Simulated Damage Research Articles

Under storm risk, economic productivity of Norway spruce (Picea abies (L.) H. Karst) in monoculture shows sharper decline than in mixture with European beech (Fagus sylvatica L.)

Key messageBy calibrating and validating a forest growth model for seven species in Germany and coupling it with a wind damage simulator, we specifically estimated the impact of wind damage on the net present value of Norway spruce and European beech in mixture and monoculture. Under risk, the net present value of spruce managements saw the sharpest declines, although the highest end net present value was still obtained through a heavily thinned spruce monoculture.ContextWind damage is one of the most important risks to Central European forests, and adaptation measures are essential.AimAdaptive management strategies should simultaneously account for forest production and wind risk. We simulated the effect of adaptive measures on wind-risk in German forests.MethodsA process-based forest growth model, “3-PG Mix”, was recalibrated and coupled with the storm damage risk model “Lothar”. We investigated the effect of thinning regimes on wind risk in monoculture and mixed species stands. The net present value of the simulated regimes was calculated and compared (risk vs. no risk).ResultsSpruce regimes achieved the highest net present values when risk was not considered. Considering risk in spruce and beech mixtures and monoculture, all regimes reached values below 3000 € ha−1 by year 120. The exception was a heavily thinned spruce monoculture at 4507 € ha−1, being the most profitable regime under risk.ConclusionWe conclude, on the basis of this modelling study, that heavy thinning reduced storm risk and maintained a higher net present value in spruce. Species mixture of beech and spruce saw net present values levels remain more constant under risk, while beech monoculture increased.

Meso-scale damage analysis of three-dimensional textile stitched composite subjected to compression loading

This article deals with damage simulations of three-dimensional (3D) textile stitched composites under compression loading at meso-scale. The 3D fabric geometry is created by experimental geometry measurements based on textile fiber microscopic images. At first, if a meso-scale of 3D unit-cell of the stitched composite is drawn in Catia software, then the model is imported into Abaqus finite element (FE) software. In addition, a Fortran code is prepared and linked to the Abaqus FE software for computing the stitched composite's mechanical coefficient. Finally, a user-defined subroutine in the finite element implements the damage model to anticipate the stitched composite’s damage initiation and growth. The results of FE modeling show good agreement with the experimental results. This research could contribute the investigation of the integrity and damage tolerance of 3D-stitched composites for aerospace structures.

Finite Element Analysis Combined With Machine Learning to Simulate Open-Hole Strength and Impact Tests of Fibre-Reinforced Composites

Data-driven calibration techniques, consisting of theory-guided feed-forward neural networks with long short-term memory, have previously been developed to find suitable input parameters for the finite element simulation of progressive damage in fibre-reinforced composites subjected to compact tension and compact compression tests. The results of these machine learning-assisted calibration approaches are assessed in a range of virtual open-hole strength tests under tensile and compressive loadings as well as in low velocity impact tests. It is demonstrated that the calibrated material models with bi-linear softening are able to simulate the structural response qualitatively and quantitatively with a maximum error of 9[Formula: see text] with regards to experimentally measured open-hole strength values. Furthermore, the highly efficient models enable the virtual analysis of size effects as well as accurate force simulations in quasi-isotropic laminates under impact loading.

Simulation‐based methodology to identify damage indicators and safety thresholds for post‐earthquake evaluation of structures

AbstractAfter a strong earthquake, criteria are needed to determine whether buildings are safe to reoccupy based on observable damage. This paper presents a simulation‐based methodology to identify relevant damage indicators and safety thresholds for building structures. Prior knowledge of the most relevant damage indicators and their thresholds can increase the accuracy and confidence of post‐earthquake evaluations. Current practice to translate observable damage into a tagging decision relies on qualitative guidelines based on past earthquake experience and judgment, which may be susceptible to speculation and interpretation. In addition, past experience may not be relevant to newer structural systems and to large or complex (e.g., high‐rise) buildings. To augment past observations and data from structural component tests, nonlinear dynamic analyses can be used to estimate the collapse safety of structures with simulated damage. Technologies to execute these simulations have matured over the years, although to date they have not been systematically applied to evaluate the destabilizing effects of simulated damage on collapse safety. In this paper, a methodology is presented to use numerical simulations of damage to identify and evaluate relevant damage indicators that can be quantitatively related to safety thresholds. Damage indicators are selected based on their reliability in estimating the structural safety and their sensitivity to modeling uncertainty, that is, where the preferred indicators are insensitive to variability in the structural materials and model parameters. The safety threshold for each damage indicator is selected to maximize accuracy in post‐earthquake building assessments. The methodology is demonstrated through an application study of ductile reinforced concrete frame buildings. Results show that aggregated indices of structural component damage (e.g., aggregated over the floor of a building) outperform other damage indicators based on peak or residual drifts or simpler percentages of damaged components. Subject to agreement of a number underlying assumptions, this methodology can be applied to a wider variety of structures to improve post‐earthquake evaluation guidelines.

