嘉黎断裂中段重大工程区地质力学分析

嘉黎断裂是青藏高原东南缘断裂系中一条重要的深大断裂。近年来,众多大型线路工程和水利水电工程在藏东南开展,嘉黎断裂孕育的多种工程地质灾害对其建设和运维带来了巨大挑战。现有研究主要关注嘉黎断裂的全新世活动性,鲜有学者从工程地质力学角度分析断裂特征。本文以重大工程建设密集的嘉黎断裂中段为研究对象,开展了针对性的野外地质调查和工程地质力学分析。结果表明,嘉黎断裂中段的断裂地貌、岩石组合、岩体结构、地应力场、剪切带特征、第四纪活动性等工程地质力学因子具有典型的分段特征。断裂中段的工程地质力学模式可分为两类:(1)临近喜马拉雅东构造结的“韧性”工程地质力学模式;(2)远离东构造结的“脆性”工程地质力学模式。不同模式的形成主要是受到东构造结下伏热地幔流产生的高温高压强变质作用带的影响。基于分段特征,探讨了嘉黎断裂沿线的不同段需重点关注的工程地质问题及孕灾特征,为这一地区的重大工程建设和地质灾害防范提供理论参考。     

Engineering geological assessment of the proposed Uru Dam, Turkey

This paper describes the results of the engineering geological investigations and rock mechanics studies carried out at the proposed Uru Dam site. Analyses were carried out in terms of rock mass classifications for diversion tunnel, kinematic analysis of excavation slopes, permeability of the dam foundation and determination of rock mass strength parameters.Uru Dam is a rock-filled dam with upstream concrete slab. The dam will be built on the Suveri River in the central part of Turkey. The foundation rocks are volcanic rocks, which consist of andesite, basalt and tuff of Neogene Age. Studies were carried out both at the field and the laboratory. Field studies include engineering geological mapping, intensive discontinuity surveying, core drilling, pressurized water tests and sampling for laboratory testing.Uniaxial, triaxial and tensile strength tests were performed and deformation parameters, unit weight and porosity were determined on the intact rock specimens in the laboratory. Rock mass strength and modulus of elasticity of rock mass are determined using the Hoek–Brown empirical strength criterion. Rock mass classifications have been performed according to RMR and Q systems for the diversion tunnel.Engineering geological assessment of the proposed dam and reservoir area indicated that there will be no foundation stability problems. Detailed geotechnical investigations are required for the final design of the dam.     

Investigation of the Geological and Geotechnical Characteristics of Daroongar Dam,Northeast Iran

This paper discusses the results of the engineering geological and geotechnical investigations that have been carried out at the Daroongar dam site. According to the geomorphology and geological conditions and economic reason, the dam has been designed as an earth dam with a clay core. The dam foundation is composed of a sequence of sandy limestone and limy marl of the Upper Cretaceous period. This study is based on field and laboratory investigations, surface discontinuity surveying, drilled borehole data and permeability of dam foundation. The present studies include the evaluation of the dam foundation by water pressure tests. The water pressure tests indicate the necessity to provide a grout curtain below the dam foundation.The geology of the Daroongar dam foundation has a significant influence on the permeability and groutability characteristics. The permeability of jointed rock masses is strongly depended on joint characteristics; degree of jointing, opening, continuity and presence of filling materials. The laboratory tests included tests for unit weight, porosity, uniaxial, triaxial, tensile strength and deformation parameters. The strength and modulus of elasticity of rock masses were determined using the Hoek–Brown empirical strength criterion. The rock mass qualities and classifications of the dam site is assigned using the rock mass rating (RMR), the rock quality (Q) and the geological strength index (GSI) classification systems.     

Safety concept and criteria for hazardous waste sites

The problem of waste disposal in Germany has been solved by using a combination of above-ground and underground disposal. Site selection criteria and precise criteria for the performance assessment of various types of waste disposal are available. In view of long-term safety of disposal, it is necessary to include geological and hydrogeological viewpoints in addition to purely engineering viewpoints.

In particular, the geotechnical site-specific safety assessment is described, as defined by the government in “Technical Regulations on Wastes” (TA-Abfall) in the section “Underground Disposal”. This safety assessment must cover the entire system comprising waste, cavern/mine and surrounding rock. For this purpose geo-mechanical models have to be developed.

