Researcher Aids Arkansas Highway Projects Through Subsurface Analysis

Source: Researcher Aids Arkansas Highway Projects Through Subsurface Analysis | University of Arkansas FAYETTEVILLE, Ark. – A University of Arkansas geotechnical engineer is collaborating with the Arkansas Department of Transportation to map subsurface conditions before road construction begins to identify issues early and help keep highway construction projects on track and on budget. Clint Wood, a civil engineering associate professor and geotechnical engineer, creates profiles of subsurface conditions and soil composition by sending stress waves into the ground and measuring their response at the surface. The non-invasive technology is similar to how ultrasound imaging works on the human body. The technology provides important information for highway designers and construction contractors, who’ve had to rely on imperfect methods for determining subsurface conditions, such as exploratory drilling, a strategy that can miss changes between limited drilling locations. Wood compares designing based on limited exploratory drilling to navigating with an incomplete map. The research is conducted for and in conjunction with the Arkansas Department of Transportation. With an additional $115,318 grant, the transportation department has provided a total of $561,427 in funding. The work focuses on estimating the depth and stiffness of bedrock for new highway alignments and understanding subsurface conditions that cause slope instability. The latter is especially important for understanding how water moves through a slope. Unexpected changes in bedrock depth near slopes can also create pockets where water collects, which can cause the soil in the slope to become saturated, leading to instability. Projects that encounter these issues can face substantial extra costs and delays while designers and contractors adapt the original plan or have to attempt another repair. Those problems can be avoided, or at least minimized, by better understanding the subsurface conditions through non-invasive testing. LIDAR AND DRONE ACCURACY In a separate project, Wood and several other U of A [...]

Corps honors Flynn for geotech work

Source: Corps honors Flynn for geotech work EDWARDSVILLE — Southern Illinois University Edwardsville School of Engineering (SOE) alumnus Stefan Flynn has been recognized as the 2021 U.S. Army Corps of Engineers (USACE) Early Career Geoprofessional of the Year. “While simply being nominated for this award meant a lot to me, I was humbled to have been selected,” said Flynn. “It was equally exciting to see an award created for early career professionals. This award is a testament to the leadership of the Geotechnical, Geology and Materials Community of Practice and their efforts to support, involve and recognize our employees at all professional levels.” “For those organizations that are not already doing so, I highly encourage you to consider ways to recognize your younger/early career professionals,” said Flynn. “I am both proud and grateful to work for such a dedicated and impactful organization as the USACE with our great teams across the nation, within the Mississippi Valley Division, and at home in the Rock Island District.” In 2014, while pursuing a bachelor’s in civil engineering at SIUE, Flynn began working with the USACE as a student intern at the St. Louis District. Upon graduation in 2015, he was offered a full-time job with the Rock Island District. He currently serves as a senior geotechnical engineer and conducts design, construction and inspection of dams, levees and navigation structures. The Early Career Geoprofessional of the Year award recognizes Flynn for exhibiting professionalism and commitment to excellence through: • Enhanced regional and/or national projects, • Achievements and innovations in geotechnical engineering, geology or materials engineering, • Contributions to professional/technical societies, • Enhanced relationships with peers, partners and contractors, and • Demonstrated exemplary levels of trust and integrity. During his time at SIUE, Flynn served as a research assistant and conducted research for the Illinois [...]

