Process and arrangement for the support of underground cavity systems by an efficient safety casing wall

This invention relates to a method for bracing an underground cavity, wherein the cavity is lined with a tensionable layer, an expansible arch is then inserted against said layer, the arch is then tensioned and clamped in position to exert pressure in accordance with a specified formula.

The invention concerns a process and an arrangement for the complex support 
of underground cavities or cavity systems such as mine road or drift, 
tunnel, industrial halls, liquid reservoirs, etc. 
The disadvantages of the generally known processes and arrangements for the 
same purpose are as follows: 
As a consequence of the manner of installing the temporary and permanent 
support devices (props, shafts, rings, etc.) a full adaptation of the 
support to the rock is obtained at a point in time determined by the 
rheological properties of the surroundings, generally after a significant 
rock deformation. 
As a consequence--even before the support is loaded--rock deterioration 
starts which results in a considerable narrowing of the sections and 
increases maintenance costs. This 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 in advance--, consequently at certain 
locations of the support stress peaks may form which result in damage or 
destruction zones not only in the rock but also in the support. 
The hitherto known support installing technology could not be taken into 
account in a precalculable manner so that the support structure 
substantially influences the surrounding rock; this reaction may cause an 
unavoidable process of heavy destructions, and cannot provide for a 
favorable balance between the rock and the support. 
Attempts are known to classify rock into different classes on the basis of 
an idealization of their actual characteristics and behavior. The strength 
characteristics of the support are to be associated with these idealized 
characteristics. (See Rabcewict-Sattler: The new Austrian Tunnel Building 
Method. Bauingenieur 1965, No. 8). 
Naturally this idealization did not allow the most recent researches into 
the mechanics of rock to be carried into practice and has hindered the 
spread of the recent technology. 
It is no coincidence that the mentioned method has only been maintained in 
the field of tunnel construction. Serious damages, and even destructions, 
can be prevented by the closed-loop regulating system according to this 
invention, wherein the support cooperates with the surrounding rock to 
adjust a load-distribution level between the rock and the support; both 
the rock and the support; both the rock and the support are expected to 
endure deformations which exceed the permitted magnitudes. Conventional 
solutions do not provide a facility to modify the value of the rock 
pressure within wide limits. In these cases the pressure of the 
surrounding rock constitutes an in situ natural characteristic, and thus 
load levels arise which virtually necessitate destruction of the support. 
Thus new supports have to be built in from time to time. 
The conventional solutions only provide specific data--relating solely to 
the support--and do not provide development of a modular process and 
apparatus--noting that cavity formation and their support constitute a 
complex system--which can be adapted to varied cavity forming methods, 
geometric configurations of the caivty, and to varying transport systems, 
forming an integral unit with such systems. 
The gist of the invention consists in that the changes that take place in 
the course of forming a cavity are defined according to the results of the 
latest rheological researches as they relate to the rock and the support 
structure, the parameters being determined according to a complex system 
involving all the characteristics of the surrounding and their change with 
time. The processes and arrangements are then realized by the aid of these 
parameters. 
The technological steps determined by the invention are thus time-dependent 
functions, the relative use of which is interpreted on the basis of the 
rheological changes of the rock and the support. From this it follows that 
the essential feature of the invention is the scientific discovery that in 
the support of underground cavities, the emphasis is not on a defense 
against nature (by taking up the pressure of the rock with a support 
apparatus) but rather through a good knowledge of the laws of nature by 
utilizing these laws such that a deliberate regulative activity is 
achieved rather than a mere defense. 
Thus the invention concerns a system of practical deductions inferrable 
from the new theories concerning the mechanics of rocks wherein the 
planning, dimensioning and technological formation of the support and 
supporting devices as well as the installations therefor are all 
incorporated. 
The support of cavities made by the various technical and technological 
processes is a complex task. In the course of solving this task one must 
have regard to a complexely interrelated system of conditions of which the 
principal element groups are the following: 
stress conditions in the neighborhood of the cavity 
physical and mechanical parameters of the rock 
manner, means and technology of forming the cavity 
geometry (shape and dimensions) of the cavity 
characteristics of the used support. 
The exemplary elements of the following description may naturally be 
substituted by structural elements of similar function but the essence of 
the invention consists in their coordination into a unitary system. 
In accordance with the foregoing it is our opinion that the rock formation 
and the supporting structure form a collaborating double system wherein a 
suitably constructed support apparatus and the excess pressure caused by 
the bracing of the cavity, the so-called transferred pressure, are divided 
between the rock and the support in such a way that both accommodate the 
excess pressure without damage or destruction. 
This recognition has led to a re-evaluation of the task of supporting 
structures and to the development of new support technologies suited to 
these new circumstances. 
