scholarly journals Mechanical Interpretation of Effects of Aeolian FineSands on Coal Fly Ash in Northern Shaanxi Province, China

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xin Wei ◽  
Chongyang Gao ◽  
Keyu Ai ◽  
Jun Zhao ◽  
Ling Xu
Keyword(s):  
Fly Ash ◽  
Critical State ◽  
Soil Mechanics ◽  
Coal Fly Ash ◽  
Shaanxi Province ◽  
Triaxial Tests ◽  
Severe Problem ◽  
Mechanical Behaviours ◽  
Northern Shaanxi ◽  
Mechanical Interpretation

The coal fly ash (CFA) is massively produced as a consequence of coal source residues in Northern Shaanxi Province, China. Since disposing the waste materials in mountainous gully widely distributed in the same area is one of the possibilities, the high compressibility and low strength of CFA become a severe problem for the stacking. The aeolian fine sands are close to Mu Us Desert, as the addition material was introduced to improve the mechanical behaviours of CFA. A series of oedometer and triaxial tests were performed on pure CFA, pure sands, and their mixtures containing 25%, 50%, and 80% of sands by weight, respectively. Test results were analyzed within the framework of critical state soil mechanics. With increasing sands content, normally consolidated lines (NCLs) and critical state lines (CSLs) of tested materials change in volume space as well as their compression or shearing paths. The mechanical parameters like C c , Г, λ decrease as a result of increasing sands content. On the contrary, the M and ∅ c s ' increase with augmenting sands content. It is concluded that the aeolian sands can significantly decrease the compressibility of the CFA and increase its shear strength. These findings would be useful for the treatment of CFA, which is significant for solving environmental problems in northern Shaanxi Province.

Effects of fines on liquefaction behaviour in well-graded materials

2017 ◽  
Vol 54 (10) ◽  
pp. 1460-1471 ◽  
Author(s):  
Katherine A. Kwa ◽  
David W. Airey
Keyword(s):  
Critical State ◽  
Soil Mechanics ◽  
State Parameter ◽  
Triaxial Tests ◽  
Particle Sizes ◽  
Graded Materials ◽  
Fines Content ◽  
Cyclic Resistance ◽  
Wide Range ◽  
Soil Behaviour

This study uses a critical state soil mechanics perspective to understand the mechanics behind the liquefaction of metallic ores during transport by ship. These metallic ores are transported at relatively low densities and have variable gradings containing a wide range of particle sizes and fines contents. The effect of the fines content on the location of the critical state line (CSL) and the cyclic liquefaction behaviour of well-graded materials was investigated by performing saturated, standard drained and undrained monotonic and compression-only cyclic triaxial tests. Samples were prepared at four different gradings containing particle sizes from 9.5 mm to 2 μm with fines (<75 μm) contents of 18%, 28%, 40%, and 60%. In the e versus log[Formula: see text] plane, where e is void ratio and [Formula: see text] is mean effective stress, the CSLs shifted upwards approximately parallel to one another as the fines content was increased. Transitional soil behaviour was observed in samples containing 28%, 40%, and 60% fines. A sample’s cyclic resistance to liquefaction depended on a combination of its density and state parameter, which were both related to the fines content. Samples with the same densities were more resistant to cyclic failure if they contained higher fines contents. The state parameter provided a useful prediction for general behavioural trends of all fines contents studied.

scholarly journals Observed and predicted behaviour of rail ballast under monotonic loading capturing particle breakage

2015 ◽  
Vol 52 (1) ◽  
pp. 73-86 ◽  
Author(s):  
Buddhima Indraratna ◽  
Qi Deng Sun ◽  
Sanjay Nimbalkar
Keyword(s):  
Critical State ◽  
Large Scale ◽  
Soil Mechanics ◽  
Confining Pressure ◽  
Particle Breakage ◽  
Shear Behaviour ◽  
Triaxial Tests ◽  
Triaxial Apparatus ◽  
Elastoplastic Constitutive Model ◽  
Constitutive Parameters

A substantial amount of experimental evidence suggests that the critical state envelope for ballast is nonlinear, especially at low confining pressure. To study the implications of this nonlinearity and the associated role of particle breakage, monotonically loaded drained triaxial tests were conducted using a large-scale cylindrical triaxial apparatus. A nonlinear critical state envelope is determined in the q–p′ and υ–lnp′ planes. Mathematical expressions for critical state stress ratio and specific volume are proposed to incorporate the evolution of particle breakage during monotonic shearing. In this paper, an elastoplastic constitutive model based on the critical state soil mechanics framework is presented to capture the salient aspects of stress–strain behaviour and degradation of ballast. Constitutive parameters were conveniently determined from large-scale laboratory tests. The model is able to predict the monotonic shear behaviour of ballast corroborating with the laboratory measurements. The proposed model is further validated using experimental results available from past independent studies.

