Origin of strong nonlinear dependence of fracture (joint) spacing on bed thickness in layered rocks: mechanical analysis and modeling

2021 ◽  
Author(s):  
A. I. Chemenda ◽  
J. Lamarche ◽  
C. Matonti ◽  
L. Bazalgette ◽  
P. Richard
Keyword(s):  
Mechanical Analysis ◽  
Nonlinear Dependence ◽  
Joint Spacing ◽  
Bed Thickness

Relationship between joint spacing and bed thickness in sedimentary rocks: effects of interbed slip

1998 ◽  
Vol 135 (5) ◽  
pp. 637-655 ◽  
Author(s):  
SHAOCHENG JI ◽  
ZHEMING ZHU ◽  
ZICHAO WANG
Keyword(s):  
Shear Strength ◽  
Fracture Strength ◽  
Sedimentary Rocks ◽  
Tensile Fracture ◽  
Formation Mechanisms ◽  
Joint Spacing ◽  
Tensile Fracture Strength ◽  
Mechanical Models ◽  
Bed Thickness ◽  
The Relationship

This paper consists of three parts. The first part presents a critical review of previous mechanical models on the relationship between joint spacing (s) and bed thickness (t) in sedimentary rocks. The second part describes a new mechanical model dealing with the effects of interbed slip on joint spacing. The third part presents the comparison between theoretical results of the model and joint data measured from Cambrian flysch sediments at Plage Victor in the Saint-Jean-Port-Joli area of the Quebec Appalachians. This study demonstrates two formation mechanisms of tensile joints: near-end fracturing takes place in the layers with smaller tensile fracture strength (C0<30 MPa) and smaller interbed shear strength (τ0<20 MPa) while mid-point fracturing occurs in those layers with larger C0 (>50 MPa) and τ0(>30 MPa) values. For the rocks with moderate tensile fracture strength (30<C0<50 MPa) and interbed shear strength (20<τ0<30 MPa), the near-end fracturing and mid-point fracturing take place preferentially in the thicker and thinner brittle layers, respectively. In the regime of near-end fracturing, the correlation between s and t is linear and independent of the thickness of the bounding non-jointing layers (d). In the regime of mid-point fracturing, however, the s–t relationship can be either linear or non-linear, depending on the variation of d value. The present study also suggests that the near-end fracturing is probably the prevailing process for the formation of tensile joints in bedded sedimentary rocks and that the coefficient of joint spacing (K) defined by the ratio of s to t is considered as an indicator of C0/(2τ0) for the jointed layer.

scholarly journals A Vertical Joint Spacing Calculation Method for UDEC Modeling of Large-Scale Strata and Its Influence on Mining-Induced Surface Subsidence

2021 ◽  
Vol 13 (23) ◽  
pp. 13313
Author(s):  
Yaqiang Gong ◽  
Guangli Guo ◽  
Guojian Zhang ◽  
Kaikai Guo ◽  
Qiu Du ◽  
...  
Keyword(s):  
Calculation Method ◽  
Large Scale ◽  
Surface Subsidence ◽  
Mining Subsidence ◽  
Joint Spacing ◽  
The Sustainable Development ◽  
Fundamental Knowledge ◽  
Bed Thickness ◽  
Modeling Strategy ◽  
Vertical Joint

While universal discrete element code (UDEC) is widely used for understanding the mechanism of large-scale strata movement and the effects of mining subsidence on the environment, the fundamental knowledge of how to set vertical joint spacing (VJS) in UDEC is still not fully understood. To address the knowledge gap, we first present a novel VJS calculation method, then conduct UDEC experiments, and finally compare the predictions of UDEC models with field subsidence observation. The results suggest the following: (1) when compared to the conventional VJS setting (1× to 3× bed thickness), the maximum surface subsidence (MSS) prediction via UDEC models based on our proposed VJS setting method is closer to field observation; (2) a smaller but varying VJS setting can also have the effect of a larger VJS setting; and (3) with the increase in VJS, MSS first drops, then rises, and reaches the minimum when VJS is set at approximately 7× bed thickness. This paper provides an explanation of the VJS setting in UDEC and establishes a bridge between the KS theory and VJS, which is helpful for the sustainable development of such an UDEC modeling strategy and for a better understanding of the influences of mining subsidence on the environment in mining-affected areas.

Fracture spacing and its relation to bed thickness

1989 ◽  
Vol 126 (4) ◽  
pp. 355-362 ◽  
Author(s):  
Qin Huang ◽  
J. Angelier
Keyword(s):  
Maximum Likelihood ◽  
Exponential Distribution ◽  
Maximum Likelihood Method ◽  
Likelihood Method ◽  
Gulf Of Suez ◽  
Joint Spacing ◽  
Fracture Spacing ◽  
Negative Exponential Distribution ◽  
Bed Thickness ◽  
Negative Exponential

AbstractUsing examples from the Gulf of Suez and southeastern France, the distribution of tension tectonic joints as well as shear tectonic joints in continuous profiles is shown to fit a Gamma distribution. The parameters of this distribution are determined using the maximum likelihood method. Apparent fit with negative exponential distribution in photointerpretation analysis results from lack of resolution. The average joint spacing is directly proportional to bed thickness; it decreases when the degree of rock consolidation increases.

