Abstract: A Device for driving rods used primarily for soil mechanics tests into the round, of the type comprising a traction and compression resistant tubular one-piece rod (42) made of a material and capable of being curved by reversible elastic derformation, a drum (44) for winding said rod (42) and a device (46) for driving and extracting said rod.

Abstract: A method for measuring the three dimensional stress in rock surrounding a borehole comprises the steps of cutting slots into the wall of a borehole at different angles relative to the borehole axis so as to effect stress relaxation and strain deformations which are representative of the stresses normal to the angle of the respective slots, and measuring the respective strain deformations adjacent to the slots that are being cut into the borehole wall at a sufficient number of angles to satisfy the mathematical requirement of six independent equations to solve for the three dimensional stress tensors so as to determine the three dimensional stress field surrounding the borehole from measurements in a single borehole.

Abstract: A device for measuring the deformation of a structural component comprises a sensor installed at a first end of a hollow bore in the structural component, the sensor having a measuring surface and producing an electrical signal indicative of a deformation in the measuring surface, and a transmission element which passes through the hollow bore. The transmission element has a first end which is supported by the structural component, and a second end which bears upon the measuring surface of the sensor, so that a deformation which occurs in the structural component will be transmitted to the measuring surface by the transmission element.

Abstract: A measuring instrument includes first and second rigid, elongate measuring elements which are interconnected by a flexible element. The measuring elements are supported in a measuring tube inserted in the foundation soil. Whenever a displacement occurs in the foundation soil or construction, the measuring tube is deformed and the second measuring element is pivoted with respect to the first measuring element. The curvature or bending which thereby occurs in the flexible element of suitable dimensioning or configuration is preferably determined by at least one wire strain gage fitted to the flexible element in the plane of deformation, the elongations being converted, for example by use of a Wheatstone bridge circuit, into proportional electrical current or voltage signals. Preferably, wire strain gages are disposed on all four mutually perpendicular outer sides of the flexible element, in order to allow for the detection of displacements in mutually perpendicular planes.

Abstract: A remote sensing system is provided which operates as a bipolarized, differential mode, LDI (laser differential interferometry) system to detect an electrical signal produced at a remote location. The system is adapted to reduce the effects of turbulence induced frequency fluctuations by using an array retroreflector apparatus which converts a single sensing beam into a single return beam having two, overlapping, transversely polarized sensing signals; thus, turbulence induced noise will be common mode to both return signals and cancel at the receiver.In preferred embodiments, the system is used to remotely detect an amplified array signal from a plurality of seismic detectors (e.g., geophones or hydrophones) connected to form an array at the remote location. The target is coupled to common motions at the selected location and the amplified array signal is coupled to an optical component within the target.

Abstract: A shock wave gauge (20) is made from a piece of pure-quartz glass rod (22), or other suitable transparent mineral material. A segment (38) of the rod is uniformly heated above its melting point. The heated segment is then drawn away from a non-heated body segment, forming an optical fiber thread (26). The thread is thinned to a desired size while the rod material is still above its melting point. Upon cooling, the fiber optic thread is cut to a desired length. The body segment (24) of the rod and fiber optic thread (26) drawn therefrom comprise the gauge. The gauge is preferably assembled inside of a housing (34) to protect the thread, with at least one end (24') of the body segment protruding out from the housing. In use, a shock wave impacts the exposed end of the body segment. The pressure of the shock wave causes the temperature of the rod material to rise by an amount proportional to the pressure.

Abstract: A monitoring unit for installation on a cable bolt comprises a tube designed to fit within a cable bolt hole and having a collar at one end thereof, a cable bolt adapted to be grouted in the rock at the centre of the tube, a base plate placed tightly against the tube collar adjacent the rock face, a centralizer sleeve designed to fit over the cable bolt to keep the cable centralized within the base plate and tube, an elongated measuring plate having a centre hole for insertion of the cable bolt to fit tightly against the base plate and a groove cut at equal distances from each side of the centre hole for allowing the measuring plate to bend if the rock moves with respect to the cable bolt, and a cable clamp for fixing the measuring plate tight against the base plate.

