Fracture Zones In Rocks Research Articles

Microbial Mineralization-Based Rapid and High-Strength Simultaneous Repair of Surrounding Rock Fracture Zones and Lining Cracks

Grouting technology based on microbial mineralization represents a novel approach to enhancing the properties of rock and soil. Widely studied for its combination of high efficiency and environmental friendliness, this method improves the strength and permeability of rock and soil. In this study, a novel approach involving bioslurry + filling particles was proposed to reinforce sand columns. It was observed that the addition of filling particles provided new nucleation sites for crystallization, significantly enhancing the cementation effect of sand particles. After 3 days of grouting treatment, sand columns containing 10% filling particles exhibited an order of magnitude reduction in permeability with the unconfined compressive strength (UCS) reaching 2.5 MPa, more than twice that of sand columns reinforced with bioslurry alone. Additionally, this study presented a method for the simultaneous repair of sand particles and concrete cracks. Results indicated that after 3 days of the grouting treatment, the interfacial shear strength between sand columns and concrete reached 100 kPa. Moreover, for concrete with crack apertures less than 1 mm, the permeability coefficient was reduced by over 80%, while the recovery ratio of the splitting tensile strength reached 64.2%. These findings highlight the potential of microbial mineralized grouting technology in addressing practical challenges, providing a foundation for the rapid and high-strength simultaneous repair of tunnel-surrounding rock fracture zones and lining cracks.

Research on energy-absorption active control method for large deformation of tunnel surrounding rock through multi-fault fracture zone

To study the problems of large deformation of surrounding rock and water-rich dense fracture zones during tunnel construction through fault fracture zone, the NPR (Negative Poisson’s Ratio) anchor cable control method is studied based on the Tabaiyi Tunnel. First, the mechanical deformation mechanism of surrounding rock is analyzed by geological conditions, lithology and strength of surrounding rock, and different surrounding rock zones are obtained. Then, based on the self-developed high-prestressed NPR anchor cable, the tunnel prevention and control measures are designed. The high-stress NPR anchor net technology is used to support the common large deformation and fault fracture zone, while in the water-rich dense fracture zones, the combined support of double gradient grouting technology and high-stress NPR anchor net technology is adopted. Finally, to evaluate the control effect of the support design scheme, the deformation of surrounding rock, the axial force of NPR anchor cable, and the pressure of steel arch are monitored in real time. The results show that the high-stress NPR anchor net technology can effectively control the large deformation of tunnel surrounding rock caused by fault zone. In addition, in the water-rich zones, the double gradient grouting technology can provide sufficient anchoring force for the NPR anchor cable. The two technologies control the maximum deformation of surrounding rock within 300 mm and realize the stability of tunnel primary support.

Stress field analysis: Construction of site descriptive model of underground research site in KAERI

This study aims to integrate geological investigation data and construct a rock mechanical site descriptive model relative to site selection research for deep geological disposal of spent nuclear fuel. As preliminary research for the model construction process, a sub-divided numerical domain was introduced by adopting existing fracture zone in the site region of an underground research facility in KAERI. The spatial properties of the domain were decided based on the rock classification information of core specimens obtained from several boreholes. Stress field estimation modeling was performed using the constructed domain and the results were compared with the in-situ state of the field test. When the depth-dependent stress ratio was assigned to the model condition, it was confirmed that an appropriate stress state was ensured with the similarity of the in-situ stress along the depths. Additionally, uncertainties of the input properties in the stress estimation model were also assessed. The effect of uncertainties could be considered through a sensitivity analysis of rock mass and fracture zone properties to identify stress dependence on mechanical properties. Significant stress distribution was not indicated with a variation in the rock mass properties. However, weak fracture zone modeling induced a slightly disturbed stress in a shallow depth range. These results indicated that the uncertainty of the rock mechanical site descriptive model could be increased due to the fracture zone properties. This study is a case of prior research in Korea on the site evaluation model that is already applied in leading foreign countries related to site selection research for nuclear fuel disposal. The applicability based on the achievement of this study can be improved through consideration of derived equivalent properties of fractured rock. And more reliable results can be succeeded by assigning properly defined boundary conditions for the simulation of various geological scenarios.

