盾构机掘进通过花岗岩球状风化体施工技术——以广州地铁六号线二期萝香区间工程施工为例

引用广州地铁萝香区间盾构机掘进通过花岗岩球状风化体的案例,对盾构穿越花岗岩球状风化体发育地层的施工风险进行了分析.在施工过程中,采取盾构机掘进参数控制、同步注浆控制、施工监测与二次补充注浆的方法,成功通过花岗岩球状风化体.列举了一些施工中的异常情况和处理措施.     

论文物环境对文物保护的影响

长期以来文物保存环境一直受到人们的关注,文章着重论述了文物保存环境对文物的影响,并通过多个实例说明了文物保存环境的破坏给文物带来的种种损害,指出了整治文物保存环境和文物保护的重要性,为整治文物保存环境和文物保护提供了新的思路.     

Experimental tests used for treatment of red weathering crusts in disintegrated granite – Egypt

Rock weathering is defined as the process of rocks alteration as a result of the adjustment of its internal constituents by the action of physical, chemical and biological factors, to the prevailing conditions of the atmosphere and in the environment. In humid polluted areas “red weathering” is one of the major deterioration forms that characterize most granitic rocks. Several intervention steps are required to remove and treat all surfaces affected by this form. It is one of the most aggressive forms of deterioration which are essentially composed of some complex species of clay minerals “Kaolinite, Illite, Montmorillonite and Tosudite”, in addition to some species of salts as “Gypsum” pigmented by “Hematite” as a colorant. After several investigatin techniques, these crusts need several intervention and conservation steps to remove and eliminate the aggressive effects resulted from the red crusts through three essential steps: “cleaning, gap filling and strengthening and stabilizing”. After evaluating all materials and methods that were performed by “DBN, SEM, EDX, and AAS”, the present study suggests that the most suitable cleaning methods are composed of three essential steps “dry and vacuum cleaning (DVC), ultra-sonic cleaning (USC), poultice cleaning (PC)”. Furthermore, the elected gap filling material composed of “Araldite AY-103” mixed with “Granite powder as petro-filler.” Finally, different evaluation methods proved that “Wacker H” is the most suitable strengthening and stabilizing material for consolidation purpose.     

土遗址防风化加固效果评价指标综述

表面加固是防止土遗址风化的一种重要手段.加固效果的系统评价是土遗址加固科学研究的关键环节之一,关系到土遗址能否耐久保存.从土遗址加固前后的颜色变化、透气性、渗透速度和深度、力学强度、透水性、土壤孔隙度及孔隙率、重量变化、pH变化以及耐老化性等方面对土遗址的防风化加固效果评价指标进行了综述,以期为土遗址保护工作者更好地选择保护材料提供理论依据.     

天山乌鲁木齐河源区径流水化学特征及影响因素分析

在乌鲁木齐河源区采集两年的大气降水和1号冰川、空冰斗、总控3个水文点逐日定时径流样品,对主要离子、pH、电导率EC和总溶解固体TDS进行了分析。结果表明,大气降水离子类型为Ca^2＋-Na^＋-HCO3--SO4^2-,接近中性;径流离子类型为Ca^2＋-Na^＋-HCO3--SO4^2-,呈弱碱性。径流中EC和TDS均值总控〉1号冰川〉空冰斗,其中1号冰川径流的峰值远高于其它两个水文点。受不同下垫面的影响,1号冰川水文点TDS变化受日径流量影响显著,而空冰斗水文点基本不受影响。径流中离子组成主要受岩石风化作用影响,离子比值和Piper图分析说明控制径流离子的主要过程是碳酸盐、黄铁矿和长石类矿物风化。海盐校正分析得出,大气降水对1号冰川、空冰斗、总控径流离子贡献率分别为4.91％,9．10％和5．42％。通过阳离子通量计算,2006年、2007年1号冰川径流的化学风化侵蚀率分别为18．1t／（km^2·a）和12．3t／（km^2·a）。     

乐山大佛基岩酸雨影响评价及防治对策

在酸雨的作用下,大佛砂岩的风化剥蚀作用很强烈,为定量研究酸雨对乐山大佛基岩的影响,实地采集了乐山大佛基岩及乐山酸雨样本,搜集了大量相关资料,进行了模拟酸雨试验。研究表明,乐山大佛早期的新鲜基岩,在长期的风化剥蚀作用下,由外到内形成了粉末层—硬壳层—风化层—新鲜基岩层,这一完整的表层层次结构。这种层次模式是由岩石表面逐渐递次向岩石内部发展的。通过模拟酸雨试验还发现,乐山大佛基岩,在最近30年酸雨的作用下,风化剥蚀作用强烈.,平均剥蚀速率在0.2克/小时·平方米左右,总计被剥蚀厚度约2厘米。提出了应更高度警惕酸雨对乐山大佛裸露基岩的破坏,进一步深化对乐山大佛裸露基岩保护的相应防治对策。     

