Soil stabilization and pile formation method

Abstract

A method of forming a grouted pile member in unstable soil involves introducing a pile member into a soil region having an N penetration value of between 2 and 11. Grout is introduced through the pile member under pressure and forms a column generally below the pile member. The pile member may, optionally, then be lowered into the grouted material.

1 . A method of securing a pile member in unstable soil, comprising the steps of: 
 a) introducing a first tubular pile member having a terminating end into a region of unstable soil having an N penetration value of between 2 and 11; and    b) pumping cement-based grout through said tubular pile member and into said unstable soil region, said grout forming a grout mass below the tubular member.    
   
   
       2 . A method according to  claim 1 , further comprising the step of: 
 c) lowering said pile member into said grout mass.    
   
   
       3 . A method of securing a pile member in unstable soil, comprising the steps of: 
 a) introducing a first tubular pile member into an unstable soil region such that said pile member terminates at an end positioned within the unstable soil region, the unstable soil region having an N penetration value of between 2 and 11;    b) introducing a second tubular member inside of said first tubular pile member, and inserting it deeply enough that its terminating end is positioned below the terminating end of said first tubular member;    c) introducing cement-based grout under controlled pressure;    d) withdrawing said second tubular member as grout is pumped therethrough, yielding a generally columnar grout formation that is generally in vertical alignment with and substantially below said first tubular member; and    e) lowering said pile member into said grouted material.    
   
   
       3 . A method of securing a pile member in an unstable soil region, comprising the steps of: 
 a) introducing a first tubular pile member into an unstable soil region such that said pile member terminates at an end positioned within the unstable soil region, the unstable soil region having an N penetration value of between 2 and 11;    b) pumping cement-based grout under controlled pressure through said tubular pile member and into the semi-stable material in said second layer, said grout forming a grout mass below the tubular member;    whereby said pile member is secured without excavating any soil material, but rather soil material is consolidated by the introduction of grout material introduced under controlled pressure.    
   
   
       4 . A method according to  claim 3 , further comprising the step of: 
 c) lowering said pile member into said grout mass;    
   
   
       5 . A method of securing a pile member in unstable soil comprising the steps of: 
 a) introducing a first tubular pile member such that said pile member terminates at an end positioned within an unstable soil region characterized by an N penetration value of between 2 and 11;    b) introducing a second tubular member inside of said first tubular pile member, and inserting it deeply enough that its terminating end is positioned below the terminating end of said first tubular member;    c) introducing cement-based grout under controlled pressure through said second tubular member;    d) withdrawing said second tubular member as grout is pumped therethrough, yielding a generally columnar grout formation that is generally in vertical alignment with and substantially below said first tubular member; and    e) lowering said pile member into said grouted grout formation;    whereby said pile member is secured without excavating any soil material, but rather soil material is consolidated by the introduction of grout material introduced under controlled pressure.