Abstract: A slope monitoring device includes a cable anchored at one end to the sloped wall of an open pit mine, dump, or the like. The cable extends over an idler pulley at the top of the sloped wall and passes around a further pulley coupled to an optical shaft encoder which generates a digital signal corresponding to the angular position of the pulley. The cable is engaged by a clutch and is wound about a play-off reel, each secured to a weighted sleeve slidingly extending about a vertical post. The weighted sleeve maintains tension upon the cable, while the clutch allows additional cable to be played off of the reel when tension is increased due to movement of the wall. The shaft encoder information, along with the temperature, battery condition, and cable condition, are transmitted by radio to a remote location for processing.

Abstract: A formation test tool is set forth in the present disclosure and has a snorkel on one side and upper and lower diametrically opposite back-up pistons on the opposite side. The back-up pistons are constructed with a back-up plate on the end of the back-up piston encircling and centered around a formation punch. The formation punch has a small diameter and specified length so that, during operation, the punch contacts the sidewall of the well borehole, and pressure is increased thereafter to force the punch into the formation until fracture failure occurs evidenced by a change in hydraulic pressure and a lurching movement of the back-up piston as the punch penetrates the formation. By knowing the diameter of the punch and by observing the hydraulic pressure necessary to obtain failure of the formation at the point of contact with the punch, data can be obtained which is indicative of the compressive strength of the formation.

Abstract: A rockbolt monitor monitors increased loadings on a rockbolt in underground mines. The monitor includes a rockbolt plate fitted on the rockbolt to engage the surface of the rock, a stack of belleville washers on the end of the rockbolt outside the rockbolt plate and a spring seat plate outside the belleville washers. When a nut is fitted onto the rockbolt and torqued, the belleville washers will compress to provide the desired force urging the rockbolt plate against the surface of the rock. This spring arrangement allows relative movement of the rockbolt plate on the rockbolt in response to ground movement, such as caused by blasting. The load indicator itself includes a threaded sleeve screwed into a threaded bore in the spring seat plate. A spring loaded piston rides in the sleeve. It is biased into engagement with the rockbolt plate.

Abstract: A landslide detecting apparatus which is laid under the ground include: a light source; a lens device for converting a beam of light from the light source into a parallel pencil of rays; a condensing lens device; a light detecting device; and a shading mechanism adapted to partly or entirely intercept the pencil of rays in response to external pressures applied thereto. Any change in the earth's crust in a direction to cause a landslide causes the shading mechanism to operate in correspondence with the magnitude of the change so as to partly intercept the parallel pencil of rays and cause a change in the quantity of light detected, making it possible to obtain a quantitative knowledge of the change in the earth's crust.

Abstract: A device for testing the loading of a test pile extending downwardly into the ground. The device includes a reaction pile axially disposed inside the test pile and a reference pile axially disposed inside the reaction pile. The reaction pile extends further into the ground than the test pile and the reference pile extends further into the ground than the reaction pile. A loading device simultaneously exerts a downward force on the test pile and an upward reaction force on the reaction pile such that the test pile moves downwardly, and a laser distance measurement system, attached to the test pile and extending axially therewith, also moves downwardly. The laser distance measurement system resides in a test chamber defined by a shroud circumscribing the test device and secured to the top of the test pile so as to move downwardly therewith.

Abstract: A method of performing small scale micro hydraulic fracturing in which fluid is pumped into the test interval until the initiation of a fracture is indicated, immediately after which fluid is pumped out of the interval so as to prevent propagation of the fracture and allow closure thereof, the portion then being repressurized by pumping fluid back in. By pumping out when the fracture is initiated, propagation is substantially prevented allowing estimation of the fracture length and toughness to be obtained and the time taken for the measurement reduced.

Abstract: A downhole penetrometer comprising a body which can be lowered into a borehole and including a tooth and an associated actuator for moving the tooth radially outwardly from the body so as to penetrate the wall of the borehole, a sensing arrangement being provided for determining the force applied to the tooth and the extent of penetration of the tooth into the borehole wall. A motor and pump arrangement is included to power the actuator, power typically being provided by a wireline which can also be used to communicate readings to the surface. A pair of inflatable packer modules are situated above and below the tooth to isolate an interval of the borehole in which a measurement is being made.

