MCC Model Research Articles

Parametric Study of the Deep Excavation Performance of Underground Pumping Station Based on Numerical Method

Environmental responses to deep excavations are combined results of numerous factors. The effects of some factors are relatively straightforward and can be considered carefully during the design. On the other hand, more features impact excavation-induced performances indirectly, making their influences difficult to be clearly understood. Unfortunately, the complexity and non-repeatability of practical projects make it impossible to thoroughly understand these issues through realistic deep excavation projects. Therefore, parametric studies based on repeatable laboratory and numerical tests are desired to investigate these issues further. This work examines the influence of several key features on excavation-induced displacements through a series of 3D numerical tests. The study includes the choice of soil constitutive models, the modeling method of the soil–wall interface, and the influences of various key soil parameters. The comparison shows that the MCC model can yield a displacement field similar to the HSS model, while its soil movement is greatly improved compared to the MC model. Both the soil–wall interface properties and soil parameters impact the excavation-induced displacement to a large extent. In addition, the influence mechanisms of these parameters are analyzed, and practical suggestions are given. The findings of this paper are expected to provide practical references to the design and construction of future deep excavation projects.

An effective stress-based approach to modeling the chemo-mechanical behavior of saturated active clay

Pore water chemistry can exert significant controls over the chemo-mechanical behavior of chemically active soils, which has not been characterized by using the traditional Terzaghi’s effective stress to a satisfactory extent. In this paper, based on the concept of intergranular stress, a generalized effective stress for saturated active soils is reconceptualized and incorporated into the framework of the modified Cam–Clay (MCC) model to describe the mechanical response of soils upon complex chemical and mechanical loadings. The proposed model is capable of capturing very well the diverse features of the chemo-behavior of saturated active soils, while inheriting all the advantages of the MCC model, by introducing only one additional parameter. Within this context, a simple equation is derived to predict the development of swelling pressure with the variation of pore water chemistry. It is shown that the proposed swelling-pressure equation predicts very well the development of swelling pressure for expansive soils with a dilute pore solution, though discrepancy appears at high concentration. Because the double layer of clay particles is severely suppressed at high salt concentration, the microfabric of soil can be significantly changed, pointing to the importance of taking into account the effect of soil fabric in the constitutive modeling of active soils with high pore water concentration.

Are markers of survival associated with perioperative outcomes for tumor thrombectomy patients?

Despite modern advances in surgical and perioperative technologies, management of renal cell carcinoma (RCC) with tumor thrombus (TT) is a morbid procedure that necessitates careful patient selection. It is not known whether established prognostic models for metastatic RCC are suitable prognostic tools for more immediate perioperative outcomes in patients with RCC with TT. We evaluated if established risk models for cytoreductive nephrectomy, as a potential extension of their purpose-built use, are associated with immediate perioperative outcomes in patients undergoing nephrectomy and tumor thrombectomy. Perioperative outcomes of patients who underwent radical nephrectomy and tumor thrombectomy for RCC were compared to presences of established predictors of long-term outcomes from prior risk models individually and as stratified by risk grouping (International Metastatic Renal-Cell Carcinoma Database Consortium [IMDC], Memorial Sloan Kettering Cancer Center [MSKCC], M.D. Anderson Cancer Center [MDACC], and Moffitt Cancer Center [MCC]). Wilcoxon rank-sum test or the Kruskal-Wallis test compared continuous variables and the chi-square test or Fisher's exact test compared categorical variables. Fifty-five patients were analyzed with 17 (30.9%) being cytoreductive. Eighteen (32.7%) patients had a level III or higher TT. Individually, preoperative variables were inconsistently associated with perioperative outcomes. Poorer risk patients per the IMDC model had more major postoperative complications (Clavien-Dindo grade≥3, P = 0.008). For the MSKCC model, poorer risk patients had increased intraoperative estimated blood loss (EBL), longer length of stay (LOS), more major postoperative complications, and more likely to discharge to a rehabilitation facility (P < 0.05). Less favorable risk patients per MDACC model had increased LOS (P = 0.038). Poorer risk patients per the MCC model had increased EBL, LOS, major postoperative complications, and 30-day hospital readmissions (P < 0.05). Overall, cytoreductive risks models were heterogeneously associated with perioperative outcomes in patients undergoing nephrectomy and tumor thrombectomy. Of available models, the MCC model is associated with more perioperative outcomes including EBL, LOS, major postoperative complications, and readmissions within 30 days when compared to the IMDC, MSKCC, and MDACC models.

