Research on rock hand specimen naming method based on deep learning and Inception-v3 model

The naming of rock hand specimens is usually conducted by geological workers based on observed mineral composition,texture characteristics,etc.,combined with their own knowledge reserves.The accuracy of identification results is limited by the experience,research interests,and identification level of the identifier,as well as the complexity of the rock composition.To improve the efficiency of rock hand specimen identification,this paper proposes a method for rock image recognition and classification based on deep learning and the Inception-v3 model.It encompasses the preprocessing of collected photographs of typical intrusive rock hand specimens,along with augmenting the sample size through data augmentation methods,culminating in a comprehensive dataset comprising 12501 samples.Experimental results show that the model has good learning ability when there is sufficient data.Through iterative training of the Inception-v3 model on the rock dataset,the accuracy of rock image recognition reaches 92.83%,with a loss of only 0.2156.Currently,several common types of intrusive rocks can be identified:gabbro,granite,diorite,peridotite,granodiorite,diabase,and granite porphyry.Software is developed for open use by geological workers to improve work efficiency.

Experimental investigation on hard rock fragmentation of inserted tooth cutter using a newly designed indentation testing apparatus

This investigation aims to explore the effects of stress conditions and rock cutting rates on hard rock fragmentation through indentation tests on a newly designed triaxial testing apparatus.This apparatus was designed to realize a triaxial loading and indentation test of cylindrical specimens using inserted tooth cutter.The boreability and crushing efficiency of granite rock was investigated by analyzing the change rules of the thrusting force,penetration depth,characteristics of chippings and failure patterns.Several quantitative indexes were used to evaluate rock boreability in this investigation.The granite rock samples all had a chiselled pit and a crushed rock core.Under initial stress conditions,only flat-shape chippings were stripped from the rock surface when the thrusting force reached 20 kN.The rock cutting special energy had a close correlation with the initial stress conditions and inserted tooth shape.Moreover,a thrusting force prediction model was proposed in this paper.The contribution of this study is that for the first time the influence mechanism of the initial triaxial stress conditions on rock fragmentation is investigated using an inserted tooth and the newly designed testing apparatus.This study has a crucial importance for practical underground hard rock crushing in geoengineering.

Effect of size on characteristic of acoustic emission in rock specimen

A series of uniaxial-compression tests were conducted on some granite speci- mens.A multi-channel,high-speed AE signal acquiring and analyzing system was em- ployed to acquire and record the characteristics of AE events and demonstrate the tem- poral and spatial distribution of these events during the failure process.The test results show that in the primary stage,many low amplitude AE events are developed rapidly and distributed randomly throughout the entire specimens.In the second stage,the number of AE increases much slower than that in the first stage,while the amplitude of most AE events became greater.Contrarily to the primary stage,AE events clusteres in the middle area of the specimen and distributes vertically conformed to the orientation of compres- sion.The most distinct characteristic of this stage is a vacant gap formed approximately in the central part of the specimen.In the last stage,the number of AE events increases sharply and their magnitude increases accordingly.The final failure location coincidently inhabited the aforementioned gap.The main conclusion is that most macrocracks are de- veloped from the surrounding microcracks existed earlier and their positions occupy the earlier formed gaps,and the AE activity usually becomes quite acute before the main rup- ture occurs.

Numerical analysis on the influence of rock specimen size on crack stress field

In the simulation of rupture processes of seismic sources by using either numerical method or rock mechanics experiments, improper setting of the specimen size will influence the stress field near the faults. In this study, 2D finite element method (FEM) was used to calculate the stress field of rock specimens in different sizes with fixed-size elliptic holes. The calculated stress field was compared with analytic solution for elliptic-hole problem in an infinite medium. Numerical results showed that boundary effect of a rock specimen with an elliptic hole on stress field under uniaxial compression cannot be neglected. Critical aspect ratio of the specimen is about 3:2, and critical ratio of distance between the tip of the hole and the border of specimen (d) to the major axis of the elliptic hole (l) is about 7.3. Numerical analysis on rock specimen size can provide theoretical reference for rock specimen experiments, and it is also helpful for setting of model sizes in numerical simulations of fault movement.

Real-time computerized tomography(CT) test of failure process of jointed granite under unloading in three gorges project(TGP)

This paper deals with the real-time computerized tomography(CT) test for moni- toring the complete damage failure process of a single-crack granite specimen that is subjected to the confining pressure unloading. For this purpose, the State Key Laboratory of Frozen Soil of China has developed a special CT Triaxial Testing Equipment for Rocks and Soils that can give clear images of complete failure process of a rock specimen during removal of confining pressures, including various stages of development and penetration of cracks etc. The results have shown that it is easy for failure phenomenon to happen suddenly in the process of unloading condition of jointed rocks.