Back Analysis of Landslide Deposit Basal Failure Plane Residual Shear Strength

IACGE 2013 ◽  
2013 ◽  
Author(s):  
N. Matasovic ◽  
C. Conkle ◽  
A. F. Witthoeft ◽  
A. Stern ◽  
T. Hadj-Hamou
Keyword(s):  
Shear Strength ◽  
Back Analysis ◽  
Failure Plane ◽  
Residual Shear Strength ◽  
Landslide Deposit

A landslide in till near Warman, Saskatchewan, Canada

1985 ◽  
Vol 22 (2) ◽  
pp. 195-204 ◽  
Author(s):  
E. Karl Sauer ◽  
E. A. Christiansen
Keyword(s):  
Shear Strength ◽  
Water Table ◽  
Back Analysis ◽  
Clay Content ◽  
Aerial Photographs ◽  
Adjacent Area ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Residual Shear Strength ◽  
Insight Into

Little information is available about typical shear strength parameters of tills in southern Saskatchewan even though till is the most common earth material used for construction in this region. The Warman landslide in the South Saskatchewan River Valley provides some insight into the shear strength characteristics of a till, and the results are compared with laboratory tests. The till is from the Upper till of the Sutherland Group, which has a high clay content relative to the underlying and overlying tills. A back analysis of the landslide produced [Formula: see text]′ = 27° assuming c′ = 0. Comparison with laboratory test data and results from a similar landslide near Lebret, Saskatchewan, suggests that [Formula: see text]′ = 22.5° with c′ = 7 kPa may be appropriate "residual" shear strength parameters. A rising water table appears to have been the main contributing factor to instability between 1969 and 1984. There is a possibility, however, that at the 1:50 return interval for flood levels on the river, erosion at the toe of the landslide debris may be a significant factor. Numerous slump scars in the form of small amphitheatres, presently inactive, can be observed in the aerial photographs of the adjacent area. These failures likely occurred intermittently, depending on fluctuating water table and river flood levels. Key words: landslide, till, correlation, stratigraphy, back analysis, shear strength, residual, aerial photographs.

Regina Beach — a town on a landslide

1986 ◽  
Vol 23 (1) ◽  
pp. 60-68 ◽  
Author(s):  
A. Wayne Clifton ◽  
Richard T. Yoshida ◽  
Roy W. Chursinoff
Keyword(s):  
Shear Strength ◽  
Back Analysis ◽  
Slope Movement ◽  
Mountain Lake ◽  
Residual Shear Strength ◽  
Bentonitic Clay ◽  
South Central ◽  
Risk Of Rupture ◽  
Landslide Development ◽  
The Town

The town of Regina Beach is constructed on landslides along the Last Mountain Lake valley, a glacial meltwater channel in south-central Saskatchewan, Canada. The landslides are retrogressive in nature and are seated in bentonitic clay shale of the Bearpaw Formation. A study was conducted at Regina Beach to determine the sensitivity of the slopes to changes in slope geometry as a result of regrading, or groundwater changes. Back-calculated shear strength was compared with values from the laboratory and from other landslides in Cretaceous bedrock shales. Modest changes in grading of the toe areas would result in significant reductions in the local stability and future movements of upslope portions of the landslide. Development should minimize the amount of grading. Increased slope movement due to breaks in watermains was observed and measured. This correlated well with analysis. Development in landslide areas must assume that differential vertical and horizontal movements will occur. Proper site reconnaissance should identify optimum locations for buildings and services such that the risk of rupture or damage is minimized. Key words: landslide, retrogressive, back analysis, residual shear strength, Bearpaw Formation, inclinometer, slope movement.

scholarly journals Experimental Study on the Shear Behavior of Bolted Concrete Blocks with Oblique Shear Test

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Bo Meng ◽  
Hongwen Jing ◽  
Shengqi Yang ◽  
Yingchao Wang ◽  
Biao Li
Keyword(s):  
Shear Strength ◽  
Shear Failure ◽  
Normal Force ◽  
Concrete Block ◽  
Shear Resistance ◽  
Shear Behavior ◽  
Failure Plane ◽  
Residual Shear Strength ◽  
Apparent Cohesion ◽  
Concrete Blocks

