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MLS - APT’s Role in Pavement Design Model Development MLS and MMLS3 Innovative APT Technology and Applications 移动式路面加速加载系列 MLS 和 MMLS3 创新技术和应用 Prof Fred.

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Presentation on theme: "MLS - APT’s Role in Pavement Design Model Development MLS and MMLS3 Innovative APT Technology and Applications 移动式路面加速加载系列 MLS 和 MMLS3 创新技术和应用 Prof Fred."— Presentation transcript:

1 MLS - APT’s Role in Pavement Design Model Development MLS and MMLS3 Innovative APT Technology and Applications 移动式路面加速加载系列 MLS 和 MMLS3 创新技术和应用 Prof Fred Hugo PE FSAAE DEng PhD 南非工程院院士 南非 - 中国交通合作中心 SACTCC 顾问 Advisor Beijing 16 May 2008 年 5 月 16 日 北京

2 APT is controlled application of wheel loading to pavement structures for the purpose of simulating effects of long-term in-service loading conditions in a compressed time period Definition of APT (after Hugo,2004 Synthesis 325) 路面加速加载试验的定义

3 What do we want to know and why? 主要点 1.Deflection >>related to stress and strain 2.Rutting >>related to deformation 3.Stiffness changes >>related to response and performance 4.Distress Mechanisms and related models and transfer functions a.Deformation >>rutting b.Flexural performance >> fatigue and cracking c.Shear >> deformation/cracking d.Environmental response and performance >> hot / cold / wet / dry

4 What do we want to know and why?(cont) 续 1.Loading rate>>related to stress and strain 2.Range of validity of characteristics >>related to extrapolation and prediction of of response and performance 3.Effect of Aging >>related to response and performance 4.Effect of Densification >>related to response and performance 5.Effect of Material Properties >>related to response and performance 6.Validation of analytical tools

5 Innovative Technological Tools for Evaluating MLS APT Response and Performance 创新技术和特点 Varying Size of Facility 不同比例  MMLS3 - 1/3 scale 三分之一  MLS10 - full-scale 足尺  MLS66 - full-scale 足尺 Mobile Testing Facility 移动式测 试多种工况

6 Innovative Technological Tools for Evaluating MLS APT Response and Performance (cont) 续 Multiple Wheel Trains Lateral Wander Varying Test Length Varying Speed and Frequency Varying Tyre Pressures Varying Tyre Tread Varying Load Amplitude

7 Two MLS66 being delivered in 2008 两台超大型 MLS66 在 2008 年投入使用

8 同济大学和辽宁省交科院

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15 A Brief Review of Case Studies as Introduction to the Topic 实际情况回顾 In Mozambique ANE embarked on an APT program by WB as most cost effective means to: –Evaluate construction techniques –Determine most economical use of available sub-standard materials in a composite pavement structure –Develop a mechanistic-empirical design system best suited for its needs with due regard to materials and environment

16 Mozambican Pavement Structure Problem Statement 世行项目

17 Research Overview 研究总观

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19 200μm electron microscope photos of yellow sand vs. red sand (hydrometer results compatible) yellowred

20 Scaled Subbase and Base in Laboratory 试验室

21 Namibia Field Application LTPP comparable to MMLS3 Performance Prediction Field testing in Namibia Rut after wet field testing

22 Latest Laboratory Test Bed, Profilometer and Water Heater

23 MLS studies in global perspective 2008 Applications MMLS MMLS3 Labs US Europe Africa MLS10/66 Owners/ Applications China

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25 MMLS3 Tyre contact stresses being measured by SIM of CSIR Refer de Beer and Sadzik SATC 2007

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27 Salient Features of MMLS3 Testing that need to be borne in mind 小型三分之一比例尺 MLS

