On use of CPT data for pile analysis under horizontal load

Abstract

Method of coefficient of subgrade reaction evaluation by CPT data is described in the article. To work out the method, experimental field investigations were carried out. At the first step, results of the parallel coupled soil tests with CPT and standard stamp according to GOST 19912-2011 and 20276 -1999 were obtained. After processing the experimental data obtained, the correlation design formula is offered to determine the modulus of the total linear soil strain, this formula is the basis for coefficient of subgrade reaction evaluation. At the second step, field investigations at three sites composed of dispersed cohesive soils were carried out. The paper presents results of pile horizontal load test and results of soil CPT – the values of soil resistance under the cone end along the whole depth of pile penetration. The experimental data obtained allowed diagrams plotting by which the ultimate horizontal load could be determined in dependence upon depth of pile penetration and averaged value of resistance under the cone end. While diagrams plotting, method of extrapolation of data obtained when 8 and 12 meter length pile horizontal load test was used. Parabolic dependences of the pile ultimate horizontal load upon its length and soil resistance value under the cone end while CPT are shown. The above parabolic dependences were straitened to obtain the design linear dependences and the overall chart for the interval of plasticity of dispersed cohesive soils: “tough – very soft consistency”. The offered method of analysis of the pile ultimate resistance under horizontal load allows obtaining results without labor-intensive, long-term and expensive CPT.