The requirements of the support are the following: 
a/ Activity. By this is meant the property of the support which immediately 
on installation takes part in road balancing, prevents the excess pressure 
to be transferred to the rock, which would initiate processes whereby rock 
falls could occur and the controllability of the mechanical phenomena 
could be lost. 
b/ Yieldability. By this property the automatic control of the dual 
(rock-support) system can be realized. The support apparatus installed in 
the caivty is made to be in contact with the rock and takes part therewith 
in the bearing of the excess pressures or stresses. The transfer of load 
from the rock to the support takes place with certain attendant 
deformations. Since all rock-mechanical process is a rheological process 
this transfer of stress takes place continuously with time at a rate 
dependent upon the support constants and the characteristics of the rock. 
The yieldability of the support is destined to fulfill a regulating 
function of undergoing a permissible small deformation whenever the load 
is transmitted to the support or reaches an undesirable value whereby to 
avoid a destructive load on the support. 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 represents the sum of the strength characteristics 
of the supporting structure. Without suitable load-bearing capacity, an 
equilibrium state could only be reached after complete filling up of the 
cavity, tantamount to the destruction of the cavity and its surroundings. 
The requirements of the support are fully met by a so-called steel 
supporting apparatus employing tensioning and/or a shaft support with shot 
or sprayed concrete (possessing adequate elasticity and rigidity 
characteristics). 
In the case of using a 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 pressure with the aid of 
hydraulic forepoling and tensioning apparatus. By tensioning the 
support--with a pressure P.sub.o --the value of the transferred pressure 
is decreased to (P.sub.pr -P.sub.o).L compared with the original value 
P.sub.pr.L, wherein P.sub.pr represents the primary pressure normal to the 
plane of the cavity under examination, and L is the relevant dimension of 
the cavity. The following correlations are set out for explanation: 
how the support should be pre-tensioned in the case of a section of long 
life, 
how the support should be pre-tensioned in the case of cavities of a 
planned lifetime, 
how the support should be pre-tensioned according to the mechanical 
condition of the surrounding rock in the case of the most favorable cavity 
configuration, 
how the installation length of the support should be determined. 
The pre-tensioning of the support in the case of long life (exceeding 15 to 
20 years) takes place with a pressure P.sub.o : 
##EQU1## 
wherein 
.xi. is a factor dependent on the purpose of the cavity 
P.sub.pr is a primary stress prevailing at the location of bracing the 
cavity 
.sigma..sub.meg.sup.bizt is the standard load permitted for the support 
n is a safety factor 
.alpha. is the cooperation coefficient of the rock and the support, 
expressed by the multi-variant function: 
EQU .alpha.=f(E.sub.b, m.sub.b, L, K.sub.b, G), wherein 
E.sub.b is the elastic modulus of the support 
m.sub.b is the Poission number of the support 
L is the main dimension (span length) of the support 
K.sub.b is the standard cross-sectional factor of the support 
G is the elastic modulus of the rock jacket 
Pre-stressing of the support in the case of a planned life t.sub.o : 
##EQU2## 
wherein 
e is 2.71 (the base number of natural logarithm) 
t.sub.o is the planned life of the cavity 
.beta. is the time factor of the cooperating rock and support, which can be 
calculated on the basis of rheological constants of the support and the 
rock, as well as the dimension of the construction: 
EQU .beta.=f(E.sub.b, m.sub.b, L, K.sub.b, G, .tau., .eta.) 
in which expression 
.tau. is the relaxation factor of the rock 
.eta. is the viscosity factor of the rock, creep modulus 
.xi. is a factor dependent on the purpose of the cavity 
P.sub.pr is a primary stress prevailing at the location of bracing the 
cavity 
.sigma..sub.meg.sup.bizt is the standard load permitted for the support 
n is a safety factor 
A is a mechanical constant which is computed from and depends on the shape 
and dimensions of the support 
.alpha. is the cooperation coefficient of the rock and the support 
(The further symbols have the same significance as above). 
In the case where the most favorable shape of the cavity (from the point of 
view of the load distribution of the rock and the support)--regarding the 
mechanical condition of the rock--cannot be formed then the pre-stressing 
of the support to be installed in a section of given geometry must be 
determined such that it approximates an optimum stress condition. 
The pressure transmitted through a pressing jaw in the direction of the 
primary principal stress makes an angle .psi. with the clockwise 
direction: 
##EQU3## 
wherein 
P.sub.o is the pressure value 
k is the quasi-Poisson number valid for the location of the cavity bracing 
INSTALLATION LENGTH OF THE SUPPORT 
Let 1 be the installation length of a support in the case of a support 
apparatus without prestressing. If the latter is of the value P.sub.o then 
the installation length can be increased by a factor of .psi., i.e. 
EQU 1.sub.o =1..psi. 
in which equation 
##EQU4## 
.xi. is a factor dependent on the purpose of the cavity 
P.sub.pr is the primary main stress 
P.sub.o is the pre-stressing which values can be computed from equations 1 
and/or 2. 
For certain parts or measures of the invention earlier attempts are known, 
such as for instance the German Pat. No. 1,143,468, relating to the 
pre-stressing of the support. 