Pickeringite: A deleterious salt on buildings

Pickeringite, MgAl₂(SO₄)₄·22H₂O, was observed as efflorescence at the church of Saints Peter and Paul in Largario (Switzerland). The spongy salt crusts formed directly on rusty, deeply weathered gneiss rich in mica. The building stones originate from rocks in the vicinity of the village. On outcrops, similar occurrences were discovered. Ferrous and pyritic gneiss exhibited efflorescences of gypsum, epsomite, potassium alum, and pickeringite in sheltered places. Based on these observations and the known conditions of formation, we conclude that pickeringite resulted as a secondary mineral from weathering of pyritic gneiss. Most likely, weathering happened in an environment where, among other ions, aluminium and magnesium were present, but calcium and carbonate were absent. Such conditions rarely occur. If our hypothesis was confirmed, the fact that an extremely acid, calcium- and carbonate-free weathering system evolves next to lime mortars and plasters would be very surprising. It would imply that restricted zones devoid of a buffering effect develop on a microscopic scale.     

The building stones of the ancient centre of Naples (Italy): Piperno from Campi Flegrei. A contribution to the knowledge of a long-time-used stone

Piperno, a Late Quaternary magmatic rock cropping out on the eastern side of the Campi Flegrei (Italy), is probably the most important building stone of Naples, used over a time-span from at least the Roman age until the beginning of the 20th century. Despite its wide diffusion in the monumental architecture of Naples, very little is known about this rock, as regards its technical features, as well as the geological aspects. This paper aims at providing a first overall contribution towards a rediscovery of this long-time-used material, in view of careful restoration works, which nowadays at Naples only take into account the proper geological features of the stone in a few peculiar cases. Thus, it seems of extreme importance to understand the basic parameters of Piperno and, above all, its response to weathering agents. Main mineralogical, petrographical and engineering–geological properties are presented here for the first time, with specific reference to two sampling areas, located at Pianura and Soccavo, in the western sector of the Neapolitan urban area. As far as many of its physico–mechanical features are concerned, Piperno extends over a wide range of values, which allow different varieties of the rock to be identified. This preliminary result is seemingly in accordance with data from old historical literature, which stated the existence of six horizons in the Piperno formation.     

Marine Aerosol Weathering of Mediterranean Calcarenite Stone: Durability of Ethyl Silicate,Nano Ca(OH)2, Nano SiO2, and Nanostructured Consolidating Products

ABSTRACT

Calcarenite stone samples from a historic building (Bizerte, Tunisia) were collected and treated under different environmental conditions with several consolidating products: alkoxysilane (ethyl silicate), a surfactant-templated novel sol–gel, Ca(OH)₂, and SiO₂ nanoparticles. These were subjected to marine aerosol accelerated aging cycles and studied by several non-destructive tests and techniques to assess the stability of the products. Results show that weathering caused by salt crystallization is not inhibited but it is slowed down due to the enhancement of superficial mechanical properties (surface cohesion and micro-hardness) achieved after one month of treatments application. A high or low relative humidity of the consolidation environment significantly affects the final mechanical and aesthetical physical properties and therefore conditions the durability of the treated substrates, even producing higher damage than observed in the blank specimens, depending on the product.     

Spectral Characteristics of Chemically Weathered Sandstones in the Yungang Grottoes,China

ABSTRACT

Many of the sandstones at cultural heritage sites around the world are susceptible to chemical weathering, and long-term monitoring of the chemical weathering would be of great value for heritage conservation and would also provide reference data for environmental protection policies and projects. Reflectance spectroscopy is a potential tool for monitoring sandstone weathering due to its non-destructive characteristics. In this paper, we present the results of an investigation into the reflectance spectra of sandstones at the Yungang Grottoes, China, where the sandstones are variously fresh, calcite-dissolved, or argillitic-altered. We found several spectral absorptions, including those at 490, 675, 900, 1410, 1918, 2205, 2330, 2350, and 2380?nm. The absorptions at 490, 675, and 900?nm are related to hematite cement, while that at 2330?nm is associated with calcite cement. The absorptions at 1410, 2205, 2350, and 2380?nm are induced by the Al–OH vibration of kaolinite, and that at 1918?nm is related to crystal water. The calcite-dissolved sandstones have lower absorption intensities at 2330?nm than fresh sandstones, and the argillitic-altered sandstones have lower absorption intensities at 490, 675, and 900?nm than the fresh sandstones. In the 1st-derivative reflectance plots, the absorption peaks at ～1400?nm shift towards shorter wavelengths with increasing kaolinite contents. The spectral features of the fresh, calcite-dissolved, and argillitic-altered sandstones are all different, and this means they can be distinguished spectroscopically, which demonstrates the usefulness of reflectance spectroscopy for the long-term monitoring of sandstone weathering in the Yungang Grottoes.