含石量和坡度变化对土石混合堆积体的动力响应及失稳的影响

引用本文

韩培锋, 樊晓一, 田述军, 文华, 张友谊. 含石量和坡度变化对土石混合堆积体的动力响应及失稳的影响[J]. 地震地质, 2020,42(1): 212-225.
HAN Pei-feng, FAN Xiao-yi, TIAN Shu-jun, WEN Hua, ZHANG You-yi. STUDY ON DYNAMIC RESPONSE AND INSTABILITY OF SOIL-ROCK MIXTURE DEPOSIT WITH DIFFERENT STONE CONTENTS AND SLOPE GRADIENTS[J]. SEISMOLOGY AND GEOLOGY, 2020,42(1): 212-225. 复制到剪切板

DOI:10.3969/j.issn.0253-4967.2020.01.014
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含石量和坡度变化对土石混合堆积体的动力响应及失稳的影响

韩培锋^1,^2,³⁾, 樊晓一^1,³⁾, 田述军^1,³⁾, 文华^1,³⁾, 张友谊^1,³⁾

1) 西南科技大学, 土木工程与建筑学院, 绵阳 621010

2) 水利部山洪地质灾害防治工程技术研究中心, 武汉 430010

3) 工程材料与结构冲击振动四川省重点实验室, 绵阳 621010

〔作者简介〕韩培锋, 男, 1984年生, 2014年于中国科学院水利部成都山地灾害与环境研究所获岩土工程专业博士学位, 讲师, 研究方向主要为工程地质灾害发生机理、岩土工程渗流, E-mail: hanpeifeng@yeah.net。

收稿日期: 2019-04-01

基金项目: 国家重点研发计划项目(2018YFC1505401)、水利部山洪地质灾害防治工程技术研究中心开放基金(CKWV2019759/KY)、国家自然科学基金(41877524, 41971214)和四川省科技厅重点研发项目(2018SZ0345)共同资助

摘要

土石混合堆积体在地震荷载作用下的动力响应是研究其在地震荷载作用下失稳机理的重要指标。文中基于室内振动台模型试验, 研究了含石量和坡度变化对土石混合堆积体动力响应特征的影响。试验结果表明: 峰值加速度(PGA)的放大系数在水平方向随着高程的增加而增大; 坡度越大时水平方向的PGA放大系数越大, 而含石量越大时其对应的水平方向的PGA放大系数越小; 土石混合堆积体的坡脚处竖直方向的PGA放大系数增长明显, 而坡顶竖直方向的PGA放大系数有减弱的趋势; 相同激振强度下, 土石混合堆积体的坡度越大则坡体顶部的永久位移越大, 而含石量越大则对应的坡顶位移越小; 堆积体滑坡振动过程及滑动后, 大粒径颗粒向下运动的速度较快, 使得土石混合堆积体坡脚的堆覆具有非常明显的颗粒分选现象。文中的研究结果对于分析土石混合堆积体的含石量和坡度变化与其在地震荷载作用下的动力响应规律具有实际意义。

关键词: 土石混合堆积体; 含石量; 坡度; 峰值加速度; 动力响应

中图分类号:P694 文献标志码:A 文章编号:0253-4967(2020)01-0212-14

STUDY ON DYNAMIC RESPONSE AND INSTABILITY OF SOIL-ROCK MIXTURE DEPOSIT WITH DIFFERENT STONE CONTENTS AND SLOPE GRADIENTS

HAN Pei-feng^1,^2,³⁾, FAN Xiao-yi^1,³⁾, TIAN Shu-jun^1,³⁾, WEN Hua^1,³⁾, ZHANG You-yi^1,³⁾

1) School of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang 621010, China

2) Research Center on Mountain Torrent and Geological Disaster Prevention, Ministry of Water Resources,Wuhan 430010, China

3) Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province, Mianyang 621010, China

Abstract

Soil-rock mixture deposit is an extremely heterogeneous loose rock-soil deposit formed since Quaternary, which is composed of blocks, fine-grained soil and pore with a certain engineering scale and high strength and has a certain stone content. These soil-rock mixtures accumulated on slopes have been completely destroyed and their mechanical strength is very low. They are widely distributed in the mountainous areas of Southwest China, which poses a great threat to the engineering. Earthquakes occur frequently in Southwest China, and the instability of soil-rock mixture deposit under seismic load is one of the important factors causing the damage to this type of deposit. The dynamic response of soil-rock mixture deposit under seismic load is an important index to study its instability mechanism under seismic load.
Based on indoor shaking table model test, the influence of rock content and slope gradient on dynamic response characteristics of soil-rock mixture deposit was studied. In model tests, rock content is 30%, 40% and 50%respectively, and slope gradient varies from 20°, 30° and 40°. Two different seismic loading frequencies and three different excitation strengths were given. The peak acceleration(PGA)amplification coefficients in horizontal and vertical directions of soil-rock mixture deposit were analyzed under the change of rock content and slope gradient. The permanent displacement and deformation law of the top and foot of the slope of soil-rock mixture deposit were analyzed by model test. The experimental results show that the dynamic acceleration response characteristics of the soil-rock mixture deposits at the top and foot of the slope are different under different slope gradients and rock content conditions, and the horizontal PGA amplification coefficients of the soil-rock mixture deposits are also different. With the same seismic frequency and excitation intensity, the horizontal PGA amplification coefficient increases with increased slope gradient, and the rate gets faster. With the increase of stone content, the magnification coefficient of horizontal PGA decreases, and the higher the stone content, the slower the decrease rate of horizontal PGA magnification coefficient. When the slope gradient of soil-rock mixture deposit increases, the corresponding horizontal and vertical PGA amplification coefficients increase with the same seismic frequency and excitation intensity. The amplification coefficients of PGA in the vertical direction are different, but the overall magnification is weaker than that in the horizontal direction. The vertical PGA amplification coefficients of the foot, middle and lower parts of the slope are larger, while the vertical PGA amplification coefficients of the upper and middle parts of the slope tend to decrease. The higher the frequency of seismic wave is, the smaller the vertical PGA amplification coefficient corresponding to the same elevation will be, which indicates that the vertical PGA amplification coefficient is negatively correlated with the elevation. The variation trend of PGA magnification coefficient of soil-rock mixed deposit in vertical direction is different with the change of stone content. Under the same excitation intensity, the larger the slope gradient is, the larger the permanent displacement at the top of the slope will be, and the larger the rock content, the smaller the corresponding displacement at the top of the slope. The permanent displacement of the top of the slope is obviously larger than that of the foot of the slope, which indicates that the magnification effect of the top of the slope is obvious. After the vibration process and sliding of the landslide, the large-sized particles in the soil-rock mixture deposit move downward faster and slip on the surface of the deposit body. There was a very obvious phenomenon of particle sorting in the pile-up at the foot of the landslide body. The results of this study are of practical significance for the analysis of the dynamic response law of soil-rock mixture deposit under seismic load due to the change of rock content and slope gradient.

