营口地区软土的流变模型

根据室内三轴剪切流变试验的结果,研究了营口地区淤泥质软土的流变特性.结果表明,该类软土具有明显的变形时效性及其在不同应力水平下的蠕变特性.通过分析蠕变曲线的规律,选择了西原模型和双阀值模型这两种理论模型来描述软土的流变特性.由非线性拟合的结果得出其扩展的理论模型精度更高及双阀值模型比西原模型精度更高的结论,同时还指出软土的非线性特性对参数拟合的影响.最后,选择了Singh Mitchell模型及其修正模型对软土进行经验拟合,并达到了良好的精度.     

基坑开挖软土流变特性的试验研究

考虑基坑开挖土体卸载的应力特点。在室内利用三轴仪模拟这一应力路径，对基坑中软土的流变特性进行了试验研究，推导了蠕变方程。总结出了此种情况下土的流变特点．     

宁波软土流变试验及经验模型

为了研究宁波软土的流变特性及经验模型,进行一维固结流变试验和三轴排水流变试验,并采用西原模型拟合模型参数.试验对比分析表明,固结试验的侧限作用会阻碍试样流变的发展,应力-应变等时曲线偏向应力轴,而三轴流变试验试样的流变能够得到充分地发展,应力-应变等时曲线偏向应变轴,能够更好地体现软黏土的流变性状.将一维西原模型应力-应变关系扩展到三维,采用修正剑桥模型屈服函数描述材料的塑性屈服.推导荷载恒定时土样的轴向应变计算公式,根据三轴排水流变试验结果进行曲线拟合,确定西原模型参数.结果表明,该模型能够较好地符合宁波软土的流变规律.     

节理岩体蠕变特性试验研究

某矿地处高应力区,岩体破碎、节理裂隙发育,且具有显著流变性,开挖与维护难度极大,给正常生产和工程安全带来巨大挑战,因此,岩体蠕变规律研究成为一项重要的基础工作,为此,根据试验要求及实际取样情况,对该区节理岩体的蠕变特性进行了试验研究.在对试验数据深入分析和对比研究的基础上,选取Burgers 模型来描述岩体的蠕变特性,并编制了Burgers蠕变模型试验数据处理程序,对蠕变模型参数进行了拟合和加权平均取值.试验结果表明,Burgers蠕变模型能较好的描述岩体的蠕变特性.     

煤岩蠕变特性试验研究

利用自行研制的压缩蠕变试验装置,对煤样进行了蠕变试验研究,根据试验结果,将蠕变强度与瞬时强度进行了比较,拟合得出了蠕变曲线经验公式,认为蠕变试验曲线接近对数规律,建立了蠕变理论模型,并求出了相应的参数.     

煤岩蠕变特性试验研究

利用自行研制的压缩蠕变试验装置,对煤样进行了蠕变试验研究,根据试验结果,将蠕变强度与瞬时强度进行了比较,拟合得出了蠕变曲线经验公式,认为蠕变试验曲线接近对数规律,建立了蠕变理论模型,并求出了相应的参数.     

水环境中高水速凝材料蠕变特性及其流变模型

为了研究高水速凝材料作为采空区充填体是否具有长期、有效控制上覆岩层移动变形的能力,对高水速凝材料进行了瞬时物理力学试验和微观扫描分析,及利用重力连续加载方式进行了干燥和水环境中的蠕变试验,根据蠕变试验曲线进行了高水速凝材料的流变模型辨识和参数反演。结果表明：高水速凝材料在空气环境中容易丧失强度,水环境条件工作更利于提高其自身结构和承载力的稳定性;高水速凝材料的长期蠕变稳定性取决于荷载水平是否达到其材料的长期屈服强度;Burgers流变模型能更好地描述水环境中高水速凝材料这种“类”软岩的蠕变特性。     

海相软土三轴流变试验研究

采用应力控制式三轴流变仪对连云港海相软土进行试验,根据分级加载的方法,记录时间和土体的变形量、孔隙压力值,得到土体的应力-应变-时间关系曲线,从软土流变性质上分析解决软土地基工程事故,对海相软土的地基处理、海相软土地区高速公路和房屋建筑的设计施工有着重要的理论意义和工程指导意义.     

