Abstract: A measuring device for long-term installation in a bore in a rock formation or detecting gradual changes in bore diameter, especially gradual constriction which might affect the condition of radioactive waste deposited in the bore, utilizes telescoping parts under outward spring pressure. One of the two elements of the transducer which by the relative displacement of these elements measures changes in diameter, is a rod held in a friction mounting on one of the telescoping parts that maintains the position of the device in the bore. The other element of the transducer is fixed on the other telescoping part which also carries limit stops (7,8) which in corporation with a stop (6) on the rod confines the lengthwise movement of the rod to a stroke equal to the maximum measuring range of the transducer. For measuring gradual constriction, the transducer is automatically set to begin with the maximum measureable diameter.

Abstract: The bore hole rock shear testing device of the present invention comprises a case assembly having a longitudinal axis, a driving block, at least one wedge member, and a restraint member. The wedge member is positioned between the restraint member and the driving block and includes a rock engaging surface facing radially outwardly from the longitudinal axis of the case assembly. The driving block and the wedge member have complimentary tapered surfaces which cause the rock engaging surface to be urged radially outwardly when the wedge member is compressed or squeezed between the driving block and the restraint member. Power means are provided for moving the driving block toward the restraint member, and a restraint mechanism selectively holds the restraint member against movment.

Abstract: The soil testing device of the present invention includes a tapered body member having opposite tapered surfaces which converge toward one another at their lower ends. Within one of the tapered surfaces is a cavity having a diaphragm placed thereover. Beneath the diaphragm are a plurality of sensors which extend in a line between the upper and lower ends of the cavity. Means are provided for introducing fluid pressure into the cavity. When the device is inserted into the soil, the sensors sense the various pressures being exerted on the diaphragm by the soil, and record these pressures on a gauge or meter located above the surface of the soil.

Abstract: A borehole stress-meter includes a resiliently radially expandable hollow body within which can be positioned a gage plug having strain gages fixed thereto. The interior section of the hollow body is tapered, as is the gage plug so that advancement of the gage plug within the hollow body will cause the gage plug to become prestressed. The hollow body can be inserted into a bore drilled in earth material whose stress is to be measured by an installation or setting tool. Subsequently, the gage plug is advanced within the hollow body so as to prestress the gage plug. The setting tool is then removed and stress may be measured by an appropriate strain indicator.

Abstract: A device for determining the shear strength of rock and soil is disclosed. The device includes means for supporting the device within a borehole, a primary shaft, a plurality of shearing units slidably attached to the shaft having shear heads which are movable from a retracted position to a material-engaging expanded position, and a slip joint between adjacent shearing units such that the units operate independently from one another. The shearing units apply progressively greater normal forces on the material to be tested and sequentially shear the material being tested.In operation, the device is lowered into a borehole. Then the shearing units are moved from their retracted position to their expanded material-engaging position so as to apply progressively greater normal forces on the material to be tested. An axial force is then applied to the shaft so that the material engaged by the shearing unit closest to the anchor shears.

Abstract: The device of the present invention comprises a frame having at least one sensor mounted thereon. The sensor includes a diaphragm flush with one surface of the frame, a porous filter flush with one surface of the frame, and a strain gauge bonded to diaphragm and in electrical communication with a read-out instrument. A passageway in the frame provides communication between the filter and the diaphragm such that the water pressure of the saturated soil is transmitted through the filter such that the soil pore pressure is exerted on the back side of the diaphragm. Simultaneously, the total pressure of the saturated soil is exerted on the front side of the diaphragm when the device is embedded in the soil. The strain gauge measures the net pressure on the diaphragm which is equal to the soil effective stress, thus giving a direct measurement of such stress.

Abstract: An extensometer for measuring changes in the vertical distance between the roof and floor of a mine opening which comprises; a pair of rigid telescoping members, a tension spring securing said members to each other in a telescoping relationship, a hook for attaching a non-extensible cable to each of said members, and an indicator for determining telescopic movement of said members. The extensometer of this invention is utilized by securing one of said telescoping members to the roof of the mine and the other telescoping member to the floor of the mine with the axis of said members being disposed along the vertical. The telescoping members are secured, under tension, to the mine roof and floor by means of a non-extendible cable such as a steel cable. The indicator for determining the telescopic movement of the members may be a pair of lugs or flanges or other indicating marks, each member of which pair is affixed to a separate telescoping member.

