Penetration and uplift resistances of two interfering pipelines buried in clays

2021 ◽  
pp. 2150020
Author(s):  
Sorawit Seehavong ◽  
Suraparb Keawsawasvong
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Limit Analysis ◽  
Failure Mechanisms ◽  
Ground Surface ◽  
Linear Increase ◽  
Unit Weight ◽  
Cohesive Soils ◽  
Input Parameters ◽  
Bearing Loads

The primary aim of this paper is to determine penetration and uplift resistances of two interfering pipelines buried in clay with a linear increase in strength. The advanced finite element limit analysis of upper and lower bound theorems is used to perform new limit analysis solutions for both penetration and uplift resistances of two interfering pipelines. The strength profiles of cohesive soils are the cases of normally consolidated clays in deep water by setting the shear strength at the ground surface to be zero and linearly increased with the depth. The twin pipelines have the same geometries and are simultaneously failed at the same magnitude of the failure uplift or bearing loads. There are three considered input parameters including the spacing between the pipes, the embedded depth of the pipes, and the unit weight of soils. All input parameters have significant influences on the penetration and uplift resistances of two interfering pipelines. Failure mechanisms of the problems are also investigated, and stability charts of the penetration and uplift resistances of two interfering pipelines are produced for practical uses in offshore geotechnical engineering.

Limit analysis and finite element evaluation of lateral pipe–soil interaction resistance

2016 ◽  
Vol 53 (1) ◽  
pp. 14-21 ◽  
Author(s):  
W.O. McCarron
Keyword(s):  
Finite Element ◽  
Monte Carlo ◽  
Shear Strength ◽  
Monte Carlo Simulations ◽  
Limit Analysis ◽  
Soil Conditions ◽  
Cohesive Soils ◽  
Perfectly Plastic ◽  
Soil Shear Strength ◽  
Upper Bound Technique

The lateral breakout soil resistance of pipelines supported on undrained cohesive soils determined from limit analysis and finite element methods are compared for a linearly increasing soil strength profile. The limit analysis solution is based on an upper-bound technique. The finite element solutions are developed from coupled Eulerian–Lagrangian simulations. The capacities determined by the two methodologies are in close agreement for the perfectly plastic soil conditions. The relative ease with which the limit analysis solutions are obtained allows rapid investigation of the implications of uncertainty of the soil shear strength profile and pipe embedment via Monte Carlo simulations. Monte Carlo simulations illustrate the implications of correlated random variables describing the shear strength profile and pipe embedment.

scholarly journals Finite Element Limit Analysis of Active Earth Pressure in Nonhomogeneous soils

2016 ◽  
Vol 64 (4) ◽  
pp. 1131-1138
Author(s):  
Peyman Hamidi ◽  
Tohid Akhlaghi ◽  
Masoud Hajialilou Bonab
Keyword(s):  
Finite Element ◽  
Limit Analysis ◽  
Earth Pressure ◽  
Retaining Walls ◽  
Unit Weight ◽  
Analysis Method ◽  
True Solution ◽  
Soil Layers ◽  
Stability Of Slopes ◽  
Limit Analysis Method

Limit analysis is a useful method to calc1ulate bearing capacity of footings, earth pressure of retaining walls, stability of slopes and excavations. In recent years, many efforts have been focused on stability problems of geotechnical structures with the limit analysis method. The limit analysis method includes the upper and lower bound theorems. By using the two theorems, the range, in which the true solution falls, can be found. In this paper upper bound finite element limit analysis is used for calculate active earth force on retaining walls in non-homogeneous soils. Elements with linear strain rates cause to eliminate the necessity of velocity discontinuities between the elements. Nonlinear programming based on second order cone programming (SOCP) ,which has good conformity with Mohr-Coulomb criterion used in this paper. The sensitivity of active earth force against backfill surcharge (q), soil layers cohesion (Ci), soil layers unit weight (γi) and friction angle between soil and wall (δi) is surveyed.

Stability of dual square tunnels in cohesive-frictional soil subjected to surcharge loading

2014 ◽  
Vol 51 (8) ◽  
pp. 829-843 ◽  
Author(s):  
Kentaro Yamamoto ◽  
Andrei V. Lyamin ◽  
Daniel W. Wilson ◽  
Scott W. Sloan ◽  
Andrew J. Abbo
Keyword(s):  
Finite Element ◽  
Upper Bound ◽  
Limit Analysis ◽  
Ground Surface ◽  
Interface Condition ◽  
Design Stage ◽  
Tunnel Stability ◽  
Surcharge Loading ◽  
The Stability ◽  
Frictional Soils