However, the known processes are not efficient because they did not take 
into account those mechanical processes taking place with time wherein the 
rock environment and the support display a behavior or functions that are 
determined in advance. This means, e.g., that in a primary field 
characterizable with a quasi-Poission number of k=2 or a figure close 
thereto, the true-to-side lateral support clamping in the case of a driven 
road can cause such serious damages which only cease 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--in the 
knowledge of the parameters of the rock, and of the primary stress 
field--provides the possibility of using an optimum technology, taking 
measurements with the aid of a computer, for maintaining control of the 
mechanical processes which change with time. 
CONTINUOUS SHAFT SUPPORT (SHELL SUPPORT) OF AN ADEQUATE ELASTIC MODULUS 
The use of traditional shaft supports has the defect that there is lack of 
cooperation between the rock and the shaft vault. In the case of a usual 
shaft thickness (v/d.gtoreq.1/8) the shafts are very stiff. 
These defects can be eliminated--at least reduced--by filling up the gap 
between the rock mantle and the shaft support, or by the utilization of 
yielding inserts. 
When this gap is filled manually with mortar this expedient is useless. 
Although in given cases the injection of said or mortar can provide a 
better filling this expedient is still not satisfactory. 
The fundamental defect of filling the space behind the shaft is that this 
can only be effected after the event and the effect of cooperation arises 
only belatedly, in other words only after destruction of the rock takes 
place--during the period of the separately encountered stress. One can 
accordingly appreciate the importance of density at the support points 
(slide-bar heads) of the cavity mantle. 
The above-described defects are completely eliminated by the inventive 
process by using a shot or sprayed concrete technology, adapted to the 
latest rock-mechanical principles and determined in advance. 
The thickness of the shot or sprayed concrete layer is a definite part of 
the cavity but is of a smaller magnitude and therefore has to be regarded 
as a sheel construction. The small layer thickness and a perfect fit to 
the rock result in such a support being of predetermined deformability 
(elasticity) which perfectly cooperates with the rock from the 
commencement of the installation. 
The new principles, related to the rock mechanics, determine the behavior 
of the cavity environment, and on that basis one can determine the change 
in time of the load increase on the shot concrete shell; thus the 
hardening of the shot concrete can be controlled in a programmed 
manner--with the deliberate proportioning of the concrete mixture. 
The dimensional correlations described below ensure the optimum 
coordination of the two processes and the formation of the most favorable 
construction as well as the maintenance at a predetermined load-bearing 
value between the rock and the support. 
The function of the cavity support construction realized by means of the 
shot concrete technology can be characterized in that the shell 
construction matches the rock perfectly, it has corresponding statical 
properties, and satisfies all demands made on the supporting apparatus 
(activity, yieldability, load-bearing capacity). A further advantage of 
this procedure is that it can be fitted into any cavity bracing technology 
and is readily mechanizable. 
The wall thickness of the shot concrete shaft in the case of a longer life 
(greater than 20 years) can be determined by two methods: 
a/ The load on the rock should not cause a destructive process at the 
circumference of the cavity, i.e. the reduced standard stress rising in 
the rock mantle should at no time exceed the permitted value: 
##EQU5## 
The value V.sub.1 can be determined from the following relation, where 
.alpha.=.alpha. ( . . . V.sub.1 . . . ): 
##EQU6## 
The standard load of the support should remain below a permitted value: 
##EQU7## 
The thickness V.sub.2 of the support can be calculated from the 
correlation: 
##EQU8## 
The wall thickness of the support should be taken equal to the greater of 
V.sub.1 and V.sub.2, i.e.: 
EQU V=Max{V.sub.1 ; V.sub.2 } 
Symbols: 
.xi. is a factor dependent on the purpose of the cavity 
P.sub.pr is a primary stress prevailing at the location of bracing the 
cavity 
P.sub.o is the prestressing pressure of the support 
A is a constant which is computed from and dependent on the shape and 
dimensions of the cavity section 
L.sub.o is a function dependent upon the installation length of the support 
.alpha. is the cooperation coefficient of the rock and the support, that is 
a function of the geometrical dimensions of the cavity and the wall 
thickness of the concrete support, as well as the material constants of 
the rock and the support 
.phi. is a function of the geometry of the support dimensions 
n.sub.1, n.sub.2 are safety factors 
In the case of a support of shot concrete of circular section with a radius 
R and a thickness v the following values apply: 
##EQU9## 
wherein 
E.sub.b is the elastic modulus of the support 
G is the creep elastic modulus of the rock 
m.sub.b is the Poisson number of the support 
Determining the wall thickness of shot concrete for a life t.sub.o ; 
v.sub.1 is determined from the equation: 
##EQU10## 
and v.sub.2 is determined from the following equations: 
##EQU11## 
.beta. is a cooperation time factor of the rock and the support, which in 
the case of a circular section of a radius R and a wall thickness v is: 
##EQU12## 
wherein 
.tau. is the relaxation factor of the rock 
.eta. is the creep factor of the rock 
In order to form the shot concrete wall one requires a machine line which 
can produce the supporting structure that can optimally adjust itself to 
local conditions of the structural elements, can solve the transport and 
the correct proportioning of the materials in accordance with concrete 
technology. By this machine equipment one can 
1/ perform an efficient, entirely homogenized function that activates the 
mixture 
2/ and which concrete, composed by the homogeneization, is brought to the 
surface in a suitable manner. 
