A Combined Analytical and Numerical Approach for the Evaluation of Radial Loads on the Lining of Vertical Shafts

The evaluation of the load acting on a shaft support is of fundamental importance for the correct dimensioning of the structure. The load acting on the support can appear somewhat complex. One approach to define the load on the lining may be to use the convergence-confinement method (CCM) normally used in the tunneling design. This process involves intersecting the convergence-confinement (CC) curve with the support reaction line. However, in order to be able to adopt this technique, it is necessary to know the radial displacement of the shaft wall at the point in which the support is to be installed. Using the equations of Vlachopoulos and Diederichs (Rock Mech Rock Eng 42:131–146, 2009) the reaction line of the support can be calculated. Numerical models developed with Flac 2D v.6.0 considering the Mohr–Coulomb criterion and an ideal elasto-plastic behavior simulating stepwise excavation and support installation were developed. The relation between applied internal stress and radial displacement of the wall shaft, obtained by the numerical simulation was compared with the CC curve obtained by the CCM and it showed a good match between the two methods. However, an iterative procedure has also been used to insert the reaction line in the CC graph. The result shows lower initial displacements (and therefore greater radial stress) when compared with the values obtained by numerical calculation with the axisymmetric model. It is therefore recommended the combined use of the CCM (analytical method) and the axisymmetric numerical model (step by step simulation) to obtain the values of the final load on the lining and the final plastic radius, necessary for the correct design of supporting structures on the shaft wall.     

Challenges to the development of carbon markets in China

China has introduced several pilot emission trading schemes to build the basis for a national scheme. The potential scale of this initiative raises prospects for a regional carbon trading network as a way to further engage other major Asian economies. However, the Chinese carbon markets rest upon a unique political-economic context and institutional environment that are likely to limit their development and viability. This article offers an overview of such structural economic and political constraints. Four main challenges are identified, namely, inadequate domestic demand, limited financial involvement, incomplete regulatory infrastructure, and excessive government intervention. The first two challenges concern economic dimensions and may be partially addressed by the incentives created by the newly introduced emission trading schemes. The other two are more deeply entrenched in the dominant political system and governing practice. They require fundamental changes to the ways in which the state and the market interact. The success of China's carbon market reform depends crucially on the ability of the ongoing efforts to transform the distorted state–market relationship.

Policy relevance

The burgeoning carbon markets offer opportunities for emissions mitigation at lower costs and enable circulation of a new form of capital, i.e. carbon credits, across borders. China accounts for a gigantic share of global GHG emissions and has the potential to significantly scale up these opportunities. There are clear implications for market developers and participants worldwide, including climate policy makers who attempt to link their emission trading schemes to other schemes, firms who seek to take advantage of the inexpensive carbon offsets generated in developing countries, international financial institutions who endeavour to establish their business in an emerging major carbon market, etc. This article can inform their decisions by identifying key issues that may undermine their ability to achieve these goals. Policy makers and stakeholders will benefit from this analysis, which shows how the Chinese carbon markets operate in ways that may be different from their experience elsewhere.     

Investigation of rainfall-induced failure processes and characteristics of cataclinal and anaclinal slopes using physical models

In this study, two types of small-scale physical modeling tests have considered the impact of the infiltration of rainfall and groundwater level in order to investigate the processes involved in rock slope deformation and failure. The study conducted the physical tests under controlled conditions of groundwater level with rock block shape for two rock slope types (cataclinal and anaclinal slopes). Observations obtained during each stage of deformation and failure were used to explain how gravity deformation varies with groundwater conditions on cataclinal and anaclinal slopes, and infer how rainfall and groundwater influence slope failure. Our results indicate that groundwater level is a crucial factor in the deformation failure of slopes. The failure mechanisms of cataclinal slopes differ considerably from those of anaclinal slopes. The infiltration of surface water and groundwater can have a significant influence on rock layer deformation and the speed of failure. Different shapes of rock block have two toppling types of rock slope, the spherical rock model relatively close to flexural toppling type and the triangular rock model relatively similar to block flexural toppling type, respectively. Details of the failure characteristics of cataclinal and anaclinal slope models are discussed in this paper.     

Benefits of flavonoids and straw mulch application on soil microbial activity in pea rhizosphere

The importance of flavonoids in rhizosphere–legumes symbiosis has been recognized as critical. However, the limited data are available about their impact on soil microbial communities. In rhizosphere, it remains unclear whether flavonoids, mulch or their joint effects influence on soil microbial diversity and enzymes activity. Therefore, in this study, the effects of flavonoids and straw mulching on soil microbial functional diversity, fungi abundance and enzymes activity (dehydrogenases, protease, acid phosphomonoesterase) in pea rhizosphere were evaluated. The field study was conducted in Lublin, Poland (51°15′N, 22°35′E), on a Haplic Luvisol. Flavonoids were applied on pea seeds and after sowing soil surface was covered with straw mulch. In soil rhizosphere sampled three times during the vegetative period of pea were determined: dehydrogenases, protease and acid phosphomonoesterase activities, metabolic potential of soil bacteria, microbes number and predominant fungal species. The results showed that dehydrogenases and protease activities were significantly increased with time during pea growing season. Significant increase in dehydrogenases activity was observed after flavonoids and mulch influence. There was no impact of studied factors on acid phosphomonoesterase. The effects of flavonoids and mulch on biodiversity indices were related to sampling terms. Straw mulching increased potentially antagonistic fungi in pea rhizosphere. The results of this study can be useful in understanding the effects of flavonoids and mulch on microbial activity and dynamics in pea rhizosphere which is very important in soil quality and crop production.     

