Dynamic Deformation Research Articles

A smoothness control method for kilometer‐span railway bridges with analysis of track characteristics

AbstractSignificant dynamic deformations during the operation of kilometer‐span high‐speed railway bridges adversely affect track maintenance. This paper proposes a three‐stage smoothness control method based on a comprehensive analysis of track alignment characteristics to address this issue. In the method, historical measured data are grouped into multicategories, and reference alignments for each category are reconstructed. Then, the reference alignment category to which the track to be adjusted belongs is accurately matched. Finally, a novel smoothness optimization algorithm is designed to use the 60 m chord as the optimization unit, and the 10 m and 30 m combined chords within the unit constrain the midchord offset and vector distance difference. The proposed method was applied to formulate the maintenance scheme for the Shanghai–Suzhou–Nantong Yangtze River Bridge. The result indicates that the track smoothness improved by more than 79.7%, and the high‐speed train operational performance improved by over 64.3%, effectively enhancing the maintenance quality.

Hot compression bonding of a 9Cr oxide dispersion strengthened alloy and a 9Cr reduced-activation ferritic/martensitic alloy

An innovative method of hot compression bonding is proposed in this work for the joining of 9Cr oxide dispersion strengthened (ODS) alloy and 9Cr reduced-activation ferritic/martensitic (RAFM) alloy. The microstructural evolution of the bonding interface was investigated by scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD), and transmission electron microscopy (TEM). The results verify that the pinning effect of nano-oxides particles (NPs) in 9Cr ODS alloy significantly enhances its dynamic recrystallization (DRX) temperature and deformation resistance. Continuous DRX (CDRX) first occurred on the 9Cr RAFM alloy side, and the areas near the bonding interface were composed of recrystallized grains. With increasing strain, CDRX also showed up on the 9Cr ODS alloy side. Inevitable slight oxidation occurred at the bonding interface during the hot compression bonding (HCB) process, and the interfacial oxides transformed from initial coarse CrO to TiO and finally to Y-Ti-O nanoparticles with sizes comparable to pre-existing NPs dispersed in the 9Cr ODS alloy matrix. It is believed that interfacial oxide transformation and grain structure consistency contributed to the excellent interface healing of the two dissimilar alloy pieces. The effectiveness of the bonding was tested by tensile tests and fractography analysis, revealing that ideal metallurgical bonding could be achieved under a controlled strain level of 10 % at 800 °C followed by soaking at 1000 °C for 4 h.

Численное исследование задачи низкоскоростного столкновения стального шара с ледяной плитой

In this paper, the dynamic deformation process during the low-speed collision was investigated. The full 3D dynamic contact problem was simulated in the Abaqus software, based on the explicit finite-element method on structured meshes. Two basic mechanical models (linear isotropic elastic and elastoplastic) are considered. The obtained results showed the possibility of the experimental data, available in the open literature for different striker velocities, reproduction. The better understanding of the ice deformation process can be useful for different applied problems, like the ice impact on the aircraft wings estimation and the ice-water contact reflected waves filtration during the seismic survey in the Arctic region.

Strength analysis of linear-elastic frame structures under pulse-periodic loads

Pulse-periodic loads on structures are one of the most dangerous for the their stress-strain state under dynamic load.Purpose: The aim of the work is to analyze the dynamic deformation of linear-elastic frame structures under pulse-periodic loads.Approach: It is found that a simple frame structure with additional concentrated masses affects the loading parameters (length, shape and pulse frequency). The analysis is given to physical characteristics of the deformed structure and its dynamic response under the pulse-periodic load.Research findings: Prerequisites are formulated for an unfavorable (from the position of VAT parameters) combination of the load and structural parameters.

Influence of Interface Type on Dynamic Deformation Behavior of 3D-Printed Heterogeneous Titanium Alloy Materials.

Using the Split Hopkinson Pressure Bar technique, strain-limited dynamic compressive loading experiments were performed on TA1/TA15 heterostructure (HS) materials. The plastic deformation mechanisms, fracture forms, and energy absorption properties of an HS material with a metallurgical bonding interface (MB) and an HS material without a metallurgical bonding interface (NMB) are compared and analyzed. The results show that there is no significant difference between the two deformation mechanisms. The fracture forms are all "V-shaped" fractures within the TA1 part. The NMB was carried for 57 μs before failure and absorbed 441 J/cm3 of energy. The MB was carried for 72 μs before failure and absorbed 495 J/cm3 of energy. Microstructure observations show that there is a coordinated deformation effect near the MB interface compared to the NMB, with both TA1 and TA15 near the interface carrying stresses. This causes an enhancement of the MB load-bearing time and a 12% increase in energy absorption.

