Dynamic shear modulus of undisturbed soil under different consolidation ratios and its effects on surface ground motion

The dynamic shear modulus for three types of undisturbed soil under different consolidation ratios is presented by using the resonant column test method. Its effects on surface ground motion is illustrated by calculation. The test results indicate that the power function is a suitable form for describing the relationship between the ratio of the maximum dynamic shear modulus due to anisotropic and isotropic consolidations and the increment of the consolidation ratio. When compared to sand, the increment of the maximum dynamic shear modulus for undisturbed soil due to anisotropic consolidation is much larger. Using a one-dimensional equivalent linearization method, the earthquake influence factor and the characteristic period of the surface acceleration are calculated for two soil layers subjected to several typical earthquake waves. The calculated results show that the difference in nonlinear properties due to different consolidation ratios is generally not very notable, but the degree of its influence on the surface acceleration spectrum is remarkable for the occurrence of strong earthquakes. When compared to isotropic consolidation, the consideration of actual anisotropic consolidation causes the characteristic period to decrease and the earthquake influence factor to increase.

Analysis and improving ways for water condition in winter wheat field of dryland in subhumid areas of the Loess Plateau

Based on the soil moisture data from the locating experiments from 1986—1990, and using the water balance method, the water supply and demand state in the field of winter wheat, and the ways for improving water condition in dryland of dry subhumid area of the Loess Plateau were studied. The results suggested that a low precipitation satisfying ratio of 42.9%—58.8% appears in the growing period of winter wheat, and the yield, to a great extent depended on the water that was stored in deep soil layer in the previous rainy season. The filed trial results showed that tillage in the summer fallow period,straw cover, soil moisture regulation with adequate fertilization, crop rotation and proper cropping system could be the efficient ways for improving the water condition,and for the exploitation and utilization of natural water resources(both precipitation and soil water) in the winter wheat field of dryland.

Phenotypic plasticity of Artemisia ordosica seedlings in response to different levels of calcium carbonate in soil

Plant phenotypic plasticity is a common feature that is crucial for explaining interspecific competition, dynamics and biological evolution of plant communities. In this study, we tested the effects of soil CaCO_3(calcium carbonate) on the phenotypic plasticity of a psammophyte, Artemisia ordosica, an important plant species on sandy lands in arid and semi-arid areas of China, by performing pot experiments under different CaCO_3 contents with a two-factor randomized block design and two orthogonal designs. We analyzed the growth responses(including plant height, root length, shoot-leaf biomass and root biomass) of A. ordosica seedlings to different soil CaCO_3 contents. The results revealed that, with a greater soil CaCO_3 content, A. ordosica seedlings gradually grew more slowly, with their relative growth rates of plant height, root length, shoot-leaf biomass and root biomass all decreasing significantly. Root N/P ratios showed significant negative correlations with the relative growth rates of plant height, shoot-leaf biomass and root length of A. ordosica seedlings; however, the relative growth rate of root length increased significantly with the root P concentration increased, showing a positive correlation. These results demonstrate that soil CaCO_3 reduces the local P availability in soil, which produces a non-adaptive phenotypic plasticity to A. ordosica seedlings. This study should prove useful for planning and promoting the restoration of damaged/degraded vegetation in arid and semi-arid areas of China.

Estimation of soil reinforcement by the roots of four postdam prevailing grass species in the riparian zone of Three Gorges Reservoir, China

Soil erosion and bank degradation is a major post-dam concern regarding the riparian zone of the Three Gorges Reservoir. The development and succession of vegetation is a main countermeasure,especially to enhance bank stability and mitigate soil erosion by the root system. In this study, the roots of four prevailing grass species, namely, Cynodon dactylon, Hemarthria altissima, Hemarthria compressa, and Paspalum paspaloides, in the riparian zone were investigated in relation to additional soil cohesion. Roots were sampled using a single root auger. Root length density（RLD） and root area ratio（RAR） were measured by using the Win RHIZO image analysis system. Root tensile strength（TR） was performed using a manualdynamometer, and the soil reinforcement caused by the roots was estimated using the simple Wu＇s perpendicular model. Results showed that RLD values of the studied species ranged from 0.24 cm/cm3 to20.89 cm/cm3 at different soil layers, and RLD were significantly greater at 0–10 cm depth in comparison to the deeper soil layers（＆gt;10 cm）. RAR measurements revealed that on average 0.21% of the reference soil area was occupied by grass roots for all the investigated species. The measured root tensile strength was the highest for P. paspaloides（62.26MPa） followed by C. dactylon（51.49 MPa）, H.compressa（50.66 MPa）, and H. altissima（48.81MPa）. Nevertheless, the estimated maximum root reinforcement in this investigation was 22.5 k Pa for H.altissima followed by H. compressa（21.1 k Pa）, P.paspaloides（19.5 k Pa）, and C. dactylon（15.4 k Pa） at0–5 cm depth soil layer. The root cohesion values estimated for all species were generally distributed at the 0–10 cm depth and decreased with the increment of soil depth. The higher root cohesion associated with H. altissima and H. compressa implies their suitability for revegetation purposes to strengthen the shallow soil in the riparian zone of the Three Gorges Reservoir. Although the soil reinforcement induced by roots is only assessed from indirect indicators, the present results still useful for species selection in the framework of implementing and future vegetation recovery actions in the riparian zone of the Three Gorges Reservoir and similar areas in the Yangtze River Basin.