Abstract: A method of determining capability and quality of a foundation pile and a method of designing the foundation pile comprises the following steps: positioning a ground charcteristics analyzer in a bored hole where the foundation pile is constructed; displacing the surrounding ground of the bored hole; and measuring the force applied to a bored hole and the induced displacement; so that the characteristics and quality of soil and the pile can be analyzed simultaneously with executing the construction. A ground characteristics analyzer with which the above-mentioned methods are performed comprises a horizontal pressing device which protrudes in the radial direction from the outer peripheral of the body of the analyzer to displace the surrounding ground of a bored hole and a vertical depressing device which protrudes downward to deform the bottom ground of the bored hole.

Abstract: The invention relates to a device for monitoring strain or deformation within rock boreholes in three-dimension. The device comprises in general a vibrating wire strain monitor for monitoring strain or deformation in an axial direction with respect to the borehole axis interposed between two other vibrating wire string monitors which monitor strain or deformation in radial directions with respect to the borehole axis. The radial vibrating wire strain monitors each have elements by which they may be anchored within a borehole. Together, the three vibrating wire strain monitors monitor strain or deformation in three orthogonal directions within a borehole. The combination allows the axial vibrating wire strain monitor to utilize the radial vibrating wire strain monitor's anchors thereby eliminating their requirement to provide separate anchoring means therefor.

Abstract: Methods and apparatus for monitoring the compaction of backfill material in an excavation include hammer structure for impacting backfill material in the excavation, a sensor module for disposition at the bottom of the excavation to be backfilled that includes a transducer for developing an electric signal in response to energy transmitted through backfill material from the hammer structure, and a control module responsive to electric signals from the sensor module for providing an indication of the quality of compaction of backfill material in the excavation.

Abstract: A fluid squeeze monitor downhole tool and a method of monitoring formation squeeze features a tool body that can be placed downhole at a desired elevational location to produce a controlled, localized reduction of pressure head and measure the resultant inward displacement of the borehole wall. The reduction in head is accomplished by draining the fluid in a bladder (or collapsible container) located on the tool body into a reservoir "sump" that is incorporated into the downhole tool.

Abstract: A method of determining capability and quality of a foundation pile and a method of designing the foundation pile comprises the following steps: positioning a ground characteristics analyzer in a bored hole where the foundation pile is constructed; displacing the surrounding ground of the bored hole; and measuring the force applied to a bored hole and the induced displacement; so that the characteristics and quality of soil and the pile can be analyzed simultaneously with executing the construction. A ground characteristics analyzer with which the above-mentioned methods are performed comprises a horizontal pressing device which protrudes in the radial direction from the outer peripheral of the body of the analyzer to displace the surrounding ground of a bored hole and a vertical depressing device which protrudes downward to deform the bottom ground of the bored hole.

Abstract: A method for obtaining in-situ stress measurements in a well is accomplished by installing a membrane packer on a drill string. The packer membrane is attached near the drilling tool and is capable of being radially expanded by fluid pressure to abut against the borehole. When a measurement of the in-situ stress is desired, a 3 way valve is actuated to divert drill string fluid into the packer until the membrane contacts the borehole. Further increments of fluid addition at this point are accomplished only by large increases in inflation fluid pressure. Pressure is increased (with little increase in volume) at a ramp rate until it reaches a value equal to the least principal stress, at which point the formation microfractures. The microfracture(s) result in a decreased pressure and/or volume ramp rate, which indicate their presence. Further pressurization would generate similar indications of fractures resulting from intermediate and maximum principle stresses.

Abstract: A borehole strain monitor for soft rock consisting of a sensing unit, an installation/retrieval provision and a read-out unit. The sensing unit has a U-shaped yoke and is fitted with a vibrating wire transducer. A magnetically coupled variable frequency oscillator determines the point of resonance for the tensioned wire. The resonant frequency is measured with a frequency counter. The sensing unit is used, typically, in boreholes between two and six inches in diameter. The unit is firmly seated in the borehole by means of a pad at one side and a positively guided wedge at the other to bring the unit in contact with diametrially opposed portions of the borehole wall.

