针对高地应力软岩隧道围岩稳定性差的问题，基于泡沫混凝土具有防水、保温、抗震、压缩性大和一定延性的特点，采用数值模拟的方法，分析了高地应力软岩公路隧道泡沫混凝土的卸压效应及其影响因素，进而研究泡沫混凝土的力学参数对卸压效果的影响。采用控制变量法计算确定了泡沫混凝土的最佳力学参数取值范围，进而分析得到了高地应力软岩公路隧道的泡沫混凝土卸压机理，根据以上研究成果，构思出一种新型的泡沫混凝土复合式衬砌结构型式——泡沫混凝土复合式衬砌。研究表明：高地应力软岩公路隧道添加泡沫混凝土层后，围岩应力的释放率由普通支护条件下的30%提高至62%，围岩强度应力比由1.92提高至3.74，隧道支护结构承受的荷载平均减小了37.19 MPa；泡沫混凝土的最佳力学参数中弹性模量取400~800 MPa，屈服压应力系数k取0.4~0.6，静水屈服拉应力系数kt取0.1~0.3，单轴抗压强度取2.0~4.0 MPa；利用泡沫混凝土的高压缩力学特性，可诱导隧道围岩进一步产生可控的变形，从而释放围岩应力，减小支护结构荷载；新型衬砌可有效消除高地应力软岩公路隧道运营期间可能出现的局部围岩挤入产生的集中荷载、活动断层的错动引起的剪切变形、围岩的全断面压缩导致的荷载陡增等对隧道支护结构造成的破坏，为高地应力区软岩公路隧道的卸压及支护技术研究提供了新的思路。
Abstract
According to the poor stability of surrounding rock in high geostress soft rock highway tunnel, as well as the foam concrete material characteristics, such as waterproof, thermal insulation, shock resistance, high compressibility and ductility performance, numerical simulation method was adopted to analyze the pressure relief effect and influence factors of foam concrete in the high geostress soft rock highway tunnel. Furthermore, the influences of mechanics parameters of the foam concrete on the pressure relief were investigated. The value-taken ranges for optimum mechanical parameters of foam concrete were determined by variable control method. And then the pressure relief mechanism of the foam concrete was further analyzed. Based on the research achievements, a new type of foam concrete compound lining structure was proposed, namely the foam concrete compound lining. The results show that after adding foam concrete layer to high geostress soft rock highway tunnel, compared with ordinary supporting conditions, the release rate of surrounding rock stress is increased from 30% to 62%, the strength stress ratio of surrounding rock is increased from 1.92 to 3.74, and the load on the support structure of the tunnel averagely reduces 37.19 MPa. The values of optimum mechanical parameters of foam concrete are listed as follows. The range of elastic modulus is 400-800 MPa, that of yield stress coefficient k is 0.4-0.6, that of net water yield tensile stress coefficient kt 0.1-0.3, and that of uniaxial compressive strength 2.0-4.0 MPa. Taking advantage of high compression mechanical characteristics of foam concrete, a further controllable deformation of surrounding rock is deduced so as to release the surrounding rock stress and reduce the load on supporting structure. The new type of compound lining effectively eliminates the concentrated load by the squeeze of local surrounding rock, the shear deformation by active fault dislocation and the tunnel support structure failure led by sharp increase of load which is caused by whole section compression in high geostress soft rock highway tunnel during operation period. This provides a new idea for researches on pressure relief and supporting technology for high geostress soft rock highway tunnel.
关键词
隧道工程 /
泡沫混凝土复合式衬砌 /
数值模拟 /
卸压机理 /
支护结构
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Key words
tunnel engineering /
foam concrete compound lining /
numerical simulation /
pressure relief mechanism /
support structure
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中图分类号：
U457.3
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脚注
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基金
国家自然科学基金项目（51408067）；湖南省交通科技项目（201331）；湖南省教育厅科学研究重点项目（10A007）
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