Study of dilatancy behaviors of calcareous soils in a triaxial test     

Xing Wang  Xin-Zhi Wang  Yue Qin 《Marine Georesources & Geotechnology》2013,31(9):1057-1070

Abstract

In this article, the dilatancy of calcareous soil is studied systematically based on triaxial consolidation drainage shear tests, and the difference in dilatancy between calcareous soil and siliceous soil is also investigated. It was found that: ① Calcareous soil experience obvious dilated deformation. Dilatancy tendency increases with increasing related density and decreases with increasing confining pressure. ② The volumetric strain rate initially increases from negative to positive. After it reaches a maximum, there is a small decrease in the volumetric strain rate, but it is still greater than zero, and the stress-strain curves are of softening type. ③ For the same condition, the dilatancy deformation of calcareous sand begins later than that of siliceous sand, and the volume compression before dilatancy is also larger for calcareous sand. ④ The critical state alone cannot accurately describe the entire deformation process of soil, and it is proposed that the phase transformation state be added to the standard method used to assess soil dilatation and contraction. ⑤ Based on the statistical analysis of experimental data, mathematical relationships were established between void ratio, relative density, and effective confining pressure of phase transformation state and critical state, respectively.

• Highlights

• Reports results from a well-designed experiment that includes a good amount of samples and data.

• Effects of relative density and effective confining pressure on deformation mode and mechanical properties of calcareous sand are evaluated.

• The difference in dilatancy between calcareous sand and siliceous sand was compared

• The phase-transformation state and critical state were compared with the axial strain, volumetric strain and deviatoric stress.

• Using phase-transformation void ratio and critical void ratio to describe the whole deformation process of calcareous sand is proposed.

• The mathematical expressions of phase-transformation void ratio and critical void ration were given, respectively.

  相似文献   

Test and Numerical Analysis of the Constitutive Relation of a Diatomaceous Soft Rock     

《Marine Georesources & Geotechnology》2013,31(3-4):183-200

A kind of diatomaceous soft rock and its constitutive model are studied in this article. Based on Yin and Graham's (1999) 3-D elastic viscoplastic constitutive model, the formulation under a triaxial stress state is established, and it is used to simulate the time-dependent stress-strain behavior and effective stress path of consolidated undrained triaxial tests of both normally consolidated and overconsolidated soft rock. The comparison between the model predictions and measured results shows that their agreement is good. This demonstrates that the constitutive equation established here can be used to simulate the time-dependent stress-strain behavior of the soft rock under triaxial stress condition.  相似文献   

承船厢吊耳的局部应力分析研究   总被引：1，自引：0，他引：1  

张世联  徐汉涛  杨文华  韦疑男 《海洋工程》1999,17(3)

承船厢是升船机系统中的一个重要结构物,该结构物中的关键结构吊耳是否有足够的强度,应力分布是否合理将直接影响升船机系统工作的可靠性。在对吊耳进行光弹性试验基础上,对吊耳的光弹性模型进行有限元分析,通过结果的分析比较,确定承船厢吊耳的局部结构的计算可靠程度  相似文献   

堤下爆炸法处理淤泥地基新工艺的理论、实验及工程应用(Ⅱ)桩对桩间抛石棱体下爆炸挤淤的动力响应     

杨振声  燕琳  张加华 《海洋工程》1999,17(2)

本文是堤下爆炸法处理淤泥地基新工艺的研究及应用的第二部分,着重介绍该工艺应用于桩间棱体的挤淤时,爆炸冲击波和淤泥、石块运动对桩的作用。计算和检测表明,桩体的安全是可以得到保证的。  相似文献   

中国对虾类淋巴器结构观察及功能探讨   总被引：2，自引：0，他引：2  

刘晓云  刘树青  姜明 《中国海洋大学学报(自然科学版)》1999,(1)