Numerical study on the effect of in-situ stress on smoothwall blasting in deep tunnelling

In the present study, a numerical model is first calibrated against the crack networks and pressure attenuation data in laboratory blasting test. Then, based on the calibrated numerical model, two-hole plane models are developed and used to perform a series of simulations of smoothwall blasting in deep tunnelling subjected to in-situ stress. The evolutions of rock fracture and excavation damage zone in the roof/floor and sidewalls under different far-field hydrostatic pressure and anisotropic in-situ stress conditions are numerically investigated. The findings in numerical modelling are also analytically interpreted with the stress distributions around the designed tunnel perimeter and perimeter borehole. The numerical and analytical results show that the variations of rock cracking and excavation damaged zone induced by smoothwall blasting with in-situ stress are mainly attributed to the high tangential compressive stress concentration around the remaining rock after inner primary blasts and the tensile stress acting on the wall of perimeter hole, which control the crack propagation and initiation respectively. At last, the implications of findings for practical smoothwall blasting in deep tunnelling are discussed.

EXPERIENCE IN GEOSTRUCTURAL AND GEODYNAMIC INVESTIGATIONS OF NUCLEAR POWER PLANT ALLOCATION TERRITORIES FOR ASSESSING STABILITY OF ENGINEERING STRUCTURES

The results of geological and structural-geodynamic research are presented for the territories of several nuclear power plants (NPP) located on the East European Platform. The influence of geological structure, lithology, and the latest tectonic movements are considered as well as the resultant structures and relief, which generally represent the geological environment, on the stability of the NPP areas. Structural and geodynamic conditions, in particular, recent tensile stresses that cause intense rock fracturing and high gas-fluid permeability, suffusion, karst and landslide, are proved to be the main causes of hazardous processes resulting in settling and tilting of some NPP buildings. Tectonic sloping of the sites towards descending depressions, the sand basement of NPP sites, sloping clay aquicludes, fluctuating water levels in the adjacent water reservoirs, the presence of so-called “hydrogeological windows”, the buried relief and modern structural and geodynamic conditions, i.e., tectonic stresses (tensile stresses in many cases) contribute to building deformations. Along with solving practical problems, a number of theoretical issues are considered. Lineaments are associated with rock fracture zones and faults zones; the fault zones in crystalline foundation influence the formation of recent structures; and new platform structures, i.e. gravity-tectonic massifs and pull-apart depressions, are distinguished.

Lineament Analysis by Using Remote Sensing and GIS Technique of Sangaw Area, Kurdistan Region, NE Iraq

Recently, structural lineaments have typically been increasingly emphasized in morphotectonic research because they are thought to be an excellent guide for determining tectonic settings and fracture zones in rocks. ERDAS Software was used to extract and analyze the lineaments within the Sangaw ‎area, which is located in the northeastern part of Iraq. This study employed a Digital Elevation Model from the Shuttle Radar Topography Mission with a resolution of 30 meters. Directional filtering was used to extract the lineaments in four distinct directions (N-S, E-W, NE-SW, NW-SE). The overall trend’s direction of the lineaments is determined to be NW-SE, indicating that the area was succeeding the main tendency of Zagros folds. According to the density map of the lineaments, the low and medium-density lineaments occupy the main portion of the study area. The direction of the maximum tectonic stress and the rotation of the Arabian Plate counterclockwise led to the formation of joints in multiple directions, which were clarified by the system of lineaments’ relationships in harmony with the directions of the tectonic stresses and their contrast and effects. The field study showed high density and distinct activity in the study area of erosion and weathering processes as well as tectonic.