Abstract: A system 10 for measuring deflection and/or deformation of a layer in a pavement structure under load is disclosed and claimed. The system comprises at least one apparatus 11 including electric coils 17 sensitive to relative movement between them and a separately anchored body 18 of ferromagnetic material. The apparatus 11 comprises two longitudinally spaced relatively moveable discs 19, 22 and a body 21 of a resilient, transversely expandable material between the discs. A nut 25 serves to urge the discs 19, 22 towards one another thereby causing the body 21 transversely to expand to secure the apparatus at a predetermined depth against a wall in a test hole.

Abstract: A protective tube is vertically buried in the ground, and sinking elements for generating magnetism are buried at plural positions at different depths in the ground outside the side wall of this tube. Magnetic sensors capable of detecting magnetism are disposed in the tube to detect the magnetism generated by the sinking elements, and the depth position of the sinking elements in the ground is measured according to the detected signal, so that the fluctuations by settlement or uplift of the ground may be known by each bed differing in depth. A plurality of magnetic sensors are fixed to the side wall surface of the tube, corresponding to the individual sinking elements.

Abstract: A strain gage assembly is secured between two initially longitudinal locations on the exterior of a flexible elongated member, such as a steel structural cable, or an electrical transmission cable, or a glass fiber optic communication cable, to thereafter upon the subsequent pre-stressing and/or the possible excessive straining of the cable, create an observable or transmittable reading of the excess tensile and torsional strain being sustained by the flexible elongated member. This assembly, in one embodiment, has an in line arrangement of a vibrating wire strain gage, the vibrating wire thereof secured to a calibrated coiled spring, in turn secured to an inner tube shaft, in turn telescopically fitted within an outer tube shaft, secured to the vibrating wire strain gage. Using two spaced securement means, this strain gage assembly is secured to the exterior of a flexible elongated member.

Abstract: A method and apparatus to determine in-situ "creep" displacement in a cored or drilled borehole. A borehole creep displacement (BCD) tool is suspended into the borehole via a wireline logging cable. Gaging piston fluid forces gaging pistons in a mechanical/electrical assembly of said tool to extend and contact the borehole wall which causes gaging pressure to build. Upon reaching a predetermined pressure, excess fluid flows into a micro-motion fluid distribution body and into an actuator assembly causing an accumulator linear variable displacement transformer (ALVDT) to move thereby causing electrical signals to be transmitted to surface equipment. Once the LVDT has been displaced fully, a closed fluid system within the gaging pistons and a micro-motion assembly is created. Thereafter, any movement of the gaging pistons by the borehole wall will cause fluid motion of a micro-motion cylinder which is attached to a micro-motion LVDT.

Abstract: A method and apparatus of measuring rock-stress uses a tapered sensing plug which is wedged into a conically shaped end portion of a borehole. A rod is used to place the sensing plug in position, to orient the plug relative to its longitudinal axis for sensing stress in a particular direction, and to prestress the sensing plug by causing same to be wedged in the tapered portion of the bore.

Abstract: The present invention relates to a method and apparatus for measuring subsidence by evaluating the distance between radioactive markers which have previously been implanted in the formation traversed by a borehole. The apparatus comprises an elongate body containing at least two nuclear detection assemblies which are spaced apart along the longitudinal axis of the body. Each detection assembly inludes at least one position sensitive detector for detecting position along the longitudinal axis of the body. Measurements are performed while the apparatus is held stationary opposite the markers.

Abstract: A sensor unit is disclosed for use in monitoring in situ changes in dynamic and static stress properties of any material to be monitored, such as monolithic concrete or underground rock structures. The sensor unit includes a hollow, waterproof tubular body to be inserted into a cylindrical borehole in the material to be monitored. A transducer is mounted within the body, which by means of strain gauges, provides an output signal responsive to deflection of the sidewall of the borehole. The transducer is coupled to the sidewall by means of pressure buttons. A monitor is also disclosed, which comprises the sensor unit, a data collection unit and a data analyzing unit. A method for sensing dynamic and static changes in material stresses is also disclosed.

