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为了明确预切槽法开挖隧道过程地层和预筑拱的力学响应,设计了1∶10大比尺三维地质力学模型试验,真实地模拟了预切槽法的切槽灌注和掌子面土体开挖过程,研究了预切槽法施工过程中地层变形及预筑拱结构受力情况。通过土体中埋设的位移、土压力及应变测点得到了洞周土压力和预筑拱的应变值,通过对试验数据的分析和与数值模型计算的对比,进一步了解地层变形的发展过程,寻找结构受力特征及施工过程的关键问题。研究结果表明:切槽混凝土灌注压力和灌注及时性对预筑拱成拱效果的影响较大;切槽及灌注混凝土过程引起的地层沉降占比较大,预筑拱形成后下部土体开挖引起的地层沉降较小,说明预筑拱可以保护掌子面超前核心土,显著减少隧道收敛变形,有效控制地层沉降;预筑拱两侧边墙和拱腰受压,拱顶主要受拉,采用素混凝土灌注的预筑拱极易发生破坏,实际工程设计施工时需要注意提高预筑拱抗拉性能。
In order to clarify the mechanics response of tunnel pre-excavation tunneling pre-arch and pre-incision method, a 1: 10 large-scale three-dimensional geomechanical model test was designed to simulate slotted perfusion and face soil Body excavation process, the deformation of prestage during the construction process and prestressed arch structure stress situation. Through the displacement, earth pressure and strain measuring points buried in the soil, the earth pressure around the hole and the prestressed arch strain value are obtained. By analyzing the experimental data and comparing with the numerical model, we can further understand the development process of the strata deformation, Look for the structural characteristics of the force and the key issues of the construction process. The results show that the perfusion pressure and timeliness of cut concrete have a great influence on the arching effect of prefabricated arch; the proportion of formation settlement caused by cutting and pouring concrete is larger, and excavation of lower soil after pre-arching is caused The results show that the pre-arch can protect the core surface ahead of the face, significantly reduce the tunnel convergence and deformation, and effectively control the settlement of the formation. The sidewalls and arch waist on both sides of the prefabricated arch are compressed and the arch is mainly tensioned. Concrete precast concrete pouring is extremely prone to damage, the actual engineering design and construction need to pay attention to improve the tensile properties of precast arch.