A fractional-order two-surface plasticity model for over-consolidated clays and its application to deep gallery excavation

This paper proposes a novel fractional-order two-surface constitutive model for over-consolidated clays within the framework of the fractional plasticity and bounding surface theories. It incorporates the stress-fractional operator of the loading surface into isotropic and progressive hardening rules, thus obtaining an incremental stress–strain relation without an explicit plastic flow rule. The proposed fractional-order model can replicate the main features of over-consolidated clays well, including stiffness non-linearity, the occurrence of plastic strains before high peak strength, non-associativity, weak/strong dilatancy, and cyclic behavior. In model simulations on a set of element tests along different loading paths on natural Boom clay and remolded Fujinomori clay, the proposed model reveals better agreement than the modified Cam-Clay model (MCC). Next, the fractional-order model, ACC-2 model and MCC model are implemented via a user-defined material subroutine in ABAQUS with an explicit integration scheme based on the forward modified Euler method with automatic sub-stepping and error control. The different models are then applied to the fully coupled two-dimensional hydromechanical modeling of the excavation of two deep underground galleries in natural Boom clay. The results ultimately verify the validity and applicability of the proposed model.

Analyses on face stability of shallow tunnel considering different constitutive models

Based on the finite element limit analysis method, the stability of the face in case of active failure under three constitutive models, the Mohr-Coulomb model (MC), the modified Cambridge model (MCC) and the Drucker-Prager model (DP), were analyzed. The ultimate support pressure of the face and the influence of factors such as different burial depth ratios (C/D), cohesion (c) and friction angle (φ) in the MC model are also discussed. The results show that the safety factor obtained by the MCC model under the same support pressure is always smaller than that of the MC model, and the difference is the largest when there is no support pressure. As the support pressure increases, it will gradually approach the MC model. When the support pressure is small, the safety factor obtained by the DP model is larger than the MC model, but when the support pressure is large, it is smaller than the MC model, and the final difference tends to be stable. It is necessary to select an appropriate constitutive model according to different rock masses in practical engineering. The self-stabilizing performance of the face is not affected by C/D, and the ultimate support pressure will increase with the increase of C/D, decrease linearly with the increase of cohesion, and decrease with the increase of friction angle. When the friction angle is small, the ultimate support pressure is greatly affected by C/D, and when the friction angle is large, it is hardly affected by C/D.

Probabilistic Analysis of Ground Surface Settlement of Excavation Considering Spatial Variable Modified Cam-Clay Model Parameters

The modified Cam-clay model (MCC model) is capable of representing the consolidation process of the soil under a complex stress path and thus is extensively adopted in the numerical analysis of excavation engineering. For reliability problems of ground surface settlement of excavation, minimal attention has been paid to investigating the effect of spatial variable MCC model parameters on the settlement during the staged construction of the excavation. Based on laboratory tests and sensitivity analysis, this study launched the probabilistic transient hydro-mechanical coupling analysis of excavation settlement considering spatial variable deformation parameters (λ and κ) using an MCS-FORM hybrid approach. The results show that: (1) Both the deformation parameters have a positive relationship with the settlement, and κ has a more significant effect than λ. (2) The observed maximum settlement and the location with maximum settlement follow a log-normal distribution. (3) An increasing COV of parameters leads to an enhanced surface settlement, expansion of the significant influence region, and decreased reliability. (4) The reliability index is greatly enhanced with the delimited controlled standard value of the surface settlement, Hcon, and it decreases significantly at the preliminary stage and then decreases progressively until stable during excavating. Overall, adopting the deterministic analysis without considering the spatial variability of MCC parameters leads to underestimating the risk due to the settlement and the significant influence region.

