Abstract: A two-stage energy dissipation type shed tunnel support structure connected by a principle of Dougong and a design method thereof are provided. The two-stage energy dissipation type shed tunnel support structure includes a Dougong joint domain, crossbeams and columns. The Dougong joint domain includes section steel members, wavy-wall cylindrical elastoplastic buffers, U-shaped sliding connecting troughs and high-strength bolts. Multiple layers of the section steel members are orthogonally stacked to form a Dougong shape, the wavy-wall cylindrical elastoplastic buffers are arranged between adjacent layers of the section steel members, and the U-shaped sliding connecting troughs are arranged at upper and lower ends of the wavy-wall cylindrical elastoplastic buffers, which realizes a connection between the wavy-wall cylindrical elastoplastic buffers and a section steel in two orthogonal directions.

Abstract: Disclosed is a drill and blast method for advancing the tunnel face in a mine, which makes use of a mobile canopy. The mobile canopy having vertical supports connected to a frame that supports a shield. The mobile canopy allows for face production activities and ground support activities to occur simultaneously or near simultaneously. This allows for more rapid advancement of the tunnel face compared to traditional batch drill and blast techniques.

Abstract: Systems for installing roof support sheets on a mine roof. One system includes a support frame, a lifting system, and a feeding system. The support frame holds a plurality of roof support sheets. The lifting system lifts at least one of the sheets from the support frame. The feeding system obtains the at least one sheet from the lifting system and feeds the at least one sheet toward an installation apparatus for installation on the mine roof. The lifting system includes a shoe and at least one arm for moving the shoe to engage and move the at least one sheet. The feeding system includes a drive assembly and a support. The drive assembly engages and moves the at least one sheet toward the installation apparatus, and the support supports the at least one sheet moved by the drive assembly.

Abstract: Systems for installing roof support sheets on a mine roof. One system includes a support frame, a lifting system, and a feeding system. The support frame holds a plurality of roof support sheets. The lifting system lifts at least one of the sheets from the support frame. The feeding system obtains the at least one sheet from the lifting system and feeds the at least one sheet toward an installation apparatus for installation on the mine roof. The lifting system includes a shoe and at least one arm for moving the shoe to engage and move the at least one sheet. The feeding system includes a drive assembly and a support. The drive assembly engages and moves the at least one sheet toward the installation apparatus, and the support supports the at least one sheet moved by the drive assembly.

Abstract: A prop head bearing device used for a shield support and to receive a prop head includes a prop head bearing main body with a prop head receiving portion, a flange adjacent to the prop head receiving portion and a flange bore, and a receiving portion adjacent to the flange and remote from the prop head receiving portion. The prop head bearing device may also include a securing element including a securing element bore adapted in shape to the receiving portion, such that in the mounted state the securing element is locked with respect to the bore direction of the flange bore and that the securing element bore is aligned to the flange bore.

Abstract: A yield support prop for a mine includes a first metal tube extending from the mine floor having a first portion having a first outside diameter and a second portion having a second outside diameter. The prop includes a second metal tube that is disposed about the first portion and extends toward the mine roof, when the second tube receives a load from the mine roof, the second portion deforms the second tube and expands the second tube creating resistance against the load from the mine roof. A method for supporting a mine roof. A method for building a yieldable mine prop.

Abstract: A gob shield for a shield support and a method for producing such a gob shield. The gob shield having a cover plate, two cap connecting joints for connecting the gob shield to a roof cap, and side plate pairs having respectively two side plates with bolt receptacles for the fastening of links of a link mechanism to the gob shield. In order to simplify the production of the gob shield, each cap connecting joint is a component part of a separately producible elongate assembly, which, by a rear end, can be welded in place in the interspace between the side plates of a side plate pair before this master assembly comprising assembly and side plate pair is welded to the cover plate.

Abstract: A support prop which includes telescopically interengaged inner and outer tubular members, a one-way valve for introducing pressurized liquid into a volume inside at least one of the members, a pressure relief valve for releasing liquid from the volume when the liquid pressure in the volume exceeds a predetermined value and a number of wedges which are located between opposing surfaces of the tubular members and which are engaged with one member and which deform the inner member when telescopic yielding action of the members takes place.

