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11.
Abstract We propose that international climate change policy would be strengthened by the development and adoption of targets for atmospheric concentrations of greenhouse gases 25–50 years in the future in addition to near- and long-term targets. ‘Interim concentration targets’, which could be accommodated under the current Convention/Protocol framework, would provide several advantages over the current focus on either the short term (e.g. Kyoto Protocol) or the long term (e.g. ultimate stabilization targets). Interim targets would help constrain rates of climate change (which are not sufficiently addressed by short- or long-term targets, even when paired together). They would also provide a means for keeping open the option of achieving a range of long-term goals while uncertainty (and political disagreement) over the appropriate goal is resolved. We substantiate a number of rationales for such an approach, discuss the use of interim targets in other contexts, and illustrate how such targets for climate change policy might be set. 相似文献
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碎裂结构边坡稳定性受多组相交结构面控制,且受降雨、地震等多因素影响强烈,具有一定的特殊性。本文以某花岗岩碎裂结构边坡为例,在边坡的地质条件和岩体结构研究的基础上,结合施工及监测反馈信息,深入分析了边坡变形破坏模式,并根据稳定性计算结果,提出锚索、钢筋桩与排水相结合的支护方案。研究结果表明:坡体内部陡倾卸荷裂缝发育形成后缘切割面,中下部滑面追踪陡缓两组结构面发展;支护措施实施后,边坡经历512地震及雨季,多点位移计监测结果表明,地震和降雨对边坡稳定性影响较大,支护措施较好地控制了边坡变形。 相似文献
13.
This paper focuses attention on the some basic aspects of the role of clay fraction of marly soils including palygorskite and sepiolite upon marl behaviour. The clay fraction of marl is generally dominated by palygorskite and/or sepiolite. It is the performance of these clay soil fractions that are the root cause of many of the problems encountered in the use of such soils as load-bearing materials. This makes it necessary to investigate the role of palygorskite and sepiolite on marly soil's performance. In this paper, some geotechnical and geoenvironmental aspects of marl behaviour is investigated and a new definition and classification of marly soils is presented. This classification focuses attention on the presence of palygorskite or sepiolite as the major fraction of marl, which governs its geoenvironmental and geotechnical behaviour. 相似文献
14.
The development of stability problems related to classical mixed methods has recently been observed. In this study, a soil-water coupled boundary-value problem, one type of stability problem, is presented using the element-free Galerkin method (EFG method). In this soil-water coupled problem, anomalous behavior appears in the pressure field unless a stabilization technique is used. The remedy to such numerical instability has generally been to adopt a higher interpolation order for the displacements than for the pore pressure. As an alternative, however, an added stabilization term is incorporated into the equilibrium equation. The advantages of this stabilization procedure are as follows: (1) The interpolation order for the pore pressure is the same as that for the displacements. Therefore, the interpolation functions in the pore pressure field do not reduce the accuracy of the numerical results. (2) The stabilization term consists of first derivatives. The first derivatives of the interpolation functions for the EFG Method are smooth, and therefore, the solutions for pore pressure are accurate. In order to validate the above stabilization technique, some numerical results are given. It can be seen from the results that a good convergence is obtained with this stabilization term. 相似文献
15.
E. M. Frempong 《Geotechnical and Geological Engineering》1995,13(4):181-198
Summary The presence of mica in pavements can be detrimental due to the effects of high compressibility and low compacted density it imparts to the soils. Three residual micaceous compressible soils derived from granite, granitic gneiss and phyllite can neither be used as base nor sub-base course in their untreated form. In this study, these soils have been treated with a range of lime and sand contents to determine their effects on consistency, compactability, bearing and compressive strengths and volume stability against swell. With 6–8% lime, soils derived over phyllite and granitic gneiss were rendered suitable for use as sub-base course as their plasticity index, 96 hour soaked CBR values and unconfined compressive strengths (UCS) were improved to satisfy existing local criteria. Similarly, with 30% sand both soils became suitable for sub-base course construction. The use of both additives markedly improved the volume stability of all the soils against swell. 相似文献
16.
下伏软弱层黄土边坡变形机制分析及治理对策研究 总被引：4，自引：6，他引：4
本文研究了陕北某电厂夹断层破碎带上覆黄土的泥岩、砂岩互层反倾边坡的变形机制,并研究治理对策及其治理效果。通过边坡工程地质条件及变形破坏特征分析,建立FLAC3D地质模型,采用数值模拟方法研究了边坡变形破坏机制,在此基础上提出削方减载、锚筋桩、锚杆及坡面防护的综合治理措施。研究结果表明,边坡的变形受开挖坡形的影响,坡体浅表层特别是断层带及坡顶黄土部位出现大范围拉应力集中,断层带出现向坡外的挤出变形,带动上部黄土的牵引式变形,引起沿黄土和基岩基覆界面的剪切变形,在黄土中出现大量拉裂缝,在一定条件下潜在滑移面逐渐贯通,坡体将产生整体失稳。边坡的治理应通过削方减载改善坡体应力环境,并重点控制断层带及黄土与基岩基覆界面的变形,数值模拟结果表明,治理后边坡稳定性较好,满足设计要求。 相似文献
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18.
Silt cannot satisfy the requirements of highway construction because of its low strength. A new stabilizing agent (SEU-2) was developed to improve the mechanical performance and applicability of silt in road. Laboratory tests, including unconfined compression and shrinkage tests, were performed. Test results show that the new stabilizing agent can significantly increase the strength and the water stability, and decrease the shrinkage strain of silt. Field tests were also carried out and the results indicated that the new stabilizing agent could effectively improve the entire stiffness of subgrade. From the point of view in mechanics and applicability in road, adding 4% new stabilizing agent is an economic and reasonable method to stabilize the silt. The stabilized silt has high early strength, small shrinkage deformation, and high entire stiffness. It can satisfy the requirements of highway subgrades. 相似文献
19.
The aim of the present study is to optimize the slow release biostimulant ball (BSB) for bioremediation of contaminated coastal sediment using response surface methodology (RSM). Metals contamination and stabilization of metals in coastal sediments using BSB were investigated. The effects of BSB size (1–5 cm), distance (1–10 cm), and time (1–4 months) on the stabilization of metals including Fe, Cd, Cu, and Pb were determined. The maximum stabilization percentages of Fe, Cd, Cu, and Pb, of 64.5%, 54.9%, 63.8%, and 47.6%, respectively, were observed at a 3 cm ball size, 5.5 cm distance, and a period of 4 months; these values are the optimum conditions for effective treatment of contaminated coastal sediment. The determination coefficient of the R2 value suggests that > 91.55%, 89.97%, 96.10%, and 86.40% of the variance is attributable to the variables of Fe, Cd, Cu, and Pb, respectively. 相似文献
20.
In water treatment calcium hydroxide is used in softening and decarbonization techniques as well as in stabilization processes. Due to its slight solubility calcium hydroxide is applied as suspension. The dissolution kinetics plays a major role in these processes. For the characterization of calcium hydroxide dissolution empirical methods exist. These methods allow relative comparison of different calcium hydroxide products. Thus in this study a dissolution rate model is presented that is based on the chemical reactions determining the dissolution. This model allows to predict the dissolution with respect to particle diameter and temperature. However, the most important factor is the particle diameter i.e. the total surface of particles in solution. Furthermore an effect of the dosed amount of calcium hydroxide particles on the solubility was found. 相似文献