Liquefaction susceptibility and deformation characteristics of saturated coral sandy soils subjected to cyclic loadings-a critical review

Coral sandy soils widely exist in coral island reefs and seashores in tropical and subtropical regions.Due to the unique marine depositional environment of coral sandy soils,the engineering characteristics and responses of these soils subjected to monotonic and cyclic loadings have been a subject of intense interest among the geotechnical and earthquake engineering communities.This paper critically reviews the progress of experimental investigations on the undrained behavior of coral sandy soils under monotonic and cyclic loadings over the last three decades.The focus of coverage includes the contractive-dilative behavior,the pattern of excess pore-water pressure(EPWP)generation and the liquefaction mechanism and liquefaction resistance,the small-strain shear modulus and strain-dependent shear modulus and damping,the cyclic softening feature,and the anisotropic characteristics of undrained responses of saturated coral sandy soils.In particular,the advances made in the past decades are reviewed from the following aspects:(1)the characterization of factors that impact the mechanism and patterns of EPWP build-up;(2)the identification of liquefaction triggering in terms of the apparent viscosity and the average flow coefficient;(3)the establishment of the invariable form of strain-based,stress-based,or energy-based EPWP ratio formulas and the unique relationship between the new proxy of liquefaction resistance and the number of cycles required to reach liquefaction;(4)the establishment of the invariable form of the predictive formulas of small strain modulus and strain-dependent shear modulus;and(5)the investigation on the effects of stress-induced anisotropy on liquefaction susceptibility and dynamic deformation characteristics.Insights gained through the critical review of these advances in the past decades offer a perspective for future research to further resolve the fundamental issues concerning the liquefaction mechanism and responses of coral sandy sites subjected to cyclic loadings associated with seismic events in marine environments.

Prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum

This study focuses on the analytical prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum considering the volumetric deformation modes of the soil above the tunnel crown.A series of numerical analyses is performed to examine the effects of cover depth ratio(C/D),tunnel volume loss rate(h t)and volumetric block proportion(VBP)on the characteristics of subsurface settle-ment trough and soil volume loss.Considering the ground loss variation with depth,three modes are deduced from the volumetric deformation responses of the soil above the tunnel crown.Then,analytical solutions to predict subsurface settlement for each mode are presented using stochastic medium theory.The influences of C/D,h t and VBP on the key parameters(i.e.B and N)in the analytical expressions are discussed to determine the fitting formulae of B and N.Finally,the proposed analytical solutions are validated by the comparisons with the results of model test and numerical simulation.Results show that the fitting formulae provide a convenient and reliable way to evaluate the key parameters.Besides,the analytical solutions are reasonable and available in predicting the subsurface settlement induced by shield tunnelling in sandy cobble stratum.

Experimental and numerical investigation on alternatives to sandy gravel

The NATO agreement STANAG 4569 defines the protection levels for the occupants of logistic and light armored vehicle.The Allied Engineering Publication,AEP-55,Volume 2 document outlines the test conditions for underbelly improvised explosive device(IEDs),which must be buried in water-saturated sandy gravel.The use of sandy gravel has some drawbacks,for instance reproducibility,time consumption,and cost.This paper focuses on the investigation of four alternatives to sandy gravel,which could produce similar specific and cumulative impulses:a concrete pot filled with water,a concrete pot filled with quartz sand,a steel pot without filling and a concrete pot filled with glass spheres(diameter 200μm—300μm)and different water contents.The impulses are measured with a ring technology developed at the Fraunhofer EMI.A numerical soil model based on the work of Marrs,2014 and Fi serov a,2006 and considering the soil moisture was used to simulate the experiments with glass spheres at different water contents,showing much better agreement with the experiments than the classical Laine&Sandvik model,even for high saturation levels.These results can be used to create new test conditions at original scale that are more cost-effective,more reproducible and simpler to manage in comparison to the current tests carried out with STANAG sandy gravel.