The stability of dual square tunnels in cohesive-frictional soils subjected to surcharge loading has been investigated theoretically and numerically assuming plane strain conditions. From the viewpoint of the efficient utilization of underground space for human activities, noncircular openings and tunnels should be preferred in the design stage. Despite the importance of this issue, previous research on the subject is very limited. At present, no generally accepted design or analysis method is available to evaluate the stability of multiple tunnels–openings in cohesive-frictional soils. In the design stage, it is important to consider the interaction effects of dual tunnels. Unlike the case of a single tunnel, the centre-to-centre distance appears as a new parameter that must be considered and plays a key role in tunnel stability. In this study, continuous loading is applied to the ground surface and a smooth interface condition is modelled. For a series of tunnel size-to-depth ratios and material properties, rigorous lower- and upper-bound solutions for the ultimate surcharge loading are obtained by applying finite element limit analysis techniques. For practical suitability, the results are presented in the form of dimensionless stability charts and a table with the actual tunnel stability numbers closely bracketed from above and below. As an additional verification of the solutions, upper-bound rigid-block mechanisms have been developed, and the predicted collapse loads from these mechanisms are compared with those from finite element limit analysis. Finally, a discussion is presented regarding the location of the critical tunnel spacing between dual square tunnels where interaction no longer occurs.

scholarly journals Generalized framework to predict undrained uplift capacity of buried offshore pipelines

2016 ◽  
Vol 53 (11) ◽  
pp. 1841-1852 ◽  
Author(s):  
Shubhrajit Maitra ◽  
Santiram Chatterjee ◽  
Deepankar Choudhury
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Small Strain ◽  
Unit Weight ◽  
Soil Parameters ◽  
Burial Depth ◽  
Uplift Capacity ◽  
Finite Element Analyses ◽  
Simple Method ◽  
Offshore Pipelines

Estimation of undrained uplift capacity is essential for the determination of optimal burial depth of buried offshore pipelines. However, a generalized prediction model that incorporates various factors influencing this capacity is scarce in the literature. In this paper, results from a series of small-strain finite element analyses are presented that explore the effects of pipe embedment, pipe–soil interface roughness, interface tensile capacity, soil shear strength, and unit weight on pipe uplift response. From the study, a simple method to predict the undrained upheaval resistance of buried pipelines for any practical range of pipeline and soil parameters is proposed. Factors associated with transition in failure mechanism with embedment are also examined. The numerical model is validated by comparing the results with available analytical and experimental data. Large-deformation finite element analyses have also been performed independently for a few cases to justify the applicability of small-strain methods in modelling pipe upheaval. Accuracy of the model for generalized shear strength profile is then examined by considering practical values of parameters over broad ranges. The proposed methodology gives results with maximum error less than 8% for all ranges of parameters and hence can be adopted in design practices.

Undrained Uniaxial Capacities of Suction Bucket Foundations in Rows

2018 ◽  
Author(s):  
Zhong Xiao ◽  
Yumin Lu ◽  
Ying Liu
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Soft Soil ◽  
Failure Mechanisms ◽  
Soft Clay ◽  
Finite Element Models ◽  
Simple Construction ◽  
Bucket Foundation ◽  
Spacing Ratio ◽  
Soil Shear Strength

Suction bucket foundations in rows, sunk by self-weight and passive suction, can be used as footings of breakwater, trestle bridge, offshore cofferdam and other structures, and they have a fine application prospect on soft soil for their advantages of good bearing capacities, simple construction, low investment, being reusable and so forth. A large number of finite-element models for suction bucket foundations in undrained soft clay were established to investigate uniaxial capacities of suction bucket foundations, and the effects of foundations spacing ratio, embedment ratio and soil shear strength were studied. The results show that foundations spacing ratio has certain effect on the uniaxial capacities of a suction bucket foundation but is less influential than other factors; embedment ratio and soil shear strengths have more influence on the uniaxial bearing capacities and failure mechanisms of bucket foundation. Based on these results, simplified formulae are proposed to predict uniaxial capacities of suction bucket foundations in rows for designers to use directly.

scholarly journals Seismic Vulnerability Assessment of a Historical Church: Limit Analysis and Nonlinear Finite Element Analysis

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
G. Castellazzi ◽  
C. Gentilini ◽  
L. Nobile
Keyword(s):  
Finite Element ◽  
Limit Analysis ◽  
Seismic Vulnerability ◽  
Failure Mechanisms ◽  
Fe Analysis ◽  
Nonlinear Finite Element ◽  
Element Analysis ◽  
Seismic Vulnerability Assessment ◽  
The Church ◽  
Selection Of

The seismic vulnerability of a historical Basilica church located in Italy is studied by means of limit analysis and nonlinear finite element (FE) analysis. Attention is posed to the failure mechanisms involving the façade of the church and its interaction with the lateral walls. In particular, the limit analysis and the nonlinear FE analysis provide an estimate of the load collapse multiplier of the failure mechanisms. Results obtained from both approaches are in agreement and can support the selection of possible retrofitting measures to decrease the vulnerability of the church under seismic loads.

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