UD researchers study climate change impacts on soils at military installations

Source: The Ground Underfoot - Civil and Environmental Engineering UD researchers study climate change impacts on soils at military installations We walk over it, drive over it and build on it. Yet, it is probably safe to say, most of us rarely think about the ground beneath our feet. Underneath the grass, concrete, asphalt and other materials in our built environment, however, soil provides structure and stability for what lies above. The United States military wants to understand the role that climate impacts, such as flooding, storm surge or sea level rise, will have on soils at its coastal military bases and facilities, which are critical to national security. Soil conditions can affect the integrity of the ground underpinning buildings, roads, bridges and more. For example, if a soil’s pH were to rise significantly, due to increased salt content-containing ions such as sodium from storm surge, it could create saline conditions that could hamper the ground’s ability to support this necessary infrastructure. Understanding these threats will enable faster and more accurate routing and maneuverability for U.S. forces. The Delaware Environmental Institute (DENIN) is collaborating with the Engineer Research and Development Center (ERDC) of the U.S. Army Corps of Engineers and Louisiana State University to understand how vulnerable military installations along coasts may be affected by soil changes due to sea level rise and coastal flooding. DENIN has received $3.79 million in first- and second-year funding from the U.S. Department of Defense to start this work, and is eligible for an additional $3.82 million in continued funding over the following two years. Led by DENIN Director Don Sparks, Unidel S. Hallock du Pont Chair of Soil and Environmental Chemistry in UD’s Department of Plant and Soil Sciences, the UD effort includes interdisciplinary collaboration with Yan Jin, Edward F. and Elizabeth Goodman Rosenberg Professor [...]

ASU Receives Western States Seismic Policy Council Award in Excellence

Source: Sustaining solid ground | ASU News   A team of faculty members and students in the Ira A. Fulton Schools of Engineering at Arizona State University contributed to a major geotechnical engineering field research project recently recognized with a 2021 Western States Seismic Policy Council Award in Excellence. Associate Professor Leon van Paassen led the group from ASU’s Center for Bio-mediated and Bio-inspired Geotechnics, in a collaboration with researchers from Portland State University and the University of Texas at Austin. The endeavor has been funded by the Natural Hazard Engineering Research Infrastructure program of the National Science Foundation. Recent ASU civil engineering doctoral graduate Elizabeth Stallings Young (second from the right) is shown with Portland State University students and staff members involved in characterizing soils near the Portland International Airport, one of two main sites for a major soil liquefaction research project supported by the National Science Foundation. Van Paassen and Professor Edward Kavazanjian, director of the Center for Bio-mediated and Bio-inspired Geotechnics, have collaborated on projects to reduce the impact of earthquakes on soils. One of these aftereffects is liquefication, or the process by which soil saturated with water loses strength, which can lead to ground failure. ​The multi-university project involves microbially induced desaturation — called the MID technique — for mitigation of earthquake-induced liquefaction in silty soils. Photo by Leon van Paassen/ASUDownload Full Image Seeking earthquake and engineering solutions The work has included treating two test sections located within the Port of Portland Critical Energy Infrastructure hub (the Harborton site) and adjacent to Portland International Airport (the Sunderland site). The map shows two sites in the vicinity of Portland International Airport and the Port of Portland Critical Energy Infrastructure hub that are test sections for the research to develop techniques for reducing soil damage as a result of earthquakes. Map courtesy of Portland State University There, researchers monitored the treatment performance and [...]

Using Torque Testing for Better Designs

Source: Using Torque Testing for Better Designs All Engineers can relate to an experience we’ve had where what we designed was not how it turned out in “the real world”. Rarely does a project end up being exactly as what we put down on paper. Soil testing for foundation supports is no exception and unfortunately these differences almost never end on the positive side of a cost estimate. One way to mitigate those differences is to use a testing process which directly relates with the type of foundation being used. For helical piles, while there are well-established trends between ASTM D1586 N60 blow count N values and potential pile length, even the slightest variations in testing methods and/or soil description can create significant differences in the “design” versus “reality”. The more accurate method for a helical pile foundation design would be to do actual torque tests (a.k.a. helical probe tests) at the site. While most designs initially begin with a Geotechnical Report including boring logs, for helical piles using an actual torque test prior to start of work instead will provide a much more accurate picture of soil capacity and allow for a finite design. Even with boring logs and N60 blow counts being used for preliminary designs, a torque test can be used to “fine-tune” the foundation design. Many owners might think that the additional cost associated with a site torque test, albeit nominal, is not needed. However, time and time again, the small additional cost has proven to save substantial money on the foundation project by allowing the engineer to confirm and enhance their foundation design. In addition, site torque tests can be incorporated directly into a design created in the HeliCAP® v3.0 Helical Capacity Design software to provide real time updates to designs giving better solutions with more confidence. Adding actual [...]

