CN1908324A - Artificial bedding pile stabilization process for rock-embedded pile construction in deep-water bare bedrock - Google Patents

Abstract

The invention relates to an artificial base stabilizing technique of deep-water expose base rock embedded post, wherein said stabilizing technique comprises: it forms artificial base at the thickness as Y and the edge slope as X via packing sands and stones with bags at the exposed base rock, while Y should be higher than the minimum soil-embed depth of post base; then pouring bagged stones at its bottom, top and around edge, at 1-3m thickness; and the thickness of bagged sand or soil at the middle layer, S=Y-the thickness of around bagged stone as 2-6m; the incline degree of slope is 1:2-1:3. Compared with present technique, the invention has short time, lower cost and high quality.

Description

The deep-water bare basement rock socketed pile steady stake of the artificial bedding technology of constructing

Technical field

The invention belongs to the pile foundation Foundation Design technology in the building field, adopt the steady stake technology of artificial bedding during pile foundation constructions such as especially a kind of harbour that is used for deep-water bare basement rock environment, bridge.

Background technology

Building foundation engineering is the foundation of building, pile foundation is again the base form that all kinds of buildings often adopt, for Important Project projects such as harbour, bridges, owing to influenced by sea-floor relief, basement rock buries more shallow or exposed substantially, is not enough to form the stable geological conditions of pile foundation.Carry out the socketed pile construction at above-mentioned exposed basement rock, must adopt steady stake measure, with the homeostasis that satisfies pile foundation (stake or sleeve pipe), the condition of carrying out follow-up construction.Proposing reference scheme in existing " port works socketed pile design and construction rules " is: adopt the steel bar concrete casing is installed on basement rock, fill out medium coarse sand in the casing and shake towards closely knit, as the anchor spike measure, pile foundation sets in casing.Though this measure has example, with this technology have that operation is many, complex process, diving operation amount be big, long in time limit, must rely on defectives such as main equipment, and cost is higher.

Summary of the invention

The present invention is directed to above-mentioned the deficiencies in the prior art and defective, for a kind of artificial bedding of deep-water bare basement rock socketed pile constructing structure to satisfy the homeostasis of pile foundation, guarantee that safety carries out the condition of follow-up embedding rock construction.

For achieving the above object, the technical solution used in the present invention is: this deep-water bare basement rock socketed pile steady stake of artificial bedding technology of constructing is meant in exposed basement rock (or covering layer is thinner) zone with throwing the artificial bedding of filling out packed rubble, packed sand or earth formation certain thickness Y and gradient X.The thickness Y of this artificial bedding should be greater than the minimum embedded depth of pile, and the minimum embedded depth h of pile calculates according to relevant external force; The bottom of artificial bedding, top layer and outer peripheral edge surface layer are thrown and are filled out packed rubble, and the intermediate layer of artificial bedding is thrown to fill out and established packed sand or earth.The outer surface layer of described artificial bedding is thrown about 1～3 meter of thickness filling out packed rubble, and the artificial thickness of subgrade bed Y-2 of the thickness S=of intermediate layer packed sand throwing and filling or earth is the thickness of packed rubble doubly; The side slope degree X of artificial bedding is about 1: 2～and 1: 3, the top line of artificial bedding should be greater than 2～2.5 times of stakes directly apart from B with pile center's line.

The present invention is with throwing the steady stake technology that packed rubble, packed sand or earth form artificial bedding of filling out, substitute the steady stake of original concrete casing technology, both simple and easy to do, reduction of erection time, it is also relatively low to improve workmanship, cost again, can save considerable engineering cost, being situated between has determined builds the technical barrier of the pile foundation construction of large pier, bridge or offshore platform on the thin ground of deep-water bare basement rock or covering layer.

Description of drawings

Fig. 1 is the artificial bedding cross-sectional drawing of the present invention.

Fig. 2 is a calculation diagram of the present invention.