Abstract: A quality undisturbed sample of of cohesionless soil, in which the in-situ state of stress and strain is kept, can be obtained by in-situ freezing of the soil and subsequent removal of the frozen sample for testing. The in-situ horizontal stress in the cohesionless soil can be determined by the thawing the high quality undisturbed sample or, alternately, the frozen hole made in the frozen ground. A test apparatus and procedure for each of the two alternatives adjusts the pressure on the cylindrical sides of the sample or of the cored hole in the ground, to maintain the respective diameter as thawing occurs. The final pressure indicates the horizontal stress. In the case of testing the cylinder-shaped sample removed from the ground, it is loaded axially to reproduce the vertical load conditions at the level in the ground from where it was taken.

Abstract: A transducer is placed in a telescopic strut and connected to a roof cam and a floor cam. The cams are pivoted to a roof support and a constant load is applied to the cams by a gas spring. As convergence takes place a transducer in the telescopic strut records the relative movement between the floor and roof and transmits this as an electrical signal for analysis.

Abstract: This invention is a stress gauge whose components include a piezoresistive sensor embedded in epoxy, a flatjack, and a housing for the sensor and flatjack. The preferred piezoresistive sensor is ytterbium because of its sensitivity to pressures in the range of interest. This arrangement allows the gauge sensing element to be calibrated at the place of measurement. That calibration is provided by a well controlled uniaxial load applied to the gauge to test the gauge response. Upon removal of the applied load, the gauge can continue to measure the stress history of the surrounding medium.

Abstract: A vibrating wire strain meter has a steel proving ring across the bore of which extends a taut wire. The outer surface of the proving ring has sloping or tapered grooves extending axially along the entire length of the ring. A pair of diametrically opposed wedges sloping at the same angle as the grooves are used to wedge the proving ring in a borehole. The tapered grooves provide positive guiding of the wedges such that the device can be positioned accurately and repeatably in relation to the borehole wall. Preferably, the wire extends across a diameter which is perpendicular to the diameter on which the grooves and wedges are located. A novel tool for inserting and withdrawing the strain meter is also described.

Abstract: A complete, three-dimensional stress state of underground rock is determined by a method which includes the steps of: drilling a rock to form a borehole with a substantially spherical bottom; deforming the borehole either by releasing the rock from the stresses by overcoring or by applying an external static pressure to the rock; and measuring displacements of the spherical bottom in at least xx, yy, zz, xy, yz and zx radial directions during the deformation of the borehole.

Abstract: A conventional borehole shear tester is modified by incorporating a volume-monitoring accessory in the non-pressurized chamber vent line. This accessory includes a fluid reservoir operatively connected to the non-pressurized chamber of the shear head unit. A change in the level of fluid in the reservoir indicates changes in the volume of the non-pressurized chamber, which in turn indicates a change in shear head diameter. By maintaining a constant fluid level in the reservoir, the volume of the non-pressurized chamber remains constant and the shear head diameter remains constant. Thus, with the shear head diameter fixed, the normal pressure exerted on the wall of the borehole varies as the soil dilates or consolidates. Accordingly, the modified borehole shear tester of the present invention simulates friction pile behavior.

Abstract: Apparatus for use in testing the mechanical behaviour and deformation characteristics of rocks and the like at various locations in a borehole comprises a pressure intensifier used in conjunction with a dilatometer head, the two being rigidly interconnected so as to be lowered into the borehole. The pressure intensifier comprises a cylindrical housing providing upper and lower cylinders, and a double action piston which provides a 6 to 1 differential between the input pressure side and the output pressure side. Pressure changes are measured by means of a pressure transducer, and volumetric changes are determined from measurements of the linear displacement of the piston. Such linear displacements are measured by means of a shaft encoder coupled to a motion translating device for translating linear displacement into rotary displacement.

Abstract: A borehold probe includes a soft outer plastic cylinder secured to a central mandrel and inflatable by hydraulic pressure conducted therethrough to impinge upon the sidewall of a borehole with controlled pressure. A plurality of LVDT diameter sensors is secured to the probe in planes perpendicular to the axis thereof and spaced angularly thereabout. A plurality of acoustic transducers is also secured to the exterior of the probe to monitor acoustic emissions as well as to survey the earthen media with ultrasonic emissions. The cylinder inflation pressure is increased gradually to exceed both the tensil strength of the media and also the principal stress therein to initiate fracture of the media surrounding the borehole. The cylinder is then deflated to unload the fractured media, and gradually reinflated to first elastically deform the fractured media and then re-expand the fractures previously created.