Mechanical and Functional Responses in Astrocytes under Alternating Deformation Modes Using Magneto-Active Substrates.

This work introduces NeoMag, a system designed to enhance cell mechanics assays in substrate deformation studies. NeoMag uses multidomain magneto-active materials to mechanically actuate the substrate, transmitting reversible mechanical cues to cells. The system boasts full flexibility in alternating loading substrate deformation modes, seamlessly adapting to both upright and inverted microscopes. The multidomain substrates facilitate mechanobiology assays on 2D and 3D cultures. The integration of the system with nanoindenters allows for precise evaluation of cellular mechanical properties under varying substrate deformation modes. The system is used to study the impact of substrate deformation on astrocytes, simulating mechanical conditions akin to traumatic brain injury and ischemic stroke. The results reveal local heterogeneous changes in astrocyte stiffness, influenced by the orientation of subcellular regions relative to substrate strain. These stiffness variations, exceeding 50% in stiffening and softening, and local deformations significantly alter calcium dynamics. Furthermore, sustained deformations induce actin network reorganization and activate Piezo1 channels, leading to an initial increase followed by a long-term inhibition of calcium events. Conversely, fast and dynamic deformations transiently activate Piezo1 channels and disrupt the actin network, causing long-term cell softening. These findings unveil mechanical and functional alterations in astrocytes during substrate deformation, illustrating the multiple opportunities this technologyoffers.

Integrated construction of stretchable supercapacitor with outstanding deformation stability and flame retardancy

The fast development of wearable electronics requires urgently stretchable energy storage devices, but conventional stretchable energy-storage devices suffer from poor dynamic deformation stability. The key is to create a new construction strategy of "electrode/electrolyte interface integration". Herein, we have proposed a clever strategy that combines layer-by-layer electrospinning with a self-selected vapor-phase polymerization (VPP) method to assemble the integrated stretchable supercapacitors (ISSCs). Furthermore, the interface stability enhancement mechanism is revealed through experimental and theoretical simulations, showing that the synergistic effect of molecular chain entanglement and mechanical meshing endows excellent anti-deformation stability of ISSCs. As a result, the as-assembled ISSCs deliver excellent dynamic deformation electrochemical stability with 99.5 % capacitance retention after 500 stretching cycles at strain and outstanding flame retardancy (limiting oxygen index (LOI) up to 48.1 % at a film thickness of only 0.22 mm). The innovative integrated design strategy endows a systematic construction plan for the scalable fabrication of wearable organic energy storage devices.

Assessing the influence of aneurysm dimensions on hemodynamic patterns and wall deformation dynamics for predicting rupture risk

Cerebral aneurysms are among the most dangerous cardiovascular diseases which display no symptoms prior to reaching critical conditions. As cerebral aneurysms are deadly diseases with a very small treatment window after reaching the critical stage, numerical investigations of this phenomenon are commonly used to assess the risk of rupture. In this study, the fluid-structure interaction (FSI) method is used to analyze the effects of aneurysm size on hemodynamic factors predicting rupture in three aneurysms of different geometries, at the same location, and using the same boundary conditions. In the present study, the aneurysms experience TAWSS at values under 2 Pa in incremented areas as the aneurysmal sizes increase, this is while the relatively larger distribution of high TAWSS (as high as 20 Pa) regions are perceived in smaller aneurysms. Furthermore, the maximum OSI stands at below 0.05 in the smaller cases while the larger case experiences a maximum OSI as high as 0.2, which is considered a predictive parameter for rupture. The vortex core lines experience discontinuities with increased aneurysmal size, which is in agreement with the development of flow complexities with size. The hemodynamics factors such as the time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and vortex core line investigated in this study, suggest that greater size can be considered a major risk factor for rupture. In addition to that, we have found that the displacement trend of the aneurysm changes as size increases; developing more in the dome rather than the aneurysmal sac. This change in trend might also present a potential to be used as a predictive parameter.

Hard- and Software Controlled Complex for Gas-Strain Monitoring of Transition Zones.

