1State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China2Dadu River Hydropower Development Company, Ltd., Chengdu 610016, China3Power China Guiyang Engineering Corporation Limited, Guiyang 550081, China4Sichuan Highway Planning, Survey, Design and Research Institute Ltd., Chengdu 610041, China5College of Water Resource and Hydropower, Sichuan University, Chengdu 610065, China
Correspondence should be addressed to Jia-wen Zhou; [email protected]
Received 5 July 2020; Revised 13 August 2020; Accepted 19 August 2020; Published 28 August 2020
A series of settlement, cracking, and collapse of the Zhengjiaping slope has been increasingly developing since October 2015during impoundment at the DagangshanHydropower Station. It is a dangerous signal, whichmeans thatlandslide potential will beexisted for the Zhengjiaping slope and poses greatthreat to the operation of hydropower station and traffic safety. Related slopeprotection measures and research studies have been implemented accordingly in the Zhengjiaping slope to prevent and controladverse influences on property security and human life in the reservoir area. In order to understand the geological and hy-drological settings of the Zhengjiaping slope and its surroundings, a field investigation was carried out to determine thelithological composition and toppling/sliding deformation characteristics using exploratory adit and site boreholes. +e largedeformation process in the apparently deformed area was analyzed using borehole inclinometers and global navigation satellitesystems (GNSS). It was found that the apparently deformed area zone was characterized by crushed rock masses, with only a smallamount of slope deposits and the sliding deformation occurring in Zone I. +e deformation process of the reservoir landslide wasconsidered to be a complex integration of the geological effects of various adverse factors. Impoundment and heavy rainfall are thedirect causes of sliding deformation. During the preparation of the basic conditions for sliding, lithology, tectonic activity, andartificial disturbances play an important role, including the sliding mass and the sliding surface zone.
1. Introduction
Reservoir landslides are various types of gravitational massmovements of the earth’s surface that occur on the banks ofthe reservoir area [1, 2]. According to a field investigation,the origin of reservoir landslides is complicated and mul-tiple: (i) slope deposits by alluviation, proluvial action,colluviation, ancient landslide action, or hybrid origin; (ii)broken rock mass by weathering, runoff erosion, tectonicactivities, seismic load, artificial disturbances; and (iii) rockmass with the involvement of soft interlayer. Furthermore,differences also exist in proportion of the shallow earth with
deformation occurring in the mass above the sliding surface.Integral failure or disintegrated failure has been ever pre-sented in previous occurrences of reservoir landslides be-cause of the differences in the amount and developmentdegree of the sliding surface zone [3, 4].
+e preparation and occurrence of reservoir landslides isa very complex and dynamic process that is a long-playingintegration of multiple factors. It is generally accepted thatimpoundment, reservoir level fluctuations, rainfall, andartificial disturbances are the main contributing factors[5–10]. +ere have been many studies focusing on the originof reservoir landslides from slope deposits [11–14]. For slope
HindawiAdvances in Civil EngineeringVolume 2020, Article ID 8852227, 13 pageshttps://doi.org/10.1155/2020/8852227
deposits, impoundment and the coupling of heavy rainfalland reservoir level drawdown during the operational periodweakens the physical and mechanical properties of the slopematerial, forms transient seepage, and changes the me-chanical behavior, which are highly conducive to the oc-currence of reservoir landslides [15]. Understanding howadverse factors contribute to the formation of sliding con-ditions for the earth’s surface and the causative factors thatcause sliding deformation is particularly important forlandslide prevention and mitigation. A comprehensiveunderstanding of reservoir landslides is important forpredicting or identifying precursor phenomena to largereservoir landslides and further generating a series of ef-fective prevention and control measures. Few articles havemade specific reference to reservoir rock landslides, butprevious studies have made important contributions to theunderstanding of different aspects related to general rockslide failures. From these studies, there are implications forthe understanding of reservoir landslides. Field investigationof geological conditions and characterization of the velocity,distribution, and evolution of movement are fundamentaltasks for understanding unstable slope behavior and po-tential failure [16–18]. According tomany cases, topography,lithology, geological structure, and tectonic activity play animportant role in the development of slope instability, whichshould usually be a long-term evolutionary process from itsinception to catastrophic failure [19]. For rock slopes withpotential geologic hazards, the temporal evolution of geo-morphology and structure, as well as the influence of lith-ologic differences and tectonic activity on slope deformation,are of great interest [20–25]. For rock slopes that haveundergone landslides, mathematical description of the dy-namic mechanisms and kinematic processes of disastertriggers is a key point [26–32]. To prevent the occurrence ofrock slides, methods for evaluating the stability of slopes inreservoir areas have been investigated, such as develop-mental characterization of cracked rock masses, reliabilityanalysis of rock slopes, or predictive models based onmonitoring or statistical analysis [33–39].
