Reliability approach for the side resistance of piles by means of the total stress analysis (α Method)

2007 ◽  
Vol 44 (11) ◽  
pp. 1378-1390 ◽  
Author(s):  
C. Cherubini ◽  
G. Vessia
Keyword(s):  
Stress Analysis ◽  
Undrained Shear Strength ◽  
Clayey Soils ◽  
Total Stress ◽  
First Order ◽  
Side Resistance ◽  
Reliability Method ◽  
Real Size ◽  
Bored Piles ◽  
Adhesion Factor

The evaluation of the pile–soil adhesion plays a fundamental role in the estimation of the side resistance for total stress analysis. Over the years, researchers have presented proposals for adhesion factor formulations even though only a few of them have shown a certain agreement in numerical and (or) methodological terms. Hence, several real-size experimental analyses have improved the understanding of the pile–soil adhesion phenomenon and mechanism. Nevertheless, the undrained shear strength (cu) values depend on the experimental technique employed. Such results force engineers to make a difficult choice among various formulations. A reliability analysis is performed in this paper to take into consideration the variations in formulations and values of the side resistance of bored piles in clayey soils. This study involves piles having different lengths and diameters, which are supposed to be bored in Matera clays. Such soil is characterized by means of laboratory investigation campaign, and its mechanical and stochastic main features are reported here. Values of reliability index β are calculated by means of the first-order reliability method.

Suction Piles in Clay: Reliability Assessment of Deepwaters

2006 ◽  
Author(s):  
Jorge Sa´nchez Moreno ◽  
Edison Castro Prates de Lima ◽  
Gilberto Bruno Ellwanger
Keyword(s):  
Mechanical Properties ◽  
Monte Carlo ◽  
Reliability Assessment ◽  
Element Model ◽  
Analytical Models ◽  
Clayey Soils ◽  
First Order ◽  
Deep Waters ◽  
Reliability Method ◽  
First Order Second Moment

This paper presents an illustrative example of the reliability assessment of suction piles foundation in clayey soils for deepwater applications. The results of two reliability approaches, using suction piles as the foundation system for tension leg platforms (TLPs) under deep waters environmental conditions in the Campeche Bay (Mexico), are compared. The first approach uses the first-order second moment (FORM) reliability method with a suction pile analytical model and the second one uses the Monte Carlo reliability method with a suction pile Finite Element model. The uncertainties of the loads, soils mechanical properties and analytical models were included in the reliability analysis. The results from this study point to important topics for future works.

scholarly journals EFFECT OF DRYING-WETTING PROCESS ON FRICTION CAPACITY AND ADHESION FACTOR OF PILE FOUNDATION IN CLAYEY SOIL

2015 ◽  
Vol 77 (11) ◽  
Author(s):  
Daniel Tjandra ◽  
Indarto Indarto ◽  
Ria Asih Aryani Soemitro
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Pile Foundation ◽  
Undrained Shear Strength ◽  
Clayey Soils ◽  
Content Change ◽  
Adhesion Factor ◽  
Undrained Shear ◽  
Water Content Change ◽  
Friction Capacity

Clayey soils had a seasonal water content change, which occurred in the zone known as active zone. This change happen due to the seasonal drying and wetting cycles, which affects the fluctuation of water table. The water content variation causes the change in undrained shear strength and these changes have an impact to the friction capacity and adhesion factor of pile foundation. This paper discusses the undrained shear strength, friction capacity of pile and adhesion factor of piles under drying and wetting cycles. Research was conducted on two different types of clayey soils. Laboratory experiments for varying soil water content were done. Soil samples were placed in a cylinder tube, the concrete pile model was then inserted into the soil. The diameter of the tube was about 15 times of the pile diameter. Loading test was carried out to investigate pile friction capacity. The result of this study showed that there was great effect of seasonal water content change on undrained shear strength, friction capacity and also adhesion factor of pile in the clayey soils.

