Commodity concrete pump construction has been widely used in construction, but for the height of more than 300m high-rise pumping, due to pumping pressure is too high, the use of concrete strength, viscosity, pumping is particularly difficult to pump the construction zone Come to a series of technical problems to be explored. With the popularization and rapid development of pumping concrete, continuous research on high-rise concrete pumping technology has considerable practical value and economic significance for improving the construction quality and construction efficiency of super high-rise buildings. The 88th floor of the main building of Hong Kong International Financial Center, 420m high, is the fifth largest in the world and the tallest building in Asia. The maximum height of concrete pumping is 408m, which has high requirements on construction safety, reliability, environmental protection and automation. All the main buildings of C60 concrete are used to ensure project quality and structural strength, which poses a severe challenge to concrete conveying equipment. To this end in the concrete recipe has also taken some measures conducive to pumping, and the mixing station built in the site, about 300m away from the concrete pump to ensure that the concrete reaches the pouring surface within 20min, reducing slump loss. This project each layer of concrete dosage about 240m3, divided into two construction, using two Sany Heavy Industry HBT90CH-2122D high pressure concrete pump, while laying the same two sets of pipes, two pumps can be pumped at the same time. Pumping process in the 400m high concrete pump hydraulic system working pressure of 24 ~ 25MPa, concrete outlet pressure of 16MPa, 10 to 11 times per minute commutation, the delivery of about 40m3 / h. 2 Equipment status 2.1HBT90CH concrete pump 2.1.1 Technical Features 1) Double-power structure To ensure the reliability of the construction process, the whole power of two diesel engines were used to drive two sets of pumps. The application of dual power and power confluence technology, usually two sets of pump work at the same time, when a group of fault can cut off the group, the other group still maintain 50% of the displacement to continue to work to avoid interruption of the construction process. 2) Automatic high and low pressure switching hydraulic system High and low pressure pumping mode switching process all controlled by a computer, just press a button to complete the switch in an instant, without downtime, no pollution. 3) High-pressure concrete piston As pumping maximum height of 408m, the concrete inside the pipe counter-pressure on the concrete piston, according to the characteristics of this key operating conditions, the use of enhanced polyurethane material developed to adapt to the pumping structure of high-pressure concrete piston. 4) the ophthalmic plate, cutting ring hydraulic system high and low pressure pump mirror plate thrust, resulting in seal failure, and the pair of coupling between the seal is to ensure ultra-high-level pumping the key. HBT90CH concrete pump to reduce the flow of S pipe to reduce the thrust, while using high preload technology to make the cutting ring and the lens plate close fit, to ensure reliable sealing. 5) washing 408m super high-rise pump in the HBT90CH concrete pump is still used to pump how high, washed high this legendary and created the highest washing world record technology, concrete waste minimized to save the entire project Concrete 2640m3, equivalent to 1.9 million Hong Kong dollars. In addition, there is no residual concrete, which reduces the burden of sediment treatment and management and reduces the workload and cost of the construction process. 2.2 auxiliary equipment with engineering requirements supporting the design of a cloth radius of 32.5m tailless drag automatic climbing cloth rod, the main parameters of the cloth radius (m) 32.5 tower height (m) 31 climbing automatic continuous climb climbing speed (m /s)0.5 Total power (kW) 30 Total mass (t) 24 The cloth rod is driven by four hydraulic motor speed reducer units. The gear rack drives the cloth rod and the support frame to rise alternately to achieve the automatic continuous climb of the whole machine. Climbing process can be completed by 1 person operation. Due to the restriction of the structure of the building, the maximum span of the supporting rod of the fabric rod is up to 10m and the minimum is only 3.5m. Sany Heavy Industry has specially designed a large-span luffing beam for this purpose. 2.3 The delivery pipe at the pump outlet layout 100m horizontal pipe, 90 ° elbow 4, 45 ° elbow 1, 15 ° elbow 2; 140m high on the 32 floor, the layout of the 30m horizontal pipe, 90 ° elbow 3 in the 200m 45 layer layout 90 ° elbow 2; 55m in the 55 layer 90 ° elbow arrangement 2; and then has been up, the entire pipeline including the cloth machine tower exposed 10m, arm length 32m, Bend conversion 44m, a total length of 622m. Straight pipe ends are rigid support firm fixed. 3 pumping construction technology key high-rise concrete pumping construction there are many technical problems, should take the following measures. 3.1 Equipment pumping capacity Maximum pumping capacity of the equipment should have some reserves to ensure smooth delivery, to avoid plugging. In this pumping height of 408m, the working pressure of the concrete pump hydraulic system is 24 ~ 25MPa, the concrete outlet pressure is 16MPa, while the working pressure of the hydraulic system of the HBT90CH super high pressure concrete pump can reach 35MPa and the maximum pressure of the concrete outlet can reach 22MPa , Which is also the key factor for HBT90CH successfully pumping 400m super high-rise pumping. 