An integrative assessment of water vulnerability in First Nation communities in Southern Ontario,Canada

Assessing vulnerability related to water is a global concern and especially important to populations experiencing multiple exposures and sensitivities. Approaches are required that span social and physical concerns, and that bridge multiple types and forms of knowledge. This research investigates the water vulnerability of three First Nation communities in Ontario, Canada. A collaborative process was used to build an integrative understanding of water vulnerability, develop an associated instrument, and undertake the community scale assessments. Results from the assessment provided communities with a comprehensive overview of water vulnerability, and pointed to gaps in knowledge and specific areas where attention was needed. Conducting assessments at a community scale following the methodology employed in this research responds to the need for integration and context sensitivity when engaging in water vulnerability assessments and introduces innovations to existing assessment tools. A holistic approach to water vulnerability assessment provided decision-makers with the context-specific details and empirical insights they require to prioritize issues and allocate resources.     

Assessment of identifiable defect size in a drilled shaft using sonic echo method: Numerical simulation

The purpose of this paper is to study the capabilities of the sonic echo method in assessing the location of defects and the minimum possible detectable defect size in a drilled shaft. Three-dimensional axisymmetric finite element models were performed to investigate the effects of the defect size, defect depth-to-shaft diameter ratio, and shaft-to-soil stiffness ratio on the response of the sonic echo test. According to the results from the numerical simulations, a useful formula for defect size assessment in a shaft based on the sonic echo method is proposed, considering these factors simultaneously. Furthermore, a formula for predicting the detectable length-to-diameter ratio of a shaft was also recommended which correlates with the shaft-to-soil stiffness ratio and it varies from 10 to 32.     

Petrographical and geochemical investigation of the Triassic marbles associated with Menderes massif metamorphics,Kavaklıdere,Muğla,SW Turkey

Vast marble deposits occur in a cover sequence of the Menderes Massif, SW Turkey. Four major marble deposits are recognized in Mu?la province based on the stratigraphic levels. These are Permo-Carboniferous aged black marbles (1), Triassic aged marbles (2), Upper Cretaceous aged marbles (3), and Paleocene aged pelagic marbles (4). This study deals with Triassic aged marbles of the southern part of the Menderes Massif. The Triassic marbles from SW Turkey consist of two big marble horizons in the Çayboyu (ÇM) and Kestanecik (KM) regions. The characteristic samples are collected from different stratigraphic levels in marble deposits in the ÇM and KM horizons. Mineralogical and major, trace, and rare earth element (REE) analyses of marble, limestone, and schist were conducted on these samples to reveal their petrographical and geochemical characteristics. The ÇM horizon is represented by calcitic marble layers. Nickel, cobalt, manganese, and iron elements filled in fractures, fissures, and intergranular spaces of calcite crystals and these elements give the pinky colour to the marble from the ÇM horizon. KM marbles were deformed, metamorphosed, and recrystallized under greenschist facies P–T conditions. As a result of the metasomatic reaction of magnesium and manganese rich fluids with marbles, dolomite, and manganese, minerals such as rhodochrosite and pyrolusite have crystallized along vein walls and layers in the KM horizon. Dolomitization was determined in KM marbles, whereas ÇM marbles show the character of limestone. MgO, MnO, Fe₂O₃, Ni, and Zn contents of marbles from the KM horizon are higher than those of ÇM marbles due to metasomatic reactions. The Sr content in white coloured marbles ranges between 11.20 ppm and 112.20 ppm and this concentration reaches up to 272.70 ppm due to metasomatic reactions and fluid intake. The REE content of Triassic marbles is independent of the abundance of carbonate and the REE enrichment observed due to syn-metamorphic fluid flow. The significant negative Eu anomaly in REE patterns indicates that the protoliths of Triassic marbles are carbonate rocks of sedimentary origin.     

基于E-FAST的流溪河模型参数敏感性分析

基于E-FAST全局定量敏感性分析方法的思想,提出一个针对分布式物理水文模型——流溪河模型的参数敏感性分析方法,包括参数简化及取值范围确定、参数采样及采样次数的确定、敏感性评价指标的选取、参数敏感度计算4个部分.针对我国4个不同规模的流域(黄龙带水库流域、流溪河水库流域、长湖水库流域和新安江水库流域)开展了分布式物理水文模型参数敏感性分析,并采用4种不同的评价函数进行了对比计算.结果表明,流溪河模型饱和含水率和田间持水率是高度敏感参数,饱和水力传导率、土壤层厚度、土壤特性系数、边坡和河道糙率为敏感参数,其他参数为不敏感参数.     

Subalpine koura,Paranephrops planifrons (Decapoda), in Tongariro National Park: Zoogeographic implications

Koura, Paranephrops planifrons, were found up to 1260 m a.s.l. in a subalpine area of Tonga‐riro National Park in May and July 1978. Their habitat is described briefly, and possible factors limiting the distribution and abundance of high altitude populations of freshwater crayfish are listed. It is suggested that all mountains may not necessarily form absolute zoogeographic barriers to koura; the kind of mountain and the ecological milieu may be more important.