Current Issue : January - March Volume : 2021 Issue Number : 1 Articles : 5 Articles
Background. Soil contamination by hexavalent chromium is becoming a main environmental concern in China. This study\ndeveloped a sewage sludge biochar modified by FeSO4 (CHBC) as a new reductant for Cr(VI)-contaminated soil. The effectiveness\nof CHBC-stabilized Cr(VI)-contaminated soil was investigated. Methods. Typical industrial Cr(VI)-contaminated soil in China\nwas chosen as the medium. The total and Cr(VI) contents of the contaminated soil were 1014.6 and 973.5 mg/kg, respectively. The\neffectiveness of the Cr(VI)-contaminated soil stabilized by CHBC was investigated by the leaching test (US EPA method 1312), the\nsimplified bioaccessibility extraction test (US EPA 2007 protocol and British Geological Survey), alkaline digestion (US EPA\nmethod 3060A), sequential extraction (BCR sequential extraction procedure), X-ray diffraction, and the risk assessment code test.\nResults. Results show that CHBC substantially reduced the leachability and Cr(VI) content of the contaminated soil. The\nleachability and content of Cr(VI) were lower than the thresholds of the Environmental Quality Standards of Soil in China for civil\nreuse and the China Environmental Quality Standards of surface water for civil use when the soil was stabilized with 10%dosage of\nCHBC. Conclusion. CHBC is highly efficient in stabilizing Cr(VI) and can effectively reduce the leachability and bioavailability of\nCr in contaminated soil and thus feasible for stabilizing Cr(VI)-contaminated soil and shows potential for application in the field....
The fracture development and distribution around the deep soft rock roadway are pivotal to any underground design. In this\npaper, both field investigation and numerical simulation were taken to study the fracture evolution and rock deformation of a coal\nmine roadway at Kouzidong mine, Fuyang, Anhui Province, China. Based on the borehole imaging technique, we found an\nasymmetric distribution of the fracture zone in the surrounding rock of the roadway. By analyzing the C value of the fractures in\nthe borehole images,we found that the fracture interval distribution of the surrounding rock of the tunnel, the number of fractures\nwill fluctuate decrease with the increase of the depth. To effectively study the fracture propagation and distribution of the roadway\nunder longwall retreatment and roadway excavation, the global-local numerical technique was applied via FLAC3D and PFC2D.\nIn the roadway excavation process, fractures were first formed in the shallow section of the roadway and progressively propagated\ntoward the deeper soft rock layer; the main failure mechanism was a tensile failure. During longwall retreatment, fractures\ncontinuously developed toward the deeper soft rock layer. However, the failure mechanism transformed to shear failure. From\nnumerical results, it can be seen that the stress concentration at the ribs was released, which led to shear failure at the roof and\nfloor. Due to the extensive tensile cracks in the shallow section, the surrounding rock experienced expansion and fracture. The\ndeep shear failure also induced the formation of the nonadjacent crushing zone and elastic zone, which is in line with the borehole\nimaging results....
This paper proposes a numerical simulation of the mechanical behavior of a\nreinforced concrete pile foundation under an axial load. In fact, the foundation\nof a structure represents the essential structural part of it, because it ensures\nits bearing capacity.............................
The setting of pre assessment criteria for soil compaction is hardly determined,\nespecially, in case of undecided structure locations. Different design\nguidelines recommend achieving a specific value of relative density for the\ncompaction of fill placement works. Alternatives were discussed through the\nliterature to predict the value of relative density based on soil field tests (e.g.\ncone and standard penetration tests). This paper presents the weakness of\nusing the Over Consolidation Ratio (OCR) as guidance to assess the value of\ncone tip resistance using the soil relative density....
In the previous investigations of the vibroacoustic characteristics of a submerged cylindrical shell in a flow field, the fluid viscosity\nwas usually ignored. In this paper, the effect of fluid viscosity on the characteristics of vibration power flow in an infinite circular\ncylindrical shell immersed in a viscous acoustic medium is studied. Fl¨uggeâ??s thin shell theory for an isotropic, elastic, and thin\ncylindrical shell is employed to obtain the motion equations of the structure under circumferential-distributed line force. Together\nwith the wave equations for the viscous flow field as well as continuity conditions at the interface, the vibroacoustic equation of\nmotion in the coupled system is derived. Numerical analysis based on the additional-damping numerical integral method and tenpoint\nGaussian integral method is conducted to solve the vibroacoustic coupling equation with varying levels of viscosity. Then,\nthe variation of the input power flow against the nondimensional axial wave number in the coupled system with different\ncircumferential mode numbers is discussed in detail. It is found that the influence of fluid viscosity on the vibroacoustic coupled\nsystem is mainly concentrated in the low-frequency band, which is shown as the increase of the crest number and amplitude of the\ninput power flow curves....
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