Geotechnical characteristics of large rapid rock slides

2010 ◽  
Vol 47 (1) ◽  
pp. 116-132 ◽  
Author(s):  
James Glastonbury ◽  
Robin Fell
Keyword(s):  
High Strength ◽  
Significant Loss ◽  
Slide Mass ◽  
Geotechnical Characteristics ◽  
Lateral Margins ◽  
Internal Deformation ◽  
Strength Rock ◽  
First Time ◽  
Loss Of Strength ◽  
Rock Slides

Based on the analysis of 51 case studies of large rapid rock slides, for a landslide to travel rapidly after failure there has to be a significant loss of strength on the basal surface of rupture, lateral margins, and (or) internally within the slide mass, or the factor of safety has to be maintained below 1.0 after failure by high groundwater pressures. Internally sheared compound slides and translational slides may all travel rapidly depending on their detailed geotechnical and geometric characteristics. The characteristics of these landslides that suggest an increased likelihood of rapid failure have been identified. All the rapid rock slides examined in this study involved relatively high-strength rock masses. Most cases were considered to be first-time landslides, largely involving brittleness on the basal rupture surface. However, there were some cases considered to be reactivated or active landslides on pre-sheared rupture surfaces. For this latter group, the loss of strength leading to rapid landsliding was associated with brittle internal deformation or lateral margins.

Geotechnical characteristics of large slow, very slow, and extremely slow landslides

2008 ◽  
Vol 45 (7) ◽  
pp. 984-1005 ◽  
Author(s):  
James Glastonbury ◽  
Robin Fell
Keyword(s):  
Friction Angle ◽  
Slow Movement ◽  
Rupture Surface ◽  
Rock Mass Strength ◽  
Geotechnical Characteristics ◽  
Lateral Margins ◽  
Slow Moving ◽  
Rock Slides ◽  
Piezometric Pressure ◽  
Landslide Movement

Based on a study of 45 large slow-moving landslides, it is apparent that for a landslide to travel slowly after failure, the sliding is most likely to be active or reactivated, on a basal rupture surface at or close to residual strength. The likelihood of slow movement after failure is also increased when the inclination of the basal rupture surface is less than the residual friction angle. The slow-moving landslides are all of low rock-mass strength with varying degrees of disaggregation, or they possess soil strength. The influence of lateral margins on landslide restraint is generally small, with landslide movement typically controlled by fluctuations in piezometric pressure. The most commonly observed slow large landslides are mudslides and translational debris–rock slides, followed by particular forms of translational rock slides and internally sheared compound slides. Some mudslides display evidence of short periods of up to moderate velocities.

scholarly journals ADDITIVE REFURBISHMENT OF A VIBRATION-LOADED STRUCTURAL COMPONENT

2021 ◽  
Vol 1 ◽  
pp. 345-354
Author(s):  
Nicola Viktoria Ganter ◽  
Tobias Ehlers ◽  
Paul Christoph Gembarski ◽  
Roland Lachmayer
Keyword(s):  
Fatigue Strength ◽  
Structural Component ◽  
Significant Loss ◽  
Additive Process ◽  
Particle Damping ◽  
Bending Stresses ◽  
First Time ◽  
Loss Of Strength

AbstractIn the event of damage to additively manufactured components whose shape cannot be produced by machining, an additive repair can potentially be not only ecologically but also ecologically more favorable than the production of a new component. In addition, a number of hurdles that otherwise often impede the use of additive repair, e.g. the availability of the material of the damaged component for the additive process, are eliminated. As far as the authors are aware, this publication is the first to present a process for the additive refurbishment of additively manufactured components using the example of a wheel carrier. In this context, the possibility of increasing the fatigue strength of a structural component in refurbishment is discussed for the first time. To increase the fatigue strength of the wheel carrier, the chosen approach is to integrate the effect of particle damping into the component. Particularly in the case of components subjected to bending stresses, the effect of particle damping can be integrated into the component's interior without having to accept a significant loss of strength.

