GB1597804A

GB1597804A - Process and apparatus for supporting underground cavities

Info

Publication number: GB1597804A
Application number: GB19200/78A
Authority: GB
Original assignee: Magyar Szenbanyaszati Troszt
Current assignee: Magyar Szenbanyaszati Troszt
Priority date: 1977-05-17
Filing date: 1978-05-12
Publication date: 1981-09-09
Also published as: DE2821561A1; ATA353478A; NL7805304A; SE8303498D0; DE2821561C2; NO781690L; JPS549103A; FR2391353A1; ES469923A1; CA1112884A; FR2391353B1; AT374248B; SE8303498L; IT7823518A0; IT1158716B

Description

PATENT SPECIFICATION ( 11) 1 597 804

4 ( 21) Application No 19200/78 ( 22) Filed 12 May 1978 ( 31) Convention Application NoMA 2875 ( 19) 9 ( 32) Filed 17 May 1977 in I > ( 33) Hungary (HU) Uo >( 44) Complete Specification published 9 Sept 1981

4 M ( 51) INT CL 3 E 21 l D 11/00 ( 52) Index at acceptance EIF 43 A 43 B ( 54) PROCESS AND APPARATUS FOR SUPPORTING UNDERGROUND CAVITIES ( 71) We, MAGYAR SZENBANYASZATI TROSZT, a body corporate organised under the laws of Hungary, of Tatab Anya, Hungary, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following 5 statement:-

Background of the Invention

Field of the Invention

The invention concerns a process and apparatus for the complex support of mainly underground cavities such as mine roads or drifts, tunnels, liquid reservoirs and industrial halls 10 Description of the Prior Art

The most important disadvantages of known and generally used cavity support systems are as follows:

( 1) As a consequence of the manner of installing temporary and permanent support devices (TH rings, props, shafts etc) the full contact between the rock and 15 the support is formed at the point in time determined by the rheological properties of the surrounding rock and generally after a significant rock deformation As a consequence:even before the support is loaded a rock deterioration process starts up which results in a considerable narrowing of the sections and requires a 20 maintenance activity of significant cost This circumstance causes the support to have a short life, and the load of the support which changes with time is distributed in a random manner and cannot be planned deliberately, consequently at certain locations of the support stress peaks may be formed which result in damage or destruction not only of the rock 25 but also of the support, the hitherto known support mounting and installing technologies and methods cannot take into account in a precalculable manner that the support device actively reacts on the surrounding rock and this reaction effect may on the one hand start an irreversible destructive process but may also 30 provide for balance or equilibrium while providing a favourable rock support Attempts are known to classify rock strata into different categories or classes on the basis of greater or lesser idealisation of their actual behaviour The strength characteristics of the support have been associated with these idealised characteristics (e g Rabcewicz-Sattler: 35 Die neue Osterreichische Tunnelbauweise, Bauingenieur 1965, No 8).

Naturally this idealisation does not allow the most recent researches into the mechanics of rock to be carried into practice and has hindered the spread of recent technology Consequently, it is no coincidence that e g.

the cited method has only remained in the field of tunnel construction 40

The destruction process can be prevented by the closed loop regulating system resulting from the invention wherein the support co-operates with the surrounding rock to adjust the load distribution level between the rock and the support which can be supported by each of them without destruction or without deformations which exceed permitted magnitudes 45 ( 2) Generally conventional solutions cannot modify the value of the rock pressure within wide limits, rather in their case the pressure of the surrounding rock arises as an in situ natural characteristic, and thus in most cases load level arise which virtually necessitate destruction of the support and thus make it mandatory periodically to carry out re-supporting works 5 ( 3) Generally the conventional solutions only provide specialised constructions relating solely to the support, and do not provide a modular process and apparatus, with regard to the complex system of cavity formation and support, which is utilisable with the most widely varied cavity forming (winning) methods regardless of the geometric configuration such as dimension and shape of the cavity 10 and regardless of the associated widely varying transport or rock removal systems, forming an integral part with such systems and methods.

Summary of the Present Invention

It is an important aspect of the invention that the changes that take place in the course of forming the cavity are interpreted according to the results of the 15 latest rheological researches as they relate to the combined system of the rock and the support apparatus, the parameters are determined within the framework of a complex system involving all the characteristics of the surrounding rock and their change with time, and the processes and apparatus are co-ordinated to these parameters accordingly The technological steps determined by the invention are 20 thus time-dependent functions, the relative use of which are interpreted on the basis of rheological changes of the rock and the support.

From this it follows that a further essential feature of the invention is the scientific discovery that in the formation and support of underground cavities, the emphasis is not on defense against nature by taking up the pressure of the rock with 25 a support apparatus, but rather through a good knowledge of the laws of nature affecting the apparatus; the effects of natural phenomena are utilised which represents an advance from the phase of defense to the phase of deliberate regulation Thus the invention is a system of practical deductions inferrable from new theories concerning the mechanics of rocks wherein the planning, 30 dimensioning and technological formation of the support and supporting devices as well as the installations thereof are all incorporated.

The support of cavities made by various technological processes is a complex task In the course of solving this task one must have regard to a complexly interrelated system of conditions of which the principal element groups are the 35 following:the stress conditions around the cavity; the physical and mechanical characteristics of the surrounding of the rock; the manner, the apparatus and the technology of forming the cavity; the geometry (dimensions, shape) of the underground cavity; 40 the characteristics of the support.

The apparatus elements determined purely by way of example and described below as a technological system may naturally be substituted or replaced by technical elements of similar function but the essence of the invention is their coordination into a unitary system 45 In accordance with the foregoing the rock formation and the supporting apparatus form a collaborating double system wherein a suitably constructed support apparatus and the excess pressure caused by opening the cavity, the socalled transferred pressure, are divided between the rock and the support in such a way that both can accommodate the excess pressure without damage or 50 destruction.