Ecological effect of the plantation of Sabina vulgaris in the Mu Us Sandy Land,China

Vegetation restoration through artificial plantation is an effective method to combat desertification,especially in arid and semi-arid areas.This study aimed to explore the ecological effect of the plantation of Sabina vulgaris on soil physical and chemical properties on the southeastern fringe of the Mu Us Sandy Land,China.We collected soil samples from five depth layers(0-20,20-40,40-60,60-80,and 80-100 cm)in the S.vulgaris plantation plots across four plantation ages(4,7,10,and 16 years)in November 2019,and assessed soil physical(soil bulk density,soil porosity,and soil particle size)and chemical(soil organic carbon(SOC),total nitrogen(TN),available nitrogen(AN),available phosphorus(AP),available potassium(AK),cation-exchange capacity(CEC),salinity,p H,and C/N ratio)properties.The results indicated that the soil predominantly consisted of sand particles(94.27%-99.67%),with the remainder being silt and clay.As plantation age increased,silt and very fine sand contents progressively rose.After 16 years of planting,there was a marked reduction in the mean soil particle size.The initial soil fertility was low and declined from 4 to 10 years of planting before witnessing an improvement.Significant positive correlations were observed for the clay,silt,and very fine sand(mean diameter of 0.000-0.100 mm)with SOC,AK,and p H.In contrast,fine sand and medium sand(mean diameter of 0.100-0.500 mm)showed significant negative correlations with these indicators.Our findings ascertain that the plantation of S.vulgaris requires 10 years to effectively act as a windbreak and contribute to sand fixation,and needs 16 years to improve soil physical and chemical properties.Importantly,these improvements were found to be highly beneficial for vegetation restoration in arid and semi-arid areas.This research can offer valuable insights for the protection and restoration of the vegetation ecosystem in the sandy lands in China.

Did Species and Functional Diversities of Sandy Intertidal Marine Nematodes Reveal Similar Response to Environmental Changes?

Free living marine nematodes were sampled from two sandy beaches in Dalian City,in December of 2015,and April,July,and October of 2016.The spatial and seasonal variations of marine nematode species diversity(based on species abundance dataset)and functional diversity(based on functional traits dataset:feeding types and life history strategies)were investigated to understand the environmental drivers and how they respond to specific environmental variations.Sediment granularity was revealed to be the main environmental factor causing spatial differences in nematode diversity indices between the two beaches.Species diversity indices,namely species number,Margalef index,Shannon-Wiener diversity index(H’),were higher in fine-grained sediments,while the functional diversity indices,including functional evenness,functional dispersion,and Rao’s quadratic entropy index(RaoQ),were higher in coarse-grained sediments.Nematode species diversity indices also fluctuated with seasonal variations of temperature,dissolved oxygen,pH,salinity,and sediment chlorophyll-a within the study beaches.However,functional diversity indices did not show significant seasonal variations and exhibited weak correlation with the studied environmental variables.Overall,the functional diversity indices were negatively correlated with the species diversity indices,suggesting an inconsistent response to environmental changes.A decrease in nematode species diversity in coarse sands,accompanied by an increase in functional diversity,can be regarded as an early warning signal of environment disturbance.If more biological traits are involved in calculating functional diversity indices,it will be helpful for the future study of the internal connections of species diversity and functional diversity.

Spatiotemporal variations in ecological quality of Otindag Sandy Land based on a new modified remote sensing ecological index

Otindag Sandy Land in China is an important ecological barrier to Beijing;the changes in its ecological quality are major concerns for sustainable development and planning of this area.Based on principal component analysis and path analysis,we first generated a modified remote sensing ecological index(MRSEI)coupled with satellite and ground observational data during 2001–2020 that integrated four local indicators(greenness,wetness,and heatness that reflect vegetation status,water,and heat conditions,respectively,as well as soil erosion).Then,we assessed the ecological quality in Otindag Sandy Land during 2001–2020 based on the MRSEI at different time scales(i.e.,the whole year,growing season,and non-growing season).MRSEI generally increased with an upward rate of 0.006/a during 2001–2020,with clear seasonal and spatial variations.Ecological quality was significantly improved in most regions of Otindag Sandy Land but degraded in the southern part.Regions with ecological degradation expanded to 18.64%of the total area in the non-growing season.The area with the worst grade of MRSEI shrunk by 15.83%of the total area from 2001 to 2020,while the area with the best grade of MRSEI increased by 9.77%of the total area.The temporal heterogeneity of ecological conditions indicated that the improvement process of ecological quality in the growing season may be interrupted or deteriorated in the following non-growing season.The implementation of ecological restoration measures in Otindag Sandy Land should not ignore the seasonal characteristics and spatial heterogeneity of local ecological quality.The results can explore the effectiveness of ecological restoration and provide scientific guides on sustainable development measures for drylands.

