SEISMOLOGY AND GEOLOGY ›› 2020, Vol. 42 ›› Issue (1): 212-225.DOI: 10.3969/j.issn.0253-4967.2020.01.014

• Research paper • Previous Articles     Next Articles

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

HAN Pei-feng1,2,3)(), FAN Xiao-yi1,3), TIAN Shu-jun1,3), WEN Hua1,3), ZHANG You-yi1,3)   

  1. 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
  • Received:2019-04-01 Online:2020-02-20 Published:2020-06-17

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. 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:

    〔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

  • 基金资助:
    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

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.

Key words: soil-rock mixture deposit, stone content, slope gradient, peak ground acceleration, dynamic response

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

CLC Number: