The 1D normal compression line and structure permitted space of low–medium density chalk

2018 ◽  
Vol 8 (4) ◽  
pp. 298-304 ◽  
Author(s):  
F. J. Alvarez-Borges ◽  
B. N. Madhusudhan ◽  
D. J. Richards
Keyword(s):  
Medium Density ◽  
Compression Line ◽  
Normal Compression

scholarly journals Mechanical behaviour of Panzhihua iron tailings

2019 ◽  
Vol 56 (3) ◽  
pp. 420-435 ◽  
Author(s):  
W. Li ◽  
M.R. Coop
Keyword(s):  
High Risk ◽  
Rate Of Convergence ◽  
Mechanical Behaviour ◽  
Critical State ◽  
Preparation Method ◽  
Tailings Impoundment ◽  
Tailings Dams ◽  
Different Shapes ◽  
Compression Line ◽  
Normal Compression

Safety problems have concerned many researchers studying tailings dams in recent years, as they have a high risk of failure due to liquefaction. Existing analysis of liquefaction in tailings within a critical state framework has relied on the critical state line (CSL) being unique in the volumetric plane. However, recent advances have highlighted a so-called “transitional” behaviour in which the location of the normal compression line (NCL) and CSL is a function of the density of the soils at deposition. This paper presents a detailed investigation of the mechanics of tailings taken from three locations of an iron tailings impoundment. Reconstituted samples were prepared by different methods and at different densities. No transitional behaviour was found, although the results show that the rate of convergence of the compression curves changes, with the finest pond material reaching a unique NCL earliest. The preparation method was found not to have a large effect on the behaviour for these tailings. Unique CSLs could be clearly identified for all the three tailings, but with different shapes, giving rise to a changing susceptibility to liquefaction. This susceptibility tends to increase from the pond to the upper beach.

Some aspects of the compressibility behaviour of a clayey sand

2001 ◽  
Vol 38 (6) ◽  
pp. 1177-1186 ◽  
Author(s):  
Flavia Burmeister Martins ◽  
Luiz Antônio Bressani ◽  
Matthew Richard Coop ◽  
Adriano Virgilio Damiani Bica
Keyword(s):  
Published Data ◽  
Clayey Sand ◽  
One Dimensional ◽  
Sand Mixture ◽  
Oedometer Tests ◽  
Compression Line ◽  
Normal Compression

The intrinsic behaviour of a residual clayey sand derived from sandstone was investigated in one-dimensional compression. The data show some interesting differences when compared with other published data, in that no unique normal compression line can be identified. Although the compressibility on first loading is similar to that for many sandy materials at states on their normal compression lines, the locations of the compression curves were found to be a function of the initial voids ratio, and there was no convergence at higher stresses. Tests on a model clay-sand mixture indicated that this behaviour is common to gap-graded clayey sands.Key words: sands, compressibility, oedometer tests.

scholarly journals An elastic-viscous-plastic structured UH model

2021 ◽  
Vol 248 ◽  
pp. 01033
Author(s):  
Zhu Enyang ◽  
Wang Yihe
Keyword(s):  
Test Data ◽  
Soil Structure ◽  
Model Simulation ◽  
Time Effect ◽  
Plastic Strains ◽  
Time Effects ◽  
Hardening Model ◽  
Combined Actions ◽  
Compression Line ◽  
Normal Compression

On the basis of the structured unified hardening model (structured UH model) considering soil structured collapse, the time effect is take into account, and an elastic-viscous-plastic structured UH model is extended. In the presented model, the moving normal compression line (MNCL) is extended to a moving instant normal compression line (MINCL) for simulating both soil structure effect and time effect. Then the instance plastic strains irrespective of time effect are calculated by referring the MINCL, and the plastic strains due to time effect are calculated by referring the traditional instant normal compression line. Comparisons between test data and model simulation indicate that the presented elastic-viscous-plastic structured UH model is qualified to simulate the combined actions of soil structure and time effects both in compression and in shearing.

