Dynamic Response and Failure Process of a Counter-Bedding Rock Slope under Strong Earthquake Conditions

There are massive landslides and potential landslides along the Three Rivers Basin in the Qinghai–Tibet Plateau, which pose a serious threat to the Sichuan–Tibet Railway. A normal shaking table model test was conducted to study the dynamic characteristics and dynamic response of a symmetrical counter-bedding rock slope based on the Zongrong Village landslide. The influences of the dynamic parameters, seismic wave type, and a weak intercalated layer on the slope’s dynamic response were considered. The results showed symmetry between the growth trend of the acceleration amplification factor and other research results. When the input wave amplitude was constant, the acceleration amplification factor increased at first and then decreased as the frequency increased. When the input frequency was near the slope’s natural frequency, the acceleration amplification factor increased at first and then decreased with an increase in the input amplitude and reached the maximum value at 0.3 g. The acceleration amplification factor increased linearly with height in the vertical direction inside the slope but increased slowly at first and then sharply along the slope surface, reaching the maximum value at the slope’s top and exhibiting an obvious “elevation effect”. When sinusoidal waves, Wolong waves, and Maoxian waves with the same amplitude were input, the slope’s amplification effect on the bedrock wave was more obvious. The weak intercalated layer showed the phenomenon of “thin layer amplification” and “thick layer attenuation” in response to the input seismic wave. The slope’s failure process can be roughly divided into three stages: (1) the formation of tensile cracks at the top and shear cracks at the toe; (2) the extension of cracks and the sliding of the slope-surface block; (3) the formation of the main sliding surface.

Shear Properties and Strength of Weak Intercalated Layers in Dam Foundation of Datengxia Power Station

For gravity dam with weak intercalated layer in foundation,the shear strength of the weak intercalated layers is the main factor in the control of the dam stability. It is the key point of geological and experimental work to ensure the shear strength to satisfy safety and economy of dam. The material composition,mineralogical composition and structure,genetic type and characteristics of shear stress and strain of weak intercalated layer in dam foundation of Datengxiapower station are analyzed,the valuation rule of the shear strength of weak intercalated layer with plasticfailure mode is discussed,and finally the recommended geological value of shear strength of weak intercalated layer in this project is proposed.

Analysis and Treatment of Landslide at the Tunnel Portal in Nanjing Road

The landslide at the tunnel portal in Nanjing Road is mainly determined by a weak intercalated layer between the completely weathered bedrock and the strongly weathered bedrock. The weak intercalated layer has low permeability and weak shear strength, and its interface dip outside of the slope. As the consequence, landslide is likely to happen again due to a rainstorm or other inducement. In order to prevent a second landslide, a comprehensive treatment scheme is presented, which implements anti-slide piles as the major treatment and several auxiliary treatments including filling and compacting the cracks, cutting-off and draining water, locally bolt-shotcrete support, and repairing the existing retaining wall and the lattic frame beams. After applying this scheme, the slope stability meets the design requirements.

Numerical Simulation of the Tunnel Blasting Process in Weak Intercalated Layer

In order to study the effect which weak intercalated layer produces in the rock during the process when explosives transferring the energy, this research uses ANSYS/LS-DYNA toexplore the numerical simulation of the law which the stress wave of weak intercalated layer rock with different thickness propagates and decays. It also compares the effect to stress wave in certain position when the thickness of the intercalated layer is different or inexistent. The outbreak pheno-menon of the rock with weak intercalated layer occurs in the blasting process is analyzed as well, so the effect of weak intercalated layer should be fully considered when arranging blast hole around the tunnel. Then the research provides the theoretical basis for selecting blasting parameters.