Integrity Of Rock Mass Research Articles

Analysis of Coral Reef Rock Mass Integrity Based on RMDI Method

At present, relatively few drilling surveys have been conducted on coral reefs, and comprehensive geological info on coral reefs is difficult to obtain. However, research of coral reef is of great importance to our development and exploitation of maritime resources. The survey of Chenhang Island in Paracel (Xisha) Islands saw China’s first usage of digital borehole camera technology, which resulted in a large amount of first-hand geological data. We have utilized the rock mass integrity index (RMDI) method in our analysis of coral reef integrity, and with reference to the rock mass classification standard, formulated the correlation between RMDI values and coral reef intactness, enabling the engineering evaluation of coral reef integrity. Through statistical analysis of camera data gathered along the CK2 borehole’s approx. 1km length, we performed an integrity evaluation of the entire borehole length using the RMDI classification, and created a coral reef stratum development diagram which is consistent with the actual cores. The results indicate: (1) the classification system based on RMDI is feasible in the integrity evaluation of coral reefs; (2) the coral reef integrity values obtained using the RMDI method are accurate; (3) borehole camera survey and statistical analysis are of great utility in the study of coral reefs.

Acoustic Detection on Analysis of Rock Mass Integrality

This paper briefly described borehole wave velocity test and the principle and method of wave velocity test technique, by using acoustic measurement and control technology of tunnel rock mass test, integrality index of rock mass is obtained, ultimately, we evaluate the rock mass integrity. The actual application effect is good and provides an important basis for the engineering rock mass quality evaluation.

Test of Anchored Shear about Fractured Rock and Numerical Simulation Analysis of the Slope Rock Mass

The mechanics mechanism of bolt reinforcement of joint fissure test pieces were discussed with the method of variable angle plate indoor model experiment and the deformation of bolt control of jointed slope were analyzed by numerical simulation. The results show that: the bolt reinforcement can improve not only the integrity of joint fissure rock mass, but also be a very good control of deformation of jointed slope. It establishes the foundation on the quantitative for evaluation of joint fissure rock mass deformation and stability.

The Discussion of Issues Related to the Rock Mass Structure Classification of Dam Foundation

Because various lithologic rock present very obvious differences in many aspects (such as: the apparent lumpiness, longitudinal wave velocity, mechanical property etc), the results of the rock mass structure classification by using current specification or general methods can not reflect the true engineering geological properties. Based on a large number of onsite structural surface investigations, acoustic measurements and field and laboratory tests, this paper discusses the related issues on division of rock mass structure using single lumpiness indicators and analyzes the impact of the structural body property and structural surface effect on the rock mass structure. At the same time, the related issue on the integrality coefficient is discussed in the evaluation of rock mass integrity degree. Finally, the proposal which rock structure classification should consider the structure bodys strength and stiffness, the structure surfaces extension length and closed degree, the structure body block size and the rock mass compression wave velocity is put forward.

Numerical Simulation Analysis on Anchored Shear Test of the Fractured Rock and the Slope Rock Mass

Discussing the mechanics mechanism of bolt reinforcement of joint fissure test pieces with the method of Variable angle plate indoor model experiment, analyzing the deformation of bolt control of jointed slope combined with the numerical simulation. The results show that: the bolt reinforcement can improve not only the integrity of joint fissure rock mass, but also be a very good control of deformation of jointed slope. It established the foundation on the quantitative for evaluation of joint fissure rock mass deformation and stability.

A Expansive Limits Anti-Permeability Strength Methodology of the Coal Mine Floor Water Inrush Evaluating

Abstract In order to solve the difficult problems on coal mine floor water inrush evaluation, on the basis of the servo-controlled permeability test of rock in the complete stress-strain process, the concept of expansive limits anti-permeability strength was presented. Then established coal floor water inrush model, the model includes the floor aquifuge effective thickness, lithology, rock mass integrity and expansive limits anti-permeability strength and detailed describes how to get valus the factors. Finally, took No. 17 coal seam of Yangcun coal mine in Yanzhou as an applicational example, it proves that the expansive limits anti-permeability strength method is feasible on the floor water inrush evalution.

Collapse Analysis of Jointed Rock Slope Based on UDEC Software and Practical Seismic Load

Once rock slope under the earthquake effect is instability, it will cause huge economic damage and casualties. Therefore, it is necessary to study the mechanism of the collapse analysis of jointed rock slope based on UDEC Software and practical seismic load .As an example that Lan-Cheng-Yu product oil pipeline in K0526+300 jointed rock slope, this geological model of the slope is established on the geological and structure feature of the slope. It is easy to establish the numerical model of rock slope considering the structure characteristics with the UDEC software. The practical 5.12 earthquake loads and the related constraints are inputted to carry through the slope dynamic analysis. It verifies that is feasible to use the UDEC software in the collapse analysis of the crack development of rock slope, through the comparison and analysis between the simulation results and slope body actual damage. results presented in the paper indicates that the effects of earthquake makes the interface between rocks decrease, then damage the integrity of rock mass, ultimately lead to rock slope collapse. It is important significance to prevent and mitigate disaster in areas where earthquakes are common for this study.