Simulation of blast-induced rock tunnel damage using a 3D numerical model

The field tests conducted by the American Engineering Research Associates (ERA) provided important results about the distribution and extension of the damage zones and the failure area that occurred in unlined tunnels as a result of buried explosions in the rock mass surrounding these tunnels. Despite the importance of these results, they did not include specific values for the failure thickness and the fracture angle in the damaged tunnel sections. In the current study, a 3D numerical model is used to simulate one of ERA’s tests using ABAQUS. In this model, the impact of a buried explosion on a tunnel located at (5m) away from the center of the detonation is studied. The results of this model are in good agreement with the published results of ERA’s tests. In addition, the current numerical results give complete values for the change in the failure thickness and the fracture angle over the entire length of the damaged zones of the tunnel. The results of the current study show that the thickness of the failure remains almost constant beyond damage zone 1, while the angle of the fracture decreases remarkably as the charge-to-tunnel distance increases, which causes a decrease in the failure area.

Study on Joint Damage of Double Prefabricated Fragments Penetrating Finite Thickness Concrete

In order to study the joint damage mechanism of multiple prefabricated fragments to finite thickness concrete targets, experiments on the damaging effect of a single fragment on a 300 × 300 × 100 mm concrete target were carried out, and the reliability of the simulation calculation model of single fragment damage to concrete was verified. On this basis, according to the trajectory of two fragments penetrating concrete, the double fragment penetration is divided into two penetration situations, that is, coplanar and heterogeneous. The orthogonal optimization method is used to carry out the joint damage simulation calculation of the double fragments to the concrete target by changing the fragment velocity, penetration angle, fragment spacing, and other factors. The simulation results show that the relationship between joint damage and fragment spacing is the largest when the fragment trajectories are coplanar, and the partial least squares regression coefficients affecting the joint damage time and surface joint length are 0.70 and 0.68 respectively. When the trajectory is different, the joint damage mode is relatively complex. Based on this, the joint damage degree analysis method between fragments is established, and each variable can explain 73.8% of the joint damage degree. It is found that the joint damage of the front pit area is the largest when the fragment is in different planes, and the PLS regression coefficient is −0.44. The hypothesis that joint damage is easy to occur in the area of the intersection line on the back of the target is analyzed and verified.

Evaluation of Radiological Effects on the Aptamers to Remove Ionic Radionuclides in the Liquid Radioactive Waste

Background: Aptamers are currently being used in various fields including medical treatments due to their characteristics of selectively binding to specific molecules. Due to their special characteristics, the aptamers are expected to be used to remove radionuclides from a large amount of liquid radioactive waste generated during the decommissioning of nuclear power plants. The radiological effects on the aptamers should be evaluated to ensure their integrity for the application of a radionuclide removal technique.Materials and Methods: In this study, Monte Carlo N-Particle transport code version 6 (MCNP6) and Monte Carlo damage simulation (MCDS) codes were employed to evaluate the radiological effects on the aptamers. MCNP6 was used to evaluate the secondary electron spectrum and the absorbed dose in a medium. MCDS was used to calculate the DNA damage by using the secondary electron spectrum and the absorbed dose. Binding experiments were conducted to indirectly verify the results derived by MCNP6 and MCDS calculations.Results and Discussion: Damage yields of about 5.00×10<sup>-4</sup> were calculated for 100 bp aptamer due to the radiation dose of 1 Gy. In experiments with radioactive materials, the results that the removal rate of the radioactive <sup>60</sup>Co by the aptamer is the same with the non-radioactive <sup>59</sup>Co prove the accuracy of the previous DNA damage calculation.Conclusion: The evaluation results suggest that only very small fraction of significant number of the aptamers will be damaged by the radioactive materials in the liquid radioactive waste. Keywords: Aptamer, Liquid Radioactive Waste, Decommissioning, Decontamination, Radiological Damage

