Slope Rock Mass Research Articles

Construction Technology of Cooperative Blasting in High-Steep Slope and Underground Tunnel in Offshore Oil Depot

Li, L.-B.; Zhang, J.-H., and Wu, L., 2019. Construction technology of cooperative blasting in high-steep slope and underground tunnel in offshore oil depot. In: Li, L.; Wan, X., and Huang, X. (eds.), Recent Developments in Practices and Research on Coastal Regions: Transportation, Environment and Economy. Journal of Coastal Research, Special Issue No. 98, pp. 1–5. Coconut Creek (Florida), ISSN 0749-0208.This paper aims to study the cooperative blasting technology in a high-steep slope and an underground tunnel. For this, an actual engineering project in an offshore oil depot is used as an example, and a comprehensive research method combining theoretical analysis, field test, and numerical simulation is adopted. In addition, based on the actual monitoring blasting vibration data, the dynamic parameters of the tunnel finite element model were determined, and then the existing blasting parameters were predicted accordingly to obtain the peak particle vibration velocity of the slope rock mass structure. The safety distance of the slope surface from the tunnel excavation face was determined by referring to the Safety Regulations for Blasting and the mechanical performance index of the rock mass to ensure that the tunnel excavation will not affect the stability of the slope rock mass. Meanwhile, according to the blasting parameters of the slope excavation, the measured blasting particle vibration parameters of the tunnel were combined with the tunnel dynamic finite element model to determine the safe distance between the slope excavation face and the surrounding rock of the tunnel, thereby ensuring the cooperative blasting in the high-steep slope and underground tunnel and achieving the purpose of shortening the construction period under conditions of stable slope surface and tunnel surrounding rock. This study provides an effective method for theoretical and technical research on the vibration effect of surrounding rock in existing tunnels.

Field monitoring on deformation of high rock slope during highway construction: A case study in Wenzhou, China

In order to study the deformation stability of rock slope during the excavation of cutting slope and ensure the safety of rock slope during construction and operation period, this article analyzed the deformation law of a typical slope excavation by monitoring the surface deformation and the internal displacement of the rock mass. The surface deformation of the slope is monitored by setting monitoring points, and the internal deformation of the slope is monitored by installing multipoint displacement meters and inclinometers. Therefore, the relationship between slope excavation and deformation is obtained. The analysis of monitoring results shows that the slope is stable before excavation, and the displacement of the slope is gradually increased with the slope excavation. After the excavation, the displacement of each slope tends to converge. The maximum displacement in surface monitoring points is 12.30 mm, and the displacement parallels to the direction of the expressway. The maximum vertical displacement in surface monitoring points is 10.60 mm which occurred in the third step; the maximum internal displacement is 11.02 mm which mainly occurs in the weak structural plane of the rock boundary. During the excavation of the weak rock slope, the slope rock mass is prone to large displacement deformation. After the excavation, the slope surface displacement and internal displacement tend to converge in a short time.

A new method for evaluating rock mass quality of slopes based on interval continuous mathematical models

Rock mass classification has been playing an important role in the analyses of civil engineering in recent years. The quality evaluation of slope rock mass becomes essential for slope stability assessment. Neither continuous expression and comparable function are rarely taken into consideration in rock mass classification, nor is the shortage in the previous quality evaluation of slop rock mass. Through constructing the benchmark intervals of evaluation indicators; mathematical models between quantized value and relative quantized value which is a new proposed parameter; and linear weighted function, the interval continuous mathematical models (ICMM) for quality evaluation of slope rock mass are presented. The application result shows that ICMM is effective for improving the comparability of rock mass quality of slopes by unifying evaluation indicators. On the other hand, the ICMM realizes the continuous expression of rock mass quality of slopes by removing the step-like features caused by the pre-set rating criteria of each evaluation indicator and rock mass quality classification, guiding the follow-up construction and protection of slopes, and ensuring the balance between economy and safety. Therefore, the ICMM is more scientific and reasonable than extant classification systems for evaluating rock mass quality of slopes.