3.2 The reliability of equipment configuration Equipment configuration should be based on the reliability of the principle of super high-rise concrete delivery of a reasonable layout of the pipeline is crucial, once the equipment failure to stop pumping more than 2h, the concrete will appear in the duct bleeding, Segregation, will make the entire piping system concrete scrapped and seriously affect the construction quality. Trinity HBT90CH pump with two engines, can work simultaneously to improve work efficiency, but also a separate operation, even if there is a failure of the standby engine to continue to work, greatly improving the reliability of the construction process. In addition, two independent pumps and piping systems are also a strong guarantee of smooth construction. 3.3 Ultra-high pressure resistant pipe system In the ultrahigh pressure pump, the maximum pressure in the pipe can reach 22MPa, longitudinal will produce 27t pull, must use ultra-high pressure resistant pipe system. In addition, the conventional connection and sealing methods can not meet the requirements, the following solutions need to be taken. 1) The use of ultra-high pressure pipe wall thickness 9.5mm above, to protect the pipe blast resistance. 2) The connection between the pipes is guaranteed by the strength of the screw, the longitudinal tension is borne by the screw, so that the joint can be reliably guaranteed. 3) with high-pressure concrete skeleton seal ring to prevent the concrete under the high pressure of 22MPa squeeze out from the pipe clip gap to ensure long-term reliable seal. 4) The smaller the pipe diameter, the greater the transmission resistance, but too large duct explosion resistance is poor, and the concrete flow in the pipe slow, long residence time, affecting the performance of concrete, the best choice of diameter 125mm transport tube. 3.4 reasonable pipe cloth pipe pouring program should be based on the concrete and less use of elbows and hoses, pipelines as short as possible to shorten the length. The project pipeline laying along the floor or wall, the concrete floor or wall with expansion bolts to install a series of bearings, each pipe by two bearings fixed. In order to reduce the pipe concrete back pressure in the pump outlet layout of the horizontal pipe and a number of 100m elbow, and achieved good results. 3.5 Properly applicable concrete mix The principle of mix design is not only to meet the strength, durability requirements, but also economical and reasonable, with a good pumpability, so in addition to the usual factors to be considered must handle the following aspects. 1) The amount of cement used for pumping high-rise concrete cement content must take into account the strength and pumpability, less than the amount of cement with less than strength requirements, too large then the viscosity of concrete, pumping resistance increases the increase pumping Difficulty, but also reduce the efficiency of inhalation. In this case, the amount of cement for the 375kg / m \ +3, in the construction has achieved good results. 2) coarse aggregate conventional pumping operation requires the maximum aggregate particle size and diameter ratio of not more than 1: 3; in the ultra-high-rise pumping prone to segregation due to pressure within the pipeline, the ratio should be less than 1: 5, Which sharp flat stones to less, so as not to increase the amount of cement. 3) Slump Ordinary pumping operation in the slump of concrete about 160mm most conducive to pumping, high slump easily segregated, low mobility is poor. In the ultra-high-rise pumping to reduce pumping resistance, slump should be controlled at 180 ~ 200mm, at the same time to prevent the segregation of concrete can be incorporated zeolite powder to reduce bleeding. 4) fly ash and admixture Fly ash and admixture can significantly reduce the amount of water used to improve the workability of concrete mix. However, due to more varieties of admixtures, adaptability to fly ash are also different, the optimal dosage should be determined by testing. 3.6 to ensure the continuous supply of concrete For concrete sticky, fast condensing characteristics, in order to ensure the homogeneity of the concrete, mixer to the pump feed reverse high speed rotation 20 ~ 30s, the pumping process should be carried out quickly and not Stop stirring, to avoid the concrete in the pumping process caused by the accumulation of long tube stuck phenomenon. 3.7 to ensure the smooth pumping of concrete pressure before the application of water wet pump hopper, pump room, piping and other parts in contact with the concrete, check the pipeline without exception before the use of cement mortar lubrication pressure delivery. When the pump is started to pump, the pump should be in a low-speed running state. Pay attention to observe the pressure of the pump and the working conditions of each part. After being smoothly pumped, the pump speed can be raised to normal. When the concrete pumping difficulties, the sudden increase in pump pressure will lead to pipe vibration, hit the pipe with a hammer to find the blockage of the pipe, using positive and negative pump jog handling or disassembly clean, after checking to confirm no blockage Continue pumping, so as not to damage the pump. During the construction, the pipe withdrawal method from far to near and the second pipe laying method are adopted. The direction of the concrete pouring is the same as the pumping direction. 3.8 Other precautions 1) Do not use the pipe that produces cracks and surface dents, the pipe clamp must be tight to prevent the pipe explosion from wounding; 2) timely fault handling and replacement of the necessary wearing parts; 3) after shutdown should be promptly cleaned and Pay attention to pump maintenance.
