最新刊期
卷 42 ， 期 5 ， 2010
- 摘要：Abstract:A large number of dammed lakes induced by Wenchuan earthquake can be classified based on the formation mechanism and characteristics. With the formation mechanism of seismic landslide (collapse) disasters, dammed lakes were classified into two major categories as the overall-sliding type and the collapse-sliding type. Moreover, the collapse-sliding dammed lakes were divided into two subtypes as the fall-sliding type and the fall-ejection-sliding type according to the formation characteristics of landslides. The typical cases of various earthquake-induced dammed lakes were proposed in this study to analyze the formation methods, development characteristics and disposal measures, with a certain academic significance for raising the awareness of earthquake-induced dammed lakes and providing scientific guidance for long-term control of earthquake-induced dammed lakes.关键词：earthquake-induced dammed lake,Wenchuan earthquake, formation mechanism, classification
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发布时间：2023-11-14 - 摘要：Abstract:Mitigating debris-flow hazards is a great challenge in a period after Wenchuan Earthquake. Because of the complexity of debris supply and formation, the debris-flow discharge with respect to flood discharge was amplified in runoff, converging and moving stages of debris flows, and previous methods of calculating debris-flow peak discharge were not available for the debris-flow ravines in the earthquake affected region. The investigation of the formation of post-quake debris flows indicated that debris-flow hydrologic process is not linearly equivalent with flood hydrologic one, and debris-flow amplification coefficient is not linearly proportional to flood peak discharge. An empirical relationship of power function between the amplification coefficient and the flood peak discharge was built by analyzing the field data of seven debris-flow ravines in Subaohe, Weijiagou and Dubahe basins of the earthquake region. Combined the classical modified flood discharge method with the empirical formula, a nonlinear flood method was developed for calculating debris-flow peak discharge, which can be applicable to post-earthquake region.
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发布时间：2023-11-14 - 摘要：Abstract:Coplanar and stepped buried reverse faults were carried out to study the relationship between faults movement and surface rupture appearing in soil layer using geomechanical model test. Furthermore, the Gaoyuan Bridge damaged during Wenchuan Earthquake was taken as an example to study the effect of fault propagation on bridge foundation by changing the arrangement of the bridge to these two types of faults. Digital speckle correlation method and high speed camera were used to observe and analyze the process of the fault movement. We have studied the effect of fault dip angles and loading rates. The research results indicated that the failure process of discontinues reverse faults can be divided into four stages: elastic stage, fault coalescence stage, sliding stage and failure stage. The width of surface rupture zone, the uplifts of bedrock and sediment layer were statistics, which indicated the width of surface rupture zone and the uplift of the coplanar type were greater than the stepped one. The larger the fault dip angle, the wider the surface rupture zone was resulted. The uplift of bedrock was greater than the uplift of soil layer. The bridge perpendicular to the fault was damaged and no damage to the parallel one.
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发布时间：2023-11-14 - 摘要：Abstract:A lot of collapses and landslides induced by the Wenchuan Earthquake formed a lot of barrier dams. When these dams outburst, it tends to form dam-breaking debris flow. Since it has the characteristics of fast disaster-forming and large scale, the disaster loss caused by the dam-breaking debris flow is much more serious than that caused by the normal rainstorm debris flow. This paper took the barrier lake of the Tangfang gully in the Pingtong town, Pingwu County, Sichuan province as an example the characteristics and countermeasures of dam-breaking debris flow. It analyzed the forming process, flow discharge calculation and countermeasures of dam-breaking debris flow after earthquake by means of field investigation, field measurement and sampling analysis. The dam-breaking debris flow discharge were calculated by by means of morphology investigation method and flood method. The calculating results showed that the flow discharge result calculated by the flood method was obviously smaller than the one calculated by morphology investigation method. The main reasons are that there was serious blockage in the gully, a lot of loose solid materials induced by the earthquake, as well as the decrease of critical rainfall conditions of inducing debris flow. As a result, debris flow scale increased after the earthquake. The status of debris flow prevention in Tangfang gully had a lot of problems, such as poor conveyance capacity, broken basement and no excess-height in bend of the drainage canal, no preventing projects in the watershed. Since there were enough loose solid substances in the Tangfang gully recently. Under the condition of rainfall, debris flows will occur again. It will threaten 1600 people’s life and property safety in the Pingtong town and the reconstruction work after the earthquake. According to these problems, the countermeasures of building check dam, heightening drainage canal, warning and forecasting are put forward in this paper.关键词：Wenchuan earthquake;Pingwu County;Tangfang Gully;Dam-breaking Debris Flow;countermeasures
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发布时间：2023-11-14 - 摘要：Abstract:The debris flow hazards following the Wenchuan earthquake were characterized by high frequency, large-scale and serious potential risks and debris flows have been the key restricting factor to restoration and reconstruction in Beichuan County. Developing degrees evaluation of debris flow is of great significance to the reconstruction. Taking Beichuan County as the study area and using ArcGIS technology and multi-factor superposition method, we evaluated the developing degrees of debris flows in Beichuan County following the Earthquake based on the field survey and remote sensing interpretation. Landslides density, formation lithology, seismic intensity, slope gradient, surface roughness and average annual precipitation were selected as evaluation factors and each of them was subdivided into five grades. Analytic Hierarchy Process (AHP) was used to determine the weights of factors and quantify each grade. On that basis, we constructed multi-factor weighted superposition evaluation model and evaluated the developing degrees of debris flow in the study area. According to the evaluation results, the study area was divided into three areas: high growth area, medium growth area and low growth area. The high growth area concentrated on the hanging wall of Beichuan-Yingxiu Fault and distributed along Leigu -Qushan -Chenjiaba townships, accounting for 6.6% of the study area; the medium growth area located on both sides of the high growth area and mainly on the hanging wall of Beichuan-Yingxiu Fault, accounting for 22.5% of the study area; the rest belonged to low growth area, accounting for 70.9% of the study area. We suggested that human activities should avoid debris flows in the high growth area and debris flow disaster evaluation should be conducted in the medium growth area to ensure no disaster threat, or must avoid debris flow, too.关键词：debris flow;restoration and reconstruction;multi-factor superposition method;developing degrees evaluation;Beichuan County