According to the multi-barrier principle, the geological setting must be able to contribute significantly to isolation of the waste over longer periods. The assessment of the integrity of the geological barrier can only be performed by making calculations with validated geomechanical models.

Various engineering geological data are required for the selection of a site, for the design and construction of a repository, and for a safety analysis for the post-operational phase. These data can only be attained by the execution of a comprehensive site-specific geomechanical exploration and investigation program. The planning and design of an underground repository in rock salt layers are described, as an example for the various steps of this type of safety assessment.     

Prediction of Rock Mass Squeezing of T4 Tunnel in Iran

One of the most important steps in designing underground structures is the evaluation of ground conditions in terms of squeezing potential and behavior of the geological structures. Generally, constructing a tunnel in the squeezing condition is a very slow and difficult task. Therefore, recognition and evaluation of the squeezing potential is very important in selecting a suitable excavation method and support, especially in weak rocks. This research is concerned with the assessment of squeezing potential along tunnel T4 of water conveyance system from Azad dam to Ravansar plain with the length of 11,380 m, located between Kurdistan and Kermanshah provinces, west of Iran. This tunnel is in an almost NS direction and flows through the contact zone of Iran and Arabic plates. According to the engineering geological investigations, the squeezing potential has been recognized as the most important difficulty in the excavation of tunnel T4. This conclusion can be explained by the several indicators including lithology, high disintegration of rock masses, alteration of rocks on the border of Iran and Arabic plates’ contact zone, low rock mass quality, high overburden, and highly jointed rock masses in a shuffle tectonic condition. This paper deals with the engineering geological and geomechanical properties of rock masses. Then, it evaluates squeezing intensity using empirical, semi-empirical, and analytical properties methods. The analysis conducted in these work shows that the tunnel excavation would encounter squeezing problems, which is most severe in region 2 due to the effects of the major young Zagros fault.     

与地下石油储备库有关工程地质问题研究现状和对策

我国将要兴建实施较大规模战略石油储备地下库面临一系列工程地质问题和挑战。为更好地服务于库址选择和规划,为工程设计和施工提供地质依据,本文在总结归纳已有工程实例和分类基础上,结合作者已经完成的两个石油战略储备基地选址评价,提出和分析了与地下油库有关工程地质问题及相应对策。     

Engineering geological evaluation of geological barrier rocks at landfills and repositories

 A site specific evaluation of geological barriers is required for landfills and waste repositories. The waste-repository-rock system has to be taken into consideration for this. Since the geotechnical barrier in conjunction with geological barriers contributes considerably to long-term isolation of the harmful substances from the biosphere, it is absolutely necessary to use engineering geology and hydrogeological methods for a quantitative assessment of the barrier effect of the host rock and the geological environment. For a waste disposal mine, the load-bearing capacity of the rock, the protective properties of the surrounding rock formations and the geological stability of the area are important factors in a safety analysis, of which the geotechnical stability analysis is an important part. Such an analysis comprises an engineering geological study of the site, laboratory and in situ experiments and model calculations, long-term monitoring, and special geological and geochemical investigations. Existing geomechanical modelling techniques provide a useful tool to perform barrier integrity calculations and to design an underground disposal mine. As an example, the barrier performance of the rock salt of the Gorleben salt dome is demonstrated using various safety indicators. Received: 3 January 1997 · Accepted: 29 January 1997     

乌东德水电站特高拱坝施工期坝基岩体质量工程地质评价

特高型拱坝坝拱座岩体承受的荷载巨大,坝基岩体质量是拱座稳定的关键,在施工期如何准确评价坝基岩体质量,是拱坝建基岩体工程地质研究的重要问题。本文以工程地质条件研究为基础,从岩性、岩体结构分布着手,研究建基岩体工程地质特征;以现场、室内试验、声波测试为依据,建立坝基岩体质量评价标准。对乌东德拱坝施工期揭露的建基面岩体进行质量划分,研究发现：乌东德拱坝建基岩体质量优良,以Ⅱ级岩体占绝大多数,少量Ⅲ₁级岩体,极少量Ⅲ₂级岩体,与可研成果高度吻合;建基岩体满足岩体质量与声波验收要求,岩体质量空间分布较连续,且相对均匀,有利于承受拱坝推力。     

