Abstract The authors proposed a new rock mass classification named as Rock Mass Quality Rating (RMQR), which consists of six main input parameters, quantifies the state of rock mass and helps to estimate geomechanical properties (UCS, cohesion, friction angle, deformation modulus, Poisson's ratio, tensile strength) of rock masses using a unified formula considering RMQR together with intrinsic geomechanical properties of intact rock. The comparisons of the empirical formula together with the values of constants were found to be quite consistent with the experimental results for data compiled from various rock engineering projects in Japan. Based on the databases of the authors, the application of the system was also extended to rock support selection for underground caverns and tunnels by considering the type of instability mode in relation to RMQR value. Some empirical relations, established between RMQR and dimensions of the elements of support systems, seem sufficient for many engineering applications and act as guidelines.

Abstract The rock-mass disturbance due to engineering activities is an important factor to estimate strength and deformability of rock-mass. Blasting practice in underground hard-rock mining is very common and so as disturbance generated due to blast. Degree of disturbance due to blasting varies with different rock type, rock characteristics and properties and blast characteristics. To estimate the most realistic strength and deformability of rock-mass in underground hard-rock it is necessary to estimate the extent of disturbance. However quantification of disturbance factor has been done already using factors such as geological strength index and uniaxial compressive strength of rock-mass which gives value of disturbance factor as 0 for good blast and 1 for poor blast. Previous quantification approach provides general values of disturbance factor "D" with limited factor however approach gives very strong and clear background for further research. Also previous research helps in providing comprehensive information about the disturbance in rock-mass.This paper includes numerical and empirical estimations using real-time data from underground hard-rock mine and hence provides a new relationship to quantify the value of disturbance factor "D". In this paper rock-mass characterization, rock properties and blast characterization are taken into account. Elemental analysis has been done on major factors associated with rock-mass characterization, rock properties and blast characteristics which affect disturbances in rock-mass due to blasting. Accordingly rock-mass characterization influences blast 54% whereas rock properties and blast characterization influence 28% and 18%. Result shows that rock-mass with different characteristics and properties behave differently with blast characterization and hence the degree of disturbance generated due to blasting changes accordingly.

Abstract Drying induced deformation is a well-known coupled process of deformation and moisture transfer within a porous material. It is important to be able to predict the drying shrinkage behavior to overcome engineering issues associated with desaturation of soft sedimentary rocks, which are porous and low in strength. However, researchers focus more on simulating the moisture transfer or suction evolution during the drying process of soft rocks and contribute less on drying shrinkage estimation. Hence, an existing micromechanical model which was used to analyze the drying shrinkage behavior of concrete was adapted and modified to model the shrinkage behavior of soft sedimentary rocks. Shrinkage estimation of Tage tuff during drying at 50 °C and with 50% relative humidity is presented in this paper. Development of capillary stress in water filled pores due to evaporation is the leading cause of shrinkage. Hence, the pore structure is the most important factor to consider when estimating the drying shrinkage. Therefore, pore size distribution determined by the mercury intrusion porosimetry was used to represent the pore structure of Tage tuff during shrinkage estimation. Moreover, a linear elastic relationship between capillary stress and shrinkage was assumed during the formulation of equations. However, ultrasonic wave velocity measurement results indicate that the elastic parameters during drying are not constant. Hence, the elastic modulus for capillary stress was assumed to be varying with saturation and was estimated by back calculations. Results indicate that the mercury intrusion porosimetry determined pore size distribution can adequately represent the shrinkage evolution of Tage tuff. Moreover, the elastic modulus due to capillary stress follows 1-tanh relation with the drying shrinkage. The capillary stress indicates linear elastic behavior with very small shrinkage, but when the shrinkage increases, the elastic modulus decreases. Thus, the elastic modulus due to capillary stress varies according to the shrinkage level of Tage tuff. However, the estimated elastic modulus for capillary stress indicates lower values and dissimilar behavior when compared with ultrasonic wave velocity calculated elastic parameters. Furthermore, it is necessary to consider the surface tension changes due to increasing concentration of dissolved ions in pore water during desaturation.

