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1.
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
2.
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
3.
《Engineering Geology》2001,59(1-2):161-172
This paper presents the results of preliminary support design of the subway tunnel for Ankara subway project in accordance with some empirical and numerical methods, using the phase 2D finite element method (FEM). The 5 m diameter subway tunnel will advance through slightly to moderately weathered dacite and weak zones. Rock masses were characterized in terms of rock mass rating (RMR), geological strength index (GSI) and Q System. Core samples were tested in the rock mechanics laboratory to determine uniaxial compressive strength, deformability parameters, unit weight, tensile strength and triaxial compressive strength properties. Finally, rock mass strengths were determined by empirical and numerical methods. Required support system was suggested. 相似文献
4.
In this paper a detailed engineering geological assessment of rock masses and support design studies at Garmi Chay dam site, has been carried out. This project is located in the northwest of Iran and will be used for flow control and water storage. The diversion tunnel of the dam has a diameter of 5.5 m and a length of 420 m and will be driven in slightly to highly weathered micaschist and trachy andesite rock units. The geological studies include field and laboratory investigations that based on the results; for more exact investigation, tunnel alignment was divided into three geotechnical zones. These zones consist mainly of highly weathered gray micaschists, dark red trachy andesites and slightly weathered gray micaschists, respectively. Then, for every zone, support capacity of rock masses was evaluated by means of empirical and numerical methods. The rock mass classification systems (RMR, Q, GSI, RSR, SRC and RMi), the convergence–confinement method and a 2D finite element computer software, Phase2 were used for empirical and numerical method, respectively. According to the results acquired from these methods some stability problems were expected in the tunnel especially in highly weathered micaschist zone, so that in practice two big collapses occurred. Because of high weathering, low constants of rock masses and their soil-like behavior, the stability analysis by analytical method does not give illogical results in lightly weathered micaschist zone. The support system, suggested by empirical method, was applied and its performance was evaluated by means of numerical modeling. After installation the support suggested by Phase2 program, the thickness of plastic zone and deformations around the tunnel decreased significantly. Consequently the agreement of these methods with each other was resulted and using combination of them was recommended for more reliable support design. 相似文献
5.
Engineering geological studies and tunnel support design at Sulakyurt dam site, Turkey 总被引：2，自引：0，他引：2
H. Basarir 《Engineering Geology》2006,86(4):225-237
This paper presents the results of engineering geological investigations and tunnel support design studies, carried out at the Sulakyurt dam site, northeast of Ankara, Turkey. The Sulakyurt dam will be used for flow control and water storage for irrigation projects. Studies were carried out both in the field and the laboratory. Field studies include engineering geological mapping, intensive discontinuity surveying, core drilling and sampling for laboratory testing. The diversion tunnel will be driven in rock mass, consisting of granite and diorite. Empirical, analytical and numerical methods were combined for safe tunnel design. Rock mass rating (RMR), Rock mass quality (Q) and Geological strength index (GSI) systems were used for empirical rock mass quality determination, site characterization and support design. The convergence–confinement method was used as analytical method and software called Phase2, a 2D finite element program, was utilized as numerical method. According to the results acquired from the empirical, analytical and numerical methods, tunnel stability problems were expected in both granite and diorite rock masses. The support system, suggested by empirical methods, was applied and the performance of suggested support system was evaluated by means of numerical modelling. It was concluded that the suggested support systems were adequate, since after applying the suggested support system to granite and diorite, tunnel deformation and the yielded elements around the tunnel decreased significantly. Thus, it is suggested that for more reliable support design empirical, numerical and analytical methods should be combined. 相似文献
6.
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
7.
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
8.
In this paper, preliminary support design of Kaletepe tunnel, located on Bilecik-Istanbul highway, Turkey, was analyzed by empirical and numerical methods. The rock mass rating (RMR) and rock mass quality (Q) systems were employed for empirical rock mass quality determination. Numerical analysis for the stress–strain distribution of the tunnel excavation and support systems was also carried out. The applied support performance was investigated at different sections of the tunnel route. It was seen that empirical and numerical approaches showed similar results. This indicates that when the empirical method is supported by numerical method, the preliminary support design will be more reliable. 相似文献
9.
