Before tunnelling work on Tokyo-Nagoya Expressway, we made six horizontal borings as a geological survey, and good results were obtained. In this report we try to explain our boring technique, its efficiency, geological problems and some other considerations to be taken for the future. The three representative features of the horizontal boring are as follows: 1. Continuously we can get necessary informations about the cross section of the proposed tunnel, such as distribution of rock properties, location of faults and cracking degree. 2. We also continuously get the information about the condition of underground water. 3. The geological survey will be done more economically and yet more precisely by adding the horizontal boring technique to the usual vertical boring method.
The San Luis Unit is a major addition to the Central Valley Project which has been progressed under the cooperation of the State of California and Federal Government of the United States. It is a storage facility for excess water from the Delta area, fed by streams of the Sierra Range during winter and spring runoff, that would normally waste into the Pacific Ocean. Some problems in engineering geology of the San Luis Dam and its surrounding area are reviewed in some detail.
In conditions as fault zone, soft mudstone, etc., the ground around an opening made in it generates the plastic flow and it results in load on the supports. In such good conditions as granite, sandstone, etc., the ground around an opening relaxes due to ex-plosion, weathering, etc., and the supports bear the load due to relaxations. This paper deals experimentally, in conformity to results of investigations in tunnels conducted by the author, with the rock pressure generated by the relaxation due to explosion, weathering, etc., and with the supports suitable to the openings in good ground.