This recognition has led to a re-evaluation of the task of supporting devices and to the development of support systems and installation technologies suited to these new circumstances Accordingly, the most basic requirements of the support system are the following: 55 a) Activity by which is meant the property of the support system by means of which immediately on installation it takes part in load balancing, does not allow for the whole of the excess pressure to be exerted on the rock and thus prevents the commencement of damaging or destructive processes which could lead to rock 60 falls and the loss of the controllability of the mechanical phenomena.

1,597,804 3 1,597,804 3 b) Yieldability which is the property destined to realise the automatic control of the dual rock-support system The support apparatus installed at the time of the cavity opening is in contact with the rock and takes part in the bearing of excess pressures or stresses The transfer of load from the rock to the support apparatus takes place 5 with certain attendant deformations Since all rock-mechanical process is rheological, this transfer of stress to the support apparatus takes place continuously with time at a rate dependent upon certain rock constants and characteristics of the support The yieldability of the support is destined to fulfil the regulating function of undergoing a permitted small deformation or yield whenever the load on the 10 supporting apparatus reaches a non-permitted or undesired value, whereby to avoid a destructive load This process continues until an equilibrium is reached wherein both the support and the rock carry a load supportable without damaging consequences.

c) Load-bearing capacity 15 represents the totality of the mechanical or strength characteristics of the supporting apparatus Without suitable load bearing capacity, the equilibrium state could only be reached after complete closure of the cavity and the destruction of the cavity and its surroundings.

The requirements of the support are fully met by A) a steel supporting apparatus employing tensioning (feeding in of pressure), 20 and/or B) shaft support with shot or sprayed concrete possessing adequate resilience and rigidity characteristics.

Relating to A: 25 In the case of using steel support the essence of the process is the tensioning of the arcs or arches installed in the excavated cross-sectional areas by means of a predetermined force or pressure with the aid of hydraulic forepoling and tensioning apparatus By tensioning the support with a pressure P the transferred pressure is decreased from (Pp -PO) L compared with the original value P L wherein Ppr 30 represents the primary main pressure normal to the plane of the 'cavity under examination and L is the relevant dimension of the cavity in that plane In what follows, the correlations are set out on the basis of which:the pretensioning of the support in the case of a mine road or drift of long life ( 1),; 3 the pretensioning of the support in the case of cavities of planned lifetime ( 2); the pretensioning of the support according to the mechanical condition of the surrounding rock in the case of the most favourable cavity configuration ( 3); the determination of the installation length or the distance of the support ( 4).

( 1) The pretensioning of the support takes place in the case of long life cavities (exceeding 15-20 years) takes place 40 with a pressure P:

Ubizt 2 An wherein:

{ is the factor dependent on the role of the cavity, 45 Ppr is a primary main stress prevailing at the location of the opening of the cavity, b izt is the standard load permitted for the support, mfeg n is a safety factor, A is a computed mechanical constant dependent on the configuration and 50 dimensions of the support apparatus, a is the value of the co-efficient of co-operation of the rock and the support which is expressed by the multi-variant function a=f(Eb, mb, L, Kb, G) wherein Eb is the elastic modulus of the support, 55 mb is the Poisson number of the support, L is the main dimension of the support (span length) Kb is the standard cross-sectional factor of the suppport, G is the elastic modulus of the rock jacket.

( 2) Prestressing of the support in the case of a planned life of to:

bizt Po= (Por ameg ( 2) 2 a An(l-e-Bto) wherein:

e is 2 71 the base number of exponential logarithm, 5 to is the planned life of the cavity, p is the co-operation factor in time of the rock and the support which can be calculated on the basis of the rheological constants of the rock and the support as well as the dimension of the construction:

B=f(Et, mb, L, Kb, G, r, p) 10 where T is the relaxation factor of the rock, i? is the viscosity factor of the rock, i e its creep modulus, g is a factor dependent on the function of the cavity, P Pr is the primary principal stress prevailing at the location of opening of the 15 cavity, abizt is the standard load permitted for the support, n is a safety factor, A is a mechanical constant which is computed and which depends on the shape and dimensions of the support, 20 a is the co-operation coefficient of the rock and the support, (the symbols not listed have the same significance as above).

( 3) In the case where the most favourable shape or configuration of the cavity from the point of view of the mechanical condition of the rock cannot be formed, because of the role the cavity is destined to play, and by most favourable is meant 25 from the point of view of the load distribution of the rock and the support, then the prestressing of the support to be installed in the cavity section of given geometry must be such that it approximates the stress condition corresponding to the optimum The pressure transmitted on a vice which makes an angle O with the primary main stress direction in the clockwise direction is given by: 30 P.

PO= lk+(k-2)cos 2 (pl ( 3) 2 (k-1) where PO is the pressure value computed from formula (I) or ( 2) and k is the quasiPoisson number valid for the location of the opening of the cavity.

( 4) The installation distance or spacing of the support 35 Let 1 be the installation distance of the support in the case of an unprestressed support apparatus If the prestressing is of the value PO then the installation distance can be increased by a factor of A, i e l O= 11 where 2 |Ppr Ppr Po Where:

g is a factor dependent on the function of the cavity, Ppr is the magnitude of the primary main stress, PO is the value of the pre-stressing which can be computed from formula (I) or ( 2).

For certain parts or components of the invention earlier attempts are known, 45 such as for instance patent specification No 1,143,468 of the German Federal

Republic relating to the clamping in of the support where the significance of the prestressing of the support has already been recognised However, the known 1,597,804 1,597,804 5 processes are not sufficiently efficient because they did not take into account those mechanical processes taking place with time wherein the knowingly controlled and dimensioned functions of the rock environment and the support are determined.

