Macro Parameters Research Articles

Implementation and validation of a bonded particle model to predict rheological properties of viscoelastic materials

This work focuses on implementing a particle-based method able to characterize viscoelastic materials whose rheological properties, such as storage modulus G’ and loss modulus G”, are known. It is based on the Bonded Particle Model, with the elastic constitutive relation here substituted with a viscoelastic one to capture time-scale effects. The Burgers model, vastly used in literature to model viscoelastic systems, is discretized and implemented. The test case used for calibration comprises of a cubic lattice, sheared with a periodic motion, to mimic the effect of a shear rheometer. After appropriate filtering of the stress response, the rheological properties are obtained, highlighting the effect of the lattice geometry, as well as the particle size, on the accuracy of the model. Moreover, the Burgers parameters are calibrated by analytically fitting the experimental dataset, showing the limitation of the Burgers model. The micro-contact parameters are obtained from the macro parameters through appropriate scaling. After completing a frequency sweep, the simulated G’ and G” show a relatively large error, around 25% for G’ for example. For this reason, a more robust model, namely the Generalized Maxwell Model, has been implemented. The calibration procedure is performed in the same fashion as for the Burgers model. Moreover, the tangential micro-contact parameters are scaled w.r.t. the normal ones. This scaling parameter, called α, is calibrated by minimizing the Root Mean Square Error between simulation and experimental data, giving errors below 10% in both G’ and G” for a large dataset. Additionally, a full ring plate-plate rheometer setup is simulated, and the simulation is compared with the given experimental dataset, again finding a good agreement.

Three-dimensional Meso-scale virtual strength test of steel slag porous asphalt mixture based on PFC3D

In recent years, steel slag has gained widespread utilization in pavement construction as a green, low-carbon building material. In this study steel slag aggregate (SSA) was used as a partial replacement for basalt aggregate in porous asphalt mixture. To gain an in-depth understanding of the microscopic cracking characteristics of steel slag aggregate porous asphalt concrete (SSA-PAC), laboratory three-point bending tests and numerical simulations were conducted. Based on CT scanning images, 3D models of SSA and basalt aggregates within particle size ranges of 4.75–9.5 mm and 9.5–13.2 mm were generated. These characteristic aggregates were then randomly placed to establish a three-dimensional model using PFC3D (Particle Flow Code in 3 Dimensions). The micro-contact parameters were derived through the conversion and calibration of macro and micro-mechanical parameters. The results of the 3D virtual strength test exhibited a close resemblance to those obtained from laboratory semi-circular bending (SCB) tests. The displacement trend chart of the aggregates revealed three distinct stages: vertical displacement, vertical displacement combined with a small amount of lateral displacement, and lateral displacement. Cracking mainly occurred at the interface between the aggregates and asphalt mortar, which aligned with actual cracking scenarios. The cracking behavior of the asphalt mixture was characterized by evaluating the number of cracks, notch width, and coordination number throughout the loading process. Additionally, the influence of loading rates on cracking behavior was analyzed. The results of this study demonstrated that the established 3D model effectively revealed the cracking characteristics of SSA-PAC.

Discrete Element Study on Mesoscopic Shear Mechanical Behavior of Fully Weathered Coastal Red Sandstone Considering Different Rock Mass Stability Grades

The macro parameters such as cohesion and internal friction angle are usually measured on experimental test. The macro shear mechanical behaviors are determined by mesoscopic shear mechanical behaviors, which are difficult to be measured accurately on experimental test. This paper aims to study the mesoscopic shear mechanical behaviors of fully weathered coastal red sandstone (FWCRS) such as the force and displacement of rock particles, the force chain network, the microcracks and the coordination number, which can be systematically studied by discrete element software such as Particle Flow Code (PFC). This paper established models characterizing FWCRS with different rock mass stability grades by results obtained on experimental tests, and investigated the differences of their mesoscopic shear mechanical behaviors. The results show that the mesoscopic shear mechanical behaviors of FWCRS can be characterized by performing direct shear simulation and the differences among different rock mass stability grades were also revealed. As the stability increases from grade 1 to grade 5, the shear stiffness increases, the number of microcracks reduces by 48.07%, and there are significant differences in properties of shear band, development of microcrack, the coordination number and the force chain network. The research results can provide reference for the related research such as the evolution of mesoscopic shear mechanical behaviors in the failure process of rock mass in FWCRS and similar strata.

