Field instrumentation, monitoring of drilled shafts for landslide stabilization and development of pertinent design method

"Prepared in cooperation with the Ohio Department of transportation and the U.S. Department of Transportation, Federal Highway Administration."; "November 2010."; "FHWA/OH-2010/15"--Technical rept. documentation p.; Includes bibliographical references (p. 215-224).; Sponsored by Ohio Dept. of Transportation; State job no.: 134238; Harvested from the web on 1/27/11A user's manual for UA SLOPE Program. Version 2.1 (Nov. 2010).The design method for using a single row, spaced drilled shafts, socketed into a firm rock strata, to stabilize an unstable slope has been developed in this research. The soil arching due to the presence of spaced drilled shafts in a slope was observed in 3-dimensional finite element simulations and field monitoring data. A comprehensive 3-D finite element parametric study was used to derive an empirical equation to quantify the arching induced load transfer. A limiting equilibrium based slope stability analysis method, incorporating the arching effect, was developed and coded into a PC based program UA SLOPE 2.1, to allow for analysis of the factor of safety of the shaft/slope system and the earth thrust on the drilled shaft. The developed analysis and design method was validated based on more than 40 cases of 3-dimensional finite element simulations, covering a wide range of slope geometry, soil strength parameters, and the drilled shaft diameter, spacing, and location conditions. Three slope stabilization projects in Ohio involving the use of drilled shafts were monitored with instrumentations to obtain a 3-year performance data of the stabilized slope and to validate the design based on the developed method. In addition, a field testing program at the ATH-124 Project site was conducted to quantify arching during several stages of surcharge load induced slope movements. The developed UA SLOPE 2.1 program was verified by comparisons with the calibrated finite element simulation results of this field surcharge loading condition. The UA SLOPE 2.1 program is recommended for use in finding an optimized design (i.e., location, diameter, and spacing) of the drilled shafts to stabilize an unstable slope