Differences between steel boxed construction, steel construction and steel sheet pile cofferdam construction

Boxed Cofferdam and Steel Boxed Cofferdam difference is that the former has a base plate, which is no floor. Other design calculation is basically the same. Boxed Cofferdam generally used in relatively deep riverbed, Caps bottom elevation below the surface and away from the higher river bed, in particular the kind of urgent water and the river bed is not suitable for steel box sets sinking geology. The box sets just apply to shallow areas, water flow rate is small and the geological situation is more adapted to the situation sinking steel box sets, of course, depends on the specific requirements of the design requirements and the relevant economic indicators and the river and can not be.

Steel cofferdam for water blocking structure is bearing platform construction, its role is hanging by fief concrete cofferdam side and on the floor surrounded by water, and dried to provide anhydrous environment for the construction of platform. Compared with steel cofferdam, steel box cofferdam with a short construction period, low flow resistance, which will help navigation, without sinking into the river bed, small construction difficulty, a small amount of concrete, etc., which have been widely used in the large-span bridge in deep water Applications.

Steel sheet pile cofferdam is most commonly used as a sheet pile cofferdam. Is a steel sheet pile with a lock port, there is a bar-shaped cross-section, Z-shaped groove and the like, there are a variety of sizes and interlocking forms.

Its advantages: high strength, easy to break into the hard soil; constructability in deep water, if necessary, with Diagonal bracing to become a confining cage. Waterproof performance; can form a variety of shapes as required cofferdam, and can be repeatedly used, and therefore, its use is widespread.

Often used in bridge construction worth a caisson cofferdam, its wide use. Column base, pile foundation and open-cut foundation cofferdam.

Common cofferdam mainly in the form of steel sheet pile cofferdam, cofferdam, steel boxed cofferdam, steel box cofferdam, steel-concrete composite cofferdam. Which has a steel sheet pile cofferdam construction speed, good economic returns, reusable and many other advantages, it is widely used in the construction of the bridge deep water foundation cofferdam when.

Bridges and culverts on steel piles and reinforced concrete sheet pile cofferdam General Provisions

1. Punched steel sheet pile (including reinforced concrete sheet piles, the same below) before the cofferdam deal piling equipment to conduct a comprehensive inspection.

2. Before lifting steel sheet pile, steel sheet pile site should be cleaned groove, locking should be trimmed or test plug; steel sheet pile group fight component should rugged gripper prison, spreader should not be tied to the steel sheet pile fixture. Welded steel sheet pile rings should someone check, if necessary trial hanging.

3. Hammers and hoist should set up special operations. Steel sheet pile lifting, should obey the command signal. When the job should be on leash rope slip sheet piles to prevent sharp swings after lifting. No piles of steel sheet pile lifted position near the front can not stop people in place.

4. When the steel sheet pile into the lock port, the result of resistance can not be inserted into the locking position and the need to hammer piles are pressed into the wire rope hoist should be used to control the whereabouts of the pile hammer stroke to prevent sudden decline pile hammer with steel sheet pile.

5. Punched steel sheet pile, as a result of insufficient height crane can be moved downward hanging position, hanging points but not less than 1/3 of the pile under pile length position.

6. When the steel sheet pile hammer sinking, the initial phase should be tapped. Pile cap (pad) should be replaced deformation.

Board structure construction excavation wall of a stake

Building deep excavation safety specifications JGJ311-2013 provisions:

1. Steel sheet pile disposal site should be smooth solid combination of steel sheet pile piled high should not exceed 3 layers. Sheet pile construction work area should be free of high-voltage lines, the work area should be clearly marked or fenced. Pile hammer – administration process, monitoring the distance should not be less than 5m.

2. When the pile driver equipment assembly, to deal with each fastener to be checked before the fasteners not tightened can not be a counterweight installation. After assembly is completed, the deal with the whole test run to confirm each transmission, gear box, protective cover, good, each member is connected securely.

3. Pile operations should meet the following requirements:

  • Non-lifting, hanging hammer, rotary or walking and other movements at the same time;
  • When the pile driver hammer running belt should be put to the lowest bit pile hammer. Hammers hanging there in the pile and the hammer case, the operator may not leave their posts;
  • When vibration pile hammer job, vibration pile hammer hanging crane, must be protected against loosening on its hook, vibration pile hammer shall be equipped with safety rope hanging on steel earrings;
  • Instrumentation process, should be promptly corrected verticality pile. Set of locks should be checked before using the subsequent sheet pile lock between the pile and the first piling. When the pile buried more than 3m. Do not use hammers walking or turning motion to correct the verticality of the pile;
  • When downtime is longer, it should pile hammer falling pad is good;
  • Can not be suspended pile hammer overhaul;
  • After the job should be piling machine parked on a solid flat surface, the pile hammer down pad is, and should be cut off the power supply.

