沉积方向对土体强度的影响对于研究初始各向异性而言具有重要意义。基于砂土颗粒的毛细效应提出一种试样制备方法,制备若干组具有不同沉积方向的密砂试样。通过系列三轴固结排水剪切试验研究沉积方向对强度、体变的影响,并拟合得到沉积方向和峰值强度的关系公式。研究表明:沉积方向夹角在0°~90°范围内对峰值强度和体变的影响比较显著,当沉积方向夹角与试样破坏面方向(45°+φ/2)接近时,剪切带形成得更早,试样更容易达到破坏,所对应的峰值强度更低,达到峰值和残余状态更早。依据试验结果拟合得到沉积方向夹角和峰值强度的关系公式,公式预测结果与试验结果吻合度在不同围压条件下均较高。研究结果为研究砂土的初始各向异性力学特性提供了有益的方法。
Abstract
The influence of sedimentary direction on the strength and volumetric change of dense sand was examined via series of triaxial conslidated drained shear test. Dense sand specimens with different sedimentary directions were prepared based on the capillary effect of sand. Test results revealed that sedimentary direction had obvious influence on the ultimate peak strength and volumetric deformation of sand when the direction changed between 0°~90°. When the sedimentary direction was close to the failure plane direction which is suggested as (45°+φ/2), the shear band of sample developed earlier, leading to easier failure with lower peak strength and earlier residual stage. Furthermore, a fitting formula reflecting the relation between sedimentary direction and peak strength is put forward. The formula-predicted result well coincided with test result under different confining pressures. Studying the influence of sedimentary direction on strength is of importance to the research of initial anisotropy of sand.
关键词
砂土 /
毛细效应 /
沉积方向 /
固结排水 /
剪切试验 /
峰值强度
Key words
sand /
capillary effect /
sedimentary direction /
consolidated undrained /
shear test /
peak strength
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1] 刘 洋. 砂土的各向异性强度准则:原生各向异性[J].岩土工程学报,2013,35(8):1526-1534.
[2] DUNCAN J M, SEED H B. Strength Variation along Failure Surfaces in Clay[J]. Journal of Geotechnical and Geoenvironmental Engineering of ASCE, 1966, SM6: 81-104.
[3] 栾茂田, 许成顺,何 杨,等. 主应力方向对饱和松砂不排水单调剪切特性影响的试验研究[J]. 岩土工程学报,2006, 28(9): 1085-1089.
[4] 孙 奇,董全杨,蔡袁强,等. 偏应力比和应力主轴偏转角同时变化下饱和砂土变形特性研究[J].岩土力学,2015,36(8):2261-2269.
[5] 冷 艺,栾茂田,许成顺,等. 饱和砂土排水与不排水剪切特性的比较研究[J]. 防灾减灾工程学报, 2008, 28(2): 143-151.
[6] 于艺林,张建民,童朝霞,等. 定轴排水剪切试验中各向异性砂土的力学响应[J].岩土力学,2011,32(6):1637-1642.
[7] 李广信. 高等土力学[M]. 2版.北京:清华大学出版社,2016.
[8] ODA M, KOISHIKAWA I. Effect of Strength Anisotropy on Bearing Capacity of Shallow Footing in a Dense Sand[J]. Soils and Foundations, 1979, 19(3):15-28.
[9] 童朝霞,周少鹏,姚仰平,等. 测定各向异性砂土抗剪强度特性的新型直剪装置及初步应用[J].岩石力学与工程学报,2012,31(12):2579-2584.
[10]宋 飞,张建民.各向异性砂土渐近状态试验研究[J].岩土工程学报,2010,32(4):551-561.
[11]曾虹静,王忠涛,罗 强,等. 自制砂土装样设备及其控制要素分析[J]. 人民长江, 2012, 43(11):66-70.
[12]黄 博,汪清静,凌道盛,等. 饱和砂土三轴试验中反压设置与抗剪强度的研究[J].岩土工程学报, 2012,34(7):1313-1319.
[13]董 彤,郑颖人,孔 亮,等. 考虑主应力轴方向的砂土各向异性强度准则与滑动面研究[J].岩土工程学报,2018,40(4):736-742.
基金
国家自然科学基金项目(51609117,51209028);河南省教育厅科学技术研究重点项目(14B560023)
PDF(2939 KB)