Abstract: A longitudinally yieldable support for underground roof support includes a first support section with a first elongate outer shell filled with a solid compressible filler material and a second support section filled with a second solid compressible filler material with a second elongate outer shell extending above the first elongate outer shell. The second support section has density that is greater than a density of the first solid compressible filler material. A pair of attachment members are coupled to the second elongate outer shell and are configured for lifting the second elongate outer shell relative to the first elongate outer shell and for securing the second elongate outer shell relative to the first elongate outer shell once lifted.

Abstract: A prop which includes first and second telescopically engaged tubular members, wherein at least one member is internally pressurized with water and wherein yielding is controlled by means of a friction ring acting between opposing surfaces of the two members and by a release valve which controls the pressure of the water.

Abstract: A prop, for example for supporting the roof of an underground mine, is provided in the form of a vessel. The vessel includes a base having a bottom and one or more sides. A cover, including a top and one or more sides is provided. The top includes a space for accommodating a roof bolt when installed in a mine. Sides of the cover and of the base overlap each other to a maximal extent in a collapsed configuration. A port is formed in the one or more sides for filling the vessel with material when the sides of the cover and of the base overlap each other to a minimal extent in an extended configuration. Consequently the prop is able to go from a collapsed configuration for transportation or storage, to an extended configuration for supporting the roof of the mine. The top of the vessel may comprise a flexible envelope fast with the one or more sides of the cover for receiving the filling, in order to present a deformable upper surface for bearing an uneven load.

Abstract: A yield support prop for a mine includes a first metal tube extending from the mine floor having a first portion having a first outside diameter and a second portion having a second outside diameter. The prop includes a second metal tube that is disposed about the first portion and extends toward the mine roof, when the second tube receives a load from the mine roof, the second portion deforms the second tube and expands the second tube creating resistance against the load from the mine roof. A method for supporting a mine roof. A method for building a yieldable mine prop.

Abstract: The present invention provides a device useful for supporting underground mine/tunnels. The device continuously monitors the roof load coming over the canopy and correspondingly yielding/convergence indicated by the pointer on graduate scale. The roof load coming on the canopy (9) is transmitted to the prop via a set of steel disc springs (5) to increase the yielding and longevity of the present device. The present invention has mechanism for preloading upto the desired load. It is a simple, easily transportable and user friendly device having quick release mechanism from a safe distance.

Abstract: A mine rib support for bracing a vertical mine rib disposed between a mine floor and a mine roof. The support includes an elongated upright and continuous telescopically expandable support having a preset curvature. The member is longitudinally expanded for engaging the mine floor and the mine roof under compression with the curvature facing towards the mine rib. A support plate is laterally extended from the support member into compression engagement with the mine rib, thereby prestressing the support for support of the mine rib.

Abstract: Systems for installing roof support sheets on a mine roof. One system includes a support frame, a lifting system, and a feeding system. The support frame holds a plurality of roof support sheets. The lifting system lifts at least one of the sheets from the support frame. The feeding system obtains the at least one sheet from the lifting system and feeds the at least one sheet toward an installation apparatus for installation on the mine roof. The lifting system includes a shoe and at least one arm for moving the shoe to engage and move the at least one sheet. The feeding system includes a drive assembly and a support. The drive assembly engages and moves the at least one sheet toward the installation apparatus, and the support supports the at least one sheet moved by the drive assembly.

Abstract: A shield cap for a shield-type support for underground mining includes a cap plate, with reception devices for the connection of hydraulic cylinder heads to the shield cap, and a supporting structure welded below the cap plate and having a plurality of longitudinal spars. At least two of the longitudinal spars include substantially I-profile struts having an upper profile chord, a lower profile chord and a middle chord running perpendicularly to the two profile chords. The distance between the upper and the lower profile chord decreases at least over a part length of each strut.

Abstract: A telescoping mine prop is prestressed by engaging the prop with a jack and thereby telescopically expanding the prop against opposing surfaces of the mine with the jack. Thereafter the prop is locked in position and the jack is disengaged from the prop for use with the expansion of another prop, thereby leaving the mine prop in a prestressed condition.

Abstract: A method and device for supporting a structure above a fixed surface. The device can include a support pedestal whose height is adjustable through a range of heights without a substantial gap in the obtainable heights. In one embodiment, the support pedestal can include a base member, a support member and a coupling member operatively connecting the base member and the support member. The coupling member can include first and second cylindrical walls, whereby an outer wall of the coupling member bears directly on an outer wall of the base member. Locking members can be utilized to operatively attach the coupling member to at least one of the base member or the support member. The locking members can function to increase the structural stability of support pedestal.

