The geotechnical characteristics of an ice-thrust mudstone, Wabamun Lake area, Alberta

1989 ◽  
Vol 26 (2) ◽  
pp. 227-234 ◽  
Author(s):  
D. M. Cruden ◽  
S. Thomson ◽  
P. C. Tsui
Keyword(s):  
Shear Strength ◽  
Shear Zone ◽  
Upper Cretaceous ◽  
Slope Failure ◽  
Back Analysis ◽  
Soft Rock ◽  
Lake Area ◽  
Geotechnical Characteristics ◽  
Brittle Mode ◽  
Maximum Shear Strength

This first detailed report of the geotechnical characteristics of ice-thrust soft rock examines Upper Cretaceous, once heavily overconsolidated mudstones in the Highvale coal mine, Alberta. The fissured and brecciated sample from an ice-thrust shear zone in the mine behaves as a lightly overconsolidated sediment in laboratory tests and shows a non-brittle mode of shear deformation with a maximum shear strength close to residual. This behaviour is due to weathering and glaciotectonic deformation, which have jointed, sheared, and remoulded the mudstone, thus eliminating the fabric formed by overconsolidation.In the ice-thrust mudstone, platy clay minerals dominate and have been grouped into aggregations or shear-remoulded matrices. The strength of the brecciated portion of the mudstone ranges from peak to residual. The strength along principal displacement shears is at or close to residual, as back analysis of a slope failure shows. Key words: ice-thrust shear zone, glaciotectonic deformation, consolidation, nonbrittle deformation, principal displacement shears, shear strength.

Deterministic and probabilistic treatments of multiplanar pitwall failures at Himmetoglu (Turkey) coal mine

2001 ◽  
Vol 38 (4) ◽  
pp. 828-849 ◽  
Author(s):  
Ergün Tuncay ◽  
Resat Ulusay
Keyword(s):  
Shear Strength ◽  
Coal Mine ◽  
Slope Failure ◽  
Failure Modes ◽  
Probabilistic Approach ◽  
Back Analysis ◽  
The South ◽  
Bedding Planes ◽  
Geotechnical Investigations ◽  
Deterministic And Probabilistic Approaches

This paper describes the investigation of a large and progressive slope failure in the south sidewall of the Himmetoglu coal mine in northwest Turkey. A number of slope instabilities leading to interruptions in mining have been experienced at the mine. Geotechnical investigations consisted of structural mapping, observations of instabilities, review of detailed groundwater information, long-term monitoring of slope movement, and back-analysis of the various failure modes. Deterministic and probabilistic approaches based on the limiting-equilibrium method were employed to examine various slope profiles and excavation sequences for achieving better stability conditions. Analysis of the movement monitoring records and geotechnical information indicated that the failure of the south sidewall slope developed by a combination of sliding along the bedding planes in the hanging wall and faults in the mode of multiplanar sliding. The movement history and the results from the back-analysis of the failures revealed that the stability of the slope was highly sensitive to changes in the length of the lower part of the sliding surface, and the shear strength reduced to residual values along the discontinuity surfaces 8-10 m above the coal seam at the time of failure. The results of the analysis both from deterministic and probabilistic approaches suggest that an excavation sequence consisting of a number of stripping stages from the uppermost benches and advancing to the toe of the slope may provide the resistance to stabilize the overall slope. Simple and preliminary economic assessments based on the overburden costs in conjunction with the deterministic and probabilistic approaches are briefly discussed.Key words: back-analysis, deterministic approach, Himmetoglu coalfield, monitoring, multiplanar failure, probabilistic approach, shear strength, slope stability.

Finite Element Modeling of a Mechanically Stabilized Earth Trial Wall

2021 ◽  
pp. 036119812110164
Author(s):  
Andrew Lees ◽  
Michael Dobie
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Retaining Wall ◽  
Back Analysis ◽  
Soil Parameters ◽  
Failure Behavior ◽  
Valuable Insight ◽  
Deformation And Failure ◽  
First Case ◽  
Soil Shear Strength

Polymer geogrid reinforced soil retaining walls have become commonplace, with routine design generally carried out by limiting equilibrium methods. Finite element analysis (FEA) is becoming more widely used to assess the likely deformation behavior of these structures, although in many cases such analyses over-predict deformation compared with monitored structures. Back-analysis of unit tests and instrumented walls improves the techniques and models used in FEA to represent the soil fill, reinforcement and composite behavior caused by the stabilization effect of the geogrid apertures on the soil particles. This composite behavior is most representatively modeled as enhanced soil shear strength. The back-analysis of two test cases provides valuable insight into the benefits of this approach. In the first case, a unit cell was set up such that one side could yield thereby reaching the active earth pressure state. Using FEA a test without geogrid was modeled to help establish appropriate soil parameters. These parameters were then used to back-analyze a test with geogrid present. Simply using the tensile properties of the geogrid over-predicted the yield pressure but using an enhanced soil shear strength gave a satisfactory comparison with the measured result. In the second case a trial retaining wall was back-analyzed to investigate both deformation and failure, the failure induced by cutting the geogrid after construction using heated wires. The closest fit to the actual deformation and failure behavior was provided by using enhanced fill shear strength.

