(1. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education，Tongji University，Shanghai 200092，China；2. Department of Geotechnical Engineering，Tongji University，Shanghai 200092，China；3. Chengdu Urban and Rural Construction Commission，Chengdu，Sichuan 610094，China)
Abstract：A total of 36 groups of direct shear tests to samples with the sand-concrete interface were conducted under three different initial normal stresses and three roughness values of interface to analyze the mechanical properties of the interface and the effects of the unloading ratio and roughness on its softening and shear dilation. The soil for test is the gray silt in ③2 layer from Shanghai. The test results show that the initial normal stress influences indirectly the peak shear stress of interface by affecting the density and moisture content of the soil at interface. The peak and residual shear stress of interface decrease linearly with the increasing of the unloading ratio. The roughness of interface has no significant effects on the decreasing rate of peak and residual shear stress varied with the unloading ratio. The residual shear stress of interface increases gradually with the increasing of roughness and tends to reach the same value as the applied normal stress when specimens were sheared. The softening phenomenon of the interface becomes more obvious with the increasing of the unloading ratio. There exists a critical value for the roughness r of interface，i.e.，the softening of the interface is little affected by the roughness when r＜10 mm and is affected by the roughness when r＞10 mm. The shear contraction of interface appears under the loading conditions，and the shear dilation of interface transforms gradually to the shear contraction as the unloading degree decreases. The maximum value of shear dilation of interface increases with the increasing of unloading degree，whereas the maximum value of shear contraction decreases under the same roughness of interface.
POTYONDY J G. Skin friction between various soils and construction materials[J]. Geotechnique，1961，11(4)：339-353.
[2]
DESAI C S，DRUMM E C，ZAMAN M M. Cyclic testing and modeling of interfaces[J]. Journal of Geotechnical Engineering，1985，111(6)：793-815.
[10]
胡黎明，濮家骝. 土与结构物接触面物理力学特性试验研究[J]. 岩土工程学报，2001，23(4)：431-435.(HU Liming，PU Jialiu. Experimental study on mechanical characteristics of soil-structure interface[J]. Chinese Journal of Geotechnical Engineering，2001，23(4)：431-435.(in Chinese))
[12]
陈俊桦，张家生，李 键，等. 接触面粗糙度对红黏土-混凝土接触面力学性质的影响[J]. 中南大学学报：自然科学版，2016，47(5)：1 682-1 688.(CHEN Junhua，ZHANG Jiasheng，LI Jian. Influence of interface roughness on mechanical properties of red clay-concrete interface[J]. Journal of Central South University：Science and Technology，2016，47(5)：1 682-1 688.(in Chinese))
[17]
徐泽友，卢延浩，丁明武. 高塑性黏土与混凝土接触面剪切特性[J].河海大学学报：自然科学版，2009，37(1)：71-74.(XU Zeyou，LU Tinghao，DING Mingwu. Shear properties at interface between highly plastic clay and concrete[J]. Journal of Hohai University：Natural Science，2009，37(1)：71-74.(in Chinese))
[5]
龚 辉，赵春风，陶帼雄，等. 应力历史对黏土-混凝土界面剪切特性的影响研究[J]. 岩石力学与工程学报，2011，30(8)：1 712- 1 719.(GONG Hui，ZHAO Chunfeng，TAO Guoxiong，et al. Research on effect of stress history on shear behavior of interface between clay and concrete[J]. Chinese Journal of Rock Mechanics and Engineering， 2011，30(8)：1 712-1 719.(in Chinese))
[8]
张 嘎，张建民. 粗粒土与结构接触面单调力学特性的试验研究[J]. 岩土工程学报，2004，26(1)：21-25.(ZHANG Ga，ZHANG Jianmin. Experimental study on monotonic behavior of interface between soil and structure[J]. Chinese Journal of Geotechnical Engineering，2004，26(1)：21-25.(in Chinese))
[15]
张 嘎，张建民. 大型土与结构接触面循环加载剪切仪的研制及应用[J]. 岩土工程学报，2003，25(2)：149-153.(ZHANG Ga，ZHANG Jianmin. Development and application of cyclic shear apparatus for soil-structure interface[J]. Chinese Journal of Geotechnical Engineering，2003，25(2)：149-153.(in Chinese))
[1]
CLOUGH G W，DUNCAN J M. Finite element analyses of retaining wall behavior[J]. ASCE Journal of the Soil Mechanics and Foundations Division，1971，97(SM12)：1 657-1 673.
[4]
ZEGHAL M，EDIL T B，PLESHA M E. Discrete element method for sand-structure interaction[C]// Proceedings of the 3rd International Conference on Discrete Element Methods. Santa Fe，New Mexico：[s. n.]，2010：317-322.
[6]
赵春风，龚 辉，赵 程，等. 考虑法向应力历史的黏土-混凝土界面弹塑性分析[J]. 岩石力学与工程学报，2012，31(4)：848-855. (ZHAO Chunfeng，GONG Hui，ZHAO Cheng，et al. Elastoplastic analysis of interface between clay and concrete considering effect of normal stress history[J]. Chinese Journal of Rock Mechanics and Engineering，2012，31(4)：848-855.(in Chinese))
[7]
ZHAO C，ZHAO C，GONG H. Elastoplastical analysis of the interface between clay and concrete incorporating the effect of the normal stress history[J]. Journal of Applied Mathematics，2013，2013(12)：1-12.
[9]
张 嘎，张建民. 循环荷载作用下粗粒土与结构接触面变形特性的试验研究[J]. 岩土工程学报，2004，26(2)：254-258.(ZHANG Ga，ZHANG Jianmin. Experimental study on cyclic behavior of interface between soil and structure[J]. Chinese Journal of Geotechnical Engineering，2004，26(2)：254-258.(in Chinese))
[11]
陈俊桦，张家生，李 键. 考虑粗糙度的黏性土-结构接触面力学特性试验[J]. 四川大学学报：工程科学版，2015，47(4)：22-30.(CHEN Junhua，ZHANG Jiasheng，LI Jian. Experimental research on mechanical characteristics of cohesive soil-structure interface by considering its roughness[J]. Journal of Sichuan University：Engineering Science，2015，47(4)：22-30.(in Chinese))
[13]
HORVATH R G，KENNV T C，KOZICHI P. Method of improving the performance of drilled piles in weak rock[J]. Canadian Geotechnical Journal，1983，20(4)：758-772.
[14]
DOVE J E，JARRETT J B. Behavior of dilative sand interfaces in a geotribology framework[J]. Journal of Geotechnical and Geoenvironmental Engineering，2002，128(1)：25-37.
[16]
潘林有，程玉梅，胡中雄. 卸荷状态下黏性土强度特性试验研究[J]. 岩土力学，2001，22(4)：490-493.(PAN Linyou，CHENG Yumei， HU Zhongxiong. Experimental study on the shear strength of clay under the unloading state[J]. Rock and Soil Mechanics，2001，22(4)：490-493.(in Chinese))
2018, Vol. 37 