This means that in a primary field characterisable with a quasi-Poisson number of e g k= 2 or a figure close thereto, the lateral support clamping in the case of a 5 driven road can cause the start of a process of rock destruction which only ceases when the cavity is closed.

The present invention bases itself on the modern theory of the mechanics of rocks and on the basis of provably successful experiments and in the knowledge of the characteristics of the primary stress field and the rock provides the possibility 10 with the aid of computers of employing the best technology for maintaining control of mechanical processes which change with time.

Regarding B Continuous shaft support (shell support) of adequate resilience and strength properties The defect of traditional shaft support is the lack of cooperation 15 between the shaft and the rock or its insufficient nature and in the case of the usual shaft thicknesses of v 1 d 8 but the main fault is rigidity or stiffness These defects can be reduced in a known manner partially be filling up the back space, i e the gap between the rock mantle 20 and the support, and partly by utilisation of yielding inserts The conventional material such as slag is manually filled into the back cavity but this is an imperfect method Although in given cases the injection of sand or foam can provide superior filling and a better effect, the overall effect is still not satisfactory The fundamental defect of filling the back space behind the shaft or wall is that this can only be 25 effected after the event and the effect of co-operation arises only belatedly, in other words only after a partial or complete destruction of the rock taking place in its absence One can accordingly appreciate the importance of increasing the density of the support points of the mantle of the cavity.

The above described defects are completely eliminated by the shaft support 30 process based on the principles of the new rock mechanics and involving continuously shot or sprayed and dimensioned shaft or wall support The thickness of the shot or sprayed concrete layer is a predetermined fraction of the cavity dimensions but is of significantly smaller magnitude and therefore can be regarded as a shell construction The small layer thickness and the perfect fit to the rock 35 result in such a support being of predetermined deformability (resilience) which perfectly co-operates with the rock from the commencement of installation.

The new principles of the mechanics of the rock clarify and unambiguously fix the behaviour of the environment of the cavity and on that basis determine the change in time of the load on the applied concrete shell, i e its increase; the 40 hardening or setting process of the shot concrete can be controlled in a programmed manner accordingly with the deliberate determination of the concrete properties.

The dimensional correlations described below ensure the optimum coordination of the two processes and the formation of the most favourable 45 construction as well as the maintenance at a predetermined value of the proportioned of load bearing as between the rock and the support apparatus.

The function of the cavity support construction realised by means of a shot concrete technology can be characterised in that it is a shell construction, it matches or fits the rock perfectly, it has suitable statical or rigidity properties, 50 satisfies all demands made on the supporting apparatus such as activity, yieldability and load-bearing capacity A further advantage of it is that it can be employed with any cavity forming technology and is readily mechanisable, which will be referred to again below.

The wall thickness of the shot concrete wall or shaft 55 in the case of long life, greater than 20 years, can be determined as follows:two factors can determine the wall thickness of the shot concrete wall or shaft:

a) the load on the rock should not set off a destructive process at the circumferential points of the cavity, i e the reduced standard stress arising in the rock mantle should at no time exceed the permitted: 60 U 4 rock < arock reduced = permitted i.e the value v, can be determined from the relation:

Urock permitted 2 (g Ppr-Po)Alo( I-a)ni where:

c a=a( v,) b) the main or standard load of the support should remain below that which is 5 permitted:

o Support < Urock reduced = permitted i.e the thickness v 2 of the support can be calculated from the equation:

sup port aperm itted 2 (g Ppr-Po)A Io(R v 2)a em itted 10 n 2 The wall thickness of the support should be taken as being equal to the greater of v 1 and v 2, i e:

v=Max{v 1; v 2} The symbols have the following meanings:

l is the factor dependent upon the role of the cavity, 15 P Pr is the primary stress prevailing at the location of opening of the cavity, Po is the prestressing pressure of the support, A is a computed constant dependent on the shape and size of the opening of the cavity, Lo is a factor dependent upon the installation distance of the support, 20 ca is a function or co-operation coefficient of the rock and the support which is a function of the material constants of the rock and the support, the geometrical dimensions of the cavity and the wall thickness of the support, is a function of the dimensions and geometry of the support, and n, N 2 are 25 safety factors.

In the case of a support of shot concrete of circular section with radius R and thickness v:

A= 1 Eb( 2 Rv-v 2) 30 <X-3 Ebm,( 2 Rv-v 2)+ 2 G(mb+)l(mb-I)R 2-2 mb Rv+mbv 2 l R 2 0 =2 Rv-v 2 where Eb is the elastic modulus of the support G is the elastic sliding modulus of the rock mb is the Poisson number of the support 35 The wall-thickness of the shot concrete planned for a life of to V 1 is determined from the equation:

rock permitted 2 (g Pp, Po)A Iol 1-a V, (l-e-go)l n, V 2 is determined from the equation:

support permitted 40 2 ({Ppr-Po)Alofa V 2 ( 1-e-o)n 2 1,597,804 /3 is a co-operation factor in time of the rock and the support which in the case of a circular road of radius R and thickness v is:

Ebmb( 2 Rv-v 2)+ 2 G(mb+ 1)l(mb-I)R 2-2 mb Rv+mbv 2 l TE b M( 2 Rv-v 2)+ 21 i(mb+ l)l(mb-1)R 2-2 mb Rv+mbv 2 l where r is the relaxation constant of the rock 5 i? is the creep factor of the rock.

In order to form the shot concrete wall or shaft, one requires a machine line which can produce the supporting apparatus which can optimally adjust itself to the terrain in question and can solve the transport to the site of the additives, the correct dimensioning of the concrete, the function of a perfectly homogenised and 10 mixture activating mixer and which can apply the homogenised concrete composition of which is in accordance with the prescription to the surface in a suitable manner.

