烧结法赤泥洗涤中的二次反应及全沉降槽洗涤流程的探讨

通过对烧结法赤泥分离洗涤过程中二次反应及其影响因素的研究，指出：（１）即便是对活性较大的α－２ＣａＯ·ＳｉＯ２，也存在“安全区”这一概念，构成“安全区”的主要参数是赤泥浆的液固分离时间和溶液中的Ｎａ２ＯＴ浓度；（２）在沉降槽大型化的发展趋势中，应充分考虑到烧结法赤泥的物理化学特性。以此为依据对中州铝厂一期试生产两年一直不稳定的赤泥洗涤流程进行了改造，获得成功，并取得了显著的经济效益。

河流泥沙颗粒的全静态沉降分析技术

根据泥沙颗粒分析的特殊性与浑匀沉降消光分析的现状，提出全静态沉降分析技术的概念，并简要介绍据此技术设计制造的ＤＬＹ９５ 光电颗粒分析仪及其性能。

基于FBG传感技术的软基全断面沉降传感器研发

针对目前我国高速公路软土地基施工沉降监测中量测仪器自动化程度低、数据传输滞后、测量误差大等问题,利用光纤光栅传感技术,采用梁弯曲理论和差分算法,研究开发了一种监测软基沉降变形的光纤光栅传感器,该新型传感器的特点是可以监测软基整个横断面的沉降变形。通过室内模型试验结果表明,新型光纤光栅软基全断面沉降传感器的量测结果与实际变形吻合较好,验证了该新型全断面沉降传感器的可行性。该新型传感器与无线网络相结合,可以实现对软基整个横断面内的沉降变形进行实时远程在线监控,为软基施工安全监测提供了一种新方法。

高水玻璃含量全尾砂絮凝沉降试验研究

受矿山选矿分散剂水玻璃影响,单独使用有机絮凝剂难以实现细尾砂颗粒沉淀,导致选厂回水使用困难。基于无机絮凝剂压缩双电层作用开展了无机-有机絮凝剂配合使用试验。试验结果表明:高分子量的非离子絮凝剂在沉降速度、固体通量和底流浓度方面更有优势;已被中和的带负电的胶体粒子在聚合氯化铝(PAC)掺量不断增加时重新吸附而带正电,颗粒间排斥力变大,表现出尾砂絮团沉降速率随PAC增加而降低;推荐全尾砂最佳絮凝沉降条件为:尾砂给料质量浓度15%~17.5%,2;非离子絮凝剂掺量50 g/t,PAC掺量6 kg/t,此时对应固体通量为1.77~2.24 t/(m^(2)·h)。

基于响应面法的某矿全尾砂絮凝沉降参数优化

为对某矿山全尾砂絮凝沉降参数进行优化,提出利用BBD响应面法确定其最优参数。实验结果表明:供砂溶度对絮凝沉降速度影响最大,其次为絮凝剂添加浓度,絮凝剂单耗对全尾砂絮凝沉降速度影响不大。根据某矿山实际情况得出的最佳全尾砂絮凝沉降参数为供砂浓度16.28%,絮凝剂单耗为8.22 g/t,絮凝剂添加浓度0.12%,按照此方案得到的沉降速度为409.46 cm/h,与理论值429.937 cm/h的误差为5%,利用响应面法优化得到全尾砂絮凝沉降参数具有一定的可靠性,能够为矿山全尾砂絮凝沉降参数进行优化提供理论依据。

九寨沟大气氮、磷和硫沉降的通量及水环境意义

为了解九寨沟大气氮、磷和硫沉降的现状及对水体景观的潜在影响,于2010—2011年在长海监测了干湿沉降,于2011—2012年度在日则和沟口监测了全沉降。长海和沟口位于旅游线上,而日则为背景点。结果显示,长海SO2-4的年通量为8.67 kg S/hm2,总无机氮(TIN)的年通量为3.04 kg N/hm2,都主要来自人为源。在总氮(TN)、总溶解性氮(TDN)、总磷(TP)和总溶解性磷(TDP)的全沉降方面,沟口和日则具有类似的特征,反映这两点的TN、TDN、TP和TDP全沉降主要受区域环境的影响,受当地旅游活动的影响相对较小。结合相关文献,发现氮沉降可能已超过九寨沟水体养分氮沉降临界值,湿沉降的TIN含量都超过我国自然保护区地表水环境TN的标准;过量硫沉降偶尔导致酸雨,威胁景观钙华的健康。为制定九寨沟的相关保护措施,今后有必要深入量化氮和硫沉降的来源及对水环境的影响程度。

