Constitutive models of frozen soil

2000 ◽  
Vol 37 (4) ◽  
pp. 811-816 ◽  
Author(s):  
Ping He ◽  
Yuanlin Zhu ◽  
Guodong Cheng
Keyword(s):  
Failure Process ◽  
Constitutive Models ◽  
Confining Pressure ◽  
Frozen Soil ◽  
Damage Development ◽  
Soil Particles ◽  
Whole Process ◽  
Pressure Melting ◽  
Stress States ◽  
Relationship Of

The constitutive models on viscoelastoplasticity and the damage to frozen soil presented in this paper can be used to analyze the relationship of stress and strain, under complicated stress states, and damage development and the failure process of the internal structure of frozen soil. The models successfully predict the whole process of creep, including the failure stage. Both strengthening and weakening effects of confining pressure, namely increasing the friction force between soil particles and decreasing the frozen force between ice and the soil particles due to pressure melting of ice, are considered in the constitutive models.Key words: viscoelastoplasticity, damage development, constitutive model, frozen soil.

scholarly journals Researches on the Constitutive Models of Artificial Frozen Silt in Underground Engineering

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Yugui Yang ◽  
Feng Gao ◽  
Hongmei Cheng ◽  
Yuanming Lai ◽  
Xiangxiang Zhang
Keyword(s):  
Mechanical Characteristic ◽  
Stress Level ◽  
Strain Softening ◽  
Triaxial Compression ◽  
High Stress ◽  
Constitutive Models ◽  
Confining Pressure ◽  
Frozen Soil ◽  
Conventional Triaxial Compression ◽  
Shear Process

The researches on the mechanical characteristic and constitutive models of frozen soil have important meanings in structural design of deep frozen soil wall. In the present study, the triaxial compression and creep tests have been carried out, and the mechanical characteristic of frozen silt is obtained. The experiment results show that the deformation characteristic of frozen silt is related to confining pressure under conventional triaxial compression condition. The frozen silt presents strain softening in shear process; with increase of confining pressure, the strain softening characteristic gradually decreases. The creep curves of frozen silt present the decaying and the stable creep stages under low stress level; however, under high stress level, once the strain increases to a critical value, the creep strain velocity gradually increases and the specimen quickly happens to destroy. To reproduce the deformation behavior, the disturbed state elastoplastic and new creep constitutive models of frozen silt are developed. The comparisons between experimental results and calculated results from constitutive models show that the proposed constitutive models could describe the conventional triaxial compression and creep deformation behaviors of frozen silt.

scholarly journals Energy Absorption Characteristics of Frozen Soil Based on SHPB Test

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Qin-yong Ma ◽  
Dong-dong Ma ◽  
Pu Yuan ◽  
Zhao-ming Yao
Keyword(s):  
Energy Absorption ◽  
Impact Loading ◽  
Soil Type ◽  
Incident Energy ◽  
Confining Pressure ◽  
Freezing Temperature ◽  
Frozen Soil ◽  
Absorbed Energy ◽  
Stress States ◽  
Absorption Characteristics

Dynamic compressive tests are performed in three frozen soil types under different stress states at freezing temperatures of −5°C and −15°C with impact loading pressures from 0.3 MPa to 0.6 MPa. The effects of frozen soil type, freezing temperature, impact loading pressures, and stress states on incident energy and energy absorption characteristics, such as absorbed energy and energy absorbency rate, are investigated. The experimental results show that most of the incident energy is reflected back to the incident bar, and incident energy linearly increases with the increase of impact loading pressures. Both absorbed energy and energy absorbency rate are found to be negatively correlated with freezing temperature, and there values under confining pressure state are larger than that under uniaxial condition. The effects of confining pressure on absorbed energy are quite different at different freezing temperatures. In addition, frozen soil type also affects absorbed energy and energy absorbency rate. Meanwhile, impact loading pressure shows an increased effect on the absorbed energy, but it has little effect on energy absorbency rate in the research.

scholarly journals The Establishment of Segmented Constitutive Relationship of Coal under Triaxial Compression: Take the No. 3 Coal of Xinhe Colliery as an Example

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yongjie Yang ◽  
Yang Zhang ◽  
Tianli Zhang
Keyword(s):  
Mechanical Test ◽  
Triaxial Compression ◽  
Failure Process ◽  
Confining Pressure ◽  
Test System ◽  
Constitutive Relationship ◽  
Peak Strain ◽  
Deformation Stage ◽  
Triaxial Compressive Strength ◽  
Relationship Of

