Determination of lateral earth pressure in soils by in situ measurement

The in-situ stress state of a soil plays a key role in the design and construction of many civil engineering projects. In-situ testing methods provide rapid and economical means of estimating the stress state in a variety of soils. The objective of this research was to investigate reliable and accurate means for estimating the lateral stresses in the ground using easily applied in-situ soil testing techniques.; A number of in-situ testing methods used for estimation of the lateral stresses were reviewed. Of these methods, the dilatometer test, the lateral stress sensing cone penetration test, and the stepped blade test were selected for further study due to their simplicity and cost effectiveness. A method for estimating the lateral stress from sleeve friction measured during a CPT was also developed which appeared very promising when evaluated using existing CPT data.; Accurate assessment of the vertical thrust required to push the dilatometer into the ground is essential for making accurate estimates of the lateral stresses from a DMT. The dilatometer used during this research was modified to measure a continuous profile of penetration resistance during a test.; A number of laboratory calibration chamber (CC) tests were performed with the dilatometer and the lateral stress sensing cone penetrometer (LSSCP) on Monterey # 0 and Ticino sands. These tests were used to evaluate the existing correlations and develop new correlations for estimation of the lateral stresses. Data from the LSSCP tests were also used to evaluate further the sleeve friction method for estimating the lateral stresses.; A number of field tests were performed with the dilatometer, the LSSCP, and the stepped blade at various well-documented sites. Data from the field test were used to evaluate the existing and newly developed correlations (from the laboratory CC tests). Suitability, accuracy, reliability and simplicity of the three in-situ methods was also studied.; The method for estimating in-situ lateral stresses from measured sleeve friction gave results of reasonable accuracy in a variety of soil types. The reliability of this method is dependent on the measured sleeve friction and overconsolidation ratio (OCR) of the soil. A method for estimating OCR of cohesive soils from a CPT, as described in this thesis, gave very good results. In cohesionless soils, the LSSCP and DMT were equally accurate and reliable for estimation of in-situ lateral stresses. The LSSCP could be very cost-effective due to the high rate of testing that is possible (i.e. four to five times as compared to a DMT). The stepped blade is more suitable for soft cohesive soils. Use of the blade in stiff soils may result in severe damage to the equipment.