长短桩复合地基承载力发挥系数取值研究

根据水泥土长短桩复合地基试验结果,得到了考虑荷载水平的水泥土长短桩复合地基承载力计算公式。然后,考虑复合地基中桩体、桩间土和复合地基沉降量之间的相互关系,利用现场载荷试验成果,对单桩复合地基和长短桩复合地基的桩间土承载力发挥系数和合理的s/b取值范围进行了对比研究,得到了长短桩复合地基桩间土承载力发挥系数的计算方法。结果表明:长短桩复合地基桩体先于桩间土出现破坏,桩体极限荷载点对应的复合地基s/b值为s/b的上限;当垫层模量Ec为100M Pa时,长短桩复合地基s/b上限为0.0034,对应的桩间土承载力发挥系数为0.29。     

绵阳市代表性点位土壤多环芳烃剖面分布特征

通过挑选绵阳市有代表性的点位土壤柱,应用GC MS分析土壤柱垂直剖面中多环芳烃的含量水平,得出其垂直剖面分布特征。结果表明：5~20 cm深度中的PAHs含量最高,40 cm以下则含量锐减。由于表层（0～5 cm）土壤与大气之间的土气交换频繁,PAHs含量相对较低,而5~20 cm处土壤受到表层土壤的遮盖,PAHs富集较高,含量达到整个土壤柱最高值。多环芳烃总体垂直剖面分布特征表现出随深度增加含量减少的趋势。PAHs总含量以江油市点位(33024 ng/g)最高,其次是三台县点位(29989 ng/g),最低是游仙区点位(11274 ng/g)。研究区主要污染物为Nap、Phe和Chr/y。其中不同的土质、种植物都能影响PAHs的富集和迁移速率,导致含量在不同深度上产生变化。此外,参照有关环境质量标准,发现PAHs总量上江油市点位与三台县点位属于轻微污染、游仙区点位则属于无污染。     

Evaluation of environmental feasibility of steel pipe sheet pile cutoff wall at coastal landfill sites

An evaluation method that can express the local leakage of leachate from joint sections in steel pipe sheet pile (SPSP) cutoff walls is discussed in this study. In particular, the evaluation of environmental feasibility (containment of leachates containing toxic substances) considering a three-dimensional arrangement and hydraulic conductivity distribution of the joint sections in the SPSP cutoff wall is compared with an evaluation that uses the equivalent hydraulic conductivity. This equivalent hydraulic conductivity assumes that the joint section and the steel pipe are integrated; therefore, the hydraulic conductivity is substituted with a uniform permeable layer. However, in an evaluation that employs the equivalent hydraulic conductivity, it is difficult to consider the local leakage of leachate containing toxic substances from the joint sections in the SPSP cutoff wall. It was established that evaluations of the environmental feasibility of SPSP cutoff walls with joint sections must take into account the local leakage of leachates containing toxic substances from the joint sections. Also, it was clarified that technologies that lower the hydraulic conductivities of joint sections in SPSP cutoff walls and also facilitate the use of sparser joint arrangements contribute significantly to increasing the environmental feasibility of SPSP cutoff walls at landfill sites.     

吨量煤体的自燃过程实验模拟研究

为更好地弄清矿井实际的煤自然发火规律,利用装煤量达5吨的大型实验台对两种烟煤分别进行了自燃模拟实验。大煤量的实验能够很好地模拟煤矿中煤低温氧化和传热传质共同作用导致的发火过程,实验得到的自然发火期与煤矿实际发火期也是一致的。实验中煤样从缓慢氧化变为快速氧化的临界温度为100～110℃。当煤温低于,临界温度时,煤样的升温受到空气流带走热量和向外界散热的影响很大,因此夹层水的保温作用就很关键。当煤温超过临界温度后,反应加快,温度急剧上升,散热的影响明显降低,反应主要受限于氧气的供应情况。     

刚性桩复合地基的理论、实测与安全性研究

科学合理的设计理论是工程安全性和经济性的保障,现场监测是确保工程安全和质量最有效的手段。本文以提高刚性桩复合地基工程的安全性为目的,围绕关乎建筑物安全的“沉降量”等参数指标,从设计理论与试验监测两个方面开展研究。本文完善了刚性桩复合地基的设计理论,通过现场监测试验取得了第一手的数据资料,可作为今后类似工程的设计和施工参考。本研究为进一步提高刚性桩复合地基的安全性提供了理论和实践保障。     

