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1.
The joint frequency rating index accounts for 40% of the weight in the hundred-mark Rock Mass Rating 2014 (RMR14) classification system. However, owning to the natural variations of in-situ rock mass, this parameter is difficult for site engineers to obtain along the tunnel axis, especially in groundwater-rich conditions or prior to any disturbances made to rock mass. In this study, we propose an equivalent joint frequency, expressed quantitatively in terms of the ratio of the P-wave propagation velocity in the rock mass to that of the intact rocks, which is mainly based on engineering statistics easily obtained from the Chinese National Standard, GB/T 50218. We also explore a new rating method, based on field P-wave propagation velocity tests, for the joint frequency in the RMR14 classification system. Literature from in-situ databases is discussed to verify the applicability of the proposed rating method. The verifications demonstrate that, compared with the results of on-site parameters ratings as per the RMR classification system, the new rating method using P-wave propagation velocity can obtain a certain degree of accuracy. Hence, this enables the presentation of the primary state of integrity of an in-situ rock mass in accordance with the RMR14 classification system, through simple and non-destructive field P-wave velocity tests.
相似文献2.
一种基于块体化程度理论的裂隙岩体巷道顶板稳定性分级方法研究 总被引：1，自引：0，他引：1
岩体完整性是进行巷道顶板稳定性分级的一个重要指标,当前分级方法均是从一维角度对岩体结构进行描述,不能全面刻画出三维空间上顶板围岩的完整性。针对这一缺陷,引入裂隙岩体块体化程度理论,以块体化程度代替常规标准中表征岩体完整性的岩体质量RQD值和节理间距两项子指标,开展裂隙岩体巷道顶板稳定性分级研究,创新形成了一种适用于裂隙岩体顶板稳定性分级的BT分级方法。以块体百分比和块体体积曲线为基本依据,构建出裂隙岩体巷道顶板围岩块体化程度的解算流程;运用AHP法对稳定性影响因素权重进行了排序,制定出稳定性分级方法与标准。以铜坑矿92号矿体裂隙岩体试验区巷道顶板结构面调查数据和岩石力学参数为基础,运用传统分级方法RMR法和BT法分别对各试验区巷道顶板稳定性进行评价,对两种分级结果进行比较分析,结果表明：与传统的RMR法相比,BT法在稳定性描述、分级准确性和安全管理指导作用等方面更为优越,更能够客观真实地反映出裂隙岩体巷道顶板稳定性。研究成果可为复杂裂隙岩体条件下的巷道顶板安全分级与管理提供更为可靠的科学依据。 相似文献
3.
Summary ?Strain-dependent hydraulic conductivities are uniquely defined by an environmental factor, representing applied normal and
shear strains, combined with intrinsic material parameters representing mass and component deformation moduli, initial conductivities,
and mass structure. The components representing mass moduli and structure are defined in terms of RQD (rock quality designation)
and RMR (rock mass rating) to represent the response of a whole spectrum of rock masses, varying from highly fractured (crushed)
rock to intact rock. These two empirical parameters determine the hydraulic response of a fractured medium to the induced-deformations.
The constitutive relations are verified against available published data and applied to study one-dimensional, strain-dependent
fluid flow. Analytical results indicate that both normal and shear strains exert a significant influence on the processes
of fluid flow and that the magnitude of this influence is regulated by the values of RQD and RMR. 相似文献
4.
综合灰色系统理论与传统的边坡岩体质量分级方法(SMR法),提出改进SMR法。传统的岩体质量分级方法中定量指标取值离散性很大,造成质量分级结果阶梯变化。灰色系统理论的灰度特征对解决这类小样本、离散性的问题有很好的适用性。首先对传统质量分级方法的评价指标进行灰类划分,确定各指标所占权重,再构建评价指标的三角白化权函数,并基于最大隶属度准则对边坡岩体进行质量分级。最后结合工程边坡实例,与一般工程RMR(岩体质量分级)与SMR法比较,改进SMR法的评价结果更加吻合工程现状,且质量分级稳定性高,表明其应用于边坡岩体质量分级是科学和准确的。 相似文献
5.