2021 Erosion and Sediment Control Field Days

The Southern New England Chapter of the Soil and Water Conservation Society (SWCS) is hosting a 2021 Erosion & Sediment Control Field Days on Wednesday October 6th & Thursday October 7th. It will be a hybrid experience combining virtual presentations, hands-on experience, and outdoor demonstrations. Attending both sessions as a registered attendee, 6.5 hours of continuing education credits will be available. There is a 100% virtual option as well.

Earthquake in Haiti Triggers Landslides

Source: Hundreds of landslides followed Haiti earthquake, Tropical Depression Grace - The Washington Post Source: Earthquake in Haiti Triggers Landslides After a 7.2 magnitude earthquake hit southwestern Haiti on the Saturday morning of August 14th, hundreds of landslides threatened the area. Landslides are one of the biggest causes of earthquake-related deaths. In 2010, the earthquake near Haiti's capital, Port-au-Prince, killed roughly 200,000 people and led to tens of thousands of landslides. The earthquake was centered about eight miles southeast of Petit-Trou-de-Nippes at a depth of six miles. USGS reported at least 150 landslides south of the epicenter, to the west of the town L'Asile. The mountains and south of Beaumont experienced hundreds more. “Even though a lot of the central and western parts of the epicentral area have been obscured by cloud cover, we haven’t seen too many landslides in the gaps in the clouds,” wrote Robert Emberson, a landslide researcher at NASA’s Goddard Space Flight Center. “We anticipate that the bulk of the landsliding (at least from the earthquake) is in the [Pic Macaya] National Park.” The National Hurricane Center predicted 5 to 10 inches of rain in Haiti with a possibility of up to 15 inches. Flash flooding, mudslides, and landslides were all expected following the rain. “With the ongoing tropical storm rainfall, further landslides are likely,” wrote Emberson. “In particular, landslide material mobilized by the earthquake may be washed downstream as debris flows. We will continue to monitor changes over the coming days to assess the exacerbated impact of the rainfall and provide situational awareness.” Landslides and earthquakes have recently in multiple parts of the world. Denali Park, Sichuan China, Battle Creek Michigan, and a recent Monsoon in India are just four of the most recently affected areas.

Environmental Regulations Changing China’s Hydropower Stations

Source: China’s Thousands of Small Dams Struggle to Stay Afloat Chen Tai’an poses for a photo atop the Hongsha Hydropower Station dam in Liuyang, Hunan province, 2021. Diao Fanchao for Sixth Tone   For decades, rural areas along the Yangtze River depended on small hydropower stations. Now, amid rising ecological costs and safety concerns, the government wants to make them more sustainable. Early in April, continuous rain lashed the central city of Liuyang, Hunan province for days. As the Yangtze River Basin entered its major flood season and its banks swelled, Chen Tai’an stood inside the hydropower plant he partly owns, listening to the rumble of its turbines. He says it’s the best time of the year to generate hydropower since most turbines operate at full capacity. But this year has been different. Chen says his Hongsha Hydropower Station’s annual revenue fell by more than 30,000 yuan ($4,600) as its output was cut by 100,000 kilowatts per hour. The reduced power generation stemmed from new, and more stringent, government guidelines for maintaining “ecological water flow” — the level and quality of water in rivers to sustain the local ecosystem. According to a 2018 government policy mandated for small hydropower stations, Chen couldn’t store water during the dry spell between August and March — meaning river water could no longer be fully stored to generate electricity as in previous years. So he was given until August of last year to install a floodgate on the dam to release one-tenth of the annual runoff into the river, with which he complied. “All that water wasted… such a shame,” says Chen, looking at the river and furrowing his brow. He’s still pondering what the government meant by “ecological water flow.” To him, all river water is a valuable resource, and using turbines to turn it into [...]

Sichuan China Earthquake

Source: Sichuan, China: Earthquake leaves three dead and 60 injured - CNN An earthquake in China's southwestern province of Sichuan left at least 3 people dead and 60 injured on September 16th, according to China's state-run media. Local authorities put the quake at 6.0-magnitude, while the US Geological Survey (USGS) put it at 5.4-magnitude on an 8-point scale. The quake hit in the early hours of the morning, with the epicenter located about 52 kilometers (32.3 miles) southwest of Yongchuan district in Chongqing, with an initial depth of 10 kilometers, according to USGS. The earthquake left at least 1,221 collapsed houses and more than 3,000 severely damaged homes, according to the Global Times. "I woke up to the tremor and saw the chandelier in my room swinging dramatically and the writing desk was shaking," one resident, surnamed Tang, told the Global Times. "It's been a long time since an earthquake of this magnitude has occurred." Chinese authorities launched rescue efforts in the morning, with the provincial government activating a level 2 response, the second highest in China's four-tier earthquake emergency response system, according to Xinhua. Luzhou City, home to about five million residents, was among the hard-hit areas. Thousands of soldiers and emergency workers have been sent on rescue efforts, along with rescue equipment, medical supplies, makeshift surgical vehicles and heavy machinery. Tents have been set up for evacuees in a nearby village. Experts say a more serious earthquake is unlikely, though there may be aftershocks, Xinhua reported. Sichuan is located along one of several seismic belts in China, which makes it prone to earthquakes. One local employee in Luzhou told the Global Times that though residents are used to earthquakes, they are usually of a lower magnitude -- and Thursday's quake was much stronger than average. A number of [...]

