Texas Business reports: Before the Tarrant Regional Water District builds and buries a 150-mile pipeline that will stretch from Lake Benbrook to Lake Palestine in East Texas, it must ensure that the soil that surrounding the mammoth line will remain stable for decades to come.
To that end, the district has awarded a grant of nearly $600,000 to Ali Abolmaali, UT Arlington professor and interim chair of the department of civil engineering, to simulate the behavior and response of pipe-soil interaction that will surround its massive Integrated Pipeline Project.
The pipeline is a $2.3 billion project developed by the Tarrant Regional Water District and Dallas Water Utilities. The pipeline is expected to provide water for an additional 1.5 million people in North Texas. Construction could begin as early as 2014, with the pipeline operating by 2021.
“It’s important that forces and deflections of the soil-pipe interaction system are accurately estimated for varying soil and pipe dimensions to be used as design tools,” Abolmaali said. “We are developing three dimensional non-linear finite element models of pipe and surrounding soil by taking into account algorithms for staged construction, this is a unique model.”
Such massive construction projects typically use crushed rock as a backfill. But crushed rock is very expensive, particularly for a pipeline so long and one that will be 108 inches in diameter for much of its length. That’s why the district has turned to native soil as a backfill material.
“We have to quantify the risk in building the pipeline,” said David Marshall, engineering services director for the Tarrant Regional Water District. “The pipe acts more like a shell for the water. We can’t have a crack in the shell.”
Abolmaali will develop computer simulation programs that the water district can use to gauge the response of the pipe and the loads that the pipe must be able to handle. He also will conducting field tests and perform comparisons between those field tests and computer simulations.
“Then we’ll use the simulation to develop design aids for teams,” Abolmaali said. “We will develop design equations that will then be introduced into national specifications.”
Marshall said Abomaali’s work is critical, as design standards for such pipelines have not been updated since the 1920s.
“They never considered back then that we’d be using a 108-inch pipe today,” Marshall said.
Infrastructure needs today are substantially more important than society ever envisioned, UT Arlington Engineering Dean J.-P. Bardet said.
“This is a water highway that will help this North Texas area with basic needs now and in the future,” Bardet said. “Dr. Abolmaali’s work ensures the district makes the right decisions.”