Abstract: A sensor and system for measuring movement between two points includes a plurality of members having bearing surfaces thereon with links pivotally connecting the members in a manner which causes the plurality of members to move into alignment along the direction of movement to be measured as such movement occurs. Two end members of the plurality of members are connected to the points between which movement is to be measured and an optic fiber is woven between the plurality of members causing the members in contact therewith from being aligned in the direction of movement to be measured before such movement occurs. Movement between the two points causes alignment of the members and bending of the optic fiber over the bearing surfaces thereon. Spacing of the members and configuration of the bearing surfaces thereon enable the sensor to measure movement over distances up to one inch or more.

Abstract: To measure the modulus of elasticity of the rock in the wall of a borehole, a plug is cut in the borehole wall. The plug, its base attached to the surrounding rock, acts as a short column in response to applied forces. A loading piston is applied to the top of the plug and compression of the plug is measured as load is increased. Measurement of piston load and plug longitudinal deformation are made to determine the elastic modulus of the plug material. Poisson's ratio can be determined by simultaneous measurements of longitudinal and lateral deformation of the plug in response to loading. To determine shear modulus, the top of the plug is twisted while measurements are taken of torsional deformation.

Abstract: The state of stress in a rock mass surrounding a borehole (21) can be estimated by measuring the initial dimensions of the borehole, cutting a cone-shaped opening extending outwardly from the borehole having a bottom wall (44), and cutting a conical slot (45) from the bottom wall (44) of the cone-shaped opening outwardly from the borehole at an angle to the axis of the borehole. The release of stress on the rock between the borehole and the conical slot results in a change in the dimensions of the borehole. An apparatus for carrying out the measurements includes one or more cutting arms (27) pivotally mounted to a main support housing (26) and capable of being rotated thereon while being pivoted outwardly to cut the cone-shaped opening.

Abstract: An apparatus and method is described herein which simulates and applies soil shear stress conditions to test pipe segments and thereby induces the mechanical soil stress effects upon adherent pipeline anti-corrosion protective coatings. A test pipe segment having an adherent anti-corrosion protective coating is emplaced centrally in a test apparatus housing chamber, having both a concentrically-located soil reservoir in contiguous contact with said test pipe segment, and a gas pressure reservoir surrounding said soil reservoir. Desired movements of said test pipe segment are controlled and regulated by a universal testing machine. Gas pressures in the gas pressure reservoir exerts pressure on the soil reservoir, thereby simulating soil stress forces on the centrally disposed pipe segment with its adherent anti-corrosion coating.

Abstract: An inexpensive device which is easily operated to accurately measure the Coulomb parameters of the soil. The Coulomb parameters are used in Coulomb's equation to calculate the shearing stresses along a failure surface of the soil. The device includes an instrument to test soil shear strength to which several weights have been added. To obtain the Coulomb parameters, the instrument is placed on the soil to be tested and weights are incrementally added to it. The instrument is rotated at each weight increment and the shearing stresses are read from its calibrated dial. The stresses are plotted on a graph from which the Coulomb parameters are determined. The shearing stress of the soil with any known force applied to it can then be determined.

Abstract: In a rod extensometer for measuring movements in rock structures and in foundations, the measuring rod system consists of a one piece flexible rod made of reinforced plastic and surrounded by an encasing tube and connected at one end to a fixed-point anchoring device and by its other end to a pick-up element for the measuring value. This design enables the rod extensometer to be inserted into a borehole at short notice and with very little loss of time. Furthermore, the rod can form a practically endless structure wound onto a delivery spool and thus stored and transported with ease and in a space-saving manner.

Abstract: Measurements of the deformability of deep rock masses are made by positioning a borehole jack (20) having opposed bearing plates (22, 24) in a borehole at a position at which measurements are to be made, and driving the pressure plates (22, 24) apart to displace the walls of the borehole. A lateral displacement probe (30) is mounted between the pressure plate surfaces in position to detect and measure displacements of the wall of the borehole at points lying on a diameter perpendicular to the direction of the resultant of the equal and opposite forces applied by the pressure plates (22, 24) to the wall (21) of the borehole. The lateral displacement probe (30) includes probe tips (35) that are biased firmly against the wall (21) of the borehole to move inwardly or outwardly therewith. A displacement transducer provides an output signal transmitted to the surface which is indicative of the displacements of the probe tips (35).

