DEVELOPMENT OF A GEOPHYSICS-BASED MULTIPHASE CONSTITUTIVE MODEL
Abstract
bstract: Soil deposits are inherently spatially and temporally variable. Variations of material types, state conditions (e.g. density, degree of saturation), and stress states (e.g. in situ stresses, pre-consolidation stresses) dramatically affect the mechanical behavior of a soil mass. Thus, because of this spatial variability, the mechanical behavior of a soil mass can differ significantly for one location to another within the deposit. It therefore becomes apparent that it is critical to quantify the variability of soil properties within a soil mass and assess how that variability affects the three-dimensional mechanical behavior of the mass. However, the measurements required to comprehensively assess spatial and temporal variability of a terrain are difficult to obtain and are not well understood. Remote characterization of land surfaces and subsurfaces using geophysical methods, allow for the determination of material properties and behavior over a large spatial domain. The geophysical properties of a soil system are affected by parameters such as soil type, pore structure, degree of saturation, stress state, and history. These parameters also affect the strength and deformation behavior of a soil system. Thus, there is a high likelihood that geophysical measurements in soil systems will provide a reliable means to evaluate and predict engineering behavior. This research proposes to develop a coupled hydro-mechanical-geophysical multiphase, elastoplastic constitutive model. The proposed model will be developed within a critical state soil mechanics framework and will be capable of predicting the full range of deformation and shear behavior for soils under multiphase moisture conditions (i.e. moisture conditions ranging from partially saturated to saturated states). Unique to the proposed constitutive models is that the input parameters and the forcing functions (i.e. the forces that drive changes in stress and strain states) will be developed directly from in situ measurements of seismic wave velocity and electrical conductivity. The significance of this aspect is that the full range of mechanical behavior for a multiphase geologic material will be predicted at any point and time in a three-dimensional soil mass using geophysical techniques that are readily adapted to remote and autonomous platforms. Significance to the Army: A fundamental understanding and use of terrestrial science knowledge is critical to military success on the battlefield. Rapid and efficient terrain analysis is required before vehicles and weapons systems can be effectively deployed. Subsurface terrain parameters such as soil strength and soil moisture content, are crucial elements of a terrain analysis. Spatial and temporal knowledge of these two parameters provide the Army with insight into areas such as mobility, cover and concealment, and target recognition. The proposed research will develop an elastoplastic constitutive model that will consequently facilitate the acquisition of deformation and strength profiles of multiphase geologic material using remote and autonomous platforms. Also, the proposed research aligns with the ARL Sciences-for-Maneuver Campaign in that it develops the fundamental framework for remote characterization of terrain. This framework will consequently yield new paradigms for change detection and maneuverability.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 25, 2021
- Source ID
- W911NF2110077
Entities
People
- Lindsey Bryson
Organizations
- Army Contracting Command
- United States Army
- University of Kentucky