The steel sheet pile will beerected using Construction technology for static pressuresteel sheet pile with twist drill of our company. The multifunctionalstatic pressure pile driver can not only independently press the steel sheetpile into fill, clay, silt and other soil layers, but also drill into the leadhole of various hard stratums using the self contained twist drill to press thesteel sheet pile. Meanwhile, the mechanical equipment features small, light,high output power, small operation surface and construction space as wide asthe machine. The twist drill system and the static pressure pile driver adoptintegrated control to ensure high construction efficiency, cause little damageto the steel sheet pile during construction, can be reused and save thematerial cost.

(1) Constructionsequence: Land leveling→ positioning and setting out of steel sheet pile→ excavationand trenching→ building the construction platform → entry and assembly ofmachines and materials → erection of steel sheet pile → backfill → removal ofprofile steel→ removal of steel sheet pile →exit.

Working diagram ofstatic pressure pile driver

         Pictures of entry ofmechanical equipment

(2) Inspection,hoisting and stacking of steel sheet pile

Inspection of steelsheet pile: Steel sheet piles should be tidied after arriving at theconstruction site. Remove impurities in the latch (such as welding slags andwaste filler, etc.) and repair the defect part. ① Inspection of latch:With a piece of about 2m long steel sheet pile of the same type andspecification as the standard, inspect the latch of all steel sheet piles ofthe same model. Pull the standard steel sheet pile trolley using winch andinspect the latch from the pile tip to the pile tail. Correct twisted and “bent” latches identified during inspection. ② Ensure the latcheson both sides of each steel sheet pile parallel. Meanwhile, control the widthof steel sheet piles to the same range as far as possible. Inspection of width:Measure the width of each steel sheet pile by upper, middle and lower partsusing steel ruler, control the width of each steel sheet pile to the samerange, and limit the difference to 1. For local deformation that can be seen bynaked eyes, carry out tightened inspection. Steel sheet piles exceeding thedeviation should not be used. ③ Other inspection of steel sheet pile. Carry out completeinspection of missing parts, remaining traces, uncleanliness, scale andcurliness of the pile body and adopt relevant measures to ensure normal use. ④Lubricatethe latch and adopt anti- seepage measures to erect the steel sheet pilesmoothly and increase anti- seepage performance of steel sheet pile. The latchof each steel sheet pile must be evenly lubricated using oil mixture, withproportion ratio of butter: dry bentonite: dry saw dust=5:5:3.

Hoisting of steelsheet pile: Steel sheet piles should be hoisted with two points. Control thenumber of steel sheet piles hoisted each time, pay attention to preventingbending and damage to steel sheet pile, and protect the latch from damage. Thesteel sheet piles can be hoisted by bundles and piece by piece. If steel sheetpiles are hoisted by bundles, they should be tied using steel rope. If they arehoisted piece by piece, they should be hoisted using special slings. Thetwo-point hoisting method is shown below:

Example of hoistingmethod

Stacking of steelsheet pile: When necessary, steel sheet piles should be stacked with a sleeperbetween two layers and the stacking height should not exceed 2m. For Lassensteel sheet piles, the spacing between sleepers should not exceed 4m. Steelsheet piles should be stacked in a flat and secure place resistant tosettlement deformation under heavy pressure for ease of transportation. Steelsheet piles should be stacked as shown below:

Example of steelsheet pile stacking

(3) Positioning ofsteel sheet pile

①Determine the base line: The measurer determines the axis, reserves the workingface for construction, and determines the construction position of steel sheetpile and groove. After the location axis isdetermined, set the start point and end point on the site, and set theobservation point of the location axis on the extension line.

② Determine the pileposition: Indicate the position of steel sheet pile by sequence.

(4) Build the construction platformand excavate the groove

When the design elevation of thepile top to the ground is ＜ 500mm, to ensure smoothoperation and displacement of the static pressure pile driver with twist drill,a groove whose width is at least 1400mm and height (from the pile top to thegroove bottom) is at least 500mm should be excavated along the center line ofthe support pile. The optimal width of the groove should be 2000mm and theoptimal height (from the pile top to the groove bottom) should be 1000mm. When the design elevation of the pile top to the groundis h≥500mm, the groove is not needed.

(6) Press the steelsheet pile

The steel sheet pileis erected using twist drill static pressure piling method. That is, erect thesteel sheet piles piece by piece from the start point to the end pointaccording to the set path using static pressure pile driver.

Construction sequenceof steel sheet pile

① Set a counter forcebase horizontally on the planned normal of the start point;

② Hoist the staticpressure pile driver, place the balancing weight or the steel sheet pile ofequivalent tonnage, and place them securely as per the required tonnage;

③ With the weight ofthe balancing weight as the counter force, press 4-5 counter force piles;

④ Move the pile driverto the counter force pile using the hydraulic clamp, clamp and fix it, andremove the counter force base and the counter force balancing weight;

Pictures of settingthe counter force base on the site

⑤ Press the steelsheet pile. When the steel sheet pile is securely supported, the staticpressure pile driver will move automatically;

⑥ Press the steelsheet pile to the design elevation;

⑦ Repeat steps ⑤-⑥ to pressremaining steel sheet piles;

Pictures of hoistingsteel sheet piles

The steel sheet pilecan be pressed using static pressure pile driver with twist drill using thefollowing 3 methods:

① In N≤25 soil layer,the steel sheet pile should be directly pressed under static pressure. Pressingprocess: Hoist the steel sheet pile into the chuck of the static pressure piledriver using crane, and confirm the perpendicularity and the planned normal ofthe jacked pile;

a) Start pressing thesteel sheet pile;

b) When the new steelsheet pile is securely supported, the static pressure pile driver will moveautomatically;

c) Press the steelsheet pile to the design elevation;

d) Weld the pile tip(the weld is 15cm below the pile tip);

e) Repeat steps a)-d)to press remaining steel sheet piles.

