Stabilit
slope is a very important factor in the work related to
excavation and stockpiling of soil, rocks and minerals, because it
involves the issue of human safety (workers), security equipment and the
smooth production. The
circumstances are associated with the various types of work, such as
the construction of roads, dams, canal excavation, excavation for
construction, mining and others.In
mining operations slope stability problems will be found in the open
pit excavations, dams for water supply work, dump the waste (tailings
disposal) and stockpiling ore (stockyard). If
the slopes are formed as a result of the mining process (pit slope) as
well as a means of supporting a mining operation (such as dams and
roads) is not stable, it will disrupt production activities.From
the above description, it is understood that the slope stability
analysis is an important part to prevent disruption to the smooth
production and the occurrence of the fatal disaster. In the undisturbed state (naturally), soil or rocks generally are in balance against the forces that arise from within. If
for whatever reason such as changing the balance due to lifting,
lowering, excavation, backfilling, erosion or other activities, then the
soil or rock that will strive to achieve new circumstances naturally. This
method is usually a process of degradation or reduction of the load,
especially in the form of an avalanche-avalanche or other movements
until a new equilibrium is reached circumstances. On
the ground or in a state of undisturbed rock (naturally) been working
voltages of vertical, horizontal and pore water pressure. Three of the above have an important role in shaping the slope stability.While
the soil or rock itself has original physical properties, such as the
shear angle (angle of internal friction), cohesion force and weight of
the contents is also very important role in determining the strength of
the soil and that also affects the stability of the slope. Therefore,
in an attempt to perform slope stability analysis should be known with
certainty voltage system that works on the ground or rocks and also
physical properties of the original. With the knowledge and the data can then be analyzed the behavior of soil or rock if excavated or "bullied". After
that, it could be determined that the slope geometry allowed or apply
other methods that can help to stabilize the slope and steady.In
determining slope stability or steadiness known term safety factor
(safety factor) which is the ratio between the forces that resist the
movement of the forces that drive land is considered stable, when
formulated as follows:Factor of safety (F) = force retention / driving forceWhere to state:F> 1.0: slope in the steady stateF = 1.0: seimbnag slopes in the state, and is ready to slideF <1.0: unstable slopesSo
in analyzing the stability of slopes will always be associated with the
calculation of the number of factors to determine the safety of the
slope. There are several factors that affect the stability of slopes, among others:1. Spreading rockDistribution
and diversity of rock types is associated with slope stability, is due
to the strength, physical and technical properties of the different rock
types with other rocks. Leveling rock types will result in an error analysis. For example: slope consisting of sand would be different with a slope consisting of clay or mixtures thereof.2. Geological
structure of the geological structures that affect slope stability and
need to be considered in the analysis is a regional and local
structures. These structures include faults, stocky, bedding plane, syncline and anticline, unconformity, liniasi, etc.. This
structure greatly affects the strength of the rock because it is
generally a weak field in the rock, and water seepage is a place that
accelerates the weathering process.3. MorphologyMorphological state of a region will greatly affect the stability of the slopes in the area. Morphology
consisting of a physical condition, characteristics and shape the
earth's surface, determine the rate of erosion and deposition that
occurs, menent ukan direction of flow of surface water and ground water
and rock weathering process.4. ClimateClimate affects the temperature and amount of rain, so that also affect the weathering process. The tropics are hot, humid with high rainfall will cause rock weathering process is much faster than the sub-tropical regions. Because of the thickness of the soil in the tropics is thicker and lower power than the fresh rock.5. Weathering rateRate
of weathering affect the original properties of rocks, such as cohesion
figures, the magnitude of the shear angle, bulk density, etc.. The higher rate of weathering, the rock strength will decrease.6. The work of humanIn addition to natural factors, human also contributed no small. For
example, an initially stable slope, because humans cut down shade
trees, tillage is not good, not good drainage, excavation / mining, and
other causes such slopes become unstable, so that erosion and landslides
easily happen.Basically
avalanches will occur for two reasons, namely increased shear stress
(she ar st ree s) and a decrease in shear strength (shear strenght). The factors that can increase the shear stress is:1. Reduction buffering lateral, partly because of erosion, avalanches earlier that generate new slopes and human activities.2. Voltage increase, partly because of the addition of loads, seepage water pressure, and stacking.3. Dynamic force, which is caused by earthquakes and other vibrations.4. Appointment or regional decline, caused by the movement of mountain formation and changes in slope angle.5. Removal
of the buffer, which is caused by cutting the cliffs by the river,
weathering and erosion under the surface, mining and tunneling,
reduction / destruction of materials at the base.6. Lateral
voltage, which is caused by the presence of water in cracks and
freezing water, a layer of clay swelling and residual displacement
voltage. While the factors that reduce the shear strength is:a) The state or baseline, is already low from the start due to the composition, texture, structure and geometry of the slope.b)
Changes due to physical weathering and chemical reactions, which cause
berposi into soft clay, disinteggrasi granular rocks, falling cohesion,