Keyword: soil-rock mixture deposit; stone content; slope gradient; peak ground acceleration; dynamic response

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0 引言

土石混合体是指第四纪以来形成的由具有一定工程尺度、强度较高的块石、细粒土体及孔隙构成且具有一定含石量的极端不均匀的松散岩土介质(徐文杰等, 2013)。强烈地震、崩塌和雨水冲刷搬运作用导致大量土石混合物堆积在坡体表面、沟道和坡脚, 形成大量土石混合堆积物斜坡。这些堆积在坡体上的土石混合体, 其结构已被完全破坏, 力学强度极低。影响土石混合堆积物斜坡稳定性的因素较多, 其中含石量和斜坡坡度是主要的影响因素(张倬元等, 1994)。在中国西南山区广泛分布的土石混合堆积体对工程沿线构成了极大威胁, 如川藏公路沿线(尚彦军等, 2001)等。因此, 开展地震荷载作用下土石混合堆积体动力响应特征研究对于认识该类型地质灾害的发生机理具有重要意义。

相关研究表明, 含石量是影响土石混合堆积体稳定性的重要因素。目前对于土石混合体中含石量变化的影响研究, 主要是采用大型剪切试验分析含石量的变化对其力学特性的影响(金磊等, 2015; 刘新荣等, 2017)。也有学者针对土石混合堆积体在含石量变化时的破坏过程开展研究工作, 并指出含石量对堆积体斜坡的变形失稳有重要影响(龚健等, 2017)。在数值计算方面, 则有相关工作通过数值模拟的方法研究含石量变化时土石混合堆积体的抗剪强度变化, 指出含石量较低时抗剪强度随含石量的增加而增加(金磊等, 2017; 严颖等, 2017)。坡面角度增加对岩质高陡边坡的加速度沿高程的放大效应明显(韩宜康等, 2014)。相关学者通过大型振动台模型试验开展了不同地形条件下岩质边坡动力响应特征的研究, 结果表明地形条件(尤其是坡度)对动力响应产生的影响较为明显(邹威, 2011; 刘汉香等, 2014)。

综上可知, 目前的研究主要集中在利用直剪试验探究含石量变化对土石混合堆积体的力学特性的影响及通过模型试验分析变形破坏过程, 而对于其在含石量变化时的动力响应研究不足。在坡度方面, 迄今主要分析了岩质坡体在地震荷载下的动力响应, 而对于土石混合堆积体动力响应的研究亟待加强。在地震灾区形成的土石混合堆积体成因各异, 其含石量和坡度也各不相同, 而这两者是影响土石混合堆积体在地震荷载作用下动力响应特征的重要因素。因此, 开展地震荷载作用下土石混合堆积体含石量和坡度变化的动力响应特征研究, 对于了解土石混合堆积体在地震荷载作用下的变形破坏机理十分重要。

基于上述分析, 本文采用室内大型振动台模型试验装置, 开展了不同含石量和堆积体坡度条件下土石混合堆积体在地震荷载作用下的模型试验, 以探讨地震荷载作用下含石量、坡度等因素对土石混合堆积体动力响应的影响, 从而为地震诱发土石混合堆积体失稳破坏的机理研究提供参考。

1 模型试验

1.1 试验设备平台

本试验在中国科学院水利部成都山地灾害与环境研究所内进行。试验振动台的设备主要有模型台基座、振动弹簧、激震电动机、调频箱、起降装置(调坡装置)、模型钢架和侧板等。振动弹簧共有4个, 位于基座横梁上以支撑上部模型箱, 最大载重达0.2t。模型台基座为型钢结构, 台基座底部设置可调节高度的升降螺杆。激震电动机采用MVE系列振动源三相异步电动机, 其激振力的调整范围为0~13 000kN, 可通过调频控制箱调节频率, 调频范围为0.5~50Hz, 方向为X和Z向。水平X方向可输入的最大加速度为0.8g, 竖直Z方向可输入的最大加速度为0.6g。试验平台的长、宽和高分别为2.6m、 0.5m和0.55m。在模型平台两侧安装侧板, 试验过程中可通过后缘底部的升降装置改变堆积体的坡度, 模型试验台与水平面夹角的调整范围为0° ~30° 。图 1 为模型试验振动台设备的照片。

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	图 1 堆积体模型试验振动台装置图Fig. 1 Shaking table device diagram for model test of soil-rock mixture deposit.

1.2 模型试验设计方案

本试验主要模拟土石混合堆积体的含石量和坡度变化时的动力响应特征, 因此进行相似关系设计时主要考虑2个因素(梁双庆等, 2016): 重力场对试验的影响S_G=1; 模型材料力学特征的相似性。以模型尺寸、堆积体密度和地震加速度为控制量, 按Buckingham π 定理导出各物理量之间的相似关系, 如表1所示, 其中λ =10。

表1 模型试验相似常数 Table1 Similarity coefficients of model test

土石混合体的含石量(粒径> 2mm)一般为25%~75%, 故设计含石量分别为30%、 40%和50%。试验的材料选择茂县某土石混合堆积体滑坡, 其含水率为13.5%, 容重为18.9kN/m³, 内摩擦角为38.9° , 黏聚力为39.7kPa。通过筛分试验, 将该土石混合堆积体中粒径< 2mm的细颗粒进行筛分后待用, 粒径为2~40mm的颗粒经筛分后作为块石料。根据等质量替换法, 替换粒径> 40mm的颗粒, 基于试验设计的含石量方案, 将粒径< 2mm的细颗粒和粒径为2~40mm的颗粒按照一定比例均匀混合后待用。相关研究指出, 大部分滑坡发生的坡度为20° ~50° (许冲等, 2012, 2013; 田颖颖等, 2015)。因此, 基于试验条件将模型试验土石混合堆积体的坡度设计为20° 、 30° 和40° 。

为保证试验过程中堆积体的密实度一致, 在进行试验之前需提前测试压实力度, 并基于试验要求选择合适的压实度。采取分3层堆积的方式, 每层厚18cm, 在堆积模型过程中用木槌沿整个层面均匀敲击相同的次数, 使得斜坡体的密实度一致。堆积模型时, 堆积体的坡面与试验平台的夹角为20° , 之后调整模型试验台的角度使其分别达到设计的角度要求。为了研究不同地震频率条件下不同含石量和坡度的土石混合堆积体的动力响应特征, 本文采用频率为15Hz和20Hz的正弦波, 设置3种不同的激振强度, 分别为0.2g、 0.3g和0.4g。

为监测地震荷载作用下堆积体中不同部位的动力响应特征, 分别在坡体内距离堆积体坡体表面的坡脚、坡面中间、坡顶处设置二向加速度监测传感器P1、 P2、 P3和P4, 4个监测点在竖直方向的高度分别为15cm、 25cm、 35cm和45cm, 并在振动台上设置加速度传感器以进行对比分析。在坡体顶部和坡脚分别埋设位移传感器D1和D2, 以监测不同频率和激振强度下土石混合堆积体的位移变化。土石混合体模型及加速度和位移监测点的布置如图 2 所示, 基于试验方案堆积的土石混合堆积体实物模型如图 3 所示。

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	图 2 土石混合堆积体模型图(单位: mm)Fig. 2 Model of soil-rock mixture deposit(unit: mm).

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	图 3 土石混合堆积体实物模型图Fig. 3 Physical model chart of soil-rock mixture deposit.

2 土石混合堆积体的加速度动力响应

峰值加速度(PGA)放大系数的定义为斜坡内任一点的响应加速度峰值与振动台面上响应加速度峰值的比值(韩培锋等, 2019)。设定基座台面的高程坐标为0, 每个监测点距离基座台面的高度为其相对高程值。通过测量监测点不同位置处的峰值加速度放大系数得到堆积体在不同高度处的加速度动力响应特征曲线。

本振动台模型试验的输入地震波为El Centro波, 时长为53.48s, 如图 4 所示。按照试验方案, 开展不同地震频率、不同激振强度下的振动台试验, 并在试验过程中监测坡体不同部位的加速度及坡体的永久位移。

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	图 4 地震波时程图Fig. 4 Seismic time-history curve.

2.1 水平方向的加速度响应

为便于分析, 选择输入地震频率为15Hz和20Hz、振幅为0.3g、含石量为30%和40%的土石混合堆积体模型试验为例进行分析, 得到不同地震频率作用下不同坡度和含石量土石混合堆积体水平方向的PGA放大系数随高程的变化规律, 试验结果如图5所示。

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	图 5 不同坡度的堆积体水平方向的加速度响应 a 含石量30%, 15Hz; b 含石量30%, 20Hz; c 含石量40%, 15Hz; d 含石量40%, 20HzFig. 5 Acceleration response of deposit with different slope gradients in horizontal direction.

