龙井茶冲泡下沉特征及加工工艺对外形品质和下沉速度的影响

为解决目前市场上部分龙井茶冲泡后下沉慢的问题,文章研究了龙井茶冲泡后下沉规律、影响茶叶下沉的物理因素及加工工艺对其外形品质和下沉速度的影响。结果表明,龙井茶沸水冲泡后静置过程中,芽叶集中下沉时间点能够作为茶叶下沉速度的衡量标准。茶条宽度及长宽比是影响龙井茶下沉的重要物理因素,手工龙井茶外形较窄、下沉快,芽叶集中下沉时间点在90~200 s间;机制龙井茶外形相对宽扁,茶条最宽幅度宜控制在0.55 cm以内,长宽比控制在4.0~6.0之间的龙井茶,其下沉速度较快,芽叶集中下沉时间点小于290 s;茶条最宽幅度大于0.6 cm,长宽比小于4.0的产品下沉速度慢。加工过程中青锅及精制能够显著影响茶条规格,其中青锅工序中注重压力控制,轻压杀青后逐步加压做形,控制好压力差,适当延长做形时间,可以形成龙井茶扁平、挺直、光滑、嫩绿油润的良好风格;精制能明显提高外形的美观度,加快冲泡过程中的下沉速度。

Inversion and Prediction of Consolidation Settlement Characteristics of the Fluvial Sediments Based on Void Ratio Variation in the Northern Modern Yellow River Subaqueous Delta, China

The modern Yellow River delta is formed near the estuary of the Yellow River with the characteristics of short formation time, efficient sedimentation rate and loose structure which make sediments prone to be compacted and consolidate under the geostatic stress and overburden stress. It is one of the key areas with land subsidence disasters in China, bringing a series of safety hazards to production and living. Based on the data of massive surface cores and ten drill holes ranging from 12 to 40 m obtained from the northern modern Yellow River subaqueous delta, the inversion method suitable for the calculation of consolidation settlement characteristics of the modern Yellow River subaqueous delta is discussed, and the consolidation settlement characteristics of the delta sediments are inversed and predicted in this paper. The actual void ratio of the delta sediments at the depth from 3 to 15 m shows a significant power function relationship with the depth, while the void ratio of the sediments below 15 m changes little with depth. The pre-consolidation settlement(from deposition to sampling) of the delta sediments is between 0.91 and 1.96 m, while the consolidation settlement of unit depth is between 9.6 and 14.0 cm m^(-1). The post-consolidation settlement(from sampling to stable) of the subaqueous delta sediments is between 0.65 and 1.56 m in the later stage, and the consolidation settlement of unit depth is between 7.6 and 13.1 cm m^(-1) under the overburden stress. The delta sediments with a buried depth of 3 to 7 m contribute the most to the possible consolidation settlement in the later stage.

Petroleum Hydrocarbon Distribution Features in Water and Sediment off Fujian Shore

This study on the distribution features of petroleum hydrocarbon in water and sediment off the Fujian shore using data obtained from the baseline research on oceanic contamination in Fujian showed that: during the research period, petroleum hydrocarbon concentrations in water varied from 5.77 μg/L to 37.28 μg/L, averaged 14.48 μg/L; was lower in the wet season than in the dry season; and was highest in the Minjiang Estuary and Jiulong Estuary in both seasons. The petroleum hydrocarbon concentrations in shore sediment varied from 14.48 mg/kg to 784.36 mg/kg, averaged 133.3 mg/kg, and was closely related to sediment types (granularity).

巨厚松散层下煤层开采地表移动规律研究

为了研究巨厚松散层下采煤对地表沉陷的影响,以赵家寨煤矿地表移动观测数据为基础,研究了巨厚松散层地质采矿条件下采煤对地表沉降特征、地表最大下沉速度、地表最大下沉速度滞后距以及地表不同阶段移动持续时间的影响,结果表明在巨厚松散层条件下开采,地表下沉系数偏大,接近于1,主要影响角正切值偏小,地表移动范围较大,拐点偏移距较小,地表最大下沉速度滞后距较小,最后得出在巨厚松散层下开采,地表显现出下沉速度加快,活跃期延长而衰退期缩短,地表残余变形减小并且稳定快等特征。

The Settlement Characteristic of Underground Urban Complex in Shanghai

The effects of excavation unloading, construction reloading and underground water on basal heave of excavation projects were presented and analyzed based on the measurement results of an underground urban complex which was located in Shanghai. The effects on water pressure and building settlements were analyzed as well. The numerical analyses by finite element method (FEM) were conducted. It showed that the soil under the excavation base continued to heave during the following certain construction stage. It also found that the bearing capacity of uplift piles which supported the buildings affected the structure quality significantly. The conclusions can be applied in future projects.

Mechanisms of suspended sediment restoration and bed level compensation in downstream reaches of the Three Gorges Projects(TGP)

River basin reservoir construction affects water and sediment transport processes in downstream reaches. The downstream impact of the Three Gorges Projects （TGP） has started to become apparent： （1） reduction in flood duration and discharge, and significant reduction in sediment load. Although there was some restoration in downstream sediment load, the total amount did not exceed the pre-impoundment annual average; （2） in 2003-2014 the d 〉 0.125 mm （coarse sand） load was restored to some degree, and to a maximum at Jianli Station, which was mainly at the pre-impoundment average. After restoration, erosion and deposition characteristics of the sediment was identical to that before impoundment. The degree of restoration during 2008-2014 was less than during 2003-2007; （3） after TGP im- poundment, there was some restoration in d 〈 0.125 mm （fine sand） sediment load, however, it was {ower than the pre-impoundment average; （4） due to riverbed compensation, the d 〉 0.125 mm sediment load recovered to a certain degree after impoundment, however, the total did not exceed 4400x104 t/y. This was mainly limited by flood duration and the average flow rate, and was less affected by upstream main stream, tributaries, or lakes. Restoration of d 〈 0.125 mm suspended sediment was largely controlled by upstream main stream, tributaries, and lakes, as well as by riverbed compensation. Due to bed armoring, riverbed fine suspended sediment compensation capability was weakened; （5） during 2003-2007 and 2008-2014, Yichang to Zhicheng and upper Jingjiang experienced coarse and fine erosion,lower Jingjiang experienced coarse deposition and fine erosion, Hankou to Datong had coarse deposition and fine erosion, and Chenglingji and Hankou was characterized by coarse deposition and fine sand erosion in 2003-2007, and coarse and fine erosion in 2008-2014. This difference was controlled by flood duration and number at Luoshan Station.