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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 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
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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
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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
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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
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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
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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
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Two MLS66 being delivered in 2008 两台超大型 MLS66 在 2008 年投入使用
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同济大学和辽宁省交科院
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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
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Mozambican Pavement Structure Problem Statement 世行项目
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Research Overview 研究总观
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200μm electron microscope photos of yellow sand vs. red sand (hydrometer results compatible) yellowred
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Scaled Subbase and Base in Laboratory 试验室
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Namibia Field Application LTPP comparable to MMLS3 Performance Prediction Field testing in Namibia Rut after wet field testing
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Latest Laboratory Test Bed, Profilometer and Water Heater
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MLS studies in global perspective 2008 Applications MMLS MMLS3 Labs US Europe Africa MLS10/66 Owners/ Applications China
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MMLS3 Tyre contact stresses being measured by SIM of CSIR Refer de Beer and Sadzik SATC 2007
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Salient Features of MMLS3 Testing that need to be borne in mind 小型三分之一比例尺 MLS
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Analysis of MMLS3 Performance Stress Potential
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Comparison of Vertical Compressive Stresses MMLS3 vs Trucks (Epps et al., WesTrack)
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Deflection vs. speed under full-scale truck traffic
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Comparison between some MMLS3 Results at different trafficking speeds Axles x1000 Rutting mm 1m 4mm
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MMLS3 Testing in conjunction with the HVS on N4 near Pretoria 现场试验 MODIFIED BENKELMAN BEAM
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BASE / SUBGRADE
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Red Sand
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HOT MIX ASPHALT (HMA)
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ROLLER PERFORMANCE DURING CONSTRUCTION
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MONITORING EFFECTIVE STIFFNESS RELATIVE TO DENSITY OF COMPACTION
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Construction of CTB
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Test Site during construction!
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MONITORING OF TRIAL SECTION STIFFNESS AFTER CONSTRUCTION
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PSPA DATA ANALYSIS Portable Seismic Pavement Analyzer 便携式 P-SPA
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First Correlations of Seismic Stiffness and Cracking
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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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Response Model (after Jooste) 100 150 200 250 Tensile Strain (microstrain) LET FE (Static – Square loading area) FE (20 km/h) FE (80 km/h)
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Stiffness vs. HVS Reps (after Jooste)
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Load Setting / PSPA
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Trafficking
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Rut Measurements
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NCAT field study Phase 2 Core holes 在美国测试
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NCAT HMA damaged by wet trafficking
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Stiffness loss during trafficking of S9 NCAT 路面刚度损失
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Wet SASW stiffness Young's Modulus vs. Load applications (30 Hz) in Texas (See SAICE - 2002)
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Stiffness loss during trafficking of all NCAT sections
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SASW NCAT after 10 Million E80s
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Surface Wave Test - NCSU Effect of Microcracking
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Fatigue cracks NCSU
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APT PERFORMANCE MONITORING IN LABORATORY
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Relative stiffness ratios for MMLS3 and MLS10 – 7% CTB in lab and field
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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 32.5 + 2.5% LIME Red2 640mm AC 3.5% CEMII 32.5 + 3.5% 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 32.5 + 4% SS60 Red2
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Layout of Test Sections
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HVS and MMLS3 on R80 Pta West 测试结果对比
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VERTICAL CONTACT STRESS PROFILES MMLS3 vs.HVS @ 750 kPa contact stress– 91% (R80 Pta West)
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SHEAR STRESS PROFILES MMLS3 vs. HVS @ 750 kPa contact stress–75% (R80 Pta West)
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MMLS3 Data Processing (R80 Pta West) Rutting - Extended Standard Mix vs Rut resistant mix
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MMLS3 Data Processing (R80 Pta West) Rutting - Standard Mix vs Rut resistant mix
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MMLS3 Data Processing (R80 Pta West) Extrapolation of Rutting Data: 0-50k; 0-100k; 0-150k; 0-200k = 12% difference
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MMLS3 Data Processing (R80 Pta West) Rutting Profiles - Heave (left and right@ 450mm)
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Key to application of the MMLS3 Understanding APT: distress mechanisms performance related factors
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Applications MMLS MMLS3 Labs US Europe China Africa MMLS3 studies in global perspective
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MLS10 after completion of field trial on 25 yr old untrafficked section of stiff HMA/CTB pavement in Switzerland 在瑞士量侧
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A Concluding Note on APT modes 结论 Slow, overloaded, uni- and bi-directional Faster, uni-directional
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