西安建筑科技大学学报(自然科学版)

为探明高地应力软岩隧道在不同开挖工法下洞周塑性变形和应力重分布的响应特征以及地质强度参数对开挖变形的影响机制,寻求不同围岩等级下合理的开挖工法体系以及最佳支护时机,利用数值分析手段,对四种工法下的围岩应力、塑性区分布及变形失稳展开分析研究.结果表明:(1)对于软弱围岩,采用CRD法和三台阶临时仰拱法能够有效控制围岩变形、应力和塑性区的发展,尤其是对拱脚位移的控制效果突出明显,三台阶法和环形预留核心土法开挖后将在拱脚处产生较大的收敛变形;(2)采用临时支撑将在支撑及拱脚位置产生明显的应力集中,实际过程中应加强对此位置的保护,设置锁脚锚杆或补强注浆提高其强度承载力;(3)开挖后过早支护没有充分发挥围岩自承能力,支护不及时围岩内出现松动压力使围岩进入流变状态,软弱Ⅴ级围岩合理支护时间段应在开挖后荷载释放10%～30%内;(4)拱腰水平收敛整体随侧压力系数的增加而增大,但当K为0.5时,拱腰水平位移有从向内收敛迅速向外扩张的趋势; 拱顶以上围岩竖向沉降随侧压力系数的增大而减小.数值模拟结果为类似高地应力软岩隧道设计施工和变形控制提供参考和依据.

In order to explore the response characteristics of plastic deformation and stress redistribution around the tunnel under different excavation methods and the influence mechanism of geological strength parameters on excavation deformation, a reasonable excavation method system under different surrounding rock grades was sought. The best support time is to use numerical analysis methods to analyze and study the surrounding rock stress, plastic zone distribution and deformation instability under the four construction methods. The results show that:(1)For weak surrounding rock, the CRD method and the three-step temporary invert method can effectively control the deformation, stress and the development of the plastic zone of the surrounding rock, especially the control effect of the arch toe displacement is obvious. The three-step method After excavation with the ring-shaped reserved core soil method, larger convergence deformation will occur at the arch toe.(2)The use of temporary support will cause obvious stress concentration at the support and arch foot position. In the actual process, the protection of this position should be strengthened, and the lock foot anchor rod or reinforcement grouting should be set to improve its strength bearing capacity.(3)Premature support after excavation did not give full play to the self-supporting capacity of the surrounding rock, and the loose pressure in the surrounding rock caused the surrounding rock to enter the rheological state if the support was not timely. The reasonable supporting period of soft V grade surrounding rock should be within 10%～30% of load release after excavation.(4)The horizontal convergence of the arch waist generally increases with the increase of the lateral pressure coefficient, but when k is 0.5, the horizontal displacement of the arch waist tends to converge inward and rapidly expand outward; The vertical settlement of the surrounding rock above the vault decreases with the increase of the lateral pressure coefficient. The numerical simulation results provide reference and basis for the design and construction of similar high in-situ stress soft rock tunnel and deformation control.

引言
1 工程背景
2 三维隧道动态开挖分析
3 软岩隧道支护时机优化
4 不同水平应力下围岩位移特征
5 结论

图1 分离式隧道内轮廓图
Fig.1 Separated tunnel interior profile

表1 基于GSI分类系统和H-B准则确定的围岩力学参数表<br/>Tab.1 Mechanical parameters of surrounding rock determined based on GSI classification system and H-B criterion

表1 基于GSI分类系统和H-B准则确定的围岩力学参数表
Tab.1 Mechanical parameters of surrounding rock determined based on GSI classification system and H-B criterion

表2 支护力学参数<br/>Tab.2 Mechanical parameters of supporting

表2 支护力学参数
Tab.2 Mechanical parameters of supporting

图2 各开挖工法模型洞室网格细部划分示意图<br/>Fig.2 Diagram of mesh division of each excavation method

图2 各开挖工法模型洞室网格细部划分示意图
Fig.2 Diagram of mesh division of each excavation method

图3 不同岩体强度下各工法洞周位移变化<br/>Fig.3 Variation of circumferential displacement under different rock mass strength

图3 不同岩体强度下各工法洞周位移变化
Fig.3 Variation of circumferential displacement under different rock mass strength

图4 各工法围岩主应力随岩体强度变化趋势<br/>Fig.4 Main stress of surrounding rock varies with the strength of rock mass

图4 各工法围岩主应力随岩体强度变化趋势
Fig.4 Main stress of surrounding rock varies with the strength of rock mass

表3 中间断面围岩主应力状态<br/>Tab.3 principal stress state of surrounding rock in middle section

表3 中间断面围岩主应力状态
Tab.3 principal stress state of surrounding rock in middle section

图5 围岩各监测点主应力提取结果<br/>Fig.5 Principal stress of surrounding rock's monitoring point

图5 围岩各监测点主应力提取结果
Fig.5 Principal stress of surrounding rock's monitoring point

图6 Ⅴ级围岩塑性区分布图<br/>Fig.6 Ⅴ grade surrounding rock plastic separation layout

图6 Ⅴ级围岩塑性区分布图
Fig.6 Ⅴ grade surrounding rock plastic separation layout

图7 最佳支护时机Ts及最佳支护时段[TS1～TS2]示意图<br/>Fig.7 Schematic diagram of optimal supporting time TS and optimal supporting period[TS1～TS2]

图7 最佳支护时机Ts及最佳支护时段[TS1～TS2]示意图
Fig.7 Schematic diagram of optimal supporting time TS and optimal supporting period[TS1～TS2]

表4 隧道开挖后围岩荷载释放系数LDF设置<br/>Tab.4 Setting of load release coefficient LDF of surrounding rock after tunnel excavation

表4 隧道开挖后围岩荷载释放系数LDF设置
Tab.4 Setting of load release coefficient LDF of surrounding rock after tunnel excavation

图8 洞周位移随开挖后荷载释放比例变化趋势图<br/>Fig.8 Trend of displacement around tunnel with the proportion of load release after excavation

图8 洞周位移随开挖后荷载释放比例变化趋势图
Fig.8 Trend of displacement around tunnel with the proportion of load release after excavation

图9 洞周局部位移随侧压力变化趋势图<br/>Fig.9 Trend of displacement around hole with lateral pressure

图9 洞周局部位移随侧压力变化趋势图
Fig.9 Trend of displacement around hole with lateral pressure

图10 岩体沉降量随侧压力系数变化趋势<br/>Fig.10 Settlement of rock varies with lateral pressure coefficient

图10 岩体沉降量随侧压力系数变化趋势
Fig.10 Settlement of rock varies with lateral pressure coefficient

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备注

引言

1 工程背景

2 三维隧道动态开挖分析

3 软岩隧道支护时机优化

4 不同水平应力下围岩位移特征

5 结论

期刊信息