Development of In-situ Testing Equipment for Friction Between Ground and Structure Foundation

Research Project

Project/Area Number	62850104
Research Category	Grant-in-Aid for Developmental Scientific Research
Allocation Type	Single-year Grants
Research Field	Building structures/materials
Research Institution	Tokyo Institute of Technology
Principal Investigator	KISHIDA Hideaki Tokyo Institute of Technology, Professor, 大学院総合理工学研究科, 教授 (30016513)
Co-Investigator(Kenkyū-buntansha)	UESUGI Morimichi Tokyo Institute of Technology, Research Associate, 大学院総合理工学研究科, 助手 (20151780) KAKURAI Masaaki Takenaka Technical Research Laboratory, Senior Research Staff, 技術研究所, 主任研究員
Project Period (FY)	1987 – 1988
Project Status	Completed (Fiscal Year 1988)
Budget Amount *help	¥5,500,000 (Direct Cost: ¥5,500,000) Fiscal Year 1988: ¥1,400,000 (Direct Cost: ¥1,400,000) Fiscal Year 1987: ¥4,100,000 (Direct Cost: ¥4,100,000)
Keywords	Pile / Earth Anchor / Soil / Foundation / Friction / 原位置試験
Research Abstract	In the present design of piles and earth anchors, the estimation of frictional resistance is dependent on the loading test and/or empiricism with a considerable uncertainty. For better understanding and estimation of frictional resistance, a testing apparatus is developed for the measurement of in-situ friction and normal stress. 1. Studies on friction between soils and construction materials are reviewed. These studies often use the frictional resistance as the ratio of the shear stress to the normal stress acting on the interface. It is necessary to estimate the normal stress for appropriate use of the results of these studies. 2. Experimental studies on the in-situ tests are reviewed. Most apparatus developed in the experimental studies are either to measure the in-situ lateral stress or frictional resistance between ground and the apparatus. It is rare to measure both lateral stress and frictional resistance with one apparatus. The theoretical studies have not yet succeeded to evaluate the accurate lateral stress acting on installed pile surface. 3. A new apparatus is designed and fabricated to measure both frictional resistance and lateral stress at the same time. The design was based on the piezo-cone penetrometer which measure tip resistance, local side friction and pore water pressure at the same time. One part of the friction sleeve was machined from the inside to a wall thickness of some 0.3mm. The bending strain was mesured by means of electric resistance strain gauges bonded to the inside of the thin part of the friction sleeve. The measured values were calibrated under the compressive load and hydraulic pressure. 4. Laboratory tests were carried out in large sand samples with controlled density under imposed boundary (lateral and overburden) pressure. The test results showed that the new apparatus is capable of measuring the lateral and frictional resistance at the same time.