Abstract: A highly portable pressure intensifier for use with a borehole dilatometer head having an expandable body defining an internal cavity to measure deformation properties of in-situ rock masses. The housing of the intensifier comprises two axially aligned interconnecting cylinders, one of which is of substantially larger diameter. The larger cylinder has a reciprocating piston mounted therein, the piston having a plunger portion which extends axially into the smaller cylinder. The smaller cylinder is connected to the cavity of the dilatometer head by means of high pressure tubing. The larger cylinder is filled ahead of the piston with a first working liquid. The second cylinder, the dilatometer head cavity and the interconnecting tubing are filled with a second working liquid.

Abstract: A device positionable in a borehole for monitoring relative mass displacements axially along the borehole between at least two spaced-apart anchor points, comprises at least two retrievable anchor members arranged in spaced-apart opposite relationship to define the at least two anchor points, the anchor members each having radially displaceable borehole wall contacting means and including mechanical means for radially outwardly displacing the borehole wall contacting means to engage the borehole wall and thereby fix the anchor member in the borehole against the wall thereof. A linear displacement sensing means is arranged between the anchor members, the displacement sensing means being connected to one of the anchor members and including an elongated axially movable sensor element, the sensor element being normally biased in a direction toward the other anchor member for contact engagement therewith.

Abstract: Earth's crustal stress is measured by drilling a bore-hole in rock body, producing a longitudinal crack at a selected portion thereof with or without a natural traverse crack through intermittent application of hydraulic pressure thereat while measuring the pressure at different stages of crack production, producing an artificial traverse cracks through the use of a prenotch, determining orientations of the cracks thus produced by inspecting the bore-hole surface conditions, and numerically analyzing the crack orientations and the pressures at different stages of crack production.

Abstract: An improved back-pressured pneumatic pressure cell is provided along with a method of using the same. The device includes at least one sensing cell mounted on a blade for insertion into the soil. The cell includes a perforated outer ring and a perforated central disk separated by a threshold. A resilient membrane covers the outer ring and central disk. A first back-pressure is applied through the perforations of the outer ring to the membrane, while a second back-pressure is applied through the perforations of the central disk to the membrane. The second pressure is slightly less than the first pressure. When the first pressure reaches the soil pressure, the seal between the membrane and the threshold is broken, thereby permitting a momentary reverse flow of pressure through the perforations of the central disk until the first and second pressures equalize, as monitored by a differential pressure gauge. A valve regulates the pressure differential between the first and second pressures.

Abstract: A pressure-measuring transducer device for transforming a change of tested pressure into a change of output signal frequency. Variable reluctance sensing elements and an FM IC block are assembled together in a base. The transducer device can have a variety of configurations and external forms and is sturdy and reliable, tightly sealed, interference resistant, and adapted for use in measuring dynamic and static pressures of different mediums. The pressure transducer has a piston type double film, and the base is made of aluminum alloy and is "honeycombed". The specific gravity is approximately equal to that of soil. It is adapted for measuring soil pressure or boundary soil pressure of reinforced concrete structure and pressure of loose solid substances. An alternate embodiment is used for measuring pore pressure in soil. Several forms of filtering devices are provided.

Abstract: A method is provided for determining at least one characteristic magnitude of a geological formation from a so-called characteristic set formed of three magnitudes designated respectively by K.sub.1C, .sigma..sub.3 and H.sub.F which are the stress intensity factor of the formation, the minimum in situ principle stress and the fracture height knowing at least one of these magnitudes. In this method, the geological formation is subjected to a fracturing operation during which the minimum pressure reached during the fracturing and the volume V.sub.m of the fracture at the time when the pressure is minimum are determined. Then the desired characteristic is determined from mathematical relationships.