Abstract Blasting is the most commonly used excavation technique in mining and civil engineering applications. In this study, the authors applied a new system consisting of accelerometers, which are compact and standalone type to monitor the blasting-induced vibrations and investigate if it is possible to evaluate the characteristics of surrounding rock masses in a Taru-Toge tunnel in Central Japan. In addition, the damage around the blasted holes may be used to infer in-situ stresses. The authors also attempted to infer in-situ stresses using the damage of blasted-holes and compared with those from AE method and other techniques. The authors will describe the outcomes of these studies in the paper and discuss the implications in tunneling.

Abstract Fault-slip induced by mining activities in underground mines could inflict severe damage to mine openings. In order to estimate the occurrence of fault-slip related seismic events, a better understanding of fault-slip potential in active mining areas is of importance. In the present paper, the variation in fault-slip potential induced by ore extraction in underground mining is examined with a 3D mine-wide model encompassing a steeply dipping tabular orebody at a depth of 1.5km below surface, and in situ stress conditions that are typical of the PreCambrian Shield. The fault is assumed to run parallel to the orebody. Static analysis is first carried out, in which stopes on a given sublevel are sequentially extracted from the center of the orebody in an outward direction. It is shown that when the first stope is extracted, a significant increase in fault-slip potential takes place within 10 m from the stope boundary, beyond which the mining-induced change in fault-slip potential drastically decreases. The area is thus considered a high risk for fault-slip due to the local unclamping effect triggered by stope extraction. As the mining sequence proceeds, a regional unclamping effect takes place and results in additional increase in fault-slip potential at the observation points. The change in fault-slip potential normalized by the shear strength eventually reaches 0.1 at a point 60 m away from the orebody. Thus, for the mining depth and field stress adopted in this study, it can be said that the range between 10 and 60 m away from the orebody represents moderate risk area for fault-slip, whereby the fault slip might be reactivated due to the regional unclamping effect induced by extracting a large volume of the orebody. Beyond this range, it may be assumed that the risk of fault-slip is quite low, and fault-slip could occur only if the stress state of the fault is critical before mining activity begins.

Abstract Cutter forces have an indispensable place in mechanical excavation, especially selection of excavating machine. During mechanical excavation, three-dimensional forces occur on the cutter. These are cutting force or rolling force (FC and FR), normal force (FN) and sideway force (FS). Cutting force and normal force is very important variables such that torque and thrust capacity of mechanical excavator is determined via these variables in design stage. Cutter forces can be calculated or measured practically or theoretically. In laboratory rock cutting tests, cutter forces occurring on index or real cutters can be determined practically. These rock cutting tests are, full scale rock cutting test and small scale rock cutting test. Cutter forces are found theoretically by cutting theories developed by some researchers. Best way of determining cutter forces is laboratory rock cutting tests but they could be found in a few research centers around the world. So researchers are searching alternative ways of determining cutter forces. In this study, six different rock samples are conducted to laboratory tests for determination of physical and mechanical characteristics. During this experimental period, uniaxial compressive strength, Schmidt hammer rebound value, uniaxial tensile strength, unit weight and apparent porosity parameters are determined. As well, same rock samples are conducted to small scale rock cutting test and cutting force and normal force is measured during cutting test. Data which are obtained from these tests are analyzed in SPSS program and multivariate linear regression formula are developed for cutting force (FC) and normal force (FN) both. These multivariate formula include three parameters which are uniaxial compressive strength, Schmidt hammer rebound value and apparent porosity. Other parameters (uniaxial tensile strength and unit weight) were not entered through regression. Multivariate linear formulas were tested via ANOVA test and passed this test.

Abstract One of the major problems during the construction and operation of reservoirs, which can undermine the water maintainability, is related to water seepage from the reservoir. In pumped storage power plant, due to connect between upper and main reservoir, water seepage from upper reservoir have a significant effect on the efficiency of the power plants to produce energy. The objective of this research is to estimate water seepage from the upper reservoir of Rudbar pumped storage power plant, based on combined geological and geotechnical investigations using numerical and analytical methods. Geological investigations show that the upper reservoir consists of limestone and marly limestone. Obtained data of seven exploratory boreholes and seven joint measurement stations have been considered as the main source for seepage calculations in analytical method and distinct element method (DEM), respectively. The input data such as permeability of layers and the hydraulical and mechanical properties of discontinuities has been obtained from measured data. Results from both methods (analytical and numerical) have an appropriate consistency together. The estimated seepage from analytical method and DEM is around 348,000 m 3 /day and 280,000 m 3 /day, respectively. Due to the high amount of water seepage and economical value of Water in this region, water tightening is necessary.

