scholarly journals Experimental evaluation of the shear behavior of large landslide slip zone using Multistage - Multiphase shearing method.

2020 ◽  
Author(s):  
Ephrem Getahun ◽  
Shengwen Qi ◽  
Songfeng Guo ◽  
Zhenming Shi
Keyword(s):  
Slip Surface ◽  
Experimental Tests ◽  
Strength Parameter ◽  
Shear Mode ◽  
Friction Resistance ◽  
Shear Process ◽  
Coseismic Landslide ◽  
Ring Shear Apparatus ◽  
Mechanism Of Landslide ◽  
Shear Behaviors

Abstract Abstract The study of shear behaviors comprises of the analysis of shear deformation characteristics and strength parameter determinations. Understanding the constitutive behaviour of shear zone soil samples is essential for evaluation of the critical shear behaviors of reactivated landslides, through considerate experimental tests. The experiment was carried out based on the multistage - multiphase shear technique via ring shear apparatus. The main advantage of this new method is to examine the same soil specimen for progressive loading and the continuous phases of shearing. The result shows that two major shear characteristics under the multiphase shear mode; the first is a post-peak shear weakening behavior of the soils on the last phase shear process, it indicated a decrease in friction resistance on fast rate effects, which enables to narrate with fastly moved coseismic landslide behaviors. The other one is a practical increase in friction coefficient values (hardening behavior) on the entire shear process as the rate increases. This shear resistance scenario can also be related with the stabilization mechanism of landslide slip surface soils against sliding.

scholarly journals Thermal and Quasi-Static Mechanical Characterization of Polyamide 6-Graphene Nanoplatelets Composites

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1454
Author(s):  
Pietro Russo ◽  
Francesca Cimino ◽  
Antonio Tufano ◽  
Francesco Fabbrocino
Keyword(s):  
Chemical Resistance ◽  
Experimental Tests ◽  
Polyamide 6 ◽  
Graphene Nanoplatelets ◽  
Strength Parameter ◽  
Melt Compounding ◽  
Static Mechanical ◽  
Thermal And Electrical Properties ◽  
Multifunctional Products

The growing demand for lightweight and multifunctional products in numerous industrial fields has recently fuelled a growing interest in the development of materials based on polymer matrices including graphene-like particles, intrinsically characterized by outstanding mechanical, thermal, and electrical properties. Specifically, with regard to one of the main mass sectors, which is the automotive, there has been a significant increase in the use of reinforced polyamides for underhood applications and fuel systems thanks to their thermal and chemical resistance. In this frame, polyamide 6 (PA6) composites filled with graphene nanoplatelets (GNPs) were obtained by melt-compounding and compared in terms of thermal and mechanical properties with the neat matrix processed under the same condition. The results of the experimental tests have shown that the formulations studied so far offer slight improvements in terms of thermal stability but much more appreciable benefits regarding both tensile and flexural parameters with respect to the reference material. Among these effects, the influence of the filler content on the strength parameter is noteworthy. However, the predictable worsening of the graphene sheet dispersion for GNPs contents greater than 3%, as witnessed by scanning electron images of the tensile fractured sections of specimens, affected the ultimate performance of the more concentrated formulation.

scholarly journals Analysis of trimaran-pentamaran side hull location based on clearance and staggers with stern form variations

2018 ◽  
Vol 67 ◽  
pp. 04003
Author(s):  
Yanuar ◽  
Wiwin Sulistyawati ◽  
R. Joshua Yones ◽  
Samodero Mahardika
Keyword(s):  
Surface Area ◽  
Optimum Design ◽  
High Speed ◽  
Frictional Resistance ◽  
Experimental Tests ◽  
Hull Form ◽  
Negative Interference ◽  
Friction Resistance ◽  
Resistance Reduction ◽  
Wetted Surface Area

An optimum design of ship is to achieve the required speed with minimum power requirements. On multihull, sidehull position against to mainhull influences the friction resistance and its stability. Frictional resistance of multi-hull increases due to the addition of wetted surface area of hull, but wave making resistance can be lowered by a slender hull form. This research are experimental tests of trimaran with five Wigley hulls on a combination transom and without transom. The test varied on stagger, clearance and trim at several speeds. A ship with formation arrow tri-hull on forward was given to prove the resistance reduction due to cancellation wave which was indicated by negative interference. The influence diverse position of sidehull has shown that model non-transom (NT) stern moreover give beneficial resistance than model with transom (WT) at high speed. Similarly, in the trim conditions that NT more favorable on trim specifically for high speed depending on the position of the sidehull to the mainhull.

