• Proceedings of the Korean Society for Rock Mechanics Conference
• /
• 2000.09a
• /
• pp.211-222
• /
• 2000

The design values of rock socketed pile related with properties of rock mass are not clearly established. However, the drilled shafts socketed in rock are widely used as the foundation of large scaled structure. In this study, the characteristics of behavior of rock socketed pile is researched, and the properties of interface between pile and rock considering soil-structure interaction are evaluated for numerical modeling of rock socketed pile based on the previous researches. Based on the properties of interface and rock mass, the behaviors of rock socketed piles are numerically modeled and compared with field measurement. To verify the numerical analysis, a micro pile socketed in rock is modeled and the results of numerical analysis are compared with field measurement. The numerical results show a good agreement with field measured data, especially in terms of load transfer characteristics.

• Proceedings of the Korean Society for Rock Mechanics Conference
• /
• 2011.09a
• /
• pp.89-97
• /
• 2011

Brittle failure of rock is a classical rock mechanics problem. Rock failure not only involves initiation and propagation of single crack, but also is a complex problem associated with initiation, propagation and coalescence of many cracks. As the most important feature of rock material properties is the heterogeneity, the Weibull statistical distribution is employed in the rock failure process analysis (RFPA) method to describe the heterogeneity in rock properties. In this paper, the applications of the RFPA method in geotechnical engineering and rockburst modeling are introduced with emphasis, which can provide some references for relevant researches.

• Tunnel and Underground Space
• /
• v.10 no.3
• /
• pp.457-468
• /
• 2000

The design values of rock socketed pile related with properties of rock mass are not clearly established. However, the drilled shafts socketed in rock are widely used as the foundation of large scaled structure. In this study, the characteristics of behavior of rock socketed pile is researched, and the properties of interface between pile and rock considering soil-structure interaction are evaluated for numerical modeling of rock socketed pile based on the previous researches. Based on the properties of interface and rock mass, the behaviors of rock socketed piles are numerically modeled and compared with field measurement. To verify the numerical analysis, a micro pile socketed in rock is modeled and the results of numerical analysis are compared with field measurement. The numerical results show a good agreement with field measured data, especially in terms of load transfer characteristics.

• The Journal of Engineering Geology
• /
• v.32 no.1
• /
• pp.85-99
• /
• 2022

Rock discontinuities, as weak interfaces in rock, control mechanical properties of rock mass. Presence of discontinuities complicates the engineering properties of rock, which is the root of anisotropy and heterogeneity that have nonnegligible influences on the rock engineering. Morphological characteristics of discontinuities in natural rock are an important factor influencing the mechanical properties, particularly roughness, of discontinuities. Therefore, the accurate measurement and characterization of morphologies of discontinuities are preconditions for studying mechanical properties of discontinuities. Taking discontinuities in red sandstone as research objects, the research obtained three-dimensional (3D) morphologies of discontinuities in natural rock by carrying out 3D morphological scanning tests. The waviness and roughness were separated from 3D morphologies of rock discontinuities through wavelet transform. In addition, the calculation method for the overall slope root mean square (RMS) as well as slope RMSs of waviness and roughness of 3D morphologies of discontinuities considering the shear direction was proposed. The research finally determined an evaluation method for 3D morphologies of discontinuities by quantitatively characterizing 3D morphologies with the mean value of the three slope RMSs.

• Tunnel and Underground Space
• /
• v.7 no.1
• /
• pp.13-19
• /
• 1997

It is necessary to study on thermo-hydro-mechanical effect at rock mass performing project such as radiowaste disposal in deep rock mass. In this study, thermo-hydro-mechanical coupling analysis which is considered interaction and the variation of rock properties induced by temperature increase was performed for the circular shaft when appling temperature of 20$0^{\circ}C$ at the shaft wall. The shaft is diameter of 2 m and under hydrostatic stress of 5 MPa. In the cases, thermal expansion by temperature increase progress from the wall to outward and thermal expansion could induce tensile stress over the tensile strength of rock mass at the wall. When rock properties were given as a function of temperature, thermal expansion increased, tensile stress zone expanded. Lately, water flow is activated by increase of permeability and decrease of viscosity.

• Tunnel and Underground Space
• /
• v.24 no.3
• /
• pp.224-233
• /
• 2014

It is well known that rock properties can be affected by loading in underground condition. In the case of flooded underground mine or tunnels, rock properties variation due to loading might be different from the loading in dry condition. In order to verify the influence of saturated loading condition on rock properties, various laboratory tests had been carried out. Loading on the rock specimen was controlled to be ranged in between 20 ~ 80% of UCS. By comparing the variation of thermal, mechanical, and physical properties of rock specimens under the same load in saturated and dry condition, it was possible to find that the rock properties can be more significantly disturbed in the saturated loading condition than in dry loading condition.

