Fault Area Research Articles

Experimental Study on Strength Anisotropy of Loess in Near-Fault Area

The anisotropy of loess has been widely studied. However, most studies only consider the difference in soil quality and do not consider the impact of special areas. In addition, the conclusions of scholar researches are differences, and not representative. With the development of underground engineering construction, the direction of principal stress of loess is no longer just vertical, and the study of loess anisotropy has become a key issue. Therefore, this study takes the loess near-fault area of the Lishan piedmont fault as the research object, the differences of shear strength parameters in different directions were studied by routine triaxial shear test. The results show that the anisotropy of loess in this area is obviously different, which is greater than that of loess in other sites. The difference mainly reflect in the cohesion. The cohesion of the sample of the θ=90° is 1.62 times that of the sample of the θ=0° about. The difference of saturated loess is decreases, and the difference of cohesion is about 30%. The results provide a reference for the construction of the underground engineering for this areas, the engineering construction should pay attention to the difference in the strength and deformation on different directions of the loess.

Service Restoration in Distribution Systems based on Optimal Scheduling of Search for Fault Location and Switching Operation by Crews

The service restoration within a short period, performed when the permanent fault occurs in a distribution system, is essential for high supply reliability. The service restoration can be achieved by searching the fault location and controlling switches to isolate the fault area. However, the service restoration faces difficulties in the uncertainty of the fault location and the multiple crews' scheduling of the switching operations. It is important to search for the unknown fault location efficiently and optimize the crews' scheduling for their service restoration procedures. This paper proposes an optimization method of the service restoration procedures performed by crews considering the search of the unknown fault location by crews to handle the difficulties. The proposed method combines an efficient fault location search with scheduling for multiple crews. We formulate the scheduling problem as a mixed-integer linear programming problem which allows us to schedule the procedures efficiently using optimization solvers. The proposed method is verified by the computational experiments using the large-scale distribution system model with many manual and remote switches.

Building Resilience through Sustainable Tourism: A Case Study of Lembang and Greater Bandung Area

Owing to frequent tectonic activities, the Lembang Fault area in Java Island is highly vulnerable to disasters. Encompassing 51 villages along the fault, this region has witnessed rapid economic growth, transforming it into a sought-after tourist destination. The objective of this research is to map the levels of economic activity in the area and offer recommendations for sustainable economic development. The methodology employed encompasses data collection, in-depth interviews with agencies, business stakeholders, and developers, literature review, and research analysis. The findings of this study indicate that the areas situated along the fault corridor face significant disaster risks while exhibiting substantial economic activity. By utilizing recommendation maps and insights gleaned from interviews, it is determined that the most suitable area for further development lies on the north side of the Lembang Fault corridor. This research strives to provide valuable recommendations for future studies concerning economic sustainability in disaster-prone areas, specifically focusing on the Lembang Fault area. It contributes to enhancing our understanding of economic resilience in vulnerable regions and emphasizes the critical role of sustainable economic development in mitigating disaster risks.

Estimating Impacts of Tsunami on Buildings around Ambon Bay of Indonesia

Ambon is a city situated inside a long bay in eastern part of Indonesia. The city has been stricken by a number of tsunamis in the past. The last tsunami event was generated by a submarine landslide inside the bay that hit two villages in the city in 1950. Despite the long story of tsunamis inside the Ambon city, no study has been conducted to estimate the impacts of future tsunamis on the growing coastal area of Ambon. This study was aimed at assessing the building vulnerability in Ambon due to projected impacts of future tsunamis. A numerical simulation was performed to generate tsunami inundation areas in the city using Cornell Multi Grid Coupled Tsunami Model (COMCOT) based on maximum fault area in the segment. A series of field works to classify the building types in the city were performed in May 2023 on around 70,000 units of buildings along the bay of Ambon. The classifications were done using Hazard United States (HAZUS) frameworks. Tsunami fragility curves were used to estimate the impacts of the tsunami based on flow depths obtained from the numerical simulations. Based on the surveys, this study found that buildings within 200 m from coastline of the bay could be in Damage State 4 (DS4) which is the most severe impacts of tsunamis on buildings.

