Experimental study on the distribution of earth pressure through three-dimensional trapdoor tests

In order to clarify the mechanical behavior in tunnel excavations, the authors develop and perform three-dimensional trapdoor experiments. The influence of excavations is considered in the experiments. Based on the results, the distribution of earth pressure is found to greatly affect the process of the excavations. It can be confirmed, therefore, that a higher level of earth pressure is working on a ground where loosened conditions occur due to a previously lowered trapdoor.