Tissue Microstructure Estimation of SANDI Based on Deep Network

Diffusion magnetic resonance imaging(dMRI)is a noninvasive method to capture the anisotropic pattern of water displacement in the neuronal tissue.The soma and neurite density imaging(SANDI)model introduced soma size and density to biophysical model for the first time.In addition to neurite density,it can achieve their joint estimation non-invasively using dMRI.In the traditional method,parameters of the SANDI are estimated in a maximum likelihood frame-work,where the nonlinear model fitting is computationally intensive.Also,the present methods require a large number of diffusion gradients.Efficient and accurate algorithms for tissue microstructure estimation of SANDI is still a challenge currently.Consequently,we introduce deep learning method for tissue microstructure estimation of the SANDI model.The model comprises two functional components.The first component produces the sparse representation of diffusion sig-nals of input patches.The second component computes tissue microstructure from the sparse repre-sentation given by the first component.The deep network can produce not only tissue microstruc-ture estimates but also the uncertainty of the estimates with a reduced number of diffusion gradi-ents.Then,multiple deep networks are trained and their results are fused for the final prediction of tissue microstructure and uncertainty quantification.The deep network was evaluated on the MGH Connectome Diffusion Microstructure Dataset.Results indicate that our approach outperforms the traditional methods in terms of estimation accuracy.

海南岛文昌现代红色沙质土壤的主量元素分析结果与意义

对海南岛东北部文昌坑尾园风成砂物质基础上发育的现代“红色沙壤”中SiO_(2)、Al_(2)O_(3)、TOFE、CaO、Na_(2)O、K_(2)O、MgO这7种主量元素的研究发现:现代红色沙壤土中SiO_(2)含量最高,MgO含量最低;CIA分别与Saf和ba存在负相关关系且剖面上下部数据变化符合土壤自剖面底到顶风化程度变弱的规律;坑尾园剖面高CIA值,与该地所处的热湿环境相关。在此环境下,水土流失带来元素迁移,使得除SiO_(2)外的6种元素值均因减少而处于低值状态。

基于储层甜点特征的致密砂砾岩油气藏压裂增产技术研究

中拐凸起南斜坡二叠系佳木河组二段储层为一套含浊沸石的致密砂砾岩。早期,在有利构造上钻探的直井产量均较低,2014年钻探该区第一口水平井用于提产,但因未能有效控制缝高,致深部水体锥进过快,长期试采效果差。近年来,地震地质综合研究发现,储层存在局部甜点。因下部并无隔层,压裂时需严格控制裂缝下延。通过对储层甜点特征进行梳理,综合评价了各断块甜点的优质程度,为试油段优选和新井的部署提供依据。为了实现控缝高压裂,提高单井产量和试采效果,开展人工隔层导流能力室内实验、完成人工隔层支撑剂粒径的优选,进行压裂数值模拟研究、确定了研究区形成有效厚度人工隔板的临界施工参数。研究认为,前置液阶段,改变液体黏度和排量、铺置有效人工隔层能够抑制水力裂缝向下扩展;携砂液阶段,加入一定浓度纤维,可进一步提升支撑剂对上部优质储层的支撑。这种组合控缝高工艺技术投入该区压裂实施后,有效控制了裂缝下延高度,甜点层段得到充分改造,试油及后续试采期间维持了较高油气产能,压裂提产效果明显。

毛乌素沙地包气带气态水同位素特征及其运移规律

为揭示包气带气态水在大气、土壤和地下水之间交换对内部水与能量传递的响应,该研究应用原位监测、同位素示踪与数值分析相结合的方法,对毛乌素沙地包气带气态水时空变化特征与运移规律进行分析。结果表明,受大气水汽来源和局地循环影响,降水δD_(L)和δ^(18)OL值均表现出春夏富集、秋冬贫化。各深度土壤气态水δ^(18)O_(a)与液态水δ^(18)OL值呈显著正相关(P<0.01),但在季节上,春夏季为极显著线性正相关(P<0.01),而秋冬季则无显著相关性(P=0.12)。表层水汽通量的增大伴随δ^(18)O_(a)富集,而水汽密度夏季的增大和冬季的减小均表现出表层δ^(18)O_(a)富集,夏季蒸发比冬季冻结更能引起表层土壤δ^(18)O_(a)富集。受包气带温度梯度驱动影响,夏季土壤深部气态水接受浅层水汽补给,冬季浅层接受中深层水汽的补给,而春、秋季剖面分别存在温度聚合和发散零通量面,使得补给关系复杂。该研究明确了土壤δ^(18)O_(a)的变化受水汽迁移模式、大气蒸发能力和土壤冻融的共同控制,表层δ^(18)O_(a)的富集在冬季受蒸发与向上的水汽传输共同影响,而夏季主要受土壤水的昼夜蒸发与凝结循环作用所致,该结果为厘清土壤水汽迁移机制以及进一步阐明包气带水循环过程提供科学依据。

