Distribution characteristics of seepage field and prediction of water inflow before and after tunnel construction

¹ China Institute of Water Resources and Hydropower Research, Beijing, China
² Fujian Research Center for Tunneling and Urban Underground Space Engineering, Huaqiao University, Xiamen, China
³ Yankuang Group, Shaanxi Future Energy Chemical Corp, Yulin, China

^* Corresponding author: aCAO Ruilang: finite@yeah.net

Abstract

In the construction of a deep tunnel with rich water and soft rock, accurate evaluations of the distribution characteristics of seepage field and water inflow are important bases for predicting the stability of tunnel surrounding rock and the disturbance state of groundwater environment. This paper used the Flac3D finite difference software seepage module, based on field geological borehole, measured seepage parameters and groundwater level. A three-dimensional numerical model of geological seepage in engineering area was established. The distribution characteristics of groundwater seepage field, the variation law of seepage field before and after tunnel excavation, and the water inflow during construction period were studied. As the tunnel was excavated, the excavated surface became a drainage channel, the isoline of groundwater pressure was changed into parallel non-parallel curve set by the parallel line of the initial seepage field. The nearer the tunnel centre was, the more obvious the variation tendency of groundwater pressure was. Grouting measures were very effective for tunnel water gushing, which not only reduced water inflow, but also effectively reduced the external water pressure of lining. It was infeasible to plug water when blocking the water without grouting and only adjusting the permeability of the lining.