26 Sep 2024

A Geospatial Model for Identifying Stream Infrastructure Locations

Abstract: Management of hydraulic infrastructure for flood control, hydropower, navigation, and water supply is a critical component of the Army Dams and Transportation Infrastructure Program (ADTIP). This project provides a tool to locate stream infrastructure using a one-dimensional approach supplemented with geospatial filtering that only needs digital elevation model (DEM) files as primary input. The regions in and around Forts Liberty, Sill, and Cavazos were selected as study areas, and stream networks with corresponding stream elevation profiles were created and searched for elevation changes that met vertical threshold and search window criteria. Recall, Fβ, and a ratio of under to overprediction were used to evaluate performance. The search algorithm generally overpredicts the number of stream infrastructure locations and especially so for large search windows (20 or 25 cells) and small vertical threshold values (5 or 10 m). Overall, it was found that midrange vertical threshold values (2 or 2.5 m with long search windows (20 or 25 cells) with the land cover classification (LCC) check applied yielded results that minimized false negatives and overpredictions. The significance of this tool is that it may reduce costly field investigations, or at least aid in the prioritization of site visits for hydraulic infrastructure managers.

26 Sep 2024

High-Rate Characterization and Modeling of a Hyperelastic Block Copolymer Subjected to Ballistic Impact

Abstract: A polystyrene-polyisobutylene-polystyrene star-block copolymer (PS-PIB-PS) is a thermoplastic elastomer with visco hyperelastic characteristics that displays a high level of toughness and performs well in shock attenuating applications. The research goal is to investigate experimentally and numerically the capacity of PS-PIB-PS to dissipate kinetic energy and examine its deformation and failure modes under impact by spherical steel projectiles at speed ranges of 200–1,700 m/s. First, PS-PIB-PS is characterized using a Split-Hopkinson Pressure Bar to measure high strain rate response and calibrate a hyperelastic material model. Second, ballistics tests are conducted on 12 in. × 12 in. PS-PIB-PS targets with various thicknesses to determine the ballistic limit and residual velocity (Vr) versus impact velocity (Vi) relationship. Finally, ALE3D is used to model the ballistic response and capture the extreme deformation observed during testing. During ballistic impact tests, significant deformation occurred on the backside of polymer targets, followed by perforation of the polymer, culminating with retraction and recovery of the polymer in a self-healing manner. Numerical simulations captured the deformation behavior during impact and predicted the Vr versus Vi response with high accuracy. This research provides a method of modeling hyperelastic materials subjected to ballistic impact and provides a better understanding of energy dissipation of these materials.

25 Sep 2024

Accelerated Concrete Flexural Strengths for Airfield Pavements

Abstract: Mixture-proportioning studies and submittals are an integral part of the pavement design and planning process as outlined in the Unified Facilities Guide Specification 32 13 14.13 for Department of Defense airfield pavements. Many aspects of the required testing are time-consuming due to the duration of the test (e.g., alkali–silica reaction experiments) or to the required concrete age at testing (e.g., compressive or flexural strength testing). Time awaiting testing results often delays projects and adds cost. The objective was to develop an accelerated testing requirement for flexural strength (currently 650 psi or greater at 90 days), thereby reducing the time to pavement acceptance. Potential accelerated testing methodologies were evaluated in a literature review. A statistical analysis generated under a design of experiments protocol determined concrete flexural strength gain and correlation ratios. Results of the statistical analysis showed that a reduced flexural strength of 600 psi could be accepted at 14 days and still reach the minimum flexural strength requirement of 650 psi at 90 days with high certainty (i.e., greater than 95% certainty). Additionally, the results stemming from the design of experiments compared favorably with data gathered from four mixture-proportioning submittals acquired via the Transportation Systems Center.

12 Sep 2024

SEG-2 Viewer MATLAB App User Guide

Purpose: This technical note documents the functionalities of the SEG-2 Viewer and provides a step-by-step user guide for the application. SEG-2 Viewer is a MATLAB app that was developed at the Geotechnical and Structures Laboratory (GSL) of the US Army Engineer Research and Development Center (ERDC) for visualizing and analyzing geophysical data in SEG-2 format.

11 Sep 2024

Helical Anchor Installation with the High Mobility Engineer Excavator: Proof-of-Concept Testing

Abstract: Proof-of-concept testing was conducted to determine the viability of helical anchor installation using the US Army’s High Mobility Engineer Excavator (HMEE). To facilitate the proof-of-concept test, a new hydraulic hose kit was designed that connects the Bridge Supplemental Set (BSS) drive motor to the HMEE’s auxiliary hydraulic system. Additionally, a steel mount was fabricated that provided means to attach the BSS drive motor to the boom of the HMEE. Testing indicated the HMEE can successfully install the BSS anchors with the required hardware, but the vehicle’s large footprint will likely increase the installation time compared to previous methods. Several improvements to the hydraulic hose kit design were identified through the experiment, and guidance was created to facilitate efficient HMEE usage in the future. Once a permanent solution is developed to mount the BSS drive motor to the HMEE, the capabilities of the BSS will be greatly expanded by allowing each Multi-Role Bridge Company to install anchors using multiple vehicle types.

