CPT-sondering och trycksondering, en jämförande studie om utvärdering av friktionsvinkel i friktionsjord

Sammanfattning: Knowledge of the soils friction angle is necessary to avoid landslides at slope stability surveys and dimensioning for foundation of different constructions. Frictional forces mainly builds up friction soil and the friction angle is defined by the angle when landslides occur. Friction angle can be evaluated using CPT or pressure probe. Both methods are performed similarly, with constant pressure and sink rate, but differ in time, cost, competence requirements and number of measurable parameters. The methods also differ when evaluating the friction angle. For CPT, the Conrad software is used while pressure probe is evaluated with empirical values, set against the peak pressure. This degree project compares the results from performed and evaluated CPT and pressure probes from several drill points in a project. The purpose of the study is to draw conclusions about the soils friction angle, whether the empirically evaluated values of the friction angle by pressure probing, can be correlated with the values of the friction angle through CPT, evaluated with the Conrad software. Both CPT and the evaluation with Conrad are more advanced methods and are therefore seen as the correct value for the soils friction angle. The result shows that pressure probe provides a good indication when evaluating the friction angle and can be used, with the knowledge that the friction angle is rarely evaluated higher than from CPT. The methods differ the most towards the surface to almost correlate towards the depth.