某水电站地下洞室随机块体稳定性评价及系统锚固设计

地下洞室中的随机块体是指由岩体中的随机节理或者基体裂隙构成的不确定性块体 ,在已建的地下厂房中 ,这类块体大量存在 ,这类块体的稳定性会对洞室的施工安全造成较大的影响。在设计中这类块体常常是通过系统锚杆进行加固 ,但由于块体位置随机性和几何特征的不确定性 ,使得系统锚杆的长度和间距很难确定。本文以某水电站的地下洞室为研究对象 ,在深入了解地质条件、岩体结构特点的基础上 ,找出可能构成随机节理的分布规律 ,再分析节理与节理、节理和Ⅰ、Ⅱ类确定性结构面可能的组合 ,得到可能的随机块体 ,然后采用块体理论评价其稳定性 ,得到随机块体的几何特征和稳定状况 ,总结出最优的锚杆长度 ,为地下洞室的系统锚杆长度的确定提供了理论依据

STABILITY EVALUATION OF RANDOM BLOCKS AND DESIGN OF SYSTEMATIC ANCHORING FOR THE UNDERGROUND CAVERNS IN A HYDROPOWER STATION

Random blocks in underground tunnels are those uncertain blocks cut by random joints or fractures in bedrock, which have been observed in many existing underground factory buildings. Designers often reinforce these blocks by using systematic anchors, of which length and space are difficult to determine because of the randomness of the block’s position and the indeterminacy of the block’s geometry. This paper presents a case study in a hydropower station to demonstrate distribution patterns of the random joints based on geological conditions and rock structure of the underground caverns. Potential random blocks are then defined by combining different sets of joints, or by combining joints with the Type I and II structural planes. Stabilities of the random blocks are eventually evaluated using the block theory. Finally, the optimal anchor length can be determined as part of the design of the systematic anchors.