4. When the sheet pile wall around the pits in the adjacent building (structure) buildings and underground pipelines, should be static piling method of construction, the construction should be controlled and the rate of pressure piles according to environmental conditions. When static piling job, there should be unity of command, staff and pile pressure hoisting personnel should be in close contact with each other.

5. Envelope sheet pile construction process, should strengthen the monitoring of the surrounding groundwater level and pore water pressure.

Steel sheet pile cofferdam construction – screen method

10 ~ 20 sheet pile inserted to a depth of soil, so that the pile driver hammer back and forth, and both ends of the pile 12 to the desired depth and then hit the middle portion of the sheet pile sequentially beating. This construction method prevents the screen tilt and rotation of the sheet pile, the requirements of a closed envelope, often use this method.

Using this method can guarantee the achievement of good verticality, and to reduce the difficulties can be encountered in the pile and scattered piles, and can better control the length of the pile wall. As the positioning along the entire sheet piles, not necessarily all of the piles are playing to the design elevation, thus ensuring localized pile can not play to the design elevation and undermine the overall effect of the wall, the drawback is faster than installing pile construction method is slow and pile high shelf.

How to ensure the structural stability of the steel sheet piling cofferdam?

Formed steel sheet piling cofferdam of steel sheet piling is composed of many root constituted by punched by the root, snap each other to form a closed whole. The most common is the use of steel sheet piling cofferdam Larsen steel sheet piling, steel sheet piling cofferdam structure of how to ensure its stability?

We commonly used type IV steel sheet piling cofferdam structures are needed to support the inside of the cofferdam, which requires cofferdam according to the size, depth, chosen steel, I-beam or H-beam were supporting.

We encountered a large cofferdam cofferdam need more overall structure design, finite element analysis software is generally designed so as to ensure the stability of the overall structure of the cofferdam.

Why steel sheet pile will be the case it leaks and flooded sand

Steel sheet pile seems to have become one of the most common construction tools, some users reacted sheet piles will be some leakage and flooded sand phenomenon. What causes it? We work together to analyze it!

(1) Many of the old sheet pile pile more, prior to use is not enough time to repair or overhaul the correction is not thorough enough, resulting in locking engagement at a bad leak occurred at the seams and so on.

(2) Corner sheet piles are special points to achieve closure collapse to be a special craft corner. If the corner pile after cutting general welding process, if not handled properly will be deformed.

(3) Steel sheet pile to be mutually inserted in order to form a huge barrier net, if cut in at the mouth of the steel sheet pile lock is not tight, the case of leakage will occur.

Everything is cause and effect, we should pay attention to some of the steel sheet pile construction subtle, ensure the normal work and construction safety sheet pile.

Some Small Details of Steel Sheet Piling Construction

Retaining wall construction requires the use of land, but the use of water construction fence is not the reality, the wall of the building is brick and cement, cement easily disintegrated in the water, so the water wall will soon collapse, and the construction of the wall in the water more difficult than Great, so the cement wall is only suitable for use on land, but also need water construction envelope construction envelope water only choose steel sheet piling, steel sheet piling in the water because of relatively strong, steel sheet piling in the water like a bridge column as well, so supporting role is a large, steel sheet piling structure is simple, but many construction details, because the use of steel sheet piling must face the impact of the water, the construction firm will not become serious consequences, so the steel sheet piling construction for a security firm, which requires many of the construction techniques.

Since it is a fixed steel sheet piling to play the role, so good in itself must fastness in water, and steel sheet piling into the water at the time of the shaking must ensure that smaller steel sheet piling, sheet piles in the construction of the parallel is very important, because the parallel steel sheet piling can withstand greater impact, and steel sheet piling parallel to set up the appearance of more smooth. steel sheet piling needs to maintain long-term stability, the steel sheet piling construction period will not be touching a machine, especially a large touch machine, the machine could lead directly touching or shaking the collapse of the steel sheet piling increases, so the sheet pile to a certain distance away from the construction site.

The inclination of the steel sheet piling sheet pile factors also affect the quality of a steel sheet piling tilt position will affect all sheet piles, steel sheet piling so need to ensure that each of the root to be vertical, although the inclination can not be avoided, but to minimum inclination.

Problems encountered in steel sheet pile construction and treatment measures

We also mentioned some of the details and procedures regarding Larsen steel sheet pile construction, let’s see if in the construction process into a problem, how to solve.

Because of the complex geological structure of bed, pulling a steel sheet pile construction often encounter some problems, the solution is often used as follows:

1. obstacle. Pile process sometimes encounter a large stone or other unknown obstacles, resulting steel sheet pile driving deep enough, use curved corner pile or piles around obstacles.

2. the skew. Corrective measures to squeeze steel sheet pile Miscellaneous Fill area during lateral extrusion force by stones of different sizes easily deflect, be taken: in the event of a deflected position to pull up the sheet pile 1.0m ~ 2.0m, then down into the hammer, and so forth up and down several times to pull vibration, the vibration can be a large stone broken or it is displaced, so that the steel sheet pile position is corrected to reduce the inclination of the steel sheet pile.

