A device for measuring strain in an elongated metallic bar, the device comprising a housing arranged to be secured to the metallic bar, at least one optical sensor, at least one light source arranged to emit light across an interior space of the housing, and a thread arranged freely movable within a sheath and having a proximal end extending to a distal end of the housing and a distal free end arranged to be attached to the metallic bar at a distance from the housing such that longitudinal deformation of the metallic bar causes displacement of the proximal end of the thread in relation to the housing, and wherein the at least one optical sensor is configured to measure the displacement of the proximal end of the thread by measuring light emitted from the at least one light source.

A collaborative erosion-control method of releasing-splitting-supporting based on coal mass pressure relief and roof pre-splitting provided by the disclosure includes the following steps: step 1, driving into a coal seam to release pressure; step 2, low roof pre-splitting during driving process; step 3, supporting of roadway surrounding rock and support reinforcement; step 4, floor destressing of the roadway; step 5, high roof pre-splitting before mining; step 6, destressing and supporting of the advanced roadway surrounding rock during the mining process of the working face. The collaborative erosion-control method of releasing-splitting-supporting based on coal mass pressure relief and roof pre-splitting, and to carry out local pressure relief, roof pre-splitting and reinforcement support construction in the whole cycle of the coal working face in a progressive manner, so as to achieve the prevention and control of rock burst in the working face.

A collaborative erosion-control method of releasing-splitting-supporting based on coal mass pressure relief and roof pre-splitting provided by the disclosure includes the following steps: step 1, driving into a coal seam to release pressure; step 2, low roof pre-splitting during driving process; step 3, supporting of roadway surrounding rock and support reinforcement; step 4, floor destressing of the roadway; step 5, high roof pre-splitting before mining; step 6, destressing and supporting of the advanced roadway surrounding rock during the mining process of the working face. The collaborative erosion-control method of releasing-splitting-supporting based on coal mass pressure relief and roof pre-splitting, and to carry out local pressure relief, roof pre-splitting and reinforcement support construction in the whole cycle of the coal working face in a progressive manner, so as to achieve the prevention and control of rock burst in the working face.

Rock bolts are typically used to provide support for rock formations and to hold the formation together. Rock bolts may fail due to a number of reasons. Failures in rock bolts may cause overload or loss of preload in the rock bolt. Aspects of the disclosure provide a sensing device for a rock bolt. The sensing device includes a spacer and at least one load sensor. Each said at least one load sensor includes a respective resilient compressible element that is adjacent a respective end of the spacer. The resilient compressible element compresses responsive to a respective load threshold. Each load sensor provides respective sensor output as a function of whether or not the respective resilient compressible element is compressed. The sensing device generates device output indicating a status of the rock bolt.

Rock bolts are typically used to provide support for rock formations and to hold the formation together. Rock bolts may fail due to a number of reasons. Failures in rock bolts may cause overload or loss of preload in the rock bolt. Aspects of the disclosure provide a sensing device for a rock bolt. The sensing device includes a spacer and at least one load sensor. Each said at least one load sensor includes a respective resilient compressible element that is adjacent a respective end of the spacer. The resilient compressible element compresses responsive to a respective load threshold. Each load sensor provides respective sensor output as a function of whether or not the respective resilient compressible element is compressed. The sensing device generates device output indicating a status of the rock bolt.

A monitoring system includes a fastener. A sensor is coupled to the fastener. A circuit board is electrically coupled to the sensor. An antenna electrically coupled to the circuit board.

A monitoring system includes a fastener. A sensor is coupled to the fastener. A circuit board is electrically coupled to the sensor. An antenna electrically coupled to the circuit board.

A monitoring system includes a fastener. A sensor is coupled to the fastener. A circuit board is electrically coupled to the sensor. An antenna electrically coupled to the circuit board.

A monitoring system includes a fastener. A sensor is coupled to the fastener. A circuit board is electrically coupled to the sensor. An antenna electrically coupled to the circuit board.

Rock bolts are typically used to provide support for rock formations and to hold the formation together. Rock bolts may fail due to a number of reasons. Failures in rock bolts may cause overload or loss of preload in the rock bolt. Aspects of the disclosure provide a sensing device for a rock bolt. The sensing device includes a spacer and at least one load sensor. Each said at least one load sensor includes a respective resilient compressible element that is adjacent a respective end of the spacer. The resilient compressible element compresses responsive to a respective load threshold. Each load sensor provides respective sensor output as a function of whether or not the respective resilient compressible element is compressed. The sensing device generates device output indicating a status of the rock bolt.