Abstract Two examples of inverse problem technique application to geomechanical tasks concerned with rock mass characterization were considered. An approach to estimating geometric parameters of underground voids formed in soil under natural or anthropogenic influence was offered. Irreversible deformation of soil is modeled using discrete element method. The formulated inverse problem on finding void geometry and occurrence depth by the data on configuration of the subsidence trough has unique solution. Based on geomechanical model of gas migration in block coal bed, the inverse problem was formulated for estimation of diffusion-capacity parameters (gas content, coefficients of diffusion and mass exchange) by the pressure measured in degassing borehole. The numerical analysis of cost function using synthetic input data revealed the necessity of the additional information on coal bed gas-kinetic properties for the inverse problem to be unambiguous solvable.

ABSTRACT To provide a practical tool to estimate the rock mass strength for use with the Hoek-Brown failure criterion, the GSI system was introduced. A GSI value is determined from a chart based upon the structure interlocking and joint surface conditions. Continuous fractures usually occupy only a part of the surface of the joint plane within a given rock volume. In jointed rock masses, rock bridges exist due to the non-persistent nature of joints. However, joints are often assumed to be fully persistent for stability analysis of rock structures such as tunnels or slopes. This oversimplification may lead to an overestimation of the number of removable blocks near the excavated face, resulting in excessive expenditure on the rock support. The objective of this study is to analyze how joint persistence will increase the overall rock mass strength in jointed hard rock masses; the study will focus on the influence of joint persistence on the residual strength of rock bridges. An equivalent rock mass strength, considering joint persistence, is obtained analytically and compared with the results from the numerical analysis. Correlation analysis is then performed to relate the rock mass strength to the characteristics of joint persistence and the results are compared to those from the GSI system considering joint persistence. As a result, GSI can vary by as much as 30% depending upon joint persistence.

ABSTRACT Tunnel stability should be estimated and expressed by two curial points, tunnel deformationand stress distribution of rock mass around tunnel, through theoretical studies(Gioda, G.and Locatelli, L., 1999; Sterpi., D., 1999; Kim, Sang-Hwan, 2003) and many case studues(Song et al., 2002; Wang,Yi-Wan,2001) on tunnel deformation analysis until the recent. For the first point, some hybrid analysis was proposed by a conjugated method about the critical strain analysis by Sakurai(1988,1990,1997), 3D numerical simulation, field measurement on tunnel excavation, and stability analysis of stress-strain relation based on elastic theory.For the second point, recently successful cases on tunnel excavationin South Korea were introduced. Also, as an new approach about 2 arch conventional tunnel, positive effects of pre-supporting system were respectively introduced relating to the conventional method. Thekey items about the utilization of field measurement on tunnel coustruction and the choice of tunnel excavation methodon primary design were conclusionally summaried and suggested.

