A field study of the behavior of small-scale single rammed aggregate piers, testing methodology and interpretation

AbstractThis paper presents the measured behavior of small-scale single rammed aggregate piers as a function of the piers’ slenderness ratio. For this purpose, loading tests at the site were carried out on two groups of single rammed aggregate piers with a constant diameter of 135 mm and variable lengths of 350–1000 mm, and two groups with a constant length of 1000 mm and various diameters of 105–185 mm. The testing area consisted of relatively uniform saturated soft alluvial clay overlain by a 1-m-thick wet soft-to-stiff silt layer. Results show that when length and diameter change, the pier load and top settlement variations at the design limit, in terms of the slenderness ratio, are not in the same direction while other design limit parameters’ variations are. The variations of design limit parameters in the two modes of change to pier length and diameter including the applied load, top settlement, stiffness modulus and pier modulus, in terms of the slenderness ratio, make a linear function while the variations of load and settlement ratio show an exponential function. Interpretations of the test results are particularly focused on the load-settlement behavior and variations of design limit parameters as a function of pier slenderness ratios

Diagnostic accuracy of a clinical diagnosis of idiopathic pulmonary fibrosis: An international case-cohort study

We conducted an international study of idiopathic pulmonary fibrosis (IPF) diagnosis among a large group of physicians and compared their diagnostic performance to a panel of IPF experts. A total of 1141 respiratory physicians and 34 IPF experts participated. Participants evaluated 60 cases of interstitial lung disease (ILD) without interdisciplinary consultation. Diagnostic agreement was measured using the weighted kappa coefficient (\u3baw). Prognostic discrimination between IPF and other ILDs was used to validate diagnostic accuracy for first-choice diagnoses of IPF and were compared using the Cindex. A total of 404 physicians completed the study. Agreement for IPF diagnosis was higher among expert physicians (\u3baw=0.65, IQR 0.53-0.72, p20 years of experience (C-index=0.72, IQR 0.0-0.73, p=0.229) and non-university hospital physicians with more than 20 years of experience, attending weekly MDT meetings (C-index=0.72, IQR 0.70-0.72, p=0.052), did not differ significantly (p=0.229 and p=0.052 respectively) from the expert panel (C-index=0.74 IQR 0.72-0.75). Experienced respiratory physicians at university-based institutions diagnose IPF with similar prognostic accuracy to IPF experts. Regular MDT meeting attendance improves the prognostic accuracy of experienced non-university practitioners to levels achieved by IPF experts

Performance of helical anchors in sand

Helical anchor consist of some steel shafts with a series of helical steel plates welded on a pitch. During installation, helical anchor was screwed into the ground by using a standard truck or trailer mounted augering equipment. The equipment will apply a rotating moment to the steel shafts to screw the anchors into ground. The torque resistance of the anchor will be monitoring along the installation. When the torque resistance achieved its designed values, it verified that capacity of anchor achieved. Behavior of helical anchor under uplift load in cohesionless soil has been studied using previous researches. Based on a few number of laboratory model results many investigators reported the uplift loading of helical anchor embedded in cohesionless soil, a review of related last works shows that not much research has been done to define the uplift capacity in cohesionless soil, a problem that is often encountered in field. The paper observed that the ultimate uplift capacity is dependent on the relative undrained/drained shear strength of cohesionless soil, the depth ratio of embedment and soil thickness ratio

History of horizontal anchor plates based on experimental works in cohesion less soil

Buried anchors have been used for thousands years to stabilize structures. Anchor plates may be made of steel plates, precast concrete slabs, poured concrete slabs, timber sheets and so forth. This paper presents the history of anchor plates in experimental works in cohesion less soils due to different researches by last researchers from first research until now. The role of this last experimental research has focused on predicting anchor behavior and force in cohesion less soil. Although there are not entirely sufficient substitutes for full-scale field testing, tests at laboratory scale have the advantage of allowing close control of at least some of the parameters encountered in research. These anchors can be installed by excavating the ground to the required depth and then backfilling and compacting with good quality cohesion less soils. The results are involved of laboratory testing that they are typically problem specific and they are difficult to extend to field problems with different material or geometric parameters in field scale. The paper observed that the ultimate uplift capacity is dependent on the relative friction angle, density based on loose or dense conditions and the depth ratio of embedment

Different theories & numerical analysis of anchor plates in sand

This study elucidates the behavior of horizontal anchors in sand based on different theoretical and numerical analyses. This paper presents different theoretical & numerical analysis of anchor plates in loose and dense sand. Numerical methods can be used to estimate the ultimate pullout capacity of anchor plates. This paper discussed different theories and numerical analysis in anchors plates from previous researchers. Analyses, beginning from Meyerhof & Adams (1968) until the most recent analysis such as Sakai & Tanaka (1998) are reviewed. The analysis is pioneered by Vesic (1971), Sarac(1989) and Smit (1989), Krishna(2000), Fargic and Marovic (2003), Merfield and Sloan(2006), Dickin & Lama(2007), Kumar and Bhoi (2008), Kuzer & Kumar(2009) and Niroumand and Kassim(2010). The results are involved different theories and numerical analysis that the results in theoretical and analysis were more than experimental results. According to the results, the ultimate load per bonded length as total length or overburden ratio in the tension anchor plate is increased

Performance of Helical Anchors in Sand

Helical anchor consist of some steel shafts with a series of helical steel plates welded on a pitch. During installation, helical anchor was screwed into the ground by using a standard truck or trailer mounted augering equipment. The equipment will apply a rotating moment to the steel shafts to screw the anchors into ground. The torque resistance of the anchor will be monitoring along the installation. When the torque resistance achieved its designed values, it verified that capacity of anchor achieved. Behavior of helical anchor under uplift load in cohesionless soil has been studied using previous researches. Based on a few number of laboratory model results many investigators reported the uplift loading of helical anchor embedded in cohesionless soil, a review of related last works shows that not much research has been done to define the uplift capacity in cohesionless soil, a problem that is often encountered in field. The paper observed that the ultimate uplift capacity is dependent on the relative undrained/drained shear strength of cohesionless soil, the depth ratio of embedment and soil thickness ratio