Analysis of Earth-Rockfill Dam Slope Stability by Strength Reduction Method Based on Nonlinear Strength

2011 ◽  
Vol 243-249 ◽  
pp. 2271-2275
Author(s):  
Shu Yu ◽  
Li Hong Chen ◽  
Ze Ping Xu ◽  
Ning Chen
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Reduction Method ◽  
Slip Surface ◽  
Strength Reduction ◽  
Strength Parameter ◽  
Strength Reduction Method ◽  
Critical Slip Surface ◽  
Rockfill Dam ◽  
The Earth

In the design process of the earth-rock dam, the slope stability problem was always focused on. The shear strength of rockfill in the earth-rock dam had strong nonlinear characteristics. The characteristic directly affected the factor of safety (FOS) of stability of dam slope and the determination of the critical slip surface. The shear strength parameter of rockfill was related to the minimum principal stress σ3 closely. And the value of σ3 had close relationship with the deformation characteristics of filling material and the process of dam filling etc. Strength reduction method has been widely used in solving the FOS of slope stability, and this method has the advantage on the searching of the critical slip surface. Combining the deformation and stress analysis of earth-rockfill dam filling process and the strength reduction method, this paper proposes a comprehensive method of dam slope stability analysis.

Measurement of the strength parameter on undisturbed slip surface by new Slip Surface Direct Shear box apparatus

Landslides ◽  
2018 ◽  
pp. 641-647
Author(s):  
T. Mayumi ◽  
T. Yamasaki ◽  
K. Kato ◽  
A.M.K.B. Abeysinghe
Keyword(s):  
Slip Surface ◽  
Strength Parameter ◽  
Direct Shear ◽  
Shear Box

Strength Degradation of Existing Bridge Columns under Seismic Loading

1996 ◽  
Vol 1541 (1) ◽  
pp. 29-42
Author(s):  
Omar A. Jaradat ◽  
David I. McLean ◽  
M. Lee Marsh
Keyword(s):  
Shear Failure ◽  
Seismic Loading ◽  
Experimental Tests ◽  
Bridge Columns ◽  
Lap Splices ◽  
Reinforced Concrete Bridge ◽  
Bar Buckling ◽  
Existing Bridges ◽  
Shear Behaviors ◽  
Constant Axial Load

The strength and degradation behavior of reinforced concrete bridge columns under seismic loading were investigated. Experimental tests were conducted on four reduced-scale column specimens that incorporated deficiencies selected to be representative of those present in existing bridges designed before 1971. The columns were fixed against rotation at both the top and bottom, resulting in a transfer of shear forces through the column even after the lower hinging region lost its flexural capacity. The specimens were subjected to increasing levels of cycled inelastic displacements under constant axial load. The focus of the study was to characterize the load and displacement capacities present in older columns for purposes of seismic assessment and retrofit design. Flexure-dominated failures occurred in three of the specimens. A rapid degradation in flexural strength was observed at the bottom hinging regions of the tested columns because of the presence of lap splices and poor confinement. Top hinging regions that did not have lap splices exhibited degradation in flexural capacities at higher displacement ductilities because of eventual longitudinal bar buckling. In the fourth specimen, flexural yielding was initially observed at both the top and bottom of the column, but this was followed by an eventual brittle shear failure. Various procedures for assessing flexural and shear behaviors were compared with the observed experimental results.

