Characterisation of stress and moisture-dependent resilient behaviour for compacted clays in South China

2019

In the strict framework of limit analysis, an analytical approach is derived to obtain the upper bound solutions for threedimensional inhomogeneous slopes in clays under undrained conditions. Undrained strength profiles increasing linearly with depth below the crest of the slope and below the outline surface of the slope are assumed representative of cut slopes and natural slopes, respectively. Stability charts are produced for the cut slopes and the natural slopes under both static and pseudostatic seismic loading conditions. e presented charts are convenient to assess the preliminary and short-term stability for 3D slopes in practical applications, such as rapid excavation or buildup of embankments and slopes subjected to earthquakes. Compared with the available results from the finite element limit analysis method, a better estimate of the slope safety is obtained from the analytical approach.

Section: Stability Analysismentioning

confidence: 99%

Static and Seismic Stability Charts for Three‐Dimensional Cut Slopes and Natural Slopes under Short‐Term Undrained Conditions

Zhou

2019

“…When the fracture density is high, the continuous saturation zone is formed inside the slope. According to bivariate unsaturated shear strength formula put forward by Fredlund et al [30], the strength of unsaturated soil is determined by several factors [31,32] such as effective shear strength parameters (c′ and φ′), matrix suction (u a −u w ), and φ b . When the soil is saturated, the effective shear strength parameters (c′ and φ′) decrease, the matrix suction almost disappears in the saturated region, and φ b decreases accordingly.…”

Section: Analysis Of In Uence Of Fracture On Slope Stabilitymentioning

confidence: 99%

Effect of Colluvial Soil Slope Fracture’s Anisotropy Characteristics on Rainwater Infiltration Process

Zeng

Liu

et al. 2018

The SEEP/W module of finite element software GEO-slope is used to analyze the effects of fracture depth, permeability coefficient ratio, fracture angle, and fracture number on the rainwater infiltration process. Moreover, the effect of fracture seepage anisotropy on slope stability is discussed combining with unsaturated seepage theory. The results show that the pore water pressure in the fracture increases rapidly with the rainfall until it changes from negative pressure to positive pressure. The greater the fracture depth is, the greater the pore water pressure in the fracture is, and the greater the infiltration depth at the time of rainfall stopping is. When the permeability coefficient is greater than the rainfall intensity, the permeability coefficient ratio has a great influence on the infiltration process of rainwater. The smaller the fracture angle is, the greater the maximum pore water pressure is in the fracture depth range, and the greater the depth of the positive pore water pressure is. However, with the increase of fracture angle, the infiltration depth decreases, and the range of the surface saturation area of slope increases obviously. With the increase of fracture density, the saturated positive pressure region is connected to each other in the slope. The influence range and the degree of the rainwater on the seepage field are larger and larger. There is a power relation between the saturation area and the fracture number, and also the concentration distribution of long fractures directly forms the large-connected saturated zone and raises groundwater. The range of the saturated zone and variation law of the pore water pressure under fracture seepage are obtained, which provide a reference for the parameter partition assignment of slope stability analysis under fracture seepage.

“…Constructing road embankments on soft soil foundation, or there exists sinkholes or voids underneath, faces the threat of excessive settlement or different settlement. Although lightweight fill, piles, and subgrade enhancing technologies are always adopted to solve the problem, as well as other engineering issues, implementing a geosynthetic is often necessary to reduce settlement and enhance stability [1][2][3][4][5][6][7]. In reinforced structures, the geosynthetic mainly plays a load redistribution role between the subsided zone and the surrounding less-deformed zone.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Geomembrane Effect Based on Mobilized Shear Stress due to Localized Sinking

Lü

Liu

et al. 2019

Installing geosynthetic reinforcement at the bottom of the embankment will provide positive support for subgrade stability and settlement control, if there is a void or a weak foundation. In routine design work, the geomembrane effect must be well estimated and the tensile strain should be precisely predicted. Conventional analytical methods often adopt the limit state method to calculate the overlying load on the deflected geosynthetic. However, this assumption does not necessarily apply to all conditions, especially when the foundation soil can provide certain resistance. In this study, a semiempirical prediction method for evaluating the geomembrane effect of the basal reinforcement was proposed, and an iterative solution for calculating tensile strains of a deflected geosynthetic was deduced. In derivation, a virtual inclined slip surface and interaction between the geosynthetic and soil were quantitatively evaluated by coupling the arching effect and the geomembrane effect. Moreover, the development of shear stress along the slip surface can be considered, as well as different segments of the basal reinforcement. en, the proposed method was validated by two large-scale experiments. Comparison of the results of this method with measurements and results of other analytical models confirmed that this analytical method can take good care of the varying process of the localized sinking, regarding the overlying loads on the geosynthetic and the subsequent tensile strains.