Ultrasonic attenuation model of mixed particle three-phase system based on Monte Carlo method

From the perspective of calculating ultrasonic absorption and scattering properties of individual solid particle and droplet, the ultrasonic wave is treated as discrete phonons. And by tracking their motion process and event statistics, a new prediction model of ultrasonic attenuation of spherical mixed particles in gaseous medium is established with Monte Carlo method. Considering the difference in physical properties between solid particles and liquid particles, the ultrasonic absorption characteristics of the two kinds of particles are obviously different, and when dimensionless particle size &lt;i&gt;kR&lt;/i&gt; ≤ 1, the backscattering of particles is uniform and dominant, then the ultrasonic scattering pressures gradually transit from the dominant position of backscattering to the trend of forward enhancement with the increase of dimensionless particle size. The numerical simulation results for the system with a single particle type are compared with those from various standard models such as classical ECAH model and McC model, showing that they are in good agreement. Similarly, the results are then compared with experimental results, which accord with each other in general. After calculating and verifying the ultrasonic attenuation of aluminum particles and submicron droplets respectively in air, the method is extended to the three-phase monodisperse and polydisperse mixed particle system composed of aluminum particles and liquid droplets. In the three-phase system of gas-liquid-solid mixed particles, the particle type has a significant influence on ultrasonic attenuation, and the attenuation contribution of different particles against mixing ratio does not follow the linear gradient with the increase of volume concentration. For a polydisperse system, the ultrasonic attenuation spectrum is greatly affected by the average particle size, but it is insensitive to the width of particle size distribution. The numerical results also show that both the particle type and particle distribution size should be carefully take into account in the polydisperse system. Moreover, the MCM model can be further extended to non-spherical particles and combined with mathematical inversion to form the theoretical basis for the measurement of mixed particle system.

The Relationship between Family Relational Patterns with Sexual Function and Sexual Satisfaction in Married Women

The goal of this study was to investigate the relationship between family relational patterns with sexual function (SF) and sexual satisfaction (SS) in married women. The sampling method was multi-stage cluster sampling. Dta collection was done by the Communication Patterns Questionnaire—Short Form (CPQ-SF), Larson Sexual Satisfaction Questionnaire, and Sexual Satisfaction Scale for Women. The results showed a significant positive relationship between the mutual constructive communication patterns (MCC) with the SF. Also, there was a negative and inverse relationship between mutual avoidance communication (MAC) pattern and SF (except for the pain component) and also between the demand-withdrawal communication (DWC) pattern and SF in the stimulation and SS components. Also, there was a negative and inverse relationship between the communication models, except for the MCC model, with women’s SS. In analyzing the multivariate regression analysis (MRA), it was observed that the MCC had the most predictable role of women’s SF.

A semi‐analytical solution for displacement‐controlled elliptical cavity expansion in undrained MCC soil

AbstractConventional cavity expansion theory is a one‐dimensional problem and is not applicable for the two‐dimensional cavity expansion issue, which is also required for geotechnical problems. This paper proposes a novel semi‐analytical solution for displacement‐controlled elliptical cavity expansion (DC‐ECE) in undrained soil. The displacement and strain fields for DC‐ECE are obtained from the strain path method (SPM) with the aid of conformal mapping theory. The effective stress can be subsequently obtained by the incremental stress‐strain calculation using a suitable constitutive model such as the MCC model. Then, the computed effective stress results are substituted into the stress equilibrium equation to give the pore pressure solution. The new semi‐analytical solution reveals the non‐axisymmetric characteristics of DC‐ECE and allows the elastic‐plastic (EP) boundary, excess pore pressure, stress, and displacement to be calculated. The proposed method provides a solution to non‐axisymmetric cavity expansion issues and it can be applied to geotechnical engineering problems, including vertical drain installation, flat dilatometer tests and noncylindrical pile penetration in clay.

