A large scale in-situ freezing and thawing test was carried out in a tunnel of the Kamaishi Mine to understand the conduction of heat in a fractured rock mass. Nine freezing pipes of 2.5m long were installed in nine boreholes drilled from the tunnel floor. The brine liquid was circulated through those pipes in order to freeze the rock mass of the test site. The temperature of the brine was flxed at -20°C and the circulation of the brine liquid was continued for 7-10 days in each freezing process. Thawing process was conducted by stopping the circulation after each freezing process. The duration of thawing process was about 1 month. The transient change of the temperature around those pipes was continuously measured in 23 observation holes at depths of 1m, 2m, 3m, respectively. The temperature distributions around the freezing pipes were calculated by three dimensional finite element analysis using homogeneous continuum assumptions. The latent heat of water, contained in the rock mass and the heat transfer from the tunnel floor were taken into account in the analysis. The calculated temperature changes were compared with the measured ones. The conclusions obtained are summarized as follows. (1) The change of the temperature is infiuenced considerably by the latent heat of water when a phase change of water occurred in the rock mass. (2) Thickness of thermal boundary layer, induced by heat transfer from the tunnel floor, is evaluated as 1-3cm in the analysis. (3) The temperature distributions in the fractured rock mass can be estimated by the assumption that the rock mass is homogeneous continuum.
The calculation method was based on the fan-shoot searching technique which proposed to evaluate the stability of a quarrying slope. By using the simplified slice method theory, it was possible to deal with the discontinuous planes, as weak as cracks in a shear strength, and search for a slide plane of an arbitrary shape. When applying this method to the quarrying slope on site, it required the data on the strength of rock masses and the shear characteristics of cracked surfaces. In this study, the former were estimated from the rock testing and by the seismic prospecting, and the latter were obtained by the shear testing of rock samples carrying a simple crack. From the result of the stability analysis for the quarrying slope on site, a slide plane of high probability of occurrence was indicated.
Structural analysis of a valleyward tilting structure of slate in the Setogawa Group of the Simanto Belt indicates that it is a bending fold produced by fracturing and slipping along slaty cleavages, which is caused by gravity. Formation process of the tilting structure is explained as follows: (1) At the initial stage, well-persistent cleavage plane fractures grew along slaty cleavages. (2) At the next stage, the rock masses separated by the well-persistent cleavage plane fractures bended individually with growth of many short cleavage plane fractures. (3) At the third stage, fracturing of tension fracture perpendicular to cleavages, wedge-patterned fracture zone and fold-shaped pattern of short cleavege plane fractures were developed in a zone and resulted in the formation of a hinge of bending fold. The producing fold is asymmetric. (4) Finally, the movement type of the folded slate changed by gradation from creep to topple.
The precise evaluation of evapo-transpiration is indispensable to develop the water resources in the arid and/or the semi-arid areas such as the Sahele in Africa. The evapo-transpiration were successfully measured in the Sahele by using a new equipment that was developed by the present authors. This measurement was carried out during 17/Aug. /1994-28/Aug. /1994 at several locations in the vicinity of the Nara city of Republic of Mali. The equipment used is mainly composed of two parts; a transparent box and a electric wind fan. A part of the ground surface was covered with the box and air was injected into the box through a pipe by the wind fan. Then, air in the box was exhaused through another pipe installed on the other side of the box. The evapo-transpiration from the ground surface and the plants covered with the box can be calculated from the air flow discharge and the absolute humidity difference between the injected and the exhaused air. The obtained results are as follows: (1) The evapo-transpiration was mainly affected by the solar radiation. (2) More than 60% of water poured on the ground surface in a day time was rapidly evaporated during 3 hours after the water supply. (3) The transpiration from plant was about 3-4 times larger than the evaporation from the bare soil surface. (4) The evapo-transpiration rate obtained by the equipment was about 1/3-1/5 of the evaporation rate from water surface measured by the pan-type and the PICH-type evaporation meter.