A rock bolt assembly provides an indication of a coupling. The rock bolt assembly includes two shaft sections, namely inner and outer shaft sections. A coupler is configured to couple the two shaft sections together at proximate ends. An electrical conductor is insulated from the outer shaft section and extends from the dead end of the outer shaft section to the head at the live end of the outer shaft section. An electrical contact arrangement is provided at the dead end of the outer shaft section, configured to electrically interconnect the outer shaft section and the conductor when the inner and outer shaft sections are coupled. Electrical terminals are provided at the head and connected respectively to the outer shaft section and to the conductor, the electrical terminals being electrically interconnected or continuous when the outer shaft section and the conductor are electrically interconnected.

This invention discloses an underground rock anchoring system comprising a rock bolt having a bolt shaft operatively locatable in an elongate rectilinear hole drilled into a hanging wall such that an end portion of the bolt shaft protrudes from the hole, the bolt shaft having a side wall defining a hollow internal chamber extending along at least part of the length of the bolt shaft, a bearing plate adapted to be fitted over the protruding end portion of the bolt shaft for bearing against a rock surface of the hanging wall; and fastening means for pulling the bearing plate taut against the rock surface of the hanging wall. The invention also extends to a rock anchoring method in which such system is used.

This invention discloses an underground rock anchoring system comprising a rock bolt having a bolt shaft operatively locatable in an elongate rectilinear hole drilled into a hanging wall such that an end portion of the bolt shaft protrudes from the hole, the bolt shaft having a side wall defining a hollow internal chamber extending along at least part of the length of the bolt shaft, a bearing plate adapted to be fitted over the protruding end portion of the bolt shaft for bearing against a rock surface of the hanging wall; and fastening means for pulling the bearing plate taut against the rock surface of the hanging wall. The invention also extends to a rock anchoring method in which such system is used.

The present disclosure provides systems and methods for determining residual tension of a target bolt. An example method may include modeling ratios of times-of-flight of longitudinal waves and times-of-flight of shear waves as a function of tension for a plurality of test bolts. The modeling may include receiving data from longitudinal wave and shear wave transducers, analyzing the data to assess certain quality characteristics, and using a machine learning algorithm to create the model. The example method may further include determining a ratio of a time-of-flight of longitudinal waves and a time-of-flight of shear waves in a target bolt. The example method may further include determining residual tension in the target bolt based on the model and the ratio of a time-of-flight of longitudinal waves and time-of-flight of shear waves in the target bolt.

The present disclosure provides systems and methods for determining residual tension of a target bolt. An example method may include modeling ratios of times-of-flight of longitudinal waves and times-of-flight of shear waves as a function of tension for a plurality of test bolts. The modeling may include receiving data from longitudinal wave and shear wave transducers, analyzing the data to assess certain quality characteristics, and using a machine learning algorithm to create the model. The example method may further include determining a ratio of a time-of-flight of longitudinal waves and a time-of-flight of shear waves in a target bolt. The example method may further include determining residual tension in the target bolt based on the model and the ratio of a time-of-flight of longitudinal waves and time-of-flight of shear waves in the target bolt.

A tension indication device for a rock bolt includes a support washer, a cover member having a central hole for receiving a trailing portion of the rock bolt, and an indicator substance provided in a first space in the cover member or in a recess in the support washer for facing the nut. Upon rotation of the nut, indicator substance is forced out of the first space such that the indicator substance is visible at inspection of the rock bolt, thereby indicating that the rock bolt has been tensioned.

A tension indication device for a rock bolt includes a support washer, a cover member having a central hole for receiving a trailing portion of the rock bolt, and an indicator substance provided in a first space in the cover member or in a recess in the support washer for facing the nut. Upon rotation of the nut, indicator substance is forced out of the first space such that the indicator substance is visible at inspection of the rock bolt, thereby indicating that the rock bolt has been tensioned.

The present disclosure provides a system for determining tension in a target bolt. The system includes one or more ultrasonic wave transducers configured to detachably couple to the target bolt and capable of generating shear and longitudinal waves in the target bolt. The system further includes a pulser-receiver configured to operatively couple with the one or more transducers and cause the one or more transducers to generate ultrasonic longitudinal and shear waves in the target bolt, and is further configured to process signals received from the one or more transducers to generate signal data. The system further includes a processing device configured to operatively couple with, and receive the signal data from, the pulser-receiver. The processing device includes a processor coupled to memory, wherein the memory stores instructions that, when executed by the processor, cause the processor to determine, based on the signal data, a TOF ratio of longitudinal and shear waves in the target bolt, and tension in the target bolt based on a model and the TOF ratio in the target bolt, wherein the model relates TOF ratios and tension levels for a plurality of test bolts.

The present disclosure provides a system for determining tension in a target bolt. The system includes one or more ultrasonic wave transducers configured to detachably couple to the target bolt and capable of generating shear and longitudinal waves in the target bolt. The system further includes a pulser-receiver configured to operatively couple with the one or more transducers and cause the one or more transducers to generate ultrasonic longitudinal and shear waves in the target bolt, and is further configured to process signals received from the one or more transducers to generate signal data. The system further includes a processing device configured to operatively couple with, and receive the signal data from, the pulser-receiver. The processing device includes a processor coupled to memory, wherein the memory stores instructions that, when executed by the processor, cause the processor to determine, based on the signal data, a TOF ratio of longitudinal and shear waves in the target bolt, and tension in the target bolt based on a model and the TOF ratio in the target bolt, wherein the model relates TOF ratios and tension levels for a plurality of test bolts.

The invention provides a displacement measuring device which includes an elongate rigid body which extends between a proximal end and a distal end and which is adapted for insertion in a rock hole, the body including a first member and a second member, a proximal anchor engaged with the first member and positioned and adapted to engage the rock hole at a proximal location, a distal anchor engaged with the second member and positioned and adapted to engage the rock hole at a distal location, and a displacement sensor, wherein the first member is adapted to move axially relatively to the second member when the proximal location moves away from the distal location, as a result of a displacement, and wherein the displacement sensor is responsive to movement of the first member relatively to the second member and which is adapted to generate a first output which is indicative of the extent of the displacement.