Major rock slides in the Rockies

1976 ◽  
Vol 13 (1) ◽  
pp. 8-20 ◽  
Author(s):  
D. M. Cruden
Keyword(s):  
The United States ◽  
Aerial Photographs ◽  
Rupture Surface ◽  
Characteristic Appearance ◽  
Slide Mass ◽  
Order Of Magnitude ◽  
Lateral Margins ◽  
Further Development ◽  
Rock Slides ◽  
Geometry And Kinematics

The Frank Slide is the best known of a number of major rock slides in the Canadian Rockies. Seven other slides of the same order of magnitude are described from the Front and Main Ranges between Jasper and the United States border.The geometry and kinematics of the slides are controlled by discontinuities in the rock slide mass. Typically, the major part of the rupture surface is parallel to bedding; the orientation of the lateral margins and the scarp of the slide may be controlled by joint sets.Sliding tends to occur on slopes where bedding dips towards valleys at angles between 30 and 40° and in thickly-bedded, massive weathering rocks such as quartzites, dolomites, and limestones. Major causes of sliding appear to be erosion at the foot and lateral margins of the slide mass.The slides may be easily identified on aerial photographs by their effect on the local vegetation and by the characteristic appearance of their debris. All the slides observed are post-glacial, their frequency seems to have been underestimated and, in places, they may impose major constraints on further development.

TRANSMISSION ELECTRON MICROSCOPY OF SURFACE AND INTERFACIAL STEPS

1997 ◽  
Vol 04 (03) ◽  
pp. 559-566 ◽  
Author(s):  
J. M. GIBSON ◽  
X. CHEN ◽  
O. POHLAND
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Free Surface ◽  
Significant Loss ◽  
Stress Fields ◽  
Preliminary Results ◽  
Surface Steps ◽  
Transmission Electron ◽  
First Time

Transmission electron microscopy is uniquely able to extend techniques for imaging free surface steps to the buried interface regime, without significant loss of detail. Two mechanisms for imaging surface and interfacial steps by transmission electron microscopy are described. They are thickness contrast and strain contrast. The former reveals the position and approximate height of steps, whereas the latter detects stress fields which are commonly associated with steps. The basis for each of these methods is elaborated, and preliminary results are shown for step images at Si/SiO2 interfaces, where measurable stress fields have been directly detected for the first time.

scholarly journals Nitrogen-phosphate Fertilizers Based on Activation of Phosphorite Powder with Partially Ammoniated Mix of Phosphoric and Sulphuric Acids

2020 ◽  
pp. 1-10
Author(s):  
A. A. Rasulov ◽  
Sh. S. Namazov ◽  
B. E. Sultonov
Keyword(s):  
Citric Acid ◽  
Gross Domestic Product ◽  
Optimal Condition ◽  
Ammonium Sulphate ◽  
Weight Ratio ◽  
High Strength ◽  
Technological Parameters ◽  
Phosphate Fertilizers ◽  
First Time ◽  
Phosphoric Acids

In this article obtaining complex nitrogen-phosphate fertilizers based on activation of phosphorite powder with partially ammoniated mix of phosphoric and sulphuric acids have been studied. In order to reduce the foaming of the process, for the first time a partially ammoniated mix of acids was used. The optimal technological parameters for activation phosphorite powder with partially neutralized mixes of sulphuric and phosphoric acids are the followings: the mix of sulphuric and phosphoric acids with a ratio of SО3:Р2О5 = 1.2; рН of acids – 2.5; weight ratio of ammonium sulphate-phosphate slurry towards phosphorite powder is 100 : 20; temperature is 60°С; duration is 30 min.  The composition nitrogen-phosphate fertilizers obtained in optimal condition contains (wt., %): N – 11.55; Р2О5total -24.61; Р2О5acceptable by citric acid -21.66; Р2О5 acceptable by EDTA -20.24; Р2О5water-soluble  -13.02; CaOtotal -13.59; СаОacceptable by citric acid -11.43. In that condition, granulated products of nitrogen-phosphate can be produced with high strength. The advantage of offered promising technology concludes in reduction two times expenditure of the most expensive ammonia in comparison with ammonium sulphate production and an increase in gross domestic product.

scholarly journals The nanostructuring of ultra-high-molecular-weight polyethylene in thermal and mechanical fields as revealed by DSC

2021 ◽  
Vol 2103 (1) ◽  
pp. 012095
Author(s):  
L P Myasnikova ◽  
A K Borisov ◽  
Yu M Boiko ◽  
A P Borsenko ◽  
V F Drobot’ko ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Melting Temperature ◽  
Mechanical Characteristics ◽  
Thickness Distribution ◽  
High Strength ◽  
High Modulus ◽  
Know How ◽  
First Time ◽  
Ultra High Molecular Weight

