不同应力路径下花岗岩残积土的强度和变形特性试验研究

发布时间：2018-05-27 18:19

本文选题：花岗岩残积土 + 应力路径　；参考：《湖南工业大学》2017年硕士论文

【摘要】：由于花岗岩残积土存在的地区的基础设施发展量的增加,需要更好的理解和量化花岗岩残积土的性质和行为,为花岗岩地区的基坑支护土石方工程、边坡地质灾害治理工程等岩土工程技术设计提供资料。以深圳市花岗岩残积土为研究对象,采用室内试验与数值模拟相结合的方法,研究不同应力路径条件对花岗岩残积土的强度与变形特性的影响。力学试验包含花岗岩残积土的基本物理性质试验、基质吸力强度试验、压缩试验下的结构变形特征试验、常规三轴压缩(CTC)试验、减压压缩(RTC)试验、恒定平均应力压缩(TC)试验、K0合并固结压缩试验、基于邓肯-张模型的数值计算与试验结果拟合研究,围压的范围为50kPa~500kPa。试验以三轴剪切为主,以探讨应力路径对花岗岩残基土强度与变形的影响。综合本研究的成果主要可分为四个部分,分别为:花岗岩残积土的强度特征方面,在不同围压条件下,饱和花岗岩残积土轴向伸张试验的抗剪强度及破坏应变明显低于轴向压缩试验,此一结果显示,若以轴向压缩试验取代轴向伸张试验,则强度将有被高估的现象。结构性花岗岩残积土的压缩变形特征方面,当含水量增加时,结构参数曲线较稳定,一些强化结构耦合已被破坏,土压力引起的土体密度的增加会使残留的花岗岩土体结构变异性降低,可以增加结构稳定性。三轴剪切路径下花岗岩残积土工程特性对比研究方面,湖南花岗岩残积土破坏时的主应力差要小于深圳花岗岩残积土破坏时的主应力差,而其体应变大于深圳花岗岩残积土的体应变,湖南花岗岩残积土的强度指标稍小于深圳花岗岩残积土的强度指标。基于邓肯-张模型的数值计算与试验结果拟合研究方面,当围压处于较高状态,改进的邓肯-张模型能准确的描述花岗岩残积土的应力-应变;当围压处于低压状态,改进曲线预测和测量曲线模型可以更准确地反映花岗岩残积土的应力-应变工程特性。如果今后对花岗岩残积土的研究更深入,这项成果可以延伸到研究其他区域的花岗岩残积土,作为对其结果普适性的探讨与延伸,这对花岗岩残积土这种特殊土的理解、掌握和应用具有现实意义和工程价值。
[Abstract]:Because of the increase of infrastructure development in the area where granite residual soil exists, it is necessary to better understand and quantify the nature and behavior of granite residual soil in order to support earthwork engineering in foundation pit in granite area. The technical design of geotechnical engineering such as slope geological hazard control project provides data. Taking the granite residual soil in Shenzhen as the research object, the influence of different stress path conditions on the strength and deformation characteristics of the granite residual soil was studied by means of laboratory test and numerical simulation. The mechanical tests include the basic physical properties of granite residual soil, the matrix suction strength test, the structural deformation characteristic test under compression test, the conventional triaxial compression CTC test, the decompression compression test and the RTC test. Constant mean stress compression test (TC0) combined with consolidation compression test is carried out. The range of confining pressure is in the range of 50kPa500kPa. based on the numerical calculation of Duncan-Chang model and the fitting of experimental results. Triaxial shear was used to study the influence of stress path on the strength and deformation of granite residual soil. The results of this study can be divided into four parts: the strength characteristics of granite residual soil, under different confining pressure conditions, The shear strength and failure strain of saturated granite residual soil are obviously lower than that of axial compression test. The results show that the strength will be overestimated if the axial tensile test is replaced by axial compression test. In terms of the compressive deformation characteristics of structural granite residual soil, when the water content is increased, the structural parameter curve is more stable, and some strengthened structural coupling has been destroyed. The increase of soil density caused by earth pressure will decrease the structural variability of the residual granite soil and increase the structural stability. In the aspect of comparative study on engineering characteristics of granite residual soil under triaxial shear path, the principal stress difference of granite residual soil in Hunan Province is smaller than that in Shenzhen granite residual soil failure. The bulk strain is larger than that of the granite residual soil in Shenzhen, and the strength index of the granite residual soil in Hunan is slightly smaller than that of the granite residual soil in Shenzhen. On the basis of the numerical calculation of Duncan Chang model and the fitting of experimental results, when the confining pressure is in a high state, the improved Duncan Chang model can accurately describe the stress-strain of the granite residual soil, and when the confining pressure is in the low pressure state, The improved curve prediction and measurement curve model can more accurately reflect the stress-strain engineering characteristics of granite residual soil. If further research on granite residual soil is carried out in the future, this result can be extended to the study of granite residual soil in other regions as an exploration and extension of the universality of its results, which is the understanding of granite residual soil as a special soil. It is of practical significance and engineering value to master and apply.
【学位授予单位】：湖南工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU41

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