The support construction can be realised with clamped in steel supports which are independent or with such supports stabilised with reinforced concrete and with 15 reinforced concrete construction Where a concrete or reinforced concrete is combined with the clamped steel supports account must be taken of the hardening process of the concrete.

As is well known the development of the rock pressure is also a time dependent process The above described dimensioning process makes it possible 20 optimally to co-ordinate the two processes and thus to form the mechanism in the most advantageous way This decides the material of the construction, the time and manner of the installation.

The installation of the concrete of the construction takes place by way of example with a shot concrete technology and fulfils two functions: 25 a) the ground work or contact function is a concrete which continuously contacts the surface of the rock where it causes an excess stress to prevent loosening of the rock while at the same time forming a transitional layer; b) a load bearing concrete shell which is expediently of monolithic reinforced concrete and which takes up the role of load-bearer in the course of the above 30 described mechanical co-operation.

The new interpretation of the per se known contact layer is that account is deliberately taken of the characteristics of the material (the rheological characteristics of the rock, its breaking strength, changes with time, moisture content) and thus serves as a transitional layer formed on the rock surface after 35 breakage which penetrates into the fissures and aligns itself with the load-bearing walls or shafts Thus in comparison with the known principles, the effecting of the clamping process is given a new content.

For example, the apparatus according to patent specification No 1,193,904 of the German Federal Republic is not suitable for the stressing or clamping of 40 controllable loads in the vertical and horizontal directions or to mount supports of balanced moment and the co-operation with the forepoling is not achieved.

The situation is the same with patent specification No 1,408,727 of the

German Federal Republic The favourable co-operation of the ring of the rock requires a tensioning apparatus which can transfer not only circumferential but 45 also radial loads in a regulable manner and at a controllable location (favourable contact), because of its construction.

For this reason, the disclosures of patent specification No 2,326,686 and

1,283,778 of the German Federal Republic are less effective because they are s O suitable only to exert tangential loads 50 The task is only partially solved by clamping or mounting devices of the polygonal type (as is known from patent specification No 1,193,457 of the German

Federal Republic and Hungarian patent specification No 162,676) and the latter demonstrates that active support can be effective if it is exerted on shield surfaces thus foreshadowing the construction of an active shield for drifting with 55 mechanised winning.

The last solution is fully equivalent as regards the mechanics of the rock, with the present invention but its field of application and its embodiments are different.

The construction according to Utility Model No GB 1461 of the German Federal Republic partially solves the above-mentioned disadvantages but its use is 60 limited to specially constructed roof arch supports and is not suitable for exerting large clamping forces.

1,597,804 The forepoling mentioned in our process constituting one phase of the technology may in principle be carried out with any of a number of known forepoling devices but the effectiveness of the work is the greater the better the forepoling the arch mounting and the clamping phases are co-ordinated The possibility of this co-operation of the phases is considerably limited with the 5 solutions of e g patent specification Nos 2,360,726 and 2,252,450 of the German

Federal Republic Other solutions, such as that in patent specification No.

1,080,948 of the German Federal Republic involving crabs cannot exert adequate forepoling forces and thus does not enable the joint mounting of the lining or lagging and the arch This same disadvantage prevails also with the constructions of 10 patent specification Nos 2,253,670 and 1,180,704 of the German Federal Republic.

Other known solutions are limited to solving a given partial task only e g.

supporting the face, or e g the so-called Moll arches (see patent specification No.

1,193,911 of the German Federal Republic).

The aim of the force-introducing mechanism 15 is to change the stress condition of the rock jacket defining the section of the cavity through the supporting element by means of forces of chosen direction and magnitude.

In the sense of the invention the essence of the solution is as follows:

1) The mechanism performs its operations expediently by combination with 20 the working phases of the forepoling device or apparatus, being effected by a displacement of the wire ropeway formed on the forepoling apparatus and is connected in this way to pretensioned (i e forepoled) upper prop, so that the position and stress condition of the latter no longer changes.

2) The advantageous exploitation of the available space: it consists of a 25 clamping mechanism involving internal hydraulics to which temporary supports are connected by way of articulated suspending mechanism wherein the temporary supports are constituted by elements which are effective in the direction of the sis and floor and in dependence on the shape of the cavity section are exchangeable, the upper transition being constituted by suitably formed 30 projections of the forepoling device itself.

3) A divided force introducing support system which is divided by the spacing elements into an external and an internal support arch; both supports can be clamped by themselves but not necessarily with the same direction and magnitude of force transmission 35 4) The mechanism described in 3) may also be constructed so that the outer support system is concreted in and during the hardening and setting time tension of the internal support arch provides the supplementary portion of the conserving reaction system and is dismantled from the set or hardened concrete.

5) A force introducing mechanism wherein the internal hydraulic clamping 40 mechanism and/or the temporary supports connected thereto contain a fixing or securing projection on to which the drilling machine for drilling the rock and anchoring the rock and the feed lafette can be suitably adjusted for rock bolting.

6) The performance of the fourth introducing process is carried out by partially simultaneous rock bolting and the anchoring takes place in the course of 45 the conservation of the mounting.

The mechanism of the clamping: it is a connection which allies itself in the prescribed manner to the cavity and is capable of introducing the forces.

1) The arch elements are mounted by radial devices using such forces as will ensure that the support element, e g a ring, should to some extent be deformed 50 into a cavity, and the points of attack of the forces are so determined that the bending stresses in the arch elements should be equalised or balanced to a suitably chosen value. 2) The mounting and clamping described in 1) is combined with tangential

stressing of the arches and this then becomes simultaneously one of the locations of 55 the conservation.

