Predicting fracture geometry via 3D Printing

Predicting rock fracture is crucial in geotechnical engineering, especially in mining, tunneling, and excavation operations. Rock fractures can lead to instability and collapse of structures, posing a significant risk to human safety. By predicting rock fractures, engineers can design and construct safe and stable structures. Moreover, predicting rock fracture is essential in the oil and gas industry to optimize production and reduce costs. Fracturing rock formations can increase the permeability and porosity of the reservoir, allowing for more efficient extraction of oil and gas. However, fracturing can also cause unwanted leaks and fractures, leading to contamination of the surrounding environment. Furthermore, rock fractures can also be a source of seismic activity, and predicting them is crucial for seismic hazard assessment. Seismic activity caused by rock fractures can lead to earthquakes, landslides, and other natural disasters that can cause significant damage to infrastructure and loss of life. Predicting rock fractures is also important in environmental science, particularly in understanding the behavior of groundwater and contaminant transport. Rock fractures can create preferential pathways for water and contaminants to flow through, which can have a significant impact on the quality and availability of groundwater.

Indeed, cracks are everywhere, and they often mean trouble. In the foundation of your house, in your windshield, in the tectonic plates below your feet. But, surprisingly, scientists don’t actually understand them as well as they would like. In a new study published in the peer-reviewed journal Scientific Reports, Purdue physics professor Laura Pyrak-Nolte and her lab team works with Purdue’s Rock Physics Research Group to better understand how and where fractures form. Being able to predict and understand fractures is vitally important to a wide range of fields, including improving the safety and efficacy of natural gas production, carbon sequestration, and nuclear waste disposal. It’s also important in improving the structural integrity of large 3-D-printed components, including bridges and human habitats on other planets.

3D printing of rocks is a technology that allows for the creation of synthetic rock samples using 3D printing technology. This technique involves the use of a 3D printer to build up layers of material, typically using a combination of binders and powdered minerals or other materials that mimic the properties of natural rocks. 3D printed rocks can be used for geomechanical testing, which involves studying the behavior of rocks under different loading conditions. This technology allows for the creation of synthetic rock samples with precise geometries and material properties, which can be used to simulate real-world conditions and improve our understanding of the behavior of rocks under stress. 3D printing of rocks can be a valuable tool for education and outreach, allowing students and the general public to study and interact with geological specimens in a more tangible and accessible way. 3D printing of rocks can also be used for resource exploration, allowing for the creation of synthetic rock samples that closely mimic the properties of natural rocks. This technology can help to reduce the costs and risks associated with traditional exploration methods, such as drilling and excavation.

Overall, 3D printing of rocks is an exciting and rapidly developing field that has the potential to transform the way we study and interact with geological materials, as well as revolutionize resource exploration and geomechanical testing.

In nature, rocks contain a wide variety of features and a diverse array of unique qualities. Among them are the way the layers of minerals form, as well as the orientation of the “mineral fabric”  the way the mineral components that make up rock layers and formations are organized. The research team work centers on the question of whether we can detect fractures remotely and whether we can predict how they form, and can we learn about their fracture geometry from their mineral composition? They had a way to print synthetic rocks out of gypsum, so we could 3-D-print rocks with repeatable features. Many people are familiar with the idea of using a 3-D printer to create plastic items, but fewer realize that you can use a 3-D printer to create synthetic rock samples. Such 3-D-printed rock samples help physicists and engineers study rocks, as they help keep the variables of the experiment controlled. All 3-D-printed substances are made up of layers. In this case, the printer puts down a layer of bassanite powder, a calcium sulfate mineral and, just like an inkjet printer, it goes across spraying a binder, then putting another layer of bassanite on top of it. This printing process induces chemical reaction of bassanite powders with water-based binder solution. The result is a gypsum sample that has layers bound together by gypsum crystals. The power of the process is that researchers can use a computer program to control the quality of every aspect of the synthetic rock. Before 3-D printing technology, scientists either had to study rock samples from nature or casts formed by mixing mineral powder and water. Neither set of samples could be relied upon to be uniform, nor to deliver quantifiable, repeatable results needed to draw firm conclusions about rock mechanics.

Previously scientists testing some rocks from natural rock formations has a lot of discrepancy even if you get two samples very close to each other in location, they will be a bit different. They have all kinds of minerals with natural differences. However,  the new method of 3-D printing technology, it is possible to test rocks and gather reproducible results. The authors were able to design the shape in all dimensions. And it’s a much more accurate process than working with natural rock or casts of rock.

The authors were printing samples with various orientations of mineral fabric, determining if the orientation had any effect on how and where fractures formed when the sample was subjected to tension. When the authors tested randomly generated rock samples made with a traditional casting method. They discovered that in rock samples with no layers and no oriented grains, fractures formed smoothly, with no corrugations. However, different roughnesses emerged in each sample because of the different mechanical qualities in the rock. The key idea is that if we understand how corrugations are produced, just by looking at a rock sample it is possible to remotely predict fracture geometry and preferential flow paths for fluids.