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以长湘高速公路李家冲隧道工程为背景,针对地表高压铁塔塔基受到隧道开挖及爆破影响的情况,运用FLAC3D对铁塔4个塔基的沉降及质点振动速度进行了数值分析。并与现场实测数据进行对比分析,结果表明:(1)隧道开挖后铁塔塔基发生沉降,最大沉降量发生在测点3即1号塔基处,为3.55 mm。(2)施加爆破动载荷后,最大沉降量增量出现在1号塔基为2.23 mm,其他塔基沉降量也有不同程度的增大。(3)塔基的质点振动速度幅值为4.2cm/s,在允许的安全振速范围之内。质点振动速度与隧道开挖中线距离有关,距隧道开挖中线距离越近质点振速越大,反之则越小。分析结果与实际观测结果相吻合,并给出了避免爆破震动诱发地表铁塔塔基失稳塌陷的几条建议。
Taking the Lijiachong Tunneling Project of Chang-Xiang Expressway as the background, the numerical analysis of settlement and particle vibration velocity of four tower foundation of the tower was carried out using FLAC3D in view of the tunnel excavation and blasting of the surface high-pressure tower. The results show that: (1) The settlement of the tower foundation of the tower after tunnel excavation has occurred. The maximum settlement occurred at the measuring point 3, tower 1, at 3.55 mm. (2) After the dynamic load of blasting is applied, the increment of the maximum settlement occurs when the foundation of No. 1 is 2.23 mm, and the settlement of other towers also increases to some extent. (3) The mass vibration velocity of the foundation is 4.2cm / s, which is within the allowable safe vibration speed range. The velocity of particle vibration is related to the middle distance of tunnel excavation. The closer to the middle of the tunnel excavation, the larger the vibration velocity of particle and vice versa. The analysis results are in good agreement with the actual observations and some suggestions are given to avoid the instability collapse of the tower base caused by blasting vibration.