Groundwater tracer test of a sedimentary formation by three-dimensional analysis using FEM at the Matsumoto tunnel

Abstract

A field tracer test in a Tertiary sedimentary rock at the Matsumoto Tunnel under construction was performed. A tracer solution was injected into a borehole which was 130 m apart from the cutting face of the tunnel. Seepage water along the tunnel was sampled in order to measure the concentration of tracer. Effective porosity, hydraulic conductivity and longitudinal dispersivity were analyzed from the relationship between the tracer concentration and the time elapsed from the start of tracer injection by the three-dimensional groundwater flow and advection-dispersion code using FEM (Finite Element Method).

建設中の松本トンネルにおいて第3紀堆積岩の現場トレーサ試験を行った。トレーサ溶液はトンネルの断面から130m離れたボアホール内に注入した。トレーサの濃度を測定するために、浸透水をトンネルに沿って採取した。FEM(有限要素法)に基づく3次元地下水流および移流分散コードにより、トレーサ濃度とトレーサ注入開始からの経過時間の関係から、有効空隙率、透過係数ならびにトンネルの長さ方向の分散度の解析を行った。