A practical procedure for the back analysis of slope failures in closely jointed rock masses

Where closely jointed rock masses are encountered in slopes, failure can occur both through the rock mass, as a result of combination of macro and micro jointing, and through the rock substance. Determination of the strength of this category of rock mass is extraordinarily difficult since the size of representative specimens is too large for laboratory testing. This difficulty can be overcome by using a non-linear rock mass failure criterion or by back analysis of such slopes to estimate the rock mass strength. In this paper, a practical procedure and a computer program are presented for the back determination of shear strength parameters mobilized in slopes cut in closely jointed rock masses which obey a non-linear failure criterion rather than a linear one. The procedure shows that the constants to derive normal stress dependent shear strength parameters of the failed rock masses can be determined by utilizing a main cross-section and without a pre-determined value of rock mass rating (RMR). Trials are made for different RMR_m and RMR_s values corresponding to various possible combinations of the constant m and s, which are used in the Hoek–Brown failure criterion, satisfying the limit equilibrium condition. It is also noted that the procedure provides a quick check for the rock mass rating obtained from the site investigations. The method is used in conjunction with the Bishop's method of analysis based on circular slip surfaces. The procedure outlined in this paper has also been satisfactorily applied to documented slope failure case histories in three open pit mines in Turkey.     

Applicability of the geological strength index (GSI) classification for very weak and sheared rock masses. The case of the Athens Schist Formation

 The Athens Schist Formation includes a wide variety of metasedimentary rocks, varying from strong or medium strong rocks such as sericite metasandstone, limestone, greywacke, sericite schist through to weak rocks such as metasiltstone, clayey and silty shale and phyllite. The overall rock mass is highly heterogeneous and anisotropic owing to the combined effect of advanced weathering and severe tectonic stressing that gave rise to intense folding and shearing followed by extensional faulting, which resulted in highly weathered rock masses and numerous shear and/or mylonite zones with distinct downgraded engineering properties. This paper is focused on the applicability of the GSI classification system to these highly heterogeneous rock masses and proposes an extension of the GSI system to account for the foliated or laminated weak rocks in the lower range of its applicability. Received: 5 March 1998 · Accepted: 13 July 1998     

超临界CO2在高温裂隙岩体中的热交换研究

近年来,由于超临界CO₂(Supercritical CO₂,简称scCO₂)额外的地质封存效益,将scCO₂替代水,作为深部地热开采的工作流体的设想,正受到越来越多的关注。因此,开展高温裂隙岩体中流体运动和热交换过程的模拟研究,对于理解深部地热开采机理具有重要意义。本文在充分考虑scCO₂热物理性质随压力和温度变化的基础上,建立了基于三维裂隙网络显式描述的复杂高温裂隙岩体scCO₂热-流耦合模型。通过与热流耦合作用下的二维单裂隙模型的解析解进行对比,验证了数值模型的正确性,然后对scCO₂在复杂三维随机裂隙岩体的渗流和热交换过程进行了模拟。研究发现:贯通的裂隙网络通道是scCO₂的主要流动路径,在贯通的裂隙簇中会出现明显的优势流,突破现象最早在贯通裂隙簇中产生,scCO₂流体对压力非常敏感,选择合适的注入压力能显著增加热交换效率和降低流动难度。模拟结果表明,本模型可以很好地展现裂隙岩体换热过程的非均质特性和结构面控制特性,可作为评价scCO₂采热过程的有效工具。     

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.     

Effect of high levels of alkalinity on geotextiles. Part 1: Ca(OH)2 solutions

The adverse effect of high alkalinity solutions on certain polymers has long been recognized by the polymer industry. Most chemical resistance charts and summary tables give an approximate indication of where problems might occur. Lacking, however, is the degree of this effect and the general conditions in which problems might exist. Furthermore, there is no testing methodology to quantitively assess the possible effects.

This paper investigates six geotextiles using alkaline solutions of pH = 12 and pH = 10; and it compares the resulting flow and strength behavior to the as-recieved fabric incubated at the neutral condition of pH = 7. All tests were conducted at the temperature of 25°C (77°F). The flow rate is seen to decrease with the duration of the experiment, and is caused mainly by the formation of a precipitation filter layer on top of the fabrics. The strength data showed a significant reduction in strip tensile strength for both polyester fabrics in the pH = 12 solution. No significant trends were seen in the pH = 10 solution within the 120 days of these tests.

The results point out the necessity of knowing site-specific information about the groundwater (and perhaps soil conditions) so as to properly select a geotextile. Furthermore, the results seem to question the effects of groundwater with moderate alkalinity for longer time periods than evaluated here, and perhaps under elevated temperatures as well. Additional work into these potentially adverse effects seems to be warranted.     