PHYSICAL AND MECHANICAL PARAMETERS OF BOREHOLE HYDRAULIC MINING OF NONG’AN OIL SHALE

The experiments on physics and mechanics of borehole hydraulic mining were designed to determine mechanical characteristics of mined oil shale. Oil shale of Nong'an deposit belongs to slightly weathered and relatively complete rocks. Oil shale beds are characterized by a very definite discontinuity in both horizontal bedding orientation and vertical bedding direction. Compressive strength, tensile strength, Poisson's ratio and other data characterizing oil shale beds in different directions in the Nong'an min- ing site were obtained and compared. The direction of borehole hydraulic mining was determined. The vertical bedding direction to break oil shale was considered to be better, because strength in this direction is low, rock mass integrity poor, and the degree of weathering more pronounced. The diameter of borer nozzle, dynamic pressure, maximum caving capacity and other parameters needed for borehole hydraulic mining were selected.

A new seismic well logging technique and its application

A new seismic well logging technique has been developed for identifying the damaged zone around the rock masses that was affected by the stability of rock structures due to excavation of underground. In this study, we firstly purpose to introduce a new seismic well logging technique, then to show the results of the examples applied on rock structures of open-pit limestone mine and an underground power station. Finally, we intend to verify its efficiency. A new seismic well logging technique consisted of trigger sensor, super-elastic probe and signal conditioner was found applicable to evaluate the state of rock mass. From the measured result of rock slope in an open-pit limestone mine due to blasting, we defined that it was able to quantitatively evaluate the extent of damages of rock structures as well as to determine the location of damaged zone. In addition, this technique can measure P- and S-velocities simultaneously. P-velocity measurement from an access tunnel closed underground power station was also successfully carried out for observing the state of rock mass. It is expected that the newly developed seismic well logging technique would be a useful method for evaluating the integrity of rock mass and for ensuring an efficient tunnel support members.

Delineating rockmass damage zones in blasting from in-field seismic velocity and peak particle velocity measurement

Damage to the surrounding rock during blasting either in underground or surface excavation, is a growing concern today. It has been found that the integrity of rockmass is reduced significantly from pre to post blast condition due to disregard paid to the surrounding rockmass. For exercising suitable engineering controls accurate measurement of the same is a prerequisite. To delineate the blast-induced rock damage zone seismic imaging technique can be used. Seismic imaging is a non-destructive method to determine the field seismic velocity of the rockmass for its characterisation. Further, it is considered that the blastinduced ground vibration is the root cause of rock damage due to structural dilation and should be controlled to localize its effect. Different researchers have related ground vibration to damage to arrive at the thresholds levels of damage. However, the accuracy in measurement/estimation of extent of damage is always a concern. This paper presents a case in which the seismic imaging technique was successfully used to delineate the extent of rock damage extent. The damage zone was also correlated with the vibration model developed to establish the same for its direct use in damage assessment.

Surrounding Rock Mass Quality Evaluation of Huangdao Water Sealed Underground Oil Tank

Huangdao water sealed underground oil tank, which lies in Qingdao, Shandong province, is one of strategic reservoir of oil in China. Targeting at a real pragmatic problem that sometimes the rock mass integrity index is more than 1 and taking Huangdao water sealed underground oil tank as an example, the rock sample wave velocity-stress relation tests are carried out. Then unloading index is put forward and formula of raock integrity index is modified so as to improve rock quality classification method. In the end, the improved rock quality classification method is applied to Huangdao water sealed underground oil tank engineering. The result shows that the quality of most rock masses here is level I or II.

Dynamic Numerical Simulation for the Problem of Tunnel Rock Mass Large Deformation of a Hydropower Project in the Upper Reaches of Lancang River

It is a very effective technology methods that using dynamic numerical simulation of discrete element method to study the large deformation problems of underground engineering rock mass which in the complex rock mass mechanics environmental conditions.Research achievements show that the development of deformation failure of the tunnel surrounding rock and the final convergence stability are mainly controlled by rock mass structure and its stress environment in the special toppling deformation rock mass. Deformation of the rock mass that in the lateral unloading and relaxation and also has a complex rock mass structure developed sustainably and progressivity over time,will eventually seriously damaged in roof fall. The surrounding rock deformation of the tunnel ,which have a good rock mass integrity and do not have the obvious unloading and relaxation stress environment, gradually tended to be stable after the initial deceleration-type development.