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发布时间：2023-11-14 - 摘要：Abstract:The selection of the immigrant location for Wenchuan people after the earthquake was carried out using RS and GIS. According to the particularity of this great earthquake, considering sustainable development and capability of responding to future disasters of the seismic disastrous area, eight factors including geological hazards, fault structure, vegetation cover, settlements, roads, water system, gradient, and elevation were considered as for the assessment. Information extraction of these factors and thematic map were carried out by Remote sensing image and digital topographic map, and finally the locating modeling for the research area was developed. The results suggested that the respective ratios of high-suitability area, medium-suitability area, Low-suitability area and non-suitability area are 0.64%, 24.94%, 69.94% and 4.48%, and the distribution of their Location is clear revealed in the figure 11, which could be used as a good reference for decision makers.关键词：earthquakes;location;Remote Sensing(RS);Geographic Information System(GIS)
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发布时间：2023-11-14 - 摘要：Abstract:Abstract：For revealing the relationship between distribution of landslides and environmental factors, 4722 earthquake-induced landslides had been obtained with field investigation and interpretation of remote-sensing images, and used GIS techniques to finish the statistical data including distance from middle faults, lithology, altitute, river, slope and aspect of slope. The main results of the paper about responsive mechanism between the distrution of landslides and factors can be summarized as follows. (1) The zonal distribution of landslides was consistent with strike of middle faults and the seismic energy was released along the middle faults which caused the attenuation of energy obvious in minor axis and about 64.42% of landslides were distributed within 20 km from middle faults. The density in hangingwall of middle faults was obviously higher than that in footwall which underwent the variation of reduce-increase-reduce because of the break of middle and front thrusting faults. (2) The release of seismic energy was restricted by landform and river. The high density of landslides was in high altitude, steep slope, intense incision. The concentrated distribution of landslides was in river banks and the origin of landslides was in upside of slope because of the magnified effect for earthquake. (3) About 99.43% of landslides were distributed in area where the seismic intensity was more than Ⅶ and the highest density of landslides were in soft rocks because of the earthquake site coefficients. (4) The high density occurred in the intersection direction of the gradient topography and the faults breaking and landslides with large scale appeared in the union direction, which was convenient for seismic energy transmitting.
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发布时间：2023-11-14 - 摘要：Abstract:To study the seismic design of subgrade engineering, subgrade seismic damage of Wenchuan 8.0 Earthquake was investigated. Two damage types of un-reinforced road embankment under earthquake were found, including slope collapsing and pavement cracking, while there was nearly no damage to road embankment whose upper part was reinforced by geogrid. Body sliding was restrained by reinforcement on the top of the embankment with long geogrid, which prevented the fissures from developing downward, and slope collapsing was precluded by reinforcement on the upper part of the embankment with short geogrid, which restrained the lateral deformation of soil mass. According to conventional design of geogrid-reinforced road embankment, optimized seismic design was proposed. Dynamic-strength-reduction method was employed to compare the seismic performance of conventional design with that of optimized seismic design of geogrid-reinforced road embankment. The result showed that geogrid used would decreased by 23.1%, maximal seismic displacement of embankment would decreased by 19.0%, and maximal stress of geogrid would decreased by 14.1% after optimized design. Optimized design not only decreased consumption of geogrid, but also restrained the lateral deformation of soil mass, thus the seismic behaviour of road embankment improved. This study will provide scientific evidences for reconstruction of road embankment engineering in seismic disaster area.关键词：subgrade engineering;seismic design;finite difference method;geogrid-reinforced embankment;earthquake
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发布时间：2023-11-14 - 摘要：Abstract:The remote sensing image and the survey results after the earthquake showed that，the Wenchuan Ms8.0 Earthquake had induced more than 5528 collapses and landslides in the Wenchuan County with the area of about 4083 km2. Based on GIS, the statistical relationships of the collapses and landslides distribution and the factors，such as lithology，the distance to faults，slope gradient，elevation and others，was analyzed. Susceptibility of triggering factors of Wenchuan Earthquake was analyzed by the means of slope certainty factors (CF). The most numerical intervals of each factor which are inclined to hazards were determined. The results showed that the hazards mainly distributed in the stratum of Proterozoic，Sinian and Permian with hard rock；in the slope of more than 40 degree；within a 10 km buffer zone to the active faults and fixed within 6 km to the no active faults；the collapses and landslides distributed mainly in the area of the elevation 1000～2500 m；mainly range in relative height between 600～1000m；the mainstream of the Min River absolutely controlled the hazard distribution. The conclusions indicated that the factors had effect of seismic wave propagation in media and distance effect；there was significant different numerical interval which inclined to collapses and landslides in lithology and slope between induced by earthquake and by rainfall. This research can provide a good referential and scientific basis for steady susceptibility analysis of earthquake-induced collapses and landslides in other regions.关键词：Wenchuan earthquake;collapse and landslide;susceptibility analysis;certainty factor (CF)
