摘要
斜坡中的软弱夹层往往控制着其变形破坏模式。在地震作用下,软弱夹层与地震波的复杂作用机制使得该类斜坡的地震响应特征很难被充分了解。在已有认识的基础上,开展4个含软弱夹层斜坡模型的振动台试验,旨在通过与均质斜坡模型响应进行比较,揭示含软弱夹层斜坡的地震动力响应特性,并观察软弱夹层在这一响应过程中所起的作用。主要研究结果为:(1)4个含软弱夹层模型的水平分量(PHA)和竖直分量(PVA)加速度响应均呈现出高程放大效应,且主要体现在夹层以上部位。在夹层以下部位,水平分量加速度放大系数始终保持在1.5以内。(2)与均质模型响应的比值表明,在夹层以上部位,夹层的存在对2个加速度分量的影响与夹层特征和激振强度密切相关。当激振强度较弱(≤0.3 g)时,厚夹层和薄夹层的存在都能对PHA和PVA响应起到增强作用。当激振作用增强时,厚夹层表现出了隔震作用,在坡顶,PHA和PVA响应相对均质模型分别减弱50%和70%。(3)与加速度响应一致,坡表水平向位移响应也呈现出了高程放大特征,且在坡顶最大。然而,与均质斜坡模型的初始变形出现在坡顶这一现象不同的是,含夹层模型的变形最早出现在夹层以上、坡顶以下的部位。分析产生这一差异的可能原因在于,当激振强度较大时,含夹层模型相对于均质模型在该部位的水平向响应强度显著增强,而夹层的挤压变形也可能造成初始变形部位更靠近夹层。(4)含软弱夹层模型的最终破坏部位和破坏程度,与夹层的厚度和倾角密切相关,表现为含水平夹层模型的破坏部位高于含反倾夹层模型,而含薄夹层模型的破坏程度高于含厚夹层模型。
The weak layer in a slope always controls slope deformation and failure mode. Under an earthquake,the complex interaction mechanism between the weak interlayer and the seismic waves hinders the understanding of the dynamic responses of this type of slope. Based on the existing knowledge,shaking table tests were conducted for four slope models containing a weak interlayer. The effects of the weak interlayer were uncovered by comparing the responses of the models with and without a weak interlayer. Both the horizontal(PHA) and vertical(PHA) acceleration responses were amplified along the altitude for all four slope models,especially in the locations with the elevation higher than the interlayer. In the locations with the elevation lower than the interlayer,the PHA amplification factor remained within 1.5. In comparison with the homogeneous model,the existence of an interlayer resulted the two component responses in the upper part of slope strongly depended on the features of the interlayer and the input intensity. When the input intensity was weak(≤0.3 g),the responses for the models with a thin or a thick interlayer were stronger than in the homogenous model. With the increasing of the input intensity,the thick interlayer generated an effect of seismic isolation,which caused the PHA and PVA responses at the slope crest decreasing by 50% and 70% respectively. The horizontal displacements on the slope surface were amplified and reached the maximum value at the crest. The initial deformation occurred at the top of for the homogeneous model slope. However,for the four models with a weak interlayer,the deformation was firstly observed in the position above the interlayer and below the crest. The location and the degree of the slope failure were closely related to the thickness and the dipping angle of the weak interlayer. The model with a horizontal interlayer caused the failure location higher than the models with an anti-dip interlayer and the model with a thin interlayer caused the failure more severe than the one with a thick interlayer.
引文
[1]许宝田,阎长虹,陈汉永,等.边坡岩体软弱夹层力学特性试验研究[J].岩土力学,2008,29(11):3 077–3 081.(XU Baotian,YAN Changhong,CHEN Hanyong,et al.Experimental study of mechanical property of weak intercalated layers in slope rock mass[J].Rock and Soil Mechanics,2008,29(11):3 077–3 081.(in Chinese))
[2]许宝田,钱七虎,阎长虹,等.多层软弱夹层边坡岩体稳定性及加固分析[J].岩石力学与工程学报,2009,28(增2):3 959–3 964.(XU Baotian,QIAN Qihu,YAN Changhong,et al.Stability and strengthening analysis of slope rock mass containing multi-weak interlayers[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(Supp.2):3 959–3 964.(in Chinese))
[3]郭富利,张顶立,苏洁,等.软弱夹层引起围岩系统强度变化的试验研究[J].岩土工程学报,2009,31(5):720–726.(GUO Fuli,ZHANG Dingli,SU Jie,et al.Change of strength of surrounding rock system induced by weak interlayer[J].Chinese Journal of Geotechnical Engineering,2009,31(5):720–726.(in Chinese))
[4]张农,李桂臣,阚甲广.煤巷顶板软弱夹层层位对锚杆支护结构稳定性影响[J].岩土力学,2011,32(9):2 753–2 758.(ZHANG Nong,LI Guichen,KAN Jiaguang.Influence of soft interlayer in coal roof on stability of roadway bolting structure[J].Rock and Soil Mechanics,2011,32(9):2 753–2 758.(in Chinese))
[5]范留明,李宁.软弱夹层的透射模型及其隔震特性研究[J].岩石力学与工程学报,2005,24(14):2 456–2 462.(FAN Liuming,LI Ning.Transmission model of weak intercalation and its vibration isolation properties[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(14):2 456–2 462.(in Chinese))
