Seismic stability of the Revelstoke earthfill dam

1982 ◽  
Vol 19 (1) ◽  
pp. 63-75
Author(s):  
K. S. Khilnani ◽  
P. M. Byrne ◽  
K. K. Yeung
Keyword(s):  
Time History ◽  
Seismic Stability ◽  
Triaxial Tests ◽  
Dynamic Resistance ◽  
Foundation Soil ◽  
Dynamic Stresses ◽  
Cyclic Triaxial Tests ◽  
Undisturbed Samples ◽  
History Of ◽  
Liquefaction Failure

The foundation soil beneath the earthfill section of the proposed Revelstoke dam comprises, in part, a deep silt-clay layer that contains pockets of loose to compact saturated sands. Removal of this material beneath the core of the dam was required for seepage and erosion control. Analyses were performed to determine if considerations of earthquake stability would also require removal of this material beneath the shells.A factor of safety against the occurrence of a liquefaction failure beneath the shells was determined by comparing the dynamic resistance obtained from cyclic triaxial tests on undisturbed samples with the time history of dynamic stresses caused by the design earthquakes. Preliminary analyses clearly indicated that the silt-clay beneath the upstream shell should be removed. Beneath the downstream shell, the computations indicated factors of safety at the lower range of acceptable values and a portion of the silt-clay beneath the downstream shell was removed so that only minor damage would occur even in the unlikely event of liquefaction of the material left in place.

Deviation Forces From the Wedge Penetration Failure of Anisotropic Rock

1973 ◽  
Vol 95 (4) ◽  
pp. 1093-1100 ◽  
Author(s):  
W. B. Bradley
Keyword(s):  
Time History ◽  
Theoretical Work ◽  
Drill String ◽  
Triaxial Tests ◽  
Maximum Deviation ◽  
Anisotropic Rock ◽  
Green River ◽  
Rock Interaction ◽  
Confining Pressures ◽  
History Of

Deviation of boreholes is caused by drill string flexibility and the interaction between the drill bit and the formation being drilled. While work has been devoted to the analysis of drill string mechanics, less work has been directed toward the understanding of bit rock interaction. This paper presents the results from some experimental work on the deviation forces and chip volumes generated by the wedge penetration of anisotropic rock. The single blow wedge penetration tests were conducted on blocks of Green River shale cut to simulate formation dip angles from 0 to 90 deg. During the tests, the time history of the force required to penetrate the rock, together with the deviation forces perpendicular and parallel to the strike of the formation were recorded. Tests were conducted using wedges with 30 and 60 deg included wedge angles at atmospheric and 10,000 psi confining pressures. In conjunction with these tests, triaxial tests were performed to determine the failure characteristics of this particular rock. Results from these tests showed that appreciable deviation forces were generated by the 30 and the 60 deg wedges at both confining pressures. Maximum deviation forces were generated in the 30 deg dip region and in the 60 deg dip region, with the deviation forces tending to zero at 0 deg, 90 deg, and in the region of 45 deg. The results are in general agreement with field observations. The volumes generated correlate with the measured forces as well as field experience. Predominant chip volumes were created on the updip side of the tooth at low dip angles and on the downdip side of the tooth at high dip angles for both tooth geometries. Published predictions on the advantages of 60 deg teeth for deviation control were found to be in disagreement with experimental results. When combined with the measured rock failure properties, the theoretical work upon which the above predictions were based did predict deviation forces in qualitative agreement with the experimentally determined values.

Liquefaction Testing of Stratified Sands Interlayered with Silt

2012 ◽  
Vol 256-259 ◽  
pp. 116-119 ◽  
Author(s):  
Min Cai Jia ◽  
Bing Ye Wang
Keyword(s):  
Critical Thickness ◽  
Confining Pressure ◽  
Cyclic Behavior ◽  
Triaxial Tests ◽  
Experimental Program ◽  
Cyclic Triaxial Tests ◽  
Hydraulic Fill ◽  
Soil Deposits ◽  
History Of ◽  
Different Thickness

The cyclic behavior of stratified sands interlayered with silt is at present poorly understood, although stratified sands exist for various soil deposits and hydraulic fill, which have a history of liquefaction during earthquakes. The main objective of this research project was to compare the cyclic behavior of stratified and homogeneous sands for various silt contents. A comprehensive experimental program was undertaken in which stain-controlled undrained cyclic triaxial tests for stratified sand samples interlayered with different thickness silt were performed. The silt thickness ranged from 0 to 80mm was considered. The confining pressure in all test series was 100kPa. The results indicate that the thickness of the silt seam sandwiched in the sand samples has a significant influence on the liquefaction resistances of layered sands. In other words, there is a critical thickness of silt seam that the saturated stratified sands have a critical shear strain. This finding justifies applying the laboratory tests results of homogeneously reconstituted samples to the field conditions for the range of variable studied.

