Pipe Soil Interaction

SYNOPSIS

STIFFNESS CHARACTERISTICS OF BURIED AND ON-BOTTOM PIPELINES LOADED AXIALLY

Under the Guidance of

Mr. Adarsh K.R. Arya

Assistant Professor Senior Scale

Submitted by:

Mintu Choudhury

SAP ID: 500024885

M.Tech: Pipeline Engineering

Problem• Some pipelines operate in high temperature and pressure

upto 150 C.

• It leads to expansion in the pipeline which causes a important phenomenon in the pipeline called Upheaval Buckling due to the accumulation of compressive stresses.

Background• Buckling is a effect induced by a compressive force, which

distorts pipeline

• It is the same as buckling phenomenon in the column loaded axially

• There is uneven distribution of restrain provided by soil

• This occurs due to difficult conditions of laying pipeline in the seabed

Soil Resistance

• The movement of buried or on-bottom pipeline is restricted by the soil

• The lateral movement is limited by the soil, which the pipeline tries to push (Fig 1 and 2)

• The axial movement is limited by the soil-pipeline friction (Fig 3)

The selection of appropriate pipeline/soil response conditions is dependent on four factors:

Soil conditions

Pipeline roughness

Rate of pipeline movement

Degree of burial

Procedure• Information to found out for different soil conditions

• Among the information:

Assume pipeline roughness Consolidation Coefficient of Soil Subsea Temperature Drained and Undrained Conditions for Partially Embedded and Buried Pipes Cohesive and Non-Cohesive Nature of Soil Governing Equations

• Interaction of the pipe material and the different soils will be compared by finding out the Fa (soil axial resistance)

• A chart will be plotted for axial resistance vs. different soil conditions to compare the results

Governing Equations

Motivation• The problem of UHB has become common now in

subsea pipelines in high pressure and temperature conditions

• Research has been carried out to reduce the temperature and pressure to avoid UHB

• But very less research has been carried out to solve the problem geotechnically

Objectives• To study the behavior of the pipe in different soil

conditions

• Check out the soil behavior in both on-bottom pipes and partially embedded pipes

• To propose proper burial depth for subsea pipelines for different soil condition

Thank You