工程地质学报  2018, Vol. 26 Issue (1): 179-192   (3989KB)
 Article Options PDF (3989KB) Full Text HTML Abstract Figures References History 收稿日期：2017-12-18 扩展功能 把本文推荐给朋友 加入引用管理器 Email Alert 文章反馈 浏览反馈信息 本文作者相关文章 薛雷 秦四清 泮晓华 陈竑然 杨百存 张珂

① 中国科学院地质与地球物理研究所, 中国科学院页岩气与地质工程重点实验室 北京 100029;
② 中国科学院地球科学研究院 北京 100029;
③ 中国科学院大学 北京 100049;
④ 南洋理工大学, 土木与环境工程学院 新加坡 639798

MECHANISM AND PHYSICAL PREDICTION MODEL OF INSTABILITY OF THE LOCKED-SEGMENT TYPE SLOPES
XUE Lei①②③, QIN Siqing①②③, PAN Xiaohua, CHEN Hongran①②③, YANG Baicun①②③, ZHANG Ke①②③
① Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029;
② Institutions of Earth Science, Chinese Academy of Sciences, Beijing 100029;
③ University of Chinese Academy of Sciences, Beijing 100049;
④ School of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639798
Abstract: The slope, whose stability is controlled by the locked segments within a potential slip surface, is referred to as the locked-segment type slope. It is well known that the instability prediction of slopes is a worldwide scientific problem. We suggest here that solving the instability prediction of the locked-segment type slope can be taken as a breakthrough because it has the explicit instability mechanism. In the present study, the classification method of locked-segment type slopes is discussed. It is pointed out that there exists an essential connection between three-phase creep development of the locked-segment type slope and the damage process of the locked segment, and that a locked-segment type slope will evolve into the tertiary creep stage when the cumulative damage of the locked segment reaches its volume dilation point. It is found that the peak strength point and the residual strength point of the locked segment can be regarded as two characteristic catastrophe points, respectively corresponding to the occurrence of the abrupt landslide and progressive one. Combining a one-dimensional renormalization group model with the strain-softening constitutive model of the locked segment, we establish the mechanical expressions among the volume dilation point, the peak strength point and the residual strength point and hence present a physical instability prediction model of locked-segment type slopes. The evolutionary mechanisms of three typical cases, the Yanchihe avalanche, the Xintan landslide and the wedge rockslide on the left abutment of Libby Dam, are reasonably explained and satisfied retrospective analysis results are obtained by the model. Finally, some related supporting techniques and applying principles about the model are introduced for actual applications.
Key words: Locked-segment type slope    Locked segment    Abrupt landslide    Progressive landslide    Tertiary creep    Instability prediction

0 引言

 图 1 锁固型斜坡示意图(据杨百存等(2017)修改) Fig. 1 Schematic illustration of the locked-segment type slope

1 锁固型斜坡分类

 图 2 锁固型斜坡分类(据Chen et al.(2017a)修改) Fig. 2 Classification of the locked-segment type slopes

1.1 跨层斜切式

1.2 顺层直剪式

1.3 均质岩桥式

1.4 挡墙式

1.5 支撑拱式

2 锁固型斜坡失稳的物理预测模型

 图 3 锁固型斜坡演化过程(a)与锁固段变形破坏过程(b)的对应关系(据秦四清等(2010a)和Xue et al.(2014a)修改) Fig. 3 Corresponding connection between the creep process of the locked-segment type slope(a) and the damage process of the locked segment(b)

 图 4 三轴压缩下花岗岩AE事件从随机分布到丛集的演化(据Lei et al.(2004)修改) Fig. 4 Evolution of AE events from random to cluster distribution for a granite specimen subjected to triaxial compression

 $p = 1 - {{\rm{e}}^{ - \left( {\frac{\varepsilon }{{{\varepsilon _0}}}} \right)m}}$ (1)

 $\tau = {G_{\rm{s}}}\varepsilon {{\rm{e}}^{ - \left( {\frac{\varepsilon }{{{\varepsilon _0}}}} \right)m}}$ (2)

 $\frac{{{\varepsilon _{\rm{f}}}}}{{{\varepsilon _0}}} = {\left( {\frac{1}{m}} \right)^{\frac{1}{m}}}$ (3)

 $\frac{{{\varepsilon _{\rm{t}}}}}{{{\varepsilon _0}}} = {\left( {\frac{{m + 1}}{m}} \right)^{\frac{1}{m}}}$ (4)

 ${p_{\rm{c}}} = 1 - {2^{\frac{1}{{1 - {2^m}}}}}$ (5)

 图 5 锁固段体积膨胀点的物理意义 Fig. 5 The physical implication of the volume dilation point of the locked segment a.不稳定不动点pc迭代求解过程；b.锁固段变形破坏过程

 图 6 锁固段破裂一维重正化群模型示意图(据秦四清等(2010a)和Xue et al.(2014a)修改) Fig. 6 Schematic illustration of one-dimensional renormalization group model describing the failure process of locked segment

 $\frac{{{\varepsilon _{\rm{c}}}}}{{{\varepsilon _0}}} = {\left( {\frac{{\ln 2}}{{{2^m} - 1}}} \right)^{\frac{1}{m}}}$ (6)