Influence of material spatial variability on slope stability in soft rock

Impacts of material spatial variability usually are not considered in traditional slope stability analyses. However, most geotechnical materials are not uniform inside a slope. The objective of the present study was to evaluate the impact of material spatial variability on slopes in soft rocks. The random field model was used to obtain the material spatial variability. The numerical analyses of slopes in soft rock mass were performed using a distinct element method based program UDEC. After that, Monte Carlo simulation, UDEC, and random field models were used together to analyze the impact of material variability and the slope stability. A series of numerical experiments were performed to understand the effect of joint spacing, joint angle, and size of scale fluctuation (δ). Also, failure types and mechanisms were synthesized and evaluated. The probability of failure became higher as the slope considered horizontal spatial variability of the material. The influence of the horizontal size of δ on slopes without joints was much higher than the slopes with joints. In addition, the slopes with joints yielded fewer failures as δ increased. The results of the analyses could be used for prevention of slope failure, future support system, and geotechnical exploration.

Research on Elevation Effect of Blasting Vibration in Step Slopes

Vibration caused by blasting is an important factor affecting the safety of blasting production and the stability of slope rock mass. This paper conducts on-site blasting vibration measurement and concrete model blasting vibration test. It is concluded that the elevation has both amplification and attenuation effects on blasting vibration. And the attenuation effect is dominant, and the amplification effect is supplemented. In the region where the elevation amplification effect appears obvious, the magnification increases with the increase of the elevation. The law of change is first increased and then decreased.

Classification of Red-Bed Rock Mass Structures and Slope Failure Modes in South China

Red beds are Meso–Cenozoic continental sedimentary strata that are mainly composed of gravel stone, sandstone, siltstone, mudstone, and shale and occasionally have interlayers of limestone, halite, and gypsum. As a typical rock mass, red beds are widely distributed throughout South China. In a typical tropical and subtropical continental environment, red beds are the product of multiple sedimentary cycles, which have resulted in complicated rock mass structures that play an important role in rock mass stability. It is thus of great significance to investigate the influence of different rock mass structures on the stability of red-bed slopes. In this paper, the geological formation history of red beds in South China is described. The main features of red-bed rock mass slopes in South China are discussed. The main combinations of inner geomechanical structures comprise: (1) mega-thick soft rock structures; (2) mega-thick hard rock structures; (3) thick hard rock structures with weak intercalation; and (4) soft–hard interbedded structures. In addition, the features of slope failure are analyzed, and four common failure modes are identified from the statistical data: (a) weathering spalling and scouring; (b) rock falls; (c) landslides; and (d) tensile dumping.

Influence of Water Level Rise on the Bank of Reservoir on Slope Stability: A Case Study of Dagangshan Hydropower Project

This paper considers stability of slope under varying water level for the right bank of reservoir of Dagangshan hydropower project. SEEP/W and SLOPE/W are used for numerical analysis. Morgenstern-Price method is used for stability analysis. Change in Factor of Safety with the rise in water level is obtained. Three cases of water level rise are studied as fast, medium and slow. It is found out that, when water level rises, the water table also rises correspondingly hence changing the properties of the rock mass in slope and its behavior to different situations and stresses. With the change in the water table line, the property like permeability changes, which is a significant property for slope stability and affects directly the strength of rock mass. Also due to change in water table within the slope, the situation of saturated and unsaturated portions in the slope also changes which is a complex phenomenon to deal with. So it has to be considered as an important factor. The changing pattern of the factor of safety with the elevation is similar for the cases of slow and medium but it is different for fast case. There is difference in factor of safety for the same elevation for different cases so the speed of the rise in water level also influences the impact on the stability. The comparison of fast and medium cases show that the difference in factor of safety is low but while comparing the cases- slow and fast the difference is high.

