Microscopic Failure Mechanism Analysis of Rock Under Dynamic Brazilian Test Based on Acoustic Emission and Moment Tensor Simulation

The dynamic tensile failure of rock is a main failure mode in deep underground engineering projects. The microscopic failure mechanism analysis of this failure mode plays a key role in dynamic disaster warning. Moment tensor inversion is a very well-known method used to analyze failure mechanisms. However, an acoustic emission (AE) event cannot be accurately distinguished in rock dynamic experiments at the laboratory scale, because there are hundreds of AE events generated within a few hundred microseconds in one dynamic test. Therefore, moment tensor analysis is rarely applied in rock dynamic tests with laboratory scale. In this paper, AE and moment tensor simulations with the discrete element method (DEM) are introduced to analyze the microscopic failure mechanism of rock under a dynamic Brazilian test. Comparing the simulation results of AE and moment tensor analysis with the simulation results of micro-crack with DEM, the moment tensor discriminant method can obtain the mechanical mechanism and energy level of micro-cracks. Furthermore, R, which is the ratio of isotropic and deviatoric components of the moment tensor, is used to analyze the AE source mechanism. The implosion, shear, and tensile of the AE source mechanism can better explain the evolution process of main axial crack and the shear failure zones of the Brazilian disc specimen under dynamic tensile simulation. These findings contribute to a better understanding of the microscopic failure mechanism of rock under a dynamic tensile test than the statistical types of micro-cracks based on break bonds with DEM.

Analisis Potensi Tsunami Menggunakan Mekanisme Fokus (Studi Kasus Gempa 15 November 2014

Lempeng laut Maluku merupakan lempeng mikro yang berada di antara lempeng mikro Sangihe dan Halmahera yang bergerak berlawanan arah, kondisi ini mengakibatkan kegempaan daerah Sulawesi Utara dan sekitarnya terkonsentrasi di sebagian besar wilayah Laut Maluku dan sisanya terjadi di Laut Sulawesi. Adapun tujuan penelitian ini adalah untuk menentukan karakterisik pola patahan akibat gempabumi tanggal 15 November 2014 di Laut Maluku koordinat 10 LS – 30 LU dan 1200 - 1300 BT dengan sumber data dari katalog gempa bumi USGS dan Global Centroid Momen Tensor. Analisis bola fokus bahwa gempa tanggal 14 November 2014 dengan koordinat 10 LS – 30 LU dan 1200 - 1300 BT adalah kombinasi sesar mendatar dan sesar naik atau jenis sesar ini disebut juga oblique. Hasil analisis menggunakan Sofware WinITDB dan perhitungan rumus empiris menunjukkan bahwa terjadi deformasi di dasar laut 1,409 m, yang menyebabkan terjadinya Tsunami yang kecil, karena deformasi yang terjadi belum cukup kuat pengaruhnya untuk merobek permukaan dasar laut.Molucca Sea plate is the plate between the micro’s plate Sangihe and Halmahera are moving in opposite directions, these conditions result in the regional seismicity of North Sulawesi and the surrounding area is largely concentrated in the Molucca sea and the rest occur in the Celebes Sea. As for the purpose of this research is to determine the result of fracturing pattern karakterisik gempabumi November 15, 2014 in the Molucca sea coordinates 10 LS – 30 N and 1200-1300 BT with the source data from the USGS earthquake catalogs and the Global Centroid Moment Tensor. Analysis of the focal sphere that the earthquake on 14 November 2014 with coordinates 10 LS – 30 N and 1200-1300 BT is a combination of horizontal fault and fault ride or any type of fault is also called oblique. The results of the analysis using WinITDB Software and calculation of empirical formula indicate that occurs on the ocean floor deformation 1.409 m, which led to a small Tsunami, because deformations that occur are not yet strong enough to rip his influence the surface of the seabed.