大型地下洞室极限位移预测与稳定性分析

建立大型地下洞室的随机权重粒子群算法–最小二乘支持向量机(RandWPSO-LSSVM)预测模型，通过实例检验预测模型的可靠性，应用于糯扎渡水电站大型调压井洞室围岩的极限位移预测分析，并与数值计算结果对比分析，综合评价工程区围岩的稳定性。研究结果表明，RandWPSO-LSSVM预测模型所预测的极限位移相对真实值的最大误差为6.72%，误差较小，预测效果较好，满足工程要求；糯扎渡水电站大型调压井地下洞室在设计支护参数情况下数值计算的最大位移为19.45 mm，最大拉应力为0.54 MPa，均分布在五洞交叉口边墙位置，远小于微新风化岩体抗拉强度，塑性区也较少，围岩最大位移小于五洞交叉口边墙位置的极限位移预测值，工程区围岩较稳定；研究结果对提前预估大型地下工程的稳定性具有重要意义，可为合理制订施工决策提供参考。

LIMIT DISPLACEMENT PREDICTION AND STABILITY ANALYSIS OF LARGE UNDERGROUND CAVERNS

A kind of random weight particle swarm optimization(RandWPSO)-least squares support vector machine(LSSVM) prediction model of limit displacement of large underground cavern is established and applied to limit displacement prediction and analysis of large surge shaft of Nuozhadu hydropower station.The reliability of the model is validated by a case study.Through comparing with the results of numerical calculation,the surrounding rock stability of engineering area is evaluated comprehensively.The results show that the maximum relative error of limit displacement obtained by RandWPSO-LSSVM prediction model to the real value is 6.72%.The prediction error is quite less;and the prediction effect is well and meets the engineering requirements.The maximum displacement and tensile stress obtained by numerical calculation under condition of design support parameters are 19.45 mm and 0.54 MPa,respectively,mainly located at the five-tunnel area sidewall.The maximum tensile stress is far less than the tensile strength of little weathering rock mass;and the plastic zone distribution is less.The maximum displacement obtained by numerical calculation is less than the predication value obtained by RandWPSO-LSSVM prediction model.The surrounding rock of engineering area is stable.The results have great significance for estimating the stability of large underground cavern and will provide important guidance for making construction decisions reasonably.