AN EXPERIMENTAL STUDY OF SLOPE STABILITY WITH GROUP ACTION OF MICROPILES

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 8, August 2018, pp , Article ID: IJCIET_09_08_007 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed AN EXPERIMENTAL STUDY OF SLOPE STABILITY WITH GROUP ACTION OF MICROPILES Harish Chand Post Graduate, Department of Civil Engineering Chandigarh University, Gharuan, District, Mohali, Punjab, India Jagdeep Singh Assistant Professor, Department of Civil Engineering Chandigarh University, Gharuan, District, Mohali, Punjab, India ABSTRACT This paper discusses an experimental study of slope stability of modeled soil by considering group action of micropiles. To find the load carrying capacity of grouped micropiles which are embedded in soil, known lengths and diameter of micropiles are taken for experiment purpose. For group action of micropiles diameter and lengths are considered constant for every pile that was used in experiment. Pile load test are performed to check the capacity of individual and group action of piles. Sandy soil are randomly taken from the campus of Chandigarh University Punjab.Group action of micropiles in sandy soil by using pile load test which was setup in campus of Chandigarh University, Punjab (India). The present investigation consist of manually model soil micropiles experimental study of group action of micropiles where the major consideration are spacing of micropiles which influence the micropiles capacity. From the experiment it has been seen that the load carrying capacity of grouped micropiles depends upon the spacing of micropiles. Key words: Sandy soil; Group micropiles; Stability; Pile load test. Cite this Article: Harish Chand and Jagdeep Singh, An Experimental Study of Slope Stability with Group Action of Micropiles. International Journal of Civil Engineering and Technology, 9(8), 2018, pp INTRODUCTION A slope is defined as, when it is required to raise level line of a highway over the current ground level it ends up important to construct embankments or embankments can also be defined as a raised bank to carry a road, across a low-lying area, as given in figure

2 An Experimental Study of Slope Stability with Group Action of Micropiles Figure 1 Embankment of Soil 1.1. Height of Embankment The height of embankment relies upon the desired grade line of the roadway and profile of soil structure or topography 2. STABILITY OF SLOPES The embankment of slopes should sufficiently be stable so that the feasibility of the fall may be extinct under the contrary wetness and other unfavourable duration. Therefore the farness of slope should be observed or the slope should be planed giving least factor of safety of 1.5. Repeatedly, slopes with absolute flatness are liked in main road embankment because of aesthetic and different causes Slope Failure Factors Figure 2 Roadway slope & slope above highway (Source ftp://ftp.odot.state.or.us) Gravity can be partitioned into segments acting parallel to a incline and opposite to the slant. Disappointment will probably happen if the impact of friction on the potential sliding surface is reduced. The physical properties of the incline materials, for example, cohesion between grains may diminish the potential for slant failure. The edge of rest is the most extreme slope produced when loose unconsolidated material is framed into the piles. The expansion of overabundance water may destabilize slopes by including weight, destroying attachment amongst grains, and diminishing friction

