en Geotechnique Geotechnique Research Paper Research Paper Stabilization of earth slopes with various proposed methods is one of the important concerns of geotechnical engineering. In this practice, despite numerous developments, design conservativeness and high costs of stabilization are the issues yet to be addressed. This paper not only deals with pile location optimization but also studies the effects of the pile length by using line segments slip surface (non-circular). Taking into account the line segments slip surface in stabilization of earth slopes is a new topic which has been addressed in this paper. The line segments slip surface is actual slip surface and for determining the pile location it can lead to the actual length of the pile. The line segments critical slip surface is obtained by using the Alternating Variable Local Gradient (AVLG) optimization method. AVLG is an approach in optimization process and it is based on the Univariate method. The line segments form the initial and critical slip surface. Pile improper installation and inadequate length not only fails to increase the factor of safety, but also reduces it. The analyses are performed using the limit equilibrium (LE) method. Results of these analyses are acceptable and are properly consistent with the results obtained by other researchers. Stabilization of earth slopes, Line segments slip surface, Pile length, Pile location optimization 14 27 http://ijce.iust.ac.ir/browse.php?a_code=A-10-1174-2&slc_lang=en&sid=1 M. hajiazizi mhazizi@razi.ac.ir 180031947532846009481 180031947532846009481 Yes Department of Civil Engineering, Razi University, Taghe Bostan, Kermanshah, Iran A. R. Mazaheri a.mazaheri@pgs.razi.ac.ir 180031947532846009482 180031947532846009482 No Department of Civil Engineering, Ph.D Student, Razi University, Taghe Bostan, Kermanshah, Iran