3) The conservation of the introduced stress condition takes place with such a force distribution that the load-bearing of the support element is optimal, the force distribution having a radial and tangential component and regarding the combined rock and support mechanism together is of an optimal value 60 4) The mounting of the support apparatus (e g ring) is such that a suitably dimensioned grid is mounted on the adjacent surfaces which grid is intersected by the supporting arches and has transverse elements (for roads, elements directed 1,597,804 along the axis of the road) whereby to transmit clamping forces so that the intermediate space is protected from fall and is pretensioned by pressure.

5) The mounting can also take place so that the force conservation remains partly in the concrete but partly takes place by way of an external element which S can be recovered after the concrete has set 5 Forepoling follows the steps of making the cavity and loading or is parallel with loading in the operational sequence of cavity formation (road building, tunnel building etc).

The task of forepoling is to prevent the covering rock from falling by producing such a stressed condition which is suitable for the disturbance free performance of 10 the transition to the clamping in of the final and permanent support element without loosening the rock.

1) In the forepoling process the roof support elements and the spatial supports (grid) are clamped in at the same time-must be done in such a way that when the final or permanent forces are introduced this situation does not have to change 15 2) Forepoling can also take place with paired support beams which are movable by way of a hydraulic mechanism via a lever so that during forepoling the beam is not only rocked from its lower position but also performs a forwardly advancing motion.

3) Another preferred embodiment of the forepoling apparatus is that which, in 20 order to ensure the horizontal and vertical bend of the cavity contains:an upper or transitional support wherein the forepoling main support is fitted t with the aid of displaceable guides, the upper part of the main support is divided into two parts by the over pivot or half-pivot; the rear portion can be adjusted in accordance with the radius 25 of curvature in the vertical sense of the cavity, in the so-called "loosening" part of the movement cycle of the working cylinder which performs the forepoling an element is actuated, e g a chain, which indexingly advances the forepoling apparatus.

The generation of the stresses and deformed condition as well as their 30 conservation produced by clamping with radial and tangential forces may also be combined with the per se known rock bolting Rock bolting is suitable for achieving force conservation by radial means The bedding of the rock bolting can be performed not only along tangential but also along axial elements such as the axial supports of the grid and this means that the stress condition created thereby 35 may be optimally chosen and maintained both in the plane of the ring and in the intermediate fields.

By having due regard to the main directions of the stresses and the magnitudes of the primary stresses, the disposition of the rock bolt can be such that optimal stress condition arises for the given cavity configuration 40 It is a condition of advantageously using the machine group required for carrying out the process according to the invention that:it should fit in well in the complex technological process of cavity formation, it should enable all further processes to be carried out undisturbed, it should provide the output required by the speed or velocity of the face, 45 it should ensure the multistage wall or shaft formation so that in given cases the installation of the required steel support (e g installation of ring) is carried out as an accompanying process with the provision of the contacting concrete and the load-bearing final wall or shaft with essentially the same main machines, 50 it should be suitable for walling a cavity driven in any desired direction such as road or inclined shaft.

The preparation of monolithic shafts or bricklinings can be grouped into two technological main groups:

1) The preparation and homogenisation of the material of the lining, 55 2) The installation of the lining.

The preparation of the material of the shaft or lining consists in the high efficiency mixing together of solid particulate materials, liquid materials and pulverulent materials and their binders in given unit packs or in doses which are determined by weighing before or after the process 60 Because of the given characteristics of the site the preparation of the composition requires optimally variable serving elements that can be put together in a modular manner Among the conditions for optimisation the available space 1,597,804 requirement and the transport paths provide absolute conditions while relative conditions are constituted by the-technical process of the road driving and cavity opening.

The application of the lining or wall is effected by a shooting machine operating on known principles, e g patent specification No 2,000,278 of the German Federal 5

Republic by means of a shooting or spraying head formed at the end of its hose.

The lining of larger sections cannot be carried out by the operator in a standing position The variously constructed and known moving platforms have been proved in external use and apparatus, but in underground working sites can only be used on very large sections In most practical cases the constructional dimensions of the 10 platform are such that they cannot be kept in operation juxtaposed with the machines carrying out the various technological processes and cannot therefore be fitted into the complex process of cavity formation, such as road driving.

An effective solution to this problem is signified by a manipulating apparatus with automatic position control which enables the operator to carry out in one 15 position the concreting of -one section while solving or fulfilling the conditions as regards quality and building technology The application or shot or sprayed concrete technology requires that the operator should sense or feel the forces exerted on the head to see its movement and the formation of the wall or lining It is better if the operator is disposed from the spraying head at a distance of a few 20 metres, in a quiet situation and while being in complete possession of the capacity for intervening directly and for sensing the physical parameters nevertheless should be able to form a perfect lining or wall in one fixed position while eliminating the need for downtime due to transforming or advancing the platform.

Brief Description of the Drawings 25

The accompanying purely schematic drawings illustrate a purely exemplary embodiment of the full technological machine line according to the invention, wherein:

Figure 1 is a "flow diagram" of the complete machine line, with the bottom portion continuing on from the top portion, 30 Figure 2 is a side view of the force applying mechanism, Figure 3 is an enlarged detail of Figure 2 but showing a variant, Figure 4 is a view taken along the line m-m in Figure 2, Figure 5 is a variant of the apparatus shown in Figure 2, adapted for a circular section, 35 Figure 6 is a partial view of the conserved state after application of force, Figure 7 is a side view of the forepoling mechanism in its clamped position, Figure 8 is a detentioned or collapsed position of the mechanism shown in Figure 7, Figure 9 is a section along the line n-n of the apparatus shown in Figure 8, 40 Figure 10 is a detail in side view of the mixing machine line, Figure 11 is a continuation of Figure 10, Figure 12 is a sectional view of the container for the concrete additive, Figure 13 is a longitudinal section of the mixer unit forming part of the mixing machine line shown in Figure 10, 45 Figure 14 is a plan view taken along the arrow F of the apparatus shown in Figure 13, Figure 15 is a side view of the manipulating device for the application of the shaft or lining, and Figure 16 is the sensing unit forming part of the manipulator of Figure 15 50 The machines required for achieving the process according to the invention are shown in schematic assembly in Figure 1 The support of the e g road is commenced by installing the main props la of steel arches 1 which is applied by the forepoling apparatus 200 in such a manner that the surface of the driven cavity first receives the so-called contact concrete layer 2 This latter eliminates unevenness 55 and provides a good surface against which the steel arch I and a grid 3 placed therebetween can bear In the next working phase, the clamping in of the steel arches is finished by means of the force applying construction 100.

