Evaluating the Long-Term Durability of Lime Treatment in Hydraulic Structures: Case Study on the Friant-Kern Canal

2020 ◽  
Vol 2674 (6) ◽  
pp. 431-443 ◽  
Author(s):  
Pavan Akula ◽  
Narain Hariharan ◽  
Dallas N. Little ◽  
Didier Lesueur ◽  
Gontran Herrier
Keyword(s):  
Slope Failure ◽  
Fluorescence Analysis ◽  
Engineering Properties ◽  
Hydraulic Structures ◽  
Lime Treatment ◽  
Geochemical Model ◽  
Bureau Of Reclamation ◽  
Tenfold Increase ◽  
Geochemical Reactions

The slopes along the Friant-Kern Canal were last treated in the 1970s with 4% quick lime to mitigate issues related to slope failure caused by expansive Porterville soils. The immediate benefits of lime treatment were well documented by the Bureau of Reclamation. However, questions remain over the long-term durability of lime-treated materials. In this study, we compare the engineering properties and changes in the soil mineralogy of treated and untreated sections to establish the effectiveness of lime after more than 40 years of performance. A geochemical model was developed using the GEM-Selektor program to simulate the geochemical reactions in the soil-lime system and predict stable pozzolanic products. The experimental results show a reduction in the plasticity index from 23 to 6 after lime treatment together with a tenfold increase in strength. Lime addition lowers the risk of volumetric expansion and erosion in soils from moderately high to very low. Further, a pH increase from 6.30 to 8.90 in lime-treated sections indicates that lime treatment continues to be effective. X-ray fluorescence analysis shows the presence of Ca2+ ions in quantities similar to the initial treatment dosage indicating negligible leaching of lime. The geochemical model provides evidence of the formation of pozzolanic products in the soil-lime system which was validated using thermogravimetry analysis. The performance history of the Friant-Kern Canal together with the findings of this study affirm the long-term durability of lime treatment on this project and strengthens the case for using lime in the repair of hydraulic structures.

Forensic Analyses and Rehabilitation of a Failed Highway Embankment Slope in Texas

2021 ◽  
pp. 036119812199635
Author(s):  
Burak Boluk ◽  
Anand J. Puppala ◽  
Sayantan Chakraborty ◽  
Puneet Bhaskar
Keyword(s):  
Mechanical Properties ◽  
Laboratory Tests ◽  
Slope Failure ◽  
Engineering Properties ◽  
High Plasticity ◽  
Slope Failures ◽  
Lime Treatment ◽  
Embankment Slope ◽  
The Stability ◽  
Highway Embankment

A comprehensive investigation was designed and conducted to identify the potential causes of failure of a highway embankment slope in Texas and evaluate the effectiveness of lime treatment to rehabilitate the failed slope. Highway slopes built with high plasticity clays often experience shallow slope failures after exposure to repeated wet–dry weathering cycles. Lime stabilization generally reduces the swell–shrink potential, enhances the engineering properties of problematic clayey soils, and can potentially prevent surficial slope failures. However, exposure to wet–dry cycles can negate some of the benefits of lime treatment and therefore a study was conducted to address the use of this lime treatment to stabilize embankment slopes. Extensive laboratory tests were conducted to study the effect of weathering cycles on the degradation of hydro-mechanical properties of untreated and lime-treated soils. Rainfall-induced slope stability analyses were performed to investigate the probable causes of slope failure and evaluate the stability of lime-treated surficial slope. The optimum stabilizer dosage and treated layer thickness required for the slope rehabilitation were determined based on laboratory tests and numerical analysis results. The stability analysis results indicate that the degradation of surficial soil’s hydro-mechanical properties and the development of a perched water table during prolonged rainfall possibly caused the slope failure. The post-treatment increase in shear strength properties, reduction in moisture fluctuations recorded by embedded moisture sensors, and the presence of newly installed underlying drains are expected to prevent recurrence of surficial slope failures. Salient results from this study are covered in this paper.

scholarly journals Pseudogymnoascus destructans growth in wood, soil and guano substrates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jenny Urbina ◽  
Tara Chestnut ◽  
Jennifer M. Allen ◽  
Taal Levi
Keyword(s):  
Dna Extraction ◽  
Emerging Infectious Diseases ◽  
Transmission Risk ◽  
Pseudogymnoascus Destructans ◽  
White Nose Syndrome ◽  
Management Interventions ◽  
Pathogen Persistence ◽  
Tenfold Increase ◽  
And Control

