Rapid consolidation and compaction method for soil improvement of various layers of soils and intermediate geomaterials in a soil deposit

Abstract

The rapid consolidation and compaction method comprises (i) first driving a hollow pipe, (ii) driving a pipe with a removable end plate after filling and compacting the sandy material in it, through the hollow pipe, to required depth, creating high excess pore-water pressures in the range of 50 to 300 KPa in clayey soils, (iv) pulling out the pipe section leaving behind the removable end plate and thereby installing porous displacement piles which allows dissipation of the excess pore-water pressures horizontally to the porous displacement pile, in which the excess water flows out vertically to the ground surface, and (v) the length of the drainage path is reduced to half the spacing between adjoining porous displacement piles, allowing rapid consolidation resulting in increase in density. Installing the porous displacement piles in the layer of loose to medium dense sand layer results in the instantaneous increase in its density.

1 . A rapid consolidation and compaction method for densifying various layers of soils and intermediate geomaterials in a soil deposit, the rapid consolidation and compaction method comprising:
 (i) Installing porous displacement piles in at least one layer of clayey and silty soil for the rapid consolidation and densification of the at least one layer of the clayey and silty soil;   (ii) wherein installing the porous displacement piles in the at least one layer of sandy soil for instantaneous densification of the sandy soil;   (iii) wherein first driving a non-displacement pile comprising of a pipe section into ground;   (iv) wherein when the porous displacement pile is a column of compacted sandy soil, driving a displacement pile comprising the pipe section attached with a removable end plate and filled with compacted layers of the sandy soil into the at least one layer of the soil or intermediate geomaterial through inside the non-displacement pile;   (v) wherein after driving the displacement pile as described above, placing a weight or a hammer on top of the compacted sandy soil in the pipe section before pulling the pipe section out of the ground;   (vi) wherein during pulling the pipe section of the displacement pile out of the ground, the removable end plate opens 100 percent of inside area of the pipe section;   (vii) wherein during pulling the pipe section of the displacement pile, placing the weight or the hammer on top of the compacted sandy soil in the pipe section to continue to push the compacted sandy soil vertically downwards to fill the compacted sandy soil in the space previously occupied by the pipe section;   (viii) wherein placing the weight or the hammer at the top of compacted soil in the pipe section to prevent necking to form in the column of the compacted sandy soil during pulling the pipe section out of the ground;   (ix) wherein after pulling out of the pipe section of the displacement pile out of the ground, leaving the column of the compacted sandy soil in the ground;   (x) wherein an area of cross-section of the column of the compacted soil is at least equal or more than an inside area of the pipe section;   (xi) wherein the column of the compacted sandy soil left in the ground after pulling out of the pipe section, behaves as a porous displacement pile up to the depth up to which the pipe section of the displacement pile was driven;   (xii) wherein when porous displacement pile is a porous reinforced concrete pile, with or without prestress, driving the porous reinforced concrete into the at least one layer of the soil or intermediate geomaterial through inside the non-displacement pile;   (xiii) wherein when the porous displacement pile comprises of a porous pipe section with the attached end plate, driving the porous pipe section into the at least one layer of the soil or intermediate geomaterial through inside the non-displacement pile;   (xiv) wherein when the porous displacement pile comprises of the pipe section with small holes, attached with the end plate and filled with the compacted sandy soil, driving the pipe section into the at least one layer of the soil or intermediate geomaterial through inside the non-displacement pile;   (xv) wherein the porous displacement pile displaces and laterally forces the soil or the intermediate geomaterial away from the displacement pile;   (xvi) wherein the porous displacement pile occupies space previously occupied by the clayey and silty soil and develops excess pore-water pressures in saturated clayey and silty soil and the excess pore-water pressures and the excess pore-water pressures in partially saturated clayey and silty soil, by pressurizing the pore-water and air present in the pores of the saturated clayey and silty soil;   (xvii) wherein the excess pore-water pressures and pore-air pressures developed in the clayey and silty soil are rapidly dissipated by flow of the pressurized pore-water and pore-air through the porous displacement pile to the ground surface or to the sandy layer located within the ground, thereby densifying the clayey and silty soils;   (xviii) wherein the porous displacement pile occupies the space previously occupied by the sandy soil reducing volume of voids of the soil matrix and densifying the sandy soil instantaneously;   (xix) wherein in the sandy soil, the excess pore-water pressures do not develop and if develop, dissipate immediately;   (xx) wherein the porous reinforced concrete piles, the porous pipe sections with the attached end plate and the pipe sections with small holes and the attached end plate and filled with the compacted sandy soil will not require pulling the porous reinforced concrete pile and the pipe sections out of the ground;   (xxi) wherein installing a plurality of the porous displacement piles spaced apart in a grid pattern in the entire area requiring densification;   (xxii) wherein installing the porous displacement piles either vertically or at a batter.   
     