Study of the damage and cracking of heterogeneous rocks based on the FFT method - A comparison of computer generation and image reconstruction models

Studying the influence of microstructure on the damage and cracking process of rocks is of great practical engineering importance for evaluating the mechanical properties of surrounding rocks in complex geological engineering environments. To incorporate rock microstructures into numerical models, two main methods, i.e. computer generation methods (e.g. molecular dynamics, MD) and image reconstruction methods (e.g. digital image processing, DIP), are frequently adopted. However, the strengths and weaknesses, the differences and applicability regarding the two major methods have not been systematically discussed and analyzed in simulating the damage and cracking in heterogeneous rocks. In this study, the MD model was firstly optimized based on the previous work, and the “Realistic grain size based microstructure model generation program” was developed by the observed mineral grain sizes from microscopic images. The DIP model was developed by directly using digital images of rock materials via the image reconstruction methods. On this basis, the damage and cracking process of rocks was investigated and compared with the above two models using a technique based on the Fast Fourier transforms (FFT). To this end, a series of macro and micro experiments were conducted to obtain the basic mechanical properties of the Dingziwan Granite (DG) and several examples are generated by the MD and DIP model with calibrated macro and micro parameters by the laboratory data. The two models combined with the FFT method are applied to predict the macro and micro mechanical behavior of the DG under different confining pressures and their differences and applicability are quantitatively analyzed and compared. The results indicate that, in general, the two models are both capable of predicting the macro and micro mechanical behaviors of the heterogeneous rocks, but each has its own strength. The improved MD model can efficiently study the influence of the rock heterogeneity on its macroscopic behavior, while the DIP model can highly reproduce the microcracking process such as intragranular, transgranular and grain boundary cracking.

Comprehensive evaluation of ballastless-track sealants based on macro–micro tests and principal component analysis

In order to establish a comprehensive evaluation system of ballastless-track sealants, a method is put forward based on macro–micro tests and principal component analysis(PCA). In this study, the performance parameters of four different ballastless-track sealants (SE, NI, WQ, SY) were obtained by low-temperature performance test, atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS) test. Then the PCA method was conducted to reveal the complex relationship between macro and micro performance parameters of sealants, such as the maximum tensile force, the maximum failure displacement, the surface roughness, the surface adhesion, the chemical bonding rate with SiO2, and the principal component contribution rate was calculated. Finally, the comprehensive score was utilized to evaluate the performance of different sealants. The results show that the macroscopic properties of the sealant are closely related to the microscopic parameters roughness, surface adhesion and chemical bonding rate of SiO2. The macro–micro performance parameters of sealant are comprehensively evaluated through PCA, and the results are as follows: NI > SE > WQ > SY. The PCA can comprehensively evaluate the performance of sealant intuitively and accurately, avoiding the subjective influence of evaluating the material performance only through macro-tests or micro-tests.

Avalanche-size distribution of Cayley tree

Attacks on networks is a very important issue in developing strategies of eradicating spreads of malicious phenomena in networks, such as epidemics and fake information. This field of research is referred to as networks immunization. The traditional approach to evaluating the effectiveness of attacks on networks focuses on measuring macro parameters related to the entire attack, such as the critical probability of a percolation occurrence in the network p_c and the relative size of the largest component in the network, known as the giant component, but not considering the attack on a micro perspective, which is the analysis of node removals, during an attack, themselves, their characteristics and results. In this paper we present and apply the last method of focusing on the micro scale of an attack. Based on the theory of percolation in networks, we analyze the phenomenon of an avalanche which results due to a single node removal from a network. An avalanche is a state in which a removal of a single node from the giant component of a network leads to the disconnection of additional nodes. This process significantly contributes to the fragmentation (immunization) of the network, comparing to the impact of the initial node removal alone. Specifically, we focus on the size parameter of an avalanche, which is the number of nodes that are disconnected from the giant component due to a single node removal. Relating to a random attack on a network of the type of Cayley tree, we derive analytically the distribution of the sizes of avalanches that occur during the entire attack on it, until the network is dismantled (immunized) and the attack is terminated.

