石家庄泄洪渠河道生态设计

石家庄位于河北省西南部,太行山迎风区,海河流域子牙河系中上游山前区域,由于市区处于太行山迎风坡暴雨高值区,且河道源短流急,产流区地形坡度较大,植被稀少,洪水一旦发生,量级较大。为了彻底解决石家庄市的环境问题及城市防洪的后顾之忧,政府提出了要对泄洪渠进行全面的维修和加固。1

On the Ecological Restoration Mode of Urban Water Revetment Landscape

Urban waterfront revetment is a special zone between water and land,with high ecological,economic and aesthetic value. Waterfront revetment landscape is not only an important part of urban water and land ecosystems,but also an integral part of the city. Based on the current situation of ecological environment of waterfront revetment landscape,we come up with different ecological restoration modes for different types of revetment,to achieve the organic integration of waterfront revetment landscape and ecology.

Stable-thickness study of masonry block on the inner slope of dikes

Dike failure caused by overtopping is likely to result in major casualties and property losses.Aiming at this fact,a series of physical model experiments were conducted on stable thickness of masonry block on the inner slope of the dike.According to the erosion of block embankment with different thicknesses,the relation between the stable thickness of masonry block pitching of the inner slope and the average overtopping discharge is discussed.New equations subject to irregular waves are presented for average overtopping discharge,based upon the analysis of mean overtopping discharge and comparison of present overtopping discharge formulas at domestic and abroad.Finally,a calculation equation of the stable thickness of the dry masonry block stone of inner slope subject to irregular waves is given.In conclusion,the formula matches well with the experiment result,which is capable of functioning as an important reference for structure designs of the dike in China.

Some Problems in the Design of Breakwaters in Dayaowan Port Area

In this paper, some problems in the design of the breakwater for Dayaowan port area are described including the optimal selection of the layout plan of the breakwater; the selection of structural type of the breakwater, the concrete block type for bank protection, the reversed L-shape parapet; the elevation of the parapet; the stability test of the whole revetment; as well as wave absorbing effects of the perforated

Field Application of Mulberry Straw Arch in Ecological Bank Revetment

With the growing level of awareness and increasing demand for environmental protection,timber pile revetments with significant ecological effects have experienced increasingly wide application in China.The current timber pile revetment system has two problems:continuous dense piles have high construction costs and require large timber consumptions,while the discrete pile-bamboo fence systems have poor retaining effects.Considering these problems,an original revetment structure form is proposed:a discrete pile-mulberry straw arch structure.To investigate the mechanical properties of the mulberry straw,some mechanical tests are conducted on mulberry straw and its arch structure.It is found that the average compressive strength of mulberry straw is 2.30 MPa,the bending strength is 20.08 MPa and the shear strength is 2.99 MPa;considering the structural characteristics of arches,mulberry straw arches have a high bending strength,which affords immense potential for their application in revetment structures.Furthermore,by doing field study of the discrete timber pile-mulberry straw arch structure for bank revetment,it is found that the arch height of the mulberry straw arch changes 1.4–1.6 cm after 489 d observation.The soil settlement before the straw arch is 0.13–0.18 cm and the settlement of the pile is 0.66–0.72 mm.Compared with bamboo fence structure,the cost of using mulberry straw arch structure as revetment material can save up to 27.07%.Therefore,the discrete timber pile-mulberry straw arch has a rational and stable structure that provides effective support for protecting the riverbank and the toe of gentle slopes and effectively prevents the collapse of bank slopes in the rear.The new revetment structure proposed in this paper has signifi-cant ecological and economic effects,is easy to construct and feasible for standard production,and consequently has great application potential.

Waterfront Revetment in Yaodu Town, Qingbaijiang District, Chengdu

With the advancement of urban-rural integration, township waterfront functioning as urban waterfront is increasingly emphasized by people. Township waterfront is expected to not only meet the basic needs of urban waterfront in landscape, but also give consideration to both leisure tourism and ecological protection. This paper analyzes the existing problems in the revetment design on the township waterfront and elaborates the importance and feasibility of constructing the ecological revetment in the traditional townships as well as design procedures. The concept of ecological design is introduced into the revetment design on the township waterfront to meet the requirements of both man and nature, so as to achieve a harmonious coexistence between man and nature and sustainable development in a real sense.