Zokor activity promotes soil water infiltration in the Mu Us sandy land of northern Shaanxi,China

Zokors are common subterranean rodents that inhabit agricultural fields, shrublands, and grasslands in the arid and semi-arid regions of China. Zokor burrowing activities can alter soil structure and affect soil hydrological processes;however, there are few studies regarding their effects on soil preferential flow in the Mu Us sandy land. An evaluation of the effects of zokor disturbance on their habitat and soil water is important for understanding the ecological role of zokors in the soil ecosystem of the Mu Us sandy land. A field dye-tracing experiment was conducted in the Gechougou watershed on the southeastern edge of the Mu Us sandy land to investigate the effect of zokor burrowing activity on soil preferential flow characteristics. Our results showed that the density of zokor tunnels was the highest(0.40–0.46 m m^(-2)) under 30%–50% vegetation coverage and that the tunnels were approximately 3 cm from the surface.Both stained area ratio and stained path number were higher at sites with zokors than without zokors. Stained path widths were 10–80 and > 80 mm at zokor-harboring sites exhibiting homogeneous flow and heterogeneous finger flow, respectively. In the absence of zokors, homogeneous flow and highly interacted macropore flow were predominant. Soil water content below the zokor tunnels was higher than that above the tunnels. Moderate disturbance of soil structure by zokor activity facilitated soil water infiltration. These results enabled a better understanding of the effect of soil fauna on soil structure and hydrological processes and provided recommendations for ecological construction and renovation in arid and semi-arid regions.

Numerical computation of anti-liquefaction effect of lattice-type cement-mixed soil countermeasure

Continuous soil-cement wall confinement method to resist liquefaction is a new kind of process. However, whether it also has a good effect on anti-liquefaction or not needs to be urgently answered for earthquake engineering. Quiet boundary is adopted on the lateral face while free field boundary is employed at the bottom. Byrne model on dynamic pore water pressure generation is accepted and natural seismic wave EI Centro whose peak acceleration is adjusted to 0.2 g in proportion is used for input. A double-layer foundation with sandy soil in the upper portion while clay soil in the lower part is chosen as the calculation model, which is 30 m in length and 20 m in width. The groundwater level is on the ground surface. Excess pore water pressure rate is considered as a liquefaction index in the three-dimensional non-linear earthquake response computation. The anti-liquefaction effectiveness and its influencing factors, such as confinement element area are studied. For the natural double-layer foundation, it is liquefied when the excess pore water pressure rate reaches 1.0 under the seismic load. Under the same earthquake load, the peak excess pore water pressure reduces to 0.56 after adopting reinforcement of the continuous soil-cement wall, which is 46% lower than before. It indicates that continuous soil-cement wall confinement method can attain the purpose of anti-liquefaction. Accordingly, it can be a sort of engineering measure to carry on the anti-liquefaction foundation treatment.

Experimental study on the seismic behavior of high strength concrete fi lled double-tube columns

To study the seismic behavior of high strength concrete fi lled double-tube(CFDT) columns,each consisting of an external square steel tube and an internal circular steel tube,quasi-static tests on eight CFDT column specimens were conducted.The test variables included the width-to-thickness ratio(β1) and the area ratio(β2) of the square steel tube,the wall thickness of the circular steel tube,and the axial force(or the axial force ratio) applied to the CFDT columns.The test results indicate that for CFDT columns with a square steel tube with β1 of 50.1 and 24.5,local buckling of the specimen was found at a drift ratio of 1/150 and 1/50,respectively.The lateral force-displacement hysteretic loops of all specimens were plump and stable.Reducing the width-to-thickness ratio of the square steel tube,increasing its area ratio,or increasing the wall thickness of the internal circular steel tube,led to an increased fl exural strength and deformation capacity of the specimens.Increasing the design value of the axial force ratio from 0.8 to 1.0 may increase the fl exural strength of the specimens,while it may also decrease the ultimate deformation capacity of the specimen with β1 of 50.1.