Understanding the Level of Turbulence by Asymmetric Distributions: A Motivation for Measurements in Space Plasmas

In this article, on the basis of the Langevin equation applied to velocity fluctuations, we numerically model the partial variance of increments, which is a useful tool to measure time and spatial correlations in space plasmas. We consider a coupled map lattice model to relate the spatial scale of fluctuations, k, to some macro parameters of the systems, such as the Reynolds number, R λ , the κ parameter of Kappa distributions, and a skewness parameter, δ. To do so, we compute the velocity probability density function (pdf) for each spatial scale and different values of Reynolds number in the simulations. We fit the pdf with a Skew–Kappa distribution, and we obtain a numerical relationship between the level of turbulence of the plasma and the skewness of obtained distributions, namely, . We expect the results exposed in this paper to be useful as a tool to characterize the turbulence in the context of space plasma and other environments.

Is the remittance inflow to the Turkish economy sustainable? A glimpse of the future through the lens of the past.

The impact of global remittance inflows on numerous macro and microeconomic parameters has long piqued the interest of researchers, policymakers, and academics. Remittances have always been vital to Turkey's development as a remittance recipient country. However, this trend has recently changed, Turkey is currently receiving significantly less remittance, and this reduction in remittance is well noted in its economic performance. This study is an attempt in this regard to find out whether remittance inflow to Turkey will be sustained in the future or its decline will continue. The findings of this study will provide insight to the country's economic and financial policymakers in devising policies that would ensure future remittance inflows. An auto-regressive integrated moving average (ARIMA) approach is applied, and remittance inflow data from 1974 to 2019 is used to forecast remittance inflow for the next 11 years till 2030. According to the results, remittances would drop to a level of -1.00 percent of GDP in 2030, down from 4.00 per cent in 1974.

Evolution and Influencing Mechanisms of the Yili Loess Mechanical Properties under Combined Wetting-Drying and Freeze-Thaw Cycling.

Landslides frequently occur in the loess-rich Yili region of Xinjiang, China, due to the combined effects of wetting-drying and freeze-thaw (WD-FT) cycles, which cause changes in the soil/loess internal structure and shear strength. This paper explores the combined effect of WD-FT cycles on the shear strength evolution of Yili loess through cyclic and triaxial shear tests. The micromechanism of the effect of WD-FT cycles on the loess properties is studied through scanning electron microscopy tests. Finally, the gray correlation analysis method assesses the correlation between relevant macro and micro parameters. The results show that: (1) With the increase in WD-FT cycles, the cohesion of loess decreases first and then gradually stabilizes, while the internal friction angle first grows and then drops before stabilizing. This indicates that the WD-FT cycles cause different degrees of decline in the soil's internal friction angle and cohesion. (2) As the number of WD-FT cycles increases, the average abundance and directional probability entropy fluctuate slightly, gradually decreasing and stabilizing. In contrast, the particle size dimensionality gradually decreases and stabilizes, and the pore area ratio first increases and then gradually stabilizes. (3) Six microstructural parameters (average diameter, average abundance, particle size dimensionality, directional probability entropy, particle roundness, and pore area) are selected for correlation analysis with the shear strength index of loess. The results show that the particle size dimensionality closely correlates with macroscopic internal friction angle under coupled cycling, while the pore area closely correlates with macroscopic cohesion. These findings are instrumental in preventing and controlling loess landslides caused by WD-FT cycles in the Yili region of Xinjiang, China, and similar loess-rich regions.

