Abstract: The present disclosure provides a risk assessment method of water inrush in tunnels constructed in water-rich grounds. The method includes the following steps: simulating a tunnel excavation process by finite element software MIDAS GTS NX and fluid-structure interaction; according to a research method of control variables, analyzing effects of a groundwater level, an elastic modulus and advanced pipe shed grouting on the stability of surrounding rock, and improving an algorithm of a radial basis function (RBF) neural network using a Grey Relation Analysis (GRA)-based Partitioning Around Medoid (PAM) clustering algorithm to assess risks of water inrush occurring in Qingdao area.

Abstract: The present disclosure provides a multi-factor quantitative analysis method for deformation of a neighborhood tunnel. The method includes the following steps: analyzing monitoring data generated at a tunnel site; simulating collapse occurring at a shallow buried section of a tunnel; determining the degree of influence of each factor on the tunnel and a stratum; and determining quantitative influence of each factor on tunnel deformation. The present disclosure can not only provide an accurate theoretical basis for the construction of the shallow buried section of the small-distance tunnel, but also guarantee safety and cost saving during tunnel construction.

Abstract: A printed circuit board (PCB) is provided. The PCB includes a first microwave board material, a second prepreg, and a third ordinary board material that are pressed together. The first microwave board material, the second prepreg, and the third ordinary board material are provided with an opening respectively. At least two openings have different sizes. In a region between boundaries of the at least two openings having different sizes, a borehole is provided to pass through the board material in the region. A back-drilled hole is selectively used. A radio-frequency device and a method for manufacturing a PCB are further provided. Thus, it is suitable for designing different power modules and other circuit modules on the same single board, and is compatible with the existing basic PCB manufacturing technologies, which further has a low cost, and can meet the requirements of large-power radio-frequency circuits with different frequencies.

Abstract: A printed circuit board (PCB) is provided. The PCB includes a first microwave board material, a second prepreg, and a third ordinary board material that are pressed together. The first microwave board material, the second prepreg, and the third ordinary board material are provided with an opening respectively. At least two openings have different sizes. In a region between boundaries of the at least two openings having different sizes, a borehole is provided to pass through the board material in the region. A back-drilled hole is selectively used. A radio-frequency device and a method for manufacturing a PCB are further provided. Thus, it is suitable for designing different power modules and other circuit modules on the same single board, and is compatible with the existing basic PCB manufacturing technologies, which further has a low cost, and can meet the requirements of large-power radio-frequency circuits with different frequencies.