INTERNATIONAL JOURNAL OF CIVIL ENGINEERING AND TECHNOLOGY (IJCIET) STABILITY ANALYSIS OF EARTH DAM BY GEOSTUDIO SOFTWARE

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1 INTERNATIONAL JOURNAL OF CIVIL ENGINEERING AND TECHNOLOGY (IJCIET) ISSN (Print) ISSN 097 (Online) Volume, Issue, July- December (0), pp. 7- IAEME: Journal Impact Factor (0):.8 (Calculated by GISI) IJCIET IAEME STABILITY ANALYSIS OF EARTH DAM BY GEOSTUDIO SOFTWARE Dr. S. P. Tatewar, Laxman N. Pawade (Associate Professor, Department of Civil Engineering, Government College of Engineering, Amravati- 0, India, (M. Tech (Civil-Geo-tech) Scholar, Government College of Engineering, Amravati- 0, India, ABSTRACT Slope stability analysis of earth dam is very important to ascertain the stability of the structure. The stability of earth dam depends on its geometry, its components, materials, properties of each component and the forces to which it is subjected. The design of earth dams involves many considerations that must be examined before initiating detailed stability analyses. Such as geological and subsurface explorations, the earth and/or rock-fill materials available for construction should be carefully studied. This paper presents stability analysis carried out on m high Bhimdi earth dam situated near Tq. Warud Dist. Amravati (Maharashtra State) by changing different parameters such as changing berm width, changing position of filter drains and to gain desire stability how much strengthening required that was carried out by using software Geo-studio. The Existing design results are compared with the simulated results obtained from software Keywords: Design Parameters, Geo studio Software, Slope Stability, Strengthing.. INTRODUCTION Slope stability analysis using computers is an easy task for engineers when the slope configuration and the soil parameters are known. However, the selection of the slope stability analysis method is not an easy task and effort should be made to collect the field conditions and the failure observations in order to understand the failure mechanism, which determines the slope stability method that should be used in the analysis. Therefore, the theoretical background of each slope stability method should be investigated in order to properly analyze the slope failure and assess the reliability of the analysis results. Two dimensional slope stability methods are the most common used methods among engineers due to their simplicity. However, these methods are based on simplifying assumptions to reduce the three-dimensional problem to a two-dimensional problem and therefore the accuracy of the analysis results vary between the different analysis methods. Traditionally uncertainties in design parameters are assumed to be accounted for through the use of safety factors. By 7

2 International Journal of Civil Engineering and Technology (IJCIET), ISSN (Print), ISSN 097 (Online) Volume, Issue, July- December (0), IAEME assigning generous safety factors dam performance (capacity and safety) is assumed to remain in an acceptable range and it is customarily presumed that dams never fail. Nowadays, in most modern engineering codes and society, the appropriateness of the safety factor approach is being questioned. This approach does not allow for transparent accounting of uncertainties and for numerical quantification of safety. It does not permit for optimizing safety and economy uniformly across the system by associating.. LITERATURE REVIEW The literature shows considerable working on the study of stability of earthen dam by changing various parameters. Slope stability analysis by using limit equilibrium method in d and d shows two dimensional limit equilibrium methods will always estimate lower factors of safety compared to three-dimensional methods. Slope side effect should be considered in D limit equilibrium methods to produce more realistic simulation of the problem. Side resistance using the at-rest earth pressure coefficient should be considered can produce lower bound D factors of safety while using the active earth pressure coefficient can produce upper bound factor of safety.[].upstream side slope stability under sudden drawdown condition by computer programming shows the effect of horizontal drains on upstream slope of earth fill dams during rapid drawdown using finite elements and limit equilibrium methods. Changing of pore water pressure, outpouring seepage flow and factor of safety are inspected. By using Geo studio 00[]. Effect on factor of safety for varying thicknesses of core by using software SLIDE.0 were studied on construction of earth and rock fill dams. The study shows that stability of the dams depends on its geometry, materials properties and the forces to which it is subjected. []. GEOSTUDIO SOFTWARE Geo studio software is mostly used in varies civil engineering application and their problem analysis by considering different consideration. Now days it s widely used this area mostly for finite element analysis, slope stability, seepage analysis and so on other applications. Following are steps for used Geo studio 00 software. ) For slope stability open the Geo Studio SLOPE/W Define module. ) Identify the individual toolbars available. ) Set the working area. ) To set the working page size. ) Set the scale. ) Set the grid spacing. 7) Set and display the grid. 8) To save the data to a file. 9) To sketch an axis. 0) Sketch the slope stability problem. ) Specify the analysis methods. ) Specify the options used in the analysis. ) Define the soil properties. ) Draw the first region of the problem. ) Draw the piezometric line. ) Draw entry and exit location. 7) Turn off the points and the point numbers. 8) Display soil properties. 9) Verify the problem. 0) Save the problem. ) Viewing the results. 8

3 International Journal of Civil Engineering and Technology (IJCIET), ISSN (Print), ISSN 097 (Online) Volume, Issue, July- December (0), IAEME Table : The details of Bhimadi earth dam Topo sheet no. K/, K/ Latitude 9 0 longitude 78 0 Name of river Local Nalha sub basin Wardha Basin Godavari Total catchment area 7. Sq km free catchment area 7. Sq km, Avg.Annual 90.7mm Total yield available.98 Mm Annual utilization. Mm Gross storage.9mm Live storage.mm Dead storage 0.07 Mm Type of dam Earthen Dam Maximum dam 0.8 m Length of dam 0 m. Stability Analysis of Earth Dam by Changing Width of Berm Study of stability analysis of Bhimdi earth dam by changing width of berm was carried out by using Geo studio software. The effect of variation in width of berm on factor of safety is as discus below and existing soil properties are as shown in Table and properties of Anchors and nails are as shown in Table. Specification Table : Properties of Soil used Table casing of dam Filter Base foundion section layer (F) Foundion soil (F) hearting Unit Weight in KN/m Cohesion in KN/m Phi in degree Table : Properties of Anchorage and Nailing For Anchorage For Nailing Constant Applied Load 0KN/m Bond diameter 0.8m Bond diameter 0.8m Bond skin friction KN/m Bond skin friction KN/m Nailing Spacing.0m Anchor Spacing.0m Bar capacity 0KN/m Bar capacity 0KN/m Shear Capacity 0KN/m Shear Capacity 0KN/m Bar Safety factor.0 9

