大同盆地土壤盐渍化分布及演化特征

介绍了大同盆地的地理概况,分析了盐渍土对盆地的影响,结合土壤盐渍化的分级与分布情况,对土壤盐渍化分布的演化特征进行了分析,指出大同盆地大部分表层土壤为非盐化区和轻度盐化区,中强度盐化区及盐土区沿着桑干河流域分布,并且在过去40年中,盐渍化面积呈先增大后减小的趋势。     

Salinity effects on soil shrinkage characteristic curves of fine-grained geomaterials

Fine-grained clayey soils are prone to substantial volume changes during desiccation in response to the dynamics of their moisture regime, and are of critical importance in several geotechnical and geo- environmental engineering applications. As such, the complex interactions between the fraction of soil solids and the ionic pore fluid play a critical role in governing such volume changes, and have been the focus in studies dealing with marine geotechnology, mine-tailing ponds, engineered barrier systems, etc. With this in mind, the present investigation evaluates the volume changes and accompanying densification from a saturated slurry state to a constant volume state of a reference fine-grained geomaterial, kaolin, subjected to evaporative dewatering. For this purpose, several parametric studies involving determination of soil shrinkage characteristic curves (SSCCs) of kaolin under the influence of varied salt constituents and concentrations of pore fluid are performed. Furthermore, a critical assessment of SSCCs depicting progressive shrinkage and volume change behaviour of geomaterials is provided, followed by the analysis of experimentally obtained SSCCs of the kaolin to explore the impacts of pore fluid salinity. Moreover, the SSCCs are parameterised with a predictive model and the fitting parameters are used to quantitatively demonstrate the salinity-dependent volume change response of a representative fine-grained porous system.     

滨海新区土壤盐碱化垂向分布特征及其对工程建设的影响

土壤盐碱化是天津市滨海新区的主要地质环境问题之一。本文选取滨海新区北部汉沽盐田区、中部塘沽城建区、南部大港农业区为典型场地,首次从垂向开展土壤盐碱化分布特征研究。在此基础之上,对不同深度土壤盐碱化的工程腐蚀性进行定量分析。结果表明,滨海新区盐渍土在垂向上呈现出表聚性和随深度递减的规律：在盐田分布区,23m以浅为中盐渍土...     

天津滨海新区土壤盐渍化特征及其改良探讨

土壤盐渍化危害极大且难治理,严重制约着土地资源利用与生态环境建设。本文针对天津滨海新区土壤盐渍化问题,从含量、分布、类型、纵向变化等方面分析了土壤盐渍化特征,探究了土壤盐渍化改良措施,旨在为天津市滨海新区土地资源规划、利用提供科学依据。结果表明:区内表层盐渍化土壤及盐土广布,面积合计约1743.20 km~2;农用地表层盐渍化土壤及盐土合计约占全区农用地面积的52.94%;表层非盐渍化土壤以苏打型为主,轻度—重度盐渍化土壤以硫酸盐-氯化物型为主,盐土以氯化物型为主;春季土壤盐分剖面在坑塘水面、盐田、其他草地和裸土地等土地利用类型内主要表现为表聚型,在果园、水浇地和公园与绿地等土地利用类型内主要表现为底聚型;区内土壤盐渍化情况复杂,建议因地制宜,采取综合防治措施进行盐渍土改良。     

上海长江口地区土体含盐量分布调查

针对长江口土层孔隙水的平均盐度已远远高于淡水盐度范围的现象,通过试验,对长江口五类土层孔隙水平均盐度进行了测定,试验结果对长江口地区地下工程的设计有一定的参考价值。     

Enhancing anaerobic digestibility and phosphorus recovery of dairy manure through microwave-based thermochemical pretreatment

Anaerobic digestion and struvite precipitation are two effective ways of treating dairy manure for recovering biogas and phosphorus. Anaerobic digestion of dairy manure is commonly limited by slow fiber degradation, while struvite precipitation is limited by the availability of orthophosphate. The aim of this work is to study the possibility of using microwave-based thermochemical pretreatment to simultaneously enhance manure anaerobic digestibility (through fiber degradation) and struvite precipitation (through phosphorus solubilization). Microwave heating combined with different chemicals (NaOH, CaO, H₂SO₄, or HCl) enhanced solubilization of manure and degradation of glucan/xylan in dairy manure. However, sulfuric acid-based pretreatment resulted in a low anaerobic digestibility, probably due to the sulfur inhibition and Maillard side reaction. The pretreatments released 20-40% soluble phosphorus and 9-14% ammonium. However, CaO-based pretreatment resulted in lower orthophosphate releases and struvite precipitation efficiency as calcium interferes with phosphate to form calcium phosphate. Collectively, microwave heating combined with NaOH or HCl led to a high anaerobic digestibility and phosphorus recovery. Using these two chemicals, the performance of microwave- and conventional-heating in thermochemical pretreatment was further compared. The microwave heating resulted in a better performance in terms of COD solubilization, glucan/xylan reduction, phosphorus solubilization and anaerobic digestibility. Lastly, temperature and heating time used in microwave treatment were optimized. The optimal values of temperature and heating time were 147 °C and 25.3 min for methane production, and 135 °C and 26 min for orthophosphate release, respectively.     

