Electrical Characterization of Soil for In-Situ Measurement of Liquefaction Potential

A new method for characterizing the fundamental sand properties with electrical parameters is described. Correlations are established between the electrical parameters and relative density, Dr, cyclic stress ratio, τ/ σ\u270, and the parameter K2max. An electrical probe, used to measure the electrical parameters in situ, is described. Field measurements, taken with the probe at one of the 1906 San Francisco earthquake sites, indicate that this is a viable alternative for the in situ evaluation of liquefaction potential

A Comparative study of Ease of Insertion, Hemodynamic Changes and Postoperative Adverse Events of Proseal Laryngeal Mask Airway Versus I Gel

BACKGROUND & OBJECTIVES : The major responsibility of the anaesthesiologist is to provide adequate ventilation to patient. The most vital element in providing respiration is maintenance of patent airway. The tracheal intubation is the gold standard method for maintaining a patent airway during anaesthesia. The laryngeal mask airway has gained recognition as an acceptable device for securing the airway of patients during anaesthesia and emergency airway management within the hospital environment. The main aim of this study is to compare the two supraglottic airway devices, IGEL with Proseal LMA in clinical performance in elective short surgeries with spontaneous ventilation. METHOD : The study was conducted to evaluate the two airway device Proseal LMA and I – GEL in view of ease of insertion, number of attempts, hemodynamic changes and postoperative adverse events. The study was conducted to 60 ASA I & II patients of both sexes aged 18 – 50 years going for elective surgical procedures with spontaneous ventilationAfter taking permission from ethics committee and getting written informed consent from patients, the patients will be allotted randomly into 2 groups of 30 patients. One group will receive Proseal LMA and another group will receive I Gel. Group-1: Patients received anaesthesia with Proseal LMA Group-2: Patients received anaesthesia with I –Gel. RESULTS : The ease of insertion of I-GEL was easy for 90% of cases (27) and 10% (3) of cases had difficult. The Proseal shows 83.3% cases (25) had easy in insertion and 16.7% of cases (5) had difficult in insertion. This is statistically significant in p value of ˂ 0.05 I-GEL shows 93.3% cases (28) had successful in first attempt and 6.7% of cases (2) had successful in second attempt. The Proseal had 83.3% of cases (25) successful in first attempt and 16.7% of cases (5) had successful in second attempt. This is statistically not significant has p value of ˃ 0.05 In duration of attempts I- GEL had mean duration of 14.57 with standard deviation of 2.1. The Proseal had mean duration of attempt shows 24.97 with standard deviation of 4.2. So in duration of attempts of I-GEL versus Proseal LMA was statistically significant has p value of ˂ 0.05. Therefore, in view of duration attempts the I-GEL was better than Proseal I-GEL had 6.7% of cases (2) shows blood staining in device after removal and 93.3% of cases (28) shows no blood staining in device after removal. Proseal had 26.7% of cases (8) shows blood staining in device after removal and 73.3% of cases (22) shows no blood staining in device after removal. This shows statistically significant in blood staining of device after removal with p value of ˂ 0.05. So I- GEL was less blood staining in device than Proseal. Above study shows in hemodynamic changes during insertion, intraopeartive period and removal both groups had same changes no difference in data wise. INTERPRETATION AND CONCLUSION : With the above study I –GEL was better in view of ease of insertion, placement was rapid and also less traumatic to airways than Proseal LMA. So I- GEL is a cheap and effective SGD alternative to Proseal LMA

Significance of the VELACS Project to the Solution of Boundary Value Problems in Geotechnical Engineering

The VELACS project was conducted in order to improve existing methods for the analysis of the consequences of soil liquefaction. The project showed that centrifuge studies are repeatable only under carefully controlled conditions. Most procedures were able to predict the onset of liquefaction in contractive soils, but only effective stress based fully coupled nonlinear procedures were able to predict deformations due to liquefaction· None of the currently available procedures could simulate the behavior of dilative soils adequately. Problems were attributed to improper constitutive model implementation and inadequate calibration. An example to evaluate the behavior of a flow slide observed in a dynamic centrifuge test is presented. Numerical simulations of deformations with a finite deformation formulation showed that the main core of the embankment remained stable after shaking. This is in agreement with the observed behavior

leap ucd 2017 centrifuge tests at cambridge

As part of the LEAP project the seismic response of a liquefiable 5° slope was modelled at a number of centrifuges around the world. In this paper the two experiments conducted at Cambridge University are discussed. The model preparation is detailed with particular emphasis on the sand pouring, saturation and slope cutting process. The presence of the third harmonic in the input motion is shown and its significance discussed. The potential for wavelet denoising to filter random electrical noise from the pore pressure traces is illustrated. CPT strength profiles are highlighted and a possible softer layer in one of the tests is discussed. Whilst the specifications called for one dense and one loose test, the likelihood that both Cambridge tests were loosely poured is assessed. The PIV technique is used to obtain the displacements of the slope during the test. Finally, the correspondence between the PIV displacements and physical measurements of the marker movements is compared

Evaluation of dynamic site response and deformation of instrumented site - Kobe

The observed dynamic response of an instrumented site at Port Island during the 1995 Kobe earthquake was utilized to demonstrate the feasibility of computer simulation of earthquake induced site response and liquefaction-induced deformations of a level ground site. Non-destructive in-situ electrical and shear wave velocity methods were used to obtain the initial state parameters and constitutive model constants representative of the site. The analysis used the fully coupled, effective stress-based, nonlinear, finite element program SUMDES with a reduced order bounding surface hypo-plasticity model to simulate the stress-strain behavior of cohesive soils and modified reduced order bounding surface hypo-plasticity model to simulate the stressstrain behavior of non-cohesive soils. The results of the dynamic analysis such as acceleration time histories and liquefaction-induced deformations agreed reasonably well with the acceleration time histories and liquefaction-induced vertical and horizontal deformation behaviors observed during the Kobe earthquake. The results of this study show that computer simulation of earthquake effects at level ground sites is possible using non-destructive in-situ testing and a verified numerical procedure. © 2004 ASCE

Project VELACS-Control Test Results

Results presented in this paper represent the first part of research produced by the Verification of Liquefaction Analysis by Centrifuge Studies (VELACS), a cooperative research effort involving eight universities. Ultimately, the objective of the project is to perform a series of dynamic centrifuge model tests on a variety of different soil models to study the mechanisms of liquefaction‐induced failure and to use the results of these tests to verify various numerical procedures used in the analysis of liquefaction problems. However, prior to completing this final part of the project, a series of model tests was run by each of the eight universities to evaluate the dependence of centrifuge test results on the testing apparatus and test team; these results are presented here. Each university performed one model test using a standard model box; soil‐ and test‐preparation technique; soil configuration; and input earthquake motion. Model accelerations, pore‐water pressures, and surface settlements were measured during the eight tests and are compared in this paper. The test results help to define a general mechanism of liquefaction and show that similar results can be obtained when testing standard models at different centrifuge facilities. Although some scatter was observed, the results are sufficiently close to endorse their use in analysis validation exercises