scholarly journals THE GEOLOGICAL STRUCTURE EFFECTS ON SLOPES STABILITY AND TUNNELS OF METAMORPHIC ROCKS AT POBOYA GOLD MINE PALU

Author(s):  
Sriyati Ramadhani ◽  
Ahmad Rifa'i ◽  
Wahyu Wilopo

Poboya area has many geological structures that result in distribution of strength and stress of rocks not evenly distributed, as a result, the rock mass strength becomes disturbed and slopes become unstable. The objective of the study was to determine the geological structure effect on slope stability and tunnel conditions on metamorphic rocks at the Poboya gold mine. The study was conducted in the Mantikulore sub-district, Palu, Central Sulawesi. Lithology composing study area is metamorphic rocks consisting of gneiss and schist, therefore, the analysis was carried out on both locations which have many geological structures. Numerical analysis was performed applying the finite element method with the RS2 program assistance. The findings show that the safety factor value of the existing slope at gneiss and schist location under static loading is 4.6 and 2.72, if there is an earthquake it becomes 1.07 and 0.77. The safety factor value under static loading with the joint is 4.58 and 2.03, while under dynamic loading with joint, it becomes 0.94 and 0.64. The geological structure effect which represented by the joint gave a big impact with a decrease of safety factor at gneiss about 0.43% under static loading and 80% under dynamic loading. Meanwhile, at schist, safety factor decreased 25% under static loading and 76% under dynamic loading. For tunnel stability, the existence of joint will increase the displacement of 65% at gneiss under static loading and 84% under dynamic loading, while at schist, it increases 25% under static loading and 54% under dynamic loading. This illustrates that geological structures under dynamic loading affect significantly slope stability of Poboya gold mine.

2014 ◽  
Vol 881-883 ◽  
pp. 1719-1725
Author(s):  
Zhi An Huang ◽  
Huan Yong E ◽  
Ying Hua Zhang ◽  
Yu Kun Gao ◽  
Ming Shan Gong

As the geological condition of western Luming molybdenum mine is broken and there are faults through, to find out the geological structures of west mine is quite significant for the study of Luming mine slope stability. With EH4 geophysical technology to detect west Luming molybdenum geological condition, the data of the detection point was collated and sorted out, through the inversion method, two faults F3 and F4 was inferred in the west zone of LuMing mine, which is likely to cause slope instability phenomena. What is more, at the northwest of the pit, lithology with water was composed of alluvial deposits and broken sediments, the depth of the strata with water is more than 80 miles. So the impact of water on slope stability should be fully considered during mining process.


2019 ◽  
Vol 5 (2) ◽  
pp. 149 ◽  
Author(s):  
Diana Ariesta

Landslide is a natural phenomenon that can be controlled by a combination of various factors, such as topography, lithological condition, geological structure, water table, etc. Landslide is stated as a natural disaster if it causes casualties, direct losses and subsequent impacts of the initial destruction, as happened in Banaran Village, Ponorogo Regency. This study is aimed to examine the effects of initial groundwater table conditions and rainfall wetting on Banaran Village landslide. This study was conducted by assuming scenarios of initial groundwater table conditions. Soil parameters were obtained by testing soil samples in the laboratory. Infiltration parameters were acquired through permeability tests using the Philip-Dunne method, while areal rainfall was calculated using the Thiessen polygon method. In addition, slope stability modeling was calculated by using SLOPE/W while rainfall wetting analysis was carried out through SEEP/W. The analysis of Banaran Village landslide through these two numerical models was conducted by considering two conditions: 1) without rainfall and 2) with rainfall and infiltration. The analysis results imply that the landslide occurred in the initial groundwater table condition in scenario 3 with a safety factor of 1.008, and in a similar scenario with a safety factor of 0.973 when taking into account rainfall and infiltration. The results from SEEP/W and SLOPE/W indicate that the initial condition of the groundwater table highly influenced the decrease of the safety factor, while the wetting process did not cause a significant decrease of the safety factor.


2013 ◽  
Vol 275-277 ◽  
pp. 1423-1426
Author(s):  
Lin Kuang ◽  
Ai Zhong Lv ◽  
Yu Zhou

Based on finite element analysis software ANSYS, slope stability analysis is carried out by Elastic limiting equilibrium method proposed in this paper. A series of sliding surface of the slope can be assumed firstly, and then stress field along the sliding surface is analyzed as the slope is in elastic state. The normal and tangential stresses along each sliding surface can be obtained, respectively. Then the safety factor for each slip surface can be calculated, the slip surface which the safety factor is smallest is the most dangerous sliding surface. This method is different from the previous limit equilibrium method. For the previous limit equilibrium method, the normal and tangential stresses along the sliding surface are calculated based on many assumptions. While, the limit equilibrium method proposed in this paper has fewer assumptions and clear physical meaning.