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发布时间：2023-11-14 - 摘要：Abstract:According to 5.12 Wenchuan earthquake peak acceleration attenuation relations, EW, NS, UD direction of the decided dam bedrock ground peak acceleration are 510 gal, 450 gal, 420 gal, and then measured acceleration records(051MXT) are conversion to the input acceleration time history of Zipingpu Dam by using the ratio method.Based on rockfill E-B model parameters inversion by the construction phase deformation monitoring data, the initial parameters of dynamic models with vibration hardening characteristics are gained by Jilintai,Houziyan and other projects laboratory test data; combined with Guanmenshan, Chahanwusu-situ testing data and the dam measured spectral characteristics of the earthquake acceleration, they are adjusted; by calculating effective vibration times to the input earthquake acceleration and using the measured data, the rockfill permanent deformation parameters are decided by the inversion analysis; it is concluded that：vibration hardening dynamic model reflects the rockfill material 'shock shrinkage' phenomenon during an earthquake. The main reason of the larger Zipingpu dam permanent deformation during 5.12 Wenchuan earthquake are that both the longer main shock time and the near earthquake, Shear failure of concrete slab betweenⅡand Ⅲ stage is secondary damage caused by rockfill permanent deformation. Existing dynamic analysis theories and methods of embankment dam can basically reflect earth-rock dam seismic characteristics.关键词：5.12 Wenchuan earthquake , Zipingpu CFRD,permanent deformation,dam-slope stable , back-analysis
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发布时间：2023-11-14 - 摘要：Abstract:In this study, Wenchuan Wolong seismic wave, etc. were selected, and the shake table test on ‘tie column + ring beam + cast-in-place slab’ recycled aggregate concrete (RAC) masonry structure was conducted. Not only the dynamic characteristics of structure, but also the damping ratio, frequency changes and the top floor displacement of the model under intensity 8 of frequently occurred, basic and seldom occurred earthquake were tested. On the basis of test results, the model’s maximum drift angle under three occurrences was respectively less than the allowable value of earthquake resistant structure suggested by the Code for Seismic Design of Buildings. Tiny cracks were found on the wall, however it showed RAC masonry structure constrained by ‘tie column + ring beam’ system exhibited good seismic behavior and can resist the earthquake action under each level of fortification intensity in the location. It is concluded that RAC masonry structures can be promoted in the earthquake hit-area reconstruction.关键词：recycled concrete block masonry house;tie column + ring beam + cast-in-place slab;shaking table test;seismic behavior
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发布时间：2023-11-14 - 摘要：Abstract: The slopes in western mountains are used to be developed into the infrastructure construction for the scarcity of land resources. However, it usually lead to collapse and causes great damage for improper cut slope. Here based on the upper bound theorem of limit analysis, the stability of cutting slope with different shear index under different cutting way was studied. Then according to the pre-reinforced technology for cutting slope, the design of pre-reinforced pile to stabilize high cutting slope is studied while the design load is also proposed. Finally, the minimum yield acceleration which can result into the permanent displacement and the permanent displacement of advanced support system under earthquake is researched. In short, the whole studies provide a scientific method for pre-reinforced technology of high cutting slope.关键词：high cutting slope;Upper Bound Method;Pre-piled;seismic yield acceleration;permanent displacement
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发布时间：2023-11-14 - 摘要：Abstract:The optimum range of parameters of lead rubber bearing (LRB) for large scale base-isolated tank on different sites is a crucial problem in the research of isolated tank. The Bouc-Wen model was adopted to simulate the non-linear hysteretic characteristics of force-displacement relationship for LRB.The nonlinear equations of motion of isolated tank was solved by the Newmark’s step-by-step method and Runge-kutta method. The seismic response of the large scale based-isolated storage tank with LRB was investigated And the influence of LRB parameters on the response of large scale base-isolated tank on different sites was analyzed. The result indicated that the isolation frequency is the primary parameter that affects the seismic response of the isolated tank. The optimal ranges of isolation frequency of large scale base-isolated tank for site I, site II, site III , and site IV are 0.5~5 rad/s, 2~5 rad/s, 2~5 rad/s and 1.5~3 rad/s respectively. The influence of the yield strength on the seismic response of tank depends on the site type and isolation frequency. There are optimum yield strength that make the base shear attain the minimum value on site II and site III. Further, the optimum yield strength increases as the isolation frequency increases.关键词：isolated tank;lead rubber bearing;Bouc-Wen model;seismic response
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发布时间：2023-11-14 - 摘要：Abstract: Seismic assessment and strengthening of existing old, under-designed buildings for seismic forces is a subject that has received a lot of attention from civil engineers and researchers in many areas of high seismicity around the world. Existing buildings with various strengthening systems have quite different seismic performances from one to another. A summary of the damage and retrofitting of an unreinforced masonry structure in Hanwang town which suffered slight damage during Wenchuan Earthquake was presented, and the role of the strengthening system was evaluated. A seismic retrofitting building which had excellent performance during 1985 Mexico Earthquake was also assessed. Numerical simulation on seismic retrofitting performance of one building located in Dujiangyan was conducted based on ANSYS. Comparison of analysis results and the two case buildings shows that: seismic assessment of existing building is crucial to choose the retrofitting system; global seismic performance of one building should be optimized after being retrofitted and not but simple repair; less increase of the weight of one retrofitted building is an important factor in success of retrofit solution; some retrofitting solutions may lead to higher increase in weight which would lead to reduce the efficiency of the stiffening, and lead to higher seismic roads; and large earthquake force may be developed due to retrofitting systems.关键词：Strengthening;seismic performance assessment;Wenchuan earthquake;Mexico Earthquake;nonlinear analysis
- 2669
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发布时间：2023-11-14 - 摘要：Abstract:In this paper the schemes for urban emergency water supply are evaluated and sorted with Gray Target to establish index system of water quantity, water quality, engineering difficulty and investment etc. its steps includes: establishing standard mode, gray target transformation, building gray associated with difference information space, calculating gray relational coefficient and approaching coefficient, at last identifying the extent near Grey Bull’s-eye. The model is simple, efficient and feasible. This method is suitable to deal with the uncertainty in less data, incomplete information.关键词：grey target theory;emergency water supply;Multi-0bject
