Many areas in China are located in the karst dispersal area. There are many open karst caves, which spread widely and in varying depths. The outer cover layer of karst caves is mostly soft soil layer, so the bearing capacity is small. When constructing highways in these sections, it is difficult for traditional construction methods to deal with such problems as lack of bearing capacity of embankment foundation (especially high fill embankment) and construction of bridge pile foundation passing through large karst caves.
The bored column geological map of the pile foundation of a bridge on a highway under construction in our province shows that 32.2-60.5 meters below the surface is a karst cave, and the upper surface of the cave has a cover layer of nearly 32 meters, and it is a sandwich between soft clay and sand. The original plan of a bridge built here considers the difficulty of the construction of the pile foundation of the bridge and the possibility of the pile foundation of the highway bridge being operated on the left and near in the construction process. The negative impact brought by the original bridge construction plan had to be replaced by filling roadbed, but due to the high filling, the conventional filling construction method may present problems such as the lack of bearing capacity of the foundation and the large settlement of the soft foundation after construction. If the construction of this roadbed is stopped by mixing light soil with air bubbles, the difficult problems that can not be solved by other methods can be solved better: changing the bridge into a new one. For the light embankment, the pile foundation construction in the original karst cave area has been cancelled; the volume weight of the foamed lightweight soil embankment can be adjusted to one fourth of the ordinary embankment, which can restrain the lack of bearing capacity of the foundation; greatly reduce the settlement of the embankment after construction; and greatly shorten the construction period.
With the gradual application of foam concrete in other aspects, the proportion of this application will definitely drop, but it will still adhere to a higher proportion. From the perspective of development, the application of foam concrete in open backfill, retaining wall, trash cover, foundation treatment and other projects will be increasingly expanded. Although its application in these aspects is not improved, the total amount of application will be considerable once it is implemented because of the considerable amount of engineering. With the development and improvement of the application technology of foam concrete, its application scope will expand year by year, and the prospect is very wonderful. At present, organic thermal insulation materials account for more than 90% of the total thermal insulation data market, which is also the main reason for the high incidence of fire. The market urgently needs building thermal insulation materials which are energy-saving and fire-proof.