Effect of Waterscape Structures on Nitrogen and Phosphorus Removal Efficiency in Revetment Wetland System

The effect of aeration and waterscape structures reaeration system on nitrogen and phosphorus removal efficiency in revetment wetlands was studied by laboratory simulation. The results showed that the removal efficiency of TN, TP in tranquil flow waterscape was 61% and 72%; aeration and waterscape structure system promoted nitrogen and phosphorus removal efficiency in revetment wetland through increasing the DO content in the water, compared with system without artificial oxygen, the removal efficiency of TP in waterscape structures increased by 11. 6%-19. 1%, and that of TN increased by 10.5%-16. 1%; meanwhile, disturbance brought by the waterscape structure systems enhanced the adsorption of TP and flocculation effect; in addition, nitrification was confirmed as the main control step of TN removal in revetment wetland system.

Geo-textile in Riverbank-Embankment Protection from Flood Flow Erosion

Bank erosion of rivers, e.g. Bagmati, Burhi Gandak, Kosi and Kamla-Balan, all originating in the Himalayan hills of Nepal and flowing throughthe alluvial plains of North Bihar, is a chronic and common phenomenon.Cutting and deposition result in shifting or meandering of the riverendangering the embankment, road, bridge, barrage, and countryside.Anti-erosion and maintenance require huge investment. The river Kamla-Balan faces bank erosion throughout its embanked length, but stretchesat km 37 and 62 are highly unstable and vulnerable. This paper dealswith the problem, presents the hydrological details responsible for thehazard, and demonstrates the effectiveness of supplementary geo-textilewith conventional sand filter pitching to protect the soil and slope of theriverbank. Estimated flood discharge and velocity at 100 years of returnperiod is nearly 2100 cumecs and 0.9 m/sec, respectively. Riverbed andbank material is represented by silt with d50 of 0.018 to 0.05 mm while0.02 mm of silt may get eroded and transported by flow above 0.15 m/s. Launching apron is also required due to local scour. Model study testshows its suitability under various hydraulic conditions. Study reveals theeffectiveness of woven type geo-textile reinforced revetment irrespective ofcost and environmental consideration.

Numerical optimization on differential adjusting measures for asymmetrical degenerated warm permafrost railway embankment

Affected by climate warming and shady–sunny slope effect,the permafrost foundation under the railway is undergoing a significant asymmetric degradation process;research on the corresponding regulating or strengthening measures is urgently needed.Based on a well developed of numerical model,we analyzed the‘thermal repair’effect of three redesigned differential thermal reinforcement on the partially degraded permafrost embankment with steps.The results show that,when used as a strengthening measure,the method of laying crushed rock revetment(CRR)with different thicknesses on the sunny and shady slopes cannot completely eliminate the residual warm permafrost regions formed in the previous thermal erosion.When the TCRR scheme is adopted for reinforcement,although horizontal region from the evaporation section of thermosyphones(TPCTs)to the right side of the embankment is remarkably cooled,permafrost under the sunny slope is still deteriorating.In the long run,both ETCRR and TCECRR reinforcement schemes can produce a large range of‘cold core’right below the whole embankment.However,from the perspective of the simultaneous functioning range and cold storage capacity,the TCECRR scheme is signally more efficient.The thermal insulation materials in the above composite strengthening measures can not only resist the heat input in the warm season,but also improve their working efficiency by maintaining the temperature difference between the evaporation section of the heat pipe and the external environment in cold season.The addition of crushed rock revetment in TCECRR has played its thermal semiconductor effect and further improved the comprehensive thermal repair efficiency of the composite measures.

Cooling effect of ballast revetment on the roadbed of Qinghai-Tibetan Railway

The data obtained through the roadbed surface thermal regime experiment (ROBSTREX), which was carried out at Beiluhe test section of Qinghai-Tibetan Railway from October to December in 2002, were used to estimate the cooling effect of ballast revetment on the roadbed. The results show that both riprap rock ballast revetment and crushed stone ballast revetment can reduce the temperature of the roadbed. But the cooling effect of riprap rock ballast revetment is better than that of crushed stone ballast revetment when the temperature of roadbed is higher. The cooling effect of crushed stone ballast revetment is better than that of riprap rock ballast revetment when the temperature of the roadbed is lower, especially at deeper roadbed layers. In the frozen season, the heat release from the roadbed also shows that the cooling effect of ballast revetment on the roadbed is obvious, and the cooling effect of crushed stone-ballast revetment on the roadbed is much evident than that of riprap rock ballast revetment.