基于修正Peck法的隧道施工全地层变形规律研究

研究隧道施工引起上覆不同深度处的地层沉降变形对分析城市地铁隧道施工对邻近建(构)物的影响意义重大.考虑隧道施工地层扰动变形由下向上逐渐变形的特点,基于Peck法的沉降槽宽度与随机介质理论中地表影响半径关系,由下向上逐步分析隧道上覆各埋深地层的沉降变形;考虑各地层土性质、厚度和隧道半径对沉降槽宽度造成的影响,求得沉降槽宽度在地层各深度处的表达式;讨论了隧道上覆地层土性参数、成层土厚度和隧道开挖半径对地层沉降变形的影响,分析表明:地层的沉降槽宽度主要取决于该地层与隧道开挖面之间的覆土性质和厚度,与隧道半径也有很大关系;地层土的性质、厚度和隧道半径决定了地层的沉降范围,而地层损失决定了地层沉降量大小.隧道半径越大,沉降槽宽度越大;覆土的内摩擦角越小,沉降槽的宽度越小,地层沉降曲线越窄.

泥质软岩弃渣填筑路堤沉降分析

为确定泥质软岩弃渣路堤沉降特性,结合施工案例进行监测分析、制定监测方案、布置测点对路堤施工各个阶段的沉降速率、全断面变形进行监测。分析监测结果,得出路堤底部在填筑施工阶段沉降量较大,路堤中部和上部在稳定阶段沉降量较大,但完工阶段沉降量较小,说明路基结构稳定,施工质量满足要求。

重庆市汞污染的观测研究

为研究重庆市区汞污染状况，2004年9～11月，同步观测了重庆市近郊铁山坪小流域（TSP）和观音桥（GYQ）两个区域的全沉降、穿透水、地表径流和土壤中的总汞含量，估算了小流域中汞的输入输出通量，分析了城区和郊区的大气汞沉降和分布特征。结果表明，重庆已在一定程度上受到汞污染。在TSP，湿沉降是汞输入的主要方式，也就是说，在TSP，细颗粒是大气汞的主要来源，表层土则是大气汞的一个主要的汇。GYQ区域的汞污染比TSP相对严重。在GYQ，除了湿沉降以外，干沉降是汞来源的重要形式，表明在GYQ，粗颗粒可能对大气汞有很大的贡献。因此，本地源的排放对城区的影响比对郊区的影响大，尤其是城区火电站附近的土壤样品比郊区土壤的汞含量高很多，说明火电站是大气汞的重要来源之一。

Dynamic experiments on flocculation and sedimentation of argillized ultrafine tailings using fly-ash-based magnetic coagulant

In order to accelerate the sedimentation of super-large-scale argillized ultrafine tailings with bad features such as low settling velocity, muddy overflow water, and large flocculant dosage, a fly-ash-based magnetic coagulant （FAMC） was used in a dynamic experimental device. To obtain the best possible combination of the impact factors （magnetic intensity, FAMC dosage, flocculant dosage, and feed speed） for minimum overflow turbidity, a response surface methodology test coupled with a four-factor five-level central composite design was conducted. The synergy mechanism of FAMC and flocculant was analyzed based on the potential measurement and scanning electron microscopy. The results show that the flocculant dosage, overflow turbidity, and solid content can be reduced by 50%, 90%, and 80%, while the handling capacity per unit and efficiency of backfill and dry stacking can be promoted by 20%, 17%, and 13%, respectively, with a magnetic intensity of 0.3 T, FAMC dosage of 200 mL/t, flocculant dosage of 30 g/t, and feed speed of 0.6 t/（m^2·h）. Therefore, synergy of FAMC and flocculant has obvious efficiency in saving energy and protecting the environment by allowing 70×10^6 t/a of argillized ultrafine tailings slurry to be disposed safely and efficiently with a cost saving of more than 53×106 Yuan/a, which gives it great promise for use in domestic and foreign mines.

Settlement Prediction for Buildings Surrounding Foundation Pits Based on a Stationary Auto-regression Model

To ensure the safety of buildings surrounding foundation pits, a study was made on a settlement monitoring and trend prediction method. A statistical testing method for analyzing the stability of a settlement monitoring datum has been discussed. According to a comprehensive survey, data of 16 stages at operating control point, were verified by a standard t test to determine the stability of the operating control point. A stationary auto-regression model, AR(p), used for the observation point settlement prediction has been investigated. Given the 16 stages of the settlement data at an observation point, the applicability of this model was analyzed. Settlement of last four stages was predicted using the stationary auto-regression model AR (1); the maximum difference between predicted and measured values was 0.6 mm, indicating good prediction results of the model. Hence, this model can be applied to settlement predictions for buildings surrounding foundation pits.

Numerical study of flocculation settling and thickening of whole-tailings in deep cone thickener using CFD approach

Deep cone thickener (DCT) is the key equipment in cemented paste backfill (CPB), so it is essential to study the flocculation settling and thickening characteristics of the whole-tailings in DCT. Coupled with population balance model (PBM), computational fluid dynamics (CFD) was used to study the characteristics, namely particle size distribution (PSD) and underflow concentration in DCT. Based on actual production, the effects of rake rotational speed, feed rate and tailings slurry concentration were simulated and analyzed in a certain range. The PSD varied with rake rational speed, feed rate and tailings slurry concentration almost in the same trend, but the influence of feed rate was less than that of rake rational speed and tailings slurry concentration. The underflow concentration increased at first and then declined with rake rational speed and feed rate, but it rose and fell with the tailings slurry concentration. Finally, the optimal key parameters on the flocculation settling and thickening of the whole-tailings in DCT were obtained: rake rotational speed of 17 r/min, feed rate of 3.25 m^3/h and tailings slurry concentration of 20%, giving the reference values to the industrial production in Baishitamu Copper Mine.

Native woody legumes respond more negatively to extreme drought than invasive ones

Plant invasion potentially will be affected by increased extreme drought events and deposition of atmospheric N.However,results from previous research indicate that it is not clear as to how extreme drought,N deposition and their interaction affect alien plant invasion,in particular for the invasive woody legumes.We conducted a greenhouse experiment with three invasive and three native woody species of legumes(Fabaceae).We grew plants in extreme drought and in well-watered conditions combined with low and high levels of N and compared plant height,number of leaves and biomass production and allocation.Growth of native woody legumes was suppressed more by extreme drought than that of invasive woody legumes.Although an increase in soil N availability decreased the root mass fraction of plants of all species,it did not affect their overall performance.We found that invasive woody legumes can tolerate the adverse effects of the prolonged extreme drought better than native woody legumes.These results enhance our understanding of the effects of drought due to climate change on the invasion of alien woody legumes.

Neutral responses of plant community Ca concentration to nitrogen enrichment in a semiarid grassland

Calcium(Ca)is an essential nutrient for plant growth and Ca concentrations in forage have important implications for ruminant diet and health.It remains an open question whether forage Ca concentration would be decreased by increasing nitrogen(N)deposition.We manipulated the increasing rates of N addition(2008–2015)in a semiarid grassland,northern China.Plant Ca concentrations for all species were examined in each plot under N treatment.The Ca concentrations at functional group and community levels were calculated based on the concentration of each species presented and their relative biomass in each plot.We found that community-level Ca concentration remained stable across a gradient of wide-ranged N addition rates,although Ca concentration at both species and functional group levels showed negative responses to N enrichment.Given that forbs had higher Ca concentration than grasses,the increasing relative biomass of forbs canceled out the negative responses of species-level and functional group-level Ca concentration.Our results further showed that community Ca pool showed a positive but saturating response to N addition,with a threshold at the rate of 10 g N m^(−2)yr^(−1).Our findings highlight the role of changes in plant relative biomass in controlling the responses of forage Ca concentration and stock to N enrichment.

Safety threshold of high-speed railway pier settlement based on train-track-bridge dynamic interaction

This paper presents a method to determine the safety threshold of bridge pier settlement in high-speed railways.An analytical expression of the mapping relationship between the pier settlement and the rail deformation is derived theoretically for the double block ballastless track-bridge system.By adopting the superposition of the track random irregularity and the rail deformation caused by the pier settlement as the excitation inputs,the variations of vehicle dynamics indices with pier settlement are comparatively analyzed.Then,the safety threshold of the bridge pier settlement is obtained according to the limit of vehicle running safety and ride comfort indices of the high-speed trains.Results show that the dynamics indices of different trains have different sensitivities to the pier settlement,and the train CRH2C is the most sensitive one among all the types of Chinese high-speed trains.When passing through the bridges in common span with pier settlement at the speed of 250–350 km/h,the trains suffer the low-frequency excitations,and the vertical acceleration of car body is most sensitive to the pier settlement of all the dynamics indices.When the car body vertical acceleration just exceeds the allowable limit,the critical settlement value is 23.4 mm,which is much bigger than the pier differential settlement limit in the current code for Chinese high-speed railways.