The support construction can be built in by itself with clamped-in steel 
supports, with such supports stabilized with reinforced concrete, and with 
a reinforced concrete construction. Where a concrete or reinforced 
concrete structure is combined with the clamped steel supports, account 
must be taken of the hardening process of the concrete. 
As is well known the formation of the rock pressure is also a 
time-dependent process. The above-described dimensioning process makes it 
possible optimally to coordinate the two processes and thus to form a 
structure 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 shot concrete technology and fulfils two functions: 
a/ the ground concrete layer is continuously applied to the surface of the 
rock where it causes an excess stress on the gangue material to prevent 
loosening of the rock while at the same time forming a transitional layer; 
b/ a load-bearing concrete shell is formed which is expediently monolithic 
reinforced conctete and which acts as a load-bearer in the course of the 
already described mechanical cooperation of the concrete support and the 
rock. 
The contact layer, known per se, serves as a transitional layer which 
penetrates into the gaps and adapts itself to the load-bearing wall, 
account being deliberately taken of the material characteristics 
(rheological characteristics of the rock, its breaking strength, moisture 
content, etc.). 
In comparison with the known principles, the clamping is supplemented by 
new procedural steps. 
For example, the clamping device according to German Pat. No. 1,193,904 is 
not suitable for the controllable clamping of loads in the vertical and 
horizontal directions, or to clamp supports of a balanced moment. A 
cooperation with forepoling is not achieved. The situation is the same 
with German Pat. No. 1,408,727. Favorable cooperation of the ring and of 
the rock requires a clamping apparatus which is adjustable to transfer not 
only circumferential but also radial loads and at a controllable location, 
so as to achieve favorable contact conditions and/or surfaces. 
For this reason, the disclosures of German Pat. Nos. 2,326,686 and 
1,283,778 are less effective because they are suitable only to exert 
tangential loads. 
The task is only partially solved by the known clamping devices of the 
polygonal type (see German Pat. No. 1,193,457 and Hungarian Pat. No. 
162,676). The latter teaches that active support can be effective only if 
it is exerted on a shield surface, thus proving the necessity of an active 
shield for branch sections in case of drifting with mechanized winning. 
The present invention contains a proposal that is equivalent with the 
above-mentioned but its field of application is different. 
A known construction partially solves the above-mentioned disadvantages but 
its use is limited to specially constructed roof arch supports and is not 
suitable for exerting large clamping forces. 
The forepoling mentioned in the inventive process, and/or one phase of its 
technology, may in principle be carried out with 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 
coordinated. 
The possibility of this cooperation is considerably limited as can be 
proven with reference to the German Pat. Nos. 2,360,726 and 2,252,450. 
Another solution, such as that in German Pat. No. 1,080,948, involving a 
crab, cannot exert adequate forepoling forces and additionally does not 
enable the joint tensioning of the lining or of the arch. This same 
disadvantage prevails also with the construction of German Pat. Nos. 
2,253,670 and 1,180,704. Other known solutions are limited to solving a 
given partial task only, e.g. supporting the face (see German Pat. No. 
1,193,911) or e.g. the so-called Moll arches. 
The aim of the force-introducing mechanism is to change the stress 
condition of the rock jacket to a 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 
the working phases of the forepoling device, effected by a displacement of 
a wire ropeway formed on the forepoling apparatus, connected to a 
pre-tensioned (i.e. forepoled) upper prop so that the position and stress 
condition of the latter do not change. 
2/ The available space is advantageously exploited. To this end, a 
hydraulically operable clamping mechanism is used to which temporary 
supports are connected by way of exchangeable elements--depending on the 
shape of the cavity. The elements are suitable to take up forces acting in 
the direction of the sides and the floor. The upper transition is 
constituted by the projections formed to suit the forepoling device. 
3/ A support system for introducing divided forces, which is divided by the 
spacing elements into an external and an internal support zone. Both 
supports can be clamped by themselves but not necessarily with the same 
direction of force introduction and magnitude of force reception. 
4/ A mechanism described in 3/ can also be constructed so that the outer 
support system is filled with concrete, and during the hardening--setting 
time tension of the internal support arch--provides the supplementary 
portion of the conserving reaction system and is dismantled once the 
concrete has hardened. 
5/ A force introducing and transmitting mechanism wherein the internal 
hydraulic clamping mechanism and/or temporary supports connected thereto 
cintain a securing projection to which a drilling machine--for anchoring 
the rock--and a feed lafette can be secured for including a rock screw of 
proper direction. 