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发布时间：2023-11-14 - 摘要：Abstract:There are many portable shelter which mainly contained foam Polystyrene(PS) need be recycled after earthquake. Recycled polystyrene (rPS) is not degradable which will cause serious environment pollution, so the large amount of disposable polystyrene plastic wastes produced after earthquake makes imperative the search for recycling them. In this work, rPS was toughened with ethylene-octylene copolymer thermoplastic elastomer (POE) and high-density polyethylene (HDPE), compatibilized by styrene-butadiene-styrene copolymer (SBS) in order to enhance the toughness of rPS. The prepared blend showed an impact strength of 12.6 kJ/m2 and a tensile strength of 25.2 MPa, which can be well used to substitute HIPS since this system is economical and environmental friendly. The properties of composite for UV ageing resistance and thermal and oxygenic ageing resistance were both improved after the addition of complex ageing resistance agent, which will prolong the using time of the composite parts.关键词：Polystyrene, recycle, toughen, ageing
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发布时间：2023-11-14 - 摘要：Abstract:From the point of materials stability, the practical application possibility of recycled aggregate concrete used in reinforced concrete shear wall is investigated, as one of effective methods to use recycled aggregate. The research focuses on the drying-shrinking crack of reinforced recycled concrete shear wall under constraint conditions. Drying-shrinking strains and cracks of reinforced concrete shear wall and common reinforced concrete shear wall were measured with surface bonded strain gauge and internal buried gauge under constraint conditions, respectively. The results reveal that internal shrinkage strain is obviously less than surface shrinkage strain, and there is a little difference of internal strains between reinforced recycled concrete shear wall and common reinforced concrete shear wall. However, shrinkage strain of common reinforced concrete shear wall is higher than reinforced recycled concrete shear wall, while, micro cracks of recycled concrete is obviously higher than common concrete.
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发布时间：2023-11-14 - 摘要：Abstract:By means of a series of large-scale shaking model tests, the mechanism of side slope’s superficial dynamic effect under earthquake disturbance and its anchoring prevention were experimentally studied to the typical pattern of small collapse-slide and shallow soil damage along Dujiangyan to Yingxiu section of national highway No.213 in Wenchuan earthquake region. Using a 2.1 m height single-side model slope built by sand blended with clay and excited by three typical earthquake waves of 0.253g and 0.471g accelerations separately, the different quantitative dynamic response characteristics between the superficial and deep position of slope body were analyzed comparatively. These response analysis included magnification factors of acceleration, dynamic strain value and predominant frequency corresponding with three height prototype single-side slopes of 2.1 m, 10.7 m and 21.5 m. The result showed that the accelerate response of slope body’s surface was approximately 1.4 times of the deep position averagely, and predominant frequency of vibration was increased around 45 percent accordingly. In particularly, it presented significant dynamic shear strain of superficial stratum and dynamic tension-compression strain between the superficial and deep position, which reached 6.5×10^-3and 2.2×10^-3respectively and averages about soil’s failure limit strain. Due to the stress superposition of the stripping action conducted by tension-compression strain of incompatible response movement between superficial and deep position and the kneading action deduced by shear strain, slope’s superficial failure or damage were occurred. Furthermore, with comparative shaking table model tests between anchored slope and natural slope, the mechanism of superficial failure prevention effect of anchoring structures was preliminary studied. It was found that, anchoring structures could remarkably reduce superficial accelerate response by about 15 to 35 percent and increase natural frequency by 39 percent compared with the original natural slope at slope top in experiments. Anchoring prevention mechanism included as follows: firstly, earthquake resonant interaction was reduced due to higher natural frequency of anchored slope; secondly, the incompatible movement was diminished by anchoring structures which joined the slope’s superficial and deep position into a whole; thirdly, stripping action induced by stress wave reflection on slope’s surface was counteracted by the anchoring force. These results can provide references for road reconstruction and hazards prevention after earthquake.关键词：slope stability;earthquake effects;dynamic response of slope surface;anchorage
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- 11
发布时间：2023-11-14 - 摘要：Abstract:The incipient motion of sediment is very important in exploring the mechanism of scouring induced by the dam break. The Shields diagram remains the most widely used criterion for incipient motion of sediment. However the engineer is faced with problems when predicting inception of sediment transport, mainly because the shear velocity cannot be directly determined, and this implicit nature makes applications rather inconvenient. This study aims at developing an empirical formulation of the Shields diagram for incipient motion of sediment, the formula shows that it is approximately equal to Eq.(5) and Eq.(6) for very large and small Re*c, respectively. Comparison between present model with other formulas and experimental data shows that the authors’ formula fits experimental data best and the formula structure also can be acceptable. Finally, the model was applied in the scouring prevention of Tandjiashan barrier lake downstream Channel.关键词：汶川大地震;起动拖拽力;希尔兹曲线;摩阻流速
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发布时间：2023-11-14 - 摘要：Abstract:As Wenchuan earthquake was of high magnitude and shallow seismic focus，it caused considerable damage and thousands of geo-hazards. Numerous geo-hazards broke out simultaneously and rock fall, rock avalanches, landslides, dammed lake and debris flows responded the earthquake violently. Most geo-hazards will produce large amounts of sediment into the river, such as the sediment due to the strong main shock and aftershock, the sediment generated by the excavation of landslide dam spillway and the debris flow caused by rainfall and flash flood, etc. Find out the sediment transport rules is important for the post-disaster reconstruction, debris flow disaster monitoring and warning, river regulation and flood control and resource utilization. According to the characteristics of the slope sediment incipient motion and it’s relevant research foundation, with the consideration of relative exposure degree, relative roughness, shape coefficients, sediment restart incipient motion of rock avalanche bodies and landslide bodies was studied, and we deduced sediment incipient motion conditions of rock avalanche bodies and landslide bodies after earthquake.关键词：earthquake;geo-hazards;rock avalanche bodies;landslide bodies;incipient motion condition
