| 講演要旨(和文) | | 深度1,500mの大深度に適用可能なダウンホールPS検層用の測定システムを整備した.受振装置は,孔壁圧着型で3連のゾンデに3成分の10Hz地震計が内蔵されている.直径が51mmで小孔径のボーリングでも利用可能である.起振装置は,構造が単純で故障が無い重錘落下と板たたき振源を用いている.S波の起振は,長さ5m幅1mの板に500kgの重錘を打撃し,P波の起振は500kgの重錘を高さ1.5mから2mの高さから落下させる.1,350mのボーリング孔を利用して測定実験を実施した.繰り返し(スタッキング)回数は,深度600mまでは1回,深度1,000m以上でも3回で,P波およびS波ともに速度構造を把握するのに十分なS/Nのデータが取得できた.解析の結果,既存音波検層やサスペンションPS検層による速度構造とも整合した結果が得られた. |
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| | 講演要旨(英文) | | We have been developing the clamping tool for borehole measurement, called borehole shuttle. It is available to connect 3 units each one of which has 3 component 10Hz geophones. The diameter of borehole shuttle is 51mm. It is suitable in shallow borehole that is about 200-300m for civil and construction engineering. Borehole shuttle was improved to apply for downhole PS logging in 1,500m deep borehole. Experimental study uses the 1,350m deep borehole in OYO Tsukuba center was carried out. Weight dropping was prepared for P wave seismic source and wooden-board driving was prepared for S wave source. The maximum number of measurement was 3 stacking. The performance of measurement system in deep drilling was adequate to estimate P and S wave velocity structures. |
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