Metastable states of silty clays during drying

2002 ◽  
Vol 39 (4) ◽  
pp. 992-999 ◽  
Author(s):  
Francesco Cafaro
Keyword(s):  
Experimental Research ◽  
Soil Samples ◽  
Transmission Mechanism ◽  
Total Stress ◽  
Overconsolidated Clays ◽  
Stress Transmission ◽  
Drying Behaviour ◽  
Compression Line ◽  
Normal Compression ◽  
Desaturation Process

An experimental research program has been carried out on the drying behaviour of normally consolidated silty clays with the aim of observing and interpreting state paths followed by soil samples under suction increase at zero external total stress. The behaviour of overconsolidated clays during drying is also discussed for comparison and shows the influence of stress history on the desaturation process. The drying state paths of normally consolidated reconstituted clay samples are plotted together with the corresponding isotropic normal compression lines, assuming equivalence between suction and effective stress for a fully saturated soil. The importance of the stress transmission mechanism in explaining the observed offset between the virgin drying line and the normal compression line is pointed out. Moreover, an energy-based interpretation of this volumetric offset is proposed in terms of fabric metastability.Key words: desaturation, drying, fabric, matric suction, silty clays, volume change.

scholarly journals A single-stress model for the prediction of yielding of unsaturated cemented soils under isotropic loads

2020 ◽  
Vol 195 ◽  
pp. 02001
Author(s):  
Agostino Walter Bruno ◽  
Domenico Gallipoli ◽  
Mohamed Rouainia ◽  
Marti Lloret-Cabot
Keyword(s):  
Void Ratio ◽  
Surface Model ◽  
Partial Saturation ◽  
Good Ability ◽  
Proposed Model ◽  
Cemented Soils ◽  
Single Stress ◽  
Soil Behaviour ◽  
Compression Line ◽  
Normal Compression

This paper presents a bounding surface model predicting the combined effects of cementation and partial saturation on the mechanical behaviour of soils subjected to isotropic loading. The loss of cementation caused by loading, wetting or drying of a normally consolidated soil is described by a “cementation bonding function”. This states that, under virgin conditions, the ratio between cemented and uncemented void ratios monotonically decreases with increasing levels of scaled stress. The scaled stress is the variable governing the intrinsic behaviour of the soil under both saturated and unsaturated conditions. Combination of the cementation bounding function with a previously proposed model for unsaturated soil behaviour leads to the formulation of a “cemented unified normal compression line” (CUNCL). This describes the virgin behaviour of both cemented and uncemented soils under saturated and unsaturated conditions. Progressive yielding is modelled by assuming that the slope of the generic loading curve tends towards the slope of the CUNCL as the soil state moves from overconsolidated to virgin conditions. The model has been calibrated and validated against existing experimental data demonstrating a good ability to predict the void ratio of cemented soils during isotropic loading, unloading and wetting under both saturated and unsaturated conditions.

scholarly journals Calcium carbonate modified urea–formaldehyde resin adhesive for strength enhanced medium density fiberboard production

RSC Advances ◽  
2021 ◽  
Vol 11 (40) ◽  
pp. 25010-25017
Author(s):  
Li Lu ◽  
Yan Wang ◽  
Tianhua Li ◽  
Supeng Wang ◽  
Shoulu Yang ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Urea Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Medium Density ◽  
Ionic Bond ◽  
Resin Adhesive ◽  
Uf Resin ◽  
Modified Urea

Reactions between CaCO3 and CH2O2 during polycondensation of UF resin produce Ca2+. Ionic bond complexation binds Ca2+ with UF resin. The UF resin crystalline percentage decreases from 26.86% to 22.71%. IB strength of resin bonded fiberboard increases from 0.75 to 0.94 MPa.

Sign in / Sign up

Export Citation Format

Share Document