深埋有压隧洞平行四边形管片衬砌结构受力特性研究

水荷载是深埋有压隧洞的主要荷载,内水压力或外水压力直接作用在衬砌管片上,管片衬砌的受力特性对于工程安全稳定运行具有重要意义。平行四边形管片作为一种新型管片,在错缝拼装方式下应用具有较大优势,但尚未对其结构受力特性进行研究。依托某市供水隧洞工程实际,建立新型平行四边形管片衬砌的三维有限元数值模型,研究其在运行期和检修期的受力特性。结果表明,运行期内水压力作用下,衬砌各管片单独受力,管片间变形与拉应力不连续,以环向螺栓连接,各接缝开度呈现靠近衬砌内侧小、外侧大的特点;检修期外水压力作用下,衬砌管片受力整体性较好,管片间环向变形与压应力连续,环向螺栓压应力偏小,各接缝压力靠近衬砌内侧较大、外侧较小。同时,根据衬砌与豆砾石间摩擦系数讨论结果可看出,运行期衬砌朝外变形,管片与豆砾石间呈压紧趋势,其受力变形受摩擦系数的影响较为敏感,检修期管片与豆砾石间呈分离趋势,管片受力特征基本不受摩擦系数的影响。

Structure Characteristics of Parallelogram Segment Lining in Deep-buried Tunnel under Hydraulic Pressure

Water load is the main load deep buried tunnel under hydraulic pressure bears. The internal and external water pressure are applied on the lining segments directly, therefore the mechanical characteristics of segment lining play an important role in engineering stability and safety. As a new kind of lining segment, parallelogram segment has great advantages in engineering application under staggered joint erection, while the research about it is few. According to a water supply tunnel in a city, a three-dimensional finite element numerical model of the parallelogram segment lining has been established to investigate its mechanical characteristics during operation and overhaul period. It can be concluded that during operation period, the lining segments in a ring bear internal water pressure independently, and the displacement and tensile stress are discontinuous, which are connected only by bolts; Besides, for every segment joint, the joint opening of one side near the lining outer surface is wider than near the inner surface; During overhaul period, the lining segments bear external water pressure as a whole, and the circumferential displacement and compressive stress are continuous; Besides, for every segment joint, the pressure on one side near the lining inner surface is larger than near the outer surface. Meanwhile, the influence of different friction coefficients between the lining and pea gravel has been discussed. The results show that the lining mechanical characteristics are sensitive to friction coefficients during operation period since the lining deforms outwards and squeeze the pea gravel under internal pressure; While they are insensitive during overhaul period as the lining deforms inwards and is separated from the pea gravel under external pressure.