Micro-mechanical damage simulation of filament-wound composite with various winding angle under multi-axial loading

With the application of Filament Wound Composites (FWC) in the market, the general model for composites with different process parameters is urgently needed. In this paper, a generalized full-scale 3D finite element model (FEM) is established considering the fluctuation and lamination characteristics of FWC fiber arrangement. The Generalized Method of Cell (GMC) is embedded into the commercial FEM code of ANSYS as user-defined subroutine (UMAT) to obtain the micromechanics of the component materials and the macro-structural scale and the micro-structural scale are thus linked. For the damage analysis, three different failure criteria are used to explore the failure process of materials under different loads. The comparison of the predicted results with the experimental results shows that the simulation method can reflect the progressive damage of FWC under different loading conditions well. Furthermore, the effects of the winding angle on the mechanical properties of FWC under different loads are also investigated. The results show that the modulus and strength of the material decrease as the angle increases under pure tensile loading, and both the modulus and strength reach the maximum when the winding angle is 45 under torsional loading. Under tensile-torsional loading, the maximum strength value of the material is related to the tensile-torsional stress ratio.

Numerical Simulation of the Seismic Damage of Daikai Station Based on Pushover Analyses

Numerical analysis is an important method for the study of seismic performance of underground structures. Current research on the seismic damage of Daikai station and the subway tunnel during the Great Hanshin earthquake mainly focuses on the dynamic time-history analysis. However, the modeling process of the dynamic time-history analysis is complicated and shows the characteristics of the enormous calculation amount, long running time and low computation efficiency. This paper briefly introduces the seismic phenomena of Daikai station and the subway tunnel during the Great Hanshin earthquake. The internal forces of Daikai station and the subway tunnel under horizontal and vertical bi-directional seismic effects are obtained by simplified seismic analysis. The pushover analyses of the columns are carried out to obtain the seismic performance curves of the columns under different vertical pressures by considering various loading and restraint conditions. Finally, the pushover analyses of the soil-structure system are carried out to reproduce the seismic damage of Daikai station and subway tunnel under horizontal and vertical bi-directional seismic effects. The results show that the computed damage is similar to the actual damage. The pushover analysis method, which considers both horizontal and vertical inertia forces of the soil, can be used to simulate the damage and study the collapse mechanism at Daikai station. Compared with the dynamic analysis, the calculation efficiency of the pushover analysis method is significantly higher; it is therefore suggested to use pushover analysis in seismic analysis of underground stations.

High-fidelity simulation of low-velocity impact damage in fiber-reinforced composite laminates using integrated discrete and continuum damage models

A high-fidelity finite element (FE) model based on integrated discrete and continuum damage modeling techniques was developed to predict damage modes, locations, sizes, and damage occurrence sequence in a composite laminate during a low-velocity impact event. Fiber breakage and transverse matrix cracking were captured using the three-dimensional Hashin’s criteria, and delamination was captured by inserting a layer of cohesive elements between every adjacent composite ply. Delamination progression from one layer to another was captured by embedding cohesive elements inside each composite ply aligned with the fiber orientation and with a 45° angle to the thickness direction. The refined mesh and intralaminar cohesive elements were only used in the predicted damage region based on an analytical solution. The FE model predicted impact response was validated by drop-weight tests, and the layer-by-layer damage areas were validated and characterized by X-Ray CT inspections on 254 mm by 304.8 mm IM7/977-3 laminates with a stacking sequence of [0/45/90/-45]4s. The absorbed energy, damage areas, maximum deflection, contact time, and peak load were predicted with less than 10% error. The detailed damage occurrence sequence during the impact event was predicted through histories of energies dissipated by different damage modes. The modeling methodology developed in this work highlights the effects of modeling parameters on convergence, solution accuracy and computational efficiency, and provides an effective approach for progressive damage modeling of composite laminates.

