Sheet-pile construction isn't as simple as you might think. To achieve good construction results, attention to detail is essential. Today, we’ll go into detail about the key points you need to pay attention to when working with sheet piles—packed with valuable information! I recommend saving this article and studying it again and again.

I. General Requirements

1. The placement of sheet piling must comply with design requirements and facilitate earthwork operations for the trench foundation, leaving sufficient space outside the most protruding edge of the foundation for formwork installation and removal.

2. The plan layout of the steel sheet-pile support for excavation pits and trenches should be as straight and neat as possible, avoiding irregular corners to facilitate the use of standard steel sheet piles and the installation of supports. Each peripheral dimension should closely match the modular dimensions of the panel forms.

3. Throughout the entire foundation construction period, during earth excavation, lifting and transportation, rebar tying, concrete pouring, and other construction operations, it is strictly prohibited to collide with the supports, arbitrarily remove the supports, make arbitrary cuts or perform electric welding on the supports, or place heavy objects on the supports.

II. Support Line Surveying

Based on the design requirements for the excavation section width of the foundation pit and trench, mark out the positioning lines for driving the steel sheet piles and indicate the pile-driving positions with white lime.

3. Steel Sheet Pile Entry and Stacking Area

Organize the timing of steel sheet pile deliveries according to the construction schedule or site conditions, ensuring that the construction of steel sheet piles meets the schedule requirements. The stacking locations for steel sheet piles should be dispersed along the support line based on construction requirements and site conditions, avoiding concentrated stacking that could lead to unnecessary secondary handling.

4. Construction Sequence for Steel Sheet Piles

Layout and positioning—Excavation of trenches—Installation of guide beams—Driving steel sheet piles—Removal of guide beams—Construction of walings and supports—Earth excavation—Foundation construction (load-transfer belt)—Removal of supports—Construction of the basement’s main structure—Backfilling of earth—Extraction of steel sheet piles—Treatment of voids left after removal of steel sheet piles

V. Inspection, Lifting, and Stacking of Steel Sheet Piles

1. Inspection of steel sheet piles

For sheet piling, material inspection and visual inspection are typically conducted to identify and correct any sheet piles that do not meet the required standards, thereby reducing difficulties during the driving process.

(1) Visual Inspection: Includes items such as surface defects, length, width, thickness, rectangularity of end faces, straightness, and lock-mold shape. Please note:

a. Welding components that may affect the driving of steel sheet piles should be removed.

b. Holes and section defects shall be reinforced accordingly;

c. If the steel sheet piles exhibit severe corrosion, their actual cross-sectional thickness should be measured. In principle, all steel sheet piles should undergo an inspection of their surface quality.

(2) Material Inspection: Conduct comprehensive tests on the chemical composition and mechanical properties of the base material of steel sheet piles. These tests include chemical composition analysis of the steel, tensile and bending tests on components, interlock strength tests, and elongation tests. For each specification of steel sheet pile, at least one tensile and one bending test must be performed. For every 20–50 tons of steel sheet piles, two specimen tests shall be conducted.

2. Lifting and transporting steel sheet piles

The handling of sheet piling should be carried out using a two-point lifting method. During lifting, the number of sheet piles lifted at one time should not be excessive, and care must be taken to protect the interlocking edges from damage. There are two lifting methods: lifting in bundles and lifting individual piles. Bundled lifting typically uses steel cables for bundling, while single-pile lifting commonly employs specialized lifting devices.

3. Stacking of steel sheet piles

The location for stacking sheet piling should be chosen on a flat, firm site that will not experience significant settlement or deformation due to the weight of the piles, and it should also be conveniently accessible for transportation to the pile-driving construction site. When stacking, the following points should be noted:

(1) The sequence, location, orientation, and layout of the materials should take into account future construction requirements.

(2) Steel sheet piles shall be stacked separately according to their model, specification, and length, and signs indicating this information shall be placed at the stacking area.

(3) Steel sheet piles should be stacked in layers, with no more than 5 piles per layer. Each layer must be supported by sleepers, spaced approximately 3 to 4 meters apart. The sleepers at the upper and lower layers should be aligned vertically. The total stacking height should not exceed 2 meters.

6. Installation of the guide frame

In sheet-pile construction, to ensure the accuracy of the pile-driving axis and the verticality of the piles, control the precision of pile driving, prevent buckling and deformation of the sheet piles, and enhance the penetration capacity of the piles, it is generally necessary to install a rigid guide frame with sufficient stiffness—also known as a "construction waler."

The guide frame adopts a single-layer, double-sided configuration and typically consists of guide beams and surrounding pile caps. The spacing between the surrounding pile caps is generally 2.5 to 3.5 meters. The gap between the two sides of the surrounding enclosure should not be too large—typically slightly larger than the thickness of the sheet-pile wall by 8 to 15 millimeters. When installing the guide frame, the following points should be noted:

(1) Use a theodolite and a level to control and adjust the position of the guide beam.

(2) The height of the guide beam should be appropriate, facilitating control of the construction height of steel sheet piles and improving construction efficiency.

(3) The guide beam must not experience sinking or deformation as the steel sheet piles are driven deeper.

(4) The position of the guide beam should be as vertical as possible and must not collide with the steel sheet piles.

7. Driving of Steel Sheet Piles

The construction of steel sheet piles is critical to ensuring waterstop and safety during the project, making it one of the most crucial processes in this construction. During construction, attention should be paid to the following requirements:

(1) Sheet piles shall be driven using a crawler excavator. Before driving, it is essential to familiarize yourself with the location of underground pipelines and structures, and carefully mark out the accurate centerlines of the support piles.