Abstract: A method for controlling parametric variations in processes where one variable is subject to an exponential change with time. One application is particulary advantageous in underground mine roof bolting using mechanical anchors where a device utilizing the method can be employed to install mine roof bolts at varying initial tensions in such a manner that the bolt tensions found among a population of roof bolts converge to one tension value within one or two hours after installation due to individual differences in tension decay rate. Since roof bolt tension decay bears an exponential relationship to time, variability in bolt tension which develops after mentioned convergence has taken place is small for a long period of time, in marked contrast to a conventional installaton which is characterized by bolt tension variability which grows rapidly into a far wider range immediately after installation.

Abstract: A device for alerting miners of an unsafe condition existing in mine shafts includes a surface-engaging member, a chamber-defining member having a compressible medium therein, and a plunger connected between the surface-engaging member and chamber-defining member. The plunger is slidably engaged with the chamber at one end in contact with the compressible medium therein so that the plunger moves in response to a compression force applied to the surface engaging member and applies pressure on the compressible medium. A switch for actuating an alarm in response to a predetermined amount of movement between the surface-engaging member and the chamber-defining member, is provided and a visual indicator operatively associated with the compressible medium is utilized so as to set the switch to establish the predetermined amount of movement necessary to actuate the alarm.

Abstract: A deformograph comprises a sensitive element shaped as a tube of an optically sensitive material and fixed in a borehole by cementing the gap between said tube and walls of the borehole. One end of the tube is tapered off and provided with a specular coating, while the other end thereof has a specular coating with transparent sections. There are also provided a polarized light source furnishing a light signal transmitted through the material of the tube, and a sensing unit designed to pick off from the sensitive element a useful light signal indicative of the changing condition of the earth's crust in a given area.

Abstract: A thin shell pressure sensor for sensing in situ pressures in a medium in which the sensor is embedded is provided. The sensor operates on the principle that the membrane stresses near the apex of a thin shell under an external pressure load are proportional to the applied pressure. The constant of proportionality is dependent only on the geometry of the sensor.

Abstract: This invention relates to a method of gathering information from sensors from which the Young's modulus, Poisson's ratio, and the two principal stresses can be obtained. The absolute secondary principal stresses can also be obtained. The method involves the placement of two inclusions of different, but known, physical properties in a single bore hole with a strain or displacement rosette sensor placed in each inclusion and oriented so as to measure physical properties on a plane normal to the bore hole axis. It is extremely important that intimate contact exists between the inclusions and the bore hole surface, because the physical properties of the two inclusions are different and the interactions between each inclusion and the rock mass will be different. The measurements from each rosette sensor and the known physical properties of each inclusion, the Young's modulus, the Poissons ratio, and the two principal stresses for the rock mass can be derived by known mathematical formula.

Abstract: A method for controlling parametric variations in processes where one variable is subject to an exponential change with time. One application is particularly advantageous in underground mine roof bolting using mechanical anchors where a device utilizing the method can be employed to install mine roof bolts at varying initial tensions in such a manner that the bolt tensions found among a population of roof bolts converge to one tension value within one or two hours after installation due to individual differences in tension decay rate. Since roof bolt tension decay bears an exponential relationship to time, variability in bolt tension which develops after mentioned convergence has taken place is small for a long period of time, in marked contrast to a conventional installation which is characterized by bolt tension variability which grows rapidly into a far wider range immediately after installation.

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: In the medium to be examined there is embedded a measuring tube which possesses at its inner surface essentially equidistantly spaced measuring markers. These measuring markers are in the form of mechanical stops or impact members having an impact surface forming part of a right circular cone. To determine the spacing between neighboring measuring markers there is provided a measuring probe or sensor having two measuring heads connected with one another, by means of a connection tube, such that they are relatively shiftable in the lengthwise axis of the measuring probe. Each measuring head is constructed as a mechanical counter stop having an impact or stop surface forming part of a spherical surface. Internally of the connection tube there is arranged an inductive length transmitter producing an output signal characteristic of the spacing between the measuring heads.

Abstract: A material tester of minimal thickness is provided. A thin metal plate has in one surface an annular groove, and within the groove the plate thickness is reduced, to an amount less than the groove depth. A flexible diaphragm extends over the central part of the plate and over the groove, and is clamped to the plate by an annular ring overlying the groove. Passages extend in the plate from an edge to a chamber defined by the diaphragm and the central portion of the plate. A supporting structure including a handle is attached to the plate, and conduits extend between passages in the handle and the passages in the plate.