Abstract: There are a lot of complex problems involving a number of conflicting factors when planning a TBM drive in squeezing ground. In this respect, numerical analyses represent a helpful decision aid. In the present paper, Beheshtabad water transmission tunnel is introduced, and mechanized full face and drill and blast excavation challenges in squeezing ground are investigated. Then the geomechanical rock mass parameters in the 19th zone are determined. In following, the approach to thrust evaluation and effective parameters on that is discussed, and the required thrust for penetration in the work face on the basis of advance rate, cutterhead geometry and compressive and tensile strength of the host rock is calculated. Then the numerical analysis pattern and the achieved results are investigated. According to these results, if three and ten cm overcutting were performed in the most and least favorable geotechnical condition respectively, double shield TBMs could be used in the 29030–31600 and the 34900–37490 Km of the tunnel. In the 31600–34900 Km, utilization of single and double shield TBMs is not possible, and decision on the usage of double and single shield TBMs in this section could be made if an exploration gallery were planned, and additional insitu tests were done for the determination of long term parameters of the host rock. 1. INTRODUCTION The requirement of water in the central part of Iran has increased because of Increasing of population, industry concentration, decreasing water quality and underground water level reduction in this area. To provide the water necessities for human, industrial and agricultural, the Beheshtabad water transmission tunnel which its length and lined Diameter is 65 Km and 6 meter respectively is under investigation. In accordance with overground and underground investigations, geophysics studies, drilled boreholes and engineering geology mapping, the tunnel route is broken up to 29 zones. The high squeezing conditions in the 19th zone will take place according to high tunnel convergence, which is obtained by close form solution, because of high overburden and weak geotechnical conditions. The tunnel in this chainage will be excavated by TBM and for machine type selection, calculation of the required thrust for excavation is essential, so in this research, according to 3, 5 and 10 Cm over excavation in the 19th zone, the necessary thrust and appropriate method of excavation are determined. 2. EXCAVATION PROBLEMS IN SQUEEZING GROUND Squeezing refers to the phenomenon of large time dependent deformation during tunnel excavation. It occurs mostly in week rocks with high deformability and a low strength, often in combination with a high overburden. In addition, there are considerable challenges for tunnel excavation if tunnel convergence exceeds 5 percent due to high squeezing conditions [1]. Various types of TBMs have different challenges in squeezing ground according to their thrust and existence or inexistence of the shield. Also drill and blast technique in contrast to mechanized full face excavation has flexibility in over-excavation quantity, but on the downside, the advance rate of this method is very slow.

ABSTRACT Accurate estimation of the reservoir parameters is a basic problem in reservoir studies and reservoir scheduling. So consideration of the parameters which would affect the reservoir parameters is too much important for such estimation. In the present paper, several tools such as petrophysics evaluation stages, ptrophysical logs, saturation equations and corresponding parameters were used for determination of reservoirs parameters. One of the most prominent and effective parameters is the group of Archi coefficients (m, n and a). These coefficients play an important role in calculation of reservoir values. Any error made in the calculation of these parameters, can change the reservoir volume to an unacceptable value. Within the above mentioned group, the cementation exponent (m) acts as an essential value which under affect porosity, Saturation and rock types determination. In the present study an effort is made to investigate the effects of this parameter on results of the petrophysics evaluation carried out in one of the fields of the Sarvak formation. To do so, first using several tools, the cementation exponents were estimated and then the variation trends of the reservoir parameters, which were posed by the m values were studied. Finally the best tool which gave the most convenient values for m was recommended for the Sarvak formation in particular studied field. Introduction The main goal of the present study is to determine two important parameters of the Sarvak formation including: porosity and water saturation. Here an effort is made to execute a sensitivity analysis considering the Archi parameters which are known as some important parameters in evaluation of the characteristics of the above mentioned reservoir. To do so, different tools such as core analysis results, governing equations, default parameters and mathematical methods have been used. Archi parameters including: a, m and n are usually gained through the core analysis [1], otherwise the default values are used in this manner. Such parameters vary for different kind of rocks. Following is the Archi parameters for the Carbonates and sandstones: For the carbonates the a, n and m are equal to 1, 2 and 2 respectively and for the sandstones these values change to 0.62, 2 and 2.15.[4] Cementation factor (m) is one of the factors involved in the calculation of the water saturation and as a result the in evaluation of the initial Hydrocarbon in place. Various methods are created for the computation of the m value and using it in the evaluation of the hydrocarbon reservoirs. Some of these methods get use of the default values. The bases of such values are different equations such as: Archi, Homble, Shell and etc. using the default values which means the constant value for parameter m in each case, gives a proportional distribution of the possible error over the entire reservoir.