In parallel with the advance of the forepoling device, a temporary wire ropeway 4 is installed, it is on this that the force applying mechanism 100 and the 60 manipulator 600 can be displaced.

The formation of the lining by means of shot concrete is illustrated as being in two stages: the application of the contact concrete 2 for the forepoling device is effected by a manipulator 600 connected to the forepoling device by a connecting lo 1,597,804 element 600 a: the application of shot concrete for the load bearing lining is effected by a manipulator 600 b displaceable along the wire ropeway 4, with the construction of the manipulator 600 b being, if desired, the same as that of the manipulator 600 Conveying hoses 6 effect the conveying of the concrete mixture to the spraying or shooting heads 7 and the material issuing from the shooting or 5 spraying machine 300 can be directed to one of the manipulators 600 via a distributor 8 The mixture unit 500 receives its supply from containers 10 advanced along a conveying track 9 either by way of direct emptying of the containers or via balance members 450 Belts 401 are provided after the mixer and between the mixer and the spraying or shooting head there is a transfer belt 402 10 The general constructional form of the force applying mechanism 100 is shown in Figure 2 for the case of a generally non-circular section road On the left hand side of the Figure the construction is shown partly in section in order better to illustrate it In this case, the arch support 1 comprises a roof arch la, side arches lb and a floor or sole arch Id pivotally connected by hinges lc to the side arches The 15 hydraulic working cylinder 101 is connected by an upper hinge or pivot to a transmitting support 102 The forepoling apparatus 200 and the wire ropeway 4 are carried by this support 102 The lower pivot of the working cylinder is connected to a transverse beam 103 which is connected via hinges 104 to bell crank levers 105.

The fixed pivot of the bellcrank lever is the pivot 106, which can be positionally 20 adjusted relative to the pivot 104 The horizontal forces are transmitted from the bellcrank levers 105 to the transfer or transmitting supports 108 by a push rod 107.

The transmitting or transfer supports 109 transmit the vertically downwardly acting forces The base body 110 serves to hold the whole mechanism together The configuration of the floor or sole arch Id may be constructed in various ways and 25 thus the constructional form of the transmitting support 109 may change also In the drawing the support 109 only transmit vertical loads The variant according to Figure 3 shows a transmitting support 109 a which can be clamped by means of a wedge 112 and can form a load of any direction by way of the support 111.

Figure 4, which is a partial section of Figure 2 along the line m-m illustrates 30 that the three pivot support 113, 114, 115 serves for the adjustable support of the carrier 108 and with its aid can be driven next to the base body 110 and thus a favourable position changing condition can be formed.

Figure 5 illustrates the case where the force application takes place with the intermediation of a double arch supporting system The assembled actuating 35 mechanism 100 of the force application construction resembles that according to Figure 2 but here the constructional form of the supports is matched to the arch carrying system which in this example is of circular section The arches Im of the double arched supporting system are fixed to each other by way of fixed elements In and clampable elements 1 k which exert their effect in a tangential direction 40 This system subsequently remains in the concrete wall and is connected to the internal arch supporting system by way of intermediate rods lp, the internal system consisting of a roof arch support 131, side arch supports 132 and a floor support 133 The application of force takes place in the already known manner by means of the actuating mechanism 100, the intermediate supports 108 a and 109 a and the 45 working cylinder 101 A wedge 135 fixes the clamped state in the internal arch support system The wedge 135 is inserted into a guide which is formed either fixedly or adjustably along a stirrup 134 A clamping element Ik is fixed on the part which remains in the concrete wall In the Figure, this is a suitably dimensioned flat steel strap bent onto the perpendicularly bent ends of the arches Im Naturally, the 50 conservation may also be carried out with other suitably formed arch fixing elements, what is essential however is that the clamped-in condition should not release in the event of loosening or de-actuating the force application mechanism 100.

Figure 5 illustrates a mode or variant of roof bolting wherein specially purpose 55 built drilling element 151 is used to form the holes for the anchor bolts.

Expediently, the drilling member 151 is disposed on a drilling support 152 which can provide the required adjustment possibilities and the drilling support is connected to the base body 110 by way of a fixable pivotal connection 153.

The left hand side of Figure 6 illustrates the condition wherein after clamping 60 in of the double arch support according to Figure 5, the force application mechanism 100 has been removed and where the application of shot or sprayed concrete to produce the lining 5 has been achieved It can be seen that the length of the transmitting rods lp should expediently be dimensioned so that it should be somewhat shorter than the thickness of the lining The right hand side of Figure 6 65 1,597,804 1 1 1 1 as seen shows the finished road section; here the cutting off of the rods lp has been accomplished although of course it is possible to utilise the projecting ends of the rods e g for suspending some desired element from them.

The mechanism accomplishing forepoling is designated by 200 in Figure 1 Its actual construction is shown in Figure 7, 8 and 9 Figure 7 shows the construction 5 in its side view in its clamped basic position Figure 8 shows it in its released condition in side view, while Figure 9 is a diagrammatic and enlarged view of the section n-n.