Fluid evolution and ore genesis of Cu–Pb–Zn veins in the Panjiaduan deposit, Great Xing’an Range, NE China: evidence from fluid inclusion and H–O–He–Ar isotopes

AbstractThe southern Great Xing’an Range (SGXR), located in the eastern segment of the Central Asian Orogenic Belt (CAOB), is one of the most economically important Cu–Mo–Fe–Sn–Pb–Zn–Ag metallogenic provinces in China. The newly discovered Panjiaduan Cu–Pb–Zn deposit (9.3 Mt; at 1.36% Cu, 2.90% Pb, 3.80% Zn and 38.12 g/t Ag), located in the SE segment of the SGXR, is primarily hosted in fracture zones in volcanic rocks and granodiorite of the Manitu Formation. Four paragenetic stages of metallic mineralization are identified: (I) quartz-pyrite-arsenopyrite; (II) quartz-polymetallic sulphide; (III) quartz-galena-sphalerite-argentite; and (IV) quartz-calcite-minor sulphide. The hydrothermal quartz contains three types of primary fluid inclusion (FIs): vapour-rich two-phase liquid-vapour (LV-type), liquid-rich two-phase liquid-vapour (VL-type) and three-phase liquid-vapour-solid FIs (SL-type). Stages I and II contain all types with homogenization temperatures (Th) of 324–386 °C and 276–334 °C as well as salinities of 0.7–38.0 wt% and 0.9–34.7 wt%, respectively, whereas stage III is composed of VL- and LV-type FIs with Th of 210–269 °C and salinities of 0.5–7.2 wt%. Only VL-type FIs occur in stage IV, with Th of 139–185 °C and salinities of 1.6–4.2 wt%. The δ18OH2O and δD values vary from −15.7 to 2.6‰ and −132.7 to −110.2‰, respectively, indicating predominant meteoric water with an initial magmatic source. The He–Ar isotopic compositions of the pyrite inclusions from the Panjiaduan Cu–Pb–Zn veins suggest that fluids were derived from the crust.

FRACTURING AND PERMEABILITY OF CRYSTAL ROCKS AND THEIR FRACTURE ZONES, HYDROGEOLOGICAL ASPECT

Fractured rock aquifers are regarded as of particular scientific and practical interest because of their importance for underground water supply, energy storage and safety radioactive waste disposal. The study of fissure waters of crystalline rocks in the context of global warming to address issues of drinking water supply is highly relevant today. It has potential practical importance for the future.The sustainable use of groundwater in fractured rock aquifers requires a detailed knowledge of their hydraulic properties. The complexity of hydrogeological conditions in massive fractured rocks results from uncertainties about the configuration of the fractures, while the potential for groundwater movement in such rocks is primarily determined by their permeability and, consequently, hydraulic conductivity. Fractures (fracture networks) have different permeability properties, which is one of the key parameters required for understanding and predicting fluid and water flow. This paper reviews and analyses the results of global studies of fracturing and permeability of crystalline rock massifs and the fault zones occurring in them. Since the study of permeability of crystalline rocks concerns many disciplines — including structural geology, tectonophysics, petrophysics, hydrogeology, and hydrology — this review highlights information about the distribution of groundwater in fractured crystalline rocks in the context of their potential exploitation. This study consists of two parts: generalization of research results concerning fracturing and permeability of crystalline rocks, and particularities of structure of fracture zones in crystalline rocks and of the presence of groundwater in them. Based on this review of the structure and development of fracture zones (including their evolution under the influence of weathering and other secondary processes), recommendations are given for using tectonophysical reconstructions to improve hydrogeological field works and mathematical modeling.

Determination Method of Excavation Damage Zone Based on Surrounding Rock Damage-Fracture Ratio in Underground Engineering

The depth of the excavation damage zone in the surrounding rock mass is an important parameter to determine the support design scheme, and is also of great reference significance to evaluate the stability of the surrounding rock. An acoustic test is the most commonly used method to obtain the depth of the excavation damage zone in surrounding rock. However, under high stress conditions, the surrounding rock is seriously broken and the internal structural planes are significantly developed, leading to the test error reaching meter-level. This paper, based on dimensional analysis, proposed the surrounding rock damage-fracture ratio R, which was defined as the depth of excavation damage zone to the depth of highly damaged zone, to characterize the relationship between the excavation damage zone and highly damaged zone. The established indicator considered the stress condition of the engineering zone, rock integrity, tunnel excavation span, and rock fracture zone depth and was verified with allowable error in engineering practice. The results show that the model can overcome the limitations of the acoustic wave testing method in surrounding rock testing of deep underground caverns, and the method of determining the depth of the surrounding rock damage zone based on the damage-fracture ratio R provides a practical and alternative method for determining the damage zone of surrounding rock excavation.

