An Approach to the Evaluation of Underground Intersections in Shallow Rock Cover

2007 ◽  
Author(s):  
Eric C. Wang ◽  
Donald P. Richards ◽  
Victor W. K. Wu
Keyword(s):  
Rock Cover

scholarly journals Factors affecting presence and relative abundance of the Endangered volcano rabbit Romerolagus diazi, a habitat specialist

Oryx ◽  
2021 ◽  
pp. 1-10
Author(s):  
Felipe Osuna ◽  
Roger Guevara ◽  
Enrique Martínez-Meyer ◽  
Raúl Alcalá ◽  
Alejandro Espinosa de los Monteros
Keyword(s):  
Sierra Nevada ◽  
Relative Abundance ◽  
Linear Models ◽  
Cattle Grazing ◽  
Patch Occupancy ◽  
Factors Affecting ◽  
Rock Cover ◽  
Volcanic Fields ◽  
Mountain Grasslands ◽  
Insight Into

Abstract Habitat specialists are particularly vulnerable to extinction when habitat conditions are altered. Information on the habitat use of such species is thus important because it provides insight into factors that influence distribution and abundance, which is crucial for conservation. Here, we aimed to identify factors that influence the patterns of presence and abundance of the Endangered volcano rabbit Romerolagus diazi, a rare leporid with a patchy distribution. Through exhaustive sampling of its range in the Sierra Chichinautzin and Sierra Nevada volcanic fields, Mexico, and using generalized linear models, we found that the probability of patch occupancy was higher where bunchgrass cover exceeded 75%, rock cover exceeded 5%, no cattle grazing was observed and human settlements were at least 7 km away. Patches with greater relative abundance were those with similar characteristics, but located at elevations > 3,600 m, and with rock cover < 15%. Cattle grazing was identified as a major threat to local populations of the volcano rabbit, particularly in the Sierra Chichinautzin. Because of the significance of bunchgrasses for this species, the protection of the mountain grasslands is required in both volcanic fields.

Vegetation and vegetation-environment relationships at Grootbos Nature Reserve, Western Cape, South Africa

Bothalia ◽  
2008 ◽  
Vol 38 (1) ◽  
pp. 89-102 ◽  
Author(s):  
M. Mergili ◽  
S. Privett
Keyword(s):  
South Africa ◽  
Nature Reserve ◽  
Soil Depth ◽  
Vegetation Type ◽  
Cape Floristic Region ◽  
Western Cape ◽  
Floristic Diversity ◽  
Rock Cover ◽  
Scrub Forest ◽  
Fire Incidence

The private Grootbos Nature Reserve is located at the Western edge of the Agulhas Plain in the Cape Floristic Region of South Africa, an area characterized by high habitat and floristic diversity. The Reserve is covered in near-natural fynbos shrublands with a few patches of forest and wetland. The main objective of this study was to classify the vegetation into discrete units and relate them to the prevailing environmental conditions. The vegetation was analysed by numerical means (TWINSPAN, DC A, CCA) and mapped on GIS. At the vegetation type level. Forest Thicket and Fynbos formed distinctive clusters, whereas the wetland releves were intermixed, but without relationships to one of these units. Fire incidence served as the major determinant of the forest-fynbos boundary. The Forest Thicket grouping was separated into Thicket (as transitional to fynbos), Afromontane Forest and Milkwood Scrub Forest. Two broad complexes were distinguished within the Fynbos grouping, the Alkaline Sand Fynbos Complex corresponding to Coastal Fynbos. and the Acid Sand Fynbos Complex corresponding to Mountain Fynbos. They discriminated along gradients of pH. soil depth and rock cover. The complexes were further subdivided into formations by using one or a few subjectively chosen dominant species as indicators. The transitions between these formations were rather continuous than discrete. The vegetation type and complex levels correspond well to existing fynbos-wide classifications. Comparing the formations to the results of other vegetation studies is problematic even on the scale of the Agulhas Plain, due to the high regional plant diversity in the Fynbos Biome.

