Physical response of landfill geomembranes
Dr. Brachman has conducted and directed award winning research on the physical response of landfill geomembranes (thin polymer liners). The geomembrane (GM) needs to be protected from physical damage from the overlying coarse gravel when buried beneath the waste. There was a paucity of data on what tensions develop in GMs from the coarse gravel required in Ontario landfills and what can be done to limit these tensions. By devising and conducting specialized laboratory testing, Brachman and his students have: quantified the distribution and magnitude of gravel contacts acting on the GM (Brachman and Gudina 2008); demonstrated that tensions are made worse when a wrinkle is present in the GM (Gudina and Brachman 2006); quantified wrinkle deformations and strains from vertical pressure (Brachman and Gudina 2008, Gudina and Brachman 2006); demonstrated that geotextiles selected solely to prevent puncture do not limit tensions to allowable levels; and developed protection layers that effectively limit GM tensions (Dickinson and Brachman 2008). Brachman, his collaborators and students also have: developed solutions to quantify leakage through holes in wrinkles (Rowe et al. 2004); devised techniques to quantify GM wrinkles in the field (Take et al. 2007); and constructed a large-scale field site to monitor wrinkles (Brachman et al. 2007). Dr. Brachman was selected to present a keynote address at the 2006 Canadian Geotechnical Conf. (Canadian Geotechnical Colloquium) based on this work. He is also a co-author of the leading book on landfill barrier systems used by practicing engineers (Rowe et al. 2004).
On-going and future research includes the assessment of allowable tensile strain levels for GMs, investigating the implications of wrinkle-free installations on the long-term performance of GMs, measuring the physical response of aged GMs and quantifying the physical response under enormous vertical pressures.