Online-Joining of C/SiC-C/SiC via Slurry Reaction and Precursor Infiltration and Pyrolysis Process with C/SiC Pins

2012 ◽  
Vol 531-532 ◽  
pp. 135-140 ◽  
Author(s):  
Yu Di Zhang ◽  
Hai Feng Hu ◽  
Chang Rui Zhang ◽  
Guang De Li
Keyword(s):  
Shear Strength ◽  
Carbon Fiber ◽  
Flexural Strength ◽  
Fracture Mode ◽  
Pyrolysis Process ◽  
Strong Bond ◽  
Sic Composites ◽  
Maximum Shear Strength ◽  
Application Prospects ◽  
Complex Components

C/SiC composites have widely application prospects in the field of aeronautic and aerospace for their excellent properties. The joining of C/SiC composites is a key to fabricate large and complex components. In this paper, 1D C/SiC pins were prepared by precursor infiltration and pyrolysis (PIP) process and used to join C/SiC composites by Slurry react (SR) and PIP process. The shear strength of the C/SiC pins with different carbon fiber volumes was investigated with the maximum shear strength as high as 339.46MPa. Influences of C/SiC pins on the joining properties of C/SiC composites were studied. The shear strength and flexural strength of C/SiC-C/SiC joining are improved from 9.17MPa and 30.41MPa without pins to 20.06MPa and 75.03MPa with one C/SiC pin (diameter 2mm), respectively. The reliability of C/SiC-C/SiC joining is also improved with C/SiC pins in that the fracture mode changes from catastrophic without pins to non-catastrophic. The SEM photos show a strong bond between joining layer and C/SiC composites without obvious interface.

scholarly journals Determination of reinforcing bars for tests of hollow core slabs with continuity

2013 ◽  
Vol 6 (6) ◽  
pp. 903-932
Author(s):  
A. P. Santos ◽  
M. A. Ferreira ◽  
R. C. Carvalho ◽  
L. M. Pinheiro
Keyword(s):  
Shear Strength ◽  
The Other ◽  
Hollow Core ◽  
Reinforcing Bars ◽  
Simply Supported ◽  
Resistance Moment ◽  
Hollow Core Slab ◽  
Maximum Shear Strength

The structural designs of floors formed by hollow core slabs usually consider these as simply-supported slabs. In recent years there have been project changes and hollow core slabs with continuity are widely used. The objective of this study is to suggest a way to calculate the reinforcement bars to be used in tests with continuity provided by a structural topping. Thus, this paper presents a method based on the maximum positive resistance moment and maximum shear strength of a hollow core slab. The method is applied to a test in hollow core slab specimens which have the following dimensions: 2 m width, 6 m long, and 21 cm high. The results indicated that the method was satisfactory to the performed test, and can therefore be applied to the other test configurations or even designs.

scholarly journals Investigations of a Weathered and Closely Jointed Rock Slope Failure Using Back Analyses

2021 ◽  
Vol 13 (23) ◽  
pp. 13452
Author(s):  
Kuo-Shih Shao ◽  
An-Jui Li ◽  
Chee-Nan Chen ◽  
Chen-Hsien Chung ◽  
Ching-Fang Lee ◽  
...  
Keyword(s):  
Failure Criterion ◽  
Slope Failure ◽  
Back Analysis ◽  
Jointed Rock ◽  
Geological Strength Index ◽  
Northeastern Region ◽  
In Situ Investigation ◽  
Disturbance Factor ◽  
Value Range ◽  
Jointed Rock Slope

This study presents the case of a landslide triggered by a high groundwater level caused by several days of continuous rainfall in the northeastern region of Taiwan. The slope where this landslide occurred consists of closely jointed and weathered bedrock. By means of finite element limit analysis and the Hoek–Brown failure criterion, this study performed a slope failure simulation similar to the actual landslide and deduced the reasonable value range for the combination of key Hoek–Brown failure criterion parameters through back analyses. The results indicate that the key parameters affecting the bedrock’s slope stability were the geological strength index (GSI) and the disturbance factor (D), whereas the effects of the unconfined compressive strength (σci) were less significant. The results of the back analysis reveal that the suitable D-value range and GSI of closely jointed and weathered sandstone in the northeastern region of Taiwan are 0.8 to 0.9 and 20 to 30, respectively. These back-analyzed value ranges can serve as a reference for broader applications in the preliminary stability analysis of similar rock slopes where it is difficult to perform in situ investigation.

scholarly journals Diffusion Bonding of Ti6Al4V at Low Temperature via SMAT

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 94
Author(s):  
Yuqing Chen ◽  
Guofeng Wang ◽  
Yongkang Liu ◽  
Liqiang Zhan ◽  
He Diao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Diffusion Bonding ◽  
Welded Joint ◽  
Surface Mechanical Attrition Treatment ◽  
Mechanical Attrition ◽  
Long Time ◽  
Tc4 Alloy ◽  
Heat Preservation ◽  
Maximum Shear Strength

Titanium alloys used to be welded to gain good joint strength at 920 °C through diffusion bonding. However, due to the heat preservation at high temperatures for a long time, we obtain joints with great bond strength while the mechanical properties of the sheet are lost. In this paper, taking Ti6Al4V alloy as an example, we studied the microstructure of the surface under the different times of surface mechanical attrition treatment (SMAT). In addition, the microstructure and mechanical properties after diffusion bonding at 800 °C-5 MPa-1 h were also conducted. The results show that the shear strength of TC4 alloy welded joint after SMAT treatment is improved, and the maximum shear strength can reach 797.7 MPa, up about 32.4%

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