When Fig. 3 is the wave current coexistence of Fig. 2, C _D, C _MWith (KC) _PGraph of a relation.

η when Fig. 4 is ω t=0 a ° of Fig. 2 _MaxValue.

Fig. 5 is the construction sequence schematic diagram of the artificial bedding of the present invention.

The specific embodiment

Shown in Figure 1, this deep-water bare basement rock socketed pile steady stake of artificial bedding technology of constructing is meant with throwing and fills out packed rubble 1, packed sand or the earth 2 artificial bedding with formation thickness Y and side slope X.Because after pile foundation (piling bar or other preformed pile or sleeve pipe) set, current and wave were bigger to pile foundation stabilizing influence, need advanced line stabilization calculating, find the solution the minimum underground layer degree of depth h of pile, thereby determine the artificial thickness of subgrade bed Y of the present invention.

The shape end face of artificial bedding is little, the bottom is big, and the top line of artificial bedding should be greater than 2～2.5 times of stakes footpaths apart from B with pile center's line, and the peripheral gradient X of bedding is 1: 2～1: 3.The top material layer that throwing is filled out, bottom and the periphery rubble that is packed in bag, its thickness is 1～3 meter, optimum thickness is 2 meters; Middle packed sand throwing and filling or packed earth, the artificial thickness of subgrade bed Y-2 of its thickness S=is the thickness of packed rubble doubly, be packed in bag 4 meters of the thickness of rubble of the artificial thickness of subgrade bed Y-of the optimum thickness S=periphery of packed sand throwing and filling or packed earth.

Calculation diagram of the present invention shown in Figure 2, key of the present invention are the thickness Y that determines artificial bedding.

The diameter of D among the figure---pile;

The height of η---corrugated more than standing level, η _MaxMaximum value for η;

P---wave and current are to the distribution active force of pile foundation;

P---wave and current are to the total force of pile foundation;

The depth of water of d---calculating place;

The minimum underground layer degree of depth of h---pile;

Te, Tp---soil pressure;

Other---be the mark of convenience of calculation setting;

Promptly, find the solution the minimum underground layer degree of depth h value of pile by the active force of wave, current and foundation soil.

One, sets up the mechanical equation group.

Force balance equation: P+Tp=Te

Torque equilibrium equation: M (P)+M (Tp)=M (Te)

P wherein---by wave and current calculation of parameter;

Tp, Te---by ground soil property calculation of parameter;

M (P)---by the moment of P generation;

M (Tp), M (Te)---by the moment of Tp, Te generation;

Two, Tp, Te's finds the solution

Tp＝γ’h ₁[tg ²(45°+/2)-tg ²(45°-/2)]×h ₂

Te＝γ’h ₁[tg ²(45°+/2)-tg ²(45°-/2)]×h ₁/2

γ ': the buoyant unit weight of foundation soil, : foundation soil angle of friction

The diameter of D among the figure---pile;

The height of η---corrugated more than standing level, η _MaxMaximum value for η;

P---wave and current are to the distribution active force of pile foundation;

P---wave and current are to the total force of pile foundation;

The depth of water of d---calculating place;

The minimum underground layer degree of depth of h---pile;

Te, Tp---soil pressure;

Other---be the mark of convenience of calculation setting;

Promptly, find the solution the minimum underground layer degree of depth h value of pile by the active force of wave, current and foundation soil.

Three, set up the mechanical equation group.

Force balance equation: P+Tp=Te

Torque equilibrium equation: M (P)+M (Tp)=M (Te)

P wherein---by wave and current calculation of parameter;

Tp, Te---by ground soil property calculation of parameter;

M (P)---by the moment of P generation;

M (Tp), M (Te)---by the moment of Tp, Te generation;

Four, Tp, Te's finds the solution

Tp＝γ’h ₁[tg ²(45°+/2)-tg ²(45°-/2)]×h ₂

Te＝γ’h ₁[tg ²(45°+/2)-tg ²(45°-/2)]×h ₁/2

γ ': the buoyant unit weight of foundation soil, : foundation soil angle of friction

Five, P's finds the solution

1, simplified method.At current are principal elements, under the negligible situation of wave:

$P={\mathrm{Kn}}_{2}R\frac{V^2}{2g}---(1-1)$

K---resistance to water-flow coefficient wherein;

n ₂---the water depth effect coefficient;

R---water density;

V---calculate flow velocity;

G---acceleration of gravity;

More than each parameter all can look into and get by " port works load standard ".