The shear behavior of concrete blocks reinforced by fully grouted bolts with different diameters was studied in this paper. More than 90 intact cubic samples (100 mm × 100 mm × 100 mm) with bolts ranging from 2 mm to 5 mm in diameter were tested at a constant stain rate of 0.5 mm/min. An oblique shear apparatus, which could simultaneously apply shear and normal force on tested samples at three slope angles (53°, 58°, and 63°) of a predetermined shear plane, was employed. The results indicate that the bolt has no evident influence on the shear behavior of intact concrete blocks at the prepeak shear strength stage. The bolt could significantly reduce the shear strength drop in the peak shear strength of the concrete block and contribute to reserving the residual shear strength of concrete blocks, especially at steep slope angles of the shear failure plane. The shear resistance provided by the bolt to the concrete block at the residual shear slip stage has a positive relationship with the diameter. The bolt with a larger diameter inflected in the vicinity of the shear failure plane of concrete block at the postpeak shear strength stage; additional normal force and direct shear resistance could still be persistently provided. Two empirical equations of the apparent cohesion and apparent internal angle of the bolted concrete block were obtained by linear regression considering rb, which is the ratio of the cross-sectional area of the bolt to that of the bolted concrete block.

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.

Residual shear strength of fine-grained soils and soil–solid interfaces at low effective normal stresses

2015 ◽  
Vol 52 (2) ◽  
pp. 198-210 ◽  
Author(s):  
Hisham T. Eid ◽  
Ruslan S. Amarasinghe ◽  
Khaled H. Rabie ◽  
Dharma Wijewickreme
Keyword(s):  
Shear Strength ◽  
Large Strain ◽  
Laboratory Research ◽  
Normal Stresses ◽  
Interface Shear ◽  
Residual Shear Strength ◽  
Fine Grained ◽  
Solid Interface ◽  
Wide Range ◽  
Shear Area

A laboratory research program was undertaken to study the large-strain shear strength characteristics of fine-grained soils under low effective normal stresses (∼3–7 kPa). Soils that cover a wide range of plasticity and composition were utilized in the program. The interface shear strength of these soils against a number of solid surfaces having different roughness was also investigated at similar low effective normal stress levels. The findings contribute to advancing the knowledge of the parameters needed for the design of pipelines placed on sea beds and the stability analysis of shallow soil slopes. A Bromhead-type torsional ring-shear apparatus was modified to suit measuring soil–soil and soil–solid interface residual shear strengths at the low effective normal stresses. In consideration of increasing the accuracy of assessment and depicting the full-scale field behavior, the interface residual shear strengths were also measured using a macroscale interface direct shear device with a plan interface shear area of ∼3.0 m2. Correlations are developed to estimate the soil–soil and soil–solid interface residual shear strengths at low effective normal stresses. The correlations are compared with soil–soil and soil–solid interface drained residual shear strengths and correlations presented in the literature.

Drained Residual Shear Strength Power Function Coefficients a and b

2021 ◽  
Vol 44 (6) ◽  
pp. 20200234
Author(s):  
Timothy D. Stark ◽  
Abedalqader Idries
Keyword(s):  
Shear Strength ◽  
Power Function ◽  
Residual Shear Strength

Ballistic impact response of carbon/epoxy tubes with variable nanosilica content

2017 ◽  
Vol 52 (12) ◽  
pp. 1589-1604 ◽  
Author(s):  
Aniruddh Vashisth ◽  
Charles E Bakis ◽  
Charles R Ruggeri ◽  
Todd C Henry ◽  
Gary D Roberts
Keyword(s):  
Fracture Toughness ◽  
Shear Strength ◽  
Glass Transition ◽  
Transition Temperature ◽  
Impact Damage ◽  
Mass Density ◽  
Impact Response ◽  
Residual Shear Strength ◽  
Damage Area ◽  
The Matrix

Laminated fiber reinforced polymer composites are known for high specific strength and stiffness in the plane of lamination, yet relatively low out-of-plane impact damage tolerance due to matrix dominated interlaminar mechanical properties. A number of factors including the toughness of the matrix can influence the response of composites to impact. The objective of the current investigation is to evaluate the ballistic impact response of carbon/epoxy tubes with variable amounts of nanosilica particles added to the matrix as a toughening agent. Mass density, elastic modulus, glass transition temperature and Mode I fracture toughness of the matrix materials were measured. Tubes manufactured with these matrix materials were ballistically impacted using a round steel projectile aimed at normal incidence across the major diameter. After impact, the tubes were nondestructively inspected and subjected to mechanical tests to determine the residual shear strength in torsion. Increasing concentrations of nanosilica monotonically increased the modulus and fracture toughness of the matrix materials. Tubes with nanosilica had smaller impact damage area, higher residual shear strength, and higher energy absorbed per unit damage area versus control materials with no nanosilica. Overall, the addition of nanosilica improved the impact damage resistance and tolerance of carbon/epoxy tubes loaded in torsion, with minimal adverse effects on mass density and glass transition temperature.

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