Abstract. The paper presents a view on applications of stochastic finite elements(S.F.E.)⊂ R3 in one complex system, considering a differential equation with random parameters, () Q t g t V d z V y V x k y z k x y k x x y z x y z = ∂ ∂ − ∂ ∂ − ∂ ∂ − ∂ ∂ − ∂ ∂ − ⎟⎠ ⎞ ⎜⎝ ⎛ ∂ ∂ ∂ ∂ + ⎟ ⎟⎠ ⎞ ⎜ ⎜⎝ ⎛ ∂ ∂ ∂ ∂ + ⎟⎠ ⎞ ⎜⎝ ⎛ ∂ ∂ ∂ ∂ φ φ φ φ φ α φ φ φ 2 () () where, x, y, z are the 3D spatial coordinates,. t- the processes time φ =φ ( x , y , z , t ) is a process function (temperature, pressure etc) Kij- the conductivity tensor.In general case it is: zx zx zz yx yy zz xx xy xz K K K K K K K K K K = (12), d- capacity coefficient (function),g- mass coefficient (function),Q- density of the volume flux, V –velocity vector. This equation in specific conditions goes to: - non stationary fluid flow in porous medium (or / and), - mass transport (or /and) - heat transfer (or/and) - vibrating system etc. The paper contains: 1-An approach of the mean value estimation of the parameter distributions, using S.F.E.. The next is defined as a block vi, with the random function Z(x), where x∈vi. is a random variable i.e. the value at point x determines the respective probability distribution p(x). After the estimation of the mean value over the domain vi, is calculated by zvi = ∫ i v i Z x dx v 1 () (1) 2.-Development of the numerical model using S.F.E. applying a mixed algorithm at the, i.e. it is applied. the Galerkin,s approach not "as a whole" as it is often happened in the literature[3][15], but partly, combining it with other numerical procedure as Runge-Kutta of the fourth order etc. In this treatment, the initial and boundary conditions have been supposed to be treated specifically according by the given problem. 1286 3.- Several simple examples as particular case of the mentioned equation. 4.-Conclusions, the good things of the S.F.E in stationary flow, mass transport, heat transfer, vibrating, subsidence, waving, deformations, consolidations, earthquakes and other phenomenon's. Introduction. Some processes are complex, as non stationary flow, mass transport, heat transfer, vibrating, subsidence, waving, deformations, consolidations, earthquakes and other geodynamics, reservoir engineering [1][14][16] Their complexity depend on their random mechanical, physical, chemical etc parameters, relations between them, their risk state etc.. Several processes could be deterministic, other ones stochastic, several could be studded "separately and independently" as the simple heat conduction, one phase fluid flow in porous medium etc.

ABSTRACT On the ground surface, microtremors generated by various causes are existing, and those microtremors are affected by the structure and the characteristic of the ground. The microtremor survey method is the technique to grasp subsurface S-wave velocity structure by microtremors of the ground surface. The observation work of this exploration is only limited to observing the natural microtremor of ground surface by a few number of seismometers. No large scale instrument is necessary. These facts make the exploration method simple, easy and non-destructive. This exploration method can be applied for the depths of several meters to several thousand meters underground which is a very wide range. This exploration method has been used in deep part structure survey for earthquake disaster prevention as well as shallow ground survey. This lecture introduces some implementation case examples about applying microtremor survey method at alluvial ground, deep part structure survey and fault survey. 1. Introduction Geophysical exploration method uses the physical properties of ground in order to estimate the geological structure of ground. In the method of using elastic wave, refraction seismic survey or reflection seismic survey can be done. The kind of elastic wave to apply is body wave (Swave or P-wave) generated by an artificial vibration source and using many seismometers. Especially in the deep part seismic survey, in order to improve the S/N ratio, the hardware and software will be required at large scale and survey cost will become at large amount. In the microtremor of the ground surface, the surface wave is predominant compared to the body wave, which this surface wave is used in the microtremer survey method. The surface wave has dispersion characteristics (propagation velocity changes with frequency), which at low frequencies reflects the situation of the deep part of ground. As for the surface wave, seismometers are installed on the ground surface and microtremor will be observed. Then the dispersion characteristics of the surface wave will be extracted. The S-wave velocity structure can be obtained by inverse analysis of dispersion characteristics of surface wave. The advantages of microtremor survey method are as the followings The observation instrument is small (there is no need to vibration source, there are a few simultaneous observation points) Noise resistant (practicable in rural and urban areas) Time period required for operation and analysis is short In addition, from what can be obtained from the S-wave velocity structure, the estimation of ground's engineering elevation or dynamic characteristics is possible which indicates the extreme efficiency of the geophysical exploration method. Here, examples about seismic basement survey as well as active fault survey related to the estimation of engineering basement for alluvial ground, ground of Shinkansen line at the 2004 Niigata Chuetsu earthquake and the 2007 Niigata Chuetsu-oki earthquake are given.