Soil fixation and erosion control by Haloxylon persicum roots in arid lands, Iran

Vegetation roots contribute to soil fixation and reinforcement, thus improving soil resistance against erosion. Generally, the amount of soil fixation presented by roots mainly depends on root density and tensile strength. In the present study, we conducted the research in order to further understand the biotechnical properties of Haloxylon persicum and also to quantify its role in increasing soil cohesion in arid lands of Iran. Ten H. persicum shrubs were randomly selected for root distribution and strength investigations, in which five samples were set on flat terrain and other five samples on a moderate slope terrain. The profile trench method was used to assess the root area ratio(RAR) as the index of root density and distribution. Two profiles were dug around each sample, up and downslope for sloped treatment and north and south sides for flat treatment. The results showed that RAR increased with increasing soil depth and significantly decreased in 40–50 cm layers of downhill(0.320%) and 50–60 cm for uphill(0.210%). The minimum values for the northward and southward profiles were 0.003% and 0.003%, respectively, while the maximum values were 0.260% and 0.040%, respectively. The relationship between the diameter of root samples and root tensile strength followed a negative power function, but tensile force increased with increasing root diameter following a positive power function. The pattern of increased cohesion changes in soil profile was relatively similar to RAR curves. The maximum increased cohesion due to the presence of roots in uphill and downhill sides were 0.470 and 1.400 kPa, respectively. In the flat treatment, the maximum increased cohesions were 0.570 and 0.610 kPa in northward and southward profiles, respectively. The analysis of variance showed that wind and slope induced stresses did not have any significant effect on the amount of increased cohesion of H. persicum. The findings served to develop knowledge about biotechnical properties of H. persicum root system that can assist in assessing the efficiency of afforestation and restoration measures for erosion control in arid lands.

Spatio-temporal Distributions of Tropospheric NO_2 over Oases in Taklimakan Desert, China

Soil biogenic NO emission is one of the most important sources of atmospheric nitrogen oxides(NOx) worldwide. However, the estimation of soil source, especially in arid areas presents large uncertainties because of the substantial lack of measurements. In this study, we selected the Ruoqiang oases on the southeastern edge of the Taklimakan Desert, China as the study area and applied Ozone Monitoring Instrument(OMI) NO2 retrievals(DOMINO v2.0, 2005–2011) to investigate the spatial distribution and seasonal variations in tropospheric NO2 vertical column density(VCD). High NO2 VCDs were observed over the oases(farmlands and natural vegetation), with the highest value obtained during summer, and lowest during winter. Pulses were observed during spring. We conducted in-situ measurements in June 2011 in Milan oasis and employed ground-based multi-axis differential optical absorption spectroscopy(MAX-DOAS) instruments to validate satellite NO2 retrievals. The findings are as follows: 1) in the study area soil biogenic NO emission is the dominant source of tropospheric NO2; 2) oases(farmlands) are hotspots of tropospheric NO2, and a higher increase in tropospheric NO2 is found in oases from winter to summer; and 3) enhancement of soil biogenic NO emission due to soil managements is predictable. Given the rapid agricultural development in the southern Uygur Autonomous Region of Xinjiang, researches on soil biogenic NO emission and increase in tropospheric NOx should be given more importance.