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发布时间：2023-11-14 - 摘要：Abstract:Because of broken structure caused in earthquake, the dangerous rocks collapse frequently under the action of special external force after the event, which restricts the reconstruction greatly. Here from the real structure of rock, based on the analysis of destructive external force, and according to the fracture mechanics, the failure mechanism of dangerous rocks is studied clearly by modeling reasonably. Then the condition of different kind’s collapses is given and proposed to diagnose dangerous rock. At last, an example is given to prove the theory. The result shows the aftershock, rainfall and their coupling action are the main forces that cause the collapse after the event, and there is a critical minimum depth of crack under any action which can lead the failure. Meanwhile it is also found that the critical depth is smaller under couplings action.关键词：dangerous rock after the event;crack propagation;stress intensity factor;critical acceleration;critical depth
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发布时间：2023-11-14 - 摘要：Abstract:Abstract: Seven dam break experiments were designed, with different inner slopes and gradation of grain building dam, to study effect of the conditions above on the process of dam break. According to photography of dam break, four stages were observed, and flow erosion of dam body was the most intense in stage Ⅲ. In stage Ⅰ, inner slope was eroded; In stage Ⅱ, the top of the breach was eroded; In stage Ⅲ, outer slope was eroded; In stage Ⅳ, the shape of the dam body kept steadily and water level of reservoir gradually came to the constant. Using the WYG-Ⅱwater level measurement system, the real-time water lever data of the reservoir can be obtained. The result of the experiments indicate that the steeper of the inner slope was, the more peak discharge of dam break was; if the non-uniformity coefficient was bigger, the peak discharge of dam break increase at first because of lee erosion, but decrease at last because of the conceal function. Empirical formula of peak discharge of dam break was established by single factor analysis.关键词：Blocked dam;dam break;Peak discharge;Lee erosion
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发布时间：2023-11-14 - 摘要：Abstract:In order to repair many structures damaged in Wenchuan earthquake, using carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) to repair the reinforced concrete (RC) beams was studied. The failure types, stiffness change, crack developing characteristics and shear resistance were investigated. Beam size, stirrup ratio, FRP type and arrangements of sheets along the shear span were analyzed during experimental study. The test result indicated that CFRP or GFRP can increase the shear resistance and deformability greatly, and the rigidity of strengthened beams also increases obviously. Compared to strengthening with CFRP, the GFRP strengthening method increase the deformability and the utilization ratio of strengthening material. The shear resistance increases with the beam height, but not fit for the deformability. Increasing stirrup ratio can delay the crack appearing obviously, improve the cracking load and ultimate strength of strengthened beam, but reduce the ultimate deflection greatly. Finally, according to the analysis of test data, the theoretical and practical formula for calculating the bearing capacity of RC beams strengthened with FRP sheets was established. The results showed that the theoretical calculation is in accord with the experimental data.关键词：concrete beam;Strengthening;shear capacity;experimental study;CFRP;GFRP
- 3230
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- 7
发布时间：2023-11-14 - 摘要：Abstract:In order to provide experimental basis for the reconstruction of river bend after the earthquake, a series of clear-water scour with the same initial bed material were done in a U-shape bend. The variations of flow structure, sediment sorting coefficients and bed deformations were analyzed. The results showed that, there was large transverse velocity at the blunt position of the bend’s inlet, bed sediment sorting was remarkable for non-uniform bed sand, and bed deformations had a large difference in different domains which were favorable to further understand the interactions among flow structure, sediment movement and channel deformation in bends.关键词：earthquake;landslide;bend flow;bed material sorting;bed deformation
- 2571
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发布时间：2023-11-14 - 摘要：Abstract:A quantitative analysis of the increased flood hazard in the Wenchuan Earthquake-hit region was carried out. Flood routing was performed for the reach of Tongkou River from Tangjiashan Quake Dam to Beichuan City and the change of flood defense capacity of Beichuan City was examined. It was shown that since the river bed was seriously raised by the Tangjiashan Quake Lake drainage and subsequent Weijiagou Debris Flow, the present flood defense capacity near Beichuan City had become much lower than that before the earthquake (i.e., the capacity against a 20-year flood) and far away from the requirement of protecting a national commemoration earthquake site. Meanwhile, the predicted water level and erosion depth were sensitive to the manning roughness coefficient for flood routing. It would be desired in future to explore the manning roughness coefficient changing with river geomorphology and bed material composition.关键词：earthquake;Beichuan;recovery;flood control;subsequent disaster;disaster prevention
- 3170
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发布时间：2023-11-14 - 摘要：Abstract:The assessment method of post-earthquake reinforcement measures and calculation method of safety factor for general stability of underground caverns under earthquake effect were proposed. Firstly, the approach of simultaneous anti-shear and anti-tensile strength reduction was adopted to calculate the safety factor for general stability of underground caverns. The general stability of caverns could be easily quantitatively assessed. Afterwards, the wave filed method was employed to simulate the impacts of Wenchuan earthquake. The post-earthquake reinforcement measures taken at Yingxiuwan hydropower plant, which was located in the epicenter region, were assessed. The pre-earthquake and post-earthquake as well as pre-reinforcement and post-earthquake safety factors of underground caverns were summarized. The variation laws of safety factors indicated that the proposed methods were able to reflect earthquake influences and prove the necessity of reinforcement measures. Meanwhile, by comparing the safety factors under different calculation schemes, it was discover that the anti-seismic capacity of underground caverns could not be fully restored to the level before the earthquake. However, the reinforcement measures were able to meet the seismic fortification standard required by design codes. It was therefore concluded that the long-term stability of underground caverns can be guaranteed and the post-earthquake reinforcement measures were reliable as well. The proposed methods provided useful references to the post-earthquake restoration and reinforcement design of similar projects.关键词：earthquake effects, underground power plants, strength reduction, reinforcement design, functional assessment
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- 5
