Tunneling in karstic geology confronts numerous challenges due to unpredictable occurrence of voids. The current approach of karstic void risk assessment is qualitative or semi-quantitative and lacks consideration of the spatial variability and distribution of voids. This often influences the pricing strategies, and design and construction activities on tunnel projects. This paper presents a geostatistical modeling-based methodology to develop a quantitative assessment of karstic void risk for a tunnel project in a karstic geological setting. The methodology is applied on an actual mixed-ground tunnel project situated in a karstic geological environment in Malaysia. The geology at the tunnel project site consists of sedimentary rock formations with limestone as the predominant rock type overlain by weak sedimentary residual soils. Pluri-Gaussian simulation (PGS) technique, a stochastic geostatistical-modeling algorithm, is applied to characterize the spatial distribution of voids in 3D along tunnel alignment. Simulations from PGS take into consideration the anisotropic distribution of voids on the tunnel project site. PGS utilizes void data from borehole investigations to model different void sizes (V_s) as categorical variables. The variability in multiple realizations from PGS technique is used to quantify the uncertainty in occurrence probabilities, number, and frequency of karstic voids. The proposed methodology demonstrates the ability to develop probabilistic estimates of occurrence frequency of different void sizes. Probabilistic assessments indicating 95% confidence interval (CI) on number of voids and respective occurrence probabilities are presented. The probabilistic assessment results are applied to estimate the grout quantity required for void treatment, while considering uncertainty in void occurrence. A minimum, mean, and maximum cumulative grout volume of about 2000 m³, 4000 m³, and 8000 m³ (for 95% CI), respectively, is estimated along the alignment.

由于空隙的不可预测性，岩溶地质中的隧道掘进面临着许多挑战。目前的岩溶空隙风险评估方法是定性或半定量的，缺乏对空隙空间变异性和分布的考虑。这通常会影响隧道项目的定价策略以及设计和施工活动。本文提出了一种基于地质统计建模的方法，用于为岩溶地质环境中的隧道项目开发岩溶空隙风险的定量评估。该方法应用于位于马来西亚岩溶地质环境中的实际混合地面隧道项目。隧道工程现场地质为沉积岩层，以石灰岩为主要岩石类型，上覆弱沉积残留土。Pluri-Gaussian 模拟 (PGS) 技术是一种随机地质统计建模算法，用于表征沿隧道路线的 3D 空隙空间分布。PGS 的模拟考虑了隧道项目现场空隙的各向异性分布。PGS 利用钻孔调查中的空隙数据来模拟不同的空隙尺寸（V _s ) 作为分类变量。来自 PGS 技术的多次实现的可变性用于量化岩溶空隙发生概率、数量和频率的不确定性。所提出的方法证明了开发不同空隙尺寸的发生频率的概率估计的能力。给出了表明空洞数量和各自发生概率的 95% 置信区间 (CI) 的概率评估。概率评估结果用于估计空隙处理所需的灌浆量，同时考虑空隙发生的不确定性。最小、平均和最大累积灌浆体积约为 2000 m ³、4000 m ³和 8000 m ³ （对于 95% CI），分别沿比对估计。