Abstract: This invention relates to an apparatus and method for detecting and measuring the position of a fracture in solid formations, such as for example a grout filled borehole. An electrical element is placed the length of the borehole prior to filling the hole with grout. When the hole is filled and the grout solidified, any fracture in the grout also breaks the electrical element. The element is constructed such that its electrical capacitance is a known function of its length. The element is constructed of easily frangible materials so that it is severed in close proximity to the grout fracture. The capacitance of the element after the fracture can be measured using suitable instrumentation. The position of the break is a function of the capacitance as measured after the break.

Abstract: A vibratory wire strain gage and more particularly a vibratory wire strain gage having an improved means for readily tensioning the gage wire and, if desired, adjusting such tension prior to installation.

Abstract: A vibrating wire stress meter and the method used to clamp its wire in position. The wire is highly tensioned diametrically across the sides of a hollow metallic cylinder and held there by two anchor tubes. A wedge and platen assembly in turn hold this cylinder in a rock borehole such that small stress changes in the surrounding rock cause the diameter of the cylinder to slightly change. This cylinder variation is transmitted to and measured by the preloaded wire by noting variations in its frequency or period of vibration. To cause the wire to vibrate a coil, magnet, and yoke are used as a plural pole electromagnetic plucker.Clamping of the wire is accomplished by highly tensioning the wire between two opposite hollow tubes that are seated in opposite aligned countersunk holes of the cylinder and then extruding the steel tubes around the wire. The wire extends through holes of those hollow tubes as well as the aligned holes in the cylinder walls which are diametrically opposite each other.

Abstract: A vibrating wire stress meter. The wire is highly tensioned diametrically across the sides of a hollow metallic cylinder and held there by two anchor tubes. A wedge and platen assembly in turn hold this cylinder in a rock borehole such that small stress changes in the surrounding rock cause the diameter of the cylinder to slightly change. This cylinder variation is transmitted to and measured by the preloaded wire by noting variations in its frequency or period of vibration. To cause the wire to vibrate a coil, magnet, and yoke are used as a plural pole electromagnetic plucker.Clamping of the wire is accomplished by highly tensioning the wire between two opposite hollow tubes that are seated in opposite aligned countersunk holes of the cylinder and then extruding the steel tubes around the wire. The wire extends through holes of those hollow tubes as well as the aligned holes in the cylinder walls which are diametrically opposite each other.

Abstract: An apparatus for breaking and cutting rock and similar materials is provided with one or more roller cutter constructions, each comprising an annular cutter rotatably mounted in a housing. Impact forces are applied directly to the cutter intermittently with a reciprocable hammer. The cutter mountings are constructed to permit the impact force to drive the cutting edge of the cutter into rock while substantially isolating the cutter mountings from the hammer impact and rock reaction forces.