Constitutive relationship of coal under triaxial compression must be determined during solving the theoretical calculation and numerical simulation about coal body failure. This paper carried out the conventional triaxial compression test on No. 3 coal of Xinhe Colliery using the MTS815.03 servo-controlled rock mechanical test system. The results indicate that the failure process of coal can be divided into 5 stages: densification stage, apparent linear elastic deformation stage, accelerated inelastic deformation stage, fracture and developing stage, and plasticity flow stage. Within the test confining pressure (20 MPa), the peak strain of coal is approximately linearly positively correlated with the confining pressure. The relationship between elastic modulus of coal and confining pressure is quadratic polynomial. The triaxial compressive strength and residual strength of coal are approximately linearly positively correlated with confining pressure. The constitutive relationship model of coal can be simplified as the four segments of straight line model of “elastic–plastic hardening–plastic softening–residual perfectly plastic.” Through fitting calculation of test data, the segmented constitutive equation of coal can be obtained, and the every segment span of strain.

scholarly journals Seepage Damage Statistical Model of Filled Fractured Rock considering Structural Surface and Failure Characteristic

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xinyu Liu ◽  
Yuan Tian ◽  
Zhende Zhu
Keyword(s):  
Elastic Modulus ◽  
Weibull Distribution ◽  
Statistical Model ◽  
Fractured Rock ◽  
Failure Process ◽  
Strain Curve ◽  
Confining Pressure ◽  
Tensile Failure ◽  
Whole Process ◽  
Structural Surface

Damage theory studies the whole process of initiation, propagation, and instability of microcracks in materials and provides an important basis for the estimation of the risk of materials. Therefore, it is assumed that the rock microunit strength is the damage variable of the medium and obeys the Weibull distribution. According to the tensile failure characteristics of filled fractured rock under the action of seepage stress, the maximum tensile strain criterion is used to define the rock microunit strength parameters, and the equivalent elastic modulus of the fractured rock is used to establish a new damage statistical model. This paper mainly studies the rationality and feasibility of using this new constitutive model to describe the seepage failure process and damage characteristics of filled fractured rock. The results indicate that (1) the accuracy of the equivalent elastic modulus is affected by the confining pressure and the characteristics of the structural surface. In the elastic phase, using the equivalent elastic modulus, E V R H has better fit. In the plastic phase, it is better to use the E V parameter. (2) The established Weibull distribution statistical model can better calculate the stress-strain curve of fractured rocks with weak and soluble fillings. (3) The rock strength characteristics affected by different stress conditions and different filling fracture states calculated by the model are the same as the experimental data. (4) The model using equivalent elastic modulus parameters reflects the threshold characteristics of rock failure and the damage evolution process. After comparison, it is found that the model can accurately calculate the final damage value of the fractured rock with weak and soluble filling. However, the final damage value used to calculate the fractured rock of the hydraulic material filling is much higher and inaccurate.

Determination of a Rubber-Like Material Model as an Inverse Problem

2011 ◽  
Vol 70 ◽  
pp. 225-230 ◽  
Author(s):  
Agnieszka Derewonko ◽  
Andrzej Kiczko
Keyword(s):  
Selection Process ◽  
Axial Stress ◽  
Constitutive Models ◽  
Material Model ◽  
Polyester Fabric ◽  
Point Of View ◽  
Air Cushion ◽  
Ill Conditioning ◽  
Stress States

The purpose of this paper is to describe the selection process of a rubber-like material model useful for simulation behaviour of an inflatable air cushion under multi-axial stress states. The air cushion is a part of a single segment of a pontoon bridge. The air cushion is constructed of a polyester fabric reinforced membrane such as Hypalon®. From a numerical point of view such a composite type poses a challenge since numerical ill-conditioning can occur due to stiffness differences between rubber and fabric. Due to the analysis of the large deformation dynamic response of the structure, the LS-Dyna code is used. Since LS-Dyna contains more than two-hundred constitutive models the inverse method is used to determine parameters characterizing the material on the base of results of the experimental test.

Study on the Dynamic Performance of Asphalt Concrete under Passive Confined Pressure

2012 ◽  
Vol 226-228 ◽  
pp. 1755-1759
Author(s):  
Hua Zhang ◽  
Fei Li ◽  
Yu Wei Gao
Keyword(s):  
Elastic Modulus ◽  
Asphalt Concrete ◽  
Poisson Ratio ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Dynamic Strength ◽  
Confining Pressure ◽  
Mechanical Behaviors ◽  
One Dimensional ◽  
Stress States

An improved passive confining pressure SHPB method was used to study the dynamic mechanical behaviors of asphalt concrete under quasi-one dimensional strain state. The effect of confining jacket material and its geometrical sizes on the confining pressure were discussed. The dynamic strength, dynamic modulus of elasticity and dynamic Poisson ratio of asphalt concrete were obtained. The influential rules of confining pressure on the dynamic properties were studied by comparing the stress-strain curves of asphalt concrete under different stress states. The study found that passive confining greater impact on the strength of asphalt concrete than elastic modulus and Poisson ratio, but the elastic modulus improved with the increase of confining pressure.

