Shear Stress Slopes

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Factors That  Cause Increase 
in Shear Stress Slopes
(Highway Research Board, 1978)

1. Demolition material support
 
    a. Erosion

• The stream or river
• The ice avalanche
• By action of waves at sea
• The changes in wet and dry (wind, freezing)
 

    b. Natural slope movement  
        (fall, avalanches, decline)
 
    c. Human activity

• Mineral and cutting slopes
• Demolition of retaining wall or plaster
• Rapid reduction of water (lake, sea)

 
2. Excess load
 
    a. By cause - natural causes

• The weight of water that seeped into the soil (rain, snow)
• The accumulated material from previous avalanches 
 

    b. Human activity

• Development of embankment
• The construction of buildings or other heavy loads on top of the slope
• Leakage of water from the sewer - sewer, water or sewer pipes

 
3. Effect of moment (earthquake)
 
4. The loss of the material - which underpins 
     the bottom of the slope stability of slopes

•  By river or sea water
•  The influence of climate
•  By underground erosion due to seepage (piping), dissolution of the material contained in the soil
•  By human activity
•  By loss of shear strength of material at the bottom of the slope

 
5. The increase in lateral pressure

• By water in cracks or gaps
• By freezing water in cracks
• The development of clay

Factors That Reduced Land in Strong Shear Slopes
 
1. Innate factors of nature - 
    the nature of the slope-forming material

• Composition
• Composition
• The composition of secondary or inherit
• Perselang - interlude layer (stractification)

 
2. Changes caused by climate change and  
     activity fisiokimia (physiochemical)

• The process of drying and wetting
• Hydration
• The loss of an intermediary substance which glue the

 
3. Effect of pore water pressure
 
4. Changes in structure or composition

• Disposal or reduction of stress (stress release)
• Degradation structure

Landslide Causes

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1. Geological causes

•   Weak or sensitive materials
•   Weathered materials
•   Sheared, jointed, or fissured materials
•   Adversely oriented discontinuity (bedding, schistosity, fault, unconformity, contact, and so forth)
•   Contrast in permeability and/or stiffness of materials

2. Morphological causes

•   Tectonic or volcanic uplift
•   Glacial rebound
•   Fluvial, wave, or glacial erosion of slope toe or lateral margins
•   Subterranean erosion (solution, piping)
•   Deposition loading slope or its crest
•   Vegetation removal (by fire, drought)
•   Thawing
•   Freeze-and-thaw weathering
•   Shrink-and-swell weathering

3. Human causes

•   Excavation of slope or its toe
•   Loading of slope or its crest
•   Drawdown (of reservoirs)
•   Deforestation
•   Irrigation
•   Mining
•   Artificial vibration
•   Water leakage from utilities

Although there are multiple types of causes of landslides, the three that cause most of the damaging landslides around the world are these:

Landslides and Water

Slope saturation by water is a primary cause of landslides. This effect can occur in the form of intense rainfall, snowmelt, changes in ground-water levels, and water-level changes along coastlines, earth dams, and the banks of lakes, reservoirs, canals, and rivers.

Landsliding and flooding are closely allied because both are related to precipitation, runoff, and the saturation of ground by water. In addition, debris flows and mudflows usually occur in small, steep stream channels and often are mistaken for floods; in fact, these two events often occur simultaneously in the same area.

Landslides can cause flooding by forming landslide dams that block valleys and stream channels, allowing large amounts of water to back up. This causes backwater flooding and, if the dam fails, subsequent downstream flooding. Also, solid landslide debris can "bulk" or add volume and density to otherwise normal streamflow or cause channel blockages and diversions creating flood conditions or localized erosion. Landslides can also cause overtopping of reservoirs and/or reduced capacity of reservoirs to store water.