Neutron-induced damage simulations using MCNP6 and SRIM codes: Beyond neutron transmutation doping of silicon

When a high degree of consistency and precision in dopant (phosphorous) distribution is required, the NTD technique is used, but neutron irradiation made damages in the silicon. This study focused on neutron-induced damage to silicon, as well as phosphorus produced inside the irradiated samples. The evolution of the resistivity and the surface morphology versus Displacement per Atom (DPA) was determined in addition, it used the Monte Carlo Neutron Transport simulation MCNP6 and SRIM codes for estimation of DPA. In this work, among the most important results obtained from experimental and simulation methods, it was found that: resistivity and RMS increased with an increasing DPA, this phenomenon occurred after neutron irradiation. The experimental results show good agreement with the simulation data. Furthermore, the enhancement of irradiation times leads the resistivity values to attain saturation. This later reaches a stability value above 11 × 1016 Displacement /cm3 between 0.74 and 3.96 × 1018n/cm2.

Time-Domain Structural Damage and Loss Estimates for Wind Loads: Road to Resilience-Targeted and Smart Buildings Design

A time-domain wind-induced damage evaluation for the risk- and resilience-targeted design of building structures requires nonlinear dynamic analysis (NDA) solvers to handle long duration input loads. Moreover, post-construction damage identification based on real-time vibration monitoring depends on accurate damage simulation from the design stage and available artificial intelligence (AI)-based technology. In this paper, an integrated time-domain approach for the performance-based analysis and design for wind is presented. The nonlinear dynamic analysis (NDA) is performed with the Force Analogy Method (FAM) and the state–space formulation to solve the nonlinear equations of motion. Then, the Incremental Dynamic Analysis (IDA) is used to perform probabilistic fragility analyses for a typical reinforced concrete (RC) frame structure. The analysis also provides estimates of expected losses, gives the building owners business support data to compare, e.g., the final annual building income (FABI), the cost of repair and the function recovery duration for various wind events in an integrated resilience-based building design framework. This provides the basis for mapping structural damage on large urban scales and for straightforward quantification of wind-induced damage from available response acceleration time-series acquired from real-time vibration monitoring.

Minimally Invasive Retrofitting of RC Joints with Externally Applied SMA Plate—Adaptive Design Optimisation through Probabilistic Damage Simulation

Beam–column joints are the critical section of many reinforced concrete (RC) structure types in which any failure could lead to the collapse of the entire structure. This paper attempts to employ a superelastic shape memory alloy plate as an innovative and adaptive external strengthening element to rehabilitate existing concrete beam–column joints and enhance the structure’s performance. An experimentally investigated beam–column joint is used as the case study, and it is investigated numerically to validate the effects of an innovative strengthening technique based on shape memory alloys. The results show that the proposed technique could increase the joint’s stiffness and reduce the risk of overall failure. A particular innovation in the proposed method is associated with the novel material itself but also with the fact that the increased potential costs of using special alloys are counteracted by its potential to produce these elements in an optimised industrially produced fastened plate. This fits-all construction product further allows a rapid and minimally invasive strengthening technique. Moreover, to achieve this, the plate is adaptively designed against random critical load combinations through probabilistic damage prediction.

A novel framework to study community-level social and physical impacts of hurricane-induced winds through synthetic scenario analysis

Strong hurricane winds often cause severe infrastructure damage and pose social and economic consequences in coastal communities. In the context of community resilience planning, estimating such impacts can facilitate developing more risk-informed mitigation plans in the community of interest. This study presents a new framework for synthetically simulating scenario-hurricane winds using a parametric wind field model for predicting community-level building damage, direct economic loss, and social consequences. The proposed synthetic scenario approach uses historical hurricane data and adjusts its original trajectory to create synthetic change scenarios and estimates peak gust wind speed at the location of each building. In this research, a stochastic damage simulation algorithm is applied to assess the buildings’ physical damage. The algorithm assigns a damage level to each building using the corresponding damage-based fragility functions, predicted maximum gust speed at the building’s location, and a randomly generated number. The monetary loss to the building inventory due to its physical damage is determined using FEMA’s direct loss ratios and buildings’ replacement costs considering uncertainty. To assess the social impacts of the physical damage exposure, three likely post-disaster social disruptions are measured, including household dislocation, employment disruption, and school closures. The framework is demonstrated by its application to the hurricane-prone community of Onslow County, North Carolina. The novel contribution of the developed framework, aside from the introduced approach for spatial predicting hurricane-induced wind hazards, is its ability to illuminate some aspects of the social consequences of substantial physical damages to the building inventory in a coastal community due to the hurricane-induced winds. These advancements enable community planners and decision-makers to make more risk-informed decisions for improving coastal community resilience.

