LESSON 5: MASS WASTING PART 2 Flashcards
2 general ways to reduce the risk of mass wasting
- Recognizing and Avoiding the Hazard
- Engineering Controls
T or F: it is more often more advisable to mitigate than avoid hazards
FALSE: if more cost-effective, avoid the hazard, but if mitigation is more cost-effective, then go.
how to: Recognizing and Avoiding the Hazard
- Identify those slopes that are unstable and subsequently
- minimize human activity within the hazard zone thru
- zoning laws designed to restrict development and
- construction ordinances that prohibit oversteepening of slopes
________ involve a number of different controls, and a combination of these controls is usually chosen based on ________ and the _________. In some cases the goal is to _______; in others, it is simply to ________ that is all but impossible to stop.
ENGINEERING SOLUTIONS involve a number of different controls, and a combination of these controls is usually chosen based on THE TYPE OF EXPECTED MOVEMENT and the CHARACTERISTICS OF THE SITE ITSELF. In some cases the goal is to PREVENT MOVEMENT; in others, it is simply to PROVIDE PROTECTION FROM MOVEMENT that is all but impossible to stop.
name the 7 engineering controls
- retaining walls
- rock bolts
- controlling water
- terracing
- covering steep slopes
- reducing slope materials
- protective structures
engineering controls that are common along Philippine highways
retaining walls with perforated pipes
what must be done if the objective is to prevent movement?
slope stability can be maximized by:
- simultaneously increasing frictional forces and
- decreasing the weight acting in the downslope direction
are commonly used whenever a flat or level surface is needed in sloping terrain, such as for roadways, buildings, and parking lots; involves stabilization of oversteepened slope thru cutting. It can also be used to gain control over slides or flows that occur repeatedly
retaining walls (+perforated pipes)
are commonly used to anchor loose rocks to more massive, solid bodies of rock; applicable on areas that have highly fractured rocks are exposed on steep slopes and where weakness planes are inclined in the same direction as the slope
rock bolts (with wire mesh + shot grip)
4 techniques to control or limit the amount of water that can accumulate within the slope material
- common: install a network of perforated pipes and/or gravel beds in order to drain water from within the slope.
- diverting water is especially important in keeping water from flowing into open fractures at the top of slumps and slides.
- It may even be necessary to cover large sections of a slope with impervious plastic sheeting to prevent water from infiltrating into unstable materials. (esp for sanitary landfills esp if subsurface is impermeable, use geoliners that prevent seepage from infiltration)
- limiting the amount of water being used nearby for landscape or agricultural irrigation
involves creating a series of benches on a hillside—retaining walls are often used to support the oversteepened portions of the slope.
terracing
flat surfaces in terracing
benches
terracing is an ancient practice in parts of _____ and
_____ where they provide flat areas for
______ in rugged terrain
ASIA AND SOUTH AMERICA
FOR GROWING FOOD
what is the effect of terracing on slopes?
- decreases the overall steepness of the slope, but also
- breaks the slope up into shorter segments.
= when a rock does break loose, it will travel only a short distance before encountering a bench or step - The rock will most likely come to a stop on the bench as opposed to tumbling down onto the highway.
what should we compound with terracing?
retaining walls, shot grip and wire mesh
