摘要:

In situ porosity and permeability were measured on Great Bahama Bank sediments using electrical conductivity and permeability probes. Core samples were recovered at the probe measurement sites for laboratory determinations of porosity and permeability. Penetration depths of cores and probes were approximately 2.5 m subbottom.

ISSN:0360-8867    

DOI:10.1080/10641199009388227

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Selected oölitic sediments from the Great Bahama Bank were studied to assess (1) the role of microfabric in determining porosity and permeability, and (2) particle packing relationships, i. e., grain support versus matrix support. Scanning electron microscopy and light microscopy revealed that the sediment consists of oöids, which are the major constituents of the sand‐size fraction, supported by a matrix composed predominantly of aragonite needles. The supporting matrix of aragonite needle clusters, which constitutes only about 10–20% of the total sediment dry weight, is the microstructural characteristic that increases the porosity and lowers the wet bulk density compared to a grain‐supported microfabric characteristic of clean sands. The presence of a fine‐grained matrix reduces the permeability of these sediments relative to clean sands.

ISSN:0360-8867    

DOI:10.1080/10641199009388228

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

During the past 20 years, a major challenge facing the Chinese offshore engineering community has been evaluating the feasibility of using gravity base platforms on extremely weak soils frequently encountered along the coast of China. Such structures are not well suited for weak soils because the foundation generally provides both inadequate vertical bearing capacity and horizontal sliding stability.

ISSN:0360-8867    

DOI:10.1080/10641199009388229

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The application of a new criterion to compute the axial capacity of pipe piles driven into sands is described for offshore conditions. The new criterion is tested, independently, against measured capacities from 64 pile load tests and is compared with current recommended practice of API RP2A. These comparisons show that the new criterion is more reliable than the current API criterion and that the new criterion can provide greater capacities for long, large‐diameter pipe piles used in the marine environment. Topics also discussed include (1) the use of limiting values for unit shaft resistance and unit end bearing, (2) computing the capacity of piles in layered soil profiles, (3) the soil plug resistance in overcoming end bearing resistance, and (4) the influence of rate of loading and cyclic loading on pile capacity. A few examples are included to demonstrate the applications.

ISSN:0360-8867    

DOI:10.1080/10641199009388230

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0360-8867    

DOI:10.1080/10641199009388226

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor