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| CRITICAL EMBEDMENT DEPTH OF RIGID RETAINING WALL IN FOUNDATION PIT OF UNSATURATED SOILS |
| ZHANG Changguang，ZHAO Junhai，ZHU Qian |
| (School of Civil Engineering，Chang?an University，Xi?an，Shaanxi 710061，China) |
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Abstract When the soils around the foundation pit are actually in an unsaturated state，the design of anti-overturning retaining wall based on the saturated soil mechanics neglecting matric suction is unreasonable. Assuming the matric suction with the uniform and linear distributions，equations for critical embedment depths of anti-overturning were obtained on the basis of the unified solution of shear strength for unsaturated soils under the plane strain condition，and the moment equality considering the intermediate principal stress effect and the strength nonlinearity. The procedure of engineering application with the obtained results was given and the parametric analysis about the coefficient of critical embedment for anti-overturning was discussed. The proposed results are orderly solution series. The effect of strength theory on the anti-overturning design for rigid retaining wall of foundation pit led to remarkable difference. The greater strength of unsaturated soils in comparing to the saturated soil could be utilized considering the intermediate principal stress effect. The critical embedment coefficient was significantly influenced by the matric suction and its distributions. Therefore，the distributions of matric suction should be reasonably assumed and some engineering measures should be adopted to ensure its stability. Two methods can deal with the effect of strength nonlinearity of unsaturated soils：the method 1 with a small stable suction angle which is simple but conservative；while the method 2 with piecewise hyperbolic suction angle is precise but slightly complicated. The dual effects of high matric suction on the strength of unsaturated soil and the structural design should be correctly understood.
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Received: 04 January 2014
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| [1] FREDLUND D G，RAHARDJO H. Soil mechanics for unsaturated soils[M]. New York：John Wiley and Sons，lnc.，1993：1–19.
[2] LU N，LIKOS W J. Unsaturated soil mechanics[M]. New York：John Wiley and Sons，lnc.，2004：3–40.
[3] MATSUOKA H，SUN D A，KOGANE A，et al. Stress-strain behaviour of unsaturated soil in true triaxial tests[J]. Canadian Geotechnical Journal，2002，39(3)：608–619.
[4] MACARI E J，HOYOS L R. Mechanical behavior of an unsaturated soil under multi-axial stress states[J]. Geotechnical Testing Journal，2001，24(1)：14–22.
[5] 邢义川，谢定义，汪小刚，等. 非饱和黄土的三维有效应力[J]. 岩土工程学报，2003，25(3)：288–293.(XING Yichuan，XIE Dingyi， WANG Xiaogang，et al. 3D effective stress of unsaturated loess[J]. Chinese Journal of Geotechnical Engineering，2003，25(3)：288–293. (in Chinese))
[6] 邵生俊，罗爱忠，邓国华，等. 一种新型真三轴仪的研制与开发[J]. 岩土工程学报，2009，31(8)：1 172–1 179.(SHAO Shengjun，LUO Aizhong，DENG Guohua，et al. Development of a new true triaxial apparatus[J]. Chinese Journal of Geotechnical Engineering，2009，31(8)：1 172–1 179.(in Chinese))
[7] 于清高，邵生俊，佘芳涛，等. 真三轴条件下Q2黄土的破坏模式与强度特性研究[J]. 岩土力学，2010，31(1)：66–70.(YU Qinggao，SHAO Shengjun，SHE Fangtao，et al. Research on failure modes and strength characteristics of Q2 loess under true triaxial condition[J]. Rock and Soil Mechanics，2010，31(1)：66–70.(in Chinese))
[8] 高大钊. 土力学与基础工程[M]. 北京：中国建筑工业出版社，1998：385–415.(GAO Dazhao. Soil mechanics and foundation engineering[M]. Beijing：China Architecture and Building Press，1998：385–415.(in Chinese))
[9] 中华人民共和国行业标准编写组. JGJ120—2012建筑基坑支护技术规程[S]. 北京：中国建筑工业出版社，2012.(The Professional Standards Compilation Group of People?s Republic of China. JGJ120—2012 Technical specification for retaining and protection of building foundation excavations[S]. Beijing：China Architecture and Building Press，2012.(in Chinese))
[10] 卢肇钧，吴肖茗，孙玉珍，等. 膨胀力在非饱和土强度理论中的应用[J]. 岩土工程学报，1997，19(5)：20–27.(LU Zhaojun，WU Xiaoming，SUN Yuzhen，et al. The role of swelling pressure in the shear strength theory of unsaturated soils[J]. Chinese Journal of Geotechnical Engineering，1997，19(5)：20–27.(in Chinese))
[11] 吴剑敏，李广信，王成华. 非饱和土基质吸力对基坑支护计算的影响[J]. 工业建筑，2003，33(7)：6–10.(WU Jianmin，LI Guangxin， WANG Chenghua. Effect of matric suction of unsaturated soil on the estimation of the load and internal force on supporting structure for deep excavation[J]. Industrial Construction，2003，33(7)：6–10.(in Chinese))
[12] 尚 军. 考虑非饱和土强度理论的水泥搅拌桩挡土墙结构稳定分析研究[J]. 天津城市建设学院学报，2004，10(4)：245–251.(SHANG Jun. Applications of unsaturated soil strength theory in the analysis of general stability of cement mixed pile retaining wall[J]. Journal of Tianjin Institute of Urban Construction，2004，10(4)：245–251.(in Chinese))
[13] STANIER S A，TARANTINO A. An approach for predicting the stability of vertical cuts in cohesionless soils above the water table[J]. Engineering Geology，2013，158(1)：98–108.