中国对虾类淋巴器位于肝胰腺前方,左右各一个,呈白色,半透明状。它由触角动脉上分出的动脉血管不断分叉、迂曲,形成了一个外包透明结缔组织膜,内部充满小管的组织结构。类淋巴器的小管依其发育时期和功能不同表现为３种不同的形态。其中,第二种小管管壁具有生成和释放血细胞的功能。在类淋巴器中,观察到小颗粒细胞,大颗粒细胞和无颗粒细胞。小颗粒细胞具有吞噬功能,在受到抗原刺激时可以胞吐方式释放细胞中的电子致密颗粒。大颗粒细胞无吞噬功能。无颗粒细胞又可分为巨噬细胞样无颗粒细胞和淋巴细胞样无颗粒细胞。前者具有很强的吞噬能力,而后者在受到抗原刺激时,可表现出类似浆细胞样分化的细胞特征。  相似文献   

双层自行式施工平台结构强度评估          下载免费PDF全文

赵鹏飞  夏利娟  杨秀礼  王磊 《海洋工程》2017,35(4):29-35

以一种适合港口施工作业的新型自行式施工平台为研究对象,介绍了该型平台特点与工作流程。根据其工作行走状态及载荷特点,使用有限元方法分析多工况下平台的结构屈服强度,并根据规范进行平台和桩腿结构屈曲评估。该平台由上下两层平台组合而成,针对此平台上下层接触的特点,探讨了不同类型MPC,ABAQUS接触分析的结构强度计算结果。研究对自行式海洋平台设计具有借鉴意义,并对平台结构强度计算研究提供了一定参考。  相似文献   

Fixed point automatic interpretation of bender-based G0 measurements     

《Computers and Geotechnics》2017

We present a new model updating technique for the automatic calculation of the small strain shear modulus of geomaterials, based on bender element experiments. The technique searches for the shear modulus that maximizes the correlation between the output signal obtained from the experiment and the output signal acquired from its computational simulation. Instead of conventional extremum finding algorithms, a fixed point technique is used to update the shear modulus at each iteration. This option increases substantially the attraction basin of the absolute maximum correlation and improves the convergence of the algorithm.  相似文献   

改进的SCS模型在黑龙江省中小流域径流模拟中的应用          下载免费PDF全文

顾雯  李丽  石晓丹  满霞玉  申瑞凤 《水文》2017,37(3):70-74

针对黑龙江省中小流域特征,以烟筒山、铁力、岔林河桥、中和4个流域为研究区,引入初损比例m和系统偏差系数k两个参数对SCS模型进行改进,探讨改进的SCS模型在模拟黑龙江中小流域降雨-径流的可行性。结果表明:改进的SCS模型模拟的效率系数均为0.80以上,可以有效的模拟黑龙江省中小流域的降雨-径流。  相似文献   

基于DEM的不同地貌类型区小流域划分及分布特征研究——以贵州省赤水河流域为例     

吕一兵  张斌  陈智虎  李亦秋  杨广斌 《测绘通报》2017,(9):110-115

小流域已经成为水土流失治理、生态系统修复等研究工作的重要地理单元。本文以贵州省赤水河流域为研究对象,探索我国西南典型喀斯特与非喀斯特地貌混合分布区小流域划分方法及小流域分布特征,基于DEM提取小流域边界,利用1∶5万地形图进行修正,并结合野外调查和地质、水文数据验证,最终将贵州省赤水河流域划定了753个小流域。其中,喀斯特地貌区小流域个数358个,喀斯特+非喀斯特地貌区小流域个数182个,非喀斯特地貌区213个;就不同流域类型小流域划分结果看,完整型小流域530个,区间型小流域180个,坡面型小流域43个;这些小流域中面积小于3km²的有9个,面积在3～10km²的有310个,面积在10～30km²的有348个,面积在30～50km²的有86个。贵州省赤水河流域小流域划分研究可为小流域治理工作提供依据,为区域制定水土保持方案和生态建设措施提供辅助决策,促进喀斯特地区水土保持与生态环境建设。  相似文献   

An analytical solution for wave propagation in a square pile due to transient point load     

《Computers and Geotechnics》2017

This paper presents an analytical solution for wave propagation in a square pile due to transient point load. The differential equation of dynamic equilibrium is established considering propagation of waves in both vertical and transverse directions. The soil resistance is simulated by Voigt model. The three-dimensional analytical solution is deduced by using Fourier transform and the separation of variable method. The arithmetical results of the proposed solution show that the velocity responses along the radial direction at the pile top are highly non-uniform. In addition, Young’s modulus and the pile side length exert undisputable influences on the velocity responses.  相似文献