Permeability Characteristics and Foundation Pit Precipitation Measures of Coral Reef Limestone
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摘要: 通过工程地质钻探和压水试验,分析了印度尼西亚东爪哇岛珊瑚礁灰岩的结构特征和透水特性,并通过现场试验,研究了珊瑚礁灰岩地区基坑的止水降水措施。结果表明,该区上部珊瑚礁灰岩按固结程度可划分为灰泥混珊瑚礁钙质结核、碎块状珊瑚礁灰岩和柱状珊瑚礁灰岩。珊瑚礁灰岩的透水率受岩体内部溶孔发育程度及其连通性的控制,透水率与固结程度成反比。灰泥混珊瑚礁钙质结核的透水率为无穷大;碎块状珊瑚礁灰岩的透水率为31~74 Lu,局部地段透水率达到无穷大;柱状珊瑚礁灰岩的透水率为2.25~17 Lu,其随深度的增加而减小。直接抽排降水措施不能有效降低基坑地下水位。压力灌浆止水帷幕通过充填珊瑚礁灰岩内部溶孔从而大大降低珊瑚礁灰岩的透水率,可用于珊瑚礁灰岩地区的基坑降水。Abstract: The structure characteristics and permeability characteristics of coral reef limestone in East Java, Indonesia were analyzed by engineering geological drilling and water pressure test in borehole. And the foundation pit precipitation measures in coral reef limestone area were studied by field test. The results show that the upper part of the coral reef limestone in this area can be divided into plaster mixed with calcareous concretion of coral reef, fragmented coral reef limestone and columnar coral reef limestone according to the consolidation degree. The permeability rate of coral reef limestone is controlled by the degree development of the dissolved cave inside the rock mass and its connectivity, and the permeability rate of coral reef limestone is inversely proportional to the consolidation degree. The permeability rate of the plaster mixed with calcareous concretion of coral reef is infinite. The permeability rate of fragmented coral reef limestone is 31~74 Lu, and in the local area is infinite. The permeability rate of columnar coral reef limestone is 2.25~17 Lu, which decreases with increasing depth. The direct pumping and drainage measures can not effectively decrease the groundwater level of the foundation pit. The pressure grouting water-resisting curtain can greatly reduce the permeability rate of the coral reef limestone by filling the dissolved caves inside the rock mass, and can be used for the foundation pit dewatering in the coral reef limestone area.
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