AU2013311263A1 - Plated pile for wet terrain or mud which can stand in stable position and needs no bedrock to rest on - Google Patents

Abstract

Pile (1) made of steel pipe (1), wherein this pile (1) is equipped with a steel plate (2) of at least 1.20 m diameter and 16 mm thickness welded at a point spaced one-third of the entire length from the upper end of the pile (1) for retaining and ceasing of the downward movement of the pile (1) as well as stabilizing its upright position in mud or wet terrain. The distance of one-third of the entire length of the pile (1) from the upper end of the pile (1) is the same as the length of torque arm of the total hydrostatic force acting on the pile (1) with respect to the center of the mass of the pile (1). This equivalent balancing torque enables the pile (1) to sturdily stand upright in a stable position in mud or wet terrain.

Description

WO 2014/037928 PCT/ID2013/000006 Description PLATED PILE FOR WET TERRAIN OR MUD WHICH CAN STAND IN STABLE POSITION AND NEEDS NO BEDROCK TO REST ON 5 Technical Field of Invention This invention relates to a pile having been improved in accordance with fluid mechanics and hydrodynamics 10 principles by welding a steel plate of specified radius at a point one-third of the entire length of the pile from its upper end so that the pile can sturdily stand in a stable upright position in mud or wet terrain, needs no bedrock to rest on, can bear a load of relatively large amount and 15 resistant to earthquake due to its ability of vibrating in a damped pattern when its equilibrium is disturbed. Background of Invention 20 In the previous pile technology, the deeper the bedrock seats in a wet terrain or mud, the longer or the more the piles needed to reach the bedrock. After reaching the bedrock, the piles were then impacted in order to be tightly embedded into the bedrock. However, despite a hard effort, 25 high operational costs, energies and times, the risk that the pile will collapse is likely still high enough in this kind of work. The pile currently invented is designed in such a way based on fluid mechanics and hydrodynamics principles so 30 that when applied in mud or wet terrain, it needs no bedrock to rest on so that only a small number of steel pipes (component of pile) are needed in order to let it sturdily stand upright in an extremely stable position in the mud. The pile can stand upright in stable position as it is 35 retained by a relatively great restoration force due to the action of surface of the steel plate welded at a point spaced at a predetermined distance above the center of gravity of the pile. Torque of the restoration force with WO 2014/037928 PCT/ID2013/000006 2 respect to center of gravity of the pile is the same as torque of the total hydrostatic force exerted by mud on the pile with respect to the center of gravity of the pile. The distance from the welded steel plate to the upper end of the 5 pile is one-third (12 m) of the entire length of the pile (H) . This distance is the same as that between the center of the total hydrostatic force working on the file and the lower end of the pile. Other advantages of this currently invented pile are 10 its high capacity to support load, and earthquake-resistant for being able to oscillate for a few seconds before ceasing (damped harmonic oscillation) when earthquake or dislocation takes place in the working area. Forces working on the pile are respectively gravity 15 (Fw), Newtonian buoyancy (FB) , friction force due to viscosity of the medium (Fj)and resistant force given by the surface of the circular steel plate (F,). Brief Description of The Invention 20 This invention is aimed at minimizing the number of piles used in mud or wet terrain, maximizing pile's capacity of a pile to bear load, increasing pile's stability and enabling the pile to be installed within mud or wet terrain 25 having no bedrock in it or having bedrock but of deeply seated location. Brief Description of The Drawings 30 Figure 1 is a vertical cross-section of the pile according this invention. Figure 2 is a vertical cross-section of a part of the pile according to this invention where the steel plate is welded and bracketed for reinforcement. 35 Figure 3 is a plan view of the steel plate welded on the pile after the steel plate is reinforced with bracket. Figure 4 is the pile with a steel plate welded on it when lowered into mud or wet terrain.

WO 2014/037928 PCT/ID2013/000006 3 Description of The Embodiment Pile according to this invention (1) is made of steel pipe and equipped by welding with a steel plate (2) of 0.60 5 m radius (R,) at a point spaced 1/3 H or 12 m from the upper end of the pile. The distance of 1/3 H (12 m) from the upper end of the pile is the same as the distance from the lower end of the pile to the center of the total hydrostatic force acting on the pile. This equivalent length of torque arm 10 enables the pile to stand sturdily upright (not inclined) in extra stable position in the mud or wet terrain after being equipped with a steel plate. The steel plate is of 1.6 cm (16 mm) thickness. To make the steel plate fixed tightly in the pile, it is reinforced with bracket (3) in the form 15 of four rectangular steel plates with curved upper edges separated 90 degrees each other on the plate and extend 47.5 cm both in vertical and radial direction, respectively (a in Fig. 2). The advantage of the pile presently invented is 20 unveiled through fluids mechanics and dynamics principles using Fig. 4 as a reference. It is shown in Fig. 4 the pile according to this invention equipped with a steel plate welded on it at a point spaced 12 m (h) from the upper end of the pile. 25 The length of the pile is H (36 m). First the pile is lowered into the mud until a depth of (H-h) meter where the plate is welded. The pile is then impacted or let freely move into the depth of y meter from the steel plate following the resultant force working on it. The mud has a 30 density of pLkg/m 3 and viscosity of p Pascal.second (Poise). Mass of the pile added with that of the load is m kg, radius of the pile is R m, radius of the steel plate is R, m and gravitation acceleration is g m/second 2 Forces acting on the pile are respectively gravity 35 (F,) , Newton's buoyancy force (FB) , friction force due to the viscosity of the mud (F) and retaining force given by the plate- (Fp) .

