What are the characteristics and advantages of the hollow grouting bolt itself?

　　1. Suspension training function of hollow grouting anchor rod: The hollow grouting anchor rod passes through the weak, loose and unstable geotechnical engineering body, and the steel bars are anchored on the geotechnical engineering body, which is stable in depth and exhibits sufficient tensile force. Get rid of the weight and sliding force of the sliding geotechnical engineering body, and avoid the load and the collapse of the tunnel wall.

　　2. Reinforcement effect of extruded structure: After the hollow grouting anchor rod is supported, a narrow area will be produced around it. The hollow grouting bolts are sequenced through an appropriate method, so that the narrowing areas generated by adjacent hollow grouting bolts overlap each other, thereby generating a narrowing area. The loose stratum in the shrinkage zone is reinforced by hollow grouting bolt structure, which improves the comprehensiveness and bearing capacity.

　　3. Combined beam (arch) effect: After the hollow grouting anchor rod is inserted into a certain deep layer in the ground, the ground is squeezed under the anchoring force of the steel bar, which increases the friction resistance of the virtual beam, and greatly reduces the thermal stress and stiffness. , Which is equivalent to changing a simple laminated multi-layer beam (arch) into a composite beam (arch). The flexural rigidity and compressive strength of the composite beam (arch) are greatly improved, thereby increasing the bearing capacity of the ground. The greater the anchoring force of the hollow grouting anchor to the steel bar, the more significant the effect.

　　4. Hollow grouting anchor rod length: According to the design plan, the total length of the hollow grouting anchor rod for a reasonable function. According to the suspension training function, it is the sum of the anchorage length of the steel bar, the length of the structural steel bar and the exposed length. According to the composite beam (arch) function, it is 1.2 times the sum of the composite beam (arch) height and the exposed length. In specific operations, the extra length of foundation pit excavation due to uneven centerline should also be considered.

　　5. Rebar anchorage length: The length of the hollow grouting bolt anchored in the stable ground can be selected according to work experience or calculation. When selecting based on work experience, the anchoring method of the steel bar and the diameter of the hollow grouting bolt should be considered. According to calculation and selection, the cohesiveness of cement mortar and hollow grouting anchor rod and the cohesiveness of cement mortar and hole edge are considered.

　　6. The length of structural reinforcement: It can be determined according to the height of the dangerous rock for suspension training along the azimuth of the hollow grouting bolt, or the height of the load of the soft rock, and the thickness of the loose ring accurately measured by detection techniques such as acoustic frequency.