基于希尔伯特-黄变换与小波分析的降雨序列多时间尺度研究

[目的]对比分析不同方法在多尺度周期计算性能方面的差异,为区域水文周期分析方法的选择提供更多参考。[方法]利用2组已知周期和趋势特征的人工序列,对基于多元经验模态分解(Multivariate Empirical Mode Decomposition,MEMD)改进的希尔伯特—黄变换(Hilbert-Huang Transform,HHT)与小波分析在多尺度周期计算性能差异上进行了测试、对比与分析;并在此基础上,使用改进的HHT(后称HHT)进一步分析了毛乌素沙地11个站点39年降雨序列的多时间尺度特征。[结果]对于人工序列,小波分析(对称延拓)结果偏大,与预设周期存在显著差异(Sig.=0.003<0.05);而HHT和小波分析(周期延拓)的周期结果与预设周期没有显著差异,且HHT精度(Sig.=0.142>0.05)要略高于周期延拓小波(Sig.=0.109>0.05)。对于实测降雨序列,HHT显示毛乌素沙地的降雨主周期存在明显区域差异:腹地站点降雨主周期为5.5 a,而边缘站点为2.7~3.3 a;分解后的残差分量表明了沙地降雨在时间上呈上升趋势,而空间上呈现由东到西逐渐减少的分布状态。[结论]HHT因其自适应性,无需考虑众多参数的选取,在保持精度的同时可以提取更多水文信息,在区域降雨序列多尺度分析上更具优势,因此具有重要的实际应用价值。

基于连续观测数据的毛乌素沙地生长季土壤水分动态及其对降雨的响应

水分是制约半干旱区沙地植物生长发育和生态建设的关键非生物因子。于2008—2010年和2018—2021年生长季(4—10月)对毛乌素沙地流动、半固定和固定沙地0~100cm深土壤水分进行了连续观测,系统分析了不同固定程度沙地土壤水分动态变化规律及其对降雨的响应。结果表明:(1)受降雨季节变化的影响,流动、半固定和固定沙地不同深度土壤水分季节变化一般呈∽型或双峰型,10 cm和30 cm深土壤水分含量波动较大,60 cm和100 cm深土壤水分含量波动较小。(2)3种固定程度沙地生长季土壤水分动态差异明显,总体来看,流动沙地土壤水分状况最好,且土壤水分含量变化相对平缓,固定沙地土壤水分状况最差,且土壤水分含量变化最为剧烈,半固定沙地居于二者之间;固定沙地10~30cm深土壤水分状况好于半固定沙地和流动沙地,30~100cm深土壤水分状况则相反。(3)降雨格局是形成土壤水分时空格局的主要原因,随降雨事件降雨量增加,降雨的入渗深度逐渐增加;但是固定沙地土壤水分的深层补充需较强的降雨和较长的时间。生长季降雨事件以小降雨事件为主,表层土壤水分波动更剧烈。生长季初期降雨较少且以小降雨事件为主,10cm以下土壤水分补充困难,土壤水分状况较差。流动沙地和半固定沙地10~30cm深土壤水分状况好于30~100cm深土壤,而固定沙地土壤水分状况则相反。研究结果可为半干旱区沙化土地近自然植被恢复与固沙植被稳定性维持提供科学依据。