6/ The performance of force introducing is carried out by partially 
simultaneous rock anchoring and the latter takes place in the course of 
the conservation of the clamping. 
Clamping mechanism: Connection or support which contacts the cavity section 
and is capable of introducing the forces. 
1/ The arch elements are clamped by radial devices using such forces as 
will ensure that the support element, e.g. a clamping ring, is deformed to 
some extent in the cavity. The points of attack of the forces are so 
determined that the bending stresses in the arch elements are equalized to 
a certain degree. 
2/ The mounting and clamping described in 1/ is combined with tangential 
stressing of the arches so as to conserve the stressing effects. 
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 a tangential 
component. 
4/ The mounting of the support apparatus (e.g. a ring) is clamped 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 along the axis of the road) whereby to transmit 
clamping forces so that the intermediate space is protected from fall and 
is pre-tensioned by pressure. 
5/ The mounting can also be performed for the force conservation so that 
the used elements remain partly in the concrete but may be partly located 
outside the concrete. The latter elements can be recovered after the 
concrete has set. Forepoling follows the sequence of making the cavity 
(road building, tunnel building, etc.) and loading, or is parallel with 
the latter in the operational sequence of cavity formation. 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 the transition to the clamping in of the support element 
without loosening the rock. 
Forepoling can be performed according one of the following operational 
procedures: 
1/ In an operational step the roof support elements and the spatial grid 
elements are clamped in at the same time in a position that the same is 
not changed when the final forces are introduced. 
2/ Forepoling can also take place by a different method, with paired 
support beam which are movable by way of a hydraulic mechanism via a lever 
so that during forepoling the beam is not only tilted from its lower 
position but also performs a forward motion. 
3/ The arrangement needed for this purpose can be built such that the 
vertical and horizontal bends of the cavity are simultaneously secured: 
by an upper (transitional) support wherein the forepoling main support is 
fitted with the aid of a displaceable guide; 
The upper guide of the main support is divded into two parts by a pivot; 
the rear portion can be adjusted in accordance with the requirements of 
the curvature of the cavity; 
An element (e.g. a chain) is moved through the working cylinder of the 
arrangement, in its idle phase, which advances the apparatus step by step. 
The generation of the stresses and deformed cidition as well as their 
conservation produced by clamping with radial and tangential forces may 
also be combined with the per se known rock bolting. The rock bolt is 
suitable for achieving force conservation by radially acting means. The 
bedding of the rock bolting performed not only along tangential but also 
along axial support elements (that is along the axial supports of the 
grip). Thus the created stress condition may be optimally chosen and 
maintained both in the plane of the expanding ring and in the intermediate 
field. 
By having due regard to the main directions of the stresses and the 
magnitudes of the primary stresses, the disposition of the rock bolts can 
be such that the given cavity configuration assumes an optimal stress 
condition. 
In order to realize the inventive process the machine arrangement requires 
the following conditions to be fulfilled: 
it should fit in well in the complex technological processes of cavity 
formation; 
it should not handicap the performance of the other steps; 
it should provide an output as required by the velocity of the face; 
it should ensure the multi-stage shaft formation so that in given cases the 
installation of the required steel section supports (e.g. installation of 
the steel rings), as well as the subsequent procedural step, is carried 
out with the same machines, and also the application of the contacting 
concrete and the load-bearing shaft; 
it should be suitable for walling any kind of cavity (road construction, 
etc.). 
The preparation of a monolithic shaft can be divided into two technological 
main groups: 
1/ the composition and homogeneization of the material; 
2/ the spreading of the material. 
The compiling of the shaft material consists in the selection of solid, 
particulate or pulverulent materials, liquid binder materials, etc., which 
are intermixed in predetermined quantities from prepared packages or 
containers. 
Because of the given characteristics of the site--the composition of the 
material requires--according to the operating possibilities--such 
arrangements that consist of variable elements which can be put together 
in a modular manner. An absolute pre-condition is the space requirement 
and the necessary transport path. A relative condition is constituted by 
the opening of a road section and the associated technical procedures. 
The formation of the wall is effected by a shooting machine. (A known 
machine can be studied in German Pat. No. 2,000,278.) A shooting head is 
attached to the end of its hose. The lining of individual sections of the 
wall cannot always be carried out by the operator while standing on the 
ground. Movable platforms have proved useful in external use but in 
underground working sites can only be used on larger sections. In most 
cases the dimensions of the platforms are such that they cannot be kept in 
operation together with the machines--which carry out the required 
technological operations--and cannot therefore be properly used. 
An effective solution is realized by a manipulating apparatus with 
automatic position control, which enables the operator to apply one charge 
of concrete in one position with a satisfactory quality. The application 
of shot or sprayed concrete technology requires that the operator should 
feel the forces exerted on the shooting head and see its movement and the 
formation of the wall of lining. 