Application of 3D-DDA integrated with unmanned aerial vehicle–laser scanner (UAV-LS) photogrammetry for stability analysis of a blocky rock mass slope

In stability analysis of discontinuity-controlled slopes, the rationality of results is related to the accuracy of three-dimensional (3D) slope morphology and the reliability of the discontinuity survey. With the advent of remote sensing technologies for engineering geological surveys and slope stability analyses, step-change increases have been made in the quality of data available and geometrical characterization of rock slopes. Although these techniques are frequently employed in the characterization of slope geometry and joint surfaces at present, limited research has been undertaken to effectively process the derived data and improve the quality in the reconstruction of slope geometry imported into 3D discontinuous numerical models. In this paper, an integrated system coupling 3D-DDA and UAV-LS photogrammetry is presented as a tool to evaluate the stability of a blocky rock mass slope. The system includes a UAV-LS module, a modeling module, a block-generation module, and a 3D-DDA calculation module. In the UAV-LS module, the use of UAV-LS system integrated with field mapping and site observations allows the acquisition of detailed outputs (point clouds) on both the slope and discontinuity geometry. An effective combination of commercial software Geomagic and Hyperworks is used in the modeling module to process oceans of 3D point cloud data and construct complex 3D geometrical models based on reverse engineering. In the block-generation module, the three-dimensional discontinuous deformation analysis (3D-DDA) method is then carried out in order to simulate the movement of potentially unstable blocks, within which an independent block-cutting algorithm is used to generate the blocks with arbitrary shapes and the finite structural planes similar to the real cases. The 3D-DDA calculation module uses 3D-DDA calculation algorithm to derive the simulation results. The capability of the proposed system for stability analysis of a jointed slope is demonstrated by a practical example.

Deformation process and mechanism analyses for a planar sliding in the Mayanpo massive bedding rock slope at the Xiangjiaba Hydropower Station

Planar sliding, which has a universal characteristic of existing planar discontinuities, is very common in nature. The Mayanpo slope, a massive bedding rockslide, typical planar sliding, exploiting a sedimentary formation of interbedded sandstone and argillaceous stratums mixed with four strongly weathered weak interlayers, presents creep deformation that has interrupted the construction of the Xiangjiaba Hydropower Station. Field investigations indicate that the deformation behavior of Mayanpo slope should be analyzed within two different zones, namely zone I (east side) and zone II (west side). Although both zones are primarily controlled by the bottom weak interlayer (JC-1), the deformation magnitudes and potential failure modes are different: (a) Zone I exhibits a deformation that is significantly larger in magnitude than zone II, and (b) zone I and zone II present multistage and integral creep-fracturing progressive deformation-failure mode, respectively. The mechanism of this creep deformation can be considered to be the endogenic and exogenic integration. The progressive degradation of predominant discontinuity from primary soft rock stratum to weak interlayer is the fundamental which provides the possibility of kinematic release. The numerical analysis conducted with hydromechanical finite difference method (FDM) shows that excavation without reinforcement and rainfall can (i) enable kinematic feasibility and creep deformation, (ii) trigger the ceaseless propagation of sliding zone along JC-1, and (iii) promote the formation of a tensile strain concentration zone in the trailing under tension-shear effect. Furthermore, discussions on the engineering core measures for prevention and control are presented, which have important implications for similar engineering projects.

A systematic approach for the analyses and design of jointed rock mass slopes against wedge and toppling failures: a case study of the stability of the abutments of the bridge across the Chenab River

ABSTRACT The stability of jointed rock mass slopes in highly seismic areas is governed by the orientation of the joints with respect to the slope and the joint characteristics and the seismic accelerations. The paper presents a systematic approach for the analysis and design of jointed rock mass slopes against wedge and toppling failures in highly seismic areas. There are nine load cases to be considered in the analyses of slopes. To address the concerns on the uncertainty and variability of the geological data, the process of “Design as you go” was suggested. The bridge across the Chenab river gorge with a main arch span of 467m which is under construction is located in a highly seismically active zone. The approach proposed in this paper was successfully implemented in the stabilization of the abutments of the Chenab bridge which enhanced the confidence in the adequacy of slope stabilization measures.

