In the study of deformation characteristics of deep foundation pit excavation in a soft soil environment, the hardening elastic-plastic model is often used for analysis, such as the HSS model and MCC model. In the soft soil area of the Nanjing River floodplain, large local deformation often occurs during deep foundation pit excavation. Some soil deformation states are between small and large strains, so a single model cannot accurately predict the deformation characteristics of soil. At the same time, the BP neural network has been widely used for predicting foundation pit deformation prediction. However, in the training process, the weight threshold easily falls into the local optimal solution, which affects the accuracy of prediction. Based on this, relying on the typical soft soil deep foundation pit project in the Nanjing area, the HSS model and MCC model in Midas are used to analyze the difference in pile deformation between the two models, and the two models are linearly fused based on the least squares criterion. The fusion model can calibrate and supplement the monitoring data of the subsequent section. The BP neural network is optimized by fusing the sparrow search algorithm, and the global optimal weight threshold is obtained by fast convergence in the training process. Based on the monitoring data of the excavated section of the narrow and long foundation pit, the training is learned. The deep deformation characteristics are revealed according to the shallow excavation of the subsequent section. The predicted results are in good agreement with the measured values. The research results have important reference value for predicting the large deformation of deep foundation pits in soft soil areas.
JIANGJ, ZHANGT, OUX D,et al .Time-effect analysis on influence of excavation on adjacent pile deformation in soft soil[J].Journal of Hunan University (Natural Sciences),2022, 49(11):206-215.(in Chinese)
XUR Q, SHENS, DONGM,et al .A simplified calculation method for horizontal displacement of adjacent shield tunnel caused by excavation in soft soil area[J]. Journal of Hunan University (Natural Sciences),2021,48(3):153-163.(in Chinese)
SONGG, SONGE X .Selection of soil constitutive models for numerical simulation of foundation pit excavation[J].Engineering Mechanics,2014,31(5):86-94.(in Chinese)
XUZ H, WANGW D .Selection of soil constitutive models for numerical analysis of deep excavations in close proximity to sensitive properties[J].Rock and Soil Mechanics,2010,31(1):258-264.(in Chinese)
[9]
BENZT .Small strain stiffness of soils and its numerical consequences[D].Stuttgart: University of Stuttgart,2006.
[10]
ROSCOEK H, SCHOFIELDA N. Mechanical behavior of an idealized wet-clay[C]//Proceedings of the Second European Conference on Soil Mechanics and Foundation Engineering,Wiesbaden:[s.n.],1963:47-54.
GUX Q, WUR T, LIANGF Y,et al .On HSS model parameters for Shanghai soils with engineering verification[J].Rock and Soil Mechanics,2021,42(3):833-845.(in Chinese)
GUX Q, LUL T, LIX W,et al .Experimental study of small strain stiffness properties of soil[J].Journal of Tongji University (Natural Science),2018,46(3):312-317.(in Chinese)
CHENY, LUOM M, XIAN W,et al .Statistical analysis of existing test results of HSS model parameters for soft soils[J].Chinese Journal of Geotechnical Engineering,2021,43(Sup.2):197-201.(in Chinese)
YINJ .Application of hardening soil model with small strain stiffness in deep foundation pits in Shanghai[J].Chinese Journal of Geotechnical Engineering,2010,32(Sup.1):166-172.(in Chinese)
SHAOY, JIANGJ, CHENJ Y,et al .Deformation of deep foundation pits due to excavation and dewatering based on HSS model and Modified Cam-Clay Model[J].Journal of Hydraulic Engineering,2015,46(Sup.1):231-235.(in Chinese)
WANGH B, XUM, SONGE X .A small strain constitutive model based on hardening soil model[J].Rock and Soil Mechanics,2011,32(1):39-43.(in Chinese)
[23]
NIX D, LUJ F, WANGY,et al .Field investigation of the influence of basement excavation and dewatering on ground and structure responses[J].Tunnelling and Underground Space Technology,2021,117:104121.
[24]
OUC Y, HSIEHP G, CHIOUD C .Characteristics of ground surface settlement during excavation[J].Canadian Geotechnical Journal,1993,30(5):758-767.
