长江三峡链子崖危岩体防治工程效果研究

STUDY ON CONTROL ENGINEERING EFFECT ABOUT LIANZIYA DANGEROUS ROCK-BODY IN THREE GORGES RESERVOIR OF YANGTZE RIVER

长江三峡链子崖危岩体防治工程于1995年5月开工,1999年8月竣工,历时51个月。至2004年底,工程效果监测已超过5a,且经受了2003年6月以来三峡水库139m蓄水位的检验。危岩体变形监测、地压监测和整体稳定性计算三方面结合可以作为评价工程治理效果的依据。地表和地下监测点总体变形速率由治理前水平速率接近2．0mm/a、垂直速率约1．5mm/a转为治理后水平速率小于1．0mm/a、垂直速率小于0．75mm/a,证明危岩体逐步稳定。施工过程中主要监测点水平速率为8．0～18．8mm/a,垂直速率为8．0～21．0mm/a,说明危岩体对施工扰动是敏感的。危岩体底部煤层采空区混凝土承重阻滑键体顶面的地压数据在2002年以后基本稳定,地压记录多数为2．0～10．0MPa,最大地压值为18．08MPa,最小地压值为-0．8MPa,证明危岩体以煤层采空区为底界的悬板偏压作用机制导致的应力集中区和负压区确实存在。2003年6月以后三峡水库蓄水至139m,淹没了煤层采空区治理工程,但整个危岩体变形速率无明显变化,地压监测记录的最大变化量小于0．01MPa。根据煤层采空区顶板与混凝土承重阻滑键体接触带现场原位大尺度(1m×1m)岩体力学试验求取的强度参数进行危岩体稳定性校核计算,得出链子崖防治工程达到正常荷载下稳定系数大于1．30(治理前为1．062),特殊荷载下大于1．15的设计目标。

The Lianziya dangerous rock-body control engineering in Three Gorges Reservoir of Yangtze River lasted 51 months from beginning in May, 1995 to finishing in Aug. of 1999. Engineering effect monitoring conducted for five years for Lianziya up to Dec. of 2004 and tested by water table 139 m of Three Gorges Reservoir after Jun. in 2003. Three factors, i.e. monitoring data about deformation in the surface of Lianziya, pressure in coal mined-out area and calculation results of stability, are united as a scientific criterion to access engineering control effects. It can be seen from deformation monitoring data that Lianziya becomes stable gradually because the horizontal displacement velocity is decreased from about 2.0 mm/a to less than 1.0 mm/a and vertical displacement velocity from about 1.5 mm/a to less than 0.75 mm/a before and after engineering control. Lianziya stability is extremely susceptible to response to constructing activity in coal mined-out area, where the horizontal velocity of surface monitoring points was about 8.0 - 18.8 mm/a and vertical velocity about 8.0- 21.0 mm/a in engineering working period from May of 1995 to Aug. of 1999. It is proved that stress concentration and relaxation belt is existent resulting from the effect of cantilever plate with inclined pressure in coal mined-out area. In the lowest layer most of pressure data on the concrete key system for bearing pressure and anti-sliding are between 2.0 and 10.0 MPa, but the maximum and minimum values are 18.08 and -0.8 MPa, respectively. All the data are almost constant since Jan. of 2002. Displacement velocity change is not obvious and pressure values change is less than 0.01 MPa in Lianziya when water table rises to 139 m in Three Gorges Reservoir of Yangtze River after Jun. of 2003. Lianziya control engineering has achieved designing goal based on the stability coefficient greater than 1.15 in special loading condition and 1.30 in general. The large size（1 m×1 m） rockmass mechanics test was made in field to obtain the strength parameters for stability calculation of the engineering.