The article describes a hard- and software controlled complex for gas-strain monitoring, consisting of stationary laser strainmeters and a laser nanobarograph, a stationary gas analyzer, and a weather station installed at Shultz Cape in the Sea of Japan; and a mobile shipboard complex, consisting of a gas analyzer and a weather station installed in a scientific research vessel. In the course of trial methodological measurements on these systems, general patterns were identified in the dynamics of greenhouse gases and deformation of the Earth's crust in the range of diurnal and semi-diurnal tides, and also in the range of ultra-low frequencies, caused by atmospheric wave processes and, possibly, individual tones of the Earth's eigen oscillations.

Design of AR system tracking registration method using dynamic target light-field

In the process of tracking registration for an augmented reality (AR) system, it's essential first to obtain the system's initial state, as its accuracy significantly influences the precision of subsequent three-dimensional tracking registration. At this point, minor movements of the target can directly lead to calibration errors. Current methods fail to address the challenge of capturing the initial state of dynamic deformation in optically transparent AR systems effectively. To tackle this issue, the concept of a static light-field is expanded to a four-dimensional dynamic light-field, and a tracking registration method for an optical see-through AR system based on the four-dimensional dynamic light-field is introduced. This method begins by analyzing the relationship between the components of the optical see-through AR system and studying the impact of a dynamic target on the initial state model. Leveraging the fundamental principle of light-field correlation, the theory and model for four-dimensional dynamic light-field tracking registration are developed. A lot of experiments have confirmed the algorithm's accuracy, enhanced its stability, and demonstrated the superior performance of the three-dimensional tracking registration algorithm.

Dynamic response of clamped metallic thin-walled cylindrical shells under lateral shock loading

A combined experimental and numerical study was carried out to explore the dynamic response of Q235 thin-walled cylindrical shells under lateral shock loading. The machined Q235 specimens were clamped on both sides and subjected to centered lateral simulated shock loading via foam projectile impact tests, with their dynamic deformation evolution, mid-point deflections, and final deformation modes experimentally measured. The mid-point deflections of the impact side are all positive (the direction of deformation is the same as the impact direction) while those of the rear side all exhibit negative values (the direction of deformation is opposite to the impact direction). To further explore this phenomenon, the method of finite element (FE) was employed to simulate the foam projectile impact, with good agreement against experimental measurements achieved. Using the validated numerical model, the effects of impact velocity, length-to-diameter ratio, and thickness-to-diameter ratio on the dynamic response of the thin-walled cylindrical shell were further analyzed. The direction of both side deflections and deformation modes are significantly affected by the impact level and the shell geometries. For the rear side, within the given range of impact momentum and geometric parameters, the numerically predicted deflection varies from −1.775 mm to 2.45 mm. Thereupon, the coupling of indentation and bulge deformation patterns are indicated, and their corresponding contribution changes are considered the main mechanism for determining the final deformation of the thin-walled cylindrical shell's rear side.

Dynamics of a viscoelastic droplet migrating in a ratchet microchannel under AC electric field

Droplet-based microfluidic devices can be powered or manipulated by applying an external electric field, and the ability to precisely control the flow in such devices is essential for various engineering and biomedical applications. In this numerical study, we investigate the deformation dynamics of a viscoelastic droplet in a ratchet microchannel under the influence of an AC electric field. We employ the leaky-dielectric electrohydrodynamic model for both the immiscible fluid phases coupled with the Oldroyd-B model for the droplet fluid. The effect of geometrical parameters such as the type of ratchet and the wavenumber of the ratchets along with the flow parameters such as the electrocapillary number, Weissenberg number and the capillary number significantly affect the droplet shape dynamics and the polymer chain extension. For the parameters considered in this work, the electric force tends to stretch the droplet in the streamwise direction and enhances the droplet deformation and polymer extension. Several interesting effects arise as a result of the coupling of the periodic hydrodynamic forcing of the ratchet walls and the electric field. Specifically, an exponential rise in the polymer chain extension for higher ratchet wavenumbers is observed, along with the cross-stream migration of the droplet for higher electrocapillary numbers when it reaches the outlet of the ratchet constriction.

Light-Responsive Soft Robot Integrating Actuation and Function Based on Laser Cutting.