Ductile fracture simulation using phase field method with various damage models based on different degradation and geometric crack functions

For simulation of ductile fracture, plasticity and damage are two essential aspects. The phase field method emerged as an efficient mathematical tool to address the fracture processes involving crack initiation, merging, and branching. From the wide literature, it has been observed that the information on the suitability of the existing phase field models for simulation of ductile fracture is scanty. This paper proposes a phase field methodologies for simulation of ductile fracture considering the aspects like different degradation and crack geometric functions. The proposed formulation couples the damage model, constitutive behaviour of elasto-plastic solid and J2 plasticity. Numerical simulations are carried out using ABAQUS with user-defined element (UEL) subroutine codes, defining the displacement field and phase field variable. Several benchmark problems were analysed to investigate the (i) behaviour of the specimen (ii) the performance of various phase field damage models (PFDM) and (iii) the effect of non-dimensional parameters considered in the damage models. The maximum percentage difference between the numerically predicted maximum load and its corresponding displacement is in good agreement w.r.t experimental value under PFDM4 (±10% range). The output of the study provides an insight on the use of various damage models and other parameters for the simulation of ductile crack propagation. This proposed model can be further extended to the prediction of remaining life or residual strength of the structural component.

Simulation of DNA damage using Geant4‐DNA: an overview of the “molecularDNA” example application

AbstractPurposeThe scientific community shows great interest in the study of DNA damage induction, DNA damage repair, and the biological effects on cells and cellular systems after exposure to ionizing radiation. Several in silico methods have been proposed so far to study these mechanisms using Monte Carlo simulations. This study outlines a Geant4‐DNA example application, named “molecularDNA”, publicly released in the 11.1 version of Geant4 (December 2022).MethodsIt was developed for novice Geant4 users and requires only a basic understanding of scripting languages to get started. The example includes two different DNA‐scale geometries of biological targets, namely “cylinders” and “human cell”. This public version is based on a previous prototype and includes new features, such as: the adoption of a new approach for the modeling of the chemical stage, the use of the standard DNA damage format to describe radiation‐induced DNA damage, and upgraded computational tools to estimate DNA damage response.ResultsSimulation data in terms of single‐strand break and double‐strand break yields were produced using each of the available geometries. The results were compared with the literature, to validate the example, producing less than 5% difference in all cases. Conclusion: “molecularDNA” is a prototype tool that can be applied in a wide variety of radiobiology studies, providing the scientific community with an open‐access base for DNA damage quantification calculations. New DNA and cell geometries for the “molecularDNA” example will be included in future versions of Geant4‐DNA.

A diagnostic framework with a novel simulation data augmentation method for rail damages based on transfer learning

The ultrasonic guide wave (UGW) has good application prospects in steel rail damage diagnosis, but the features of the rail damage implied in the UGW are complex. Deep learning enables an end-to-end approach to fault diagnosis. Nevertheless, a large amount of diversity data is needed for training, whereas the ultrasonic wave guide signals of simulation and repeated experiments lack diversity. Therefore, in this paper, a diagnostic framework based on simulation and transfer learning for rail damage is developed to tackle the problems mentioned above. The proposed framework is based on deep learning with a simulation pretraining strategy to build convolutional neural network (CNN) models through parameter fine-tuning for damage diagnosis. Specifically, for the problem that the simulation data lacks diversity, a damage mechanism-based data diversity augmentation method is proposed; this obtains the diagnostic high-value simulation data including supporting features, and expanded the diversity of the simulation data. Adopting the proposed method of data augmentation and transfer learning (TL), a diagnostic model for rail damage utilizing augmented UGW signals is constructed. The finite element simulation data of UGW with damages at different locations and depths of rails are augmented to achieve the pretraining of CNN models, and the model transfer is performed with the experimental data of rails. Ultimately, through comparative studies it can be concluded that (1) The TL diagnostic framework makes full use of the finite element simulation data to realize the model pretraining. (2) The proposed data augmentation method realizes the diversity expansion of simulation data containing supporting features and ensures the efficient application of simulation data in model pretraining.

