In-situ strength of seafloor soil determined from tests on partially disturbed cores / by H.J. Lee.

Abstract

The major obstacle to rational design of seafloor foundations and anchors has been a lack of good quality information on the bottom sediment engineering properties. Considerable engineering property data have been obtained through laboratory testing of core samples, but most of these data are of questionable validity because of the sample disturbance factor. To improve the usability and credibility of laboratory test data, an experimental investigation was undertaken to determine the extent of disturbance involved in seafloor soil sampling and handling. In-situ tests were performed and related to comparable laboratory tests. The soils tested were from the Santa Barbara Channel with a terrigenous (land-derived) origin. A technique based on earlier work was developed for predicting in-situ shear strength on the basis of laboratory test results. Various disturbance mechanisms including sampling, vibration, long-term nonref rigerated storage, and water and air expansion were investigated and analyzed quantitatively. Strength reductions varying between 15 and 50 percent were observed to result from these disturbances. The in-situ strength prediction procedure appears to be capable of compensating for all forms of disturbance except for those developing as a result of gas expansion.

Induced scattering and two-photon absorption of Alfvén waves with arbitrary propagation angles

“…For the opposite relation one-dimensional results [2][3][4][5] and results [6,7] are valid. The results of this papers can be readily obtained if one let B zk = 0 in Eq.…”

“…Here β is the square of the ratio of thermal ion velocity v T i = T i /m i (T i -is ion temperature in energetic units, m i is ion mass) and Alfvén velocity v a = B 0 / √ 4πρ 0 (B 0 is the mean magnetic field strength, ρ 0 is the mean plasma density). In papers [2][3][4][5] the case of wave propagation along mean magnetic field was considered. At last in papers [6,7] the oblique propagation of Alfvén waves was considered but random magnetic field component along mean magnetic field arising from magnetic pressure of Alfvén waves was not taking into account.…”

“…It is well known now that the main nonlinear processes for such waves are induced scattering and two quantum absorption by thermal ions. Corresponding damping rates were calculated by many authors [1][2][3][4][5][6][7]. Nevertheless totally comprehensive study is absent now.…”

Geotechnical properties of deep continental margin soils

“…Various aspects of sample disturbance have been extensively reported and discussed in the literature (see Hvorslev, 1949;Emrich, 1971;and Lee, 1973a). This section provides a very brief outline of the possible causes of sample disturbance in DSDP cores.…”

“…Long-term storage can cause creep mechanisms to operate in the sample. Vibrations in the sample storage area may accelerate this response (Lee, 1973a).…”