摘要
研究目的:由于地质条件的千变万化、施工水平的差别、支护参数的不同,即使围岩条件相同,围岩压力在时空上也具有变异性,导致实际围岩压力难以确定,而采用总安全系数法设计时,仅需要寻找围岩压力的最不利情况。为此,提出深埋隧道采用围岩压力代表值作为设计支护力的理念,并对其计算方法与合理性展开研究。研究结论:(1)采用"围岩压力代表值"作为设计支护力,为解决安全系数设计法中实际围岩压力难以确定的问题提供了思路;(2)当埋深不小于10～15倍洞径时,建议采用无支护状态下隧道(等效为当量圆)顶部45°位置处塑性区边界至开挖轮廓线范围内的围岩自重作为围岩压力代表值;当埋深小于10～15倍洞径时,可取弹塑性有限元计算的拱部90°范围内的平均塑性区自重作为围岩压力代表值,该计算结果具有合理的安全性与经济性;(3)当软弱围岩的两端为较好围岩时,荷载具有空间效应,导致围岩压力代表值低于理论计算值,具体折减值与隧道洞径、软弱围岩的长度等因素有关,超前注浆加固圈具有明显的承载作用,可以显著降低围岩压力代表值;(4)本研究结果可为完善隧道支护结构的量化设计方法提供思路。
Research purposes: Because of the ever-changing geological conditions,different construction levels and different support parameters,even if the surrounding rock conditions are the same,the surrounding rock pressure has variability in time and space,which makes it difficult to determine the actual surrounding rock pressure. When using the total safety factor method to design,only the most disadvantageous situation of surrounding rock pressure needs to be found. Therefore,the idea of using the representative value of surrounding rock pressure as the design support force for deep-buried tunnels is put forward,and its calculation method and rationality are studied.Research conclusions:( 1) Adopting ' representative value of surrounding rock pressure ' as design support force provides a way to solve the problem that the actual surrounding rock pressure in safety factor design method is difficult to determine.( 2) When the buried depth is greater than or equal to 10 ~ 15 hole diameter,it is suggested that the weight of surrounding rock of plastic zone at 45 degrees of the tunnel without support can be taken as the representative value pressure;When less than 10 ~ 15 diameter,the weight of the average plastic zone within 90°of arch calculated by elastic-plastic finite element method can be taken as the representative value of surrounding rock pressure. The calculated results are reasonable in safety and economy.( 3) When the weak surrounding rock is clamped by the better surroundingrock on both sides,the surrounding rock pressure has spatial effect. The actual representative value of surrounding rock pressure is lower than the theoretical value. The reduction value is related to the tunnel diameter,the length of weak surrounding rock and other factors. In addition,the advance grouting reinforcement ring has obvious bearing effect,which can significantly reduce the representative value of surrounding rock pressure.( 4) The research results can provide ideas for improving the quantitative design method of tunnel support
作者
肖明清
徐晨
XIAO Mingqing;XU Chen(China Railway Siyuan Survey and Design Group Co.Ltd,Wuhan,Hubei 430063,China)
出处
《铁道工程学报》
EI
北大核心
2019年第2期64-69,共6页
Journal of Railway Engineering Society
关键词
安全系数法
围岩压力
荷载空间效应
注浆加固
最小支护力
safety factor method
surrounding rock pressure
load spatial effect
grouting reinforcement
minimum supporting force
