针对软岩大变形工程处置目前大多仍沿用传统强支硬顶施工方法所存在的问题，分析挤压型大变形隧洞中采用让压支护的必要性，认为在挤压型大变形隧洞施工中，采用刚性支护进行“硬扛”是不行的；可缩式钢拱架在大变形（如δ≥500 mm）隧洞中是不能用的，需要“另辟蹊径”，创新求变。经5处工程实践证明，在软岩挤压大变形隧洞施工中，施作让压锚杆/预应力长让压锚索是一种更为有效可行的对策措施。阐述让压支护“边支边让、先柔后刚“的设计理念，阐明其工作原理，对让压锚杆及预应力让压锚索进行比选，从施工和受力2方面考虑，建议采用预应力长让压锚索。并对锚杆、锚索参数、锚固头形式、锚腔位置等关键技术指标进行分析推荐。〖JP2〗讨论让压支护的经济性，经与传统“硬扛”的方式对比估算，认定采用让压支护是完全划得来的。 首先，对软岩挤压型大变形隧洞计算分析中的若干问题作简要说明，包括： 1）二、三维分析模式的选择问题； 2）几何非线性问题； 3）非线性、非定常黏弹塑性围岩流变/蠕变时效的耦合相互作用问题； 4）几何非线性与材料非线性耦合专用程序软件研发及应用问题。然后，简述了挤压大变形隧洞中考虑几何非线性和材料非线性的耦合作用的研究进展。最后，对下一步深化研究提出5点建议： 1）进一步积累大量流变试验和隧洞现场实测资料，提出数值模拟预测挤压大变形更有理论依据、更加可信、适用的方法； 2）非线性黏弹塑性流变本构模型分析的编程工作，需引入和拓展至三维非线性黏弹性流变属性并选用相应的流变本构模型； 3）完善目前工作中存在的不足，收集更为详细的研究资料和现场实测与流变试验数据，并将试验手段、数值计算与理论演引三者相结合，对几类不同软弱岩性的挤压型非线性流变力学行为进行更细致完善的系统研究； 4）深入分析挤压型大变形问题时，应考虑多场耦合问题； 5）本研究仅局限于软岩，基于连续介质理论所建立的大变形理论，不适用于软黏土隧洞的大变形破坏问题，这应作为今后拓展研究的一个方面。

Presently, traditional strengthened support is still the main choice in soft rock large deformation projects. In this study, the necessity of yielding support for large squeezing deformation is analyzed. The traditional rigid support and retractable steel arch are not feasible for controlling the large squeezing deformation of the tunnel, especially when the deformation δ is greater than 500 mm. 〖HJ1.7mm〗The relevant results of the yielding anchor bolt and prestressed yielding anchor cable in five projects confirm their effectiveness in controlling the large squeezing deformation of soft rock. First, the design concept and working principle, are introduced Second, (yielding anchor bolt and prestressed yielding anchor cable are compared. The prestressed yielding anchor cable is recommended owing to its construction and force performance). The anchor bolt and anchor cable parameters, anchor head form, and anchor cavity position of yielding support are introduced. Third, the economic benefit of yielding support is discussed; the comparison and estimation results indicate its costefficiency. Fourth, some problems in calculating and analyzing the soft rock tunnel with large squeezing deformation are explained: (1) the mode selection of twoand threedimensional analyses; (2) the geometric nonlinearity; (3) the coupling interaction between creeptime effect and rheological mechanical properties of nonlinear nonsteady viscoelastic surrounding rock; (4) development and application of specific software for analyzing the coupling effect between geometric and material nonlinearity. Fifth, the research works on the coupling effect are summarized. Finally, the following suggestions are put forward for further research. (1) Vast amount of data should be collected from rheological tests and tunnel field measurements, and numerical simulation should be conducted to provide more feasible methods for predicting large squeezing deformation. (2) The threedimensional nonlinear viscoelastic rheological mechanical characteristics should be introduced and expanded. Furthermore, the appropriate rheological constitutive model should be adopted. (3) The test methods, numerical calculating methods, and theoretical calculation should be integrated. A more detailed study on nonlinear rheological mechanical characteristics of squeezing deformation of different soft surrounding rocks should be conducted. (4) The multifield coupling should be considered when conducting indepth analysis on large squeezing deformation. (5) The study is based on soft rock, and the proposed theory is based on continuous medium, which does not suit for large deformation failure of soft clay tunnel. However, it should be considered an extended research aspect.