ABSTRACT

The mechanism of frost heave, also known as frost jacking, is described as it is manifested in warm pipe lines, cold pipelines, and inert objects. It is shown by both descriptions of the physical phenomena and simulations of the seasonal movement of the frost line that the transport of water in unsaturated soil dries the ground around a warm pipe so that frost heave is not expected to affect most buried pipelines.

INTRODUCTION

Pipeline Simulation in the name of this organization usually refers to simulation of the flow in pipelines. As we developed better flow simulators over the years, we found that accurate flow simulation requires the simulation of many other processes associated with pipelines, such as the heat flow in the ground around the pipe and the expansion of the pipe. Accurate simulators require accurate calculations of fluid properties. Two-phase flow simulators require vapor/liquid equilibrium calculations that may be more complex than the flow calculations.

Applications of flow simulators require additional analysis: mass balances for leak detection; wave propagation analysis for leak location, the detailed functioning of pumps, compressors, and valves for surge calculations.

Frost heave is another addition to the list of physical processes affected by the flow in pipelines and affecting the pipelines that are important in some applications.

Frost heave is known to affect solid objects on or in ground subject to freeze/thaw cycles. When water freezes it expands, by about 12% in volume. If unconstrained this expansion can move the ground and anything in the ground.

Repeated cycles of freezing and thawing can significantly displace building foundations and can move rocks up out of the ground.

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