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 device for testing overall anchorage performance of a basalt fiber reinforced plastic (BFRP) anchor cable includes an anchor cable anchoring system and a data acquisition system. The anchor cable anchoring system includes a test bed, BFRP arranged over the test bed, and a distributed optical fiber bonded to a surface of the BFRP, the test bed being provided with an anchoring section at one end and an outer anchoring section at the other end, the anchoring section anchors one end of the BFRP, and the outer anchoring section anchors the other end of the BFRP. The data acquisition system includes a modem and a grating connected to two ends of the distributed optical fiber in series, and a center hole jack and a dynamometer arranged between the outer anchoring section and an end of the test bed, and the BFRP penetrates the center hole jack and the dynamometer.

A rotation indication device for a rock bolt including a central rod with a threaded trailing portion. The rotation indication device includes a blind nut having a threaded central recess for engaging the threaded trailing portion and a visual indication means provided at a bottom portion of the central recess and configured such that upon movement of the threaded trailing portion of the central rod into the bottom portion of the central recess, the central rod forces at least a portion of the visual indication means to move through a passage in the blind nut between the bottom portion of the central recess and the outside of the blind nut.

A rotation indication device for a rock bolt including a central rod with a threaded trailing portion. The rotation indication device includes a blind nut having a threaded central recess for engaging the threaded trailing portion and a visual indication means provided at a bottom portion of the central recess and configured such that upon movement of the threaded trailing portion of the central rod into the bottom portion of the central recess, the central rod forces at least a portion of the visual indication means to move through a passage in the blind nut between the bottom portion of the central recess and the outside of the blind nut.

A methods and systems for determining a change in condition of a rock bolt. Some methods may comprise, at a first point in time, propagating shear and longitudinal ultrasonic waves along the rock bolt to measure a first time of flight for each of the shear and longitudinal waves, at a second point in time after the first point in time, propagating shear and longitudinal ultrasonic waves along the rock bolt to measure a second time of flight for each of the shear and longitudinal waves, and using the relative changes of the first and second time of flights, determining the change in condition of the rock bolt section.

A methods and systems for determining a change in condition of a rock bolt. Some methods may comprise, at a first point in time, propagating shear and longitudinal ultrasonic waves along the rock bolt to measure a first time of flight for each of the shear and longitudinal waves, at a second point in time after the first point in time, propagating shear and longitudinal ultrasonic waves along the rock bolt to measure a second time of flight for each of the shear and longitudinal waves, and using the relative changes of the first and second time of flights, determining the change in condition of the rock bolt section.

Methods and systems for determining a change in condition of a rock bolt. Some methods may comprise, at a first point in time, propagating shear and longitudinal ultrasonic waves along the rock bolt to measure a first time of flight for each of the shear and longitudinal waves, at a second point in time after the first point in time, propagating shear and longitudinal ultrasonic waves along the rock bolt to measure a second time of flight for each of the shear and longitudinal waves, and using the relative changes of the first and second time of flights, determining the change in condition of the rock bolt section.

Methods and systems for determining a change in condition of a rock bolt. Some methods may comprise, at a first point in time, propagating shear and longitudinal ultrasonic waves along the rock bolt to measure a first time of flight for each of the shear and longitudinal waves, at a second point in time after the first point in time, propagating shear and longitudinal ultrasonic waves along the rock bolt to measure a second time of flight for each of the shear and longitudinal waves, and using the relative changes of the first and second time of flights, determining the change in condition of the rock bolt section.

Rock bolt (1) comprising at least an elongated body (4), one end of which comprises at least a first external conical portion (16) extending through at least one hole (12) in at least a cylindrical expandable body (5), the hole (12) over a section of the bore hole in the axial direction comprises an internally conical part (15) intended to cooperate with the elongate member outer conical portion (16). Upon relative movement of the elongate body (4) and the expandable body (5) in one direction expands the expandable body in the radial direction. The relative axial movement between the elongated body (4) and the expandable body (5) is provided by at least one tensioning device (7). The rock bolt comprises at least one wedge device (2), which in use of the rock bolt, is connected to the expandable body (5) hole (12) and at least partially inserted between a first portion (17) and at least a second part (18). The rock bolt further comprises at least one connecting means (21).