Reservoir landslides, as a notable geological hazard inreservoir areas, are characterized by their large scale andwidespread impact. Reservoir landslides pose a great threatto human beings, environmental stability, property safety,and reservoir operation [2, 15]. +e reservoir area insouthwest China has steep topography and fragile geology,with broken rock masses in shallow earth and quaternaryaccumulations covered. +e complex geological conditionsof the reservoir area are not conducive to slope stability.With the gradual development of cascading hydropowerstations, the frequent occurrence of reservoir landslides hasseriously threatened the safety of power station buildingsand the stability of the reservoir area slopes. At present, thestudy of reservoir landslides has become one of the im-portant tasks of hydropower development in southwestChina.
+is paper takes the Zhengjiaping slope as an example tostudy the deformation characteristics and mechanism of therock slope deformation occurring in the reservoir area. +egeological conditions, lithologic composition, and toppling
deformation characteristics revealed by the field survey arethe basis for understanding the deformation behavior of theZhengjiaping slope. +e monitoring mainly includes lateraldisplacement and surface point displacement. +e results oflateral displacement and geologic cognition can confirm theexistence of basic conditions for sliding deformation, in-cluding sliding mass and sliding surface zone.+e analysis ofsurface point displacement is used to identify the factorsinvolved in the deformation of the Zhengjiaping slope,including the adverse factors in the preparation of defor-mation and causative factors. +en, the influence of unfa-vorable factors on the process of formation and evolution ofsliding deformation is discussed in order to refine somepeculiarities of rock slides in the reservoir area.
2. Study Area
+eZhengjiaping slope is located in Xingfu Village, TianwanTownship, Sichuan Province, in the central alpine regionbetween the Tibetan Plateau and the Sichuan Basin insouthwestern Sichuan Province, as shown in Figure 1(a).+eZhengjiaping slope is located upstream of DagangshanPower Station on the right bank of the Dadu River, about15 km from the dam site of Dagangshan Power Station,asshown in Figure 1(b). According to the relationship betweenrock inclination and slope ([40], Figure 2), the Zhengjiapingslope belongs to the anaclinal slope. +e slope of theZhengjiaping side slope is 30°–40°, and the surface is mostlycovered by accumulated deposits.
Figure 3(a) shows the lithology of the Zhengjiaping slopeand the surrounding area. +e evident deformation zone inthe Zhengjiaping slope was developed in the stratifiedsandstone and shale of the Baiguowan Formation. +eBaiguowan Group is distributed between the East BranchFault (F1) and the West Branch Fault (F2) of the Dadu RiverFracture Zone. +e lithology of the Baiguowan Group ismostly siltstone mudstone, with gray sandstone and gray-black carbonaceous shale in the interlayer. +e Chengjiangstage, characterized by granite, is distributed on the left bankof the Dadu River and the footwall of the East Branch Faultof the Dadu River Fracture Zone on the right bank. +eZhongdian period is characterized by tonalite gneiss anddiorite gneiss, which are distributed in the footwall of theWest Branch Fault (F2) of the Dadu River Fracture Zone.+e area below 1130m elevation of the Zhengjiaping slope islocally covered by the accumulation of quaternary system.As shown in Figure 4, this study investigated the defor-mation quality of the Zhengjiaping slope by exploratoryholes and eight site boreholes. +e horizontal length of oneexploratory borehole was 100m and the investigation depthof the site borehole was 80m. +e Zhengjiaping slope hasstrong and weak weathering zones, as well as non-corresponding strong and weak unloading zones, with intactfresh rock at depth. Figure 5 shows the attitude of slopesurface, bedding plane, and major joints. Table 1 shows thevolume content of the different lithologies, and Figure 6shows the degree of weathering and unloading of the rockmasses at different depths.
