三峡库区175 m蓄水以来,巫峡段碳酸盐类岩溶岸坡在周期性水位变动下岩体劣化强烈,新生或加速形成了大量地质灾害.为探讨在周期性水位变动下碳酸盐岩类岸坡的强度弱化规律,文章从岩石(体)物理结构、化学性质、力学性质等方面开展研究,通过在巫峡最具代表性的6处库岸段开展原位岩体回弹强度测试、原位点荷载试验以及室内干湿循环试验、岩石矿物成分分析、岩石表观裂隙扫描等试验,获取水位变动条件下碳酸盐类岩石(体)的强度弱化数据.原位岩体回弹强度测试结果表明,原位岩体单一年度的强度弱化率为0.3％～25.9％,岩体强度弱化主要沿结构面产生;室内干湿循环试验结果表明,在50次干湿循环后,岩石强度弱化率为16.4％～23.9％,变形模量弱化率为17.1％～24.9％;岩石矿物成分分析结果表明,在100次循环后,CaO的溶失量为0.5％～5.6％;岩石表观裂隙扫描结果表明,岩块表面裂纹发育位置发生了水蚀痕迹加重、溶孔变大、裂纹延伸等变形现象.基于干湿循环试验数据,建立岩石强度弱化函数,推导出各点位上的指数函数弱化计算模型.该计算模型可用来预测岩石强度、变形模量与水位循环次数间的数值关系.最后以曲子滩危岩"溃屈"式破坏计算为例,探讨了岩体强度弱化后的灾变效应.研究提出的工作方法和通过试验所得到的数据可为三峡库区岸坡劣化带的防治提供数据和技术支撑.

The safety of the Three Gorges Reservoir, the world’s largest hydraulic project, has attracted significant attention. Among the landslides in the area, the Xinpu landslide complex stands out as one of the largest. However, accurately detecting and interpreting the timing and magnitude of its movement remains a challenge. This study introduces a framework using interferometric synthetic aperture radar (InSAR) for investigating the Xinpu landslide complex. In areas with dense vegetation like Xinpu, estimating landslide movement has traditionally been problematic. The proposed method, based on independent component analysis-assisted intermittent multi-temporal InSAR, overcomes this limitation by retrieving complete and reliable time-series deformation without prior deformation models. Through an analysis of Sentinel-1 datasets covering a period of 4 years, our approach significantly enhances deformation density and accuracy in comparison to other multi-temporal InSAR techniques. When contrasted with these methods, our proposed approach exhibits an average RMS improvement of up to 46.2% between GNSS measurements and the InSAR-derived results. The complete time-series deformation reveals diverse triggers at different sections of the Xinpu landslide complex. Precipitation, with a 45-day lag, primarily controls the landslide, while the toe of the landslide shows joint effects from precipitation and water level fluctuations, with a 14-day lag. Cross-correlation analysis estimates lag times for deformation responses to different triggers and enables discussion of the complex’s kinematic process. Overall, this approach enhances InSAR performance in vegetated areas and aids in uncovering landslide triggers for effective hazard mitigation.

The Qingshi landslide in the Three Gorges Reservoir was selected as a case study of ancient landslides. The detailed on-site surveys and long-term monitoring data were analysed to classify the triggering mechanism and possible evolution process of the Qingshi landslide. The results show that the ancient Qingshi landslide was triggered by the water storage in 2010. The leading edge slipped first, and the trailing edge underwent large-scale deformation after losing the resistance provided by the leading edge. In early 2011, the compaction of the leading edge of the landslide provided a certain resisting force, which controlled the overall downward movement of the landslide. In 2014, the integrity of the landslide was strengthened by emergency treatment measures, which caused the stabilization of the landslide and further reduced the displacement rate of the landslide. The local strengthening of the leading edge may act as a locking segment that could provide direct support to the sections in the middle and upper parts of the landslide. However, abnormal water-level regulation and heavy rainfall may cause the landslide to collapse again. The entire evolution process of the Qingshi landslide can provide an important reference for ancient landslides located on reservoir banks.

