Trung, L.T., Thuy, D.D. and Anh, P.V. 2019. Experimental testing of a full-scale of group efficiency in multiple soil layers. Journal of Science and Technology in Civil Engineering (JSTCE) - HUCE. 13, 3 (Aug. 2019), 135-142. DOI:https://doi.org/10.31814/stce.nuce2019-13(3)-13.