Downhole sampling method and device used in standard penetration test

Abstract

A sampling device has a closed housing, a split-barrel sampler, an anvil, a drop hammer and a lifting device. The split-barrel sampler is mounted in and extends out from the bottom end of the housing. The anvil is attached to the top of the split barrel sampler. The drop hammer is moveably mounted in the housing and is located above the anvil. The lifting device is mounted in the top end of the closed housing to lift the drop hammer to a specific height above the top of the anvil. With the sampling device, the impact energy generated by the hammer is directly transmitted to the sampler through the anvil. The impact energy lost is minimized, and the accuracy of the Standard Penetration Test result is improved.

What is claimed is:  
     
         1 . A sampling device used in a Standard Penetration Test comprising: 
 a closed housing having a top end and a bottom end;    a split-barrel sampler with a top end and a bottom end mounted in and extending out from the bottom end of the housing;    an anvil attached to the top end of the split barrel sampler;    a drop hammer moveably mounted in the housing and located above the anvil;    a lifting device mounted in the top end of the closed housing to lift the drop hammer to a specific height above the top of the anvil.    
     
     
         2 . The sampling device as claimed in  claim 1 , wherein the bottom end of the closed housing is an opening end with inner thread; and 
 a bottom cover with thread is screwed to the inner thread in the bottom end of the closed housing to close the bottom end of the closed housing,    wherein the bottom cover has a supporting base with a through hole for the split-barrel sampler penetrating through the through hole.    
     
     
         3 . The sampling device as claimed in  claim 1 , wherein the anvil has a round top face to serve as a contact face with the drop hammer.  
     
     
         4 . The sampling device as claimed in  claim 3 , wherein the drop hammer has a round bottom face to serve as a contact face with the anvil.  
     
     
         5 . The sampling device as claimed in  claim 3 , wherein the drop hammer has a flat bottom face to serve as a contact face with the anvil.  
     
     
         6 . The sampling device as claimed in  claim 1 , wherein the anvil has a flat top face to serve as a contact face with the drop hammer.  
     
     
         7 . The sampling device as claimed in  claim 6 , wherein the drop hammer has a round bottom face to serve as a contact face with the anvil.  
     
     
         8 . The sampling device as claimed in  claim 6 , wherein the drop hammer has a flat bottom face to serve as a contact face with the anvil.  
     
     
         9 . The sampling device as claimed in  claim 1 , wherein the lifting device comprises: 
 a driving device mounted in the top end of the closed housing; and    a lifting element connected to the driving device with a connecting cable and corresponding to the drop hammer to hold and lift the drop hammer.    
     
     
         10 . The sampling device as claimed in  claim 9 , wherein the lifting element is an electromagnet.  
     
     
         11 . A method of using a sampling device for a Standard Penetration Test as claimed in  claim 1 , the method comprising acts of: 
 drilling a hole in a sample of ground where the hole has a bottom at a designated depth;    setting a sampling device at the bottom of the hole;    lifting a hammer to a height of 76 cm (centimeters) above a top of an anvil with a lifting device; and free falling the hammer to impact the anvil.