Reliability analysis of a cohesive slope in a spreadsheet using FOSM, FORM and Monte-Carlo Simulation

2021 ◽  
pp. 391-402
Author(s):  
Saurav Shekhar Kar ◽  
Avijit Burman ◽  
Lal Bahadur Roy
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Shear Strength ◽  
Reliability Index ◽  
Factor Of Safety ◽  
Undrained Shear Strength ◽  
Excel Spreadsheet ◽  
First Order ◽  
Reliability Method ◽  
Undrained Shear

In geotechnical engineering uncertainties arises from loads, soil characteristics and their properties, calculation models etc. To minimize these uncertainties in geotechnical problem, various reliability based and (or probabilistic based) approaches have been developed. This abstract presents a MS-Excel spreadsheet environment based practical framework for estimating the reliability index and failure probability of a cohesive finite slope using First-order second moment method, First-order reliability method and Monte Carlo Simulation. The height and the angle of slope is considered to be 5 m and 45º respectively. The inclination of the slope is 2H:1V and the hard stratum is assumed to be present at 15 m below the soil. The values of saturated unit weight and undrained shear strength are assumed to be 18 kN/m3 and 20 kPa respectively. The stability analysis is carried out using Swedish slice method under undrained condition. The excel spreadsheet developed in the study is mainly divided into two forms i.e. deterministic model worksheet for calculating the factor of safety and uncertainty model for generating the random variables of uncertain parameters. The undrained shear strength is considered as an uncertain parameter. The nominal factor of safety value is found out to be 1.248 and the critical slip circle has coordinate (2.6, 8.8), having radius of 16 m. The reliability index is found out using FOSM, FORM and MCS.

New stability method for embankments on clay foundations

1982 ◽  
Vol 19 (1) ◽  
pp. 44-48 ◽  
Author(s):  
Robert P. Chapuis
Keyword(s):  
Shear Strength ◽  
Stress Analysis ◽  
Undrained Shear Strength ◽  
Direct Application ◽  
Published Data ◽  
Total Stress ◽  
Preconsolidation Pressure ◽  
Stability Method ◽  
Undrained Shear ◽  
Clay Foundations

The proposed method makes use of a conventional total stress analysis, corrected to take into consideration the preconsolidation pressure and the undrained shear strength profiles. Good results are obtained for seven well documented cases of embankment failures, the data of which allow a direct application of the proposed method. Many other failure cases, for which the published data are insufficient to allow such a direct application, are analysed on a statistical basis using a relationship between cuσp′ and Ip. Bjerrum's correction appears as a particular case, only statistically applicable, of the proposed method.

Some Important Issues on First-Order Reliability Analysis With Nonprobabilistic Convex Models

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
C. Jiang ◽  
G. Y. Lu ◽  
X. Han ◽  
R. G. Bi
Keyword(s):  
Reliability Analysis ◽  
Reliability Index ◽  
Probability Model ◽  
Mean Value ◽  
Convex Model ◽  
First Order ◽  
Reliability Method ◽  
Complex Engineering ◽  
Mean Value Method ◽  
Form Type

Compared with the probability model, the convex model approach only requires the bound information on the uncertainty, and can make it possible to conduct the reliability analysis for many complex engineering problems with limited samples. Presently, by introducing the well-established techniques in probability-based reliability analysis, some methods have been successfully developed for convex model reliability. This paper aims to reveal some different phenomena and furthermore some severe paradoxes when extending the widely used first-order reliability method (FORM) into the convex model problems, and whereby provide some useful suggestions and guidelines for convex-model-based reliability analysis. Two FORM-type approximations, namely, the mean-value method and the design-point method, are formulated to efficiently compute the nonprobabilistic reliability index. A comparison is then conducted between these two methods, and some important phenomena different from the traditional FORMs are summarized. The nonprobabilistic reliability index is also extended to treat the system reliability, and some unexpected paradoxes are found through two numerical examples.

Sign in / Sign up

Export Citation Format

Share Document