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Guo H.,Southwest Jiaotong University | Yao L.,Southwest Jiaotong University | Yao L.,MOE Key Laboratory of High speed Railway Engineering | Yao L.,China Institute of Technology | Sun S.,Southwest Jiaotong University
Journal of Modern Transportation | Year: 2015

In the feasibility stage of the transport route selection, large-scale geological investigations are advised before the route is determined. Therefore, rapid assessment of seismic landslide zones can be completed by the second development of the ArcGIS program. A large amount of geological information can be obtained by this method which is based on existing remote sensing image data. The integrated data can then be used to guide route location selection. This method assesses the angle between the main axis of the slope and the axis of the route and produces a zoning map that identifies slopes that threaten the route by combining with other characteristics including the climate in the study area, and the lithology and seismic structure of the near-field region. A hazard-zone map showing the degree of earthquake-induced landslide can be quickly generated by the comprehensive index method. The seismic landslide zone map was verified by comparison with the findings of a geological engineering survey conducted in the study area. © 2015, The Author(s).

Zhu H.-W.,Southwest Jiaotong University | Yao L.-K.,Southwest Jiaotong University | Yao L.-K.,MOE Key Laboratory of High speed Railway Engineering | Jiang L.-W.,Southwest Jiaotong University | Qiu Y.-L.,Southwest Jiaotong University
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

The deformation failure modes of gravity retaining walls under earthquakes are investigated by using the near-field data in Wenchuan Earthquake. It is found that the deformation failure modes of the retaining wall more closely relate with the foundation. The wall on the rock foundation mainly exhibits inclination deformation, while the wall on the soil foundation mainly shows slip deformation. Based on the Winkler foundation model, the soil mass is viewed as the combination of a set of springs and ideal rigid plasticity objects, and the relevant methods for the seismic earth pressure and the point of resultant force for gravity retaining wall under different displacement modes are proposed. The results show that the distribution of seismic earth pressure can be expressed differently under different deformation failure modes, except the slip deformation, and that the distribution of seismic active earth pressure against retaining wall is nonlinear under the rest of the deformation failure modes. The point of resultant force for the gravity retaining walls on the rock foundation is higher than that of the walls on the rock foundation. Large-scale shaking table tests for gravity retaining walls on rock foundation and soil foundation are conducted to test the proposed theory. It is indicated that the experimental results are in accordance with the theoretical ones.

Luo Y.,Southwest Jiaotong University | Yao L.-K.,Southwest Jiaotong University | Yao L.-K.,MOE Key Laboratory of High speed Railway Engineering | Yao L.-K.,China Institute of Technology
Chinese Journal of Engineering Design | Year: 2015

The scheme evaluation of mountain railway location design has the characteristic that it has many qualitative indexes. The traditional evaluation methods have not fully taken the uncertainty characteristics of qualitative indexes into account, and it also lacks of appropriate evaluation methods when qualitative indicators and quantitative indicators cross with each other. Firstly, the advantages of the cloud model in describing uncertain information were used to improve the traditional AHP. Combined with deviation method, the subjective weight and objective weight of index were calculated respectively. Through a new weighted fusion mode, the combination weight was formed. Then, according to the principle of uncertain reasoning of cloud model, an effective quantification of qualitative indexes was achieved by using the cloud generator based on the evaluation about qualitative index made by experts using linguistic variables. Finally, the projection method was introduced to select the optimal scheme. Therefore, a new model of comprehensive scheme evaluation which contained both quantitative and qualitative indexes was proposed, and an example of local alignment scheme comparison was used to illustrate its feasibility and practicability. It provides a new idea and method for the scheme evaluation of railway location design in mountains.

Huang Y.,Southwest Jiaotong University | Yao L.,Southwest Jiaotong University | Yao L.,MOE Key Laboratory of High Speed Railway Engineering | Yao L.,China Institute of Technology | And 2 more authors.
Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and Engineering | Year: 2015

2Based on the detailed data of “4·20” Lushan Earthquake from VII to IX seismic intensity zone, the distribution law of landslides triggered by earthquakes in different seismic intensity zones was explored. The mechanism is interpreted from a physical point of view. The field data shows that there exists a power-law relationship between the area and frequency of landslides in IX, VIII, VII seismic intensity zones. Exponent b of the power-law in different zones is closed. But with the decline of the seismic intensity, the density of landslides decreases monotonically. The cellular automaton simulation reveals that the dynamical mechanism of sand-pile model is subject to the same power-law distribution, with 0. 5 decline ratio of disturbance intensity. The density of avalanche decreases linearly. Physics experiments with shaking table sandpile model also support above results. It is concluded that the power-law relationship between the scale and frequency is the basic regulation of landslides triggered by earthquakes from VII to IX seismic intensity zone. Different densities may serve as a major indicator of various intensities of damage. The research results may be used to provide scientific basis to sketch and assess the mountain disasters triggered by earthquake. ©, 2015, The Editorial Board of Journal of Basic Science and Engineering. All right reserved.

Xu G.-X.,Southwest Jiaotong University | Xu G.-X.,Shijiazhuang University | Yao L.-K.,Southwest Jiaotong University | Yao L.-K.,MOE Key Laboratory of High speed Railway Engineering | And 2 more authors.
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2010

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.