从图5可知, 水平方向的PGA放大系数均大于1, 坡体不同部位的水平方向PGA放大系数各不相同, 且随着高程的增加放大系数的增加更为显著。土石混合堆积体不同临空面处的动力加速度响应差异明显, 坡脚处加速度的放大效应较弱, 而在坡顶放大效应最明显。土石混合堆积体的坡度不同, 水平方向PGA放大系数也不相同。当坡度为20° ~40° 时, 随着坡度的增大, 同一点上的水平方向PGA放大系数也相应增大, 且增大的速率越来越快。对比图5a和5b可看出, 地震波频率越高, 则堆积体水平方向的PGA放大系数越大; 当高程和坡度一致时, 地震波频率越高, 对应的水平方向PGA放大系数也越大。对比图5a与5c、 5b与5d可知, 在其它条件相同时, 含石量越大, 对应的水平方向PGA放大系数越小。

地震灾区土石混合堆积体由不同含石量的土石混合堆积而成, 其构成复杂, 块石含量将直接影响堆积体在地震荷载作用下的动力响应特征。为便于分析, 选择输入地震频率为15Hz和20Hz、激振强度为0.3g、坡度为30° 和40° 的土石混合堆积体模型试验为例进行分析, 通过试验得到不同含石量土石混合堆积体在不同高程处的水平方向PGA放大系数, 具体试验结果如图6所示。

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	图 6 不同含石量的堆积体水平方向加速度响应 a 坡度30° , 15Hz; b 坡度30° , 20Hz; c 坡度40° , 15Hz; d 坡度40° , 20HzFig. 6 Acceleration response of deposit with different stone contents in horizontal direction.

从图 6 可看出, 不同含石量的土石混合堆积体在不同高程处水平方向的PGA放大系数不一致, 其中坡脚处的放大系数最小。随着高程增大, 放大系数也相应增大, 至坡顶处其放大系数达到最大, 其值> 2, 说明地震波的峰值加速度放大效应较明显, 从而导致土石混合堆积体的坡顶在地震荷载作用下更容易发生失稳破坏。随着含石量的增加, 土石混合堆积体水平方向的PGA放大系数减小, 且含石量由40%增加到50%时其水平方向PGA放大系数的减小值比含石量从30%增加到40%时小, 该结果表明含石量越高则水平方向PGA放大系数的减小速率越慢。由于含石量较低时土石混合堆积体的刚度较低, 其形成的土石混合堆积体的固有频率与水平方向的地震波频率相近, 因此更容易形成共振, 使得响应增大。另外也可以看出, 随着相对高程的增大, 水平方向PGA放大系数快速增大, 且增大的速率越来越快。对比图6a、 6b可知, 地震波频率越高, 含石量相同的土石混合堆积体中同一点对应的水平方向PGA放大系数越显著。对比图6a与6c、 6b与6d可知, 在其它条件相同时, 土石混合堆积体的坡度越大, 对应的水平方向PGA放大系数越大。

为分析不同激振强度下堆积体的动力响应特征, 输入频率为15Hz和20Hz的地震波, 激振强度为0.2g、 0.3g和0.4g。选取土石混合堆积体坡顶(P4监测点)的水平方向PGA放大系数进行分析, 得到的响应变化结果如图 7 所示。

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	图 7 不同坡度的堆积体坡顶水平方向加速度响应 a 15Hz; b 20HzFig. 7 The horizontal acceleration response of the top of deposit with different slope gradients.

从图 7 可看出, 不同激振强度条件下土石混合堆积体在水平方向的PGA放大系数明显不同。随着激振强度的增大, 土石混合堆积体在水平方向的PGA放大系数先减小后增大, 在激振强度为0.3g时达到最小值, 土石混合堆积体在激振强度为0.2g时对应的水平方向PGA放大系数最大。这主要是由于当激振强度增大时, 土石混合堆积体内部出现局部开裂, 进而使得坡体出现局部应力调整, 从而影响放大系数的增大。由于土石混合体的结构较松散, 当激振强度继续增大时, 土石混合堆积坡体开裂后出现自愈合现象, 坡体内部逐步变得更加密实, 故其水平方向的PGA放大系数再次开始增大。对比图 7 可知, 地震波的频率对土石混合堆积体坡顶的水平方向PGA有明显影响, 当地震频率由15Hz增高到20Hz时, 坡体顶部的水平方向PGA系数明显增大。

不同含石量的堆积体坡顶水平方向的加速度响应如图 8 所示。从图 8 可看出, 含石量越大, 则相同激振强度对应的水平方向PGA放大系数越小, 土石混合堆积体的水平方向PGA放大系数随着激振强度的增大而增大。当含石量达到30%时, 堆积体坡顶的水平方向PGA放大系数开始增长较快, 随后增长减慢。而含石量较大时, 随着激振强度的增大, 堆积体坡顶水平方向PGA放大系数的增长速率越来越快, 地震波频率越高, 则坡体顶部水平方向PGA放大系数越大, 但增大现象不显著。

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	图 8 不同含石量的堆积体坡顶水平方向的加速度响应 a 15Hz; b 20HzFig. 8 The horizontal acceleration response of the top of deposit with different stone contents.

2.2 竖直方向的加速度响应

地震荷载作用下堆积体的动力响应主要集中表现在水平方向上。研究表明, 水平方向上的地震波对堆积体坡体的破坏作用更加显著, 但在竖直方向上地震波对堆积体的稳定性也将产生一定影响。为便于分析, 选择输入地震频率为15Hz和20Hz、激振强度为0.3g、含石量为50%的土石混合堆积体为例进行分析。图 9 给出了不同坡度条件下土石混合堆积体在不同高程处的竖直方向PGA放大系数的变化规律。

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	图 9 不同坡度的堆积体竖直方向的加速度响应 a 15Hz; b 20HzFig. 9 The vertical acceleration response of deposit with different slope gradients.

从图 9 可以看出, 随着土石混合堆积体相对高程的增加, 坡体内竖直方向的PGA放大效应没有水平方向明显。图9a和9b中标注了土石混合堆积体坡顶、坡脚的竖直方向PGA放大系数值。从图中可知, 对于竖直向的动力响应, 土石混合堆积体坡脚和坡体中下部的竖直方向PGA放大系数较大, 而上部和中部的竖直方向PGA放大系数有减弱的趋势。这一结论与前人的研究一致, 即竖直向加速度的高程放大效应主要表现在斜坡的中下部(杨国香等, 2012; 刘汉香等, 2014)。对比图9a和9b可知, 地震波的频率越高, 高程相同时对应的竖直方向PGA放大系数越小, 说明竖直方向的PGA放大系数与高程呈负相关。

块石含量不仅影响水平方向地震荷载作用下坡体的加速度峰值, 也影响竖直方向上的PGA放大系数。为便于分析, 选择输入地震频率为15Hz和20Hz、振幅为0.3g、坡度为30° 的土石混合堆积体为例进行分析, 通过试验得到不同含石量的土石混合堆积体不同高程处的竖直方向PGA放大系数的变化规律, 结果如图 10 所示。

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	图 10 不同含石量的堆积体竖直方向的加速度响应 a 15Hz; b 20HzFig. 10 The vertical acceleration response of deposit with different stone contents.

图 10 中, 当含石量为30%时, 堆积体在竖直方向上的PGA放大系数随着高程的增加而缓慢增大, 堆积体竖直方向的PGA放大系数在坡脚处最小, 而坡顶的放大效应最明显。当含石量继续增大到40%和50%时, 堆积体竖直方向的PGA放大系数表现出相反的趋势, 即在坡脚处放大系数较大, 而在坡顶处较小, 但都围绕着PGA为1的轴左右波动, 主要原因是当含石量较低时, 土石混合体整体表现偏向土体的性质, 而当含石量增大时, 土石混合堆积体逐渐表现出岩质堆积体的性质, 故其竖直方向PGA放大系数存在差异。

地震荷载作用下不同坡度的土石混合堆积体在竖直方向的动力响应特征与水平方向不同。为分析坡度与激振强度变化时土石混合堆积体竖直方向的动力响应特征, 选取输入地震频率为15Hz和20Hz、含石量为30%和40%时土石混合堆积体坡顶竖直方向的PGA放大系数进行分析, 得到的坡顶竖直方向加速度动力响应变化如图 11 所示。

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	图 11 不同坡度的堆积体坡顶竖直方向的加速度响应 a 含石量30%, 15Hz; b 含石量30%, 20Hz; c 含石量40%, 15Hz; d 含石量40%, 20HzFig. 11 The vertical acceleration response of the top of deposit with different slope gradients.