AbstractUnderstanding how a pathogen can grow on different substrates and how this growth impacts its dispersal are critical to understanding the risks and control of emerging infectious diseases. Pseudogymnoascus destructans (Pd) causes white-nose syndrome (WNS) in many bat species and can persist in, and transmit from, the environment. We experimentally evaluated Pd growth on common substrates to better understand mechanisms of pathogen persistence, transmission and viability. We inoculated autoclaved guano, fresh guano, soil, and wood with live Pd fungus and evaluated (1) whether Pd grows or persists on each (2) if spores of the fungus remain viable 4 months after inoculation on each substrate, and (3) whether detection and quantitation of Pd on swabs is sensitive to the choice to two commonly used DNA extraction kits. After inoculating each substrate with 460,000 Pd spores, we collected ~ 0.20 g of guano and soil, and swabs from wood every 16 days for 64 days to quantify pathogen load through time using real-time qPCR. We detected Pd on all substrates over the course of the experiment. We observed a tenfold increase in pathogen loads on autoclaved guano and persistence but not growth in fresh guano. Pathogen loads increased marginally on wood but declined ~ 60-fold in soil. After four months, apparently viable spores were harvested from all substrates but germination did not occur from fresh guano. We additionally found that detection and quantitation of Pd from swabs of wood surfaces is sensitive to the DNA extraction method. The commonly used PrepMan Ultra Reagent protocol yielded substantially less DNA than did the QIAGEN DNeasy Blood and Tissue Kit. Notably the PrepMan Ultra Reagent failed to detect Pd in many wood swabs that were detected by QIAGEN and were subsequently found to contain substantial live conidia. Our results indicate that Pd can persist or even grow on common environmental substrates with results dependent on whether microbial competitors have been eliminated. Although we observed clear rapid declines in Pd on soil, viable spores were harvested four months after inoculation. These results suggest that environmental substrates and guano can in general serve as infectious environmental reservoirs due to long-term persistence, and even growth, of live Pd. This should inform management interventions to sanitize or modify structures to reduce transmission risk as well early detection rapid response (EDRR) planning.

Research on the Ecological Protection Mechanism and Applied of Expansive Soil Slope

2014 ◽  
Vol 501-504 ◽  
pp. 359-367
Author(s):  
Feng Zhou ◽  
Kai Zhang ◽  
Ying Chun Tang
Keyword(s):  
Slope Failure ◽  
Expansive Soil ◽  
Treatment Method ◽  
Engineering Properties ◽  
Soil Slope ◽  
Protection Mechanism ◽  
Temperature Changes ◽  
Ecological Protection ◽  
Slope Treatment ◽  
Vegetation Formation

This paper summarizes and analyzes the basic concepts and ecological protection mechanism for expansion geotechnical slope failure mechanism and the resulting impact on the shallow, traction engineering properties such as analysis, proposed ecological slope of expansive soil slope mechanism of action: vegetation system by improving internal slope soil moisture and temperature changes affect the atmosphere and thus effectively reduce the depth. Vegetation root through reinforced anchoring, delay time and improving soil hydration ductility such as the role played good strength enhancement. Vegetation formation can effectively improve the damaged outer slope interface morphology, to restore the ecological environment and landscape effect. Integrating the past experience on expansive soil slope treatment, this paper provide a slope treatment method used in Nanning metro Tunli section, these will provide reference for the expansive soil slope ecological management.

Intensified paraglacial slope failures due to accelerating downwasting of a temperate glacier in Mt. Gongga, Southeastern Tibet Plateau

2021 ◽  
Author(s):  
Yan Zhong ◽  
Qiao Liu ◽  
Yong Nie ◽  
Matthew Westoby ◽  
Bo Zhang ◽  
...  
Keyword(s):  
Slope Failure ◽  
Geological Structure ◽  
Tibet Plateau ◽  
Type B ◽  
Current State ◽  
Triggering Factor ◽  
Type C ◽  
Glacier Ablation ◽  
Glacial Denudation

