负泊松比锚索超大断面隧道围岩大变形控制体系

为解决传统吸能锚索不能解决超大断面隧道软弱围岩隧道大变形的问题，首次提出将NPR锚网索支护体系应用于超大断面隧道支护措施中。本文依托侨城东路隧道东线标准段为工程背景，通过实地勘察，室内试验和理论分析的方法，从围岩岩性，物理力学特性以及水文地质条件方面，揭示了侨城东路隧道围岩大变形机理；通过室内试验得到NPR锚索物理力学特性并构建本构模型；再利用Rhino软件建立隧道以及初期支护模型、FLAC3D软件进行模拟计算，对比分析无锚索、PR锚索、不同排距NPR锚索4种方案围岩应力、位移、变形破坏规律。基于以上研究成果，进行室内相似比物理模型试验进行对比验证。结果表明，NPR 锚网索支护体系相比普通锚网索支护能够有效的控制超大断面隧道软弱围岩大变形，不仅为侨城东路北延通道工程的施工及初期支护提供了数据支撑，也为类似条件隧道的围岩变形控制奠定了理论基础。

Control system of large deformation of SURROUNDING rock in NPR anchor cable super large section tunnel

In order To solve the problem that traditional energy absorption anchor cable can not solve the large deformation of soft surrounding rock tunnel with large section, the NPR anchor net cable supporting system is first proposed to be applied to the supporting measures of super-large section tunnel. In this paper, based on the east standard section of qiaocheng East Road tunnel as the engineering background, by means of field investigation, laboratory test and theoretical analysis, the mechanism of large deformation of surrounding rock of qiaocheng East Road tunnel is revealed from the aspects of surrounding rock lithology, physical and mechanical properties and hydrogeological conditions. Physical and mechanical properties of NPR anchor cable are obtained through laboratory tests and constitutive model is constructed. Then Rhino software was used to establish tunnel and initial support model, FLAC3D software was used to simulate calculation, and the stress, displacement and deformation failure laws of surrounding rock with no anchor cable, PR anchor cable and NPR anchor cable with different row spacing were compared and analyzed. Based on the above research results, indoor similarity ratio physical model test was conducted for comparative verification. The results show that the NPR bolt-net cable support system can effectively control the large deformation of soft surrounding rock of super-large section tunnel compared with the ordinary bolt-net cable support system, which not only provides data support for the construction and initial support of qiaocheng East Road north extension channel project, but also lays a theoretical foundation for the deformation control of surrounding rock of tunnel with similar conditions.