江河源冻土区土壤碳氮空间分布特征及其影响因素

江河源区是我国高寒生态安全屏障的重要区域,冻土的长期存在使其形成低温冻结环境,弱化了土壤微生物活性,抑制了土壤有机质的矿化过程,因而其近地表浅层土壤碳氮含量高。然而,土壤碳氮含量对不同冻土分区和环境因素响应的空间分异规律尚不清楚。为此,针对江河源4个不同冻土区(季节冻土区、岛状多年冻土区、不连续多年冻土区、片状连续多年冻土区)共11个样点进行植被样方调查、土壤分层采样。在分析碳氮含量的基础上,探讨了年均地温(MAGT)、活动层厚度(ALT)、海拔(ASL)、土壤深度(SD)、植被特征及土壤pH对土壤有机碳(SOC)、全氮(TN)、碳氮比(C/N)的影响。结果表明:(1)SOC、TN、C/N在片状连续多年冻土区最高,在季节冻土区最低,且与年均地温负相关,和海拔正相关;(2)江河源区SOC、TN、C/N随土壤深度的增加而降低,自表层至40cm深度整体下降幅度分别为58.45%、36.96%、17.01%;(3)SOC、TN、C/N与植被覆盖度(FVC)显著正相关(P≤0.05),与土壤pH值显著负相关(P≤0.01);(4)冗余分析表明,土壤pH、MAGT、ALT、SD、FVC是影响江河源区SOC、TN、C/N空间分布的关键因素。研究结果可为厘清气候趋暖条件下江河源区土壤碳氮空间分异规律及多年冻土热稳定性对土壤碳氮排放的影响提供科学基础,同时也有助于预测多年冻土区土壤碳氮空间变化。

水氮管理对黑土稻作土壤碳氮磷化学计量特征的影响

为阐明不同水氮管理模式对黑土稻作产量和土壤碳氮磷化学计量特征的影响,设置3种灌溉模式(常规淹灌、浅湿灌溉、控制灌溉)和4个氮肥梯度(0、85、110、135 kg/hm^(2)),探究了水稻产量、土壤碳氮磷含量及其化学计量比和层化率对不同水氮管理模式的响应规律。结果表明:与常规淹灌和浅湿灌溉相比,控制灌溉模式下,水稻通过形成足量大穗提高库容,小幅增加结实率,从而显著提高产量(P<0.05)。稻田土壤有机碳(SOC)、全氮(STN)、全磷(STP)含量随土层深度增加而降低,施氮处理可显著提升SOC、STN含量并降低STP含量(P<0.05)。与浅湿灌溉和控制灌溉相比,常规淹灌模式增加SOC、STN含量,而与常规淹灌和浅湿灌溉相比,控制灌溉模式增加STP含量。土壤C/N随施氮量增加而降低,土壤C/P、N/P随施氮量增加而升高,施氮能提升不同土层平均C/N层化率,降低C/P、N/P层化率。相比常规淹灌,控制灌溉模式能提升不同土层SOC、STP含量层化率,在一定程度上说明控制灌溉模式下配施适宜氮肥可以改善土壤质量。综合考虑,本研究中控制灌溉模式配施110 kg/hm^(2)氮肥为最优水氮管理方式。

基于BP神经网络的原状土阻尼比智能预测法

为探究原状土阻尼比D随剪应变γ和土层深度H(上覆压力σ′_(m))的双向维度特征,本文对同一钻孔自地表至基岩深度范围内原状粉质黏土与粉土开展系列共振柱试验。利用BP神经网络技术深度挖掘、识别、学习原状土D的双向维度耦合规律,建立了D智能预测法。通过预测结果与试验数据的比较,得出基于BP神经网络的智能预测法可较好地适用于原状土D的双向维度特征预测。试验表明:原状土D与γ和H(σ′_(m))2个维度存在耦合相关。同一H(σ′_(m))维度时,D随γ增加呈现非线性上升规律;同一γ维度时,D随H(σ′_(m))增加呈现相反的降低规律;随着H(σ′_(m))维度的增加,D~γ整体非线性关系逐渐下倾伴随着增长速率逐级变缓。本文方法实现了原状土D在H(σ′_(m))和γ双向维度下的智能预测。

橡胶水泥土动剪模量和阻尼比共振柱试验研究

橡胶水泥土作为一种经济环保的耐腐蚀轻质填筑材料,在沿海港口工程及灯塔等基础建设中具有广泛的应用前景。基于共振柱试验,对不同橡胶掺量、水泥掺量和围压下橡胶水泥土动力特性展开研究,重点探究各影响因素对其动剪模量和阻尼比的影响规律。结果表明:固结压力下橡胶水泥土的累计轴向应变随着橡胶掺量和围压的增大而增大,随水泥掺量增大而减小;橡胶水泥土动剪模量曲线衰减程度随橡胶掺量的增加和水泥掺量的减小而减弱,非线性特征减弱,而受围压影响则较小;最大动剪模量随着橡胶掺量的增大而减小,随水泥掺量和围压的增大而增大。当橡胶掺量较低或水泥掺量较高时,其掺量改变对最大动剪模量影响最大;橡胶的掺入减缓了动剪模量衰减幅度,并且在较低围压下促使其更早地发生衰减。而水泥掺量的减小和围压的增大则会推迟衰减,衰减幅度也相对更大;阻尼比随动剪应变的增加而单调递增,增大橡胶掺量和减小围压会使其阻尼比增大,当水泥掺量小于15%时,阻尼比随水泥掺量增加而增大,而当水泥掺量大于15%时,阻尼比反而随之降低。