A Call for Inclusive Disaster Risk Financing in Indonesia: Addressing Vulnerabilities in High-Risk Areas

Earthquakes are a growing threat to Indonesia, with limited resources for risk mitigation. The current reliance on government relief is unsustainable. Despite Law No. 24/2007 on Disaster Management, inclusive disaster risk financing schemes have yet to be established. This study aims to provide evidence for disaster risk financing strategies in Indonesia, focusing on geological disasters in active fault areas with high population density. Aligned with the Sendai Framework for Disaster Risk Reduction (SFDRR) Priority 2, this study seeks to address the financial impact of disasters on governments and societies. By analyzing responses to risk financing following the November 21, 2022 earthquake in Cianjur Regency, this study examines emotional reactions, risk perceptions, and willingness to participate in risk insurance. The findings highlight low participation in insurance programs due to limited insurance literacy and low enrollment in micro earthquake insurance. Material losses from the Cianjur earthquake impose a significant financial burden on the government. There is a critical need for disaster insurance schemes, especially for homes and fixed assets at high risk of land loss due to landslides. Willingness to participate varies among different socioeconomic backgrounds. This article emphasizes the urgency of implementing disaster risk financing in Indonesia, with a focus on the vulnerability of poor and low-income households.

Mathematical modeling the quarry wall stability under conditions of heavily jointed rocks

Purpose. To develop techniques for estimating the pit wall stability in terms of occurring of a zone of heavily jointed rock mass during ore mining at the Akzhal deposit (Kazakhstan), to work out measures to strengthen the rock opening and to verify the effectiveness of the developed measures. Methodology. The finite element analysis of the rock stress-strain state is implemented on the basis of the elastic-plastic model and the generalized Hoek-Brown failure criterion. The rock mass quality was assessed using the RMR and GSI rating classifications. This made it possible to simulate a zone of intense fracturing by changing the characteristics of the jointed surface. The shear strength reduction procedure was used to determine the safety factor for the quarry wall. Findings. The strain distributions in the rock mass forming the quarry wall have been obtained in terms of the Akzhal polymetallic ore deposit (Kazakhstan). The case of creating a zone of heavily jointed rocks in the area of a tectonic fault was considered. The safety factor of the quarry wall was determined under conditions of increased rock fracturing, as well as after carrying out measures to strengthen the rocks with a hardening solution. Originality. The effect of intense jointness on the pit wall stability is demonstrated. A method for the consistent evaluation of the quarry wall stability is proposed considering the change in the rock properties due to natural factors and artificial reinforcement. It is shown that a change in the joint surface quality due to the hardening injection reduces the shear strains in the sliding zone. Practical value. The pit wall stability was predicted considering the formation of a zone of intense fracturing under mining and geological conditions of the Akzhal deposit. The possibility of testing the effectiveness of rock strengthening measures based on mathematical modeling was shown.

Utilization of Fun Games as Earthquake Disaster Mitigation Efforts for Inclusive Children

The lembang fault is active and can potentially trigger earthquakes in the West Bandung Regency area and its surroundings. The lembang fault has two segments, namely the western and eastern segments, with a movement of 3 mm/year. The Ngamprah Raya Special School (SLB) is a school for children with special needs located in the Lembang fault area in the western segment. This condition causes SLB Ngamprah Raya to be in an earthquake-prone area. One of those affected is highly vulnerable to earthquakes, namely children, even more vulnerable, namely children with special needs or inclusion. Children with special needs need education regarding the Lembang fault earthquake and earthquake disaster mitigation. Earthquake disaster mitigation learning based on fun games needs to be done for Children with Special Needs. The purpose of this study is to utilize fun game media for earthquake disaster mitigation education for children with special needs. The method used is participatory observation involving accompanying teachers and students. The sample used is accidental sampling. The study results show that the fun game of snakes and ladders based on disaster mitigation is effective and efficient for children with special needs with mental retardation. In its implementation, game time and participants must be considered and limited to achieve learning. Students get developmental achievements as expected by going through three cycles. Each cycle is carried out with an effective and efficient snake and ladders game adjustment scheme. Learners are more likely to be able to capture interactive material. Snakes and ladders fun game can be an alternative solution in developing earthquake disaster mitigation learning media for mental retardation.Keywords: Fun game, Disaster Mitigation, Children with Special Needs.

High-Accuracy Insulator Defect Detection for Overhead Transmission Lines Based on Improved YOLOv5

As a key component in overhead cables, insulators play an important role. However, in the process of insulator inspection, due to background interference, small fault area, limitations of manual detection, and other factors, detection is difficult, has low accuracy, and is prone to missed detection and false detection. To detect insulator defects more accurately, the insulator defect detection algorithm based on You Only Look Once version 5 (YOLOv5) is proposed. A backbone network was built with lightweight modules to reduce network computing overhead. The small-scale network detection layer was increased to improve the network for small target detection accuracy. A receptive field module was designed to replace the original spatial pyramid pooling (SPP) module so that the network can obtain feature information and improve network performance. Finally, experiments were carried out on the insulator image dataset. The experimental results show that the average accuracy of the algorithm is 97.4%, which is 7% higher than that of the original YOLOv5 network, and the detection speed is increased by 10 fps, which improves the accuracy and speed of insulator detection.