Residual strength of smectite-dominated soils from the Kamenose landslide in Japan

1987 ◽  
Vol 24 (3) ◽  
pp. 456-462 ◽  
Author(s):  
Seiichi Gibo ◽  
Kazuhiko Egashira ◽  
Masami Ohtsubo
Keyword(s):  
Residual Strength ◽  
Shear Test ◽  
Slip Surface ◽  
Clay Fraction ◽  
Particle Orientation ◽  
Shear Mode ◽  
Ring Shear Test ◽  
Ring Shear ◽  
Shearing Resistance ◽  
Clay Fraction Content

The residual strength of smectite-dominated soils from the main slip surfaces of the Kamenose landslide, Japan, was measured by ring shear test, and the relations of the residual strength to the clay fraction content and clay particle orientation were studied. The residual angles of shearing resistance, [Formula: see text], were estimated assuming that the residual cohesion is zero. The magnitude of the residual angle of shearing resistance was dependent on the <2-μm clay fraction content, CF, and on the effective normal stress, [Formula: see text], because of curved strength lines. At [Formula: see text] equivalent to the overburden pressures, the soils had [Formula: see text] of 6–8°. These residual angles of shearing resistance were fitted on the [Formula: see text] – CF line for sand–bentonite mixtures, and exhibited the sliding shear mode.The orientation of smectite particles on shear surfaces showing slickensides was assessed by X-ray diffraction technique. The orientation of smectite particles was found to reduce the residual strength considerably, and this orientation effect was revealed more clearly at low effective normal stresses. Key words: residual strength, particle orientation, landslide, smectite, shear mode, slip surface, slickenside, clay mineral, physicochemical properties, ring shear test.

scholarly journals Railroad Tie Lateral Resistance on Open-Deck Plate Girder Bridges

2020 ◽  
Author(s):  
John T. Gergel ◽  
Vishali M. Vasudevan ◽  
Matthew H. Hebdon
Keyword(s):  
Wood Species ◽  
Experimental Tests ◽  
Lateral Loads ◽  
Friction Resistance ◽  
Railroad Bridges ◽  
Girder Bridges ◽  
Lateral Resistance ◽  
Deck Plate ◽  
Bridge Superstructure ◽  
Plate Girder

Abstract On open-deck railroad bridges, the crossties (sleepers) are directly supported by the bridge superstructure and anchored with deck tie fasteners such as hook bolts. These fasteners provide lateral resistance for the bridge ties, and in railroad bridge design, their spacing is controlled by the required lateral resistance of the ties. Currently there are no provisions to assist in the calculation of lateral resistance provided by railroad ties on open-deck bridges, and as a result there are no specific requirements for the spacing of deck tie fasteners. This has led to different design practices specific to each railroad, and inconsistent fastener spacing in existing railroad bridges. A research plan was conducted to experimentally quantify the lateral resistance of timber crossties on open-deck plate girder bridges using different wood species and types of fasteners. Experimental tests were conducted on four different species of timber crossties (Beech, Sycamore, Southern Pine, and Oak) with three different types of fasteners (square body hook bolt, forged hook bolt, and Quick-Set Anchors). A structural test setup simulated one half of an open-deck bridge with a smooth-top steel plate girder, and hydraulic actuators to apply both vertical and horizontal load to a railroad tie specimen. The three main contributions to lateral resistance on open-deck bridges were identified as friction resistance between tie and girder due to vertical load from a truck axle, resistance from the fastener, and resistance from dapped ties bearing against the girder flange. Initial testing conducted at Virginia Tech isolated each component of lateral resistance to determine the friction coefficient between tie and girder as well as resistance from just the fastener itself. Results indicate that friction resistance varies based on the magnitude of vertical truck axle load, species of wood, and quantity of creosote preservative on the tie, while fastener resistance varies based on type of fastener and displacement of the tie. With the experimental results, a preliminary equation for calculating the overall resistance of open-deck timber crossties is developed, which allows for a recommendation of fastener spacing based on the type of fastener, wood species, and anticipated lateral loads on the structure.

Study on Seepage Properties of Zheng-Gang Large Landslide under Rainfall Condition

2012 ◽  
Vol 594-597 ◽  
pp. 2557-2563 ◽  
Author(s):  
Yu Zhang ◽  
Bo Lu ◽  
Huai Kun Sun
Keyword(s):  
Slip Surface ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Hydrodynamic Pressure ◽  
Rainfall Infiltration ◽  
Rainfall Condition ◽  
Sliding Mechanism ◽  
Mechanism Of Landslide ◽  
Effective Drainage ◽  
Seepage Properties

