The point load test for weak rock in dredging applications

Abstract The point load test is shown useful for weak/saturated rocks which are commonly encountered in mechanical dredging operation. To support the dredging use of the point load test, orginally intended to obtain a field strenth index for hard rock materials, a comparative, testing program was initiated, which included more than four hundred rock tests. The resulting data base system provides test a summary of test data and comparison calculations. The data base contains point load and unconfined compressive strength tests and some wet versus dry strength comparison tests. Applicability of the point load test was shown for the weak rock materials typical of many coastal deposits. A correlation with unconfined compressive strength was demonstrated for several dredge sites, and for a low-strength rock simulant. However, correlation factors were consistently much lower than the generalized, or target average, values cited in testing standards, which are consistent with results in hard rock tunneling and mining applications.