     
         2 . The rapid consolidation and compaction method for densifying the various layers of the soils and the intermediate geomaterials in the soil deposit in accordance with  claim 1 , the rapid consolidation and compaction method comprising:
 (i) wherein first driving the non-displacement pile into the ground, in order to minimize heave at the ground surface or at top of the layer to be densified;   (ii) wherein not driving the non-displacement into the ground but driving the displacement pile directly or not driving the non-displacement to adequate depth to prevent the heave, will result in less amount of densification as the soil displaced by the displacement pile will be sum of reduction of voids in the soil plus the soil which heaved at the ground surface or at the top of the layer to be densified.   
     
     
         3 . The rapid consolidation and compaction method for densifying the various layers of the soils and the intermediate geomaterials in the soil deposit in accordance with  claim 1 , the rapid consolidation and compaction method comprising:
 (i) wherein filling the sandy soil in layers and compacting each layer inside the pipe section;   (ii) wherein either compacting the sandy soil inside the pipe section at same location where the pipe section filled and compacted with the sandy soil is to be driven or at another location other than that where the pipe section filled with the compacted sandy soil is to be driven;   (iii) wherein gradation, that is particle size distribution of the compacted sandy material to be designed to allow free flow of excess pore-water for dissipating the excess pore-water pressures or the excess pore-air pressures and also to prevent migration of fine particles of in-situ soil in to it;   (iv) wherein the porous reinforced concrete piles, the porous pipe sections attached with the end plate and the pipe section with the small holes, attached with the end plate and filled by the compacted sandy soils to be used as the porous displacement piles if (1) drivable by a pile drivable hammer into the soil without exceeding allowable driving stresses, (2) allow free drainage and flow of water and also prevent migration of the fine particles of the in-situ soil, and (3) the small holes in the pipe section to be quite small for retaining the sandy soil during compaction in the pipe section.   
     
     
         4 . The rapid consolidation and compaction method for densifying the various layers of the soils and the intermediate geomaterials in the soil deposit in accordance with  claim 3 , for the method of compacting sandy soil in the pipe section, the rapid consolidation and compaction method comprising:
 (i) wherein using one of following three methods for compacting sandy soil in the pipe section;   (ii) wherein in first method, filling the sandy soil in the layers in the pipe section and compacting and densifying each layer by drops of the hammer or the weight;   (iii) wherein the hammer or the weight is connected to a boom of crane or to the pile driving hammer by means of a connecting rod connecting the weight or the hammer;   (iv) wherein in second method, filling each layer of the sandy soil in the pipe section and placing hammer or weight on the top of the sandy soil in the pipe section;   (v) wherein then attaching a surface vibrator on side of the pipe section and vibrating the pipe section to compact and densify each layer of the sandy soil inside the pipe section;   (vi) wherein in third method, filling each layer of the sandy soil in the pipe section and placing the hammer or the weight on the top of the sandy soil in the pipe section and vibrating the hammer or the weight for densifying the sandy soil inside the pipe section;   (vii) wherein using these methods, compacting the sandy soil in the pipe section to relative densities to achieve either medium dense or dense or very dense sand conditions;   (viii) wherein (a) compacting the sandy soil in the pipe section to a particular relative density and (b) spacing and diameter of the porous displacement piles in the grid pattern to depend on subsurface soil conditions at a site, and the specifications up to which subsurface soil layers to be densified at that site;   (ix) wherein the porous displacement piles with the relative density greater than the density of densified in-situ soil densified by the rapid consolidation and compaction method, works as a reinforcement to share more load of an embankment or foundation of a structure than that by the densified in-situ soil, thereby reducing the total settlement of the structure or the embankment;   (x) wherein the pipe section during compaction of the sandy soil to be laterally supported to maintain the pipe section in vertical position.   
     