PROGRAM OF PREDICTION AND MANAGEMENT OF COINTEGED DYNAMIC ECONOMIC PROCESSES BASED ON THE CYBERNETIC APPROACH

2019 ◽  
Author(s):  
Olena Bundak ◽  
Nataliia Zubovetska
Keyword(s):  
Computer Program ◽  
Pair Correlation ◽  
Time History ◽  
Critical Area ◽  
Concrete Object ◽  
Graphic Arts ◽  
Ex Post ◽  
History Of ◽  
Successive Change ◽  
Rms Errors

A method and computer program ConRow, which prognostication of development of the dynamically CPLD economic transients is executed by, is described in the article. Such prognostication of economic processes is very important in the cases when their development can result in undesirable consequences, that to go out in the so-called critical area. Extrapolation in a critical area with the use of information about the conduct of the system at an area, near to it, allows to estimate to the lead through of experiment in the critical area of his consequence. For the imitation of conduct of object the function of review is set on entrance influence. For a concrete object this function can express, for example, dependence of change of level sale from time-history of charges on advertising and set as a numeral row. Statistics as a result of analysis of row are represented in a table, where the level of meaningfulness is set statistician, and also parameters of the handed over criteria. The graphic reflection of information is intended for visualization of analysis. Here represented on the points of graphic arts, the crooked smoothing which are calculated as полиномиальные regressions is added. The best approaching is controlled by sight on the proper graph, and also by minimization of their rms errors. Models of prognostication by sight and as formulas represented on graphic arts, the middle is here determined tailings and their chance is checked up on statistics of signs. After the got models determined also and prognosis values of influences and reviews. Establishing an order models of Сr(p) of co integrate regression is carried out separate custom controls. The coefficient of clay correlation of ruФ shows by itself pair correlation between lines with a successive change in relation to each other on a size to лагу of l = 1, 2, 3 . The program was tested on the example of ex-post prognosis at establishing an integration connection and possibility of prognostication of growth of nominal average monthly settlings on the basis of these statistical indexes of consumer inflation in Ukraine.

scholarly journals Comparison of Novel Seismic Protection Devices to Attenuate the Earthquake Induced Energy

Actuators ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 73
Author(s):  
Osman Hansu ◽  
Esra Mete Güneyisi
Keyword(s):  
Lateral Displacement ◽  
Time History ◽  
Seismic Protection ◽  
Base Shear ◽  
Seismic Demands ◽  
Nonlinear Time History Analyses ◽  
History Of ◽  
Protection Devices ◽  
Nonlinear Time History ◽  
Better Than

This study addresses an alternative use of viscous dampers (VDs) associated with buckling restrained braces (BRBs) as innovative seismic protection devices. For this purpose, 4-, 8- and 12-story steel bare frames were designed with 6.5 m equal span length and 4 m story height. Thereafter, they were seismically improved by mounting the VDs and BRBs in three patterns, namely outer bays, inner bays, and all bays over the frame heights. The structures were modeled using SAP 2000 software and evaluated by the nonlinear time history analyses subjected to the six natural ground motions. The seismic responses of the structures were investigated for the lateral displacement, interstory drift, absolute acceleration, maximum base shear, and time history of roof displacement. The results clearly indicated that the VDs and BRBs reduced seismic demands significantly compared to the bare frame. Moreover, the all-bay pattern performed better than the others.

scholarly journals Development of a Field Deployable Firebrand Flux and Condition Measurement System

2020 ◽  
Author(s):  
Simone Zen ◽  
Jan C. Thomas ◽  
Eric V. Mueller ◽  
Bhisham Dhurandher ◽  
Michael Gallagher ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Time History ◽  
Infrared Camera ◽  
Thermal Conditions ◽  
Particle Characterization ◽  
Fire Dynamics ◽  
Rate Of Spread ◽  
New Instrument ◽  
History Of

