破碎围岩注浆加固体开挖稳定性及水压超载试验研究

来源期刊:中南大学学报(自然科学版)2016年第6期

论文作者:张伟杰 李术才 魏久传 张庆松 张霄 李鹏

文章页码:2083 - 2091

关键词:开挖稳定性;水压超载试验;物理场演化特征;渗透性;加固安全度

Key words:excavation stability; hydraulic overload test; evolution law of physical fields; permeability; safety degree of reinforcement

摘    要:利用三维注浆模型试验系统,开展帷幕注浆加固体开挖稳定性试验,研究位移、总压力及孔隙水压力时空演化规律。研究结果表明:加固体内部位移、土压力及孔隙水压力随开挖步序推进,经历缓慢增长—急剧增加—逐渐稳定3个阶段;开挖对注浆加固体影响范围约3倍洞径,且拱顶位置扰动最大。6级水压超载试验过程中,隧洞拱顶持续沉降,注浆加固体渐进破坏;超载水头压力与初始水头比值h/h0<3时,涌水速率qw呈线性增大;h/h0≥3后,qw非线性急剧增长;涌出物(水、泥沙)形式经历渗水—滴水—股状涌水—溃水—涌泥的发展阶段;总压力和孔隙水压力均呈现快速增大-稳定-再增大特征,并于破坏时刻附近突跳,且孔隙水压力响应灵敏度更高。注浆加固体渗透性测试试验表明,注浆后泥质软弱区(SCZ)渗透系数k减小3个数量级,破碎区(FZ) k减小2个数量级。基于注浆薄弱区短板效应的认识,提出加固安全度K作为注浆综合效能评判指标,破碎岩体加固后综合性能提高10.3倍。

Abstract: The excavation stability test of curtain grouting reinforced body was carried out using 3D grouting model test system to obtain the temporal and spatial evolution law of displacement, total pressure and pore pressure. The results show that the internal displacement, soil pressure and pore pressure are propelled with the excavation step. It undergoes three periods: slow growth-dramatic increase-gradual stabilization. The influence scope of excavation on grouting was about triple tunnel diameter, and the most serious is on the vault. In the sixth hydraulic overload test, the vault of tunnel subsides continuously; the grouting reinforced body has progressive failure. The water inflow rate qw increases linearly, when the ratio between overload pressure head and initial head h/h0<3. After h/h0≥3, qw increases rapidly nonlinearly. The water inrush form goes through five developmental stages: water leaking-water dripping-water gushing-water bursting-mud inrushing. Both the total pressure and pore pressure present the rapid increase-stabilization-further increase characters. They change abruptly at the destroying moment. The response sensitivity of pore pressure is higher. The grouting reinforced body permeability test indicates that the coefficient of permeability k of soft-clay zone (SCZ) reduces three orders of magnitude after grouting, and the k of fracture zone (FZ) reduced two orders of magnitude. The strengthening safety degree K is proposed as the main evaluation index of grouting evaluation indexes based on the cognition of cask effect in non full-reinforced zone. The combination property of fractured rock mass is increased by 10.3 times after being grouted.

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