Research on Seepage of Jointed Rock Mass of Tunnel and Limited Discharge of Grouting

Abstract

In underground engineering such as tunnel engineering, the condition of surrounding rock such as water-containing jointed rock mass is a common engineering geology. For broken, water-containing surrounding rock, the reasonable measures to prevent and drain water has always been a key issue. Based on the statistical information of the structural surface of the surrounding rock of the Hongtuzhang tunnel, DIPS software was used to classify the structural plane of the tunnel. Based on the statistical analysis of the occurrence, size, and density of the structural plane, the two-dimensional structural plane network model of the rock mass was established, and the permeability tensor (K1 = 1.61 × 10−6 m/s, K2 = 5.78 × 10−7 m/s) was calculated. Consider the worst orientation, the permeability tensor (K1 = 1.61 × 10−6 m/s) was selected to calculate the grouting design. Based on the theory of limited discharge, the influence of parameters of permeability coefficient ratio n and thickness of grouting layer Tg on the tunnel water inflow and lining external water pressure was analyzed. The recommended value of tunnel drainage was 3.0 m3/m∙d, then the corresponding grouting circle parameters were put forward (permeability coefficient ratio n = 100, thickness of grouting layer Tg = 8 m).

Study of New Materials for Controlled Grouting Reinforcement

“…For hydropower projects, due to the huge volume of the project and the environmental protection requirements, cement grouting is usually used [1], which uses ordinary cement prepared in grouting liquid injected by pressure, mainly to play the role of consolidation and anti-seepage, which plays a very important role in ensuring the safety of the project [2]. As construction and environmental requirements have improved, the shortcomings of conventional grouting techniques have become more apparent, such as the one-sided pursuit of groutability [3], which leads to thinning of the slurry, resulting in a large spread of grout and more material waste. Secondly, if there are pores in the grouting area, especially if there is pore water flow, the grout will be washed away, which will not achieve the grouting effect, and the washed away grout will also pollute the downstream water body; and thirdly, the high water-cement ratio causes a very long curing time for condensation, which affects the construction efficiency.…”