地下洞室群自然通风网络计算机分析模型

依据自然通风网络稳定流动的物理规律和图论的相关理论，对热源形式作了简化，建立了约束气流温度参数的补充方程组，推导出其矩阵表达式；根据网络分支流量一温度参数的耦合特点，提出模型求解的一种数值计算方法，得到自然通风网络的计算机分析模型。     

地质灾害危险性综合评估——以广东省五华县为例

该文以遥感及GIS作为数据获取与分析处理的技术手段,以地质环境条件复杂程度,潜在地质灾害隐患点的分布、灾害点密度、灾害体规模、地质灾害危害程度等作为基本评价要素对五华县地质灾害危险性进行综合评估并分区,最终划定地质灾害危险程度高、中、低3个等级共12个亚区;即高危险区(ⅠA)有4个亚区,中危险区(ⅡB)有4个亚区,低危险区(ⅢC)有4个亚区。     

高层建筑边坡地质灾害危险性评估与防治

以湖南省长沙市通用国际社区南块地边坡项目建设场地为项目背景,综合项目建设场地的地质条件,采用定性—半定量的方法,对该边坡地质灾害的危险性进行了现状评估和预测,提出了相应的防治措施和施工建议。     

A new quantitative method for risk assessment of geological disasters in underground engineering: Attribute Interval Evaluation Theory (AIET)

A new quantitative method named Attribute Interval Evaluation Theory (AIET) is proposed for risk assessment of geological disasters in underground engineering in the present study. The AIET not only can quantitatively evaluate and prioritize risks by combining consequences and probability of occurrence, but also can make an analysis of the reliability of evaluation results. The values of evaluation indices are taken as intervals rather than unique values, which is more reasonable because of geotechnical complexity and uncertainty. A simple and practical software package is developed so that the risk assessment process which is subjected to a large number of calculations can be completed automatically in a few seconds. Engineering applications to different geological disasters and results comparison indicate that the AIET can be successful in evaluating and prioritizing risks in most cases. The confidence coefficient value has a big impact on the reliability of evaluation results. The reasonable confidence coefficient value for an evaluation result with a reliability index of no less than 80% is found to be in the range of 0.60–0.63, and its maximum value can reach 0.66 for most of the engineering practices.     

Lining structural monitoring in the new underground service of Naples (Italy)

A new underground stretch connecting two existing lines of the urban railway underground system was built in Naples. The tunnel was excavated by NATM through unsaturated pyroclastic silty sand at relatively large depths, ranging between thirty to eighty metres. The geometry of the section is rather typical with a top part shaped as half a circle and a rectangular bottom. The tunnel was conventionally built with a staged construction: after the full face excavation, a temporary lining composed by horse-shoe steel ribs and sprayed concrete was put in place. Two steel ribs, spaced about one hundred metres apart and located about sixty metres below the ground surface, were instrumented with twenty-four vibrating wire strain gauges, installed at six symmetric locations. Nearly two years of measurements were collected. In the paper the measured strains and the back-calculated internal forces are reported. The results of FE 3D and 2D back-analyses are also shown allowing to throw a light on the observed behaviour.     

Engineering geological mapping of heterogeneous rock masses in the Northern Apennines: an example from the Parma Valley (Italy)

Most of the geological formations in the Northern Apennines are made up of flysch and tectonic mélanges. A general characterization of the most common rock masses cropping out in the Val Parma is presented in this paper, using the Marinos–Hoek classification based on the Hoek–Brown criterion. Three groups were identified: heterogeneous rock masses essentially controlled by single discontinuities with strengths much lower than the main rock mass (HH); truly heterogeneous rock masses with approximately equal alternations of hard and weak horizons which fail through the weaker materials (TH) and a rock mass in which the majority of the material is weak, tending to soil-like behaviour (WH). A general engineering geological map of the study area is presented, highlighting the spatial distribution of the three different groups.     

基于Matlab的BP神经网络在泥石流危险性评价中的应用

由于泥石流孕育环境、成灾条件及其诱发因素等的随机性、不确定性和模糊性,决定了泥石流是一种非常复杂的非线性系统。人工神经网络因其具有较强的自组织性、自适应性和自学习能力等优势,更适合于解决非线性问题。本文基于Matlab程序建立了区域泥石流危险性评价的BP神经网络模型,并将该模型应用于凉山州德昌县22个乡镇的区域泥石流危险性评价中,取得了良好的应用效果,评价预测的准确率高达95%。该方法不仅解决了泥石流危险度评价因子和评价等级之间的复杂非线性关系,而且过程简单,结果不受人为因素的影响,是一种具有应用价值、有效的泥石流危险性评价方法。     

Environmental driving forces of urban growth and development: An emergy-based assessment of the city of Rome,Italy