2021 ◽  
pp. 46-54
Author(s):  
Muhammad Amin Syam ◽  
Heriyanto Heriyanto ◽  
Hamzah Umar

PT Belayan Internasional Coal is an open-pit system mining company, one of its geotechnical activities is the construction of the slopes. Slope stability analysis used the Bishop Simplified method to obtain the value of the dynamic safety factor (≥ 1,1). Currently, the value of the Safety Factor (FK) is an indicator in determining whether the slope is stable or not. The parameters used in the slope stability analysis are the physical and mechanical properties of the rock, namely weight (ɣ), cohesion value (c), and internal shear angle (∅). From the results of dynamic overall slope calculations, the recommended overall slope is constructed with an individual slope angle of 55°, a bench width of 5 meters, a height of 10 meters, and the number of individual slopes of 8 slopes. This design will produce dimensions of the overall slope with 41° slope angle, 80 meters high, and has a dynamic safety factor value of 1,102 with the water-saturated condition. Thus, the slopes are in stable condition.


Author(s):  
Miftahul Jannah ◽  
Adi Suryadi ◽  
Muchtar Zafir ◽  
Randi Saputra ◽  
Ihsanul Hakim ◽  
...  

On the study area there are three types of structure, those are fault, fold and joint. Types of fault were found  in the study area, reverse fault with the strike/dip is N215oE/75o, normal fault has a fault directions N22oE and N200oE with pitch 35o, and dextral fault with pitch 10o and strike N219oE. Fold and joint structures used to determine the direction of the main stress on the study area. Further, an analysis used stereonet for data folds and joints. So that from the data got three directions of main stress, those are Northeast – Southwest (T1), North – South (T2) and Southeast – Northwest (T3). On the Northeast – Southwest (T1) stress there are four geological structures, anticline fold at ST.3 , syncline folds at ST. 13a, ST. 13b, ST. 13c and ST. 33, chevron fold at ST. 44 and joint at ST. 2. On the North – South (T2) stress there are three geological structures, those are syncline fold at ST. 35, anticline fold at ST. 54 and joints at ST. 41, ST. 46 and ST. 47. On the Southeast – Northwest (T3) stress were also three geological structures, those are chevron fold at ST 42a, overturned fold at ST. 42b, syncline fold at ST. 42c and joints at ST. 5 and ST. 34.


Land ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1250
Author(s):  
Sina Shaffiee Haghshenas ◽  
Sami Shaffiee Haghshenas ◽  
Zong Woo Geem ◽  
Tae-Hyung Kim ◽  
Reza Mikaeil ◽  
...  

Slope stability analysis is undoubtedly one of the most complex problems in geotechnical engineering and its study plays a paramount role in mitigating the risk associated with the occurrence of a landslide. This problem is commonly tackled by using limit equilibrium methods or advanced numerical techniques to assess the slope safety factor or, sometimes, even the displacement field of the slope. In this study, as an alternative approach, an attempt to assess the stability condition of homogeneous slopes was made using a machine learning (ML) technique. Specifically, a meta-heuristic algorithm (Harmony Search (HS) algorithm) and K-means algorithm were employed to perform a clustering analysis by considering two different classes, depending on whether a slope was unstable or stable. To achieve the purpose of this study, a database made up of 19 case studies with 6 model inputs including unit weight, intercept cohesion, angle of shearing resistance, slope angle, slope height and pore pressure ratio and one output (i.e., the slope safety factor) was established. Referring to this database, 17 out of 19 slopes were categorized correctly. Moreover, the obtained results showed that, referring to the considered database, the intercept cohesion was the most significant parameter in defining the class of each slope, whereas the unit weight had the smallest influence. Finally, the obtained results showed that the Harmony Search algorithm is an efficient approach for training K-means algorithms.


2019 ◽  
Vol 16 (5) ◽  
pp. 939-949
Author(s):  
Yonggao Yue ◽  
Tao Jiang ◽  
Jingye Wang ◽  
Yunfeng Chao ◽  
Qi Zhou ◽  
...  

Abstract Performing exact predictions of geological conditions for tunnel construction is important for ensuring safe and quick tunnel engineering. Weak effective signals and strong random noise are the main factors that affect the distance and precision of tunnel seismic detection. Considering that directional seismic wave (DSW) technology has the ability to enhance target signals and suppress random noise, we attempt to apply this method to solve the problems of low detection accuracy and short detection distance. However, the process of data processing with the DSW technique generates false multiple wave interference (FMWI), which can lead to the misinterpretation of geological structures. This study analyses the origins of FMWI and presents the random dislocation directional seismic wave (RDDSW) method to suppress this interference. The results of a numerical simulation indicate that the FMWI is effectively suppressed and that the signal-to-noise ratio of the data is increased by approximately N times through use of the N-element RDDSW technique. In the ideal case, only spherical diffusion attenuation is considered, and the detection distance increases by approximately $\scriptstyle\sqrt N $ times. In addition, this method is also effective for signals from curved events, thereby improving the precision of the analysis of the geological structure of the tunnel. Furthermore, the field data results further verify that the RDDSW technique can significantly suppress interference and thus improve the quality of the data at little cost. Hence, the RDDSW technique has great significance for accurately predicting the geological structures of tunnels and increasing the detection distance in tunnels.


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