Accelerated disintegration of .i.in situ./i. disconnected portions of sandstone outcrops

0545009 - GLÚ 2022 RIV NL eng J - Journal Article
Filippi, Michal - Slavík, M. - Bruthans, J. - Weiss, T. - Řihošek, J.
Accelerated disintegration of in situ disconnected portions of sandstone outcrops.
Geomorphology. Roč. 391, October (2021), č. článku 107897. ISSN 0169-555X. E-ISSN 1872-695X
R&D Projects: GA ČR(CZ) GA19-14082S
Institutional support: RVO:67985831
Keywords : Sandstone * Weathering * Dilation * Rock stress * Disintegration * Confinement
OECD category: Physical geography
Impact factor: 4.406, year: 2021
Method of publishing: Limited access
https://www.sciencedirect.com/science/article/pii/S0169555X21003056

Sandstoneweathering/disintegration is a complex process involving loose material production, rockfall phenomena, and creation of picturesque natural sceneries. On historical monuments, they induce damage to building stone. Here we present a newlook on sandstone weathering/recession the central aspect of which is rapid disintegration of portions of the rock massif, which are no longer physically connected with the main rock mass, though still in situ. A set of field and laboratory measurements including mechanical (tensile strength, drilling resistance) and hydraulic (permeability, surface moisture) methodswere applied to compare the properties of the disconnected portions with those of the surrounding rock mass. Also, physicalweathering experimentswere performed to characterize the effect of confinement on the breakdown rate of several sandstone samples. The presence of disconnected portions is very common in dry climates where they are usually elongated parallel to horizontal surfaces. In humid temperate climates, however, they are less abundant, being elongated mostly vertically. The surfaces of disconnection followbedding planes, planar elements of other sedimentary structures, and subhorizontal fractures, and stress shadows on subvertical cliff faces. Weathered surfaces of the disconnected portions show reduced tensile strength and drilling resistance values, a faster capillary water absorption and a higher surface moisture compared to the much less weathered surfaces of the surrounding rock mass. Physical experiments demonstrated that a confinement by the surrounding rockmassmay considerably delay the loosening of rock during weathering. The much faster disintegration rates of the disconnected portions of rock compared to their surroundings are explained by the fact that they are not confined and have a larger surface area. The recession rates of sandstone surfaces with disconnected portions are highly variable both in space and time and their genesis can be demonstrated by two suggested conceptual models.
Permanent Link: http://hdl.handle.net/11104/0322911