对IPLV的学习和研究(1):定义解读

通过对GB 50189—2005和GB/T 18430.1—2007的研读,探讨了我国标准中对IPLV的定义。鉴于产品标准作为设计标准的引用和约束标准,认为在研究IPLV时,将产品标准与设计标准分开讨论的研究方式是不可取的。强调了IPLV计算和检测的公式不是IPLV完整的表达式,还应受到GB/T 18430.1—2007标准中其他特定条款的约束。离开这些特定条件,IPLV计算和检测公式不能单独成立。尽管目前的IPLV指标不是评价冷水机组及其系统最完善的方法,但是在更完善的评价方法得到广泛认同之前尚无法被替代,采用COP和IPLV两个评价指标要比只采用其中任何一个要更客观,也更科学。     

世界卫生组织新修订饮用水水质准则值(2011)简介(上)

本文简要介绍了世界卫生组织2011年新修订的饮用水中有关微生物、可接受性、放射性和化学品方面的准则值。     

《爆破安全规程》(GB 6722—2014)边坡岩体爆破振动速度安全允许值的理论探讨

开挖爆破诱发的地震波对岩质边坡有显著影响,我国《爆破安全规程》(GB 6722—2014)给出了边坡岩体的爆破振动速度允许值,但未明确说明取值的理论依据。为此,分析露天开挖爆破条件下邻近边坡岩体的附加动应力和质点振动速度场分布特征,推导以坡表质点振动速度表征的岩体附加动应力表达式。以边坡岩体不发生剪切和张拉破坏为控制要求,考虑边坡岩体分级特征和坡体结构特征,提出基于简单边坡模型的浅层岩体的爆破振动速度允许值。分析表明,岩体强度、边坡坡度、滑动面深度和地震波频率等均对边坡岩体的允许振动速度存在显著影响。其次,无剪切破坏条件下计算的爆破振动速度允许值与《爆破安全规程》(GB 6722—2014)的控制标准在量级上较接近,而无张拉破坏时各级岩体的爆破振动速度允许值差别不大,《爆破安全规程》(GB 6722—2014)中岩质边坡爆破振动控制标准应在理论分析和工程实践基础上进一步细化。     

民用建筑中的接地(一)接地的基本概念

本文说明了实际工程中正确理解接地符号的内含，有助于对“接地”效果的分析；简述了在工程设计中根据接地电阻值的要求，估算接地体数量；分析了“一点接地”和“等电位”的概念。     

The Fe3O4-formation by the ‘Ferrite Process’: Oxidation of the reactive Fe(OH)2 suspension induced by sucrose

A mechanism of the formation of small particles of iron oxide in the wastewater treatment system ‘Ferrite Process’ is described. Small particles consisting of the Fe₃O₄−γ-Fe₂O₃ solid solution having slightly higher content of γ-Fe₂O₃ were obtained by the aerial oxidation of Fe(OH)₂ suspension in the presence of a weak dispersing reagent, sucrose, at pH 9.0. The increase of γ-Fe₂O₃ content is caused by a further oxidation of the Fe₃O₄ particles in the course of the reaction. The further oxidation was accelerated below 1000 Å of the particle size. When SO²⁻₄ ion coexisted with sucrose in the reaction medium, the further oxidation was reduced and the treatment of the wastewater was improved. At a temperature interval of 40°–65°C, the formation of α-FeOOH was completely inhibited by a small amount of sucrose and only Fe₃O₄ was obtained.     

Distribution of the solvent-extractable organic compounds in fine (PM1) and coarse (PM1-10) particles in urban, industrial and forest atmospheres of Northern Algeria

The distribution of the solvent-extractable organic components in the fine (PM₁) and coarse (PM_1-10) fractions of airborne particulate was studied for the first time in Algeria. That was done during October 2006 concurrently in a big industrial district, a busy urban area, and a forest national park located in Algiers, Boumerdes, Blida, respectively, which are the three biggest provinces of Northern Algeria. Most of the organic matter identified in both particle size ranges consisted of n-alkanes and n-alkanoic acids, with minor contributions coming from polycyclic aromatic hydrocarbons (PAHs), nitrated polycyclic aromatic hydrocarbons (NPAHs), oxygenated PAHs, and other polar compounds (e.g., caffeine and nicotine). The potential emission sources of airborne contaminants were reconciled by combining the values of n-alkane carbon preference index (CPI) and selected diagnostic ratios of PAHs, calculated in both size ranges. The mean cumulative concentrations of PAHs reached 3.032 ng m^− 3 at the Boumerdes site, urban, 80% of which (i.e. 2.246 ng m^− 3) in the PM₁ fraction, 6.462 ng m^− 3 at Rouiba-Réghaia, industrial district, (5.135 ng m^− 3 or 80% in PM₁), and 0.512 ng m^− 3 at Chréa, forested mountains (0.370 ng m^− 3 or 72% in PM₁). Similar patterns were shown by all organic groups, which resulted overall enriched in the fine particles at the three sites. Carcinogenic and mutagenic potencies associated to PAHs were evaluated by multiplying the concentrations of “toxic” compounds times the corresponding potency factors normalized vs. benzo(a)pyrene (BaP), and were found to be both acceptable.     

鄂西北山区传统戏场建筑丛考（上）——戏场建筑的产生及其发展沿革

该文通过对鄂西北山区现存传统戏场建筑的分析和对部分已毁戏场建筑的考证,概述了该地区常见的戏场建筑形式：寺庙戏楼、会馆戏楼和宅院戏楼等,并分析论证了该地区传统戏场建筑起源和发展的根源性因素以及多种地域文化因素。