<p>Topographic development via paraglacial slope failure (PSF) represents a complex interplay between geological structure, climate, and glacial denudation. Where debris generated by PSFs is deposited on the surface of a glacier, this debris can increase the extent or thickness of a supraglacial debris-cover, in turn modifying glacier ablation and affecting meltwater generation. To date, little attention has been paid to intensity and frequency of PSFs and their significance as a geomorphic agent and hazard in glacierised, monsoon temperate regions of Southeast Tibet. We mapped PSFs along the 5 km-long, west-east trending ice tongue of Hailuogou Glacier (HLG), Mt. Gongga, using repeat satellite- and UAV-derived imagery between 1990 and 2020. Three types of PSF were identified: (A) rock fall, (B) slide and collapse of sediment-mantled slopes, and (C) gulley headwards erosion. We analyzed the formation, evolution and current state of these PSFs and discuss these aspects with relation to glacier dynamics and paraglacial geomorphological history. South-facing slopes (true left of HLG) showed more destabilization and higher PSF activity than north-facing slopes. We observed annual average rates of downslope sliding for type B PSFs of 1.6-2.6 cm d<sup>-1</sup>, whereas the average upward denudation rate for type C PSFs was 0.7-3.39 cm d<sup>-1</sup>. We show that type A PSFs are non-ice-contact rock collapses that occur as a long-term paraglacial response following glacier downwasting and the exposure of steep rocky cliffs and which could also be influenced by precipitation, freeze-thaw cycling, earthquakes or other factors. In contrast, type B and C PSFs are a more immediate response to recent glacier downwasting. We further argue that the accelerating downwasting of glacier are used as a preparatory or triggering factor, which could directly or indirectly cause the PSFs.</p>

Effect of Lime on Compaction, Strength and Consolidation Characteristics of Pontian Marine Clay

2015 ◽  
Vol 72 (3) ◽  
Author(s):  
Siaw Yah Chong ◽  
Khairul Anuar Kassim
Keyword(s):  
Construction Material ◽  
Soft Clay ◽  
Engineering Properties ◽  
Dry Density ◽  
Marine Clay ◽  
Maximum Dry Density ◽  
Stabilization Phase ◽  
Compaction Curve ◽  
Stabilized Soil

Marine clay is a problematic construction material, which is often encountered in Malaysian coastal area. Previous researchers showed that lime stabilization effectively enhanced the engineering properties of clay. For soft clay, both strength and consolidation characteristics are equally important to be fully understood for design purpose. This paper presented the effect of lime on compaction, strength and consolidation characteristics of Pontian marine clay. Compaction, unconfined compression, direct shear, Oedometer and falling head permeability tests were conducted on unstabilized and lime stabilized samples at various ages. Specimens were prepared by compaction method based on 95 percent maximum dry density at the wetter side of compaction curve. It was found that lime successfully increased the strength, stiffness and workability of Pontian marine clay; however, the permeability was reduced. Unconfined compressive strength of stabilized soil was increased by 49 percent at age of 56 days whereas compressibility and permeability was reduced by 48 and 67 percent, respectively. From laboratory tests, phenomenon of inconsistency in engineering characteristics was observed for lime stabilized samples below age of 28 days. This strongly proved that lime stabilized soil underwent modification phase before stabilization phase which provided the long term improvement.

scholarly journals Conservation of Subfossil Bones from a Lacustrine Setting: Uncontrolled and Controlled Drying of Late Quaternary Vertebrate Remains from Cold Lake, Western Canada

2018 ◽  
Vol 32 (1-2) ◽  
pp. 1-13
Author(s):  
Christina I. Barrón-Ortiz ◽  
Matthew R. Sawchuk ◽  
Carmen Li ◽  
Christopher N. Jass
Keyword(s):  
Freeze Drying ◽  
Late Quaternary ◽  
Fluorescence Analysis ◽  
Drying Methods ◽  
Western Canada ◽  
Long Term Storage ◽  
Water Saturated ◽  
Cold Lake ◽  
Surface Delamination

Abstract Water-saturated vertebrate remains (e.g., bone, antler, and ivory) are particularly challenging to stabilize for long-term storage, research, and analysis. These types of specimens are sensitive to damage caused by water loss, which frequently results in delamination, twisting, and cracking. The recovery of late Quaternary vertebrate remains from underwater areas of Cold Lake, western Canada, prompted us to conduct a series of analyses to better understand the preservation of the remains and their susceptibility to damage, and to test different conservation techniques to achieve successful drying. X-ray fluorescence analysis of a sample of specimens revealed that the remains have particularly high iron concentrations, a condition that might have contributed to weaken their structure, further compromising their integrity when drying. Additionally, we found that certain bone elements, such as long bones, are more susceptible to severe surface delamination than others, and as a result these specimens should be monitored more closely during their treatment. Of the four drying methods we tested, controlled air-drying produced the best results, followed by solvent-drying. In contrast, vacuum freeze-drying and vacuum freeze-drying with 20% v/v Acrysol WS-24 in water, an acrylic dispersion, while rapid, resulted in differing degrees of delamination and cracking.

