In situ yield behaviour of a coal pillar

Summary An indication of the complete stress-strain behaviour of coal was obtained through instrumenting a headgate yield pillar and monitoring the changes in vertical and horizontal pillar stress, pillar strain, and roof-floor convergence as a function of time and distance from the moving longwall face. A semiautomated monitoring program was conducted over a 5 month period as the longwall face advanced toward and eventually passed the instrumented pillar. The development of a confined core and yield zone within the pillar was confirmed by the vertical and horizontal stress changes. Thein situ pre-failure (208 to 661 MPa) and post-failure moduli (55 to 208 MPa) of the coal were determined from the change in pillar stress versus pillar strain. Thein situ moduli are an order of magnitude lower than the 3450 MPa, commonly assumed for coal.     

Numerical Simulation of Rainfall-induced Xianchi Reservoir Landslide in Yunyang, Chongqing, China

A calamitous landslide happened at 22:00 on September 1, 2014 in the Yunyang area of Chongqing City, southwest China, enforcing the evacuation of 508 people and damaging 23 buildings. The landslide volume comprised 1.44 million m3 of material in the source area and 0.4 million m3 of shoveled material. The debris flow runout extended 400 m vertically and 1600 m horizontally. The Xianchi reservoir landslide event has been investigated as follows: (1) samples collected from the main body of landslide were carried out using GCTS ring shear apparatus; (2) the parameters of shear and pore water pressure have been measured; and (3) the post-failure characteristics of landslide have been analyzed using the numerical simulation method. The excess pore-water pressure and erosion in the motion path are considered to be the key reasons for the long-runout motion and the scale-up of landslides, such as that at Xianchi, were caused by the heavy rainfall. The aim of this paper is to acquired numerical parameters and the basic resistance model, which is beneficial to improve simulation accuracy for hazard assessment for similar to potentially dangerous hillslopes in China and elsewhere.     

土体应力-应变关系转型问题分析

通过对土体应力应变试验结果的分析,明确指出了土体普遍存在的应力-应变关系转型现象。提出了按后破坏模量和临界围压两个参数判别土体应力-应变关系转型的方法,对影响土体应力-应变关系转型的因素包括土的类型、围压、初始密度或含水率、排水条件及应力路径等进行了简要分析。最后,对砂土初步提出了一个能反映转型现象的组合应力-应变关系模型的理论框架。