3 Harish Chand and Jagdeep Singh 2.2. Major Conditions for Slope Failure The failure of embankment is caused by various reasons out of which the important reasons are listed below: A portion of the roadways site needs to fill in to level the site for construction of the embankment. In the event that the compaction of fill isn t done properly or contains such materials that is vulnerable to extraordinary change in the volume then settlement can happen. The best of the soil is accessible locally is regularly selected with a view to keep the lead and lift as low as would be prudent. Excessive rain, not sufficient drainage can cause all the slopes or foundation problems. The type of soil and its bearing capacity assumes essential part in embankment failure. The most widely recognised purpose behind failure of soil is settlement of soil. The other manner by which soil can come up short shear strength. At the point when load acting on it acts literally, it might prompt shear failure in soil. It is generally occurred in case of loose sandy soil. Erosion: At the point when regular conditions are altered by the construction of a road, it marks the beginning of a race between appearance of erosion and the development of vegetation. Unsettling influence amid construction can disturb the frequently sensitive adjust between stabilizing, components, for example, vegetation and other which look to destabilize such as running water, In some cases, erosion may come about in cumulative slopes, streams, waterways and dams at some separation from the underlying effects The variables prompting the failure of slope might be ordered into two categories The elements which cause an expansion in the shear stresses. The stresses may increment because of weight of water causing immersion of soil surcharge loads, leakage or some other reason. The stresses are additionally expanded to steepening of slants either by natural erosion. The components which cause a decrease in the shear quality of soil. The loss of shear quality may happen because of an expansion in water content, increment in pore water weight, cyclic loads, or any other cause. The majority of the normal slope failure happens amid blustery seasons as the presence of water causes the two expands stresses and loss of strength. 3. MICROPILES These days to enhance capacity (bearing) of the soil and to stabilize the soil especially in loose soil, different techniques are been utilized that incorporate different strategies for improvement. Extraordinary compared to other techniques out of those is utilization of micropiles. The use of micropiles technique is increasing day by day because it is efficient, minor materials, choice of quick equipment and transport of micropiles execution facilities and settlement control. Piles are separated into two general composes: replacement piles and displacement piles (Fleming et al, 1985). Replacement piles are constructed inside a formerly penetrated borehole, thus the uncovered ground. Displacement piles are operated into the ground. The surrounding soil are displacing during the installation of displacement piles. Piles with diameter of 300 mm or 30 cm are generally referred as micropiles. Micropiles can withstand axial and additionally horizontal loads, and might be viewed as a substitute for ordinary piles or as one part in a composite soil, depending on the design concept employed

4 An Experimental Study of Slope Stability with Group Action of Micropiles Micropiles are installed by techniques that cause insignificant unsettling influence to neighbouring structures, soil and the nature. They can be introduced in access-prohibitive nature and ground conditions and in all types of soil. Figure 3 Micropiles 3.1. Micropiles Action in Groups A micropile isn't utilized uniquely underneath a segment or divider since it is greatly hard to drive the micropile totally vertical and to put the establishment precisely finished it s inside line. In genuine practice, auxiliary loads are upheld by a few micropiles going about as a gathering. Minimum three numbers of micropiles was used to hold the single column in a shape of triangle. Staggered patters of micropiles were considered in wall construction on the both side of centre line of walls. Whole loads is transferred to the micropiles by a single unit is known as pile cap as shown in figure 4 Figure 4 Pile group At the point when micropiles are put in a gathering, there is a probability the weight isobars of nearby micropiles will cover each different as appeared in Fig.5 (b).the dirt is exceptionally worried in the zones of covering of weights. With adequate cover, either the dirt will come up short or the micropile gathering will settle too much since the consolidated weight knob stretches out to a significant profundity underneath the base of the micropile. It is conceivable to dodge cover by introducing the micropiles promote separated as appeared in Fig 5 (c). Large spacing is suitable some time because it increase the pile cap length and also increase the cost so that the proper spacing are required for the micropiles

5 Harish Chand and Jagdeep Singh Figure 5 Pressure isobars of (a) single pile, (b) group of piles, closely spaced, and (c) group of piles with piles far apart. Group efficiency of group micropiles ( ) Where ultimate load of the piles works in group, = the ultimate load of the pile for individual behaviour of pile action, N = Total number of piles working in the group. 4. EXAMPLE OF APPLICATION AND MONITORING THE DATA Figure 6 Experiment arrangement To study the group action of micropiles against the slope failure, a modeled is prepared in campus of Chandigarh University, Punjab (India) was adopted an example for experiment