2 Advances in Civil Engineering
+e impoundment in Dagangshan Hydropower Stationbegan in May 2015. In October 2015, during the process ofrising to normal water level, cracks were found in the middleand leading edge of the Zhengjiaping slope. By the end ofFebruary 2016, the width, number, and distribution range ofcracks increased. In addition, a localized area of theZhengjiaping slope has a more pronounced deformation inthe 1100–1260m elevation range. A number of cracks havebeen intermittently distributed along the back edge,extending about 100m in length, 10–60 cm in width, and20–50 cm in vertical offset. On both sides, cracks have amaximum crack aperture of 35 cm and a vertical offset of
about 20 cm. On 22 April 2016, a large number of bubbleswere found emerging from the water surface of the reservoirnear the upstream of the study area.
3. Methods
+e distinct deformation zone of the Zhengjiaping slopeextends from 1,125m from the front elevation to 1,330mfrom the back elevation along the direction orthogonal to theflow direction of the Dadu River. According to the differentdeformation characteristics, the study area can be dividedinto Zone I and Zone II. +e volume of Zone I is about
N
Dam site
Dadu River
Deformed area in Xinhua slope
(b)
Study area in Zhengjiaping slope
Beijing
ChengduStudy area
(a)
The S
outh
Chi
na S
ea
0 3000m
Figure 1: Site location of the Dagangshan Hydropower Station: (a) location of the Dagangshan reservoir and (b) the regional topographicmap of the study area (from Google Earth, 2018).
Figure 2: Geological conditions and topographic characteristics of the Zhengjiaping slope: (a) geological map of the Zhengjiaping slope and(b) three-dimensional visualization of the study area.
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5×105m3 and the volume of Zone II is about 1.5×106m3.According to the geological background of the Zhengjiapingslope, the soil surface process and lithology of the obviousdeformation zone are analyzed by field investigation andbasic mechanical test. +e deep lateral deformation
monitoring operation was carried out using three boreholeinclinometers (IN01-IN03). +e Zhengjiaping slope pointdeformation monitoring operation was conducted usingGNSS (Global Navigation Satellite System), including acontinuously operating satellite positioning reference station
ZK01
ZK02
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ZK07
ZK06ZK05
ZK04 PD01
Zhengjiaping slope
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Zone I
Zone IITP03
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Y3D coordinate system
Excavated surface
Excavated materialPressing slope toe
(b)
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(b)Section position (Figure 4)
Figure 3: Overall view of the Zhengjiaping slope: (a) layout of exploratory adit, site boreholes, borehole inclinometers, and GNSSmonitoring points and (b) postexcavation morphology and support measures. PD represents exploratory adit; ZK represents site boreholes;IN represents borehole inclinometers; and TP represents GNSS monitoring points.
Sandstone and shale, freshSandstone and shale, WTSandstone and shale, STSandstone and shale, DR
GraniteAccumulated depositsFaultsGNSS monitoring point
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Figure 4: Geological profile of the selected location of the Zhengjiaping slope. NWL represents normal water level; OWL represents originalwater level; DR represents disintegration and relaxing deformation zone; ST represents strong toppling deformation zone; and WTrepresents weak toppling deformation zone.
4 Advances in Civil Engineering
and several deformation monitoring points. For betteranalysis of the monitoring data, a three-dimensional coor-dinate system was used, as shown in Figure 4.
4. Results
4.1. Earth Surface Processes. For the anaclinal slope, the softplastic features of the rock masses and the thin stratifiedstructure in the Baiguowan Formation favor the develop-ment of toppling deformation under long-term maximumprincipal stresses parallel to the slope surface [41, 42].Different processes of flexural toppling deformation ofbedrock occur on the Zhengjiaping slope, which can beroughly divided into four categories: (1) the disintegrationand relaxing deformation zone; (2) the strong topplingdeformation zone; (3) the weak toppling deformation zone;and (4) the normal rock stratum zone (Table 2).
Disintegration and the relaxing deformation zone aremainly distributed in the shallow part of the Zhengjiapingslope at a depth of 6.6–46.25m. As shown in Figure 7, rockstratum has a dip angle 0°–20°, partly gently slope out. +edeformation is characterized by strong tensile fracture. +e
fragmented relaxed rock mass has evidently internal hollowparts, which are filled with large pieces of block brokenstones and breccia rock cuttings.
