东南亚礁灰岩的工程特性

Engineering properties of reef calcareous rock in Southeast Asia

东南亚地区所属的热带环境,有利于珊瑚礁灰岩的形成,而这类礁灰岩由于沉积年代新,具有较特殊的岩体结构特征和工程地质特性。本文结合印度尼西亚东爪哇岛上的实际工程,探讨了珊瑚礁灰岩的基本工程性质。电镜扫描和矿物分析表明,发育于浅海环境的礁灰岩,成岩作用弱,导致了礁灰岩具有较大的孔隙率和疏松的结构,进而控制了礁灰岩的力学特性。通过室内力学试验、钻孔波速试验和标准贯入试验等原位试验得出:礁灰岩属于典型的软岩,其标贯锤击数不符合正态分布的特点,且离散性很大;剪切波波速远小于一般岩石,压缩波与剪切波波速的比值小于2.0,突出了礁灰岩结构疏松的特点;由于发育大量孔隙和小空洞,钻孔压水试验表明礁灰岩具有较大的渗透性和连通性,其水文地质特性也与一般岩石差异较大。

Coral reef calcareous rock which deposits in neritic environment is widespread in tropical ocean area. It is of the special structure and engineering characteristics because of sedimentary environment and its short depositional history. Depended on an actual project in East Java in Indonesia,the basic engineering properties of coral reef rock are discussed. The results of electronic microscope scanning and mineral analysis show that the weak diagenesis of calcareous rock results in large porosity and loose structure and controls the mechanical behavior of the rock. The laboratory tests and in-situ tests indicate that the reef calcareous rock belongs to very soft rock,and the SPT blow counts with non-normal distribution of the rock have wide fluctuation range. The shear wave in the reef rock is much slower than it travels in hard rocks,and the ratio of compression wave speed and shear wave speed close to 2. 0,all the phenomena of seismic wave is clear that the calcareous rock has a loose structure. The hydrogeological characteristics of the calcareous rock with high permeability and well connectivity much differ from that of other rocks due to plenty of pore.