3. shaped pile corrected. Steel sheet pile axial inclination is large, special-shaped piles to correct, shaped pile is generally wider at the top and a width greater than or less than the standard width of the sheet pile, the pile can be shaped according to the actual welding process inclination; inclination is small You can also use the hoist rope or hoist the pile and pulled back the hammer again.

4. into the phenomenon. On the basis of the softer, sometimes occurs when the construction will pile into the adjacent phenomenon, is used to measure the number of adjacent piles are welded together and painted on the locking connection when administered playing piles to reduce the resistance of lubricants butter.

5. Conclusion

Construction of the actual results show that, compared with the steel sheet pile cofferdam cofferdam filling with construction progress faster, safer, small footprint, etc., which for the narrow creek embankment remediation project within the city, the water is deep, rapid stream engineering using silt or fine sand and soft soil and other groups with a suitable filling cofferdam is more favorable, but the drawback is the cost of the steel sheet pile material one-time investment is high, take up more liquidity, and therefore whether the use of steel and steel sheet pile cofferdam pile into the quantity and turnover and other issues must be carefully analyzed, preferably after technical and economic comparison may decide.

Finally, we also recommend that all of the construction process, attention to detail, safety is of primary importance.

Why is it called Larsen steel sheet pile?

There are various types of steel sheet pile, Larsen steel sheet pile mainly to distinguish between domestic channel, channel because there are a lot of people like to call sheet pile.

Larsen sheet pile is well-known and has long been known in the field of civil engineering construction materials. Used in retaining structures under various conditions, its applications and advantages have been (in the professional field) and has been continually proven and confirmed.

In 1902, German national Chief Engineer Mr. Trygve Larsen in Bremen developed the world’s first production of a U-shaped cross section protruding rivet interlocking steel sheet pile.

In 1914, both sides of the chain can come out of sheet pile. The (improved) has been overwhelming majority of the world sheet pile (manufacturers) are still in use. Oldest Larsen U-shaped plate Giken Kochi pile is placed in the company headquarters to show to commemorate the history of U-shaped plate piles. The above-mentioned interconnect structure can refer to the following figure. On both sides of each U-shaped plate piles “U herniation” design can be used to chain adjacent sheet pile.

Interlocking structure may (in tiles interlocked) a watertight structure is formed so as to increase the strength of porphyritic structure. It can be widely used in soil cofferdam and support (engineering).

Larsen steel sheet pile as a new building material, cofferdam in the bridge, a large pipe laying, trenching for temporary retaining, retaining, retaining sand wall; at the dock, unloading Course for wall, retaining walls, embankments revetment, etc., play an important role on the project. Larsen steel sheet pile cofferdam do not only green, environmental protection and construction speed, low construction cost, with good waterproof function.

Cold – formed products are hot-rolled steel sheet piles and steel sheet pile by two types of production technology division. In engineering construction, cold-formed steel sheet pile narrow range of applications, mostly as a supplementary application material, hot-rolled steel sheet pile has been a leading product engineering applications. Based on the many advantages of steel sheet piling in the construction job, the State Administration of Quality Supervision, Inspection and Quarantine, the National Standardization Management Committee on May 14, 2007 issued a “U-shaped hot-rolled steel sheet pile,” the national standard, and on December 1, 2007 the formal implementation. According to statistics, China’s annual consumption of sheet piles remained at about 30,000 tons, accounted for only 1% of the world, and is limited to a number of ports, terminals, shipyards and other permanent works and bridge construction cofferdam, excavation, etc. temporary works.

Sheet Pile Design

Sheet pile wharf structure:

In front of the sheet pile wall: composed of vertical quay wall, neither through the air high-pile wharf, nor bulky gravity wharf, the disadvantage is that external force is not too large, used for medium and small pier.

Middle bar: power transmission structure in the middle, the main consideration is the need for preservation, is an important part of sheet pile wharf affect durability

Rear anchoring structure: This is a reduction from the sheet pile at a depth of role pile displacement and improve the force.

Top design guide beam or sheet pile cap beam, which is actually gravity quay parapet.

Tile dock calculation:

Buried depth (front and rear calculated soil pressure, the residual water pressure) in front of the sheet pile, internal forces (pileup load, mooring force, etc.), pull the lever (assuming drawbar pull rod arranged with the rear anchoring structure).

Design modulus first sheet pile is in pre-time need to be implemented, followed by external force according to the geological exploration is calculated, assuming sheet pile embedded depth (that is, applied to sheet piling focus).

Implementation of embedded depth (meet deformation requirements), determine the corresponding rod internal forces, in the best distance to determine the relevant anchoring structure and sheet pile (the force best), calculated value based on the implementation of the standard rod pull rod internal forces, after the turn, calculation rod sections, prefabricated rod.