Concrete Dam Safety Inspection with Ground Penetrating Radar GPR

Source: Concrete Dam Safety Inspection with Ground Penetrating Radar GPR | For Construction Pros A non-destructive with ground-penetrating radar inspection could save time and money during investigations of this critical element in concrete infrastructure. GSSI using the Structure Scan™ Mini XT to refine the dam survey area. Geophysical Survey Systems As the world struggles to improve its critical infrastructure, many are seeking out non-destructive testing (NDT) methods that can help to accurately determine what can be repaired and what needs to be replaced. In the field of dam safety, NDT methods are seen as a way to cut down on the actual work that has to be done, while making sure that condition data is most accurate. Engineers, facility managers, and dam operators need accurate information on the structural health of their facility to take decisive action to prevent catastrophic incidents. Earthquake monitoring systems can assist decision-making by providing predictive data before an earthquake and evaluating the structural integrity of the dam or levee before and immediately after an earthquake (Dam Safety Group,  Ground-Penetrating Radar for Dam Investigative Applications, 2021) Among the available NDT methods, ground-penetrating radar (GPR) is growing in importance for dam evaluation applications. Increasingly, both public- and privately-funded dam owners are looking to GPR technology to inspect the dam infrastructure and surrounding areas. GPR can be cost-effectively integrated with other types of ground surveys to build a visual understanding of the overall subsurface of the site. The technology can be rapidly deployed, provides an effective means to evaluate subsurface information, and contributes to continuous monitoring and condition assessment throughout a structure’s life. In response to the need for the best possible NDT methods, several industry experts founded the Dam Safety Group, which provides a wide range of geophysical and seismic techniques and technologies to address non-invasive [...]

South Dakota Homeowners Sue County Over Sinkhole Risks

Source: South Dakota Homeowners Sue County Over Sinkhole Risks More than 150 homeowners in a development outside Rapid City, South Dakota, are suing Meade County over risks to their properties after a sinkhole exposed an abandoned gypsum mine. The federal complaint filed Sept. 27 by Hideaway Hills residents in Black Hawk seeks damages to be determined by a jury and other relief “allowed by law or equity.” The sinkhole forced about 40 residents from 15 homes in April 2020. Geotechnical studies show there could be water flowing through the abandoned mine and toward Interstate 90 and there is the potential for future sinkholes, the Rapid City Journal reported. The complaint alleges several violations of the state Constitution. It says the decision to approve the subdivision by the county Planning Commission and the Meade County Commission put homeowners at risk. “Without the decisions to approve the subdivision, issue building permits and certificates of occupancy, the opportunity for harm would not have existed,” the complaint states. Developers allegedly informed the county in 2001 of an underground gypsum mine and discussed taking steps to determine if it was safe to build on. The commission approved the subdivision proposal in 2003. Katelyn Cook, an attorney for the county, said her legal team does not comment on pending litigation. South Dakota isn't the only area that suffers from sinkholes. Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania tend to have the most damage from sinkholes.

Microbial material modification helps to control frost heave and saline soil solidification

Source: Microbial material modification helps to control frost heave and saline soil solidification Chinese researchers recently conducted a study on process of biogas generation improving physical and mechanical properties of soil. A research team led by Sheng Yu from the Northwest Institute of Eco-Environmental Resources (NIEER) of the Chinese Academy of Sciences (CAS), together with their colleagues from Southeast University, has implanted Pseudomonas Stutzeri in the soil pores and induced it to produce nitrogen bubbles, and they also analyzed the influence mechanism of mitigation of sand liquefaction using biogas bubbles. In the natural environment, there are many microorganisms in rock and soil masses, and its metabolic activities will change physical and mechanical properties of rock and soil. These microbial activities can be controlled, enhanced and used to solve geotechnical problems, and such methods have been named as biogeotechnologies. As an emerging interdisciplinary field, it has developed rapidly in recent years due to its advantages of low carbon and friendly environment. From the perspective of practical application, biogeotechnologies can be used for rock and soil reinforcement, sealing of water leakage, prevention of sand liquefaction, soil erosion resistance control, and contaminated soil treatment and so on. Based on the above research results, the NIEER research group is exploring to apply biogeotechnologies to frost heave control and saline soil solidification, and has achieved some preliminary results. In this study, the researchers applied biogas generation process to soil frost heaving treatment, and studied improvement of biogas production performance under low temperature conditions. Results showed that sealing effect of bubbles and microorganisms on the water migration path can reduce soil permeability coefficient by one order of magnitude. Besides, they also introduced biomineralization to solve the prominent problem of saline soil with high chloride content in Northwestern China. Based on excellent curing effect, they analyzed the deterioration mechanism of [...]

