浅析张集矿立井地面预注浆堵水效果

介绍了张集矿立井基岩段水文地质和基岩地面预注浆的有关情况。根据井简实测资料,分析基岩裂隙的发育规律、裂隙层界面的浆波充填情况、实际浆液有效扩散半径及堵水效果。认为：立井基岩地面预注浆,不仅能成功地起到堵水的自的．从而缩短工期、降低造价、提高质量,而且还有利于井筒安全揭穿突出谋层,达到安全施工。     

地下水位下降对井壁破坏的影响分析

在用“２Ｄ σ”软件对所建模型进行数值计算的基础上, 分析了因采煤引起淮北矿区下部含水层水位下降而对井壁产生的影响。其表现为： 下部含水层水位下降将引起地层压缩沉降; 地层与井壁间产生附加应力, 并在基岩下部产生应力为零的中性点; 轴向应力由小变大; 当第一含水层和下部含水层同时有水位下降时, 也有类似的规律。计算结果与淮北诸矿井壁变形位置及变化状况基本相符, 因此在此基础上进行的井筒优化设计具有实际指导意义     

Limestone Dissolution Processes in Beke Doline Aggtelek National Park,Hungary

Aggtelek National Park, Hungary, is a limestone karst upland characterized by karren, dolines and river caves. For a period of two years, climatic and carbonate dissolution variables were monitored at four depths in a 7·5 m shaft through the soil fill in the floor of a typical large (150 m diameter) doline. Results are compared to other monitoring stations in the shallow soils on side slopes. Runoff and groundwater flow are focused into the base of the doline soil fill, where moisture is maintained at 70–90 per cent field capacity and temperatures permit year-round production of soil CO₂. The capacity to dissolve calcite (limestone) ranges from c. 3 g m⁻² per year beneath thin soils on the driest slopes to 17–30 g m⁻² per year in the top 1–2 m of doline fill and at its base 5–7 m below. © 1997 John Wiley & Sons, Ltd.     

Field study of set-up effect in open-ended PHC pipe piles

Large-scale field tests were conducted to study set-up effect in open-ended prestressed high-strength concrete pipe piles jacked into stratified soil. Four open-ended prestressed high-strength concrete pipe piles with 13 and 18 m in embedment depth were fully instrumented with fiber Bragg grating sensors and installed. Several restrike dynamic tests were performed on each test pile, with the time interval from 21.5 to 284 hours after installation. Static loading tests (SLTs) were later performed on each test pile at 408 hours after installation to substantiate the dynamic tests. Changes with time in pile bearing capacity and in the shaft and toe resistances were studied based on the results of the pile tests. The development of shaft resistance set-up in different layers was studied in particular. It was found that set-up effect in the shaft resistance is significant and the toe resistance increment was minor. The overall set-up factor of total bearing capacity was found to range from 0.09 to 0.53, and the set-up effect of friction pile is much larger than the end bearing pile. More significant set-up in shaft resistance was observed in fill and alluvium layer. The dimensionless set-up factor A for shaft resistance in marine deposits ranges from 0.5 to 1.43, and it contributes the most to the shaft resistance as the shaft resistance in marine deposits is higher.     

End Bearing Capacity of Drilled Shafts in Sand: A Numerical Approach

In this paper, a modeling procedure is carried out to numerically analyze the end bearing capacity of drilled shafts in sand. The Mohr–Coulomb elastic plastic constitutive law with stress dependent elastic parameters is used for all numerical analyses performed in this study. The numerical results are compared with the available experimental equations. It is seen that numerical results are in good agreement with experimental equations. The variation of the end bearing capacity of drilled shafts versus embedment depth is also studied. Numerical results show that with increase in pile embedment depth, the end bearing capacity increases. However, the rate of increase becomes smaller as the pile embedment depth increases. Also, numerical analyses show that, for equal settlement, the end bearing decreases with increase in the pile diameter. Finally, a sensitivity analysis is performed to obtain the separate effect of each sand parameter on the end bearing capacity of drilled shafts, and the parameters that are most influential are identified.     

基于自平衡试桩法大直径嵌岩桩尺寸效应分析

基于自平衡测试技术,通过现场的原位测试方法,对大直径嵌岩桩的尺寸效应进行了研究,内容包括桩径尺寸和嵌岩深度变化以及桩端阻力尺寸效应的影响分析等。从测试结果来看,嵌岩桩也存在一定程度的尺寸效应现象。当其他条件一定时,随着桩径的增大,桩侧阻力存在着减小现象;在同一种岩层的情况下,随着嵌岩深度的增大,桩侧阻力发挥也并不相同,嵌岩深度越大,桩侧阻力发挥也越小。实测结果表明,桩周岩石的特性变化对桩侧阻力影响最大,岩石抗压强度越高,桩侧阻力也越大。此外,桩径的变化对桩端阻力的影响更为明显。因此,在大直径嵌岩桩的设计中应注意尺寸效应对桩基承载力的影响。     

On behavior of load transfer for drilled shafts embedded in weak rocks

This study deals with the formulation of an analytical solution for load transfer in drilled shaft and its application. The emphasis is on quantifying the mobilization of side resistances, which are closely related to shear behaviors of the concrete-rock interface. In this modelling, the side resistance is idealized by using elasticity-brittleness-plasticity, and a simple slip-line field is built to identify the critical shear displacement. The closed-form solution of load transfer is obtained by using the proposed shear model. Comparison between predictions and field observations is also made to validate performance of the proposed method.     

采用空气潜孔锤钻进技术在井筒内施工泄水孔实践

袁店一井煤矿风井井筒基岩段施工中遇工作面大量涌水,排水能力无法满足掘砌需要。为保证井筒掘砌施工安全,提出施工钻孔直达风巷的方法进行快速泄水,但已无法进行传统泥浆钻进。通过采用长距离悬空钻杆结合空气潜孔锤钻进技术以及孔口管的安装等施工工艺和措施,有效解决了岩粉上返、水压过大、钻杆摆动等施工技术难题,快速地完成了泄水孔的施工,成功将井筒基岩段涌水排入井下水仓,从而确保了井筒的安全和快速施工。     

沂源鲁村煤矿千米混合立井围岩稳定性分析与施工措施

基于沂源鲁村煤矿围岩稳定性差,塑性变形量大的实际情况,采用弹塑性力学分析的方法,分析了鲁村煤矿千米混合立井岩石开挖后围岩应力重新分布情况和塑性变形,进而确定是否采用临时支护措施,以确保施工安全。研究表明鲁村煤矿混合井围岩掘进深度大于780 m时,围岩变得不稳定,需要施加锚喷临时支护,同时增加井筒掘进荒断面,预留围岩变形空间。     

竖井内爆炸动力响应分析

系统地分析了内爆炸条件下冲击波在竖井内的传播和反射规律,并基于经典弹性理论,建立了动力平衡方程,推导出了竖井井壁动力响应的计算表达式,得到了竖井侧墙最大径向位移和最大内力分布。计算表明：竖井侧墙最大径向位移出现在竖井中间的某处位置,具体与点源爆炸物高度有关,随着爆炸高度的增加,最大径向位移出现的位置也在向井口方向移动,但是幅值大小有所减小。