2, under the situation that current, wave factor all can not be ignored, finding the solution of P value is complicated, and process is as follows:

Wave and current are to the effect of pile foundation: when calculating wave and bourn acting force, its element of wave should adopt the element of wave under water currents.Wave determines that by following regulation wherein L is the wavelength in the flowing water to the active force of the vertical small diameter cylinders of D/L≤0.2 with current.

2-1. the forward wave current power that acts on the water-bed face on the height z place pile section will be calculated as follows:

$p(z,t)=K_D|u(z,t)+u_c|\·[u(z,t)+u_c]+K_M\frac{\∂u(z,t)}{\∂t}---(2-1)$

$K_D=\frac{\mathrm{\γ}}{2g}{\mathrm{DC}}_D---(2-2)$

$K_M=\frac{\mathrm{\π\γ}}{4g}{D}^2{C}_M---(2-3)$

$u(z,t)=\frac{{\mathrm{\ω}}_{r}H}{2}\frac{\mathrm{chkz}}{\mathrm{shkd}}\cos \mathrm{\ωt}---(2-4)$

$\frac{\∂u(z,t)}{\∂t}=\frac{{\mathrm{\ω}}_r^{2}H}{2}\frac{\mathrm{chkz}}{\mathrm{shkd}}\sin \mathrm{\ωt}---(2-5)$

ω _r＝ω-ku _c (2-6)

P in the formula (z, t)---act on the forward wave current power (kN/m) on the pile section;

U (z, t)---the horizontal velocity (m/s) of water particle orbital motion;

The height value (m) of above calculating place of the water-bed face of z---cylinder;

T---the time (s) is when crest is t=0 by the cylinder center line;

u _c---flow rate of water flow (m/s);

G---acceleration of gravity (m/s ²);

The depth of water of d---calculating place (m);

---the horizontal acceleration (m/s of water particle orbital motion ²);

ω---wave circular frequency (s ^-1);

C _D, C _M---be respectively speed power and inertia force coefficient.

Coefficient C _D, C _MValue is determined by Fig. 2-1

2-2. wave number k finds the solution by following formula:

(ω-ku _c) ²＝gkthkd (2-7)

2-3. the KC number among Fig. 3 can calculate by following formula:

When | u _c|＜u _m(2-8)

$\mathrm{KC}=\frac{\mathrm{\π}\left|u_c\right|T}{D}$ When | u _c| 〉=u _m(2-9)

As shown in Figure 3,

＝arccos(|u _c|/u _m) (2-10)

$u_m=\frac{\mathrm{\πH}}{T}\mathrm{cthkd}---(2-11)$

T in the formula---wave period is got spectrum peak period T frequently during irregular wave _P, T _PGet 1.05T _s,

This moment, the KC number was with (KC) _PExpression;

u _m---the maximum horizontal speed (m/s) of water surface place water particle orbital motion;

H---wave height is got significant wave height during irregular wave.

2-4. ask the total wave current power that acts on the whole pile, should be along cylinder from water-bed z=0 to water surface z=d+ η

The height of corrugated more than standing level when η calculates phase place for this.Calculating is no less than the wave current power of 5 points, comprises z=0, d and d+ η 3 points, tries to achieve total power with the segmentation summation then.

2-5. the height η value of corrugated more than standing level can be calculated as follows:

η＝η _maxcosωt (2-12)

η max in the formula can determine by Fig. 4.