Light-cured dental composites characterization by Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 428-429
Author(s):  
B. M. Culbertson ◽  
M. L. Devinev ◽  
E. C. Kao
Keyword(s):  
Electron Microscopy ◽  
Mechanical Analysis ◽  
Service Performance ◽  
Dental Composite ◽  
Dental Composites ◽  
Neat Resin ◽  
Scanning Calorimetry ◽  
Research Meeting ◽  
Formulation Variables

The service performance of current dental composite materials, such as anterior and posterior restoratives and/or veneer cements, needs to be improved. As part of a comprehensive effort to find ways to improve such materials, we have launched a broad spectrum study of the physicochemical and mechanical properties of photopolymerizable or visible light cured (VLC) dental composites. The commercially available VLC materials being studied are shown in Table 1. A generic or neat resin VLC system is also being characterized by SEM and TEM, to more fully understand formulation variables and their effects on properties.At a recent dental research meeting, we reported on the differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) characterization of the materials in Table 1. It was shown by DSC and DMA that the materials are substantially undercured by commonly used VLC techniques. Post curing in an oral cavity or a dry environment at 37 to 50°C for 7 or more hours substantially enhances the cure of the materials.

Study of the process of forming a hole for a thread at manufacturing a high nut

2020 ◽  
Vol 76 (8) ◽  
pp. 841-846
Author(s):  
I. G. Shubin ◽  
A. A. Kurkin
Keyword(s):  
Metal Flow ◽  
Nonlinear Dependence ◽  
Geometrical Parameters ◽  
Relative Height ◽  
Forming Process ◽  
Normal Height ◽  
Accuracy Class ◽  
Limit Values ◽  
Program Complex ◽  
Class B

During manufacturing nuts of increased height, a problem of obtaining correct cylindrical form of the hole for thread and overall geometrical parameters arises. To solve the problem it is necessary to know regularity of the blank forming process. Results of the study of a technological process of high hexahedral nuts forming presented. The nuts were M18 of 22 mm height, M16 of 19 mm height and M12 of normal height 10 mm according to GOST 5915–70, accuracy class B, steel grade 10 according to GOST 10702–78. The volumetric stamping was accomplished at the five-position automatic presses of АА1822 type. It was determined, that unevenness of the metal flow in the process of plastic deformation of blanks of increased height nuts was caused by different stress conditions by their sections. To simulate the mode of deformation, the program complex QForm-3D was chosen. The complex ensured to forecast with necessary accuracy the metal flow in a blank, as well as to define the deformation force and arising stress in the working instrument. The simulation showed the presence of regularity between preliminary formed buffle and deviation of dimensions and form of a blank wall after its finishing piercing, which can be expressed by a nonlinear dependence. The limit values of the relative height of the buffle С/D = 0.56–0.588 defined, exceeding which will result in rejection of the finished product. Accounting the limit values of the relative height of the buffle will enable to correct a mode of technological operations and technological instruments at stamping of high hexahedral nuts.

Rubber–Road Contact: Comparison of Physics-Based Theory and Indoor Experiments

2016 ◽  
Vol 44 (3) ◽  
pp. 150-173 ◽  
Author(s):  
Mehran Motamedi ◽  
Saied Taheri ◽  
Corina Sandu
Keyword(s):  
Rough Surface ◽  
Practical Importance ◽  
Surface Profile ◽  
Surface Characteristics ◽  
Mechanical Analysis ◽  
Friction Model ◽  
Rubber Friction ◽  
Optical Profilometer ◽  
Viscoelastic Modulus ◽  
Longitudinal Slip

ABSTRACT For tire designers, rubber friction is a topic of pronounced practical importance. Thus, development of a rubber–road contact model is of great interest. In this research, to predict the effectiveness of the tread compound in a tire as it interacts with the pavement, the physics-based multiscale rubber-friction theories developed by B. Persson and M. Klüppel were studied. The strengths of each method were identified and incorporated into a consolidated model that is more comprehensive and proficient than any single, existing, physics-based approach. In the present work, the friction coefficient was estimated for a summer tire tread compound sliding on sandpaper. The inputs to the model were the fractal properties of the rough surface and the dynamic viscoelastic modulus of rubber. The sandpaper-surface profile was measured accurately using an optical profilometer. Two-dimensional parameterization was performed using one-dimensional profile measurements. The tire tread compound was characterized via dynamic mechanical analysis. To validate the friction model, a laboratory-based, rubber-friction test that could measure the friction between a rubber sample and any arbitrary rough surface was designed and built. The apparatus consisted of a turntable, which can have the surface characteristics of choice, and a rubber wheel in contact with the turntable. The wheel speed, as well as the turntable speed, could be controlled precisely to generate the arbitrary values of longitudinal slip at which the dynamic coefficient of friction was measured. The correlation between the simulation and the experimental results was investigated.

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