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

doi:10.3969/j.issn.0253-4967.2020.01.014

Abstract

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:

P694

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.

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.

Figures/Tables 17

Fig. 1 Shaking table device diagram for model test of soil-rock mixture deposit.

Table1 Similarity coefficients of model test

物理量	相似关系	相似比
长度l	C_l	Λ
位移u	C_u=C_l	Λ
速度v	C_v =(C_lC_a)^-1/2	λ^-1/2
加速度a	C_a	1
黏聚力c	C_v=C_l C_ρC_a	Λ
内摩擦角φ	C_c	1
振动频率f	C_f=(C_a /C_l)^1/2	λ^-1/2
时间t	C_t =(C_l/C_a)^1/2	λ^1/2
密度ρ	C_ρ	1

Fig. 2 Model of soil-rock mixture deposit(unit: mm).

Fig. 3 Physical model chart of soil-rock mixture deposit.

Fig. 4 Seismic time-history curve.

Fig. 5 Acceleration response of deposit with different slope gradients in horizontal direction.

Fig. 6 Acceleration response of deposit with different stone contents in horizontal direction.

Fig. 7 The horizontal acceleration response of the top of deposit with different slope gradients.

Fig. 8 The horizontal acceleration response of the top of deposit with different stone contents.

Fig. 9 The vertical acceleration response of deposit with different slope gradients.

Fig. 10 The vertical acceleration response of deposit with different stone contents.

Fig. 11 The vertical acceleration response of the top of deposit with different slope gradients.

Fig. 12 The vertical acceleration response of the top of deposit with different stone contents.

Fig. 13 Permanent displacement curves of different parts of deposit with different slope gradients.

Fig. 14 Permanent displacement curves of different parts of deposit with different stone contents.

Fig. 15 Modeling diagrams of soil-rock mixture deposit at different times during instability and failure process.

Fig. 16 Phenomenon chart of particle-size sorting at slope foot of physical model.

References 17

[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).
[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).
[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).
[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).
[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).
[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).
[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).
[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).
[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).
[10]	田颖颖, 许冲, 徐锡伟, 等. 2015. 2014年鲁甸MS6.5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: 10.3969/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 landslides triggered by the 2014 Ludian MS6.5 earthquake[J]. Seismology and Geology, 37(1): 291—306(in Chinese).
[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: 10.3969/j.issn.0253-4967.2013.02.021.
	XU Chong, XIAO Jian-zhang.2013. Spatial analysis of landslides triggered by the 2013 MS7.0 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).
[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: 10.3969/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 landslides[J]. Seismology and Geology, 34(1): 47—62(in Chinese).
[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).
[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).
[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).
[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).
[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).