28 Analysis of MMLS3 Performance Stress Potential

29 Comparison of Vertical Compressive Stresses MMLS3 vs Trucks (Epps et al., WesTrack)

30 Deflection vs. speed under full-scale truck traffic

31 Comparison between some MMLS3 Results at different trafficking speeds Axles x1000 Rutting mm 1m 4mm

32 MMLS3 Testing in conjunction with the HVS on N4 near Pretoria 现场试验 MODIFIED BENKELMAN BEAM

33 BASE / SUBGRADE

34 Red Sand

35 HOT MIX ASPHALT (HMA)

36 ROLLER PERFORMANCE DURING CONSTRUCTION

37 MONITORING EFFECTIVE STIFFNESS RELATIVE TO DENSITY OF COMPACTION

38 Construction of CTB

39 Test Site during construction!

40 MONITORING OF TRIAL SECTION STIFFNESS AFTER CONSTRUCTION

41 PSPA DATA ANALYSIS Portable Seismic Pavement Analyzer 便携式 P-SPA

42 First Correlations of Seismic Stiffness and Cracking

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46 PSPA TIME RECORD SHEAR WAVE VELOCITY: V S = V R ( 1.13 – 0.16v) SHEAR MODULUS : G = ρ V S 2 YOUNGS MODULUS : E = 2 ( 1 + v ) G

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49 Response Model (after Jooste) Tensile Strain (microstrain) LET FE (Static – Square loading area) FE (20 km/h) FE (80 km/h)

50 Stiffness vs. HVS Reps (after Jooste)

51 Load Setting / PSPA

52 Trafficking

53 Rut Measurements

54 NCAT field study Phase 2 Core holes 在美国测试

55 NCAT HMA damaged by wet trafficking

56 Stiffness loss during trafficking of S9 NCAT 路面刚度损失

57 Wet SASW stiffness Young's Modulus vs. Load applications (30 Hz) in Texas (See SAICE )

58 Stiffness loss during trafficking of all NCAT sections

59 SASW NCAT after 10 Million E80s

60 Surface Wave Test - NCSU Effect of Microcracking

61 Fatigue cracks NCSU

62 APT PERFORMANCE MONITORING IN LABORATORY

63 Relative stiffness ratios for MMLS3 and MLS10 – 7% CTB in lab and field

64 Full Scale Constructed Test Sections SECTIONSURFACINGSTABILIZING AGENTSAND TYPECONSTRUCTION NUMBER TYPE 1S2 Seal 5% CEMII 32.5 Red1 240mm AC 5% CEMII 32.5 Red1 360mm AC 5% CEMII 32.5 Red1 440mm AC 5% CEMII 32.5 Red2 540mm AC 2.5% CEMII % LIME Red2 640mm AC 3.5% CEMII % LIME Yellow2 740mm AC 7% CEMII 32.5 Yellow2 840mm AC 7% CEMII 32.5 Red2 9S2 Seal 7% CEMII 32.5 Red2 10S2 Seal 5.5% SS60 Red2 11S2 Seal 1.5% CEMII % SS60 Red2

65 Layout of Test Sections

66 HVS and MMLS3 on R80 Pta West 测试结果对比

67 VERTICAL CONTACT STRESS PROFILES MMLS3 750 kPa contact stress– 91% (R80 Pta West)

68 SHEAR STRESS PROFILES MMLS3 vs. 750 kPa contact stress–75% (R80 Pta West)

69 MMLS3 Data Processing (R80 Pta West) Rutting - Extended Standard Mix vs Rut resistant mix

70 MMLS3 Data Processing (R80 Pta West) Rutting - Standard Mix vs Rut resistant mix

71 MMLS3 Data Processing (R80 Pta West) Extrapolation of Rutting Data: 0-50k; 0-100k; 0-150k; 0-200k = 12% difference

72 MMLS3 Data Processing (R80 Pta West) Rutting Profiles - Heave (left and 450mm)

73 Key to application of the MMLS3 Understanding APT: distress mechanisms performance related factors

74 Applications MMLS MMLS3 Labs US Europe China Africa MMLS3 studies in global perspective

75 MLS10 after completion of field trial on 25 yr old untrafficked section of stiff HMA/CTB pavement in Switzerland 在瑞士量侧

76 A Concluding Note on APT modes 结论 Slow, overloaded, uni- and bi-directional Faster, uni-directional


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