Engineering: April 2009 Archives

In The Effect of Winter Rains on the Stability of Slopes, geology expert Joshua Feffer, R.G., C.E.G. writes a primer on the general types and causes of slope failures and the role that geologist’s provide as investigative consultants.

Shallow Failures

Shallow or surficial failures are the most common type and are commonly called mudflow or erosion failures. Shallow failures occur when the upper few feet of fill or “colluvial” soil on a slope becomes saturated; that is, the internal pore spaces within the soil are filled with water. This weakens the internal strength of the soil and may cause the soil to behave more like a liquid than a solid causing the soil to “flow”. Most commonly, these types of failures occur on steep slopes, slopes that have sparse vegetation, or in areas that have a concentrated flow of water.

Downhill homeowners tend to bear the brunt of these failures when the soil and debris flow onto their properties and often into their homes resulting in substantial property loss and potential injury. These failures can be caused by triggering events such as broken pipes, poor drainage from upper properties, and from construction defects such as slopes that were built too steeply or inoperative or poorly maintained drain lines.

In The Effect of Winter Rains on the Stability of Slopes, geology expert Joshua Feffer, R.G., C.E.G. writes a primer on the general types and causes of slope failures and the role that geologist’s provide as investigative consultants.

Types Of Slopes

Slopes vary in shape (mainly steepness), origin of the underlying soil (fill, cut, natural), and type of geology or soil (clay, sand, bedrock). As a general statement, the steeper and higher the slope and the weaker the soil or bedrock, the more prone the slope is to failure.

Slope Gradient

Slopes vary in their steepness. Most current fill and cut slopes (manufactured slopes) are graded to have a 2:1 (horizontal to vertical) gradient; that means for every one foot up, the slope extends 2 feet out. Steeper slopes were either constructed before about 1985 or are natural slopes that have not been graded. A natural slope can be near vertical. Many older graded slopes were built to a gradient of 1.5:1.

Vasilios Manousiouthakis, a professor of chemical and biomolecular engineering at the UCLA Henry Samueli School of Engineering and Applied Science, has been awarded $2.1 million in grant funding to build a state-of-the-art hydrogen fueling station on the UCLA campus.  A $1.7 million grant from the California Air Resources Board (CARB) and a $400,000 grant from the state's Mobile Source Air Pollution Reduction Review Committee (MSRC) will go toward the construction of one of the largest hydrogen fueling stations in California, with a capacity to produce 140 kilograms of hydrogen a day for use in hydrogen-powered vehicles...

Major energy providers and automotive manufacturers view hydrogen-powered fuel-cell vehicles as the most sustainable mobility solution in the long term. Manousiouthakis, a systems engineering expert who focuses on the development of novel hydrogen production methods, believes that hydrogen production based on the reforming of natural gas - a process that involves the endothermic transformation of natural gas and water into hydrogen and carbon dioxide - is the most economical route for hydrogen production today.

Excerpted from ImperialValleyNews.com.