Dr. Scott Goodrick(GFDI Affiliate) Southern Research Station, U.S. Forest Service
2:30 PM, Tuesday September 30, 2014 Melvin Stern Seminar Room, 18 Keen Bldg. Refreshments will be served at 2:00M
ABSTRACT: Quantitative fire behavior predictions became a reality for the U.S. Forest Service in 1972 with what is now referred to as the Rothermel spread model. This semi-empirical model related the forward spread of a fire to a relatively set of fuel, weather and terrain related variables. While this model is limited in the range of fire phenomena it can describe, it has become the cornerstone of all operational fire behavior prediction tools used by the U.S. Forest Service. I'll be discussing the strengths and weaknesses of this model with a view towards how its use has evolved over the past 40+ years. I will also discuss a number of issues that need to be addressed in attempting to move beyond the Rothermel model for operational fire behavior predictions.
Dr. Kamal TawfiqChair, Dept. of Civil & Environmental Engineering & GFDI FAMU/FSU College of Engineering
2:00 PM, Thursday October 9, 2014 Melvin Stern Seminar Room, 18 Keen Bldg. Refreshments will be served at 1:30M
ABSTRACT: In deep foundation design, drilled shafts (also referred to as bored piles or drilled caissons) are preferred because of their large load capacities and greater economy compared to driven piles. Simply, a drilled shaft is a deep borehole in the ground filled with concrete. The concrete in the drilled shaft can be plain or reinforced with a steel rebar cage. Despite their apparent simplicity, a special construction procedure must be followed when installing drilled shafts through water bearing or caving soils. In such cases, the contractor has two alternatives to deal with the situations. These alternatives include (1) the use of casing or (2) the use of drilling slurry. In certain conditions, the contractor must use both to prevent a collapse of the borehole. If the soil is stiff enough to sustain vertical cuts without stabilization, the dry method of construction can be followed. The use of the slurry method in drilled shaft construction started in the late 1940s. Contractors at that time used slurry made out of in-situ clays and water to provide stability to the advanced borehole until the temporary casing was in place. At that time, the surface friction was not considered in the design of the drilled shaft, therefore, such an effect on the mobilized surface friction was not considered detrimental. In the 1960s engineers started to use slurries made of the commercially processed clay mineral, bentonite and attapulgite. This technique was adapted from the oil recovery industry. The particulate nature and the additives that are often included in the commercially packaged clays have caused federal and state agencies to require that mineral slurries not be disposed in landfills. These requirements motivated the manufacturers of drilling products to develop alternative polymer drilling fluids. These new generations of slurry can be used in drilled shaft construction and can be disposed of on site. Unlike the mineral slurries, polymer slurries are considered to be non-particulate and non-hazardous. Two general types of polymer slurries have evolved over the past several years: non-biodegradable (synthetic) and biodegradable. In this study, the advantage and disadvantage of using both mineral vs. polymer slurries will be presented. Additionally, there is a need to develop more efficient inspection devices to determine the quality of the borehole construction when these slurries are used.