沉积方向对密砂固结排水剪切强度的影响研究
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摘要
基于砂土颗粒的毛细效应制备具有不同沉积方向的密砂试样,通过三轴固结排水剪切试验研究沉积方向对试样强度和体变特性的影响,建立沉积方向和峰值强度的拟合公式。研究结论表明,在0°～90°范围内,沉积方向对峰值强度和变形的影响比较显著,对残余强度的影响较弱。当沉积方向与破坏面方向(45°+φ/2)接近时,试样更容易达到破坏状态,所对应的峰值强度更低。拟合公式能够反映沉积方向和峰值强度的关系,围压对该关系有显著的影响,同时,公式能够预测最不利沉积方向的大小。
Based on the capillary effect of the sand, a test technology is suggested to prepare the dense sand sample with different sedimentary directions. A series of triaxial tests are performed to study the influence of the sedimentary direction on the strength and the volume change of the sand sample, meanwhile,a fitting formula is suggested for the relation between the ultimate strength and the sedimentary direction.Main study results show that the sedimentary direction has a great influence on the ultimate strength and the deformation characteristics of the sand for the direction in the range between 0° ～90°, but it has little influence on the residual strength of the sand. When the sedimentary direction is close to the failure plane direction, which is suggested as 45° + φ/2, the test sample is easier to reach the failure stage and the ultimate strength is low. The suggested fitting formula could reflect the relation between the sedimentary direction and the ultimate strength reasonably, in which the confined pressure has an influence on the relation. Meanwhile, the formula could be used to predict the most unfavorable sedimentary direction.
Based on the capillary effect of the sand, a test technology is suggested to prepare the dense sand sample with different sedimentary directions. A series of triaxial tests are performed to study the influence of the sedimentary direction on the strength and the volume change of the sand sample, meanwhile,a fitting formula is suggested for the relation between the ultimate strength and the sedimentary direction.Main study results show that the sedimentary direction has a great influence on the ultimate strength and the deformation characteristics of the sand for the direction in the range between 0° ～90°, but it has little influence on the residual strength of the sand. When the sedimentary direction is close to the failure plane direction, which is suggested as 45° + φ/2, the test sample is easier to reach the failure stage and the ultimate strength is low. The suggested fitting formula could reflect the relation between the sedimentary direction and the ultimate strength reasonably, in which the confined pressure has an influence on the relation. Meanwhile, the formula could be used to predict the most unfavorable sedimentary direction.
引文
1刘洋.砂土的各向异性强度准则:原生各向异性.岩土工程学报,2013,35(8):1526-1534Liu Yang.Anisotropic strength criteria of sand:inherent anisotropy.Chinese Journal of Geotechnical Engineering,2013,35(8):1526-1534(in Chinese)
2 Ducan JM,Seed HB.Strength variation along failure surfaces in clay.J Geotech Eng Div 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.岩土工程学报,2006,28(9):1085-1089Luan Maotian,Xu Chengshun,He Yang,et al.Experimental study on effect of orientation of the principal stress on undrained behavior of saturated loose sand under monotonic shearing.Chinese Journal of Geotechnical Engineering,2006,28(9):1085-1089(in Chinese)
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.岩土力学,2015,36(8):2261-2269Sun Qi,Dong Quanyang,Cai Yuanqiang,et al.Deformation of fully saturated sand under simultaneous variations of deviatoric stress ratio and principal stress rotational angle.Rock and Soil Mechanics,2015,36(8):2261-2269(in Chinese)
5冷艺,栾茂田,许成顺.饱和砂土排水与不排水剪切特性的比较研究.防灾减灾工程学报,2008,28(2):144-151Leng Yi,Luan Maotian,Xu Chengshun,et al.A comparative study of drained and undrained shear behavior of saturated sands.Journal of Disaster Prevention and Mitigation Engineering,2008,28(2):144-151(in Chinese)
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.岩土力学,2011,32(8):1637-1642Yu Yilin,Zhang Jianmin,Tong Zhaoxia,et al.Behavior of anisotropic mica sand under fixed principal stress axes drained shear test.Rock and Soil Mechanics,2011,32(8):1637-1642(in Chinese)
7李广信.高等土力学.北京:清华大学出版社,2016Li Guangxin.Advanced Soil Mechanics.Beijing:Tsinghua University Press,2016(in Chinese)