发布时间：2023-11-14 - 摘要：Abstract:The dynamic characteristic of space beam string structure was investigated in this paper. The modal analysis was firstly carried out with this structure and the corresponding upper single-layer shell without the lower cable-strut system. Then the time history analysis were performed to study the dynamic behavior of space beam string structures under earthquake action, including the effect of numbers of struts, sag-span ratios, stiffness of upper beams, prestress and area of cables. The results show that the lower cable-strut system does increase the stiffness of space beam string structures, and most vibration modes of the structure are vertical modes. The increase of numbers of struts, sag-span ratios and sections of upper beams are conducive to increase of structural stiffness and resisting global deformation. But the effect of prestress and area of lower cables on the seismic performance of space beam string structure is slightly.关键词：hybrid system;earthquake;seismic design;modal analysis;cables
- 4014
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- 0
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- 1
发布时间：2023-11-14 - 摘要：Abstract:In order to understand the initiation model and mechanism and forecast and prevent the debris flow after earthquake, designing the facilities of debris flow initiation according to the environment post-earthquake to study the debris flow initiation mechanism. In this study, the 25 groups test were carried out at different slopes using the same soil material to study the debris flow initiation of debris flow at varies slopes, the results show that: 1. The initiation model of debris flow is erosion → gully → collapse → block → failure and transformed into debris flow between 8°-12° as initiation due to dam-failure; 2. The initiation model of debris flow is increased erosion gradually (down cutting erosion, back word cutting and lateral erosion) with the bulk density increasing and transformed into debris flow between 13°-17° as initiation due to erosion; 3. The initiation model of debris flow is surface flow → infiltration → failure → fluidization and transformed into debris flow between 18°-25° as initiation due to slope failure; 4. The change character of water pore-pressure is different at different slope experiments; the water pore-pressure inner soil reveals the initiation mechanism of debris flow at different slope. The prevention programmer could reference for the results of initiation model at different at varies slopes and carry out the different plan; the change characters of water pore-pressure revealed the initiation process of debris flow could be used forecast debris flow initiation for post-earthquake reconstruction projects.
- 3445
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- 18
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- 18
发布时间：2023-11-14 - 摘要：Abstract: In order to enhance seismic performance of the frame structure and masonry structure with frame at bottom layer, combined shear wall consisting of frame and gridiron composite wall was proposed in this paper, and shear bearing capacity calculation method for the wall was researched. 1/2 scale frame-sparse gridiron composite walls were tested under reversed cyclic loading. Damage processes, load-bearing capacity and hysteretic curves characters of the walls were analyzed. Based on the experiments and reinforced concrete masonry walls data, the force features and shear resistance mechanism of the wall were analyzed, and general shear bearing capacity formula were put forward, and application methods under different conditions were gave at the same time. Comparative analysis between calculation results and test results indicated that the formula was accuracy enough, and can be referred in frame structure or masonry structure with frame at bottom layer.
- 2090
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- 2
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- 2
发布时间：2023-11-14 - 摘要：Abstract:Volume and topography are two important factors affecting runout distance of landslides. On the basis of detailed field investigation of the landslides triggered by “5.12 ” Wenchuan earthquake, the relationships between runout distance and landslide volume and initial slope angle for 46 typical earthquake-induced landslides were analyzed. The results show that there are good exponential relationships between the logarithmic values of displaced volume and horizontal and vertical distances for the landslides, and the R2 values are 0.8244 and 0.7859 respectively. Moreover, there is an good linear relationship between the equivalent friction coefficient and tangent values of initial slope angle for the landslides, and the R2 values is 0.7973. In addition, a relation of horizontal(Lr) and vertical distance(H), landslide volume(V) and initial slope angle(θ) for the landslides, was obtained by binary linear regression, with the equation of logLr=-0.0785logV+1.2347log(H/tanθ).关键词：“5.12” Wenchuan earthquake;earthquake-induced landslides;runout distance estimation;landslide volume;Topography
- 2619
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- 0
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- 22
发布时间：2023-11-14 - 摘要：Abstract: To establish relation between oblique incidence wave and design seismic component, and structure wave field which can result in non uniform ground motion, in this paper, design seismic component is regarded as result of oblique plane SV wave and oblique plane P wave. According to theory of wave propagating in solid, both incidence angles and amplitudes of the oblique waves have deterministic relation. Based on viscous-spring artificial boundary condition, the time-domain calculating method for dynamic interaction between soil and structure object to obliquely incident seismic waves is developed. Half space example with simple ground motion and Koyna seismic horizontal history proves that the method advised in this paper has good precision and can produce similar seismic response to the design seismic component. With general FEM software, the advised method can easily applied to the dynamic analysis of long span structure with non uniform ground motion.关键词：oblique incident wave, wave field decomposition, FEM, non uniform ground motion, viscous-spring artificial boundary
- 2656
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- 18
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- 3
发布时间：2023-11-14 - 摘要：Abstract:In this paper, the pseudo excitation method was further improved and used for multi-dimensional random seismic analysis of a typical stadium canopy roof structure named Jinan Olympic Center. Theoretical formulations for multi-dimensional pseudo excitation algorithm were derived. A method of evaluating average peak responses was recommended. Seismic random models and parameters under multiple seismic ground motions were detailed introduced. The displacement responses of key nodes under single dimension and multiple dimensions were compared by calculating. The structure response under multi-dimension seismic input would be significantly magnified. The results of pseudo excitation method and the time history analysis were compared to verify the accuracy of multi-dimensional pseudo excitation method, and they were in good agreement. Multi-dimensional pseudo excitation method as an efficient random vibration analysis method provides an effective way to the field of random vibration analysis of large-scale stadium canopy roof structure.