Abstract: A mine support yieldable prop includes a threaded shaft rotatably mounted in an end of the prop to move into and out of the prop end to move a bearing plate toward or away from a mine roof, and/or a bearing plate pivotally mounted to the end of the prop to level the prop with uneven mine roofs.

Abstract: A mine support yieldable prop includes a threaded shaft rotatably mounted in an end of the prop to move into and out of the prop end to move a bearing plate toward or away from a mine roof, and/or a bearing plate pivotally mounted to the end of the prop to level the prop with uneven mine roofs.

Abstract: A post adjustable in length as required. The post can be adjusted at any time during and after construction. The post can be used as an extension of a column which requires adjustment in length. The post can be used as a jack. The post is capable of withstanding compression, tension, and dynamic loading. The post can be used to provide support to beams and girders in a house frame.

Abstract: A mine rib support for bracing a vertical mine rib disposed between a mine floor and a mine roof. The support includes an elongated upright and continuous telescopically expandable support having a preset curvature. The member is longitudinally expanded for engaging the mine floor and the mine roof under compression with the curvature facing towards the mine rib. A support plate is laterally extended from the support member into compression engagement with the mine rib, thereby prestressing the support for support of the mine rib.

Abstract: A longwall mining system includes at least one face end roof support having a longitudinal length, and at least one near end roof support adjacent the face end roof support. The near end roof support has a longitudinal length substantially shorter than the face end roof support longitudinal length. There is also at least one face roof support adjacent the near end roof support, and the face roof support has a longitudinal length substantially shorter than the near end roof support longitudinal length. There is also a forward conveyor extending forward to and attached to the face end roof support, the at least one near end roof support, and the at least one face roof support, and a rearward conveyor extending rearward of and attached to the face end roof support, the at least one near end roof support, and the at least one face roof support.

Abstract: A module is for use in drilling a borehole in a face of a mine passage using a drilling element and installing a bolt in the borehole once formed. The module may include a bolt holder for holding a plurality of bolts and a drilling element holder for holding a plurality of different drilling elements. A manipulator moves along an arcuate path between the bolt and drilling element holders to deliver the respective components to a drill head positioned along the arcuate path. The drill head may also slide relative to the mast in two different directions, and includes a drill guide for determining the location of the face to be worked. Related aspects of control of the module and methods are disclosed.

Abstract: A suspending hydraulic pillar includes an oil cylinder, a movable prop, a handle-valve body, a reset spring, a top cover, a bottom seat, a three-way valve, a position-limiting steel wire, and a guide ring. The handle-valve body is provided between a port of the oil cylinder port and the moveable prop. Position-limiting steel wire, a guiding ring, and an oil inlet is located on a lower part of the moveable prop. The three-way valve is provided in the handle-valve body. A dust-prevention ring and a sealing ring are provided between the handle-valve body, the movable prop, and the oil cylinder. The handle-valve body is fixed on the oil cylinder by means of a connecting steel wire. The handle-valve body does not move up and down as the movable prop telescopically extends or contracts. The suspending hydraulic has good stability, high strength and supporting force, good sealing, and high anti-erosive capability.

Abstract: A hydraulic prop 1 is provided for use in underground mining and tunnel construction and is to be used above all in the shield support. In this shield support or in the hydraulic prop 1, the exterior pipe 15 having the foot connection part 16 and the handle 17 and the interior pipe 19 having the head plate 20 are effectively connected together via spring steel wire ties 35 which are disposed or are to be disposed in corresponding connecting grooves 36, 37, 38 or 39, 40, 41 such that in the transition region 42 sufficiently high forces can be transferred so as to ensure a connection between the components which is effective and remains effective. A setting pressure of 600 t can be realised at about 700 bar with the corresponding equipment, wherein in an advantageous manner this particular connecting technique permits the use of high-strength pipes which results in considerably thinner-walled pipes.

Abstract: A module and related methods of use in drilling a borehole in a face of a mine passage using a drilling element and installing a bolt in the borehole once formed. The module may include a bolt holder for holding a plurality of bolts and a drilling element holder for holding a plurality of different drilling elements. A manipulator moves along an arcuate path between the bolt and drilling element holders to deliver the respective components to a drill head positioned along the arcuate path. The drill head may also slide relative to the mast in two different directions, and includes a drill guide for determining the location of the face to be worked.

