盾构隧道施工引起的地层位移对既有桥梁桩基的影响分析

盾构法已成为我国城市地铁施工中一种重要的施工方法,由施工引起的地面沉降对其周围环境的影响是盾构隧道设计和施工中非常重要的问题。本文根据某地铁盾构隧道穿越桥桩工程,应用三维有限差分软件FLAC-3D进行了数值模拟,并对计算结果和实测结果进行了对比和分析,研究了隧道开挖中产生的位移对既有桥桩的影响,得出桩基变形的规律,并提出相应的工程建议。     

The Santa Barbara Basin is a symbiosis oasis

It is generally agreed that the origin and initial diversification of Eucarya occurred in the late Archaean or Proterozoic Eons when atmospheric oxygen levels were low and the risk of DNA damage due to ultraviolet radiation was high. Because deep water provides refuge against ultraviolet radiation and early eukaryotes may have been aerotolerant anaerobes, deep-water dysoxic environments are likely settings for primeval eukaryotic diversification. Fossil evidence shows that deep-sea microbial mats, possibly of sulphur bacteria similar to Beggiatoa, existed during that time. Here we report on the eukaryotic community of a modern analogue, the Santa Barbara Basin (California, USA). The Beggiatoa mats of these severely dysoxic and sulphidic sediments support a surprisingly abundant protistan and metazoan meiofaunal community, most members of which harbour prokaryotic symbionts. Many of these taxa are new to science, and both microaerophilic and anaerobic taxa appear to be represented. Compared with nearby aerated sites, the Santa Barbara Basin is a 'symbiosis oasis' offering a new source of organisms for testing symbiosis hypotheses of eukaryogenesis.     

额济纳旗环境人口容量与人口分布研究

分析了额济纳旗人口与环境的演变过程以及人口增长对生态环境的主要影响,计算了环境人口容量,在此基础上确定了可能控制的人口自然增长率阈值,并对今后20年内的人口数量进行预测.据此提出合理分布人口,实现生态环境可持续利用的建议:实施生态移民,阻断荒漠化过程;依托原有人口分布区的基础设施优势,合理布局人口;妥善安置移民的生产和生活,协调移民新村与环境的关系.     

地方高校研究生生源的现状及对策的探讨

对地方高校研究生生源的现状及其特点进行分析,认为地方高校研究生生源数量不足,缺乏优秀生源,生源分布不均衡,调剂生源过多;在这基础上,提出加强招生宣传,加强学科建设,重视研究生的培养质量,提高研究生的就业率和就业质量等对策。