粒化高炉矿渣-氧化镁固化连云港软土的力学特性试验

为研究粒化高炉矿渣-氧化镁对连云港软土固化体力学特性的影响规律,采用粒化高炉矿渣-氧化镁(GBM)对连云港地区软土进行固化处理,并与相同添加量的普通硅酸盐水泥(OPC)固化土作对比。采用抗压强度试验和渗透试验,探讨了GBM对软土固化体力学特性的影响规律,并结合压汞试验(MIP)和扫描电镜试验(SEM)分析了GBM-软土相互作用的内在机理。结果表明:GBM和OPC均会提高软土固化体的力学特性,但相同添加量的GBM固化土的抗压强度大于OPC固化土,且相同添加量的GBM固化土的渗透系数和含水率均低于OPC固化土。压汞试验结果表明:相同添加量的GBM固化土的孔隙体积低于OPC固化土,且OPC主要改变了固化土中孔径1μm孔隙体积,而GBM主要改变了固化土中孔径0.1μm孔隙体积。扫描电镜试验结果表明:相同添加量的GBM固化土的土颗粒团聚和胶结程度均高于OPC固化土。孔隙分布、土颗粒团聚和胶结程度的差异是GBM固化土力学特性优于OPC固化土的本质原因。     

复杂土质库盆填筑料室内标准试验探究

江苏句容抽水蓄能电站工程上水库库盆填筑料方量较大、料源种类繁多，为加快施工进度，合理取得现场控制指标及指导现场施工，对各类土料进行颗粒试验，依据每种土料的性质进行分析，取得较为合理的室内试验方法，为后期填筑质量控制提供依据。     

碎石桩法处理软土地基在公路工程中的应用

在软土地基进行工程建筑时，常常会遇到两方面的工程地质问题，即地基土的承载力不足和建筑物产生过大的沉降。特别是旧路改建工程，由于软土孔隙比大、渗透系数小、沉降稳定时间长、很容易造成新旧路堤的不均匀沉降，因此，需要采取相应的治理措施。从工程实际出发．较为系统地阐述了碎石桩法在公路工程中处理软土地基的加固机理、设计方法，并采用应力面积法对加固前后地基土的最终沉降量进行了计算，同时采用了砂井地基的固结理论着重分析了碎石桩法对软土地基渗透固结的影响。     

林地土壤渗透试验研究

林地土壤渗透系数和土壤非毛管孔隙度、容重呈线性相关,土壤物理性状中影响土壤渗透性的主要是非毛管孔隙;乔木林比灌木林更能提高深层土壤的渗透系数;造林整地大大降低表层土壤的渗透,易产生地表径流。水土保持林的营造应建立人工(乔木)—天然(灌丛)复合植被。     

5种抗性植物对湘潭尾矿不同改良方式的适应性研究

对湘潭尾矿不同处理下锰矿废弃地抗性植物生长状况、养分吸收和重金属毒害进行分析.结果表明:冬青卫矛生长最好,荷花玉兰、棕榈、海桐、小叶女贞次之;不同树苗高增长率表现出85%尾矿土+15%矿渣+复合肥处理>85%尾矿土+15%河沙+复合肥处理>100%尾矿土+复合肥处理>对照的相同规律;5种植物叶片中N的含量100%尾矿土+复合肥、85%尾矿土+15%矿渣+复合肥、85%尾矿土+15%河沙+复合肥3种处理明显高于对照,与100%尾矿土+复合肥处理相比,荷花玉兰、冬青卫矛和海桐在85%尾矿土+15%矿渣+复合肥和85%尾矿土+15%河沙+复合肥处理方式下,植物体的N含量较高;施肥降低了荷花玉兰、冬青卫矛、海桐、小叶女贞对M n的吸收;供试的5种植物对M n的富集率高于对Cd的富集率;棕榈对M n有富集作用,而对Cd表现出负富集的作用.     