It is better if the operator is disposed from the spraying head at a 
distance of a few meters, in a quiet situation--while being in complete 
possession of his capacity for intervening directly and for sensing the 
physical parameters--and should be abel to form a complete, perfect lining 
in a fixed position, without moving the platform.

Reverting to FIG. 1 one notes that the installation of a support into a 
mining section commences by inserting a main prop 1a of steel arches 1. 
The main prop is tensioned by a forepoling apparatus 200, applying to the 
surface of the cavity first a contacting concrete layer 2. This eliminates 
unevenness so that both the steel arches 1 as well as a grid 3 placed 
therebetween are properly supported. The steel arch or support being 
completely mounted in the subsequent working phase, is clamped by a force 
applying device 100. 
Parallel with the advancement of the forepoling device 200 a temporary 
ropeway is installed; the mechanism 100 and a manipulator 600 can be 
displaced along this ropeway. 
The formation of the lining or wall is accomplished with shot concrete, 
being illustrated in two stages: the concrete layer 2 is applied or spread 
by the manipulator 600 that is attached to the forepoling apparatus. 
Between the latter and the manipulator 600 there is a connecting element 
600a. The concrete is shot for a load-bearing lining 5 by the aid of a 
manipulator 600b displaceable along the ropeway 4, the manipulators 600, 
600b having identical constructions, if desired. Hoses 6 effect the 
conveying of the concrete mixture to shooting heads 7. The material issues 
from a concrete shooting machine 300 and is guided through a distributor 8 
into one of the manipulators 600. 
The concrete mixture is filled from containers 10 (which are movable along 
a conveying track 9) into a mixer unit 500 either by direct emptying or 
through the intermediary of a balance 450. Transfer of the material before 
the mixer unit is performed by way of a conveyer belt 401, and by the 
intermediary of a further belt 402 between the concrete shooting machine 
and the mixer unit. 
A general constructional form of the force applying mechanism is shown in 
FIG. 2 for the case of a road section which does not have a circular part. 
(On the left-hand side of the illustration the arrangement is partly shown 
in section.) 
The arch support 1 includes a roof arch 1a, side arches 1b and a floor or 
sole arch 1d connected by hinges 1c. A force transmitting support 102 is 
connected to the upper pivot of a hydraulic working cylinder 101. A lower 
pivot of the cylinder is connected to a transverse beam 103, which latter 
is connected to a bell-crank lever 105 by way of pivots or hinges 104. The 
lever 105 has a stationary pivot 105 which is adjustable in relation to 
the hinge 104. Horizontal forces from the lever 105 are conveyed to a 
force transmitting support 108 by way of a push rod 107. The horizontally 
acting forces are transmitted through the levers 105. A base body 110 
serves to hold the entire mechanism together. The configuration of the 
floor or sole arch 1d may be completed in various ways and thus a force 
transmitting support 109 may also have various embodiments. In the 
exemplary embodiment a support 109 is shown that only transmits vertical 
loads. According to FIG. 3 a transmitting support 109 can be tensioned by 
means of a wedge 112 and can endure any loads by way of a support 111. 
FIG. 4 illustrates a partial section m--m of the arrangement according to 
FIG. 2. The support having three pivots 113, 114, 115 is for adjustably 
holding the support 108. With its aid, the latter can be bent to the base 
body 110. This allows a favorable position changing condition. 
FIG. 5 illustrates the case where force application is performed with a 
double arch supporting system. The assembled actuating mechanism 100 of 
the force applying mechanism is again similar to that shown in FIG. 
2--however with the difference that the force transmitting supports are 
adapted to the section of the cavity. The arches 1m of the system are 
fixed to each other by way of fixed connecting elements 1n and a clampable 
connecting element 1m (which are effective in a tangential direction). 
These parts remain later in the concrete and are connected to the inner 
support arch by way of force transmitting rods 1p, the arch consisting of 
a roof arch support 131, a side arch support 132 and a lining support 133. 
Forces transmitted by means of the mechanism 100, by way of force 
transmitting supports 108a, 109a and the operating cylinder 101 (known per 
se), the fixing of the clamped condition being accomplished on the support 
arch system by clamping a wedge 135. The latter is clamped into a 
stationary guide disposed on the support arch and/or on a similar guide 
adjustable on a stirrup 134. On the part that remained in the concrete, a 
clamping element 1k is attached. The latter is a suitably dimensioned flat 
steel strap bent onto the perpendicularly bent ends according to the 
illustration. Naturally, conservation may also be carried out with a 
suitably formed fixing element. It is essential however that the 
clamped-in condition be maintained when the force applying mechanism is 
released. 
The figure illustrates a roof bolting by way of screws, the holes for the 
bolts being formed by the aid of a drilling lafette 151 serving this 
purpose. 
Preferably the drilling lafette is mounted on a drilling support, can be 
set to any desired position, and can be connected to the base body 110 by 
means of a pivotal connection 153. 
The left-hand side of FIG. 6 illustrates the condition wherein the lining 
or wall is completed with shot concrete after the arch support has been 
clamped according to FIG. 5 and the force transmitting mechanism removed. 
