Exam - Citations And Graph Ideas Flashcards
What is the total number of fatal landslide events recorded between 2004 and 2016?
4862 fatal landslide events
This data is sourced from Froude & Petley, 2018.
What are the types of movement classified by Hungr et al 2014?
Fall
Topple
Slide
Spread
Flow
Slope deformation
What is an example of a complex landslide/ its impacts?
Mt Evans Rock Avalanche (Jan 2013) - flooding, close of SH6 (motorway), loss of fibre optic communications
What are the factors for why a slope could reactivate or initiate with effect in graph?
- Reduced cohesion (take off cohesive factor)
- Reduce friction (lessen gradient of line)
- Reduced effective stress (line to the left closer to 0)
- Increase shear stress (upwards movement arrow)
What are the internal causes if instability from Moore et al 2006?
Materials
Weathering
Pore water pressure
What are the external causes of slope failure Moore et al 2006?
Removal of slope support
Increased loading
Transient effects
What are internal causes of soil strength loss?
Soils subject to strength loss on contact with water or as a result of stress relief (strain softening).
Includes fine grained soils which are subject to strength loss or gain due to weathering, and soils with discontinuities characterised by low shear strength such as bedding planes, faults, joints etc.
What is weathering in the context of soil?
Physical and chemical weathering of soils causing loss of strength (apparent cohesion and friction).
Includes slope ripening and soil weakening processes (e.g. loss of vegetation, shrink and swell, desiccation and surface cracking).
How does pore-water pressure affect soil strength?
Elevated pore-water pressures causing a reduction in effective normal stress, most severe during wet periods or intense rainstorms.
What are the ways of removal of slope support?
Undercutting by water (waves and stream incision), washing out of soil (groundwater flows), and human intervention (e.g. cutting, excavations, tunnelling and mining).
What contributes to increased loading on soil?
Natural accumulations of water, snow, talus, and human intervention (e.g. fill, tips, buildings).
What are transient effects that can impact soil stability?
Earthquakes and tremors, shocks and vibrations.
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X
What causes grain crushing in debris flow slides?
Rapid sliding along the shear zone.
(Okada et al., 2000; Sassa et al., 1996)
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x
What initiates creep in soil mechanics?
Increasing pore pressure leading to slow to rapid displacement.
What is liquefaction?
A process where saturated soil substantially loses strength and stiffness due to applied stress, often leading to flow.
What is the role of groundwater in debris flow slides?
Groundwater path contributes to pore water pressure changes affecting stability.
What is the formula for bulk density?
Mass of soil/total volume (kg/m3 or g/cm3)
What is the formula for bulk unit weight?
Bulk density * gravity
What is the void ratio?
Volume of voids/ volume of solids
What is the degree of saturation formula?
Volume of water/ volume of pores
What is the equation for specific gravity?
Soul density/ water density
What is the formula for porosity?
(Volume of voids/ total volume)x 100
What is the formula for porosity?
Volume of voids/ total volume
How do gonzalez and ferrer 2011 describe drained and undrained?
Drained - voids filled with water and air and fully water
Undrained - voids filled only with water
Physical properties depends on packing and if drained or undrained (if pore fluid can move rapidly under load)
What are the equations for total stress at depth, at depth under water and in multilayer soil?
- Sigma v = y x z (z depth, y unit weight)
- Sigma v = above + yw x zw (unit soil and water)
- “ = y1d1 + y2d2 + y3(z-d1-d2)
What did Morgenstern 1995 write on?
Fundamental concepts of the limit equilibrium method for slope stability analysis e.g., slip mechanism results in slope failure
What would a graph for confining pressure and normal/ shear stress be like? Hudson and Harrison 93
Increasing confining pressures increases peak and reduces/ removes drop to residual
What do graphs look lien for different levels of rock strength?
Very good rock steep increase and vertical big drop to critical medium lesser increase and half drop least curved low increase and no drop
How do you work out pore water pressure?
Water unit weight x height
How do you get zw for fs calculations?
Assume worst case so full tension crack so = z
What papers talk about the effect of temp and size in rock strength?
Jaeger et al 07 for temp (high temp lower peak)
Read and Stacey 09 for size (large less strong)
What did potyondy and cundall 04 show with rock failure?
Failure the result of micro-fractures forming and coalescing
What is importantly to remember with hoek-brown criteria for intact rock?
Empirical - chosen to fit data
What is hoek-brown lacking in and what can aid it?
When minor principle stress becomes negative (tension) so griffths used
What factors from Benedetta lecture can I add into essay?
Preconditions and preparatory factors (former being linked to susceptibility)
What paper should I mention for talking about the type of slope failures?
Hungr et al 2014
What could I put when talking about materials leading to slope failure?
Drained or undrained with their strength diagram (dilation or densification)
What things should I add to answer which Jon mentioned?
Factor of safety (1 or below - byerless law)
Slope shear strength main resistor (friction and cohesion)
Drained undrained
Rain water generating pore pressure examples - rescuing effective more instability
Rapid pore pressure and liquefaction
Stress pathway diagrams
What did gonzalex and ferrer produce a paper on in 2011?
Drained vs undrained
Who put forward the idea of rock mass strength?
Hoek and brown 1997
Who produced the geomechanics system?
Bieniawski 76 and 89
How has the Hoek-brown failure criterion developed as of 2018?
Accounts for discontinuities
estimates the mechinical behaviour of rock masses
What did carey et al 2019 produce a paper on?
The effect of pwp and Eqs on the movement rate of slow moving slides, it found that stong Eq acceleration resulted in rapid strain increases
What is a source for liquefaction?
Bishop 1973 - Rapid loss of large proportion of the shear resistance due to the generation high pore water pressures
