Analyzing Effects of Soil Parameters on Buried Pipe Behavior and Deciding Governing Parameter Using Statistical Approach

2015 ◽  
Author(s):  
Gaurav P. Bhende ◽  
Pallavi B. Kulkarni ◽  
Priyanka M. Kale
Keyword(s):  
Stress Analysis ◽  
Friction Angle ◽  
Soil Survey ◽  
Soil Parameters ◽  
Buried Pipe ◽  
Governing Parameter ◽  
Active Length ◽  
Soil Parameter ◽  
Future Design ◽  
Analysis Methods

One of the most common and practical difficulties a pipeline engineer faces at the initial stage of the project is the lack of Soil survey data. Hence, various soil parameters like soil type, density, friction angle, cohesive pressure, depth of cover, pipe coating etc. are needed to be assumed. The critical designs like anchor block requirement, pipe route changes, support loads which involve a huge cost are required to be ‘Issued for Construction’ based on assumed data. This paper briefly illustrates and compares the results obtained from the two most common buried pipe stress analysis methods viz. ‘American Lifeline Alliance - Appendix B’ (1) and ‘Stress Analysis Methods for Underground Pipelines’ (2) and shows their effects graphically on the various Stress Analysis results like pipe movement, end force, active length (virtual anchor length) and bending stress generated in the buried pipeline. Further, this paper comes up with an unique application of ANOVA, a Statistical method, to find out the most significant soil parameter affecting the said results. The paper explains this method with a solved example. These results are useful for a pipeline engineer to determine the governing soil parameter in the design and thus provide a useful tool to make optimum assumptions in absence of soil data so as to minimize the changes in future design and helps saving the cost of the project due to rework.

Comparative study of stress analysis of gears with different helix angle using the ISO 6336 standard and tooth contact analysis methods

2016 ◽  
Vol 230 (7-8) ◽  
pp. 1350-1358 ◽  
Author(s):  
Layue Zhao ◽  
Robert C Frazer ◽  
Brian Shaw
Keyword(s):  
Stress Analysis ◽  
Contact Stress ◽  
Helix Angle ◽  
Contact Analysis ◽  
Bending Stress ◽  
Contact Ratio ◽  
Tooth Contact Analysis ◽  
Tooth Contact ◽  
Iso Standard ◽  
Analysis Methods

With increasing demand for high speed and high power density gear applications, the need to optimise gears for minimum stress, noise and vibration becomes increasingly important. ISO 6336 contact and bending stress analysis are used to determine the surface load capacity and tooth bending strength but dates back to 1956 and although it is constantly being updated, a review of its performance is sensible. Methods to optimise gear performance include the selection of helix angle and tooth depth to optimise overlap ratio and transverse contact ratio and thus the performance of ISO 6336 and tooth contact analysis methods requires confirmation. This paper reviews the contact and bending stress predicted with four involute gear geometries and proposes recommendations for stress calculations, including a modification to contact ratio factor Zɛ which is used to predict contact stress and revisions to form factor YF and helix angle factor Yβ which are cited to evaluate bending stress. The results suggest that there are some significant deviations in predicted bending and contact stress values between proposal methods and original ISO standard. However, before the ISO standard is changed, the paper recommends that allowable stress numbers published in ISO 6336-5 are reviewed because the mechanisms that initiate bending and contact fatigue have also changed and these require updating.

scholarly journals Inland Excess Water Projection Based on Meteorological and Pedological Monitoring Data on a Study Area Located in the Southern Part of the Great Hungarian Plain

2013 ◽  
Vol 6 (3-4) ◽  
pp. 31-37 ◽  
Author(s):  
Károly Barta
Keyword(s):  
Field Capacity ◽  
Flood Plain ◽  
Soil Survey ◽  
Soil Parameters ◽  
Soil Factors ◽  
Southeastern Part ◽  
Genetic Types ◽  
Excess Water ◽  
Complex Measurement ◽  
Different Depths

Abstract The research investigated the process of excess water formation. Complex measurement stations were developed in order to determine the most important hydro-meteorological and soil factors contributing to the formation of excess water. The stations measure the amount of precipitation, evapotranspiration, evaporation from water surface, soil moisture in 3 different depths; soil temperature in 5 different depths; furthermore, soil water level. The study area is located in the southeastern part of Hungary, near Szeged, in the flood plain of Tisza and Maros with extremely clayey soils. The former soil data were completed by new soil survey to determine several soil parameters (e.g. bulk density, porosity, field capacity, saturated hydraulic conductivity). Infiltration was calculated from the measured parameters and water budget elements of bigger rainfall event were analyzed between March 2010 and August 2011. Genetic types of excess water can be separated based on the data.