Changes in the hydraulic conductivity field, resulting from the redistribution of stresses in fractured rock masses, are difficult to characterize due to complex nature of the coupled hydromechanical processes. A methodology is developed to predict the distributed hydraulic conductivity field based on the original undisturbed parameters of hydraulic conductivity, Rock Mass Rating (RMR), Rock Quality Designation (RQD), and additionally the induced strains. The most obvious advantage of the methodology is that these required parameters are minimal and are readily available in practice. The incorporation of RMR and RQD, both of which have been applied to design in rock engineering for decades, enables the stress-dependent hydraulic conductivity field to be represented for a whole spectrum of rock masses. Knowledge of the RQD, together with the original hydraulic conductivity, is applied to determine the effective porosity for the fractured media. When RQD approaches zero, the rock mass is highly fractured, and fracture permeability will be relatively high. When RQD approaches 100, the degree of fracturing is minimal, and secondary porosity and secondary permeability will be low. These values bound the possible ranges in hydraulic behaviour of the secondary porosity within the system. RMR may also be applied to determine the scale effect of elastic modulus. As RMR approaches 100, the ‘softening’ effect of fractures is a minimum and results in the smallest strain-induced change in the hydraulic conductivity because the induced strain is uniformly distributed between fractures and matrix. When RMR approaches zero, the laboratory modulus must be reduced significantly in order to represent the rock mass. This results in the largest possible change in the hydraulic conductivity because the induced strain is applied entirely to the fracture system. These values of RMR bound the possible ranges in mechanical behaviour of the system. The mechanical system is coupled with the hydraulic system by two empirical parameters, RQD and RMR. The methodology has been applied to a circular underground excavation and to qualitatively explain the in situ experimental results of the macropermeability test in the drift at Stripa. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
6.
Raoof Gholami Vamegh Rasouli Andisheh Alimoradi 《Rock Mechanics and Rock Engineering》2013,46(5):1199-1209
Rock mass classification systems such as rock mass rating (RMR) are very reliable means to provide information about the quality of rocks surrounding a structure as well as to propose suitable support systems for unstable regions. Many correlations have been proposed to relate measured quantities such as wave velocity to rock mass classification systems to limit the associated time and cost of conducting the sampling and mechanical tests conventionally used to calculate RMR values. However, these empirical correlations have been found to be unreliable, as they usually overestimate or underestimate the RMR value. The aim of this paper is to compare the results of RMR classification obtained from the use of empirical correlations versus machine-learning methodologies based on artificial intelligence algorithms. The proposed methods were verified based on two case studies located in northern Iran. Relevance vector regression (RVR) and support vector regression (SVR), as two robust machine-learning methodologies, were used to predict the RMR for tunnel host rocks. RMR values already obtained by sampling and site investigation at one tunnel were taken into account as the output of the artificial networks during training and testing phases. The results reveal that use of empirical correlations overestimates the predicted RMR values. RVR and SVR, however, showed more reliable results, and are therefore suggested for use in RMR classification for design purposes of rock structures. 相似文献
7.
Shen Yan-jun Yan Rui-xin Yang Geng-she Xu Guang-li Wang Shan-yong 《Geotechnical and Geological Engineering》2017,35(6):2523-2548
The basic quality (BQ) system is regarded as the national rock mass classification system that can be appropriate for use in most types of rock engineering in China. Two underlying parameters that the uniaxial compressive strength (UCS) and the rock intactness index (KV) are taken into account to access the basic BQ value. However, The KV was usually measured by an indirect acoustic wave approach which often cannot reflected the actual conditions. In this study, a direct measured parameter KGSI is recommended to obtain by means of the GSI system to replace the original KV, and a new method [BQ]GSI expressed by the new parameter KGSI is proposed. In particular, a graphic method is also presented to determine rapidly and rationally the rock mass classification by the X, Y coordinates of the UCS and the KGSI. In order to further compare the evaluation results and application effects between the [BQ]GSI and the international rock mass classification systems, a comprehensive solution is carried out. First, the evaluation factors of rock mass qualities from all these system are classified according to three groups: the rock mass inherent parameters, external parameters, and construction parameters. Second, the correlations among these evaluation factors in the new [BQ]GSI system and the common international systems (i.e. RMR, Q, and RMi) were compared. And the formulas or charts among the three groups are presented. Finally, five hydropower underground excavations are chosen to analysis the comparison results of the [BQ]GSI system and the international common RMR, Q, or RMi systems. The applicability scope of these international RMR, Q, or RMi systems is also discussed in the context of China’s rock characteristics and geological stress conditions. 相似文献
8.
This paper presents the engineering geological properties and support design of a planned diversion tunnel at the Boztepe dam site that contains units of basalt and tuffites. Empirical, theoretical and numerical approaches were used and compared in this study focusing on tunnel design safety. Rock masses at the site were characterized using three empirical methods, namely rock mass rating (RMR), rock mass quality (Q) and geological strength index (GSI). The RMR, Q and GSI ratings were determined by using field data and the mechanical properties of intact rock samples were evaluated in the laboratory. Support requirements were proposed accordingly in terms of different rock mass classification systems. The convergence–confinement method was used as the theoretical approach. Support systems were also analyzed using a commercial software based on the finite element method (FEM). The parameters calculated by empirical methods were used as input parameters for the FEM analysis. The results from the two methods were compared with each other. This comparison suggests that a more reliable and safe design could be achieved by using a combination of empirical, analytical and numerical approaches. 相似文献
9.
