Kuala Lumpur limestone formation exhibits karstic features with irregular bedrock profiles and variable weathering condition. The Klang Valley Mass Rapid Transit project is the first Mass Rapid Transit project in Malaysia. The Cochrane station is one of the underground stations with maximum excavation depth of 32m below ground and it is located in Kuala Lumpur limestone formation. This station also serves as launching shaft for the tunnel boring machine from both ends of the station. A cost effective earth retaining system deemed suitable for the geological formation was adopted using secant pile wall supported by temporary ground anchors. High ground water table is also a concern. Rock grouting was carried out to prevent water ingress into excavation pit as well as excessive ground settlement and occurrences of sinkholes surrounding the excavation area due to groundwater drawdown. Vertical rock excavation adjacent to the secant pile wall involving rock slope strengthening works, surface protection, controlled blasting and vibration control was successfully designed and implemented. This paper presents the design of the secant pile wall together with vertical rock excavation to the final depth of the station in karstic limestone formation. The unique experience (design and construction) gained from this project will be useful reference for similar excavation works, especially in mature karstic limestone.
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机译：吉隆坡石灰岩形成展示具有不规则基岩型材和可变风化条件的岩溶特征。 Klang Valley Mass Rapid Transit项目是马来西亚第一个大众迅速运输项目。 Cochrane站是地下站之一，最大挖掘深度为32米以下，它位于吉隆坡石灰石形成。该电台还可用于从站的两端的隧道镗床发射轴。采用由临时接地锚固件支撑的割线桩壁采用适用于地质地层的成本有效的地球挡土系统。高地水位表也是一个问题。进行岩石灌浆，以防止水进入挖掘坑以及由于地下水拔出而围绕挖掘区域的过度地沉降和污水孔的发生。垂直岩石挖掘与涉及岩石坡度强化作品，表面保护，控制爆破和振动控制的近距离割岩壁相邻。本文介绍了透明岩壁的设计与垂直岩石挖掘到岩溶石灰石形成中的最终深度。从该项目中获得的独特体验（设计和施工）将有用的类似挖掘工作的参考，特别是在成熟的岩溶石灰岩中。
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