[6]王玉杰,陈先锋,彭天浩.浅析岩石夹层对爆破效果的影响[J].岩石力学与工程学报,2004,23(8):1 385–1 387.(WANG Yujie,CHEN Xianfeng,PENG Tianhao.Analysis on influence of rock interlayer on blasting[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(8):1 385–1 387.(in Chinese))
[7]李夕兵.论岩体软弱结构面对应力波传播的影响[J].爆炸与冲击,1993,13(4):334–342.(LI Xibing.Influence of the structural weakness planes in rock mass on the propagation of stress waves[J].Explosion and Shock Waves,1993,13(4):334–342.(in Chinese))
[8]王观石,李长洪,陈保君,等.应力波在非线性结构面介质中的传播规律[J].岩土力学,2009,30(12):3 747–3 752.(WANG Guanshi,LI Changhong,CHEN Baojun,et al.Propagation law of stress wave in nonlinear structural surface medium[J].Rock and Soil Mechanics,2009,30(12):3 747–3 752.(in Chinese))
[9]张奇.应力波在节理处的传递过程[J].岩土工程学报,1986,8(6):99–105.(ZHANG Qi.Propagation process of stress wave in rock joints[J].Chinese Journal of Geotechnical Engineering,1986,8(6):99–105.(in Chinese))
[10]范留明,闫娜,李宁.薄弹性软弱夹层的动力响应模型[J].岩石力学与工程学报,2006,25(1):88–92.(FAN Liuming,YAN Na,LI Ning.Dynamic response model for thin soft interlayer considering interbedded reflecting waves[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(1):88–92.(in Chinese))
[11]黄润秋,余嘉顺.软弱夹层的地震动强度效应研究[J].自然科学进展,2003,13(11):1 177–1 181.(HUANG Runqiu,YU Jiashun.Study on intensity effect of ground motion for weak intercalated layer[J].Progress in Natural Science,2003,13(11):1 177–1 181.(in Chinese))
[12]徐红玉,陈殿云,杨先健,等.弹性介质中平面SH波通过弹性夹层时的传播特性[J].岩石力学与工程学报,2003,22(2):304–308.(XU Hongyu,CHEN Dianyun,YANG Xianjian,et al.Propagation characteristics of plane SH wave passing through elastic interlining in elastic medium[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(2):304–308.(in Chinese))
[13]刘立平,杨实君,李英民.软夹层参数对边坡动力特性的影响分析[J].重庆大学学报:自然科学版,2007,30(5):31–34.(LIU Liping,YANG Shijun,LI Yingmin.Influence of soft soil layer on dynamic characteristic of the slope[J].Journal of Chongqing University:Natural Science,2007,30(5):31–34.(in Chinese))
[14]梁庆国,韩文峰,马润勇,等.强地震动作用下层状岩体破坏的物理模拟研究[J].岩土力学,2005,26(8):1 307–1 311.(LIANG Qingguo,HAN Wenfeng,MA Runyong,et al.Physical simulation study on dynamic failures of layered rock masses under strong ground motion[J].Rock and Soil Mechanics,2005,26(8):1 307–1 311.(in Chinese))
[15]杨国香,伍法权,董金玉,等.地震作用下岩质边坡动力响应特性及变形破坏机制研究[J].岩石力学与工程学报,2012,31(4):696–702.(YANG Guoxiang,WU Faquan,DONG Jinyu,et al.Study of dynamic responses characteristics and failure mechanism of rock slope under earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(4):696–702.(in Chinese))
[16]许强,刘汉香,邹威,等.斜坡加速度动力响应特性的大型振动台试验研究[J].岩石力学与工程学报,2010,29(12):2 420–2 428.(XU Qiang,LIU Hanxiang,ZOU Wei,et al.Study on slope dynamic responses of accelerations by large-scale shaking table test[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(12):2 420–2 428.(in Chinese))
[17]刘汉香,许强,侯红娟.岩性及岩体结构对地震作用下斜坡加速度响应规律的影响[J].岩土力学,2013,34(9):2 482–2 488.(LIU Hanxiang,XU Qiang,HOU Hongjuan.Influence of lithology and discontinuity on slope acceleration responses under an earthquake[J].Rock and Soil Mechanics,2013,34(9):2 482–2 488.(in Chinese))
[18]石乃鑫.含软弱夹层岩质边坡的地震时程响应分析[硕士学位论文][D].兰州:兰州理工大学,2010.(SHI Naixin.Dynamic response time-dependent analysis of rock slope with soft soil layer[M.S.Thesis][D].Lanzhou:Lanzhou University of Technology,2010.(in Chinese))
[19]邹威.强震作用下均质斜坡动力响应的大型振动台试验研究[硕士学位论文][D].成都:成都理工大学,2011.(ZOU Wei.Large-scale shaking table test on dynamic response of homogeneous slopes under the effect of strong earthquake[M.S.Thesis][D].Chengdu:Chengdu University of Technology,2011.(in Chinese))
[20]侯红娟.水平层状斜坡地震动响应特性的振动台试验研究[硕士学位论文][D].成都:成都理工大学,2013.(HOU Hongjuan.The seismic dynamic response characteristics of the shaking table test on horizontally layered slope[M.S.Thesis][D].Chengdu:Chengdu University of Technology,2013.(in Chinese))
[21]刘汉香.软硬岩组合型斜坡地震动响应的大型振动台模型试验研究[硕士学位论文][D].成都:成都理工大学,2011.(LIU Hanxiang.Large scale shaking table test study on seismic response of combinational rock slopes[M.S.Thesis][D].Chengdu:Chengdu University of Technology,2011.(in Chinese))