[14] PUFAHL D E，FREDLUND D G，RAHARDJO H. Lateral earth pressures in expansive clay soils[J]. Canadian Geotechnical Journal，1983，20(2)：228–241.
[15] VANAPALLI S K，OH W T. Stability analysis of unsupported vertical trenches in unsaturated soils[C]// Proceedings of GeoCongress 2012：State of the Art and Practice in Geotechnical Engineering. Oakland，California，USA：[s. n.]，2012：2 502–2 511.
[16] 汪丁建，童龙云，邱岳峰. 降雨入渗条件下非饱和土朗肯土压力分析[J]. 岩土力学，2013，34(11)：3 192–3 196.(WANG Dingjian，TONG Longyun，QIU Yuefeng. Rankine?s earth pressure analysis of unsaturated soil under condition of rainfall infiltration[J]. Rock and Soil Mechanics，2013，34(11)：3 192–3 196.(in Chinese))
[17] VO T，RUSSELL A R. Unsaturated soil interacting with a rotating model wall[J]. International Journal of Physical Modelling in Geotechnics，2013，13(2)：63–78.
[18] VO T，RUSSELL A R. Slip line theory applied to a retaining wall-unsaturated soil interaction problem[J]. Computers and Geotechnics，2014，55(3)：416–428.
[19] 张常光，张庆贺，赵均海. 非饱和土抗剪强度及土压力统一解[J]. 岩土力学，2010，31(6)：1 871–1 876.(ZHANG Changguang，ZHANG Qinghe，ZHAO Junhai. Unified solutions of shear strength and earth pressure for unsaturated soils[J]. Rock and Soil Mechanics，2010，31(6)：1 871–1 876.(in Chinese))
[20] 张常光，胡云世，赵均海. 平面应变条件下非饱和土抗剪强度统一解及其应用[J]. 岩土工程学报，2011，33(1)：32–37.(ZHANG Changguang，HU Yunshi，ZHAO Junhai. Unified solution of shear strength for unsaturated soil under plane strain condition and its application[J]. Chinese Journal of Geotechnical Engineering，2011，33(1)：32–37. (in Chinese))
[21] 张常光，赵均海，张冬芳. 非饱和土强度非线性及对被动土压力的影响[J]. 广西大学学报：自然科学版，2012，37(4)：797–802. (ZHANG Changguang，ZHAO Junhai，ZHANG Dongfang. Nonlinear strength of unsaturated soils and its influence on passive earth pressure[J]. Journal of Guangxi University：Natural Science，2012，37(4)：797–802.(in Chinese))
[22] 张常光，曾开华，赵均海. 非饱和土临界荷载和太沙基极限承载力解析解[J]. 同济大学学报：自然科学版，2010，38(12)：1 736–1 740. (ZHANG Changguang，ZENG Kaihua，ZHAO Junhai. Analytical solutions of critical load and Terzaghi?s ultimate bearing capacity for unsaturated soil[J]. Journal of Tongji University：Natural Science，2010，38(12)：1 736–1 740.(in Chinese))
[23] 赵均海，梁文彪，张常光，等. 非饱和土库仑主动土压力统一解[J]. 岩土力学，2013，34(3)：609–614.(ZHAO Junhai，LIANG Wenbiao，ZHANG Changguang，et al. Unified solution of Coulomb?s active earth pressure for unsaturated soils[J]. Rock and Soil Mechanics，2013，34(3)：609–614.(in Chinese))
[24] 俞茂宏. 双剪理论及其应用[M]. 北京：科学出版社，1998：249–282.(YU Maohong. Twin-shear theory and its application[M]. Beijing：Science Press，1998：249–282.(in Chinese))
[25] 俞茂宏. 岩土类材料的统一强度理论及其应用[J]. 岩土工程学报， 1994，16(2)：1–10.(YU Maohong. Unified strength theory for geomaterials and its applications[J]. Chinese Journal of Geotechnical Engineering，1994，16(2)：1–10.(in Chinese))
[26] FREDLUND D G，MORGENSTEM N R，WIDGER R A. The shear strength of unsaturated soils[J]. Canadian Geotechnical Journal，1978，15(3)：313–321.
[27] GAN K J，FREDLUND D G. Multistage direct shear testing of unsaturated soils[J]. Geotechnical Testing Journal，1988，11(2)：132–138.
[28] RASSAM D W，COOK F. Predicting the shear strength envelope of unsaturated soils[J]. Geotechnical Testing Journal，2002，25(2)：215–220.
[29] LEE I M，SUNG S G，CHO G C. Effect of stress state on the unsaturated shear strength of a weathered granite[J]. Canadian Geotechnical Journal，2005，42(2)：624–631.
[30] FREDLUND D G. Unsaturated soil mechanics in engineering practice[J]. Journal of Geotechnical and Geoenvironmental Engineering，2006，132(3)：286–321.
[31] HOUSTON S L，PEREZ-GARCIA N，HOUSTON W N. Shear strength and shear-induced volume change behavior of unsaturated soils from a triaxial test program[J]. Journal of Geotechnical and Geoenvironmental Engineering，2008，134(11)：1 619–1 632.
[32] ZHOU A N，SHENG D C. Yield stress，volume change，and shear strength behaviour of unsaturated soils：validation of the SFG model[J]. Canadian Geotechnical Journal，2009，46(9)：1 034–1 045. |
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2014, Vol. 33 
