scholarly journals The Friction Angle of the Leiyang Marble Surface after Exposure to High Temperature

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Meng Hong Peng ◽  
Man Huang
Keyword(s):  
Surface Condition ◽  
Surface Friction ◽  
Friction Angle ◽  
Effect Of Temperature ◽  
Tilt Test ◽  
Rock Surface ◽  
Sliding Angle ◽  
Normal Loading ◽  
Basic Friction Angle ◽  
Marble Surface

There is a lack of information about the temperature-dependent nature of the rock surface, which is one of the essential parameters to predict the surface friction. In the present study, we experimentally study the effect of temperature on the basic friction angle of the marble surface through the direct shear test under the low normal loading condition and tilting test (Stimpson/disk tilt test). The basic friction angle gradually decreases with the increase in temperature from 20°C to 600°C for the two kinds of the tilting test. The results indicate that the Stimpson test on samples with the length-to-diameter ratio of 2 can be more reliable to estimate the basic friction angle of the rock surface after exposure to high temperatures. The results illustrate that the sliding angle depends on the surface condition. With the increase in the repetitive measurements, the sliding angle decreases as the marble surface is cleaned, and the parameter increases as the marble surface is not cleaned.

Experimental Studies on the Basic Friction Angle of Planar Rock Surfaces by Tilt Test

2018 ◽  
Vol 47 (1) ◽  
pp. 20170308 ◽  
Author(s):  
Ning Zhang ◽  
Charlie C. Li ◽  
Aizhong Lu ◽  
Xuguang Chen ◽  
Dejun Liu ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Friction Angle ◽  
Tilt Test ◽  
Basic Friction Angle

scholarly journals Determination of the basic friction angle ϕb of joints using the field tilt test: results of various “fast” tests on outcrops

2021 ◽  
Vol 833 (1) ◽  
pp. 012048
Author(s):  
L Jordá-Bordehore ◽  
L Alejano ◽  
R Tomás ◽  
S C Loaiza ◽  
M T García ◽  
...  
Keyword(s):  
Friction Angle ◽  
Tilt Test ◽  
Test Results ◽  
Basic Friction Angle

A finite element study on effect of frictional heating in the taylor rod impact problem

2014 ◽  
Vol 11 (6) ◽  
pp. 529-542 ◽  
Author(s):  
Sachin Gautam ◽  
Ravindra Saxena
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
High Strain ◽  
Frictional Heating ◽  
Equivalent Plastic Strain ◽  
Surface Friction ◽  
Effect Of Temperature ◽  
Element Formulation ◽  
Strain Rates ◽  
High Strain Rates

In an impact phenomenon the material is subjected to very short duration high force levels resulting large plastic deformations and rise in temperature at high strain rates. A circular rod impacting against a rigid surface called as Taylor rod impact test is widely used for determining the mechanical behaviour of materials subjected to high strain rates with associated increase in temperature. A three-dimensional large deformation, thermo-elasto-plastic, dynamic, contact, finite element formulation is developed to study the effect of temperature rise due to plastic deformation and surface friction on the deformation and stress fields. It is found that the predicted equivalent plastic strain values are influenced by temperature generated due to plastic deformation and surface friction. The values of the coefficient of friction have a profound effect on the location of fracture initiation on the impacting face in a circular rod.

scholarly journals Experimental study on acidification effect of tailing sand

2021 ◽  
Vol 248 ◽  
pp. 01048
Author(s):  
Wenzhao Chen ◽  
Kai Yang ◽  
Jiaqing Fan ◽  
Xiqi Liu ◽  
Xiaoqing Wei
Keyword(s):  
Fine Particles ◽  
Iron Concentration ◽  
Chemical Properties ◽  
Surface Friction ◽  
Friction Angle ◽  
Immersion Test ◽  
Coarse Particles ◽  
Natural Conditions ◽  
Lead Zinc ◽  
Reaction Processes