Soft robots with good deformability and adaptability have important prospects in the bionics and intelligence field. However, current research into soft robots is primarily limited to the study of actuators and ignores the integrated use of functional devices and actuators. To enrich the functions of soft robots and expand their application fields, it is necessary to integrate various functional electronic devices into soft robots to perform diverse functions during dynamic deformation. Therefore, this paper discusses methods and strategies to manufacture optical stimuli-responsive soft actuators and integrate them into functional devices for soft robots. Specifically, laser cutting allows us to fabricate an optically responsive actuator structure, e.g., the curling direction can be controlled by adjusting the direction of the cutting line. Actuators with different bending curvatures, including nonbending, can be obtained by adjusting the cutting depth, cutting width, and the spacing of the cutting line, which makes it easy to obtain a folded structure. Thus, various actuators with complex shape patterns can be obtained. In addition, we demonstrate a fabrication scheme for a worm-like soft robot integrated with functional devices (LEDs are used in this paper). The local nonbending design provides an asymmetric structure that provides driving power and avoids damage to the functional circuit caused by the large deformation during movement. The integration of drive and function provides a new path for the application of soft robots in the intelligence and bionics field.

Permeability estimation for deformable porous media with convolutional neural network

PurposeAccurately evaluating fluid flow behaviors and determining permeability for deforming porous media is time-consuming and remains challenging. This paper aims to propose a novel machine-learning method for the rapid estimation of permeability of porous media at different deformation stages constrained by hydro-mechanical coupling analysis.Design/methodology/approachA convolutional neural network (CNN) is proposed in this paper, which is guided by the results of finite element coupling analysis of equilibrium equation for mechanical deformation and Boltzmann equation for fluid dynamics during the hydro-mechanical coupling process [denoted as Finite element lattice Boltzmann model (FELBM) in this paper]. The FELBM ensures the Lattice Boltzmann analysis of coupled fluid flow with an unstructured mesh, which varies with the corresponding nodal displacement resulting from mechanical deformation. It provides reliable label data for permeability estimation at different stages using CNN.FindingsThe proposed CNN can rapidly and accurately estimate the permeability of deformable porous media, significantly reducing processing time. The application studies demonstrate high accuracy in predicting the permeability of deformable porous media for both the test and validation sets. The corresponding correlation coefficients (R2) is 0.93 for the validation set, and the R2 for the test set A and test set B are 0.93 and 0.94, respectively.Originality/valueThis study proposes an innovative approach with the CNN to rapidly estimate permeability in porous media under dynamic deformations, guided by FELBM coupling analysis. The fast and accurate performance of CNN underscores its promising potential for future applications.

Study on the method of transfer alignment based on the distributed inertial network of guided submunition

Aiming at the problem of poor transfer alignment accuracy between missiles with a high length-to-diameter ratio as a carrier missile and the internally carried guided submunition, this study proposes a transfer alignment method based on the distributed inertial network of the guided submunition. Initially, considering the influence of the deflection deformation of the carrier missile body and the dynamic nonlinear deformation of the lever arm on the transfer alignment accuracy, the corresponding error model is established and compensated for the sub-inertial guide velocity to improve the accuracy of the observed quantities. Additionally, in response to the high failure rate of low-cost inertial guidance systems equipped with guided submunition, we used an inertial network data fusion architecture based on the isolation of device failure monitoring, which effectively isolates the faulty data through the fusion of inertial measurements at the sensor level and optimal fusion of filtering to further improve the reliability of transmission alignment. The effectiveness of the method proposed in this paper is verified through a large number of simulation experiments. Compared with the traditional transfer alignment method between a single master inertial guide and a sub inertial guide, the method in the paper has obvious improvement in the transfer alignment accuracy. In addition, this method is not affected by the failure of inertial devices in the distributed inertial network, and can continuously maintain a high transfer alignment accuracy. For this kind of missile-borne distributed inertial network with a sub-node sets layer, it is found after comparison that: the transmission alignment error is basically the same for different slave nodes in the same sub-node sets; between different sub-node sets, the closer to the master inertial guide the transmission alignment error is smaller. This study provides a new solution idea and certain reference value for solving the problem of poor transfer alignment accuracy between missiles with a high length-to-diameter ratio as a carrier missile and the internally carried guided submunition.