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。 相似文献
10.
Evangelin Ramani Sujatha Thirukumaran V. 《Journal of the Geological Society of India》2018,91(4):489-495
Linear infrastructure networks like roads play a vital role in the socio-economic development of hill towns centered on tourism. Stability of the slopes along the hill roads are therefore a major concern and slope failures lead to disruption of traffic and loss of property/life or both. This study analyses the stability of cut-slopes along the Kodaikkanal – Palani hill road in the Western Ghats, India using rock mass classification systems like rock mass rating (RMR), slope mass rating (SMR) and continuous slope mass rating (CSMR). These geomechanical classifications provide a preliminary assessment of rock quality based on rock strength, discontinuity properties, hydrogeological condition of the slopes and slope stability based on the inherent rock strength parameters, discontinuity orientation and method of excavation. The results showed that both rock quality and discontinuity orientation contribute to type of failure in rock slopes with RMR > 40. SMR results are conservative while CSMR classification is matches more closely to the failures obtained from the field survey. CSMR classification represents continuous slope stability conditions and hence are more suitable for development of spatial database. Cutting of roads, thereby, steepening slopes has a definite influence on the stability of slopes. 相似文献
11.
Satish Kumar Kishor Kumar N. N. Dogra 《Journal of the Geological Society of India》2017,89(4):407-412
Rock slopes require geo-engineering evaluation to assess the instability of critical slopes leading to landslides particularly in Himalayan terrain where rocks are highly jointed, fractured and weathering prone. Interplay of discontinuities in the rocks coupled with other parameters is one of the prime causes of failure of slopes. Engineering rock mass classification, such as, rock mass rating (RMR) and slope mass rating (SMR) along with geological strength index (GSI) have widely been used for stability assessment of rock slopes above tunnel portals, and these classifications are employed here for assessment of stability of slopes of critical nature along Rampur-Powari highway in Himachal Pradesh. In the present study, out of 154 numbers of slopes, a total of 29 have been selected for assessment of their criticality by employing RMR, SMR and GSI. 相似文献
12.
G. Exadaktylos M. Stavropoulou G. Xiroudakis M. de Broissia H. Schwarz 《Rock Mechanics and Rock Engineering》2008,41(6):797-834
Summary Basic principles of the theory of rock cutting with rolling disc cutters are used to appropriately reduce tunnel boring machine
(TBM) logged data and compute the specific energy (SE) of rock cutting as a function of geometry of the cutterhead and operational
parameters. A computational code written in Fortran 77 is used to perform Kriging predictions in a regular or irregular grid in 1D, 2D or 3D space based on sampled data referring to rock mass classification
indices or TBM related parameters. This code is used here for three purposes, namely: (1) to filter raw data in order to establish
a good correlation between SE and rock mass rating (RMR) (or tunnelling quality index Q) along the chainage of the tunnel,
(2) to make prediction of RMR, Q or SE along the chainage of the tunnel from boreholes at the exploration phase and design
stage of the tunnel, and (3) to make predictions of SE and RMR or Q ahead of the tunnel’s face during excavation of the tunnel
based on SE estimations during excavation. The above tools are the basic constituents of an algorithm to continuously update
the geotechnical model of the rock mass based on logged TBM data. Several cases were considered to illustrate the proposed
methodology, namely: (a) data from a system of twin tunnels in Hong Kong, (b) data from three tunnels excavated in Northern
Italy, and (c) data from the section Singuerlin-Esglesias of the Metro L9 tunnel in Barcelona.
Correspondence: G. Exadaktylos, Department of Mineral Resources Engineering, Technical University of Crete, Chania, Greece 相似文献
13.
Rock Mass Classification and Slope Stability Assessment of Road Cut Slopes in Garhwal Himalaya, India 总被引：1，自引：0，他引：1
There are many rock mass classification schemes which are frequently used for different purposes such as estimation of strength and deformability of rock masses, stability assessment of rock slopes, tunneling and underground mining operations etc. The rock mass classification includes some inputs obtained from intact rock and discontinuity properties which have major influence on assessment of engineering behaviour of rock mass. In the present study, detail measurements were employed on road cuts slope faces in Garhwal Himalayas to collect required data to be used for rock mass classification of Rock Mass Rating (RMR) and Geological Strength Index (GSI). The stability assessment of rock slopes were also done by using Slope Mass Rating. In addition the relation between RMR and GSI were also evaluated using 50 data pairs. 相似文献
14.
15.
