基于特尔菲–理想点法的隧道围岩分类研究

基于理想点法的基本原理,选取岩石单轴饱和抗压强度Rc、岩石质量指标RQD、岩体完整性系数Kv、结构面强度系数Kf、地下水渗水量ω作为评价指标,通过特尔菲科学方法确定其权重系数,建立隧道围岩分类模型,并利用广州抽水蓄能电站第1期工程围岩实测资料进行模型检验。结果表明:特尔菲–理想点法判别结果与实际围岩类别大致相同,且和人工神经网络判别结果、突变级数法判别结果基本符合,从而验证了特尔菲–理想点法用于围岩分类是可行的。最后,运用建立的特尔菲–理想点法围岩分类模型对浙江省诸永高速公路西华岭隧道围岩类别进行判别,经计算分析发现,所选洞段围岩判定结果与设计围岩类别相吻合,进一步证明了该方法用于隧道围岩分类的合理性和有效性。这一方法在西华岭隧道中的成功应用,不仅可以为该隧道设计、施工提供参考,同时对以后同类隧道工程围岩分类有一定的参考价值。

Study on implemention method for optimization design of pile foundation stiffness to reduce differential settlement

The measured data of foundations of high-rise buildings indicate that there are two shortcomings for those pile-box and pile-raft foundations designed by using the traditional design concept. One is disk-shape settlement distribution, which may result in the significant secondary forces in the super structure, and the other is the saddle-shape reaction distribution, which may result in the increase of punch force and moment in foundation slabs. In view of superstructure-soil-foundation interaction effect, the optimization design method for pile foundation and soil stiffness is put forward based on the loads, geological characteristics and superstructure layout by analyzing the field experimental results. The optimization design method adopts strengthening and reducing settlement, coupling hardness with softness, local balances, entirety harmony to realize differential settlement, cap internal force(foundation) and minimized resources consumption. Based on the conceptual design, the analysis of the interaction of superstructure-foundation-pile-soil helps to further optimize pile arrangement and reinforcements in the slab. An engineering case is taken as an example to analyze and interpret the application of strengthening index and avianizing index in the optimization design of pile foundation stiffness to reduce differential settlement.