3D Finite Element Analysis of a Contiguous Pile Wall

Source: 3D Finite Element Analysis of a Contiguous Pile Wall Source: RS3 | 3D Finite Element Software For Advanced Analysis | Rocscience 3D Finite Element Analysis of a Contiguous Pile Wall Introduction This article provides a brief summary of a 3D finite element analysis carried out using RS3 to model a contiguous pile retaining wall at the site of a proposed commercial development in the UK. The development site is located on sloping ground approximately 35 m from a motorway cutting. Due to the sloping topography of the site, cut and fill earthworks are to be undertaken to form a level development plateau upon which a large warehouse is to be built. This will require the construction of a circa 400 m long contiguous pile retaining wall to support the ground along the site’s upslope boundary where ground levels will be reduced by up to 8.4 m. Wall Design A plan showing the arrangement of the piles and the 2.0 m wide by 0.8 m deep capping beam is shown in Figure 1. The main 900 mm diameter piles are 17 m long and are staggered in a zigzag arrangement at 0.25 m offsets either side of the capping beam centerline. Interspersed mid-way between the main piles are 600 mm diameter infill piles. The infill piles are located along the capping beam centerline and are 11 m long. Figure 1: Pile and capping beam arrangement Ground Conditions The ground conditions are summarized in Figure 2 which shows a 2D section perpendicular to the wall alignment at the location where the retained height attains its maximum value of 8.4 m. The succession of strata comprises a veneer of clay-rich Glacial Till overlying Coal Measures bedrock. The Coal Measures bedrock is dominated by siltstone and mudstone and has been divided into three [...]

Parameters Variation Model Customization and Sensitivity Analyses

Source: Parameters Variation: Model Customization and Sensitivity Analyses Parameters Variation Model Customization and Sensitivity Analyses A well-known engineering challenge in the framework of finite element (FE) analysis-based design is the large number of input factors involved in geotechnical computational models. There is always a significant amount of uncertainties associated with the properties of geomaterials, being naturally highly heterogeneous materials. In the context of model calibration and validation, conducting a sensitivity analysis is very important. This can determine the key factors which govern the system and efficiently characterize the geotechnical variability for any considered design problem.   Powerful mechanisms for the consideration of parameter variation are also very interesting for speeding up FE model creation and automating results in post-processing. These are also quite useful in reducing model definition for specific types of engineering problems (excavation wall of a specific type under simple ground conditions, simple tunnel shape in uniform rock mass, etc.) to a limited number of parameters that can be inputted in a text file or Microsoft Excel spreadsheet without expert knowledge of the PLAXIS user interface and different modeling techniques and FE know-how. The sensitivity analysis and parameter variation tool in PLAXIS A sensitivity analysis determines how different values of an independent variable affect a particular dependent variable under a given set of assumptions. In other words, sensitivity analyses study how various sources of uncertainty in a mathematical model contribute to the model's overall uncertainty. The Sensitivity Analysis and Parameter Variation tool (see Figure 1) can be used to evaluate the influence of model parameters on calculation results for any particular PLAXIS FE model: The Select Parameters tab sheet will first provide information about all the parameters that can be changed to perform the sensitivity analysis. Available parameters include most model parameters of the data sets for soil and [...]

A Climate Change-Induced Disaster in Denali National Park

Source: A Climate Change-Induced Disaster in Denali National Park | Time The Times has recently showcased an article on the current rockslide situation in Denali National Park. The effects of climate change have been dramatic with the current melting of the permafrost. The National Parks Service has recently upped through gravel removal of the Pretty Rocks Landslide in an effort to keep up as the rapidly thawing permafrost picks up pace. Alaska is right now recognized as the country’s fastest-warming state. The landslide hit unprecedented speed 4 weeks ago causing the team to close the back half of the park weeks earlier than anticipated. This only signals bad news as reservations are canceled in the short term and the long term implications are yet unknown. “This is the canary in the coal mine for infrastructure disruption in Alaska,” says the Camp Denali lodge owner Simon Hamm. “If things continue on the path they’re on, it’s not going to just be Pretty Rock—it’s going to be half of the Alaskan highway system.” Rapid deterioration Denali National Park is one of the U.S.’s largest national parks at 6 million acres, and sits about four hours north of Anchorage. While the entrance to the park is certainly beautiful, many people prefer to hop on buses to access the park’s marquee attractions deep down its single 92-mile road: views of Mt. Denali (formerly Mt. McKinley), the highest peak in North America at 20,000 feet; the gleaming Wonder Lake; rolling mountainsides that contain an abundance of wildlife, including grizzly bears, moose, caribou and bighorn sheep. About halfway along the road lies the Pretty Rocks Landslide, a slowly sliding section of earth that acts more like a glacier than a rockfall. Since the 1960s, permafrost deep below the earth’s surface has thawed, causing the soil and [...]

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