 $\frac{{{u_{\rm{f}}}}}{{{u_{\rm{c}}}}} = {\left( {\frac{{{2^m} - 1}}{{m\ln 2}}} \right)^{\frac{1}{m}}}$ (7)

 $\frac{{{u_{\rm{t}}}}}{{{u_{\rm{c}}}}} = {\left[ {\frac{{\left( {1 + m} \right)\left( {{2^m} - 1} \right)}}{{m\ln 2}}} \right]^{\frac{1}{m}}}$ (8)

 $\frac{{{u_{\rm{t}}}}}{{{u_{\rm{f}}}}} = {\left( {1 + m} \right)^{\frac{1}{m}}}$ (9)

 ${u_{\rm{f}}} = 1.48{u_{\rm{c}}}$ (10)

 ${u_{\rm{t}}} = 2.49{u_{\rm{c}}}$ (11)

 ${u_{\rm{t}}} = 1.68{u_{\rm{f}}}$ (12)

 ${u_{\rm{f}}}\left( k \right) = {1.48^k}{u_{\rm{c}}}$ (13)

 ${u_{{\rm{t - last}}}} = 2.49{u_{{\rm{c - last}}}}$ (14)

 ${u_{{\rm{t - last}}}} = 1.68{u_{{\rm{f - last}}}}$ (15)

 $\Delta = \frac{{u_{\rm{f}}^ * \left( 1 \right) - 1.48u_{\rm{c}}^ * }}{{0.48}}$ (16)

 图 7 斜坡平面滑动失稳力学模型 Fig. 7 Mechanical model of instability for a planar-slip slope

3 典型案例分析
3.1 盐池河山崩

1980年6月3日，湖北远安县盐池河磷矿发生灾难性大型山体崩塌(地理坐标为111.299°E，31.209°N)，导致整个工矿区被毁，造成约284人死亡以及2 500万元财产损失。崩塌体在脱离鹰嘴崖山体垮落冲击地面过程中，引起一次与MS1.6天然地震能量近乎相当的强烈震动，并最终散落在崖下河谷宽缓地带和斜坡上，形成南北长约560 m、东西宽约400 m、最大厚度约40 m、方量约100×104 m3的堆积体，导致河道堵塞形成堰塞湖(荣建东，1981; 连志鹏等，2013; 李腾飞等，2016)。

 图 8 盐池河崩塌山体地质剖面示意图(a)及1980年裂缝Ⅳ水平位移观测记录(b) (据孙玉科等(1983)和杨百存等(2017)修改) Fig. 8 Sketch of geologic profile map of the Yanchihe avalanche(a) and cumulative horizontal displacement observed at crack Ⅳ in 1980(b)

3.2 新滩滑坡

1985年6月12日凌晨，在长江西陵峡上段兵书宝剑峡出口，湖北省秭归县新滩镇以北至广家崖一线斜坡上(地理坐标为110.808°E，30.951°N)，发生了约3 000×104m3的巨型堆积层滑坡，造成新滩古镇全部被毁。庆幸的是，滑区内居民1 371人在滑坡发生前，已全部安全转移，无一伤亡。这一滑坡灾害史上的奇迹，一方面归功于政府果断决策、组织撤离有力，另一方面更是得益于科研人员开展的长期位移监测、中长期预报分析和及时的临滑报警(陈德基等，1985; 傅冰清等，1989; 王尚庆，1996)。

 图 9 新滩滑坡地质剖面图(a)、“支撑拱”模型(b)、A3监测点水平位移观测记录(c)及降雨资料(d) Fig. 9 Geologic profile map of the Xintan landslide(a); Sketch illustrating the soil arch structure that acts as the locked segment(b); Cumulative horizontal displacement observed at monitoring point A3(c); Monthly rainfall record(d)

3.3 Libby坝左坝肩楔形岩质滑坡

1971年1月31日，美国蒙大拿州Libby坝左坝肩楔形岩质斜坡(图 10a)发生失稳滑动(地理坐标为115.309°W，48.408°N)，庆幸的是此次事件未造成人员伤亡。该楔形岩质滑坡两侧边界分别由层理面DS+122和节理面A切割而成，前缘坡脚因开挖修建蒙大拿州37号高速公路而出现临空面(图 10b)(Voight，1979)。根据层理面DS+122相对光滑平整，而节理面A粗糙度较大的特征，Xue et al.(2017)推测该楔形滑坡在滑动之前沿节理面A应存在未贯通锁固段。按照我们提出的锁固型斜坡分类体系(二)的标准，推测该滑坡属于“跨层斜切式”。

 图 10 Libby坝左坝肩1971年楔形岩质滑坡俯视图(a)、正视图(b)及H监测点位移观测记录(c) Fig. 10 Top view of the wedge rockslide on the left abutment of Libby Dam(a); Front view(b); Stair-step movement record observed at monitoring point H(c)

4 讨论与结论

4.1 斜坡代表性位移监测数据的遴选原则

4.2 锁固段赋存位置与数目的判识

4.3 锁固型斜坡加速蠕滑阶段起点的判识