Yao L.-K.,Southwest Jiaotong University | Yao L.-K.,MOE Key Laboratory of High speed Railway Engineering | Yao L.-K.,China Institute of Technology | Huang Y.-D.,Southwest Jiaotong University | Yang Q.-H.,Southwest Jiaotong University
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2010

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 dynami-cal 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.

Duan S.,Southwest Jiaotong University | Yao L.,Southwest Jiaotong University | Yao L.,China Institute of Technology | Yao L.,MOE Key Laboratory of High Speed Railway Engineering | Guo C.,Southwest Jiaotong University
Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology | Year: 2016

A method of determining the stage of geomorphic development is built up in complicated mountainous river basin, which can also be used to regional assessment of the regional severity of collapse-landslide caused by earthquake or heavy rainstorm. Based on the theory of the erosion cycle and the theory of river's developing by stages, the stage of geomorphic development is estimated by combining the Strahler's integral (HI) and the stream-gradient indices (SL indices). Then regional severity of collapse-landslide is estimated by development stage with DEM (digital elevation model) and ArcGIS technique. Both of the change point of HI of branch basins and the breakpoint of SL indices can be the cut-off point of development stage. In the same development stage, HIs are very similar. HI of the whole same development stage can be the representative HI of all the HIs of branch basins. The basins in development stage of late youth and maturity have the severest regional disasters, with HI change from 0.45~0.6. © 2016, Harbin Institute of Technology. All right reserved.

Ren J.,MOE Key Laboratory of High Speed Railway Engineering | Yang R.,MOE Key Laboratory of High Speed Railway Engineering | Wang P.,MOE Key Laboratory of High Speed Railway Engineering | Yong P.,Southwest Research Institute | Wen C.,Southwest Jiaotong University
Transportation Research Record | Year: 2014

This study is a preliminary analysis of the causes of upwarping of reinforced concrete slabs of a twin-block slab track, specifically on the subgrade-bridge transition section. The analysis considers the structural features and force characteristics of slab track 011 the basis of site investigations and numerical simulation, and a corresponding repair method is proposed. It is determined that the temperature and temperature gradient of the slab, the connection status between the slab and the hydraulically bonded layer (HBL), and the position of the terminal spine are the main factors that lead to the upwarping of the slab. Model tests on the force transmission parameters between slab and HBL, are carried out to measure the adhesive strength of the cohesive contact and the friction coefficient for the frictional contact. The adhesive strength is found to range from (1.803 to 1.57 MPa. The actual friction coefficient with large dispersion varies significantly from 1.5 to 3.0 because of the influence of the strength of the material and the friction roughness. The analysis output shows that the upwarping of the slab decreases with the reduction of temperature and temperature gradient of the slab, but the upwarping increases with the decrease in adhesive strength and friction coefficient. Increasing the number of terminal spines with 4-m spacing, which is optimized after the spacing effect, contributes to the reduction of the slab upwarping. A reasonable layout scheme for anchor pins can significantly improve the integrity and stability of track structure affected by slab upwarping. From the output of the analysis, a repair method that involves setting additional anchor pins between the slab and HBL is thus recommended.

Su Q.,MOE Key Laboratory of High Speed Railway Engineering | Li X.,Southwest Jiaotong University | Bai H.,Southwest Jiaotong University
Applied Mechanics and Materials | Year: 2011

A series of tests based on large scale model are designed to study dynamic response of pile-broad subgrade, aiming at structure's response towards different load frequency and structure's performance under long-term dynamic load. The test results indicate that dynamic stress of reinforcement and soil decrease slightly with load frequency, while accelerations trend to increase. Soil under loading plate has certain supporting effect because stress of reinforcement is smaller in test group with soil remains. Performance of pile-board subgrade under long-term dynamic load is steady and reliable since none of stress and displacement varies obviously when loading times increase to 10 6. Ultimate bearing capacity of pile-board subgrade is much bigger than actual demand, so the structural type of pile-broad plate remains to be optimized. © (2011) Trans Tech Publications, Switzerland.

Zhou C.-B.,MOE Key Laboratory of High speed Railway Engineering | Su Q.,MOE Key Laboratory of High speed Railway Engineering | Bai H.,Sichuan Expressway Construction and Development Co. | He Y.,MOE Key Laboratory of High speed Railway Engineering | Zhao W.-H.,MOE Key Laboratory of High speed Railway Engineering
Applied Mechanics and Materials | Year: 2014

It's the first application of NEPBS crossing over-shallow-embedded metro in deep soft ground on new Shanghai-Hangzhou passenger dedicated railway (SHPDR) in China. It's necessary to study the engineering behavior of NEPBS in complex geology field. Long-term observation systems were installed at the typical test sections of SHPDR; Combined with theoretical analysis model, the mechanical properties and deformation laws were analyzed and tested. Measurement results show that the test reinforcement stresses of loading plates and supporting beams are small; the test bending moments agree well with the theoretical bending moments, which are far less than the resistance bending moments; the piles improved the mechanical properties of deep soft ground, so the plate-soil contact stresses are small, the maximum value is 132 kPa; 45 days after the train operation, the post-construction settlement is 1.86 mm; the settlements of individual test points are not yet stable, but they tend toward stability, which can meet the requirements of settlement control of SHPDR. © (2014) Trans Tech Publications, Switzerland.

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