ABSTRACT Rock mass deformation has a major impact on rock mass behavior. Different in situ experiments were carried out at various scales to determine the deformation modulus in Bakhtiary dam. These experiments are extremely costly and time-consuming so it is favorable to forecast this parameter with high accuracy and precision. In this paper the spatial structure of deformation modulus, which was obtained from plate load tests, was investigated at Bakhtiary dam and hydro electric power plant using variogram function that is the representative dispersal of variables. Then the deformation modulus was modeled and estimated using geostatistical estimator (Kriging). Also the Kriging error distribution function was calculated. The results indicated that the estimation was reliable and the forecasting accuracy and precision were acceptable. 1. Introduction The deformation modulus of a rock mass is an important input parameter in any analysis of rock mass behaviour that includes deformations such as dams, tunnels and etc. Field tests to determine this parameter directly are time consuming, expensive and the reliability of the results is sometimes questionable. Therefore, study on deformation modulus variations and create a model to estimate that has been considered. Geostatistics is an interpolation method developed for estimating values of a parameter of interest using a limited set of data. It assumes that a spatial relationship exists within the data set. Geostatistical methods are obtained powerful tools for studying on variability of any parameters and estimating that. These methods are more popular in mining engineering since the 1970s, and currently they are applied in many fields of earth science, particularly in the hydrologic and environmental studies. Cromer [1] advocated the use of geostatistics in addressing geotechnical problems specially when interpretation derived from the spatial distribution of data has impact on decision making. Harrison and Hudson [2] gave illustrative worked examples on the use of geostatistics and stressed the under-utilization of geostatistical methods in rock engineering. In this study, based on deformation modulus parameter and considering these as spatial data, geostatistical analysis was performed on these values with using geostatistical software (WinGslib), and then according to variograms specifications were created models for estimating the deformation modulus in various area of Bakhtiary dam site. 2. Bakhtiary Dam Site The site of Bakhtiary dam and powerhouse is located in Lorestan province, southwest of Iran. The project site is almost 100 km to Khorram Abad, the nearest provincial center and also to Dorud town. It is almost 300 km to Ahwaz. The dam site is located on the Bakhtiary River bank, one of the Dez River headstreams, 5 km upstream of the confluence of the Sezar and Bakhtiary rivers, amid the Zagros Mountains and almost 50 km to the upstream of the Dez dam and hydropower plant. Its catchment's area is 6495 km2 and its average height from sea level is 2200 m, with a maximum of 4080 m.a.s.l. The mean discharge value of the river is 145 m3/s.

ABSTRACT All the design tools used to design against failure have some simplifications and assumptions. Model uncertainty, which is associated with imperfect assumption in the design tools, defines the deviation from the true failure surface. Quantification of model uncertainty is one of the critical issues in the design process which is easily neglected and it has great effect on the safety of project. One of the most common failures in underground openings is the block failure, and analytical solution based on joint relaxation is one design tool used to analyze block stability. The purpose of this paper is to show the reliability of the analytical solution. This has been done by comparing the result of it against the result of DEM in different stress conditions. The results show that the analytical solution is an accurate solution when the vertical stress is negligible, while for the cases with higher value of vertical in situ stress or in the cases where the tip of wedge is located out of distressed zone, the model uncertainty increases. Therefore the vertical stress is one important factor in the safety prediction of roof rock blocks which neglecting it makes model uncertainty and unsafe design. 1. Introduction One of the most common failure modes of underground openings is block failure. Variety of different design tools such as analytical solution, kinematics analysis and numerical analysis are available for estimating block stability. Among them ‘Kinematic’ refers to the motion of bodies without reference to the forces that cause to move [1]. The problem with Kinematic analysis of wedge is the method ignores forces acting on joints [2] therefore design based on full wedge weight and frictional force would be conservative. The conservatism is more pronounced in cases where the block has low apical angle [3,4]; therefore the analytical solution based on joint relaxation [5] was developed in order to consider the influences of horizontal stress field and joint stiffness on the stability of finite and removable blocks (according to Goodman and Shi definition, [6]). Crawford and Bray [5] proposed a two dimensional plain strain analytical solution for stability analysis of blocks in the roof for both symmetric and asymmetric wedges. The solution is based on joint relaxation to calculate joint deformation based on horizontal clamping forces and joint stiffness. However the solution is simplified based on some assumptions. The designer needs to know how good is the analytical design tool with the simplified assumptions and how much is the model uncertainty. The model uncertainty is associated with the imperfect representation of reality, and this is given by the simplification and idealization of joint relaxation. Model uncertainty is classified as epistemic uncertainty. The epistemic uncertainty is a knowledge based uncertainty and it could be reduced. In this paper the model uncertainty of Crawford-Bray solution is quantified. 2. Model Uncertainty Generally all types of engineering works are subjected to the uncertainty. The word uncertain means feeling doubt about something (Longman dictionary). Baecher and Christian [7] dividedthe uncertainty in to three group.