击实试验与渗透试验在垃圾填埋场粘土衬里料场检测中的应用

某垃圾填埋场,由于场地内无自然的粘土防渗层,可做衬里的料场虽为粘土,但渗透系数满足不了小于1.0×10-7cm/s要求,可通过改造土的质量密度,减小土的渗透性来满足要求,击实试验与渗透试验是一种行之有效的检测方法,在此项检测中成功地进行了应用。     

湖南湘潭矿业废弃地土壤特性研究

对湖南湘潭锰矿废弃地的土壤基质特殊性和少量自然定居植物营养元素和重金属元素含量进行研究.结果表明:尾矿废弃地土壤以砂粉土为主,通气透水性能差,渗透系数小,易造成地面积水;矿渣废弃地渗透系数大,蓄水量少而蒸发失水强,抗旱力弱.2类废弃地土壤营养元素含量低,重金属元素锰、铜的含量高,毒害大.在自然定居的少量植物中,商陆和荩草为超积累植物.采用植物生物原位修复法改善极端生境条件,既经济又高效.     

针叶树材纵向气体渗透的三维流阻网络

气体在木材中的渗透是通过木材内的孔隙通道进行 ,而木材内的孔隙结构非常复杂 ,在纵向、径向、弦向的连接特性均不相同。以往关于针叶树材气体渗透的模型或理论 ,只考虑针叶树材内气体渗透通道在 1个或 2个方向上的连接。本文根据针叶树材管胞流阻和管胞在纵向、径向、弦向的连接特性 ,建立了一个描述针叶树材纵向气体渗透性的三维流阻网络 ,并运用重正化变换求解出流阻网络的流阻 ,计算了针叶树材气体纵向渗透系数。所得马尾松木材气体纵向渗透系数计算值与其测量结果进行比较 ,两者十分吻合 ,表明本文关于针叶树材气体纵向渗透三维流阻网络理论的科学性     

铁尾矿不同改良措施对苜蓿和紫穗槐生长的影响

以河北省迁安市铁尾矿为基质,通过苜蓿和紫穗槐盆栽试验,研究铁尾矿与无机肥、土壤、有机肥(猪粪)的不同基质配比在短期内对豆科植物苜蓿和紫穗槐生长的影响,旨在为铁尾矿土壤修复和植被恢复提供依据,结果表明:1%猪粪施肥处理下2种植物出苗率较高,分别为72%和52%,掺土处理效果整体好于施肥处理,当掺土25%时,苜蓿、紫穗槐出苗情况已大有改善,出苗率分别为86%、71%;掺土处理对紫穗槐、苜蓿的叶绿素和蛋白含量影响更显著,当掺土25%以上时,二者叶绿素含量显著增加,直至全土处理达到最大值(36.33mg/g、33.79mg/g);苜蓿在掺土量达到25%、紫穗槐在掺土量达到75%时,植物蛋白含量开始明显提升,分别为4.12%、4.52%;紫穗槐的平均株高(28.82cm)、生物量(9.35g)、根冠比(1.31%)等生长指标均高于苜蓿(15.70cm、8.14g、0.55%);掺土处理对2种植物各生长指标作用显著,其中25%掺土处理就开始有明显提升;1%猪粪促进植物生长;5%以上猪粪施用量抑制植物成活及生长;尾矿中添加土壤比补充肥料更有利于苜蓿、紫穗槐生长,但25%掺土和无机肥混合配比也能促进苜蓿和紫穗槐的生长。     

