In order to study on the vibration effect of the blasting in the upper and lower cross tunnels, depress the impact of blasting vibration on existing adjacent tunnel and acquire the sound way of tunnel blasting construction, the finite element software LS-DYNA was adopted to calculate what vibration effect of existing tunnel would be generated by the different detonation modes (simultaneous initiation and hole-by-hole initiation) and the different cut modes (parallel cut and oblique cut). In general, the results of numerical simulation compared with the results measured in real, they are generally consistent. Results show that the vibration velocity of hole-by-hole initiation of digital electronic detonator is 40% lower than ordinary simultaneous initiation of millisecond detonator, and the vibration acceleration is reduced by 24%. As regards vibration displacement, the distinction between the two detonation modes is small. The rule of velocity decay with increasing distance from the initiating position is similar in this two cases. Meanwhile, the vibration velocity of oblique cut is lower than parallel cut. But, for the vibration acceleration, the oblique cut is 15% higher than parallel cut. For oblique cut, the seismic waves show a pronounced periodicity and the energy is relatively concentrated. The fact is quite opposite when the parallel cut applied. In the case of explosion of hard rock strata, the effect of oblique cut is better than parallel cut. KEY WORDSTunnel engineering, Explosion vibration, Numerical simulation, LS-DYNA In recent years, with the rapid economic growth in China and the booming development of the national transport industry, the subway construction has become an essential development project in large and medium-sized cities. In that cities, such as Chongqing, Xiamen and Qingdao, the drilling and blasting method usually used to subway construction in hard rock strata. In addition, Article no. 16 THE CIVIL ENGINEERING JOURNAL 2-2019-` due to the outward expansion of the city and the characteristics of the original terrain, a lot of "mountain city" appeared. As a result, many mountain hard rock tunnels have emerged in the construction of municipal roads and subway traffic. So, the surrounding buildings, especially cultural building relics, will be impacted by blasting construction in central urban area. How to choose a reasonable tunnel blasting method to reduce the impact of blasting vibration on the surrounding buildings is a considerable issue.As the science and computer technology progressed, the method of numerical simulation of blasting vibration effect and evaluating structural safety is widely used. Singh P K (2002) delved into the destruction problems of underground tunnels in the effect of adjacent tunnel blasting [1] . There are research results indicate that blasting vibrations induced by a new tunnel excavation might cause spalling, fissures, or even collapse of existing tunnel linings [2] . Yao et al. (2004) conducted numerical simulations on the blasting construction process ...

Geotechnical engineering material is a kind of heterogeneous composite material. The stone, mineral, gravel, hole, and crack contained in it have different physical and mechanical properties, and their responses to external forces are very different. For example, stress distribution, crack propagation, and failure mode are closely related to material heterogeneity and microstructure. This paper presents a finite element model method for processing CT images of geotechnical materials by using digital image technology. This paper presents a finite element model method for processing CT images of geotechnical materials by using digital image technology. The theory of digital image processing is applied to geotechnical CT image processing to realize pseudo-color enhancement of CT image, and the histograms of different geotechnical CT numbers are obtained. Canny operator is used to detect the edge of geotechnical CT image, and the binary image of geotechnical microstructure is obtained. According to the color change of pseudo-color enhanced image and CT histogram, the meso-structure and variation of rock and soil can be quantitatively analyzed. The finite element model established by this method can fully consider the heterogeneity of geotechnical materials, especially the effect of void distribution on the mechanical properties of geotechnical materials.