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INVESTIGATION OF IMPACT STRESSES INDUCED IN LABORATORY DYNAMIC COMPACTION OF SOFT SOILS
Author(s) -
THILAKASIRI H. S.,
GUNARATNE M.,
MULLINS G.,
STINNETTE P.,
JORY B.
Publication year - 1996
Publication title -
international journal for numerical and analytical methods in geomechanics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.419
H-Index - 91
eISSN - 1096-9853
pISSN - 0363-9061
DOI - 10.1002/(sici)1096-9853(199610)20:10<753::aid-nag846>3.0.co;2-r
Subject(s) - geotechnical engineering , dynamic compaction , stiffness , deformation (meteorology) , soil water , linear elasticity , compaction , geology , constitutive equation , shear (geology) , structural engineering , mechanics , engineering , finite element method , soil science , oceanography , physics , petrology
Abstract The majority of currently available analytical tools to predict ground stresses due to impact are based on linear spring‐dashpot dynamic models. Although these simple models adequately represent stiff ground possessing linear visco‐elastic behaviour, they suffer from two striking limitations when applied to relatively softer ground; (1) the inability to account for the permanent deformation resulting from impact, (2) failure to incorporate stiffness changes of softer soil within the impact duration. In this paper, the authors present an improved analytical approach formulated on the basis of a series of laboratory impact tests, to address the shortcomings of the current dynamic models in relation to soft soils. In this procedure, the impact zone is modelled as three distinct zones; (1) a zone beneath the falling weight undergoing non‐linear axial deformation while being in vertical motion, (2) an inner zone immediately surrounding zone 1 with non‐linear shear deformation, and (3) an outer zone undergoing a relatively lower degree of (linear) shear deformation. The soil constitutive parameters pertinent to the model are obtained from a modified dynamic compression test that simulates the impact conditions. It is shown that analytical predictions of the impact stress history and penetration are in agreement with test results. The findings are useful in the exploration of dynamic compaction techniques that will be effective in soft soil improvement.