saturated hydraulic conductivity
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CATENA ◽  
2022 ◽  
Vol 210 ◽  
pp. 105891
Author(s):  
Zhuo Zeng ◽  
Jihong Xia ◽  
Shunan Dong ◽  
Wangwei Cai ◽  
Chuanbin Dou ◽  
...  

Minerals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 93
Author(s):  
Sada Haruna ◽  
Mamadou Fall

Recycling of tailings in the form of cemented paste backfill (CPB) is a widely adopted practice in the mining industry. Environmental performance is an important design criterion of CPB structures. This environmental performance of CPB is strongly influenced by its saturated hydraulic conductivity (permeability). Superplasticizers are usually added to improve flowability, but there is a limited understanding of their influence on the hydraulic properties of the CPB. This paper presents new experimental results on the variations of the hydraulic conductivity of CPB containing polycarboxylate-based superplasticizer with different compositions and curing conditions. It is found that the hydraulic conductivity of the CPB decreases with the addition of superplasticizer, which is beneficial to its environmental performance. The reduction is largely attributable to the influence of the ether-based superplasticizer on particles mobility and cement hydration. Moreover, both curing temperature and time have correlations with the hydraulic conductivity of CPB containing superplasticizer. In addition, the presence of sulfate and partial replacement of PCI with blast furnace slag reduces the hydraulic conductivity. The variations are mainly due to the changes in the pore structure of the CPB. The new results discussed in this manuscript will contribute to the design of more environmental-friendly CPBs, which is essential for sustainable mining.


Agronomy ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 133
Author(s):  
Ting Yang ◽  
Xuguang Xing ◽  
Yan Gao ◽  
Xiaoyi Ma

Applying soil amendments plays a critical role in relieving water stress in arid and semiarid areas. The natural clay mineral attapulgite (ATP) can be utilized to adjust the balance of water and soil environment. In this study, we investigated four different particle size distribution typical soils in the Loess Plateau: (1) lou soil (LS), (2) dark loessial soil (DS), (3) cultivated loess soil (CS), (4) sandy soil (SS). Five ATP application rates (0, 1%, 2%, 3%, and 4%) were selected to test the effect of ATP on the soil water retention curve, soil saturated hydraulic conductivity, and soil structure. The results showed that applied ATP significantly increased the soil clay content, and the relative change of SS with 3% ATP applied increased by 53.7%. The field water holding capacity of LS, DS, CS, and SS with 3% ATP applied increased by 8.9%, 9.6%, 18.2%, and 45.0%, respectively. Although applied ATP reduced the saturated hydraulic conductivity, the values of CS and SS were opposite when the amount of ATP applied was >3%. The relative change in the amount of 0.25–1 mm soil water-stable aggregates of SS was 155.9% when 3% ATP was applied. Applied ATP can enhance soil water retention and soil stability, which may improve limited water use efficiency and relieve soil desiccation in arid and semiarid areas or similar hydrogeological areas.


2022 ◽  
Vol 9 ◽  
Author(s):  
Qingqing Zhang ◽  
Laigui Wang ◽  
Huabin Zhang

In order to analyze the effects of rainfall events on the stability of an open-pit rock slope, with considering the spatial variability of saturated hydraulic conductivity, based on the unsaturated seepage theory and the random filed theory, modified functions of the unit saturation, the hydraulic conductivity (k), and the shear strength parameters are established for unsaturated slope, by using FISH and the non-intrusive stochastic method. A saturated-unsaturated seepage random field model is proposed. And then the impacts of the rainfall intensity, the rainfall duration, and the spatial variability of saturated hydraulic conductivity (ks) on the infiltration process and stability of the unsaturated rock slope are analyzed. The results show that the proposed model can estimate rainfall infiltration of rock slope accurately. Rainfall mainly affects the seepage field in the shallow layer of the slope, where a transient saturated zone can be formed. With the development of the rainfall duration, the weight of the rock mass increased, the matric suction reduced, the negative pore pressure, the degree of saturation, and the infiltration depth of the rock slope increased, and the water in the slope root connects with the initial water table gradually, the unsaturated zone shrinks, which causes the safety factor of the model decreases, but the trend of change slows down gradually. As the rainfall intensity strengthened, the infiltration depth increased and the safety factor of the slope reduced, while the changing rate increases first and then decreases. Increasing the correlation length of k can reduces the infiltration depth and safety factor of the slope. Increasing the variation coefficient of k will increase the infiltration depth, while the safety factor of the slope decreases. The infiltration depth and safety factor of the slope are most affected by rainfall duration, but its sensitivity to the variability coefficient of k will be strengthened when the rainfall intensity exceeds the infiltration capacity. This conclusion can provide reference significance for the risk estimation of slope geological hazards, which are induced by the rainfall infiltration.


