Supported Underpinning Piers

Abstract

An underpinning system is provided that includes a supported underpinning pier. The underpinning pier supports a structure's foundation and may have one or more elongated support members attached thereto. The elongated support members may be micropiles, driven piles or helical piles. The underpinning pier may have a variety of configurations. In one configuration, the underpinning pier extends laterally outside of the structure's existing foundation and is attached to one or more micropiles at an exterior region of the underpinning pier, which resists the application of bending moments to the underpinning pier. A method is also provided for installing the underpinning system and/or the micropile supported underpinning pier.

1 . An underpinning system for a structure, the system comprising: 
 an underpinning pier having an upper portion engaging a foundation of the structure and receiving downward forces from the foundation, the underpinning pier having a depth less than that of a predetermined bearing stratum; and    a first elongated support member extending from a bottom portion of the underpinning pier and extending downward from the underpinning pier, the elongated support member transmitting downward forces from the underpinning pier to the predetermined bearing stratum.    
   
   
       2 . The underpinning system of  claim 1 , wherein the elongated support member is a micropile.  
   
   
       3 . The underpinning system of  claim 1 , wherein the elongated support member is a helical pier.  
   
   
       4 . The underpinning system of  claim 1 , wherein the elongated support member is a driven pile.  
   
   
       5 . The underpinning system of  claim 1 , further comprising a lateral support member installed through the underpinning pier and anchored to a portion of soil behind the underpinning pier.  
   
   
       6 . The underpinning system of  claim 1 , further comprising a vertical sleeve inserted into the underpinning pier.  
   
   
       7 . The underpinning system of  claim 1 , wherein the underpinning pier laterally extends beyond an end of the foundation of the structure.  
   
   
       8 . The underpinning system of  claim 1 , further comprising a second elongated member extending from the bottom portion.  
   
   
       9 . The underpinning system of  claim 8 , wherein the first elongated member is at a first angle and the second elongated is at a second angle, the second angle being different from the first angle.  
   
   
       10 . The underpinning system of  claim 8 , further comprising a first and second plurality of elongated support members.  
   
   
       11 . The underpinning system of  claim 1 , wherein the underpinning pier is formed of concrete.  
   
   
       12 . A method for forming an underpinning structure, the method comprising: 
 inserting one or more elongated support members in a downward direction below a foundation of a structure;    excavating an underpinning pier below the foundation to include a top portion of the one or more elongated support members;    forming an underpinning pier form within the underpinning pier excavation;    placing concrete within the underpinning pier form such that an upper portion of the concrete is proximate the foundation and a gap is formed between the upper portion of the concrete and the foundation; and    packing a filler material in the gap to form a substantially continuous structural interface between the foundation and the concrete.    
   
   
       13 . The method of  claim 12 , wherein the elongated support members include micropiles.  
   
   
       14 . The method of  claim 12 , wherein the elongated support members include helical piles.  
   
   
       15 . The method of  claim 12 , wherein the elongated support members include driven piles.  
   
   
       16 . The method of  claim 12 , wherein the step of excavating for the underpinning pier form is done after the step of inserting one or more support members and the step of placing concrete is done after the step of excavating.  
   
   
       17 . The method of  claim 12 , wherein the step of inserting one or more support members is performed after the step of excavating for the underpinning pier.  
   
   
       18 . The method of  claim 12 , wherein the step of excavating for the underpinning pier is performed first, the step of placing the concrete is done second and the step of inserting one or more support members is done third.  
   
   
       19 . The method of  claim 18 , wherein a sleeve is inserted into the underpinning pier concrete.  
   
   
       20 . An underpinning system for a structure, the system comprising: 
 an underpinning pier having an upper portion engaging a foundation feature of the structure and a lower portion below the upper portion and extending laterally away from the structure, the lower portion having a greater width than the upper portion, the underpinning pier receiving downward forces from the foundation feature; and    a plurality of elongated support members extending downward from the underpinning pier, the elongated support members transmitting downward forces from the underpinning pier into the earth at a greater depth than the underpinning pier.    
   
   
       21 . The underpinning system of  claim 20 , wherein the plurality of elongated support members are micropiles.  
   
   
       22 . The underpinning system of  claim 20 , wherein the plurality of elongated support members are helical piles.  
   
   
       23 . The underpinning system of  claim 20 , wherein the plurality of elongated support members are driven piles.