Experimental investigation of the effect of compliant pores on reservoir rocks under hydrostatic and triaxial compression stress states

2019 ◽  
Vol 56 (7) ◽  
pp. 983-991
Author(s):  
Hua Yu ◽  
Kam Ng ◽  
Dario Grana ◽  
John Kaszuba ◽  
Vladimir Alvarado ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Triaxial Compression ◽  
Matrix Material ◽  
Volumetric Strain ◽  
Confining Pressure ◽  
Differential Pressure ◽  
Sandstone Sample ◽  
Stress States ◽  
Rock Springs ◽  
Stage 1

The presence of compliant pores in rocks is important for understanding the stress–strain behaviors under different stress conditions. This paper describes findings on the effect of compliant pores on the mechanical behavior of a reservoir sandstone under hydrostatic and triaxial compression. Laboratory experiments were conducted at reservoir temperature on Weber Sandstone samples from the Rock Springs Uplift, Wyoming. Each experiment was conducted at three sequential stages: (stage 1) increase in the confining pressure while maintaining the pore pressure, (stage 2) increase in the pore pressure while maintaining the confining pressure, and (stage 3) application of the deviatoric load to failure. The nonlinear pore pressure – volumetric strain relationship governed by compliant pores under low confining pressure changes to a linear behavior governed by stiff pores under higher confining pressure. The estimated compressibilities of the matrix material in sandstone samples are close to the typical compressibility of quartz. Because of the change in pore structures during stage 1 and stage 2 loadings, the estimated bulk compressibilities of the sandstone sample under the lowest confining pressure decrease with increasing differential pressure. The increase in crack initiation stress is limited with increasing differential pressure because of similar total crack length governed by initial compliant porosity in sandstone samples.

Damage evolution and recrystallization enhancement of frozen loess

2017 ◽  
Vol 27 (8) ◽  
pp. 1131-1155 ◽  
Author(s):  
Zhiwei Zhou ◽  
Wei Ma ◽  
Shujuan Zhang ◽  
Cong Cai ◽  
Yanhu Mu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Damage Evolution ◽  
Deformation Process ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Recrystallization Process ◽  
Frozen Soils ◽  
Time Deformation ◽  
Pressure Melting

A series of multistage triaxial compression, creep, and stress relaxation tests were conducted on frozen loess at the temperature of −6℃ in order to study the damage evolution and recrystallization enhancement of mechanical properties during deformation process. The effect of strain rate, confining pressure, and hydrostatic stress history in the degradation laws of mechanical properties is investigated further. The strain rate has a significant influence on the stress–strain curve which dominates the evolution trend of mechanical properties. The mechanical behaviors (strength, stiffness, and viscosity) of frozen loess all exhibit evident response for the consolidation and pressure melting phenomenon caused by the confining pressure. The multistage loading tests under different hydrostatic stresses are capable of differentiating the development characteristics of mechanical properties during axial loading and hydrostatic compression process, respectively. The testing results indicated that the recrystallization of the ice particle in the frozen soils is an important microscopic factor for enhancement behaviors of mechanical parameters during the deformation process. This strengthening degree of mechanical properties is determined by temperature, duration time, deformation degree, and stress state during the recrystallization process. The phase transformation led by pressure melting and ice recrystallization is a nonnegligible changing pattern of frozen soils microstructure, which has apparent role in the damage evolution of mechanical properties.

scholarly journals Resilient modulus and cumulative plastic strain of frozen silty clay under dynamic aircraft loading

2021 ◽  
Vol 3 (10) ◽  
Author(s):  
Xiaolan Liu ◽  
Xianmin Zhang ◽  
Xiaojiang Wang
Keyword(s):  
Plastic Strain ◽  
Resilient Modulus ◽  
Confining Pressure ◽  
Frozen Soil ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Research Findings ◽  
Cumulative Plastic Strain ◽  
Construction Operation ◽  
Compaction Degree

AbstractThis paper describes an investigation into the factors influencing the resilient modulus and cumulative plastic strain of frozen silty clay. A series of dynamic triaxial tests are conducted to analyze the influence of the temperature, confining pressure, frequency, and compaction degree on the resilient modulus and cumulative plastic strain of frozen silty clay samples. The results show that when the temperature is below − 5 °C, the resilient modulus decreases linearly, whereas when the temperature is above − 5 °C, the resilient modulus decreases according to a power function. The resilient modulus increases logarithmically when the frequency is less than 2 Hz and increases linearly once the frequency exceeds 2 Hz. The resilient modulus increases as the confining pressure and compaction degree increase. The cumulative plastic strain decreases as the temperature decreases and as the confining pressure, frequency, and compaction degree increase. The research findings provide valuable information for the design, construction, operation, maintenance, safety, and management of airport engineering in frozen soil regions.

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