【作者】 廖亚林；

【导师】 杨和平；

【作者基本信息】 长沙理工大学 ， 道路与铁道工程， 2011， 硕士

【摘要】 在膨胀土边坡工程中,国内铁道、公路、水利等部门曾多采用土钉墙、重力式挡土墙和抗滑桩三大加固措施,并采取短锚杆喷射混凝土和浆砌片石等全封闭措施对路堑边坡进行坡面防护,但工程处治的实际效果是刚性支护结构发生破坏的现象屡见不鲜。为进一步探讨刚性挡土墙是否适合支护膨胀土边坡,本文针对墙体绕基底转动的变位模式,尝试开展了以下分析研究:第一,完成了广西百色膨胀土样的室内固结快剪、膨胀力及固结试验,确定了土样的相关力学指标,建立了膨胀力与起始含水率、膨胀变形量的关系,为推导土压力公式和开展数字分析做好准备。第二,基于对已有研究成果及室内试验结果分析,将膨胀力沿墙背土层深度变化的量化式引入土压力水平层分析法中,推导了挡墙土压力公式;并编写matlab程序进行计算,获得土体增湿后的土压力大小、土压力作用点高度及其随墙顶位移的变化;根据墙身稳定要求,反算不同墙顶位移下考虑膨胀力作用时墙身所需截面尺寸,并与正常填土挡墙的算例进行对比,获得刚性墙支护膨胀土适用性的量化指标:填土初始含水率较小且增湿后,土压力显著增大,其作用点位置也明显升高;若挡墙静止,较正常填土墙顶宽需增大2.6倍才能维持墙身稳定;墙顶位移量需15cm时膨胀力作用才完全消散;第三,运用FLAC软件的热、力学耦合分析功能,用材料温度场等效模拟土体湿度场,考虑大气影响深度范围内膨胀土体的增湿条件,对比分析了土体增湿前后墙与土体间的相互作用,数值模拟结果也表明:土体增湿后土压力强度峰值明显增大,挡土墙和墙后土体产生显著的侧向位移,需很大限度地增大截面尺寸才能保证膨胀土挡墙的稳定。因此,从安全和经济性考虑,刚性挡墙不适合支护膨胀土堑坡。最后,运用灰色局势决策理论分析了柔性支护、刚性支护及刚柔结合三种膨胀土堑坡处治方案的优劣性,对比工程成本、施工难易及生态环保等指标,得出柔性支护处治膨胀土堑坡为最佳方案,刚性支护方案最差。更多还原

【Abstract】 In the slope project of expansive soils, although reinforcement measures including soil nailing wall、gravity retaining wall and anti-slide pile and major protective measures including full closed short bolt shotcrete and mortar flag stone for expansive soil slope reinforcement and protection were used by the departments at home and abroad including railway、highway and water conservancy, the failure phenomena of rigid protection in practical project.For investigating the expansive soil slope supported by rigid retaining walls, according to movement modes of expansive soil retaining walls rotated basement, the paper analyzed as follows:Firstly, the samples correlated mechanical properties were determined by the consolidated quick shear test、expansive force test and consolidation test the Bai-se expansive soil of the Bai-se expansive soil. And then, the variation relationships of the expansive force with initial water content and expansive deformation were established to the derivation of earth pressure formulas and numerical analysis.Secondly, the mathematical expression of the variation relationship between the expansive force and depth of soil layer in the climate influenced layer was proposed by summarizing the result of the laboratory test and existing research results. Then, the mathematical expression was introduced to deduce the calculation formula of the soil pressure of expansive soil retaining walls in the rigid retaining walls horizontal layer analysis method, the calculation program of Matlab was compiled to analyze the value of earth pressure、height of earth pressure acted point and the variation of wall displacement resulting from the expansive soil after moistening. According to the stability requirements of the retaining wall, the wall body section size under the expansive force in the different of wall displacement was reverse calculated, and the quantitative indexes of applicability analysis of expansive soil retaining walls were obtained by comparing with wall body section size without expansive force. The test results are showed that the earth pressure acted point rose markedly with the earth pressure increasing after expansive soils water content was less humidifying. When the expansive soil retaining walls was stationary, the wall body section size were needed to increase 2.6 times for the retaining walls stability, and only the deflection on the top of wall reaching 15cm the expansive action would be completely dissipated.Thirdiy, according to the material temperature field equivalent simulated the soil humidity field of FLAC, and the expansive soil humidifying conditions in the climate influenced layer was considered, the interaction between the soil and the retaining wall was comparative analysis. the numerical simulation results are showed the earth pressure rose markedly in the climate influenced layer after moistening, and the remarkable lateral displacement was produced between the retaining walls and the soils behind retaining wall. Considering the security and the project costiy, the rigid retaining wall is unsuitable to support the expansive soil slope.Finally, the advantages and disadvantages of expansive soil slope treatment program such as flexible supporting and rigid and rigid-flexible support were analyzed by gray theory, In considering the project cost, difficulty of construction and ecological protection, compared the flexible support is the best way of treating expansive soil slope, rigid support is the worst.更多还原