Drop mass compaction of soil

Abstract

A soil compaction apparatus includes a drop mass soil compactor having a mass and a lift assembly that repeatedly raises the mass above a soil surface and then drops it to apply impacts to the soil surface. The apparatus also has a sensor arranged to provide periodic indications of one or more instantaneous properties of the soil. The apparatus also includes a controller that received a signal from the sensor and controls the lift assembly to attain desired, pre-programmed soil properties based on a number of impacts, energy imparted to the soil at each impact or frequency if impacts of the mass.

1 . A method of compacting soil comprising: 
 repeatedly raising a mass above the soil surface and then dropping the mass to apply impacts to the soil surface;    from the impacts on the soil surface periodically deriving indications of one or more instantaneous properties of the soil; and    controlling at least one of the number of subsequent impacts, energy imparted to the soil at each impact and frequency of the impacts, in accordance with the indicated property or properties, a sensor being associated with the mass to provide the periodic indications and an output of the sensor is fed to a controller including a programmable logic controller (PLC) that is pre-programmed with one or more predetermined soil properties to be attained,    the PLC operating automatically to vary at least one of the number of impacts, the energy imparted to the soil at each impact and the frequency of the impacts to achieve the predetermined soil property or properties.    
   
   
       2 . The method according to  claim 1 , wherein indications are periodically derived of instantaneous mechanical or physical properties of the soil.  
   
   
       3 . The method according to  claim 2 , wherein the mechanical properties of the soil include at least one of the stiffness of the soil, strength of the soil and the bearing capacity of the soil.  
   
   
       4 . The method according to  claim 1 , wherein indications are periodically derived from at least one of total soil settlement and incremental soil settlement.  
   
   
       5 . The method according to  claim 1 , wherein the sensor is an accelerometer associated with the mass and the accelerometer is configured to output signals related to the deceleration of the mass at each impact to the PLC.  
   
   
       6 . A soil compaction apparatus comprising: 
 a drop mass soil compactor having a mass and means for repeatedly raising the mass above a soil surface and then dropping it to apply impacts to the soil surface; and    a control means having a programmable logic controller (PLC) which is pre-programmed with one or more predetermined soil properties to be attained and a sensor associated with the mass to provide periodic indications of one or more instantaneous properties of the soil, the PLC being arranged to respond to the indications provided by the sensor and to control at least one of a number of impacts, energy imparted to the soil at each impact and frequency of impacts of the mass, to thereby achieve in the soil the one or more predetermined soil properties.    
   
   
       7 . The apparatus according to  claim 6 , further comprising: 
 a geographical position monitor which is interfaced with the PLC to enable the control means to exercise control over the compaction of soil in accordance with a geographical plan.    
   
   
       8 . The apparatus according to  claim 7 , wherein the geographical position monitor is a global positioning system (GPS).  
   
   
       9 . The apparatus according to  claim 6 , wherein the sensor is an accelerometer arranged to output signals related to the deceleration of the mass at each impact to the PLC.  
   
   
       10 . The apparatus according to  claim 6 , wherein the apparatus is configured to be vehicle mounted.  
   
   
       11 . The apparatus according to  claim 10 , wherein the apparatus is configured to be movable from a transportation orientation in which the apparatus is carried on the vehicle to an operative position in which the apparatus is located alongside the vehicle.  
   
   
       12 . A soil compaction apparatus comprising: 
 a drop mass soil compactor having a compaction mass and a lift assembly, the lift assembly being coupled to the compaction mass and being configured to repeatedly raise the compaction mass above a soil surface and drop the compaction mass onto the soil surface;    a sensor having an output, the sensor detecting at least one of conditions of the mass and conditions of the soil; and    a controller that receives the output from the sensor and controls the lift assembly, the controller controlling at least one of a number of impacts, energy imparted on an impact and frequency of impacts of the compaction mass.