The behavior of a jointed rock mass depends mainly on the geometrical and mechanical properties of joints. The failure mode of a rock mass and kinematics of rock blocks are governed by the orientation, spacing, and persistence of joints. The mechanical properties such as dilation angle, shear strength, maximum closure, strength of asperities and friction coeffiient play important roles on the stability and deformation of the rock mass. The normal and shear behaviour of a joint are coupled due to dilation, and the joint deformation depends also on the boundary conditions such as stiffness conditons. In this paper, the joint constitutive law including the dilatant behaviour of a joint is numerically modelled using the edge-to-edge contact logic in distinct element method. Also, presented is the method to quantify the input parameters used in the joint law. The results from uniaxial compression and direct shear tests using the numeical model of the single joint were compared to the analytic results from them. The boundary effect on the behaviour of a joint is verified by comparing the results of direct shear test under constant stress boundary condition with those under constant stiffness boundary condition. The numerical model developed is applied to a complex jointed rock mass to examine its performance and to evaluate the effect of joint dilation on tunnel stability.

일반적으로 NATM공법에서 지보의 설계는 암반반응곡선의 개념을 통해 수행된다. 그러나 암반반응곡선은 암질이 좋고 과지압에 의한 문제가 심각하지 않은 지역에 적용되며, 따라서 주로 불연속면에 의해 암반의 거동이 영향을 받는 지역에서는 시공과정에 직접 적용하기가 힘들다. 본 연구에서는 암반 블록에 대한 블록반응곡선을 연구하여, 블록반응곡선상에서 지보를 설계하였다. 각각의 차분시각에서의 변위와 응력을 얻기위해서 개별요소 프로그램인 UDEC을 사용하였다. 블록은 Mohr-Coulomb 모델이며, 불연속면은 Barton-Bandis 모델이다. 블록과 불연속면의 물성은 실험실 실험을 통하여 구하였다. 블록반응곡선을 이용한 지보설계과정을 이해하기 위하여 간단한 모델분석을 실시하였다. 동일한 형상의 키블록이 공동의 천장, 측벽, 바닥에 존재할 경우, 각 블록의 안정성 판단 및 지보의 설계를 실시하였다. 또한 초기지압의 영향을 알아보기 위하여, 측압계수(K)를 달리하여 해석해보았다. 현재 건설중인 공동에 대한 안정성 판단 및 지보설계를 블록반응곡선을 이용하여 설계하였다.

Thermomechanical characteristics of rocks such as thermal shock, thermal expansion, thermal cracking were experimentally investigaed using Iksan granite, Cheonan tonalite and Chung-ju dolomite to obtain the basic data for proper design and Chung-ju dolomite to obtain the basic data for proper design and stability analysis of underground structures subjected to temperature changes. The effect of thermal shock did not appear when the heating speed was under 3$^{\circ}C$/min. and there existed little difference between multi-staged cyclic heating and single-cycled heating. Thermal expansion of rocks was affected by mineral composition, crack porosity and the degree of thermal craking. In quartz-beraring multimineralic rocks such as Iksan granite and Cheonan tonalite, the thermal expansion coefficient increaseed continuously with temperature rise, but that of Chung-ju dolomite which was a monomineralic rock showed a constant value for the temperature above 250$^{\circ}C$, Chung-ju dolomite yielded the lowest critical threshold temperature(Tc) of 100$^{\circ}C$ and unstable thermal cracking was initiated above the new threshold temperature(Tc')of 300$^{\circ}C$. Above Tc' thermal cracks grew but they were not interconnected. Iksan granite showed closing of microcracks to the temperature of 100$^{\circ}C$, then expanded linearly to Tc of 200$^{\circ}C$. Above Tc, thermal cracking was initiated and progressed rapidly and almost all the grain boundaries were cracked at 600$^{\circ}C$. Cheonan tonalite also showed similar behavior to iksan granite except that Tc was 350$^{\circ}C$ and that thermal cracks propagated more rapidly. Thermal expansions calculated by Turner's equation were found to be valid in predicting the thermal expansion and cracking behavior of rocks.

터널의 설계를 용이하게 하기 위하여 ROMES 프로그램을 개발하였다. 개발된 프로그램의 타당성 검토를 위하여 기존 Classextltmxpa으로 검증한 결과 높은 상관관계를 얻었으며 기존의 암반분류 사례에 적용한 결과 정밀하고 객관적인 분류가 가능한 것으로 밝혀졌다.

Recently, most of the underground excavation works are adopting heavy duty mobile diesel equipments which have outstanding merits in view of efficiency. However, these equipments are causing hygienic problems to the workers due to the various hazardous exhaust contaminants. Considering that there are always dead end workings in underground excavation sites, it is very important how to supply enough airflow to the workings to dilute diesel exhaust contaminants. This paper introduced the theoritical mechanism and actual trends of exhaust contaminants of diesel equipments under operation at local mines and suggested the design method of intake air volume in underground excavation workings using diesel equipments.

"수갱공사의 기술적 문제에 대해서(ll)"에서 4가지 특성중 굴하용 권양기의 용량을 결정하는 지표가 되는 한계심도의 결정, 대형 수갱 또는 출수가 많은 경우 폭약의 불발 사고를 방지하는 방법을 다루었으며, 금회에는 수갱의 출수문제를 검토하기로 한다. 검토하기로 한다.

Two types of deformations can occur on the cable during the monitoring of the rock displacement by the time domain reflectometry. One is the impedance model for tensile deformation, and the other is the capacitance model for the shear deformation. The former gives a response signal with a gradual change in the amplitude of the reflected voltage, meanwhile the latter produces a signal with a blunted spike. The resolution of the TDR can be improved to 0.125% using calibration crimps on the cable of 60 meters long. It is recommended that the diameter of the cable should be 18 mm at least in order to induce a better reflected pulse without any open-circuit. The actual TDR technique cannot characterize the type and the magnitude of rock displacement quantitatively. Systematic investigation of the TDR parameters, such as the exact of cable diameter, cable length, number of crimps, combination of shearing and extension, and environment of the TDR equipment, will be able to improve the resolution to 0.01 mm.