Geomechanics evaluation and field investigation of surrounding rocks are the basis and precondition of rock bolt’s supporting design, which should be finished before supporting design of rock bolt.
It should firstly determine areas, consider all factors that influences support system and then rock bolt’s design should be defined in this area. So geomechanics evaluation and field investigation include following contents:
1. The property and intensity of surrounding rocks:
The width, obliquity and intensity of surrounding rocks all have influence on choice of rock bolt’s sizes and construction methods.
2. The structure of surrounding rocks and geology.
The distribution of joints, cracks and discontinuity surface have influence on integrity of surrounding rocks. The location of fault and fold have influence on stability of surrounding rocks.
3. Ground stress.
The size and orientation of ground stress, the intersection angle with roadway axes and mining conditions around have influence on ground stress.
4. Environment influence.
Environment around also has great influence on construction, such as: hydrogeological condition, water inflow, gas gushing amount, incidence for surrounding rock’s intensity and weathering characteristics, etc.
5. Rock bolt’s anchoring force.
Rock bolt used in construction should adopt end anchorage way. Pull-out test should be conducted in the range of designed anchorage length. When anchoring force meets designed requirements, rock bolt can be used.