Trenching apparatus and methods of forming inground retaining walls

Abstract

A trenching apparatus (10) is for excavating deep trenches in which inground concrete retaining or foundation walls may be formed. The trenching apparatus (10) has a crawler base (11) on which a carrier assembly (14) is pivotally supported by pivots (16) whereby it may be tilted by rams (17) to maintain the platform horizontal. An automatic control device (64) is provided for this purpose. The carrier assembly (14) has a pair of rails (18/19) along which a carriage (21) may move. The carriage (21) supports a sleeve (24) through which a trenching arm (25) may be lowered to excavate a trench section as the carriage (21) is driven along the rails (18/19).

What I claim is: 
     
       1. Trenching apparatus comprising: a supporting base supported for longitudinal movement along an excavation line;   a carriage;   mounting means for mounting said carriage on said supporting base, said carriage being restrained by said mounting means for longitudinal movement along said supporting base; and   a trenching arm assembly supported by said carriage and operable to excavate a section of trench along said excavation line as said carriage moves longitudinally along said supporting base, said trenching arm assembly including a trenching arm frame, said trenching arm frame supporting opposed trench-engaging members which may be forced outwardly into engagement with the opposed side walls of a trench, and advancing means associated with said members for advancing said trenching arm frame.   
     
     
       2. Trenching apparatus according to claim 1, wherein a shield means is connected to said trenching arm assembly for containing soil pressures in the walls of the trench being excavated, said shield means providing a clear space within the trench into which reinforcement may be fed and being provided with a concrete discharge means associated with said shield means for discharging concrete into the trench behind said shield means. 
     
     
       3. Trenching apparatus according to claim 1, wherein said trenching arm assembly is pivotable about a longitudinal axis to be able to be tilted relative to said supporting base. 
     
     
       4. Trenching apparatus according to claim 3, wherein said mounting means includes a platform having longitudinally extending guide rails along which said carriage may move and being provided with drive means for moving said carriage along said guide rails. 
     
     
       5. Trenching apparatus according to claim 4, wherein said carriage is provided with supporting wheels captively engaged with said rails. 
     
     
       6. Trenching apparatus according to claim 4, wherein said platform is pivotally connected to said supporting base for pivotal movement about a longitudinal tilt axis and being provided tilting means for controlling the pivotal movement of said platform about said tilt axis. 
     
     
       7. Trenching apparatus according to claim 4, wherein a digging chain is guided about said trenching arm frame and a chain drive means drives said digging. 
     
     
       8. Trenching apparatus according to claim 7, wherein said trenching arm frame is adjustably mounted on a carrier supported by said carriage wherein a depth of excavation may be varied and being provided with a depth adjustment control means for selectively positioning said trenching arm frame relative to said carrier. 
     
     
       9. Trenching apparatus according to claim 8, wherein said trenching arm assembly is pivotally connected to said carriage for movement between a lowered trenching attitude and a raised travelling attitude. 
     
     
       10. Trenching apparatus according to claim 8, wherein said carrier is connected to said carriage for pivotal movement about a transverse pivot axis. 
     
     
       11. Trenching apparatus according to claim 7, wherein said trenching arm frame supports trenching arm advancing means remote from said carrier which is engageable with the side walls of a trench and operable to advance the trenching arm assembly. .Iadd. 
     
     
       12.  A trenching apparatus, comprising: a trenching arm assembly having an upper end and a lower end;   an above ground propulsion unit connected to said upper end of said trenching arm assembly for advancing said upper end of said trenching arm assembly along an excavation line;   digger means associated with said trenching arm assembly for initially digging said trenching arm assembly substantially vertically downwardly from ground level to a position wherein said lower end of said trenching arm assembly is located below ground; and   a below ground propulsion unit carried by said lower end of said trenching arm assembly for advancing said lower end of said trenching arm assembly, as said above ground propulsion unit advances said upper end thereof, along said excavation line. .Iaddend. .Iadd.13. A trenching method, comprising:   digging substantially vertically downwardly from ground level to a desired trench depth using a trenching arm assembly so that a below ground propulsion unit mounted to a lower end of said trenching arm assembly is located below ground level;   excavating a trench by propelling an upper end of said trenching arm assembly along an excavation line with an above ground propulsion unit, and by propelling said lower end of said trenching arm assembly along said excavation line with said below ground propulsion unit. .Iaddend. .Iadd.14. A trenching method, comprising:   digging substantially vertically downwardly from ground level to a desired trench depth using a digger mechanism associated with a trenching arm assembly so that a lower end of said trenching arm assembly is located below ground;   excavating a trench by propelling an upper end of said trenching arm assembly along a desired trench line with an above ground propulsion unit, and by propelling said lower end of said trenching arm assembly along said desired trench line with a below ground propulsion unit which is separate from said digger mechanism. .Iaddend.