Efficient atomistic simulations of radiation damage in W and W–Mo using machine-learning potentials

The Gaussian approximation potential (GAP) is an accurate machine-learning interatomic potential that was recently extended to include the description of radiation effects. In this study, we seek to validate a faster version of GAP, known as tabulated GAP (tabGAP), by modelling primary radiation damage in 50–50 W–Mo alloys and pure W using classical molecular dynamics. We find that W–Mo exhibits a similar number of surviving defects as in pure W. We also observe W–Mo to possess both more efficient recombination of defects produced during the initial phase of the cascades, and in some cases, unlike pure W, recombination of all defects after the cascades cooled down. Furthermore, we observe that the tabGAP is two orders of magnitude faster than GAP, but produces a comparable number of surviving defects and cluster sizes. A small difference is noted in the fraction of interstitials that are bound into clusters.

Computational modeling and a Geant4-DNA study of the rejoining of direct and indirect DNA damage induced by low energy electrons and carbon ions

Purpose DNA double-strand breaks (DSBs) created by ionizing radiations are considered as the most detrimental lesion, which could result in the cell death or sterilization. As the empirical evidence gathered from the cellular and molecular radiation biology has demonstrated significant correlations between the initial and lasting levels of DSBs, gaining knowledge into the DSB repair mechanisms proves vital. Much effort has been invested into understanding the mechanisms triggering the repair and processes engaged after irradiation of cells. Given a mechanistic model, we performed – to our knowledge – the first Monte Carlo study of the expected repair kinetics of carbon ions and electrons using on the one hand Geant4-DNA simulations of electrons for benchmarking purposes and on the other hand quantifying the influence of direct and indirect damage. Our objective was to calculate the DSB repair rates using a repair mechanism for G1 and early S phases of the cell cycle in conjunction with simulations of the DNA damage. Materials and Methods Based on Geant4-DNA simulations of DSB damage caused by electrons and carbon ions – using a B-DNA model and a water sphere of 3 μm radius resembling the mean size of human cells – we derived the kinetics of various biochemical repair processes. Results The overall repair times of carbon ions increased with the DSB complexity. Comparison of the DSB complexity (DSBc) and repair times as a function of carbon-ion energy suggested that the repair time of no specific fraction of DSBs could solely be explained as a function of DSB complexity. Conclusion Analysis of the carbon-ion repair kinetics indicated that, given a fraction of DSBs, decreasing the energy would result in an increase of the repair time. The disagreements of the calculated and experimental repair kinetics for electrons could, among others, be due to larger damage complexity predicted by simulations or created actually by electrons of comparable energies to x-rays. They are also due to the employed repair mechanisms, which introduce no inherent dependence on the radiation type but make direct use of the simulated DSBs.

Experimental simulation for moisture damage of saturated asphalt mixture and evolution of mixture’s pore water pressure, accumulative strain

Moisture damage has significant impact on pavement’s performance and service life, researching this kind of distress’ mechanical mechanism, experimental simulation protocol or theoretical analysis method continues to be the research that should be conducted in depth for pavement researchers. But, due to the complexity of this distress’ influencing factors, there is still not a satisfactory research result by far, particularly for its experimental simulation test, the current research lack of a satisfactory apparatus or protocol that can simulate asphalt mixture’s moisture damage in lab. So then, this paper, basing on a fully mechanical analysis in advance for asphalt pavement’s moisture damage, develops an experimental apparatus being capability to simulate and investigate asphalt mixture’s moisture damage in lab by improving a dynamic triaxial tester, then utilizes this improved triaxial tester investigate moisture damage of asphalt mixture with different air void percent or applied by different confining pressure, and acquires these mixture’s characteristics regarding their pore water pressure evolution, strain cumulation, specimen deformation as well as their influencing factors, then classifies these test results into three types according to their characteristics. The test results demonstrate, this developed apparatus can comparatively satisfactorily simulate mixture’s moisture damage phenomena in lab, its simulation test results are close to field investigation results, and air void percent, confining pressure and loading frequency are the principal factors that have significant impact on mixture’s moisture damage test results. For the specimen with lower air void percent or under a higher confining pressure, their test results are primarily type 1, whose pore water pressure and cumulative strain are relatively low, deformation are pure compression. Whereas, for the specimen with larger air void percent or applied by higher confining pressure, their pore water pressure and cumulative strain are usually larger, specimen are generally observed with stripping or cracking in the end of test, even some are found with diagonal cracks, these characteristics are classified as type 3. As for type 2, their test results are primarily between that of type 1 and type 3, their pore water pressure, cumulative strain are relatively large, yet specimen’s deformation mainly attribute to compression, and only swelling in radial direction or slight stripping are found with specimens.