Abstract
The Cone Penetration Test (CPT) is a valuable tool for continuous soil profiling and estimating soil properties. A CPT sounding will often pass through the active zone of an unsaturated soil profile, near the ground surface where moisture conditions and matric suction can vary considerably with depth and time. For many projects, the active zone is also significant to the support of shallow foundations and overlying embankments. However, the strength and stiffness of the unsaturated soils in this zone can be significantly affected by variations in the moisture content and matric suction. Likewise, the cone penetration tip resistance and sleeve friction will be influenced by the variations in moisture conditions and suction. Therefore, it is important to consider the soil moisture conditions when CPTs are conducted relative to the moisture conditions assumed for geotechnical design. This paper presents a method for predicting changes in tip resistance as result of changes in matric suction. The method extends the bearing capacity theory to predict changes in cone tip resistance due to changes in matric suction. CPT data collected at test sites, during wet and dry seasons and representing different soil types, are presented to demonstrate the viability of the proposed method.
Highlights
Due to its rapidity and minimal dependence on the operator, the cone penetration test (CPT) is a valuable tool for characterizing soil stratigraphy and estimating soil properties for geotechnical analysis
This paper presents a method based on bearing capacity theory that can be used to estimate the influence of degree of saturation and matric suction on qc
The method of analysis presented in this paper is based on the soil water characteristic curve (SWCC) as presented by Zapata et al [8], bearing capacity theory for quantifying cone penetration in soil [9] and shear strength of unsaturated soil as presented by Vanapalli et al [10]
Summary
Due to its rapidity and minimal dependence on the operator, the cone penetration test (CPT) is a valuable tool for characterizing soil stratigraphy and estimating soil properties for geotechnical analysis. In most instances the CPT sounding passes through a near surface zone of soil that it is an unsaturated state. Often this zone is critical to the support of overlying structures, in the case of shallow foundations and mats. Depending on the time of subsurface exploration, the unsaturated zone may be dry or wet depending on the season when the CPT soundings are conducted. Soil properties estimated from CPT soundings using traditional analysis techniques will likely overestimate the strength and stiffness of the soil if conducted during a dry season. There is a need to developed methods for interpreting CPT results that consider the degree of saturation and matric suction of the soil at the time the sounding is conducted. This paper presents a method based on bearing capacity theory that can be used to estimate the influence of degree of saturation and matric suction (ua-uw) on qc
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