Bridge 1-351 over Muddy Run: Design, Testing, and Erection of an All-Composite Bridge

2000 ◽  
Vol 1696 (1) ◽  
pp. 118-123 ◽  
Author(s):  
J. W. Gillespie ◽  
D. A. Eckel ◽  
W. M. Edberg ◽  
S. A. Sabol ◽  
D. R. Mertz ◽  
...  
Keyword(s):  
Large Scale ◽  
Flexural Rigidity ◽  
Limit State ◽  
Engineering Properties ◽  
Molding Process ◽  
Strength Limit ◽  
Large Scale Testing ◽  
Longitudinal Joint ◽  
Composite Bridge

Bridge 1.351 on Business Route 896 in Glasgow, Delaware, was replaced with one of the first state-owned all-composite bridges in the nation. Composites are lightweight construction materials that do not corrode, which results in benefits such as ease of construction and reduced maintenance costs. A summary of the design, large-scale testing, fabrication, erection, and monitoring of this bridge is presented. The bridge was designed to AASHTO load and resistance factor design specifications. A methodology was developed to incorporate the engineering properties of these unique composite materials into the design. The bridge consists of two 13 × 32 ft (3.96 × 9.75 m) sections joined by a unique longitudinal joint. The sections have sandwich construction consisting of a core [28 in. (71.12 cm) deep] and facesheets [0.4 to 0.6 in. (10.16 to 15.24 mm) thick] that provide shear and flexural rigidity, respectively. The composite bridge was fabricated with E-glass preforms and vinyl-ester resin, which offers excellent structural performance and long-term durability. Each of the sections was fabricated to near-net shape in a single step by a vacuum-assisted resin transfer molding process. The overall structural behavior has been accurately predicted with simple design equations based on sandwich theory for anisotropic materials. Large-scale testing of full-sized subcomponents was conducted to prove that the design satisfied deflection, fatigue, and strength limit states. A redundant longitudinal joint was designed that consisted of both an adhesively bonded vertical joint between sections and splice plates. Assembly procedures were developed, and transverse testing of the full-sized joint was conducted. Final bridge sections were proof-tested to the strength limit state. The construction phase included section positioning, joint assembly, and application of a latex-modified concrete wear surface. The bridge was reopened to traffic on November 20, 1998. Results from the long-term monitoring effort will be documented.

scholarly journals General Assessment of the Operational Utility of National Water Model Reservoir Inflows for the Bureau of Reclamation Facilities

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2897
Author(s):  
Francesca Viterbo ◽  
Laura Read ◽  
Kenneth Nowak ◽  
Andrew W. Wood ◽  
David Gochis ◽  
...  
Keyword(s):  
Water Model ◽  
Short Term ◽  
Bureau Of Reclamation ◽  
Hydrologic Processes ◽  
One Year ◽  
Inflow Performance ◽  
Basin Area ◽  
National Water ◽  
Total Inflow

This work investigates the utility of the National Oceanic and Atmospheric Administration’s National Water Model (NWM) for water management operations by assessing the total inflow into a select number of reservoirs across the Central and Western U.S. Total inflow is generally an unmeasured quantity, though critically important for anticipating both floods and shortages in supply over a short-term (hourly) to sub-seasonal (monthly) time horizon. The NWM offers such information at over 5000 reservoirs across the U.S., however, its skill at representing inflow processes is largely unknown. The goal of this work is to understand the drivers for both well performing and poor performing NWM inflows such that managers can get a sense of the capability of NWM to capture natural hydrologic processes and in some cases, the effects of upstream management. We analyzed the inflows for a subset of Bureau of Reclamation (BoR) reservoirs within the NWM over the long-term simulations (retrospectively, seven years) and for short, medium and long-range operational forecast cycles over a one-year period. We utilize ancillary reservoir characteristics (e.g., physical and operational) to explain variation in inflow performance across the selected reservoirs. In general, we find that NWM inflows in snow-driven basins outperform those in rain-driven, and that assimilated basin area, upstream management, and calibrated basin area all influence the NWM’s ability to reproduce daily reservoir inflows. The final outcome of this work proposes a framework for how the NWM reservoir inflows can be useful for reservoir management, linking reservoir purposes with the forecast cycles and retrospective simulations.

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