基于共振柱试验的堆积层滑坡滑带土动力特性研究

动剪切模量和阻尼比是描述土体动力特性的两个关键参数。为研究堆积层滑坡滑带土的动力特性,开展不同剪应变、含水率及围压下滑带土的共振柱试验,来研究动剪切模量与阻尼比随动剪应变的变化规律,并利用Hardin-Drnevich模型对滑带土的动力特性参数进行拟合,得到了最大动剪切模量、动剪切模量比、阻尼比试验曲线以及动力本构模型拟合参数。研究结果表明:含水率和围压是影响滑带土最大动剪切模量的两大关键因素,相同含水率条件下,最大动剪切模量随围压的增大而增大。低围压条件下,最大动剪切模量随含水率的增大而降低,且各级含水率下动剪切模量与动剪应变近似呈现线性关系,围压较高时,随着动剪应变的增加,动剪切模量的减小速度明显加快,且线性关系有所减弱。通过试验获取了不同含水率及围压条件下滑带土的动模量和阻尼比衰减曲线。基于实验数据进行回归拟合,得出了Hardin-Drnevich模型参数。为了评估滑带土的力学特性,将这些参数与袁晓铭所建议的一般黏土曲线进行了对比分析。结果显示滑带土的动剪切模量比要低于一般黏土的平均值,阻尼比大部分数据处于一般黏土的平均值。试验成果可为该类滑坡的动力稳定性分析及滑坡防治提供参考。

花岗岩山坡A-C结构土壤下典型植被优先流发育特征研究

土石山区A-C结构土壤条件下土薄石多,不同植被条件下优先流发育的是否受到土壤厚度、石砾含量的影响尚不明确。本研究利用染色示踪法与图像处理技术,对鲁中南花岗岩山坡2种土层厚度条件下的黑松林、刺槐林(土层厚度约为40 cm)和板栗林(土壤厚度约为80 cm)优先流染色剖面分布特征及其影响因素进行研究。结果表明,3种植被覆盖下基质流发育深度和最大入渗深度非均匀系数差异不显著(P>0.05),但土层较厚的板栗林最大入渗深度、优先流比、长度指数均明显较高(P<0.05),因此土层较厚条件下优先流发育程度较高。根长密度、土壤容重、总孔隙度、非毛管孔隙度、石砾含量,是影响各植被条件下优先流路径选择的重要因素,但土壤物理性质和根系的剖面分布变化是影响不同植被条件下优先流发育差异的关键因素。研究结果有助于进一步揭示土石山区优先流产流机制。

大兴安岭寒温带森林演替过程中土壤碳氮磷含量及生态化学计量特征

通过研究森林演替过程中土壤碳氮磷含量的变化特征及其化学计量比,分析在0~200 cm土层中,不同演替阶段土壤有机碳氮磷含量的变化情况。选择黑龙江漠河森林生态系统国家级定位观测研究站森林演替过程中3个典型阶段的代表群落,即兴安落叶松林、落叶松-白桦混交林和白桦林为研究对象,分别对其碳氮磷含量分析。结果表明,在演替前期(白桦林)的土壤中,C含量范围为5.78~28.29 g/kg,N含量为0.243~1.232 g/kg,P含量为0.243~1.232 g/kg。演替中期(落叶松-白桦混交林)C含量为6.39~29.41g/kg,N含量为0.077~1.472 g/kg,P含量为0.41~1.374 g/kg。而在演替后期(兴安落叶松林)的土壤中,C含量范围为6.36~34.61g/kg,N含量范围为0.353~1.463 g/kg,P含量范围为0.353~1.463 g/kg。不同林型的土壤C、N、P化学计量比也存在差异。在0~90 cm土层中,前期的C∶N范围为4.15~11.13,后期为5.92~21.85,中期为5.58~23.24。在90~200 cm土层中,前期的C∶N范围为7.46~19.8,后期为4.56~13.09,中期为5.88~18.07。在50~200 cm土层中,前期的C∶P为4.02~9.11,后期为2.24~10.51,中期为3.32~10.76。在0~200 cm土层中,前期的N∶P范围为0.51~2.95,后期为0.28~1.61,中期为0.36~2.13。通过分析显示,森林演替过程中土壤碳氮磷含量及其化学计量比存在一定的变化规律,了解这些变化规律有助于更好地评估森林生态系统营养循环和土壤质量的变化,为森林管理和保护提供科学依据。