Simulation of rheological behavior of asphalt mixture with lattice model

A three-dimensional(3D) lattice model for predicting the rheological behavior of asphalt mixtures was presented.In this model asphalt mixtures were described as a two-phase composite material consisting of asphalt sand and coarse aggregates distributed randomly.Asphalt sand was regarded as a viscoelastic material and aggregates as an elastic material.The rheological response of asphalt mixture subjected to different constant stresses was simulated.The calibrated overall creep strain shows a good approximation to experimental results.     

Rheological behavior of basalt fiber reinforced asphalt mastic

The characters of basalt fiber are analyzed and compared with commonly used fibers. The rheological behaviors of the basalt fiber reinforced asphalt mastic are investigated by the dynamic shear rheological tests and the repeated creep tests. The results show that basalt fiber has excellent reinforced performances, such as high asphalt absorption ratio, low water absorption ratio, high tensile strength, high elastic modulus and high temperature stability. The rutting factor of the fiber reinforced asphalt mastic is higher than the plain asphalt mastic and the reinforced effects are more remarkable under high temperature. The rheological performances of the asphalt mastic demonstrate a good linear relationship between different temperature and loading frequency. The creep stiffness modulus of the asphalt mastic at different loading time can be expressed by power function. Improved Burgers model is used to represent the rheological behaviors of the asphalt mastic with basalt fiber and the model parameters are estimated.     

Effects of stress conditions on rheological properties of granular soil in large triaxial rheology laboratory tests

In order to study the rheological properties of red stone granular soil,a series of rheological experiments were executed on large tri-axial rheological apparatus.Under 100,200 and 300 kPa confining stress conditions,the rheological tests were carried out.These experiment results showed that the stress conditions,especially the stress level were the critical influencing factors of the rheological deformation properties.Under the low stress level(S=0.1),the granular soil showed the elastic properties,and there was no obvious rheological deformation.Under the middle stress level(0.20.8) creep curves showed the non-linear viscous plastic rheological properties.Especially,under the stress level of S=1.0,the accelerated rheological phase of creep curves occurred at early time with a trend of failure.The stress level had obvious effects on the final rheological deformation of the soil sample,and the final rheological deformation increments nonlinearly increased with stress level.The final rheological deformation increment and step was little under low stress level,while it became large under high stress level,which showed the nonlinearly rheological properties of the granular soil.The confining pressure also had direct effects on final rheological deformation,and the final rheological deformation linearly increased with confining pressure increments.     

河道淤泥气泡混合轻质土剪切流变特性及模型

利用剪切流变试验对以水泥为固化剂的河道淤泥气泡混合轻质土的流变特性进行了试验研究。试验结果表明,经固化处理的河道淤泥气泡混合轻质土在荷载作用下具有类似于硬粘性土的流变特征。剪切流变可以分为3个阶段：在剪应力水平较低时,剪切流变曲线呈衰减稳定型;随着剪应力水平的提高,剪切流变曲线呈非稳定的等速型;当剪应力水平增大到一定程度时,剪切流变曲线呈加速型。河道淤泥气泡混合轻质土的流变性随着混合轻质土强度的提高而降低。根据试验所呈现的剪切流变规律,可以发现河道淤泥气泡混合轻质土的剪切流变符合七元件黏弹塑性剪切流变模型,模型能够比较好地描述河道淤泥混合轻质土在各种剪应力水平下的衰减、等速以及加速流变过程。     

粉砂质泥岩的三轴蠕变试验研究

为了揭示分布于北天山中西部的志留系上统紫红色粉砂质泥岩的蠕变特性,为拟建于此的某深埋越岭特长隧洞的设计、施工,以及长期稳定问题评价提供依据,通过钻孔取样进行了三轴蠕变试验研究。试验在5台岩石三轴蠕变试验机上进行,围压分别为0、5、10、20、30 MPa。试验取得以下主要成果：1）揭示了这类黏土岩的蠕变特性可用西原模型加以描述,并由此建立了蠕变本构方程;2）采用曲线求参法求解了各流变参数;3）采用叠加原理与等时曲线法获得了岩石的长期强度;4）各蠕变参数随围压的升高而增大,长期强度较瞬时强度降低的幅度亦随围