To study shearing properties of rubbles used for rubble-mound foundations peculiar to port and harbour facilities, filed survey and laboratory tests were carried out. As filed survey, grading and shape properties of rubbles produced in representative four quarries were investigated, laboratory tests are triaxial compression tests with large scale specimen (30cmD×60cmH or 120cmD×240cmH) and compaction tests. Test materials are seven kinds of crushed stone which have the grading similar to rubbles and maximum grain size of 2.55cm to 20cm.
　Main results are as follows:
1. Rubbles have poor grading and uniformity coefficient is 1.3 to 2.5.
2. By the test results of crushed stones, the characteristics of rubbles under shearing can be estimated.
3. These characteristics are due to particle breakage caused by poor grading.