Semi-analytical BEM-FEM analysis of passive vibration isolation by a row of SDCM piles in saturated soil

A novel eco-friendly pile, i.e., Stiffed Deep Cement Mixing (SDCM) pile, is introduced to construct a single-row or multi-row of piles to isolate the ground vibrations in the paper. The dominant frequency of ground vibrations due to the metro-train and heavy-duty trucks is obtained by a series in-site measurement. Thereafter, the practicability of using SDCM piles as wave barrier is discussed through an in-situ test, and it shows that a row of SDCM piles can mitigate ground vibrations to a certain degree. Moreover, to investigate the screening efficiency of a row of SDCM piles for scattering incident Rayleigh waves in saturated soil, a 3D semi-analytical boundary element method (BEM)-finite element method (FEM) coupling model and the algorithm implementation were developed. The effects of the model parameters on isolation effectiveness were examined and thoroughly discussed. The results show that a row of SDCM piles with precast high-strength concrete (PHC) core piles can isolate the ground vibrations due to incident Rayleigh waves, and the PHC piles play a critical role in the barrier system. A row of SDCM piles with full-length core piles demonstrates superior isolation effectiveness to those with shorter core piles. Increasing the number of piles in a row can achieve improved vibration isolation effectiveness, while the clear net spacing between adjacent piles has a limited influence on the overall isolation performance. According to these results, the use of full-length core piles and a clear net spacing of 0.2∼0.3 λ R (Rayleigh wavelength) are recommended in practical engineering applications. • l A novel environmentally friendly vibration barrier using SDCM piles is proposed for the first time. • l A 3D semi-analytical BEM-FEM coupling model is developed to simulate a row of SDCM piles as barrier in saturated soil. • l Full-length precast core piles are shown to be critical, significantly enhancing isolation performance. • l increasing pile number improves screening efficiency, while pile spacing and core pile type have limited influence on overall vibration isolation