Ecotoxicological assessment of doxycycline in aged pig manure using multispecies soil systems

This paper assesses the ecotoxicity of the antibiotic doxycycline in aged spiked pig manure using a multispecies soil system (MS 3) covering plants, earthworms and soil microorganisms. The study reproduced realistic exposure conditions, as well as higher exposure doses covering the uncertainty factors typically employed for covering interspecies variability. MS 3, consisting of columns of natural sieved soil assembled with earthworms and seeds from three plant species, were employed. Pig manure was spiked with doxycycline (75 or 7500 microg/ml), aged for 15 days under aerobic/anaerobic conditions and added on top of the soil columns (120 ml/column, equivalent to 220 kgN/ha). Water and doxycycline free manure were used as negative controls. Doxycycline (7500 microg/ml) solution was used as a positive control. No effects on plants or earthworms were observed. Significant effects on soil phosphatase activity, indicating effects on soil microorganisms, were observed at the highest exposure dose, affecting all soil layers in the doxycycline-solution-treated MS 3 (positive control) but only the top layer in the spiked pig manure system. Chemical analysis confirmed the different behavior of doxycycline in both systems (with and without manure) and those effects were observed in soil with measured concentrations over 1 mg/kg soil. The detection of doxycycline in leachates revealed a potential mobility. Leachate concentrations were similar for doxycycline solution and spiked manure treatments.     

非饱和黄土重力势、基质势和温度势探讨

0　前　　言 黄土地区路基、水利等工程项目大多处于浅层土体 ,浅层土体基本上是非饱和的 ,且大面积暴露于地表 ,由于受到太阳辐射、蒸发、降水等因素的影响 ,黄土中的温度和含水率均是变化的 ,温度的变化可促使水分迁移使含水率发生变化 ,含水率增大时不仅使黄土强度降低[1～ 5] ,而且加剧了冻融性 ,阴阳坡等边界条件差异可引起土体含水率不均匀变化 ,并可进一步引起变形差异 ,这些常常导致一系列病害的发生 ,为了保证工程安全 ,应对黄土含水率分布随外界因素的变化过程进行研究。土体含水率变化是土中水分迁移的结果 ,对暴露于地表的浅层一般黄土体而言 ,土体水分迁移的动力来源于水势梯度 ,水势主要包括重     

HFRPT整体形生物化粪池在排污工程中的应用

介绍了平煤郑州商务会馆工程室外HFRPT整体形生物化粪池的技术原理、工艺流程、特点,并阐述了室外施工安装的具体方法以及注意事项,分析了HFRPT整体形生物化粪池的经济效益和社会效益,应大力推广应用.     

预应力次应力的分析和应用

阐述了预应力结构中次应力的概念、产生机理及影响等,并结合工程实例说明了次应力的应用及次弯矩的有效利用,实践证明：合理的设计方案对于次应力的有效应用是相当关键的。     

Association of manganese effluent with the application of fertilizer and manure on tea field

Manganese (Mn) concentrations in the tea field effluent were 1.1-3.5 mg/l over a 2 year period from June 1997 to May 1998 (first water year) and June 1998 to May 1999 (second water year). The annual Mn loads were 38,000 g/ha in the first water year and 19,000 g/ha in the second. The highest Mn loads were observed, respectively, in July 1997 (10,000 g/ha) in the first water year and in June 1998 (4100 g/ha) in the second. The water-soluble Mn content of soil of the tea field increased abruptly with decreasing soil pH in the pH region below 4.5. The large Mn load from the tea field during the rainy season is likely due to application of excess fertilizer and manure before the rainy season, which may lead to acidification of the soil.     

