石灰处理软土路基深度对土基回弹模量影响研究

发布时间：2018-01-16 14:21

本文关键词：石灰处理软土路基深度对土基回弹模量影响研究　出处：《河北工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：土基回弹模量是路面结构设计的重要参数,较高的土基模量也是路面结构承载力的重要保证。软土路基的土基回弹模量往往难以达到规定的要求,给路面结构的承载能力和整体稳定性带来不良影响。利用石灰处理软土路基以提高土基回弹模量是工程中经常采用的技术措施。由于软土含水量、土质特性、石灰掺量、石灰处理路基深度和压实度等因素对路基顶回弹模量都有很大影响,造成在实际工程中石灰处理软土路基盲目性和随意性很大。本文的主要研究工作如下:(1)调查了天津地区软土的分布规律以及其物理力学指标,软土路基常见处理方式,以及天津市城区的交通轴载情况。调查结果显示,天津市城区道路交通量非常大,货车超载现象非常普遍,软土路基虽经过各种方式改良,但路面结构还是容易发生破坏。(2)通过室内试验,系统分析了不同因素对经石灰处理后软土的CBR值、回弹模量、抗压强度及劈裂强度等力学性能的影响。试验结果表明,对于不同含水量的软土,8%~12%石灰含量的石灰土的各项力学性能指标均随压实度的增大而增大,随含水量的增大而减小;经过改良后的软土可以用于路基铺筑;不同土质软土由于组成成分有所不同,石灰对其力学性能的改良效果也有所差异,设计施工时应根据土质做出调整。(3)计算分析发现现行规范中的当量回弹模量换算公式不适用于低模量比的石灰土路基。根据弹性层状体系理论以及弯沉等效原则,通过Kenpave程序及Minitab统计分析软件,回归出一个荷载作用半径为15cm的换算公式。修正后的新公式适用于石灰土与原状软土模量比小于8且石灰处理厚度大于20cm的路基顶当量回弹模量换算。误差验证表明其精度和可靠性非常高。最后通过试验路路基弯沉检测验证了回归公式。(4)按照《城市道路路基设计规范》(CJJ 194-2013)的对路基回弹模量的要求,通过本文回归的换算公式分别计算出软土路基在不同含水量、石灰含量、压实度情况下的合理处理深度;计算了各方案的工程费用,并采用美国AI设计法计算了各方案道路使用寿命;通过响应面优化法对工程费用和使用寿命两个指标进行优化,得到了软土路基在不同含水量下的最佳处理方式。
[Abstract]:The modulus of resilience of soil foundation is an important parameter of pavement structure design, and the high modulus of soil foundation is also an important guarantee of the bearing capacity of pavement structure. The modulus of resilience of soil foundation of soft soil subgrade is often difficult to meet the prescribed requirements. It is often used in engineering to use lime to treat soft soil subgrade in order to improve the resilience modulus of soil foundation. Because of the water content of soft soil, soil quality characteristics. The content of lime, the depth of roadbed treated with lime and the degree of compaction have great influence on the elastic modulus of the top of subgrade. The main research work of this paper is as follows: 1) the distribution law of soft soil in Tianjin area and its physical and mechanical indexes are investigated. The investigation results show that the traffic volume of Tianjin urban area is very large, and the phenomenon of overloading of freight cars is very common. Though the soft soil subgrade is improved in various ways, the pavement structure is still liable to be destroyed. (2) through laboratory tests, the CBR value and resilience modulus of soft soil after lime treatment are analyzed systematically. The effect of compressive strength and splitting strength on the mechanical properties. The test results show that the soft soil with different moisture content. The mechanical properties of lime soil with 12% lime content increased with the increase of compaction and decreased with the increase of water content. The improved soft soil can be used for subgrade paving. Because the composition of different soil soft soil is different, the improvement effect of lime on its mechanical properties is also different. The design and construction should be adjusted according to the soil quality. It is found that the equivalent elastic modulus conversion formula in the current code is not suitable for lime soil subgrade with low modulus ratio, according to the theory of elastic layered system and the equivalent principle of deflection. Through Kenpave program and Minitab statistical analysis software. A conversion formula with a load action radius of 15 cm is obtained. The new formula is suitable for replacing the equivalent elastic modulus of the top of roadbed when the modulus ratio of lime soil to undisturbed soft soil is less than 8 and the thickness of lime treatment is more than 20 cm. The error verification shows that its precision and reliability are very high. Finally, the regression formula is verified by the test road subgrade deflection test. 4) according to CJJ194-2013, the requirements of subgrade resilience modulus. The reasonable treatment depth of soft soil roadbed under different water content, lime content and compaction degree is calculated by the conversion formula of regression in this paper. The project cost of each scheme is calculated, and the road service life of each scheme is calculated by American AI design method. Two indexes of engineering cost and service life are optimized by response surface optimization method, and the optimal treatment method of soft soil subgrade under different water content is obtained.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416

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