Dynamic analysis of an axially loaded pile embedded in elastic-poroelasitc layered soil of finite thickness

This paper presents an analytical solution for determining the dynamic characteristics of axially loaded piles embedded in elastic-poroelastic layered soil of finite thickness. The interface between the elastic and poroelastic soil coincides with the groundwater table level, which is explicitly taken into account in the solution. The pile is modelled as elastic one-dimensional rod to account for the effect of its dynamic characteristics on the response of the soil-pile system. The solution is based on Biot's poroelastodynamic theory and the classical elastodynamic theory, which we use to establish the governing equations of the soil and pile. Accordingly, the pile base resistance, shaft reaction, and the complex impedance of soil-pile system are obtained using the method of Hankel integral transformation. Following the validation of the derived solution, we identify the main parameters affecting the vertical dynamic impedance of the pile via a parametric study. The presented method poses as an efficient alternative for quickly estimating the dynamic characteristics of axially loaded piles, without having to resort to complex numerical analyses.     

中国耕地数量下降之剖析:1986～1995年

本文从不同的数据来源对比和分析了１９８６至１９９５年之间中国耕地资源数量下降的状况,并对其构成进行了详尽的剖析。指出农业结构调整（指耕地改为园地、林地、牧地、鱼塘）占地是耕地减少的主要原因,达到总量的６２％;其次是三项建设（国家建设、集体建设和农村建房）,占总量的２１％;第三是灾害毁地,占总量的１７％。针对存在的问题,本文提出了加强土地用途管制等对策。     

基于InSAR监测数据的石膏矿采空塌陷特征分析——以邳州平台矿和希州矿为例

石膏是一种重要的矿产资源,但石膏矿的大量开采会产生严重的采空塌陷隐患。目前关于石膏矿采空塌陷的研究多集中于采空区矿柱和护顶层的稳定性等方面,有关矿区采空塌陷地表变形及监测预报方面的研究甚少,也缺乏有效的研究方法。针对石膏矿开采后地面变形特征及塌陷特征研究,通过对矿区InSAR监测数据进行地表变形分析,确定了采空塌陷前的地表变形特征。根据邳州平台矿和希州矿2007—2018年InSAR监测数据进行计算分析,可以看出地面塌陷前,地表存在早期缓慢变形,可根据变形量及范围判断塌陷类型及范围。对InSAR监测数据的计算和分析可为矿区地面塌陷地质灾害的监测、预报及防治提供数据资料与科学依据。     

Vertical vibration of piles in viscoelastic non-uniform soil overlying a rigid base

Acta Geotechnica - This paper presents an analytical methodology that provides the dynamic response of an elastic pile embedded in viscoelastic non-uniform soil overlying a rigid base, when...     

Vertical dynamic response of a pile embedded in a poroelastic soil layer overlying rigid base

Acta Geotechnica - This paper presents an analytical solution to investigate the vertical dynamic response of an elastic pile embedded in poroelastic soil overlying a rigid base. The pile top is...     

Analysis of gob collapse characteristics in gypsum mine based on InSAR monitoring data—A case study of Pizhou Pingtai and Xizhou mine

Gypsum is an important mineral resource. Bulk mining of gypsum will cause serious gob collapse. At present, the research on gob collapse of gypsum mine mainly focuses on the stability of pillars and top layers in the gob area. The research on the surface deformation in gob collapse areas and the monitoring and forecasting methods is rare. What’s more, there is also a lack of effective methods. This article focuses on the study of surface deformation characteristics and collapse characteristics after gypsum mining. The surface deformation characteristics before gob collapse can be obtained from the InSAR monitoring data analysis on ground deformation in the mining area. According to the calculation and analysis of InSAR monitoring data of Pingtai and Xizhou mine from 2007 to 2018, it can be seen that the surface deformed gradually in the early stage before gob collapse. The deformation amount and scale can be used to analyze the gob type and scale. This research can provide data basis and scientific evidence for monitoring, forecasting and preventing ground collapse in gypsum mining area.