Displacement Prediction of Surrounding Rock in Tunnel Based on cellular ant algorithm

The deformation of tunnel surrounding rock is the key factor to analyze the stability of surrounding rock. However, due to the influence of many factors and the strong non-linear relationship between the factors, it is difficult to predict the deformation effectively. In this paper, a method based on cellular ant neural network model is proposed to simulate the displacement of surrounding rock with time. The results show that this method is efficient and feasible, and can meet the requirements of engineering and control.

Analysis of suspension bridge tunnel-type anchorage construction on the stability of surrounding rock

In order to study the interaction between the left and right tunnels of suspension bridge tunnel-type anchorage, the finite difference numerical software is used to analyze the mechanical properties of the surrounding rock during the construction process. A numerical analysis model based on FLAC3D is established to analyze the stress, displacement and plastic zone changes of the surrounding rock of right tunnel anchor cavern during the construction of left tunnel anchor cavern. The right tunnel anchor cavern is excavated firstly, and then the left tunnel anchor cavern is excavated. The numerical simulation results show that the main displacement of the right tunnel occurs in the construction stage of the anchor plug body and the rear anchor cavern of the left tunnel. During the excavation of the left tunnel, the plastic zones of the left and right tunnel anchor caverns are only connected above the middle of the waist wall. Therefore, it is suggested that during the construction process, especially in the excavation stage of the anchor plug body and the rear anchor cavern, the area above the middle of the tunnel waist wall should be strengthened in time to ensure the construction safety.

Study on the Stability of Surrounding Rock of Underground Circular Cavern Based on the Anchor Reinforcement Effect

Achieving a comprehensive and accurate understanding of the anchor reinforcement mechanism and a quantitative evaluation of the surrounding rock’s stability for an anchored underground cavern can provide an important theoretical basis for supporting and excavating the cavern. First, the composite bearing structure composed of the anchor and surrounding rock was defined as the surrounding rock reinforcement body by using the homogenization method, and a new method for evaluating the stability of surrounding rock by the surrounding rock reinforcement body deformation and damage degree was proposed. Second, based on the anchor reinforcement effect, the expression of the physical-mechanical parameters of the surrounding rock reinforcement body was deduced, and the analytical solution of stress and displacement of the surrounding rock reinforcement body was obtained. Finally, the stability coefficient of surrounding rock indicating the degree of the surrounding rock reinforcement body damage was defined. The research showed that the theoretical solution agreed well with the results of the numerical simulation, and the difference between the theoretical solution and the monitoring value was less than 10%, which verified the reliability of the method and the results of this paper. The design of the length and spacing of the anchor followed the principle of long but sparse and short but dense, and the pretightening force of the anchor and the stability coefficient of surrounding rock varied linearly. The analytical solution of this paper provides a theoretical reference for understanding the mechanism of anchor support and provides a quantitative evaluation method for the stability of surrounding rock. Compared with the traditional support design, the theory of this paper gives full play to the self-stability of the surrounding rock and the strength of the anchor, which is conducive to saving support costs and avoiding the construction limitations in some projects.

The Supporting Technology Research in Large Section Inclined Shaft with Fracture and Soft Surrounding Rock

This paper is based on the large section inclined shaft crossing goaf of Pingdingshan No.6 Mine as engineering background, and aimed at solving the difficult supporting problem of fractured surrounding rock. After establishing and calculating the mechanical models of U-steel and inverted arch, the support’s vertical reaction force (N1) and horizontal counterforce (X1) are determined as 180.96 KN and 48.12 KN, while the maximum bending stress (σmax) and ultimate bearing capacity of the inverted arch are obtained as 375.59 Mpa and 0.27 Mpa. It shows that the deformation of surrounding rock is well controlled by the supporting structure. The numerical simulation model is built by using the software FLAC3D to analyze the stability of surrounding rock after supporting. The results suggest that the deformation of roof, floor and sides is reduced by 17%, 23% and 71% respectively after supporting with U-steel in the inclined shaft, and the accuracy of results has been verified by a field experiment. Therefore, the “U-steel+ pouring concrete + inverted arch + backwall grouting” technology can effectively control the damage of surrounding rock and improve the stability of surrounding rock.