水泥-过磷酸钙复合材料固化铅污染土的浸出和力学特性

水泥是铅污染土固稳修复常用的固化剂,在修复重度铅污染土时效果较差。而过磷酸钙在稳定铅污染土方面具有溶出风险低、长期稳定性好和环境安全性高的优点。为了研究水泥-过磷酸钙复合材料固化后铅污染土的浸出和力学特性,采用水泥-过磷酸钙复合材料对铅污染土进行固化/稳定化处理,通过浸出试验、无侧限抗压强度试验和渗透试验对固化前后的铅污染土固化体进行浸出和力学特性变化特征对比分析,分别探讨了水泥和过磷酸钙添加量对固化土浸出和力学特性的影响规律。结果表明:水泥可显著改善铅污染土的强度和渗透特性,当水泥的添加量从5%增加到30%时,固化土的抗压强度从0.56 MPa增加到4.78 MPa;渗透系数从8.2×10-7cm/s减小到2.2×10-8cm/s。但水泥在固稳高浓度铅污染土效果较差,当水泥的添加量从5%增加到30%时,固化土的浸出浓度从56.3 mg/L减少到19.8 mg/L,固化土的浸出浓度远高于我国危险废弃物鉴别标准(GB/T 5085.3—2007)。过磷酸钙可显著降低污染土中铅的浸出特性,固化土的浸出浓度从43.5 mg/L减少到0.17mg/L;但过磷酸钙会降低固化土的力学性能。随着过磷酸钙添加量从1%增加到5%,固化土的抗压强度从1.17MPa降低到0.42 MPa;渗透系数从3.0×10-7cm/s增加到1.3×10-6cm/s。因此,在铅污染土实际工程中应根据实际的场地工况和修复目标,合理选择水泥和过磷酸钙的配比,保证修复后的铅污染土强度特性和浸出特性均满足修复标准。     

Thermal and Aeration Properties of Mor Layers in Finland

Thermal conductivity (K _T), air permeability (K _a) and relative diffusivity of oxygen (ratio of oxygen diffusion coefficient in the soil to the oxygen diffusion coefficient in free air, D/D ₀) were measured from undisturbed mor samples taken from low-fertility (CT) Scots pine (Pinus sylvestris L.) sites and medium-fertility (MT) Norway spruce (Picea abies (L.) Karst.) sites. K _T     

马尾松木材横向液体渗透性的研究

分析和讨论了影响马尾松木材横向液体渗透性及其各向异性的机理.对马尾松木材的径向液体渗透性和弦向液体渗透性进行了测量.结果表明,马尾松木材的径向液体渗透性大于弦向液体渗透性,并且,马尾松木材的径向液体渗透性和弦向液体渗透性都是从边材向心材逐渐减小,并随着含水率的下降而升高.其原因是径向液体流动的主要通道是木射线和水平树脂道,弦向主要是管胞壁和交叉场上的纹孔.     

Shear behaviour in numerical triaxial compression tests by 3D fluid-coupled DEM: a fundamental study on mechanisms of landslide initiation

Shear behaviour in triaxial compression tests was numerically examined by 3D fluid-coupled DEM in a fundamental study on the mechanisms of landslide initiation. Changes in pore-water pressure because of undrained compression were calculated by introducing a measurement sphere surrounding a ball which represented the soil particles. The pore-water pressure was assigned to the measurement sphere as the product of the changes in volumetric strain and modulus of compressibility of water, and resulting flow due to the pressure differences among neighbouring measurement spheres was given on the basis of Darcy’s law. Specimens for the numerical triaxial compression tests were prepared with wide ranges of initial void ratio by use of samples with three different grain-size distributions. In the loose specimens, positive pore-water pressure build-up and subsequent liquefaction were numerically reproduced. In contrast, in the dense specimens, negative pore-water pressure was observed, showing upgrade of soil structure. For the medium specimens, phase transformation, which is a typical characteristic of granular soils, was successfully reproduced. Although steady-state lines were found for each sample on a p_\textss^￠ - e₀ p_{\text{ss}}^{\prime } - e_{0} diagram, there was a gap at a specific initial void ratio. Although the angles of internal friction were inversely proportional to the initial void ratio in both the undrained and drained tests in the medium to dense specimens, the observed angles of internal friction were smaller than the particle-to-particle friction angle. This result may be attributable to the fact that the balls could not form the complicated soil structures created in reality by particles with complex shapes.     