② In 25<N≤75 soillayer, press the steel sheet pile using twist drill under static pressure. Thepressing process is:

a) Assemble theexpansion bit of the twist drill;

b) Hoist the steelsheet pile into the chuck of the static pressure pile driver using crane, andconfirm the perpendicularity and the planned normal of the jacked pile;

c) Press the twistdrill and the steel sheet pile simultaneously;

d) When the new steelsheet pile is securely supported, the static pressure pile driver will moveautomatically;

e) Press the steelsheet pile to the design elevation;

f) Weld the pile tip(the weld is 15cm below the pile tip);

g) When the twistdrill rotates reversely, remove the drill bit and inspect whether it is worn;

h) Repeat steps b)-g)to press remaining steel sheet piles;

③ In N>75 soillayer, press the steel sheet pile using twist drill under static pressure.The pressing process is:

a) Assemble thepre-excavation twist drill and the pre-excavation beacon;

b) Pre-excavate usingtwist drill;

c) Remove thepre-excavation twist drill and beacon and replace the drill bit;

d) Hoist the steelsheet pile into the chuck of the static pressure pile driver using crane, andconfirm the perpendicularity and the planned normal of the jacked pile;

e) Press the twistdrill and the steel sheet pile simultaneously;

f) Press the steelsheet pile. When the steel sheet pile is securely supported, the staticpressure pile driver will move automatically;

g) Press the steelsheet pile to the design elevation;

h) Weld the pile tip (theweld is 15cm below the pile tip);

i) Remove anddisassemble the drill bit and assemble the pre-excavation twist drill;

j) Repeat steps a)-g)to press remaining steel sheet piles.

The soil layer ofthis project is 10<N≤29 soil layer, so the steel sheet pile should bepressed using twist drill under static pressure. Before construction, test thepiles to confirm whether they can be pressed smoothly. If not, they should bepressed by twist drill simultaneously.

(6) Removal of steelsheet pile

① After backfill,remove the steel sheet pile. The steel sheet pile is erected and removed usingstatic pressure pile driver in this project. The pile holes must be timelybackfilled after the piles are removed. The pile holes should be filled withwater and sand, etc.

② Pile removal usingstatic pressure pile driver

a) Hoist the twistdrill out as a whole and tidy the hydraulic pipe of the twist drill;

b) Hoist the sleeveof the twist drill into the chuck;

c) Weld the anti-dropsteel plate on both sides in the upper part of the sleeve;

d) Remove the steelsheet pile using static pressure pile driver;

e) When the topelevation of pile exceeds the sleeve, install the lock pin and hoist theremoved steel sheet pile using crane;

f) Place the removedsteel sheet pile in the designated position;

g) Repeat steps a)-f)to finish removal of pile.

Pictures of staticpressure pile pressing

Pictures of pilepressing （self-guided）

        Picture 1 of implementation effect

Picture 2 ofimplementation effect

(8) Constructionrequirements for steel sheet pile

① Get familiar withunderground pipelines and structures, carefully set out the center line ofsupport piles, and remove roadbed, rocks and other underground obstacles in theshallow part when necessary.

② In the pilingprocess, keep monitoring the piling process. The permissible deviation of theaxis of steel sheet pile should be ±30mm, the permissible deviation of the topelevation of pile should be ±10mm, and the perpendicularity should not exceed0.5%. When there is a large deviation, remove and re-erect the pile.

③ After piling, timelyinspect water tightness of the pile body, weld and repair the leak part andcarry out safety monitoring.

④ The piles must notbe stacked around the supporting area (about 1 time of pile length).

⑤ In the pilingprocess, the steel sheet piles (group) should be kept flat and secure. Toensure normal operation, a crane and an excavator should be adopted. The steelsheet pile hoisted must be inserted into the latch of the previous pilemanually and slowly to prevent damage to the latch. After that, the liftingrope can be loosened slightly to slide the pile into the latch by dead weightor press it under static pressure. If it is difficult, insert the pile forciblyunder static pressure, and erect the pile normally after the pile is insertedwith a certain depth and stable.

⑥ The steel sheet pileshould be sunk in strict accordance with pile sinking specification. Fourcorners of the foundation pit must be protected using corner pile to maximizethe anti-seepage performance of small-diameter steel sheet pile and ensuresmooth construction.

⑦ The enclosure andthe support should be fully welded to ensure welding quality.

⑧ The lower part ofthe latch in the piling direction of the steel sheet pile should be tied usingcork to prevent silt from entering the latch and avoid effect on the pilingprocess. Jointed steel sheet piles with joints should be staggered withjointless steel sheet piles. When necessary, the joints should be staggered formore than 2m vertically.