8 Oda M,Koishikawa I.Effect of strength anisotropy on bearing capacity of shallow footing in a dense sand.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.岩石力学与工程学报,2012,31(12):2579-2584Tong Zhaoxia,Zhou Shaopeng,Yao Yangping,et al.An improved direct shear apparatus for shear strength of anisotropic sands and its primary application.Chinese Journal of Rock Mechanics and Engineering,2012,31(12):2579-2584(in Chinese)
10宋飞,张建民.各向异性砂土渐近状态试验研究.岩土工程学报,2010,32(4):551-561Song Fei,Zhang Jianmin.Experimental study on asymptotic behaviour of anisotropic sand.Chinese Journal of Geotechnical Engineering,2010,32(4):551-561(in Chinese)
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.人民长江,2012,43(11):66-70Zeng Hongjing,Wang Zhongtao,Luo Qiang,et al.Introduction to a new sand pourer and its control element analysis.Yangtze River,2012,43(11):66-70(in Chinese)
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.岩土工程学报,2012,34(7):1313-1319Huang Bo,Wang Qingjing,Ling Daosheng,et al.Effects of back pressure on shear strength of saturated sand in triaxial tests.Chinese Journal of Geotechnical Engineering,2012,34(7):1313-1319(in Chinese)
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.岩土工程学报,2018,40(4):736-742Dong Tong,Zheng Yingren,Kong Liang,et al.Strength criteria and slipping planes of anisotropic sand considering direction of major principal stress.Chinese Journal of Geotechnical Engineering,2018,40(4):736-742(in Chinese)
2 Ducan JM,Seed HB.Strength variation along failure surfaces in clay.J Geotech Eng Div 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.岩土工程学报,2006,28(9):1085-1089Luan Maotian,Xu Chengshun,He Yang,et al.Experimental study on effect of orientation of the principal stress on undrained behavior of saturated loose sand under monotonic shearing.Chinese Journal of Geotechnical Engineering,2006,28(9):1085-1089(in Chinese)
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.岩土力学,2015,36(8):2261-2269Sun Qi,Dong Quanyang,Cai Yuanqiang,et al.Deformation of fully saturated sand under simultaneous variations of deviatoric stress ratio and principal stress rotational angle.Rock and Soil Mechanics,2015,36(8):2261-2269(in Chinese)
5冷艺,栾茂田,许成顺.饱和砂土排水与不排水剪切特性的比较研究.防灾减灾工程学报,2008,28(2):144-151Leng Yi,Luan Maotian,Xu Chengshun,et al.A comparative study of drained and undrained shear behavior of saturated sands.Journal of Disaster Prevention and Mitigation Engineering,2008,28(2):144-151(in Chinese)
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.岩土力学,2011,32(8):1637-1642Yu Yilin,Zhang Jianmin,Tong Zhaoxia,et al.Behavior of anisotropic mica sand under fixed principal stress axes drained shear test.Rock and Soil Mechanics,2011,32(8):1637-1642(in Chinese)
7李广信.高等土力学.北京:清华大学出版社,2016Li Guangxin.Advanced Soil Mechanics.Beijing:Tsinghua University Press,2016(in Chinese)
8 Oda M,Koishikawa I.Effect of strength anisotropy on bearing capacity of shallow footing in a dense sand.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.岩石力学与工程学报,2012,31(12):2579-2584Tong Zhaoxia,Zhou Shaopeng,Yao Yangping,et al.An improved direct shear apparatus for shear strength of anisotropic sands and its primary application.Chinese Journal of Rock Mechanics and Engineering,2012,31(12):2579-2584(in Chinese)
10宋飞,张建民.各向异性砂土渐近状态试验研究.岩土工程学报,2010,32(4):551-561Song Fei,Zhang Jianmin.Experimental study on asymptotic behaviour of anisotropic sand.Chinese Journal of Geotechnical Engineering,2010,32(4):551-561(in Chinese)
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.人民长江,2012,43(11):66-70Zeng Hongjing,Wang Zhongtao,Luo Qiang,et al.Introduction to a new sand pourer and its control element analysis.Yangtze River,2012,43(11):66-70(in Chinese)
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.岩土工程学报,2012,34(7):1313-1319Huang Bo,Wang Qingjing,Ling Daosheng,et al.Effects of back pressure on shear strength of saturated sand in triaxial tests.Chinese Journal of Geotechnical Engineering,2012,34(7):1313-1319(in Chinese)
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.岩土工程学报,2018,40(4):736-742Dong Tong,Zheng Yingren,Kong Liang,et al.Strength criteria and slipping planes of anisotropic sand considering direction of major principal stress.Chinese Journal of Geotechnical Engineering,2018,40(4):736-742(in Chinese)