从图 11 可以看出, 不同激振强度条件下土石混合堆积体在竖直方向的PGA放大系数各异, 随着激振强度的增大, 土石混合堆积体在竖直方向的PGA放大系数逐渐减小, 随后再次增大, 但变化幅度较小。在激振强度为0.3g时竖直方向的PGA放大系数值最小。土石混合堆积体的坡度越大, 则相同激振强度对应的竖直方向PGA放大系数越大, 不同激振强度下土石混合堆积体在竖直方向上的PGA放大系数增长较缓慢。

为分析含石量与激振强度变化时土石混合堆积体竖直方向的动力响应特征, 选取输入地震频率为15Hz和20Hz、坡度为30° 和40° 时土石混合堆积体坡顶竖直方向的PGA放大系数进行分析, 得到的响应变化如图 12所示。

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	图 12 不同含石量的堆积体坡顶竖直方向的加速度响应 a 坡度30° , 15Hz; b 坡度30° , 20Hz; c 坡度40° , 15Hz; d 坡度40° , 20HzFig. 12 The vertical acceleration response of the top of deposit with different stone contents.

从图 12 可以看出, 不同激振强度条件下土石混合堆积体竖直方向的PGA放大系数各异, 相同含石量条件下随着激振强度的增大, 其竖直方向放大系数逐渐增大。相同激振强度下, 含石量越高的堆积体竖直方向的PGA放大系数值越小。对比图 12 可知, 地震波频率越高, 则相同激振强度对应的竖直方向PGA放大系数越大。

3 振动荷载作用下土石混合堆积体的变形规律

为分析地震荷载作用下土石混合堆积的位移变化规律, 利用位于坡体顶部和底部的D1和D2位移传感器进行监测, 分析地震波作用后堆积体的位移变化规律。当该坡体在地震荷载作用下发生失稳破坏时, 选取位移记录破坏前的最大位移。含石量为30%和40%、地震波频率为20Hz时在地震荷载作用下土石混合堆积体顶部和坡脚位移的变化规律如图 13 所示。坡度为30° 和40° 、地震波频率为20Hz时土石混合堆积体坡顶和坡脚的位移变化如图 14 所示。

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	图 13 坡度变化下堆积体不同部位的永久位移变化曲线 a 含石量30%, 坡顶; b 含石量40%, 坡顶; c 含石量30%, 坡脚; d 含石量40%, 坡脚Fig. 13 Permanent displacement curves of different parts of deposit with different slope gradients.

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	图 14 含石量变化下堆积体不同部位的永久位移变化曲线 a 坡度30° , 坡顶; b 坡度40° , 坡顶; c 坡度30° , 坡脚; d 坡度40° , 坡脚Fig. 14 Permanent displacement curves of different parts of deposit with different stone contents.

从图 13 可知, 地震荷载作用下土石混合堆积体的位移随坡度发生变化, 相同激振强度下, 堆积体的坡度越大, 其顶部和底部的永久位移越大。对比图 13 中坡顶和坡脚的位移变化可以看出, 坡顶的永久位移明显大于坡脚, 说明坡体顶部的放大效应更明显。由图 14 可知, 不同含石量对土石混合堆积体的位移影响差异明显。含石量越低时, 对应的坡体永久位移越大, 这与前面分析的动力响应的特征类似, 主要也是由于含石量为30%时堆积体本身的固有频率与地震波频率相近, 从而引起共振所致。

土石混合堆积体坡体表面在地震荷载作用下不断出现大粒径颗粒, 并有部分滚落到堆积体的坡脚处, 且大颗粒的滚落使得坡体局部出现明显的溜滑带, 堆积体与大颗粒之间的黏结较弱, 堆积体的滑动部分没有作为整体一起向下滑, 而是出现浅层溃散滑动, 土石混合堆积体的连续滑动面接近平面, 详见图 15。在振动过程中及滑动后, 土石混合堆积体中的大粒径颗粒向下运动的速度较快, 并在堆积体表面上溜滑, 最后在坡脚处堆覆, 出现非常明显的颗粒分选现象, 见图 16。

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	图 15 土石混合堆积体失稳破坏过程中不同时刻的模型 a t=95s; b t=103sFig. 15 Modeling diagrams of soil-rock mixture deposit at different times during instability and failure process.

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	图 16 物理模型坡脚处的颗粒分选现象Fig. 16 Phenomenon chart of particle-size sorting at slope foot of physical model.

4 结论

本文基于室内土石混合堆积体振动台模型试验, 分析地震荷载作用下含石量和坡度变化对松散堆积体动力响应的影响, 并讨论其水平和竖直方向的动力加速度响应、坡体永久位移的变化规律, 主要得出以下结论:

(1)不同坡度和含石量条件下土石混合堆积体在坡顶和坡脚表现出不同的动力加速度响应特征, 且水平方向的PGA放大系数也不相同。在相同地震频率和激振强度下, 随着坡度的增大, 其水平方向的PGA放大系数增大, 且增大的速率越来越快; 随着含石量的增加, 水平方向的PGA放大系数减小, 含石量越高, 水平方向PGA放大系数的减小的速率越慢。土石混合堆积体坡度增大时, 相同地震频率和激振强度对应的水平和竖直方向的PGA放大系数均增大。

(2)土石混合堆积体竖直方向上的PGA放大系数各异, 但整体较水平方向弱。坡脚和坡体中下部竖直方向的PGA放大系数较大, 而上部和中部竖直方向的PGA放大系数有减弱的趋势。地震波频率越高, 相对高程相同时对应的竖直方向PGA放大系数越小, 说明竖直方向的PGA放大系数与高程呈负相关。含石量不同时土石混合堆积体在竖直方向的PGA放大系数变化趋势不一致, 含石量为30%时竖直方向的PGA放大系数随着高程的增加而缓慢增大, 而当含石量继续增大到40%和50%时, 堆积体竖直方向的PGA放大系数则表现出相反的变化趋势。

(3)相同激振强度下, 土石混合堆积体的坡度越大, 坡体顶部的永久位移越大, 而含石量越高, 对应的坡顶位移则越小。坡顶的永久位移明显大于坡脚, 说明顶部的放大效应更明显。堆积体滑坡振动过程中及滑动后, 土石混合堆积体中的大粒径颗粒向下运动的速度较快, 并在堆积体表面上溜滑, 在堆积体坡脚的堆覆具有非常明显的颗粒分选现象。