2022 ◽  
Vol 42 (1) ◽  
Author(s):  
曾建辉,马波,郭迎香,张泽宇,李桂,李占斌,刘晨光 ZENG Jianhui

Geoderma ◽  
2022 ◽  
Vol 405 ◽  
pp. 115465
Author(s):  
Vincenzo Bagarello ◽  
Gaetano Caltabellotta ◽  
Massimo Iovino

CATENA ◽  
2022 ◽  
Vol 208 ◽  
pp. 105788
Author(s):  
Héctor Aguilera ◽  
Carolina Guardiola-Albert ◽  
Luis Moreno Merino ◽  
Carlos Baquedano ◽  
Elisabeth Díaz-Losada ◽  
...  

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 219
Author(s):  
Tian Chen ◽  
Mao Du ◽  
Qiangling Yao

Compacted bentonite is envisaged as engineering buffer/backfill material in geological disposal for high-level radioactive waste. In particular, Na-bentonite is characterised by lower hydraulic conductivity and higher swelling competence and cation exchange capacity, compared with other clays. A solid understanding of the hydraulic behaviour of compacted bentonite remains challenging because of the microstructure expansion of the pore system over the confined wetting path. This work proposed a novel theoretical method of pore system evolution of compacted bentonite based on its stacked microstructure, including the dynamic transfer from micro to macro porosity. Furthermore, the Kozeny–Carman equation was revised to evaluate the saturated hydraulic conductivity of compacted bentonite, taking into account microstructure effects on key hydraulic parameters such as porosity, specific surface area and tortuosity. The results show that the prediction of the revised Kozeny–Carman model falls within the acceptable range of experimental saturated hydraulic conductivity. A new constitutive relationship of relative hydraulic conductivity was also developed by considering both the pore network evolution and suction. The proposed constitutive relationship well reveals that unsaturated hydraulic conductivity undergoes a decrease controlled by microstructure evolution before an increase dominated by dropping the gradient of suction during the wetting path, leading to a U-shaped relationship. The predictive outcomes of the new constitutive relationship show an excellent match with laboratory observation of unsaturated hydraulic conductivity for GMZ and MX80 bentonite over the entire wetting path, while the traditional approach overestimates the hydraulic conductivity without consideration of the microstructure effect.


Agriculture ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1293
Author(s):  
Abdulaziz G. Alghamdi ◽  
Abdulrasoul Al-Omran ◽  
Arafat Alkhasha ◽  
Zafer Alasmary ◽  
Anwar A. Aly

Water management and irrigation conservation in calcareous sandy soil are of significant importance for sustaining agricultural production, especially in arid and semi-arid region that facing scarcity of water resources. The changes in hydro-physical characteristics of calcareous sand soil were investigated after date palm waste-derived biochar application in column trials. Significance of pyrolysis temperature (300 °C, 500 °C, and 700 °C), particle size [<0.5 mm (D0.5), 0.5–1 mm (D1), and 1–2 mm (D2)], and application rate (1%, 2.5%, and 5%) were studied. Variations in infiltration rate, intermittent evaporation, and saturated hydraulic conductivity as a function of aforementioned factors were investigated. After amending the top 10-cm soil layer with different biochar and application rates, the columns were subjected to six wetting and drying cycles by applying 25 cm3 tap water per week over a 6-week period. Overall, biochar application resulted in decreased saturated hydraulic conductivity, while improved cumulative evaporation. Specifically, biochar produced at 300 °C and 500 °C demonstrated 10.2% and 13.3% higher cumulative evaporation, respectively., whereas, biochar produced at 700 °C with 5% application rate resulted in decreased cumulative evaporation. Cumulative evaporation increased by 5.0%, 7.7% and, 7.8% for D0.5, D1 and D2 (mm) on average, respectively, as compared with the untreated soil. Thus, biochar with particle size 0.5–1 mm significantly improved hydro-physical properties when applied at 1%. Generally, using biochar produced at medium temperature and small particle size with appropriate application rates could improve the soil hydro-physical properties.


2021 ◽  
Vol 67 (No. 4) ◽  
pp. 199-207
Author(s):  
Václav Novák ◽  
Petr Šařec ◽  
Kateřina Křížová

To investigate the effects of organic matter activators combined with a pig slurry on a soil’s physical properties, a field experiment was carried out in a monoculture of corn (2015–2017). Three pig slurry application variants complemented with the activators in question, i.e. with PRP SOL spread directly on the soil surface (SOL), with Z’fix added to the slurry during the pig housing (ZF) and with a combination of both PRP SOL and Z’fix (ZF_SOL), were compared with just the pig slurry (C) under an equal dose of nitrogen and a uniform growing technology. According to the results, a positive effect of the penetration resistance with the pig slurry and the activators of organic matter (Z’fix and PRP SOL) was not proven. The saturated hydraulic conductivity was demonstrably better achieved with the Z’fix activator, but PRP SOL activator also provided a certain improvement. The largest change in the unit draught was observed in the ZF_SOL application (20% increase). The results seem ambiguous; however, they give a good indication of the activators’ effect in practice. Nevertheless, the findings would certainly benefit from further verification.


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