WO 2014/037928 PCT/1D2013/000006 4 Fw= mg, FR = R 2 (H - h + y)p_ g, F= pd [ 2 R(n- h + y) udy 5 F,. = 7C(R 2 - R 2 )PgY. Resultant force that moves the pile downward =F-B-V FP. 10 d--~ = 2g ~(H - h + y)p,g - 27rRu~ dff7(R 2 R R 2 )pgy mndj2 + 2 7rR~u-+ 7rp, g(RP 2R2) y =Mg _ 7R 2 (-h)p~g (2 7Ri) 2 - 4m~rpg(R P2 - 2R 2) < 0. 15 Solution to this differential equation is y(t) e"P'(A cos Qt+ B sin Qt) + in- 7CR 2H - h) p, 7rp,(R 2 - 2R') 20t e~- e'[(BP - A Q) sin Qt±+ (AP±+ BQ) cosgQt] where = - Rp 25 Q= I V7rp,.mg(R2 -2R 2)+ f2 R 2Y2 =tU, A= i- R 2 (1[- h)pL] ffp,(Rp,2 -2R 2 30 Rp4m- rR2(H- h)p,] 30 ~~p,(RP2 - 2R 2 )Vipmg(Rp2 - 2R')+ ;T 2 R 2 2 When t = 0, y(t) = 0 and V(t) = 0. 35 WO 2014/037928 PCT/ID2013/000006 5 When t= ~ (indefinite), m-)R 2 (H- h)pL y rpL(R|-2R) 5 and V(t) =0. Y(t) and v(t) show that the pile oscillates in damped harmonic pattern in the mud or wet terrain due to the 10 viscosity of the mud of p Pascal.second (Poise). The velocity of the pile gets reduced through times and lower and finally ceases in a depth of d = (H- h) +y 15 =(H- h)+ m- RR 2 (H- h)pL 1ePL(R, -2R) The length of the pile left stand upright above the mud surface is H - ym = 12- ymor 20 M- cR2 (H- hpL) 12 pL R,2 - 2R) Frequency (f) and oscillation period (T) of the pile are respectively 25 f - 1 * pLmg(R 2 - 2R 2 ) + R 2

P

2 2nm 30 T -cpLmg(RP2 - 2R 2 )+2 R 2i 2 * This theory matches the facts encountered in the field, i.e., the pile presently invented does not need a bedrock 35 to rest on in the mud or wet terrain, and 2) the load a pile can bear is relatively very large. If the maximum load a pile can bear is Mm kg and the mass of the pile is MT kg (so m = MT + MM) , Mm can easily be WO 2014/037928 PCT/ID2013/000006 6 calculated from the following equation. (M7 + M)- IFR 2 (H- h)pL WcpL(R| - 2R2) 5 MM =12rp(RP 2 -2R 2 )+ 7rR 2 (H- h)pL - MT. As an illustration, (not to limit the scope of invention) , a pile made of steel pipe having density of 7.86 x 10' kg/m 3 , length of 36 m, outer radius of 0.125 m and 10 thickness of 0.016 m (mass of the pile, MT , 3326.523 kg) and equipped with a steel plate having radius of R, = 0.60 m, is applied in mud of 2.5 x 103 kg/M 3 density (p) . The maximum load the pile can bear is (Mm) 30.58 tons. If the same pile is not equipped with steel plate cited 15 above, the differential equation of the pile motion in the mud will be given in the next page. 20 25 30 WO 2014/037928 PCT/ID2013/000006 7 5 d 2 y dy 2 m dt 2 +2fRu - pigRy=mg-7rR 2 (H- h)pg 10 (21rRp) 2 + 4m(7rpegR 2 )> 0. {m->RH-pi y(t) = C C 2 e"' - 7 R 2 (H2 h)p, ;TPLR 15 v(t) = n Ce"' + n2C2e" dengan n, = - (+ (rRj)2 + =zmp'gR2 m m 20 C rROp5['±m -nR 2( H -h)pi] n ti(rR) 2 nmpgR - trL 7rRP p (rRp)2 + npigR 2 n2 = - m m 25

C

2 = 05 1 - (ff rRp M- m rR2(H - h)pL VorRp)2 + npLgR 2 rj R 30 Y(t) dan v(t) show that when t = 0, then y = 0, v = 0, and when t = (indefinite), then y is indefinite and v is indefinite. This means that after being lowered or imbedded 35 into the mud or wet terrain, pile equipped with no steel plate will undergo a downward accelerated motion until the depth of no end (sinking). This downward motion will cease if the pile reaches a bedrock that possibly seats in the WO 2014/037928 PCT/ID2013/000006 8 mud. If the bedrock seats deep below the surface, a great number of piles are needed to reach the bedrock. This is one of the advantage belonging to the prior arts. It is the solution to this drawback and inefficiency this invention 5 tries to give. 10 15 20 25 30 35

Claims (2)

1. A pile made of steel pipe suitable for the application in mud or wet terrain, the pile needs no bedrock to 5 rest on, can bear a load of relatively large amount, will never collapse or be inclined in position and resistant to earthquake due to its ability of vibrating in a damped pattern when its equilibrium is disturbed, characterized by a steel plate of at least 10 1.20 m diameter and 16 mm thickness welded at a point spaced one-third of the entire length from the upper end of the pile for retaining and ceasing of the downward movement of the pile as well as stabilizing its upright position in mud or wet terrain. 15

2. The use of plated pile disclosed in Claim 1 20 25 30 35