GHG emission analysis of an optimal arrangement of stiffened composite pile group based on bearing capacity: A case study

Abstract

Stiffened composite pile (SCP) composed of cement-soil mixing piles and precast pipe piles have been widely used in the construction industry to effectively handle soft soil in foundation treatments. In this study, the mechanical properties of a SCP were analyzed through field tests and numerical simulations and the optimal arrangement of the SCP group was obtained. The greenhouse gas (GHG) emissions during the construction process of the SCP group were calculated by considering three aspects: material consumption, mechanical requirements, and labor consumption. The results were then evaluated and compared with those of the traditional bored cast-in-place pile (BCP) group. It was found that the optimal arrangement of ground treatment with the SCP group was determined with a pile having an inner core diameter of 500 mm, an outer diameter of 700 mm and pile spacing of 2.8 m, which is four times the pile outer diameter. Compared to the BCP group, the SCP group has advantages of 6.16 % reductions GHG emissions of building materials, 42.76 % that of mechanical usage, and 53.11 % that of labor consumption. The final settlement of pile groups exhibits a clear negative correlation with their GHG emissions. The variation in GHG emissions is primarily dependent on changes in pile spacing, while the effect of the inner core pile diameter is relatively minor. The scientific significance of this study is rooted in the quantitative evaluation and comparison of GHG emissions during the construction phase of two different types of pile foundations. It also elucidates the interplay between the load-bearing capacity of SCP group and their GHG emissions. This study can serve as a crucial reference for the design and construction of foundation engineering, ensuring that pile foundation construction aligns with both the requisite load-bearing performance and low-carbon construction standards.