Under influence of heavy rainfall, the Zheng-gang landslide in Gu-Shui hydropower station of China started to have serious deformation. Based on the geological field investigations, the mechanism of rainfall infiltration was qualitatively analyzed previously. The rainfall infiltration reduces shear strength on the slip surface by increasing pore water pressure and the hydrodynamic pressure is generated which increased with the hydraulic gradient and water level, thus resulting in the instability of landslide and increased landslide movement. Secondly, combined with the seepage theory of saturated-unsaturated, quantitative study was carried out on the seepage properties of landslide under rainfall condition. Not only the dynamic sliding mechanism of landslide is revealed, but also the seepage stability was evaluated. The worst stability condition came out 4 days after the rain stopped, and the maximal thickness of perched water up to 6m. The results of stability analysis have agreement with the field observations. Finally, the effective drainage measures were proposed.

Study of the Effect of Shear Rates on Residual Shear of Landslide Soil

2013 ◽  
Vol 639-640 ◽  
pp. 598-601
Author(s):  
Chuan Sheng Chen ◽  
Jing Fang Liu ◽  
Shi Zhi Wen
Keyword(s):  
Friction Coefficient ◽  
Residual Strength ◽  
Slip Surface ◽  
Shear Behaviour ◽  
Residual Shear Strength ◽  
Shear Rates ◽  
Ring Shear ◽  
Ring Shear Apparatus ◽  
The Stability ◽  
Landslide Slope

The residual strength is one of the most important strength parameters to evaluate the stability of a reactivated landslide slope, but the relation between residual strength gained by using ring shear tests and shear speed still remains unclear. In order to clarify the relationship between them, the variation in residual friction coefficient of slip surface soils with shearing rates were calculated and discussed in this paper by means of an undrained ring shear apparatus on Miaowan sample of China-Loess Plateau , predominantly consists of silty-sandy(81.3%), and Kamenose sample of Japan, predominantly consists of clay(73.2%) in texture .The residual friction coefficient was observed to be lower for higher shear rates in Kamenose sample;while the variation of its shear behaviour at different shear rates is fluctuant in Miaowan sample. This change in pore water pressures and soil texture could be thought as the rate effect mechanism of residual shear strength.

Non-Linear Modeling of Masonry Arches Strengthened with FRCM

2017 ◽  
Vol 747 ◽  
pp. 93-100 ◽  
Author(s):  
Bartolomeo Pantò ◽  
Marialaura Malena ◽  
Gianmarco de Felice
Keyword(s):  
Cultural Heritage ◽  
Central Italy ◽  
Closed Form Solution ◽  
Polymeric Materials ◽  
Experimental Tests ◽  
Constitutive Law ◽  
Shear Mode ◽  
Masonry Arches ◽  
Macro Modeling ◽  
Non Linear

Recent seismic events, such as the Central Italy (2016), the Emilia (2012) and L’Aquila (2009) earthquake, have demonstrated the high vulnerability of cultural heritage represented by historical and monumental buildings. These structures are often characterized by the presence of elements with a curved geometry such as arches and vaults, which interact with the vertical elements (walls or columns) during the earthquake motion, producing a significant effect on the seismic response of the entire structure. Aiming at the reduction of the seismic vulnerability of curved masonry elements, several techniques of reinforcing based on composite fiber materials, have been recently developed and widely investigated by means of experimental tests and numerical simulations. The using of fiber reinforced systems, applied through cementitious mortar (FRCM), is becoming a very common technique of retrofitting for historical and monumental masonry buildings. This technique, if compared to the using of fiber polymeric materials (FRP), is more compatible with the mechanical properties of the masonry and more appropriate with the preservation needs of cultural heritage, associated to the historical constructions. A discrete macro-modeling approach, already available in the literature for modeling masonry structures with plane and curved geometry, is here employed to predict the non-linear behaviour of masonry arches strengthened with FRCM. In that approach the reinforcement is explicitly modeled by using a rigid plate, while the interaction between the reinforcement and the masonry support is governed by a discrete zero thickness interface. In this paper the interfacial behavior is updated with a more sophisticated bond-slip constitutive law specifically conceived for FRCM reinforcement within the framework of fracture mechanics; in particular the proposed calibration takes into account both the pure opening mode (mode I) and the in plane shear mode (mode II). The obtained numerical results are compared with an analytical closed form solution of the problem and validated by mean of experimental tests on prototypes, available in the literature.

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