Effect of cyclic loading parameters on post-cyclic pullout resistance of soil nail

Abstract:

Pullout resistance of cement-grouted soil nails is a key factor affecting the safety conditions of retaining walls, slopes and excavations. Hence, survey of resistence of pullout nail is the one of the most important parameters in designing of nailing functions. This parameter depend on critical factors including: instalation method, overburden press, grouting pressure, degree of saturation of the soil, the roughness of nail surface, changes of lengh & diameter of nail, the shear strengh of the soil and etc.

Sometimes, used soil nail layers affected by cyclic loads due of traffic passing, train and so on. Hence the research aimed to study influence of this kind loadings on resistence of nail post-cyclic pullout and affective factors on it. The study pointed to apply slopes and nailed retaining walls next to traffic loads and rail-roads. Several studies conducted; according to, vary factors influence on nail pullout behavior that buried into soil. Key studies carried out in form of impression of static loading on nail pullout resistance including: overburden stress, grouting stress, impression of an addition to grouting, nail geometry, nail spaces, using spiral nails, comparison laboratory results of pullout set with direct shear test in interface grouted-nail to earn identical ratio and etc. yet, it not examineted cyclic loading impression on post-cyclic pullout resistance in nails. The study just focus on geogrid. For the first time, this research provide impression of cyclic loading on post-cyclic pullout resistance in nails.

This research used nail pullout set; able to apply static and cyclic loads in conditions of force or displacement controling with differ frequencies and sinus shape of cyclic wave. This search used the notes of specifications of pullout set; also, sampling due to test and tables of done tests. In this research examined affection of variation of static, cyclic load rate. Resistance of post-cyclic pullout nail generally is more to static pullout resistance; even though , more affections of cyclic loading lead to decrease of resistance; also, obserued in the cyclic part developing in displacement.
Key words : pullout resistance , soil nail , post-cyclic , static and cyclic load