Physico-chemical characteristics and heavy metal concentrations of copper mine wastes in Zambia:implications for pollution risk and restoration

Soil characterization is a vital activity to develop appropriate and effective restoration protocols for mine wastelands while insights into the total content of heavy metals in the soil is an important step in estimating the hazards that the metals may pose to the vital roles of soil in the ecosystem.This study addressed the following research questions:(1) To what extent do the physico-chemical characteristics vary between mine waste sediments and the nearby forest soil?(2) Are the concentrations of heavy metals high enough to be considered as toxic?and(3) Are heavy metals present in mine waste sediments potential sources of pollution?We hypothesized that the physicochemical characteristics of mine waste sediments are less favorably for plant establishment and growth while the concentrations of heavy metals are very high,thus restricting the success of revegetation of mine waste lands.Mine waste sediments were sampled following a diagonal transect across tailings dams,overburden dump sites and the local forest soil from the top layer(0-20 cm) using a closed auger.Samples were analyzed for arsenic,barium,lead,cadmium,cobalt,copper,chromium,nickel,vanadium,and zinc as well as for soil physico-chemical properties.The mine waste sediments were dominated by silt whilst the forest soil by sand particles,with significantly high bulk density in the former.Both the forest soil and overburden sediments were acidic than the alkaline tailings dam sediment.Total organic carbon and nitrogen contents were significantly low in mine wasteland substrates but the concentration of Ca and Mg were significantly higher in tailings dam substrate than the forest soil.The concentrations of available P,K and Na were similar across sites.The mean concentrations of heavy metals were significantly(p 0.01) higher in mine waste sediments than the forest soil;except for cadmium(p=0.213).The order of contamination by heavy metals on the tailings was CuCo Ba Ni As Zn Pb Cr V Cd,and that on the overburdens was Cu Co Ba Ni ZnCr Pb V As Cd.The pollution load index(PLI)was nearly twice higher for the tailings dam(8.97) than the overburden(5.84).The findings show that the copper mine wastes(the tailings dams and overburden waste rock sites)are highly contaminated by heavy metals;which,in turn,might pose serious hazards to human health and agricultural productivity.In addition,poor macro-nutrient availability,substrate compaction and soil acidity(particularly on overburden sites) coupled with toxic level of heavy metals would be the main challenges for successful phytostabilization of copper mine wastelands.     

Liquid penetration in different cells of two hardwood species

Two experimental techniques were used to test the water permeability of two Korean hardwood species: diffuse porous Populus tomentiglandulosa T. Lee (eunsasi poplar) and ring porous white oak, Quercus serrata Thunb (konara oak). The first technique measured the void volume filled at different moisture content (MC) levels. Samples were treated with water via a schedule of full-cell impregnation. A significant relation between MC and permeability (the fractional void volume) was found. A reduction in liquid permeability was observed at MC above the fiber saturation point (FSP), whereas the opposite result was observed at MC below FSP due to the effect of the voids available in the wood. However, the differences of increased permeability from MC level 20% to 0% were found satistically the same in either wood species. The second technique measured the speed of liquid penetration in vessels, fibers, and rays with no application of external pressure. In this method, liquid flow was captured via video and the penetration speed was measured. Vessels, fibers, and rays in poplar were found to be more permeable than those in oak. Different anatomical factors such as cell diameter, cell length, pit number, pit aperture area, and thickness of the pit membrane seemed to be responsible for the variation of liquid flow rate in different cells of the two hardwood species.     

Shear strengths of undisturbed and remolded soil under typical forests in Jinyun Mountain, Chongqing City, southwest China

To find the controlling measures in preventing soil and water loss from soil mechanics, according to the prescribed methods of soil engineering test regulations, shear strengths of undisturbed and remolded soils under five typical forests in Jinyun Mountain, Chongqing City were measured using the direct shear apparatus. Shear difference of both undisturbed and remolded soils was compared at the same vertical loading, under the condition of the same dry density and water content from the same forest land. The effect of roots (the finest roots) in soil-root composites (undisturbed soils) was analyzed. The results indicate that undisturbed soils have higher shear resistance and less shear displacement than remolded soils at the same vertical loading, when both soils have the same dry density and water content under the same vegetations. It has been shown that shear failure of undisturbed soils approximately indicate plastic failure, while shear failure of remolded soils is of the elastic nature. Shear strength of undisturbed soils has a positive correlation with root content, and relevant regression models about undisturbed soil were established from this. Translated from Transactions of the Chinese Society of Agricultural Engineering, 2006, 22(11): 6–9 [译自: 农业工程学报]     