Research on Influence Factors of Bearing Capacity of Concrete-Filled Steel Tubular Arch for Traffic Tunnel

When a traffic tunnel passes through special strata such as soft rock with high geo-stress, expansive rock, and fault fracture zones, the traditional supporting structure is often destroyed due to complicated loads, which threatens the construction and operation safety of tunnel engineering. Concrete-filled steel tubular (CFST) structure gives full play to the respective advantages of steel and concrete and has better bearing capacity and economic benefits than traditional support structure, which has achieved good results in some underground engineering applications. In order to promote the application of CFST in the construction of traffic tunnels with complex geological conditions and improve the bearing capacity of the initial supporting structure of tunnels, the influencing factors of the bearing capacity of CFST arch were studied by numerical simulation. The main achievements are as follows: (1) The load-displacement curves of CFST members under different material parameters are basically consistent. CFST members have significant restrictions on displacement in the elastic stage and have high ultimate bearing capacity. Although the bearing capacity decreases obviously after reaching the peak, it shows good extension performance. (2) The height of the steel tube section, the thickness of the steel tube wall and the grade of the core concrete have an approximately linear positive correlation with the bearing capacity of CFST arch, but the influence of these three factors on the bearing capacity of CFST arch decreases in turn, and when the grade of core concrete increases above C50, it has no significant effect on the bearing capacity of members.

Assessment of Fractures in Excavation Damaged Zone around Roadways of an Iron Mine Using Optical Televiewer Detecting Method

The properties of the excavation damaged zone (EDZ) are critical to the stability of the surrounding rock masses of the chamber, roadway, and dam, and fractures in the EDZ also affect the properties of the EDZ. In this paper, the fractures in the EDZ of an underground iron mine roadway were tested using borehole television (BTV). The results revealed that the better the grade of rock mass is, the less broken it was after excavation. An assessment method based on BTV image data has been proposed for evaluating the roadway’s surrounding rock. This method uses the borehole image data to classify the excavated surrounding rock into intact rock mass, joint zone, fracture zone, and broken zone based on the condition of rock and the distribution of fractures within the rock mass. A relatively complete joint zone caused by the construction of the drill and blast method was found by using this method, and the support measures should ensure that this joint zone is not damaged. The method provides a better basis for improving the support design, according to which the improved support measures have achieved a better support effect and economic benefits.

Analysis of Crystalline Rock Permeability Versus Depth in a Canadian Precambrian Rock Setting

AbstractOver the last 50 years, there has been an increased interest in characterizing Precambrian crystalline rock, such as the Canadian Shield, to investigate the feasibility of deep geologic repositories for isolating used nuclear fuel from the biosphere. Extensive work has been conducted in Canada with a large amount of that work undertaken by Atomic Energy of Canada Limited. Few peer‐reviewed journal articles were published based on these data, so a large amount of the data, specifically on fracture zones, are unavailable for modelers and analysts. By collecting and analyzing over one‐hundred technical reports, journal articles, and conference proceedings, written between 1975 and 1996, it was possible to characterize plutonic Precambrian crystalline rock and separate the data into (1) equivalent porous media (EPM) for rock mass and (2) fracture zones (FZs). A third category, aggregate media (AM), was used herein to represent the entire data set (EPM + FZs). Using the data from these studies, a novel logistic function was fit to represent the mean permeability, with respect to depth, of crystalline rock for EPMs and FZs in plutons. Understanding rock permeability is critical for the long‐term isolation of used nuclear fuel so that accurate predictions of fluid flow and mass transport can be evaluated in the area of the proposed storage location.

