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Pre-compacted MX80 bentonite/Callovo-Oxfordian (COx) claystone mixture has been proposed to backfill and seal the underground galleries for radioactive waste disposal in France. While emplacing these pre-compacted blocks, technological voids are created between the blocks and the host rock and among the blocks themselves. It is expected that homogenization process will take place over time for the structure constructed with pre-compacted blocks upon hydration. This study investigated the boundary friction effect on such a process. Results showed that after the filling of technological voids, the soil far from the technological voids would swell further, while those near the voids would be compressed under the welling pressure generated by the soil behind, resulting in an increase in homogeneity in terms of dry density distribution. However, this homogenization process would stop after a certain time. Further examination showed that the homogenization process ended when the maximum boundary friction force became equal to or higher than the vector sum of swelling forces in the radial direction. Based on the force equilibrium and the mass conservation, the final dry density distribution was estimated. Comparison between the estimation and the measurement showed a good agreement, indicating the relevance of the identified mechanism related to boundary friction.
相似文献3.
Wei-min Ye Zi-yuan Qi Bao Chen Ji Xie Yu Huang Yao-ru Lu Yu-Jun Cui 《Environmental Earth Sciences》2011,64(1):269-276
Karst rocky desertification is a process of land degradation involving serious soil erosion, extensive exposure of basement
rocks. It leads to drastic decrease in soil productivity and formation of a desert-like landscape. In this regard, changes
in climatic conditions are the main origin of the soils degradation. Indeed, soils subjected to successive dry/wet cycling
processes caused by climate change develop swelling and shrinkage deformations which can modify their water retention properties,
thus inducing the degradation of soil–water capacity. The ecological characteristics of cultivation soils in karst areas,
Southwest of China, are extremely easy to be affected by external environmental factors due to its shallow bedding and low
vegetation coverage. Based on the analysis of the climate (precipitation) of this region during the past decades, an experimental
study has been conducted on a cultivated soil obtained from the typical karst area in southwestern China. Firstly, the soil–water
properties have been investigated. The measured soil–water retention curve shows that the air-entry value of the soil is between
50 and 60 kPa, while the residual saturation is about 12%. Based on the experimental results, three identifiable stages of
de-saturation have been defined. Secondly, a special apparatus was developed to investigate the volume change behavior of
the soil with controlled suction cycles. The vapor equilibrium technique was used for the suction control. The obtained results
show that under the effect of dry/wet cycles, (1) the void ratio of the cultivated soil is continuously decreasing, leading
to a gradual soil compaction. (2) The permeability decreases, giving rise to a deterioration of water transfer ability as
well as a deterioration of soil–water retention capacity. It is then obvious that the long-term dry/wet cycling process caused
by the climate change induce a continuously compaction and degradation of the cultivated soil in karst rocky desertification
areas. 相似文献
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Acta Geotechnica - The reclamation of land filled with high water content dredged clays is an important geological and geo-environmental issue. When designing such reclaimed land, the yield... 相似文献
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Acta Geotechnica - Compacted bentonite/sand mixtures are often considered as sealing/backfilling materials in deep geological disposal for radioactive waste. This study investigates the swelling... 相似文献