针对目前水电站地下厂房工程中不同围岩分类方法存在评价结果不一致、围岩力学参数存在室内试验值与实际情况不吻合的现象,现推荐采用岩体精细化描述体系对围岩岩体结构进行定量化评价。将常用围岩分类方法(RMR、Q、RMi、GSI、BQ、HC)评价指标予以归纳分组,并通过各组内不同指标对比分析获得围岩分类方法中的基础评价指标。以大岗山水电站主厂房某区段为分析对象,采取现场岩体精细化地质素描与后期数据挖掘、拟合相结合方法,并依据评价指标间的关联关系,获得了基础、非基础评价指标的分布概型及对应参数,实现对该段围岩岩体精细化描述认知;基于精细化描述结果,应用Monte Carlo法生成符合各评价指标分布概型的大量随机数,而后参照各分类方法评价思路与评分流程,得到评价指标在各分类方法对应的大量随机评分值,通过归纳统计获得不同围岩分类方法评价结果的分布概型;基于各围岩分类方法评价结果与力学参数值之间的关联关系实现对力学参数概率特征分析。该分析方法与思路可为类似工程围岩质量及力学参数的精确确定提供一定借鉴,并可为实现围岩支护极限状态设计提供必要的原始参数支持。 相似文献
16.
A general approach to rock engineering designing aspects adopted at the Khiritharn Pumped Storage Scheme is described. The scheme involves excavation of three large caverns and tunnels in jointed sandstone within a suture zone in Southeast Thailand. Geological condition and engineering properties of the sandstone were investigated. Strength and modulus properties of the intact rock were determined from laboratory tests and properties of rock mass were empirically estimated for the design analysis in the de.nite study stage on the basis of three rock mass classi.cation systems namely the Rock Mass Rating (RMR), Geological Strength Index (GSI) and a Japanese system (EPDC). While the GSI gives strength and modulus of deformation values slightly higher than the RMR classi.cation, the EPDC gives a lower value of modulus of deformation but comparable rock mass strength value for the level of con.ning pressures at the depth of the cavern excavation. The results of stress analysis and loosening wedge analysis for the cavern excavations suggest favorable excavation condition. 相似文献
17.
隧洞围岩分类与洞径和超欠挖之间的关系研究 总被引：5，自引：0，他引：5
岩体的地质结构特征是影响隧洞围岩超欠挖的主要因素,正确评价岩体的质量,对岩体进行分类,并研究岩体质量与隧洞超欠挖之间的关系对分析和预测隧洞超欠挖具有重要的意义。对隧洞围岩的RMR分类和Q分类与超欠挖之间的关系进行了详细研究,研究了在同类岩体条件下不同开挖洞径与隧洞超欠挖之间的关系,并由此建立了RMR分类和Q分类之间的关系,得出围岩的RMR分类和Q分类与隧洞超欠挖呈线性关系和对数线性关系,根据超欠挖建立起来的RMR分类和Q分类之间的关系比较符合工程实际。最后研究了超欠挖与围岩分类及洞径之间的复相关关系。 相似文献
18.
Assessment of the Stability of Rock Slopes by the Slope Stability Rating Classification System 总被引：2，自引：1，他引：1
Given the lack of suitable systems in the characterization of slope stability of heavily jointed rock masses, a new rock mass
classification system called Slope Stability Rating (SSR) is proposed. In addition to the so-called modified Geological Strength
Index, the proposed system considers five additional parameters whose relative effects on the stability of fractured rock
slopes were precisely examined based on data retrieved from eight different rock slope sites in Iran. An overall rating for
the rock mass is obtained from the summation of the individual ratings of each parameter. A number of design charts are provided
as illustration. The new system was then validated based on 46 slope case histories from Iran and Australia. For this, by
means of the design charts previously mentioned, a recommended stable angle for each slope was given and compared with the
current slope conditions. As a result, SSR design charts for maximum excavation angle (FS = 1.0) and also for other more conservative
excavation angles (FS = 1.2, 1.3, 1.5) were presented. 相似文献
19.
Analysis of support requirements for a shallow diversion tunnel at Guledar dam site, Turkey 总被引：2，自引：0，他引：2
Engineering geological properties and support design of a planned diversion tunnel at Guledar dam site, which was located at the North of Ankara, Turkey were studied in this article. The main purpose of the construction of the planned tunnel is to regulate, drainage and to provide water for irrigation purposes. The diversion tunnel runs mainly through formations of limestone, sandstone and diabase. Rock masses at the site were characterized using Rock Mass Rating (RMR), Rock Mass Quality (Q), Rock Mass Index (RMi) and Geological Strength Index (GSI). RMR, Q, RMi and GSI were determined by using field data and mechanical properties of intact rock samples, measured in the laboratory. Support requirements for the planned diversion tunnel were determined accordingly in terms of the rock mass classification systems. Recommended support systems by empirical methods were also analyzed using 2D Finite Element method. Calculated parameters based on empirical methods were used as input parameters in the finite element models. The results from both methods were compared with each other. This comparison suggests that more reliable support design could be achieved by using the finite element method together with the empirical methods. 相似文献
20.
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. 相似文献