pengggembungan clay layers, dissolving the cementing material rocksc) Changes in force between the grains due to the influence of water content and pore water pressure.d) Changes in the structure, such as the formation of cracks in the clay contained in the cliff / slope.1.1. Geometry Level (Bench Dimension)Before you know some opinions about the dimensions levels, please note on level terms as shown below. In determining the level gometri, some things to consider, among other things:1. Daily and annual production targets2. Size mechanical devices used3. In accordance with the ultimate pit slope4. According to the criteria of slope stabilityThe
elements consist of a high level, the determination of the width and
slope dimensions influenced by: (1) heavy equipment used (especially the
digging and transport equipment), (2) the geological conditions, (3)
physical properties of rocks, (4 ) the expected separation selectivity between ore and waste, (5) the rate of production and (6) climate. High
level is the vertical distance between the horizontal level in the pit;
wide horizontal distance floor level is a place where all the
activities excavation, loading and drilling-blasting carried out, and
the slope of the ladder is the ladder slope angle. Sought appropriate level height limit dertgan type tool used in order to fit the peak load reached by boom equipment. Besides,
the upper limit level must also take into account the stability of the
slope, which is not due to landslides caused by rain or blasting
vibration. High on open pit and quarry andesite and granite about 15 m, whereas the uranium mine is only about 1.0 m.Tilt wall ladder is one of the factors that affect the size and shape of the pit and the pit area. Slope levels will also help to determine the amount of waste that must be removed to get the ore. Mentioned
earlier that the slope should be stable level during the last
penggailan activity, therefore it is necessary to analyze the stability
of the slopes around the mine area (pit). Rock
strength, fracture, cracks, soil water content and other geological
information is the key factor to analyze the mine slope. Result
of differences in the characteristics of rocks and geological
information, then do not be surprised if in the mining area will be a
different slope. The slope of the wall surface work (individual slope) on ore mining and quarry rock compact ranges between 720-850. Width
determination will be influenced by the level of the desired production
rate, the dimensions and the number of carriers and unloading
equipment, the drilling-blasting activities and geological conditions
around the pit.There
is no standard formula to determine the level width; however, some
important parameters below should be considered, include:1. radius maneuver conveyance when the material will be loaded by the loading tool, Rm:2. flexible enough to run into at least two means of conveyance, 2 Lt + c;3. The maximum width of the output stack blasting (muckpile), Mp;4. the width of the area to be drilled, Ld.Based
on the above parameters, it may be possible empirical formulas wide
level (LB) as follows: LB = Rm + (2LT + c) + Mp + Ld parameter Lt is the
width of a truck maximum and c is a constant that depends on the
distance of the two trucks are safe when passed, which is between 5.0 m to 10 m. Some of those who issued an opinion regarding the dimension level, among others:1. Head Quarter of U.S. Army (sand Pit Quarry Technical Bulletin No. 5-352)2. Lew is (Elements of Mining)3. L. Shevyakov (Mining of Mineral Deposits)4. Melinkov and Chevnokov (Safety in Open Cast Mining)5. Popov (The Working of Mineral Deposits)6. Young (Elements of Mining)7. E. P. Pfeider (Surface Mining)8. Head Quarter of U.S. Army (sand Pit Quarry Technical Bulletin No. 5-352)Wmin = Y + G + Ls + Wt + Wbwherein:Wmin: minimum path width (m)Y: The width is provided for drilling (m)Wt: width provided for the tools (m)Ls: power shovel without a boom length (m)G: Radius floor work was interrupted by a shovel (m)Wb: Width of broken material (m)1. Lewis (Elements of Mining)High levels as follows:a. For good hidraulicking is 20 ft and 60 ft maximumb. Ideal for dredging depths between 50 ft - 80 ft, but there are up to 130 mc. Open-cut to between 12 ft - 75 ft; were a good 30 ft. As for the mine ore can reach 225 feet. Wide level adjusted for loading tracks, power shovels and regional operations for blasting. Width between 20 ft - 75 ft, 50 ft and ideally generally 30 ft.2. L. Shevyakov (Mining of Mineral Deposits)Wide level depending on the method of excavation and hardness minerals are mined.a. For Soft MaterialsB = (1.00 s.d 1.50) Ro + L + L1 + L2WhereB: Width levels (m)Ro: Digging radius of tool load (m)L: Distance ant fig ladder with side rails (3-4 m)L1: Width lori (1.75 to 3.00 m)L2: Distance to guard against erosion (m)b. For Hard MaterialsB = N + L + L1 + L2WhereB: Width levels (m)N: width needed for broken material (m)Here is not provided width for excavator / unloading, as deemed fit to work beside broken tool material3. Melinkov and Chevnokov (Safety in Open Cast Mining)a. For the soft layer (soft strata)B = 2R + C + C1 + LWhereB: Width levels (m)R: Digging radius of tool load (m)C: Distance sided ladder or broken rail material to the center line (m)L: width provided for the safety factor, usually of dump-truck (m)b. For the soft layer (soft strata)C = A + B + C1 + L + AWhereB: Width levels (m)A: Width of broken material (m)A: Width of cutting pert ama (m)
4. Popov (The Working of Mineral Deposits)a. High level and slopeSlope depends on the level of minerals in the water bladder; when relatively dry normally allows a large degree slope.ii) Generally high levels ranged from 12-15 m with a slope:1) for igneous rocks: 70o - 80o2) for sedimentary rocks: 50o - 60o3) for the rock ledge and dry sand: 40o - 50o4) to rock argilaceous: 35o - 45ob. Wide levelPath width between 40-60 m, usually made between 80-100 m when using multi-row bore hole. Minimum width for hard rock:Vr = A + C + M + B + C1WhereVr: Width Minimum level (m)A: Width of broken material (m)C: Distance to the center of the rail embankment (m)C1: Half width of a lorry (m)B: Width blown sediments (6-12 m)L: Width is provided to ensure the extraction of sediment at levels below5. Young (Elements of Mining)a. High levels of1) to mine iron ore: 20-40 ft2) to mine copper ore: 30-70 ft3) to lime st on e: s.d. 200 ftb. Wide level: 50-250 ftc. Degree slope: 45o - 65o
6. E. P. Pfeider (Surface Mining)L = Lm + SF xWhereL: High level (m)Lm: Maximum height of the cutting-tool loading (m)SF: Swell Factor (m)x = 0.33 for how to corner cut= 0.50 for a box cut way
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