川藏铁路卡子拉山滑坡发育特征与防灾减灾对策

为查明川藏铁路卡子拉山隧道进口规划建设区地质灾害特征,评价其在川藏铁路建设和运营期间可能遭受的地质灾害风险,采用高精度遥感、机载LiDAR、工程地质勘查等“空-天-地”一体化技术对该隧道进口规划区开展调查研究。结果表明:川藏铁路卡子拉山隧道进口规划区内发育有1#、2#滑坡和俄洛堆不稳定斜坡;1#滑坡规模约32.48×106 m3,2#滑坡规模约10.15×106 m3,均为已发生的特大型岩质滑坡;俄洛堆不稳定斜坡位于2处滑坡中部,规模约35.80×104 m3,下部为强风化岩体,上部为碎石土结构,为中型复合型结构斜坡。评价认为:川藏铁路卡子拉山隧道进口选线从2处滑坡体中部山脊穿过,2处滑坡对铁路选线未构成地质安全风险,但隧道进口穿过的俄洛堆不稳定斜坡存在潜在地质安全风险;1#、2#滑坡体在天然工况下处于稳定状态,俄洛堆不稳定斜坡在天然和地震工况下处于稳定状态,在暴雨工况下处于欠稳定状态。为规避工程建设扰动诱发潜在的滑坡风险,建议将卡子拉山隧道选线进口向东南侧平移,通过边坡开挖的合理设计、施工期间的实时监测及运营期间的针对性治理等措施,从源头上对潜在滑坡风险进行防控,以保证工程建设及运营安全。研究结果可为川藏铁路选线提供科学的地质依据。     

Geotechnical Engineering Assessment of the Nargesi Damsite, Southwest Iran

This paper describes the results of the engineering geological investigations and geotechnical studies performed in the Nargesi dam site. The dam foundation located on the sedimentary rocks of Neogen period. To conduct this study, the steps including field and laboratory investigations, surface discontinuity surveying, drilled borehole data, and permeability were performed on dam foundation. Besides, the evaluation of the dam foundation was carried out by water pressure tests, which indicate the necessity of creating a grout curtain below the dam foundation. The permeability and groutability characteristics of the Nargesi dam foundation are significantly affected by geology of the site. The rock mass properties of the test section obtained from secondary permeability index (SPI) completed with the degree of jointing of the drill core acts as a useful reference for ground treatment design. Here, the performed laboratory tests were as: determination of density, moisture percent, porosity percent, water absorption, uniaxial compressive strength, Point-load strength index (Is50), p-wave velocity (Cp), s-wave velocity (Cs), deformability, and triaxial tests. The rock mass properties and classifications of the damsite is assessed using rock mass rating, the rock quality (Q), and the geological strength index classification systems. The strength and modulus elasticity of rock masses were determined through the equations proposed by different researchers. According to the findings of this work, except for some cases, there is a reasonable correlation between SPI and rock quality designation values. Based on these results, grout type and composition was suggested for the design of grout curtain.     

深部咸水层二氧化碳地质储存场地选址储盖层评价

深部咸水层CO2地质储存属于环保型工程项目,开展地质评价来确定良好的储盖层是实现CO2地质储存长期、有效、安全封存的首要前提。储层地质评价内容主要包括储层的物理性质及其注入能力等;盖层地质评价内容主要包括盖层发育特征及封闭能力等。在规划选址到工程选址的不同阶段,储盖层评价的内容和对象应根据不同阶段的目的依次提高精度和量化程度。通过国内深部咸水层CO2地质储存工程场地选址阶段划分,结合储盖层地质评价的主要内容,初步建立了储盖层适宜性评价指标及其分级标准,对国内深部咸水层CO2地质储存工程场地选址中的储盖层地质评价及适宜性评价工作具有一定的指导意义。     

某水电站坝基G23挤压蚀变破碎带成因及工程性质分析

G23挤压蚀变破碎带是某水电站坝基的主要工程地质问题。通过对该水电站枢纽区新构造运动及构造体系特征的综合分析,探讨了G23挤压蚀变破碎带的成因机制。基于典型岩样的物相及微形貌试验成果,分析了G23带构造岩的岩性特征,明确了G23带岩体的物理性质及其转变特征,预测了该挤压蚀变破碎带在工程作用下的变化趋势。结合蚀变岩样三轴压缩试验的变形破坏规律,阐述了G23带对工程作用的响应及其对工程的影响。     

