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针对搅拌桩施工会引起周围土体的位移及产生很高的超静孔隙水压力的工程现象,首先分析了搅拌桩施工中固化剂的注入体积与膨胀压力、成桩直径的关系。结果表明,5%~10%的注入浆液的体积可以对周围土体产生1.8~3.0倍不排水抗剪强度的膨胀压力,成桩直径比搅拌叶片的名义直径大5%~10%。然后量测室内模型桩、现场搅拌桩的成桩直径,分析了注入浆液的体积与成桩直径的关系。结果表明,对于深度不太大的水泥土搅拌桩,有约45%的注入体积会通过上浮隆起的土体损失掉;大约5%的注入体积通过劈裂裂缝渗入到周围土体中;大约50%的注入体积会转化为成桩直径,使桩体膨胀5%~10%,即实测桩径比搅拌叶片的名义直径大5%~10%。 相似文献
97.
大气环境影响评价工作分级要求要点 总被引:1,自引:0,他引:1
根据大气环境影响评价工作的分级要求,提出了针对性的工作要点,以满足大气环境评价工作的需要. 相似文献
98.
Jennifer E. Kay Stephanie K. Kampf Rebecca N. Handcock Keith A. Cherkauer Alan R. Gillespie Stephen J. Burges 《Journal of the American Water Resources Association》2005,41(5):1161-1175
Emitted thermal infrared radiation (TIR, λ= 8 to 14 μm) can be used to measure surface water temperatures (top approximately 100 μm). This study evaluates the accuracy of stream (50 to 500 m wide) and lake (300 to 5,000 m wide) radiant temperatures (15 to 22°C) derived from airborne (MASTER, 5 to 15 m) and satellite (ASTER 90 m, Landsat ETM+ 60 m) TIR images. Applied atmospheric compensations changed water temperatures by ?0.2 to +2.0°C. Atmospheric compensation depended primarily on atmospheric water vapor and temperature, sensor viewing geometry, and water temperature. Agreement between multiple TIR bands (MASTER ‐ 10 bands, ASTER ‐ 5 bands) provided an independent check on recovered temperatures. Compensations improved agreement between image and in situ surface temperatures (from 2.0 to 1.1°C average deviation); however, compensations did not improve agreement between river image temperatures and loggers installed at the stream bed (from 0.6 to 1.6°C average deviation). Analysis of field temperatures suggests that vertical thermal stratification may have caused a systematic difference between instream gage temperatures and corrected image temperatures. As a result, agreement between image temperatures and instream temperatures did not imply that accurate TIR temperatures were recovered. Based on these analyses, practical accuracies for corrected TIR lake and stream surface temperatures are around 1°C. 相似文献
99.
随着页岩气平台井工厂化压裂施工启动,在大排量、高压力、长时间施工条件下,高压管汇失效爆裂大幅增加。为减少高压管汇在压裂过程中失效爆裂风险,运用故障假设、因果分析法从人的因素、物的因素、技术工艺、生产管理、工作环境5个方面分析事故的原因,提出了提升采购产品质量、修订完善高压管汇使用技术规范和管理制度、实施专业化管理、应用大数据管理高压管汇、优化现场地面高压管汇流程分配布局设计与联接工艺等高压管汇失效爆裂风险预防控制措施和失效后应急安全防护措施,建立了生命周期全过程、专业化的高压管汇失效爆裂防控与应急防护体系,实现风险可防受控。为页岩气压裂作业的安全提供了参考。 相似文献
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The inhibition effect of heptafluoropropane (CF3CHFCF3) on methane explosions under different inhibitor concentrations in a closed vessel was studied. A high-speed camera and a pressure sensor were adopted respectively to record flame propagation characteristics and pressure data. Results indicate that the relationship between flame propagation and pressure rising was correlated. As the equivalent ratio (ϕ)≤1, the pressure presented a trend of rising firstly and then decreasing with increasing CF3CHFCF3 concentration, and it was found that there existed a critical concentration for pressure decrease. As ϕ > 1, the pressure exhibited a decreasing trend. Although the pressure appeared to seemingly increase, the moment that the pressure began to rise (trise) and the moment that the maximum explosion overpressure appeared (tPmax) were obviously delayed. The average rate of pressure rise ((dP/dt)ave) was decreased as the concentration of CF3CHFCF3 increased. It indicates that CF3CHFCF3 can effectively reduce the explosion reaction rate. The critical concentration of CF3CHFCF3 for complete inhibition was determined. Meanwhile, the synergy of CF3CHFCF3-inert gas can improve the inhibition effect. Compared with CF3CHFCF3–N2, the synergy of CF3CHFCF3–CO2 presented a better inhibition effect, and the inhibition effect was increased with increasing inert gas concentration. And the mechanisms of physical and chemical effects on explosion inhibition were analyzed. 相似文献