Integrity assessment of rock mass behind the shotcreted slope using thermography

This paper presents the results of a field study of using thermography to identify the existence of eroded caves behind shotcrete-protected slopes. The temperature variation calculated from the highest and lowest temperatures measured at each point on the shotcrete surface is utilized to evaluate the integrity of the rock mass behind the concrete. In addition, ground penetration radar (GPR) is performed at three selected locations near the toe of the slope of concern; while the necked eye observation and knocking tests are conducted at two of the selected areas. The soils taken out from the rock mass and the abnormal echo, as well as strong GPR reflection patterns, confirm the existence of eroded caves behind the shotcrete surface. The agreement of the locations that show both strong GPR reflection and large temperature variation verifies the applicability of thermography in evaluating the integrity of rock mass behind the shotcrete surface.

Generalized crack initiation and crack damage stress thresholds of brittle rock masses near underground excavations

The rock mass failure process is characterized by several distinct deformation stages which include crack initiation, crack propagation and coalescence. It is important to know the stress levels associated with these deformation stages for engineering design and practice. Extensive theoretical, experimental and numerical studies on the failure process of intact rocks exist. It is generally understood that crack initiation starts at 0.3 to 0.5 times the peak uniaxial compressive stress. In confined conditions, the constant-deviatoric stress criterion was found to describe the crack initiation stress level. Here, generalized crack initiation and crack damage thresholds of rock masses are proposed. The crack initiation threshold is defined by σ1−σ3=A σcm and the crack damage threshold is defined by σ1−σ3=B σcm for jointed rock masses, where A and B are material constants and σcm is the uniaxial compressive strength of the rock masses. For a massive rock mass without joints, σcm is equal to σcd, the long-term uniaxial strength of intact rock. After examining data from intact rocks and jointed rock masses, it was found that for massive to moderately jointed rock masses, the material constants A and B are in the range of 0.4 to 0.5, 0.8 to 0.9, respectively, and for moderately to highly jointed rock masses, A and B are in the range of 0.5 to 0.6, 0.9 to 1.0, respectively. The generalized crack initiation and crack damage thresholds, when combined with simple linear elastic stress analysis, assist in assessing the rock mass integrity in low confinement conditions, greatly reducing the effort needed to obtain the required material constants for engineering design of underground excavations.

A correlation between P-wave velocity, number of joints and Schmidt hammer rebound number

Engineering design of the major infrastructures mainly relies on determination of rock mechanical parameters. However, such indexes are traditionally acquired from the borehole tests of the construction site. The drilling test is generally time-consuming and costly procedure. Further, such tests provide geology information only at some specific points, need more equipment, are hardly carried out in the high topographic sites, and often leave ambiguity in the subsurface interpretation. Alternatively, geophysical research of ERT (electrical resistivity tomography) is swift, user-friendly, inexpensive and non-destructive, and can provide a bridge between the limited drilling tests and a true geotechnical model of the subsurface. In the present research, we introduce a novel geophysical approach to estimate rock mass integrity index (Kv) via integration between the ERT-based electrical resistivity and the limited borehole-based Kv. The obtained Kv offers 2D and 3D evaluation of rock mass integrity along all ERT profiles for large coverage of the project site where even no borehole data exist. Furthermore, uncertainty in the evaluation of water-clay distinction was removed by the integration of IP (induced polarization) with ERT. Our research, compared to the conventional geotechnical investigations, removes uncertainties in the geotechnical model and offers more accuracy in rock mass quality classification for various types of rock units. This approach removes the extensive drilling tests and offers a comprehensive assessment of rock mass integrity to achieve the proper design of engineered infrastructures in the highly heterogeneous terrains.

Dilution in underground bulk mining: implications for production management

Abstract The minimization of dilution represents a major opportunity for quality improvement in Canadian underground metal mining. The characteristics of the principal forms of dilution, planned and unplanned, are reviewed. These are controlled by quality factors relating to exploration, mine design and stoping practice. The scope for quality improvement and the need for technology development is analysed in the context of underground bulk mining. The design principles for a production management system which tightly monitors and controls dilution are proposed. This revolves around the reconciliation of accurate and timely data on ore reserves, stope fragmentation, cavity morphology, rockmass integrity, and production statistics. Particular priority will require to be placed on continued sensor development for measurement of cavity geometry, borehole deviation, grade and tonnage. This is intended to exploit a rapidly evolving underground communications technology and forms part of a rationale for future computer integrated mining.