Geotechnical and Geophysical Assessment of the 2021 Tamban Chimbo Landslide, Northern Andes of Ecuador

The recent landslide at the Tamban site, on 21 December 2021 (23:30 local time), provides relevant information on the trigger mechanisms and their relationship with geological factors. Therefore, the predominant aims of the current study were to identify the lithological units in the rocky substrate and subsoil from geophysical surveys, delineating the thickness of the tuff- and lapilli-supported fall layers. Additionally, we evaluated the deformation dynamics from probabilistic and deterministic analysis, where a plane with well-differentiated discontinuities of normal-type geological fault was evidenced. This deformation feature was associated with a planar-type landslide that reached a debris flow up to 330 m distance, with varied thicknesses. Furthermore, we conducted a probabilistic analysis, which started from the characteristics of the post-slide material analyzed through triaxial trials that were conducted to a retro-analysis in order to obtain the parameters of the moment the event occurred. With the base parameters to perform the landslide analysis and determine its safety factors in compliance with current regulations, a reinforced earth configuration was applied using the Maccaferri’s Terramesh method. Hence, it was possible to provide an analysis methodology for further geological scenarios of landslides that occurred in the province of Bolívar, the northern Andes of Ecuador.

Middle Jurassic to Early Cretaceous orogenesis in the Klamath Mountains Province (Northern California–southern Oregon, USA) occurred by tectonic switching: Insights from detrital zircon U-Pb geochronology of the Condrey Mountain schist

The Klamath Mountains Province of Northern California and southern Oregon, USA, consists of generally east-dipping terranes assembled via Paleozoic to Mesozoic subduction along the western margin of North America. The Klamath Mountains Province more than doubled in mass from Middle Jurassic to Early Cretaceous time, due to alternating episodes of extension (e.g., rifting and formation of the Josephine ophiolite) and shortening (e.g., Siskiyou and Nevadan events). However, the tectonic mechanisms driving this profound Mesozoic growth of the Klamath Mountains Province are poorly understood. In this paper, we show that formation of the Condrey Mountain schist (CMS) of the central Klamath Mountains Province spanned this critical time period and use the archive contained within the CMS as a key to deciphering the Mesozoic tectonics of the Klamath Mountains Province. Igneous samples from the outer CMS subunit yield U-Pb zircon ages of ca. 175–170 Ma, which reflect volcanic protolith eruptive timing. One detrital sample from the same subunit contains abundant (~54% of zircon grains analyzed) Middle Jurassic ages with Paleozoic and Proterozoic grains comprising the remainder and yields a maximum depositional age (MDA) of ca. 170 Ma. These ages, in the context of lithologic and thermochronologic relations, suggest that outer CMS protoliths accumulated in an outboard rift basin and subsequently underthrust the Klamath Mountains Province during the Late Jurassic Nevadan orogeny. Five samples of the chiefly metasedimentary inner CMS yield MDAs ranging from 160 Ma to 130 Ma, with younger ages corresponding to deeper structural levels. Such inverted age zonation is common in subduction complexes and, considering existing K-Ar ages, suggests that the inner CMS was assembled by progressive underplating over a >10 m.y. timespan. Despite this age zonation, age spectra derived from structurally shallow and deep portions of the inner CMS closely overlap those derived from the oldest section of the Franciscan subduction complex (South Fork Mountain schist). These relations suggest that the inner CMS is a composite of South Fork Mountain schist slices that were sequentially underplated beneath the Klamath Mountains Province. The age, inboard position, and structural position (i.e., the CMS resides directly beneath Jurassic arc assemblages with no intervening mantle) of the CMS suggest that these rocks were emplaced during one or more previously unrecognized episodes of shallow-angle subduction restricted to the Klamath Mountains Province. Furthermore, emplacement of the deepest portions of the CMS corresponds with the ca. 136 Ma termination of magmatism in the Klamath Mountains Province, which we relate to the disruption of asthenospheric flow during slab shallowing. The timing of shallow-angle subduction shortly precedes that of the westward translation of the Klamath Mountains Province relative to correlative rocks in the northern Sierra Nevada Range, which suggests that subduction dynamics were responsible for relocating the Klamath Mountains Province from the arc to the forearc. In aggregate, the above relations require at least three distinct phases of extension and/or rifting, each followed by an episode of shallow-angle underthrusting. The dynamic upper-plate deformation envisioned here is best interpreted in the context of tectonic switching, whereby slab steepening and trench retreat alternate with slab shallowing due to recurrent subduction of buoyant oceanic features.

Application of Stereo Digital Image Correlation on Facial Expressions Sensing.