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Yu-Jun Zhang Xing-Bin Li Lin-Shan Song Ling Yuan Bao-Guan Chen Bing-Ru Chen Yu-Oi Wang Jing-Xin Sun 《Geostandards and Geoanalytical Research》1986,10(1):61-71
The concentrations of 36 elements in geochemical reference samples issued by the Ministry of Geology and Mineral Resources of China were determined by neutron activation analysis. Three main variants of the technique, instrumental, epithermal, and nreirradiation separation neutron activation analysis (INAA, ENAA, PNAA), were employed in a systematic study of the samples by three laboratories: the Institute of Atomic Energy of the Academia Sinica (INAA, ENAA), the Institute of High Energy Physics of the Academia Sinica (INAA), and the Institute of Geophysical and Geochemical Prosnecting of the Ministry of Geology and Mineral resources (INAA,PNAA). Both long and short irradiations and both Ge(Li) and HPGe detectors were used. A supplementary software nackage for data processing was developed. About 81% of the data determined by neutron activation agreed with recomended values with in 15%. 相似文献
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Valry Ferber Jean-Claude Auriol Yu-Jun Cui Jean-Pierre Magnan 《Engineering Geology》2009,104(3-4):200-210
We conducted a study of the spatial distributions of seismicity and earthquake hazard parameters for Turkey and the adjacent areas, applying the maximum likelihood method. The procedure allows for the use of either historical or instrumental data, or even a combination of the two. By using this method, we can estimate the earthquake hazard parameters, which include the maximum regional magnitude Mˆmax, the activity rate of seismic events and the well-known bˆ value, which is the slope of the frequency-magnitude Gutenberg-Richter relationship. These three parameters are determined simultaneously using an iterative scheme. The uncertainty in the determination of the magnitudes was also taken into consideration. The return periods (RP) of earthquakes with a magnitude M ≥ m are also evaluated. The whole examined area is divided into 24 seismic regions based on their seismotectonic regime. The homogeneity of the magnitudes is an essential factor in such studies. In order to achieve homogeneity of the magnitudes, formulas that convert any magnitude to an MS-surface scale are developed. New completeness cutoffs and their corresponding time intervals are also assessed for each of the 24 seismic regions. Each of the obtained parameters is distributed into its respective seismic region, allowing for an analysis of the localized seismicity parameters and a representation of their regional variation on a map. The earthquake hazard level is also calculated as a function of the form Θ = (Mˆmax,RP6.0), and a relative hazard scale (defined as the index K) is defined for each seismic region. The investigated regions are then classified into five groups using these parameters. This classification is useful for theoretical and practical reasons and provides a picture of quantitative seismicity. An attempt is then made to relate these values to the local tectonics. 相似文献
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基于水环境保护的湿地公园规划探讨——以山东拥翠湖国家湿地公园为例 总被引：1，自引：1，他引：0
人口增长、经济发展和生活水平的提高导致对有限的水资源竞争和水冲突的增加,确保水资源的可持续利用是保障社会经济可持续发展的前提。水资源的可持续利用是建立在生态系统良好的基础上,湿地公园的建立是统一保护与利用水资源的有效方式之一。湿地公园内的水环境保护与湿地公园的长远发展息息相关。以山东拥翠湖国家湿地公园为例,探讨了水环境保护理念下的湿地公园规划方法及内容,包括水资源、水岸、栖息地的保护,以及合理利用湿地资源的方法。由于湿地水环境保护标准尚未确定,基于水环境保护前提下的湿地公园规划还需完善。 相似文献
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依据地震波速得到的上地幔温度和气象台站记录的地表温度为约束,结合地表热流和热导率观测数据,利用有限元方法计算了中国大陆及邻区岩石圈三维热结构.基于此温度结果和GPS观测得到的应变率数据,以滑动摩擦、脆性破裂和蠕变三种强度机制为约束,计算得到了中国大陆及邻区岩石圈三维流变结构.结果显示:弱强度和低等效黏滞性系数的下地壳在中国大陆及邻区普遍存在,并且下地壳的流变强度和等效黏滞性系数比上地壳和岩石圈地幔一般要低1~2个数量级;中国大陆范围内青藏高原存在着厚度最大、强度最低的下地壳;青藏高原的岩石圈强度和等效黏滞性系数比华北、华南和印度板块的都要低;岩石圈流变结构的横向分布特征与重力梯度带和地形过渡带比较一致. 相似文献
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煤炭资源开采以后,采空区上覆岩层的原始受力平衡状态受到破坏,依次发生冒落、断裂、弯曲等移动变形,最终涉及地表,形成采煤塌陷地。徐州九里湖湿地正是在采煤塌陷地的机理上发展起来的,其生态旅游的开发以恢复生态学理论为指导,开发对策由生态恢复、环境教育和科研监测三方面构筑,包括人工干预粉煤灰堆填区生态修复、人工恢复湿地植物和水禽栖息地、沟通内外水系实现水循环、人工湿地净化水体改善水质、水岸驳岸去园林化生态处理、采煤塌陷地环境解说、湿地科普宣教活动和科研监测与国际学术交流等。 相似文献