One can see that the length of the transmitting rods 1p is to be chosen 
such that it is somewhat longer by the amount of the wall thickness. On 
the right-hand side of the figure one can see the completed road section. 
Here the rods 1p are shortened (cut off); it is however possible to 
utilize the protruding rod ends for suspending purposes. 
The forepoling apparatus 200 is shown in detail in FIGS. 7, 8, 9. FIG. 7 
shows the mechanism in a side view and in its clamped position, FIG. 8 
being similarly a side view, in the lowered position, and FIG. 9 
constitutes a schematic section of the forepoling apparatus along line 
n--n. 
The intermediate support 102 bears against the roof arch 1a. The lower part 
has an inverted T-profile and has at the bottom a horizontal plane. 
At the foot of the T-profile there are displaceable shoes 201 the lower 
projections of which serve to guide a forepoling body 202. Similarly a 
pair of forepoling beams rests at the foot, which is pivotally attached at 
a guide 204. This position allows vertical movement in the space, the 
horizontal movements being realized at a guide that is formed on the edge 
of the forepoling body. A bell-crank lever 206 can be rotated about a 
pivot 207 by means of a working cylinder 205, having an arcuate console 
208 that supports the forepoling beams 203. 
A horizontal change of direction is made possible by sliding the shoes 201 
along the foot of the intermediate support. A change in the vertical plane 
is possible with the aid of an adjustable sliding shoe 210 of a pivot 211. 
The required position can be attained by a working cylinder 212. 
The forepoling beams 203 are mechanically fixed by a wedge 214 fitted into 
a guide of a console 213. 
The forepoling apparatus is advanced by the aid of the working cylinder 205 
such that a rod 215, pivotally connected with the lever 206, pushes a 
slide 209 "backwards", a chain 216 being on its one end attached to the 
slide while a supporting ear connects the other end to the shoes 201. Thus 
the pivot 207 exerts a horizontal advancing force. 
The shot concrete lining is produced with the spraying machine 300 (see 
FIG. 10). A shooting head 304--which is rigidly installed on an air tank 
302 disposed on a subframe 303--is connected with the distributor 8 by way 
of a flexible conduit 6a. The subframe is so constructed that the 
individual shooting units are mounted parallel or in a row, interconnected 
in a known manner. A cooperation of the shooting units is synchronized by 
means of a control system 305 and as the distributor 8 although a single 
shooting unit is suitable for applying the concrete lining. 
Feed funnels 301 of the apparatus are interconnected by a hopper mechanism 
306 whereby the material arriving from the conveyer band 402 is 
distributed. The output mixture is compiled in the mixer unit 500. For 
operating the mixer unit, feed vessels 550 and feed horns 551 are 
provided, the latter being disposed at the mixer unit. Charging of the 
horns is accomplished simultaneously and automatically according to a 
predetermined program by the operation of the band 401 and dosing outlets 
403. 
These outlets may be operated by a known screw mechanism or on the basis of 
the known fluidization principle. The mixer unit is preferably rotated 
about a vertical shaft by the aid of a rotating mechanism 404. 
FIG. 11 illustrates three conditions of material supply through the mixer 
unit. 
The material of solid consistency directly charged into one of the vessels 
550 from the container 10. This is most advantageous when a particular 
amount of the material is to be stored in the container 10 (corresponding 
to a charge). The same applies to the conveyer band 401 so that a 
container can be directly emptied. It should however be noted that in the 
latter case a particular amount of material should be interpreted in a 
broader sense. The container 10 is opened at the bottom and can be placed 
onto a hopper 451. The material from the container is weighed on the 
balance 450, and the desired amount is then discharged. 
The structural elements from which the balance 450 is assembled can be 
interconnected with an automatic control system, and they are suitable for 
compiling the desired amount of material in situ. This allows variable 
quantities of different wall thicknesses to be produced from the shot 
concrete, in a pre-programmed manner. 
In FIG. 12 a further exemplary embodiment is shown which contains two 
spaces. The material is filled into the lower space by way of a charging 
orifice 10b, then being covered with a partition plate 10d. This allows a 
different kind of material (for example powders) to be stored above (in 
the upper space). After a discharge orifice 10c is opened, the various 
materials can be emptied simultaneously. The container 10 may be suspended 
by way of ears 10a. The container can be filled in any position but the 
discharging should only be performed when it is suspended. 
FIG. 13 shows the mixer unit in a longitudinal section while FIG. 14 is an 
axonometric illustration in the direction of the arrow F. The mixing 
vessel has two parts: a lower part 501 and an upper part 502, that are 
coupled together by way of a pivot 504. In the closed position, the vessel 
is preferably in an inclined position (optimally 15.degree. to 
25.degree.), so that a discharge spout 503 should be higher than ground 
level. 
