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1.
《Ceramics International》2021,47(22):31319-31328
Manufacturing lightweight aggregate (LWA) at high temperature is an effective way to immobilize heavy metals in solid waste. This work investigated the performance and solidification mechanism of LWA prepared from copper contaminated soil. The volume expansion of LWA could reach a maximum of 28%, and its lowest density accounted of 1.5 g/cm3, which met the standard requirements. Optical microscope and micro-CT test illustrated that the addition of Cu leaded to obvious phase separation in LWA. The Cu leaching result of LWA first increased and then dropped with the temperature. The XRD test found that the main formation phase of Cu in LWA were t-CuFe2O4 and amorphous phase that they had different acid resistance ability. XPS revealed that the main cause of the agglomeration of liquid phase in LWA was the chain broken reaction between Cu and Si–O tetrahedron. SEM-EDS results showed that the distribution of Cu and Si had a strong correlation, which meant that Cu mostly formed amorphous phase. This work showed the uniqueness of Cu in the high temperature immobilization and pointed out the best immobilization target phase. 相似文献
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This paper is prepared in honour of Professor E.T. Brown for his outstanding contributions to rock mechanics and geotechnical engineering and also for his personal influence on the first author's research career in geomechanics and geotechnical engineering. As a result, we have picked a topic that reflects two key research areas in which Professor E.T. Brown has made seminal contributions over a long and distinguished career. These two areas are concerned with the application of the critical state concept to modelling geomaterials and the analysis of underground excavation or tunnelling in geomaterials.Partially due to Professor Brown's influence, the first author has also been conducting research in these two areas over many years. In particular, this paper aims to describe briefly the development of a unified critical state model for geomaterials together with an application to cavity contraction problems and tunnelling in soils. 相似文献
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《Geotextiles and Geomembranes》2021,49(5):1256-1269
This study investigates the seismic performance of geosynthetic-reinforced modular block retaining walls backfilled with cohesive, fine grained clay-sand soil mixture. Shaking table tests were performed for three ½ scaled (wall height 190 cm) and ¼ scaled model walls to investigate the effects of backfill type, the influence of reinforcement length and reinforcement stiffness effects. The El Centro and Kobe earthquake records of varying amplitudes were used as base acceleration. Displacement of the front wall, accelerations at different locations, strains on the reinforcements, and the visual observations of the facing and the backfill surface were used to evaluate the seismic performance of model walls. The model walls were subjected to rigorous shaking and the walls did not exhibit any stability problems or signs of impending failure. The maximum deformations observed on the models with cohesive backfill was less than half of the deformation of the sand model. The load transfers between the geogrid and cohesive soil was comparable to that of sand and hence the needed reinforcement length was similar as well. As a result; the model walls with cohesive backfills performed within acceptable limits under seismic loading conditions when compared with granular backfilled counterparts. 相似文献
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《岩石力学与岩土工程学报(英文版)》2020,12(3):630-641
Structure is an evident determinant for macroscopic behaviors of soils. However, this is not taken into account in most constitutive models, as structure is a rather complex issue in models. For this, it is important to develop and implement simple models that can reflect this important aspect of soil behavior. This paper tried to model structured soils based on well-established concepts, such as critical state and sub-loading. Critical state is the core of the classic Cam Clay model. The sub-loading concept implies adoption of an inner (sub-loading) yield surface, according to specific hardening rules for some internal strain-like state variables. Nakai and co-workers proposed such internal variables for controlling density (ρ) and structure (ω), using a modified stress space, called tij. Herein, similar variables are used in the context of the better-known invariants (p and q) of the Cam Clay model. This change requires explicit adoption of a non-associated flow rule for the sub-loading surface. This is accomplished by modifying the dilatancy ratio of the Cam Clay model, as a function of the new internal variables. These modifications are described and implemented under three-dimensional (3D) conditions. The model is then applied to simulating laboratory tests under different stress paths and the results are compared to experiments reported for different types of structured soils. The good agreements show the capacity and potential of the proposed model. 相似文献
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文章中主要采用有机溶剂萃取法(OSE)对高浓度石油污染土壤进行修复,经过精馏操作,有效回收原油,建立脱附等温曲线,研究了石油污染物在土壤-有机溶剂两相间的迁移规律。 相似文献
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