CONSTRUCTION OF THE BREAKWATER USING BAMBOO PILE AND BAMBOO MATTRESS AS FOUNDATION MATERIAL Ryusuke Tsutsumi 1

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1 CONSTRUCTION OF THE BREAKWATER USING BAMBOO PILE AND BAMBOO MATTRESS AS FOUNDATION MATERIAL Ryusuke Tsutsumi 1 ABSTRACT From March 2012 until September 2014, the international port of Tanjung Priok in the north Jakarta has undergone massive construction development. The main objective is to improve vessel traffic efficiency. For this purpose, the channel was enlarged, the existing breakwater was demolished and new breakwater was constructed 500m offshore side. Although main construction item is dredging, this report is focus on design, construction management and results using bamboo material to foundation of new breakwater. Keywords: Sand replacement, Bamboo material, Availability of local material, Trial construction, INTRODUCTION Tanjung Priok port is the biggest port in Indonesia handles about half the total containers of whole country. The volume of container handled is 20 th in the world for the year The facility of the port, especially the breakwater, has been used and maintained since 1900 s when Indonesia was under the rule of the Netherlands. The port has two entrances, however, general cargo vessels were not allowed to pass in a portion of the east entrance due to shallow water and considerable subsidence of the breakwater. At the west side entrance, the width is only 125m which does not allow two-way traffic of big vessels. Finally, the turning basin is located at an unsecured area outside the port which requires an escort tugboat for vessels turning and entering into the port. The current condition of the port facilities cannot support increase vessel traffic, massive improvement of port facilities is necessary for safe and efficient ship port calls. Photo-1 Port Entrance Before Construction Photo-2 Front of Berth Area Before Construction 1 Engineer, Toyo Construction Co., Ltd., 2-43, Aomi, Koto-ku, Tokyo , Japan Tel: Fax: , Tsutsumi-ryusuke@toyo-const.co.jp 1020

2 Table of Contents WODCON XXI PROCEEDINGS OUTLINE OF CONSTRUCTION Project THE URGENT REHABILITATION PROJECT OF TANJUNG PRIOK PORT Location Jl. Raya Pelabuhan No.8, Tanjung Priok, Jakarta Utara Indonesia Employer DIRECT GENERAL OF SEA TRANSPORTATION, MINISTRY OF TRANSPORTATION Engineer NIPPON KOEI JAPAN PORT CONSULTANT Wiratman&Associates PT.Rayakonsult JV Financial Resources OFFICIAL DEVELOPMENT ASSISTANCE OF JAPAN Contractor TOYO ADHI KARYA JV Construction Term 22nd MARCH th SEPTEMBER 2014 (900days) Quantity Demolition of Existing Breakwater Construction of New Breakwater Trench Excavation Driving Bamboo Pile Installation Bamboo Mattress Re-use Material Replacement Stone Work Coping Block 30.0t Type Coping Block 23.0t Type Tetra Block 2.0t Type Tetra Block 3.2t Type Dredging Work 2,057 ｍ 1,469 ｍ 150, ,720 nos 45, , , nos 82 nos 22,326 nos 942 nos 8,019,000 Figure-1: Construction Location and Plan 1021

3 HISTORY OF BAMBOO PILE AND MATTRESS ADOPTION Concurrent to the breakwater construction project and months later, Phase 1 of another container terminal project (figure-2) also started in the adjacent area. The future planned, Phase 2, will also be constructed and will reclaim the offshore side of the new breakwater of our project. Due to that plan, if the new breakwater utilized the original location, said breakwater would have to be totally demolished. However, if the new breakwater was constructed towards the offshore side, 110m from the original location, it could be utilized as a revetment for the future reclamation. Figure-2: New Container Terminal Project Plan (Phase I and II) Under the original design, the new breakwater foundation would excavate the weak stratum (Clay and Silt AC1 Layer N=0~4) and improve it by replacing it with fine sand (figure-3). However, due to the thicker deposit of weak stratum than in the original relocation area the new breakwater construction if following the same design of excavation and sand replacement might become costly and delay progress due to the difficulty of sourcing suitable sand replacement material. In consideration of the above issues, a traditional method of construction in Indonesia, using bamboo piles and bamboo mattress, (bamboo being very abundant and easily procured locally) was adopted as a foundation for the new breakwater (Figure-4) Concrete Block 2 ton type, Kd = Armor Stone 500 ~ 1,000 kg M.H.W.S C.D } : 4/ Rubble Stone (50 ~ 100 kg) : 1.5 Armor Stone 250 ~ 500 kg Foot Protection 100 ~ 200 kg Re-use material from demolished existing breakwater Bamboo Mattress Bamboo Pile Figure-3 Original Typical Section Figure-4 New Typical Section A foundation using bamboo has already been used in prior construction at Jakarta Fishing Port located in 10km west of the Tanjung Priok Port. (Figure-5 & Figure-6) This port was constructed 30 years ago and is still being used at present. Specification of bamboo piles and mattress of this project referred to in the specification for this fishing port. Figure-5 Typical Section of JAKARTA FISHING PORT Figure-6 Location of Jakarta Fishing Port 1022