     
         5 . The rapid consolidation and compaction method for densifying the various layers of the soils and the intermediate geomaterials in the soil deposit in accordance with  claim 1 , for attaching the removable end plate to the pipe section, the rapid consolidation and compaction method comprising:
 (i) wherein using one of the following three different methods to attach the removable end plate at end of the pipe section;   (ii) wherein in the first method, removable end attached to the pipe section by a hinged connection;   (iii) wherein during withdrawal of the pipe section out of the ground, bottom of the pipe section opens fully, because the removable end plate becomes vertical at the side of the hinged connection opening the bottom of the pipe section in vertical piles;   (iv) wherein for batter piles, the removable end plate with the hinged connection aligns in longitudinal direction of batter of the displacement pile, opening the bottom of the pipe section;   (v) wherein in the second method, a removable short pipe section connected to the removable end plate and then both together inserted at the end of the pipe section;   (vi) wherein as an option, the short pipe section is snug to the inside of the pipe section or the short pipe is attached to the pipe section by thin aluminum rivets which break when the pipe section is being pulled out;   (vii) wherein during the withdrawal of the pipe section out of the ground, the pipe section opens fully and the short pipe section attached to the removable end plate is left behind at the bottom of the column of the compacted soil;   (viii) wherein in the third method, the plurality of connecting rods first bolted to the removable end plate located at the bottom of the pipe section and thereafter, the connecting rods fastened at the top of the pipe section;   (ix) wherein when the pipe section filled with the compacted sandy soil has been driven in the ground, bolts at the top of the pipe section are unfastened allowing the connecting rods and the attached removable end plate to disengage with the pipe section during the withdrawal of the pipe section;   (x) wherein therefore, when the pipe section is being pulled out of the ground, the connecting rods and the removable end plate are left in the ground;   (xi) wherein for all the above cases, whichever is selected, after the pipe section has been withdrawn out of the ground, the column of the compacted sandy soil installed in the ground behaves like the porous displacement pile.   
     
     
         6 . The rapid consolidation and compaction method for densifying the various layers of the soils and the intermediate geomaterials in the soil deposit in accordance with  claim 5 , for transporting the pipe section filled by the compacted soil to another location, the rapid consolidation and compaction method comprising:
 (i) wherein when the pipe section has been filled and compacted at location other than that where it is to be driven, then for the first method, in addition of the hinged connection on one side, an angle bolted to the removable end plate and the pipe section at diametrically opposite side of the hinged connection, or at equal spaced points if more than one angle bolted to the pipe section and the removable end plate;   (ii) wherein after attaching the at least one angle to the pipe section and the removable end plate, mobilizing the pipe section filled with the compacted sandy material to the location where it is to be driven;   (iii) wherein removing the angle section or the angle sections when the pipe section transported to the location where the pipe section to be driven and when the removable end plate in contact to the ground, but not resting on it to easily pull out the angle or angles;   (iv) wherein when the pipe section has been filled and compacted at the location other than where it is to be driven, then for the second method, attaching the short pipe section to the removable end plate, and connecting to the pipe section by the plurality of the bolts to hold the compacted sandy material in the pipe section in place;   (v) wherein removing the bolts after the pipe section has been transported to the location where the pipe section to be driven and when the removable end plate in contact with the ground.