Major investigations in the Phase I-a include geophysical survey (e.g. electro-magnetic survey and reflection seismic survey), subsurface hydrological investigations, drilling of three 1,000m-class boreholes (MIU-13). Investigations also include geophysical logging, hydraulic tests and initial stress measurements (hydraulic fracturing test) using boreholes, and chemical and mineralogical analyses, rock mechanical tests and initial stress measurements (AE/DRA test) using rock core samples. Besides, the long-term monitoring of pore water pressure is carried out using boreholes excavated before the MIU Project commenced. Tab.3.1, Tab.3.2 and Fig.3.3 show the items and purposes of investigations, the outline of borehole investigations, and the location where investigations are carried out, respectively.

In order to understand the geological environment of the Shobasama site, three kinds of models are constructed : geological model, hydrogeological model and rock mechanics conceptual model. As for construction of each model, firstly, only data obtained from literature survey and the result of geoscientific researches except for the MIU Project are used. Following model construction, the model is revised using newly-obtained data from the MIU Project.

Geology
Models are constructed for two areas : Shobasama site and an area including the Shobasama site (ca.4kmca.6km : Fig.3.4). The latter area is established to carry out groundwater flow simulation.
For each area, two models are constructed. First model is constructed using data obtained from literature survey and geoscientific researches except for the MIU Project. Second model is constructed adding data obtained from Phase I-a to the data used for the first model.

Hydrogeology
Models are constructed for above-mentioned two areas.
Purpose of the modeling for the first area is understanding the effect of fault and model's boundary conditions on groundwater flow. Purpose of the modeling for the second area is improving the accuracy of groundwater flow simulation.
In the first area, one hydrogeological model is constructed. In the second area, two hydrogeological models are constructed. First one is constructed using the data obtained from geoscientific researches except for the MIU Project. Second one is constructed adding data from the Shobasama site to the data used for the first model.
Also, groundwater flow simulation is carried out in both of above-mentioned two areas.

Hydrochemistry
Groundwater sampling and analyses are planned to be carried out in and after 2000 FY. Using those data, hydrochemical model would be constructed.

Rock mechanics
Conceptual model is constructed for the Shobasama site. First, for the modeling, the data obtained from geoscientific researches except for the MIU Project and data obtained from MIU-1 are used. Secondly, the model is revised by adding data from MIU-2. Lastly, the revised model is revised again by adding data from MIU-3.

In the model, rock mass is divided into some zones qualitatively according to physical/mechanical properties and initial stress.

Investigation techniques and equipment
The MIU Project plays a role as a place for application of investigation techniques and equipment developed by the Tono Geosciences Center (henceforth 'TGC'). TGC applies the existing (including developed by TGC) investigation techniques and equipment to actual investigations and improves them.

Additionally, literature surveys on the overseas precedents are carried out to examine the evaluation techniques of the prediction of effects caused by the shaft excavation.

Furthermore, the basic concept of designing facilities is examined to develop the engineering technologies needed for the deep underground.

	Item	Purpose
Subsurface hydrological investigations	Subsurface hydrological investigations Meteorological observation Water level observation Soil moisture observation, etc.	Estimate the recharge rate from ground surface to deep underground.
Water level monitoring	Seepage face observation(AN-3,AI-4)	Obtain in-situ data of steady state groundwater level and its change caused by borehole excavation.
	MP observation(AN-1)	Obtain in-situ data of steady state pore water pressure and its change caused by borehole excavation.
Geophysical survey	Electric survey(1 survey line, 200m) Electromagnetic survey(MT) Reflection seismic survey(1 survey line, 600m)	Estimate distribution and continuity of unconformity, geological structure, alteration zone and fracture zone,etc.
Borehole investigations Existing boreholes AN-1(ca.1,000m) AN-3(ca.400m) New boreholes MIU-13(ca.1,000m)	Geological survey Optical microscopy, Geophysical survey, BTV investigations, etc.	Confirm geology and extract geological structure (fracture, fault and dyke)which act as groundwater path.
	Hydraulic test Permeability test (3holesca.30 intervals) Pumping test (3holesca.10 intervals)	Obtain in-situ data of hydraulic conductivity of groundwater path and change in hydraulic conductivity by depth.
	Analysis Rock sample analysis (3holes)	Understand geochemical property of geological formations and change in geochemical property by depth.
	Rock mechanical test Physical/Mechanical test (3holes10points) Initial stress measurement (3holes10points)	Understand physical/mechanical property of granite and its change by depth.

		MIU-1	MIU�|2	MIU-3
Depth (m)		1011.8	1012.0	1014.0
Diameter		HQ(ca.100mm)	HQ(ca.100mm)	HQ(ca.100mm)
Drilling fluid		Fresh water	Fresh water	Fresh water
Physical logging*
BTV investigations
Pumping test (100m interval)(point)		10	10	11
Inhole hydraulic test (6.5m interval)(point)		30	30	23
Flowmeter logging
Mineralogical test**
Age dating (using rock core: Fission track method)
Physical/mechanical property test (point)	Apparent density	180	20	40
	Effective porosity	180	20	40
	Water ratio	180	20	40
	Seismic wave velocity	180	20	40
	Uniaxial compression test	90	20	10
	Brazilian test	30	40	10
	Triaxial compression test	90	10	10
Initial stress measurement (point)	AE/DRA	10	20	10
	Hydraulic fracturing	-	10	10

^* : Electrical, Micro resistivity, Density, Neutron, Gamma-ray, Acoustic, Temperature, Caliper and Deviation
^** : Modal/chemical composition analysis