+e distribution depths of the strong toppling defor-mation zone range from 6.6–46.25m. As shown inFigure 8(a), the stratified rock mass is characterized bystrong tensile deformation between the bedding planes, andthe extension-shear fracture surfaces of the cutting beds arecommonly developed. +e deformation behavior of therocks in the strong toppling deformation zone is complexand can be summarized into three basic failure modes:intercalated shear sliding, discontinuous tensile fracture, andcut-bed tensile sliding (Figure 9). Intercalated shear sliding isa common phenomenon in schistosity planes and weak rockbelts. Stratified rock masses with large dip angles have atendency to dip out of the slope under bending momentsfrom ground stresses, similar to cantilever beams. +eflexural toppling deformations have a process of gradualdevelopment from the shallow part to the deep part, andthe higher elevation causes the more intense deformation.In the local stratigraphy, tensile deformation occurs be-tween the bedding planes under the high flexural toppling
N
E
S
W
Bedding jointN15°W/SW∠80°
Bedding plane
SN/W
∠80°
Slope
SN/E∠
33°
Dominant joint set1N80°W/NE∠68°
Dominant joint set2SN/E∠50°-60°
Figure 5: Stereonet with projections of the slope surface, bedding plane, bedding joint, and dominant joint sets.
Table 1: Statistical results of lithologic composition in different site boreholes on the Zhengjiaping slope.
deformation. As flexural toppling deformation develops, thelevel of toppling of the stratified rock mass is increasinglyenhanced and the tensile stresses applied to the stratifiedrock mass are increasingly expanded. If the increased tensilestress reaches or exceeds the tensile strength, tensile frac-tures occur in the stratified rock mass accompanied byintercalated shear dislocations, resulting in discontinuoustensile fractures. When the development of toppling de-formation is sufficient, the inclination of the deformedsection changes considerably, the ground stress bendingmoment increases greatly, and the shear effect is greatlyamplified. Under the joint action of shear and tension,cutting-bed tension sliding occurred on the deformedsection.
Wedged cracks can be observed where there is evidenttoppling deformation, including the strong toppling deformation
Figure 7: Photograph of the toppling deformation characteristicsin the disintegration and relaxation of the deformation zone.
6 Advances in Civil Engineering
zone and the weak toppling deformation zone. As shown in
Figures 8(b) and 10, the existence of intercalated shearsliding and discontinuous tensile rupture rebuild themorphology of the original intact bedrock and form wedged
cracks. +e weak toppling deformation zone is majorly
distributed in the deep part of the Zhengjiaping slope, with adepth more than 38.4m. +is zone is characterized by theweak toppled level and slightly intercalated shear slidingwith a dip direction of 40°–60°. Because of the weak ex-tension between bedding planes and the rare development ofextension-shear fracture surfaces cutting the rock stratum,the stratified rock mass has a few tensile ruptures in the weaktoppling deformation zone.
4.2. Deep Deformation. As shown in Figure 11, the dataobtained by borehole inclinometers show lateral displace-ments of monitoring points for approximately half a year. Asshown in Figure 4, the borehole inclinometers IN01 andIN03 were installed in Zone II, and IN02 was installed inZone I.+e evident deformation zone has a sliding surface ofdevelopment with a depth of approximately 50m on IN02and several shearing dislocation zones of development onboth borehole inclinometers. +ere are differences in thetiming, number, and development of shear deformation
Tension deformationbetween bedding planes
Slope outside
Cutting-bed shear sliding
(a)
Slope outside
Wedged cracks
Intercalated shear sliding
Cutting-bed tension-shear rupture
(b)
Figure 8: Photographs of the toppling deformation characteristics in the strong toppling deformation zone: (a) view of the cutting-bedshearing sliding and tension deformation between bedding planes and (b) view of intercalated shearing sliding.
Maximum principal stress
Slope Rock formationN
S
EWσ1σ1
σt
σr
σt
σt
σr
σt
σt
σr
σrσr [σb]
σt
σr
α
>
α [τ]>
Figure 9: Schematic diagram of evolution process of the toppling deformation in the Zhengjiaping slope.
Slope outside
Wedged cracks
Figure 10: Photograph of the toppling deformation characteristicsin the weak toppling deformation zone.
Advances in Civil Engineering 7
zones at the three borehole locations. +e records of theborehole inclinometers indicate that the rock mass of Zone Iactually participates in the sliding deformation. However, ascan be seen in Table 3, the rock mass below 80m depth isidentified as a weak toppling deformation zone or a normalrock stratum zone, which makes it difficult to produce asliding surface zone. +erefore, it is certain that the dis-placement of Zone I is characterized by a combination ofsliding and toppling deformation processes that need to befocused on.
