8.4　Water Resistance

8.4.1　The water resistance work shall comply with the following requirements:

1　Where water seepage occurs，use shotcrete or grout for treatment；

2　The daily water inflow rate after treatment should not be higher than 100m3/d every 1Mm3 capacity.

3　Grout a material that resists ground water and stored oil or oil product.

8.4.2　Pre-grouting should be performed into any section where there is a high water inflow rate or any fracture zone before tunneling；it is necessary to carry out post-grouting if there is considerable water permeation after tunneling.The grouting operation shall comply with the following requirements:

1　Drill holes for pre-grouting:the number of grouting holes，hole distribution mode，and hole direction shall be determined through a comprehensive analysis of the fissures and ground water in the stratum in front of the tunneling face，equipment capabilities，effective grout diffusion radius，drill inclination rate，the requirements for the grouting effect，etc.

2　The grouting section's length should be 10m-15m，depending on the engineering gedogical conditions，hydrogedogical conditions，drilling equipment，and the time limit.However，a certain thickness of water-retaining rock shall be reserved during tunneling.

3　Post-grouting holes shall be drilled in a shattered fault zone，a fissure-intensive zone，a surrounding rock-rock dike contact zone，or a zone where there is considerable water inflow.The grouting reinforcement depth should be 3m to 5m.In case of extensive water seepage，the holes should be densely drilled to a shallow depth.In case of fissure-induced seepage，the holes should be sparsely drilled to a deep depth.

4　The depths of the post-grouting holes shall be at least 1m.Their diameters should be at least 40mm.The hole spacing may be determined according to the water seepage situation.

5　The pre-grouting or post-grouting pressures shall be 0.5MPa-1.5MPa higher than the hydrostatic pressure.