THE STRUCTURE AND STRENGTH OF 1ST-YEAR ICE RIDGES IN THE BALTIC SEA

被引:95
作者
LEPPARANTA, M
HAKALA, R
机构
[1] TECH RES CTR FINLAND,STRUCT ENGN LAB,SF-02150 ESPOO,FINLAND
[2] MINIST ENVIRONM,SF-00121 HELSINKI,FINLAND
基金
芬兰科学院;
关键词
D O I
10.1016/0165-232X(92)90036-T
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
Sea ice ridges are typical features in the Baltic Sea ice pack accounting for on average up to one-third of the total ice mass. They are difficult obstacles to winter navigation and cause large forces on ships and offshore structures. However, the internal structure and strength properties of ice ridges are quite poorly known. This paper presents the results of an experimental project on the structure and strength of first-year ice ridges in the Baltic Sea carried through during 1987-1989. Altogether, six freely floating ridges were investigated. Their total thickness ranges from 4 to 17 m. Valuable field data about the size and shape of ridges, consolidated and unconsolidated parts, block size and porosity have been obtained by drilling and sampling. Divers and underwater video cameras have been used for observing the ridge keel structure. The totally consolidated layer within the ridges was 1-2 times the thickness of the surrounding level ice. The average porosity was 29%. The strength of the keel part has been measured with a full scale loading test. The force required to shear the keel was determined as a function of the normal force, the settlement rate, and the porosity of the keel. The shear strength of the ridge keels was from 1.7 up to more than 4.0 kPa. Also small scale tests were conducted in an ice tank giving results in agreement with the full scale tests.
引用
收藏
页码:295 / 311
页数:17
相关论文
共 30 条
[1]  
COX GFN, 1985, P C ARCT 85 ASCE SAN, P476
[2]  
CROASDALE KR, 1990, 10TH P IAHR S IC ESP, V1, P153
[3]  
Fransson L., 1985, P 8 INT C PORT OC EN, P75
[4]  
HAKALA R, 1988, UTFORSKNING OVER ISK
[5]  
HNATIUK J, 1978, J GLACIOL, V20, P519
[6]  
HOPKINS MA, 1989, 8TH P INT C OFFSH ME, V4, P175
[7]  
KANKAANPAA P, 1991, THESIS U HELSINKI HE
[8]  
Kankaanpaa P., 1988, GEOPHYSICA, V24, P15
[9]  
Kankaanpaa P., 1989, P 10 INT C PORT OC E, V1, P87
[10]  
KEINONEN A, 1977, 22 BOARD NAV WINT NA