立式加热炉节能减排可行性研究

大庆油田原稳装置采用立式加热炉,烟气中存在大量的废热。在现有装置运行中,烟气直接排放,浪费了大量的热量。通过在实验装置中可回收废热资源及废热回收技术研究,采用热管技术回收烟气废热,用于预热空气,不仅会节能降耗,给企业创造可观的经济效益,还会减少大气污染,创造良好的社会效益。     

EFFECTS OF COAL PILE RUNOFF ON STREAM QUALITY AND MACROINVERTEBRATE COMMUNITIES1

Samples of coal pile runoff, Georges Creek water, and macrobenthos above and below two coal storage areas along Georges Creek, Allegany County, Maryland, were collected in July, August, and September 1982, and February and July 1983. Coal pile runoff was collected under high- and low-flow conditions. Water samples were analyzed for Hg, Zn, As, Fe, Mn, Al, SO₄^?2, pH, filterable and non-filterable residue, conductivity and acidity. Leachate from coal piles along Georges Creek contained high concentrations of heavy metals, particularly manganese, aluminum and zinc. Iron and sulfate were very high and the pH ranged from 1.4 to 3.1. Georges Creek water had much lower concentrations of metals, iron and sulfate and a pH of about 7.0. The distribution of macrobenthos in Georges Creek showed the effects of both runoff from coal storage piles and periodic drought. Brillouin's diversity index values were low even in areas which did not dry. Densities of tubificid worms and chironomid larvae were very high above the coal storage areas where organic inputs were high. At all the rest of the sampling stations, macroinvertebrate densities were very low. Where coal pile runoff enters Georges Creek, it compounds the effects of periodic drought and further stresses the aquatic community.     

VARIABILITY IN THERMAL STRATIFICATION IN A RESERVOIR1

ABSTRACT: The thermal stratification characteristics of a flow-augmentation reservoir, Round Valley Reservoir, New Jersey, and attendant driving conditions were documented and analyzed for portions of three years. Substantial differences in the thermal stratification regime of the reservoir occurred in response to the documented changes in meteorological, operating, and light penetration conditions. The features of stratification that were affected included: the depth of the upper mixed layer, the average temperature of the epilimnion, the temperature gradient in the metalimnion, and the average temperature in the hypolimnion.     

Protozooplankton in the Deep Oligotrophic Traunsee (Austria) Influenced by Discharges of Soda and Salt Industries

Traunsee is a deep oligotrophic lake in Austria characterised by an artificial enrichment of chloride in the hypolimnion (up to 170 mg L^-1) caused by waste disposal of soda and salt industries. Protists were collected monthly over one year, observed alive and after Quantitative Protargol Staining (ciliates) or via epifluorescence microscopy (heterotrophic flagellates). Three sites within the lake (0–40 m depths) were compared to deeper water layers from 60–160 m depths where chloride concentrations and conductivity were increased. In addition, we observed the protozooplankton of two neighbouring lakes, i.e. reference systems, during one sampling occasion. In Traunsee the abundance of ciliates was low (200–36 600 cells L^-1) in contrast to high species diversity (at least 60 different species; H_S = 2.6) throughout the year. The main pelagic species in terms of abundance were small oligotrichs and prostomatids like Rimostrombidium brachykinetum/hyalinum, Balanion planctonicum and Urotricha spp. throughout the investigation period. Among free-living heterotrophic flagellates, which occurred at densities of 40–2800 cells mL^-1, small morphotypes dominated in the pelagial. No differences at the community level between the three lakes could be observed and pelagic ciliates and flagellates seemed not to be affected by increased chloride concentrations or by enhanced conductivity.     

DESIGN OF DESALTING PLANTS FOR CONJUNCTIVE OPERATION1

ABSTRACT The selection of an evaporator design must reflect the balancing of captial cost (primarily in heat exchanger surface and vessels) against operating cost (primarily steam cost) to achieve minimum cost. In a conjunctive plant the tendency is to select a low-capital cost, high-operating cost plant. In addition, it is advantageous to use a high-capacity plant which needs to be operated much less of the time than a plant which is sized just at the needed rate. For example, in the study of a possible system to satisfy a future increase of 450 MGD in water supply to New York Qty, a plant of 750 MGD capacity was selected as optimum. This plant, of the advanced VTE-MSF process type, would have a performance ratio of 9 lb product/1000 Btu as compared to 10-13 normally used for base-loaded plants. Steam would be supplied by a multi-unit dual-purpose nuclear power plant. The most economical type of energy supply would be “interruptible”; the steam would be used by a low pressure turbine to generate electricity during periods of peak electrical demand but would be available to the desalting plant at other times. The low pressure turbine would be available as spinning reserve during desalting plant operation. It is estimated that the desalting plant would have a load factor of 27 per cent over its life.