Robust Prediction of Ordnance Depth of Burial in Soils Using Field Calibrated Phenomenological Model & Probabilistic Simulations
Dr. Stephan Bless | New York University
The overall objective of this project is to deliver a demonstrated methodology for predicting the depth of burial (DoB) of munitions at former test ranges. The methodology will be based on a robust phenomenological model for penetration into soils. It will be probabilistic, specifying maximum depths and confidence levels. Features of the methodology that will ensure success include:
- It will be site specific, relying on in situ data from locations of interest.
- The inputs required for the projectiles will be baled on standard munition descriptions.
- It will not require subject-matter experts in soil mechanics.
Technical challenges will be met by a series of models, and experiments for hypothesis testing and calibration that will take place first in the laboratory and then in situ. The core of the approach is a phenomenological model guided by numerical calculations and calibrated by experiments. The model development and laboratory experiments comprise Task 1: development of the probabilistic hybrid Poncelet-CPT model (CPT is cone-penetrometer test). Using the Poncelet framework, the model will establish connections between penetration parameters and soil properties. Experiments will include direct measurement of the strength of soils as a function of loading rate, visualization of mesoscale soil response, and most importantly novel ballistic tests to directly measure Poncelet coefficients for selected soils at two rates: high rates manifested in projectile penetration, and low rates pertaining to cone-penetrometer tests. The model will be stochastic in terms of prediction of Poncelet coefficients. Since results from Task 1 are essential to ultimate success, a Go/No Go review will be conducted at its completion, 22 months after initiation of the project. Task 2 will be validation of the model through field measurements. Field measurements will include CPT and ballistic penetration, using conventional and newly developed apparatus, and limited soil characterization observations. The field testing will also lead to refinement of the probabilistic treatment to take into account uncertainties that arise from sampling. The third and ultimate task will be synthesis of the previous results into a field manual. An advisory panel will be convened to critically review the manual and to aid its acceptance by the user community. The technical work will be performed by a team of researchers from the Department of Civil and Urban Engineering at New York University, the Department of Civil Engineering from Manhattan College, and the Ballistics Research Laboratory at Southwest Research Institute. There will be consultation with SERDP and other cognizant DoD researchers through the execution of the project. In addition to the user manual, there will be scholarly publications in soil mechanics and penetration mechanics and participation in SERDP symposia.
Remediation of military ordnance test sites will become much more cost effective when this project is completed because range managers will have a good estimate of the probability that unexploded ordnance (UXO) will lie deeper than can be easily detected by surface probes. In addition, the project will result in a significant advance in the state of the art for engineering models for cohesive and cohesion-less soil penetration. Quantitative data for physical properties of several baseline soils will be made available.