【作者】 唐迎春；

【导师】 欧孝夺；

【作者基本信息】 广西大学 ， 结构工程， 2013， 博士

【摘要】 南宁市轨道交通工程较多路段将穿越膨胀岩区域,该区域主要为第三系膨胀性泥岩,其成岩时间短,胶结程度差,具有显著吸水膨胀和失水收缩的特性。膨胀岩的胀缩性将对盾构管片内力和变形产生影响,膨胀岩与盾构管片的相互作用研究是一个全新的工程难题,值得深入研究。本文以南宁轨道交通一号线穿越膨胀岩区域为靶区,通过资料收集及综合分析,采用室内试验、数值计算及大型物理模型试验等综合研究方法,开展了膨胀岩与地铁隧道结构相互作用研究。通过现场调研和资料整理,剖析了南宁第三系泥岩的工程特性,揭示了南宁第三系膨胀泥岩的分布及构造特殊性,并对其物理指标、力学指标及膨胀特性指标进行了分析研究。基于区域工程地质条件、隧道上覆土层特征、水文地质条件等因素,对南宁轨道交通一号线膨胀岩区段进行岩层组合特性研究,提出了岩层组合模型。通过机理试验,研究了膨胀变形的时程特性和膨胀力影响因素及其关系。提出了综合考虑干密度和初始含水率双因素对膨胀力影响,获得膨胀力与干密度、初始含水率之间关系：P(ω,ρd)=-265.012pd+21.453ω+34.583e(2.3ρd-0.1ω)-142.294并开展微变形条件下膨胀力试验研究,提出了膨胀力随着微变形变化的规律,即微变形膨胀力与对应的零变形膨胀力之比随变形率增大而呈指数变小,得到膨胀力比值与微变形率关系式为：P/P0(ε)=C·eD·ε其中C,D为拟合常数。在此基础上,针对代表性岩层组合模型采用荷载-结构法,并考虑膨胀岩层施加范围对盾构管片的影响,研究不同情况下膨胀力对盾构管片内力及位移变形规律。研究表明：盾构管片受力最不利岩层组合模型是底部为膨胀岩,上部为非膨胀岩层的第Ⅲ类岩层组合；并研究得出了管片弯矩和变形随着底部膨胀围岩厚度的变化规律,即弯矩和变形随着盾构管片底部与膨胀围岩接触厚度夹角θ的增大呈现先增大后减小的趋势,其中最大正弯矩在θ=45°时出现,最大负弯矩和最大变形出现在0=30°。考虑膨胀力随着接触变形而衰减的修正模型进行数值计算,改进后计算模型能够更准确反映膨胀力对管片的内力和变形影响规律,考虑膨胀力折减后其内力和变形值均有所减小结合计算分析结果,构建膨胀岩围岩与盾构管片大型模型试验,分别围岩介质中埋设湿度传感器、土压力盒,在管片结构中埋设应变计和百分表,通过改变重塑膨胀性围岩的含水率以模拟膨胀力施加,实测盾构管片和围岩的内力、变形情况,研究盾构管片结构受力、变形规律,实测数据与数值模拟结果相吻合。基于南宁第三系膨胀性泥岩特殊和复杂的工程特性,在数值和物理模型研究基础上,解决了该区盾构设计中如何考虑膨胀围岩影响的难题,给出了在膨胀围岩下盾构管片的膨胀力施加范围以及膨胀力施加方式,优化了设计计算模型,可以更准确地反映盾构管片的实际受力情况。该成果可为南宁市涉膨胀岩区段地铁建设提供理论指导,也为国内外类似膨胀岩区域的地铁建设提供借鉴。更多还原

【Abstract】 There are many swelling rock areas will be across by Nanning rail transit, which is mainly consist of the tertiary mudstone. This tertiary mudstone has the characteristics of short digenetic time, poor degree of consolidation and significantly in water swelling and water loss shrinking. The swell-shrink characteristics of the swelling rock will influence on the internal force and deformation of the shield segment. The research on the interaction of the swelling rock with the shield segments become a new engineering problem, which is worth in-depth study. Taking the swelling rock area across in Nanning rail transit line1as the target, through data collecting and comprehensive analyzing, using laboratory test, numerical calculation and comprehensive research methods, large-scale physical model test, the interaction research on the swelling rock and the subway tunnel structure was carried out.Through site investigation and data compilation, analyzes the engineering properties of the tertiary mudstone in Nanning, reveals the distribution and the structure characteristics of the swelling tertiary mudstone in Nanning, and the physical index, mechanical index and the swelling feature index were analyzed. Based on the regional geological conditions, the covering soil characteristics of the shield tunnel and hydrogeological conditions of Nanning rail transit line1where across the swelling rock area, the strata combination characteristics of swelling rock section were studied and the rock combination model was put forward. Through mechanism test, the calendar features of the swelling deformation and the expansion of swelling force influencing factors and their relationships were studied. Consideration both the dry density and the initial moisture content of double factors impact the swelling force, got the relationship between them:P(ω,ρb)=-265.012ρd+21.453ω+34.583e(23ρb-01ω)-142.294Then the experiment research on micro expansive force under the condition of deformation were taken, proposed the change law of the expansion forces as the micro deformation, that the ratio of the expansion force of micro deformation to the corresponding zero deformation lessen as the micro deformation rate increase. The equation of the ratio of the expansive force and the micro deformation rate was obtained as follow:P/P0(ε)=C·eD·ε, C, D for fitting constants. On the basis of this analysis, the representative rock combination model for load-structure method, and considering the applying range of the influence of shield segments expansive rock, the expansive force under the condition of the segment internal force and deformation law were studied. Research shows that the class Ⅲ as the most adverse combination model, which the bottom of the shield segment were swelling rock, the upper of non-swelling rock. The results show that the moment and deformation of the segment change along with the thickness of the bottom swelling rock, which increases at first then decreases with the angle θ increasing, When the contact angel θ between expansion force and segment equal45°, positive bending moment was max, the maximum negative bending moment and maximum deformation happened When the contact angel θ equal30°Considering expansion force as the contact deformation and the attenuation correction model for numerical calculation, the improved calculation model can more accurately reflect the expansive force influence law of internal force and deformation of the segments after considering expansion force reduction value of internal force and deformation were reduced.Based on the special and complex properties of the tertiary mudstone in Nanning, on the basis of both numerical and physical model research, the problem about how to consider the effect of swelling rock surrounding the shield in the design were solved. The swelling force applied range and exerting mode for shield segments of the swelling rock surrounding were given, and the design and calculation model was optimized which can be more accurately reflect the actual stress of the segment. The results could be used in Nanning where the swelling rock section of subway construction to provide theoretical guidance and may benefit to the subway construction for both the domestic and foreign similar swelling rock areas for reference.更多还原