Creep Tests on Reconstituted Soft Clay, Performed by Means of a Biaxial Device

Author(s):  
Alessandra Bizzarri
Keyword(s):  
2011 ◽  
Vol 90-93 ◽  
pp. 1819-1823
Author(s):  
Bin Tang ◽  
Zhe Zeng ◽  
Yan Xia Gong

Abstract: Conducted a series of triaixl coupled consolidation and creep tests ,and researched the coupled consolidation and creep character for the typical soft clay in Wuhan region in different drainage conditions.The following conclusions are got from analysing the stress、strain and time relationship curves in different conditions:(1)The consolidation drainage condition is very important in the soil consolidation creep deformation.When the stress is low,the deformation amount in the consolidation undrained condition is much smaller than that in the consolidation drained condition;with the increasing of the stress,the viscoplasticity will appear,and the deformation speed in the undrained condition exceeded that in the drained condition;when the stress increases to some point,the deformation amount in the undrained condition will exceed that in the drained condition finally.(2)The consolidation creep deformation rule for the typical soft clay in Wuhan region in different drainage conditions can be expressed by empirical formula.


Author(s):  
F. Monchoux ◽  
A. Rocher ◽  
J.L. Martin

Interphase sliding is an important phenomenon of high temperature plasticity. In order to study the microstructural changes associated with it, as well as its influence on the strain rate dependence on stress and temperature, plane boundaries were obtained by welding together two polycrystals of Cu-Zn alloys having the face centered cubic and body centered cubic structures respectively following the procedure described in (1). These specimens were then deformed in shear along the interface on a creep machine (2) at the same temperature as that of the diffusion treatment so as to avoid any precipitation. The present paper reports observations by conventional and high voltage electron microscopy of the microstructure of both phases, in the vicinity of the phase boundary, after different creep tests corresponding to various deformation conditions.Foils were cut by spark machining out of the bulk samples, 0.2 mm thick. They were then electropolished down to 0.1 mm, after which a hole with thin edges was made in an area including the boundary


2013 ◽  
Vol 58 (1) ◽  
pp. 95-98 ◽  
Author(s):  
M. Zielinska ◽  
J. Sieniawski

Superalloy René 77 is very wide used for turbine blades, turbine disks of aircraft engines which work up to 1050°C. These elements are generally produced by the investment casting method. Turbine blades produced by conventional precision casting methods have coarse and inhomogeneous grain structure. Such a material often does not fulfil basic requirements, which concern mechanical properties for the stuff used in aeronautical engineering. The incorporation of controlled grain size improved mechanical properties. This control of grain size in the casting operation was accomplished by the control of processing parameters such as casting temperature, mould preheating temperature, and the use of grain nucleates in the face of the mould. For nickel and cobalt based superalloys, it was found that cobalt aluminate (CoAl2O4) has the best nucleating effect. The objective of this work was to determine the influence of the inoculant’s content (cobalt aluminate) in the surface layer of the ceramic mould on the microstructure and mechanical properties at high temperature of nickel based superalloy René 77. For this purpose, the ceramic moulds were made with different concentration of cobalt aluminate in the primary slurry was from 0 to 10% mass. in zirconium flour. Stepped and cylindrical samples were casted for microstructure and mechanical examinations. The average grain size of the matrix ( phase), was determined on the stepped samples. The influence of surface modification on the grain size of up to section thickness was considered. The microstructure investigations with the use of light microscopy and scanning electron microscopy (SEM) enable to examine the influence of the surface modification on the morphology of ’ phase and carbides precipitations. Verification of the influence of CoAl2O4 on the mechanical properties of castings were investigated on the basis of results obtained form creep tests.


Author(s):  
Xian Shi ◽  
Shu Jiang ◽  
Liu Yang ◽  
Mingming Tang ◽  
Dianshi Xiao
Keyword(s):  

Author(s):  
Ripon Hore ◽  
Sudipta Chakraborty ◽  
Ayaz Mahmud Shuvon ◽  
Md. Fayjul Bari ◽  
Mehedi A. Ansary

2021 ◽  
Vol 11 (15) ◽  
pp. 6736
Author(s):  
Ong Heo ◽  
Yeowon Yoon ◽  
Jinung Do

When underground space requires excavation in areas below the water table, the foundation system suffers from buoyancy, which leads to the uplifting of the superstructure. A deep foundation system can be used; however, in cases where a hard layer is encountered, high driving forces and corresponding noises cause civil complaints in urban areas. Micropiles can be an effective alternative option, due to their high performance despite a short installation depth. Pressurized grouting is used with a packer to induce higher interfacial properties between micropile and soil. In this study, the field performance of micropiles installed using gravitational grouting or pressure-grouted using either a geotextile packer or rubber packer was comparatively evaluated by tension and creep tests. Micropiles were installed using pressure grouting in weak and fractured zones. As results, the pressure-grouted micropiles showed more stable and stronger behaviors than ones installed using the gravitational grouting. Moreover, the pressure-grouted micropile installed using the rubber packer showed better performance than the one using the geotextile packer.


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