8603工作面回采巷道支护方案优化及数值模拟

针对深部软岩巷道围岩变形量大,传统支护结构失效的问题,以煤峪口矿回采巷道为研究背景,综合应用数值模拟和工程实践对原支护方案下巷道破坏特征进行分析,提出采用中空注浆锚索进行补强支护,并采用FLAC3D分析了两种支护方案下巷道围岩的收敛量以及应力分布情况,得出了优化支护方案能够有效控制巷道围岩破碎程度,并通过工程实践得到验证。     

Seismic behavior of geosynthetic-reinforced retaining walls backfilled with cohesive soil

This study investigates the seismic performance of geosynthetic-reinforced modular block retaining walls backfilled with cohesive, fine grained clay-sand soil mixture. Shaking table tests were performed for three ½ scaled (wall height 190 cm) and ¼ scaled model walls to investigate the effects of backfill type, the influence of reinforcement length and reinforcement stiffness effects. The El Centro and Kobe earthquake records of varying amplitudes were used as base acceleration. Displacement of the front wall, accelerations at different locations, strains on the reinforcements, and the visual observations of the facing and the backfill surface were used to evaluate the seismic performance of model walls. The model walls were subjected to rigorous shaking and the walls did not exhibit any stability problems or signs of impending failure. The maximum deformations observed on the models with cohesive backfill was less than half of the deformation of the sand model. The load transfers between the geogrid and cohesive soil was comparable to that of sand and hence the needed reinforcement length was similar as well. As a result; the model walls with cohesive backfills performed within acceptable limits under seismic loading conditions when compared with granular backfilled counterparts.     

Three-dimensional finite element analysis of geosynthetic-reinforced soil walls with turning corners

The paper presents in-depth three-dimensional finite element analyses investigating geosynthetic-reinforced soil walls with turning corners. Validation of the 3D numerical procedure was first performed via comparisons between the simulated and reported results of a benchmark physical modeling built at the Royal Military College of Canada. GRS walls with corners of 90°, 105°, 120°, 135°, 150°, and 180° were simulated adopting the National Concrete Masonry Association guidelines. The behaviors of the GRS walls with corners, including the lateral facing displacement, maximum reinforcement load, factor of safety, potential failure surface, vertical separation of facing blocks, and types of corners were carefully evaluated. Our comprehensive results show (i) minimum lateral displacement occurs at the corner; (ii) lower strength of reinforcements are required at the corner; (iii) higher corner angles lead to lower stability; (iv) potential failure surface forms earlier at the end walls; (v) deeper potential failure surfaces are found at the corners; (vi) larger numbers of vertical separations are found at walls with smaller corner angles. The paper highlighted the salient influence of the corners on the behaviors of GRS walls and indicated that a 3D analysis could reflect the required reinforcement length and the irregular formation of the potential failure surfaces.     

Soft Matter Technology at KIT: Chemical Perspective from Nanoarchitectures to Microstructures

Bioinspiration has emerged as an important design principle in the rapidly growing field of materials science and especially its subarea, soft matter science. For example, biological cells form hierarchically organized tissues that not only are optimized and designed for durability, but also have to adapt to their external environment, undergo self‐repair, and perform many highly complex functions. Being able to create artificial soft materials that mimic those highly complex functions will enable future materials applications. Herein, soft matter technologies that are used to realize bioinspired material structures are described, and potential pathways to integrate these into a comprehensive soft matter research environment are addressed. Solutions become available because soft matter technologies are benefitting from the synergies between organic synthesis, polymer chemistry, and materials science.     

我国环境土壤中的重要超铀核素分布

Pu、Am、Np是3种重要的超铀核素，环境中的这些核素主要来源于人类的核活动，包括大气层核武器试验、核设施排放和核事故释放等。这些超铀核素不仅具有放射性，还兼具化学毒性。我国地域辽阔，环境土壤类型丰富，在当前核电事业蓬勃发展的背景下，建立和扩大我国环境土壤中这些重要超铀核素的“准本底”数据库是辐射环境安全评价的重要组成部分，也是公众关心的热点问题。近30多年来，研究人员对我国不同环境土壤中这几种超铀核素从不同科学角度开展了调查测量研究。本文对此进行整理和分析，对我国环境土壤中这些重要超铀核素（主要是Pu核素，还包括241Am和237Np）的来源、浓度水平和分布特征进行讨论和综述，为辐射环境安全评价奠定基础。     

软土地区管幕群顶管施工地面沉降监测与分析

依托上海14号线桂桥路站管幕段实例工程,对管幕群顶管顶进施工过程地面沉降情况进行监测,分析群顶管施工对地面沉降的影响,在此过程中对本工程采用水土分算或合算进行讨论。根据顶进过程实际工况和监测数据,分析管幕群顶管施工影响地面的原因,提出相应控制措施。结果表明:①管幕群顶管施工引起最大地面沉降出现在始发井出加固区区域;②在本工程中采用水土合算计算正面土压力较为符合实际情况;③管幕群顶管施工过程中影响地面变形的因素主要包括前舱压力、顶进速度、洞门止水、管壁摩擦和同步注浆等方面。     

Field study of a retaining wall constructed with clay-filled soilbags

This paper presents a field study of constructing retaining walls using soilbags that are formed by filling the excavated clayey soils into woven bags (geosynthetics). The strength and deformation of the soilbags filled with clayey soils were studied via laboratory tests. A 100?m testing retaining wall was constructed with soilbags in a waterway project. The lateral deformation, the lateral pressures and the surface settlements of the testing retaining wall were monitored during construction and after 7 months operation. The results show that the soilbags can increase the strength of clayey soils. After 7 months of the completion, the lateral deformation and the surface settlement of the testing retaining wall tend to be stable with the maximum values of 29.4?cm and 19.2?cm, respectively. The lateral earth pressure on the front retaining structure could be positively reduced owing to the interlayer's friction of soilbags. Compared to the conventional gravity concrete retaining wall, about 38% construction cost was saved in the 100?m testing retaining wall.     

Design and calibration of a laminar soil box suitable for a low-capacity shake table using free-field tests on Ganga sand

The present study concentrates on design, commissioning and calibration of a uniaxial laminar soil box suitable for use on a low base-shear capacity shake table available at IIT Kanpur, India. The box is designed to simulate the behavior of soil deposits subjected to earthquake motions, with minimal boundary effects due to reflection of waves at the boundary. The 1.1 m × 1.6 m × 0.765 m box is comprised of a series of individual lamina supported independently on multiple roller bearings guided through a guide channel. The outer frame connected to the guide rods is designed in such as way that it can transfer the self weight of each lamina out of the shake table. A series of free-field tests are carried out on dry Ganga sand sample to calibrate the box. Dynamic response parameters, such as acceleration, displacement, stress-strain behavior, strain-dependant modulus and damping ratio of the sand at various depth are investigated. Large strain and subsequent increased inelasticity is observed towards the top of the sand bed. The experimental results are further compared with equivalent-linear SHAKE analysis and nonlinear finite element ground response analysis of the free-field soil using OpenSees for assessing the performance of the laminar box.