Abstract: A device for determining microscopic motion in static creep and dynamic oscillation between two objects by measuring relative displacement between the two objects connected by a metal wire includes a linear variable differential transformer disposed within a cylindrical housing. One end of the housing includes an extendable tubular member which is joined to one of the objects, The other end of the housing includes a fitting for securing a wire extending to the other object. The core of the linear variable displacement transformer is supported by a pair of spider diaphragms disposed on opposite sides of the transformer. The tubular member is connected by an extension spring to one of the diaphragms, while the wire retaining fitting is connected by a universal joint to the other diaphragm. The diaphragms provide high axial compliance so that the core may undergo microscopic displacement in concert with the displacement between the two objects.

Abstract: A device and method for determining compressive strength of solid matter in situ. One embodiment is particularly advantageous in underground mine roof bolting, where the device can be used to indicate the compressive strength of the rock immediately surrounding the roof bolt anchor. Such compressive strength indication is developed for each bolt installed as it is installed using no machine operator time or effort beyond the time and effort normally used already. The compressive strength indication is developed by monitoring rate of bolt head torque increase with respect to bolt head rotation and relating these to anchor tooth penetration parameters and hence rock compressive strength.

Abstract: An improved method and apparatus for monitoring from time to time earth/soil/rock movements. The invention comprises a simplified apparatus for use in a vertically driven hole into an underground earth/strata formation for such purposes; and features use of vertically aligned but spaced apart casing sections in a single bore hole. The casing sections are individually bonded to adjacent strata, whereby movements thereof relative to one another may be monitored by means of a single, repeatedly usable torpedo suspending and subterranean level reading line.

Abstract: A ferrite core is suspended from the base of a borehole in a tunnel roof structure and is positioned within coil turns located at the roof surface such that movement of the roof structure causes displacement of the core with respect to the coil turns thus producing a change in inductance. The coil and core are incorporated as a frequency-determining element in an LR oscillator. Therefore, movement of the tunnel roof structure is reflected as a change in the frequency of the oscillator. This frequency is monitored and, if the change exceeds a predetermined threshold, an alarm is given. Several methods of suspending the core in the coil are disclosed, one of which allows for a non-verticle borehole.

Abstract: A device for measuring movements or deformations has at least one pair of variable reactance movement pick-ups, each pick-up comprising transducer elements whereby a modified inductive or capacitive reactance signal is generated by each pick-up in response to the movements or deformations. The variations of the reactances of the two pick-ups are arranged to be equal but opposite. An electrical oscillator is connected alternately to the two pick-ups by automatic switching elements, and each pick-up alters the oscillation frequency in dependence upon the variation of its reactance. The required measurement is derived from the difference between the two altered frequencies.

Abstract: An extensometer anchor for use in a mine borehole. The anchor has an anchor body that, when in an operative mode, is placed in the borehole. Extending at least partially around the outer surface of the body are one or more grooves whose major plane is generally perpendicular to the length of the borehole. Seated within each groove is a compressible resilient anchor member, like a ring, which remains loaded by a retaining device, such as a cotter pin, extending through it. Upon being pulled from outside of the borehole, the retaining device unloads the compressed anchor which then moves to expand outwardly in the borehole and firmly anchor the anchor body and attached extensometer within the mine borehole.

Abstract: A mine warning device which comprises tensioned arms that abut the roof of an underground mine. The arms support a cone shaped shaft which is attached to a warning indicator. The indicator remains invisible within the body of the device when the rocks forming the roof are stable. Upon a shifting of the mine roof, which applies pressure to the arms of the device, the shaft is released and the warning cylinder falls into view. Preferably, the device attaches to bolts that hold plates to the mine roof and the warning indicator is fluorescent.

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: Movement of the roof of a mine shaft is detected by unlatching of a position sensing device in an elevated position causing it to drop to a lowered position pivotally suspended by a link from a bracket yieldably held in abutment with the roof ceiling. The bracket is positioned on the lower end of an elongated support bolt by a nut acting as a latch releasing member engageable with a latch element connected to the link for latched support of the sensing device in the elevated position.

Abstract: A shear transducer having two cylindrical bending beams with two full strain gage bridges so arranged to cancel acceleration induced by forces in the axis of interest.

Abstract: A device to monitor movement of a surface such as, for example, the roof of a mine tunnel or the like and to provide an indication if that movement exceeds some predetermined creep rate or velocity. The device includes a sensing member formed of a material whose precise creep characteristics as a function of stress and strain are known. The device includes a sensing member formed of a material whose precise creep characteristics as a function of stress and strain are known.