Atsuo Hirata

Sojo University · Faculty of Engineering

In order to measure crustal stresses at great depths of more than 1000 m from the ground surface, we have been promoting research and development of borehole-jack fracturing technique. When a borehole wall is loaded by a borehole-jack, a pair of new fractures will be induced oppositely in parallel to the borehole axis. After unloading, if the same...

A new seismic well logging technique has been developed for identifying the damaged zone around the rock masses that was affected by the stability of rock structures due to excavation of underground. In this study, we firstly purpose to introduce a new seismic well logging technique, then to show the results of the examples applied on rock structur...

Variations of physical properties such as weight loss rate, wave velocity and uniaxial compressive strength after performing freeze-thaw cyclic test were measured in order to define weathering characteristics of sandstone and andesite. Weight change in specimens of the two rocks decreased with increasing the repetition number of freeze-thaw cyclic...

This study is to consider applicability of spiral bolt strain gauge as an instrument measuring behavior of soft ground foundation and rock slope. When the instrument was installed on the ground, it can be useful to identify the state of ground behavior because it has the characteristics of flexibility, as well as to apply the ground reinforcement b...

The spiral bar is presently being developed as a new support in Japan. This study is to examine the characteristics of the spiral bar and to clarify the mechanism of interaction behavior between the spiral bar and the ground. For this study, we performed laboratory and in-situ pull-out tests, moreover carried out the numerical analysis using FLAC3D...

Methods of measuring stress and its variations are briefly reviewed with particular interest in precise measurements at depth. Stress-relief methods are widely used techniques in the engineering field. Wireless strain-cells indicate the possibility of stress-relief methods for deep wells. However, elastic coupling of [rock mortar strain-meter] must...

Stability monitoring of rock slope covered with limestone is an important for safety operation of limestone open cut mine in Japan. In this paper, a series of field measurements has been carried out in a limestone open cut mine and deformation behavior of rock slope with cover rock has been discussed. Results obtained in the present study are summa...

This paper presents the contents of the compact vertical seismic prospecting (VSP) system and its application to in-situ measurement. A new method of rock property investigation by using this compact vertical seismic prospecting system is proposed. This investigation system consists of a vibration sensor and a super elastic alloy pipe to press the...

It is of extreme importance for an analysis with a high degree of accuracy that characteristics of rock around cavern such a tunnel are well known. A new method of rock property investigation by using a compact vertical seismic prospecting system is proposed. This investigation system consists of a probe attached vibration sensor and super elastic...

Estimation of blasting vibration is important for the safety control in blasting work. In the previous report about the blasting vibration in tunnel excavation, the authors proposed a method to predict the amplitude spectrum of blasting vibration.In the present paper, a method to predict the maximum amplitude of blasting vibration is proposed. Anal...

The blasting vibration in advance of a working tunnel was observed in a existing tunnel, that is active and crosses above 20m distant from the surface of the working one, and in rock which is not affected by the tunnel.Vibration caused by blasting has an important effect upon underground structures. The dynamic response of the structures caused by...

The authors developed a computer program for predictive calculation of transient underground climate. One can compute simultaneously the variations of flow rates, temperatures and humidities of air flow in the airways along one circuit with time passage, by using the program. They made a one simple circuit model in which heat sources are placed alo...