4 In addition, part of existing break water in Tanjung Priok Port has been constructed using bamboo material as foundation 50 years before (Figure-7). When that breakwater was demolished in this time, those bamboo piles appeared to be in condition. It means bamboo placed into the sea could maintain its function without degradation for decades (Photo-3). Figure-7 Existing Breakwater Section Photo-3 The Bamboo Piled 50 Years Ago THE EXPECTED EFFECT ON THE BAMBOO MATERIAL USED AS FOUNDATION A Bamboo Pile is composed of 7 bamboo trunks bundled up, to make the diameter 30cm with a length from 9.0m to 12.0m depending on the thickness of weak stratum (Figure-8, Photo-4). The Bamboo Mattress is put in a double cross formation and in a 3-layer structure. Each layer consists of three bamboo lengths bound together every 50 cm (Figure-9). Bamboo Pile Detail 300 9,000 Figure-8 Detail of Bamboo Pile Photo-4 Bamboo Pile Figure-9 Bamboo Mattress Plan 1023

5 Photo-5 Fabricated Bamboo Mattress Bamboo piles are expected to prevent rotation slip of the piled area and are regarded as an improvement to existing ground shear resistance (Figure-10). The perpendicular strength counteracts the reduced settlement of the breakwater based on the calculation model for the consolidation settlement (Figure-11). The bamboo mattress is also expected to prevent rotation slip. Rotation Slip analysis was calculated using the shear resistance of bamboo piles and the mattress. Figure-10 Rotation Slip Analysis Figure -11 Consolidation Settlements Calculation Model MANAGEMENT METHOD AND CONSTRUCTION RESULTS Piling of Bamboo Pile Trial Piling Work There is no clear history about construction management for bamboo piling, so trial piling was conducted to determine the criteria and construction methods. When Jakarta Fishing Port (mentioned above) was being constructed, some bamboo piles did not reached to bearing stratum which causes the rotation slip of the breakwater. Piling until reaching the bearing stratum is most important for construction management. Trial piling of bamboo piles adopted the drop hammer method which was referenced for the Jakarta Fishing Port project. A crane barge was also used (15ton lifting capacity) with s casing to guide the pile (Figure-12, Photo-6). +2.0m -7.0m -16.0m Figure-12 Piling Bamboo Pile Plan Photo-6 Trial Piling Bamboo Pile 1024

6 At first, as confirmation of workability the hammer fall height and hammer weight were evaluated. In regard to the hammer fall height it was considered to look at the case where the hammer fall position was kept at same elevation. Another case was for the hammer fall height to always be kept 2m above the pile head. In the case where the hammer fall position was kept constantly, as the penetration of the pile advanced, the fall height distance of the hammer became greater and the penetration amount increased due to increase of the blow energy. However, damage to the pile head was confirmed (Figure -13, Photo-7). So, it was judged that the fall height of less than 2m from pile head was necessary. Photo-7 Broken Pile Head Figure-13 Relation with Penetration and Dropping Height With regard to hammer weight, Use of 1.2t and 2.0t hammers were evaluated with the fall 2.0m above the pile head. It was seen that using the heavier hammer gave more blow energy and could then finish with smaller blow times. In both cases there had not been any damaged pile head so the use of the 2.0t weight hammer was adopted (Figure-14). Figure-14 Relation with Penetration and Hammer Weight 1025