季冻区湿地软土固结特性与固结压力相关性的试验研究

针对黑龙江省松嫩平原湿地软土的固结特性,进行压缩固结试验研究。研究表明,季冻区软土孔隙比大、含水率大、压缩性强,其物理力学性质和工程性质略优于珠江三角洲软土。随着固结压力的增大,压缩系数逐渐减小,压缩模量逐渐增大,团结压力大于200kPa时,压缩系数变化趋势逐渐变缓,固结系数随固结压力增大逐渐减小,其变化范围为1．71—7．11×10^-4cm^2／s,固结系数在固结压力超过400kPa时趋于稳定。其研究成果可为季冻区软土工程处理提供技术支持。     

Necromass in undisturbed and logged forests in the Brazilian Amazon

Necromass is an important stock of carbon in tropical forests. We estimated volume, density, and mass of fallen and standing necromass in undisturbed and selectively logged forests at Juruena, Mato Grosso, Brazil (10.48°S, 58.47°W). We also measured standing dead trees at the Tapajos National Forest, Para, Brazil (3.08°S, 54.94°W) complementing our earlier study there on fallen necromass. We compared forest that was selectively logged using reduced-impact logging methods and undisturbed forest. We estimated necromass density accounting for void volume for necromass greater than 10 cm diameter at Juruena for five decay classes that ranged from freshly fallen (class 1) to highly decayed material (class 5). Average necromass density adjusted for void space (±S.E.) was 0.71 (0.02), 0.69 (0.04), 0.60 (0.04), 0.59 (0.06), and 0.33 (0.05) Mg m⁻³ for classes 1 through 5, respectively. Small (2–5 cm) and medium (5–10 cm) size classes had densities of 0.52 (0.02) and 0.50 (0.04) Mg m⁻³, respectively. The average dry mass (±S.E.) of fallen necromass at Juruena was 44.9 (0.2) and 67.0 (10.1) Mg ha⁻¹ for duplicate undisturbed and reduced impact logging sites, respectively. Small and medium sized material together accounted for 12–21% of the total fallen necromass at Juruena. At Juruena, the average mass of standing dead was 5.3 (1.0) Mg ha⁻¹ for undisturbed forest and 8.8 (2.3) Mg ha⁻¹ for forest logged with reduced impact methods. At Tapajos, standing dead average mass was 7.7 (2.0) Mg ha⁻¹ for undisturbed forest and 12.9 (4.6) Mg ha⁻¹ for logged forest. The proportion of standing dead to total fallen necromass was 12–17%. Even with reduced impact harvest management, logged forests had approximately 50% more total necromass than undisturbed forests.     

湘中丘陵区两类林分生产力与土壤肥力的比较研究

以湘中丘陵区石栎马尾松混交林和马尾松纯林为研究对象,对两类林分进行了生物量和封理化性质的测定分析,结果表明:混交林林分生物量远高于马尾松纯林,是纯林的2.99倍;混交林乔木层生物量也高于纯林;混交林林分平均净生产力高于纯林,是纯林的3.62倍;混交林和纯林的根系总质量分别占林分生物量的9.76%和11.08%.在各级根中,两类林分均以粗根所占比例最大,细根所占比例最小,根系质量均随深度的增加而递减;混交林枝叶比略小于纯林,而枝叶指数、冠根比及光合部分与非光合部分比值则相反;混交林土壤营养元素含量显著高于马尾松纯林,但混交林土壤容重比纯林低,总孔隙度与毛管孔隙度、非毛管孔隙度比纯林林地高,本研究结果,为湘中丘陵区石栎马尾松混交林及马尾松纯林的培育提供了重要参考依据。