Study on Deformation and Failure of Toppling Deformation Slope of Miaowei Hydropower Station under Storage Condition

With the completion and operation of hydropower stations in Southwest China, the stability of reservoir slope is impacted by the change of water level during reservoir storage and operation. It has become an important engineering geological problem in the design and operation of hydropower stations. Taking the Miao River Hydropower Station in Lancing River Basin as the research object, the structural characteristics of the bank slope and the influence of reservoir impoundment are analyzed. The deformation of the slope rock mass in the reservoir area is serious. During the reservoir storage, the stability of the bank slope is outstanding. In order to analyze the influence of the change of water level on the stability and failure mode of the tilting deformable body on the bank slope under the condition of water storage, through the numerical simulation analysis, using UDEC discrete element software after impoundment, it is concluded that after water storage, the strength of rock mass is reduced, and the failure mode changes from sliding failure to collapse and failure, but the stress field of the slope has little change.

Slope Stability of Metamorphic Rocks Based on Rock Mass Classification at Poboya Gold Mine, Central of Sulawesi Province

Poboya Mountains is one of the gold mines located in Palu city. Miners conduct quarrying and slope slicing to extract gold ores every day, resulting in changes on slope stability. The research is to determine rock mass classification and slope stability of metamorphic rocks. The research conducted at Poboya Gold Mine, it geographically located at central of Sulawesi province. The classification of rock mass carried out through a field survey and a laboratory testing, and then determined according to methods of RMR and SMR. The results showed that for gneiss at location 1, it obtained values of 60-69 for RMR and SMR as well. Meanwhile, for schist at location 2, the obtained values are 56-71 for RMR and 57-79 for SMR. Schist at location 3 has values of 65-75 for RMR and 69-79 for SMR, and schist at location 4 have values of 56-70 for RMR and 59-85 for SMR. Referring to the rock mass classification results, it can be concluded that slopes location at Poboya with a good quality of rock mass is at schist of location 3. Generally, slopes considered stable, hence there will be no landslides, and if landslide occurs, it will merely occurs on small blocks.

软弱基座型高边坡危岩演化及应力场分析

危岩崩塌具有爆发突然、难以预测、危害性大等特点，准确合理推断危岩崩塌演化发展过程及趋势成为预防和治理危岩崩塌的关键性问题。以黄泥堡高边坡危岩为依托，结合现场工程地质调绘，通过分析高边坡危岩体的结构特征，得出近水平层状软弱基座型危岩体悬臂–拉裂式破坏模式；运用地质学基础理论，分析阐述高边坡危岩体崩塌的形成及演化发展过程的四个阶段；在此基础上，推导出评价危岩崩塌稳定性的表达式；采用数值模拟方法对依托工程实例进行应力场模拟分析，研究地应力场的演化特征。结果表明，岩腔底部产生应力集中现象，并且随着岩腔的发展加深而越来越明显。为高边坡危岩稳定性评价以及治理措施提供指导和借鉴。 Perilous rock and collapse is provided with characteristics of sudden outbreak, unpredictable, harmful and so on, accurately and reasonably infer the process and trend of the evolution of pe-rilous rock and collapse is the key issues for the prevention and treatment of rock collapse. In this paper, based on the high rock slope of Huang Nibao, combined with the site engineering geological mapping, the structural features of dangerous rock mass in high slope is analyzed, and the cantilever-rupture failure mode of the near horizontal layered perilous rock in soft foundation is obtained. Based on the basic theory of geology, the four stages of the formation and evolution of the perilous rock and collapse are analyzed and explained. On the basis of this, the expression of the stability for the perilous rock and collapse is derived. Based on the engineering example, the numerical simulation method is used to analyze the stress field, and study the evolution characteristics of the stress field. The results show that, the stress concentration occurs at the bottom of the rock cavity and becomes more and more obvious as the rock cavity deepens. It provides guidance and reference for the stability evaluation and treatment measures of perilous rock in high slope.