11 Sep 2024

Evaluation of the Bridge Supplement Set overhead cable system with uneven bank heights

Abstract: A numerical model was developed to analyze the effects of environmental conditions and construction layout on the structural capacity of the modernized Bridge Supplemental Set (BSS). Environmental variables included even and uneven bank heights, soil strength, river width, and river flow rate conditions. Construction variables included tower placement, tower guy line orientation, and catenary length. Loading conditions, the drag force of the bridge due to river current, were conservatively applied with the assumption of uniform flow rate across the entire river width to account for the wide range of operating environments in which the BSS may potentially be used. Analysis of system performance informed several BSS construction optimizations to maximize system capabilities over the wide range of conditions considered. Catenary length was found to have the greatest influence on system performance, indicating that a small increase in catenary length would greatly reduce the loading on the critical components of the BSS, thus increasing the capacity and safety of the system. A stand-alone computer program was developed to quickly provide BSS construction guidance for a large variety of operating conditions, as the number of charts and figures required to account for most scenarios numbers in the thousands.

9 Sep 2024

Leveraging Artificial Intelligence and Machine Learning (AI/ML) for Levee Culvert Inspections in USACE Flood Control Systems (FCS)

Abstract: Levee inspections are essential in preventing flooding within populated regions. Risk assessments of structures are performed to identify potential failure modes to maintain the safety and health of the structure. The data collection and defect coding parts of the inspection process can be labor-intensive and time-consuming. The integration of machine learning (ML) and artificial intelligence (AI) techniques may increase accuracy of assessments and reduce time and cost. To develop a foundation for a fully autonomous inspection process, this research investigates methods to gather information for levees, structures, and culverts as well as methods to identify indicators of future failures using AI and ML techniques. Robotic plat-form and instrumentation options that can be used in the data collection process are also explored, and a platform-agnostic solution is proposed.

4 Sep 2024

Comparison of Numerical Simulations of Heat-Induced Stress in Basalt

Abstract: Energy losses due to excessive noise and heat are primary liabilities in traditional mining processes. Some of the currently researched methods to improve these liabilities involve heating the rock to induce internal stress fractures that make it easier to extract or remove rock with traditional mining equipment. Physical experimentation has yielded useful data that have been applied to numerical simulations of the heating and fracturing of rock, and multiple such simulations have been developed in the commercial multiphysics simulator COMSOL. Since COMSOL is not widely available on DoD high-performance computers, the goal of this research is to develop methods of replicating simulations developed in COMSOL as simulations that run in Abaqus FEA, another commercial multiphysics simulator. In this work, a simulated basalt cylinder with a 25 mm radius and a 158 mm height is subjected to a surface heat flux approximating the effects of a laser beam applied to the top of the cylinder. Simulated stress distributions, displacements, and temperatures obtained from both simulators are compared. When comparable results were not obtained using both simulators, the differences in results were investigated using simplified versions of the simulation.

15 Aug 2024

Repair Quality Assessment: Spiral 4

Abstract: The Expedient and Expeditionary Airfield Damage Repair (E-ADR), Joint Capability Technology Demonstration (JCTD) program developed, demonstrated, and transitioned a repeatable capability for rapidly repairing bomb-damaged craters at adaptive base locations using logistically friendly technologies, indigenous materials, and less manpower than traditional crater repair methods. Within the E-ADR JCTD program, quality assessment took a major role to ensure quality repairs were performed while meeting the requirements of “just enough, just in time.” Repair criteria for backfill compaction and surface cap quality were developed through extensive testing. These criteria were incorporated into an easy-to-use and deployable smartphone application, the E-ADR Repair Assessment (ERA) application. This report focuses on the backfill quality assessment criteria development, roughness tolerance of surface caps checking procedure, and the development of the ERA application. The criteria and the ERA application both proved successful in the expedient evaluation of backfill and surface cap materials.

11 Jul 2024

Sliver Spall Mitigation: Field Investigation, Laboratory Study, and Mixture Proportioning Analysis

Abstract: A combined field and laboratory study was conducted to identify factors contributing to sliver spall of concrete pavements and recommend avenues for prevention. In this study, spall density maps of eight airfields were created, and cores were taken for petrographic analysis. A companion laboratory study evaluated nondestructive testing equipment for identifying concrete prone to sliver spalling. Concrete mix designs with good and poor performance were analyzed for trends in mixture proportioning and aggregate gradation. Spall density mapping indicated sliver spalling was more likely to occur on longitudinal joints and that the distress was not solely a material or mixture design-related issue. The laboratory study concluded that surface resistivity measurements were able to differentiate edge-finishing techniques (normal versus overworked, mortar-rich edge) after seven days of curing. An analysis of particle packing theory and mixture proportioning trends showed there was substantial overlap in the gradations for good and poor performing pavement. Thus, acceptable mixture designs can produce poor quality pavement if not constructed properly. The main contributors to early age sliver spalling of concrete airfield pavement occur during pavement construction.