Method for Embedding Rock Anchors

Abstract

According to the invention, a drill rod comprising an inner channel is drilled into the rock. A free-flowing, self-hardening mass is pressed through the inner channel of the drill rod, filling the drilled hole, so that it hardens with the drill rod remaining in the drilled hole. The hardening mass is a mixture of a hardenable plastic and a hardening plastic. Said plastics are supplied to the inner channel of the drill rod over a pre-determined transport time F which corresponds to the hardening time. The hardening time is defined by the selection of the plastics and the mixing ratio thereof such that the transport time essentially corresponds to the hardening time and leads essentially to the flow path of the hardened mixture being completely filled between the mixing point and the output of the drilled hole.

1 - 19 . (canceled)  
   
   
       20 . Method for embedding rock anchors, whereby an anchor rod having an internal passage is inserted in a drilled hole, through which internal passage a free-flowing, self-curing composition is forced, the finished drilled hole is filled with the composition and the composition cures in the drilled hole with the anchor rod remaining in the drilled hole, characterised in that 
 the curable composition is made from a mixture of a hardenable plastics material and a hardening plastics material;    the hardenable plastics material and the hardening plastics material are fed in a mixed state to the internal passage of the drill rod for a predetermined feed time F;    the plastics materials are so selected and brought together, at a mixing point located shortly before or in the internal passage, and are mixed to form the mixture in such a mixing ratio as to yield a defined curing time H, the feed time F and the curing time H being so coordinated to one another that the feed time substantially corresponds to the curing time and leads to substantially complete filling with the curable mixture of the flow path between the mixing point and the outlet of the drilled hole.    
   
   
       21 . Method according to  claim 20 , characterised in that the internal passage and the drilled hole are flushed with air during and/or after the drilling, and in any case prior to the introduction of the curable mixture.  
   
   
       22 . Method according to  claim 20 , characterised in that the mixer is arranged in the internal passage.  
   
   
       23 . Method according to  claim 20 , characterised in that the mixer is a static mixer arranged upstream of the internal passage.  
   
   
       24 . Method according to  claim 20 , characterised in that the viscosity of the curable mixture in the curing time is at least 100 000 Pa sec.  
   
   
       25 . Method according to  claim 20 , characterised in that the curable mixture hardens to such a degree during the curing time that the torque of the drill rod in the drilled hole is greater than the torque required to detach the drill rod from the drill chuck retaining same.  
   
   
       26 . Method according to  claim 20 , characterised in that a substance or synthetic material which causes pre-crosslinking of the components, with an increase in viscosity to more than 500 Pa sec, preferably more than 1000 Pa sec, within and preferably at the start of the curing time, is admixed to the curable mixture or to one of its components.  
   
   
       27 . Method according to  claim 20 , characterised in that the inlet of the internal passage of the drill rod is blocked by a non-return valve which is open in the filling direction.  
   
   
       28 . Method according to  claim 20 , characterised in that the hardenable and the hardening plastics materials are conveyed at a pressure-independent feed quantity per time unit during the feed time F.  
   
   
       29 . Method according to  claim 20 , characterised in that the supply of plastics materials, and optionally of admixtures, is switched off or otherwise terminated if a predefined limit pressure is exceeded.  
   
   
       30 . Method according to  claim 20 , characterised in that, taking account of the characteristic curve of the feed rate of the hardenable and hardening plastics materials, the filling time for the filling volume V to be filled downstream of the mixing point conforms to the equation:  
         V=kx   0 ƒ H ( q   A   +q   H ) dt , where  V=filling volume of internal passage downstream of mixing point plus filling volume of drilled hole    q A =feed quantity per time unit of hardenable plastics material    q H =feed quantity per time unit of hardening plastics material    dt=time increment    H=curing time    K=constant taking account of location-independent factors, in particular temperature and constitution of rock.    
   
   
       31 . Method according to  claim 20 , characterised in that the plastics components are fed through an injection head (adapter  11 ) 
 which is permanently connected via conduits to the feed pumps of the plastics components carried on a transport vehicle (drilling carriage);    which is guided movably between a rest position and an operating position on the drilling carriage, and    which in the operating position is connectable in a pressure-sealed manner via a connecting piece to the end of the anchor rod projecting from the drilled hole.    
   
   
       32 . Method according to  claim 31 , characterised in that 
 a stop valve for closing and opening the feed conduit is located in each of the feed conduits of the plastics components within the injection head;    both stop valves can be opened and/or closed only synchronously in normal operation, and    preferably the drive motors of the pumps can each be switched off by means of a pressure sensor located in its respective feed conduit upon attainment of a predefined maximum pressure.    
   
   
       33 . Method according to  claim 31 , characterised in that the plastics conduits formed in the injection head and connected to hoses on the feed side open, on the side facing towards the connecting piece (connection side of the connecting piece), into a smooth, preferably flat surface which preferably can be flushed by a high-pressure jet, preferably a water jet, upon uncoupling of the connecting piece.  
   
   
       34 . Method according to  claim 31 , characterised in that the connecting piece consists of two half-shells which are movable relative to one another perpendicularly to the flow direction of the plastics materials conducted in the interior thereof and which in the assembled state enclose in a pressure-sealed manner, or otherwise connect, the injection head on one side and the end of the anchor rod projecting from the drilled hole on the other.  
   
   
       35 . Method according to  claim 31 , characterised in that the feed conduits of the plastics materials are conducted separately from one another in the injection head and in that the plastics materials are brought together in the connecting piece.  
   
   
       36 . Method according to  claim 35 , characterised in that the static mixer is arranged in the internal passage of the anchor rod.  
   
   
       37 . Method according to  claim 35 , characterised in that the static mixer is arranged in the connecting piece.  
   
   
       38 . Method according to  claim 37 , characterised in that the static mixer has a tubular configuration with mixing elements arranged in its mixing tube and preferably is surrounded by a plastics tube, in that the half-shells of the connecting piece form in the assembled state a guide passage fitting snugly around the mixing tube, in which guide passage the mixing tube is fixed at both ends in a preferably form-fitting but easily detachable manner for support against the inlet pressure of the plastics materials entering the mixer.