• 한국터널공학회:학술대회논문집
• /
• 2005.04a
• /
• pp.348-358
• /
• 2005

Although the evaluation of the mechanical properties and behavior of discontinuous rock masses is very important for the design of underground openings, it has always been considered the most difficult problem. One of the difficulties in describing the rock mass behavior is assigning the appropriate constitutive model. This limitation may be overcome with the progress in discrete element software such as PFC, which does not need the user to prescribe a constitutive model for rock mass. Instead, the micro-scale properties of the intact rock and joints are defined and the macro-scale response results from those properties and the geometry of the problem. In this paper, a $30m{\times}30m{\times}30m$ jointed rock mass of road tunnel site was analyzed. A discrete fracture network was developed from the joint geometry obtained from core logging and surface survey. Using the discontinuities geometry from the DFN model, PFC simulations were carried out, starting with the intact rock and systematically adding the joints and the stress-strain response was recorded for each case. With the stress-strain response curves, the mechanical properties of discontinuous rock masses were determined and compared to the results of empirical methods such as RMR, Q and GSI. The values of Young's modulus, Poisson's ratio and peak strength are almost similar from PFC model and Empirical methods. As expected, the presence of joints had a pronounced effect on mechanical properties of the rock mass. More importantly, the mechanical response of the PFC model was not determined by a user specified constitutive model.

• Tunnel and Underground Space
• /
• v.21 no.2
• /
• pp.138-144
• /
• 2011

Mine closure does often accompany the flooding of mine galleries due to ceasing a pumping operation. When a mine gallery is flooded, rocks around the gallery are fully saturated and the gallery is subject to a water pressure. The uniaxial unconfined compressive strength of a rock depends on its water content and decreases as the water content increases. A water pressure may originate the crack growth of a rock or the discontinuity growth of rock mass. Although the water in a gallery will give some support pressure inside the gallery, the degradation of rock mass properties caused by a water pressure will reduce the stability of the gallery. In this study, 2-dimensional discontinuous and 3-dimensional continuous numerical analyses have been conducted to evaluate an effect that a reduction of rock mass properties around the gallery induced by a water pressure has on the stability of mine gallery. The numerical analyses show that a reduction of rock mass properties caused by a water pressure increases displacements of rock mass around mine gallery. 2-dimensional model is found to give larger values of displacement than 3-dimensional model.

• Tunnel and Underground Space
• /
• v.6 no.1
• /
• pp.19-29
• /
• 1996

Back analysis model, capable of calculating the mechanical properties and the in-situ stresses of jointed rock mass, was developed based on the inverse method using a continuum theory. Constitutive equation for the behavior of jointed rock contains two unknown parameters, elastic modulus of intact rock and stiffness of joint, hence algorithm which determines both parameters simultaneously cannot be established. To avoid algebraic difficulties elastic modulus of intact rock was assumed to be known, since the representative value of which would be quite easily determined. Then, the ratio ($\beta$) of joint stiffness to elastic modulus of intact rock was assigned and back analysis for the behavior of jointed rock was carried-out. The value $\beta$ was repeatedly modified until the elastic modulus from back analysis became very comparable to the predetermined value. The joint stiffness could be calculated by multipling the ratio $\beta$ to the final result of elastic modulus. Accuracy and reliability of back analysis procedure was successfully testified using a sample model simulating the underground opening in the jointed rock mass. Applicability of back analysis model for the underground excavation in practice was also verified by analyzing the mechanical properties of jointed rock in which underground oil storage cavern were under construction.

• Journal of Conservation Science
• /
• v.30 no.2
• /
• pp.189-203
• /
• 2014

In this study, the identification and distribution for rock types of the South Gate Wall of Myeoncheoneupseong Town Wall in Dangjin was investigated, and the homogeneity analysis of rock properties in the wall between the surrounding out crops estimated by examining the possible provenances. The Town Wall consists of variable rock types about 15 kinds. Granitic rocks (61.0%), quartzite (21.0%) and quartz feldspar porphyry (8.7%) accounted over 90% of total survey section. These rock properties are very similar to surrounding rocks of the Town Wall on the basis of occurrences, magnetic susceptibility, petrography, mineralogical and goechemical characteristics. Thus, it is probable that the rock properties of the Town Wall were supplied from the Town Wall around about 8km within at Seongsangri, Yangyuri, Seongbukri, Galsanri and Daedeokdong area. And supplied rock properties in the construction process, easy procurement rather than rock type was most likely seems to be considered.