Mechanism analysis of permeability based on promoting coal matrix shrinkage by water jet

High pressure pulsed water jet (HPWJ) is a new technology of effectively improving coal seam permeability. However, the mechanism of increased permeability is not yet clear, which restricts the application of HPWJ in different coal seams. From the perspective of improving permeability by coal matrix shrinkage, the impelled dynamic equations is established based on analysis of coal dynamic effects by water jet. According to theoretical analysis of the stress state of coal matrix, it is concluded that HPWJ can promote coal matrix shrinkage, and the relationship equation between jet impact-coal matrix is derived. Besides, the gas seepage function in the coal slotted by the HPWJ is gained by using PM model, which provides theoretical support for generalizing the technology in the coal mine.     

Numerical simulation of seepage field of gas extraction drilling of single bedding of mining-coal bed

Aiming at the problem of reasonable decorate of coal gas extraction drilling, combining with the initial and boundary condition of borehole extraction, the solid and gas coupling mathematical model of gas seepage of borehole extraction is deduced based on established control equations of seepage field and deformation field. Taking gas extraction of stone coal slit as an example, according to the characteristics of coal seam in the research, the numerical simulation method is used to obtain the distribution rule of gas pressure, coalbed gas permeability, and coalbed gas seepage velocity as well as seam deformation. The effective radius of gas extraction drilling of single bedding about mining-coal bed is determined, which provides the basis for optimum arrangement of gas extraction drilling of single bedding. The results show that the effective radius of stone coal is about 4 m. If the prolonging drilling drainage time is less than 20%, the drilling quantities would reduce by about 50%.     

土坝坝体防渗中劈裂灌浆技术的应用

文中阐述了土坝坝体劈裂灌浆防渗技术的机理、设计和施工要求，展现了该技术良好的推广价值。     

田埂宽度对水田无机氮磷侧渗流失的影响

对杭嘉湖地区稻田土壤氮磷侧渗流失的研究结果表明，稻田土壤侧渗流失是氮磷流失的一个重要途径。田埂对水田的无机氮磷的侧渗有明显的截留作用，且截留效果与田埂宽度及其土壤紧实度密切相关，截留效果在氮磷的不同形态上也表现出一定的差异，其中对氨氮和磷酸盐的侧渗截流作用比较明显，对硝氮的作用则较小。     

基于Hydrus-1D模型的冬小麦根系层水分渗漏分析

利用Hydrus-1D模型模拟了河北省石津灌区冬小麦水分渗漏情况。结果表明,研究区40％的灌溉降雨量和38％的总供水量流出了200cm边界层,通过设置12种方案得到初始饱和度、2次春灌水量是影响灌区渗漏的主要因素,而二水时间间隔和第一水灌水日期影响相对较小。通过设置426种方案,分别得到了不同初始饱和度时,2次春灌灌水...     

库水位升降作用对库岸滑坡稳定性的影响研究

利用了渗流场-应力场耦合的有限元法,对三峡库区某滑坡体在库水位升降作用下的渗流特征及稳定性变化规律进行了研究。结果发现,对于该滑坡体在库水位上升过程中其稳定性将有降低的趋势,而在水位上升过程中,滑坡的稳定性开始阶段下降而后逐渐上升。     

不同近地表水文条件下紫色土坡面土壤侵蚀过程研究

采用模拟降雨试验,研究了自由下渗(free drainage)、土壤水分饱和(saturation)、壤中流(seepage)3种近地面水文条件下紫色土坡面土壤侵蚀过程.结果表明,近地表水文条件会对紫色土坡面侵蚀过程产生重要影响.在地面坡度5°～15°条件下,当地表水文条件由自由下渗演变为土壤水分饱和时,坡面侵蚀量由1.31～2.02 g/(min·m2)增加到1.83～5.50 g/(min·m2);当地表水文条件由土壤水分饱和变为壤中流时,坡面侵蚀量达到4.40～16.41 g/(min·m2).土壤水分饱和条件下坡面侵蚀量是自由下渗的1.40～2.73倍;壤中流条件下坡面侵蚀量是自由下渗时的3.36～8.12倍,是土壤水分饱和时的2.40～2.98倍.同时,坡面坡度对紫色土坡面侵蚀过程有重要的影响.     

黄河大堤基础截渗工程技术比较

黄河大堤山东段防洪标准偏低。本文从堤防防渗施工方法的可行性、耐久性和经济性等几个方面对已采用的方法和可采用的方法进行了技术分析，并对黄河永久性防洪提出了几点建议。     

Analyses on Stability of Saturated-Unsaturated Bank Slope with Revetment During Rise and Fall of River Level

The bank slope failure is closely related to the rise and fall of river level generally. In order to analysis the influence of the rise and fall of river level on Jin’an River bank slope stability in Fuzhou, the saturated-unsaturated seepage of bank slope with revetment was modelled based on the engineering geological condition of some bank of Jin’an River, and the effect of rise and fall of river induced by the DRWWOS(Drawing River Water to Wash Out Sewage) project on bank slope stability was studied. The results show the silt lying on the slope toe impedes pore water change, manifesting as in its sphere of influence river water is hard to flow into the bank when river rises, and the pore water pressure can not dissipate in time when drawdown. The faster the river rises, the more stable the bank slope becomes. On the contrary, the larger river level falling rate is more likely to leads to bank slope failure. Due to the poor bank drainage performance, the frequent rise and fall of river level results in pore water pressure increasing further, then impairing the bank slope stability. During DRWWOS project, the river level falling rate control and pore water pressure dissipation must be paid enough attention to. Also, replacing silt lying on the slope toe by good permeable material is a good choice to reinforce the bank slope.     

Using an ADCP to determine canal seepage loss in an irrigation district

Seepage from earthen irrigation canals represents substantial water loss in irrigation districts. Historically, the determination of canal seepage was accomplished using the inflow-outflow method with propeller and electromagnetic type flow meters. This method was difficult, time consuming, and limited by measurement device accuracy. In recent years, advances in technology have lead to the widespread use of Acoustic Doppler Current Profilers (ADCP) for discharge measurements in streams and rivers. Even though ADCP use has become widespread for stream discharges, studies to determine canal seepage using this new technology are limited. Using an ADCP, extensive field measurements were conducted in the Middle Rio Grande Conservancy District. This paper describes the ADCP measurement protocol used to measure irrigation canal seepage and presents predictive equations for determining canal seepage based on flow rate and canal geometry.