Landslides and Seismic Activity

Many mountainous areas that are vulnerable to landslides have also experienced at least moderate rates of earthquake occurrence in recorded times. The occurrence of earthquakes in steep landslide-prone areas greatly increases the likelihood that landslides will occur, due to ground shaking alone or shaking-caused dilation of soil materials, which allows rapid infiltration of water. The 1964 Great Alaska Earthquake caused widespread landsliding and other ground failure, which caused most of the monetary loss due to the earthquake. Other areas of the United States, such as California and the Puget Sound region in Washington, have experienced slides, lateral spreading, and other types of ground failure due to moderate to large earthquakes. Widespread rockfalls also are caused by loosening of rocks as a result of ground shaking. Worldwide, landslides caused by earthquakes kill people and damage structures at higher rates than in the United States. 

Landslides and Volcanic Activity

Landslides due to volcanic activity are some of the most devastating types. Volcanic lava may melt snow at a rapid rate, causing a deluge of rock, soil, ash, and water that accelerates rapidly on the steep slopes of volcanoes, devastating anything in its path. These volcanic debris flows (also known as lahars) reach great distances, once they leave the flanks of the volcano, and can damage structures in flat areas surrounding the volcanoes. The 1980 eruption of Mount St. Helens, in Washington triggered a massive landslide on the north flank of the volcano, the largest landslide in recorded times. 

Landslide Mitigation—How to Reduce the Effects of Landslides

Vulnerability to landslide hazards is a function of location, type of human activity, use, and frequency of landslide events. The effects of landslides on people and structures can be lessened by total avoidance of landslide hazard areas or by restricting, prohibiting, or imposing conditions on hazard-zone activity. Local governments can reduce landslide effects through land-use policies and regulations. Individuals can reduce their exposure to hazards by educating themselves on the past hazard history of a site and by making inquiries to planning and engineering departments of local governments. They can also obtain the professional services of an engineering geologist, a geotechnical engineer, or a civil engineer, who can properly evaluate the hazard potential of a site, built or unbuilt.

The hazard from landslides can be reduced by avoiding construction on steep slopes and existing landslides, or by stabilizing the slopes. Stability increases when ground water is prevented from rising in the landslide mass by (1) covering the landslide with an impermeable membrane, (2) directing surface water away from the landslide, (3) draining ground water away from the landslide, and (4) minimizing surface irrigation. Slope stability is also increased when a retaining structure and/or the weight of a soil/rock berm are placed at the toe of the landslide or when mass is removed from the top of the slope

Types of Landslides

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The term "landslide" describes a wide variety of processes that result in the downward and outward movement of slope-forming materials including rock, soil, artificial fill, or a combination of these. The materials may move by falling, toppling, sliding, spreading, or flowing. Figure 1 shows a graphic illustration of a landslide, with the commonly accepted terminology describing its features.

Figure 1. An idealized slump-earth flow 

showing commonly used nomenclature for labeling the parts of a landslide.

The various types of landslides can be differentiated by the kinds of material involved and the mode of movement. A classification system based on these parameters is shown in figure 2. Other classification systems incorporate additional variables, such as the rate of movement and the water, air, or ice content of the landslide material.

Figure 2. Types of landslides. 

Abbreviated version of  Varnes' classification of slope movements (Varnes, 1978).

Although landslides are primarily associated with mountainous regions, they can also occur in areas of generally low relief. In low-relief areas, landslides occur as cut-and-fill failures (roadway and building excavations), river bluff failures, lateral spreading landslides, collapse of mine-waste piles (especially coal), and a wide variety of slope failures associated with quarries and open-pit mines. The most common types of landslides are described as follows and are illustrated in figure 3. 

SLIDES: Although many types of mass movements are included in the general term "landslide," the more restrictive use of the term refers only to mass movements, where there is a distinct zone of weakness that separates the slide material from more stable underlying material. The two major types of slides are rotational slides and translational slides. Rotational slide: This is a slide in which the surface of rupture is curved concavely upward and the slide movement is roughly rotational about an axis that is parallel to the ground surface and transverse across the slide (fig. 3A & 3B). Translational slide: In this type of slide, the landslide mass moves along a roughly planar surface with little rotation or backward tilting (fig. 3C &  3D). A block slide is a translational slide in which the moving mass consists of a single unit or a few closely related units that move downslope as a relatively coherent mass.