[25]
MANAA I, CLOUGHG W .Prediction of movements for braced cuts in clay[J].Journal of the Geotechnical Engineering Division,1981,107(6):759-777.
[26]
WANGZ W, NGC W, LIUG B .Characteristics of wall deflections and ground surface settlements in Shanghai[J].Canadian Geotechnical Journal,2005,42(5):1243-1254.
LIUW H, ZHUH L, HES J,et al .Experimental study on parameters of hardening soil model for soils and its application in foundation pit engineering in Nanchang[J].Journal of Civil and Environmental Engineering,2021,43(6):38-47.(in Chinese)
CHENZ H, RUANY F, WANGP,et al .Parameter value of HSS model for lacustrine sedimentary soft soil[J].China Earthquake Engineering Journal,2023,45(1):74-85.(in Chinese)
ZHOUH C, QINZ H, GUX Q .Analysis of the influence of excavation on adjacent bridge piles and deformation control using HSS model[J].Journal of Ground Improvement,2023,5(5):369-375.(in Chinese)
WUD W, JIANGJ N, SHENH .Deformation analysis of foundation pit excavation based on modified Cambridge model[J].Hebei Water Resources,2022(6):44-46.(in Chinese)
XuZ H .Deformation behavior of deep excavations supported by permanent structure in Shanghai soft deposit[D]. Shanghai:Shanghai Jiao Tong University,2007:29-34.(in Chinese)
WANGW D, WANGH R, XUZ H .Study of parameters of HS-Small model used in numerical analysis of excavations in Shanghai Area[J].Rock and Soil Mechanics,2013,34(6):1766-1774.(in Chinese)
YANGQ N, ZHENGJ J, DINGL Y,et al .Three-dimensional numerical simulation of deep excavation adjacent to viaduct foundation[J].Journal of Huazhong University of Science and Technology (Natural Science Edition),2010,38(6):120-123.(in Chinese)
NIX D, WANGC, TANGD H,et al .Early-warning and inducement analysis of super-large deformation of deep foundation pit on soft soil[J].Journal of Central South University (Science and Technology),2022,53(6):2245-2254.(in Chinese)
[45]
张云 .修正剑桥模型参数对计算结果的影响[J].岩土力学,2006,27(3):441-444.
[46]
ZHANGY .Effects of parameters of modified Cambridge model on computed results[J].Rock and Soil Mechanics,2006,27(3):441-444.(in Chinese)
ZHANGJ X, ZHAOG, ZHANGL,et al .Application of HSS model in shield simulation and study on parameter sensitivity[J].Chinese Journal of Underground Space and Engineering, 2020, 16(Sup.2): 618-625.(in Chinese)
LIL X, LIUJ D, LIK J,et al .Study of parameters selection and applicability of HSS model in typical stratum of Ji’nan[J]. Rock and Soil Mechanics, 2019, 40(10): 4021-4029.(in Chinese)
TANGZ Q, TANZ Q .Application of grey timseries model to monitoring the excavation deformation[J]. Engineering of Surveying and Mapping,2014,23(2):49-53.(in Chinese)
LIS Y .Research on deep foundation settlement prediction based on interpolation exponential smoothing combined model[J].Geomatics & Spatial Information Technology,2018,41(2):183-185.(in Chinese)
[55]
刘杰 .组合预测模型在基坑变形监测中的应用[J].北京测绘,2017(4):46-49.
[56]
LIUJ. The application of a combined predict model in deformation monitoring of pits[J]. Beijing Surveying and Mapping,2017(4):46-49.(in Chinese)
WANGL, GAOF .Application research of foundation pit based on time series and BP neural network[J].Geomatics & Spatial Information Technology,2018,41(6):201-205.(in Chinese)
[59]
陈华友 .组合预测方法有效性理论及其应用[M].北京:科学出版社,2008:60-61.
[60]
CHENH Y .Validity theory of combined forecasting method and its application[M].Beijing:Science Press,2008:60-61.(in Chinese)