Slab Slides Research Articles

Laboratory analysis updates fault slip formula

The rate at which one rock slab slides past another, such as along a fault or fracture, depends on the strengths of the applied forces and the friction between the blocks. Though simple in concept, accurately modeling the interactions—especially the extreme cases of prolonged stress accumulation or the sudden rupture of an earthquake—is difficult. Researchers rely on the rate‐ and state‐dependent friction law (RSF) to estimate the slip velocity in a fracture from the imposed stresses. The empirical RSF is itself broken down into two component parts: the constitutive law, which describes how the rock reacts to external forces and pressures, and the evolution law, which attempts to explain how the friction at the fracture interface changes under varying amounts of stress. Embedded within the constitutive law are two empirical parameterizations: the direct effect coefficient, which accounts for stresses perpendicular to the direction of motion, and the state variable, which is derived from the evolution law and describes changes in the physical state of the rock at the friction interface.

A method for the analysis of soil slips triggered by rainfall

A method of practical interest is presented for the analysis of shallow landslides triggered by rain infiltration in unsaturated soils, such as soil slips or slab slides. The method combines an analytical solution to evaluate the change in pore water pressure due to rain infiltration whose rate is described by a general time-dependent function, and the infinite slope model to assess the occurrence of landslide due to a prescribed rainfall.

Failure mechanisms in loess and the effects of moisture content changes on remoulded strength

Investigations into the failure mechanisms of loess slopes in the loess region of north-central China have shown that a majority of mass movements are associated with shallow slab slides predominantly moving under tension. The effects of soil-moisture content are of paramount importance: when dry, vertical slopes in loess may exceed 15 m in height, but under conditions close to saturation the structural strength of loess rapidly decreases, causing failure of the slopes. Mass failure of loess occurs as collapse due to hydroconsolidation, and disintegration of the loess fabric as a result of liquefaction or fluidization, and can be associated with progressive failure processes. Local destruction of the openwork fabric of the loess can lead to small ‘plastic’ movements within the loess deposits. This is as close as loess can come to creep.

Crescent‐shaped slab slides in a submarine canyon system, Arequipa fore‐arc basin, off southern Peru

SeaMARC II side‐scan imagery and bathymetry, seismic reflection, and free‐fall core sampling data reveal the morphology, structure, and hydrology controls on the formation and development of a series of crescent‐shaped slab slides along the submarine canyon walls in the Arequipa fore‐arc basin off southern Peru. The crescent‐shaped slab slides occur in a segment of an approximately 25‐km‐long canyon course and generally accord with the meandering of the canyon course. Most of the slab slides commonly consist of four distinctive zones: the fissured zone, scarp zone, voided zone, and frontal zone. The fissured zone is developed on the crown of the sliding walls; the scarp zone is marked by scars with crescent‐shaped slip surfaces and throws ranging from 50 to 120 m. The voided zone is characterized by 1–3 km wide terraces resulting from slab‐type excavating of the seafloor. The frontal zone is normally comprised of debris materials distributed on the seafloor near the canyon thalweg; however, there is lack ...

Structure and morphology of submarine slab slides: clues to origin and behaviour : O'Leary, D W Marine GeotechnolV10, N1/2, Jan–June 1991, P53–69

Structure and morphology of submarine slab slides: clues to origin and behaviour : O'Leary, D W Marine GeotechnolV10, N1/2, Jan–June 1991, P53–69

千葉県嶺岡隆起帯縁辺部の粘質土地すべりの発生機構と対策

The shallow slab slides which occurred in the area around the Mineoka uplift zone in chiba prefecture were detaily described and discussed on the mechanism of generation and corrective design.The slab slides in this area are recognized to have been formed by the repeated slidings. Repeated slow slides are interpreted to have been mainly caused by the generation of small caves (so-called bora) and successive connection of caves (so-called bora-sawa). The each moving mass has the unit thickness of about 3-5m and is mostly composed of cohesive soil with N≤20, Nsw≤100.Corrective design of surface and trenches was used for the portection of the slides. As a results, the lowering of water level was expected to be 0.5 m and the safeness for the sliding rose 10%.

Structure and morphology of submarine slab slides: Clues to origin and behavior

Abstract Submarine slab slides occur in homoclinal sections of consolidated sediment and lithified strata on continental and insular slopes. They are characterized by distinctive structural and morphological features including complex scarps, sheet‐like or tabular form, proximity to intrastratal deformation, and highly comminuted, long‐runout debris sheets having distinct margins and flow forms. Such slides are difficult to explain by conventional concepts of slope stability that depend on Mohr‐Coulomb failure criteria unless conditions of very low effective stress are invoked. Geologic features suggest that some slab slides probably result from long‐term strength degradation of weak layers deep in the homoclinal section. Time‐dependent strain in clay‐rich layers can create potential slide surfaces of low factional strength. Competent layers are weak in tension and probably fragment in the first instance of, or even prior to, translation, and the allochthonous mass is readily transformed into a high‐momen...

Slab slides of the Alaska earthquake of 1964 : Skladal, G W Bull Assoc Engng Geol, V20, N1, Feb 1983, P5–8

Slab slides of the Alaska earthquake of 1964 : Skladal, G W Bull Assoc Engng Geol, V20, N1, Feb 1983, P5–8

1982 Student Professional Paper: Undergraduate Division: Slab Slides of the Alaska Earthquake of 1964

The Good Friday earthquake of 1964 brought unexpected destruction to the city of Anchorage, Alaska. In the Anchorage area, the quake registered 8.5 on the Richter scale. Though the seismic vibrations were ruinous, the major cause of damage to the city was slab slides. These slides were related to the quick clay properties of Bootlegger Cove Clay which underlies most of Anchorage. Prolonged seismic activity triggered huge masses of earth, initially bounded on one side by a bluff, to move laterally upon a horizontal and planar shear surface within the clay. The lateral displacement of many slides was extensive, and one major slide transported earth more than half a mile. Grabens formed as a result of faulting and collapsing of the sediments within the slab slide. Although the Bootlegger Cove Clay bed is shallow, its presence greatly augmented the destructiveness of the earthquake.

Slope stability and valley formation in glacial outwash deposits, North Norfolk

AbstractDry valleys and gullies in fluvioglacial sands and gravels in North Norfolk are fossil forms. Interpretation of their origin demands detailed morphological analysis, but the inevitable ambiguities of form require additional information on the sedimentology of the deposits and associated regolith. Soil mechanical data and stability analysis predict the observed modal slope angles, assuming the water table to be at or near the surface. This suggests that valley formation involved impeded drainage, and slope processes such as shallow slab slides and solifluction over permafrost. The debris was subsequently evacuated from the valleys by meltwater. The stability analysis also explains the different modal slope angles observed at two locations. Slope angle frequency distributions are composite, however, and include data from varying locations up‐valley. Up‐valley variations in slope angle are seen to reflect variations in the nature of the regolith and consequent changes in soil mechanical properties, as well as changes in valley relief. The up‐valley trends in the nature of the regolith are commensurate with a model of headward valley erosion, with a ‘younger’, less weathered regolith at the present valley head.