Papers by Keyword: Rock

Abstract: This is accomplished by a variety of indoor rock mechanics experiments and experimental sound emission, taking Chengde area of Hebei Province the tunnel rock made of rock as research object to simulate various loading rock failure process. To analysis the data obtained of acoustic emission and Dynamics in the process obtaining the characteristic parameters of rock failure process in order to Monitor and Forecast. Through the three axial compression test and the process of acoustic emission signal acquisition discussed the relation between the mechanical parameters of rock acoustic emission parameters of stress. The characteristic parameters of acoustic emission signals with stress and time change through analyzing the acoustic Emission characteristics of each stage in the process of rock failure provide the basis for the prediction of rock burst.

Abstract: This paper carried out the experimental study on the thermal conductivity of rock in different depth by transient hot-strip method and the analysis on the reliability of the data. The results show that thermal conductivity of pelitic siltstone has been less affected by the varying versus depth of the rock stratum than tuff, but the thermal conductivity of tuff slightly higher than pelitic siltstone.

Abstract: The effect of rock properties on excavation-loading operation in quarries was investigated by conducting test on the mechanical properties of selected rocks. These rock samples were tested in the laboratory for specific gravity, point load strength, uniaxial compressive strength and mineral composition using weigh balance, point load tester, 1100kN compression machine and petrological microscope respectively. The filling rates of the front end loaders bucket were determined. The result obtained show that value of uniaxial compressive strength varied from 29.22 MPa-30.87 MPa. The bucket filling rate varied from 0.180-0.250 m³/s and 0.145-0.170 m³/s for porphyritic biotite granite and coarse biotite granite respectively. There is strong relationship between bucket filling rate and strength properties with values of R² ranging from 0.9737 to 0.9981.Therefore strength parameters of the rock have effect on excavation loading operation in quarries.

Abstract: Tunnel Boring Machine (TBM) is a major equipment used in underground engineering and Cutter disk system is its major parts, which affect sharply its capability. The force and vibration characteristics of the cutter system are simulated in this paper, and the effects of its force and vibration on the cutter system reliability are analyzed. These results show that there are the most stress and the worst reliability in these joints between the cutterhead and main driver, the cutterhead and the hob, and cutter ring. These research results are very helpful for increasing the reliability and application of the rock boring machine.

Abstract: This article is based on geological surveys combined with finite element and discrete element numerical simulation methods. In-depth analysis of the complex geological structure, deformation characteristics and stress - deformation problems of dumping rock, we clarify different deformation characteristics of deformable landslide inside, at the bottom and the deep part of trailing edge, and demonstrate the deformation will gradually shift from dumping to shear slip. Potential deformation failure mode will be dumped into the whole sliding - tension, which is controlled by the bottom broken belt, and potential deformation is mainly subject to the bottom fault F_207-3 of deformed rock and the dumping broken belt at the deep part of trailing edge.

Abstract: An new intelligent displacement back analysis, named as CACA-SVM, was proposed based on support vector machine (SVM) and Continuous Ant Colony Algorithm (CACA). On the one hand, CACA-SVM used SVM to build the nonlinear mapping relationship between them. On the other hand, CACA-SVM used the global optimization performance of CACA to search the optimal rock mechanics parameters in the global space. The nonlinear mapping relationship built by SVM can fit and forecast the measuring point displacements under different parameters with high accuracy, avoiding the complex numerical calculation. CACA can prevent object function from trapping in local optimum and improve precision of back analysis. Case study shows that the forecasting trend was in good agreement with the measured trend, which indicated that the model was suitable for solving the geotechnical engineering problem of nonlinearity and uncertainty and could well be applied to displacement back analysis.

Abstract: A new method of displacement back analysis, named SVM-CTS, was proposed based on support vector machine (SVM) and continuous tabu search (CTS). On the one hand, SVM-CTS used SVM to build the nonlinear mapping relationship between the measuring point displacements and rock and soil mechanics parameters of positive analysis based on the study samples. On the other hand, SVM-CTS used the global optimization performance of CTS to catch the optimal rock and soil mechanics parameters in the global space. The nonlinear mapping relationship built by SVM can fit and forecast the measuring point displacements under different parameters with high accuracy. CTS can prevent object function from trapping in local optimum and improve precision of back analysis. Case study shows that SVM-CTS can be well applied to the displacement back analysis in geotechnical engineering.

Abstract: A numerical implement to simulate the crack propagating process in arch dam and rock base has been put forward. A new remeshing strategy of FEM meshing grid was presented for improving the calculation accuracy and efficiency. In the period of dividing the dam structure and the foundation rock into an appropriate number of discrete subregion (finite elements), the adaptive element was used to divide the original 3-D element into 8 son-elements analogical to its father-elements entirely. Of course the 2-D element was divided into 4 son-elements analogical to its father-elements entirely using the same method. The element shape function was used to solve suspend nodal point. The arithmetic and shape function’s formulation also were put forward. To satisfy the engineering accurate result, the adaptive element was used to divide the son-element or the grandson-element again. In the calculating processor, the arithmetic of adaptive load step was presented. Only one element failures in a load step. So the cracking processor can be found with automatic mesh generation. An arch dam has been as example to validate the method is right and stability. The arithmetic has important theory and utility value.

Abstract: Rock tunnel boring machine is one of the main machineries and equipments for underground engineering, and the failure of tool systems is its main failure form. Rock hob test-bed is the only testing equipment for tool failure and wear. In this paper, the breaking rock by the double disc cutter is simulated and four kinds of rocks are selected to test the influece of rock characteristics and spacing between two disc cutters on the rock breaking by the double disc cutter test-bed. The results show that there is different optimal spacing between two disc cutters for different rock; the optimal spacing is inversely proportional to the hardness of the rocks; the maximum stress appears the boundary between the disc cutter and rock.

Abstract: By means of developing new rock abrasiveness device and using quenching steel spiral simulation micro-bit, the experimental investigation on rock abrasiveness that simulating the actual drilling surroundings in petroleum engineering had been conducted. based on the data of micro-bit’s wear weight, which broke unit volume rock, of which experimental samples are made from more than 850 cores of seven main geological profiles in Shengli oilfield, rock abrasiveness is divided into eight grades with Sturges empirical formula. The bit type selection and the bit life prediction could be conducted with the upper experimental method.