Three dimensional mechanical numerical analyzing on mine pass construction of metal mine
Mine use sublevel caving method, in the production process, the mine pass is an essential ore transport channel, in the production plays an very important role. Therefore the stability of the chute is an important technical support of the mining production and the safety in underground metal mines. Taking a sublevel caving method mining as the research background, Using the MIDAS / GTS finite element software to do numerical analysis of the chute excavation and support of three-dimensional mechanical problems. Results show that: After chute excavation, the wall within 0.3m of a significant displacement, shift several millimeters; different levels of access road excavation, the wall is affected little, But the access road junction with the chute significant displacement, especially with the chute increase the depth of wall the displacement increases; Slip road connecting the wells and different levels of support according to the design parameters, the effect of displacement control of the range of wall displacement and the interchange of access road and chute is significant.
Numerical modelling of three-dimension stress rotation ahead of an advancing tunnel face
As underground excavations and construction works progress into deeper and more complex geological environments, understanding the three-dimensional redistribution of excavation-induced stresses becomes essential given the adverse consequences such stresses will have on the host rock strength and the subsequent excavation stability. This paper presents the results from a detailed three-dimensional finite-element study, which explores near-field stress paths during the progressive advancement of a tunnel face. These results demonstrate that as the tunnel face approaches and passes through a unit volume of rock, the spatial and temporal evolution of the three-dimensional stress field encompasses a series of deviatoric stress increases and/or decreases as well as several rotations of the principal stress axes. Particular emphasis is placed on the rotation of the principal stress axes as being a controlling factor in the direction of fracture propagation. If this orientation changes in time, i.e. during the progressive advancement of the tunnel face, the type of damage induced in the rock mass and the resulting failure mechanisms may also vary depending on the type and degree of stress rotation. The significance of these effects is discussed in terms of microfracture initiation and propagation, brittle fracture damage and rock strength degradation. Further analysis is also presented for varying tunnelling conditions including the effects of tunnel alignment with respect to the initial in situ stress field, excavation sequencing and elastoplastic material yielding. Implications with respect to the new Gotthard base tunnel, currently under construction in Switzerland, are presented using examples from the nearby Furka tunnel. r 2001 Elsevier Science Ltd. All rights reserved.
ANALYSIS OF BOLT′S ANCHORING QUALITY BASED ON WAVELET NEURAL NETWORK
The dynamic response of bolt achieved by impact-echo method can be effected easily by some factors.It′s difficult to classify bolt′s anchoring quality according to the dynamic response of bolt.In this paper,a new analytical method of bolt′s dynamic response is put forward.The new analytical method combing with advantages of wavelet analysis and artificial neural network is presented.Firstly,the dynamic response of bolt by numerical simulation software FLAC3D is obtained.Secondlyt,he features are extracted from the dynamic response of bolt by wavelet analysis.Thirdlyt,hese features are fed into the artificial neural network for training.Finallyt,his artificial neural network to classify the bolt′s anchoring quality intelligent according to the dynamic response of bolt is employed.In order to validate this new analytical method,some practical signals of bolt′s dynamic response are used for the test.The results indicate that the new analytical method is practicable.