The Volcanic Rock Cover of the Dogu’a Tembien Massif

2019 ◽  
pp. 139-151 ◽  
Author(s):  
Miruts Hagos ◽  
Kassa Amare ◽  
Christian Koeberl ◽  
Jan Nyssen
Keyword(s):  
Volcanic Rock ◽  
Rock Cover

Application of rock cover alteration ratio concept in preliminary design of unlined pressure tunnels

2011 ◽  
Vol 48 (11) ◽  
pp. 1674-1682
Author(s):  
André J. Rancourt ◽  
Hani Mitri
Keyword(s):  
Field Measurements ◽  
Shear Zones ◽  
Design Criterion ◽  
Design Stage ◽  
Preliminary Design ◽  
Rock Cover ◽  
Geological Conditions ◽  
Preliminary Design Stage ◽  
Minimum Stress ◽  
Hydraulic Jacking

Unlined pressure tunnels were first driven by the Norwegians into hard granitic rock, which is the ideal material for this type of structure. However, the increase in demand for electric power has propelled the industry to develop projects at sites all over the world with less favourable geological conditions. The paper places emphasis on the preliminary design phase when no field measurements are available. A recent study by Rancourt (published in 2010) has investigated the spatial distribution of the minimum stress that is required to control hydraulic jacking around unlined pressure tunnels. Various surface topographic profiles including slopes, hills, and valleys; the rock cover to tunnel diameter ratio; as well as the presence of geological features such as shear zones and dykes were investigated with numerical modelling. Effective rock cover predictions are compared to those given by the well-known Norwegian design criterion, and a correction factor called cover alteration ratio (CAR) has been introduced. In this paper, a design methodology is proposed for use of CAR at the preliminary design stage in the form of a factor of safety against hydraulic jacking to be used in conjunction with the Norwegian criterion. Limitations on the use of the Norwegian criterion are highlighted.

scholarly journals Congregating behavior and response to resource distribution of the Green House Millipede, Oxidus gracilis

2016 ◽  
Author(s):  
Gregory Bulpitt
Keyword(s):  
Environmental Factors ◽  
Abiotic Factors ◽  
Environmental Parameters ◽  
Field Recording ◽  
Litter Cover ◽  
Rock Cover ◽  
Oxidus Gracilis ◽  
Experimental Trials ◽  
And Behavior ◽  
Number Of Individuals

Background. Congregating behaviors, though common among many animal species, are little studied among millipedes. It is also unclear to what extent abiotic factors influence the distribution and behavior of millipedes. The species Oxidus gracilis was surveyed around several streams on the island of Mo’orea along with soil moisture, leaf litter cover, and rock cover. Experiments were designed in order to determine how an innate congregating behavior may affect their distributions. Methods. Fifteen transects were performed in the field, recording O. gracilis abundances and the three environmental factors every 1 m. Forty trials were performed using covered bins filled with soil and five fruits of the Tahitian chestnut tree (Inocarpus fagifer). Ten millipedes were placed in the box and left for an hour, after which the number of individuals per fruit was recorded. Results. It was found that while none of the three environmental factors were strong indicators of the distribution of O. gracilis , individuals did in fact demonstrate a tendency to congregate in the experimental trials. Discussion. The lack of significant relationships with the three environmental parameters suggests a generalist behavior of this millipede species, potentially benefitting its invasive nature. The congregating behavior could potentially be for the purposes of mating or defense. Although not studied in this paper, it is possible that conspecific chemical cues are responsible.

Application of Structural Reliability Analysis to UHB Pipeline Design

2007 ◽  
Author(s):  
Terry Griffiths ◽  
Dermot O’Brien ◽  
Richard Johnson
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
Coefficient Of Thermal Expansion ◽  
Design Sensitivity ◽  
Potential Cost ◽  
Upheaval Buckling ◽  
Structural Reliability Analysis ◽  
Rock Cover ◽  
Wide Range ◽  
Pipeline Design

The detailed design of pipelines susceptible to upheaval buckling (UHB) has been characterized by a wide range of industry approaches, especially in relation to selecting safety factors. DNV recently published the draft of their HT/HP design code (RP-F110), which aims to codify and unify approaches to this aspect of design. Sensitivity analysis using Structural Reliability Analysis (SRA) methods highlights the sensitivity of rock cover requirements to a small number of key parameters. Several of these, including: Young’s Modulus; coefficient of thermal expansion; rock cover height; and rock uplift resistance factor have very poor published public domain statistically measured information on mean and variance. It is clear that the early identification in a project of the potential cost benefits associated with an SRA approach maximizes the potential to collect good project-specific statistical data. The clear benefit is an improvement in overall safety by ensuring a more uniform probability of failure along the pipeline which meets target reliability levels.

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