Abstract The ultra-high-molecular-weight polyethylene reactor powders are widely used for the actively developing solvent-free method for producing high-strength high-modulus PE filaments, which includes the compaction and sintering of a powder followed by orientational hardening. To find an appropriate regime of the technological process, it is important to know how the nanostructure changes when transforming from a powder to a precursor for hardening. Nanocrystalline lamellae are characteristics of the powder structure. For the first time, the DSC technique was used to follow changes in the thickness distribution of lamellae in ultra-high-molecular-weight polyethylene reactor powder on its way to a precursor for orientation hardening. It was found that the percentage of thick (>15 nm) and thin (10 nm) lamellae in compacted samples and those sintered at temperatures lower than the melting temperature of PE (140°C) remains nearly the same. However, significant changes in the content of lamellae of different thicknesses were observed in the samples sintered at 145°C with subsequent cooling under different conditions. The influence of the lamellae thickness distribution in precursors on the mechanical characteristics of oriented filaments was discussed.

scholarly journals Effects of Calcium Phosphate Nanoparticles on Ca-PO4 Composite

2007 ◽  
Vol 86 (4) ◽  
pp. 378-383 ◽  
Author(s):  
H.H.K. Xu ◽  
M.D. Weir ◽  
L. Sun ◽  
S. Takagi ◽  
L.C. Chow
Keyword(s):  
Volume Fraction ◽  
High Strength ◽  
Nano Particles ◽  
Nano Silica ◽  
Ion Release ◽  
Mass Fractions ◽  
Calcium Phosphate Nanoparticles ◽  
Filler Mass ◽  
First Time ◽  
Filler Level

Nano-particles of dicalcium phosphate anhydrous (DCPA) were synthesized for the first time. The objectives of this study were to incorporate DCPA nano-particles into resin for Ca-PO4 release to combat dental caries, and to investigate the filler level effects. Nano-DCPA and nano-silica-fused silicon nitride whiskers at a 1:1 ratio were used at filler mass fractions of 0–75%. The flexural strengths in MPa (mean ± SD; n = 6) of DCPA-whisker composites ranged from (106 ± 39) at 0% fillers to (114 ± 23) at 75% fillers, similar to (112 ± 22) of a non-releasing composite (TPH) (p > 0.1). The composite with 75% fillers in a NaCl solution (133 mmol/L, pH = 7.4, 37°C) yielded a Ca concentration of (0.65 ± 0.02) mmol/L and PO4 of (2.29 ± 0.07) mmol/L. Relationships were established between ion-release and DCPA volume fraction VDCPA: Ca = 4.46 VDCPA1.6, and = 66.9 VDCPA2.6. Nano-DCPA-whisker PO4 composites had high strength and released high levels of Ca-PO4 requisite for remineralization. These new nano-composites could provide the needed combination of stress-bearing and caries-inhibiting capabilities.

scholarly journals Gut mucosal virome alterations in ulcerative colitis

Gut ◽  
2019 ◽  
Vol 68 (7) ◽  
pp. 1169-1179 ◽  
Author(s):  
Tao Zuo ◽  
Xiao-Juan Lu ◽  
Yu Zhang ◽  
Chun Pan Cheung ◽  
Siu Lam ◽  
...  
Keyword(s):  
Clustering Algorithm ◽  
Intestinal Inflammation ◽  
Rectal Mucosa ◽  
Significant Loss ◽  
Healthy Controls ◽  
Virus Like Particle ◽  
Geographical Regions ◽  
Viral Communities ◽  
First Time ◽  
Gut Microbiota Dysbiosis

