Method for strengthening soils and operating vehicle usable in the method

Abstract

A method for strengthening soils comprising: a step of making in the soil ( 1 ) a hole ( 2 ) that has a main line of extension which is at least mainly vertical; 5 a driving step wherein a micro-pile ( 11 ) is driven into the soil ( 1 ) at the hole ( 2 ); and a step of filling the hole ( 2 ) with a solidifiable material or with a compactable solid granular material; wherein the step of making the hole ( 2 ) in the soil ( 1 ) comprises an inserting step wherein a punch ( 4 ) is inserted in the soil ( 1 ) by applying a pressure to the punch, the punch comprising a lower tip ( 5 ) insertable in the soil ( 1 ), a top portion ( 6 ) opposite to the lower tip ( 5 ), an axis of extension that extends between the top portion ( 6 ) and the lower tip ( 5 ) and a cross-section that increases along the axis of extension going away from the lower tip ( 5 ), and 5 wherein the step of inserting the punch ( 4 ) in the soil ( 1 ) also causes compression and compacting of the soil ( 1 ) surrounding the hole ( 2 ).

1 . A method for strengthening soils comprising:
 a step of making in the soil ( 1 ) a hole ( 2 ) that has a main line of extension which is at least mainly vertical; and   a step of filling the hole ( 2 ) with a solidifiable material;   
       wherein the step of making the hole ( 2 ) in the soil ( 1 ) comprises making a hole ( 2 ) with a cross-section transversal to the main line of extension, that decreases from top to bottom, and wherein the step of making the hole ( 2 ) in the soil ( 1 ) comprises an inserting step wherein a punch ( 4 ) is inserted in the soil ( 1 ) by applying a pressure to the punch, the punch comprising a lower tip ( 5 ) insertable in the soil ( 1 ), a top portion ( 6 ) opposite to the lower tip ( 5 ), an axis of extension that extends between the top portion ( 6 ) and the lower tip ( 5 ) and a cross-section that increases along the axis of extension going away from the lower tip ( 5 ), wherein the inserting step is performed by positioning the axis of extension of the punch ( 4 ) substantially parallel to the main line of extension of the hole ( 2 ) to be obtained, and wherein the step of inserting the punch ( 4 ) in the soil ( 1 ) also causes compression and compacting of the soil ( 1 ) surrounding the hole ( 2 ); 
       characterised in that it also comprises, after the step of making a hole ( 2 ) in the soil ( 1 ) and before the step of filling the hole ( 2 ), a driving step wherein a micro-pile ( 11 ) is driven into the soil ( 1 ) at the hole ( 2 ). 
     
     
         2 . The method according to  claim 1 , characterised in that the step of inserting the punch ( 4 ) in the soil ( 1 ) is performed without removing material from the soil ( 1 ). 
     
     
         3 . The method according to  claim 1 , characterised in that the step of inserting the punch ( 4 ) in the soil ( 1 ) is preceded by a step of making a pilot hole in the soil ( 1 ) which is smaller than the hole ( 2 ) to be made and in that the step of inserting the punch ( 4 ) in the soil ( 1 ) is performed by inserting the punch ( 4 ) in the pilot hole in order to widen it. 
     
     
         4 . The method according to  claim 1 , characterised in that the step of inserting the punch ( 4 ) in the soil ( 1 ) is performed by applying pressure, using a first actuating device ( 8 ) that is fixed to a first ballasted body ( 9 ). 
     
     
         5 . The method according to  claim 1 , characterised in that the step of inserting the punch ( 4 ) in the soil ( 1 ) is performed using a punch ( 4 ) with a cross-section that, going away from the lower tip ( 5 ), continuously increases along the axis of extension or a punch ( 4 ) having a plurality of stretches ( 7 ) with constant cross-section that are aligned along the axis of extension where the cross-section of each stretch ( 7 ) is greater than cross-sections of the stretches ( 7 ) closer to the lower tip ( 5 ) and is less than cross-sections of the stretches ( 7 ) further from the lower tip ( 5 ). 
     