参考文献

文献列表

[1]	龚健, 刘君. 2017. 基于PIV分析的含石量对土石混合体边坡破坏过程及模式的影响[J]. 岩土力学, 38(3): 696—704. GONG Jian, LIU Jun. 2017. Influences of rock proportion on failure process and failure mode of soil-rock-mixture slope with PIV analysis[J]. Rock and Soil Mechanics, 38(3): 696—704(in Chinese). [本文引用:1]
[2]	韩培锋, 樊晓一, 田述军, 等. 2019. 降雨强度与含石量对松散堆积体失稳影响研究[J]. 工程科学与技术, 51(1): 112—120. HAN Pei-feng, FAN Xiao-yi, TIAN Shu-jun, et al. 2019. Effect of rainfall intensity and stone content on the instability of Quaternary deposits[J]. Advanced Engineering Sciences, 51(1): 112—120(in Chinese). [本文引用:1]
[3]	韩宜康, 杨长卫, 张建经, 等. 2014. 坡面角度对岩质边坡加速度高程放大效应的影响[J]. 地震工程学报, 36(4): 874—880. HAN Yi-kang, YANG Chang-wei, ZHANG Jian-jing, et al. 2014 The influence of slope angle on the elevation amplification effect of rock slope acceleration[J]. China Earthquake Engineering Journal, 36(4): 874—880(in Chinese). [本文引用:1]
[4]	金磊, 曾亚武, 李欢, 等. 2015. 基于不规则颗粒离散元的土石混合体大三轴数值模拟[J]. 岩土工程学报, 37(5): 829—838. JIN Lei, ZENG Ya-wu, LI Huan, et al. 2015. Numerical simulation of large-scale triaxial tests on soil-rock mixture based on DEM of irregularly shaped particles[J]. Chinese Journal of Geotechnical Engineering, 37(5): 829—838(in Chinese). [本文引用:1]
[5]	金磊, 曾亚武, 张森. 2017. 胶结土石混合体力学特性的块石含量及形状效应大三轴试验研究[J]. 岩土力学, 38(1): 1—9. JIN Lei, ZENG Ya-wu, ZHANG Sen. 2017. Effects of rock block proportion and shape on mechanical properties of cemented soil-rock mixture by large scale triaxial tests[J]. Rock and Soil Mechanics, 38(1): 1—9(in Chinese). [本文引用:1]
[6]	梁双庆, 苏立君, 王洋. 2016. 不同坡面角度碎石土斜坡动力响应特征研究[J]. 振动与冲击, 35(21): 153—158. LIANG Shuang-qing, SU Li-jun, WANG Yang. 2016. Dynamic response characteristics of gravel soil slope with different angles of inclination[J]. Journal of Vibration and Shock, 35(21): 153—158(in Chinese). [本文引用:1]
[7]	刘汉香, 许强, 王龙, 等. 2014. 地震波频率对岩质斜坡加速度动力响应规律的影响[J]. 岩石力学与工程学报, 33(1): 125—133. LIU Han-xiang, XU Qiang, WANG Long, et al. 2014. Effect of frequency of seismic wave on acceleration response of rock slopes[J]. Chinese Journal of Rock Mechanics and Engineering, 33(1): 125—133(in Chinese). [本文引用:2]
[8]	刘新荣, 涂义亮, 王鹏, 等. 2017 基于大型直剪试验的土石混合体颗粒破碎特征研究[J]. 岩土工程学报, 39(8): 1425—1434. LIU Xin-rong, TU Yi-liang, WANG Peng, et al. 2017. Particle breakage of soil-rock aggregate based on large-scale direct shear tests[J]. Chinese Journal of Geotechnical Engineering, 39(8): 1425—1434(in Chinese). [本文引用:1]
[9]	尚彦军, 杨志法, 廖秋林, 等. 2001. 雅鲁藏布江大拐弯北段地质灾害分布规律及防治对策[J]. 中国地质灾害与防治学报, 12(4): 30—40. SHANG Yan-jun, YANG Zhi-fa, LIAO Qiu-lin, et al. 2001. Geological hazard distribution and prevention in North of Yalu Canyon, Tibet[J]. The Chinese Journal of Geological Hazard and Control, 12(4): 30—40(in Chinese). [本文引用:1]
[10]	田颖颖, 许冲, 徐锡伟, 等. 2015. 2014年鲁甸 M_S6. 5地震震前与同震滑坡空间分布规律对比分析[J]. 地震地质, 37(1): 291—306. doi: DOI: 103969/j. issn. 0253-4967. 2015. 01. 023. TIAN Ying-ying, XU Chong, XU Xi-wei, et al. 2015. Spatial distribution analysis of coseismic and pre-earthquake land slides triggered by the 2014 Ludian M_S6. 5 earthquake[J]. Seismology and Geology, 37(1): 291—306(in Chinese). [本文引用:1]
[11]	许冲, 肖建章. 2013. 2013年芦山地震滑坡空间分布分析: 以太平镇东北方向的一个典型矩形区为例[J]. 地震地质, 35(2): 436—451. doi: DOI: 103969/j. issn. 0253-4967. 2013. 02. 021. XU Chong, XIAO Jian-zhang. 2013. Spatial analysis of land slides triggered by the 2013 M_S7. 0 Lushan earthquake: A case study of a typical rectangle area in the northeast of Taiping town[J]. Seismology and Geology, 35(2): 436—451(in Chinese). [本文引用:1]
[12]	许冲, 徐锡伟, 于贵华. 2012 玉树地震滑坡分布调查及其特征与形成机制[J]. 地震地质, 34(1): 47—62. doi: DOI: 103969/j. issn. 0253-4967. 2012. 01. 006. XU Chong, XU Xi-wei, YU Gui-hua. 2012. Study on the characteristics, mechanism, and spatial distribution of Yushu earthquake triggered land slides[J]. Seismology and Geology, 34(1): 47—62(in Chinese). [本文引用:1]
[13]	徐文杰, 张海洋. 2013. 土石混合体研究现状及发展趋势[J]. 水利水电科技进展, 33(1): 80—88. XU Wen-jie, ZHANG Hai-yang. 2013. Research status and development trend of soil-rock mixture[J]. Advances in Science and Technology of Water Resources, 33(1): 80—88(in Chinese). [本文引用:1]
[14]	严颖, 赵金凤, 季顺迎. 2017. 块石含量和空间分布对土石混合体抗剪强度影响的离散元分析[J]. 工程力学, 34(6): 146—156. YAN Ying, ZHAO Jin-feng, JI Shun-ying. 2017. Discrete element analysis of the influence of rock content and rock spatial distribution on shear strength of rock-soil mixtures[J]. Engineering Mechanics, 34(6): 146—156(in Chinese). [本文引用:1]
[15]	杨国香, 伍法权, 董金玉, 等. 2012. 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, 31(4): 696—702. YANG Guo-xiang, WU Fa-quan, DONG Jin-yu, et al. 2012. Study of dynamic responses characteristics and failure mechanism of rock slope under earthquake[J]. Chinese Journal of Rock Mechanics and Engineering, 31(4): 696—702(in Chinese). [本文引用:1]
[16]	张倬元, 王士天, 王兰生. 1994. 工程地质分析原理 [M]. 北京: 地质出版社. ZHANG Zhuo-yuan, WANG Shi-tian, WANG Lan-sheng. 1994. Principle of Engineering Geological Analysis [M]. Geological Publishing House, Beijing(in Chinese). [本文引用:1]
[17]	邹威. 2011. 强震作用下均质斜坡动力响应的大型振动台试验研究 [D]. 成都: 成都理工大学. ZOU Wei. 2011. Large-scale shaking table test on dynamic response of homogeneous slopes under the effect of strong earthquake [D]. Chengdu University of Technology, Chengdu(in Chinese). [本文引用:1]

2017

0.0

... 也有学者针对土石混合堆积体在含石量变化时的破坏过程开展研究工作, 并指出含石量对堆积体斜坡的变形失稳有重要影响(龚健等, 2017) ...

2019

0.0

... 2 土石混合堆积体的加速度动力响应峰值加速度(PGA)放大系数的定义为斜坡内任一点的响应加速度峰值与振动台面上响应加速度峰值的比值(韩培锋等, 2019) ...

2014

0.0

韩宜康, 杨长卫, 张建经, 等. 2014. 坡面角度对岩质边坡加速度高程放大效应的影响[J]. 地震工程学报, 36(4): 874—880.

HAN

Yi-kang

, YANG

Chang-wei

, ZHANG

Jian-jing

, et al. 2014 The influence of slope angle on the elevation amplification effect of rock slope acceleration[J]. China Earthquake Engineering Journal, 36(4): 874—880(in Chinese).