Particle flow study on the microscale effects and damage evolution of sandstone creep

The creep damage of hard rock is significantly influenced by its microscopic parameters and pore structure. To explore the correlation between the macroscopic creep characteristics and microscopic properties of sandstone, the construction method of Clumps with random geometry (CRG) that can simulate the creep movement of minerals was proposed. Through seepage corrosion tests and uniaxial creep tests, a rock porous creep model was established, and the CRG model was used to investigate the evolution pattern of rock fracture and the relationship between macro and micro parameters. The results demonstrate that the creep parameters of red sandstone are significantly affected by its microporosity. When particles range from 0.05 to 2 mm, the instantaneous and creep mechanical properties of the CRG model are strongly dependent on contact parameters and porosity, but less sensitive to particles size. The simulation based on CRG is in good agreement with the laboratory tests, with a certain proportional relationship existing between the microscopic contact parameters of the numerical model and the macroscopic creep parameters of the laboratory test.

1700-P: Optimizing Data Cleaning Methods for Remotely Collected Electronic Weight Measurements

Background: Digital smart scales transmit weight measurements collected outside of clinical settings to medical and research teams. Statistical packages such as SAS %TPF (TrueProfileFinder) can ensure weights belong to persons of interest instead of others who may use the scale; however, validation is required. Methods: We obtained 32,917 remotely collected weights from 222 postpartum participants using BodyTrace scales in the Pregnancy, Environment, and Lifestyle Study-2 (PETALS-2). To assess the SAS %TPF macro's performance, we applied 18 combinations of its three modifiable parameters (number of observations in a moving window, importance of weights from clinic visits, and prediction band) to a random subsample (N=16). In parallel, two manual reviewers independently classified weights as ‘belonging’ or ‘not belonging’ to participants; Cohen's κ ≥0.91 confirmed adequate interrater agreement. Outputs from the 18 models were then compared to the manual review. Results: As hypothesized, adjusting parameters impacted the macro's ability to identify weights truly belonging to participants (percent true calls). Prediction band, the predicted range for new observations based on a linear regression model, was the only parameter associated with macro performance. A prediction band of 15 lbs. was associated with a 2.71% (95% CI: 0.16%, 5.25%) increase in percent true call and 5.57% (95% CI: 1.77%, 9.38%) increase in sensitivity vs. a band of 10 lbs. Percent true call for a prediction band of 15 lbs. was 2.95% higher, but non-significant (p=0.18) vs. a band of 20 lbs. A prediction band of 15 lbs. was highly accurate (>97% true call) and sensitive (>98%). Conclusion: Weight is often assessed in interventions for glycemic control and diabetes prevention. Precise data cleaning can increase accuracy of unsupervised, remotely collected measurements. Clinicians and researchers using smart scales can apply this data cleaning method to identify SAS %TPF macro parameters that maximize accuracy. Disclosure S.Daredia: None. B.P.Smith: None. H.Serrato bandera: None. A.Millman: None. C.Quesenberry: None. A.Ferrara: None. S.D.Brown: None. Funding National Institutes of Health (R01HL142996)

Research on detection method of concrete compressive strength based on dielectric properties

Compressive strength of concrete structures is a crucial quality parameter that determines their performance throughout lifespan. This study introduces an innovative approach of utilizing electromagnetic nondestructive testing to assess the compressive strength of mature concrete. The dielectric constant and compressive strength of standard specimens were tested by open coaxial probe and pressure testing machine, respectively, using ordinary Portland cement concrete with various water-cement ratios (0.4, 0.45, 0.5, 0.55, 0.6 and 0.65) as the research object. It has been discovered that increasing porosity reduces the number of polarized particles per unit volume of concrete, resulting in a decrease in polarization intensity. This decrease is manifested as a reduction in the dielectric constant in macro parameters. The relationship between porosity and dielectric constant was characterized using a series-parallel composite concrete dielectric model. Additionally, as porosity increases, the compressive strength of concrete decreases exponentially. By considering porosity as an intermediate variable, a concrete compressive strength model based on the dielectric constant was established. The model exhibits an average error of 3.62%, indicating the precise characterization of concrete's compressive strength using the dielectric constant. This model can serve as a theoretical basis for the implementation of electromagnetic nondestructive testing techniques in strength evaluation.