     
         6 . The method according to  claim 1 , characterised in that the micro-pile ( 11 ) is driven into the soil ( 1 ) with its longitudinal axis substantially coinciding with the main line of extension of the hole ( 2 ). 
     
     
         7 . The method according to  claim 1 , characterised in that the step of filling the hole ( 2 ) is performed by embedding an upper portion ( 14 ) of the micro-pile ( 11 ) positioned inside the hole ( 2 ) and using a solidifiable material. 
     
     
         8 . The method according to  claim 1 , characterised in that the step of driving the micro-pile ( 11 ) is performed by applying pressure, using a second actuating device ( 12 ) that is fixed to a second ballasted body ( 13 ). 
     
     
         9 . The method according to  claim 8 , characterised in that during the driving step the micro-pile ( 11 ) is also made to rotate about its own longitudinal axis thereby achieving pressing-rotating driving of the micro-pile ( 11 ) into the soil ( 1 ). 
     
     
         10 . The method according to  claim 1 , characterised in that the step of inserting the punch ( 4 ) in the soil ( 1 ) is performed in such a way as to bring the lower tip ( 5 ) of the punch ( 4 ) to a depth of at least 2 m. 
     
     
         11 . An operating vehicle usable in the method according to  claim 1 , comprising:
 a chassis ( 15 );   a movement system for moving the vehicle on a soil ( 1 );   at least one driving apparatus ( 18 ) for driving a micro-pile into the soil ( 1 ); and   at least one punching device ( 19 ) for punching the soil ( 1 ) in order to make a hole ( 2 ) in the soil ( 1 );   
       wherein:
 the punching device ( 19 ) in turn comprises a first member ( 21 ), and second member ( 22 ) and a first actuating device ( 8 ); 
 the first member ( 21 ) is constrained to the chassis ( 15 ); 
 the second member ( 22 ) is movable relative to the first member ( 21 ) between a first position and a second position along a punching line; 
 the second member ( 22 ) has the shape of a punch ( 4 ) with an axis of extension that extends between a lower tip ( 5 ), insertable in the soil ( 1 ), and a top portion ( 6 ); 
 the second member ( 22 ) has a cross-section that increases along the axis of extension, going away from the lower tip ( 5 ); 
 the first actuating device ( 8 ) is mounted between the first member ( 21 ) and the second member ( 22 ) for moving the second member ( 22 ) relative to the first member ( 21 ); 
 the movement of the second member ( 22 ) comprising an outward stroke towards the second position, during which the first actuating device ( 8 ) pushes the second member ( 22 ) towards the soil ( 1 ), applying a force on the second member ( 22 ) along the driving line, the second member ( 22 ) being designed to apply a portion of said force to the soil ( 1 ) according to a radial line of action; 
 the movement of the second member ( 22 ) also comprising a return stroke towards the first position, during which the second member ( 22 ) is moved away from the soil ( 1 ), 
 
       and wherein:
 each driving apparatus ( 18 ) comprises a third member ( 23 ) that is constrained to the chassis ( 15 ), a fourth member ( 25 ) that is movable relative to the third member ( 23 ) between a first position and a second position along a driving line and a second actuating device ( 12 ) for moving the fourth member ( 25 ) relative to the third member ( 23 ); 
 the movement of the fourth member ( 25 ) comprising an outward stroke towards the second position, during which the second actuating device ( 12 ) pushes the fourth member ( 25 ) towards the soil ( 1 ), applying a force on the fourth member ( 25 ) along the driving line, the fourth member ( 25 ) being designed to transmit said force to the micro-pile to be driven in; 
 the movement of the fourth member ( 25 ) also comprising a return stroke towards the first position, during which the fourth member ( 25 ) is moved away from the soil ( 1 ). 
 
     
     
         12 . The operating vehicle according to  claim 11 , also comprising a second driving apparatus for driving a second micro-pile into the soil ( 1 ).