An intermediate support 102 bears against the roof arch la and has a lower connection portion of inverted T profile, which at the bottom forms a horizontal 10 plane At the foot of the T profile there is a displaceable shoe 201 and lower projection of which serves as a guide of the forepoling body 202 A pair of forepoling beams 203 lie against the foot of the T profile and are pivotally engaged at the rear by a guide 204, so that angular displacement in a vertical space or plane is permitted while horizontal displacement can take place along a guide formed on 15 the lower edge of the forepoling body 202 A working cylinder 205 is adapted to rotate the bellcrank lever 206 about a pivot 207 which has arcuate parts 208 to suuport the forepoling beams 203.

Sliding on the shoes 201 along the foot of the intermediate support 102 enables a horizontal change of direction to take place while a change of direction in the 20 vertical plane is produced with the aid of a working cylinder 212 by way of the sliding shoe 210 and the pivot 211 forming part of the upper guide of the forepoling body.

A wedge 214 fitting into the guide of a hook 213 mechanically fixes the forepoling beams 203 The forepoling device is advanced by moving the working 25 cylinder 205 internally so that a rod 215 pivotally connected to the bellcrank lever 206 pushes a slide 209 "backwards", the chain 216 being fittable to the slide 209 and at its other end to a supporting ear of the shoe 210, whereby a horizontal advancing force is generated on the pivot 207.

According to Figure 10 the shot or sprayed concrete lining can be produced 30 with the aid of the spraying machine unit 300 so that a feeding head 304 rigidly connected with an air boiler mounted on a subframe 303 is connectable to a distributor 8 by way of a flexible duct 6 a.

The subframe 303 is so constructed that the concrete application machine units may be mounted serially or in parallel next to each other in the above 35 described manner and can be connected together in the manner of a console The operation of the concrete application units is co-ordinated by a control system 305 so as to be synchronised with the distributor 8 but given individual units may be suitable for working in the material of the lining by themselves.

The feed funnels 301 of the sprayer units are connected together by a hopper 40 mechanism 306 which can ensure the distribution as desired of the material arriving from the conveyor band 402 A mix unit 500 makes up the starting mixture of the material of the lining Feed vessel(s) 550 and feed horns 551 located on the mixer serve to feed the mixing unit at the appropriately rapid manner, the horns being simultaneously charged in an appropriately programmed manner by supply bands 45 401 and dosing outlets 403.

The dosing outlet 403 may operate in the known manner, it may be a screw mechanism or a fluidised mechanism or the like and is preferably angularly displaceable about the vertical axis containing the rotary plate 404.

Figure 11 contains the three basic cases of providing solid feed for the mixing 50 unit.

The material may be directly charged into the feeding vessels 550 from the containers 10 This is expedient principally in the case where the containers contain a single previously charged-in and premixed dose Essentially, this same is true for the direct emptying of the container onto the transport belt 401 One should 55 remark however that in the latter case, the principle of unitary package is interpreted more broadly.

The container 10 with a discharge mechanism at the bottom can be mounted on an emptying hopper 451 An amount of material appropriate to the process is emptied from the container 10 by means of the balance members 450 The balance 60 members 450 can be serially connected under automatic control and are suitable for the assembly of the material in situ and in certain conditions can also form the layers of shot concrete which can be varied on application.

For example, the container 10 is a known type with elastic walls, provided with a charging and bottom-discharge opening and is foldable together In Figure 65 1,597,804 12 there is shown a variant with a double chamber or space wherein the material filled into the bottom space via the charging orifice 10 b is covered by a partition plate 10 d and a second material phase, e g a dry powder phase can be fed in on top of it When the discharge opening 10 c is opened, both materials are emptied simultaneously The container 10 may be suspended by way of support ears 1 Oa All 5 phases of the filling can be carried out with the containers 10 being suspended or mounted on the ground but emptying or discharging can only be carried out in the vertical position.

Figure 13 shows the mixer unit in longitudinal section while Figure 14 is a view of the mixing unit along the arrow F 10 The mixing vessel has two parts: a bottom part 501 and an upper part 502 connected together by a pivot 504 In the closed position, the vessel is expediently at an inclined position, optimally 15-25 , so as to ensure that the emptying or discharging spout 503 should be at a higher level than the bottom On tilting the bottom part 501, of the mixing vessel, it turns about the pivot 511 while the upper 15 part 502 moves relative thereto about the pivot 504, as well as about the two pivot points 505 a and 505 b of the spacer rod 505, whereby the discharge spout 503 empties the material to the transfer belt 402.

The lower part 501 and the upper part 502 of the mixing vessel form an internally cylindrical space the axis of which is shown in the drawing with the 20 reference letters x-x The mixer is driven from a motor 506 by way of transmission 507 and mixing drive 508, the mixing being effected by the mixing blades of a planetary-movement blade system 509 and the rotary blade system 510 The working cylinder 512 is provided to effect the tilting Even with very steep tipping angles, it can occur that a material containing adhesive or agglomerative additives 25 does not flow out through the discharge spout The pivot 505 b is provided on a bellcrank lever 513 which in the tipped position of the mixed vessel can be rotated by way of the working cylinder 514 about a pivot 515 and in this tipped position, the two parts of the mixing vessel are close together Then, the mixing blades of the blade systems 509 and 510 separate the adhered material from the wall of the vessel 30 and by extending the working cylinder 514 again and rotating the mixer 508 perfect discharge or emptying can be achieved.

The filling of the mixer vessel can expediently take place through three apertures at any desired time distribution The side hopper 501 a may receive from the feeding vessel 550 expediently solid particulate additives, from the feed horn 35 551 it can receive dry pulverulent additives or a hydraulic binding material while along the pipe 551 a it can receive liquid phase additives.

The feed vessel 550 is actuated by a tilting mechanism 552 so that a spout 550 b turns about the pin 550 a and sits on the side hopper 501 a The closing plate 515 inhibits the formation of dust and during feed the spount 550 b tips it out of the way 40 so as to open a free cross-section for the discharge.

