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41.
麦秸秆加筋盐渍土重型击实效果的影响因素分析 总被引:3,自引:0,他引:3
为解决因滨海盐渍土的盐胀和溶陷而引起土的强度降低问题,可采用麦秸秆加筋的方法处理盐渍土,以提高土的强度和抗变形能力。将盐渍土与一定长度和数量的防腐麦秸秆均匀拌和在一起,按照一定的碾压功将其碾压密实,此时土的含水率、麦秸秆的质量加筋率和加筋长度是影响加筋土重型击实效果的3个因素。试验结果揭示,(1)加筋土的最大干密度均小于盐渍土的,最优含水率变化不大。(2)与盐渍土一样,随着含水率的增加,加筋土的干密度先升后降。(3)随质量加筋率和加筋长度的增加,加筋土的最优含水率变化不明显,最大干密度持续下降,但降幅较小。(4)0.2%质量加筋率加筋土的干密度最大,0.3%质量加筋率的最小。(5)30 mm加筋长度加筋土的干密度最大,70 mm加筋长度的最小。建议按0.2%质量加筋率和30 mm加筋长度的防腐麦秸秆制备三轴压缩试样,以研究麦秸秆加筋滨海盐渍土的抗剪强度和应力-应变特性。 相似文献
42.
以强度增长率评价麦秸秆加筋盐渍土的加筋效果 总被引:1,自引:0,他引:1
采用麦秸秆与石灰共同加筋固化滨海盐渍土,可解决由于盐胀、溶陷和吸湿软化引起的土体强度下降问题。首先,制备盐渍土、石灰土、麦秸秆加筋盐渍土和麦秸秆加筋石灰土试样(整体均匀加筋、上部均匀加筋和下部均匀加筋);进而,进行? 50 mm试样、? 152 mm重型击实试样和? 102 mm轻型击实试样的无侧限抗压强度试验,以及? 61.8 mm试样三轴压缩试验;最后,分析抗压强度增长率、主应力差比值和黏聚力增长率的变化规律,以评价麦秸秆的加筋效果。结果表明:① 麦秸秆加筋增强了土的抗压强度和抗变形能力。② 麦秸秆加筋提高了土的黏聚力,在试样下部加筋,加筋效果更好。③ 加筋石灰土的强度由麦秸秆和石灰共同承担,加筋石灰土的浸水稳定性来源于石灰的固化作用。④ 低围压时,加筋对土的侧向变形约束较强;高围压时,加筋和围压共同限制土的侧向变形。采用麦秸秆加筋是滨海盐渍土的一种有效处理方法 相似文献
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44.
北京永定河(官厅-三家店)水体有毒有机污染物的致突变性研究 总被引:5,自引:0,他引:5
于1999年7月采样对北京西南永定河(官厅-三家店)水体进行了有毒有机物污染状的研究。水中有机物通过XAD-2树脂进行富集,沉积物样品经冷冻干燥和素氏提取后,用于Ames实验。结果表明,永定河已受到了相当程度的污染,但静止水体(水库大坝和三家店)未表现出致突变性,流动水体(八号桥和雁翅)具有较强的致突变性,最上游的八号桥点致突变性最强,沉积物样品的致突变性表现出几乎与此相反的规律,但除雁翅点样品对TA100菌株外,所有样品都表现出较强的致突变性。表明水库已成为污染物的储藏库并对下游造成二次污染,应引起有关部门的重视。 相似文献
45.
裂隙岩溶含水系统较为复杂,从水位动态和水化学组份难以判断孔隙水和地表水对其影响程度的主次性。本文通过水位和水化学组份的灰色关联度分析,结合水文地质特征,将二者对裂隙岩溶含水系统的影响程度的主次性进行量化比较,进一步验证了水文地质条件。 相似文献
46.
Characteristics of Non—Point Source Pollution in the Watershed of Miyun Reservoir,Beijing,China 总被引:1,自引:0,他引:1
Nitrogen and phosphorus are the major nutrients to cause eutrophication to degrade water quality of the Miyun Reservoir,a very important drinking water source of Bijing,China,and they are mainly from non-point sources.The watershed in Miyun County was selected as the study region with a totoal area of 1400km^2.Four typical monitoring catchments and two experimental units were used to monitor the precipitation,runoff,sediment yield and pollutant loading related to various land uses in the meantime.The results show that the total nutrient loss amounts of TN and TP are 898.07t/a,and 40.70t/a,respectively,in which nutrients N and P carried by runoff are 91.3% and 77.3%,respectively.There is relatively heavier soil eroson in the northern mountain area whereas the main nutrient loss occurs near the northeast edge of the reservoir.Different land uses would influence the loss amounts of non-point source pollutants.The amount of nutrient loss from the agricultural land per unit is highest,that from forestry comes next that from grassland is lowest.However,due to the variability of land use areas,agricultural land contributes a lot to TP and forestry lands to TN. 相似文献
47.
Nutrient Loss from Various Land-Use Areas in Shixia Small Watershed of Miyun County,Beijing China 总被引:1,自引:0,他引:1
In the Shixia small watershed,twenty experimental plots and two monitoring channels,the residential area and livestock areas were used to monitor the flow,runoff and erosion,Nitrogen and phosphorous concentrations associated with various land uses were analyzed at the same time.The results are presented as follows:(1)TP ,TN and COD concentrations of runoff samples in the residential area and livestock arease are nearly 10 times those in other land-use areas.High nutrient loads are associated with village land use,which is due to unsuitable livestock rising.These areas should be treated as the critical areas of non-point source pollution.(2)Different land use influences intensity the loss nutrients,especially slope tillings in agricultural land.The amount of nutrient loss from agricultural land per unit is highest,that from forestry is intermediated and that frompastures is lowest,However,in consideration of the variability of land-use areas,agricultural land contributes the greatest to TP and forestry land to TN.(3)The concentrations of TN and TP in sediments from gangues are highest ,those in forestry land are intermediate,and those in agricultural land are lowest.Nutrient loss from hilly areas in much greater than from mountainous areas. 相似文献
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49.
Diffuse pollution from livestock production in China 总被引:2,自引:0,他引:2
王晓燕 《中国地球化学学报》2005,24(2):189-193
With economic development and living standard improvement, livestock and poultry production has grown up rapidly, also has become the leading source of pollution in vast rural areas in China.The estimated annual loss amount of COD, BOD, NH3-N from manure in 2001 is 7.28 million ton, 4.99 million ton and 1.32 million ton, respectively. The COD loss amount from manure is close to the sum of COD from industrial and domestic wastewater. Because animal waste and wastewater can enter water bodies from spills or breaks of waste storage structures ( due to accidents or excessive rain) , and non-agricultural application of manure to cropland, this contamination has resulted in quality degradation of surface and underground drinking water supplies. Areas with concentrated livestock operations are showing elevated nutrients and organic pollutant contents in surface waters. This widespread contamination of water has prompted governments at various levels to adopt regulations and measures to control the spreading of livestock pollution. 相似文献
50.