Scissors peak bank slope is located in the left bank of Wushan gorge in the Three Gorges Reservoir area, with a total length of 2.1 km. Influenced by Shennv peak box anticline in the north and Shennv Xi-Guandukou syncline in the south, the bank slope is steeply sloping bedding rock bank slope. The slope of the bank is 45°～89°, and the whole is a composite landform of steep slope and steep cliff.The quaternary strata exposed on the bank slope are mainly cluvial gravel soil, and the exposed bedrock contains the strata of the 3rd and 4th members of the Triassic daye formation and the 1st to 4th members of the Jialingjiang formation. The strata are diversified.The rock groups are mainly hard rock group composed of carbonate lute of Daye formation and Jialingjiang formation and soft rock group composed of karst breccia of the second member of Jialingjiang formation. The rock mass structure ranges from very thin layer to very thick layer, and the slope topography, stratum, rock group and structure are complex. Within a range of 2.1 km from upstream to downstream of the bank slope, the slope structure changes greatly, the deformation and failure characteristics of the bank slope vary greatly, and the formation mechanism and failure modes differ greatly. According to the different geological conditions and characteristics of the slope, it can be divided into 6 large sections and 6 sub-sections.Based on the characteristics of the macroscopic deformation and failure of the bank slope, the current deformation and failure of the bank slope are summarized into four aspects: "structural cutting and unloading", "local fracturing, sliding", "surface dissolution", and "rock mass deterioration in the subsidence zone", and the failure modes of each section are analyzed from the perspective of the formation mechanism of the bank slope. In addition, this study also analyzed the deterioration characteristics of rock mass in the bank slope above the reservoir water level and the reservoir water level fluctuation area, and proposed four types of rock mass deterioration and failure types from the perspective of rock mass deterioration: progressive release slip along the plane, collapse slip along the weak interlayer, X-type joint slip, and toppling collapse along the plane.

In this paper, the Jianchuandong dangerous rock mass in the Three Gorges Reservoir area is taken as an example to study the failure mode and protection of submerged thick-layer dangerous rock mass. Based on field investigation and the monitoring data, it was found that the degradation of the base rock mass under the dry-wet cycles is the main factor to accelerate the deformation of the dangerous rock mass. Its failure mode is determined as slip collapse. According to the deformation and failure characteristics of the dangerous rock mass, the corresponding treatment measure is divided into two parts, inculding the reinforcement of the weak base rock mass, and anchor cable in the upper part of the dangerous rock mass. By comparing the displacement field and the stress field before and after protection, it is found that the prestressed reinforcement of the upper dangerous rock mass can effectively control the deformation of the rock mass, and the reinforcement of base rock mass can effectively control the maximum shear stress of the dangerous rock mass. The comprehensive protection effect is significant to ensure the stability of dangerous rock mass. The protection method can provide important reference for the treatment of submerged dangerous rock mass in the reservoir area.

近年来重庆发生了大量缓倾顺层泥岩滑坡,造成了较大的经济损失.在对重庆綦江新炉村滑坡进行分析过程中,发现泥岩具有较强的膨胀力.本文通过室内岩体膨胀力试验,揭示了膨胀性泥岩在吸水情况下的膨胀规律,确定了其最大膨胀力大小约为180kN.以此试验为基础,初步探讨了在缓倾顺层泥岩滑坡启动过程中膨胀力所提供的作用,结合重庆綦江新炉村滑坡稳定性计算进行了数值模拟分析,提出在缓倾顺层泥岩滑坡勘查中,应加强岩矿分析和膨胀力试验分析,以对滑坡做出正确的评价.

The purpose of this paper is to study the sliding failure of the jointed rock slope caused by the degradation of rock mass mechanics under dry-wet cycles. Based on the mechanical parameters of reservoir limestone obtained under different numbers of dry-wet cycles, a discrete element approach was adopted to analyze the slippage failure mode of HuangNanBei slope in the Three Gorges Reservoir Region. The Barton-Bandis nonlinear strength criterion for discontinuities was used to improve the Mohr-Coulomb (M-C) sliding model, and the modified M-C sliding model could make the shear strength parameters of the discontinuities change with the stress state. Under the modified model, there was a tendency for disintegration between blocks in the process of slippage, which was more in line with the actual working conditions and proved the validity and necessity of this model. Furthermore, the slip rate increased with the increase of dry-wet cycles, and the increase trend had not slowed down after 30 dry-wet cycles. The cumulative displacement from 0 to 30 dry-wet cycles was obtained by changing the mechanical parameters of the discontinuities every 10 steps to simulate each dry-wet cycle. The pattern of the cumulative displacement curve was consistent with the slip curve of the 30th dry-wet cycle, which indicated that the degradation of the rock mass mechanics is irreversible. Consequently, strengthening the hydro-fluctuation belt is of great significance for disaster prevention and control in the reservoir region.

