# Safety Evaluation of Crossing Tunnel Engineering: A Case Study
## 1 Introduction  
With the rapid development of China's economy in recent years, there has been an increasing demand for transportation. In order to meet the transportation demands, a considerable number of new road projects are being implemented, resulting in a proliferation of existing roads intersecting or running parallel to one another, and leading to the rise of road-related projects [1]. The construction of road-related projects poses significant risks for existing road infrastructure, especially for road tunnels which require excavation and explosion [2; 3]. During the construction process of such projects, blasting vibrations induced by new tunnel excavation may cause fissures, cracks or even collapse in medium and harder rocks [4; 5; 6; 7], and cause ground collapse in strongly weathered rock mass [8; 9; 10], thereby compromising road safety. Consequently, it is of immense significance to conduct technical assessments on the safety of road-related projects [11]. On-site observation and monitoring is the most widely employed approach for evaluating the safety of such projects. By documenting deformation and failure characteristics before and during construction, the safety of the construction process can be effectively appraised [12; 13; 14; 15]. The physical model test method shrinks the tunnel in equal proportion, and studies the stability of the project by reducing the true stress state of the surrounding rock [16; 17; 18]. By changing the inclination angle of the ground surface of a geotechnical model with a scale factor of 1/20, [PERSON] [19] studied the change laws and distribution forms of structural stress and the failure mechanism of tunnel under different unsymmetrical pressures. However, both the on-site observation and physical models have drawbacks as are they costly and time-consuming [20]. The development of computer technology has led to the widespread adoption of numerical simulation in the field of safety assessment [21; 22; 23; 24]. In the evaluation of tunnel support design, [PERSON] [25] employed a finite element numerical simulation analysis to predict the vertical displacements of a tunnel duringits construction. [PERSON] [1] investigated the effect of blast-induced vibration from a new railway tunnel on an existing adjacent railway tunnel. [PERSON] [26] studied the interaction mechanism between a tunnel, protection technique, and soil. Various soft computing techniques involving data mining and machine learning have also found their application in the tunnelling-related problems [8]. Hybrid neural network approach is used to predict ground settlements induced by building shield tunneling [27]. In addition, artificial neural networks (ANNs), radial basis functions (RBFs), decision trees (DTs), random forest (RF) method, support vector machines (SVMs) are also wildly applied in the prediction of engineering response of tunnels and underground excavations [28; 29; 30; 31; 32; 33]. To improve the accuracy of the safety determination, fuzzy analytical hierarchy process (FAHP) is introduced in the field of tunnel safety assessment, which has greater convenience and consumes less time [34]. However, the above studies evaluate the safety of tunnel construction from a single aspect, and fail to comprehensively evaluate the risks of tunnel construction from an engineering reality perspective. This article takes the project of the Jijiapo highway tunnel overpass on the newly built Yangmuling railway tunnel as the engineering background. By combining laboratory experiments, on-site monitoring data, and numerical simulation methods, the blasting design and corresponding parameters are adjusted to mitigate the maximum vibration velocity resulting from the blasts and ensure construction safety. A numerical calculation model was established using the finite element numerical software Midas GTS. The influence of the new railway tunnel construction on the existing highway tunnel was analyzed from both static and dynamic responses.