- 2676
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- 2
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- 1
发布时间：2023-11-14 - 摘要：Abstract: In order to complete recycled use of vast post-disaster waste cement concrete(WCC), physical and mechanical performance, durability, structure and mechanism of recycled concrete(RC) and cement stabilized cement concrete scrap base material(CCBM) were studied. The results showed that air content of RC can reach 4.7%, with vb consistency beyond 10~15s and flextural, compressive strength higher than 6MPa、56MPa at 28d, anti-permeability rank of RC exceeds S40, with low chlorinion permeability. Structure of RC includes aggregate, new and old mortar, transition zones among aggregate, new, old mortar, transition zones between aggregate and new mortar, new and old mortarh had compact structure, interface between aggregate and new mortar had cracks, but performance of RC was improved by aggregate beforehand adsorbing water, mixing fly ash and agents. Non-side-restriction compressive strength of CCBM with 4%,5%,6%,7% cement can reach 3.01 MPa, 3.94MPa, 4.75 MPa, 4.98MPa at 7d, BDR of CCBM after 5 Freeze-thaw cycles was greater than 80%, which can meet strength and freeze resistance requirements of pavement base. Therefore, “RC+CCBM” complete recycled use technology can reuse vast post-disaster WCC completely.关键词：post-disaster reconstruction;waste cement concrete(WCC);recycled concrete(RC);cement stabilized cement concrete scraps base material(CCBM)
- 2798
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- 0
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- 0
发布时间：2023-11-14 - 摘要：Abstract:In order to study the effect of vertical seismic on the dynamic response of underground structures, the nonlinear seismic response analysis of a certain metro tunnel in soft sites was carried out. In the numerical analysis, a dynamic nonlinear viscoelastic model was used to model the characteristics of soils under cyclic loading, and the dynamic plastic damaged model of concrete was selected to model the characteristics of tunnel lining. The finite element model was established with dynamic viscoelastic artificial boundary, and the nonlinear seismic response analysis of the model was carried out with the bottom imposed horizontal or two-direction seismic wave. The result shows characteristics of seismic response of the metro tunnel, and that the vertical earthquake wave have a great influence on the relative displacement between tunnel top and tunnel bottom, stress of tunnel and the vertical acceleration at tunnel bottom. Therefore, the effect of vertical earthquake can not be ignored in engineering design.
- 2424
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- 0
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- 5
发布时间：2023-11-14 - 摘要：Abstract: The improvement and extension for critical slip fields of rock slope is performed, in view of the discontinuity of rock. By fully considering the influence of structural surface to the stability of the slope，a new method is proposed for dealing with structural planes, and tensile cracks are readily introduced based on the tensile strength of rock. The improved techniques for constructing critical slip fields of rock slope are incorporated into a computer program. By numerically simulation, the most dangerous sliding surfaces are traced according to the principle of maximum thrusts with satisfaction of both force and moment equilibria, resulting in critical slip surfaces quickly and exactly as well as the corresponding factors of safety. This method has been applied to the stability analysis of five example slopes and a case slope, and the results show its accuracy and high effectiveness in rock slope stability analysis in comparison to other methods.关键词：rock mechanics;slope stability;critical slip fields;limit equilibrium;structural surface
- 2634
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- 4
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- 1
发布时间：2023-11-14 - 摘要：Abstract:Since the permanent displacement induced by earthquake can be regarded as an effective criterion for stability estimation and anti-seismic design of slopes, a new method for evaluating the displacement and improve its estimating accuracy was proposed. The forward and reverse critical acceleration of potential landslide were derived based on the limit analysis upper bound theorem, and the influence of sliding surface angle and vertical acceleration on critical acceleration was then discussed. According to the principle of energy conservation, the energy response equations of landslide system were established, the process of energy transferring, transforming and dissipating during earthquake were analyzed. A permanent displacement calculation formula of the slope with energy method was presented. In addition, the contribution of gravitational potential energy to permanent displacement was analyzed. Result showed that the reverse displacement can not be neglected when the slope has a small angle of sliding surface and weak stability, while the earthquake is strong. The critical acceleration will become an acceleration time history varying with time when take the vertical acceleration into account. Farther precision in displacement calculation can be reached via considering the effect of reverse critical acceleration and vertical acceleration wholly. Earthquake plays an important role on triggering landslides, and the permanent displacement is mainly determined by gravitational potential energy.关键词：slope;permanent displacement;critical acceleration;energy method;earthquake
- 2821
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- 0
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- 5
