Dynamic response of a slope reinforced by double-row antisliding piles and pre-stressed anchor cables

Large-scale shaking table tests were conducted to study the dynamic response of a slope reinforced by double-row anti-sliding piles and prestressed anchor cables. The test results show that the reinforcement suppressed the acceleration amplification effectively. The axial force time histories are decomposed into a baseline part and a vibration part in this study. The baseline part of axial force well revealed the seismic slope stability, the peak vibration values of axial force of the anchor cables changed significantly in different area of the slope under seismic excitations. The peak lateral earth pressure acting on the back of the anti-sliding pile located at the slope toe was much larger than that acting on the back of the anti-sliding pile located at the slope waist. The test results indicate an obvious load sharing ratio difference between these two anti-slide piles, the load sharing ratio between the two anti-sliding piles located at the slope toe and the slope waist varied mainly in a range of 2-5. The anti-slide pile at the slope waist suppressed the horizontal displacement of the slope surface.

Application of dynamic analysis of strength reduction in the slope engineering under earthquake

At present,the methods of analyzing the stability of slope under earthquake are not accurate and reasonable because of some limitations. Based on the real dynamic tensile-shear failure mechanism of slope,the paper proposes dynamic analysis of strength reduction FEM (finite element method) and takes the reduction of shear strength parameters and tensile strength parameters into consideration. And it comprehensively takes the transfixion of the failure surface,the non-convergence of calculation and mutation of displacement as the criterion of dynamic instability and failure of the slope. The strength reduction factor under limit state is regarded as the dynamic safety factor of the slope under earthquake effect and its advantages are introduced. Finally,the method is applied in the seismic design of anchors supporting and anti-slide pile supporting of the slope. Calculation examples show that the application of dynamic analysis of strength reduction is feasible in the seismic design of slope engineering,which can consider dynamic interaction of supporting structure and rock-soil mass. Owing to its preciseness and great advantages,it is a new method in the seismic design of slope supporting.

Strength reduction and step-loading finite element approaches in geotechnical engineering

The finite element limit analysis method has the advantages of both numerical and traditional limit equilibrium techniques and it is particularly useful to geotechnical engineering.This method has been developed in China,following well-accepted international procedures,to enhance understanding of stability issues in a number of geotechnical settings.Great advancements have been made in basic theory,the improvement of computational precision,and the broadening of practical applications.This paper presents the results of research on（1） the efficient design of embedded anti-slide piles,（2） the stability analysis of reservoir slopes with strength reduction theory,and（3） the determination of the ultimate bearing capacity of foundations using step-loading FEM（overloading）.These three applications are evidence of the design improvements and benefits made possible in geotechnical engineering by finite element modeling.

Two new reinforcement techniques applicable in high steep slopes along the Chengdu-Lhasa Highway, Southwest China

Anti-slide pile and anchoring hole are two types of reinforcement techniques popularly used in slope reinforcement. However, some defects of these two techniques are found in slope engineering practices. Utilizing higher tensile strength of pre-stressed structures, the authors devise two new types of slope reinforcement techniques, i.e. pre-stressed anchoring beam and pre-stressed anti-slide pile, in an attempt to overcome those defects of the existing techniques. These two new techniques are characterized by gathering multiple functions, e.g. engineering investigation, reinforcement, drainage, monitoring and strength supplement, so as to achieve high reinforcement efficiency, convenient checking, and higher ratio of function to cost. It is hoped that, if applying these two new techniques in remedies of landslide hazards along the Chengdu-Lhasa Highway, better reinforcement effects will be obtained.

Comprehensive Determination of Reinforcement Parameters for High Cut Slope Based on Intelligent Optimization and Numerical Analysis

High cut slopes have been widely formed due to excavation activities during the period of immigrant relocation in the reservoir area of the Three Gorges, China. Effective reinforcement meas-ures must be taken to guarantee the stability of the slopes and the safety of residents. This article pre-sents a comprehensive method for integrating particle swarm optimization （PSO） and support vector machines （SVMs）, combined with numerical analysis, to handle the determination of appropriate rein-forcement parameters, which guarantee both slope stability and lower construction costs. The relation-ship between reinforcement parameters and slope factor of safety （FOS） and construction costs is in-vestigated by numerical analysis and SVMs, PSO is adopted to determine the best SVM performance resulting in the lowest construction costs for a given FOS. This methodology is demonstrated by a prac-tical reservoir high cut slope stabilised with anti-sliding piles, which is located at the Xingshan （兴山） County of Hubei （湖北） Province, China. The determination process of reinforcement parameters is discussed profoundly, and the pile spacing, length, and section dimension are obtained. The results pro-vide a satisfactory reinforcement design, making it possible a signficant reduction in construction costs.