What is soil plasticity ? How does it allow you to prevent slope failures ?
Inexpensive management of surface water could have prevented the slope failures illustrated in Figure 1. The slides occurred upon a creek escarpment on the east coast of Graham Island, Queen Charlotte Forest District. Since it was harvested in the early 1990’s this escarpment has produced an estimated 50 landslides, from 20 slide zones. Slope stability investigations have revealed that the escarpment is composed of medium plastic till. The till is among the most plastic (clay-like) of the soils a forestry worker can reasonably expect to encounter along coastal British Columbia. Inexpensive management of surface water would have prevented the worst of the slope failures upon the escarpment. Had the rock quarries in Figure 2 been built to be free draining, the slides in Figure 1 should not have occurred.
Soil Characterization Based on Physical and Mechanical Properties of Pliocene-Pleistocene Geology in Bukidnon Philippines
Soil characterization is important since it gives an idea of the state of soil in the field. Moreover, Philippine geology map shows a vast area of Pliocene-Pleistocene classification, where until now no up to limited study presented the soil characteristics of this type of geology. These soil characteristics are essential for engineering purposes like design, land development, slope stability, disaster risk mitigation, stabilization, and other relevant utilization. In addition, it identifies if the soil in the site is problematic like being expansive or collapsible. In this study, the soil from thirty sampling locations in the two barangays of Kibawe, Bukidnon with Pliocene-Pleistocene geology is characterized based on their physical and mechanical properties. The results showed that the soil in this geology is classified as fine-grained soil with other locations as gap-graded. The plasticity index (PI) varies from 14.11-71.28%, which indicates medium to very high plasticity. The liquidity index (LI) of the soil varies from 0.12 to 0.96 which means that the soils at their in-situ water content are in the plastic state of intermediate strength and can be deformed like a plastic material. Based on USCS, there are four soil types CH, MH, CL and ML while based on AASHTO soil classification system it belongs to A-7-5 and A-7-6 groups with moderate and high plasticity, respectively. Majority of the soils under this geology are highly expansive and have a high tendency to swell. On the other hand, it has 25 locations that are non-collapsible soil and only 5 are collapsible. In terms of cohesion-PI relationship, it shows that the cohesion value increases with the increasing value of PI. However, the friction angle for CL and ML decreases with increasing PI; while the friction angle for CH and MH increases with increasing PI. While some laboratory tests are expensive, these results may help estimate the soil properties and shear strength from other locations with the same geology.
Influence of inducers and inhibitors on the metabolism in vitro and neurochemical effects in vivo of MDMA.
(S)-(+)- and (R)-(-)-3,4-methylenedioxymethamphetamine (MDMA) were metabolized in vitro by rat liver microsomes via N-demethylation to 3,4-methylenedioxyamphetamine (MDA). Whereas no difference was found in the biotransformation of the two enantiomers in the male rat or in the phenobarbital (PB) treated animals of either sex, more than twice as much MDA was formed from (S)-(+)- than from (R)-(-)-MDMA in the untreated female rat. Although 3-methylcholanthrene (3MC) pretreated rat liver microsomes were less active than those from the untreated rats of the same sex, they formed more MDA from (+)- than from (-)-MDMA. The enantioselective metabolism thus appears to be associated with the relative abundance of individual cytochrome P-450 isozymes. (S)-(+)- and (R)-(-)-MDMA.HCl (20 mg/kg) were about equipotent in depleting serotonin (5-HT) levels in the frontal cortex at 3 hrs and 1 wk following oral administration to female rats. Pretreatment of rats with SKF-525A attenuated and that with PB enhanced the 5-HT depleting potential of either isomer at 3 hrs. The 5-HT depleting potency of (+)-MDMA was significantly greater than that of its (-)-antipode at 3 hr in PB pretreated, but not in SKF-525A pretreated animals. The results suggest that the neurochemical effects of MDMA are caused by the formation of an active metabolite in vivo, and since both enantiomers were N-demethylated in vitro to approximately the same extent by PB pretreated rat liver microsomes, the active metabolite may be other than MDA.