大港油田埕海海洋土动剪切模量与阻尼比试验研究

大港油田埕海区块是我国渤海湾海洋油气的重要产区,位于渤海湾西部沿海,属于地震高发区,因此,在该海域进行海洋工程设计建造时,必须根据工程场地的动剪切模量和阻尼比等动力学参数进行地震安全性评价。采用共振柱试验仪对大港埕海海域0~120 m不同深度的海洋土土样进行土体动参数测试与研究。研究发现埕海海洋土动剪切模量随着动剪应变的增大而降低、阻尼比随着动剪应变的增大而增大,同时发现围压与动剪切模量、阻尼比近似成线性关系等规律。相关研究成果可为海洋工程场地的设计、施工及抗震分析提供技术参考依据。

宁夏引黄灌区盐渍化土壤在改良剂作用下的水力特性试验

为了研究宁夏引黄灌区盐渍化土壤在施加有机改良剂和无机改良剂后的水力特性,选取宁夏引黄灌区典型区域进行土壤改良并进行种植试验。将改良后的土壤分5层取样在实验室中进行土柱入渗试验,利用压力膜仪和自循环达西渗流试验仪,测量了土壤含水率与压力水头之间的关系和渗透系数;根据实测数据,选取van Genuchten(VG)模型进行参数反演,对不同改良剂处理后各层土壤水分特征曲线进行了对比分析。研究发现:(1)各层土壤在水吸力相同时,施加不同改良剂后的土壤含水率一般大于对照组,而有机改良剂处理组要大于无机改良剂处理组;(2)改良后水分特征曲线及相应VG模型中的参数发生了较大变化;(3)有机改良剂处理后土壤容重有所减小,而无机改良剂处理后土壤容重变化不太明显;(4)不同改良剂处理后土柱中水分入渗的湿润锋推进速度和土壤渗透系数有不同程度增大,有机改良剂处理组增大幅度大于无机改良剂处理组。综上所述,不同改良剂对土壤容重、含水率、水分入渗速度及其他水力参数都有较大影响,说明改良剂在一定程度上改变了土壤结构。土柱试验及种植试验均表明,有机改良剂(牛粪和糠醛渣)处理组的性态要优于无机改良剂(脱硫石膏和粉煤灰)处理组。

饱和土体渗透系数与孔径关系初探

土体渗透系数是研究土体固结沉降、渗透变形、溶质运移等众多工程地质和岩土工程问题的关键参数。经典的土体渗透系数预测模型通常是利用土体渗透系数与孔隙比或粒径间的关系来预测,这些模型往往可以较好地预测单一土体的土体渗透系数,但一般不具备普适性。通过大量的试验数据分析,指出传统的土体渗透系数预测模型不具备普适性的原因,明晰孔径特征而非孔隙比或者粒径是决定土体渗透系数的关键因素,并基于Kozeny-Carman方程,建立土体渗透系数与孔径的关系模型。该模型对于粗颗粒土和细颗粒土都具适用性,且预测精度在1个数量级内。研究结果加深了对多孔介质渗透特性的认识,并为土体渗透系数预测模型的构建提供了新的思路。

西湾露天煤矿采区转向方案研究

采区接续转向方式不仅影响露天煤矿生产稳定及剥采比均衡,而且是影响露天煤矿生产组织管理及生产成本的重要因素。国家能源集团陕西神延煤炭有限责任公司西湾露天煤矿(以下简称“西湾露天煤矿”)面临着首采区开采到界及产能核增的生产影响,为了解决由此产生的生产接续及采区转向问题,基于西湾露天煤矿开采条件与开发现状,在西湾露天煤矿优化原采区划分的基础上提出采区划分及重新拉沟、扇形转向、L型推进3种转向方案,对比分析了各种采区转向方案生产能力、均衡剥采比、排土规划等方面的影响,并综合优选最佳采区转向方案。研究结果表明,L型推进方案均衡期数最少,重新拉沟方案剥采比极小值最小,扇形转向方案平均剥采比最小;在农田征地且方家畔尾坑可利用排土时,推荐采用重新拉沟方案,在首采区农田征地问题不能解决时,建议采取L型推进方案。