ABSTRACT Beheshtabad Water Transmission Tunnel is going to be driven in the Iranian central plate with an approximate length of 65 kilometers. There are several zones of weak rocks in its rout. Some of these zones are situated at great depths so that the squeezing phenomenon may occur during the tunnel exaction period. In this paper the mechanical behavior of weak rocks are studied and their effects on the stability of tunnel are investigated. Several empirical, theoretical and numerical methods are considered to model the time dependence behavior of the weak rocks. Some of these methods are used to study the time dependent behavior of the rocks surrounding this tunnel. The computed results are compared for different zones of weak rocks with potential of squeezing. These results are tabulated in tables and graphically shown in some related figures of the text. Based on these results, it is concluded that there may be a potential of squeezing causing instability in some part of the tunnel rout during its excavation. 1. Introduction Population growth, decreasing the level of underground water resources and concentration of vital industries in the central part of Iran demands a high amount of water to be transmitted to this region. Therefore, projects of water transmission to Zayande-rood (the Zayand River) are some practical and effective ways to convey the water from the West and North West of Iran to its central regions. The Beheshtabad tunnel project is planning to drive a tunnel of about 64.93 kilometer in length in order to bring water from Karoon's water resources to the Iran's central plate. This tunnel (with a SW-NE trend) will start from Darkesh-Varkesh Valley near the Ardal city and finishes at the Se-Cham Asman. This paper briefly discusses about the squeezing phenomenon associated with some part of the tunnel. Squeezing describes the reduction of the cross section of the tunnel during its excavation stages. It's due to the time dependent deformation of the surrounding rock mass resulted from the redistribution of the stresses in an elasto-visco-plastic medium. Three methods are usually used to evaluate the squeezing behavior of the surrounding rocks in a tunnel excavation sequence: empirical method, Semi-analytical method and Theoretical- Analytical method. In this study, the following methods are used to estimate the squeezing of Beheshtabad tunnel and the corresponding results are compared with each other: -Empirical methods (e.g. Geol (1994)'s approach based on N value). -Semi-analytical methods (e.g. Hoek and Marinos (2000)'s approach). -Analytical methods (e.g. Carranza-Torres & Fairhurst approach (2000) using Hoek-Brown criteria). -Analytical methods (e.g. Duncan-Fama approach (1993) using Mohr-Coulomb criteria). In order to estimate the instability of each section of the tunnel, the first step is to determine that either the rock mass should be considered as continuum or dis-continuum material.