On June 28, 2016, a landslide occurred in Xinlu Village, Qijiang District, Chongqing, China. The landslide volume was 854,200 m(3). Exposed to continuous rainfall, the rocky part of the trailing edge slipped first, and then the soil part of the leading edge was pushed downward. Numerical simulations were used to analyze the formation characteristics of the landslide and to predict the stability of the landslide after the slip. In order to ensure the accuracy and rationality of numerical calculation, we used field surveys, laboratory tests, and back-calculation to restore the typical sections, determine the relevant mechanical parameters, and control boundary conditions. The displacement, stress, effective plastic strain distribution, and safety factor, obtained by numerical calculation, were compared to examine the action of rainfall. According to the evaluation of landslide stability and numerical calculation results, the Xinlu Village landslide remained in a peristaltic stage after the initial overall sliding, and additional sliding could occur under storm conditions.

三峡库区基岩顺层滑坡大多以砂/泥岩或泥/泥灰岩互层滑坡为主,力学机制以顺层滑移剪切为主.新近发现的青石-抱龙段顺层灰岩库岸,岸坡岩性以灰岩、白云岩为主.在21个顺向斜坡中9个斜坡存在岩层弯曲现象,高程分布在145～ 175 m,且大量层面有擦痕,局部岩层强烈弯曲形成了类似逆断层的现象.这些变形破坏现象受控于重力作用下沿层面的滑移-弯曲力学机制.通过连续-非连续数值分析方法研究表明,在这一带岸坡中约200 m的主动平直滑移段下滑力驱动了约30 m的被动弯曲隆起段变形,被动弯曲隆起段位移地形变缓、岩层增厚.当前青石-抱龙一带顺层灰岩库岸岩层隆起和松动较小,处于滑移-弯曲变形的早期阶段,主要以累进性变形为主.建议对该段库岸进行专业监测,并开展进一步的调查研究工作.

自三峡库区2009年蓄水至175 m以来,库水位常年在高程145-175 m间波动,形成了高差30 m的水位变动带(消落带).由于该变动带上岩体长期在饱和浸泡-风干曝晒的循环作用下,其物理力学强度不断减弱,于是大量的新生危岩和滑坡塌岸相继形成,此类地质灾害不仅点多面广,且破坏频率高,诱发因素甚多.本文以黄南背西危岩体为典型案例,基于影像资料、原位测试数据以及离散元数值模型深入分析了该危岩体未来失稳的破坏模式和变形成因机理,重点对该危岩体的应力场、形变场和基座岩体受水位作用影响展开研究.研究表明黄南背西危岩体发生失稳破坏的三种因素:1)底部岩体出现压溃破坏,2)底部破碎岩体受水影响劣化加剧,3)基座角砾岩岩体遇水水解.危岩体发生破坏将从其底部岩体出现压溃开始,上部岩体随后下错滑移,失稳岩体发生倾倒、滑移和坠落的复合型破坏.

The landslide thrust force is an important element in landslide treatment design.With the landslide residual pushing force curve,mechanical parameters of landslide can be analyzed in inverse method.According to the different forms of residual pushing force curve,different treatment designs were proposed,which can be used in landslide treatment design. The landslide project practice shows that this method is more convenient and intuitional.

The old methods for landslide thrust design had no clear mechanical concepts.Based on the residual thrust,this article firstly analyzed the stability of the sliding soil in front of pile,and got the thrust value in different calculation cases,when the residual thrust of last block was equal to zero or approached to zero.Then with the deflection of the pile,the equivalent deflection theory was established,a formula was set up between the residual thrust and resistance.This theory had clear mechanical concepts and the calculation values were close to those in other papers.This theory is useful for designing and utilizing anti-slide piles.