Abstract: A suspending hydraulic pillar includes an oil cylinder, a movable prop, a handle-valve body, a reset spring, a top cover, a bottom seat, a three-way valve, a position-limiting steel wire, and a guide ring. The handle-valve body is provided between a port of the oil cylinder port and the moveable prop. Position-limiting steel wire, a guiding ring, and an oil inlet is located on a lower part of the moveable prop. The three-way valve is provided in the handle-valve body. A dust-prevention ring and a sealing ring are provided between the handle-valve body, the mvoable prop, and the oil cylinder. The handle-valve body is fixed on the oil cylinder by means of a connecting steel wire. The handle-valve body does not move up and down as the movable prop telescopically extends or contracts. The suspending hydraulic has good stability, high strength and supporting force, good sealing, and high anti-erosive capability.

Abstract: A hydraulic support for underground mining and tunnel construction includes an outer tube to form an upper prop and an inner tube which forms a lower prop and is received in the outer tube to define a pressure chamber. A footpiece is secured to a lower end of the inner tube. Provided on the upper end of the inner tube is a piston which is sealingly guided along the outer tube as pressure fluid is admitted into the upper prop. Disposed inside the lower prop at a location below the piston is a valve block for introducing pressure fluid into the pressure chamber, with a pressure tube connecting the valve block with the piston to thereby define a constant distance of the valve block to the footpiece.

Abstract: Methods for pillar recovery in chamber-and-pillar working materials in underground stratified beds are disclosed. Additionally, tubbing units for pillar recovery in chamber-and-pillar working of materials in underground stratified beds are disclosed. An extraction device is aligned obliquely to pillar galleries located between the pillars and the roof is supported in front of the retreat face of the extraction device with a plurality of tubbing units, each tubbing unit being adjustable in height and width and movable through operation of a vehicle. The tubbing units may be moved through other tubbing units that are set, and reset in another position.

Abstract: The present invention is directed to a yieldable prop to resist a sagging roof or thrusting floor. The invention is directed to a support apparatus disposed between the floor and the roof. The apparatus comprises a load-bearing member having a length with an axis along the length and having repeating surface undulations along at least a portion of its length. The load-bearing member is capable of moving in the direction of its axis. The apparatus also comprises a resistance member positioned adjacent a portion of length of the load-bearing member. The resistance member resists movement of the load-bearing member by incrementally deforming the undulations on the surface of the load-bearing member adjacent the resistance member as the load-bearing member moves axially.

Abstract: A support device (8) for a rib (14) between a floor (18) and a roof (16). The device includes an expansion means (10) and a pair of resilient members (12a, 12b). Each of the resilient members (12a, 12b) have a proximal end (27a, 27b) adapted for connection to the expansion mean (10) and a distal end (28a, 28b) curved away from the expansion means (10) and adapted for engagement with the floor (18) and roof (16) respectively. When the device (8) is positioned towards or against the rib (16) and the expansion means (10) is activated to drive the members (12a, 12b) apart, the member's distal ends (28a, 28b) are driven substantially vertically into engagement with the floor (18) and the roof (16) and a portion of the device (8) is driven substantially laterally (32) into abutment against the rib (14).

Abstract: A jack includes a base, a guide extending from the base, and an extensible member having an extensible fit with the guide and extending from the guide to have a free end. A support is located at the free end of the extensible member. An actuator is capable of extending the extensible member. The guide and extensible member have portions which are laterally offset with respect to the base and the support such that when the support is in pressure engagement with a panel, the laterally offset portions are disposed adjacent one side of the panel to leave an area between opposite sides of the panel substantially unobstructed.

Abstract: A roof support for an underground mine which has a hydraulic cylinder positioned between a roof engaging support and a ground engaging base and has a flexible gas barrier or enclosure surrounding surfaces of said hydraulic cylinder which are subject to corrosion by gases present in the underground mine. Continuous flowing non-corrosive gas such as nitrogen is supplied to a space between the gas barrier and the hydraulic cylinder for preventing corrosion of cylinder surfaces by corrosive gases present in the mine which may include hydrogen sulfide.