Geotechnical Behavior of Eastern Senegal Rock Mass Slopes by Geomechanical Classifications and Applications

In Senegal, rock mechanic studies began in last four years and were a very new engineering domain. So, the first stage is to characterize geological materials. It is on this way that this work is done. This paper analyzes geomechanical parameters of sandstones of Dindifélo and basalt of Bafoundou belonging to the Proterozoic rocks domain of eastern Senegal. By Rock Mass Rating (RMR) and Geological Strength Index (GSI), sandstones of the Dindifello Cliff show fair to poor characteristics while basalts of the hills of Bafoundou are fair quality. In addition to the qualities of rock mass, Young moduli, uniaxial compressive strengths and tensile strength of rock mass are also defined using Rock Quality Designation (RQD) GSI, RMR. Hoek-Brown parameters m and a, depend both on the fracturation and the content fine in the rock. Values of mechanical parameters are different when deduced from RMR, GSI and from intact rock laboratory test. Those differences are due to variables taken account. The variation depends also on the quality of the rock. Statistical analysis shows possible unstabilities which depend on rock mass parameters but with acceptable probability of failure. Probability of failure is the highest when deducing from Mohr criterion than from Hoek-Brown criterion.

Study on the Instability Mechanisms and Monitoring Control of Stratified Rock Slope with Water-Rich Strata

Water is one of the leading factors in the sliding geological disasters of rock slope, and the harm of fissure water to slope rock mass more and more becomes one of the hotspot research problems in transportation infrastructure construction in mountainous area. Based on the current research status quo of effect of fissure water on rock mass, the interaction mechanisms of water and rock in stratified rock slope were analyzed by related theories such as rock mass mechanics, fluid mechanics and soil mechanics including softening dissolution, scour hole enlargement and padding effective stress, and the influence of water–rock interaction on slope sliding disasters. Then, the influence of rainfall on the displacement field distribution of slope was analyzed during one year of monitoring a typical,natural slope in the Sichuan–Chongqing region. Observations include surface displacement, deep displacement, water level and rainfall. Finally, a targeted reinforced disposal scheme was proposed that considered the rainfall effect. The results provide reference for the instability theory and treatment measures for a high-risk stratified slope.

CHARACTERISTICS OF ROCK MASS STRUCTURE AND PREDICTION OF ROCK MASS BEHAVIOR OF HIGH-STEEP SLOPE

Due to the characteristics like high and steep slope and its strong concealment, the accurate identification of dangerous rocks in high and steep slope has always been confronting with great difficulty. The author uses technology like unmanned aerial vehicle aerial photography and Agisoft PhotoScan to establish the dioramas and three-dimentional data of the rock mass in high and steep slopes. Based on the principle that three points which are non-collinear can specify a plane, the author uses Visual Basic language to write a program in order to complete the calculation of structual plane's occurrence, thereby a algorithm is formed to accurately indetify the structual plane of rock mass and massively and rapidly extract point cloud data to calclulate the geometrical characteristics of structual plane's occurrence. And a typical rock mass slope in Zhejiang Immortals scenery area is selected as a case to analyze. After confirming the dangerous rocks, the motion features of the unstable rocks are predicted and analyzed with the assist of rolling rocks simulation software. The results show that once stones fall from A-D they will all hit directly in travel line, therefore cause great threaten to the security of travelers. It is advisable to take engineering measures as soon as possible to reduce risk levels.

