填土-减载-基础相互作用的高填黄土明洞衬砌结构力学特性及其选型研究

To meet the urban and traffic construction land demand of the loess plateau areas, there is an increasing number of the high fill loess open cut tunnel. The interaction of filling, load reduction and foundation changes the mechanical characteristics of lining structure. This subject adopts the combination of laboratory test and numerical simulation, the change rule of earth pressure around the high fill loess open cut tunnel and lining structure mechanical characteristics are studied under the interaction of filling, load reduction and foundation. And through the section optimization design, it can get the lining section forms which are suitable for high fill loess open cut tunnel after load reduction. On the premise of the similarity theory, considering the interaction of filling height, load reduction mode and foundation stiffness, simulating a practical construction by layered filling and step loading. The model test results and numerical analysis results are verified mutually, confirming the reliability of the test datas and the rationality of the numerical simulation key parameters. Then make a systematic finite element calculation, the change rule of earth pressure around the high fill loess open cut tunnel and lining structure mechanical characteristics are obtained under the interaction of filling, load reduction and foundation. Finally, considering safety, durability, economy and feasibility, through the structure selection, combining with laboratory test and numerical analysis results, it can acquire the lining section forms which are fit for the high fill loess open cut tunnel under the interaction of filling, load reduction and foundation.

为满足黄土高原地区城市及交通建设用地需求，高填黄土明洞日趋增多。填土、减载、基础相互作用改变了衬砌结构受力特性。本课题采用室内试验和数值模拟相结合的方法，研究填土-减载-基础相互作用下，高填黄土明洞周围土压力和衬砌结构力学特性变化规律，并通过截面优化设计，进一步得到适合减载后高填黄土明洞衬砌结构的断面型式。以相似理论为前提，考虑填土高度、减载模式、基础刚度相互作用，通过逐层填土、分级加载模拟实际施工过程；将模型试验和数值分析结果相互验证，确定试验数据的可靠性和数值模拟关键参数的合理性；随后进行系统的有限元计算，获得填土-减载-基础相互作用下的高填黄土明洞周围土压力和衬砌结构力学特性变化规律；最后，考虑安全、耐久、经济及可行性，通过结构型式比选，结合室内试验、数值分析结果，得到适合填土-减载-基础相互作用的高填黄土明洞衬砌结构断面型式。

随着“一带一路”和“西部大开发”战略的深入推进，中国西北地区的经济发展逐渐加速，为了进一步促进西北地区经济快速可持续发展，完善和推进交通基础设施建设至关重要。然而，西北地处黄土高原，山高谷深、沟壑纵横，土地资源稀缺与发展交通建设的矛盾日益凸显。因此，通过人为削山、填沟以增加建设用地已成为目前缓解用地紧张的主要方法，这就使高填黄土明洞在实际工程建设过程中得到了广泛应用，而对于明洞而言，填土性质、减载材料、基础之间的相互作用对其衬砌结构受力具有较大影响。本项目采用室内试验和数值模拟相结合的方法主要研究了：（1）在填土-减载-基础相互作用下，高填黄土明洞周围土压力和衬砌结构力学特性变化规律；（2）通过截面优化设计，进一步得到适合减载后高填黄土明洞衬砌结构的断面型式。（3）考虑填土高度、减载方式、基础刚度相互作用，通过逐层填土、分级加载模拟实际施工过程，并将模型试验和数值分析结果相互验证，确定试验数据的可靠性和数值模拟关键参数的合理性；（4）通过数值模拟，探究填土-减载-基础相互作用下的高填黄土明洞周围土压力和衬砌结构力学特性变化规律，得到适合填土-减载-基础相互作用的高填黄土明洞衬砌结构断面型式。