Analysis of the hydraulic conditions of the downhole spillway to possibility of the cavitation

Studying the work of the deep spillway with segment gate, the presence threshold and asymmetric diffuser outlet part with the determination of possibility appearance of cavitation. As a working case is regarded a pass a high water. Identified the causes of occurrence of cavitation in the offtake spillway tract with the definition of high-speed mode, and the study of piezometric pressure in the calculated alignments, based on data obtained by the model scale 1:50 M spillway. As a result of analysis of the data revealed that under the given working conditions cavitation will occur in the presence of any potential exciter in the pressureless part of the spillway. To ensure safe operation of the spillway is necessary to change the construction of the outlet or change the characteristics of the water flow (for example, use aerators).

Geotechnical characteristics of large slow, very slow, and extremely slow landslides

Based on a study of 45 large slow-moving landslides, it is apparent that for a landslide to travel slowly after failure, the sliding is most likely to be active or reactivated, on a basal rupture surface at or close to residual strength. The likelihood of slow movement after failure is also increased when the inclination of the basal rupture surface is less than the residual friction angle. The slow-moving landslides are all of low rock-mass strength with varying degrees of disaggregation, or they possess soil strength. The influence of lateral margins on landslide restraint is generally small, with landslide movement typically controlled by fluctuations in piezometric pressure. The most commonly observed slow large landslides are mudslides and translational debris–rock slides, followed by particular forms of translational rock slides and internally sheared compound slides. Some mudslides display evidence of short periods of up to moderate velocities.

Reclamation of a saline/sodic soil by aquifer pumping, application of tillage and gypsum and reuse of saline groundwater

In the Goulburn Valley, at a site near Tongala, Vic., shallow perched watertables receded from 18 to 135 cm below the surface and the piezometric pressure was reduced from 16 to 180 cm below the surface in a saline/sodic soil 3 months from the start of pumping. Consequently soil salinity was reduced from ECe 12.3 to 7.3 dS/m in the top 30 cm under 1 15 mm ofrainfall. Further reduction in salinity to ECe 3 dS/m was achieved after 19 months. The presence of electrolytes in irrigation water preserved soil permeability during the irrigation season, while gypsum was beneficial during the winter rainfall season. Perennial pasture was established 11 months after pumping commenced. Weeds that originally dominated the site disappeared, while clover produced 70% of total dry matter.