Strengthening effect of crushed rock revetment and thermosyphons in a traditional embankment in permafrost regions under warming climate

The embankment of the Qinghai-Tibet Railway(QTR)has been experiencing severe problems due to permafrost degradation,especially in warm and ice-rich permafrost regions.Based on ground temperature and deformation data of the embankment at location K1497+150 of the QTR in 2006-2018,the thermal regime and deformation process were analysed.The results showed that 1)the degradation rate of permafrost under the embankment was faster than that under the natural site without engineering construction,and 2)the deformation rate of the embankment had exceeded the safety range for the QTR embankment before adopting mitigative measures.In addition,this study evaluated the cooling effect on the underlying permafrost and working mechanism of two strengthening measures.Two measures,crushed rock revetment(CRR)and thermosyphons,were adopted to protect the underlying permafrost from continual degradation.The individual cooling effect of the CRR was not as good as that of the thermosyphons.However,the combination of the two could enhance the protective effects of each on the underlying permafrost,effectively cooling the permafrost and improving the stability of the embankment.

Numerical study on the influence of geometrical parameters on natural convection cooling effect of the crushed-rock revetment

The crushed-rock revetment, considered as a highly porous medium, is often applied to embankment slope to protect the underlying permafrost and ensure the thermal stability of roadway in permafrost regions. In this paper, in order to increase and optimize the cooling capacity of crushed-rock revetment in cold regions roadway engineering, based on the thermal convection theories, the practical geometry and the temperature characteristics of in-situ crushed-rock revetment, convective pattern and cooling effect of crushed-rock revetment are numerically studied, with a thickness of 1.0 m under different geometrical parameters, e.g. sloped angle and aspect ratio. The results indicate that, with a thickness of 1.0 m and a temperature difference of 10.0 ℃ between top and bottom boundaries, due to the existence of natural convection, the effective thermal conductivity of crushed-rock revetment can be increased and the thermal "semi-conductor" characteristics are endowed. However, the convective pattern changes with the variation of the sloped angle, namely, with the increase of the sloped angle, the convection cell number decreases; furthermore, when the flow changes from various cells to a single cell at a sloped angle, the Nu number is the smallest and the cooling effect is the worst, therefore, the corresponding sloped angle is considered as the worst cooling sloped angle. Besides, with the increase of the aspect ratio, the worst cooling sloped angle increases and tends to 32°, also approaching to the in-situ crushed-rock revetment angle 33.7°. Therefore, when the crushed-rock revetment em-bankment is too high, that is to say, the aspect ratio of the sloped crushed-rock revetment is too large, some measures should be taken to enhance its cooling effect, which have been researched and discussed in this paper. It is hoped that some scientific references can be supplied to the design and maintenance of the crushed-rock revetment embankment in cold regions.

Thermal and deformational repairing effect of crushed rock revetment acting as reinforcement along Qinghai–Tibet railway in permafrost regions

Due to the particularity and complexity of permafrost subgrade,research on its long-term maintenance and reinforcement under climate warming and engineering activities is of great significance.To mitigate subgrade diseases caused by thermal disturbance during the engineering construction and operation in the initial stage,the crushed-rock revetment(CRR)was additionally paved with a thickness of 1.5 m and 1.0 m on some sunny and shady shoulders of the traditional embankments along the Qinghai-Tibet railway,respectively.The improving effects for thermal and deforming stability are evaluated based on observation data of ground temperatures and embankment deformations at two sites from 2002 to 2014.The results show that a larger uplifting magnitude in the artificial permafrost table(APT),greater ground temperature decreasing amplitudes and reduction ranges of settling rate appear under the shady embankment shoulder in warm permafrost region,and both sides in the cold permafrost region when reinforcing with CRR.However,in warm permafrost region,the laying of CRR on the sunny slope of subgrade may cause considerable thermal disturbance to the underlying permafrost foundation,combined with the resulting additional stress,induce the further expansion of differential settlement.Moreover,the thermal stability strengthening effect of the CRR is closely related to the variation of the APT thickness in the earlier stage,convection intensity inside the CRR,‘cold energy reserve’in the deeper permafrost,and amount of solar radiation received by the CRR.More effective reinforcements should be implemented to alleviate the potential threaten beneath sunny embankment slope in warm permafrost regions.