THE LOAD-SETTLEMENT CHARACTERISTICS OF PFLE GROUP UNDER VERTICAL AND HORIZONTAL, CYCLIC LOADS

Abstract

The s-cu~ay dis cuss eS 'the load-s e tlemcnt characteristics of Single pile andd vertical pile groun under constant vertical and cyclic lateral load carried thrcugh the model study in c oh es i cn l es s Soil. • A brief review c.f literature cn s ingla and vertical pile group is under different conditions of load pres en ted, A review of literature reveals that studies on pile foundations with vertical and cyclic lateral load have not been investiqa- ted in the past. Thc_.ugh this a problem cf greater practical importance as pile foundations are always subjected to vertical load from superstructure whereas cyclic lateral load act due tc wind or other forces. The experimental study has been carried out us inq 1.2 cms diameter aluminium roods with f0' tip. Piles 60 cros long with 58 cros embedded length_ are us ed. Tests have been carried out in coh es ionless soil with a relative density ` 65x. Singlepile and vertical pile group of four piles at a spacir4q of three times diameter have been tested. A special cam arranqexnent has been us ed to apply cyclic loads in single steps. Records of vertical displacements, horizontal displacrnents and rotations have been taken during the tests. Pile foundations have been subjected to cyclic loads up'Lo 5GG cycles. Various combinations of vertical load and cyclic horizontal loads have been used in the investigation. The test result indicates that: (a) The vertical s ettl anent of single pile and pile group increases with the increase in vertical load even if cyclic lateral load is constant. (b) For the same number of cycles and constant load the magnitude of horizontal displacement c-f single pile and pile group increases with the increase in the applied horizontal_ load. (c) The effect of cyclic loading is to increase the verti- cal displacement, horizontal displacement and rotation of the single pile and pile= group at a faster rate uptc about 100 cycles beyond which the increase is linear and at a slow rate.