顾北矿副井井壁与冻结壁的共同作用分析

共同作用指的是井壁和冻结壁两者之间的共同作用.文章介绍了冻结壁和井壁共同作用的分析方法,并对顾北煤矿井壁和冻结壁共同作用进行了数值模拟,得出了相应的结论.     

冻结施工立井井壁受力分析

本文阐述了冻结施工立井井壁在井筒施工期间、冻结壁解冻后和矿井投产后的受力情况。分析了冻结施工立井井壁在矿井投产后受到破坏的主要原因。提出了防止立井井壁破坏的途径。     

某矿冻结外层井壁受力监测与分析

为检查某矿井冻结井筒外壁的安全性,对该矿井井筒外壁两个水平的冻结压力、钢筋应力以及混凝土应变进行了受力变形监测。通过对实测数据的理论分析,得出外层井壁应力应变均满足设计要求,井筒外壁安全可靠。     

深厚表土中冻结壁与井壁相互作用的数值分析

冻结壁对井壁的作用力构成了深厚表土中冻结井外层井壁的外载;其增长规律与冻结壁与井壁之间的聚苯乙烯泡沫板压缩性能密切相关。为研究深厚表土中冻结井外壁外载的取值方法,以华东某冻结凿井工程为背景,基于冻土的弹塑性及蠕变本构方程,开展了冻结凿井过程中冻结壁与井壁相互作用的数值分析。结果表明：冻结壁对井壁的流变作用力极为显著;泡沫板的存在及其压缩性,可显著降低冻结壁作用力,尤其是弹塑性及流变作用力P_epc的数值,并影响其增长速度及增长规律;随着泡沫板压缩性降低直至泡沫板取消,冻结壁作用力由低速、近似线性增长,变为高速、非线性增长,从而易对井壁的早期安全构成威胁。因此,冻结凿井工程设计与施工中,应针对冻结壁的流变变形特性,审慎地研究确定泡沫板的材质及厚度。     

深部井壁冻结条件下的受力分析

由于煤矿深井井壁的质量直接影响了整个矿井安全,因此,有必要对井筒的内外受力进行监测。采用现场温度监测和进行受力分析来考察井壁的安全性;通过计算和测试,发现井壁受到冻结压力后在井壁浇筑一开始的时候增长较快,大致上表现出直线型增压型,然后开始曲线的增压段。冻结压力的数值受井壁土层层厚的影响比较大,而且表现出了不规则性。     

深厚表土层冻结法凿井外层井壁的受力实测分析

介绍了对宁夏红四矿主井冻结井壁的冻结压力、钢筋应力、混凝土应变和温度的监测方法。通过对主井井壁的实时监测,获得已成型冻结段井壁的冻结压力、钢筋应力和混凝土应变,掌握了深部冻结井壁的钢筋轴力、混凝土应变的变化规律,在此基础上评价冻结壁和井壁的安全状况。通过实时监测,主井井壁实现了信息化施工。     

井塔—桩筏基础—地基—井壁共同作用机理分析

介绍了由井塔、桩筏基础、地基和井壁组成的井塔结构体系的共同承载特性,将四者作为一个整体进行了研究,分析了共同承载时各部分之间的受力特点,为井塔基础的设计奠定了基础。     

绝热温升影响的冻结井壁温度场变化规律

为研究绝热温升对冻结井壁温度场的影响,根据井壁温度实测数据,采用ANSYS有限元分析软件对冻结壁大体积混凝土的温度场分布规律进行了数值分析,建立了考虑绝热温升影响的井壁温度场分布模型。实测与模拟结果表明:井壁浇筑后初期由于水化的热影响,井壁温度迅速升高,双曲线模型计算结果与实测值吻合程度较好。研究结果为预测冻结井壁温度场的变化规律提供了参考依据。     

冻结法施工立井井筒井壁结构设计研究

简述了冻结法施工的井筒井壁结构形式,研究了钢筋混凝土双层井壁厚度的计算方法,并以内蒙古某矿井为工程背景,对考虑混凝土强度提高系数前、后的计算结果进行了对比分析,以减薄井壁厚度,从而减少矿井投资。     

钻井法凿井井壁壁后充填研究

壁后充填是钻井法凿井砌筑井壁过程中的重要步骤,对维持井筒的稳定具有重要作用。充填浆液的选择、充填方式的选用等对充填效果都有非常大的影响。本文以信湖煤矿中央风井井壁为例,介绍了充填的基本原理和详细的充填步骤,对以后井壁壁后充填具有指导作用。     