A large-scale shaking table model test of a slope with a scale of 1:10 was introduced.The model slope was composed of soil with a height of 1.8 m，length of 4.4 m，and width of 4.4 m and included four slope angles of 30°，45°，50°，and 60°.The materials of the model test were blanc fixe，river sand，gypsum，clay，and water in various ratios.A series of tests was performed with various input seismic wave types，amplitudes，and frequencies.On the basis of field investigation results，shaking table test results，and theoretical analysis results，the influence of slope angle on the elevation amplification effect of rock slope acceleration was discussed.The results indicate that the amplifications of peak accelerations gradually increased with increases in slope angles.In addition，two inflection points were noted at slope angles of 45° and 50°，respectively，which suggests landslide hazards mainly occur on slopes with angles greater than 45°.Moreover，the amplification along the slope strike direction was essentially consistent，and the step was smooth.

基于现场调查、振动台试验及理论计算等结果，由宏观现象定性的分析到理论求解的定量计算，全面、系统地研究坡面角度对岩质高陡边坡的加速度高程放大效应的影响。现场调查结果表明，边坡的失稳破坏主要发生在45°及以上的斜坡，从宏观现象上间接说明了随着坡面角度的增大，边坡的加速度放大效应会逐渐增强；振动台试验和理论计算结果从半定量和定量的角度揭示随着坡面角度的增大，临空面方向、竖直方向峰值加速度的高程放大效应逐渐增强，而在增强的过程中同时存在突然增大的拐点45°和渐趋平缓的拐点50°，即在45°以下加速度放大效应的增长较为缓慢，在45°~50°之间突然增大，在50°以上增长又逐渐变缓，这充分解释了“滑坡灾害主要发生在45°以上的斜坡”这一汶川地震震害现象。边坡走向方向的峰值加速度高程放大效应基本上不随坡面角度的增大而变化，其台阶也相对较为平缓。

... 坡面角度增加对岩质高陡边坡的加速度沿高程的放大效应明显(韩宜康等, 2014) ...

2015

0.0

金磊, 曾亚武, 李欢, 等. 2015. 基于不规则颗粒离散元的土石混合体大三轴数值模拟[J]. 岩土工程学报, 37(5): 829—838.

JIN

Lei

, ZENG

Ya-wu

, LI

Huan

, et al. 2015. Numerical simulation of large-scale triaxial tests on soil-rock mixture based on DEM of irregularly shaped particles[J]. Chinese Journal of Geotechnical Engineering, 37(5): 829—838(in Chinese).

Based on the refined method for constructing DEM model based on the computed tomography scanning of irregularly shaped (IRS) particles, a random technique for constructing DEM model for IRS rock block is proposed, and 3D DEM models for soil-rock mixture (SRM) which conforms to the macroscopic statistical rule are established. In order to study the mechanical properties and deformation mechanism of SRM with various rock block proportions (RBP), DEM numerical simulations of large scale triaxial tests are conducted. It is noteworthy that with the increase of RBP, the peak strength, residual strength, elastic modulus and axial strain at peak strength all increase. The increase of RBP leads to the increase of shear dilatancy deformation and the decrease of shear contraction deformation. During the initial period of axial loading, the microcracks originate mainly from the contacts between rock particles and soil particles very quickly and then develop in the soil matrix. With the increase of RBP, the proportion of microcracks around the rock particles increases, and local shear bands become more and more irregular and scattered. The rock particles of SRM with high RBP exhibit obvious inter-friction just in the early period, and then their inter-locking and relative sliding appear alternately.

1. School of Civil Engineering, Wuhan University, Wuhan 430072, China; 2. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China

在基于CT扫描的不规则颗粒三维离散元精细建模技术的基础上,提出了一种不规则块石三维离散元模型随机生成技术,并建立了符合宏观统计规律的土石混合体三维离散元模型。进行了含石量为0,10%,30%,50%,70%,90%的土石混合体大三轴试验数值模拟研究,对各种含石量下土石混合体的力学特性和变形破坏机理进行了深入地分析探讨。结果表明：随着含石量的增加,试样峰值强度、残余强度、弹性模量和破坏应变逐渐增大,剪缩性减小,剪胀性增强;加载初期,微裂纹主要在块石颗粒与土颗粒之间形成,发展速度很快,而后则主要在土颗粒间形成和扩展,含石量越大,块石周围微裂纹比例越高,局部剪切带越不规则,分布也越分散;高含石量（70%,90%）的土石混合体在加载初期即有比较明显的相互摩擦,随后块石相互接触、咬合与相对摩擦、滑移交替出现。

... 目前对于土石混合体中含石量变化的影响研究, 主要是采用大型剪切试验分析含石量的变化对其力学特性的影响(金磊等, 2015 ...

2017

0.0

... 在数值计算方面, 则有相关工作通过数值模拟的方法研究含石量变化时土石混合堆积体的抗剪强度变化, 指出含石量较低时抗剪强度随含石量的增加而增加(金磊等, 2017 ...

2016

0.0

梁双庆, 苏立君, 王洋. 2016. 不同坡面角度碎石土斜坡动力响应特征研究[J]. 振动与冲击, 35(21): 153—158.

LIANG

Shuang-qing

, SU

Li-jun

, WANG

Yang

. 2016. Dynamic response characteristics of gravel soil slope with different angles of inclination[J]. Journal of Vibration and Shock, 35(21): 153—158(in Chinese).

A small-scale shaking table test with the geometric scale of 1:100 with angle of 35°，45°and 55°was designed. A series of tests were performed with X and Z direction sine wave of different frequency. The law of dynamic response and characteristic of deformation and failure of gravel soil slope were studied. Results showed that the elevation has amplification effect on seismic waves. The amplification of horizontal acceleration is stronger than vertical acceleration. As the increases of inclination angle, the peak of horizontal or vertical acceleration increases firstly and decreases secondly. The most obvious amplification occurs when angle is 45°. With the increase of elevation, the peak of horizontal acceleration increases slowly in lower part of slope, and increases quickly in upper part. The peak of vertical acceleration increases in total elevation without non-obvious separation elevation. As the increases of frequency, the peak of horizontal acceleration of the same elevation increases, and the peak of vertical acceleration increases firstly and decreases secondly. The most obvious amplification occurs when frequency is 25 Hz. The PIV analysis showed that the horizontal movement of slope shoulder is most obvious under 45°and 25Hz. Therefore, gravel soil slope is prone to emerge shoulder failure under earthquake action.

1. Key Laboratory of Mountain Hazards and Earth Surface Processes, Institute of Mountain Hazards and Environment, CAS, Chengdu 610041, China; 2. State Key Laboratory of Architecture Science and Technology in West China, Xi’an University of Architecture and Technology, Xi’an 710055, China; 3. CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China; 4.Graduated University of Chinese Academy of Sciences，Beijing 100049，China

设计并完成比例1：100的小型振动台模型试验，坡面角度为35°、45°、55°，在满足相似律的条件下，输入不同频率X，Z双向正弦波，研究碎石土斜坡动力响应规律和变形破坏特征。结果表明高程对地震波具有放大作用；水平向加速度峰值放大效应强于竖直向；随着坡面角度增大，水平向或竖直向加速度峰值高程放大效应先增强后减弱，45°时最显著；坡体下部水平向加速度峰值随高程缓慢上升，坡体上部快速上升；竖直加速度峰值在整个高程内上升，无明显分界；随频率增大，坡体内同一高程水平向加速度峰值变大，竖直向加速度峰值先增大后减小，25Hz时高程放大效果最明显。PIV结果表明坡度为45°，频率为25Hz时，坡肩水平向运动最剧烈。碎石土斜坡易发生坡肩破坏。

... 2 模型试验设计方案本试验主要模拟土石混合堆积体的含石量和坡度变化时的动力响应特征, 因此进行相似关系设计时主要考虑2个因素(梁双庆等, 2016): 重力场对试验的影响S_G=1 ...