发布时间：2023-11-14 - 摘要：Abstract:In order to research retrofitting measures of ancient building with gate tower, an investigation was carried out to Shangqing Temple, a stone-wood structure on the Qingcheng Mountain. Taking into account the nonlinear boundary, the mixed-scale finite element method was adopted to respectively set up the single gate tower numerical model and another considering the cooperation of base and memorial archway. Compared with the national code, the behavior of single gate tower numerical model was analyzed to prove the validity of the numerical model. The deformation, seismic base shear and internal force of its members were investigated by the transient dynamic analysis. The measures of reinforcing the base and stone memorial archway with bolts and anchoring the mortise-tenon joint of tower gate with claw nail were proposed. The results indicated that because the dynamical participated mass of gate tower is centralized, large seismic response will happen when the gate tower was excited. The action of base results in the marked whiplash effect, but the mass of tower gate is small and the amplitude of seismic internal force is much less than the one of displacement. The gate tower has a good ductility to improve its collapse resistant capacity, and retrofitting measures of ancient building should take into account the protection and inheritance of the mechanical behavior of mortise-tenon joint.关键词：ancient building;aseismatic analysis;numerical simulation;structure retrofitting;Wenchuan earthquake
- 2538
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- 0
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- 4
发布时间：2023-11-14 - 摘要：Abstract:Wenchuan earthquake in 2008 is affecting soil erosion, and the trend of sediment transport and fluvial processes of rivers in Sichuan, China. Rivers in the earthquake district are damaged seriously by Landslides, debris flows and barrier lakes. Intensive researches are conducted during the disaster relief, recovery and reconstruction after the Wenchuan earthquake disaster in two years. A selective literature review of mechanism and technology studies relative stream corridor restoration including results at State Key Laboratory of Hydraulics and Mountain River Engineering, are summarized in this paper, on topics of serious influences to fluvial processes of rivers in Sichuan; general principles and special principles in stream corridor restoration techniques to secondary disasters of earthquakes; focus on the stability of rivers in the earthquake district; Methodology and practice examples. Further studies are especially required, including strengthen inter-disciplines studies in areas of hydraulic engineering, geo-science, and ecologic and environmental science to explore theory and key techniques of river corridor restoration after the Wenchuan earthquake.关键词：Wenchuan earthquake;Reconstruction;River sedimentation;fluvial processes;Stream restoration
- 2700
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- 4
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- 2
发布时间：2023-11-14 - 摘要：Abstract:The changes of the formation of debris flows after Wenchuan Earthquake were analyzed, including loose materials, micro-topography and hydrological condition. Analysis suggested that the total of the loose mass generated by the collapse and landslides reaches about 28×10^8m^3, which provides abundant materials for debris flows for a long term. The change of landform and especially the blockage of channel will increase the scale of debris flow. The conditions of the surface water infiltration, runoff and flow concentration are changed by the strong surface disturbance and large-scale destructive vegetation damage, which is beneficial to the formation of the erosion and flood peak easier. The great changes of the river basin constitute the conditional combination of the debris flow formation. Therefore, the intensity of post-earthquake debris flow increases rapidly and debris flow becomes one of the most serious risk source. The main characteristics of debris flows after Wenchuan Earthquake were as follows. The number of debris flow gully increased, a large number of debris flows occurred in gullies which had no debris flows before the earthquake. The critical rainfall decreased significantly. The events occurred at high frequency and in group. The the density increased by about 10% to 30% and transitional or viscous flows occurred in many gullies of turbulent flows. The discharge increased by about 50%~100%, beyond the results calculated by the current methods. The tendency of debris flow is that the intensity will grow and then devay, alternative with active and quiet periods. The first active period will last for 15 years. The trigger and control factor depends mainly on the supplies of loose material. The valleys that have rich materials and more than 5 km^2 of area will be the most dangerous in the following years.Accordingly, we proposed the strategies for mitigation of debris flow, including discrimination of potential debris flow and specification of countermeasures; risk analysis and management; calculation of magnitude and regular monitoring and warning system.关键词：Wenchuan earthquake;debris flow;formation conditions;activity characteristics;disaster prevention
- 3490
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- 0
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- 105
发布时间：2023-11-14 - 摘要：Abstract:In the conceptual framework of self-organized criticality (SOC),and by investigating the typical slopes in Ⅸ seismic zone of Wenchuan earthquake,the negative power-law relationship of landslides between volume and number,as well as between depth and number was found.Furthermore, landslides also demonstrated the similar characteristics in Ⅹ seismic zone of Wenchuan earthquake. Based on the principle of quasi-static theory,the sand-pile model centrifugation tests repeated the dynamic behavior of slope under seismic disturbances, and the dynamical characteristics of landslips can be showed with negative power distribution law when the model box floor tilted 1.5°, but showed normal distribution when 3.0°, and the cellular automaton models revealed the dynamical mechanism of the evolution of sand pile model with the changes of disturbance intensity by numerical simulation. It was suggested that the slope system in younger or maturity age has the basic properties of intrinsic SOC. There is a seismic intensity threshold, the distribution law between size and frequency of landslides triggered by earthquake can be described under the threshold, and both the huge scale and small scale landslides disasters comply with the same formation mechanism.关键词：Wenchuan earthquake;landslide;self-organized criticality (SOC);centrifugation test on sand-pile model;cellular automata
- 2981
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- 4
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- 17
发布时间：2023-11-14
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