【作者】 贺若兰；

【导师】 李宁；

【作者基本信息】 西安理工大学 ， 岩土工程， 2003， 硕士

【摘要】 土钉支护在国内外已得到广泛应用，但对支护结构与岩土介质特别是软弱岩土介质相互作用机理的研究还停留在定性描述阶段，现行设计理论只能建立在工程类比基础之上；本文借助有限元方法在量化研究方面的特有优势，对土钉支护进行了系统的数值试验研究，试图从量化的角度揭示土钉支护的加固机理，为优化设计提供较为科学的依据。 论文首先研究土钉拉拔试验中极限拉拔力与界面粘结强度的关系；然后对基坑开挖和支护进行全过程仿真分析，从支护结构内力和变形随开挖、支护过程发展形成的特征规律来揭示土钉支护的加固机理；在此基础上，对影响支护效果的支护参数和土性参数进行系统的数值试验研究，进一步量化土钉支护的合理加固参数。 主要研究成果： 1、从理论上建立拉拔试验中“极限拉拔力”和“界面粘结强度”的关系，再借助现场实测的极限拉拔荷载，获取钉土界面的合理粘结强度参数，对拉拔试验进行数值仿真分析，验证了仿真模型中界面单元的可靠性和精度，并标定了数值试验中土钉的破坏模态。 2、从量化角度揭示了土钉支护结构通过单钉的应力分担和传递作用、群钉的骨架箍束作用和钉间土体形成土拱发挥应力扩散作用集单钉锚固和群钉加固机制 西安理工大学硕士学位论文面面面面面面面面面面面面面面面面于一身的加固机理。 3、砂性土中，通过土钉长度、密度和刚度三个主要支护参数对加固效果的影响分析，得出了较优的布钉方式和各临界参数值:软粘土中，坑壁变形将出现流鼓状，且临界参数值不明显，建议在软粘土中采取土钉和桩、墙联合支护方式。更多还原

【Abstract】 The soil-nailed support system has been applied widely at home and abroad, but it is short of research on mechanism of interactive action between support structure and rock and soil medium especially soft-weak medium and some understandings rest on the stage of qualitative descriptions. Current design theories base on engineering analogy. The systemic numerical tests on soil-nailed support are made utilizing the advantage of the FEM method on quantitative research in this dissertation, the reinforce mechanism in quantitative aspect is pointed out, and the reinforce effects of support parameter and soil property parameter are abstracted so as to provide scientific basis for optimization design. The main conclusions are remarked as follows:(a) The theory formula between the ultimate tensile force and interface cohesive intensity has been established. According to ultimate tensile force from in-site measure, the scientific interface cohesive intensity parameter has been achieved, then, the numerical analysis of the tension-draw test has been made. The reliability and precision of the interface element in theanalysis model has been validated and the failure mode of the soil nailing in the tension-draw test has been demarcated.(b) The reinforce mechanism combined reinforcing and anchoring, which displayed by single nail’s stress-participating and stress-transferring, multi-nail’s framework confining and the soil-arch’s stress-proliferating, has been revealed in quantitative aspect.(c) Optimized lay-out of the soil nailing and critical parameters have been obtained by the sensitivity analysis of the length, density and stiffness in the sandy soil. In soft clay, it is proposed that the soil nailing associated with other support systems, such as piles and walls etc, should be used, for the drum-shape of the deformation at cut slope appears and the critical parameters aren’t obvious.更多还原