An empirical method for design of grouted bolts in rock tunnels based on the Geological Strength Index (GSI) 总被引：4，自引：0，他引：4
The procedure presented in this paper has been developed for the design of grouted rock bolts in rock tunnels during preliminary design stage. The proposed approach provides a step-by-step procedure to set up a series of practical guidelines for optimum pattern of rock bolting in a variety of rock mass qualities. For this purpose, a new formula for the estimation of the rock load (support pressure) is recommended. Due to its wide-spread acceptance in the field of rock engineering, the Geological Strength Index (GSI) is adopted in support pressure equation. For poor and very poor rock mass where the GSI < 27, the use of Modified-GSI is, instead, recommended. The supporting action is assumed to be provided by rock bolts carrying a total load defined by the rock load height. The mechanism of bolting is assumed to rely on roof arch forming and suspension principle. Integrated with support pressure function, the bolt density parameter is modified in order to provide an optimized bolt pattern for any shape of tunnel. The modified bolt density can also be used in analysis of a reinforced tunnel in terms of Ground Reaction Curve (GRC) in such a way as to evaluate the reinforced rock mass and the tunnel convergence. By doing so, the effectiveness of the bolting pattern is well evaluated. The proposed approach based on GSI is believed to overcome constrains and limitations of existing empirical bolt design methods based on RMR or Q-system, which are doubtful in poor rock mass usage. The applicability of the proposed method is illustrated by the stability analysis and bolt design of a rail-road tunnel in Turkey. 相似文献
10.
It is a well known fact that rock mass properties influence the process of fragmentation considerably. Model blasts and field investigations were carried out to find the effects of rock mass quality and joint orientation on tunnel blasting. Propagation of shock waves are partially restricted by joint planes. It was observed that the blast results (i.e., average fragment size and depth and cross-sectional area of the broken zone) were considerably influenced by joint orientation. Accordingly, it has been concluded that loading equipment with a larger capacity and deeper blast holes are required in formations with joint planes perpendicular to the tunnel axis. The number of blast holes, however, should be greater when joints are parallel to the tunnel axis. Furthermore, the powder factor (kg/m3) has been found to be directly related to rock mass quality (Q). Optimisation of pull, powder factor and overbreak is required in the case of weak formations with joints perpendicular to the tunnel axis. The use of contour blasting technique seems to be essential in poor and fair rock masses to minimise the overbreak, reduce the support cost and improve the stability of the opening. 相似文献
11.
ABSTRACT The local site experience is a valuable component for the success of rock mass classification systems as tunnel design methods. The Ituango hydroelectric project is a very important source of information in order to evaluate the usefulness of the main rock mass classification systems. The objective of this research is to improve understanding of some important features of excavated rock mass, such as discontinuities, block size, shear strength and joint alteration, by analyzing some hundreds of data obtained during excavation cycle. The field study included a survey of exposures after drilling and blasting rounds. Rock mass classification and support measures for each type of terrain along 1400 m tunnel were performed. The rock mass classes could be better explained if shear strength, alteration or block size is calculated. The assessment of these data allows evaluating the block fall risk, improving support and liner. A local correlation between the RMR and Q system was also obtained. 相似文献
12.
《Geomechanics and Geoengineering》2013,8(1):46-52
It is often difficult to directly obtain specific design parameters of interest. In these situations, estimation based on empirical correlations is an alternative. The deformation modulus of a rock mass, which is important to know for engineering projects, is measured by in situ tests, such as plate bearing, flat jack, pressure chamber, borehole jacking and dilatometer tests. Nevertheless, these in situ tests are expensive, time consuming and sometimes even impossible. Many attempts have been made to estimate the E modulus using easy-to-obtain parameters of a rock mass. This paper reviews previous studies and the equations that have been developed. In addition, this study presents a new relation developed using a database of 82 dilatometer test results gathered from two dam sites and a tunnel site. Statistical analyses were performed to correlate accessible rock parameters with measured E modulus values from in situ tests. Knowing that discontinuity characteristics and the strength of rock materials are the most important contributors to rock deformability, the focus was on identifying parameters that are affected by the mentioned properties. Among the tested parameters, RMR (Rock Mass Rating) showed the best correlation with the E modulus. Statistical analyses resulted in a new empirical equation that has an acceptable estimation ability. 相似文献
13.
采用非饱和的渗流应力耦合模型分析了糯扎渡水电站2#导流洞的开挖过程,导流洞部分洞身穿过节理带,洞顶水头较高。详细地讨论了高水头和节理带对施工过程的影响。节理带采用描述高密度平行节理组的各向异性节理本构来逼近;考虑开挖引起的介质变形对渗透系数的影响;考虑排水引起的饱和度变化对渗透系数的影响。所用的非饱和瞬态耦合模型可以模拟出开挖引起的EDZ区域孔隙水压力急剧升高、有效应力减小、渗透系数动态的变化以及排水对洞室稳定性的提高。数值模拟的计算结果与国外类似试验的一般性观测结论相吻合,因此,可以用来评价水位以下隧洞施工方法和施工速度的合理性和经济性。 相似文献
14.
