asphalt concrete layers are calculated as following formula: Rttku = k1.k2.Rku Where: The coefficient k1 can be calculated as the formula: K1 = 11.11 N 0e ,22 = = 5.493 × With Ne = 2.08 106 - The number of accumulative standard axle loads in the design period is determined in the section 7.3.2.4 The coefficient k2 = 1.0 – Following the section 3.3.6 in the standard - The allowable flexural strengths at the bottom of the lower asphalt concrete layer: Rttku = k1.k Rku - = 5.493 x 1.0 x 2.0 = 10.987 MPa The allowable flexural strengths at the bottom of the upper asphalt concrete layer: Rttku = k1.k Rku = 5.493 x 1.0 x 2.8 = 15.381 MPa K dcku Checking flexural conditions with =0.94 (following Table 3-7 in the standard for the road class III and the design reliability R = 0.9) as follow: … Page 61 GRADUATION THESIS - The lower asphalt concrete layer: σ ku - ROAD AND HIGHWAY SECTION = 0.94 MPa < 10.987 0.94 = 11.688 MPa ⇒ OK The upper asphalt concrete layer: σ ku = 1.1434 MPa < 15.381 0.94 = 16.363 MPa ⇒ Ok 7.3.5.3 Audit follow condition tension –bend at bottom of cement treated crushed stone layer - Merge the upper layers (from surface of Cement treated crushed stone to top) to layer, we have: h1 = + = 12 cm E1 = (1600x6 + 1800x8)/(5 + 7) = 1714.2857 MPa -Calculate Emch of layers that below Cement treated crushed stone layer From the result of table , E'tb =274 and Htb = 31 Refered to adjustable factor β = 31/33 =0.94 So we have Edctb= 0.94x274 = 257.56 MPa Apply monograph 3-1 to find Emch H'/D = 31/33 =0.94 and Esubgrade/Edctb = 42/257.56 = 0.16341 From the monograph 3-1, we have Ech.m/Edctb = 0.4, so Emch = 0.4x257.56= 102.81 (MPa) Find the σku at the bottom of Cement treated crushed stone from monograph 3.6 with: H1/D = 24/33 = 0.7273 E1/E2 = 1714.2857 /600 = 2.81 E2/E3 =5.8359 From the monograph, we have we have σku = 0.44 and with p = 0.6 MPa follow 3.11 σku = 0.44x06x0.85=0.2244 MPa Audit condition follow formula (3.9) with factor K kudc = 0.9 from table 3-7 for case road level III with reliability factor 0.95 Here, follow (3-9), we determined k1 = 1.11/(6.34x105)0.22= 0.441 and k2 =1 Rkutt=k1xk2xRu=0.441x1x2= 0.881 MPa So we have : … Page 62 GRADUATION THESIS ROAD AND HIGHWAY SECTION σku=0.85 MPa < 0.88/1= 0.88 MPa => Satisfy So expected design structure achived condition for Cement treated crushed stone layers The pavement structure have satisfied the requirement of strength following the standard of sliding conditions CONCLUSION :This pavement satisfy three conditions: strength, sliding, bending and flexural conditions It is chosen to make pavement of the road … Page 63