due to the extremely low surface soil resistance. The contractors responsible for installing the foundations for the towers faced great logistical and technical difficulties, and developed new systems for driving the piles, with the simultaneous use of 15 small piling rigs. Here we describe the methods used for determining the driving and acceptance criteria, using Dynamic Load Tests (DLT) corroborated by Static Load Tests (SLT). The Geographical Challenge The Alagados region lies inside an Environmental Extractive Reserve called “Verde para Sempre” (Forever Green), created in 2003. This is one of the largest environmental reserves in Brazil, with very strict environmental control parameters. No deep foundation had ever been executed before along this region. The main challenge faced on this job, however, was working in a place where self-propelling vessels or land vehicles and equipment could not be used. During the rainy season, the bulhado vegetation prevents the movement of outboard motor boats with propellers going deeper than 50 cm (20 in) (see Figure 1). In the dry season, the heavy mud prevents the movement of driving equipment (see Figure 2). Initially, the foundation contractor tried to utilize large size equipment, based on previous experience on this same job, namely the crossing of the Amazon River. That part of the job had taken place on a shoal near the margins of the Amazon River, on waters with depths ranging from 25 m (82 ft) and 2 m (6.5 ft). Due to the size of the Amazon, it does not have the dense bulhado vegetation of the smaller rivers, so despite the relatively shallow waters in some regions, self-propelling vessels could still navigate. A Chinese contractor built Tower 238, later known as the “Chinese Tower,” used in the crossing of the Amazon River. Figure 3 shows the kind of equipment used in the foundations of Tower 238. Vibra- tory and diesel hammers were used, weigh- ing about 100 KN (22 kips), activated by an (10,000 ft ) barge. The draft of that barge was close to 1.5 m (5 ft) in the river. (170 kips) secondary crane, on a 1,000 m 2 Figure 3. Equipment used for driving the foundations of Tower 238, the “Chinese Tower” 54 • DEEP FOUNDATIONS • JAN/FEB 2014 1,150 KN (260 kips) main crane and a 750 KN 2 This kind of equipment in the Alagados region failed. The barge could only get in the Alagados with extreme difficulty, and could cause environmental damages, with the opening of access paths larger than those permitted in the construction license. The project called for the driving of open-ended steel pipe piles, with dia- meters between 400 and 600 mm (16 and 24 in), lengths between 15 and 60 m (50 and 200 ft), compressive design load from 600 to 1,100 KN (135 to 250 kips), and uplift loads varying from 400 to 700 KN (90 to 160 kips). The contractor sought a solution that would allow driving such piles in those adverse conditions. The factors affecting the choice of the construction process were: • The pile installation had to be carried out in the rainy season, that is, from March to July. After that, the dry season would make it almost impossible for any equipment to access the driving locations. • The axis of the transmission line was up to 15 km (10 mi) away from the existing access rivers, the Aiquiqui and the Uiuy, and the access would have to be through the flooded area, with water levels as low as 1 m (3 ft), even in the rainy season. Figure 2. Heavy mud in the dry season makes equipment movement almost impossible