Sulfide minerals (mainly FeS2) contained in lead-zinc tailings are easy to be acidified in the air. The acidification mechanism is that the tailing sand generates sulfuric acid and sulfate under the catalysis of oxidant, water and oxygen. The acidic liquid generated by the reaction will continue to react with metal oxides to form an insoluble precipitate.In order to reveal the corresponding changes of chemical properties and physical properties of lead-zinc tailing sand during acidification, a series of reaction processes of tailings under natural conditions were simulated by immersion test in laboratory.It is found through the test that with the deepening of acidification, the coarse particles of tailing sand dissolve, resulting in the decrease of iron concentration in the compound, the increase of fine particles, the increase of specific surface area, the decrease of surface friction and occlusion friction between particles, resulting in the decrease of internal friction angle, and the decrease of the safety of tailings dam. words.

scholarly journals The competition between folding and faulting in the upper crust based on the maximum strength theorem

2012 ◽  
Vol 468 (2141) ◽  
pp. 1280-1303 ◽  
Author(s):  
G. Kampfer ◽  
Y. M. Leroy
Keyword(s):  
Soil Mechanics ◽  
Surface Friction ◽  
Friction Angle ◽  
Maximum Strength ◽  
Frictional Properties ◽  
Full Development ◽  
Thrust Belts ◽  
Fault Propagation Fold ◽  
Axial Surface ◽  
Kinematic Approach

It is proposed to complement the numerous geometrical constructions of fault-related folds relevant to fold-and-thrust belts by the introduction of mechanical equilibrium and of the rock limited strength to discriminate between various deformation scenarios. The theory used to support this statement is the maximum strength theorem that is related to the kinematic approach of limit analysis known in soil mechanics. The classical geometrical construction of the fault-propagation fold (FPF) is proposed for illustration of our claim. The FPF is composed of a kink fold with migrating axial surfaces ahead of the region where the ramp propagates. These surfaces are assigned frictional properties and their friction angle is found to be small compared with the usual bulk friction angle to ensure the full development of the FPF, a first scenario. For larger values of the axial surface friction angle, this development during overall shortening is arrested by the onset of fault breaking through the front limb, a second scenario. The amount of shortening at the transition from folding to break-through faulting is established.

The effect of weathering on rock wall erosion and rockfall generation at La Cornalle, Switzerland

2020 ◽  
Author(s):  
Li Fei ◽  
Marc-Henri Derron ◽  
Tiggi Choanji ◽  
Michel Jaboyedoff ◽  
Chunwei Sun
Keyword(s):  
Rock Mass ◽  
Monitoring Program ◽  
Time Lapse ◽  
Effect Of Temperature ◽  
Rock Surface ◽  
Rock Wall ◽  
Rock Face ◽  
Surface Areas ◽  
Thaw Cycle ◽  
Rock Temperature

<p>The weathering posing a significant influence on the rock wall retreat has been widely recognized. In this paper, multi-methods monitoring is designed to detect the erosion and rockfall activity on a rockslide cliff composed of marl-sandstone (maybe mixed with limestone) in Western Switzerland. The monitoring program includes weekly SfM and monthly LiDAR scanning measurements of rock cliff surface, hourly time-lapse imaging of the rock cliff, manual measurement of rock surface moisture, automated recordings of rock temperature and influencing meteorological factors (air temperature, humidity, wind, and precipitation) collected by a weather station. Sequential 3D Points Clouds acquired by LiDAR and SfM from December 2019 are used to visually identify the location of erosion and rockfall at monthly resolution. According to the rock wall structural analysis, the rock mass consists of a network of discontinuities mainly oriented nearly parallel and perpendicular to the direction of the layers. Some fractures are filled with calcite which might lead to a zone of weakness in the rock mass. During the field survey, we saw some calcite crystals covering on the rock block surface in the deposit area and exposed on rock cliff outcrop. We suppose that some rockfalls are generated along those discontinuities filled with calcite where the chemical reaction is active when there is constant water infiltrating during rainfall season. According to the preliminary panoramic thermal image of the cliff surface shot by DJI Mavic 2 Enterprise on 19 December 2019, some weathered and fresh surface areas show different temperatures in the same rock layers which suggest the thermal imaging monitoring may help us to identify the weathering spatial characteristics. In this study, we try first to reveal the effect of temperature variations (thermal stress) on crack deformation from rock temperature values extracted from thermal images and the deformation measured by the crack meter during 24h in winter and summer. Secondly, we explore the role of freeze-thaw cycle playing in the rock fall initiation and rock face erosion. Thirdly, we make clear the link between surface weathering spatial distribution and location of erosion, rockfalls. This provides a model of weathering and rockfall estimation.</p>

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