Differential Settlement Of Soft Subgrade And Its Influence On Pavment Performance

Differential settlement directly influences structural responses of pavements and governs long-term performance and service life of pavements. Highway construction practices in Sichuan Province show that premature failure of pavements caused by differential settlement is one of the prime distresses of highway pavements. Study on the containment of differential settlement to control its influence on pavement performance is one of the research frontiers in pavement field. Based on the construction practice of Chengdu bypass expressway, theoretical and implemental research efforts about differential settlement of highway subgrades in soft soil area reported in this thesis will promote the design levels of highway geotechnical engineering and pavement engineering and produce significant engineering significance.Comprehensive studies are reported in this paper with respect to differential settlement of subgrades in soft ground. Research efforts include the following subjects. The sources of differential settlement of subgrades were thoroughly explored. Differential settlement consists of three parts: non-uniform deformation of embankments, no-uniform settlement of soft ground, and differential settlement caused by structures. The mechanism causing differential settlement include geometrical, material, structural, and traffic factors. The influence of differential settlement on pavement performance was analyzed using commercial finite element method software, ANSYS, to simulate pavement structures under vehicle applications with subgrade on treated soft ground. Based on research findings, design principles and methods were proposed in the thesis about how to contain the damaging affect on differential settlement on long-term performance of pavement structures.The innovative finding of this thesis is the quantification of the influence of differential settlement on pavement structures based on laboratory tests, load plate tests, field observation and numerical simulation. Conclusions and recommendations of this thesis will have significant effect on the development of pavement design, prevention of premature failure, and reduction in maintenance costs.