Analysis of crack movements observed in an alpine bedrock cliff
Crack widths and rock temperatures were monitored on an andesitic bedrock cliff in the summit area of the Daisetsu Mountains, Hokkaido. Sequential data recorded the gradual widening of a crack to the point of critical crack extension, which resulted
in catastrophic rock breakage. Using these sequential data, the timing, magnitude, and dominant agent of crack movement are considered, with particular focus on the parameters related to rock fracture mechanics.
Origin and distribution of polygonal cracking of rock surfaces
The review of the literature and field studies by the AA. show that the cracking is much more widespread than has been generally recognised. Most of the existing theories fail to explain its geographical distribution. This paper suggests
that cracking is a direct or indirect consequence of surface crusting.
Surface disaggregation and essentially surface-parallel cracks were produced in sandstone blocks using 10 per cent solutions of sodium sulphate and magnesium sulphate applied daily to single exposed surfaces for sixty days. A control block soaked
once in saturated magnesium sulphate and subsequently wetted daily with distilled water showed extensive surface disaggregation, but no cracking. Both surface disaggregation and subsurface cracking were associated with relative concentrations
of microcrystalline salt. A tentative model of contour scaling is proposed, which involves linking together potential cracks by salt-induced fracturing of intervening, crack-stopping grains.
Seasonal dynamics of soil-water pressure in a cracking clay soil
This paper describes the results of an investigation of changes in soil water pressure head and its relationship to the macropore network in a cracking clay soil at Brimstone Farm, Oxfordshire, UK.
Investigating landslide-related cracks along the edge of two loess platforms in northwest China
China ; Crack ; Gansu ; Geophysics ; Irrigation ; Landslide ; Loess ; North-Western China ; Plateau ; Shaanxi ; Slope dynamics ; Soil properties ; Soil water
Cracks are widely developed along the edge of loess platforms in northwest China. Field surveys reveal that these cracks can be grouped into shallow and deeply penetrating ones. The former occur at a small distance from the platform edge, normally
penetrate into the top unsaturated loess with the penetration depth being controlled by the joints in loess. The latter penetrate deeper into the saturated loess farther away from the platform edge. These cracks control the inflow and drainage of irrigation
water. A full-scale field test simulating irrigation on the platform surface was conducted. The 2 types of crack can be interconnected so that the water applied in the test finally flowed into the deep crack and was discharged from the platform. Analysis
of soil stress states and the results of field test show that the deeply-penetrating cracks could have both positive as well as negative effects on slope stability.
Frost-cracking conditions, Bylot Island, Eastern Canadian Arctic Archipelago
This paper examines how frost-cracking events are related to variations in air and ground temperatures. The implications of the results for ice-wedge dynamics, frost cracking processes and frozen ground rheology are also discussed. The study site
An evaluation of the use of size distribution of sediment in runoff as a measure of aggregate breakdown in the surface of a cracking clay soil under rain
Two rainfall simulators of different plot size were used to test whether sediment in runoff could be used to measure aggregate breakdown in the surface of a cracking clay soil under rain. Size distributions of deposited sediment were similar
Thermal-contraction-crack networks as evidence for Late-Pleistocene permafrost in Inner Mongolia, China
Numerous wedges on the Ordos Plateau show typical characteristics of periglacial sand wedges that enable them to be distinguished from desiccation cracks in clayey illuviation soil horizons. The sand wedges are organized in 2 generations
The cause of this collapse has been studied from the viewpoint of engineering geology. The works (1992) have pointed out that tension cracking behind the cliff could increase its instability. However, no quantitative analysis of the effect
of tension cracking was given using slope instability analysis. This paper provides quantitative analysis, with emphasis on the effect of tension cracking.
On 5 March 1987 two earth tremors caused topsoil and turf overturning, cracks in the ash mantle, and probably also cracks in soil profiles. In seismically active regions such episodic events may substantially influence soil profile development.
Pingos in Antarctica appear to be residual landforms that have formed on the surface of the moraine as the ice core has been destroyed by ablation and thermal erosion. This interpretation appears to have misinterpreted tension cracks and coherent
slumping of sediment as dilation cracks and as evidence for the extrusion of a central sediment plug. Pingos on supraglacial debris have not been described from any other locations and it seems that their formation is inconsistent with the ablation
In situ observation of cracks in frozen soil using synchrotron tomography
of Leighton Buzzard sand, Reigate sand and spherical glass ballotini (an idealised soil). High-resolution images were obtained using a monochromatic, parallel beam of x-rays generated on Beamline I12 of the Diamond synchrotron. Cracking in the ice was directly
measured utilising the phase-contrast fringes generated by ice-air interfaces. Examination of these images revealed two modes of crack formation in the ice phase of frozen soil. Both crack types were orientated parallel to the freezing front (normal
to the heat flow), affecting both the frozen soils' mechanical behaviour, and the AA. hypothesise that these cracks are potential initiation sites for ice lens development.
by wetting and drying of clay sediments, which produces horizontal cracks within bluff material. These cracks appear to penetrate to a depth of approximately 100-150 mm before initiating vertical cracking in the sediments.
Prediction of tension crack location and riverbank erosion hazards along destabilized channels
to predict the location of tension cracks on the floodplain behind the eroding bank ace is presented and tested. A case study is used to illustrate the computational procedure required to apply the model. Improved estimates of failure block geometry using