2014

0.0

刘汉香, 许强, 王龙, 等. 2014. 地震波频率对岩质斜坡加速度动力响应规律的影响[J]. 岩石力学与工程学报, 33(1): 125—133.

LIU

Han-xiang

, XU

Qiang

, WANG

Long

, et al. 2014. Effect of frequency of seismic wave on acceleration response of rock slopes[J]. Chinese Journal of Rock Mechanics and Engineering, 33(1): 125—133(in Chinese).

Slope dynamic response to an earthquake is a product of interaction between seismic waves of complex frequencies and slope body；different frequency components induce different slope responses. Through shaking table tests，effect of wave frequency on two model slopes is analyzed. The two model slopes are composed of the same materials of high strength，but different structures，isotropic and layered. Firstly，dynamic characteristics of model slopes calculated through excitations of white noises show that，resonance frequency of each model decreases and the internal structure becomes loose as the test is going on；and the first resonance frequency of horizontal component acceleration is larger than that of vertical component acceleration. Then，emphasis is put on the slope acceleration responses and their correlations with changing frequencies. Results show that：(1) Obvious topographic amplification occurs in relative elevation h/H＞1/2 for horizontal component acceleration；while topographic amplification occurs in relative elevation h/H＜3/4 for vertical component acceleration；and the phenomena are independent of the excitation frequency. (2) Under the same excitation intensity，the horizontal component motion produces stronger response as the excitation frequency is increasing，more close to the resonance frequency. The correlation between vertical component response and frequency depends on the structure of model slope. (3) When the excitation intensity increases，the decay of slope structure (i.e. decease of resonance frequency) does not always cause attenuation of response，instead，high frequency excitation still can produce strong response due to the narrowing gap between excitation frequency and resonance frequency. (4) The layered model slope responses more severely than the isotropic model slope. Under strong motion，the structure effect is intensified for horizontal component and weakened for vertical component as excitation frequency increases.

(State Key Laboratory of Geohazard Prevention and Geoenvironment Protection，Chengdu University of Technology，Chengdu，Sichuan 610059，China)

斜坡在地震作用下的动力响应是地震波各频率组分与斜坡体共同作用的结果，不同的地震波频率将产生不同的斜坡响应。依托于振动台模型试验，针对均质和层状结构模型斜坡，首先分析试验不同阶段白噪声激振下的动力特性，得出两模型斜坡的共振频率呈现降低趋势，模型内部结构趋于松散，且水平向加速度的第1阶共振频率要低于竖直向加速度的第1阶共振频率。着重分析斜坡加速度动力响应规律及其与地震波频率变化的相关性，结果表明：(1) 两模型的水平向加速度响应在相对坡底高程(h/H＞1/2)时具有明显的高程放大效应，竖直向加速度响应的高程放大效应出现在h/H＜3/4的部位，且这一特征与激振频率的大小无关；(2) 在同等激振强度下，随着激振频率增大，越靠近模型斜坡的共振频率，两模型斜坡水平向加速度的响应程度也越高，而竖直向加速度响应强度与激振频率的相关性因模型斜坡结构不同而异；(3) 激振强度增加时伴随的模型结构恶化(即共振频率降低)并不一定导致加速度响应强度的减弱，相反，高频激振波由于更加接近模型的共振频率，使得响应减弱的可能性变小；(4) 层状结构模型斜坡的加速度响应强度大于均质结构模型斜坡，当激振强度较大时，这种层状结构效应与激振频率的相关性增强，表现为随着激振频率增大，该效应对水平向加速度而言逐渐明显，对竖直向加速度而言则相对减弱。

... 刘汉香等, 2014) ...

2017

0.0

... 刘新荣等, 2017) ...

2001

0.0

... 在中国西南山区广泛分布的土石混合堆积体对工程沿线构成了极大威胁, 如川藏公路沿线(尚彦军等, 2001)等 ...

2015

0.0

田颖颖, 许冲, 徐锡伟, 等. 2015. 2014年鲁甸 M_S6. 5地震震前与同震滑坡空间分布规律对比分析[J]. 地震地质, 37(1): 291—306. doi: DOI: 103969/j. issn. 0253-4967. 2015. 01. 023.

TIAN

Ying-ying

, XU

Chong

, XU

Xi-wei

, et al. 2015. Spatial distribution analysis of coseismic and pre-earthquake land slides triggered by the 2014 Ludian M_S6. 5 earthquake[J]. Seismology and Geology, 37(1): 291—306(in Chinese).

On August 3, 2014, an M S 6.5 earthquake happened in the Ludian County, Zhaotong City of Yunnan Province. This earthquake caused a large number of landslides. In order to study the spatial distribution of the coseismic and pre-earthquake landslides, a 44.13km 2 area at the junction of Ludian County, Qiaojia County and Huize County along the Niulanjiang River is selected in this study. By visual interpretation of the Google Earth pre-earthquake high resolution images and the coseismic aerial data of 0.2m resolution of this area, the landslide databases of pre-earthquake and coseismic are established. The result shows that there are 284 pre-earthquake landslides, and 1053 earthquake-induced landslides. Then with the help of 10m×10m resolution DEM data and the GIS, the extracted factors of elevation, slope angle, slope aspect, curvature, lithology, earthquake intensity and drainages are used to analyze the spatial distribution of the coseismic and pre-earthquake landslides by adopting LAP(Landslide Areas Percentage)and LND(Landslide Number Density). The results show that areas with elevation

1 Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China; 2 School of Engineering and Technology, China University of Geosciences, Beijing 100083, China

2014年8月3日, 云南省昭通市鲁甸县发生了 M S 6.5地震, 地震诱发了大量滑坡。文中以牛栏江沿线鲁甸县、巧家县和会泽县交界处面积为44.13km 2 的区域为研究区, 开展地震震前与同震滑坡的空间分布规律对比分析。根据震前Google Earth高分辨率影像与震后0.2m分辨率的超高分辨率航片数据, 分别建立了震前滑坡与同震滑坡数据库。结果表明, 研究区内震前有284处滑坡, 本次地震触发1 053处滑坡。借助10m×10m分辨率的数字高程模型(DEM)数据, 基于GIS平台提取研究区的高程、坡度、坡向、曲率、岩性、烈度、河流共7个主要因子, 并利用滑坡的面积百分比(Landslide Areas Percentage, LAP)和点密度(Landslide Number Density, LND)对比分析震前与同震滑坡的空间分布规律。结果表明, 震前与同震滑坡的易发高程区间分别为

... 田颖颖等, 2015) ...

2013

0.0

许冲, 肖建章. 2013. 2013年芦山地震滑坡空间分布分析: 以太平镇东北方向的一个典型矩形区为例[J]. 地震地质, 35(2): 436—451. doi: DOI: 103969/j. issn. 0253-4967. 2013. 02. 021.

Chong

, XIAO

Jian-zhang

. 2013. Spatial analysis of land slides triggered by the 2013 M_S7. 0 Lushan earthquake: A case study of a typical rectangle area in the northeast of Taiping town[J]. Seismology and Geology, 35(2): 436—451(in Chinese).

In this paper,a rectangle area of 20km?10km at the northeast of Taiping Town,which suffered strong shaking during the April 20,2013 M S 7.0 Lushan earthquake,was selected as the study area for spatial analyses of landslides triggered by the earthquake. Landslide distribution map of the study area was prepared based on quick field investigations and visual interpretation of high-resolutions aerial photographs. It is showed that at least 688 landslides were triggered by the Lushan earthquake and the landslide number density(LND)of the study area is 3.44 landslides/km 2 .Correlations of landslide number density with topographic,geologic and seismic parameters were analyzed based on the landslide inventory. The results show that the steeper the slopes,the greater the landslide number density values; the highest LND value appears at ranges from 1 600m to 1 800m in elevation. The landslides have preferred orientations,dominated by the east and SE directions. LND values of convex slopes are relatively higher. The limestone and dolomite of the Yangxin Group,Permian(P y )and granitic rocks of Proterozoic(Pt)experienced more concentrated landslides. In general,the higher the PGA value and seismic intensity zone,the greater the LND value. Correlation of landslide number density with distance from the Shuangshi-Dachuan Fault shows that there was not sudden change of LND value near the fault. The factor interaction statistics show that the slope angle and PGA affect the occurrence of earthquake-triggered landslides independently.