Abstract: Joining connections are presented for joining the functional parts of hydraulic or pneumatic operating devices the joining connections including a first part exhibiting an external wall section and a second part exhibiting an internal wall section, which are joined together with mutually overlapping wall sections having depressions that form a cavity, in the connected state that is filled with a fluid casting compound of plastic that connects the two parts together by means of a positive form fit after hardening to prevent relative displacements between the two functional parts and to seal the separating gap clearance between the wall sections of the two functional parts.

Abstract: A prop head bearing between the roof bar and the prop (4) of a shield-type support frame, comprising a ball-joint socket (3) on the roof bar and open towards the prop for receiving a ball-joint head (2) on the prop (4), with at least one movable securing element (6, 7) which, when in a secured position, engages in a recess (12, 13) in the joint head (2) to prevent accidental lifting of the joint head (2) out of the socket (3), and with a bolt which locks the securing element (6, 7) in the secured position, in which that the securing element is in the form of a securing pin (6, 7) movable along its longitudinal axis between the secured position and an assembly position, wherein the securing pin (6, 7) is lockable by the bolt (14, 19) in the assembly position, in which it does not engage in the recess (12, 13) in the joint head (2).

Abstract: A shoring device that utilizes an accessory assembly mounted to a vertical tubular member of a tubular scaffold assembly to receive a shoring member therethrough. With an adjustable threaded ring mounted over the threaded portion of said accessory assembly, a supporting surface or edge is provided to a locking pin that passes through cooperating slots in the accessory assembly and radial through holes in the shoring post member to keep the post member and the accessory assembly at a fixed position with respect to each other. The lower most end of the threaded portion comes in abutting contact with the upper end of the scaffold vertical member thus transmitting the bearing load therethrough. A user can selectively adjust the effective length of the scaffold and shoring assemblies by rotating the ring assembly.

Abstract: A lift cylinder arrangement is disclosed for a hydraulic support frame for underground mining. The support frame has a lift cylinder for lifting the base shoes during advancing, which is supported on the one hand on a return rod and on the other hand, in a pivoting manner, with an end supporting head to a drawbar connected to the base shoes. In order to allow a simple, rapid and reliable connection between the supporting head and the drawbar, the supporting head is connected to the drawbar by a plug-type locking system comprising two plug-type locking elements, which include first locking notches on the drawbar, and arranged complementarily thereto second locking notches on the supporting head, whereby the plug-type locking elements engage in at least one of the locking notches with clearance.

Abstract: A mine prop is comprised of an elongate tube having a slenderness ratio that would generally allow buckling or kneeling of the elongate tube when exposed to a sufficient axial force. A plurality of elongate support members having a length less than the elongate tube are attached to the tube to prevent buckling or kneeling of the elongate tube along the portion of the tube to which the elongate support members are attached. The portions of the tube that are unsupported by the elongate support members define one or more yieldable zones proximate at least one end of the tube. A compressible filler material is disposed within at least portion of the tube to support yielding in the yieldable zone.

Abstract: Corrosion resistance is provided for a power cylinder by providing a preloaded molded urethane elastomer sleeve liner within an outer cylinder of material such as a copper/nickel alloy which is subject to corrosion from long-term exposure to ambient fluids such as sea water. Preloading is preferably provided by thermal shrink fitting of the molded urethane sleeve liner to the inner bore of an outer metal cylinder. Preloading of a structure which has high structural integrity and low permeability thus effectively prevents incursion of fluids and gases at the interface between the outer cylinder and the sleeve liner as well as providing a surface which can be machined to a high degree of smoothness and against which reciprocating piston seals and wear assemblies can directly ride and which is resistant to abrasion therefrom even at high piston speeds.

Abstract: A mine roof support designed to extend vertically in a mine passageway. The support includes a containment structure having at least two telescoping containment members freely telescopically movable relative to one another, and a filler material introducible into the containment structure to form a column of material extending vertically in the passageway. Each containment member defines an interior space for receiving the filler material. The material is hardenable inside the containment structure to form a yieldable column whereby in the event of a mine convergence, the yieldable material yields while providing continued support and the telescoping containment members move freely relative to one another to permit such yielding without damage to the containment structure. A method of installing such a roof support is also disclosed.