ObjectiveThe pathogenesis of UC relates to gut microbiota dysbiosis. We postulate that alterations in the viral community populating the intestinal mucosa play an important role in UC pathogenesis. This study aims to characterise the mucosal virome and their functions in health and UC.DesignDeep metagenomics sequencing of virus-like particle preparations and bacterial 16S rRNA sequencing were performed on the rectal mucosa of 167 subjects from three different geographical regions in China (UC=91; healthy controls=76). Virome and bacteriome alterations in UC mucosa were assessed and correlated with patient metadata. We applied partition around medoids clustering algorithm and classified mucosa viral communities into two clusters, referred to as mucosal virome metacommunities 1 and 2.ResultsIn UC, there was an expansion of mucosa viruses, particularly Caudovirales bacteriophages, and a decrease in mucosa Caudovirales diversity, richness and evenness compared with healthy controls. Altered mucosal virome correlated with intestinal inflammation. Interindividual dissimilarity between mucosal viromes was higher in UC than controls. Escherichia phage and Enterobacteria phage were more abundant in the mucosa of UC than controls. Compared with metacommunity 1, metacommunity 2 was predominated by UC subjects and displayed a significant loss of various viral species. Patients with UC showed substantial abrogation of diverse viral functions, whereas multiple viral functions, particularly functions of bacteriophages associated with host bacteria fitness and pathogenicity, were markedly enriched in UC mucosa. Intensive transkingdom correlations between mucosa viruses and bacteria were significantly depleted in UC.ConclusionWe demonstrated for the first time that UC is characterised by substantial alterations of the mucosa virobiota with functional distortion. Enrichment of Caudovirales bacteriophages, increased phage/bacteria virulence functions and loss of viral-bacterial correlations in the UC mucosa highlight that mucosal virome may play an important role in UC pathogenesis.

scholarly journals Study of the Efficiency of Ultrasonic Turning of Heat-Resistant Alloys with Tools from Mineral Ceramics

2019 ◽  
Vol 297 ◽  
pp. 01011
Author(s):  
Nguyen Khanh Toan ◽  
Nikolay Mezin
Keyword(s):  
Nickel Alloys ◽  
High Speed ◽  
Metal Removal ◽  
Ultrasonic Field ◽  
Significant Loss ◽  
Field Energy ◽  
Thermal Processes ◽  
Heat Resistant ◽  
Defective Layer ◽  
Loss Of Strength

The results of the study of the effectiveness of high-speed ultrasonic turning of billets from heat-resistant nickel alloys without coolant are given. It was established that the introduction of ultrasonic field energy into the shaping zone reduces the contact temperature by 10–15% and the cutting force by 20–30%. However, this does not cause a decrease in metal removal performance due to a significant loss of strength and ease of cutting at temperatures above 800 C. As follows from the results, ultrasound helps to reduce the thickness of the defective layer, the formation of which is caused by thermal processes and phase transformations with the appearance of tensile residual stresses in the surface layer.

Evaluation of a metal acrylic repair product as a clamp for an external fixator

2004 ◽  
Vol 17 (02) ◽  
pp. 97-103 ◽  
Author(s):  
N. R. Gibson ◽  
R. A. Read ◽  
R. Day ◽  
I. D. Robertson ◽  
K. L. Staudte
Keyword(s):  
Mechanical Testing ◽  
Significant Variation ◽  
Significant Loss ◽  
External Fixators ◽  
Frame Design ◽  
Pullout Tests ◽  
Cyclical Loading ◽  
Cantilever Bending ◽  
Equivalent Strength ◽  
Loss Of Strength

SummaryMechanical testing was performed to evaluate an acrylic steel repair paste when used in the construction of external fixators. Individual pin-bar-acrylic constructs were compared with those made from Kirschner-Ehmer (KE) clamps or polymethylmethacrylate. The constructs were subjected to cantilever bending forces, pin-pullout tests and cantilever bending after undergoing cyclical fatigue. Forty mm segments of acrylic were significantly stronger than medium ESF clamps. Twenty-five mm segments of acrylic were of equivalent strength to clamps. Ten mm segments failed under physiological loads expected from dogs greater than 20 kg and were less likely to provide adequate pin coverage to protect against pin pull-put. The placement of a wire loop to secure the pin-bar intersects made application of the acrylic easier but did not alter stiffness. There was not any significant variation between different operators in the strength of their constructs nor tolerance of their constructs to pin pullout. Cyclical loading forces were applied to acrylic-pinbar units without significant loss of strength, and acrylic and polymethylmethacrylate units did not show any difference in stiffness after being subjected to cyclical fatigue. The acrylic steel repair paste is a handkneadable, fast setting, inexpensive and readily available acrylic for use in the construction of external fixators. It allows more flexibility in frame design than a clamp and on the basis of mechanical testing offers a very stiff and secure substitute for KE clamps or polymethylmethacrylate.

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