 

Figure 3. These schematics illustrate the major types of landslide movement

FALLS: Falls are abrupt movements of masses of geologic materials, such as rocks and boulders, that become detached from steep slopes or cliffs (fig. 3E). Separation occurs along discontinuities such as fractures, joints, and bedding planes, and movement occurs by free-fall, bouncing, and rolling. Falls are strongly influenced by gravity, mechanical weathering, and the presence of interstitial water.

TOPPLES: Toppling failures are distinguished by the forward rotation of a unit or units about some pivotal point, below or low in the unit, under the actions of gravity and forces exerted by adjacent units or by fluids in cracks.

FLOWS: There are five basic categories of flows that differ from one another in fundamental ways.

1. Debris flow: A debris flow is a form of rapid mass movement in which a combination of loose soil, rock, organic matter, air, and water mobilize as a slurry that flows downslope (fig. 3H). Debris flows include <50% fines. Debris flows are commonly caused by intense surface-water flow, due to heavy precipitation or rapid snowmelt, that erodes and mobilizes loose soil or rock on steep slopes. Debris flows also commonly mobilize from other types of landslides that occur on steep slopes, are nearly saturated, and consist of a large proportion of silt- and sand-sized material. Debris-flow source areas are often associated with steep gullies, and debris-flow deposits are usually indicated by the presence of debris fans at the mouths of gullies. Fires that denude slopes of vegetation intensify the susceptibility of slopes to debris flows. 
2. Debris avalanche: This is a variety of very rapid to extremely rapid debris flow (fig. 3i). 
3. Earthflow: Earthflows have a characteristic "hourglass" shape (fig. 3G). The slope material liquefies and runs out, forming a bowl or depression at the head. The flow itself is elongate and usually occurs in fine-grained materials or clay-bearing rocks on moderate slopes and under saturated conditions. However, dry flows of granular material are also possible. 
4. Mudflow: A mudflow is an earthflow consisting of material that is wet enough to flow rapidly and that contains at least 50 percent sand-, silt-, and clay-sized particles. In some instances, for example in many newspaper reports, mudflows and debris flows are commonly referred to as "mudslides." 
5. Creep: Creep is the imperceptibly slow, steady, downward movement of slope-forming soil or rock. Movement is caused by shear stress sufficient to produce permanent deformation, but too small to produce shear failure. There are generally three types of creep: (1) seasonal, where movement is within the depth of soil affected by seasonal changes in soil moisture and soil temperature; (2) continuous, where shear stress continuously exceeds the strength of the material; and (3) progressive, where slopes are reaching the point of failure as other types of mass movements. Creep is indicated by curved tree trunks, bent fences or retaining walls, tilted poles or fences, and small soil ripples or ridges (fig. 3F).

LATERAL SPREADS: Lateral spreads are distinctive because they usually occur on very gentle slopes or flat terrain (fig. 3J). The dominant mode of movement is lateral extension accompanied by shear or tensile fractures. The failure is caused by liquefaction, the process whereby saturated, loose, cohesionless sediments (usually sands and silts) are transformed from a solid into a liquefied state. Failure is usually triggered by rapid ground motion, such as that experienced during an earthquake, but can also be artificially induced. When coherent material, either bedrock or soil, rests on materials that liquefy, the upper units may undergo fracturing and extension and may then subside, translate, rotate, disintegrate, or liquefy and flow. Lateral spreading in fine-grained materials on shallow slopes is usually progressive. The failure starts suddenly in a small area and spreads rapidly. Often the initial failure is a slump, but in some materials movement occurs for no apparent reason. Combination of two or more of the above types is known as a complex landslide.

Vocational Theory, Blue Print The Test Items (National Examinations 2010-2011)

Mining Geology (3 Years)

1. Understanding Basic Geology:

• Explaining the branches of geological sciences
• Identify geological style
• Describe the specific exploration methods
• Explains one particular phase of exploration

2. Understanding Mineral and Rock:

• Determining the scale of violence Mosh 1822
• Identify the type of rock
• Classify rocks based on mineral constituent
• Identifying the structure of certain rocks
• Explaining the process of formation of certain rocks

3. Understanding the Concept Exploration:

• Describe the specific exploration methods
• Explains one particular phase of exploration

