Lagoon berms in western Alaska are difficult to design and build due to limited resources, high cost of construction and materials, and warm permafrost conditions. This paper explores methods to treat locally availabl...Lagoon berms in western Alaska are difficult to design and build due to limited resources, high cost of construction and materials, and warm permafrost conditions. This paper explores methods to treat locally available frozen materials and use them for berm construction. The goal is to find an optimized mix ratio for cement and additives that can be effective in increasing the strength and decreasing the thaw settlement of an ice-rich frozen silty soil. Soil of similar type and ice content to the permafrost found at a project site in Eek, Alaska is prepared in a cold room. The frozen soil is pulverized and cement, additives and fibers are added to the samples for enhancing shear strength and controlling thaw settlement. Thaw settlement and direct shear tests are performed to assess strength and settlement characteristics. This paper presents a sample preparation method, data from thaw settlement and direct shear tests, and analyses of the test results and preliminary conclusions.展开更多
The set-net fi shery resources in Haizhou Bay,China have been over-exploited because of over-fi shing and environmental deterioration.To better understand the current situations and the development trends of fi shery ...The set-net fi shery resources in Haizhou Bay,China have been over-exploited because of over-fi shing and environmental deterioration.To better understand the current situations and the development trends of fi shery resources,the temporal change of biological characteristics and community compositions were analyzed from 2011 to 2018.Meanwhile,we evaluated the impact of the summer moratorium of marine fi shing(SMMF)on the set-net fi shery.Results show that the mean total length of the six principal species showed varying degrees of decreasing trends,while the changing patterns for the mean weight proportion of the six groups varied.For the whole communities,the similarities of the inter-annual community diversities and compositions were high.SMMF is meaningful to help reproductive success and support recruitment.Every year,the catch per unit eff orts of the six principal species after SMMF were signifi cantly higher than before SMMF except for Octopus ocellatus.The target groups showed a higher mean weight proportion after SMMF than before SMMF in eight years,while the non-target groups were converse.Therefore,the resources of the set-net fi shery are changing in the study periods;and SMMF is an important factor infl uencing biological characteristics and community structure.Despite some challenges,SMMF is still one of the most appropriate policy tools to protect the set-net fi shery resources under the reality of China.展开更多
文摘Lagoon berms in western Alaska are difficult to design and build due to limited resources, high cost of construction and materials, and warm permafrost conditions. This paper explores methods to treat locally available frozen materials and use them for berm construction. The goal is to find an optimized mix ratio for cement and additives that can be effective in increasing the strength and decreasing the thaw settlement of an ice-rich frozen silty soil. Soil of similar type and ice content to the permafrost found at a project site in Eek, Alaska is prepared in a cold room. The frozen soil is pulverized and cement, additives and fibers are added to the samples for enhancing shear strength and controlling thaw settlement. Thaw settlement and direct shear tests are performed to assess strength and settlement characteristics. This paper presents a sample preparation method, data from thaw settlement and direct shear tests, and analyses of the test results and preliminary conclusions.
基金Supported by the Argo-Scientifi c Research in the Public Interest,China(No.201203018)。
文摘The set-net fi shery resources in Haizhou Bay,China have been over-exploited because of over-fi shing and environmental deterioration.To better understand the current situations and the development trends of fi shery resources,the temporal change of biological characteristics and community compositions were analyzed from 2011 to 2018.Meanwhile,we evaluated the impact of the summer moratorium of marine fi shing(SMMF)on the set-net fi shery.Results show that the mean total length of the six principal species showed varying degrees of decreasing trends,while the changing patterns for the mean weight proportion of the six groups varied.For the whole communities,the similarities of the inter-annual community diversities and compositions were high.SMMF is meaningful to help reproductive success and support recruitment.Every year,the catch per unit eff orts of the six principal species after SMMF were signifi cantly higher than before SMMF except for Octopus ocellatus.The target groups showed a higher mean weight proportion after SMMF than before SMMF in eight years,while the non-target groups were converse.Therefore,the resources of the set-net fi shery are changing in the study periods;and SMMF is an important factor infl uencing biological characteristics and community structure.Despite some challenges,SMMF is still one of the most appropriate policy tools to protect the set-net fi shery resources under the reality of China.