Large urban systems can be considered as the final point of convergence of resources, environmental services and human activities from rural settlements to villages to towns to small and big cities. The emergy synthesis method is applied in order to capture the complexity of urban systems from the point of view of the larger scale, the geobiosphere, where resources come from. Emergy is the total available energy of one kind (usually solar) directly or indirectly used up to drive a system or a process. It can be considered as a measure of a system's demand for environmental support. The population of Rome is 4.43% of total Italian population, with an emergy use of about 4% of total emergy supporting the Italian economy. Emergy use per capita is 5.50E+16 seJ/year, compared to an average value for Italy of 3.60E+16 seJ/year. An empower density of 1.09E+14 seJ/m²/year was calculated for Rome, much higher than for average Italy, 6.86E+12 seJ/m²/year. Finally, the emergy/GDP, an indirect measure of economic performance of the system, is 2.43E+12 seJ/€ for Rome compared to 1.64E+12 seJ/€ for Italy, suggesting that in an urban system (generally characterized by a larger fraction of tertiary activities) the required environmental support for the generation of economic results is much higher than for the whole economic system. Finally, comparison of above performance indicators with similar studies published by other authors (Taipei, San Juan and Macao) points out that Rome has the highest annual emergy per capita (suggesting higher potential standard of living).     

Seismic response of a geological,historical and architectural site: the Gerace cliff (southern Italy)

Bulletin of Engineering Geology and the Environment - Several historical towns and sites in Italy and other parts of Southern Europe were built on topographic reliefs, and they host inestimable...     

Fatigue-safety assessment of reinforced concrete (RC) bridges: application to the Brazilian highway network

During the assessment programme of Brazilian roadway bridges, it was noticed that two girder-slab reinforced concrete bridges, with cantilever girders on extremity spans, were a common structural solution adopted 40 years ago in Brazil. Particularities intrinsic to these systems like significant displacements expected on cantilevers associated with soil embankment settlement in bridge entrance can take to a sudden change in slope grades near its ends, provoking sometimes high impact factors. Besides that, traffic and axle load increase has been of concern because these bridges were designed with different scenarios 40 years ago. Therefore, these facts can affect the structural performance of these structures in face of 100 years life required on most current codes for new bridges. So, in this article, a safety assessment to this assembly of bridges is performed. For this study, a simulation model has been developed, which includes the most significant sources of uncertainty in the definition of traffic action and structural response of bridges. Database provided by dynamic tests of these bridges were used for this performance-based assessment. As a result, reliability indexes to fatigue and ultimate limit state of bending are calculated and compared with target values as specified by codes.     

Quality assessment of bed sediments of the Po River (Italy)

Comprehensive and contemporary evaluations of physical, chemical and toxicological endpoints have been performed on bed sediments of the Po River, the major Italian watercourse. Two extensive sampling campaigns were conducted in summer and winter low-flow conditions. Composite sediment samples were collected from ten reaches of the main river: the first was located in the upper region (ambient control), and the others downstream of the confluences of nine principal tributaries. The two sampling programs were paralleled by contemporary investigations on the macroinvertebrate community. The particle-size composition along the Po River showed a relatively uniform distribution of fine sand, a progressive downstream decrease of coarse sands and a corresponding increase of fine materials. The levels of polychlorinated biphenyls (PCB), polycyclic aromatic hydrocarbons (PAH), extractable organo halides (EOX), Cd, Cr, Cu, Hg, Ni, Pb and Zn were determined in sediment fine particles (< 63 microm), and showed marked changes across the ten river reaches. Their longitudinal trends, as those of organic carbon and total nitrogen, were very similar and largely independent of the survey season. Sediment quality benchmarks were used to evaluate sediment chemistry, and, although the overall level of contamination was from moderate to low, the reaches located downstream of the tributaries Dora Riparia, Dora Baltea, Lambro and Oglio were considered to be at risk. Sediments were tested for toxicity on Oncorhynchus mykiss, Ceriodaphnia dubia, Raphidocelis subcapitata and Vibrio fischeri. The toxicity tests were conducted both with sediment extracts and whole samples. Sediment extracts showed toxic potentials that were consistent with the spatial distribution of contaminants. Whole-sediment toxicity showed moderate/low effects which also included false positives and negatives. Alterations of the macroinvertebrate community were found for many kilometers downstream of Dora Riparia, and with a seasonal dependence, also in other reaches of the Italian river. Principal component analysis (PCA) was used to describe the longitudinal and temporal changes of the Po River, and allowed the selection of the most useful and discriminating indicators.     

How to determine the necessity for using underground space: an integral assessment method for strategic decision-making

The paper describes an integral assessment method for stategic decision-making that was designed for use in the “Strategic Study Use of the Underground Space.” The method was designed (1) to determine the functions which would lend themselves best to being constructed underground; (2) to determine the areas with a high potential for the use of underground space; and (3) to identify which developments would encourage or frustrate the use of underground space. The manner in which the method was developed and used during the study is detailed through the use of examples.     

Platinum levels in natural and urban soils from Rome and Latium (Italy): significance for pollution by automobile catalytic converter

Platinum concentrations in topsoil samples collected in 1992 (48) and in 2001 (16) from the urban area of Rome have been determined by ICP-MS. Concentrations in 47 soil samples collected in 1992 from natural sites of Latium (an area around Rome) have been determined for a first assessment of natural background levels. The Pt concentrations in Rome urban soils collected in 1992 range from 0.8 to 6.3 ng/g (mean = 3.8 +/- 1.0) overlapping the concentration range of natural soils from Latium (mean = 3.1 +/- 2.1 ng/g). No significant correlation has generally been found between Pt contents in the 'natural' soils and related bedrock or major pedogenetic parameters. These results suggest that there is no evidence of Pt pollution in Rome urban soils at that time, because the massive use of the automobile catalytic converter has only just started. Higher (up to six times more) Pt concentrations, than those measured in the 1992 samples, have been measured, in some cases, in Rome urban soils collected in 2001, suggesting a possible start of Pt accumulation because of the large-scale use in the last decade of automobile catalytic converters. At the same time, a clear decrease of lead levels in Rome urban soils with respect to the levels measured in 1992 has been observed, paralleling the decreasing number of lead gasoline-fuelled cars. Here we present one of the first systematic studies for defining background levels of Pt in Italian natural soils, thus allowing for monitoring, in the future, should any possible Pt pollution caused by the use of automobile catalytic converter, especially in urban soils, occur.     

模糊综合评判法在地下空间资源质量评估中应用

在分析影响资源质量因素的基础上,通过建立多层次模糊综合评价模型,对城市地下空间资源质量进行评估,在建立模型过程中,利用层次分析法确定权重,利用主因素突出型算子结合最大隶属度法对综合评价结果进行分析,据此得出城市地下空间资源质量等级,按不同质量等级对地下空间进行有序开发,以此指导地下空间的开发利用。     

Effects of a controlling geological discontinuity on the seismic stability of an underground cavern subjected to near-fault ground motions

The mechanism for the influence of near-fault ground motion on seismic issues for underground rock caverns has seldom been addressed, especially for caverns controlled by large geological discontinuities. In this paper, a nonlinear joint model was used to simulate the effects of unfavorable geological discontinuities under seismic excitation. The influence of near-fault ground motion on unfavorable geological discontinuities was analyzed using a large sample of ground-motion records collected from the NGA-West2 database. A damage potential index (DPI) for unfavorable geological discontinuities was proposed and discussed. The #1 surge chamber of the Baihetan Hydropower Plant, which is dominated by interlayer shear weakness zone (ISWZ) C2, was used as a study case to investigate the differences between pulse-type near-fault ground motion, non-pulse-type near-fault ground motion, and far-field ground motion. The results of the study indicate that (1) significant velocity and displacement as well as a stronger long-period response spectrum are key characteristics of pulse-type near-fault ground motions, whereas non-pulse-type near-fault ground motions display characteristics similar to those of far-field ground motions; (2) the velocity pulse is responsible for the destructive capabilities of near-fault ground motions; (3) the peak ground velocity (PGV) was shown to be the most suitable DPI of several ground-motion parameters for large geological discontinuities under seismic excitation (applicable to both near-fault and far-field ground motions); and (4) PGV was verified to be the most effective DPI for ISWZ C2 at the Baihetan #1 surge chamber. The cavern became fragile when subjected to near-fault ground motions, so special seismic reinforcement measures are recommended. These findings may provide a reference for the seismic design of underground caverns.     

Engineering geological assessment of the Diyarbakir solid waste landfill site (SE Turkey)

The paper reports a study to investigate the geological, hydrogeological and geotechnical properties of a proposed solid waste landfill site for Diyarbakır city, southeastern Anatolia. The study area is located in the vicinity of the Diyarbakır–Mardin highway and 6 km away from the city. The paper describes the topography, geology and hydrogeological characteristics of the bedrock and based on water absoprtion (Packer) and laboratory measures, gives permeability values for the firm to stiff clays on which the landfill will be placed as well as the secondary permeabilities of the basalts and the intergranular permeabilities of the sand and gravel layers within the claystone–mudrock sequence. Recommendations are made for the construction of the landfill.      

Empirical methods to quickly select an appropriate discrete fracture network (DFN) model representing the natural fracture facets

Bulletin of Engineering Geology and the Environment - The accuracy of the established discrete fracture networks (DFNs) has a significant impact on the effectiveness of solving engineering...     

Nature reserve selection on forest fragments in a suburban landscape (Rome, Central Italy): indications from a set of avian species

A set of avian forest species, known from the literature as fragmentation-sensitive, was considered as the target in nature reserve planning following a conceptual framework. Their abundance was investigated in an 'archipelago' of oak woodland fragments embedded in a suburban landscape matrix of central Italy. None of the four species were found in any wood fragment smaller than 10 ha. The presence/absence analysis of woodland fragments studied showed that the study species were present, however, in larger fragments, highlighting the strategic role of habitat size and isolation for the persistence of these species at local scale. Species numbers and their total abundance were significantly and directly correlated to overall species richness of each fragment: in this landscape context our study species shows characteristics of serving as focus and surrogate species of bird richness. The selected species are area-sensitive and poor dispersers: however, they are still relatively widespread, at a regional scale. Although the abundance of individual species may be affected by stochastic factors, total abundance of this forest bird guild may constitute a useful dependent variable that can provide rapid quantitative data needed for planning strategies at local scales.