A unified model for estimating the in-situ small strain shear modulus of clays, silts, sands, and gravels

Carlton, Brian; Pestana, Juan M.

doi:10.1016/j.soildyn.2016.01.019

Cited by 18 publications

(5 citation statements)

References 31 publications

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“…[28] found a large percentage of methicillin-resistant commensal CNSs carrying the ica and atlE genes. The results of the present study are in agreement with previous work carried out by our group in which a high percentage of the ocular microbiota of patients undergoing cataract surgery carries encoding virulence factor genes [11][12][13]. In addition, we have shown a signi cant percentage of patients showed conjunctival isolates before surgery that recovered again after disinfection with 5% povidone-iodine or at the end of surgery.…”

Section: Discussionsupporting

confidence: 93%

“…Disinfection with povidone iodine (PVI) is so far the only measure considered capable of reducing the incidence of endophthalmitis [8][9][10]. Our group has shown in previous studies a high contamination rate of the conjunctiva before and after irrigation with 5% PVI and at the end of the surgery [11,12]; as well as the aqueous humor [7]. In addition, a high frequency of virulence factors in strains isolated from the conjunctiva in patients undergoing cataract surgery [13], and from the health personnel [14] were reported.…”

Section: Introductionmentioning

confidence: 99%

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Persistence of conjunctival colonization by coagulase-negative staphylococci in patients undergoing cataract surgery

Samudio

Abente

Fariña

et al. 2022

Preprint

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PurposeTo establish the conjunctival contamination source by coagulase-negative staphylococci (CNS) during cataract surgery and discuss the implications of this colonization as a potential risk of acquiring endophthalmitis.Methods Conjunctiva samples for culture from 59 patients undergoing cataract surgery were taken of the fellow eye at baseline (T1) and from the eye to be operated before (T0) and immediately after (T2) irrigation with povine-iodine IOP5%, and at the end of surgery (T3). Genes responsible for virulence (mecA, ica and atlE) and antibiotic profile were determined; strain clonality of persistent colonizing S. epidermidis strains was established by the Multi-locus sequence typing (MLST).Results The frequency of CNS was significantly reduced in T2 (13.6%) from 81.4% in T0 and 86.4% in T1. The frequency of mecA, ica and atlE genes was 35.9%, 41.7% and 67.2%, respectively; and methicillin phenotypic resistance was 35.4%. S. epidermidis was the most frequent species isolated in every time point. MLST revealed in 7 patients 100% coincidence of the 7 alleles of the S. epidermidis isolated previous to povine-iodine 5% disinfection and at the end of the surgery. CNS isolates from T2 or T3 corresponded to the same species, antibiotic and virulence profile as those isolates from T1 or T0.Conclusion Pre-surgical prophylactic scheme significantly reduced conjunctival contamination; in those that persisted, the source of contamination was mostly the patient's microbiota confirmed by the MLST system.

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Section: Discussionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Persistence of conjunctival colonization by coagulase-negative staphylococci in patients undergoing cataract surgery

Samudio

Abente

Fariña

et al. 2022

Preprint

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“…In order to investigate the resistance of specimens to transverse deformation shear modulus of the samples was calculated. Since shear modulus is of particular importance for structural design and analysing the site response, disregarding this parameter may lead to severe damage and loss [ 84 ]. Shear modulus can be calculated through the following equation [ 85 ]:

where

, ε,

and

are shear stress, shear strain, secant modulus, and the Poisson’s ratio, respectively, and

is equal to

[ 86 ].…”

Section: Experimental Program and Methodologymentioning

confidence: 99%

Properties of Lime-Cement Concrete Containing Various Amounts of Waste Tire Powder under Different Ground Moisture Conditions

et al. 2022

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Lime-cement concrete (LCC) is a non-structural concrete in which lime and cement are used as the main binders. However, although LCC has many applications in reducing the settlement of foundations and providing a support layer for shallow foundations, little research has been conducted to evaluate its behaviour in various moisture conditions. Previous researchers have studied the feasibility of using waste tires in conventional concrete to alleviate their negative environmental impacts. However, in field projects, rubber has not been widely used because its application leads to the strength reduction of concrete. In the case of LCC, attaining high strengths is not required and thus application of waste tire particles sounds reasonable. This research evaluated the impact of various rubber powder contents on the fresh, geotechnical and durability properties of LCC at different saturation degrees induced by the capillary action and groundwater level increment, which has not been studied before. The results of more than 320 tests showed that the application of tire powder increases workability and decreases the water absorption of LCC. Moreover, all 60-day cured specimens exposed to 100% saturation degree experienced a strength reduction of less than 10% by using rubber powder contents varying from 0 to 20%. Moreover, increasing the saturation degree from 0 to 100% decreased the average compressive strength by 13.5 and 22% for 60-day cured samples of two different mix designs. The results of this research confirm that LCC containing up to 10% rubber powder could be promisingly used underneath or close to the groundwater table without its strength and geotechnical properties being jeopardized due to rubber employment and/or exposure to ground moisture.

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“…or alternatively fit to values of Vs that may be estimated by correlations (e.g., Carlton and Pestana 2016). The shear modulus exponent nG has a default value of 0.75, but may be adjusted as warranted.…”

Section: Primary Input Parametersmentioning

confidence: 99%

A constitutive model for clays and plastic silts in plane-strain earthquake engineering applications

Boulanger

Ziotopoulou

2019

Soil Dynamics and Earthquake Engineering

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A plasticity model for representing clays and plastic silts, as opposed to purely nonplastic silts or sand, in geotechnical earthquake engineering applications is presented. The PM4Silt model builds on the framework of the stress-ratio controlled, critical state based, bounding surface plasticity PM4Sand model, and is coded as a user defined material for use with the program FLAC.The model was developed to provide reasonable approximations of monotonic undrained shear strength, cyclic undrained shear strength, and shear modulus reduction and hysteretic damping responses. The model does not include a cap, and therefore is not suited for simulating consolidation or reconsolidation settlements (i.e., volumetric strains) or strength evolution with consolidation stress or seismic loading history. The primary input parameters are the undrained shear strength ratio (or undrained shear strength), the shear modulus coefficient, and the contraction rate parameter. All secondary input parameters are assigned default values based on a default calibration, but may be adjusted when calibrating against advanced laboratory test data or performing sensitivity studies. The calibration process is described and illustrated by calibrations for three different normally consolidated, fine-grained soils with plasticity indices ranging from 4 to 20. The model is shown to provide reasonable approximations of behaviors important to many earthquake-engineering applications and to be relatively easy to calibrate.

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A unified model for estimating the in-situ small strain shear modulus of clays, silts, sands, and gravels

Cited by 18 publications

References 31 publications

Persistence of conjunctival colonization by coagulase-negative staphylococci in patients undergoing cataract surgery

Persistence of conjunctival colonization by coagulase-negative staphylococci in patients undergoing cataract surgery

Properties of Lime-Cement Concrete Containing Various Amounts of Waste Tire Powder under Different Ground Moisture Conditions

A constitutive model for clays and plastic silts in plane-strain earthquake engineering applications

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