Effect of pre-crack non-uniformity for mini-CT geometry in ductile tearing regime

The mini-CT specimen attracts the attention from all over the world for application in fracture toughness measurement. However, one of the shortcomings of this geometry is related to the required tight accuracy of the specimen dimensions, in particular the fatigue pre-crack curvature which often violates the requirements of the ASTM standards. Given the limited thickness of mini-CT geometry, non-uniform pre-crack tends to develop during fatigue pre-cracking, resulting in a large proportion of mini-CT specimens being considered invalid.Previous investigations have demonstrated that mini-CT specimens with excessive crack front curvature can still provide meaningful fracture toughness results. In this paper, the effect of pre-crack front non-uniformity on ductile fracture is studied: first, the difference of macro parameters such as the applied load, J-integral and crack tip stress–strain field are investigated to illustrate the varying fracture behavior related to non-uniform pre-crack. Next, two micro-mechanics-based approaches, the Rice-Tracey void growth model and Thomason void coalescence model, are integrated to compare the ductile fracture initiation conditions associated with uniform and non-uniform fatigue pre-crack. Finally, the experimental verification of the ductile fracture simulations is performed for mini-CT specimens with uniform and 30° tilted initial cracks. The results indicate that the pre-crack non-uniformity plays a major role in the redistribution of local J-integral and stress–strain state, further affects the position of crack initiation and the early stages of crack propagation. Nevertheless, the pre-crack non-uniformity has limited effect on the global properties that are usually expected from fracture toughness tests, such as applied load, J-R curve and critical fracture toughness. The requirements in the ASTM E1820 regarding pre-crack front curvature need thus to be relaxed.

Calibration and Sensitivity Analysis of Macro and Meso Parameters of Discrete Element Model for Coal Measure Soil

The orthogonal test sequence of the meso parameters of the discrete element model was designed by using the orthogonal test method. The calculation method of directly determining the meso parameters from the macro mechanical parameters was established by using the test simulation calculation results and the multi factor nonlinear joint inversion method. The proposed method was applied to the discrete element numerical simulation of triaxial test of coal measure soil. The results show that the numerical simulation results are in good agreement with the stress-strain curves of the triaxial test of coal bearing soil. Through error analysis, it is found that the maximum error of the partial stress peak is 5.4%, the error of the cohesion is 2%, the error of the internal friction angle is 7%, and the error is all within 10%. It verifies that the method for rapid determination of the meso parameters proposed in this paper is feasible, and provides a new idea for the calibration of the meso parameters in the discrete element numerical simulation method.

A Linearizing Transformation-Based Evaluation Approach of the Fundamental Diagram

The fundamental diagram (FD) describes the functional relationship among macro parameters of traffic flow (e.g., volume, density, and space mean speed). A well-established FD is crucial for traffic operations and management (e.g., traffic estimation and control). However, there is still lacking an efficient method to select a FD and evaluate the fitting performance with empirical data. In this paper, we propose a novel evaluation approach to the FD using a linear transformation method, which can evaluate the fitting performance in the whole density region. It can also provide directions for further optimization of the FD model by performing the same transformation on the empirical dataset and the selected FD. Furthermore, we propose a quantitative indicator, called the weighted coefficient of determination, which can better evaluate the fitting performance of different FDs. The proposed method is tested with freeway field data from loop detectors. The results show that the proposed evaluation method can help select the FD that fits the empirical dataset best. The evaluation results can also be used to analyze the systematic deviation ignored by those FDs that cannot fit the data well to further improve FD models.

