How to Support Miscellaneous Fill by Rock Bolts?

With the increase of urban buildings, the use of miscellaneous fills as foundations has also increased. Due to the different particle sizes of miscellaneous fills and large pores, the construction process of a casing with pipes is generally adopted, but the casing pulls out. Problems such as shrinkage holes, collapsed holes, and stuck drills after exiting, then, how to do bolt support with miscellaneous fill?

Difficulties in Supporting Miscellaneous Fill

Complex Composition

Miscellaneous fill is generally made up of materials such as domestic waste, engineering waste, and construction waste. The composition of domestic waste is relatively complex. If the soil contains organic waste, it will be corrosive to a certain extent. Industrial waste may contain some harmful substances to the human body and the environment. The ingredients need to be investigated in detail in advance.

Loose Soil

Due to the different materials of the miscellaneous fill, the size of the particles may be quite different, and the large pores will cause the soil to be loose, the shear strength is low, and the compressibility is high. At different locations on the same site, its compressibility and bearing capacity will be different. If it is used as a foundation, it needs to be manually treated first.

Submerged in Water

If the miscellaneous fill contains humus or hydrophilic and water-soluble substances, it will cause the foundation to settle and be submerged in water. Industrial residues may contain hydrates, which tend to disintegrate or swell when exposed to water, and the strength of the fill will decrease rapidly. It is necessary to investigate the technical possibility of soil treatment and the economic rationality of its utilization.

The Mixed Fill Bolt Support Method

Construction Process

Positioning and layout - foundation pit excavation - ground leveling - anchor rod and accessories material preparation - drilling rig in place - connecting rod body and drill bit - connecting rotary grouting adapter - air/water flushing drilling - drilling synchronous grouting - extending anchor Rods - Repeated drilling and grouting - Installation of waist beams - Excavation of the next layer

Process Comparison

Under normal circumstances, the construction process of pipe casing is used for geology that is not easy to form holes. This construction process requires a lot of labor costs and is prone to collapse or hole displacement. The follow-pipe casing may face a long construction period for a single piece, which will lead to project delays, require more grouting pipes, exhaust pipes, and casing extraction equipment, high labor costs, and pipe breakage may occur during the extraction process. The overall cost is higher.

Construction Efficiency

The construction efficiency of a self-drilling hollow grouting anchor rod for miscellaneous fill is at least 3 times that of the pipe casing. The slurry can be immersed into the rock and soil mass to play the role of bonding, and finally, form a complete anchor body to improve the bearing capacity of the rock mass. The self-drilling hollow bolt does not need to be pulled out after drilling and has little disturbance to the stratum, low labor cost, and low comprehensive cost.

Ordinary rock bolts will encounter many difficulties in the construction of miscellaneous soil, and self-drilling hollow bolts can solve these problems well. If you’re interested, please do not hesitate to contact us at sinorock@sinorockco.com, we’ll respond to you asap.