(2) Before driving the sheet piles, inspect each pile individually. Discard any sheet piles with severe rust or significant deformation at the interlocking joints. Only use those that have been repaired and passed inspection. Piles that remain unqualified after repair must be prohibited from use.

(3) Before driving the sheet piles, grease can be applied to the interlocking joints of the steel sheet piles to facilitate their driving and extraction.

(4) During the driving of steel sheet piles, as the inclination of each pile is monitored and measured, if the deviation becomes too large to be corrected by alignment methods, the pile must be pulled out and driven again.

(5) Ensure tight interlocking and that, after excavation, the embedded depth is no less than 2 meters, thereby guaranteeing smooth closure of the sheet piling. In particular, the four corners of the inspection well location must be fitted with corner sheet piles. If such corner sheet piles are unavailable, use auxiliary measures—such as old tires or rags—to seal the gaps tightly, preventing water leakage from washing away soil and causing ground subsidence.

(6) During the excavation of the foundation trench, continuously monitor the condition of the sheet piling. If any obvious tilting or bulging is observed, immediately add symmetrical supports at the locations where tilting or bulging occurs.

8. Removal of Steel Sheet Piles

After backfilling the excavation pit, the steel sheet piles must be removed for reuse. Before removing the steel sheet piles, it is essential to carefully study the sequence and timing of pile extraction as well as the treatment of soil voids. Otherwise, the vibrations caused by pile extraction, combined with excessive soil entrapment during removal, could lead to ground settlement and displacement, posing risks to the already constructed underground structures and compromising the safety of nearby existing buildings, structures, or underground pipelines. Therefore, it is crucial to minimize the amount of soil entrapped during pile extraction; currently, the primary methods employed for this purpose are water injection and sand filling.

(1) Pile extraction method

Vibration hammers can be used to extract piles in this project: By generating forced vibrations, the vibration hammer disturbs the soil, weakening the cohesion of the soil surrounding the sheet piling and thereby overcoming the resistance to pile extraction. The pile is then pulled out with the aid of additional lifting force.

(2) Precautions when removing piles

a. Starting Point and Sequence for Pile Extraction: For closed-type sheet-pile walls, the starting point for pile extraction should be at least five piles away from the corner piles. The starting point for pile extraction can be determined based on the conditions during driving; if necessary, a skip-extraction method may also be employed. Ideally, the sequence of pile extraction should be the reverse of the sequence used during driving.

b. Vibratory Driving and Pulling: When extracting sheet piles, first use a vibratory hammer to loosen the interlocking joints of the sheet piles, thereby reducing soil adhesion. Then, while continuing to vibrate, gradually pull the piles out. For sheet piles that are particularly difficult to remove, first use a diesel hammer to drive the pile down by 100–300 mm, and then alternate between using the diesel hammer and the vibratory hammer for driving and pulling.

c. The crane should gradually increase the load as the vibratory hammer is started; the lifting force should generally be slightly less than the compression limit of the damper springs.

d. The power supply used for the vibratory hammer should be 1.2 to 2.0 times the rated power of the vibratory hammer itself.

(3) If the steel sheet piles cannot be pulled out, the following measures can be adopted:

a. Use the vibratory hammer to re-drive the pile once more, in order to overcome the resistance caused by the adhesion to the soil and rust accumulated at the interlocking joints;

b. Remove the sheet piles in the reverse order of their driving sequence;

c. On the side of the sheet pile subjected to earth pressure, the soil is relatively dense. By driving another sheet pile adjacent to it, the original sheet pile can be pulled out smoothly.

d. Grooves are cut on both sides of the sheet piles, and a soil slurry is injected into them to reduce resistance when the piles are pulled out.

(4) Common problems and solutions in sheet pile construction:

a. Tilting. The cause of this issue is the significant resistance between the driven pile and the interlocking joints of adjacent piles, while the penetration resistance in the direction of pile driving is relatively low. Possible solutions include: continuously monitoring, controlling, and correcting during construction using specialized instruments; when tilting occurs, use steel wire ropes to secure the pile body, pulling it gradually while continuing to drive the pile to correct the tilt step by step; and allow a moderate amount of deviation in advance for the previously driven sheet piles.

b. Torsion. The cause of this issue is that the interlocking joints are hinged connections. Possible solutions include: using blocking boards to secure the front interlocking joints of the sheet piles in the direction of pile driving; installing pulley brackets in the gaps between adjacent steel sheet piles to prevent rotational movement during pile settlement; and filling the gaps on both sides of the interlocking joints between two sheet piles with shims and wooden wedges.

c. Common connection. Cause: The steel sheet piles are tilted and bent, increasing the resistance at the slot. Remedial measures include: promptly correcting any tilting of the sheet piles; and temporarily fixing adjacent, already driven piles with angle irons welded in place.

Yantai Juxiang Construction Machinery Co., Ltd. is one of China's largest enterprises specializing in the design and manufacture of excavator attachments. With 15 years of experience in manufacturing piling rigs and more than 50 R&D engineers, Juxiang Machinery produces over 2,000 sets of piling equipment annually and maintains close, long-term cooperation with leading domestic original equipment manufacturers such as Sany, XCMG, and LiuGong. The piling equipment produced by Juxiang Machinery features exquisite craftsmanship and advanced technology; its products are exported to 18 countries worldwide, enjoy strong global sales, and have received unanimous acclaim. Juxiang boasts exceptional capabilities in providing customers with systematic, turnkey engineering equipment and solutions, making it a trusted provider of engineering equipment solutions. We warmly invite all interested parties to reach out for consultations and collaboration.