Ground compaction

Abstract

The apparatus ( 10 ) is a weighted body ( 12 ). The first regions ( 20 ) taper at a first taper angle, such as 5°. Second regions ( 22 ) taper at a greater angle, such as 60°. The ground is compacted by dropping the apparatus ( 10 ) on the ground, so that the nose ( 18 ) penetrates the ground. The relatively low taper angle of the first regions ( 20 ) tends to result in deeper penetration. The relatively high taper angle of the regions ( 22 ) tends to create some bounce on impact, helping to free any tendency for the first regions ( 20 ) to stick. The second regions ( 22 ) also create greater downward compaction.

1 . Ground compaction apparatus comprising:
 a weighted ground impact body with an outer surface which reduces in width to a nose;   the outer surface having a plurality of first regions which taper at a first taper angle, and   at least one second region between first regions, the second region tapering at a second taper angle which is greater than the first taper angle.   
   
   
       2 . Apparatus according to  claim 1 , wherein the body is generally conical. 
   
   
       3 . Apparatus according to  claim 1 , wherein the body is substantially circular in section. 
   
   
       4 . Apparatus according to  claim 1 , wherein the body is substantially polygonal in section. 
   
   
       5 . Apparatus according to  claim 4 , wherein the body is substantially hexagonal or octagonal in section. 
   
   
       6 . Apparatus according to  claim 1 , wherein the or each second region is a band around the body. 
   
   
       7 . Apparatus according to  claim 1 , wherein each first region is a band around the body. 
   
   
       8 . Apparatus according to  claim 1 , wherein at least one first region is separated from a neighbouring first region by a band providing a second region. 
   
   
       9 . Apparatus according to  claim 1 , wherein there are a plurality of second regions. 
   
   
       10 . Apparatus according to  claim 9 , wherein the spacing of second regions is non-uniform. 
   
   
       11 . Apparatus according to  claim 10 , wherein the second regions are spaced more closely nearer the nose than further from the nose. 
   
   
       12 . Apparatus according to  claim 1 , wherein the radial extent of the or each second region is substantially equal to the radial extent of a neighbouring first region. 
   
   
       13 . Apparatus according to  claim 1 , wherein the first taper angle is in the range 0° to 15°. 
   
   
       14 . Apparatus according to  claim 13 , wherein the first taper angle is substantially 5°. 
   
   
       15 . Apparatus according to  claim 1 , wherein the second taper angle is greater than 45°. 
   
   
       16 . Apparatus according to  claim 15 , wherein the second taper angle is substantially 60°. 
   
   
       17 . Apparatus according to  claim 1 , wherein the weight of the body is at least 1 tonne. 
   
   
       18 . Apparatus according to  claim 17 , wherein the weight of the body is at least 12 tonnes. 
   
   
       19 . A method of ground compaction, in which a ground compaction apparatus, the apparatus comprising a weighted ground impact body with an outer surface which reduces in width to a nose, the outer surface having a plurality of first regions which taper at a first taper angle, and at least one second region between first regions, the second region tapering at a second taper angle which is greater than the first taper angle, is dropped on the ground to be compacted. 
   
   
       20 - 22 . (canceled)