膠結不良軟岩之彈塑性模式與基礎承載模擬應用

Abstract

因地質材料之力學特性極為複雜，其力學特性包括 (A)非線型、（B）受載後可能出現不可回復之塑性變形、（C）異向性、(D)體積受剪變化性、(E)受圍壓影響、（F）受應力歷史影響、（G）受應力軌跡影響、…等，並非簡單的力學模式所能輕易模擬。本研究所採用之模式以漸進屈伏面模式為架構，以彈塑性模式來分析軟岩受壓所產生之應變軟化與體積變化。利用此模式模擬軟岩之三軸試驗，與基礎承載行為。並採用基因演算法來求取參數。實驗資料取交大西南山區、寶二水庫及人造軟岩三軸實驗之應力應變曲線，每組試驗均取三組應力應變實驗資料同時模擬迴歸分析。並探討各參數對應力應變關係的影響。由數值模擬結果與試驗結果之比較驗證此模式之合理性與正確性。並可進一步分析在軟岩中的邊坡穩定、淺基礎、深基礎等大地工程問題。

Because of the complex behavior of geomaterial mechanical property, including non-linear, the unrecoverable plastic displacement due to pressure, anisotropy, volume variation after shear stress, the effect of confining stress, stress history and stress path etc., it is hard to model by those simple mechanic model. The elasto-plastic model, a special version of the generalized transitional yielding approach, is adopted for modeling the mechanical behavior, strain hardening and volume variation, of soft rock. The model was carried out to simulate laboratory triaxial test in soft rock and application on footing bearing capacity. Optimized calibration by genetic algorithm is proposed for determining model parameters. The results of all soft-rock experiments carried out by the geotechnical group of National Chiao-Tung University. Compare the results of simulation and testing can proof the rationality and accuracy. Further, it may analysis the other geotechnical problems such as slope sliding, shallow foundation or deep foundation.