Optimizing the Grouting Design for Groundwater Inrush Control in Completely Weathered Granite Tunnel: An Experimental and Field Investigation

Abstract

Groundwater and mud inrush disaster from completely weathered granite presents a huge difficulty for tunnel construction, which requires the grouting measurement with favorable performance. To propose the optimal material parameters for grouting, numerous tests, including strength, permeability, and anti-washout, were conducted to evaluate the effects of grouting filling ratio (GFR), curing age and water velocity on the grouting effect. The test results show that: (1) The hydraulic property of completely weathered granite can be significantly improved by increasing the grouting volume and curing age. In particular, when GFR ≥ 48%, the cohesion and internal friction angle increased to about 200 kPa and 30°, which were more than three and ten times of that pre-grouting. (2) With the increase of GFR, the permeability exhibited three stages: Slowly decreasing stage, sharply decreasing stage and stable stage. When increased from 32% to 48%, the permeability coefficient sharply decreased two orders of magnitude, namely from 4.05 × 10−5 cm/s to 1 × 10−7 cm/s. (3) The particle erosion rate decreased sharply to below 10% in the low water velocity (v ≤ 0.2 m/s) when GFR ≥ 48%, but still exceeded 50% when v ≥ 0.4m/s. The results indicated that the grouting volume of GFR = 48% was a suitable grouting parameter to reinforce the completely weathered granite, particularly in the low water velocity condition. The field investigation of hydraulic-mechanical behaviors in the Junchang tunnel indicated that the grouting effect can be improved markedly.

Advanced Grouting Model and Influencing Factors Analysis of Tunnels with High Stress and Broken Surrounding Rock

“…et al, Liu, and J.Q. et al designed the grouting parameters by means of experiments and field investigations using weathered granite tunnels as example [29,30]; Liu X.L. et al analyzed the tunnel grouting process of silty fine sand stratum by theoretical analysis and numerical calculation and determined the relationship between grouting parameters [6]; Bai J.W.…”

Grouting Treatment of Water and Mud Inrush in Fully Weathered Granite Tunnel: A Case Study

“…Shi et al [45] and Liu et al [46] studied the influence of grouting layer thickness on water plugging effect through experiments, numerical simulation, and other methods and determined a grouting layer thickness that gives consideration to both safety and economy. Zheng et al [47] conducted a number of tests, including strength, permeability, and flushing resistance, to assess the impact of filling rate (GFR), curing age, and water velocity on the grouting effect in order to propose the best material parameters for grouting. Lee et al [48] showed through laboratory experiments that the waterproofing efficiency of grouting increased with the decrease of grouting hole size and W/C.…”

Influence of Different Freezing Modes on the Base Slab Displacement of an Upper Structure

“…In recent years, there have been more underpassing projects with a shorter vertical underpass distance, which put forward a tremendous challenge on the freezing design and construction. It is tough and difficult to ensure both the serviceability of existing structures and the safety of new tunnels [19]. A significant amount of research has been conducted on the ground surface movements induced by AGF [20][21][22][23][24][25].…”