scholarly journals Rheological Behavior of Rockmass Supported with Rockbolts Based on Viscoelastic Analysis Method

Mathematics ◽  
2018 ◽  
Vol 6 (10) ◽  
pp. 199
Author(s):  
Gang Wang ◽  
Wei Han ◽  
Chuanzheng Liu ◽  
Ke Wang ◽  
Hengjie Luan
Keyword(s):  
Rock Mass ◽  
Analytical Solutions ◽  
Rheological Behavior ◽  
Rheological Model ◽  
Coupling Model ◽  
Rheological Parameters ◽  
Analysis Method ◽  
Viscosity Coefficients ◽  
Viscoelastic Analysis ◽  
Close Relationship

In this paper, we present the viscoelastic solutions for rockmass supported with discretely mechanically or frictionally coupled (DMFC) rockbolts to reveal the coupling rheological mechanisms. The analytical solutions are first acquired by applying the Laplace inverse transforms. The effect of different viscosity coefficients and supporting parameters on the coupling model rheological behavior are then investigated. It is concluded that the variation of the rockbolt axial force or rock mass stress and displacement have a close relationship with rheological parameters and support parameters. In addition, the variations of mechanical states of rockbolts and rock mass are closely related to the rheological model.

Back Analysis Methods in Geotechnical Engineering

2014 ◽  
Vol 1020 ◽  
pp. 423-428 ◽  
Author(s):  
Eva Hrubesova ◽  
Marek Mohyla
Keyword(s):  
Rock Mass ◽  
Geotechnical Engineering ◽  
Back Analysis ◽  
Rheological Parameters ◽  
Analysis Method ◽  
Direct Optimization ◽  
Initial Stress State ◽  
Analytical Functions ◽  
Is Evaluation

The paper deals with the back analysis method in geotechnical engineering, that goal is evaluation the more objective and reliable parameters of the rock mass on the basis of in-situ measurements. Stress, deformational, strength and rheological parameters of the rock mass are usually determined by some inaccuracies and errors arising from the complexity and variability of the rock mass. This higher or lower degree of imprecision is reflected in the reliability of the mathematical modelling results. The paper presents the utilization of direct optimization back analysis method, based on the theory of analytical functions of complex variable and Kolosov-Muschelischvili relations, to the evaluation of initial stress state inside the rock massif.

scholarly journals Experimental Study on Water-Sand Seepage Characteristics in Fractured Rock Mass under Rheological Effect

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Jiarui Chen ◽  
Hai Pu ◽  
Jianxiong Liu ◽  
Jihua Zhang ◽  
Peitao Qiu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Rheological Model ◽  
Fractured Rock ◽  
Western China ◽  
Rheological Parameters ◽  
Sand Filtration ◽  
Fractured Rock Mass ◽  
Exponential Relationship ◽  
Rock Samples ◽  
Mixed Fluid

This study investigates water-sand bursting disasters associated with fractured rock that affect safe mining in the mining areas of Western China. A broken rock water-sand seepage rheological test device was developed, and rheological tests were conducted on multiple groups of broken rock samples with single-stage axial loading and different load levels. When the rheology of each group of broken rock samples was stable, water-sand mixed fluid was injected into the samples at a certain pressure gradient to conduct water-sand seepage tests on broken rock masses. It was found that when the porosity of a fractured rock mass is within a certain range, the water-sand mixed fluid does not completely pass through the fractured rock mass and some sand particles are filtered by the fractured rock sample. There is an exponential relationship between the sand breaking ability and the sand filtration ability of fractured rock and its initial porosity, and the permeability of fractured rock decreases by a certain extent after sand filtration. However, for different load levels, when the flow through a fractured rock mass tends to be stable, the final porosity of the fractured rock mass decreases exponentially with axial compression. Based on the classical Kelvin rheological model and the basic theory of fractional calculus, a new fractional rheological model has been proposed and the rheological parameters under different load levels were fitted to the model. The new fractional rheological model is better able to describe the rheological characteristics of broken mudstone.

Study on the Constitutive Model of Visco-Elasticity-Plasticity Considering the Rheology of Rock Mass

2013 ◽  
Vol 639-640 ◽  
pp. 567-572 ◽  
Author(s):  
Li Wu ◽  
Qing Jun Zuo ◽  
Zhong Le Lu
Keyword(s):  
Rock Mass ◽  
Constitutive Model ◽  
Rheological Properties ◽  
Rheological Model ◽  
Mechanical Characteristics ◽  
Experimental Result ◽  
Rheological Parameters ◽  
Creep Stage ◽  
Plastic Model ◽  
In Series

Considering the rheological mechanical characteristics of rock mass, a viscous-plastic model of rock mass which can describe the acceleration creep stage of rock mass was proposed. Moreover, combining with viscous-elastic shearing rheological model of rock mass in series, a new constitutive model of visco-elasticity-plasticity considering the rheology was constructed. Due to the shearing rheological curves of granite, the model of visco-elasticity-plasticity considering the rheology was identified and the rheological parameters of the model were obtained. The comparison between the viscous-elastic-plastic rheological model of rock mass and experimental result of granite shows that the accelerating rheological properties of rock mass can be depicted effectively by the constitutive model of visco-elasticity-plasticity considering the rheology.

