Method for Improving an Inwards Stability of a Levee

Abstract

A method for improving an inwards stability of an existing levee including a landslide slope ( 128 ) and at least one of a landside berm ( 132 ), a landside heel, and a landside trench. The method comprises placing columns ( 160 ) through the landside berm into one or more soft soil layers ( 40 ) with corresponding soil volumetric weights (γs), wherein the columns have a column volumetric weight (γc) that is at least 10% larger than the soil volumetric weights, and wherein the columns comprise a mineral aggregate and an impermeable filler.

What is claimed is: 
     
         1 . A method for improving an inwards stability of an existing levee including a landside slope and at least one of a landside berm, a landside heel, and a landside trench, wherein the method comprises:
 placing columns through at least one of the landside berm, the landside heel, and the landside trench into one or more soft soil layers with corresponding soil volumetric weights, wherein the columns have a column volumetric weight that is larger than the soil volumetric weights, and wherein the columns comprise a mineral aggregate and an impermeable filler.   
     
     
         2 . The method according to  claim 1 , wherein the column volumetric weight of the columns is at least 10% larger than the soil volumetric weights of the one or more soft soil layers. 
     
     
         3 . The method according to  claim 1 , wherein the impermeable filler comprises a hydraulic binding agent. 
     
     
         4 . The method according to  claim 1 , comprising:
 determining a slip surface of most probable sliding fault for the landside slope and the landside berm;   partitioning the slip surface into a torque inducing portion related to the crown of the levee and a torque resisting portion related to the landside berm;   
       wherein placing the columns involves arranging the columns in the one or more soft soil layers at the torque resisting portion. 
     
     
         5 . The method according to  claim 1 , comprising:
 forming the columns with a first column portion having a first column diameter in an upper soil layer, and with a second column portion having a second column diameter in the one or more underlying soil layers, wherein the second column diameter is larger than the first column diameter.   
     
     
         6 . The method according to  claim 5 , wherein the second column diameter is at least 30% larger than the first column diameter. 
     
     
         7 . The method according to  claim 1 , wherein the columns are placed through at least one of the landside berm, the landside heel, and the landside trench, and into the one or more soft soil layers by means of a depth vibrator. 
     
     
         8 . The method according to  claim 7 , comprising:
 drilling a first void portion and removing soil from the upper soil layer, prior to placing the columns through at least one of the landside berm, the landside heel, and the landside trench into the one or more soft soil layers with the depth vibrator.   
     
     
         9 . The method according to  claim 1 , wherein placing the columns comprises arranging at least two columns at transversally consecutive positions across the landside berm. 
     
     
         10 . The method according to  claim 1 , comprising:
 placing the columns with a predominantly vertical orientation in the one or more soft soil layers.   
     
     
         11 . The method according to  claim 1 , comprising:
 placing the columns in a spatially separated distribution in the one or more soft soil layers.   
     
     
         12 . The method according to  claim 11 , comprising:
 placing the columns with mutual spacing with a value in a range of 0.5 meter to 2.5 meter, preferably with mutual spacing in a range of 1.0 meter to 2.0 meter, and more preferably of about 1.5 meter.   
     
     
         13 . The method according to  claim 1 , wherein the columns comprise further fillers for adapting at least one of the rheological properties, the strength properties, or the hardening properties of the columns. 
     
     
         14 . The method according to  claim 1 , wherein a supporting sand layer is situated underneath the soft soil layers, wherein the columns are arranged so as to extend through the one or more soft soil layers into the supporting sand layer, and wherein the columns comprise reinforcing material for increasing a strength and/or stability of the columns. 
     
     
         15 . The method according to  claim 14 , wherein the reinforcing material comprises fiber materials. 
     
     
         16 . The method according to  claim 14 , wherein the reinforcing material comprises a geo textile for enveloping the columns, and wherein the method comprises:
 placing the geo textile prior to placing the columns.   
     
     
         17 . The method according to  claim 14 , wherein the reinforcing material is formed into steel rods, and wherein the method comprises:
 inserting the steel rods into the columns after placing the columns.   
     
     
         18 . A method for improving an inwards stability of an existing levee including a landside slope and at least one selected from a group consisting of a landside berm, a landside heel, and a landside trench, wherein the method comprises:
 placing columns through at least one selected from the group consisting of the landside berm, the landside heel, and the landside trench, into one or more underlying soft soil layers with corresponding soil volumetric weights, wherein the columns have a column volumetric weight that is at least 10% larger than the soil volumetric weights, and wherein the columns comprise a mineral aggregate and an impermeable filler.   forming the columns with a first column portion having a first column diameter in an upper soil layer, and with a second column portion having a second column diameter in the one or more underlying soil layers, wherein the second column diameter is at least 30% larger than the first column diameter.