自强水库库区工程地质评价与坝线选址研究

自强水库位于陕南秦巴山地中低山地貌区,水库为镇巴县备用水源地及旅游观光风景区,属小(1型水库。通过对库坝区地质构造、地层岩性、岩溶发育等工程地质条件分析可知,对工程建设及坝线选址有影响的工程地质问题主要为库区内发育逆冲叠瓦小断裂以及岩溶发育可能导致水库渗漏等。库区内无大型活动性断裂构造,构造较为稳定,且库区蓄水范围小,蓄水量不大,不易诱发地震。而拟选坝址位于自强河段,沟谷对称顺直,综合水库坝址区地形地貌、工程地质等条件进行坝线比选,推荐下游坝线为较为理想的坝线位置,可满足工程建设要求。     

工程地质综合性与岩体结构动态控制观的提出

当前我国一系列大型地质工程建设中地质灾害预报和动态设计、信息化施工的需求,使工程地质学面临综合理论创新发展的历史性机遇和挑战.有关学者提出大成综合理论,从源头上综合了专家的多源知识,从理论上凝炼了工程地质学高度综合的特点.以大成综合理论为基础,作者提出将众多因素相互作用进行观察、判断和测试,建立关系矩阵并加以权重分析和活跃强度等运算,提出了表征工程地质多因素作用关系简便可行途径.其研究难点在于综合认识地质条件的原生、次生和工程作用下的变化.总结复杂地质条件下国内外地质工程实践经验,提出了自然演化和工程扰动下岩体结构动态控制观(DDC).结合工程场地规划和比选,以工程地质分区(EZI)、综合适宜性(CSI)、加固需求度(DRD)等可操作的量化指标,发展工程施工乃至运行扰动作用下的岩体结构控制论,更好地服务于地质工程与环境和谐的高层次决策目标.复杂地质条件下工程实践说明了DDC提出的科学合理性,以及解决复杂性问题的实用性.     

Evidence of Amplification Effects in Fault Zone Related to Rock Mass Jointing

Results of geological, geomechanical and seismometric investigations aiming at the analysis of the seismic response in a carbonate ridge of the Nera River valley (Central Apennines – Italy) are discussed. Geological and geomechanical surveys were aimed at defining the stratigraphic and structural setting of the outcropping formations and the jointing conditions of the rock mass. Velocimetric records of both ambient noise and small-magnitude earthquakes were analysed in order to identify amplification conditions. The analysis was carried out in the time domain, through directional energy evaluation, and in the frequency domain, through H/V spectral ratios and spectral ratios with respect to a reference station. A local amplification factor was estimated from Housner intensity. The study revealed a significant seismic amplification in a fault zone. This effect was observed in intensely jointed and mylonitic rock masses, located inside moderately jointed rock masses, and is the result of specific geometries and significant impedance contrasts. A map of fault zones prone to amplification of ground motion was constructed, taking into account the jointing conditions of the rock masses and the structural setting of the investigated ridge. The study relied on an integrated methodological approach, which combined the available data under union and intersection criteria.     

Landfill site selection by decision-making tools based on fuzzy multi-attribute decision-making method

Landfill site selection is a complex and time-consuming process, which requires evaluation of several factors where many different attributes are taken into account. Decision makers always have some difficulties in making the right decision in the multiple attribute environments. After identifying candidate sites, these sites should be ranked using decision-making methods. This study applies Chang’s fuzzy AHP-based multiple attribute decision-making (MADM) method for selection of the best site of landfills based on a set of decision criteria. The Fuzzy Analytic Hierarchy Process (FAHP) was designed to make pairwise comparisons of selected criteria by domain experts for assigning weights to the decision criteria. Analytic Hierarchy Process (AHP) is used to make pairwise comparisons and assign weights to the decision criteria. It is easier for a decision maker to describe a value for an alternative by using linguistic terms and fuzzy numbers. In the fuzzy-based AHP method, the rating of each alternative was described using the expression of triangular fuzzy membership functions. Once the global weights of the criteria is calculated by AHP, they are incorporated into the decision matrices composed by decision maker and passed to fuzzy-AHP method which is used to determine preference order of siting alternatives. In this study, a computer program based on the Chang’s fuzzy method was also developed in MATLAB environment for ranking and selecting the landfill site. As an example of the proposed methodology, four different hypothetical areas were chosen and implemented to demonstrate the effectiveness of the program. By using this program, the precision was improved in comparison with traditional methods and computational time required for ranking and selecting the suitable landfill site was significantly reduced.     