On tilting, the bottom part 501 is pivoted about a pivot 511, and the upper 
part 502 about the pivot 504--as a result of the position of two pivot 
points 505a and 505b of a spacer rod 505--whereby the discharge spout 503 
empties the material onto the belt 402. 
Both the upper and the bottom parts of the vessel have an inner, 
cylindrical space, the axis x--x of which is designated in the 
illustration. The mixer unit is driven by a motor 506 by way of a 
transmission 507 and a drive 508. Mixing is effected by the aid of a 
rotated blade system 510 and another blade system 509 that performs a 
planetary movement. Tilting is accomplished with a working cylinder 512. 
It happens that the material, mixed with adhesive additioves, cannot be 
discharged through the spout 503--even with a very steep tilting angle. 
The pivot 505b is provided on a bell-crank lever 513 which can be rotated 
in the titled position of the vessel by means of a working cylinder 514 
and an articulation 515 so that the two parts are locked in the tilted 
position. This allows the material to be separated by the mentioned blade 
systems 509, 510, the working cylinder 514 is again actuated so that the 
drive 508 performs rotary movement. The material is consequently removed. 
The filling in of the material is preferably preformed through three 
apertures, in any desired time distribution. From the feeding vessel 505, 
the solid, particulate additives may be fed through a lateral hopper 501a; 
the dry, pulverulent additives and/or the hydraulic filling material 
through the feed horn 551; and the liquids through the pipe 551a. 
The feed vessel 550 is actuated by a tilting mechanism 552 in that it can 
be rotated about a pin 550a whereupon a discharge spout 550a can be placed 
onto the side hopper 501a. Pulverization is inhibited by a closing plate 
515. During feed this plate is lifted by the spout 550b so that a free 
cross-section is opened for discharging. 
The manipulator 600 is shown in FIG. 15. 
A holding tube 601 serves to fix the manipulator 600, and its position is 
generally parallel with the axis of the road section. Pivots 602 and 603 
on the tube as well as further pivots 604 and 605 mounted to the 
manipulator 600 constitute a parallelogram. When a working cylinder 606 is 
actuated a body 607 of the manipulator moves parallel to the axis of the 
holding tube 601. This realizes a movement of the manipulator that is true 
to the axis. The working cylinder is controlled by an arm 608. A directing 
arm 609 is held by the operator, its position being always parallel to the 
shooting heads, its directions of movement being identical, and the 
displaced distances being proportionally projected in advance. 
In a cylindrical bore of the manipulator body 607 is a member 610 that is 
rotated about a drilling axis parallel to the road section by means of a 
working cylinder 611, its movement being controlled by shifting the arm 
608. Pivots 612, 613 are on the member 610. The former performs the 
operation while the latter gives a back signal. Between pivots 616, 
617--mounted to the arms 614, 615--there is a rod 618 which is chosen so 
that the relative rotation of the two arms occurs in mirror fashion. 
The arm 614 is moved by a working cylinder 619, it is controlled by a valve 
620 which is disposed on the rod 618. The control valve 620 is responsive 
to the force effect of the arm 609. A bell-crank lever 630 is provided on 
the member 610, rotatable about the pivot 612, and the pivot 613 has a 
further lever 629 such that the pivots 612, 613, 624, 625 constitute a rod 
parallelogram. This system performs parallel movements and has associated 
therewith on the operating side a rod parallelogram consisting of the 
pivot 612 and of elements 621, 622, 623, and at the operating side another 
rod parallelogram consisting of the pivot 613 as well as elements 625, 
626, 627, for moving a shooting head 631 and an aiming device 632 in a 
conform manner. The movement is carried out by a working cylinder 633 by 
way of a control valve 628, in accordance with the force effect of the arm 
609. A support of a head casing 634 is rotatably inserted in a bore of the 
body of the shooting head 631. Rotary motion is accomplished by an 
operating cylinder 635. Its position is couled to a flexible shaft 636, 
and to an analogous shaft of the aiming device 632. A control valve 639 
attached to a tubular shaft 637 and a member for determining the 
direction, as well as a support 634, insure conform movements. 
The constructional principle of the connecting rods 618 and 628--which 
serve as pre-sensors--can be seen in FIG. 16. 
Coaxial, telescoped half-rods 640, 641 are disposed between pivots k.sub.1, 
k.sub.2, and they are interconnected by way of a linkage of a valve 642. 
The center position of the valve is insured by means of a spring. The 
linkage can be moved outwardly against the spring force or inwardly, to 
produce the appropriate valve position. 
It is an advantage of the invention that every operational step of 
supporting or ensuring roads designed for long life are fully mechanized 
to enable them to be carried out solely by machines. In this way, it 
achieves a significant reduction in the physical labor carried out under 
very difficult conditions, as well as a shortening of the required time. 
The invention also enables optimization of the utilization as well as of 
the quantity of the installed support materials because, after determining 
the parameters of the rock, it utilizes the latest rock-mechanical 
principles and can compute all road supporting parameters. The invention 
allows to select the most appropriate support construction and machine 
arrangement.