Continuum and discrete element modelling for describing coupled hydro-mechanical effects of earthworm burrow coatings on soil shrinkage

Structured soils with earthworm burrows are locally heterogeneous due to coatings along these biopore walls that are superimposed on the inter- and intra-aggregate pore network of the soil matrix. The partially compacted finer-textured and organic matter-rich coatings can limit the flow exchange between the macropores and the soil matrix during preferential flow. Still unknown are dynamic hydro-mechanical interrelations in coating and matrix domains that affect stress–strain behaviour at the macroscopic scale. Such hydro-mechanic interactions may be described with the discrete element method (DEM) coupled with a two-phase pore finite volume (2PFV) approach if relevant pore structures are represented in the model. The objective was to develop a coupled DEM-2PFV model together with a parameterization procedure. Major task was to create a parameterization procedure to calibrate micro parameters of the model by macro properties quantified from drainage experiments of soil samples with earthworm burrow wall coatings.The solid phase was modelled by particle aggregation creating inter and intra-aggregate pore network for the soil matrix in a cube of about 5 cm edge length and one side with the coating structure. This DEM model was coupled with a 2PFV model to simulate hydro-mechanic effects during drainage. Sand box drainage experiments were carried out on soil matrix and biopore samples with laser surface elevation measurements to obtain the mechanical stress–strain macro parameters necessary for model calibration. The poly-dispersed DEM-2PFV model was able to describe effects of two-phase air–water flow on stress–strain macro parameters. The micro parameters (i.e., particle stiffness and bond strength) of the pore scale model were obtained from macro parameters of the primary and secondary stress–strain stages by training a random forest meta-estimator. The model was able to reproduce the pore network of coating material and the inter- and intra-aggregate pore network of the matrix that are dynamically changing with the effective stress. The machine learning model revealed that the bond strength among particles within aggregates governed the shrinkage of soil matrix, while the particle stiffness of the coating material reduced the susceptibility of aggregate breakage producing a more stable inter-aggregated pore network during the drainage process. This study confirmed that coating material present in biopore surface increases the horizontal soil hydro structural stability. The microscale hydro-mechanic modelling can be useful for finding flow exchange parameters inputs for upscaled models and correlating pore-scale parameters to experimentally determined stress–strain macro parameters.

Species specifics of morphology of the liver of the fishes of the Cyprinidae family

Providing mankind with high-quality products of aquaculture is possible only by introduction of modern industrial technologies to fish farming, growing fish based on modern scientific achievements. Assessment of the ecotoxic situation and identification of impacts of various unfavourable factors of aquatic environment on aquatic organisms should be made through morphological studies of the organs that are first to encounter the impact. The study revealed species specifics of the morphology of the liver of the fishes of the Cyprinidae family – Prussian carp (Carassius gibelio), Eurasian carp (Cyprinus carpio), and bighead carp (Hypophthalmichthys nobilis), which vary by extent of the motor activity in the aquatic environment, nutrition, etc. We determined that during phylogenetic development of fish that grow in the aquatic environment, there occurs a certain restructuring of the liver: the adaptation to various living conditions were accompanied by changes in a number of parameters of macro- and microscopic architectonics of the liver. Cyprinus carpio and Carassius gibelio (omnivores) have a two-lobe liver, while Hypophthalmichthys nobilis (a herbivore) has a three-lobe liver. For C. carpio and H. nobilis, a characteristic feature of the liver was presence of the hepatopancreatitis (the liver and the pancreas, associated into a single organ), and in C. gibelio, they are differentiated into individual organs. A peculiarity of the microscopic structure of the liver of the Cyprinidae family is poorly developed interlobular connective tissue, and parenchyma of the liver lobule has a tubular structure as polyhedral, curved thick-walled tubules, the walls of which are hepatocytes. The greatest amounts of cytoplasm and karyoplasms were seen in C. gibelio, equaling respectively 12.98 ± 1.42 and 0.40 ± 0.02 µm³. The lowest volume of the indicated parameters was in C. carpio, particularly 2.97 ± 0.22 and 0.21 ± 0.01 µm³, respectively. The lowest nuclear-cytoplasmic ratio was observed in hepatocytes of C. gibelio (0.0316 ± 0.0024). The conducted morphological studies at the levels of organs, tissues and cells can reveal how the fishes’ bodies adapt to particular living conditions and impacts of environmental factors.