4.3. Slope Deformation. As shown in Figure 12, the moni-toring data obtained by the GNSS have a record of accu-mulative displacements of monitoring points forapproximately one and a half years. +e preconstructiongeological survey overlooked the potential of reservoirlandslides in the Zhengjiaping slope. When the monitoringdisplacement began on 21 April 2016, it was approximatelyone year from the beginning of impoundment, and creep/sliding deformations had already been occurring in theZhengjiaping slope. Due to the late recording of the initial
Displacement (mm)
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16/07/0616/07/1316/07/2116/07/2816/08/0416/08/14
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16/11/1516/11/2416/11/3016/12/1517/01/17
ZK02
(a)
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1060
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1150–80 –60 –40 –20 0 20 40 60 80 100
16/08/1416/08/1716/08/2116/08/3016/09/1316/09/19
16/10/2316/11/0316/11/1516/11/2316/11/3016/12/15
16/12/2116/12/2817/01/0317/01/09
Shearing dislocationproduced between21August and 13September 2016
ZK07
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Development ofslidingzone
(b)Displacement (mm)
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1265–45 –30 –15 0 15 30 45 60
16/07/1016/07/1516/07/2016/07/2816/08/1216/08/24
16/08/2816/09/0616/09/1116/09/1716/10/1616/11/22
16/11/2916/12/1417/01/1717/02/17
ZK05
Shearing dislocationproduced between 28
July and 12 August2016
(c)
Figure 11: Time evolution of the lateral displacements for different monitoring points of the borehole inclinometer: (a) IN01; (b) IN02; and(c) IN03.
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Table 3: Toppling deformation characteristics of rock masses with different depths on the bank slope.
Standard of classification Disintegration and relaxingdeformation zone
Figure 12: Time evolution of accumulative displacements in different directions for different monitoring points of GNSS in Zone I: (a)TP01; (b) TP02; and (c) TP03.
Advances in Civil Engineering 9
process of large deformation by the monitoring project, it isdifficult to obtain a correlation between deformation and thecontributing factors. At the same time, the Zhengjiapingslope was reinforced as it posed a great threat to traffic andresidents’ lives. Reinforcement was carried out from mid-May to late August 2016, mainly targeting the excavated areain Zone I. Although the reinforcement had a restrainingeffect on the deformation of the Zhengjiaping slope, acontinuous increase in cumulative displacement was stillobserved through GNSS.
Firstly, the temporal evolution of displacement andrainfall are compared. +is is an oversight of the monitoringprogram that no rainfall measuring device is arranged in therange within 5 km of the targeted slope. +ere are two
meteorological stations near the Dagangshan HydropowerStation. +e Luding Meteorological Station has a distance ofapproximately 72 km from the upstream of the dam site andthe Shimian Meteorological Station has a distance of ap-proximately 40 km from the downstream of the dam site. Asshown in Figure 13, the rainfall is mainly focused on a periodfrom June to September, which accounts for 70–80% of theyear’s precipitation. It can be used as a reference for therainfall characters for this case. +e two mutations of dis-placement growths both happened in the flood season, thatis, from June to September.
+en, the temporal evolutions of displacement and waterlevel are compared.+is two-year record can be superficiallydivided into two phases. +e first phase is approximatelyfrom the beginning of deformation monitoring to 31 Oc-tober 2016, which was characterized by the graduallyweakened growth of displacement. +e drawdown of thereservoir level was presented in the early monitoring period,which presented the decrease in the deformation velocity,and the accumulative displacements still increased. In lateAugust 2016, the reservoir level began to rise gradually, butthe deformation velocities maintained a reducing trend.After that, the deformation velocities tended to be stable andkept a small value, which had little correlation to the changesof the reservoir level. After entering the second phase, thegrowth rate of displacements tended to be stable; only in twomoments, there was an obvious mutation. +ere was a riseof water level in both displacement mutations. However,when the water level raised at other time, the growth rateof displacement had not been affected. However, the increaseof accumulative displacements shows deceleration imme-diately because of the following drawdown of the reservoirlevel. As shown in Figure 12, the occurrence time of theincreases in the two small-scale velocities is presented in theflood season with the frequent appearance of strong rainfalland increasing of water level. In conclusion, by using amonitoring analysis, impoundment and strong rainfall are
0
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Figure 13: Precipitation records from two meteorological stations near the Dagangshan Hydropower Station (the data are mean annualvalues).
