L68A1 Mast Section Common practice and recommended practice of track type tower crane foundation
The common practice of the track tower crane foundation is: first, tamp the foundation or make a layer of 37 ∶ lime soil cushion, then pave the gravel ballast, then place the wooden sleeper, and lay the rail on the wooden sleeper. This method is not suitable for heavy tower crane because of its large wood consumption and short service life. Today's recommended practice is to erect reinforced concrete base plate or reinforced concrete rail sleeper beam on the compacted foundation, fix and install I-beam on the base plate or sleeper beam with embedded parts, and then install steel rail on the I-beam. In order to improve the efficiency of track laying and save the cost of track laying, reinforced concrete sleeper beam, I-beam support and rail are often assembled together to form a 12.5m long fabricated reinforced concrete rail foundation. This kind of track foundation is very suitable for fo / 23B, HK40 / 21b, H3 / 36B and other heavy-duty self elevating tower cranes.
In the foundation with high ground endurance, this kind of concrete foundation plate can be taken as 200 cm × 200 cm × 50 cm. The top and bottom of the plate should be reinforced in two directions. If the tower crane must be installed near the deep foundation pit, the bored cast-in-place pile cap foundation shall be adopted to ensure the firmness and stability of the tower crane foundation, and measures shall be taken to prevent the slope collapse of the foundation pit.
The foundation of the fixed self elevating tower crane of the tower body must meet two requirements: one is to evenly transmit the upper load of the tower crane to the foundation and not to exceed the ground endurance; the other is to ensure that the tower crane can maintain the overall stability without tipping under various adverse conditions. Therefore, the foundation volume of the tower crane is quite large, and the foundation weight is equivalent to the weight of the tower crane's weight. The foundation weight of the fixed tower crane is closely related to the free height of the tower crane. The higher the free height, the greater the foundation weight. Taking fo / 23B tower crane as an example, when its free height is 59.8m, the concrete foundation size needs to be 6.5m × 6.5m × 1.7m. If the tower crane needs to be erected near the deep foundation pit in the foundation construction stage, and the surface soil condition is relatively poor, the foundation must also be supported by bored pile. Therefore, in order to save the cost of foundation construction, the whole mass concrete foundation should be divided into several prefabricated concrete blocks to form a prefabricated reinforced concrete foundation, so as to achieve repeated use and minimize the cost of tower crane foundation decomposed to each project.
