Non-destructive SASW evaluation of controlled low strength material as a pipeline bedding material.

摘要

Evaluation of stiffness properties of subsurface soil layers provides vital insight into the performance of a geotechnical entity. Stiffness properties can be determined by both field and laboratory tests. Owing to their advantages over laboratory tests, the field tests are often given priority. non-destructive seismic method Spectral Analysis of Surface Waves (SASW) has been implemented in the current research to investigate the stiffness properties of buried materials.;The SASW technique works on the principle of wave propagation. The surface wave velocity obtained through the test is used to determine the shear modulus, and thus the stiffness, of the geotechnical entity. In this study, the SASW technique has been employed to test the strength of Controlled Low Strength Material (CLSM) over time, with the main objective of assessing the quality of CLSM as a pipeline embedment material. CLSM is a mixture of native soil and water, with cement as an admixture. The main purpose of CLSM is to reduce the project expenses and increase the void filling capacity due its flowable nature. This study is a part of the Integrated Pipeline (IPL) project sponsored by the Tarrant Regional Water District (TRWD).;In order to accomplish this research objective, SASW tests were performed inside the pipeline in the prove-out section. Seventeen test sections were selected along the length of the prove-out section, to perform the SASW tests. The prove-out section extends to a length of 500 ft. The results from these tests were analyzed using WinTFS and WinSASW software. The unconfined compression test was performed on samples obtained from the field. The samples were checked to achieve a target strength of 70 to 150 psi for CLSM after 28 days of casting, as recommended by TRWD for this study. The laboratory tests also included the resonant column test. In order to validate the field SASW results, replicate samples were cast in the laboratory, with the appropriate design mix, to perform the resonant column test. The laboratory resonant column test results were then compared with the field SASW test results for validation of field results This research paves way for future research studies on the SASW technique as an accurate measure for determining the stiffness of geotechnical entities.