隧道开挖中注浆效果的FLAC^(3D)研究

Research on Grouting Effect on Tunneling with FLAC^(3D)

应用FLAC3D,通过改变受注围岩体的力学性质,研究注浆后隧道及围岩体开挖时的应力分布规律以及地表沉降情况.模拟结果与工程实际对比分析表明,注浆后加固体对于开挖隧道具有棚护作用,加固体两侧为应力集中区;按270°布置注浆孔,开挖引起沉降值最小,为22.3mm,实际工程监测值为27.1mm,应用FLAC3D进行注浆效果事前分析是可行的;计算值与实际值存在偏差与注浆施工的理想化有关,注浆时,应该逐渐增加注浆压力,并根据注浆终压和注浆量共同判断是否结束注浆,从而保证注浆质量.

The stress distribution and evolving surface settlement during tunneling and excavating surrounding rockmass after grouting were studied with FLAC^3D for the change in the mechanic properties of grouted surrounding rockmass.The simulation results in contrast to engineering practice indicated that the grouting serves the function of shielding to reinforce tunneling and both sides of reinforced rockmass are the stress concentration area.With the 3/4 part（270°）of a circular hole used for grouting,the settling amount due to excavation in simulation is minimum,i.e.22.3 mm which becomes 27.1 mm in practical monitoring.Therefore,it is feasible to forecast the reinforcement effect by simulation with FLAC^3D.The reason why the simulated settling amount deviates from that monitored relates to the idealized grouting construction.It＇s of importance to increasing the grouting pressure gradually and to judging whether the grouting process should be ended according to both the finishing pressure and grouting amount so as to ensure the grouting quality.