Reduction of Students’ Biological Misconceptions through the Conceptual Change Model Integrated with Android-Based Quran

This research aimed to reduce students’ misconceptions using a conceptual change model assisted by the integrated Android-based Quran. The study used a quasi-experimental design with a one-group pretest-posttest design. The study involved 95 eleventh-grade students MAN 1 Bandar Lampung. The research instrument was multiple-choice questions equipped with a certainty of response index (CRI) developed based on the revised Bloom taxonomy indicator. The data collection techniques used were tests (pretest and posttest). The results of the study obtained a reduction value of misconceptions in the pretest, namely understanding the concept of 47 % (moderate), misconception 48 % (moderate), and not understanding the concept of 5 % (low). The posttest score decreased (reduced) the proportion of misconceptions to 42 % (moderate), not understanding the concept to 4 % (low), and understanding the concept to 55 % (moderate). The hypothesis testing employed was the one-sample t-test. Therefore, H1 was accepted. It means that the conceptual change model (MCC) with Android-based Quran media can reduce students’ misconceptions with a criterion of 0.71 (medium interval). Thus, the results of this research can add to the treasury of studies on the reduction of misconceptions through the MCC model based on the Android-based Quran media. Also, as a practical use for teachers to deepen the concept of biology to guide students to understand the concept of the material better correctly.

Minimizing User Costs in Multi-Broker Mobile Cloud Computing Networks

The success and disruption of cloud computing over the past few years is unparalleled.In order to quickly allocate or reallocate virtual computing as well as storage resources, Infrastructure as a Service (IaaS) providers offer commercially accessible services that enable scaling out or in computing capabilities in response to changing needs.Users can provide new apps using IaaS services without having to manage the supporting infrastructure. In this study, the system takes into account an MCC model in which several brokers allot cloud resources to mobile consumers. The approach is distinguished by a heterogeneous cloud architecture and by the many cloud service providers' pricing models. Both a public cloud and a cloudlet are part of it. A competitive strategy and a compete-then-cooperate approach are investigated by the system as a performance bound. The computer creates a cooperative issue with the restriction that none broker should be required to shell out beyond the dispute price, with the objective of lowering the overall average broker price. The system uses a mix of the branch and bound paradigm with sophisticated convex relaxation techniques to develop a novel globally optimum solution algorithm to handle the ensuing non-convex cooperative issue.

Small Strain Soil Constitutive Models HS-SMALL & RU+MCC – Calibration and Verification

The paper presents two reasonably advanced constitutive laws for soil. First one is a hybrid of the Modified Cam Clay and a new RU (reload, unload) development, and it is author’s conception. The second one is a HS-small model by Benz. In the RU+MCC model, the Modified Cam Clay model, which is an isotropic elastoplastic hardening, describes normal consolidation behaviour - plastic model originated by Burland in 1967 within the critical state soil mechanics. This model describes realistically mechanical soil behaviour in normal consolidation states. The RU part is designed to ensure more adequate soil responses to reloading paths, particularly in the range of small strains. The HS-small model is an improvement of HS model originated form Schanz and Vermeer. This concept base on cap yield surface with incorporation of two hardening mechanisms, stiffness variation at small strains, densification mechanism, Rowe’s dilatancy and some others. The author in the FEM computer code Z_SOIL.pc has implemented the RU + MCC model. The HS-small model has been implemented into the same software by Truty. To test the influence of the small strain nonlinearity on soil - structure interaction as well as to exhibit the ability of the proposed model to simulate realistically this effect, a comparative study based on the FEM solution has been carried out. As a benchmark, a trial loading test of strip footing was used. The calibration process has based on advanced laboratory and field soil tests like resonant columns, triaxial test, dilatometer test and many others.