DENSITY ANALYSIS OF LINEAMENTS USING REMOTE SENSING DATA

Lineament analysis is an important structural and geological indicator for determining general and local tectonic trends and fracture zones in rocks, especially in mining zones. In this study we used optical and radar satellite data to analyze the density map of lineaments structure data for territory of Kashkadarya region - one of the main gas producing regions in Uzbekistan. The results show that according to Landsat 8 high density of lineaments is located near geology faults. During a detailed exploration, the density map according to SRTM data found that at an azimuth of 1800, 2250, 2700, and 3150 the density is much higher than at an azimuth of 00, 450, 900, and 1350. KEYWORDS: lineaments, optical and radar data, density map, hillshade, rose-diagram

Research on strip pressure relief drainage technology in deep coal roadway

Aiming at the characteristics of coal and gas outburst disasters in Jianxin Coal Mine, based on the compound energy mechanism of coal roadway outburst in deep mining and the distribution law of the roadway surrounding rock fracture zone, the pre-drilling pressure relief floor rock roadway and the cross-bed borehole drainage coal road way g as a r e p r o pos ed. Regi o n al anti-outburst measures have been applied in engineering. The application shows that this technical measure can greatly improve the permeability of the coal seam and the effect of pressure relief extraction, and ensure the safe and rapid excavation of coal roadways.

Study on Sealing Technology of Gas Drainage Borehole under Damage of Surrounding Rock in Deep Mine Roadway

In order to solve the problems of poor drainage effect and low efficiency caused by poor sealing quality of deep gas drainage boreholes, based on the gas geological conditions in Huainan mining area, comprehensive theoretical analysis and field engineering practice, the distribution law of surrounding rock fracture zone in different lithologic roadways was studied, and the sealing technology combining pressure grouting, screen pipe protection and deep and shallow hole grouting was put forward. Field tests showed that the technology was effective. The average gas extraction concentration and hundred hole extraction purity of boreholes are 3.75 times and 3 times higher than those of common boreholes respectively, and the field application effect is remarkable.

Analysis and Monitoring of Small‐Scale Rock Fracture Zone Deformation and Shaft Failure in a Metal Mine

Rock fracture zones were distributed in a metal mine, and their deformation was always neglected because they are available on a small scale. However, the deformation of the small‐scale fracture zone may lead to serious consequences, such as underground building and structure failure. Combined with the ground movement and surface fissure monitoring, the deformation of several fracture zones was analyzed by field monitoring, experimental test, and numerical simulation. The results showed that fracture deformation promoted the surface fissure movement. The horizontal movement of the foot wall rock of the fracture was found to be larger than the hanging wall rock. Deep mining engineering resulted in the squeezing of the shallow fracture, and the shallow fracture deformed more severely than the deep fracture. In the study area, fracture zone displacements were estimated according to a numerical model. The deformation and stress comparison of the shallow fracture zone and the deep fracture zone provided the characteristic of the broken structure in the field investigation.

A user-driven feedback approach for 2D direct current resistivity inversion based on particle swarm optimization

We have developed an inversion approach based on particle swarm optimization (PSO) for 2D direct current resistivity data. Once the PSO algorithm is implemented, cost-function changes on constraints and misfit criteria can be easily performed and an approximate invariance of the Lagrange multipliers is obtained if each term of the cost function is properly normalized. More importantly, the interpreter can divide the mesh into partitions and apply a different constraint or combination of constraints in each partition. We explore several restrictions on the log-resistivity variation, either in single or in joint versions, including spatial continuity constraints in the [Formula: see text]-and [Formula: see text]-norms, total variation, sparsity constraints using the discrete cosine transform and Daubechies bases, and minimum moment of inertia constraints to impose concentration of resistive or conductive materials along target axes. In the latter case, the earth surface might be used also as a target axis. In addition, the final state of the PSO algorithm, once a stopping condition has been reached, contains not only the best solution but also a cluster of good suboptimal solutions that can be used for uncertainty analysis. As a result, the interpreter has the flexibility to perform an interpretation process based on a feedback trial-and-error inversion approach, in a similar manner that he/she has when using a friendly forward modeling software. The interpreter can then drive the tentative solutions obtained along the inversion process to incorporate their conceptions about the geologic environment, besides appraising misfit and stability of the solutions. We evaluate synthetic and field data examples. In the first case, we determine how the interpreter can drive the inversion process in a karst environment to image dissolution features. In the second case, we explore a similar situation aiming to optimize borehole locations in fracture zones in crystalline rocks.

