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According to the interaction of three shallow tunnels with large section, the analytical solution to rock pressure has been derived and discussed. The load model is given when the bilateral tunnels are excavated. According to the model, the stresses of three tunnels and single tunnel are calculated and compared to analyze the distribution characteristics, where the stresses are influenced by controlling factors of clear distance, covering depth and inclination angle of ground surface. The results show that, in general, the bias distribution is more serious. Therefore, it is significant to settle down the load model of three shallow tunnels so as to determine the measure of reinforcement and design the structure of support. The model and results can be used as a theoretical basis in designation and further research of the three shallow tunnels. 相似文献
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用无皂乳液聚合及种子聚合方法制备了Fe3O4@P(MMA-DVB-GMA)复合微球,用乙二胺对微球开环后制备得到了表面带氨基的磁性微球,用透射电镜(TEM)、热失重分析(TGA)对其进行了表征,并考察了其对染料KN-R的吸附性能。结果表明,制备的磁性微球粒径在150nm左右,大小均一,具备明显的核壳结构,磁含量为8wt%,在磁场作用下能够快速分离出来。该吸附剂在150min内达到吸附平衡,能够有效去除染料KNR,在4~9范围内pH对吸附剂吸附容量影响较小。 相似文献
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On the basis of upper bound theorem, non-associated flow rule and non-linear failure criterion were considered together.The modified shear strength parameters of materials were obtained with the help of the tangent method. Employing the virtual power principle and strength reduction technique, the effects of dilatancy of materials, non-linear failure criterion, pore water pressure,surface loads and buried depth, on the stability of shallow tunnel were studied. In order to validate the effectiveness of the proposed approach, the solutions in the present work agree well with the existing results when the non-associated flow rule is reduced to the associated flow rule and the non-linear failure criterion is degenerated to the linear failure criterion. Compared with dilatancy of materials, the non-linear failure criterion exerts greater impact on the stability of shallow tunnels. The safety factor of shallow tunnels decreases and the failure surface expands outward when the dilatancy coefficient decreases. While the increase of nonlinear coefficient, the pore water pressure coefficient, the surface load and the buried depth results in the small safety factor. Therefore, the dilatancy as well as non-linear failure criterion should be taken into account in the design of shallow tunnel supporting structure. The supporting structure must be reinforced promptly to prevent potential mud from gushing or collapse accident in the areas with abundant pore water, large surface load or buried depth. 相似文献
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以1,3-丙二醇、四乙烯五胺、聚酰胺-胺为起始剂合成了直链型、支链型及枝状聚醚破乳剂,采用瓶试法测定了这些破乳剂对模拟压裂乳状液的破乳效果,考察了破乳剂类型及分子结构对破乳效果的影响。结果表明,支链聚醚破乳剂的破乳效果优于直链聚醚破乳剂,且支化程度增加对破乳有利;以3.0代枝状聚酰胺-胺为起始剂的聚醚破乳剂破乳效果最好,当环氧乙烷与环氧丙烷的质量比(m(EO)/m(PO))为1/3、起始剂质量分数为0.5%时,制备的枝状聚醚破乳剂对模拟压裂乳状液7min即可完全破乳。 相似文献
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针对近年频发的干旱情况不能准确及时监测评估的问题,该文以新疆为研究区域,基于温度植被干旱指数方法,利用2007年到2012年3月~8月MODIS合成产品数据获取归一化植被指数和陆地地表温度,构建LST-NDVI特征空间,得到全区的温度植被干旱指数和旱情等级空间分布图,分析了新疆干旱变化趋势,验证了温度植被干旱指数和降水因子的关系。结果表明:2007年~2012年新疆的干旱面积逐年趋于平稳,空间上表现为南疆旱情高于北疆,春季旱情高于夏季,降水量是影响温度植被干旱指数的重要因子。该研究为政府部门对新疆旱情严重地区治理提供了有效数据保证。 相似文献
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分析了依信息学确立的景观信息流在景观异质性制图的意义,及景观信息流的测度、特征和遥感与GIS对其获取的方法,探讨了景观信息流转换的表达方式。其次,把景观信息流反映在地学异质信息中,着重分析脆弱生态景观地学的异质性特征、响应以及利用GIS建立脆弱生态景观异质性制图的方法,对科尔沁沙地东南部的景观异质性特征作了分析。 相似文献
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