Relation between the ion flux and plasma density in an rf CCP discharge

Ion flux and plasma density are some of the most essential parameters for plasma-assisted process control. There is also a simple and well-known relation between them based on the Bohm criterion. This relation allows the avoidance of directly measuring both the ion flux and the plasma density simultaneously, but the question is, how accurate this estimation would be. This work represents the study of the sensitivity of the relation to plasma conditions, such as gas pressure, type of gas and plasma density. The experiments are carried out in an asymmetric rf dual-frequency CCP discharge in noble gases—Ar and Xe—and in molecular gas—N2. The gas pressure is varied from 20 mTorr up to 200 mTorr and the plasma density range is 109 to 5.6 × 1010 cm−3. Analysis of the experimental data is made by using the 2D PIC MCC model of the ion current collection by a planar electrode. The results show that there is some sensitivity of the relation to the type of gas and pressure, but the dependence of the relation on plasma density turns out to be slight. Therefore, the pressure parameterization of the relation for a certain gas can be used to establish plasma density by measuring ion current to an electrode and vice versa.

Modeling of Laboratory Tests on Saint-Roch-de-l’Achigan Clay with S-CLAY1S Model

This technical note presents some results of numerical simulations performed to evaluate the influence of anisotropy and destructuration on the stress-strain response of Saint-Roch-de-l'Achigan clay. The oedometer and triaxial tests were simulated with the finite-element method using two different constitutive models to represent the soil: the S-CLAY1S model, which accounted for anisotropy and destructuration, and the isotropic modified Cam clay model (MCC), which was used for comparison. In contrast to the MCC model, the S-CLAY1S model was able to simulate the compression curve for the whole range of stresses with one parameter set and, hence, represented soil behavior in the triaxial test in a more realistic way than the MCC. The results of this study confirm that when using recommended procedures for the determination and calibration of the input parameters, the S-CLAY1S model represents well the overall behavior of Saint-Roch-de-l'Achigan clay in the specific cases analyzed.

Comparison of model predictions of the anisotropic plasticity of Lower Cromer Till

This paper compares predictions, made using selected soil constitutive models, of the anisotropic plastic response of a sandy silty-clay, viz., Lower Cromer Till (LCT). The performance of four elastoplastic models, designated as MCC (Roscoe and Burland, 1968), S-CLAY1 (Wheeler et al., 2003), SANICLAY14 (Dafalias and Taiebat, 2014) and YANG2015 (Yang et al., 2015), are systematically evaluated based on a series of drained triaxial stress path tests, including virgin constant-stress-ratio (CSR) compression tests, probing stress path tests on initially K0 consolidated samples, and also various transitional CSR tests. Comparison of the various predictions shows that the isotropic MCC model cannot properly describe the mechanical behaviour of LCT due to its neglect of fabric anisotropy. The other three anisotropic models differ in their definition of the rotational hardening laws, particularly in the description of the equilibrium state of fabric anisotropy achieved under CSR loading. While significant improvements in model predictions can be observed from the three anisotropic models, for LCT S-CLAY1 generally tends to underestimate the volumetric deformation and both S-CLAY1 and SANICLAY14 are likely to overestimate the ratio of the deviatoric and volumetric strains for more anisotropic stress states. YANG2015 exhibits the most consistent performance in reproducing the mechanical behaviour of LCT among the four models under comparison. The importance of the virgin CSR tests to properly understanding the plastic anisotropy of soil fabric is highlighted.

A hybrid model for simulation of secondary electron emission in plasma immersion ion implantation under different pulse rise time

A hybrid fluid Particle in Cell–Monte Carlo Collision (PiC–MCC) model is presented to study the effect of secondary electron emission on the plasma immersion ion implantation process under different pulse rise time. The model describes the temporal evolution of various parameters of plasma such as ion density, ion velocity, secondary electron density, and secondary electron current for different rise times. A 3D–3 V PiC–MCC model is developed to simulate the secondary electrons which are emitted from the sample surface while the plasma ions and electrons are treated using a 1D fluid model. The simulation results indicate that the secondary electron density and secondary electron current increase as the rise time decreases. The main differences between the results for different rise times are found during the initial phase of the pulse. The results are explained through studying the fundamental parameters of plasma.