Macro and micro damage analysis and parameter inversion of HTPB adhesive Interface based on DIC and FEMU

ABSTRACT In order to realize the quantitative analysis of the structural integrity and damage evolution of hydroxyl-terminated polybutadiene (HTPB) composite solid propellant under external load, the loading failure experiments were carried out on the macro rectangular specimen and the micro specimen, and the numerical analysis of the strain evolution process in the region of interest (ROI) of the specimen was carried out using digital image correlation (DIC). At the same time, with the help of finite element model updating (FEMU) method, the mechanical and cohesion parameters of the specimen were inversed using the combination of adaptive particle swarm optimization (APSO), back propagation (BP) and Hooke-Jeeves algorithm, and the simulation of the whole process of propellant damage and fracture was realized from the microscopic point of view. The results show that inhibiting the debonding of propellant/liner interface is the key to maintain the structural integrity. It starts with the damage and fracture of the propellant side. A scanning electron microscope (SEM) in-situ dynamic tensile test shows that the initial damage occurs at the strain of 27.368%, and the through-type crack propagates along the interface when the strain reaches 43.276%. In addition, the use of combinatorial optimization algorithm can realize the global optimal inversion of 16 parameters divided into three types in 100 complete calculations, reduce the optimal objective function value to 0.0251, and assist the finite element calculation to realize the quantitative analysis and accurate simulation of the experimental process.

The Preliminary Study of Liquefaction Susceptibility Map in the Yogyakarta-Bawen Toll Road Sections I and II, Indonesia

The parts of Yogyakarta-Bawen Toll Road Indonesia, based on the geological agency’s liquefaction susceptibility map are located on moderately susceptible to liquefaction soil. This map can be a preliminary indication of liquefaction as it can roughly indicate liquefaction potential. However, it cannot illustrate the actual condition in detail as its inputs are macro parameters (geological and seismicity factors). The existence of silty sand and sand, earthquake sources, and shallow groundwater increase the liquefaction possibility to occur in this important national project. Therefore, the Liquefaction Severity Index (LSI) and the Liquefaction Potential Index (LPI) using Sonmez’s and Iwasaki’s analysis methods are conducted with peak ground acceleration (PGA) of 0.322 g for the first section and in the second section 0.298 g. The results of the three types of analysis have relatively similar trends but the differences are in each category. The LSI’s categories are very low-moderate in the observed location, meanwhile, the LPI’s categories are low-very high.

Study on the determination mechanism of the compression wave velocity of soil-rock mixture considering the effect of soil-rock interface

The wave velocity of Soil-Rock Mixture (SRM) is an important index for seismic effect analysis of natural SRM site and quality evaluation of artificial SRM project. In order to clarify the compression wave velocity determination mechanism of SRM, a ternary mesoscale model of SRM including soil matrix, rock blocks and Soil-Rock Interface (SRI) was established based on the “Divide & Fill” method and calculated with 2D FEM code. The contact stiffness model was used to characterize SRI, and three typical contact models were assumed: ideal contact, ITZ (Interfacial Transition Zone) contact and cracked contact. The calculation formula of the compression wave velocity of SRM under ideal contact condition was given. The influence mechanisms of ITZ and crack on wave velocity under non-ideal contact conditions were expounded and the multi-factor competition mechanism for the influence of macro parameters such as rock content on the wave velocity was further clarified. These conclusions were verified by the wave velocity test experiments of loess-sand mixture under different pressure conditions. Finally, the damage variable of SRM was calculated according to the compression wave velocity under ideal and actual SRI, and was proposed to be one of the indexes to evaluate the quality of SRM.