Self drilling anchors are special type of rod anchors. Self-drilling anchor consists of a sacrificial drill bit, hollow steel bar of the appropriate outer and inner diameter and coupling nuts. The anchor body is made of a hollow steel tube with an outer round thread. Steel tube has the sacrificial drill bit at one end and the corresponding nut with a steel end drilling anchor bolts are used in a way that hollow steel bar (rod) has a corresponding sacrificial drill bit on its top instead of a classic drill bit.
Self drilling anchor bolts are an anchoring solution suitable for unstable ground conditions (such as sand, gravel, silt and clay) and soft to moderately cracked rock formations. For projects facing such ground conditions, self-drilling anchors should be regarded as the main productivity solution.
Self Drilling Anchor Bolts include:
A hex nut
A load-bearing board
Extension coupling, if the anchor consists of multiple Anchor rod parts
Hollow anchor
Sacrifice bit
Galvanized anchor
Coupling box
Centralizer
Fiberglass is a kind of fiber reinforced plastic. In technical terms, fiberglass is called composite material. Fiber-reinforced plastics are made up of two parts, a matrix, which is resin or plastic, and a reinforced plastic, which in most cases is reinforced with fiber. FRP has a wide range of properties and plays an important role in economic construction.
Jiufu Glass fiber reinforced plastic bolt is made of glass fiber as reinforcement material, polyester resin as the base material, by special pultruding machine traction, through the preforming die under high temperature and high pressure curing into full thread glass fiber reinforced plastic bolt body, plus resin anchorage agent, tray and nut composition of glass fiber reinforced plastic bolt.
Model specifications (mm) bar tensile strength (kN) bar tensile strength (MPa) connecting part and thread bearing capacity (kN)
Fhj-18 φ 18 140 650 50
Fhj-20 φ 20 180 620 80
Fhf-25 φ 25/10 185 510 80
The weight of FRP bolt is light and convenient for transportation, which can reduce the investment of roadway support material in transportation and reduce the support cost in the process of coal mining. In addition, FRP bolt can penetrate into surrounding rock and rock, which does not need to occupy the roadway section, and also reduces the cost of roadway excavation. In addition, the stability of FRP bolt support is better, and the maintenance amount of roadway is less, which can reduce the maintenance cost of the project to a certain extent.
Soil nailing uses grouted, tension-resisting steel elements (nails) to reinforce in situ soils and create a gravity retaining wall for permanent or temporary excavation support.
The continuous external thread is made by hot extrolling method. The shape of Jiufu thread bar is shown as following figure.
The main diameter is 15mm to 75mm and the strength is 500MPa to 1080MPa.
All Couplings and Hex/Collar Nuts exceed 100% of the bar’s published ultimate strength and couplings will meet ACI 318 Section for mechanical rebar connections.