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
15.
深部土岩接触带是指厚表土底部一定厚度的土层及其下一定厚度的煤系风化岩组成的土岩组合体。由于它由高压态土体、高压水和软弱破碎风化岩体组成,故具有整体不良的工程地质性质,在接近该带下采煤时易发生采场顶板矿压突变剧增、突泥溃砂、突水等重大安全问题。在煤田地质勘探资料的基础上,根据深部土层土性和岩层岩性将深部土岩接触带划分为4种类型：砂土-砂岩接触类型、砂土-泥岩接触类型、粘土-砂岩接触类型、粘土-泥岩接触类型,分析了每一种土岩接触带类型对应的工程地质意义,并对丁集矿井西南区13-1煤层的土岩接触带类型进行了划分,认为13-1煤层土岩接触带类型以砂土-泥岩、砂土-砂岩为主,近松散层工作面受到底含水的威胁比较严重,工作面溃泥、溃砂、压架出水的可能性比较大,开采设计时要充分考虑。 相似文献
16.
The results of geotechnical explorations, engineering geological investigation (including laboratory and in situ tests) and
field observations have been used, along with borehole logging charts, to obtain the rock mass geotechnical data. Based on
the data, the rock mass along the Sabzkuh water conveyance tunnel route was classified by rock mass rating (RMR), Q-system
(Q), rock mass index (RMi) and geological strength index (GSI) (3 methods). A new series of correlations were established between
the systems based on the data collected from the study area. These relationships were then compared with those reported in
the literature, and two new relations were recommended. The classifications were utilized to calculate mechanical properties
(rock mass strength and deformation modulus) of the rock mass along the tunnel according to available empirical relations,
and to distinguish the upper-bound and lower-bound relations. 相似文献
17.
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18.
Faisal I. Shalabi Husam A. Al-Qablan Omar H. Al-Hattamleh 《Geotechnical and Geological Engineering》2009,27(2):237-248
Lining contact pressure and ground deformation of Raghadan transportation tunnel (Amman, Jordan) were investigated. The tunnel
is 1.1 km in length and 13.5 m in diameter. This study was intended to integrate useful relations among the widely used rock
classification system (RMR: rock mass rating), Hoek–Brown classification, and lining-ground interaction. The materials encountered
along the tunnel alignment were limestone, dolomatic limestone, marly limestone, dolomite, and sillicified limestone. The
ground conditions along the tunnel alignment including bedding planes, joint sets and joint conditions, rock quality, water
flow, and rock strength were evaluated based on the drilled boreholes and rock exposures. Elasto-plastic finite element analyses
were conducted to study the effect of rock mass conditions and tunnel face advance on the behavior of lining-ground interaction.
The results of the analyses showed that lining contact pressure decreases linearly with the increase in RMR value. Also the
results showed that tunnel lining contact pressure and crown inward displacement decreases with the increase in the unsupported
distance (distance between tunnel face and the end of the erected lining). Ground displacement above the tunnel crown was
found to be increases in an increasing rate with the decrease in the depth above the crown. This displacement was also found
to be affected by the RMR value and the unsupported distance. 相似文献
19.
针对现有方法在上软下硬岩质地层中浅埋大跨隧道松动压力计算方面存在的问题,通过离散元数值模拟和正交试验,分析了围岩的松动破坏机制、风化层厚度和岩体中节理分布状态对隧道松动区形状和范围的影响规律及敏感性。结果表明：影响松动区的主要因素依次为风化层厚度、隧道埋深、贯通倾斜节理的倾角和间距、风化层水平节理间距;松动区可分为拱形和塌穿形两种类型,其边界曲线分别可用抛物线和乘幂函数近似表示。针对塌穿形松动区,通过回归分析建立了地表松动宽度和拱顶松动土条水平长度的计算公式。按照应力传递原理,在松动区内以梯形微分岩土条为对象,通过分层积分,推导出可反映节理产状和风化层厚度影响的浅埋大跨隧道围岩松动压力计算公式。工程实例计算表明,与现有方法相比,所提方法计算的松动压力值最小。 相似文献
20.
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