土钉墙的设计及应用

结合具体的工程概况，探讨了具体的支护等级的确定，对土钉墙在高层建筑深基坑支护中的设计及应用作了详细的阐述，并对相应的锚固长度及其验算作了探讨。     

土钉墙的设计与应用

结合土钉墙的概念、特点及适用条件 ,就其作用原理、设计的一般原则和设计的方法作了介绍 ,同时为确保土钉支护方案的经济合理 ,提出了设计时应注意的几个问题。     

软土地基处理及其应用

结合珠江三角洲地区软土地基的特点，根据公路工程需要，介绍了软基监控的实施方案，阐述了真空预压及注浆法两种软土路基处理方法，总结了软土地基处理的有关经验。     

Investigation of the tetracycline, sulfonamide, and fluoroquinolone antimicrobial compounds in animal manure and agricultural soils in Turkey

Occurrence of antimicrobial residuals in the environment is of concern because of the emergence and development of antimicrobial-resistance in pathogen bacteria, and the ecotoxicological behaviour of these compounds. Investigation of antimicrobial pollution in animal manure has special importance since they constitute the major source for the dissemination of these chemicals into the environment. Hence, eight animal manure and nine agricultural soil samples from the North part of Marmara Region (Turkey) were collected and analyzed for two tetracyclines (TCs), four sulfonamides (SAs), and two fluoroquinolones (FQs). At least one antimicrobial compound was detected in all the agricultural soil and animal manure samples. The highest antimicrobial concentrations were in general detected in the fresh poultry manure samples. Mean recoveries from spiked soil and manure samples ranged from 60 to 86% and 62 to 77% for TCs, 69 to 101% and 14 to 82% for SAs, and 46 to 55% and 24 to 42% for FQs, respectively. Relationship between the recovery rates of the antimicrobial compounds and sample characteristics was statistically evaluated by means of hierarchical cluster analysis (HCA), and principal component analysis (PCA) followed by multiple stepwise regression (MSR). HCA showed agricultural soil samples with higher di- and trivalent metal contents resulted in higher TC and lower FQ recoveries. TC recoveries from manure were highest in the samples with lowest K, Mg, and Ca content, while FQs were more efficiently extracted from the manure samples with less % organic carbon (OC) content. The findings of HCA for TCs were supported by those of MSR analysis, giving comparable results. In addition, MSR of SA recoveries revealed that the increasing amounts of manure % OC led to lower recoveries.     

透明土及其在不同领域的新应用

结合透明土的研究现状,介绍了透明土的发展历程,从岩土工程性质、室内试验、实验设备与技术等方面,总结了其在不同领域的应用,有利于促进透明土技术的进一步发展。     

大跨度土质洞库复合土钉支护研究与应用

在试验研究和数值分析基础上，采用新型复合土钉支护技术对毛跨为10．5m，毛高为7．07m的土质洞库进行了成功设计与建造，提出了监测结果和结论。其新颖性在于，采用复合土钉支护大跨度土质洞库，去掉了二次永久衬砌，突破了传统洞库的建造方法，节省了笨重的机械设备和造价昂贵的多部台车，使施工便捷可行，为大跨度土质洞库建设提供了一种可供选用的新型支护方式。     

土层锚杆与土钉墙在山坡支护中的应用

结合具体工程，从工艺流程、施工要点、试验和成品保护几方面阐述了土层锚杆、土钉墙在山坡支护中的应用，说明该法在本地区有很好的应用价值。     

基于有限单元法的岩土材料本构二次开发及其应用

Duncan-Chang E-v模型因其参数概念清晰、物理意义简单等优点而广泛应用于各种土工问题的有限元分析中。本文为进一步解决有限元软件ABAQUS所提供的材料本构模型难以描述岩土介质非线性变形特征等问题,在先前工作的基础上,基于UMAT用户子程序二次开发平台,编制了Fortran接口程序,开发了Duncan-Chang E-v非线性弹性模型模块,并将该模型应用到高填石路堤施工沉降分析中。数值结果显示:由于应力不能及时扩散的缘故,在路堤填高一半、靠近外边坡的地方,出现了最大水平位移;竖向位移的大小受水平位移的大小影响,且大致出现在堤高(1/3～1/2)的位置;大主应力σ1的最大值和小主应力σ3的最大值均出现在堤底的最深处。     

土体电阻率测试的简化模型及应用

把土的导电组分分为孔隙水和土骨架,用计算模型对取自连云港地区的粘土电阻率进行了计算,并与实测结果相比较,验证了将该模型运用到土体电阻率计算中可以减少土体电阻率室内试验的工作量。