Modelling the applied vertical stress and settlement relationship of shallow foundations in saturated and unsaturated sands

2011 ◽  
Vol 48 (3) ◽  
pp. 425-438 ◽  
Author(s):  
Won Taek Oh ◽  
Sai K. Vanapalli
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Characteristic Curve ◽  
Friction Angle ◽  
Vertical Stress ◽  
Shallow Foundations ◽  
Surface Settlement ◽  
Soil Parameters ◽  
Finite Element Analyses ◽  
Unsaturated Sands

The bearing capacity and settlement of foundations are determined experimentally or modelled numerically based on conventional soil mechanics for saturated soils. In both methods, bearing capacity and settlement are estimated based on the applied vertical stress versus surface settlement relationship. These methods are also conventionally used for soils that are in an unsaturated condition, ignoring the contribution of matric suction. In this study, a methodology is proposed to estimate the bearing capacity and settlement of shallow foundations in unsaturated sands by predicting the applied vertical stress versus surface settlement relationship. The proposed method requires soil parameters obtained under only saturated conditions (i.e., effective cohesion, effective internal friction angle, and modulus of subgrade reaction from model footing test) along with the soil-water characteristic curve (SWCC). In addition, finite element analyses are undertaken to simulate the applied vertical stress versus surface settlement relationship for unsaturated sands. The proposed method and finite element analyses are performed using an elastic – perfectly plastic model. The predicted bearing capacities and settlements from the proposed method and finite element analyses are compared with published model footing test results. There is good agreement between measured and predicted results.

Statistic Analyses of Correlation Distances of Soil Parameters

2011 ◽  
Vol 480-481 ◽  
pp. 1412-1417
Author(s):  
Xiao Yong Li
Keyword(s):  
Field Theory ◽  
Random Field ◽  
Local Area ◽  
Reduction Factor ◽  
Soil Parameters ◽  
Random Field Theory ◽  
Correlation Distance ◽  
Soil Parameter ◽  
Auto Correlation ◽  
Space Effect

The correlation distance is one of the important parameters for the application of random field theory to reliability analyses. Soil spatial variability is related to soil point variability with the reduction factor of variance in random field theory, and the reduction factor of variance depends on both soil auto-correlation distance and spatial area. The sampling space effect on auto-correlation distance is studied. The vertical and horizontal correlation distances of typical stratum are analyzed in statistics based on a large amount of investigation data and the representative values of correlation distance of local area are obtained. It is concluded that that the correlation distances estimated by different soil parameters are similar, and the horizontal correlation distance is much larger than the vertical one for the same soil parameter. The sampling space should be paid attention to when calculating correlation distance of soil parameter.

Influence of cross correlation between soil parameters on probability of failure of simple cohesive and c-ϕ slopes

2016 ◽  
Vol 53 (5) ◽  
pp. 839-853 ◽  
Author(s):  
Sina Javankhoshdel ◽  
Richard J. Bathurst
Keyword(s):  
Slope Stability ◽  
Soil Properties ◽  
Cross Correlation ◽  
Friction Angle ◽  
Probability Of Failure ◽  
Unit Weight ◽  
Soil Parameters ◽  
Design Charts ◽  
Soil Slopes ◽  
Cross Correlations

This paper focuses on the calculation of probability of failure of simple unreinforced slopes and the influence of the magnitude of cross correlation between soil parameters on numerical outcomes. A general closed-form solution for cohesive slopes with cross correlation between cohesion and unit weight was investigated and results compared with cases without cross correlation. Negative cross correlations between cohesion and friction angle and positive cross correlations between cohesion and unit weight, and friction angle and unit weight were considered in the current study. The factors of safety and probabilities of failure for the slopes with uncorrelated soil properties were obtained using probabilistic slope stability design charts previously reported by the writers. Results for cohesive soil slopes and positive cross correlation between cohesion and unit weight are shown to decrease probability of failure. Probability of failure also decreased for increasing negative cross correlation between cohesion and friction angle, and increasing positive correlation between cohesion and unit weight, and friction angle and unit weight. Probabilistic slope stability design charts presented by the writers in an earlier publication are extended to include cohesive-frictional (c-[Formula: see text]) soil slopes with and without cross correlation between soil input parameters. An important outcome of the work presented here is that cross correlation between random values of soil properties can reduce the probability of failure for simple slope cases. Hence, previous probabilistic design charts by the writers for simple soil slopes with uncorrelated soil properties are conservative (safe) for design. This study also provides one explanation why slope stability analyses using uncorrelated soil properties can predict unreasonably high probabilities of failure when conventional estimates of factor of safety suggest a stable slope.

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