Abstract: To temporarily secure pit and tunnel construction a prop device 1 is intended which consists of an inner pipe 2 and an out pipe 3 which can be moved while inserted in each other. The pulling apart motion is initiated when a liquid is filled into a filler opening 11 into the outer pipe 3 whose cavity 9, 2 is separated form the cavity 9 by a plate 10. This plate 10 features a weak point 18. Endangerment of the workers is therefore eliminated. After the extension of the inner pipe 2 from the outer pipe 3 the partial wedges 40, 41, 42 are pushed into the remaining narrow gap 45 so that the desired locking effect takes immediately place. The water or liquid can exit again from the cavity 9, 2 via the filler opening 11. A very light prop device 1 that absorbs sufficient straining forces has been created.

Abstract: A ventilation overcast comprises a frame member that defines a structure having a substantially inverted U-shape with first and second opposed side wall portions and a roof portion. A curtain member having a plurality of longitudinal corrugations therein is positioned adjacent the frame member so that a bottom portion of the curtain member contacts the floor of the mine. The longitudinal corrugations allow the curtain member to be crushed when subjected to floor heave.

Abstract: A shoring leg is provided with a latch for use in maintaining an end plate of the shoring leg and a jack collar in a predetermined position relative to each another. The latch comprises a latch member having a slot to receive a mounting bracket which mounts the latch member for pivotal movement relative to the mounting means from a latching position to a release position. The latch member defines a recess adapted, when in the latching position, to receive part of the leg end plate and a corresponding part of an adjacent collar of the jack to retain the end plate and collar in the predetermined position. The latch member is biased into the latching position by a coil spring acting between the leg and the latching member.

Abstract: A ventilation overcast may comprise a plurality of support columns, each of which has an upper end and a lower end. A plurality of cross beams are connected between the upper ends of each of the plurality of support columns so that the support columns and cross beams define a generally rectangular structure having two opposed side wall portions and a roof portion. A curtain member having a plurality of longitudinal corrugations therein is positioned between the lower ends of adjacent support columns located on the same side wall portion of the ventilation overcast so that a bottom portion of the curtain member contacts the floor of the mine. The longitudinal corrugations allow the curtain member to be crushed when subjected to floor heave.

Abstract: There is a support for underground mining and tunnel construction, comprising an outer tube and an inner tube, which can be pushed into each other in a telescoping manner. A piston acted upon by a hydraulic pressure medium is located in the outer tube. This piston, when acted upon by pressure, acts on the inner tube to cause an extension. The outer tube and the inner tube can be fixed on each other by means of a mechanical locking device.

Abstract: A pit prop has two opposed ends and comprises two bearing plates located at the ends, two telescopically displaceable prop elements, a number of separate resiliently compressible rubber discs arranged adjacent each other and a tubular indicating element. The prop includes a further bearing plate with the discs being located between two bearing plates to permit yielding of the pit prop under a load. The indicating element has markings thereon to indicate the load condition of the prop. The prop includes a locking device for releasably locking the prop elements with respect to each other.

Abstract: An advancing support frame is connected to the face conveyor (9) via an advancing rod (7) engaging with the advancing cylinder (5). A lifting cylinder (10) is supported on the advancing rod (7), with which the base shoes (1) are lifted during the advancing process. The lifting cylinder (10) is guided so as to be able to move in height in longitudinal guides (15) on the inner sides of the base shoes (1). A U-shaped tension stirrup (18), whose shanks (19) directed towards the ground have elongated holes (20), is supported centrally by the lifting cylinder (10) and joined to the base shoes (1) via carrying bolts (21) fastened to them.

Abstract: A device for releasing of a frozen screw pressed against a contact surface uses a compression disc pre-loaded to an anticipated amount of deflection prior to mounting between the contact surface and the screw. The disc has an insert formed from a granulated material mixed with a water soluble binder, allowing to wash out the insert and cause collapse of the disc, so as to break the connection between the contact surface and the screw.

Abstract: An extending prop for underground and tunnel construction, comprising, an outer tube having a closed bottom end, an inner tube telescopically slidable in the outer tube and having a closed top end, and a mechanical locking device adapted to fix the relative positions of the inner and outer tubes. A hydraulically actuated flying piston is arranged in the outer tube and is separated from the inner tube. The piston is adapted to extend the inner tube upon actuation by hydraulic pressure. The piston divides the prop into a bottom chamber enclosed by the outer tube and a top chamber enclosed by the inner tube. A first filling connection is arranged on the outer tube for filling the bottom chamber with a pressure medium for actuating the piston. A second filling connection is arranged on the inner tube for filling the top chamber. The prop is fillable with construction material through the second filling connection over its entire length by displacement of the piston toward the bottom end of the the outer tube.