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Limit equilibrium methods I – planar failure surfaces
Published in Robin Chowdhury, Phil Flentje, Gautam Bhattacharya, Geotechnical Slope Analysis, 2009
Robin Chowdhury, Phil Flentje, Gautam Bhattacharya
The importance of local geology to an understanding of slope behaviour was mentioned briefly in chapter 1. Soils are far from homogeneous and geological conditions may be quite complex. Most interesting practical situations arise when there is interbedding of permeable and impermeable strong and weak layers. Interbedded sand and clay layers or sandstone and shale beds are quite common. Let us first consider a sand layer on an impermeable clay layer whose surface makes an inclination ?with the horizontal. Critical conditions will arise when seepage occurs through the sand layer. The critical angle of stability (the critical value of ?) of the sand layer may be determined by equating the shear strength and shear stress at the base of an element, the base being parallel to the surface of the sand layer. The total normal stress and the shear stress on the base is (see Figure 4.11):
Basic characteristics of soils
Published in Jonathan Knappett, R. F. Craig, Craig’s Soil Mechanics, 2019
Jonathan Knappett, R. F. Craig
Discontinuities such as fissures and shear planes, including their spacings, should be indicated. Bedding features, including their thickness, should be detailed. Alternating layers of varying soil types or with bands or lenses of other materials are described as interstratified. Layers of different soil types are described as interbedded or inter-laminated, their thickness being stated. Bedding surfaces that separate easily are referred to as partings. If partings incorporate other material, this should be described.
Basic characteristics of soils
Published in R.F. Craig, Craig’s Soil Mechanics, 2004
Discontinuities such as fissures and shear planes, including their spacings, should be indicated. Bedding features, including their thickness, should be detailed. Alternating layers of varying soil types or with bands or lenses of other materials are described as interstratified. Layers of different soil types are described as interbedded or interlaminated, their thickness being stated. Bedding surfaces that separate easily are referred to as partings. If partings incorporate other material, this should be described.
Assessing the effects of land cover change in runoff processes with RHESSys: a case study in the Waterford River Watershed, Newfoundland and Labrador, Canada
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2023
David Bautista, Lakshman Galagedara
The surface elevation in the area ranges from 0 to 260 m above the coastal mean sea level for North America (CGVD2013). Trees in this watershed are relatively small and short because of poor soil conditions (stony, shallow, highly acidic, and low fertility). The soil’s texture is coarsely to moderately-coarsely, strongly to extremely acidic, and the natural fertility is predominantly low (Ullah et al. 1988). The soil is characterized by Precambrian sedimentary rock materials, interbedded clastic sediments of sandstone, conglomerated, and slate-siltstones (Batterson, 1983). Because of hills orientation and rocky ridges parallel to the bedrock structures, infiltration processes are poor, snowmelt and rainfall have little influence on groundwater recharge, and most of the water resource is essentially converted into surface runoff (Ullah et al. 1988).
Numerical investigation of lithology and its sedimentary sequence on fracture height containment
Published in Petroleum Science and Technology, 2023
Wen Zhang, Xiangjun Liu, Lixi Liang, Jian Xiong, Jianjun Wu, Bing Li
The Ordos Basin is an important basin in northern China (Chen et al. 2011). Affected by the depositional environment, the shale gas reservoir in the study block is characterized by frequent interbedded lithology (Figure 1a), which is embodied in large sets of shale, thin sandstone, thin coal seam, carbonaceous shale, siltstone, and other lithology are frequently superimposed. Horizontal well combined with hydraulic fracturing technology is used as a key technical means for developing shale gas in this formation (Figure 1b). However, hydraulic fractures are often faced with the problem of insufficient fracture height in such reservoirs. Therefore, to improve the success rate of later fracturing, it is necessary to study the hydraulic fracture height containment based on lithology characteristics.
Sediment provenance in the Murchison and Maruia basins, Aotearoa/New Zealand: a record of Neogene strike-slip displacement, convergence, and basement exhumation along the Australian–Pacific plate boundary
Published in New Zealand Journal of Geology and Geophysics, 2022
Matthew W. Sagar, Karen E. Higgs, Dominic P. Strogen, Kyle J. Bland, Greg H. Browne
The Mangles Formation passes conformably upwards into c. 3000 m of middle–late Miocene Longford Formation (Figure 5; Figure 6). A c. 200-m-thick succession of pebble conglomerate overlain by coaly beds, medium sandstone, and carbonaceous mudstone that was deposited in an estuarine environment during the earliest middle Miocene comprises the basal Longford Formation. Fluvial conglomerate interbedded with subordinate sandstone, mudstone and coal compose the overlying c. 2800 m. The stratigraphic age range of the conglomeratic succession is not well-constrained but may span much of the middle and late Miocene (c. 16–5 Ma; Clifdenian–Kapitean stages). The uppermost levels of the Longford Formation are not preserved, with c. 3000 m thought to have been eroded due to Neogene deformation and uplift (Nathan et al. 1986).