Mitigation of floor heave in West Kentucky Coal Mine

A West Kentucky mine operation in No. 11 seam encountered floor heave, due to the localized increase in the thickness of the fireclay mine floor. Floor heave has overridden seals installed in two mined out panels. The third seal's location was planned for isolating that area from the Mains. A plan of support has been developed to prevent repetition of the floor heave and related problems outby the seals. The applied ground control measures were successful. An attempt of a 3D numerical modeling was made; thus, it would match the observed behavior of the mine floor and could be used as a design tool in similar conditions. The paper describes sequence of events, an applied mitigation ground control system, and the first stage of numerical modeling.     

Support technology of deep roadway under high stress and its application

Roadway instability has been a major concern in the fields of mining engineering. This paper aims to provide practical and efficient strategy to support the roadways under high in-situ stress. A case study on the stability of deep roadways was carried out in an underground mine in Gansu province, China. Currently,the surrounding rock strata is extremely fractured, which results in a series of engineering disasters, such as side wall collapse and severe floor heave in the past decades. Aiming to solve these problems, an improved support method was proposed, which includes optimal bolt parameters and arrangement, floor beam layout by grooving, and full length grouting. Based on the modeling results by FLAC3D, the new support method is much better than the current one in terms of preventing the large deformation of surrounding rock and restricting the development of plastic zones. For implementation and verification, field experiments, along with deformation monitoring, were conducted in the 958 level roadway of Mining II areas. The results show that the improved support can significantly reduce surrounding rock deformation, avoid frequent repair, and maintain the long-term stability of the roadway. Compared to the original support, the new support method can greatly save investment of mines, and has good application value and popularization value.     

采空区底板底臌测量技术的研究

将"隐蔽工程中点位高程动态测量装置"应用于采空区内底板岩层底臌测量.结合采区内的环境条件,分析了采空区温度升高造成测量装置内的液态水膨胀,仪器布置中存在的观测管内液体蒸发,连接管路变形等因素产生的测量误差来源,并考虑相应措施进行处理.分析结果表明,测量装置内的水膨胀无法忽略,当采空区遗煤无自燃倾向时,在20℃温差影响下,通过调整仪器参数,底板岩层底臌值测量误差可以控制在3~4 mm.经采场实地测量可知,该仪器可以承受采空区内复杂环境的影响,能够测得底板岩层的底臌值.     

淮南顾桥矿东风井人工冻土力学性能试验分析

淮南顾桥煤矿东风井采用冻结法施工,为了提供表土层冻结参数以进行矿井设计,本文对风井井筒孔检查孔所取土样进行了人工冻结的单轴抗压强度、冻胀性能以及结冰温度试验研究,得到了其应力-应变、冻胀力和结冰温度等参数,试验结果为淮南类似矿井建设提供了设计基础.     

软土基坑支护深度滑移线解研究

基于滑移场理论,分析了基坑底部被动滑移区BDE、过渡区BCD和主动滑移区ABC的区域应力状态,推算出基坑底部在假设支护深度为t时的土体极限承载力滑移线解,并以此反算出满足软土基坑抗隆起稳定安全性要求的支护深度。此外,还可求出软土基坑抗隆起稳定性安全系数以应用于抗隆起稳定性验算,并且在均质土前提下,经过简单换算得到与普朗德尔极限平衡理论公式的基坑抗隆起稳定性安全系数k相同的结果。结合工程实例验证了软土基坑支护深度滑移线解和软土基坑抗隆起稳定性安全系数的合理性。     

表面特性对结霜和融霜排液的影响

对亲水表面、裸铝表面和疏水表面上结霜和融霜排液过程进行实验研究,分析了表面特性对冷凝水珠冻结、霜层生长和融霜排液的影响。结果表明：疏水表面上冷凝水珠呈规则球缺状、冻结较晚,而亲水表面和裸铝表面上冷凝水珠形状不规则;相比于亲水表面和裸铝表面上平整霜层,疏水表面上霜层不平整,有凹穴和凸起;疏水表面上霜层平均厚度增长较亲水表面和裸铝表面缓慢;在湿空气温度和冷面温度较低的情况下,表面特性对霜层生长的影响减弱;亲水表面具有较好的排液效果,其循环再结霜量最小。     

茂名矿区巷道底臌实测与分析

通过茂名矿区软岩巷道底臌变形实测结果的分析，说明巷道底胶变形受两帮围岩下沉的影响。茂名矿区的底胶变形由两帮岩柱传递顶板压力开始，在挤压底板的同时和岩帮一起下沉，底板受严重压缩变形后破裂并臌起。提出了用实测参数估计底臌变形各分量的方法，估算结果和实际很接近。并根据底臌变形过程提出了防治底胶的基本原则，这些原则在治理茂名软岩巷道底臌中得到证实。     

季冻区公路路基粗粒土的冻胀敏感性及分类研究

对5种粗粒土13种不同含泥量土料在不同含水率、饱和度和密实度状态下进行了一系列封闭系统下的冻胀模拟试验。研究了各种粗粒土的η-w关系,并对其进行线性分析,揭示了粗粒土的冻胀规律。根据所建立的各种不同粗粒土的η-w经验关系式得出各种土料以及粗粒土的相应于不同冻胀等级和类别的界限含水率值,并与现有的规范进行对比,指出规范值得商榷的问题。     

混凝土抗冻性试验方法及评价参数的研究评述

本文主要阐述了混凝土冻融破坏的机理，国内外混凝土抗冻性试验方法,评价参数及影响混凝土的抗冻性试验方法的因素.分析结果表明在除冰盐存在的情况下大大加剧了混凝土的冻融破坏。影响这些试验方法的因素为：试件与传热介质的接触方式；传热介质的种类和浓度；冻融循环制度。通过试件单位面积的剥蚀量和动弹性模量的损失更能准确、全面地反映混凝土的抗盐冻性能，并建议在我国应建立适合道路和桥梁的单面盐冻试验方法。