AbstractA new instrument to quantify firebrand dynamics during fires with particular focus on those associated with the Wildland-Urban Interface (WUI) has been developed. During WUI fires, firebrands can ignite spot fires, which can rapidly increase the rate of spread (ROS) of the fire, provide a mechanism by which the fire can pass over firebreaks and are the leading cause of structure ignitions. Despite this key role in driving wildfire dynamics and hazards, difficulties in collecting firebrands in the field and preserving their physical condition (e.g. dimensions and temperature) have limited the development of knowledge of firebrand dynamics. In this work we present a new, field-deployable diagnostic tool, an emberometer, designed to provide measurement of firebrand fluxes and information on both the geometry and the thermal conditions of firebrands immediately before deposition by combining a visual and infrared camera. A series of laboratory experiments were conducted to calibrate and validate the developed imaging techniques. The emberometer was then deployed in the field to explore firebrand fluxes and particle conditions for a range of fire intensities in natural pine forest environments. In addition to firebrand particle characterization, field observations with the emberometer enabled detailed time history of deposition (i.e. firebrand flux) relative to concurrent in situ fire behaviour observations. We highlight that deposition was characterised by intense, short duration “showers” that can be reasonably associated to spikes in the average fire line intensity. The results presented illustrate the potential use of an emberometer in studying firebrand and spot fire dynamics.

Effect of the loading frequency on the sand liquefaction behaviour in cyclic triaxial tests

2021 ◽  
Vol 147 ◽  
pp. 106779
Author(s):  
Zhehao Zhu ◽  
Feng Zhang ◽  
Qingyun Peng ◽  
Jean-Claude Dupla ◽  
Jean Canou ◽  
...  
Keyword(s):  
Triaxial Tests ◽  
Loading Frequency ◽  
Cyclic Triaxial ◽  
Cyclic Triaxial Tests ◽  
Sand Liquefaction

scholarly journals Research of the Behavior of Clay Materials with Double Porosity

2021 ◽  
Vol 13 (6) ◽  
pp. 3219
Author(s):  
Hynek Lahuta ◽  
Luis Andrade Pais
Keyword(s):  
Double Porosity ◽  
Strength Properties ◽  
Triaxial Tests ◽  
Building Structures ◽  
Foundation Soil ◽  
Problematic Use ◽  
The North ◽  
Static Liquefaction ◽  
Confinement Stress ◽  
Clay Materials

This contribution presents results from a series of compression and undrained triaxial tests to study the mechanical behavior of dump clay from the north of Bohemia. The use of these materials as a foundation for construction can’t be achieved without the adoption of some precautions. This comes from embankment, formed by digging the ground (altered claystone), up to the level of coal mining which is in a sub horizontal stratigraphic layer. A potential static liquefaction behavior was observed in undrained tests for high confinement stress. A structural collapse was noticed with the results obtained in the triaxial test. This collapse is characterized by an unexpected large decrease in deviator and mean effective stress. The soils formed have strength properties that are potentially dangerous. These concepts can improve the use of these kinds of soils in geotechnical engineering work. It continues and expands the results obtained in previous research, especially the future problematic use of these materials as the foundation soil for line or building structures.

Stationary and Transient Response of Cylindrical Shells Under Random Excitation

1988 ◽  
Vol 110 (2) ◽  
pp. 205-209
Author(s):  
A. V. Singh
Keyword(s):  
Transient Response ◽  
Random Vibration ◽  
Time History ◽  
Wide Band ◽  
Random Excitation ◽  
Mode Shapes ◽  
The Finite Element Method ◽  
History Of ◽  
The Mean ◽  
Random Vibration Analysis

This paper presents the random vibration analysis of a simply supported cylindrical shell under a ring load which is uniform around the circumference. The time history of the excitation is assumed to be a stationary wide-band random process. The finite element method and the condition of symmetry along the length of the cylinder are used to calculate the natural frequencies and associated mode shapes. Maximum values of the mean square displacements and velocities occur at the point of application of the load. It is seen that the transient response of the shell under wide band stationary excitation is nonstationary in the initial stages and approaches the stationary solution for large value of time.

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