钢纤维混凝土特性及其井壁结构试验研究

通过对不同钢纤维掺量的混凝土试块进行力学特性研究,其中采用劈裂法和套筒致裂法对钢纤维混凝土试件抗拉强度的分布特征进行分析,并对比普通混凝土力学特征数据,反映出混凝土在抗拉强度、韧性等方面得到很大提高。通过井壁模型试验的研究,钢纤维混凝土确实是千米深井井壁支护的理想材料。     

Analysis and experimental research on a grout delivery mechanism in the remote spray lining of shafts

In this work, an analysis and experimental research on a grout delivery mechanism in the lining of shafts has been accomplished. The dynamic equation of this spraying mechanism has been established and describes the system's performance properties under different conditions of viscous friction force. The analysis introduces a combined viscous damping coefficient c^* and a ratio λ between viscous friction force and inertia force. It is proved theoretically that the relative velocity of the grout is less than the implicate velocity and the emission angle α described in the paper is always larger than 45°. Numerical simulations have been performed by feeding various different parameters into the model. Meanwhile, experimental research has been carried out, in which attention has been directed towards the directional spraying function. The real rotation to impact angles have been acquired for different values of variable ξ and the running speed of the disc. The theoretical analysis and the experimental results were in agreement. Additionally, a formula for calculating the driving torque and power has been developed. This research lays the foundation for creating remote concrete spraying machines that have a directional spray capability for the lining of shafts.     

谈土钉墙与锚杆、加筋土墙的比较分析

土钉支护是近年来发展起来的用于土体开挖和边坡稳定的一种新型挡土结构,由于经济、可靠且施工快速简便,已在我国得到迅速推广和应用.在基坑开挖中,土钉支护现已成为桩、墙、撑和锚支护后又一项较为成熟的支护技术.本文对土钉及土钉墙的概念、分类以及其应用领域和适用土层进行了阐述,同时也对土钉墙和锚杆、加筋土墙的作用机理和工作性能进行了比较分析探讨,为土钉墙基坑支护方案的选择提供一定的参考.     

深部土层失水变形时土与井壁相互作用试验与理论研究

介绍了用高压直剪仪和三轴伺服仪测定大埋深土与井壁相互作用试验方法 ,得到了土与井壁相互作用剪应力 -位移曲线、单位刚度系数和强度等参数。结合试验结果 ,分析了深部土层失水变形时 ,土与井壁接触带相互作用深部为塑性浅部为弹性的变形特点。建立了土与井壁相互作用理想弹塑性分析模型 ,得到了计算井壁附加竖直位移、应变和附加应力的解析公式 ,并讨论了其随深度和深部土层压缩量等因素变化的规律。最后给出计算实例 ,说明了理论研究的实用性     

The effects of ownership,board size and board composition on the performance of Italian water utilities

This article analyses the effects of ownership, board size and composition on the performance of 72 Italian water utilities. Information about the utilities' 335 directors was collected. Our main findings indicate that private or mixed-ownership utilities show higher profitability than entirely publicly-owned firms, even if the latter are less debt-dependent. Furthermore, our results show that the boards of Italian water utilities are dominated by politically connected directors, who boost access to debt and negatively affect the firms' capital structures. This study also shows that board composition, in terms of the age and educational background of members, influences economic performance, since graduate and senior directors exert a negative influence on profitability.     

蓄热过程中非饱和土壤热湿迁移特性的数值研究

基于多孔介质传热传质理论,建立了在蓄热过程中关于非饱和土壤热湿迁移的数学模型,采用控制容积法,利用Matlab软件对模型进行了数值求解,得到了基本的传热传质机理及温湿度场间的关联性,为优化地下蓄/放热系统提供参考依据。     

A preliminary study on mercury contamination to the environment from artisanal zinc smelting using indigenous methods in Hezhang County, Guizhou, China: Part 2. Mercury contaminations to soil and crop

Artisanal zinc smelting using indigenous method in Hezhang County, Guizhou, China has posed seriously environmental pollution to the local environment. Within less than 150 km2 area in Hezhang, a few metric tons of mercury were released into the atmosphere each year since 1989 due to artisanal zinc smelting, and the surface waters were seriously contaminated with mercury. For the first time, we investigated the mercury contamination to the local soil and crop compartments due to mercury emissions from artisanal zinc smelting activities in this area. Mercury distribution patterns in 5 soil profiles collected in artisanal zinc smelting area showed that the top soils were seriously contaminated with mercury. The soils from agriculture land close to the zinc smelting areas were also contaminated with mercury due to the deposition of mercury species that emitted from artisanal zinc smelting processes. Total mercury concentrations in top soils decrease exponentially with distance from the zinc smelting area. Corn plants that were cultivated in agriculture land close to the zinc smelting area were also contaminated with mercury. Mercury concentration in corn plant tissue increased in the order of grains相似文献