Application of BRB to Seismic Mitigation of Steel Truss Arch Bridge Subjected to Near-Fault Ground Motions

In this paper, the seismic response of a steel truss arch bridge subjected to near-fault ground motions is studied. Then, the idea of applying buckling restrained braces (BRBs) to a steel truss arch bridge in near-fault areas is proposed and validated. Firstly, the basic characteristics of near-fault ground motions are identified and distinguished. Furthermore, the seismic response of a long span steel truss arch bridge in the near fault area is analyzed by elastic-plastic time analysis. Finally, the braces prone to buckling failure are replaced by BRBs to reduce the seismic response of the arch rib through their energy dissipation properties. Four BRB schemes were proposed with different yield strengths, but the same initial stiffness. The basic period of the structure remains the same. The results show that near-fault ground motion will not only obviously increase the displacement and internal force response of the bridge, but also cause more braces to buckle. By replacing a portion of the normal bars with BRBs, the internal forces and displacements of the arch ribs can be reduced to some extent, which is more prominent under the action of pulsed ground motion. There is a clear correlation between the damping effect and the parameters of BRB, so an optimized solution should be obtained by comparison and calculation.

Simulation analysis of rolling bearings based on explicit dynamics

Based on LS-PrePost software, the three-dimensional display of healthy cylindrical roller bearings was established finite element model for dynamic simulation. Based on the explicit algorithm, the model analyzes the law of bearing stress level with radial outward load under the conditions of friction contact, speed and load, and based on the healthy roller bearing model, simulates the local spalling fault of the outer raceway by setting the unit defect, and analyzes the equivalent force change process when the roller through the fault area. The simulation results are compared with the theoretical calculation results to verify the correctness of the finite element model of the faulty bearings, and provide a certain reference for the fault diagnosis of rolling bearings.

Partial dislocation structures at expansion terminating areas of bar-shaped single Shockley-type stacking faults and basal plane dislocations at the origin in 4H-SiC

Partial dislocation (PD) combinations near the substrate/epilayer interface and the epilayer surface of 4H-SiC are analyzed for bar-shaped single Shockley-type stacking faults (1SSFs) by plan-view transmission electron microscopy (TEM) with the aid of photoluminescence imaging. Although the PDs are found to have a zigzag structure similar to that found in triangular 1SSF by TEM observation, the combination is thought to be different, consisting of a 30° Si-core + 90° Si-core for the triangular 1SSF and 30° Si-core + 30° C-core for the bar-shaped 1SSF. The features of the basal plane dislocation at the origin are speculated by also identifying the converted threading edge dislocation by additional Burgers vector determination of the PD loop by TEM.

Self-reactivated rupture during the 2019 Mw = 8 northern Peru intraslab earthquake

The 2019/05/26 Northern Peru earthquake (Mw=8) is a major intermediate-depth earthquake that occurred close to the eastern edge of the Nazca slab flat area. We analyze its rupture process using high-frequency back-projection and seismo-geodetic broadband inversion. The latter approach shows that the earthquake propagated with almost purely normal faulting along the 60° eastward dipping plane. Both imaging techniques provide a very consistent image of the peculiar space-time rupture process of this earthquake: its 60-second long rupture is characterized both by a main northward propagation (resulting in a rupture extent of almost 200 km in this direction) and by a reactivation phase of the hypocentral area, particularly active 35 s to 50 s after origin time. Given the depth of this earthquake (125-140 km), the reactivation time window coincides with the arrival time of the surface-reflected elastic wavefield. Computed values of the dynamic Coulomb stresses associated with this wavefield are of the order of ten to several tens of kPa, in a range of values where dynamic triggering has already been observed. The reactivation phase of the Peru earthquake may thus originate from fault areas that were brought close to rupture by the initial rupture front before being triggered by stress increments provided by the reflected wavefield. Source time function complexity observed for other large intermediate-depth earthquakes further suggests that such a mechanism is not an isolated case.

