应力路径

• Based on the available rule of variation in undrained shear strength during excavation , and the basic idea of the merchant model , this paper presents a constitutive relationship for saturated cohesive soils , capable of taking into account both stress path and time - dependent effect . it ' s named by the author as modified merchant model
  本文根据前人基坑开挖前后土的不排水抗剪强度变化规律的研究结果，并结合merchant模型的思想，提出了能同时考虑开挖应力路径和应力应变随时间变化的饱和粘土应力应变关系，亦可称之为修正merchant模型。
• The pore pressure , relationship of stress and strain , and the shear strength parameters obtained by unloading tests are different from those obtained by loading tri - axial tests . later the difference is analyzed in the respect of stress path and microstructure . at last , by use of a practical project the author compared and analyzed the two sets of shear strength parameters obtained by two different stress paths
  模拟基坑开挖的三轴试验得出了与常规三轴试验不同的孔隙水压力和应力-应变关系，这样得到的抗剪强度指标也低于常规三轴固结不排水加荷试验所得抗剪强度指标，继而本论文对抗剪强度指标的差异从应力路径的角度和微观结构的角度进行了分析。
• The soil ' s stress path has important effects on the retaining wall ' s lateral deformation and the soil ' s deformation during the excavation of foundation pit . an experiment simulating the soil ' s stress path behind the wall has been carried out with the stress - controlled triaxial instrument . the principle stress ratio keeps constant during consolidation and the soil samples are permitted to drain during unloading process
  利用应力式三轴仪对基坑开挖过程中围护结构后侧土体变形影响较大的因素：土体的应力路径进行了试验模拟，试验是在等主应力比固结后侧向卸荷而轴压不变的排水情况下进行的。
• With the data recorded by computer , the author studies the experiment progress in detail , which includes the development of pore press , strain , strength of the sand , etc . connecting the development of these phenomena with the development of stress path , the author finds new mechanism which can explain the phenomena in the experiment . what is more , according to the dynamic test of the sand , there appears a steady state at the last phase of the development of strain and stress path , in which the strength of the sand is studied because it is an important parameter in evaluating the stability of sand against liquefaction . secondly , the dynamic constitutive relation was studied through the dynamic tri - axial test
  本文首先采用目前国内较先进的微机控制动三轴仪，利用其可以适时采集和储存数据的优势，对砂土的实验过程进行了细致的分析，研究该过程中孔隙水压力发展、轴向应变发展以及它们与应力路径之间的关系，对饱和砂土的剪胀、剪缩和卸载体缩等多个方面进行了研究，探索了砂土的动力特性，分析了影响砂土抗剪强度的各种因素，这些因素既包括土本身的特性(土的密度、结构、级配、透水性以及初始状态等) ，又包括动荷载的特征(振动力幅值大小和振动频率等) 。
• Four types of constitutive models are provided by the code : linear elastic model , duncan - chung model , nonlinear elastic model taking stress path into account and modified three - element model . contact element is used to simulate possible sliding between soil and structure . with this code , analysis is made concerning the pore pressure dissipation , lateral deformation of the support , ground settlement , bottom heave , and variation in earth pressure and support forces ; both effects of consolidation and coupled effects of consolidation and creep are considered ; furthermore , different combinations of cohesion , permeability and excavation width are elaborated
  该程序采用了更合理的开挖荷载的计算方法，可以引入线弹性、邓肯张非线弹性、考虑应力路径的非线性弹性和修正三元件模型等四种本构模型，并在挡墙和土之间设置薄层接触面单元以模拟土体和墙体在开挖过程中可能产生的滑移。
• The conclusion is that it is more similar to practical soil pressure distribution if shear strength parameters are used which are obtained by the experiments that can simulate the actual process of active soil during excavation . so it is more reasonable to use shear strength parameters obtained by tri - axial experiments that can simulate the process of excavation in design of retaining structure
  本论文得出的结论是：用模拟基坑开挖实际应力路径的试验方法得出的抗剪强度指标计算基坑侧土压力分布，与实际情况更为接近，在基坑支护设计中，应该尽量使用模拟基坑开挖实际应力路径的三轴试验方法确定土体抗剪强度指标。
• Saturated sand are testes in the laboratory under the undrained cyclic loading condition with static - dynamic dual purpose triaxial compression test apparatus , which is designed under the cooperation of hohai university and marui co . ltd japan . the results indicate that the stress path approaches from a initial stress point to the failure lines as cyclic loading goes on , and eventually converges on a certain limiting stress path in the vicinity of the failure lines . the stress - strain curve , however , does not converge on a closed hystersis loop ; the shear strain rapidly increases in looser sand or gradually and continually increases in denser sand
  利用河海大学与日本圆井株式会社共同研制的新型的多功能静动三轴仪进行了饱和砂土循环扭剪不排水试验，研究表明，对于松砂，剪应变幅度快速地由微小增加到百分之几甚至百分之十几，对于紧砂，剪应变幅度逐渐地由微小增加到百分之几甚至百分之十几；经试验初步研究表明用初始有效平均正应力归一化的有效应力路径很好的一致性。
• First , considering the change of stress conditions in excavation slopes by means of triaxial equipment , the triaxial tests of three kinds of stress paths of q3 and q2 loess , including lateral unloading , keeping mean normal stress changeless and conventional axial loading , is carried out under different water content and consolidation stress conditions
  本文就黄土挖方高边坡工程问题，首先在三轴仪上考虑边坡开挖过程应力条件的变化，进行了q _ 3 、 q _ 2黄土不同含水量条件下围压卸荷、等p剪切及轴向加载三种应力路径的试验。
• Neglecting the influence of concrete stress - path , relative program is presented to make full - process analysis on compression - flexure members confined with cfrp in the compression zone , a key research is to analyze the effect of some parameters including axial compression ratio , thickness of cfrp , concrete strength on strength capacity and displacement ductility of reinforced compression - flexure members
  在忽略混凝土应力路径的影响下，编制相应程序对碳纤维布粘贴钢筋混凝土压弯构件进行了全过程分析及相关参数研究，并把计算结果与试验结果进行了对比，两者吻合较好。