In the bustling urban landscapes where underground tunnels and surface buildings coexist, a delicate dance of deformations plays out, one that engineers and urban planners must carefully navigate. A recent study, led by Yazdan Shams Maleki, an Assistant Professor in the Civil Engineering Department at Kermanshah University of Technology in Iran, has shed new light on this complex interaction, offering a simplified method to estimate ground deformations in building-tunnel scenarios. This research, published in the journal ‘مدلسازی پیشرفته در مهندسی عمران’ (Advanced Modeling in Civil Engineering), could have significant implications for the energy sector and urban infrastructure development.
The challenge of analyzing the mutual deformation effects between tunnels and surface buildings is compounded by the nonlinearity of soil and the intricate characteristics of buildings. Maleki and his team tackled this issue head-on, presenting a simplified method based on two- and three-dimensional finite element numerical analyses. “We aimed to make the process more efficient and accessible,” Maleki explained, “by introducing logical and facilitating simplifications in the definition of tunnel-building interaction.”
The study utilized the maximum cross-section of the Kermanshah urban train tunnel for numerical modeling, comparing the obtained deformation values with actual field measurements from other valid references. The results were promising, with vertical displacement modeling yielding a difference of only 1.45% to 6.67% when compared to field results. The difference in overall displacement results between the NATM staged tunneling model in the 3D model of a reference article and the 3D model of this study was a negligible 7.14%.
One of the most compelling aspects of this research is the presentation of a simple exponential mathematical equation to estimate deformations, efforts, and internal forces of the tunnel lining system with increasing surface construction overhead. This equation boasts a high accuracy, with a coefficient of determination greater than 0.90. “We found a clear relationship between the changes in horizontal displacement responses, settlement, shear stress, shear strain, internal efforts of the reinforced concrete lining of the tunnel, and the surface structure overhead,” Maleki noted.
The study also revealed that the horizontal displacements of the soil mass above the tunnel crown are about 25% of the vertical displacements (settlements). This finding could have significant commercial impacts for the energy sector, particularly in the planning and construction of underground energy infrastructure in urban areas.
The implications of this research extend beyond immediate practical applications. By simplifying the analysis of building-tunnel interactions, Maleki and his team have opened the door to more efficient and accurate modeling in the future. This could lead to safer, more cost-effective construction practices and better-informed urban planning decisions.
As cities continue to grow and expand underground, the need for such innovative approaches will only increase. Maleki’s work serves as a testament to the power of advanced modeling and simplification in addressing complex engineering challenges. With further research and development, the methods presented in this study could become a standard tool in the toolkit of civil engineers and urban planners worldwide.