ABSTRACT The caves and cantilever-like cliffs, which are called natural rock structures in this article, are caused by the dissolution and/or erosion of rock masses by sea waves, winds, river flow or percolating rainwater. They may present some engineering problems especially in urbanized areas along shorelines and riversides. The stability problems may arise in the form of huge sinkholes and cliff failures. The authors have been recently involved with the stability assessment of natural rock engineering structures in Ryukyu limestone formation as well as the intact and in-situ properties of Ryukyu limestone. The present article presents some procedures for the assessment of stability of the natural rock structures in Ryukyu limestone formation. The stability estimations from various methods are described and compared with each other and their implications in geo-engineering field are discussed in this article.. 1. Introduction The caves and cantilever-like cliffs, which are called as natural rock structures, are caused by the dissolution and/or erosion of limestone by sea waves, winds, river flow or percolating rain water and they may present some engineering problems especially in urbanized areas along shorelines and riversides. The stability problems may arise in the form of bending failure, shearing failure and toppling failure depending upon the natural discontinuities of rock mass as well as the geometry of natural rock structures. However, there are very few studies for evaluating the stability of rock cliffs and natural rock caves. Ryukyu limestone is widely distributed all over Ryukyu Islands and they form very steep cliffs along the shorelines of Ryukyu Islands. The toe of these cliffs is often eroded by sea waves and they result in overhanging rock cliffs. When the erosion depth reaches to a given depth, they topple as seen in Figure 1. One can see such examples along the shorelines of Ryukyu Islands. Similarly, the percolating ground water along faults and rock fractures can create natural caves of various scales. There are many spectacular examples in the Islands of Ryukyu. Some of the carstic caves are Gyokusendo, Ishigaki, Nakabari and Kin. Figure 1 shows an example of toppled and overhanging cliffs together with two caves at the site of Gushikawajo remains in Itoman city of Okinawa island. 2. Properties of Ryukyu Limestone The Ryukyu limestone is porous and its porosity varies between 4% to 30%. It is generally classified as sandy limestone and coral limestone and their physical and mechanical properties are 1516 given in Tables 1 and 2 [1,2,3]. Although coral Ryukyu limestone is quite porous it may be classified as medium strength rock and it is less prone to water content variations. 3. Rock Mass Characterization The authors carried out visual observations and explorations on Ryukyu limestone cliffs. The cliffs and caves at Gushikawajo site are constitued by coral limestone and bedding thickness is generally greater than 1–2m. There are widely spaced subvertical joints in Ryukyu limestone layers.

ABSTRACT: The design of lining and un lining of a water pressure tunnel is carried out through the detailed estimation of rock mechanical and hydrological factors and the establishment of the design guideline. The field investigation for rock mass rating and joint pattern, laboratory rock test, numerical analysis on mechanical stability using UDEC, wedge analysis for the estimation of rock block falling according to joint pattern, and hydrological analysis for the lining and un lining conditions are carried out. The design criteria are evaluated for the factors such as support pattern related with RMR range, hydraulic jacking and leakage according to the condition of rock stress and inner/outer water pressure. With these guidelines, the lining and un lining sections are designed for the water pressure tunnel with the diameter of 2.6m and the length of 5.3km. This assessment technique and the design criterion can be used as a guideline in the design of lining and un lining of the water pressure tunnel. I. INTRODUCTION The lining of a water pressure tunnel has a role in the increase of mechanical stability, the prevention of rock fall at tunnel crown, the suppression of hydraulic jacking and ground water leakage, and the improvement of water now by reducing the frictional resistance between water and tunnel wall. On the contrary to these advantages, additional cost for lining must be increased. In design of lining and un lining, therefore, various aspects should be considered such as tunnel stability, efficiency of water now, and the purpose and maintenance of tunnel. Many water pressure tunnels in Norway have been constructed without lining(Broch 1985, 1988, Selmer-Olsen 1985). This is mainly based on two aspects. One is that the rock condition in Scandinavia peninsula is very hard. The other is the basic concept of support design that some small rock fall is allowable as far as this does not influence on the tunnel stability, head loss of water pressure and maintenance of water flow channel, of course, there are some cases of collapse of unlined tunnels. In construction of water pressure tunnel recently in Korea, the lining is basically included in the support design after the experience of rock fall accident of an unlined water tunnel a few years ago. The water tunnel to be considered here is also designed as lining for the whole tunnel length at the initial design Stage. However, rock is found out very fresh and hard during actual excavation and so the initial lining design turned to be re- considered. for the re-design of lining and un lining pattern of this water pressure tunnel, the detailed estimations of rock mechanical and hydrological factors are carried out and the guideline of the lining design is established. The field investigation and laboratory test for the rock mass classification, the numerical analysis using UDEC and UNWEDGE code for the estimation of mechanical stability, and hydrological analysis for the estimation of the water now efficiency are carried out. The basic design criteria are evaluated.