全风化花岗岩改良土工程特性及其在高速铁路建设中的应用

【作者】 侯江波；

【导师】 王永和；

【作者基本信息】 中南大学 ， 道路与铁道工程， 2010， 硕士

【摘要】 目前,我国高速铁路正处于全面发展的建设时期,为了保证列车安全、舒适、平稳的运行,高速铁路对路基变形有严格的要求。新建武广客运专线沿线的相当一段线路穿越全风化花岗岩地段,A、B组填料缺乏,如果完全依靠外运合格填料,则既不经济,又不合理。为了保证工程能够高效、安全、经济的建设,必须对一些地段的花岗岩风化物进行改良,使其达到所要求的填料标准。本文在综合分析国内外全风化花岗岩研究现状基础上,通过理论分析、室内试验、和仿真数值分析等方法,对全风化花岗岩及其改良土的工程特性进行了研究,主要的研究内容和结论如下：(1)通过大量的试验研究表明,沿线大多数全风化花岗岩的物理力学性质差,内摩擦角小,吸水能力强,天然含水量大,粘结力小,结构松散,液塑限高,细颗粒含量较多,粉砂含量较高,风化花岗岩的强度指标不高,承载力低,如CBR值较低、回弹模量小等,除此之外,还有抗变形能力以及长期水稳性差等特征。(2)通过对不同掺加剂掺入量的改良土进行颗粒分析、液塑限、压缩特性、击实特性、水稳定性、强度特性等一系列试验,表明全风化花岗岩改良后土的塑性指数降低；颗粒分析曲线左移,颗粒粗化效果明显；击实曲线变平缓,驼峰变宽,这使得在施工中对含水量的控制范围变宽,施工质量更易把握；压缩性降低；渗透性下降；水稳定性提高；强度提高等。对于DK2097+560工点的黄色全风化花岗岩,掺加6%生石灰就能满足高速铁路对路基填料的要求；DK2116+200工点的红色全风化花岗岩,不宜采用生石灰改良,掺加6%水泥可以满足高速铁路对路基填料的要求。(3)运用MATLAB软件自身携带的BP网络工具建立模型对生石灰改良土无侧限抗压强度进行预测,并对影响因素进行分析。改良土存在一个最优的掺灰量,无侧限抗压强度随着压实度的增大而提高,泡水后强度会明显的降低,且强度随着龄期的延长而不断增长。(4)利用ANSYS软件建立路基仿真模型,研究改良土作为路基填料时,在不同车速、不同轮重下以及基床表层厚度改变时的动力特性。动力响应沿深度方向呈衰减的趋势,沿路基横向上,最大值出现在钢轨下或右线中心线上。在不同车速下,位移、速度、加速度、应力等物理量的响应并不是随着车速的增大而增大。在不同轮重下,位移、速度、加速度、应力等物理量的响应与轮重存在着拟线性函数关系,随着轮重的增加而增大。随着基床表层厚度的增大,移、速度、加速度、应力等物理量的响应值均有所减小。更多还原

【Abstract】 At present, it is in the constraction period of high-speed railway in China. To ensure the train safety, comfortability, smooth operation, there are strict requirements for the embankment deformation of high-speed railway. Wuhan-Guangzhou passenger rail line passes through a wide range of weathered granite, and lack of A、B group fillings, It is uneconomic and unreasonable for transporting qualified filler completely. To ensure that the project can be efficient safe and economic and reach the required standard of filling, It is necessary to improve weathered granite completely. Based on comprehensive analysis of research of weathered granite at home and abroad, engineering properties of weathered granite and its improvement were studied through theoretical analysis、laboratory test and numerical simulation methods. Main contents and conclusions are as fellows:(1) Through a large number of expermimental studies, it is shown that physical and mechanical properties of weathered granite are poor: smaller internal friction angle, better absorption capacity, bigger natural moisture content, smaller force, loosely, higher liquid and plastic limits, higher content of fine particles, higher silt content, lower strength index of weathered granite, lower carrying capacity, lower CBR value, smaller modulus,deformation resistance and long-term water stability are poor.(2) Through experiments of improved soil with different additive, including analysis of particle, liquid limit and plastic limit, characteristics of compression, characteristics of compaction, stability with water, properties of strength, it is shown that:plasticity index was decreased; curve of particle anslysis was to the left and coarsening effect of particle was obvious; curve of compaction became gently which made the control of water content in easier construction; compressibility and permeability were decreased; permeability decreased; stability with water was increased; strength was increased. For DK2097+560, improved soil with 6% lime was able to meet the requirement; but not suitable mixing lime for DK2116+200, improved soil mixing with 6% cement was able to meet the requirement of high-speed railway.(3) Unconfined compression strength was predicted with BP model of MATLAB software,and influencing factors of unconfined compression strength was analyzed. There was an optimal incorporation for improved soil mixing with lime. Unconfined compression strength increased with increase of degree of compaction, and decreased after soaking. The strength will grow with age.(4) Formed element simulation model of embankment from ANSYS. When improved soil was used as a filling, dynamic characteristics were studied at different speed、different wheelload and different thickness of surface-based bed. Dyamic response reduced with increase of the depth. Maximum appeared under the rail or the center line of the right line. Dynamic response did not increase with increase of speed. There was a linear function between dynamic response and wheelload. Response increased with wheelload. Dynamic respose reduced with thickness of surface-based bed increased.更多还原