云岗石窟立柱岩体安全性定量评价

QUANTITATIVE EVALUATION ON THE SAFETY OF THE COLUMN ROCK MASSES IN YUNGANG GROTTO

千余年来,云岗石窟遭受了严重的渗水病害,同时,因构造节理和卸荷裂隙的切割,降低了石窟的立柱岩体稳定性,其中的第9#,10#,12#窟的窟前立柱岩休风化严重,已威胁到石窟安全,需及时采取措施进行加固。通过现场勘察和病害调查,采取岩样和水样进行测试分析,并对石窟岩体进行了三维数值模拟分析,其目的是查明石柱承受荷载的大小及应力分布情况、立柱岩体的强度及安全系数、评价立柱岩体的稳定性,从而为杠窟防治和加固设计提供科学依据。研究表明:在第9#,10#和12#窟立柱岩体顶部的压应力分别由成窟前的0.45,0.44MPa增加至成窟后的1.29-1.31MPa和0.94-0.96MPa,分别增大了3倍和2倍以上;荷载最大值在第10#窟的4#柱上部,达3741kN;立柱岩体的极限单轴抗压强度为1.95MPa;按现行规范的要求,6根立柱岩体都处于不安全状态,必须对9#,10#,12#窟立柱进行加固整治。

During the past thousand years, Yungang Grotto has suffered a lot from the seepage hazard, and at the same time, the stability of upright column rock masses of the grotto has reduced because the grotto is dissected by the tectonic joints and unload cracks. The weathering effect on the upright column rock in front of grotto 9, 10 and 12 is the most serious. The stability of the columns has great effect on the safety of grotto, so relative reinforcing measures should be taken as soon as possible. The author has carried out site investigation and hazard research, and some rock and water samples had been taken and tested. Three-dimensional numerical simulation has been used to study the load on the column, and the stress distribution, strength and safety factors of the column were determined accordingly. All these work provides basis for prevention of potential hazard and reinforcement design for the grotto. Research result shows that, the compressive stress on the top of the column rock of grotto 9, 10 and 12 have grown from 0.45 MPa, 0.44 MPa (before the grotto is shaped) to 1.29-1.31 MPa, 0.94-0.96 MPa (after the grotto is shaped), respectively. The biggest load is at the top of column 4 in grotto 10, which is 3 741 kN. The highest uniaxial compressive strength of the column rock is 1.95 MPa. According to the criterion, all the six columns are in state of danger, and the grotto 9, 10, 12 should all be reinforced.