Volume 6, Issue 4

December 2021

Case-History

Steel Sheet Pile Cofferdam in China (Hubei Province)
Yunxiang Wang
Shanghai Office, GIKEN LTD.

Hongjuan He
Secretariate, IPA
In China, since they had to rely on expensive imported steel sheet piles before, the scope of application of steel sheet
piles was limited to emergency projects such as disaster recoveries. In recent years, however, Chinese domestic
production and mass production of steel sheet piles have progressed, and the price of steel sheet piles has become
significantly lower than that of imported products, so the scope of application of constructions using steel sheet piles hasbeen expanding. Recently, with the increase in infrastructure development such as high-speed railways and expressways,
the number of steel sheet pile cofferdam has rapidly been increasing. Under such circumstances, cases of adopting thepress-in piling method are increasing, especially for projects overcoming high construction difficulties. In this article, acase of cofferdam for construction of expressway bridge piers over a river is introduced.

1. Construction Outline
1.1 Construction Location
The construction site is the highway bridge (official name: Hegu Han River Highway Bridge) over the Han River in
Xiangyang City, Hubei Province, China (Fig. 1). Xiangyang is a prefecture-level city located in the northwestern part of
Hubei Province, China, and is the second largest city in Hubei Province. As shown in Fig. 2, the cofferdam by the press-in
piling method was installed to construct the 23rd and 24th piers of this highway bridge.

19m

80m

Google Map

Hubei Province

No.22

Fig. 1. Project location

No.23

No.24

No.25

Fig. 2. Longitudinal section of the highway bridge

1.2 Background and objectives of the project
The name of this project is "G316 Hegu Han River Highway Bridge and Connection Project". G316 is an important highway in
Hubei Province, which runs through Xiangyang from east to west and plays an important role in the economic development ofthe region. However, some sections of the G316 Highway are winding narrow routes with limited traffic capacity. To optimize
the local road transportation network, Xiangyang City authorities have decided to implement this project.
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December 2021

Since the 23rd and 24th piers of this highway bridge were to be constructed in the river, construction of a cofferdam wasa premise. Initially, in consideration of hard ground conditions, pre-drilling with an earth drill plus steel sheet pile drivingby the vibratory hammer method was adopted. However, due to the fact that the ground was mixed with boulders andthe ground loosened by predrilling was reconsolidated when the steel sheet pile was driven by a vibratory hammer, theconstruction became difficult. As a result, the design was changed to the press-in piling method with an auger thatenables more reliable construction. The press-in work on the 23rd pier was carried out from December 2019 to April
2020, and the 24th pier from April to May 2020, and 182 cofferdam steel sheet piles were pressed in respectively.

2. Site condition and piling method
2.1 Site condition
At this site, there were two challenges that had to be overcome. The
first was the construction period. In this project, all work wasrequired to be completed within the dry season (DecemberFebruary). The Han River, which flows through the construction siteof Xiangyang City, is the largest tributary of the Yangtze River in China,
and there is a danger of flooding in summer. As mentioned in 1.2, thepredrilling plus vibrohammer method was initially adopted. Thismethod required two steps, predrilling and steel sheet pile driving,which might slow down the progress of the work. On the other hand,in the press-in piling method with an auger, augering and pile
installation could be performed in one process, therefore, morereliable and rapid construction was possible. The project was able tobe successfully completed within the planned construction period.
The second was the hard ground condition. The ground condition atthe site, as shown in the borehole log in Fig. 3, was hard groundformed of cobbles and weathered siltstones. At the actual site,boulders (200 mm to 300 mm) were found as shown in Fig. 4.

Fig. 3. Bore hole log

By using the press-in piling method with an auger, steel sheet piles were able to be installed without problems in spite ofsuch hard ground conditions. Unfortunately, due to the spread of the new coronavirus infection in January 2020, we werecompelled to close the site for two months, but in order to catch up on the construction period, we introduced two pressin piling machines, and we were able to make it (Fig. 5). Since the press-in piling machines were small and it was easy toconstruct with multiple units, the construction was able to be completed within the planned period, and this effect ofshortening the construction period was highly evaluated by the principal contractor.

Fig. 4. Boulders found at the site

Fig. 5. Shortening of the construction period
by using two press-in piling machines.
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December 2021

2.2 Piling methodFig. 6 shows the view of during the construction. At this site, thepress-in piling method with an auger was adopted, in which thepress-in resistance was reduced and the steel sheet piles werepressed in by excavating the ground using an auger as an auxiliary
construction method. As illustrated in the process of Fig. 7, theground at the tip of steel sheet pile being pressed in wasexcavated by the auger to create a state where the core washollowed out in the ground, and the steel sheet pile was pressedin while pulling out the auger. In this construction, used steel
sheet piles were pressed in with the press-in piling machine F201C600. At construction sites in China, temporary steel sheet piles
are often reused, so damage or deformation of steel sheet piles
due to improper construction can be a problem. The press-in
Fig. 6. A view of during construction
piling method with an auger not only made it possible to press-in
the steel sheet piles with the minimum required press-inpressure, but also it was possible to install steel sheet piles with high accuracy, thus, we were able to minimize the wearof the steel sheet piles.

1. Start the operation

2. Augering at the pile toe

3. Press-in the pile while
extracting the auger.

4. Repeat 1 to 3.

Fig. 7. Press-in process (extracted from the Press-in Retaining Structures: A Handbook Second Edition, 2021)

3. Concluding Remarks
In this work, we faced various problems such as the unpredictable impact of the new coronavirus and harder groundconditions than expected. But we were able to complete the construction as planned. In the future, we will continue topromote the press-in piling method so that it may be adopted not only for temporary constructions but also forpermanent constructions of bridge piers. This case study was published as one of the activities of TC6 (TechnicalCommittee on Investigation and analysis of the development status of Press-in technology in China), which is a technicalcommittee newly established by the International Press-in Association. From now on we will continue to introduce you
construction cases in China.
We would also like to take this opportunity to thank Horizon Construction Development Ltd. for providing materials andphotographs for the construction of this work.

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