A large diameter sampler was developed to take undisturbed samples from not only soft ground but also sandy and weathered ground. The large diameter sampler developed in Korea Institute of Construction Technology (KICT-type large diameter sampler) was manufactured based on the principle of triple core barrel sampling. A specially designed cutting device was used to cut and contain various kinds of samples in the sampler during a sampling and retrieval procedure. By adjusting the stiffness of the spring located at the top of the sampler, the distance between the cutting shoe and auger can be controlled in accordance with the ground condition. In order to investigate the applicability of the developed sampler and compare the quality of the samples taken by the sampler with that by the traditional thin-walled tube sampler, samples were taken at various sites according to the ground condition. And a series of laboratory tests such as the unconfined compression test, triaxial compression test, oedometer test, large diameter Rowe cell consolidation test (D:150 mm) and resonant column test were performed. The test results showed that the samples by the KICT-type large diameter sampler show higher quality than the samples by the thin-walled tube sampler. And the validity and applicability of the developed KICT-type large diameter sampler was confirmed accordingly.
Recently, due to rapid industrial development, it is hard to construct various facilities only in sound ground. So the number of constructions in very complicated conditions at a reclamation site, landfill site, weathered rock, and also near the downtown area has been increasing. To investigate the ground characteristics, accurate site investigation techniques are needed because they are directly related to the success of the construction. To investigate soil properties, in situ tests and laboratory tests are used. Generally, in situ tests show relatively good and conservative results than laboratory tests, but in some medium plasticity clay, it shows opposite behavior (Long, 2006).