6 An Experimental Study of Slope Stability with Group Action of Micropiles Height of slope is modeled approximate 0.70 m and length is 1.5 m with angle 69ᵒ.load is manually applied on soil slope. Steel bar of 10 mm are considered as micropiles. Pressure applied is notice in the pressure gauge. Sandy soil is used for experiment purpose. All the soil parameters are check and all lab experiment are performed on soil sample. Lengths of micropiles are kept same for all the micropiles used in group. The calculations are taken on the bases of experiment performed by pile load test on sandy soil. (Meyerhof s method and IS: 2911-part Load test on piles) D C = 0.31m q = 7.02 q =2000 p =1.09 kn The point resistance or tip resistance of piles is ( p ) =1.09 kn p = kn Q s =1.09 kn To find out the point bearing pile action in group multiply the numbers of piles with ultimate capacity of single pile. Ultimate capacity of single pile is =1.09kN 5. CONCLUSIONS From the experimental setup its was observed that the spacing of micropiles is most important for group action of piles, By and large, the dispersing for point bearing micropile, for example, micropile established on rock, can be significantly less than for contact micropile since the high-point-bearing stresses and the superposition impact of cover of the point stresses will in all likelihood not overemphasize the fundamental material nor cause inordinate settlements For end bearing micropile going through compressible strata and resting in firm (clay) earth, the separating might be expanded to 3.5d. The base suitable separating of micropiles is normally stipulated in construction laws. The spacing s for straight uniform breadth micropile may change from 2 to 6 times the distance across of the pole. For friction micropile, the base dividing prescribed is 3d. For end bearing micropile going through moderately compressible strata, the dividing of micropile will not be under 2.5d. From the experiment it was proved that the efficiency of group micropile depends upon the spacing between micropiles. REFERENCES [1] Abdelaziz, Ahmed, Dahlia Hafez, and Ashraf Hussein. "The effect of pile parameters on the factor of safety of piled-slopes using 3D numerical analysis." HBRC Journal (2015). [2] Cai, Fei, and Keizo Ugai. "Numerical analysis of the stability of a slope reinforced with piles." Soils and foundations 40, no. 1 (2000):

7 Harish Chand and Jagdeep Singh [3] Chow, Y. K. "Analysis of piles used for slope stabilization." International Journal for Numerical and Analytical Methods in Geomechanics 20, no. 9 (1996): [4] Dr. K. R. Arora Soil mechanics and foundation engineering, (1987)Standerd publishers distrebuters,(2015) ISBN: [5] Elsaied, Ahmed Elzoghby. "Performance of footing with single side micro-piles adjacent to slopes." Alexandria Engineering Journal 53, no. 4 (2014): [6] Georgiadis, K., M. Georgiadis, and C. Anagnostopoulos. "Lateral bearing capacity of rigid piles near clay slopes." Soils and Foundations 53, no. 1 (2013): [7] He, Yi, Hemanta Hazarika, Noriyuki Yasufuku, and Zheng Han. "Evaluating the effect of slope angle on the distribution of the soil pile pressure acting on stabilizing piles in sandy slopes." Computers and Geotechnics 69 (2015): [8] He, Yi, Hemanta Hazarika, Noriyuki Yasufuku, Zheng Han, and Yange Li. "Threedimensional limit analysis of seismic displacement of slope reinforced with piles." Soil Dynamics and Earthquake Engineering 77 (2015): [9] Sharma, Binu. "A Model Study Of Micropiles Subjected To* Lateral Loading Condition." In Indian Geotechnical Conference Guntur, pp [10] Shin, E. C., C. R. Patra, and A. K. Rout. "Automated stability analysis of slopes stabilized with piles." KSCE Journal of Civil Engineering 10, no. 5 (2006): [11] Song, Young-Suk, Won-Pyo Hong, and Kyu-Seok Woo. "Behavior and analysis of stabilizing piles installed in a cut slope during heavy rainfall." Engineering Geology 129 (2012): [12] Summersgill, F. C., S. Kontoe, and D. M. Potts. "On the use of nonlocal regularisation in slope stability problems." Computers and Geotechnics 82 (2017):