Abstract: A testing apparatus for measuring soil shear strength which includes a torque motor connected to a torque shaft, torque cell and vane which extend beneath the soil surface. The torque cell is located between the shaft and the vane; and measures soil shear strength. It includes a torque transmission member on which an electrical transducer is mounted; and a housing which surrounds the transmission member and defines an annular cavity which protectively surrounds the transducer.

Abstract: A technique and apparatus for estimating in situ stresses by measuring stress-induced velocity anisotropy around a borehole. Two sets each of radially and tangentially polarized transducers are placed inside the hole with displacement directions either parallel or perpendicular to the principal stress directions. With this configuration, relative travel times are measured by both a pulsed phase-locked loop technique and a cross correlation of digitized waveforms. The biaxial velocity data is used to back-calculate the applied stress.

Abstract: A device which separately measures the skin friction and the load-bearing capacity of the earth at the bottom of a hole. An expansion device is in the bottom of the hole, with a shaft resting on top it. A pressurized fluid is pumped into the expansion device, via a coaxial pipe and rod, to fill and expand it. By observing the movements of the rod and pipe responsive to the expansion and relative to the ground surface, it is possible to record the pressure versus upward movement of the shaft and the pressure versus downward movement of the earth below the bottom of the shaft. The ultimate or maximum skin friction is indicated when the load-upward movement curve plotted from the data indicates no further increase in load with upward movement. The ultimate end bearing capacity is indicated when the load-downward movement curve indicates no further increase in load with downward movement.

Abstract: The invention relates to pressuremetric apparatus used to determine the mechanical properties of soil.The apparatus comprises means which include solenoid valves (10, 14, 19), pressure sensors (11, 16, 20), and an electronic unit (21) which controls the solenoid valves on the basis of information from the sensors and of preselected information, so as to automatically provide a pressure rise, in accordance with the desired program, in the dilatable cell of the pressuremeter.The invention is useful in controlling the pressure rise in probes of pressuremetric apparatus.

Abstract: A pressure sensor (10) is useful for monitoring stress changes and stress fields in a medium (12) having a borehole (14) defined therein. The pressure sensor uses piston assemblies (22, 24, 26) to transmit pressure changes to gages (84) via a fluid in a fluid line (78). The piston assemblies can be spaced apart angularly and longitudinally of the borehole to monitor a plurality of locations (16, 18 and 20), and are angularly movable with respect to each other.

Abstract: A method and apparatus for testing soil involves a probe with an inner cylinder insertable into the sample to be tested and rotatable through a limited arc of rotation. The inner cylinder may be rotated by an impulse, from an initial condition or by an oscillatory motion. An outer cylinder may be provided concentric to the inner cylinder and spaced therefrom to facilitate the measurement of liquefaction resistance and soil degradation. A motion sensor mounted on the inner cylinder enables the recording of the response of the cylinder and the soil to a particular rotary excitation. A shield may be provided about the upper end of the inner cylinder in order to allow measurements to be obtained from a region sufficiently below the surface of the soil so as to be relatively free from surface effects. A surface compression unit may be provided between the inner and outer cylinders which is operable to supply a pressure to compensate for the loss of overburden in downhole applications.

Abstract: A mine safety system and method of measuring and monitoring the mine roof support stress levels. The information which is continuously gathered is recorded and stored so that a substantially complete history of each selected roof bolt is available to mine management personnel so that a determination may be made as to what action should be taken to protect the safety of the people working in the mine.

Abstract: An instrument for testing earthen samples under triaxial load conditions includes an upwardly extending cylindrical housing with two access windows formed in the side thereof, and a transparent cylindrical sleeve adapted to be slidably received about the housing to seal the chamber within. A lower stage is supported on a laterally translatable bearing block, and connected to a double-acting horizontal hydraulic ram. An upper stage is disposed in superjacent opposition to the lower stage, and is connected to the lower end of a vertical hydraulic ram supported atop the housing. The stages include shallow sockets adapted to receive sample platens in vertical alignment with the vertical ram. The platens each include peripheral grooves adapted to be engaged by swing clamps extending from each stage. Each platen includes a filter stone portion adapted to contact a core sample disposed between the platens, with a fluid channel extending radially through each platen to the filter stone.