Lancaster County sinkhole raises concern over detours, emergency responder response times

Source: Lancaster County sinkhole raises concern over detours, emergency responder response times | WHP LANCASTER COUNTY, Pa. — A nearly 20-foot sinkhole on State Route 324 (Marticville Road) between Sprecher Road and West Penn Grant Road in Lancaster County is causing detours for community members and concern over delays for emergency responders. PennDOT implemented a detour Sunday night, originally anticipating work to fill the sinkhole would begin in a month. PennDOT Engineering District 8 Press Officer Dave Thompson exclusively tells CBS 21 News’ Samantha York Thursday the timeline has extended. “We expect this road might be closed into next spring before we can actually start working on it,” Thompson says. “That’s- that’s news to me,” New Danville Fire Company Fire Chief Brad Shenk says. 20% of his 25 active volunteer firefighters live on the opposite side of the sinkhole and respond to emergencies from home in a rural town. He says being delayed for a few minutes can make a big difference when time is of the essence, requesting the sinkhole to be filled sooner. “It’s going to have an adverse effect on our response times to get those members here,” Shenk tells CBS 21’s Samantha York. “We’re a small fire company, we’re counting on everybody to go up at any given time, whoever’s available responds and these guys are going to be delayed by several minutes.” Community members speculate the sinkhole, which reaches from the middle of the road through a drainage ditch and into adjacent property, has something to do with new construction nearby. However, the cause remains undetermined by officials – which is causing the delay in getting it fixed. “We’ve assessed what needs to be done, but we need to get some- an agreement in place with a local property owner that’s property is adjacent to [...]

California Issues Maps of Earthquake Faults to Avoid ‘Potentially Devastating’ Damage to New Buildings

Source: State Issues Maps of Earthquake Faults to Avoid 'Potentially Devastating' Damage to New Buildings - Times of San Diego The Rose Canyon Fault system. Courtesy County News Center Maps released Thursday of earthquake-prone areas are intended to ensure new construction in San Diego does not take place atop dangerous quake faults. Developed by the California Geological Survey, the regulatory Alquist-Priolo Earthquake Fault Zone maps detail where local governments must require site-specific geologic and engineering studies for proposed developments to ensure this hazard is identified and avoided. Generally, new construction for human occupancy must be set back 50 feet from the active surface trace to avoid faults that may break the surface. “Surface fault rupture is the easiest earthquake-related hazard to avoid because you can see the evidence of where it has occurred,” said Steve Bohlen, acting state geologist and head of CGS. “Surface fault rupture means that one side of a fault is moving either vertically or horizontally in relation to the other side. The deformation that movement causes is potentially devastating to buildings and infrastructure.” Two maps of revised Earthquake Fault Zones have been prepared for the Rose Canyon Fault where it comes onshore in Coronado, traversing the San Diego area to the northwest and going back offshore near La Jolla. Each of the maps covers a roughly 60-square-mile quadrangle of territory. The Alquist-Priolo Act was passed into law following the 1971 magnitude 6.6 San Fernando earthquake, which caused extensive surface ruptures that damaged buildings. Not every large earthquake, though, causes surface fault rupture. For example: the Loma Prieta Earthquake of 1989 devastated the Bay Area without breaking the surface. However, the 1992 Landers Earthquake in San Bernardino County caused surface ruptures along 50 miles, with displacements ranging from one inch to 20 feet. “Since the [...]

