M.M. Ahmadi, P.M. Byrne, R.G. Campanella
The University of British Columbia, Vancouver, Canada
ABSTRACT
The paper presents the results of a
numerical modeling for cone penetration in layered soil. Experimental studies
show that as the tip advances into different soil layers, it senses the effects
of an approaching layer. The cone penetration tip resistance is influenced by
the soil properties ahead and behind the tip. The interface distance over which
the tip resistance senses the effect of a soil layer is reported to be 5 to10
times the cone diameter. With the present analysis, the complete process of
cone penetration is modeled as the cone starts to penetrate the soil from the
ground surface to any deeper layers below the ground. This capability of the
program enables the analysis of penetration in layered soil to be modeled in a
realistic way. The commercial computer program FLAC is used for this analysis.
INTRODUCTION
Cone penetration analysis has been the
subject of research for more than three decades. To tackle this boundary value
problem, many different procedures are suggested. Bearing capacity theory
[Meyerhof (1961), Durgunoglu and Mitchell (1975)], cavity expansion theory [Vesic
(1972), Yu and Houlsby (1991), Salgado et al. (1997), Shuttle and Jefferies
(1998)], strain path method [Baligh (1985), Teh and Houlsby (1991)], and finite
element analysis [van den Berg et al. (1996)] were used to analyze the
penetration process. Yu and Mitchell (1998) present a comprehensive review of
different methods in the analysis of cone resistance. Though there have been a
number of papers in the literature presenting solutions for cone penetration,
the aspect of penetration in layered soil has been inadequately addressed. In
this Paper, a new approach for cone penetration is discussed. To validate the
reliability of this approach the experimental results from calibration chamber
tests in sand are compared with the numerical values obtained with the present
approach. Thereafter, the results of numerical analysis in layered soil are
discussed. This new modeling technique can be used to analyze the penetration
in layered soil in a realistic way. The commercial computer code FLAC (1998)
has been used for this analysis.