7 The second criteria determined was for the final driving level It was necessary to set out the criteria for the confirmation of the bamboo pile penetration to Ac2 layer from the viewpoint of settlement restraint and to prevent rotation slip. This trial piling was conducted at an existing boring position and the data taken for blow times and penetration amount. When the bamboo pile tip arrived at the Ac2 layer of the bearing stratum the penetration amount per blow was 40cm (figure-15). As a result, the following criteria was set out. It is to be judged that the pile head has penetrated to bearing stratum when the penetration amount for one blow is less than 40cm. Figure-15 Relation with Penetration and Tip Depth of Bamboo Pile Record of piling bamboo pile At the beginning, the work was done in the daytime in consideration of certainty and safety. But during the monsoon season, progress was delayed due to the bad sea condition and it became relatively calm in the night so the working time was changed to night and day from January For this reason from March 2013 after monsoon, there were days when the bamboo piles could be driven at a rate of 300piles/day. After May 2013, the weather calmed down and the number of piles driven became 250piles for a day on average. Piling work was completed with a total of 34,721pilesdriven on 25th July 2013 (Figure-16). Figure-16 Bamboo Pile Driving Record 1026

8 Effect of bamboo pile The design of the new breakwater using a bamboo foundation allowed for settlement of 50cm. During the construction term, the settlement was monitored not only at the breakwater but also at another new breakwater which was being constructed without using bamboo piling. In spite of the loading weight of the new break water with bamboo piles being about 11t/m2 compared to the one without bamboo pile whose load is about one third at about 4t/m2, the settlement with bamboo piling was clearly smaller than without bamboo piling (Figure-17). It means that the bamboo pile system is affective for reducing the amount of settlement. Figure-17 Monitoring Settlement In addition, the settlement speed with bamboo piling is earlier than was assumed although the speed slows down immediately and the loading for each construction stage shows a relatively large settlement just after that. With bamboo piles we concluded that with the characteristics of the bamboo piles the drainage effect was promoted. Installation of Bamboo Mattress Problem and Solution encountered during Installation A 4m3 grab dredger was used to install the bamboo mattress. The method was for the bamboo mattress to be brought from fabrication yard to beside the grab dredger. It was then moved to the designed location using an anchor winch with confirmation of position from a RTK-GPS system. After that, 4 steel pipes were driven for fixing the mattress, Rubble stone and/or re-used materials (masonry and sand coming from demolition of the foundation of existing breakwater) were placed on the mattress at an even weight, When the mattress had been installed, a diver confirmed the whole circumference of the mattress was touching the seabed and the gap was correct in relation to the position of the previous installed mattress (Figure-18, Photo-8). Figure-18 Installation Bamboo Mattress Plan Photo -8 Installation Bamboo Mattress 1027

9 At first, it was easy to install because the installation location was in shallow water where the depth was about 3m so that one part of mattress touched the bed without swinging in the sea soon after sinking have begun. However, there was a problem in deeper areas of about 8m depth. When the mattress was sinking and reached 1m below the sea surface, it unbalanced because of waves and currents. It then re-floated after the weight of reuse material on it had fallen off (Figure-19, Photo-9). Figure-19 Image of Bamboo Mattress Installation Photo -9 Falling down of Reuse Material Therefore a fence of bamboo was fabricated on the mattress to prevent any fall of reuse materials (Photo-6). Furthermore by installing a bamboo fence, rigidity of the bamboo mattress rose, and the bamboo mattress did not lose the balance in the sea (Figure-20, Photo-10) Additional Bamboo Fence for Retaining Stone Bamboo Mattress Figure-20 Bamboo Fence Design Photo -10 Installation using Bamboo Fence Record of Installation of Bamboo Mattress Installation of bamboo mattress in the shallow area started from September 2012 and finished early. But in the deeper area, where re-used material from demolition of existing breakwater was needed, installation had to wait due to progress of the demolition. Installation of that area started from December 2012, however, the monsoon season had then started so that construction was often stopped or failed in bad sea conditions due to the re-floating of the bamboo fence. From March 2013 after the monsoon, construction advanced smoothly as the weather got better and the bamboo fence was adopted (Figure-21) Figure-21 Bamboo Mattress Installation Record 1028

10 Photo-11 Port Entrance After Construction Photo-12 Front of Berth Area After Construction CONCLUSIONS The break water project was successfully completed with a high quality by introducing certain construction management techniques into Indonesian traditional bamboo pile and bamboo mattress methods. The bamboo pile and mattress system has satisfied the requirements for the prevention of rotation slip and reduction in the settlement period. In addition, there was also a benefit due to the reduction in the cost for materials which were easily procured locally. Finally, this method has achieved one of the goals of an ODA (Official Development Assistance of Japanese Government) project by using material that local inhabitants can supply which gives something back to the local community REFERENCE Journal of Japan Society of Civil Engineers May, 1986 issue CITATION Tsutsumi, R. Construction of the breakwater using bamboo pile and bamboo mattress as foundation material, Proceedings of the Twenty-First World Dredging Congress, WODCON XXI, Miami, Florida, USA, June 13-17,