Distribution and quantitative zonation of unloading cracks at a proposed large hydropower station dam Site

Rock mass unloading is an important rock engineering problem because unloading may impact the stability of a rock mass slope. Based on hydroelectric engineering principles, this study focuses on the classification of unloading zones to reflect the rock mass structure characteristics. Geological background and slope structure of the study region were considered to investigate the distribution and deformation of the unloading process. Quantitative indices were classified according to the formation mechanisms and the geological exhibition of unloading zones. The P-wave velocity (VP), the ratio of the wave velocity (KV, the ratio of the test P-wave velocity along the adit depth to the P-wave velocity of intact rock), the sum of joint openings every 2 meters (St), and the density of open joints (Dt) were calculated as quantitative indices for the rock mass unloading zone. The characteristics of the unloading zone of rock mass slopes at the dam site were successfully determined. The method of combining qualitative data with quantitative indices was found to be effective for the classification of slope unloading zones.

A numeral simulation of anchored interface shear stress for bolt in rock mass slope under earthquake

In order to extract the distribution regularities of shear stress on both slope’s anchored interfaces under earthquake at the same time, and reveal the mechanism of the shear interaction on anchored interfaces. Based on finite difference software FLAC3D, we build an anchored rock slope numerical model, simulated shear interaction on cable-grout interface and grout-rock interface by interface element, to study the distribution regularities of wholly grouted anchor bar anchored interface shear stress in anchored slope under simple harmonic vibration of seismic waves. The results of the study include the following: the shear stress on grout-rock interface reaches ultimate bond strength first, and debonding, the peak value of shear stress on grout-rock interface develop from failure surface to bolt end; at the same time, the shear stress on bolt-grout interface doesn’t reach ultimate bond strength, but the peak value of shear stress on bolt-grout interface move accordingly with that on grout-rock interface; after grout-rock interface debonding, the distribution of axial force along bolt is herringbone curve with both convex outer side, there is a one-to-one correspondence between curve inflection point of axial force and peak value point of shear stress on interface. The anchorage body in debonding region subjected uniform tension, the axial force in this region distributed relatively uniform. The study can provide references for study of model test, field monitoring, design and construction on relevant aspect.

Mechanism Analysis of the Failure for a Safe Jointed Rock High Slope: Tectonic Structures and Damage

Tectonic structures and tectonic damage of rock slope have an important effect on its failure mode, but it isn’t always paid attentions in actual engineering works. In the present study, a rock cut slope in Chongqing of China was reported. The survey results during the construction of the expressway indicated it should be safe, but it failed at last. The main reason is that tectonic tectonics and tectonic damage are not adequately taken into account in the design of this slope. The strong folds make the slope rock mass broken. Three groups of joints in the rock masses of the rock slope provide geometric conditions for landslides, and the further possible failure of the rock cut slope may follow the three group joints. The excavation change the stress environment of the slope and promote the destruction of the slope. Due to weathering processes, the integrality and shearing strength of the rock masses were reduced. The time-effect of excavations and weathering-effect are interacting with each other. Eventually, the slope not only slipped along the structural surface, but also produced plastic deformation damage. This indicates that in the design of the slope, the tectonic structures and tectonic damage must be fully considered, time effect is a factor which cannot be ignored.

Vibration Safety Criteria for Surficial Rock Mass of Open Pit Slope Affected by Underground Mining Blasting Operations

Introduction: Blasting vibration velocity is an important index to evaluate the stability of mine slopes under blasting operations. Objective: In order to determine the blasting vibration safety criteria for slope rock mass scientifically and reasonably, the influence of stress waves on surficial rock mass of mine slopes was analyzed when stress waves propagate to the slope surface, and mathematical models for blasting vibration safety criteria are proposed based on the ultimate tensile stress criterion, the ultimate shear stress criterion and the Mohr-Coulomb criterion. Results and Conclusion: Combined with the field blasting operations during the open-pit to underground mining in Daye iron mine, the blasting vibration safety criteria is calculated. It is obtained that the blasting vibration safety criteria for the north slope and the south slope are 11.08cm/s and 10.20cm/s respectively. The results agree well with the Safety Regulations for Blasting in China and provide a reference to determine blasting vibration safety criteria for other similar projects.