UTILIZATION OF COAL FLY ASH FROM POWER PLANTS - I. ASH CHARACTERIZATION

2008 ◽  
Vol 7 (3) ◽  
pp. 289-293 ◽  
Author(s):  
Maria Harja ◽  
Marinela Barbuta ◽  
Lacramioara Rusu ◽  
Nicolae Apostolescu
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Coal Fly Ash

scholarly journals Estimating Changes in the Green Water Productivity of Cropping Systems in Northern Shaanxi Province in China’s Loess Plateau

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1198 ◽  
Author(s):  
Jinping Wang ◽  
Jinzhu Ma ◽  
Afton Clarke-Sather ◽  
Jiansheng Qu
Keyword(s):  
Loess Plateau ◽  
Hydrological Modeling ◽  
Meteorological Data ◽  
Water Productivity ◽  
Experimental Studies ◽  
Northern Region ◽  
Green Water ◽  
Shaanxi Province ◽  
Cropping Patterns ◽  
Northern Shaanxi

Water shortages limit agricultural production in the world’s arid and semi-arid regions. The Northern region of China’s Shaanxi Province, in the Loess Plateau, is a good example. Raising the water productivity of rainfed grain production in this region is essential to increase food production and reduce poverty, thereby improving food security. To support efforts to increase crop water productivity (CWP), we accounted for limitations of most existing studies (experimental studies of specific crops or hydrological modeling approaches) by using actual field data derived from statistical reports of cropping patterns. We estimated the CWPs of nine primary crops grown in four counties in Northern Shaanxi from 1994 to 2008 by combining statistics on the cultivated area and yields with detailed estimates of evapotranspiration based on daily meteorological data. We further calculated both the caloric CWP of water (CCWP) and the CWP of productive water (i.e., water used for transpiration). We found that regional CWP averaged 6.333 kg mm–1 ha–1, the CCWP was 17,683.81 cal mm–1 ha–1, the CWP of productive green water was 8.837 kg mm–1 ha–1, and the CCWP of productive green water was 24,769.07 cal mm–1 ha–1. Corn, sorghum, and buckwheat had the highest CWP, and although potatoes had the largest planted area and relatively high CWP, they had a low CCWP.

scholarly journals Coal Fly Ash and Polyacrylamide Influence Transport and Redistribution of Soil Nitrogen in a Sandy Sloping Land

Agriculture ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 47
Author(s):  
Kai Yang ◽  
Zejun Tang ◽  
Jianzhang Feng
Keyword(s):  
Fly Ash ◽  
Sandy Soil ◽  
Coal Fly Ash ◽  
Soil Layer ◽  
Nutrient Retention ◽  
Soil Surface ◽  
Rainfall Event ◽  
N Losses ◽  
N Concentration ◽  
Application Rates

Sandy soils are prone to nutrient losses, and consequently do not have as much as agricultural productivity as other soils. In this study, coal fly ash (CFA) and anionic polyacrylamide (PAM) granules were used as a sandy soil amendment. The two additives were incorporated to the sandy soil layer (depth of 0.2 m, slope gradient of 10°) at three CFA dosages and two PAM dosages. Urea was applied uniformly onto the low-nitrogen (N) soil surface prior to the simulated rainfall experiment (rainfall intensity of 1.5 mm/min). The results showed that compared with no addition of CFA and PAM, the addition of CFA and/or PAM caused some increases in the cumulative NO3−-N and NH4+-N losses with surface runoff; when the rainfall event ended, 15% CFA alone treatment and 0.01–0.02% PAM alone treatment resulted in small but significant increases in the cumulative runoff-associated NO3−-N concentration (p < 0.05), meanwhile 10% CFA + 0.01% PAM treatment and 15% CFA alone treatment resulted in nonsignificant small increases in the cumulative runoff-associated NH4+-N concentration (p > 0.05). After the rainfall event, both CFA and PAM alone treatments increased the concentrations of NO3−-N and NH4+-N retained in the sandy soil layer compared with the unamended soil. As the CFA and PAM co-application rates increased, the additive effect of CFA and PAM on improving the nutrient retention of sandy soil increased.

Sign in / Sign up

Export Citation Format

Share Document