Structural Analyses aiding Identification of Water Conductive Fracture Zones in Crystalline Rock

Development of hydraulic conductive zones in crystalline rock can result from a wide range of geological conditions which include primary structures, post crystalline tectonics, fluid solution and movement within a developing and eroding regolith.Crystalline rock areas mostly have low water resource potential due to inherent extremely low storage and water conductive properties. Therefore, fracture zones of high hydraulic conductivity have an important role in developing groundwater resources that may be distant or where it may be difficult to obtain alternative sources in these areas.Mechanisms for development of open tension or pull-apart fractures in brittle rocks are similar to those involving development of mineralised veins. The same structural analytical techniques can be applied for water bearing structures.Crystalline rock fracture zones can be amenable to rapid recharge through rainfall runoff. They are also significant in that they provide a mechanism for underdrainage through ‘delayed yield’ of surrounding or enclosing low conductive rocks such as saprock/saprolite, pelite and phyllite.In addition to brittle rocks, open tension fracture zones of enhanced hydraulic conductivity may also occur in more fissile pelitic rocks such as slate and phyllite. These conductive zones are often associated with crestal zones of folds, strike deviations produced by conjugate shears and fracture zones discordant with layering and foliation. The development of conjugate joint sets in a region frequently provide a significant basis for this type of fracture analyses.This presentation provides examples of water supplies developed from crystalline rock structures in a range of geological and earth environments.

Structural Analyses aiding Identification of Water Conductive Fracture Zones in Crystalline Rock

Development of hydraulic conductive zones in crystalline rock can result from a wide range of geological conditions which include primary structures, post crystalline tectonics, fluid solution and movement within a developing and eroding regolith.Crystalline rock areas mostly have low water resource potential due to inherent extremely low storage and water conductive properties. Therefore, fracture zones of high hydraulic conductivity have an important role in developing groundwater resources that may be distant or where it may be difficult to obtain alternative sources in these areas.Mechanisms for development of open tension or pull-apart fractures in brittle rocks are similar to those involving development of mineralised veins. The same structural analytical techniques can be applied for water bearing structures.Crystalline rock fracture zones can be amenable to rapid recharge through rainfall runoff. They are also significant in that they provide a mechanism for underdrainage through ‘delayed yield’ of surrounding or enclosing low conductive rocks such as saprock/saprolite, pelite and phyllite.In addition to brittle rocks, open tension fracture zones of enhanced hydraulic conductivity may also occur in more fissile pelitic rocks such as slate and phyllite. These conductive zones are often associated with crestal zones of folds, strike deviations produced by conjugate shears and fracture zones discordant with layering and foliation. The development of conjugate joint sets in a region frequently provide a significant basis for this type of fracture analyses.This presentation provides examples of water supplies developed from crystalline rock structures in a range of geological and earth environments.

The capability of detailed study of coal- and orebearing structures using electrical resistivity tomography (ERT) by means of “well boresurface” observation system

Coal open-cuts of Khabarovsk and Primorskii krai are characterized by multiple coal beds of small thickness. Important is the task to evaluate structural architecture of landslide blocks distinguishing insecure beds of small thickness. In detailed study of ore deposits it is also needed to distinguish thin beds and rock-fracture zones. Therefore, in order for detailed study of such structures, it is proposed to develop a ERT technology with the use of “well bore-surface” observation system. On this stage, only theoretical justification of proposed technology is given. In order to ascertain the technology capability, the calculation of apparent resistivities for three-layer structures with various correlations of geometrical and electrical parameters was conducted. Calculations were performed with uniform spacing of 20 electrodes in a well bore and 40 of them on the surface with polling of Wenner and Schlumberger fourelectrode arrays, axial array and their three-electrode designs. Regularities of electrical field for three fragments of apparent resistivity section were established based upon the analysis of modeling results: electrodes only on the surface (horizontal profile), electrodes in the well bore (vertical profile), electrodes in the well bore and on the surface (mixed profile). Outstanding interest is represented by anomalous areas of mixed profile which are described by new regularities of the field and criteria of distinguishing beds of small thickness. Theoretically it has been demonstrated that new technology is effective with distinguishing beds of small thickness on different depths of geological section.