4 International Journal of Civil Engineering and Technology (IJCIET), ISSN (Print), ISSN 097 (Online) Volume, Issue, July- December (0), IAEME The critical slip surface s and Distance strength characteristics for varies conditions of dam observered by Geo studio software is shown in figure : (a) For both berm width m : (b) For both berm width m : (c) For both berm width m. 0

5 International Journal of Civil Engineering and Technology (IJCIET), ISSN (Print), ISSN 097 (Online) Volume, Issue, July- December (0), IAEME : (d) For both berm width m and Anchors : (e) For both berm of width m : (f) For both berm width m. Figure.: Critical slip surfaces and distance strength characteristics on downstream side dam section. The change in factor of safety for downstream side with respect to variation in berm width for existing dam section and relative factor of safety after providing variation in number of anchors and nails for strengthening of existing dam section with variation in length was computed and as shown in Table.

6 International Journal of Civil Engineering and Technology (IJCIET), ISSN (Print), ISSN 097 (Online) Volume, Issue, July- December (0), IAEME Table : Factor of safety for different condition s of dam section on Downstream side Factor of safety Length (For both Berm width) Condition of dam Nos of strengthening in (m) m m m Existing dam section With Anchor s With Nail s The variation in factor of safety for upstream side with respect to change in top and bottom berm width for existing dam section and relative factor of safety after providing variation in number of anchors and nails for strengthening of existing dam section considering water table condition with variation in length was computed and as shown in Table. Table : Factor of safety for various berm condition s on upstream side with strengthening Berm condition s Strengthening system Factor of safety Bottom berm width in m Top berm width in m Material Nos Length in m Without WT With WT Anchor Nail Anchor Nails

7 International Journal of Civil Engineering and Technology (IJCIET), ISSN (Print), ISSN 097 (Online) Volume, Issue, July- December (0), IAEME Anchor Nails Anchor Nail Anchor Nail

8 International Journal of Civil Engineering and Technology (IJCIET), ISSN (Print), ISSN 097 (Online) Volume, Issue, July- December (0), IAEME. INTERPRETATION OF RESULTS AND DISCUSSIONS From The results obtained the factor of safety against berm width was plotted and is as shown in figure below. Fig..: Plot between berm width and F.O.S. on downstream side Fig..: Plot shows variation of bottom berm width up to m with top berm width m. Fig..: Both berm width is up to m on up stream side. From the above graph it was observed that the factor of safety deceases with decreasing in berm width. Various trials were performed to achieve design factor of safety by strengthening of dam with anchors and nails. The results obtained by considering the strengthening with anchor and nail for various berm widths are as shown Figure. and..

9 International Journal of Civil Engineering and Technology (IJCIET), ISSN (Print), ISSN 097 (Online) Volume, Issue, July- December (0), IAEME (a)for m berm width (b)for m berm width Fig..: : Effect of strengthening on factor of safety on downstream side of earth dam section. a) Plot shows variation of bottom berm width up to m with top berm width m. b) Both berm width is up to m on up stream side. Fig..: : Effect of Strengthening on Factor of Safety on Upstream Side Dam Section.

10 International Journal of Civil Engineering and Technology (IJCIET), ISSN (Print), ISSN 097 (Online) Volume, Issue, July- December (0), IAEME By considering the combination of bottom berm width from m to m, and top berm width m to m, the factor of safety is increases after strengthening by anchoring and nailing. Table V. shows the variation however; It is observed that there is no variation in factor of safety after combination bottom berm width m and top berm width m (bottom berm width m and top berm width varies from m to m). Computer base stability analysis is gives us fast result but basic data required such as soil properties as well as properties and availability of strengthening material such as anchoring and nailing and other are to be calculated manually. This is very advantageous for comparative calculation of analysis by computer base and traditional method.. CONCLUSIONS Computer base analysis is comparatively easy to compute and check stability analysis. Variation in width of berm on upstream and downstream side of dam section is directly affected on factor of safety. It is conclude that by changing the berm width of earth dam the factor of safety can be restored by anchoring and nailing. The effect of anchoring and nailing on factor of safety is as shown in graph. Anchoring and nailing is not so effective in water impounded area of dam section. As per USBR recommends for earth dam section of m height required minimum m berm. By using software results less than m width berm with strengthening is not so satisfactory. There is no such improvement in increment of factor of safety. REFERENCES [] Nermeen Albataineh, (00) slope stability analysis using d and d methods. A thesis, -. [] S. M. Ali Zomorodian (00) Effect of Horizontal Drains on Upstream Slope Stability During Rapid Drawdown Condition,International Journal Of Geology Issue, Volume, -. [] Khanna Rajesh, Datta Manoj Ramana & G.V. (0) Effect of Variation in Vertical Core Thickness on Stability Analysis of Earth and Rockfill Dams, International Journal of Earth Sciences and Engineering ISSN , Volume 0, No 0 SPL, -7.