Evaluation of Ground Surface Pregrouting in a Mountain Tunnel Based on FAHP

Table 5

Five curve types of the water pressure test.

Curve types	Relationships between pressure and flow	Characteristics of curve types	Depictions
Type A		Two curves (1-2-3 and 3-4-5) are straight lines originating at (0, 0) and are coincident	An excellent condition, where the seepage form is laminar flow. Fissures do not change throughout the test.
Type B		Two curves (1-2-3 and 3-4-5) converge to the Q-axis and coincide	An acceptable condition, where the seepage form is turbulent flow. Fissures do not change throughout the test.
Type C		Two curves converge (1-2-3 and 3-4-5) to the p-axis and coincide	An acceptable condition where the fissure form changes and the permeability of the rock mass increases as the test pressure increases, but the change is temporary and reversible. As the pressure decreases, the fissures return to the original form, showing a behavior of elastic expansion.
Type D		Curve 1-2-3 converges to the p-axis and does not coincide with curve 3-4-5	A bad condition, where the fissure form changes and the permeability of rock increases as the pressure increases. This change is permanent and irreversible. The flow is significantly increased and cannot be restored to its original form, indicating fissures are split.