小浪底工程岩体力学参数研究

本文系统研究了小浪底工程的岩体的强度特征,采用了室内试验,野外结构面统计,工程地质类比法、模型试验法和Hoek Brown的经验法,估算了工程岩体的力学指标,指出了上述各种方法中所存在的不足,认为在工程实践中,应尽可能使用多种估计方法,交叉校核所得参数,以提高参数的可靠性,保证工程的安全,节约投资。     

冷生风化作用对边坡稳定性影响

The experiment shows that considerable influence on density rock properties are subjected by nival weathering conditions. The main parameter defining the rock suitability for solution various engineering and geological problems is its firmness limit on single axis pressing. The firmness properties of sandstone being in absolutely dry condition for Kabakta suite at the beginning of investigation was 64.7 MPa, for Nerungri suite sandstones it was 48. 7 MPa. The investigations showed how much the nival conditions of cryohypergenesis of rock sandstones in Kabakta and Nerungri suites have destructive influence in comparison with aquale and more over aerale conditions. In the aerale conditions sedimentary rock firmness of Kabakta suite decreased to 23.2 MPa, in aquale conditions to 16.5, and in the nivale conditions to 8.9 MPa. In Nerungri suite sandstones are according to 17.7 MPa, 11.1 MPa, and 6 MPa after 300 freezing and thawing cycles. The common sandstone firmness decrease of Kabakta suite was 25 %,of Nerungri suite it was 23.8%. Marlstone samples after 400 FTC decrease to 62% in the nivale conditions and to 33 % in the aerale conditions. After 3～5 years of exploitation marlstone will destruct due to structural and textural inhomogenesis up to gruss, i.e. it will not meet the requirements of durability.Judging by the results of carried out experiment it should be concluded that by cryogenic weathering the sedimentary rocks (sandstones) and rocks with schistose lithogenic texture (marlstone) are subjected to disintegration. The primary rock samples firmness considerably influences on the disintegration rate.     

张集线旧堡隧道工程地质条件和岩体结构特征研究

新建的张集铁路（张家口 集宁段）旧堡隧道是全线关键性控制工程,位于河北省万全县旧堡乡与尚义县土夭村之间,隧道穿越由晚太古代马市口组(Arm)麻粒岩和黑云母斜长片麻岩组成的一套高级变质岩建造,断裂构造极为发育,岩体破碎。原设计Ⅱ、Ⅲ级围岩洞段占隧道线路总长的71.8%,而已施工揭露的工程地质条件较差,全部变更为Ⅲ级加强及Ⅳ、Ⅴ级围岩,变更率高达80.3%。施工过程中多次发生挤压大变形、塌方、突涌水等施工地质灾害,共处理大塌方段8处小塌方21处计130m,处理大变形18段计550m。本文分析了DK30+520～910洞段地层岩性、地质构造、地应力、地下水等隧道围岩主要工程地质条件,从结构面和工程地质岩组的物理力学特性出发,研究了该洞段特殊的岩体结构,指出该隧道围岩岩体结构特征主要受与隧道轴线小角度相交的构造挤压破碎带及软硬交替产出的岩组控制,隧道围岩变形破坏受岩体结构控制作用明显,并总结了施工中可能遇到的几种岩体结构。该研究对类似工程地质条件地区隧道工程围岩分类、支护设计和施工有一定的借鉴意义。     

温家山莲花状构造及其岩体工程地质力学特征

地质力学在工程地质学上的应用有着广阔前景。本文在分析温家山莲花状构造体系的基础上,应用岩体工程地质力学的方法,分析和讨论了该体系内岩体结构的形成、分布和力学特征及其岩体工程地质力学条件。