MICRO-STRUCTURES AND THE FUNDAMENTAL ENGINEERING PROPERTIES OF THE BEACH CALCARENITE IN SOUTH CHINA SEA
ZHU Changqi1，2，ZHOU Bin2，3，LIU Haifeng2
(1. Faculty of Engineering，China University of Geosciences，Wuhan，Hubei 430074，China；2. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China；3. General Contraction Company of CCTEB，Wuhan，Hubei 430064，China )
Abstract：The beach calcarenite is a sedimentary rock deposited at tidal beaches of coral reefs in South China Sea. It is consisted of coral sands that predominantly cemented by the carbonite calcium materials under tropical or sub-tropical marine environments. The beach calcarenites are also deposited in some of the coastal areas in Southern China. The research on the geotechnical engineering properties of beach calcarenites has a significant theoretical and practical impact on the safeguarding of our marine sovereignty and the development of defense facilities in the area. This paper studies beach calcarenite samples that collected from different locations in the South China Sea and the coastal area by using both micro and marco structure study measures. The objective of these studies is to establish the major parameters that control the mechanical strength of the beach calcarenite as well as to provide necessary theoretical guidelines for the further researches. The results indicate that，the beach calcarenite is characterized by the low unit weight，high porosity，and large permeability. The degree of cementation of the beach calcarenite is in between weak and medium. The measured uniaxial compressive strength under the air-dry condition varies from 2.02 to 19.39 MPa. It is evident that the saturation of beach calcarenite samples will reduce its uniaxial compressive strength with a softening coefficient varying from 0.45 and 0.96. In general，a smaller softening coefficient in the beach calcarenite sample correlates with a weak cementation. The tested tensile strength of beach calcarenite samples under the air-dry condition is between 0.62 and 2.52 MPa with a ratio of compressive to tensile strength varying from 3.08 and 9.14. The range of compressive to tensile strength of beach calcarenite samples is lower than that of rock samples from land origin，which is between 8 and 12. The differences in the compressive to tensile strength ratio might reflect the differences in the sedimentary conditions of different rock samples. The correlation analyses of parameters indicate that the unit weight and the cementation are major parameters affecting the compressive strength of beach calcarenite samples. Stronger cementation in samples results in a higher strength. Both porosity and grain size in samples are secondary parameters with an insignificant effect on the compressive strength of the beach calcarenite.
朱长歧1，2，周 斌2，3，刘海峰2. 南海海滩岩的细观结构及其基本物理力学性质研究[J]. 岩石力学与工程学报, 2015, 34(04): 683-693.
ZHU Changqi1，2，ZHOU Bin2，3，LIU Haifeng2. MICRO-STRUCTURES AND THE FUNDAMENTAL ENGINEERING PROPERTIES OF THE BEACH CALCARENITE IN SOUTH CHINA SEA. , 2015, 34(04): 683-693.
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2015, Vol. 34 