地下水位变化对砂土地层地铁隧道沉降影响试验研究

为考察地铁运营后列车载荷和地下水对隧道造成的影响,对某砂性土地层城市中某一地铁盾构隧道区段运营6年间的沉降变形进行实测观察;根据实测所得沉降规律,设计并开展缩尺模型试验,研究车致振动条件下因地下水位变化产生的隧道沉降规律。结果表明:随着时间推移,隧道各测点所得数据呈现一定的周期性上升与下降变化趋势,前2年隧道总体上浮,之后略有沉降,第3年后虽有波动但基本未发生进一步沉降,第6年后隧道最大沉降不超过3 mm;砂性土地层中,地下水位变化会造成重塑土层内部应力变化,且振动荷载会导致土体颗粒结构重新调整至密实,易导致隧道发生沉降,因此不能忽视地铁周围施工降水给隧道带来的不利影响;土体振密及因地下水产生的浮力共同作用,导致隧道的上浮及沉降。相比于软土地层,砂性土地层中盾构隧道的沉降速率明显更低且沉降基本稳定时间更短,2种地层下的沉降规律、影响因素完全不同,各地层下的沉降分析理论亦无法相互适用。

内河中游区大型沉管隧道建造关键新技术——以襄阳鱼梁洲隧道为例

为解决内河中游区沉管隧道建造面临的河床冲刷强、强透水地层深厚、防洪要求高等问题,依托襄阳鱼梁洲沉管隧道工程,通过工程调研、理论分析、物模试验、数值模拟、现场测试等手段,对内河沉管隧道建造关键技术进行创新及应用,首次形成如下创新成果:1)提出沉管隧道冲刷安全量化评价方法,给出沉管结构横向稳定性安全系数等5项评价指标及其评价标准体系,填补了沉管隧道防冲安全量化评价方法的空白;2)研发利用管周摩擦力抵抗止水带回弹力的摩擦止推型最终接头,解决常规陆域接头需设置大型圬工结构的问题;3)研发并量产可满足0.3 MPa外水压水密性、100年设计使用寿命的沉管接头外侧止水带国产化产品,其百年应力松弛衰减率仅25.5%,预测使用寿命144年,使中国实现沉管隧道全产业链技术的国产化;4)提出整体式管节不设后浇带全断面顺浇预制工法,实现沉管结构预制工效提高52%、结构接缝减少61%、浇筑裂缝减少60%;5)在内河沉管隧道中采用先铺卵石垫层基础,并研发出全浮式高精度先铺卵石基床整平船;6)研发应用沉管无焊接装配式端封门和柔性水袋压载水系统,可实现舾装设施的便捷循环使用和施工效率的提升。

渤海海域辽中凹陷南部古近系东营组三段重力流砂岩优质储层特征及成因

为解决渤海海域中-深层重力流砂岩储层物性差异大、优质储层预测较难的勘探难题,基于常规物性、铸体薄片、黏土矿物和地球化学等分析测试手段,结合测井、录井、岩心和地震等资料,研究了渤海海域辽中凹陷古近系东营组三段(东三段)深水重力流砂岩储层的沉积特征及优质储层主控因素。结果表明:渤海海域辽中凹陷东三段重力流的沉积类型为砂质碎屑流,储层以中-低孔、中-低渗为主。储集空间中的粒间溶蚀孔最发育,原生孔次之。中砂岩和粗砂岩储层物性最好,细砂岩次之,粉砂岩较差。控制优质储层发育的关键因素是:(1)物质基础好,表现为分选好、泥质含量低、富含长石。(2)东营组早成岩期的快速沉降形成欠压实超压条件,使原生孔隙得以大量保存;超压延长了有机酸的生成时间,为砂岩中的钾长石和方解石等矿物溶解提供了充足的酸性流体。(3)断层沟通了储层和烃源岩,进一步促进了中-深层储层的溶解作用,有利于大量溶蚀孔的形成。(4)构造抬升和侧向挤压造成的储层破裂作用又形成了大量裂缝和溶缝带,改善了储层物性。

