Leng Wuming

Numerical Simulation Analysis on Dynamic Stress of Railway Subgrade under Heavy Haul Condition

In current, high-speed and heavy haul has become the development tendency of railway transportation from all over the world. The key of heavy haul railway transportation is to increase the axle load and the number of train formation. However, the current axle load in China is generally much lower than that in many other countries. Further researches on sub grades dynamic response rule and working performance under large axle load are lack. This paper focuses on the feature of heavy haul train loading. By using the finite element numerical calculation based on ABAQUS, sub grade dynamic stress with different axle loads are analyzed, including peak value and spatial distribution characteristics of dynamic stress. The influence law of axle load and adjacent wheel base is discussed. Moreover, the vertical attenuation coefficient curve of dynamic stress is acquired. The conclusions can be used as references for reinforcement of existing sub grade or design of new sub grade.

Calculation and Analysis for the Time-Dependency of Settlement of the Single-Driven Pile in Double-Layered Soft Clay

The dissipation of the pile-side excess pore water pressure caused by pile driving is the main cause of the settlement of single-driven pile in soft clay. Based on the three-dimensional consolidation theory, the calculation formula for reconsolidation settlement of pile-side soil was derived. In addition, the calculation formula for the settlement of the single-driven pile caused by the pile-side soil reconsolidation settlement was derived using the pile-soil interaction principle and by combining boundary conditions in double-layered soft clay. An engineering example was also calculated and analyzed. The research shows that the settlement of the single-driven pile caused by the dissipation of pile-side excess pore water pressure is larger and is far more than that caused by the vertical load. Thus, the settlement of the driven pile was larger than that of the bored pile. The research also indicates that the settlement of the single-driven pile increases with time because of the influence of the pile-side soil reconsolidation, and then it gradually becomes stable.