Facial expression is an important way to reflect human emotions and it represents a dynamic deformation process. Analyzing facial movements is an effective means of understanding expressions. However, there is currently a lack of methods capable of analyzing the dynamic details of full-field deformation in expressions. In this paper, in order to enable effective dynamic analysis of expressions, a classic optical measuring method called stereo digital image correlation (stereo-DIC or 3D-DIC) is employed to analyze the deformation fields of facial expressions. The forming processes of six basic facial expressions of certain experimental subjects are analyzed through the displacement and strain fields calculated by 3D-DIC. The displacement fields of each expression exhibit strong consistency with the action units (AUs) defined by the classical Facial Action Coding System (FACS). Moreover, it is shown that the gradient of the displacement, i.e., the strain fields, offers special advantages in characterizing facial expressions due to their localized nature, effectively sensing the nuanced dynamics of facial movements. By processing extensive data, this study demonstrates two featured regions in six basic expressions, one where deformation begins and the other where deformation is most severe. Based on these two regions, the temporal evolutions of the six basic expressions are discussed. The presented investigations demonstrate the superior performance of 3D-DIC in the quantitative analysis of facial expressions. The proposed analytical strategy might have potential value in objectively characterizing human expressions based on quantitative measurement.

Dynamic deformation characteristics of saturated coral sand incorporating fines content under drained conditions

The effect of the fine content (FC) and the relative density (Dr) on the deformation properties of saturated coral sand has been explored through a series of drained cyclic triaxial tests. An important finding is that both FC and Dr significantly affect the development of cumulative volumetric strain (εvd,irN) and dynamic elastic modulus (Ed,N). Steady state cumulative volumetric strain (εvd,irs) increases with FC and decreases with Dr. When FC increases from 0 % to 30 %, the increment in εvd,irs is about 0.69 %, 0.41 %, 0.16 % under Dr=30 %, 45 %, 70 %, respectively. Furthermore, the development rate of εvd,irN increased with FC. Another significant finding is that the increase of the FC leads to a certain decay of the initial dynamical shear modulus (Ed,1) and the steady state dynamical elastic modulus (Ed,s). When FC increases from 0 % to 30 %, the reduction in Ed,1 is about 16.38 MPa, 12.39 MPa, 10.31 MPa and the reduction in Ed,s is about 6.96 MPa, 5.44 MPa, 3.24 MPa underDr = 30 %, 45 %, 70 %, respectively. A dimensionless parameter, the relative dynamic elastic modulus (Er), is introduced to characterize the development of Ed,N with N. It is found that the growth rate of Er increased with FC, but it is independent on Dr. The equivalent skeleton void ratio (esk*) was introduced based on the binary medium theory. It is found that εvd,irs shows a power-function growth trend with an increase in esk*, while Ed,1 and Ed,s decrease linearly with the increase of esk*. A predictive model between εvd,irN/εvd,irs, Er, and esk* was established, and the applicability of the model was verified based on data from the literature.

Strength, Deformation and Fracture Properties of Hard Rocks Embedded with Tunnel-Shaped Openings Suffering from Dynamic Loads

In rock engineering, the dynamic loads caused by mechanical action and rock blasting have an extremely significant influence on the stableness of surrounding rock masses. To examine the impact of dynamic load on the mechanical properties and fracturing characteristics of hard rocks as well as the failure responses of underground openings, a number of prismatic samples with holes of different numbers and configurations were prepared for dynamic tests employing an SHPB loading device. The experimental results demonstrate that the order of dynamic compressive strength of each group of samples under the impact nitrogen pressure of 0.45 MPa is: G3 > G2 > G5 > G4 > G7 > G6, and the dynamic deformation process of the samples is parted into three phases: linear elastic deformation, plastic deformation and post-peak deformation. A total of three categories of cracks, i.e., spalling cracks, shear cracks and tensile cracks, occur in the specimens. The failure mode of the samples having one or two holes arranged in a vertical direction is controlled by shear cracks, whilst that of the rest groups of pre-holed specimens belongs to tensile-shear failure. The existence of the fabricated holes in the samples significantly weakens the mechanical properties and affects the fracture evolution characteristics, which rely on the quantity and layout of the cavities in the specimens. The interesting results are also discussed and explained, and could supply some insight in the mechanisms of tunnel surrounding rock failure and rock dynamic hazards such as rock burst.