Fault Feature Enhanced Extraction and Fault Diagnosis Method of Vibrating Screen Bearings

For mechanical equipment, bearings have a high incidence area of faults. A problem for bearings is that their fault characteristics include a vibrating screen exciter which is weak and thus easily covered in strong background noise, hence making the noise difficult to remove. In this paper, a noise reduction method based on singular value decomposition, improved by singular value’s unilateral ascent method (SSVD), and a fault feature enhancement method, i.e., variational mode decomposition, improved by revised whale algorithm optimization (RWOA-VMD), are proposed. These two methods are used in vibration signal processing with early faults of bearings having a vibrating screen and they have achieved significant application results. This paper also aims to construct a multi-modal feature matrix composed of energy entropy, singular value entropy, and power spectrum entropy, and then the early fault diagnosis of bearings of a vibrating screen exciter bearing is realized by using the proposed support vector machine, improved by the aquila optimizer algorithm (AO-SVM).

Effect of micron-sized particles on the crack growth behavior of a Ni-based powder metallurgy superalloy

Generally, larger non-metallic inclusions have a negative influence on crack growth resistance due to the stress concentration effects that result from them appearing along the paths of crack growth. The in-situ tensile behavior for dog-bone-shape specimens of a Ni-based powder metallurgy FGH4096 superalloy including micro-sized particles has been investigated. The effect of the micron-sized particles on the initiation and propagation of cracks was studied through the in-situ tensile test. The mechanism of the in-situ tensile process was investigated using molecular dynamics methods. The results showed that the particle inclusions were basically micron-sized, including carbide particles, rare earth inclusions and composite inclusions in the FGH4096 superalloy. The carbide particles cracked themselves but did not become a source of a main crack. Many carbide particles near the main crack paths did not aggravate the propagation of the main crack under tensile behavior. Molecular dynamics simulation results showed that the crack was found to be preferable close of regions of atomic disorder, and a stacking fault area formed during deformation was found to effectively release the stress concentration and delay the occurrence of cracks. Crack initiation and propagation around a notch was also investigated in detail, by combining the experimental and computational results.

Failure Behavior of Cuboid Granite Sample with a Circular Hole beneath a Bonding Fracture under Biaxial Compression

Ore bodies incubating within fault zones are a common phenomenon in geological strata and pose a huge challenge for underground mining. To effectively exploit mineral resources, the layout of the mining roadway and the interaction between the roadway and geological fault must be considered. In this paper, a bonding fracture was formed on granite samples to simulate a closed fault, under which a circular hole was fabricated to simulate the roadway of the gold mine. We performed a biaxial compression test at a true-triaxial electrohydraulic servo testing system for granite samples with a combined fracture-hole structure. It is worth noting that the fracture inclination β and relative distance between fracture and hole L were taken into account. The digital image correlation (DIC) technique was used to observe the displacement and strain field evolution around the fracture-hole structure. Our results demonstrate that (1) the strength of the granite sample decreases with increasing bonding fracture dip angle β, and the displacement drops between the hanging wall and foot wall raised in both the horizontal and vertical displacement directions. Macroscopic cracks become dense, and the failure degree becomes severe around simulated fault areas. (2) With the increase in the distance L, the strength of the granite sample increases, the influence of the hole on the slip of the fracture plane is weakened, and the discontinuity of displacement becomes less obvious. (3) The maximum principal strain field quantitatively reveals the details of the crack initiation, propagation, and coalescence around the fracture-hole structure, and displacement nucleation is observed in the vertical displacement field.

Numerical simulation of the fluid-solid coupling mechanism of water and mud inrush in a water-rich fault tunnel

This study developed a new model, a 3D coupled computational fluid dynamics (CFD)-discrete element method (DEM) model, by coupling two software programs, ABAQUS and PFC3D, to solve problems related to fluid-solid interaction systems. The complete governing equations and the two-way coupling process between the two software are presented herein. Via Transmission Control Protocol (TCP) socket communication with Python scripting, information between the two software is exchanged in real-time. Then, the classic example in the PFC5.0 documentation was used to verify the model. In the end, the ABAQUS-PFC3D model was employed to simulate the process of water and mud inrush in a water-rich fault tunnel, which could reflect the evolution process of water and mud inrush and track particle movement in a fault zone. The results show that the particles that collapsed inside the fault formed an ellipsoidal distribution during the water and mud inrush in a water-rich fault tunnel. With the continuous loss of particles in the fault into the tunnel, the migration of particles is discontinuous, and a large void appears inside the fault zone. The rapid change of the groundwater flow velocity caused the negative pore pressure. The pressure arch force structure is formed above the ellipsoidal collapse area inside the fault. The principal force field of the fault areas changes from close to the dip of the fault to close to the perpendicular to the fault.