The operation of the manipulator 600 shown in Figure 1 is shown in detail in Figure 15.

A holding tube 601 serves to fix the manipulator 600 and its position is generally parallel with the axis of the road Pivots 602 and 603 disposed on the 45 holding tube 601 as well as pivots 604, and 605 disposed on the manipulator 607 form a rod parallelogram as a consequence of which when the working cylinder 606 moves, the manipulator body 607 is displaced in a direction parallel with the axis of the holding tube 601 This represents the advance of the manipulator in the direction of the axis of the road The working cylinder is controlled or guided by a 50 manual arm 608 The joystick or directing arm 609 is held in the hand of the operator, its position is always parallel with the spray head 7 and its displacements are of the same direction so that the displacements are in a predetermined direction.

In the cylindrical shaft bore of the manipulator body 607, there is an element 55 610 which can rotate with the aid of the working cylinder 611 about the bore axis or shaft parallel with the axis of the road Its movement is controlled by the appropriate displacement of the manual arm 608 Pivots 612 and 613 are on the element 610 The operating arm 614 and the indicating arm 615 are connected to the pivots A connecting rod 618 located between pivot 616 and 617 is sochosen 60 that the angular displacement of the two arms should be mirror images of each other The operating arm 614 is moved by a working cylinder 619 and is controlled by a control valve 620 on the connecting rod 618, the valve being responsive to the appropriately directed force effect of the directing arm 609 A bellcrank lever 630 is displaceably mounted about a pivot 612 on the body 610 and a lifting lever 629 at 65 1,597,804 the pivot 613 is so disposed that the pivots 612, 613, 624 and 625 should form a rod parallelogram This system ensuring parallel movement also includes on the operative side the rod parallelogram 612, 621, 622 and 623 while on the guide side the rod parallelogram 613, 626, 625, and 627, consequently the displacements of the shooting or spraying head 631 and the base body of the aiming device 632 are in 5 conformity with each other The displacement is carried out by the working cylinder 633 by way of the control valve 628 in response to the force effect of the arm 609.

A bore of the base body 631 of the head rotatively mounts the head casing 634.

Working cylinders 635 causes the angular displacement A flexible shaft 636 10 connects it to a similar flexible shaft of the base body 632 A control valve 639 connected to the tubular shaft 637 the member 638 and the coupling 634 ensures that the movement is in conformity.

Figure 16 shows the construction in principle of the sensing and connecting rods 618 and 628 15 Coaxial and telescoped rods 640 and 641 are arranged between pivots k,-k 2 and are connected together by way of the linkage of a valve 642 The normal centre position of the valve is ensured by a spring against which the rod may be displaced externally or outwardlyhor inwardly to produce the appropriate piston position of the valve 20 It is an advantage of the invention that every operational step of supporting or ensuring roads designed for long life are fully mechanised to enable them to be carried out purely by machines In this way, it achieves a significant reduction in the physical labour carried out in very difficult conditions as well as a shortening of the time required 25 The invention also enables the optimisation of utilisation as well as of the quantity of the installed supporting materials because after determining the parameters of the rock, it utilises the latest rock mechanical principles and can compute all road supporting parameters by computation so as to select the most appropriate support construction and machines 30

Claims

WHAT WE CLAIM IS:-

1 A process for the support of underground cavities by means of support apparatus, wherein a clamping force (P) of the support apparatus and the peripheral distribution of the clamping force is satisfied by the following conditions, taking into account the mechanical and rheological characteristics of 35 the surrounding rock, the geometrical configuration of the cavity and the permissible load of the support, support permissible P=Prppr 2 a An(I eto) and wherein the support spacing is determined as a function of the mode of making the cavity, its geometry, the mechanical and rheological parameters of the 40 surrounding rock, and for a predetermined road life the spacing is given by:

where \ / ( Ppr v Ppr PO where 45 P O =the clamping force P Ppr=the primary stress prevailing at the location of opening of the cavity, g=a factor dependent upon the use to which the cavity is to be put, Usp Ie Prt,,=the standard permitted load of the support, 50 a=the co-operation coefficient of the rock and the support, A=the mechanical constant dependent upon the geometrical configuration and dimensions of the support, n=a safety factor 1,597,804 e= 2 71, the base of natural logarithms, /t=a time dependent co-operation factor of the rock and the support, to=the planned lifetime of the cavity, lo=the increased installation spacing of the support in the case of a clamping force of value PO and 5 l=the installation distance of the support without prestressing.

2 A process according to claim 1, wherein the wall thickness (V) of a shot concrete lining for supporting the cavities for any desired or arbitrary life time is determined by the following relations:

arock 2 (l Ppr-Po)A Lol 1-a{v}( 1-ee O t)= permitted 10 n, 2 (l Ppr-Po)A Lo a{v 21 ( 1-e-t)= Spe Pl O tted na 1 and v=Max v,; v 2 and in the determining wall thickness, being the larger of v 1 and v 2, where: 15 Lo=a factor dependent on the installation spacing of the support v 1 =the lining thickness computed on the basis of the load bearing capacity of the rock, n 1 =a safety factor and furthermore, 4 =is a function of the dimensions in geometry of the support, 20 v 2 =the lining thickness computed on the basis of the load bearing capacity of the support, n 2 =a safety factor.

3 A process for supporting underground cavities substantially as herein described with reference to and as shown in the accompanying drawings 25 4 Apparatus when used in the process of claim 1, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

T Z GOLD & COMPANY, Chartered Patent Agents, European Patent Attorneys, 9 Staple Inn, London WC 1 V 7 QH.

Agents for the Applicants.

Printed for Her Majesty's Stationery Office, by the Courier Press, Leamington Spa, 1981 Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.

1.597804