Thermal analysis method of electromagnetic linear actuator based on multiphysics coupling model

2021 ◽  
pp. 1-17
Author(s):  
Geng Wang ◽  
Renjing Gao ◽  
Qi Wang ◽  
Shutian Liu
Keyword(s):  
Thermal Analysis ◽  
Thermal Characteristics ◽  
Coupling Model ◽  
Analysis Method ◽  
Thermal Analysis Method ◽  
Performance Requirements ◽  
Wide Range ◽  
Multiphysics Coupling ◽  
Simulation And Experiment ◽  
Electromagnetic Linear Actuator

Electromagnetic linear actuators (ELAs) may be confronted with unsatisfactory performance when subjected to overheating. Therefore, it is significant to clarify its thermal characteristics and design the thermal performance requirements. A thermal analysis method based on multiphysics coupling model was presented, which uses the non-simplified loss distribution as the heat source to calculate the temperature field, adjusts the material properties by temperature, and considers the interaction between motion (including impact) and loss. More importantly, an improved universal equivalent winding to satisfy the condition of real compact concentrated winding was developed. Finally, the validity of this approach was verified through the experiment, and the regularity of temperature was summarized. The results show that the error of simulation and experiment is less than 6% and the permissible continuous operation frequency is no more than 30 Hz. The approach proposed in this paper can be employed not only to the ELA, but also to the design and analysis a wide range of electromagnetic machines.

Hole-Cleaning Fibers Improve Cuttings-Carrying Capacity

2021 ◽  
Vol 73 (05) ◽  
pp. 63-64
Author(s):  
Chris Carpenter
Keyword(s):  
Flow Regime ◽  
Carrying Capacity ◽  
Rheological Model ◽  
Drilling Fluid ◽  
Test Method ◽  
Abu Dhabi ◽  
Rheological Parameters ◽  
Cleaning Efficiency ◽  
Hole Cleaning ◽  
Drilling Operations

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 203147, “Investigating Hole-Cleaning Fibers’ Mechanism To Improve Cutting Carrying Capacity and Comparing Their Effectiveness With Common Polymeric Pills,” by Mohammad Saeed Karimi Rad, Mojtaba Kalhor Mohammadi, SPE, and Kourosh Tahmasbi Nowtarki, International Drilling Fluids, prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually 9–12 November. The paper has not been peer reviewed. Hole cleaning in deviated wells is more challenging than in vertical wells because of the boycott effect or the eccentricity of the drillpipe. Poor hole cleaning can result in problems such as borehole packoff or excessive equivalent circulating density. The complete paper investigates a specialized fibrous material (Fiber 1) for hole-cleaning characteristics. The primary goal is to identify significant mechanisms of hole-cleaning fibers and their merits compared with polymeric high-viscosity pills. Hole-Cleaning Indices Based on a review of the literature, most effective parameters regarding hole cleaning in different well types were investigated. These parameters can be classified into the following five categories: - Well design (e.g., hole angle, drillpipe eccentricity, well trajectory) - Drilling-fluid properties (e.g., gel strength, mud weight) - Formation properties (e.g., lithology, cutting specific gravity, cuttings size and shape) - Hydraulic optimizations (e.g., flow regime, nozzle size, number of nozzles) - Drilling practices (e.g., drillpipe rotation speed, wellbore tortuosity, bit type, rate of penetration, pump rate) In this research, rheological parameters and parameters of the Herschel-Bulkley rheological model are considered to be optimization inputs to increase hole-cleaning efficiency of commonly used pills in drilling operations. The complete paper offers a detailed discussion of both the importance of flow regime and the role of the Herschel-Bulkley rheological model in reaching a better prognosis of drilling-fluid behavior at low shear rates. The properties of the fibrous hole-cleaning agent used in the complete paper are provided in Table 1. Test Method Two series of tests were performed. The medium of the first series is drilling water, with the goal of evaluating the efficiency of Fiber 1 in fresh pills. The second series of tests was per-formed with a simple polymeric mud as a medium common in drilling operations. Formulations and rheological properties of both test series are provided in Tables 4 and 5 of the complete paper, respectively.

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