Granite Sandstone
Argillaceous siltsto
ne
Anaclinal st
ructure
Topples
Tensiledefo
rmatio
nSliding surface
Reservoir
Risin
g
InfiltrationRock softening
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Fault
Tensilefra
ctures
Excavation
Topples/tension + slid
ing
Figure 14: Mechanism of deformation development in theZhengjiaping slope.
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considered to be the major disaster-inducing factors forsliding deformation on the Zhengjiaping slope.
5. Discussion and Conclusions
Taking the Zhengjiaping slope as a research example, thispaper analyzed the influence of geological conditions andwater level on the anaclinal rock slope through field in-vestigation and monitoring analysis. +e study area of theZhengjiaping slope is characterized by a fragmentized rockmass and a small amount of slope deposits. According to thedifference in deformation characteristics, the study area canbe divided into Zone I and Zone II. Since the impoundment,the deformation characteristics of the Zhengjiaping slope aretoppling deformation, sliding deformation, and partialshallow collapse. Based on the degree of deformation and theidentification of the sliding surface area, it was found that thesliding deformation only occurred in Zone I. +e accu-mulative displacements on TP01, TP02, and TP03 had been109mm, 427.1mm, and 388.8mm, respectively, by the endof 6 January 2018.
As shown in Figure 14, the sliding deformation on theZhengjiaping slope is an integration of many adverse factors.+e hydrological activities, lithology, tectonic activities, andartificial disturbances, etc., make great contributions to theformation of the sliding mass and the sliding surface zone,for which a major performance assists in generating frag-mentized rock mass in the shallow part. +e Zhengjiapingslope has geological settings that are prone to topplingdeformation under long-term maximum principal stressparallel to the slope surface. +e main contents of the li-thology in the sliding mass are sandstone and shale, whichhave low strength and lamellar structures with a largedensity of bedding surfaces, which aggravates the devel-opment of toppling deformation. Lithology is not the directreason for the observed deformation after impoundmentbut has a specific lithologic distribution that ignores thepotential for reservoir landslides in the early investigation.As shown in Figure 3(a), the region over the F1 Fault ischaracterized by argillaceous siltstone with intercalationsof sandstone and carbonaceous shale, and the region belowthe F1 Fault is characterized by granite. +e argillaceoussiltstone, sandstone, and carbonaceous shale are differenttypes of cementitious sedimentary rock. As shown in Table 4,the argillaceous siltstone and sandstone undergo a decreasein strength when they are saturated. When the water levelrises significantly, the large volume of rock is immersed in the
reservoir water, which in turn leads to a decrease in the shearcapacity of the slope and a faster increase in displacement.
+e effects of impoundment and strong rainfall directlycause the sliding deformation, which can be represented asboth the physical and chemical actions of water on frag-mentized rock mass. Monitoring analysis showed a corre-lation between the time series of displacement and reservoirwater level, but it is not always observed. +e phenomenonthat the value of cumulative displacement was suffering thechange of water level is only existed in the flood season. +eevidence of these appearances suggests that both rainfall andwater level changes are involved in the deformation. +einfiltration of strong rainfall is aimed at a shallow part ofsliding mass and sliding surface zone by a rear scarp. +einfluencing range of impoundment is referred to as the partof the sliding mass between the normal water level (thehighest level of water that a reservoir can store under normaloperating conditions) and the original water level (the levelof the reservoir before the impoundment).
Artificial disturbance has both good and bad effects onslope stability.+e good effects referred to the reinforcementon Zone I, which caused the cumulative displacements tendto be converged. +e bad effects referred to the slope ex-cavation in the reconstruction of the S211 road. First, theimpact loads, which have been produced by the excavationwork, cause the generation of new fractures and the ex-tension of existing fractures. +e development of fracturesleads to a decrease in the rock strength around the exca-vation face. Second, excavation leads to a change in thedistribution of stresses within the slope, which is detrimentalto slope stability.
Data Availability
+e data used to support the findings of this study are in-cluded within the article.
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper.
Acknowledgments
+is work was supported by the National Key R&D Programof China (2017YFC1501102), the National Natural ScienceFoundation of China (41977229), and the Sichuan Youth
Table 4: Summary of test results of mechanical property for the rockmass in the Zhengjiaping slope (the value is average level of test results).
Science and Technology Innovation Research Team Project(2020JDTD0006).
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