Dynamic behaviors of wind turbines under wind and earthquake excitations

Source: Dynamic behaviors of wind turbines under wind and earthquake excitations: Journal of Renewable and Sustainable Energy: Vol 13, No 4 Source: How Do Wind Turbines Respond to Winds, Ground Motion During Earthquakes? - AIP Publishing LLC A new study investigates the combined effect of wind and earthquake forces to assess the dynamic behavior of wind turbines. The demand for renewable energy is nowadays at its peak. Wind power is a great source of clean energy and is harvested via wind farms placed in numerous regions across the world. This has led to some winds farms being established in earthquake-prone regions making it important to assess the combined excitation under wind and earthquake forces. In the US, these wind farms are most commonly seen in Alaska, Arkansas, California, Idaho, Illinois, Kentucky, Missouri, Montana, Nevada, Oregon, South Carolina, Tennessee, Utah, Washington, and Wyoming. The study, recently published in the Journal of Renewable and Sustainable Energy, aims at establishing a numerical model that will integrates both seismic, wind, and operation forces of wind turbines to evaluate the performance of the wind turbines. This is referred to as the "fully coupled model". Such models have been tested before but the research team emphasizes that a solid interpretation of the results is still missing. The authors studied a 5MW wind turbine subjected to a combination of wind load and input ground motion with the latter being retrieved from a list of earthquake records. The study provides some interesting findings. The results from the sophisticated numerical models suggest that the wind that acts as a dynamic load for the wind turbine also exerts a damping effect on the response of the structure. In particular, when shaking is strong, the energy absorbed due to the aerodynamic damping is higher than the actual wind loading generates hence, the [...]

Soil Nail Walls Design and Construction

Source: Soil Nail Walls - Design and Construction -NEW (7003IW2022) INSTRUCTOR:  Naresh Samtani, Ph.D., P.E., D.GE, F.ASCE Participants will have access to the virtual workshop video archives and materials for 60 days from the start day of the workshop. Virtual Workshop Brief Using a collaborative and interactive learning approach, this virtual workshop will help you understand the design and construction aspects for soil nail walls. You will learn newer design approaches based on the LRFD platform that is the basis for guidelines for soil nail walls by the American Association of State Highway and Transportation Officials (AASHTO) and the Federal Highway Administration (FHWA). The workshop will help you assimilate the design and construction aspects through active participation by frequent interactions throughout the workshop and real-time expert feedback. The interactions will facilitate a better understanding of the nuances of the newer design principles which would help you avoid costly design errors in real-world projects. In between the two live sessions, attendees will independently work on an application (e.g., exercises) or a reflection (e.g., reading) assignment. Learning Outcomes Upon completion of this course, you will be able to: Explain the terminology for soil nail walls Explain design of soil nail walls using principles of limit state design Explain the essential elements of construction Recognize construction procedures and influence on wall design and performance Explain the importance and concepts of nail testing Identify necessary characteristics of software tools Explain corrosion considerations Discuss facing (shotcrete) analysis Identify the necessary information on plans and specifications Benefits for Participants Become familiar with the latest limit state design approaches and standards for soil nail walls Avoid common pitfalls and costly errors in analysis and design Be able to categorize and streamline limit state evaluation Recognize the importance of considering construction as part of overall design process Assessment of [...]

Breaking Uncommon Ground in the Kansas Countryside

Source: Breaking Uncommon Ground in the Kansas Countryside - Alpha-Omega Geotech, Inc. Look beyond I-435 to the west of Kansas City’s urban core and you’ll see a surge of new commercial development taking shape. It’s not all typical, flat farmland and turning it into opportunity requires a strategic approach. Before you put together plans for a construction project, consider a few pointers based on our experience. Don’t Be Surprised by a Predictably Unpredictable Subgrade. Be careful not to make assumptions about what’s just below the surface and deeper down, especially along K-10 in the vicinity of Lenexa. Every potential build site is different to some degree and variations from site to site can be substantial. Much of the landscape is hilly, and history has left behind miscellaneous man made factors that will impact everything from site selection to construction. Decades of variables ranging from undocumented subgrade material, buried trees and buried gravel roads to improperly filled farm ponds lurk underground, even in areas that appear to be untouched. In addition, old limestone mines abandoned as far back as the 1980s wind through the area and present ongoing challenges for developers. The proximity of mines isn’t necessarily a deal breaker when it comes to project site selection, but you’ll need to clearly understand the limitations of the subgrade above and around them. You’ll also need to be on the lookout for mine spoils material carved out over the years and buried for disposal. Uncovering subgrade wildcards and narrowing site selection is only possible through an extensive investigation. A precise boring plan with thorough soil testing will be critical in the hunt for a project site that’s feasible in context of your timeline and budget. Make sure your geotechnical engineering partner knows exactly how you expect foundations to perform so that they can pinpoint [...]

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