水工隧洞钢筋混凝土衬砌水压致裂分析方法研究

引入具有水力耦合属性的内聚单元模拟衬砌裂缝、衬砌-围岩交界面,以反映缝隙的位移非连续特征以及内部压力水体的流动特性。结合渗流-应力间接耦合方法,提出了水工隧洞钢筋混凝土衬砌水压致裂算法,探究了衬砌裂缝发展历程、裂缝宽度演化以及缝隙内部水压力传递特征等,并基于此系统分析了衬砌-围岩有条件联合承载特性的影响。计算分析表明,隧洞充水加压过程中,衬砌裂缝促发与扩展过程短暂且密不可分,随之缝内水压力突增、内水外渗效应加剧;衬砌开裂后,缝内水压力沿衬砌径向的降低幅度非常小,量值较为接近于内水压力。有条件联合承载情况下,衬砌裂缝与衬砌-围岩交界面间隙所形成的水体流动通道可以起到传导水压力的作用,使得衬砌外水压力分布更为均匀;衬砌裂缝相对稳定,并且呈现数量少、间距大的分布特点,与衬砌压水试验结果更为吻合。

Hydraulic fracturing analysis method of reinforced concrete lining in hydraulic tunnel

The cohesive element with hydro-mechanical coupling property is introduced to simulate the lin- ing crack and lining-rock interface. In this way, the discontinuous displacement characteristics of lining crack and interface gap can be taken into consideration, as well as the flow characteristics of pressure wa- ter inside. Combined with the indirect-coupled method of hydro-mechanical interaction, the hydraulic frac- turing algorithm of reinforced concrete lining in hydraulic tunnel is proposed. The development history of lin- ing crack and the evolution of crack width are explored, as well as the water pressure transfer characteris- tics inside lining crack and interface gap. Based on this, the influences of conditional cooperation between lining and surrounding rock are analyzed systematically. Through the calculation and analysis, it can be found that the process of crack initiation and propagation is short and inseparable during the water-filling period of hydraulic tunnel. Subsequently, the water pressure inside lining crack suddenly increases, and the effect of inner water exosmosis accelerates. After the cracking of lining, the water pressure inside lin- ing crack slightly declines along the radial direction, and the pressure magnitude is relatively close to the inner water pressure. With the conditional cooperation considered,the water flow channel formed by the lin- ing crack and lining-rock interface can play a role in transmitting water pressure, resulting in a more uni- form distribution of water pressure outside the lining. The lining cracks are in a relatively stable state,and the distribution of lining cracks is small in number and large in spacing. This is more consistent with the results of field tests.