富水砂卵石地层盆形冻结止水技术研究

为解决全断面砂卵石地层地下工程的地下水控制问题,提出盆形冻结止水技术。首先,采用三轴力学试验研究冻结砂卵石的压缩力学特性和蠕变力学特性;然后,采用大尺度物理模型试验和数值模拟方法研究盆形冻结的温度场扩展规律,并根据研究结果进一步提出盆形冻结积极冻结期的群孔布置技术和维护冻结期的精细化控制技术。结果表明:1)低围压(小于3 MPa)条件下,三轴抗压强度与围压呈正线性相关,然后围压继续增大时,强度基本不变;基于损伤理论建立冻结砂卵石全过程蠕变模型。2)荷载对冻胀率及融沉系数影响最大,细粒土质量分数次之,原状饱和砂卵石是不冻胀材料,并由此建立饱和砂卵石冻胀率及融沉系数三维预测模型。3)基于大型物理模型试验及数值模拟结果,盆形冻结可以在地下水渗流条件下形成完整的盆形结构,起到有效止水的效果。4)盆底冻结管在冻结过程中表现出与单管冻结迥异的“群孔效应”,根据试验结果提出包含冻结管间距、土体导热系数、渗流速度3因素的积极冻结期冻结管合理间距的确定与布置技术。5)为节约维护冻结期的能源,提出隔排切割冻结管、仅保留盆壁冻结管2种维护形式以对冻结区域进行精细化控制,经过分析,2种方式均可以有效满足盆形结构维护期的冷量供给,保持完整的盆形形态。

断缝体识别及储层发育模式——以准噶尔盆地玛湖凹陷玛东地区百口泉组为例

断缝体是一种新的储集体类型。它是由断层、褶皱所伴生的裂缝与基质孔共同构成,具有立体不规则孔缝特征的构造地质体。断缝体包括断层滑动面、破碎带及诱导缝,既是致密砂砾岩油气藏富集的主要因素,又是钻井风险防控及储层精准改造的关键因素。准噶尔盆地玛湖凹陷玛东地区百口泉组致密砂砾岩储层具有埋深较大、岩性致密、非均质性强、异常压力高、压裂改造难度大等特征,其断缝体刻画成为制约油气效益开发的技术难点。文中以准噶尔盆地玛湖凹陷玛东地区三叠系百口泉组致密砂砾岩储层裂缝为研究对象,在地震、岩心、成像测井等资料分析的基础上,从不同尺度精细描述了裂缝响应特征及断缝体储层发育模式。通过钻井资料及压裂资料分析,断缝体识别方法得到了验证,同时也为油田地质工程一体化效益开发提供了重要的技术支撑。

福建长乐海域水沙环境及海岸演变研究

依托实测水下地形和水文泥沙资料,研究了福建长乐海域水沙环境及海床冲淤演变特征。研究结果表明:福建长乐海域为基岩岬角控制的沙质海岸,波浪较强、潮流流速小、水体含沙量低、海岸线及海床地形长期保持基本稳定状态;研究海域的常风向和常浪向均为NNE向,强风和强浪主要受台风及寒潮大风影响;研究海域属强潮海区,最大潮差为6.92 m,平均潮差为4.45 m;研究海域潮流属正规半日潮流,往复流特征明显;研究海域底质分布在横向上呈现近岸粗、深水区细的分布特点,近岸存在南北连续的砂质沉积带,波浪作用下自北向南输移的泥沙对海岸演变有一定影响。

冲击荷载下含夹层饱和砂土孔压变化规律分析

砂土中夹层的性状会影响饱和砂土孔压发展,从而影响砂土层变形。为研究夹层位置、厚度和种类等不同夹层状态下砂土液化过程中的孔压变化规律,设计了冲击荷载作用下层状砂液化试验,建立了含夹层饱和砂土理论模型,并将试验结果与理论分析进行对比。结果表明:含夹层饱和砂土的孔压发展呈现3个阶段,即快速上升、快速消散、缓慢消散阶段。高渗透性夹层高度越高,其下方土层孔压快速消散时长越短,越快趋于稳定值,但消散总时长无明显影响;低渗透性夹层高度或厚度的增大,均会使夹层上方孔压快速消散阶段速率加快,孔压消散稳定阶段延长,孔压消散总时长随之线性增长;同时,孔隙水会在低渗透性夹层下方形成水膜,夹层高度或厚度的增加均会使水膜持续时间增长,但水膜形态主要受夹层厚度影响。试验结果与理论分析较为一致,说明了试验的可靠性。

科尔沁沙地西北缘生态地质环境评价

采用层次分析法对科尔沁沙地西北缘地质环境、生态环境、社会环境进行分析,构建一套以适应农牧业发展为目标层的评价指标体系,并计算区域生态地质环境质量的综合指数,对生态地质环境状况进行评价.通过对评价结果统计认为:生态环境较比地质环境、社会环境对整个评价结果的影响更大,其中土地质量是最主要因素;研究区所有的评价单元中有86%处于中等及偏下的水平.该研究结果对正确认识研究区生态地质环境具有重要的意义.