# Static Analysis of Underground Ant Nest Structures
## 1 Introduction  
Ants are insects belonging to Insecta, Hymenoptera, Formicidae. They are the dominant group of insects and the most widely distributed and numerous social insects on earth [1]. They are extremely adaptable to the environment and can be found in all corners of the world, whether in arid deserts, wet river beaches, high-temperature tropical regions or cold arctic regions. As excellent architects of nature, they can build all kinds of nests, including above-ground ant nests, underground ant nests, tree ant nests and above-ground and underground compound ant nests, for the purposes of living, breeding and storing food. After hundreds of millions of years of selection by nature, each ant nest structure has the most reasonable structural form, providing the most comfortable living environment for the ants [2]. Among them, the underground ant nest is a nest dug out by the ants in the soil that usually has two basic units: a nest chamber and a channel. The distribution of underground nests is very extensive, and such nests can be seen in woods, field paths, along roads and even in deserts. Depending on the number of individuals in the ant colony and the degree of growth of the ant nest, the size of the underground ant nest is also different. Small nests have only a few chambers and a channel leading to the ground, whereas large ant nests can extend several meters underground, and thousands of chambers are connected to each other to form an ant kingdom. Natural underground ant nests generally have good air circulation, suitable temperature and relative humidity, and they are surrounded by trees and natural barriers. At the same time, they also have good physical structures, compression resistance, water resistance, heat preservation and moisture resistance [3]. For underground nests built on embankments, the chambers and channels are usually reinforced with'mud-retaining walls'. The mud-retaining walls are made by mixing the saliva of ants with the soil. After drying, they have higher strengthand stability than ordinary soil, which can ensure that the ant nest channel and the soil inside the nest chamber do not collapse [4]. At present, there are only a handful of people who study the structure of underground ant nests in China. Most of the reports on underground ant nests are from foreign researchers on the structure of underground ant colonies, mostly on the form of the ant nest structure [5; 6] and mainly in terms of the site selection of the ant nest, the size of the nest, the depth of the nest, the number of chambers, the interaction between the chambers and the number of entrances. By excavating and casting underground ant nests with liquid metal, paraffin wax, etc., measuring the size of the casting model, counting the number of chambers and describing the distribution and respective functions of various chambers, the channels and detailed structures in the ant nest. [PERSON] et al. studied Mycetagroicus inflatus and their nests and found that the nest generally consists of only three chambers; each spherical chamber is connected by a vertical downward channel, and there is no connection between chambers [7]. [PERSON] et al. found that computerized tomography and finite element models can be used to study complex anthill structures, and the results showed a high degree of consistency [8]. Researchers have also found that the nest structure is not exactly the same for the same type of nest and that the size and depth of nests, the diameter of the channels and the number of entrances can change depending on the existence time of the ant nest, the local climatic environment and soil conditions [9], with the number of nest chambers becoming larger and more numerous as the colony grows and the diameter of the channels often related to the size of the ants. However, little consideration has been given to the mechanical analysis of these underground exquisite ant nest structures.