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基于普宣高速公路宣威岸重力式锚碇工程,设计了不回填无预应力、不回填有预应力和回填有预应力3种计算工况,利用数值仿真试验分析了重力式锚碇和地基的力学机制和破坏模式。承载机制表明:8倍设计荷载之前没有塑性变形,为弹性工作状态,最大变形在锚岩界面,摩擦效应居主导,基底拉应力区可控,锚碇结构抗滑移和抗倾覆性均处于稳定可控状态;12倍设计荷载之后塑性区逐步扩展,达到20倍设计荷载时全部贯通,基底塑性变形明显,锚碇结构变形显著,基底夹持岩体剪切破坏,夹持效应居主导,基底拉应力区不可控,锚碇结构抗滑移和抗倾覆性均处于不可控状态;锚碇施加的预应力只在结构-岩基协调变形之前起作用,之后影响不大;回填可以极大地改善基底应力状态与结构扭转变形、抗滑移和抗倾覆稳定性,可在容许变形范围内适当考虑增强效应。可见,重力式锚碇结构-地基协调变形与联合承载机制,表现为摩擦效应、夹持效应和回填效应的综合作用。监测结果显示:通过基底拉应力和压应力监控结构与地基接触面安全性,监测值小于地基容许承载力3MPa;通过基底变位和地基深部水平位移监控结构抗滑移稳定性,实际工程监测值小于1mm;通过角点不均匀沉降监控锚碇抗倾覆稳定性,倾斜值小于0.006;通过大体积混凝土温控监测可知,内部最高温度小于60℃,进出水温差小于15℃,内表温差小于20℃,峰后降温速率小于3℃·d~(-1);锚束锁固荷载监测变化幅值不超过设计值的5%。
Based on the Xuanwei shore gravitational anchorage project of Puxuan Expressway, three kinds of calculation conditions of non-prestressed non-backfill, non-backfilled prestressed and backfilled prestressed were designed. Numerical simulation tests were conducted to analyze the effects of gravitational anchorage and foundation Mechanics and destruction mode. The loading mechanism shows that there is no plastic deformation before 8 times of design load, which is elastic working state, the maximum deformation is at the interface of anchor and rock, the friction effect is predominant, the tensile stress zone of the substrate is controllable, anti-slip and anti-overturning of anchor structure are stable The plastic zone expands gradually after 12 times of designed load and reaches 20 times the design load. The base plastic deformation is obvious, the deformation of anchorage structure is remarkable, the shear failure of basement holding rock mass is dominant, and the holding effect is dominant. The basement The tensile stress zone is uncontrollable, the anti-slip and anti-overturning of the anchorage structure are uncontrollable, and the prestressing force applied by the anchorage only plays a role before the coordinated deformation of the structure and the rock foundation, and then has little effect; the backfilling can be greatly improved Substrate stress state and structure of the torsional deformation, anti-slip and anti-overturning stability, allowable deformation within the scope of appropriate consideration to enhance the effect. It can be seen that the gravitational anchorage structure-foundation coordinated deformation and joint bearing mechanism show the combined effect of friction effect, clamping effect and backfill effect. The monitoring results show that: the basement tensile stress and compressive stress monitoring structure and ground contact surface safety, the monitoring value is less than the allowable bearing capacity of foundation 3MPa; by the basement displacement and horizontal displacement of the foundation to monitor the anti-sliding stability of the structure, the actual project monitoring value Less than 1mm; stability monitoring of anti-overturning of anchorage by uneven corner settlement with an inclination of less than 0.006; temperature monitoring of mass concrete shows that the maximum internal temperature is less than 60 ℃, the temperature difference between inlet and outlet is less than 15 ℃, the internal temperature difference is less than 20 ℃, and the post-peak cooling rate is less than 3 ℃ · d ~ (-1). The change of anchorage load monitoring amplitude does not exceed 5% of the designed value.