1. Key Laboratory of Active Tectonics and Volcano,Institute of Geology, China Earthquake Administration, Beijing 100029,China; 2. Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China

选择2013年芦山地震中受到强烈地震动的太平镇东北方向一个20km×10km的矩形区作为研究区,开展芦山地震滑坡空间分析工作.基于震后野外调查与高分辨率航片人工目视解译法,建立了研究区内地震滑坡空间分布图.结果表明,在研究区内芦山地震至少触发了688处滑坡,区域内滑坡点密度为3.44个/km 2 .统计了地震滑坡密度与地形因子、地层岩性、地震因子的关系.滑坡最易发高程为1 600～1 800m; 滑坡密度大体随着坡度的增加而增加; E与SE方向是地震滑坡的易发坡向与高发坡向; 凸坡的地震滑坡易发性最高.二叠系阳新组(P y )的灰岩与白云岩、元古界花岗岩(Pt)是地震滑坡的易发岩性.地震因子与滑坡密度的统计结果表明,大体上PGA值越大,地震烈度越高,地震滑坡越易发生; 地震滑坡与距离双石-大川断裂的统计结果表明在双石-大川断裂的出露处地震滑坡密度未发生突变.因子的交互统计结果表明了坡度与PGA这2个因子作用于地震滑坡的独立性.

... (许冲等, 2012, 2013 ...

2012

0.0

许冲, 徐锡伟, 于贵华. 2012 玉树地震滑坡分布调查及其特征与形成机制[J]. 地震地质, 34(1): 47—62. doi: DOI: 103969/j. issn. 0253-4967. 2012. 01. 006.

Chong

, XU

Xi-wei

, YU

Gui-hua

. 2012. Study on the characteristics, mechanism, and spatial distribution of Yushu earthquake triggered land slides[J]. Seismology and Geology, 34(1): 47—62(in Chinese).

On April 14,2010 at 07:49 (Beijing time), a catastrophic earthquake with M S 7.1 struck Yushu County, Qinghai Province, China. About 2036 landslides, covering an area of about 1.194km 2 , were interpreted from aerial photographs and remote sensing imageries and verified by field check. And based on the above, the spatial distribution of the Yushu earthquake triggered landslides is presented in this paper. The distribution of the landslides was strongly dominated by main surface ruptures, and their types are varied, with the collapse-type landslide as the dominant. There are five genetic mechanisms of Yushu earthquake triggered landslides, they are: the slope-toe excavation type, the surface water infiltration induced slope slip type, the fault dislocation type, the shaking type, and post-quake snow melting and rainfall penetration type. Besides the main seismic surface ruptures, there are many slope fissures developed mainly on the SE end of the surface rupture zone on the SW wall, an area undergoing intensive compression in the earthquake.

Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China

2010年4月14日青海省玉树县发生了 M S 7.1地震。文中基于现场考察与遥感影像目视解译的方法,对玉树地震滑坡进行分析,并制作了玉树地震滑坡空间分布图。结果表明,该地震触发了约2 036处滑坡灾害,总面积约1.194km 2 ;地震滑坡分布受主地表破裂控制作用强烈;滑坡类型多样,但以崩塌型滑坡为主;滑坡有5种成因机制:人工开挖坡脚型、地表水入渗致坡体震动滑动型、断裂错断震动型、震动型、后期冰雪融化或降雨入渗型;除地震主地表破裂外,还有许多坡体裂缝,主要分布在主地表破裂带SE端的SW盘,该部位在地震中受到了强烈的挤压作用。

... (许冲等, 2012, 2013 ...

2013

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... 0 引言土石混合体是指第四纪以来形成的由具有一定工程尺度、强度较高的块石、细粒土体及孔隙构成且具有一定含石量的极端不均匀的松散岩土介质(徐文杰等, 2013) ...

2017

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... 严颖等, 2017) ...

2012

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杨国香, 伍法权, 董金玉, 等. 2012. 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, 31(4): 696—702.

YANG

Guo-xiang

, WU

Fa-quan

, DONG

Jin-yu

, et al. 2012. Study of dynamic responses characteristics and failure mechanism of rock slope under earthquake[J]. Chinese Journal of Rock Mechanics and Engineering, 31(4): 696—702(in Chinese).

Large-scale shaking table test was performed to study dynamic response characters and failure mechanism of rock slopes triggered by Wenchuan earthquake. Sine waves with different frequencies，amplitudes and duration times were mainly input. Testing results show that：acceleration amplification coefficients increased nonlinearly with the increasing elevation，and they almost reach to maximum at slope surface and shoulder. Horizontal acceleration is amplified more obvious than vertical acceleration at top part of slope(above three-quarters of slope height) which is the opposite at the lower part. Acceleration amplification coefficients increased with the increasing seismic frequency nonlinearly；distribution of acceleration in slope body changed with variation of frequency. Once the input frequency approximated to the natural frequency of model slope，dynamic acceleration is amplified most obviously. Acceleration amplification coefficients increased with the increment of seismic wave amplitude；but amplitude doesn?t change the distribution of acceleration in slope body. Duration time of seismic wave has little influence on dynamic characters. Slope structure controls the deformation modes of rock slope；and acceleration amplification coefficients of bedding slope are about 15% more than those of the homogeneous slope，because of a large amount of structural surfaces in bedding slope which can make propagation of seismic wave more complex.

(1. Key Laboratory of Engineering Geomechanics of Chinese Academy of Sciences，Institute of Geology and Geophysics，Chinese Academy of Sciences，Beijing 100029，China；2. College of Resources and Environment，North China Institute of Water Conservancy and Hydroelectric Power，Zhengzhou，Henan 450011，China)

以汶川地震诱发大型岩质边坡为研究对象，基于相似理论，采用室内大型振动台模型试验，通过输入不同频率、不同持时以及不同幅值的正弦波，研究顺层及均质结构岩质边坡的动力加速度响应特征及动力输入参数对边坡动力特性的影响。试验结果表明，模型边坡动力加速度分布存在明显的而非线性高程放大特性及非线性趋表特性；且边坡对加速度的放大存在高度效应，即边坡中上部大约3/4坡高以上对水平加速度放大明显，而中下部对竖直加速度放大明显；受地形作用影响，边坡坡脚对加速度具有明显的抑制作用；地震波输入的动力参数对加速度动力特性有影响，地震波频率对加速度影响最为明显，边坡动力加速度随频率的增加而呈非线性增大的趋势，当地震波频率接近边坡模型自振频率时影响最大，且频率的增加改变坡体内加速度的分布特征；动力加速度随边坡输入加速度峰值的增加而增加，但幅值的变化并不改变加速度在坡体内的分布；地震波持时对动力加速度影响轻微。边坡坡体结构是影响其动力特性的重要因素，顺层结构边坡由于存在大量的结构面其动力加速度放大系数要高于均质结构边坡15%左右。

... 这一结论与前人的研究一致, 即竖直向加速度的高程放大效应主要表现在斜坡的中下部(杨国香等, 2012 ...

1994

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... 影响土石混合堆积物斜坡稳定性的因素较多, 其中含石量和斜坡坡度是主要的影响因素(张倬元等, 1994) ...

2011

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... 相关学者通过大型振动台模型试验开展了不同地形条件下岩质边坡动力响应特征的研究, 结果表明地形条件(尤其是坡度)对动力响应产生的影响较为明显(邹威, 2011 ...