Six, the minimum underground layer degree of depth h's of pile finds the solution

The h value need be found the solution by tentative calculation repeatedly.

Known original Natural Depth is represented with H, effective soil layer thickness deltat 1, and establishing artificial thickness of subgrade bed is Δ 2, then has: h=Δ 1+ Δ 2, d=H-Δ 2.Thereby each element of solving equation group draws a new h value, revises Δ 2 by new h value, promptly revises the d value, and so repeated calculation is obtained best h value.

Seven, artificial thickness of subgrade bed Y's determines

The thickness Y of artificial bedding should be greater than the minimum underground layer degree of depth h of pile, and with reference to geologic information and job practices, with due regard to surplus.

As shown in Figure 5, construction sequence of the present invention comprises:

The a natural ground	B throws and fills out the packed rubble of bottom
		C throws and fills out the packed sand in middle level	D throws the packed rubble of layer of filling in a form
E sets pile foundation (or sleeve pipe)	The boring of f basement rock
		The construction of g socketed pile	H removes artificial bedding

Undertaken by above-mentioned a, b, c, d, e, f, eight steps in sequence of g, h.

Do not influence structure as artificial bedding and use and surrounding environment, can omitting wherein, step h-removes artificial bedding.

Artificial bedding technology is in mountain, Shanghai International Shipping Center ocean deep water port first stage of the project, port, Baosteel clues mountain, Shanghai the second stage of the project, solved well and exposed the difficult problem that basement rock or covering layer thinner region enter pile foundation construction, and with respect to technologies such as steel bar concrete casing, steel pipe trusses, both simple and easy to do, duration shortens, and has saved considerable engineering cost simultaneously again.

Claims (8)

1, a kind of deep-water bare basement rock socketed pile steady stake of artificial bedding technology of constructing is characterized in that forming a thickness in exposed basement rock zone with the method for the packed rubble of throwing, packed sand is that Y and side slope are the artificial bedding of X.

2, the deep-water bare basement rock socketed pile according to claim 1 steady stake of the artificial bedding technology of constructing, the thickness Y that it is characterized in that described artificial bedding should be greater than the minimum embedded depth h of pile, the minimum embedded depth h of pile calculates according to related specifications and mechanical equation, and with reference to geologic information and job practices, with due regard to surplus.

3, the deep-water bare basement rock socketed pile according to claim 2 steady stake of the artificial bedding technology of constructing is characterized in that described artificial bottom layer of subgrade, top layer and periphery are thrown to fill out packed rubble, middle packed sand throwing and filling or earth.

4, the deep-water bare basement rock socketed pile according to claim 3 steady stake of the artificial bedding technology of constructing, it is characterized in that it is 1～3 meter that described artificial bottom layer of subgrade, top layer and periphery are thrown the thickness of filling out packed rubble, the artificial thickness of subgrade bed Y-2 of the thickness S=of intermediate layer packed sand throwing and filling or earth is the thickness of packed rubble doubly.

5, the deep-water bare basement rock socketed pile according to claim 4 steady stake of the artificial bedding technology of constructing is characterized in that described artificial bottom layer of subgrade, top layer and periphery throw that to fill out packed rubble thickness be 2 meters.

6, according to claim 1 or 2 or 3 or the 4 or 5 described deep-water bare basement rock socketed piles steady stake of the artificial bedding technology of constructing, the peripheral gradient X that it is characterized in that described artificial bedding is 1: 2～1: 3.

7, according to claim 1 or 2 or 3 or the 4 or 5 described deep-water bare basement rock socketed piles steady stake of the artificial bedding technology of constructing, the top line that it is characterized in that described artificial bedding should be greater than 2～2.5 times of stakes directly apart from B with pile center's line.

8, the deep-water bare basement rock socketed pile according to claim 6 steady stake of the artificial bedding technology of constructing, the top line that it is characterized in that described artificial bedding should be greater than 2～2.5 times of stakes directly apart from B with pile center's line.

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