Role of positive ions on the surface production of negative ions in a fusion plasma reactor type negative ion source—Insights from a three dimensional particle-in-cell Monte Carlo collisions model

Results from a 3D self-consistent Particle-In-Cell Monte Carlo Collisions (PIC MCC) model of a high power fusion-type negative ion source are presented for the first time. The model is used to calculate the plasma characteristics of the ITER prototype BATMAN ion source developed in Garching. Special emphasis is put on the production of negative ions on the plasma grid surface. The question of the relative roles of the impact of neutral hydrogen atoms and positive ions on the cesiated grid surface has attracted much attention recently and the 3D PIC MCC model is used to address this question. The results show that the production of negative ions by positive ion impact on the plasma grid is small with respect to the production by atomic hydrogen or deuterium bombardment (less than 10%).

MCC 모델에 의한 연약지반의 교대측방이동 영향범위에 관한 연구

This study, using the MCC Model to consider consolidation, estimated the range within which no influences occur from lateral movement and its amount of the foundation pile and abutment on the soft ground. This study performed finite element analyses, with variations on the adhesiveness and internal friction angle, depth of soft clay, embankment height, consolidation parameters, and separation distance between the abutment and embankment. The abutment`s horizontal displacement exhibits linear change with a longer separation distance, and changes into an exponential form as the embankment gets closer to the abutment. As the soft clay layer becomes 10 m deeper, the horizontal displacement tends to increase 1.5~3.0 times. However, it decreases at a rate of 0.3~0.95 when adhesiveness is increased by 10 and internal friction angle is increased by . The increase change rate in a lateral movement amount becomes greater if it is closer to the abutment when the abutment separation distance is long. When the distance is short, the change rate of horizontal displacement increases in similar a way, but it tends to be decreasing overall.

Un nuevo modelo fenomenológico y diferencial para predecir la respuesta mecánica de materiales metálicos policristalinos sometidos a deformación en caliente

This paper presents a new phenomenological and differential model (that use differential equations) to predict the flow stress of a metallic polycrystalline material under hot working. The model, called MCC, depends on six parameters and uses two internal variables to consider the strain hardening, dynamic recovery and dynamic recrystallization processes that occur under hot working. The experimental validation of the MCC model has been carried out by means of stress-strain curves from torsion tests at high temperature (900 oC a 1200 oC) and moderate high strain rate (0.005 s -1 to 5 s -1 ) in a high nitrogen steel. The results reveal the very good agreement between experimental and predicted stresses. Furthermore, the Garofalo a-parameter and the strain to reach 50 % of recrystallized volume fraction have been employed as a control check being a first step to the physical interpretation of variables and parameters of the MCC model.

Design of shallow footings on heavily overconsolidated clays

This paper presents an integrated bearing capacity–settlement approach to the design of shallow foundations on heavily overconsolidated clays by alterations of the “modified Cam clay” (MCC) model. The bearing capacity of soils and their settlements from loads imposed on shallow footings have been studied extensively. Yet, there is no consensus on a method that provides both reliable load-bearing capacity and settlement predictions. Current methods treat the soil under shallow footings as different ideal materials for the purpose of calculating the bearing capacity and settlement. The method proposed in this paper treats the soil as a single ideal material for both bearing capacity and settlement. The MCC model is tailored by adding Hvorslev’s findings on overconsolidated clays and delineating stress states that bring the soil to tensile failure from those that cause it to yield or behave elastically or to show discontinuous response. A limiting stress surface is established as defining a limiting bearing capacity. A heavily overconsolidated clay is assumed to behave elastically if its stress state is below the limiting stress surface. Predictions from the method proposed in this paper compare favorably with model tests and field test results. Examples are provided illustrating how to use the proposed method.