4. Applying drilling:

• Explain the function of one part of the machine / tool drill
• Identifying a suitable drill bit is used in certain circumstances
• Classify the drill tool

5. Doing Geological Mapping:

• Determine the tool used for a particular mapping method
• Determining the appropriate method for a particular region
• Identify the geological structure
• Determining the elements of the geological structure
• Specify the type of map
• Calculating the value of the contour interval
• Calculating the distance of two cities

6. Understanding the Concept Exploration:

• Determining image strike / dip corresponding to the data presented

7. Understanding the basics of field geology survey:

• Identify the geological survey equipment
• Identify the elements of earth romance
• Determining the category of river

8. Understanding the mineral mining / exploitation:

• Identify mining equipment
• Describes mining equipment
• Determine mining method

9. Shot hole drilling apply (blast hole drillling):

• Determining the geometry element blasting
• Calculating the volume blasting results

10. Understanding mineral:

• Determine the classification of certain minerals
• Explaining the process of formation of minerals

11. Applying a mineral exploration techniques:

• Identify methods of exploration

12. Understanding fossil microfossil and presentation techniques:

• Identifying fossils categorized as microfossil
• Determining the relative age of rocks

13. Understanding makrofosil:

• Explain the function makrofosil
• Identify where fossil life

14. Applying engineering geology:

• Determining causes of ground movement
• Describe the physical and mechanical properties of soil

15. Understanding the reclamation of former mining areas:

• Explaining the stages of reclamation
• Determining the appropriate use of land after reclamation is

Mathematics-SMK, Blue Print of The Test (National Examinations 2010-2011)

1. Performs real numbers and apply Dalan vocational field:

• Resolving issues related to the profit and loss.
• Resolving issues related to the comparison.
• Determining the number of operating results ranking.
• Simplify form roots.
• Determining the value of the logarithmic form of surgery.

2. Solve problems related to function, equation linear functions and quadratic functions:

• Determining the gradient or line equation.
• Determining the cutoff, the peak point, or the equation graph a quadratic function.

3. Solving the problems associated with the system of linear equations and inequalities:

• Determining the set of linear inequalities in one variable resolution.
• Resolving problems associated with the system of linear equations in two variables.

4. Resolve linear programming problems:

• Determining the mathematical model or the set of inequalities system settlement linear.
• Determining the optimum value of objective function.

5. Resolving the problem matrices and vectors and to apply them in the vocational field:

• Determining the operating results in the matrix.
• Determining the elements of the unknown in the similarity of two matrices.
• Determining the results of operations on vectors.
• Determining the angle between two vectors.

6. Understand the concept of circumference and area of flat wake, surface area and volume of plane geometry and to apply them in the vocational field:

• Resolving the problems associated with large round or flat wake.
• Determine the extent and volume of a plane geometry.

7. Applying the principles of mathematical logic in solving problems related to compound statement and statement berkuantor:

• Determining the truth value of compound statement.
• Determine the negation of the compound statement.
• Determining konvers, inverse, or contraposition of the statement in the form of implications.
• Draw the conclusion from two premises.

8. Applying the concept of comparison of trigonometry in solving problems:

• Determine the length of one side of a right triangle using trigonometric ratio.
• Determine the polar coordinates if known Cartesians coordinates or vice versa.
• Determining the value of the difference of two angles, if known trigonometric ratio sine and tangent.

9. Resolving problems with the concept of opportunity:

• Resolving the problem using the concept of permutations or combinations.
• Determining the chance or frequency of an event hope.

10. Applying the rules of statistical concepts in problem solving:

• Interpret data presented in the form of diagrams.
• Determine ways / steps to determine the mode of data groups.
• Calculate the mean of the data groups.
• Determine the standard deviation of individual data.
• Determining quartiles from grouped data.

11. Using the concept of limit of function and derivative function in solving the problems:

• Determining the value limit of algebraic functions.
• Determining the derivative of algebraic functions in the form f (x) = u / v

12. Using the integral concept in solving the problems:

• Determine the integral of a function algebra.
• Determine the area bounded the two curves.
• Determining the volume of rotating objects.

13. Solving the problems associated with rows and rows:

• Resolving problems associated with rows and rows.