工程上常用的基坑支护结构设计计算方法无法适用于基坑非对称开挖的情况.针对日渐常见的非对称开挖工程，通过变形控制设计，首先引入考虑位移的非极限状态土压力理论，对作用于支护结构上的土压力进行修正.基于获得的修正土压力模式，在对支护结构进行整体受力分析的基础上，获得了可用于两侧挖深不同的单撑式刚性支护结构设计计算的解析解，并进一步分析了土体内摩擦角、支撑刚度、基坑开挖的非对称程度对支护结构安全最小插入比的影响.结果表明：经典等值梁法由于采用极限状态土压力理论，计算得到的支护结构插入比偏于不安全，且计算结果的不安全程度在土体内摩擦角较小的情况下更为严重；相对于较深侧，较浅侧插入比将对基坑的非对称开挖更加敏感；与仅按单边设计相比，该解析解可以有效节约工程造价.试验实测数据验证表明，该计算方法可用于桩土刚度差异较大情况下基坑两侧挖深不同的单撑式支护结构的设计与计算.
Common design methods of retaining structure cannot be suitable in the design of asymmetric foundation pit. In view of the increasingly common asymmetric excavation, a calculation method of earth pressure considering displacement is presented to modify the mode of earth pressure acting on retaining structures. Based on the obtained earth pressure mode, the force of the whole structure system is analyzed, and the analytical solution of rigid retaining structure with bracing under asymmetric excavation is derived. The influences of the internal friction angle of soil, bracing stiffness and asymmetric degree on the insert ratio of retaining structure are analyzed. The results show that the calculated insertion ratio of classical equivalent beam method is unsafe, for the reason that this method adopts the limit equilibrium earth pressure theory. And the unsafe degree of the calculation result is more serious when the friction angle of the soil is relatively small. The insertion ratio of the shallower side is more sensitive to the asymmetric excavation than that of the deeper side. Compared with the common design method which only considers the single side, the proposed method can effectively save the project cost. The verification of the test data shows that the presented solution can be used for the calculation and design of single-strut retaining structure under asymmetric excavation.
［1］中国建筑科学研究院. 建筑基坑支护技术规程［M］. 北京: 中国建筑工业出版社, 2012.
China Academy of Building Research. Technical spe-cification for retaining and protection of buildingfoundation excavations［M］. Beijing: China Architecture & Building Press, 2012.
［2］蔡袁强, 李碧青, 徐长节. 挖深不同情况下基坑支护结构性状研究［J］. 岩土工程学报, 2010, 32(S1): 28-31.
CAI Yuanqiang, LI Biqing, XU Changjie. Characteristics of retaining structures of deep foundation pits under different excavation depths［J］. Chinese Journal of Geotechnical Engineering, 2010, 32(S1): 28-31.
［3］徐长节, 成守泽, 蔡袁强, 等. 非对称开挖条件下基坑变形性状分析［J］. 岩土力学, 2014, 35(7): 1929-1934.
XU Changjie, CHENG Shouze, CAI Yuanqiang, et al. Deformation characteristic analysis of foundation pit under asymmetric excavation condition［J］. Rock and Soil Mechanics, 2014, 35(7): 1929-1934.
［4］徐长节, 殷铭, 胡文韬. 非对称开挖基坑支撑式支护结构解析解［J］. 岩土力学, 2017, 38(8): 2306-2312.
XU Changjie, YIN Ming, HU Wentao. Analytical solutions of calculating length of retaining structures of foundation pit under asymmetric excavation［J］. Rock and Soil Mechanics, 2017, 38(8): 2306-2312.
［5］陈奕柏, 柯才桐, 高洪波, 等. 考虑变位影响的刚性挡墙非极限土压力研究［J］. 岩石力学与工程学报, 2015, 34(5): 1060-1070.
CHEN Yibai, KE Caitong, GAO Hongbo, et al. Non-limit state earth pressure against retaining wall considering influence of deformation［J］. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(5): 1060-1070.
［6］谢涛, 罗强, 张良, 等. 基于Rankine模型的墙体位移-土压力近似计算［J］. 岩石力学与工程学报, 2017, 36(5): 1279-1288.
XIE Tao, LUO Qiang, ZHANG Liang, et al. Calculation of displacement-dependent lateral earth pressure based on Rankine earth pressure model［J］. Chinese Journal of Rock Mechanics and Engineering, 2017, 36(5): 1279-1288.
［7］谢涛, 罗强, 张良, 等. Coulomb模型下考虑墙体侧向位移的土压力计算［J］. 岩土工程学报, 2018, 40(1): 194-200.
XIE Tao, LUO Qiang, ZHANG Liang, et al. Relationship between earth pressure and wall displacement based on Coulomb earth pressure model［J］. Chinese Journal of Geotechnical Engineering, 2018, 40(1): 194-200.
［8］DUNCAN J M, MOKWA R L. Passive earth pressures: Theories and tests［J］. Journal of Geotechnical and Geoenvironmental Engineering, 2001, 127(3): 248-257.
［9］MEI G, CHEN Q, SONG L.Model for predicting displacement-dependent lateral earth pressure［J］. Canadian Geotechnical Journal, 2009, 46(8): 969-975.
［10］MEI G X, CHEN R, LIU J. New insight into developing mathematical models for predicting deformation-dependent lateral earth pressure［J］. International Journal of Geomechanics, 2017, 17(8): 06017003.
［11］ZHANG Z M, FANG K, LIU X W. Simplified method of active earth pressure for special inner support structure［J］. Advanced Materials Research, 2011, 163-167: 4520-4523.
［12］NI P, MEI G, ZHAO Y. Displacement-dependent earth pressures on rigid retaining walls with compressible geofoam inclusions: Physical modeling and analytical solutions［J］. International Journal of Geomechanics, 2017, 17(6): 04016132.
［13］曹海莹, 武崇福. 深基坑桩锚支护体系非极限主动土压力演化特征与计算模式［J］. 应用基础与工程科学学报, 2016(4): 766-777.
CAO Haiying, WU Chongfu. Evolution characteristics and calculation mode of active earth pressure under non-limit state in deep foundation pit supported with piles and anchors［J］. Journal of Basic Science and Engineering, 2016(4): 766-777.
［14］FANG Y S, HO Y C, CHEN T J. Passive earth pressure with critical state concept［J］. Journal of Geotechnical & Geoenvironmental Engineering, 2002, 128(8): 651-659.
［15］PENG S Q, LI X B, FAN L, et al. A general method to calculate passive earth pressure on rigid retaining wall for all displacement modes［J］. Transactions of Nonferrous Metals Society of China, 2012, 22(6): 1526-1532.
［16］FANG Y, ISHIBASHI I. Static earth pressures with various wall movements［J］. Journal of Geotechnical Engineering, 1994, 120(8): 1307-1323.
［17］陆培毅, 严驰, 刘润. 粘性土基于室内模型试验土压力分布形式的研究［J］. 土木工程学报, 2002, 23(2): 84-88.
LU Peiyi, YAN Chi, LIU Run. Sand model test on the distribution of earth pressure［J］. China Civil Engineering Journal, 2002, 23(2): 84-88.
［18］黄运飞. 深基坑工程实用技术［M］. 北京: 兵器工业出版社, 1996.
HUANG Yunfei. Pratical technology of deep foundation pit engineering［M］. Beijing: The Publishing House of Ordnance Industry, 1996.