Near-fault broadband seismograms synthesis in a stratified transversely isotropic half-space using a semi-analytical frequency-wavenumber method

Anisotropic behavior occurs in natural soils and rocks, owing to sedimentation and weathering. However, the semi-analytical methods of near-fault broadband seismogram synthesis in the anisotropic medium are still rare. The physical-based frequency-wavenumber method was constructed for broadband seismogram synthesis due to a kinematic hybrid finite-fault source in a stratified transversely isotropic (TI) half-space for the first time. As the crucial foundation of the seismogram synthesis, the Green's function is established by the dynamic stiffness matrix method, effectively and stably modeling the broadband seismic waves propagation in a TI crust. A hybrid method of the kinematic fault source is applied to reasonably combine the low-frequency deterministic parts with the high-frequency stochastic parts, achieving a broadband waves excitation. The theoretical formulations are well-programmed by the FORTRAN code with OpenMP-based parallel technology to implement the fast solution. Compared with the two published results, the correctness of the methodology is well verified. A numerical example of an Mw7.0 scenario strike-slip earthquake is simulated to discuss the difference between TI and isotropic medium in the aspects: (i) attenuation characteristics near the fault area, (ii) rupture directional effect and velocity pulse, and (iii) response spectrum characteristics.

Outcrop scale mixing enhanced by permeability variations: the role of stationary and travelling waves of high saturation indices

AbstractTo study the ore mineralization at the outcrop scale we merge an advection–diffusion simulation with the geochemical software iphreeqc to model the mixing of two realistic fluids. We simulate the infiltration of a metal-rich fluid into a rock that is saturated with pore fluid. We test the feedback effects with a number of scenarios based on an outcrop-scale 5 × 5 m model consisting of two high-permeable vertical faults within a low-permeable host rock that lead into a permeable layer. The hot metal-rich fluid enters the model through the faults from below. We solve the advection–diffusion equation for 12 chemical species and temperature, and use iphreeqc to determine the resulting properties of local fluid domains as well as related saturation indices for minerals. The faults in the model act as pathways for the metal-rich fluid, with the infiltrating fluid displacing the pore fluid. Mixing in the model takes place as a function of advection along permeable faults coupled with diffusion of chemical species at the interface between two fluids, while heat diffusion is fast enough (103 times faster) to equilibrate temperature. Simulations show a high saturation index of mixing-derived minerals such as barite at the interface between the two fluids as a result of fluid mixing. Fast fluid pathways (i.e. faults) show travelling waves of high saturation indices of barite, while low-permeability zones such as fault walls and areas below less permeable layers experience stationary waves of high saturation indices. Our results show that, depending on the dominant transport process (advection or diffusion), mineralization will localize next to permeability contrasts in zones where local diffusion dominates.

Study on the Destructive Effect of Small Faults on Coal Pore Structure

Small fault area in coal mine has great risk of coal and gas outburst. However, the damage effect of small faults on coal pore structure still lacks systematic research. Taking a small reverse fault under Pingmei No. 2 mine as an example, this paper collects the hanging wall coal samples within 5 m from the fault plane and the coal samples 50 m from the fault plane, where there is no fault development. The pore structure characteristics of the two coal samples were analyzed and compared by means of a scanning electron microscope, mercury injection, liquid nitrogen adsorption, and Raman spectroscopy. The test results show that compared with the coal samples without faults, the coal samples at faults form micron-scale fracture zones with constant spacing, stable occurrence, and flat two walls. The pore volume and pore specific surface area of different pore sizes increase, the pore peak of mesopore (100~1000 nm) shifts from 1000 nm to 200~400 nm, and its connectivity is enhanced. The number of micropores (<10 nm) increased significantly, and the ink bottle type pores developed. Faulting also has a certain impact on the macromolecular structure of coal, which shows that the D peak area decreases and the area of G peak increases, indicating that the order degree of macromolecular structure of coal increases.

Mobile robot communication fault diagnosis method based on swarm intelligence algorithm

The current communication fault diagnosis methods mainly focus on the classifier with fault probability, which often leads to the low diagnosis efficiency. In order to overcome the above problems, mobile robot communication fault diagnosis method based on swarm intelligence algorithm is proposed in the paper. Firstly, the abnormal data is extracted after the analysis of the communication data with Kalman filter. Secondly, the supporting decision model was designed to standardize the communication exchange process and locate the fault range. Futher more, the ant colony optimization algorithm combined with particle swarm optimization was used to locate the fault area, and the multi-model hybrid method was adopted to comprehensively judge the communication fault. The different interference ratio was used in the experiment to test the performance of the proposed algorithm compared with the SVM and Bayesian model. Finally, the experiment results show the validity of mobile robort communication fault diagnosis based on swarm intelligence algorithm.